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•The SNEDDS shows resistance and homogeneity to changes in aqueous volumes, keeping its particle size constant.•The water molecules interact with the interfacial layer of the ...nanoemulsion through hydrogen bonds.•The viscosity of the SNEDDS increases with the concentration of oil due to the increase in the number of drops.•Classical two-phase models of O/W emulsions cannot correctly describe the dielectric properties of SNEDDS.•A model was proposed to describe the dielectric constant of the SNEDDS and to estimate the thickness of the interface layer.
Self-nanoemulsifying Drug Delivery System (SNEDDS) improves the bioavailability of bioactive compounds that exhibit low water solubility. In this regard, our study aims to assess the formulation of SNEDDS in a wide range of oil concentrations (0–8.6 wt%) by dynamic light scattering, FTIR, dielectric measurements, and the characterization of the interface layer and its molecular interactions with water. The proper formulation of SNEDDS accounted for the lipophilic/hydrophilic balance leading to a homogeneous distribution of oil droplets in water with constant sizes of 20–22 nm, which does not depend on oil concentration. Dielectric spectroscopy measurements in the GHz frequency range allowed us to obtain the dependence of relaxation time as a function of oil concentration and its relationship with the viscosity of the nanoemulsion. The classical two-phase model of Hanai, Maxwell-Garnet, Bruggeman, and Lichtenecker fails to describe the dielectric properties of nanoemulsions. Therefore, in this work, a three-phase model is proposed to model the dielectric measurements, which include water as the continuous phase, oil droplets, and interface layer due to using Cremophor EL (HLB = 12–14) and Labrafil M1944CS (HLB = 2–3) as surfactant and co-surfactant. This model fits well with the experimental results and allows us to obtain SNEDDS properties such as the dielectric constant (20.9), volume fraction, and the interface layer thickness (ca. 5 nm). Investigated oil–water nanoemulsions can be a model for developing different drug delivery systems. Additionally, proposed measurements in the GHz frequency range and their interpretation can be generalized for nanoemulsion characterization.
We propose a morphological analysis for searches of extended γ-ray emission associated with dark matter annihilation. Our approach is based on the likelihood analysis including the spatial templates ...produced by taking into account the residual count maps in the energy band where the dark matter annihilation spectrum has a prominent spectral feature. The approach is tested on the example of the possible dark matter annihilation signal from the Virgo cluster of galaxies.
The effect of addition of
J
-aggregates of polymethine dye into the hole-transport layer of an organic light-emitting diode (OLED) on its characteristics and operational stability was studied. ...Water-soluble PEDOT:PSS (poly(3,4-ethylenedioxythiophene)) and the interpolymer complex of polyaniline and poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAn-PAMPSA) were used as the matrices of polymer nanocomposites. The highest efficiency characteristics of the OLEDs with the considered structure were achieved using PAn-PAMPSA at a particular component ratio in the interpolymer complex. Additives of
J
‑aggregates did not significantly affect the efficiency characteristics of the OLEDs; however, an increase in the operational stability of devices was recorded.
•Reconstruction of dynamical systems from time series needs class-oriented techniques.•Reduction of the initial condition number is crucial for a hidden variable approach.•Methods for the recovery of ...delay times in time-delay systems are discussed.•Phase dynamics based methods are quite universal for studying coupled oscillators.
Reconstruction of dynamical systems from time series is an important problem intensively studied within nonlinear dynamics and time series analysis for the last three decades. Its solution is a tool to accomplish prediction, classification, diagnostics and many other tasks. Universal approaches are quite attractive, but more specific techniques based on prior information about a system under study often appear advantageous in practice. We present an overview of the works of our team where such “class-oriented” techniques have been developed for realistic situations differing by the degree of prior knowledge: fully known structure of the dynamics equations with an accent to dealing with hidden variables and partly known structure for time-delay systems and coupled phase oscillators.
Two ways of creating an optical comb in an optoelectronic oscillator are proposed and investigated. The first is based on using a multimode regime of operation in an optoelectronic oscillator; the ...second, on a modulation expansion of the laser line using high indices of modulation. Characteristics of the two schemes are investigated by means of numerical modeling.
Abstract
Due to their outstanding dielectric and magnetic properties, hexaferrites are attracting ever-increasing attention for developing electronic components of next-generation communication ...systems. The complex crystal structure of hexaferrites and the critical dependences of their electric and magnetic properties on external factors, such as magnetic/electric fields, pressure, and doping, open ample opportunities for targeted tuning of these properties when designing specific devices. Here we explored the electromagnetic properties of lead-substituted barium hexaferrite, Ba
1−
x
Pb
x
Fe
12
O
19
, a compound featuring an extremely rich set of physical phenomena that are inherent in the dielectric and magnetic subsystems and can have a significant effect on its electromagnetic response at terahertz frequencies. We performed the first detailed measurements of the temperature-dependent (5–300 K) dielectric response of single-crystalline Ba
1−
x
Pb
x
Fe
12
O
19
in an extremely broad spectral range of 1 Hz–240 THz. We fully analyzed numerous phenomena with a corresponding wide distribution of specific energies that can affect the terahertz properties of the material. The most important fundamental finding is the observation of a ferroelectric-like terahertz excitation with an unusual temperature behavior of its frequency and strength. We suggest microscopic models that explain the origin of the excitation and its nonstandard temperature evolution. Several narrower terahertz excitations are associated with electronic transitions between the fine-structure components of the Fe
2+
ground state. The discovered radio-frequency relaxations are attributed to the response of magnetic domains. Gigahertz resonances are presumably of magnetoelectric origin. The obtained data on diverse electromagnetic properties of Ba
1−
x
Pb
x
Fe
12
O
19
compounds provide information that makes the entire class of hexaferrites attractive for manufacturing electronic devices for the terahertz range.
A study of the application of a graphene-based cooling system for a personal electronic computer (PC) is presented. The features of using monocrystalline and polycrystalline graphene in practice are ...analyzed. A comparison is made with the materials currently used in the cooling systems of a PC. The heat flux densities are calculated as a function of the temperature between the copper plate and the water adsorbate and between the two layers of polycrystalline graphene and water adsorbate. The prospects for the use of graphene in cooling systems of PCs are outlined.
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