Increase In Core Radius Research Articles

A Stochastic FRET Study on the Core Dimension of Polystyrene-block-Poly(Polyethylene Glycol Monomethyl Ether Acrylate) Micelles.

Polystyrene-b-poly(polyethylene glycol monomethyl ether acrylate) (PSt-b-PPEGA) copolymers featuring pyrene and perylene as the Förster resonance energy transfer (FRET) donor (denoted as D-BCP) and acceptor (denoted as A-BCP), respectively, were synthesized via the reversible addition and fragmentation chain transfer (RAFT) polymerization. These copolymers were then used to form DA-mixed micelles via a dialysis method. The micelles consisted of D-BCP (mole fraction fD = 0.04), A-BCP (fA = 0.04), and label-free PSt-b-PPEGA (fN = 0.92). The decrease in fluorescence intensity of pyrene in the micelles confirmed the occurrence of FRET, with an observed efficiency of 0.32. A Monte Carlo approach was employed to estimate the expected FRET efficiency, assuming the random fractional distribution of D-BCP and A-BCP, along with the random spatial distribution of pyrene and perylene within the micellar core. The observed FRET efficiency suggested a core radius (Rc) of 0.95R0, where R0 was the Förster critical distance. With R0 calculated to be 3.2 nm based on Förster theory, Rc was determined to be approximately 3.0 nm, aligning closely with the dried-out core radius estimated from aggregation number and polystyrene density. This stochastic FRET methodology was further applied to investigate the swelling behavior of the polymer micelles in a mixture of N,N-dimethylformamide (DMF) and water. Dynamic light scattering analysis revealed minimal change in core dimension below 60 vol % DMF content. However, FRET analysis provided a deeper insight, showing an increase in core radius with DMF content up to 20 vol %, followed by saturation up to 50 vol %, offering a more comprehensive understanding of the micelle swelling behavior.

The combined effects of electric field and embedded dielectric matrix on the electronic and optical properties in Ge/SiGe core/shell quantum dots and its SiGe/Ge inverted structure

In this study, the binding energy (BE) and photoionization cross-section (PICS) coefficients in a Ge/Si0.15Ge 0.85 core/shell quantum dots (CSQDs) and in its inverted structure Si0.15Ge0.85 / Ge (ICSQDs) are studied. The influence of the hydrogenic impurity and capped matrix are taken into account. The electronic states and their related eigenfunctions are computed by solving the three-dimensional Schrödinger equation under the framework of the effective mass approximation (E.M.A) using the variational dimensional. The influence of the core radius and electric field strength on the BE and PICS are investigated. The numerical results reveal that the optoelectronic properties are considerably affected by the electric field strength (EF), immersed oxide matrix (OM) and geometric parameter. The obtained results prove that the PICS magnitude increases as the core radius increases and its resonant peak moves towards the lower energies for Ge/Si0.15Ge0.85 CSQDs structure, and increases as the core radius decreases and its resonant peak experiences a blue shift with increasing core radius for Si0.15Ge 0.85/ Ge ICSQDs. Moreover, with the effects of the surrounding oxide matrix and electric field strength, the PICS magnitude is improved and their resonant peak suffers a redshift.

Studying the effect of changing optical fibers parameters on their modes properties at 1000 nm wavelength

Optical fiber technology is without a doubt one of the most significant phases of the communications revolution and is crucial to our daily lives. Using the free version (2022) of RP Fiber Calculator, the modal properties for optical fibers with core radii (1.5−7.5) μm, core index (1.44−1.48) and cladding index (1.43−1.47) have been determined at a wavelength of 1000 nm. When the fiber core’s radius is larger than its operating wavelength, multimode fibers can be created. The result is a single-mode fiber in all other cases. All of the calculated properties, it has been shown, increase with increasing core radius. The modes’ intensity profiles were displayed.

Exciton binding energy and radiation lifetime in CdTe/Cd1−xZnxS strained core/shell spherical quantum dots under pressure

In this paper, the exciton binding energy and radiation lifetime in type I and II structures of CdTe/Cd[Formula: see text]ZnxS strained core/shell spherical quantum dots under the hydrostatic pressure have been studied by using the variational method within the continuous dielectric model and effective mass approximation. The results show that for these two structures, the exciton binding energies with and without strain decrease with the increasing core radius but increase with the increasing pressure. The exciton binding energy with strain is smaller than that without strain. For type I structure, the effect of strain is small, and the radiation lifetime decreases monotonically with the increasing pressure. By contrast, for type II structure, the effects of shell radius and strain on the exciton binding energy are obvious, and the radiation lifetime increases first and then decreases with the increasing pressure.

