Cylindrical Electrodes Research Articles

An advanced radio-frequency quadrupole ion cooler for accelerator mass spectrometry

An advanced radio-frequency quadrupole (RFQ) ion cooler was developed for accelerator mass spectrometry to use element-selective laser photodetachment and ion-molecule reactions for isobar suppression. The system will be installed as a central part of the new Anion Laser Isobar Separator (ALIS) at the 6 MV AMS system of CologneAMS.The new RFQ design intends to solve the technical challenge of the deceleration and trapping of heavy molecular ion beams with high emittance. Therefore, an elliptical injection electrode was developed to slow down the ions far away from the central entrance aperture. A new and easy-to-manufacture guide-field assembly was developed. For this purpose, diagonally-split cylindrical surface electrodes are capacitively coupled to a core rod that is carrying the RF signal. Consequently, only low DC voltages are needed to create a gradually changing potential in the longitudinal direction. The RFQ and the acceleration electrodes are installed in a self-aligned structure.

Vibration sensor for monitoring systems of construction elements of high-voltage power lines

PURPOSE. To develop a differential parametric inductive transducer of vibration values into an electrical signal, which is a vibration displacement sensor (DV) with a new principle of operation. Theoretically substantiate the performance of the proposed DV. To develop a new system for vibroacoustic monitoring of the technical condition of overhead power transmission line (TL) supports using the proposed DV. METHODS. When solving this goal, the theory of parametric transducers and the main provisions of the theory of vibration diagnostics were used. RESULTS. The design feature of the developed DV is the absence of an excitation coil, and its functional elements form a full-fledged measuring bridge, the arms of which include interturn capacitances of the windings of the first and second measuring coils, as well as capacitances formed by a metal cylindrical electrode with a coaxially located inside it ferromagnetic rod and the first lower rows of wire windings of the measuring coils. The bridge circuit operates in a resonant mode, which ensures the high sensitivity of the proposed sensor, and the quadrature conversion of the information signal provides the necessary level of noise immunity. The received signal is a functional dependence of the output voltage of the measuring bridge on the magnitude of external vibrations, the characteristics of the temporary realizations of which reflect the degradation processes occurring in the power transmission line supports. CONCLUSION. The proposed system for monitoring the integrity of power transmission line supports is actually a distributed real-time sensor network that implements PLC technology. The DV of each sensor module registers microvibrations of the structural elements of the corresponding power transmission line support, caused by natural disturbing factors during their operation, and converts them into an electrical information signal, which forms the basis of monitoring information about the current state of the power transmission line support structural elements.

A dual bubble layer model for reactant transfer resistance in alkaline water electrolysis

Alkaline water electrolysis (AWE) can only operate efficiently at a relatively low current density of up to 0.6 A cm–2 because bubbles cover the electrode surface at high current densities. Generally, the upper limit of current density in an electrochemical reaction is determined by the mass transfer of the reactant. Here, we propose a dual bubble layer model for the reactant transfer resistance of the oxygen evolution reaction in AWE. Using simple cylindrical nickel electrodes of different diameters, we conducted electrochemical impedance spectroscopy and microscopic observations with a high-speed video camera. The relationship between the polarization curve of the oxygen evolution reaction in AWE and the mass transfer resistance of hydroxide ions was investigated. At current densities above 0.5 A cm‒2, the bubble layer completely covered the electrode surface. This bubble layer consisted of two layers: an inner one formed by numerous primary bubbles generated on the electrode, and an outer one formed by coalesced large bubbles. The outer layer induces an additional solution resistance, Rsb. Changes in Rsb under various conditions were successfully explained by the thickness and void fraction of the bubble layer, conductivity of the solution, and tortuosity through the gap between bubbles. The inner layer resists the diffusion of hydroxide ions, and the resistance to hydroxide ion transfer through it (Rd) was modeled using the Warburg impedance element with a finite-length diffusion boundary. The charge-transfer resistance at the electrode surface (Rct) is roughly inversely proportional to the current density. This result indicates Rct is less sensitive to bubble coverage and almost all electrode surfaces are active in electrochemical reaction. The results showed that Rd increases with current density as much as Rct when the current density exceeds 1.0 A cm‒2. Up to a high current density of 2.5 A cm‒2, the change in polarization curve (ΔE/Δi) could be quantitatively explained by the sum of the bulk solution resistance, Rs0, additional solution resistance Rsb in the gaps between large bubbles, diffusion resistance Rd in the inner bubble layer, and charge-transfer resistance Rct at the electrode surface.

