Structurally and Surface-Modified Alumina Particles as a Reinforcement in Polyester-Based Composites with an Improved Toughness

Mechanics of Composite Materials - Commercial γ ? Al2O3 particles, Al2O3 n, and synthesized Al2O3 doped with iron oxide (Al2O3 Fe) were used as reinforcements to enhance the toughness of...     

Effect of “Sodium Sulfite–Ascorbic Acid” Complex Antioxidant Additive on the Composition,Structure and Semiconducting Properties of PbSe Film

Physics of the Solid State - Comparative experimental data, using dynamic light scattering methods, scanning electron and atomic force microscopy, on the composition, crystal structure,...     

The Influence of the Percolation Transition on the Electric Conductive and Optical Properties of Ultrathin Metallic Films

Physics of the Solid State - The results of the study of the peculiarities of changes in the electrophysical, optical, and plasmonic properties of ultrathin metallic films during the percolation...     

Propagation of Low-Energy Electrons and the Density of Unoccupied States in Ultrathin TCNQ Layers on the Oxidized Silicon Surface

Physics of the Solid State - The formation of unoccupied electronic states and the boundary potential barrier during thermal deposition of tetracyanoquinodimethane (TCNQ) films to 7 nm in thickness...     

The Effect of a Weak Magnetic Field on the Sensitivity of Powdered Pentaammine (5-Nytrotetrazolato-N2) Cobalt(III) Perchlorate of Various Dispersions to the Effects of a High-Current Electron Beam of Nanosecond Duration

Technical Physics - The results of experiments on the influence of a weak magnetic field on the sensitivity of powdered pentaammine (5-nytrotetrazolato-N2) cobalt(III) perchlorate to a high-current...     

“It’s better to forget physics”: The Idea of the Tactical Nuclear Weapon in the Early Cold War

Physics in Perspective - The American physicist John Wheeler once told his colleague Richard Feynman that, in case of war, “it’s better to forget physics and tell the admirals and...     

Mechanistic model for the dielectric spectrum of a simple dielectric material

ABSTRACT

In this paper, we perform molecular dynamics simulations of a dielectric fluidic material composed of permanent molecular dipoles. The dielectric spectrum features two peaks at lower frequencies than the system phonon frequency. The primary peak is observed at all temperatures studied and shifts toward lower frequencies as the temperature decreases. During this shift, the secondary peak emerges with a higher peak frequency than the primary peak. The secondary peak amplitude increases as the temperature decreases. Both peaks are dependent on the wavevector; in the small wavevector regime, the primary peak is shifted to higher frequencies as the wavevector squared and the secondary peak amplitude increases as the wavevector increases, but shows no shift in frequency. From the polarisation balance equation, we propose a model for the dielectric spectrum. This captures the spectrum features, and we conjecture that the primary peak is due to dipole moment correlations (Debye-type) and the secondary peak is due to the correlation between the dipole moment and a microscopic local field.     

Development of a Technique for the Express Assessment of Temperature Fields on the Outlet Window Membrane of the LUE-200 Accelerator

Physics of Particles and Nuclei Letters - A technique has been developed for express estimation of temperature fields using a graded curve, which can be used to justify the reliability and safety...     

Noninvasive Temperature Measurement in Dental Materials Using Nd3+, Yb3+ Doped Nanoparticles Emitting in the Near Infrared Region

In this work, the application of near infrared (NIR)-emitting NaYbF₄:1%Tm³⁺@NaLuF₄:30%Nd³⁺ core–shell nanoparticles is reported for noninvasive probing and monitoring the temperature during photopolymerization of dental materials. When excited at 808 nm, the synthesized nanoparticles emit NIR photoluminescence (PL) with two distinctive peaks at 865 and 980 nm which correspond to radiative transitions from the doped Nd³⁺ and Yb³⁺ ions, respectively. Luminescence intensity ratio between these two bands is found to vary with temperature due to temperature-dependent electronic excitation energy transfer between Nd³⁺ and Yb³⁺ ions at the core/shell interface. This finding allows luminescence ratiometric evaluation of the in situ temperature during photopolymerization of resin cement (doped with nanoparticles) in a veneer placement procedure. In addition, the NIR emission also enables PL imaging of the distribution of the adhesive under the veneer. The results highlight that rare-earth ions–doped nanoparticles with both excitation and emission in the NIR spectral range are advantageous for both PL-based nanothermometry and imaging due to the reduced attenuation of NIR light by dental ceramics.