Effect of truss core on sound radiation behavior of sandwich plate structures under structure borne excitation

Compared with traditional honeycomb and stiffened sandwich structures, lattice-based structures are considered an ideal substitute for traditional core structures due to their high stiffness and other potential multifunctional application characteristics. Based on that, the sound radiation characteristics of the sandwich plate with different truss cores under structure borne excitation were investigated in the current paper, wherein three truss cores, including pyramidal, tetrahedral and 3D-kagome cores types, are considered. The governing equations for the vibration and sound radiation analysis of the sandwich plate structure are carried out using the static equilibrium method, and then solved via the Navier approach and Rayleigh integral. By comparing the experimental results, the validity of the proposed theoretical model is verified. The theoretical model is subsequently used to investigate the influences of truss core geometric parameters and types, face sheet-core face sheet thickness ratio and aspect ratio on sandwich plate sound radiation characteristics. The results indicate that, in the range [ 5 ∘ ≤ θ ≤ 52 ∘ ] and [ 52 ∘ < θ ≤ 85 ∘ ] , the tetrahedral and 3D-Kagome core types have the maximum natural frequency values, respectively, while the resonance peaks of sound pressure level curves move to lower frequency region with the increase in truss core radius and face sheet-core face sheet thickness ratio, and the sandwich plate with the 3D-kagome core shows better sound radiation characteristics in the wide frequency range.

Numerical study on the scale effect of tip vortex cavitation induced by incoming velocities and scale ratios

Large eddy simulations of tip vortex cavitation (TVC) around an elliptical hydrofoil is performed to study its scale effect. A satisfying agreement is obtained between the numerical and experimental data. It indicates that the scale effect of TVC is remarkable. With the increase of scale ratio or incoming velocity, the intensity of TVC significantly increases. Based on our results, two mechanisms for the scale effect of TVC are proposed, i.e., the roll-up of boundary layer and the interaction between tip vortex (TV), secondary vortex and trailing vortex. As incoming velocity increases, the fusion of TV and secondary vortex enhances and the boundary layer thickness decreases, which lead to larger circulation and smaller vortex core radius, tending to intensify TV. As scale ratio increases, the fusion of TV and secondary vortex enhances and the boundary layer thickness increases slightly, which lead to much higher circulation and slight increase of vortex core radius, promoting the occurrence of TVC in general. In addition, with equal cavitation number and Reynolds number, TVC in the large scale is stronger than that in the small scale, indicating that it seems not so reasonable to equate the velocity-induced scale effect with the scale-ratio-induced one.

Calculation of Mode Properties for Single-Mode and Multimode Fibers at 633 nm

The need for optical fibers has emerged for their ability to transmit information with less attenuation over long distances. This work studies four optical fibers with core radii from 1 µm to 4.75 µm in steps of 1.25 µm and a numerical aperture of 0.17. furthermore, The mode properties were calculated at a wavelength of 633 nm by using RP Fiber Calculator (free version 2022). Also, the effect of increasing the core radius on the studied properties has been studied. Multimode fibers can be obtained when the radius of the fiber core is large compared with the fiber's operating wavelength, which is less than the cutoff wavelength of the mode. Moreover, single-mode fiber is obtained. It has been concluded that all the calculated properties increase with increasing core radius, and More than half of the power is contained in the core. Finally, Intensity profiles of all modes were illustrated.

Large Eddy Simulation Research on the Evolution Mechanism of Aircraft Wake Influenced by Cubic Obstacle

Aircraft wake is a kind of intense air movement, and the study of its generation, development, and dissipation law is of great significance to the flight safety. There are abundant researches on the evolution of aircraft wakes affected by weather and ground effects; however, there are few studies on the influence of a single obstacle on the evolution of aircraft wake. In this article, in order to explore the influence of a single obstacle on the evolution of aircraft wake, firstly, we develop a computational fluid dynamics-based method of simulation of aircraft wake affected by cubic obstacle of different heights in order to obtain the wake intensity changes and position changes before and after being affected by the obstacle. Then, the result data are visualized and analyzed, and we obtain the results of velocity and Q criterion contours, circulation, and data related to wake vortex structure. CFD simulations are conducted, including the cases of the vertical distance between wake vortex and obstacle which is 20 m, 60 m, 100 m, and no obstacle. The quantitative results indicate that a single obstacle also has a great influence on the evolution of the wake vortex. Obstacle will shorten the time for the wake vortex to enter the fast decay stage, and the smaller the distance the wake vortex is above the obstacle, the faster it enters the fast decay stage. In the same time, the circulation will reduce 20% more under the same calculation time when the wake is 20 m above the obstacle than when the wake is 100 m above the obstacle, and the circulation will reduce 45% more than when there is no obstacle. Single obstacle also leads to the generation of multiple secondary vortices and rotates around the wake vortex, resulting in the increase of wake vortex core radius, wake vortex core spacing, and wake vortex height.