On Capacitance and Energy Storage of Supercapacitor with Dielectric Constant Discontinuity.

The classical density functional theory (CDFT) is applied to investigate influences of electrode dielectric constant on specific differential capacitance and specific energy storage of a cylindrical electrode pore electrical double layer. Throughout all calculations the electrode dielectric constant varies from 5, corresponding to a dielectric electrode, to 108 corresponding to a metal electrode. Main findings are summarized as below. (i): By using a far smaller value of the solution relative dielectric constant , which matches with the reality of extremely narrow tube, one discloses that a rather high saturation voltage is needed to attain the saturation energy storage in the ultra-small pore. (ii): Use of a realistic low value brings two obvious effects. First, influence of bulk electrolyte concentration on the is rather small except when the electrode potential is around the zero charge potential; influence on the curve is almost unobservable. Second, there remain the and enhancing effects caused by counter-ion valency rise, but strength of the effects reduces greatly with dropping of the value; in contrast, the and reducing effects coming from the counter-ion size enhancing remain significant enough for the low value. (iii) A large value of electrode relative dielectric constant always reduces both the capacitance and energy storage; moreover, the effect of the value gets eventually unobservable for small enough pore when the value is beyond the scope corresponding to dielectric electrode. It is analyzed that the above effects take their rise in the repulsion and attraction on the counter-ions and co-ions caused by the electrode bound charges and a strengthened inter-counter-ion electrostatic repulsion originated in the low value.

Development of a microkinetic model for non-oxidative coupling of methane over a Cu catalyst in a non-thermal plasma reactor

A surface microkinetic plasma model for non-oxidative coupling of methane into H2 and higher hydrocarbons was developed over a Cu catalytic film. Twenty key plasma species including electron, ions, radicals, and neutrals were considered in respective chemical reactions leading to the formation of C2 hydrocarbons onto the catalyst surface. The kinetic model was coupled with a global plasma model to describe the performance of a non-thermal plasma reactor. In the reactor model, the reactant gas flows between the two coaxial cylindrical metal electrodes with a length of 50 mm and a diameter of 2 mm (inner) and 6 mm (outer electrode) coated with a Cu film. The effect of discharge power, initial CH4 concentration, and inlet flow rate on methane conversion was investigated. The surface model shows that the CH4 conversion of 47% is obtained at a discharge power of 70 W with a selectivity of C2H2 (49%). Increase in power increased the conversion of methane while increase in pressure and/or inlet gas flow rate decreased it. Also, the results of the plasma-catalyst model were compared with those of plasma alone (without catalyst). It showed that presence of the catalyst inside the plasma increases the selectivity and yield of acetylene, while it deceases the selectivity and yield of hydrogen. Also, the density of radical CH3 in the plasma phase increased in the presence of catalyst, while CH2 and CH densities decreased with that.

Influence of ion structure and solvent electric dipole on ultrananoporous supercapacitor: a lattice model study

