Inlet Hole Research Articles

Experimental Film Cooling Effectiveness of Three-Hole-Branch Circular Holes

A three-hole-branch geometry for film cooling is proposed. Each branch is made up of a streamwise 30°-angled circular hole with a circular hole of the same diameter on each side of it. These three holes share the same inlet area on the coolant supply side. Three side hole inclination angles of 30°, 37.5°, and 45° and three branch angles (the angle between the main and side holes) generated nine configurations that were tested for four blowing ratios of 0.5, 1, 1.5, and 2. To their benefits, these straight-through circular holes could easily be laser drilled on the airfoils or other gas turbine hot section surfaces. For comparative evaluation of these film hole geometries, the commonly used 7°-7°-7° diffusion hole geometry with the same inlet hole diameter was tested as a baseline under otherwise identical conditions. The pressure-sensitive paint (PSP) technique was utilized to test these geometries for their film cooling effectiveness. Depending on the branch geometry, for the same amount of coolant, some configurations were found to be superior to the baseline case for stream- or spanwise film cooling distributions while for the steeper side hole angles, these branched holes did not perform as well as the baseline case. The main conclusion is that the three holes with the same inclination angle of 30° exhibited the best film cooling effectiveness performance including the baseline geometry.

Novel electroosmotic micromixer configuration based on ion‐selective microsphere

In this paper, a micromixer of a new configuration is presented, consisting of a spherical chamber in the center of which an ion-selective microsphere is placed. Stratified liquid is introduced through the chamber via inlet and outlet holes under an external pressure gradient and an external electric field is directed in such a way that the resulting electroosmotic flow is directed against the pressure-driven flow, resulting in mixing. The investigation is carried out by direct numerical simulation on a super-computer. Optimal values of the applied electric field are determined to yield strong mixing. Above this optimal mixing regime, a number of instabilities and bifurcations are realized, which qualitatively coincide with those occurring during electrophoresis of an ion-selective microgranule. As shown by our calculation, these instabilities do not lead to an enhanced mixing. The resulting electroconvective vortices remain confined near the surface of the microgranule, and do not sufficiently perturb the stratified fluid flow further from the granule. On the other hand, another type of instability caused by the salt concentration gradient can generate sufficiently strong oscillations to enhance mixing. However, this only occurs when the external electric field is sufficiently high that the electroosmotic flow is comparable to the pressure-driven flow. This ultimately leads to creation of reverse flows of the liquid and cessation of the device operation. Thus, it was shown that the best mixing occurs in the absence of electrokinetic instability. Based on the data obtained, it is possible to select the necessary geometric characteristics of the micromixer to achieve the optimal mixing mode for a given set of liquids, which may be ten times more effective than passive mixers at the same flow rates. A comparison with the experimental data of the other authors confirms the effectiveness of this device and its other capabilities. Furthermore, the basic device design can be operated in other modes, for example, an electrohydrodynamic pump, a streaming current generator, or even a micro-reactor, depending on the system parameters and choice of an ion-selective granule.

Time-Accurate Evaluation of Film Cooling Jet Characteristics for Plenum and Crossflow Coolant Supplies

Abstract Gas turbine film cooling creates complicated and highly unsteady flow structures. This study seeks to examine the unsteady characteristics created by different cooling hole inlet geometries using a fast-response pressure-sensitive paint (PSP) technique able to capture time-accurate measurements at 2000 frames per second, resolving frequencies up to 1000 Hz. Time-accurate and time-averaged measurements are used to evaluate the performance of a plenum-style inlet and a crossflow-style inlet in varying turbulence environments over a flat plate. The results of this study are intended to begin the process of breaking down widely accepted time-averaged film effectiveness trends into the cumulative effects of freestream turbulence and momentum flux ratio, with emphasis on the cooling jet motions they cause. Jet behaviors observed in this study include a sweeping oscillation, unsteady attachment and separation from the plate, and time-accurate and time-averaged flow bias. Cooling hole inlet geometry and momentum flux ratio affect the core of the jet, and freestream turbulence affects the periphery of the jet. Crossflow-fed cooling holes show bias to the upstream side of the cooling hole with respect to the internal crossflow direction. Plenum-fed cooling holes outperform crossflow-fed cooling holes, and the difference grows with increasing momentum flux ratio. The frequency of both plenum- and crossflow-fed cooling jet motions is influenced by the freestream turbulent velocity fluctuations. The resulting mode shapes show dominant side-to-side sweeping for higher turbulence environments and a separation and reattachment motion for lower turbulence environments. At higher momentum flux ratio, the jets were seen to increasingly favor separation and reattachment motions. The results of this study are intended to better inform existing predictive tools. With a better understanding of the time-accurate behaviors responsible for creating the commonly accepted time-averaged coolant distributions, simple predictive tools may be better equipped to accurately model film cooling flows.