How do chain lengths of acyl-l-carnitines affect their surface adsorption and solution aggregation?

Hypothesisl-carnitines in our body systems can be readily converted into acyl-l-carnitines which have a prominent place in cellular energy generation by supporting the transport of long-chain fatty acids into mitochondria. As biocompatible surfactants, acyl-l-carnitines have potential to be useful in technical, personal care and healthcare applications. However, the lack of understanding of the effects of their molecular structures on their physical properties has constrained their potential use. ExperimentsThis work reports the study of the influence of the acyl chain lengths of acyl-l-carnitines (CnLC) on solubility, surface adsorption and aggregation. Critical micellar concentrations (CMCs) of CnLC were determined by surface tension measurements. Neutron reflection (NR) was used to further examine the structure and composition of the adsorbed CnLC layer. The structural changes of the micellar aggregates under different concentrations of CnLC, pH and ionic strength were determined by dynamic light scattering (DLS) and small angle neutron scattering (SANS). FindingsC12LC is fully soluble over a wide temperature and concentration range. There is however a strong decline of solubility with increasing acyl chain length. The adsorption and aggregation behavior of C14LC was therefore studied at 30 °C and C16LC at 45 °C. The solubility boundaries displayed distinct hysteresis with respect to heating and cooling. The CMCs of C12LC, C14LC and C16LC at pH 7 were 1.1 ± 0.1, 0.10 ± 0.02 and 0.010 ± 0.005 mM, respectively, with the limiting values of the area per molecule at the CMC being 45.4 ± 2, 47.5 ± 2 and 48.8 ± 2 Å2 and the thicknesses of the adsorbed CnLC layers at the air/water interface increasing from 21.5 ± 2 to 22.6 ± 2 to 24.2 ± 2 Å, respectively. All three surfactants formed core–shell spherical micelles with comparable dimensional parameters apart from an increase in core radius with acyl chain length. This study outlines the effects of acyl chain length on the physicochemical properties of CnLCs under different environmental conditions, serving as a useful basis for developing their potential applications.

Mathematical Modeling of Unsteady Solute Dispersion in Bingham Fluid Model of Blood Flow Through an Overlapping Stenosed Artery

An artery narrowing referred to as atherosclerosis or stenosis causes a reduction in the diameter of the artery. When blood flow through an artery consists of stenosis, the issue of solute dispersion is more challenging to solve. A mathematical model is developed to examine the unsteady solute dispersion in an overlapping stenosed artery portraying blood as Bingham fluid model. The governing of the momentum equation and the constitutive equation is solved analytically. The generalized dispersion model is imposed to solve the convective-diffusion equation and to describe the entire dispersion process. The dispersion function at steady-state decreases at the center of an artery as the stenosis height increase. A reverse behavior is shown at an unsteady-state. As the plug core radius, time and stenosis height increase, the dispersion function decreases at the center of an artery. There is a high amount of red blood cells at the center of the artery but no influences near the wall. Hence, this model is useful in transporting the drug or nutrients to the targeted stenosed region in the treatment of diseases and in understanding many physiological processes.

Design of Optical Fibers and Calculate their Guided Modes Properties at 1550 nm

There is no doubt that optical fiber technology is one of the most important stages of the communications revolution at all and it is of utmost importance in our daily life. In this work, five fibers with core radii 2.5, 4.5 and 6.5–8.5 μm were designed. The properties of all guided modes have been calculated at a wavelength of 1550 nm by using RP Fiber Calculator. A single-mode fiber is obtained when the core radius approaches the wavelength. As the core radius is increased, the fiber becomes a multimode. The percentage power in the core increases with increasing core radius. The modes profiles were illustrated and compared with the modern references.