A five-state modified BEG model is proposed for describing electrolyte in polar solvent in cylindrical electrode pore in which only one row of particles can be stationed. Two properties the closest to the actual situation of the aqueous electrolyte are integrated into the model: cation is dimer comprised of two tangentially tethered hard spheres of different diameters: one is charged, while the other is neutral, and polar solvent is modeled as neutral hard sphere with an electric dipole. The system partition function is obtained by numerically solving maximum real root of characteristic equation of Kramers-Wannier transfer matrix. The model is used to investigate effects of ion structure and electric valence, solvent electric dipole, and cylindrical pore radius on specific differential capacitance and specific energy storage of the resulting supercapacitor. Main findings are briefly described below. (i) The dimer counter-ion electric valence does not exert obvious influence on the saturation value of the but reduces the threshold electrode potential strength beyond which the value is just reached. (ii) Whether the dimer counter-ion is monovalent or bivalent, the peak height and the value tend to rise with the dimer neutral site size decreasing, but influence of the value on the value is very small. Only when the value is small enough, the value rises a little with decrease of the value. (iii) Increase of solvent electric dipole moment (whether by increasing the dipole charge or dipole length) always raises the value, and enlarges width of the pure solvent domain or zero and zero domain around the zero electrode potential, but does not change the value obviously. (iv) With the pore size increasing, the value reduces and the value increases. So, using small size pore is favorable to improve the supercapacitor performance from the perspective of energy storage and electrode potential applied. (v) The three parameters: dipole charge, and dipole length, are cooperative in influencing the value.

The Impact of Burr Hole Device and Lead Design on Deep Brain Stimulation Lead Stability in Benchtop and Ovine Models

Background and ObjectivesA market-released deep brain stimulation (DBS) lead and burr hole device (BHD) have been used for more than ten years to provide stable DBS therapy using leads with four equally distributed cylindrical electrodes along the distal lead length. Newer directional leads cluster segmented electrodes at the center of the electrode array. This work tests the hypothesis that improved chronic translational and rotational stability through enhanced BHD design may ensure that these newer directional electrodes remain in a stable orientation near the stimulation target to maintain therapy and maximize opportunities to adjust therapy, if needed. Materials and MethodsA new DBS lead system (commercially available in the United States and termed “new” throughout the manuscript) has been developed, and a combination of bench testing (45 product samples tested) and chronic sheep studies (17 animals followed for 13.5 weeks on average) was conducted to test the hypothesis that design changes incorporated into the new DBS system further stabilize the position and orientation of a DBS lead tip compared with a legacy DBS system. ResultsThe new DBS system demonstrated a 55% relative improvement in chronic lead tip stability compared with the legacy DBS system with over a decade of clinical use. In a bench test, the new system required 79% more applied torque and 203% more lead body revolutions to rotate the lead in the BHD than the legacy system that was not designed to offer rotational stability. ConclusionsThese measurements quantitatively demonstrate that DBS system design can positively improve lead translational and rotational stability and show that system design is an important consideration for future product development.

Reduction of a Lithium-Ion Solid Electrolyte Model Under Potentiostatic Hold

Solid state electrolytes are becomingly increasingly attractive due to their improved safety, lower self-discharge, and higher power densities over the more commonly used liquid electrolyte [1,2]. Solid electrolytes are a relatively new material in the field of lithium-ion batteries, therefore there is considerably less mathematical investigation and analysis into these materials, compared with their liquid counterparts.We review a model for a solid electrolyte from thermodynamics principles [3]. We non-dimensionalise and scale the model to identify small parameters, where we identify a scaling that widens the boundary layer in the electrolyte compared to previous literature. We consider an Li2O solid electrolyte which is attached on each end by blocks of solid lithium. We fix a potential difference across the electrolyte and consider different charge flux conditions. We present asymptotic analysis and numerical solutions for both the zero-charge flux equilibrium and for the non-zero charge flux equilibrium problems. We consider numerical simulations of the full-time dependent problem and show that there are two important time scales in the problem, an early transient timescale where the boundary layers first approach their equilibrium followed by a longer timescale where we observe the transience in the bulk of the solution.We briefly talk about the application of a solid electrolyte to cylindrical nanowire electrodes. Recent advances in electrode chemistry have allowed for cylindrical nanowire geometries exhibiting low-capacity fade. However, the performance of these electrodes is very sensitive to experimental conditions and early charge behavior and thus it is important to understand the lithium transport process in these systems. Following from this work, we will combine the solid electrolyte model with a nanowire electrode in order to investigate these processes.