NDIR CO2 gas sensing using CMOS compatible MEMS ScAlN-based pyroelectric detector

We demonstrate NDIR CO2 gas sensing using CMOS compatible MEMS ScAlN-based pyroelectric detectors. The ScAlN-based pyroelectric detectors are fabricated using 8-inch wafer level technology with 12 % Sc-doped AlN deposited at a temperature of ∼200 °C. Together with a blackbody thermal emitter, a 10 cm long enclosed gas channel with only inlet and outlet holes connected to tubings, and testing using 2 different reference gases (N2 and synthetic air), measurements show voltage signal drop due to CO2 gas absorption at the 4.26 μm wavelength at CO2 gas concentrations ranging from 5000 ppm down to 25 ppm. The signal change due to the CO2 gas response ranges from ∼2% at 100 ppm CO2 concentration to ∼40 % at 5000 ppm CO2 gas concentration for both CO2 gas measured in N2 and in synthetic air. CO2 gas response times are also measured for CO2 gas in N2 and in synthetic air at concentrations of 5000 ppm, 1000 ppm and 400 ppm. The gas response times measured around 2 s and lower. Introduction of humidity show some minor effect (<3%) to the CO2 gas response and seems most perturbed at 10 % relative humidity. To the best of our knowledge, this is the first demonstration using ScAlN-based pyroelectric detectors in NDIR CO2 gas sensing, towards practical sensor applications. The results obtained show promise in using CMOS-compatible MEMS ScAlN-based pyroelectric detectors for NDIR gas sensing, opening up possibilities for low cost, wafer-level, monolithic NDIR gas sensors with small footprint integrated with CMOS circuits.

Sustainable ways of biogas production using low-cost materials in environment

Biogas production is an anaerobic process involving various microbes such as methanogenic bacteria and Clostridium acteinum, Bacteriodes ruminicola, Lactobacillus spp, Streptococcus spp. Farmers of Indonesia are not interested in biogas production due to higher costs in establishing biogas plants. In our present research was focused on production of biogas and biofertilizers from biogas plants in separate studies. Our research forms a basis for production of biogas from low cost material available in environment. Important factors determining good quality biogas are: waste quality, digester design, temperature, system operation, presence of oxygen. In our present study, we have considered two factors as different wastes and design of biogas plants. Further, different kinds of wastes including plant wastes were used. Two designs of digester were used in the present study Raw materials used in our present study are chicken manure, chicken manure while from plants used straw (Oryza sativa), cabbage (Brassica oleracea) waste and water hyacinth (Eichhornia crassipes). Materials for biogas plant were gallon water cylinder, plastic bag, plastic hose, water faucet, motorcycle tyre and glue. The biogas plant differed in being an anaerobic fermentation unit. One biogas plant using motor tires as a gas container of anaerobic fermentation process while others use plastic bags. Refinement of the other part is carried out during the study such as inlet and outlet holes where there were 4 points and to be 2 hole points. Reducing the hole on biogas plant can reduce the leakage of the resulting gas. The parameters measured are the length of the gas produced by the flame test, gas volume in 15 days and the fire color. The total volume of mixture is 12 liters, its contain of 6 liters’ water and 6 liters the mixture manure and plant. Ratio of mixture between animal manure and plant are 6:0; 4:2; 3:3; 2:4; 0:6. The result show that the using of biogas plant with plastic bag is better than the using of motorcycle tires. From statistical analysis generally showed that the best mixture of yield was 3: 3 mixture based on gas production parameters and flame color. Comparatively, mixture chicken manure and goat manure had the best result for gas production.