Large range LSPR of KTN@Ag core-shell nanoarray dependent of structure size

The localized surface plasmon resonance (LSPR) of Ag nanosphere array and KTN@Ag (nano KTa0.65Nb0.35O3 with Ag at it’s the surface) core-shell nanoarray are elaborately analyzed based on finite-difference time-domain (FDTD). The effects of particle spacing, core size and shell size on LSPR for the KTN@Ag core-shell nanoarray structure are systematically investigated. The results indicate that the core size and shell size for the KTN@Ag core-shell nanoarray structure have a great influence on LSPR. With the increase of the Ag shell radius, the resonance absorption appears blue-shift from 878 nm to 660 nm. With the increase of KTN core radius, the resonance absorption peak exhibits significantly red-shift from 538 nm to 867 nm. Thus, the designed KTN@Ag core-shell nanoarray structure can realize the effective regulation of LSPR in a wider range, which is obviously better than the Ag nanosphere array. The controllable LSPR wavelength enables the KTN@Ag core-shell nanoarray to serve as plasmonic nanosensors. This study provides a theoretical basis for the future application of KTN@Ag core-shell nanoarray structure in optical and optoelectronic devices.

Impurity states in InGaAsP/InP core–shell quantum dot under external electric field

In the framework of effective mass envelope function approximation, the impurity states are calculated in InGaAsP/InP core–shell quantum dots by plane wave expansion method, and the effect of electric field is considered. The impurity binding energies in 1s and 2p ± states, and the impurity transition energy between 1s state and 2p ± state are calculated and analyzed in detail with the change of shell thickness, core radius, impurity position, and electric field strength. The results show that the impurity states in the core are stable when the shell thickness is more than 0.4a * . The binding energies and transition energies decrease with the increase of core radius. The applied electric field destroys the symmetrical distribution of binding energy and transition energy about the core center. The increase or decrease of the binding energy and transition energy depend upon the position of impurity and the direction of electric field.

Physical and biological effects of paclitaxel encapsulation on disteraroylphosphatidylethanolamine-polyethyleneglycol polymeric micelles

Simple size observations of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethyleneglycol)-2000] (DSPE-mPEG2000) polymeric micelles (PM) with different compositions including or not paclitaxel (PTX) are unable to evidence changes on the nanocarrier structure. In such system a detailed characterization using highly sensitive techniques such as X-ray scattering and asymmetric flow field flow fractionation coupled to multi-angle laser light scattering and dynamic light scattering (AF4-MALS-DLS) is mandatory to observe effects that take place by the addition of PTX and/or more lipid-polymer at PM, leading to complex changes on the structure of micelles, as well as in their supramolecular organization. SAXS and AF4-MALS-DLS suggested that PM can be found in the medium separately and highly organized, forming clusters of PM in the latter case. SAXS fitted parameters showed that adding the drug does not change the average PM size since the increase in core radius is compensated by the decrease in shell radius. SAXS observations indicate that PEG conformation takes place, changing from brush to mushroom depending on the PM composition. These findings directly reflect in in vivo studies of blood clearance that showed a longer circulation time of blank PM when compared to PM containing PTX.

Interband optical absorption in wurtzite GaN/InxGa1−xN/GaN spherical quantum dots with built-in electric field

Based on the principle of density matrix and the finite element method, the interband optical absorption between the electron and hole has been investigated in a wurtzite [Formula: see text] spherical core–shell quantum dot (CSQD) including a strong built-in electric field (BEF). We have studied the effects of the size and the ternary mixed crystal on the optical absorption coefficients (ACs) and refraction index changes (RICs). The results indicate that the absorption peaks of ACs and RICs decrease rapidly, and show a redshift with the increase of the component [Formula: see text]. It is also found that the absorption peaks of ACs and RICs reduce obviously and depend on the core radius and the well width. When the core radius increases, the positions of the maximum ACs and RICs show a blueshift. At the same time, it presents a redshift when the well width increases. Particularly, the influence of the well width is much stronger than the core radius in the wurtzite [Formula: see text] spherical CSQDs. We hope that these results could provide guidance on both theoretical and experimental study related to the optical properties of spherical CSQDs.

Analytical evaluation of coupling coefficients of a nine-core homogeneous optical fiber

Coupling coefficients due to inter-core coupling in a 9-core homogeneous multi-core optical fiber (MCF) are evaluated analytically. Variation of coupling coefficients with respect to the fiber parameters, like, core-to-core separation (pitch), core radius and relative refractive index difference are investigated. Results show that the coupling coefficients are inversely related to the core pitch and index contrast, but it increases with the increase of core radius. It is also observed that while keeping the pitch and index contrast unchanged, the core radius plays a significant role to control the coupling among the cores. Variation of coupling coefficients with relative index difference are compared with similar results reported earlier.