Thermo-Mechano-Electrochemical Analysis in Cylindrical Electrode Particles of Lithium-Ion Battery

A thermo-mechano-electrochemical model is proposed in this paper to study the coupled effect on diffusion induced stresses (DISs) in cylindrical electrode particles. The traditional heating model, Bernardi’s model, is modified to be practical in particle dimension. And the finite deformation theory as well as stress-induced diffusion hypothesis are also adopted to establish equations of the whole coupled system. By means of numerical simulation, the result of incipient thermal behavior shows significant dependence on both initial concentration of lithium-ion in the particle and capacity of heat interchange at particle surface. The DISs influenced by thermal behavior display amplification that is small (about 2% in 3C condition) but tend to increase with higher charging and discharging rate. Moreover, when temperature increase reaches 220 K, the result of DISs in the adiabatic model demonstrates prominent amplification which exceeds 12%. Therefore, thermal behavior is supposed to be taken into consideration when dealing with a quick-charging problem.

Application of Bioelectrochemical System and Magnetite Nanoparticles on the Anaerobic Digestion of Sewage Sludge: Effect of Electrode Configuration

Conventional anaerobic digestion is currently challenged by limited degradability and low methane production. Herein, it is proposed that magnetic nanoparticles (Fe3O4-NPs) and bioelectrochemical systems can be employed for the improvement of organic content degradation. In this study, the effect of electrode configuration was examined through the application of a bioelectrochemical system and Fe3O4-NPs in anaerobic digestion (AD). A microbial electrolysis cell with cylindrical electrodes (MECC) and a microbial electrolysis cell (MEC) with rectangular electrodes were compared against the traditional AD process. Biochemical methane potential (BMP) tests were carried out using digesters with a working volume of 800 mL charged with 300 mL inoculum, 500 mL substrate, and 1 g Fe3O4-NPs. The electrodes (zinc and copper) of both digesters were inserted inside the BMPs and were powered with 0.4 V for 30 days at 40 °C. The MECC performed better, improving degradability, with enhanced methane percentage (by 49% > 39.1% of the control), and reduced water pollutants (chemical-oxygen demand, total organic carbon, total suspended solids, turbidity, and color) by more than 88.6%. The maximum current density was 33.3 mA/m2, and the coulombic efficiency was 54.4%. The MECC showed a remarkable potential to maximize methane enhancement and pollution removal by adjusting the electrode configuration.

Enhancing the hydrophobicity of Ti–6Al–4V through multi-level electrical discharge texturing

ABSTRACT In the current work, single and multi-level micro-texturing on Ti–6Al–4V surfaces was performed through electrical discharge micromachining. The wetting properties of the single-level features obtained through EDMM have been studied, which revealed a higher water contact angle (CA) of ∼110° with respect to an untextured surface (water CA ∼38°). The concept of dimples overlapping (% of overlap between adjacent dimples) has been adopted to propose a novel technique for the simultaneous machining of multiple micro-features through a simpler cylindrical tool electrode, which otherwise necessitates multi-step fabrication or preformed tools. Adopting the proposed concept, multi-level textures consisting of micro-dimples surrounded by micro-pillars were machined on the Ti–6Al–4V surface. With multi-level textures, the water CA increases significantly compared to the untextured surfaces. The maximum water CA ∼ 104.2° was obtained with a 300 µm diameter tool and 25% dimple overlap, thereby rendering the surface hydrophobic.

ВПЛИВ ПАРАМЕТРІВ РУХУ ВОДИ НА ЕНЕРГОЕФЕКТИВНІСТЬ ЇЇ ОБРОБКИ ІМПУЛЬСНИМ БАР’ЄРНИМ РОЗРЯДОМ

A study of the energy efficiency of the pulsed barrier discharge during water treatment in the aerosol state depending on the energy of the pulses (21-72 mJ), their repetition rate (50-300 Hz), the concentration of organic impurities in water (50-100 mg / l) and water content (1.6−3.2%) in the water-air mixture. The discharge was generated by unipolar short pulses (~ 100 ns) in an electrode system with vertically arranged cylindrical electrodes with a diameter of 2 mm, the distance between which was 2 mm. The highest energy yield, which was obtained by decomposing the impurity by 90%, was 32 g / kWh. In order to determine the influence of water movement parameters on the energy efficiency of a pulsed barrier discharge under similar conditions, the energy efficiency of this type of discharge during water movement in film, drip and aerosol states was compared. It is concluded that water treatment should be carried out in the drip state on the submillimeter size of the drops. In the case of such water movement, the energy efficiency of the pulsed barrier discharge is ≈30% higher than in aerosol. References 15, figures 6, table 1.

