Diameter Dependence Research Articles

Dependence of nanowire length, diameter, and concentration on the electrochromic properties of hybrid silver nanowire network/PEDOT:PSS-based devices

Mixing silver nanowires is a relevant tool to increase the overall conductivity of hybrid electrochromic systems. Herein, the addition of silver nanowires with an average diameter of 30 nm, length of 88 um, and concentration of 3.0 mg/ml lowered the sheet resistance of PEDOT:PSS films from 280 Ω/sq to 34 Ω/sq. Further characterized for their electrochromic behavior, mixing silver nanowires with PEDOT:PSS films allowed lowering the turn-on voltage from -1.5 V to -1.1 V and reducing the switching time from 7 to 3.6 seconds. Furthermore, with the addition of silver nanowires into PEDOT:PSS, an expensive ITO transparent and environmentally impactful electrode material is no longer required. Electrochromic devices based on hybrid AgNW/PEDOT:PSS films showed higher colouration efficiency, lower sheet resistance, lower turn on voltage, and faster switching times as compared to electrochromic devices made with PEDOT:PSS films only.

Size and velocity of jet drops produced by bursting bubbles at the interface of a water jet

Bursting bubbles at the free surface of aerated faucet water jets may spread pathogens through the released droplets. Many studies focused on the production of jet drops from bursting bubbles at a planar interface, particularly for the first jet drop. The extent to which previous findings apply to bubbles in aerated jets remains unknown. In this study, we produce a wide range of bubble size distributions within different jet diameters and characterize the diameter and velocity of jet drops released from individually bursting bubbles. Several similarities with the planar case are recovered, such as the overall dependence of the jet drop diameter and bursting dynamics on the bubble diameters and the formation of secondary jet drops. However, we observe asymmetries in the ejection of the droplets, and droplets ejected horizontally appear to have the highest ejection velocity among all jet drops. By modeling the evolution of the ejected drops for the different bubble size distributions, we find that for a mean Laplace number Labub=ρwσwRbubμw2≲6×104, a fraction of the drops ejected can become airborne. Droplets deposit within 9 cm for a mean Labub≲2.1×104 and within 33 cm for a mean 2.1×104≲Labub≲1.8×105 from a faucet jet, assuming a countertop situated 20 cm below the faucet outlet. A bubble size distribution with a mean Labub of 6×104 would minimize both the risk of airborne pathogen transmission and that resulting from surface contamination.

Universal correlation for the critical diameter of deterministic lateral displacement devices with polygonal posts.

Deterministic lateral displacement (DLD) is a microfluidic technique that utilizes a specific array of micro-posts to separate cells or particles larger and smaller than a critical diameter. The critical diameter depends on the shape of the posts, the gap between the posts, and the relative shift between the adjacent rows of posts. Here, we present an experimental and numerical investigation to elucidate the functional dependence of the critical diameter of DLD arrays with polygonal posts on the geometric parameters. Based on simulations of fluid flow through DLD devices with varying geometric parameters, we first derived a correlation to predict the critical diameter of DLD arrays with polygonal post shapes having an arbitrary number of sides. We then used a novel experimental approach, wherein we coupled different DLD arrays with an upstream droplet generator to flow droplets of varying sizes and estimate the critical diameter. The critical diameter predicted by the correlation based on simulations compares well with our experimental data and with data available in the literature. The universal correlation for a critical diameter presented here can help design and optimize DLD devices with polygonal posts.

Sputtering of silver nanoparticles bombarded with 3–100 keV Ar ions

Rutherford backscattering spectrometry and scanning electron microscopy were applied to obtain sputtering yields of Ag nanoparticles (5–30 nm in diameter) under 3–100 keV Ar+ ion irradiation. For low-energy ion irradiation, the diameter dependence of the sputtering yield was approximately 1.5 times higher than that of the bulk at diameters of a few nanometers, and then approached the bulk value at larger diameters. Under high-energy ion irradiation, especially for 100 keV Ar+ irradiation, the sputtering yields of Ag nanoparticles with diameters as small as a few nanometers were extremely higher than those predicted by the theoretical calculations. We concluded that such high sputtering yield originated in Ag cluster emission.