Optimization of flow field in electrochemical trepanning of integral cascades (Ti6Al4V)

Ti6Al4V is widely applied in the integral cascades of aero engines. As an effective machining method, electrochemical trepanning (ECTr) has unique advantages in processing surface parts made of hard-to-cut materials. In ECTr, the state of the flow field has a significant effect on processing stability and machining quality. To improve the uniformity of the flow field when ECTr is applied to Ti6Al4V, two different flow modes are designed, namely full-profile electrolyte supply (FPES) and edges electrolyte supply (EES). Different from the traditional forward flow mode, the flow directions of the electrolyte in the proposed modes are controlled by inlet channels. Simulations show that the flow field under EES is more uniform than that under FPES. To further enhance the uniformity of the flow field, the structure of EES is optimized by modifying the insulating sleeve. In the optimized configuration, the longitudinal distance between the center of the inlet hole and the center of the blade is 6.0 mm, the lateral distance between the centers of the inlet holes on both sides is 16.5 mm, the length to which the electrolyte enters the machining area is 1.5 mm, and the height of the insulating sleeve is 13.5 mm. A series of ECTr experiments are performed under the two flow modes. Compared with EES, the blade machined by FPES is less accurate and has poorer surface quality, with a surface roughness (Ra) of 3.346 μm. Under the optimized EES, the machining quality is effectively enhanced, with the surface quality improved from Ra = 2.621 μm to Ra = 1.815 μm, thus confirming the efficacy of the proposed methods.

Performance of Low Air Volume Dry Powder Inhalers (LV-DPI) when Aerosolizing Excipient Enhanced Growth (EEG) Surfactant Powder Formulations.

Efficient delivery of dry powder aerosols dispersed with low volumes of air is challenging. This study aims to develop an efficient dry powder inhaler (DPI) capable of delivering spray-dried Survanta-EEG powders (3-10 mg) with a low volume (3 mL) of dispersion air. A series of iterative design modifications were made to a base low air volume actuated DPI. The modifications included the replacement of the original capsule chamber with an integral dose containment chamber, alteration of the entrainment air flow path through the device (from single-sided (SS) to straight through (ST)), change in the number of air inlet holes (from one to three), varying the outlet delivery tube length (45, 55, and 90 mm) and internal diameter (0.60, 0.89, and 1.17 mm). The modified devices were evaluated by determining the influence of the modifications and powder fill mass on aerosol performance of spray-dried Survanta-EEG powders. The optimal DPI was also evaluated for its ability to aerosolize a micronized powder. The optimized dose containment unit DPI had a 0.21 mL powder chamber, ST airflow path, three-0.60 mm air inlet holes, and 90 mm outlet delivery tube with 0.89 mm internal diameter. The powder dispersion characteristics of the optimal device were independent of fill mass with good powder emptying in one 3 mL actuation. At 10 mg fill mass, this device had an emitted mass of 5.3 mg with an aerosol Dv50 of 2.7 μm. After three 3 mL actuations, >85% of the spray-dried powder was emitted from the device. The emitted mass of the optimal device with micronized albuterol sulfate was >72% of the nominal fill mass of 10 mg in one 3 mL actuation. Design optimization produced a DPI capable of efficient performance with a dispersion air volume of 3 mL to aerosolize Survanta-EEG powders.

Simulation Analysis and Parameter Optimization of The Electronic Controlled Injector

In order to improve the dynamic response characteristics of the electronic controlled injector, a simulation model for the response characteristics of the electronic controlled injector was established. By comparing the calculation results of the simulation model with the experimental results, the validity and accuracy of the model are verified. The influence of inlet hole diameter, outlet hole diameter and needle valve diameter on the dynamic response characteristics of the needle valve of the electronic control injector was studied. The results show that the closing delay time of the needle valve decreases with the increase of the inlet hole diameter of the control chamber, the opening delay time of the needle valve decreases with the increase of the oil outlet diameter of the control chamber, and the closing delay time of the increase of the diameter of the needle valve and the opening delay time decreases. An orthogonal experiment with three factors and four levels was designed to optimize the structural parameters of the electronic control injector. The optimized results show that the dynamic response characteristics of the injector are improved.