Cold plasma treatment of porous scaffolds: Design principles

AbstractThree‐dimensional porous scaffolds have the potential to revolutionize a number of fields, including stem cell research, biomedical implants, tissue engineering, and regeneration, as well as energy technologies, filtration, and sensing. The ability to precisely engineer their surface properties is paramount to successful and enduring application. Plasma treatments promise to deliver homogeneous surfaces with tailored characteristics while generating few by‐products and not relying on the diffusion of liquids into a porous network. However, forming plasma inside complex interconnected pores is a significant challenge and requires much parameter fine‐tuning. This study uses numerical modeling to investigate key parameters which affect plasma breakdown and makes practical recommendations for achieving treatment homogeneity. We consider a dielectric barrier discharge (DBD) system, where nitrogen gas flows through a glass tube containing a porous scaffold, which is surrounded by a cylindrical electrode, with ground electrodes at either end of the tube. The parameters investigated include the scaffolds' pore size and porosity as well as electrode size and position. The results showed that homogeneous treatment is achieved by avoiding alternative breakdown pathways such as a poor seal between the scaffold and the glass containment tube, using a narrow supply electrode centered at the scaffold, and positioning ground electrodes as close as possible to the supply electrode without arcing. This strategy maximizes the electric field strength at a given voltage, allowing for higher pressures to be used, which in turn give a more homogeneous mean free path inside the pores.

Spatiotemporal Distribution of Electrically Evoked Spinal Compound Action Potentials During Spinal Cord Stimulation

ObjectivesRecent studies using epidural spinal cord stimulation (SCS) have demonstrated restoration of motor function in individuals previously diagnosed with chronic spinal cord injury (SCI). In parallel, the spinal evoked compound action potentials (ECAPs) induced by SCS have been used to gain insight into the mechanisms of SCS-based chronic pain therapy and to titrate closed-loop delivery of stimulation. However, the previous characterization of ECAPs recorded during SCS was performed with one-dimensional, cylindrical electrode leads. Herein, we describe the unique spatiotemporal distribution of ECAPs induced by SCS across the medial-lateral and rostral-caudal axes of the spinal cord, and their relationship to polysynaptic lower-extremity motor activation. Materials and MethodsIn each of four sheep, two 24-contact epidural SCS arrays were placed on the lumbosacral spinal cord, spanning the L3 to L6 vertebrae. Spinal ECAPs were recorded during SCS from nonstimulating contacts of the epidural arrays, which were synchronized to bilateral electromyography (EMG) recordings from six back and lower-extremity muscles. ResultsWe observed a triphasic P1, N1, P2 peak morphology and propagation in the ECAPs during midline and lateral stimulation. Distinct regions of lateral stimulation resulted in simultaneously increased ECAP and EMG responses compared with stimulation at adjacent lateral contacts. Although EMG responses decreased during repetitive stimulation bursts, spinal ECAP amplitude did not significantly change. Both spinal ECAP responses and EMG responses demonstrated preferential ipsilateral recruitment during lateral stimulation compared with midline stimulation. Furthermore, EMG responses were correlated with stimulation that resulted in increased ECAP amplitude on the ipsilateral side of the electrode array. ConclusionsThese results suggest that ECAPs can be used to investigate the effects of SCS on spinal sensorimotor networks and to inform stimulation strategies that optimize the clinical benefit of SCS in the context of managing chronic pain and the restoration of sensorimotor function after SCI.