Stiffness modeling of thermoset polymer fibers

AbstractRecent progress in creating micro and nano‐scale thermoset polymer fibers through extensional flow reveals remarkable mechanical properties. For instance, epoxy microfibers display a notable increase in stiffness, strength, and toughness as their diameter decreases. This size‐dependent behavior, well‐explored and explained in thermoplastic polymers, is far from being understood in thermoset polymers, as their densely cross‐linked network structure seems to restrain preferential directionality. Our theoretical analysis proposes that, during the pre‐gel curing phase, when the thermoset polymer begins clustering but remains in a liquid state, substantial cluster elongation is induced by the extensional flow. This elongated formation persists to some extent after curing completion, resulting in enhanced mechanical properties along the fiber's primary axis. Concurrently, the high extension reduces fiber diameter, leading to a power‐law diameter dependence of fiber stiffness. The model agrees well with experimental data from tensile tests on epoxy microfibers, highlighting the potential to fine‐tune mechanical properties by controlling the curing process, and laying the groundwork for future improvements.

Monolayer of microgel particles based on poly(acrylic acid) modified with dopamine for electrochemical pH sensing

A novel electroactive and pH-responsive microgel was successfully synthesized. The obtained microgel was based on acrylic acid, dopamine methacrylamide and N,N′-bis(acryloyl)cystamine as the crosslinker. Using the distillation precipitation polymerization method, spherical, smooth-surface microgel particles of ca. 400 nm in diameter were obtained. The presence of dopamine groups in the polymer network was confirmed with cyclic voltammetry and NMR spectroscopy. The dependence of microgel hydrodynamic diameter on pH was investigated using the DLS technique. The presence of -S–S- groups in the microgel particle was used to modify the Au electrode surface by chemisorption. The attachment was monitored with the QCM-D technique. The obtained microgel was successfully anchored to the Au regular- and microelectrode surfaces. The electrochemical properties of the modified electrodes were promising. It was found that modified electrodes exhibited potentially useful pH-sensing properties. Modification of Au microelectrode surface with the environmentally sensitive and electroactive microgel monolayer is a novel, innovative approach.

Теоретическое определение минимально допустимого диаметра внутреннего кольца смесителя для получения двухфазной смеси

When flushing marine systems and their components, a mixed flow of water and air can be used. This method of intensifying the flushing process of ship systems brings tangible results, but currently has a number of unresolved tasks. One of these tasks is the issue related to the risk of cavitation phenomena when using a two-phase mixture. The occurrence of cavitation depends on a number of factors, but primarily on the mass content of air in the water stream. An attempt has been made to assess the development of cavitation in the elements of a mixer used to produce a stable mixture of water and air. The design of the mixer is considered. The main theoretical dependence of the minimum allowable diameter of the narrow ring of the mixer on the main parameters of the mixed flow is determined: the densities of the phases of the mixture, the mass content of air in the stream, the initial diameter of the pipeline and the compression ratio of the jet in a narrow section, as well as on the initial pressure of the flushing flow. In the study of cavitation phenomena, a homogeneous model of a two-phase mixture was used as the most suitable for the flushing mode with a two-phase pulsating flow. The main calculation dependencies for determining the minimum allowable diameter of the narrow ring of the mixer are determined. The influence of various factors on the development of cavitation phenomena has been assessed. Recommendations are given on the choice of the diameter of the narrow ring of the mixer.

