Delivery Tube Research Articles

Effects of delivery tube configuration regarding the gas atomization for preparing Fe-based amorphous powders: Numerical and experimental investigation

The volume of fluid (VOF) model and the discrete phase model (DPM) were adopted for primary and secondary atomization processes, respectively. The effects of the inlet-limited delivery tube geometry on the flow field, melt breakup and particle cooling were then investigated. The results show that under the delivery tube extrusion length of 5 mm, the suction effect and the breakup efficiency can be improved, and the risk of freeze-off can be inhibited. With the decrease of the delivery tube diameter from 2.5 to 1.5 mm, the calculated median diameter is decreased by more than half and the average cooling rate is more than doubled. The industrial trial results under different delivery tube diameters match the simulation results, and the stable casting of melt with low flow rate can be realized by adopting the inlet-limited delivery tube. When the delivery tube diameter is 1.5 mm, the amorphous powder has a median diameter of 38.9 μm and optimal soft magnetic properties with saturation magnetization of 135.0 emu·g−1 and coercivity of 0.26 Oe.

Optimization of the gas system for gas–water combined atomization technique in FeSiBC amorphous powder production

The gas–water combined atomization is an advanced technology for Fe-based amorphous powder preparation, and its gas/water system parameters have significant impacts on powder properties. In this study, numerical simulations and industrial trials were combined to optimize the gas atomization parameters. The results showed that increasing the atomization pressure promotes the transition of the flow field to the closed wake. Moreover, the median particle size was significantly refined and the cooling rate was improved. Extending the extrusion length facilitated the decrease in suction pressure, while excessively long extrusion lengths led to instability in the atomization process. The decrease in delivery tube diameter enhances droplet breakup and cooling, but increases the risk of clogging. Industrial trials at different atomization pressures showed that low atomization pressure led to the formation of needle-shaped powder, and the FeSiBC amorphous powder prepared at 3.0 MPa exhibited optimal comprehensive properties, with saturation magnetization of 166.1 emu·g−1 and coercivity of 4.5 Oe.

Clogging of the delivery tube during preparation of copper powder by vacuum atomisation: coupling analysis of flow resistance and heat transfer

ABSTRACT During the production of micro-fine powders using gas atomization technology, the problem of clogging of the delivery tube is often encountered. Flow resistance inside the delivery tube and heat transfer of the delivery tube is one of the critical factors causing the clogging of the delivery tube. In this paper, the volume of the fluid model (VOF) coupled with the discrete phase model (DPM) were used to simulate the delivery tube-clogging process of the delivery tube involved in atomizing copper powder. The results indicate that, with the increase in the length of the delivery tube, the flow resistance increased; Shortening the length of the tube reduces the flow resistance and increases the superheat of the melt, the atomization process is uninterrupted. The atomized powder was qualitatively determined by standard deviation to determine the number of satellite balls. This research has guiding value in understanding the continuity of the atomization process.

PRODUCTION OF Ni-HARD ALLOY POWDERS BY GAS ATOMIZATION

Ni-Hard cast iron materials are frequently used in equipment where high wear resistance is required in industrial applications. Generally, Ni-Hard is produced by conventional casting techniques. In this study, it was aimed to produce Ni-Hard powders to produce Ni-Hard cast iron materials with additive manufacturing techniques. To produce spherical and fine raw materials for additive manufacturing techniques, the gas atomization technique with a close-coupled nozzle system was preferred for the production of Ni-Hard powders. Ni-Hard alloy was melted in a high-frequency 10kW induction furnace under a protective atmosphere integrated into the gas atomization system. During the atomization process, 150 °C superheating was applied to prevent the liquid metal from freezing and clogging the melt delivery tube. In terms of the continuity of the atomization process, the negative pressure (aspiration pressure) values formed at the end of the melt delivery tube at different gas pressures were measured. An aspiration pressure of -50 mbar was obtained under an atomization pressure of 35 bar. Particle size distributions, hall flow behaviour and angle of repose properties of the produced powders were determined. Finally, the characterization of the powders was carried out by scanning electron microscopy. It was determined that the powders obtained as a result of atomization exhibited a spherical morphology and a narrow size range. The Hall flow rate test result of Ni-Hard powders was measured as 22 seconds for 50 g.