Conical face-field electrostatic energy analyzers for investigating nanomaterials

The paper presents numerically calculated models of new electrostatic energy analyzers based on a conical face-field, which is restricted by concentric cylindrical (inner) and truncated-cone (outer) electrodes and two flat boundaries, perpendicular to the axis of symmetry. The calculated analyzers show good enough as energy resolution as well the acceptance characteristics, simple design ( without fringing fields) and provide wide abilities for analyzing surfaces of remote objects of different shape and size. Remote sensing allows use in various applications when is desirable to use a set of methods without mutual interference, what is useful tool's characteristic for investigating nanostructures.

Simulation and experimental study on the influence of bit structure on rock-breaking by high-voltage electro-pulse boring

High-voltage electro-pulse boring (EPB) rock-breaking can produce tensile damage, which has significant advantages in deep hard rock drilling. To develop a bit with high drilling efficiency and low energy consumption has become one technical problem in EPB technology. First, based on the electrode structure arrangement and the previous research on EPB mechanism, this paper developed three kinds of electrode bits with a coaxial cylindrical structure, electrode cross structure and multi-electrode pair structure. Second, it established a numerical simulation model of EPB with different-structure bits, and analyzed the influence of different structural arrangements on EPB. Based on the idea of parametric design of electrode bit parts, the influence of the high-voltage electrode shape on EPB was further analyzed. Finally, it built the EPB test units, and carried out the EPB tests of the bits with different structures, and made clear the influence of different structural arrangements on EPB. Compared with EPB experimental results, the bit with a coaxial cylindrical structure had the best drilling effect, followed by the one with a multi-electrode pair structure, and then the one with an electrode cross structure with the same setting of electrical parameters. At the same time, this paper made the EPB experiments on different high-voltage electrode shapes by using a coaxial cylindrical electrode bit. The results showed that the bit with a conical high-voltage electrode had the best drilling effect, followed by the one with a spherical high-voltage electrode, and then the one with a flat bottom high-voltage electrode. Through the simulation analysis and experimental study, this paper concluded the influence law of the bit structure on EPB. The application of the findings was helpful to guide the design of electrode bit structure, reduce energy consumption, and improve drilling efficiency.

Gap optimization of electrostatic aerial spray nozzles for low-speed aircraft

The gap between the spray plume and the cylindrical charging electrode for an aerial electrostatic spray nozzle is critical to achieve maximum chargeability of spray formulations prior to aerial applications of pest control products. Seven discrete gaps from the nozzle tip to the trailing edge of the electrode were tested for spray chargeability. A spray mixture of tap water and a non-ionic surfactant with an electrical conductivity of 1012.75 ± 6.70 μS was atomized through three different-sized nozzle tips (TXVK-3, TXVK-4, and TXVK-6) in a controlled high-speed wind tunnel operated at 6 different airspeeds between 80 and 177 km/h with two atomizing air pressures, 310 and 517 kPa, representing minimum and maximum values commonly used in rotary wing agricultural aircraft. The TXVK-3 nozzle yielded significantly higher charge-to-mass ratio (Q/M > 1.0 mC kg-1) compared to the TXVK-4 and TXVK-6 nozzles. At 310 kPa liquid pressure, the 6.5- and 9.3-mm gaps produced significantly higher spray charge. Data indicated that the chargeability of aerial electrostatic sprays can be improved using a smaller orifice and lower flow rate nozzle operated at a lower liquid pressure and higher airspeed. Results from this study may help aerial applicators better understand the optimum operational parameters required to maximize the electrostatic charge of spray formulations while flying low speed aircraft.

Detecting Methamphetamine in Aerosols by Electroanalysis in a Soap Bubble Wall.