On the quality of micromixing in an oxy-fuel micromixer burner for gas turbine applications: A numerical study

The study examines numerically the non-reacting flow and mixing characteristics inside a single tube of a micromixer burner for potential zero-emission premixed oxy-fuel combustion applications, such as gas turbines. The aim is to investigate how the geometrical parameters can affect the mixing quality in an oxy-fuel reactant mixture consisting of CH4, O2, and CO2. The ranges of design parameters are fuel inlet diameter (from 0.2 to 1.0 mm), number of fuel holes (4 and 6), and tube length (from 5D to 15D). It was found that the mixing quality is significantly improved by increasing the tube length. The results also showed that mixing quality is not directly dependent on fuel hole size but on the ratio of main flow to jet flow momenta. At fixed total fuel mass flow rate, the mixing quality depreciates when the number of fuel holes is increased from four to six for all hole diameters, except for the smallest one of 0.2 mm. The peak mixing quality was achieved with fuel hole diameters of 0.25 mm and 0.2 mm for the micromixer tubes with four and six inlet holes, respectively. The results showed that micromixers can achieve high mixing quality at a reasonable burner height.

Optimal Design of Hemispherical 7-Hole Probe Tip With Perpendicular Holes

The 7-hole probe measurement system is mainly used to measure three-dimensional flow fields. During the measurement, the probe head was in direct contact with the measured object, and the head structure had a significant influence on the accuracy of the flow field measurement. The main influencing factors were the hole opening mode, hole position, and hole diameter. For a hemispherical 7-hole probe with perpendicular and forward-facing holes, orthogonal experiments with three levels and three factors (inflow velocity, hole position, and hole diameter) were designed, and additional experiments were conducted on the significant factors. The importance of factors was evaluated based on the correlation between different structural parameters and the pressure coefficient. The experiment was simulated using FLUENT, and the numerical simulation results demonstrated that the square of deviance at the inlet velocity, hole diameter, and hole position was 0.0018, 0.0013, and 0.3611, respectively. The position of the hole has a significant influence on the measurement results, but the influence of the inflow velocity and hole diameter is negligible, and the pressure coefficient is the smallest when the hole is at 45°. For the hemispherical 7-hole probe with forward facing hole, the hole is the best at approximately 45°, and considering the convenience of processing, the diameter of the hole can be selected as the diameter of the 1/10 probe.

FEATURES OF SOUND GENERATION BY THE JET-DRIVEN HELMHOLTZ OSCILLATOR

Experimental studies the model of a jet-driven Helmholtz oscillator has been carried out. The oscillator is a cylindrical chamber, closed on the sides by two covers with inlet and outlet holes. The oscillator was excited by a stream of airflow. The influence of the geometric dimensions of the chamber and the openings in the covers on the amplitude of pressure fluctuations was studied and the optimal channel configuration was determined. Particular attention is paid to the study of the influence on the amplitude of pressure fluctuations of the shape and size of the nozzle - the hole in the front cover. There were measured the following processes: the pressure drop across the nozzle, to calculate the speed of the jet at the chamber entrance, and the parameters of pressure fluctuations in the chamber, to plot the amplitude-frequency spectra. There were made certain observations of a jet tone appearance and acoustic modes excitation at the natural frequency of the chamber-resonator with a smooth increase in the jet velocity. The relationship between the jet tone and the resonant in the chamber is noted. Recommendations for designing a Helmholtz jet oscillator are presented.

Prediction of the Unsteady Turbulent Flow in a Solar Air Heater Test Bench

In this work, the unsteady turbulent flow in a new solar air heater test bench, developed in our LASEM laboratory, was predicted. The considered system consists of two passages solar air heater separated by an absorber and powered by a fan working in a delivery mode, placed in the hole inlet side the insulation. On this system, a glass is hanging on the front side and an absorber is inserted inside. On the glass side, it is connected to the box prototype through a pipe. The hot air flow is routed towards the box prototype. Two circular holes, are located in the same face of the box prototype. The inlet hole allows the hot air supply. However, the outlet hole allows its escape into the ambient environment. By using the ANSYS Fluent 17.0 software, the Navier-Stokes equations coupled with the standard k-ω turbulence model were resolved. The numerical results were compared with our experimental data, established in the second passage of the solar air heater test bench. The good agreement confirms the validity of the numerical method. The range of temperatures is very useful in many applications such as industrial and domestic applications.