Micellization of Binary Diblock Co-polymer Mixtures in an Ionic Liquid

The structure of mixed diblock co-polymer micelles in the aprotic ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIM][TFSI], was investigated by dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and small-angle neutron scattering. The diblock co-polymers are poly(methyl methacrylate)-block-poly(n-butyl methacrylate) (PMMA-b-PnBMA), where PMMA is solvent selective and forms the corona of the micelles, whereas PnBMA segregates into the micelle core. In these experiments, a pair of diblocks with the same corona block length but distinct core block lengths (Ncore) was first mixed homogeneously and then allowed to self-assemble into well-defined mixed micelles. DLS and SAXS measurements show that the hydrodynamic radius (Rh) and core radius (Rc) increase monotonically with the fraction of the longer diblock in the mixture. Interestingly, the dimensions of the binary mixed micelles are significantly larger than those formed by a single diblock with the same numb...

Effect of Ionic Group on the Complex Coacervate Core Micelle Structure.

Pairs of ionic group dependence of the structure of a complex coacervate core micelle (C3M) in an aqueous solution was investigated using DLS, cryo-TEM, and SANS with a contrast matching technique and a detailed model analysis. Block copolyelectrolytes were prepared by introducing an ionic group (i.e., ammonium, guanidinium, carboxylate, and sulfonate) to poly(ethylene oxide-b-allyl glycidyl ether) (NPEO = 227 and NPAGE = 52), and C3Ms were formed by simple mixing of two oppositely-charged block copolyelectrolyte solutions with the exactly same degree of polymerization. All four C3Ms are spherical with narrow distribution of micelle dimension, and the cores are significantly swollen by water, resulting in relatively low brush density of PEO chains on the core surface. With the pair of strong polyelectrolytes, core radius and aggregation number increases, which reflects that the formation of complex coacervates are significantly sensitive to the pairs of ionic groups rather than simple charge pairing.

Single-mode large-mode-area double-ring hollow-core anti-resonant fiber for high power delivery in mid-infrared region

Abstract A novel hollow-core anti-resonant fiber with a large mode area and good single mode performance is proposed for high power delivery in mid-infrared region. The structure consists of two-layer circular tubes as the cladding. By optimizing structure parameters, a broad low-loss single-mode band, in which the fundamental mode loss is lower than 4 × 10−3 dB/m and the high order mode extinction ratio (HOMER) is higher than 1000, is achieved in the wavelength region from 2.5 to 3.3 μm in which the lowest loss of 2.87 × 10−4 dB/m occurs at 3.1 μm. The effective mode area is up to 2314 μm2 with the highest HOMER of 16,600 at the wavelength of 2.8 μm. In addition, this fiber also has good bend resistance characteristics. When the fiber is bent at the bending radius of 18 cm, the mode area reaches to 2268 μm2 with the HOMER above 100 at the wavelength of 2.8 μm. Furthermore, the effective mode area can be further increased to 4714 µm2 by increasing core radius at the cost of sacrificing single mode performance and bending resistance.

First core properties: from low- to high-mass star formation

Aims. In this study, the main goal is to understand the molecular cloud core collapse through the stages of first and second hydrostatic core formation. We investigate the properties of Larsons first and second cores following the evolution of the molecular cloud core until the formation of Larson’s cores. We expand these collapse studies for the first time to span a wide range of initial cloud masses from 0.5 to 100 M⊙. Methods. Understanding the complexity of the numerous physical processes involved in the very early stages of star formation requires detailed thermodynamical modelling in terms of radiation transport and phase transitions. For this we used a realistic gas equation of state via a density- and temperature-dependent adiabatic index and mean molecular weight to model the phase transitions. We used a grey treatment of radiative transfer coupled with hydrodynamics to simulate Larsons collapse in spherical symmetry. Results. We reveal a dependence of a variety of first core properties on the initial cloud mass. The first core radius and mass increase from the low-mass to intermediate-mass regime and decrease from the intermediate-mass to high-mass regime. The lifetime of first cores strongly decreases towards the intermediate- and high-mass regimes. Conclusions. Our studies show the presence of a transition region in the intermediate-mass regime. Low-mass protostars tend to evolve through two distinct stages of formation that are related to the first and second hydrostatic cores. In contrast, in the high-mass star formation regime, collapsing cloud cores rapidly evolve through the first collapse phase and essentially immediately form Larson’s second cores.