We present a facile method to detect methamphetamine in aerosols by trapping aerosols in a soap bubble wall for electroanalysis. A microwire was placed through a soap bubble wall as a sensing electrode along with a 1 mm diameter platinum wire as the counter/reference electrode. The resulting electrochemical cell and electrode geometry are unique and allow for reproducible electrochemistry between bubble walls. We first provide a thorough investigation of the cell and electrode geometry and an electrochemical characterization of ferrocene methanol in a soap bubble wall composed of 0.1 M KCl and 0.1% Triton X-100 (v/v). To visualize the boundary where the bubble wets the microwire (the effective electrode area) with tens of nanometer resolution, we electrodeposited platinum on carbon microwire. Scanning electron microscopy and energy dispersive X-ray spectroscopy revealed the bubble contact (i.e., cylindrical electrode height) is 157 ± 30 μm. Correlated digital microscopy suggests that the wetting reaches r ∼ 125 μm along the bubble wall laterally from the microwire. Beyond the wetting region, the bubble thickness is 18 ± 1 μm, as indicated by ultraviolet-visible spectroscopy experiments probing dissolved bis(bipyridine)ruthenium(II) chloride. We illustrate that the voltammetric character in this system is highly dependent on the bubble wetting parameters, which are tuned by changing the microwire material. We then applied this system to the collection and electrochemical detection of methamphetamine in liquid aerosols, where the bubble wall acts as a low volume collector.

Rational Design and Numerical Analysis of a Hybrid Floating cIDE Separator for Continuous Dielectrophoretic Separation of Microparticles at High Throughput.

Dielectrophoresis (DEP) enables continuous and label-free separation of (bio)microparticles with high sensitivity and selectivity, whereas the low throughput issue greatly confines its clinical application. Herein, we report a novel design of the DEP separator embedded with cylindrical interdigitated electrodes that incorporate hybrid floating electrode layout for (bio)microparticle separation at favorable throughput. To better predict microparticle trajectory in the scaled-up DEP platform, a theoretical model based on coupling of electrostatic, fluid and temperature fields is established, in which the effects of Joule heating-induced electrothermal and buoyancy flows on particles are considered. Size-based fractionation of polystyrene microspheres and dielectric properties-based isolation of MDA-MB-231 from blood cells are numerically realized, respectively, by the proposed separator with sample throughputs up to 2.6 mL/min. Notably, the induced flows can promote DEP discrimination of heterogeneous cells. This work provides a reference on tailoring design of enlarged DEP platforms for highly efficient separation of (bio)samples at high throughput.

Propolis Integration Methods into Solutions for Highly Loaded Propolis Fibers by Needleless Electrospinning.

A load-bearing matrix filled with biologically active compounds is an efficient method for transporting them to the target location. Bee-made propolis has long been known as a natural product with antibacterial and antiviral, anti-inflammatory, antifungal properties, and anti-oxidative activity. The aim of the research is to obtain stable propolis/PVA solutions and produce fibers by electrospinning. To increase propolis content in fibers as much as possible, various types of propolis extracts were used. As a result of the research, micro- and nano-fiber webs were obtained, the possible use of which have biomedical and bioprotective applications. All used materials are edible and safe for humans, and fiber webs were prepared without using any toxic agent. This strategy overcomes propolis processing problems due to limitations to its solubility. The integration of different combinations of extracts allows more than 73 wt% of propolis to be incorporated into the fibers. The spinning solution preparation method was adapted to each type of propolis, and by combining the methods, solutions with different propolis extracts were obtained. Firstly, the total content of flavonoids in the propolis extracts was determined for the assessment and prediction of bioactivity. The properties of the extracts relevant for the preparation of electrospinning solutions were also evaluated. Secondly, the most appropriate choice of PVA molecular weight was made in order not to subject the propolis to too high temperatures (to save resources and not reduce the bioactivity of propolis) during the solution preparation process and to obtain fibers with the smallest possible diameter (for larger surface-to-volume ratios of nanofibers and high porosity). Third, electrospinning solutions were evaluated (viscosity, pH, conductivity and density, shelf life) before and after the addition of propolis to predict the maximum propolis content in the fibers and spinning stability. Each solution combination was spun using a cylindrical type electrode (suitable for industrial production) and tested for a stable electrospinning process. Using adapted solution-mixing sequences, all the obtained solutions were spun stably, and homogeneous fibers were obtained without major defects.