Diameter dependence of transport through nuclear pore complex mimics studied using optical nanopores

The nuclear pore complex (NPC) regulates the selective transport of large biomolecules through the nuclear envelope. As a model system for nuclear transport, we construct NPC mimics by functionalizing the pore walls of freestanding palladium zero-mode waveguides with the FG-nucleoporin Nsp1. This approach enables the measurement of single-molecule translocations through individual pores using optical detection. We probe the selectivity of Nsp1-coated pores by quantitatively comparing the translocation rates of the nuclear transport receptor Kap95 to the inert probe BSA over a wide range of pore sizes from 35 nm to 160 nm. Pores below 55 ± 5 nm show significant selectivity that gradually decreases for larger pores. This finding is corroborated by coarse-grained molecular dynamics simulations of the Nsp1 mesh within the pore, which suggest that leakage of BSA occurs by diffusion through transient openings within the dynamic mesh. Furthermore, we experimentally observe a modulation of the BSA permeation when varying the concentration of Kap95. The results demonstrate the potential of single-molecule fluorescence measurements on biomimetic NPCs to elucidate the principles of nuclear transport.

Diameter dependence of transport through nuclear pore complex mimics studied using optical nanopores.

The nuclear pore complex (NPC) regulates the selective transport of large biomolecules through the nuclear envelope. As a model system for nuclear transport, we construct NPC mimics by functionalizing the pore walls of freestanding palladium zero-mode waveguides with the FG-nucleoporin Nsp1. This approach enables the measurement of single-molecule translocations through individual pores using optical detection. We probe the selectivity of Nsp1-coated pores by quantitatively comparing the translocation rates of the nuclear transport receptor Kap95 to the inert probe BSA over a wide range of pore sizes from 35 nm to 160 nm. Pores below 55 ± 5 nm show significant selectivity that gradually decreases for larger pores. This finding is corroborated by coarse-grained molecular dynamics simulations of the Nsp1 mesh within the pore, which suggest that leakage of BSA occurs by diffusion through transient openings within the dynamic mesh. Furthermore, we experimentally observe a modulation of the BSA permeation when varying the concentration of Kap95. The results demonstrate the potential of single-molecule fluorescence measurements on biomimetic NPCs to elucidate the principles of nuclear transport.

Providing a cavitation-free regime when flushing ship pipelines with a two-phase mixture

It is noted that during the flushing of ship systems and their elements, the mixed flow of water and air has proven itself well as a flushing medium. It has been experimentally established that there is a significant acceleration of the washing process and an increase in the number of flushed-out dirt particles. At the same time, the two-phase flushing method currently has a number of unsolved theoretical and practical problems. One of such tasks is to ensure a cavitation-free flushing regime. The issue of ensuring a cavitation-free regime when flushing ship pipelines with a twophase mixture during the passage of narrownesses stream is considered in the paper. It is known that the cavitation occurrence depends on a number of factors. The degree of each factor influence on the probability of cavitation occurrence is investigated. In this paper, an attempt to theoretically assess the development of cavitation in narrow technological jumpers is made. The main theoretical dependence of the maximum permissible diameter of the jumper on the main parameters of the mixed flow, as well as on the initial pressure of the flushing flow is determined. The main parameters of the mixed flow are the mass flow rate of the flushing water, the densities of the mixture phases, the mass content of air in the flow, the initial diameter of the pipeline and the compression ratio of the jet in a narrow section. A homogeneous mixture model is used in the theoretical study of cavitation phenomena in a two-phase flow. The main design dependencies for determining the maximum allowable diameter of the jumper depending on the main factors of the two-phase flow are defined in the paper. The influence of various factors on the development of cavitation phenomena is evaluated. Particular attention is paid to the choice of the flow diameter of the technological jumper depending on the mass flow rate of the flushing stream, the air content and the initial pressure.

Detonation parameters of the mixture of gelled nitromethane/microballoons at high porosity

The detonation properties of mixtures of gelled nitromethane (NM) with hollow glass microballoons (GMBs), the concentration of which varied from 16 to 30 wt. %, have been studied using an optical technique with high temporal and spatial resolution. It is shown that the addition of GMBs up to 30 wt. % does not qualitatively change the reaction zone structure of NM, which is in accordance with the classical detonation theory. However, the detonation parameters of the mixture decrease significantly with increasing GMB concentration—the pressure at the Chapman–Jouguet point drops by more than an order of magnitude at a porosity of 75%. The non-monotonic nature of the change in critical detonation diameter with decreasing mixture density is noted. The dependence of the critical diameter on the porosity of U-shape with the formation of two local minima at 8 and 18 wt. % GMB in the mixture and a local maximum at 13 wt. % GMB is obtained. At a concentration above 20 wt. % GMB, the critical detonation diameter increases dramatically, and at 30 wt. % GMB, the critical diameter becomes comparable to that of gelled NM.