Numerical simulation and optimization of cooling flow field of cylindrical cathode with annular magnetic field

In order to solve the problems of unstable discharge, low deposition rate and large difference in ionization rate between different targets in high power impulse magnetron sputtering, a novel cylindrical cathode with annular magnetic field based on hollow cathode effect is proposed, which can be used to produce ion beam with high ionization rate, high plasma density and no large particles. However, the traditional channel structure could not guarantee its high efficiency and uniform heat dissipation. The sealing ring may be damaged by ablation due to high power density, which restricts the further improvement of power density. Therefore, it is necessary to optimize the design of the channel structure. SolidWorks flow simulation software is used to simulate the cooling channel of plasma source. The influence of water hole structure parameters on cooling effect is analyzed, including distribution angle, hole number, diameter and inlet hole height. And the channel structure parameters are optimized. The results show that the increasing of the circumferential distribution range of the water hole is beneficial to the uniformity of heat dissipation, ensuring a large temperature difference between cooling water and copper sleeve, and strengthening heat exchange. The water inlet hole set in the upper layer of the structure is conducive to alleviating the temperature stratification phenomenon of the cooling water, so that the copper sleeve and sealing ring are in good cooling condition. Appropriately reducing the aperture is beneficial to increasing the cooling water jet velocity, enhancing the jet impact effect, and then increasing the turbulence degree, strengthening the heat transfer and improving the heat transfer efficiency. By systematically studying the influencing factors, the optimized cooling flow field structure of cylindrical cathode with an annular magnetic field is obtained. The distribution angle is 30°, the number of holes is 6, the aperture is 4 mm, and the height of water inlet hole is 36 mm. The optimized channel structure can improve the utilization rate of cooling water, obtaining better cooling effect at the same flow rate, and improving the discharge stability of the plasma source, which provides a basis for designing the cooling structure of the cylindrical cathode with annular magnetic field.

External limiting membrane angle as a composite predictive index for post-operative ELM closure in full thickness macular holes

To evaluate pre-operative qualitative and quantitative parameters of external limiting membranes (ELM) and other associated full thickness macular holes (FTMH) features and their predictive values for post-operative anatomical and functional outcomes. This was a retrospective study of 48 eyes that underwent vitrectomy with internal limiting membrane (ILM) peeling for FTMH and had type 1 closure. All subjects underwent optical coherence tomography (SDOCT, Heidelberg, Spectralis), and the eyes were divided into complete ELM closure (CEC) and incomplete ELM closure (IEC) groups based on the post-operative OCTs within 2months, and ROC curves were used to estimate which of the pre-operative parameters could best predict eyes falling in the CEC group. The mean pre-op ELM defect was smaller in CEC group (594μm vs 1126μm, p< 0.001) and so was the pre-op EZ defect (770μm vs 1186μm, p= 0.001). The mean ELM angle also was smaller in the CEC group (51.6° vs 102.5°, p< 0.001) and so was the mean hole inlet distance (353μm vs 596μm, p< 0.001). The post-operative ELM defect showed a significant negative correlation with visual acuity (r= - 0.319; p= 0.027). The ELM angle was most predictive with an AUROC of 0.958, and a cut-off of 68.3° had a sensitivity of 90% and a specificity of 89%. Our study introduces a novel parameter called the ELM angle and proves that it has a high sensitivity and specificity in predicting complete ELM reformation post-surgery in the short term as well as the long term.

