Atom species energy dependence on magnetic configurations in the perovskite yttrium orthoferrite

The article represents the results of studying of the influence of atom species in the perovskite multiferroic yttrium orthoferrite YFeO3 on magnetic configurations by ab-initio methods. Four magnetic configurations possible in magnetic sublattice that were formed by iron atoms were analyzed. It is shown that different magnetic orderings change the lattice parameters and the ions occupied positions while preserving symmetry of the unit cell, the lowest state responds G-AFM type magnetic ordering. The lattice parameters are in good relevant published experimental data. The atom species energy dependence shows that the main role in magnetic properties goes to iron and oxygen. In the ground state, magnetic properties relate with Dzyaloshinskii – Moriya interaction, while in other configurations, these relate with superexchange through Fe- O-Fe chains. Obtained results are useful for analyzing and designing straintronics devices. Also, the results can be interesting for interpretation and predicting magnetic properties of partially or fully substituted orthoferrites including substitution on rare-earth elements.

Characterization of an Innovative Detector Based on Scintillating Fiber for Personalized Computed Tomography Dosimetry

For technical and radioprotection reasons, it has become essential to develop new dosimetric tools adapted to the specificities of computed tomography (CT) to ensure precise and efficient dosimetry since the current standards are not suitable for clinical use and for new CT technological evolution. Thanks to its many advantages, plastic scintillating fibers (PSF) is a good candidate for more accurate and personalized real-time dosimetry in computed tomography, and the company Fibermetrix has developed a new device named IVISCAN® based on this technology. In this study, we evaluated performances of IVISCAN® and associated uncertainties in terms of dose-rate dependence, angular dependence, stability with cumulative dose, repeatability, energy dependence, length dependence, and special uniformity in reference and clinical computed tomography beam qualities. For repeatability, the standard deviation is less than 0.039%, and the absolute uncertainty of repeatability lies between 0.017% and 0.025%. The deviation between IVISCAN® and the reference regarding energy dependence is less than 1.88% in clinical use. Dose rate dependence results show a maximum deviation under ±2%. Angular dependence standard deviation σ is 0.8%, and the absolute uncertainty was 1.6%. We observed 1% of variation every 50 Gy steps up to a cumulative dose of 500 Gy. Probe response was found to be independent of the PSF length with a maximum deviation < 2.7% between the IVISCAN® probe and the 1 cm PSF probe. The presented results demonstrated that IVISCAN® performances are in accordance with metrology references and the international standard IEC61674 relative to dosemeters used in X-ray diagnostic imaging and then make it an ideal candidate for real-time dosimetry in CT applications.

Climate Change as a National Security Issue: Examining Framing Effects Across Party

Research suggests that framing climate change as a national security issue can shape opinion about climate change. This research is less clear about what exactly constitutes a “national security frame” and what aspects of this frame are most persuasive. We use a survey experiment to compare the relative effects of three types of national security frames we identify. Results show that a frame centered on energy dependence had the strongest effect and was the most consistent across partisanship. Surprisingly, the effects ran in the opposite direction for Democrats and Republicans on both outcomes—negative for Democrats and positive for Republicans. We also show that the energy dependence frame moderated the influence of respondents’ affect toward political candidates and parties on their climate change attitudes. The results suggest that the energy dependence frame can shape public opinion, but that it must be tailored to particular audiences to avoid backfire effects.

Development of Renewable Energy in Lithuania: Experience, State and Trends

In recent decades, the growing number of citizens and improving life quality have increased energy consumption in the world and Europe, as well as in Lithuania. Despite the fact that an increasing number of countries are focusing on the development of renewable energy, most of the energy is produced by using fossil fuels. As a result, climate change is being felt more than ever before. One of the ways to mitigate climate change is the development of renewable energy sources in the world, Europe and Lithuania. Last year, Lithuania produced 5,142 TWh of electricity, which accounted for 47% of the country’s total electricity consumption, and 22.2% of all electricity consumption was generated using renewable energy sources. According to the Lithuanian National Energy Independence Strategy, 70% of electricity will have to be produced in Lithuania by 2030, reaching 100% by 2050. However, electricity imports and resulting energy dependence are still a major challenge in Lithuania. To address the ambitious goals of eliminating energy dependence and developing climate-neutral technologies, the last decade has seen the focus on the development of renewable energy, and wind energy in particular. Forecasts for the future suggest that by the middle of the century, the country will be producing electricity mainly from renewable sources including onshore and offshore wind energy, large- and small-scale solar energy, and bioenergy systems.

Classification of X-Ray Attenuation Properties of Additive Manufacturing and 3D Printing Materials Using Computed Tomography From 70 to 140 kVp

Additive manufacturing and 3D printing is particularly useful in the production of phantoms for medical imaging applications including determination and optimization of (diagnostic) image quality and dosimetry. Additive manufacturing allows the leap from simple slab and stylized to (pseudo)-anthropomorphic phantoms. This necessitates the use of materials with x-ray attenuation as close as possible to that of the tissues or organs mimicked. X-ray attenuation properties including their energy dependence were determined for 35 printing materials comprising photocured resins and thermoplastic polymers. Prior to measuring x-ray attenuation in CT from 70 to 140 kVp, printing parameters were thoroughly optimized to ensure maximum density avoiding too low attenuation due to microscopic or macroscopic voids. These optimized parameters are made available. CT scanning was performed in a water filled phantom to guarantee defined scan conditions and accurate HU value determination. The spectrum of HU values covered by polymers printed using fused deposition modeling reached from −258 to +1,063 at 120 kVp (−197 to +1,804 at 70 kVp, to −266 to +985 at 140 kVp, respectively). Photocured resins covered 43 to 175 HU at 120 kVp (16–156 at 70, and 57–178 at 140 kVp). At 120 kVp, ASA mimics water almost perfectly (+2 HU). HIPS (−40 HU) is found close to adipose tissue. In all photocurable resins, and 17 printing filaments HU values decreased with increasing beam hardness contrary to soft tissues except adipose tissue making it difficult to mimic water or average soft tissue in phantoms correctly over a range of energies with one single printing material. Filled filaments provided both, the HU range, and an appropriate energy dependence mimicking bone tissues. A filled material with almost constant HU values was identified potentially allowing mimicking soft tissues by reducing density using controlled under-filling. The measurements performed in this study can be used to design phantoms with a wide range of x-ray contrasts, and energy dependence of these contrasts by combining appropriate materials. Data provided on the energy dependence can also be used to correct contrast or contrast to noise ratios from phantom measurements to real tissue contrasts or CNRs.

Smart and Functional Materials for Lithium-Ion Battery

Climate change and energy dependence are nowadays critical issues that the world is facing, requiring effective and urgent actions to properly address them in a timely fashion [...]

Role of inelastic couplings in the 4He + 208Pb elastic scattering in a wide energy range

The phenomenological strengths of the real part of the optical potential, obtained from elastic scattering data analyses within the optical model approach, present significant energy-dependence. This behavior has been associated to the intrinsic energy-dependence of the effective nucleon-nucleon interaction. However, in earlier works, we proposed that at least part of this dependence can arise from the effect of couplings to inelastic states of the nuclei. In order to deepen this study, in this paper we present extensive data analyses for the elastic scattering and inelastic excitation of 111 states of 208Pb, for the 4He + 208Pb system in a wide energy range. With the purpose of comparison, the theoretical cross sections are obtained in different approaches for the imaginary part of the potential, and within both contexts: optical model (distorted wave Born approximation) and coupled-channel calculations.