Electromagnetic enhancement spectra of one-dimensional plasmonic hotspots along silver nanowire dimer derived via surface-enhanced fluorescence.

We developed a spectroscopic method for directly obtaining the spectra of electromagnetic (EM) enhancement of plasmonic hotspots (HSs). The method was applied to one-dimensional (1D) HSs generated between silver nanowire (NW) dimers. The EM enhancement spectra were derived by dividing the spectra of surface-enhanced fluorescence (SEF) from single NW dimers with SEF obtained from large nanoparticle aggregates, where aggregate-by-aggregate variations in the SEF spectra were averaged out. Some NW dimers were found to exhibit EM enhancement spectra that deviated from the plasmon resonance Rayleigh scattering spectra, indicating that their EM enhancement was not generated by superradiant plasmons. These experimental results were examined by numerical calculation based on the EM mechanism by varying the morphology of NW dimers. The calculations reproduced the spectral deviations as the NW diameter dependence of EM enhancement. Phase analysis of the enhanced EM near-fields along the 1D HSs revealed that the dipole-quadrupole coupled plasmon, which is a subradiant mode, mainly generates EM enhancement for dimers with NW diameters larger than ∼80nm, which was consistent with scanning electron microscopic measurements.

Dependency of beam diameter on the resistance time of laser guards

Laser manufacturers and users of material processing machines must implement technical protective measures. The assessment of the protective effect of laser guards for use in laser machines with respect to the accessible laser parameters (e.g. beam diameter and irradiance) is currently problematic, as extensive individual resistance time tests are often required. The aim and focus of the project is to determine mathematically representable relationships between beam diameter, irradiance and resistance time for commercially available laser safety shield materials. The functional relationships found should enable the manufacturers and users of lasers to determine the appropriate shielding for the respective application solely on the basis of existing standard tests and without further time-consuming, case-specific tests. A standardized test setup (test box) is being developed to ensure globally uniform laser resistance time tests of shielding materials.

Beyond ray optics absorption of light in CsPbBr3 perovskite nanowire arrays studied experimentally and with wave optics modelling

We study experimentally and with wave optics modelling the absorption of light in CsPbBr3 perovskite nanowire arrays fabricated into periodic pores of an anodized aluminum oxide matrix, for nanowire diameters from 30 to 360 nm. First, we find that all the light that couples into the array can be absorbed by the nanowires at sufficient nanowire length. This behavior is in strong contrast to the expectation from a ray-optics description of light where, for normally incident light, only the rays that hit the cross-section of the nanowires can be absorbed. In that case, the absorption in the sample would be limited to the area fill factor of nanowires in the hexagonal array, which ranges from 13% to 58% for the samples that we study. Second, we find that the absorption saturates already at a nanowire length of 1000–2000 nm, making these perovskite nanowires promising for absorption-based applications such as solar cells and photodetectors. The absorption shows a strong diameter dependence, but for all diameters the transmission is less than 24% already at a nanowire length of 500 nm. For some diameters, the absorption exceeds that of a calculated thin film with 100% coverage. Our analysis indicates that the strong absorption in these nanowires originates from light-trapping induced by the out-of-plane disorder due to random axial position of each nanowire within its pore in the matrix.

Coexistence curve diameter and slope of vapor pressure: “universal” relation in the critical region

We have (i) discovered a universal dependence of the coexistence curve diameter, related through the exponent of critical isotherm to vapor pressure slope in the vicinity of the critical point; (ii) proved that the dimensionless diameter of the coexistence curve cannot be less than 1; (iii) obtained the universal strength of the Yang-Yang anomaly with a value of 0.62±0.01; (iv) calculated the critical amplitude of isothermal compressibility for a number of fluids using the previously unknown universal ratio.