Computational study and experimental validation on the effect of inlet hole surface on airflow characteristics and thermal comfort in a box occupied by a thermal manikin

In an indoor environment, many factors may affect the airflow characteristics and thermal comfort. Hence, a lot of research has been carried out in order to investigate the impact of these factors. The purpose of this study is to determine the effect of supply area, with maintaining the same supply airflow rate, on the airflow characteristics and the indoor thermal comfort for a ventilated box prototype occupied by a thermal manikin. Understanding the behavior of the airflow in a mechanical ventilated box occupied by a thermal manikin is the main objective of this paper. Hence, numerical simulations were carried out using the software ANSYS FLUENT 17.0. According to the obtained results, the inlet velocity has a direct effect on the velocity fields, the temperature, the static pressure and the turbulence characteristics. In addition, the numerical results affirmed that the supply area has a direct impact on indoor thermal comfort.

A Semi-Dissolving Microneedle Patch Incorporating TEMPO-Oxidized Bacterial Cellulose Nanofibers for Enhanced Transdermal Delivery.

Although dissolving microneedles have garnered considerable attention as transdermal delivery tools, insufficient drug loading remains a challenge owing to their small dimension. Herein, we report a one-step process of synthesizing semi-dissolving microneedle (SDMN) patches that enable effective transdermal drug delivery without loading drugs themselves by introducing TEMPO-oxidized bacterial cellulose nanofibers (TOBCNs), which are well dispersed, while retaining their unique properties in the aqueous phase. The SDMN patch fabricated by the micro-molding of a TOBCN/hydrophilic biopolymer mixture had a two-layer structure comprising a water-soluble needle layer and a TOBCN-containing insoluble backing layer. Moreover, the SDMN patch, which had a hole in the backing layer where TOBCNs are distributed uniformly, could offer novel advantages for the delivery of large quantities of active ingredients. In vitro permeation analysis confirmed that TOBCNs with high water absorption capacity could serve as drug reservoirs. Upon SDMN insertion and the application of drug aqueous solution through the drug inlet hole, the TOBCNs rapidly absorbed the solution and supplied it to the needle layer. Simultaneously, the needle layer dissolved in body fluids and the drug solution to form micro-channels, which enabled the delivery of larger quantities of drugs to the skin compared to that enabled by solution application alone.

Investigation of Thermohydraulic Characteristics of Vortex Chambers

Local flow swirling is used in power facilities and other technical devices. It is an effective means for acting on the air flow structure and can enhance heat transfer. A swirled flow in axisymmetric channels belongs to the group of 3D flows in the field of centrifugal mass forces. It is characterized by the ratio of two (axial and rotational) or, in some cases, three components of the velocity, the presence of transverse and longitudinal pressure gradients, and high turbulent fluctuations that bring about certain difficulties in the investigation of processes occurring in a swirled flow and it complicates detection of their regularities. Therefore, it is proposed to install a vortex chamber (VC) at the leading edge of a blade or vane of a high-temperature gas turbine. Temperature conditions and flow capacity of VC models were studied by a calorimetric method in a liquid-metal thermostat. The regularities of heat transfer rate on the surface of the cooling channels were determined depending on the number and diameter of inlet (supply) and outlet holes for various pressure drops. The VK designs were optimized considering the effect of their geometry on the formation of various swirl flow structures with different levels of heat transfer enhancement. An analysis was performed with account taken of the throughput capacity of the models. The criterial dependences of the Nusselt number vs. Reynolds number Re were obtained for three VC designs for direct- or reverse-flow direction. The highest heat fluxes were observed on the section of coolant supply via holes, which is explained by a high velocity of the initial flow swirling. Flow swirl breakage and cooling air heating are the cause of a decrease in the relative heat transfer coefficient $${\bar {\alpha }}{\text{.}}$$ The self-similarity mode is observed at a pressure ratio across the vortex chamber above 1.4. The thermal problem was solved using data of the hydraulic tests of the models with air blowing under isothermal conditions. The results of experimental studies can be included in the data bank of heat and mass transfer software products to reduce the labor intensity and time in the development of a cooling system for blades/vanes of high-temperature gas turbines.