Evaluation of Physical Properties of Maize and Pigeonpea Seeds for Seed Metering Mechanism

Physical properties of seeds such as size, shape, bulk density, angle of repose and thousand seed mass are important design parameters for seed metering mechanism. Some of the physical properties of maize and pigeonpea seeds were determined as they are crucial factor for effective planting. The average values of length, width, thickness, geometric mean diameter, sphericity, bulk density, angle of repose and thousand seed mass of maize were found as 9.79 ± 0.33 mm, 8.03 ± 0.39 mm, 4.16 ± 0.32 mm, 6.89 ± 0.26 mm, 0.70 ± 0.03, 0.76 ± 0.01 g/cm3, 26.54° ± 0.60 and 223.91 ± 1.50 g respectively at moisture content of 10.90 ± 0.03% on dry basis while similar values for pigeonpea were 6.94 ± 0.31 mm, 5.61 ± 0.30 mm, 4.99 ± 0.27 mm, 5.79 ± 0.19 mm, 0.82 ± 0.03, 0.82 ± 0.01 g/cm3, 28.36° ± 0.44 and 136.64 ± 1.56 g respectively at moisture content of 11.24 ± 0.04% on dry basis. The determined properties were found relevant to the design of the components of planter. The size of cell and delivery tube were relevant to linear dimensions while bulk density and angle of repose were relevant to hopper design.

Numerical and experimental investigation of close-coupled twin-nozzle gas atomization towards fine high-entropy alloy powder production

The close-coupled nozzle is key to controlling the particle diameter and powder defects such as satellite particles during the production of metal powders via vacuum induction melting gas atomization (VIGA). However, new nozzle structures with greatly improved fine particle yields and morphologies are needed. Also, there is a limited understanding of how gas atomization refines particles and forms satellite particles. Therefore, we developed a novel close-coupled twin-nozzle and revealed the effect of different primary and secondary pressures on the gas flow field, melt atomization, and particle characteristics (particle diameter, sphericity, and satellite particles). This approach involved both numerical simulations and experiments during the production of an AlCoCrFeNi2.1 alloy. The results showed that the particle diameter and distribution width decreased under various combinations of process parameters. This was because of the combined actions of the gas recirculation zone in the air, where the vortex was close to the bottom wall of the delivery tube and a gas jet. The yield of fine particles in the ≤ 45 µm range produced by the twin-nozzle increased to 79.25% from 55.55% upon increasing the secondary pressure from 1.0 MPa to 2.0 MPa, achieving up to a 34.12% higher fine particle yield compared with the conventional single-nozzle. In addition, as the secondary pressure of the twin-nozzle was increased, the number of satellite particles decreased, which also affected the proportion of L12/B2 phase within the powder, causing the Vickers microhardness to decrease and then increase as the particle diameter increased.

Redesigning of Asella Animal Drawn Wheat Row Planter

This study was undertaken to redesign, fabricate, and evaluate the performance of animal-drawn seed drill prototype capable of drilling wheat and barley seeds and applying fertilizer at predetermined row spacing and depths. The physical properties of seeds involved in the study were investigated to optimize the design of the seed drill’s components. The developed seed drill machine, consists of a frame, seed and fertilizer hopper, seed metering devices, seed delivery tube, adjustable furrow opener, and drive wheels. The performances were evaluated in terms of Seed and fertilizer rate, row spacing, depth of seed placement, plant count/stand, field capacity and field efficiency. The investigation revealed that the sphericity of Hidase, Digelu, Ogolcho, and Kekeba wheat varieties were 65.81 %, 64.79% and 62.62 %, respectively. Row-to-row spacing can be 20 cm and depth also adjustable to 5 to 7 cm as per wheat agronomic requirements. The developed four row animal drawn seed drill was tested in the laboratory and field. The seed rate was calibrated and observed that 127 kg/ha with a middle flap position adjustment lying in the acceptable range of the recommended seed rate. There was no visible damage observed. The mean field capacity and field efficiency were 0.112 ha/hr and 81.78% at speed of 1.71km/hr. 310 to 318 plant populations per meter square (1 m2) area were observed during field germination count. Based on the performance evaluation results, it is concluded that the developed seed drill can be effectively and economically used by most farmers.