Diameter-Dependent Competitive Adsorption of Sodium Dodecyl Sulfate and Single-Stranded DNA on Carbon Nanotubes.

The equilibrium compositions of coatings on single-wall carbon nanotubes were spectroscopically deduced for samples dispersed in dilute sodium dodecyl sulfate (SDS) and then exposed to low concentrations of ssDNA oligomers. With all studied oligomers, displacement of the SDS tended to occur at lower ssDNA concentrations for smaller diameter nanotubes than for larger diameter ones. However, the behavior varied significantly with oligomer. For example, the diameter dependence was steeper for (TAT)4 than for (ATT)4, suggesting that interstrand head-to-tail hydrogen bonding interactions play a role in SWCNT wrapping. Concentrations of ssDNA in the range of several μg/mL displace SDS from nanotubes dispersed in 1500 μg/mL SDS solutions. This effect allows the use of coating exchange to prepare ssDNA dispersions with minimal oligomer costs. Another demonstrated use exploits the structure-dependent relative coating affinities in a simple filtration method for the diameter enrichment of SWCNT mixtures.

Potential measurement error from vessel reflex and multiple light paths in dual-wavelength retinal oximetry.

This study aims to characterize the dependence of measured retinal arterial and venous saturation on vessel diameter and central reflex in retinal oximetry, with an ultimate goal of identifying potential causes and suggesting approaches to improve measurement accuracy. In 10 subjects, oxygen saturation, vessel diameter and optical density are obtained using Oxymap Analyzer software without diameter correction. Diameter dependence of saturation is characterized using linear regression between measured values of saturation and diameter. Occurrences of negative values of vessel optical densities (ODs) associated with central vessel reflex are acquired from Oxymap Analyzer. A conceptual model is used to calculate the ratio of optical densities (ODRs) according to retinal reflectance properties and single and double-pass light transmission across fixed path lengths. Model-predicted values are compared with measured oximetry values at different vessel diameters. Venous saturation shows an inverse relationship with vessel diameter (D) across subjects, with a mean slope of -0.180 (SE = 0.022) %/μm (20 < D < 180 μm) and a more rapid saturation increase at small vessel diameters reaching to over 80%. Arterial saturation yields smaller positive and negative slopes in individual subjects, with an average of -0.007 (SE = 0.021) %/μm (20 < D < 200 μm) across all subjects. Measurements where vessel brightness exceeds that of the retinal background result in negative values of optical density, causing an artifactual increase in saturation. Optimization of model reflectance values produces a good fit of the conceptual model to measured ODRs. Measurement artefacts in retinal oximetry are caused by strong central vessel reflections, and apparent diameter sensitivity may result from single and double-pass transmission in vessels. Improvement in correction for vessel diameter is indicated for arteries however further study is necessary for venous corrections.