Study on electrode vibration in the touch-down stage of fast electrical discharge machining drilling

Fast EDM (electrical discharge machining) drilling is broadly used in the manufacturing industry. When drilling inclined holes, the machining efficiency in the touch-down stage is much lower than that of drilling normal holes for a general-purpose fast EDM drilling machine. To uncover the reasons, this paper conducted observations of inclined hole drilling processes by using a high-speed video camera. It was found that the vibration of the tubular tool electrode was the major factor that led to the unstable state, resulting in low machining efficiency. And the vibration was driven by the discharge reaction force and the hydrodynamic force. The vibration enlarged the gap width and caused open circuit pulses, which misled the servo control system to feed the electrode downward. The overfeeding eventually caused short circuits and the subsequent retraction of the electrode. The iterative feeding and retraction of the electrode resulted in low machining efficiency. Then a fluid-structure interaction (FSI) model was built to analyze the vibration behavior. The impacts of the inner flow speed and the free length of electrode were studied with the model. It was found that the vibration is inevitable on general-purpose fast EDM drilling machines. Finally, to reduce the vibration impact, a new gap servo control strategy for the touch-down stage was proposed. The strategy adjusts the reference gap voltage by fuzzy rules. Experimental results showed that with the new gap servo control strategy, the performance was improved in the touch-down stage, with the machining efficiency improved by 38.75% and the area of discharge affected zone around the hole inlet reduced by 13.44%.

Extracellular matrix permeability/efficacy assay tip (E-PAT) to realize three-dimensional cell-based screening

In this work, an extracellular matrix permeability/efficacy assay tip (E-PAT), which can be used in a conventional pipette to simultaneously test drug permeability and efficacy, was developed by growing cells in the extracellular matrix (ECM) layer in a hole at the outlet (bottom) of E-PAT. In the existing permeability/efficacy assay technique conducted using the transwell assays, the Cell/ECM layers were formed on permeable polymer membranes; however, the production of small membranes to realize transwell miniaturization is expensive and difficult. To resolve this issue, in the proposed approach using E-PAT, small Cell/ECM layers were formed in the hole at the outlet (bottom) of the tip without membranes. A pipette was connected to the E-PAT to easily aspirate the Cell/ECM mixture into the hole of the tip, allowing the formation of miniature Cell/ECM layers at the bottom of the tip. Subsequently, the E-PAT was detached from the pipette and dipped into a well filled with media. The cells in the ECM grew three-dimensionally and made Cell/ECM layer in the E-PAT. The permeability/efficacy assays were performed using the Cell/ECM layer in E-PAT. The compounds or nanoparticles supplied through the inlet (hole) at the top of the E-PAT penetrated the Cell/ECM layers and were diluted by the media in the well. By measuring the concentration of the compounds or nanoparticles in the well and the cell viability in the Cell/ECM layer, the permeability and efficacy/cytotoxicity of the compounds in the proposed E-PAT could be concurrently estimated with a high throughput. In particular, E-PAT measured the IC50 (half maximal inhibitory concentration) for 3.383 μM doxorubicin (DOX) and indicated that 73 % 4 μM DOX penetrated the Cell/ECM layers, inducing the death of 57.2 % HepG2 cells. Moreover, the device demonstrated that FITC-SiO2 nanoparticles with a diameter of 25 nm permeated higher into the ECM and killed more HepG2 cells under the serum (fetal bovine serum, FBS) free media conditions than under the serum containing media conditions. The E-PAT could thus measure the compound efficacy as well as the compound permeability. The proposed tip can be a valuable tool to determine whether the efficacy/cytotoxicity of a compound is because of its low permeability.

Influence of geometrical parameters of air inlet hole on the kinematic characteristics of jet

While considering air exchange scheme in rooms with heat dissipations, it is often preferred when jet flows directly into the working area. It is necessary to take into account the influence of irregularities of velocity profiles in jets that are formed at the outflow from nozzle with different geometry. The jet outflow from inlet holes located beyond elbow was numerically studied. The influence of geometrical parameters of inlet hole on the jet characteristics was investigated.The characteristic flow streamlines for several geometries of a horizontal nozzle, the main characteristics of jet outflow were computed. The relationship between the inlet hole location relative to elbow and the outflow jet characteristics were determined. It was revealed that when the inlet hole is located in close proximity to the elbow, the velocity profiles have strong irregularities, and the jet outflows at an angle to the horizon. When the distance between the hole and the elbow increases, the jet strengthens, the transversal component of velocity does not affect the jet, the outflow angle tends to horizontal.The obtained results can be used for calculating the circulation of air masses in ventilated rooms.