MODELLING AND TESTING OF SYNCHRONOUS MOTORS WITH PERMANENT MAGNETS

Applying a layer of polymer material to the fabric gives new characteristics to the base fabric. The resulting coated material may have functional properties such as resistance to dirt, liquid penetration, etc., or the finished leather products may have a completely different aesthetic appeal. The choice of the coating method depends on several factors: the type of substrate, the polymer formula and its viscosity for coating, the desired final product and the accuracy of the coating, the economy of the process. In the conditions of modern enterprises, it is advisable to use the spray application method for the application of polymer coatings due to the fact that the roller and brush methods do not provide the opportunity to operate with different forms of parts, and volumetric application is not always economically feasible. Jet application of the material is similar to spraying, but for polymer coatings, the temperature value is important, which in this case is difficult to control. Therefore, it is advisable to use the spraying method for applying polymer coatings The paper presents the results of preliminary research on the breakdown of polymers into droplets. The shape of the flow coming out of the nozzle was determined, and based on this, a model describing this process was developed. It is shown that for a sheet of polymer flow, its thickness is inversely proportional to the distance from the nozzle and K=2sx, calculated knowing the thickness of the sheet at some distance x from the nozzle. For a “hollow cone” spray nozzle with taper angle, θ and orifice diameter, δ and sheet thickness h, at the nozzle exit, an equation for the flow length break was derived. The obtained results of the calculations of the dependence of the droplet diameter on the flow rate. A spray test was carried out in different modes. The ratio of the length of the jet to the length of the gap L serves as the beginning of the decay mode. It was determined that the ratio of the length of the jet to the length of the gap of the canvas when reaching 1 can be a reasonable criterion for evaluating the determination of the limits of the spraying mode. For a good spraying (for example, tearing of the web), small values of the ratio of the length of the jet to the length of the tearing of the web are necessary. This is achieved due to low surface tension, high gas density, high injection pressure (velocity) and large nozzle exit angles. The obtained results can be used for the design of sprayers and their modes of operation.

Research of the influence of design parameters of a vibrating conveyor on its technical characteristics

Purpose. The study is aimed at: determining the nature of the influence of design data on the technical characteristics of a two-pipe vibratory conveyor with an eccentric drive, in particular, the pipe diameter and drive power; building analytical dependencies of these values on the design characteristics: type and properties of the cargo, length of transportation, productivity; conducting a graphical analysis of the influence. Methodology. To achieve this goal, we used the calculation algorithms presented in the modern technical literature and analyzed the factors and values that affect the values of drive power and pipe diameter. It has been established that to determine the drive power of vibratory conveyors, it is necessary to carry out a detailed calculation, which includes: the angular velocity of the conveyor, the rotational speed of the eccentric shaft, the material transportation speed, the internal diameter of the pipe, the total mass of the oscillating system, the stiffness of the elastic system and the parameters of the springs, the forces in the connecting rod in the case of the resonant mode of operation and during the start-up period. Findings. For a two-pipe vibrating conveyor designed to transport a lead conglomerate, a graphical analysis of the influence of the length of transportation, productivity on the drive power and overall dimensions of the pipe was carried out. It was found that the function of the pipe diameter change with capacity is nonlinearly increasing (when other parameters are fixed), and the drive power with capacity is linearly increasing. Originality. The authors first studied the dependence of drive power and pipe diameter of a two-pipe vibrating conveyor with an eccentric drive on the lower pipe, and built analytical dependencies of technical characteristics (power and diameter) on design parameters: productivity, transportation length, type and physical and mechanical properties of the transported cargo. For a conveyor that transports lead sinter, graphical dependencies of the pipe diameter and drive power on the capacity and length of the conveyor were constructed. Practical value. The use of the constructed dependencies makes it possible to determine the general nature of the change in the above technical characteristics in the case of varying design parameters such as conveyor capacity and length. The proposed dependencies can be used to quickly determine the rational power of the conveyor drive for specific design data.

Single-file transport of binary hard-sphere mixtures through periodic potentials.

Single-file transport occurs in various scientific fields, including diffusion through nanopores, nanofluidic devices, and cellular processes. We here investigate the impact of polydispersity on particle currents for single-file Brownian motion of hard spheres when they are driven through periodic potentials by a constant drag force. Through theoretical analysis and extensive Brownian dynamics simulations, we unveil the behavior of particle currents for random binary mixtures. The particle currents show a recurring pattern in dependence of the hard-sphere diameters and mixing ratio. We explain this recurrent behavior by showing that a basic unit cell exists in the space of the two hard-sphere diameters. Once the behavior of an observable inside the unit cell is determined, it can be inferred for any diameter. The overall variation of particle currents with the mixing ratio and hard-sphere diameters is reflected by their variation in the limit where the system is fully covered by hard spheres. In this limit, the currents can be predicted analytically. Our analysis explains the occurrence of pronounced maxima and minima of the currents by changes in the effective potential barrier for the center-of-mass motion.