Improved Cochlear Implant Performance Estimation Using Tonotopic-Based Electrocochleography

Cochlear implantation produces remarkable results in postlingual deafness, although auditory outcomes vary. Electrocochleography (ECochG) has emerged as a valuable tool for assessing the cochlear-neural substrate and evaluating patient prognosis. To assess whether ECochG-total response (ECochG-TR) recorded at the best-frequency electrode (BF-ECochG-TR) correlates more strongly with speech perception performance than ECochG-TR measured at the round window (RW-ECochG-TR). This single-center cross-sectional study recruited 142 patients from July 1, 2021, to April 30, 2022, with 1-year follow-up. Exclusions included perilymph suctioning, crimped sound delivery tubes, non-native English speakers, inner ear malformations, nonpatent external auditory canals, or cochlear implantation revision surgery. Cochlear implantation. Speech perception testing, including the consonant-nucleus-consonant (CNC) words test, AzBio sentences in quiet, and AzBio sentences in noise plus 10-dB signal to noise ratio (with low scores indicating poor performance and high scores indicating excellent performance on all tests), at 6 months postoperatively; and RW-ECochG-TR and BF-ECochG-TR (measured for 250, 500, 1000, and 2000 Hz). A total of 109 of the 142 eligible postlingual adults (mean [SD] age, 68.7 [15.8] years; 67 [61.5%] male) were included in the study. Both BF-ECochG-TR and RW-ECochG-TR were correlated with 6-month CNC scores (BF-ECochG-TR: r = 0.74; 95% CI, 0.62-0.82; RW-ECochG-TR: r = 0.67; 95% CI, 0.54-0.76). A multivariate model incorporating age, duration of hearing loss, and angular insertion depth did not outperform BF-ECochG-TR or RW-ECochG-TR alone. The BF-ECochG-TR correlation with CNC scores was significantly stronger than the RW-ECochG-TR correlation (r difference = -0.18; 95% CI, -0.31 to -0.01; z = -2.02). More moderate correlations existed between 6-month AzBio scores in noise, Montreal Cognitive Assessment (MoCA) scores (r = 0.46; 95% CI, 0.29-0.60), and BF-ECochG-TR (r = 0.42; 95% CI, 0.22-0.58). MoCA and the interaction between BF-ECochG-TR and MoCA accounted for a substantial proportion of variability in AzBio scores in noise at 6 months (R2 = 0.50; 95% CI, 0.36-0.61). In this case series, BF-ECochG-TR was identified as having a stronger correlation with cochlear implantation performance than RW-ECochG-TR, although both measures highlight the critical role of the cochlear-neural substrate on outcomes. Demographic, audiologic, and surgical factors demonstrated weak correlations with cochlear implantation performance, and performance in noise was found to require a robust cochlear-neural substrate (BF-ECochG-TR) as well as sufficient cognitive capacity (MoCA). Future cochlear implantation studies should consider these variables when assessing performance and related interventions.

Missing Part in Adjustable Pressure Limiting Valve in Bain’s Circuit: A Near Miss

Breathing circuits are the delivery systems which conduct anesthetic gases from an anesthetic machine to the patient. They are designed for either spontaneous respiration or intermittent positive pressure ventilation (IPPV). The Bain co-axial circuit, a modification of Mapleson D system is the most commonly used circuit outside operating room procedures. It has several advantages over the circle system in that it is light-weight, convenient with adjustable length. Although most problems with the circuit involve disconnections, obstruction problems related to kinks in the gas delivery tube or foreign body in the elbow have been reported. We would like to report an anesthetic incident involving desaturation of patient posted for electro convulsive therapy (ECT) due to missing part of the Adjustable Pressure Limiting (APL) valve.

An impact of the material and diameter of tubes in the flowing liquid cathode atmospheric pressure glow discharge system on its analytical performance – Preliminary study

Tubes of different diameters and materials were tested as solution (tungsten, molybdenum, titanium, corundum, quartz, and graphite) and gas (tungsten, molybdenum, and titanium) delivery tubes for the flowing liquid cathode atmospheric pressure glow discharge (FLC-APGD) microplasma system. For work purposes, FLC solutions both with and without the addition of formic acid were tested and the results were compared. Additionally, to elucidate the impact of various combinations of tubes on the excitation conditions in the discharge, the excitation (Texc(H)), rotational (Trot(OH)), and vibrational (Tvib(OH)) temperatures, as well as the electron number density were all determined. It was found that certain combinations of the tubes affected the discharge stability, therefore, either the precision was poor or the discharge could not be maintained at all. As a result, detection limits (DLs) of the studied elements were assessed for some combinations of tubes in order to establish the impact of the discharge stability on the background fluctuations. It was noticed that certain materials of the tubes, namely tungsten and corundum, were superior in terms of their resistance to the conditions under which the discharge was sustained. The analytes signals were found to be slightly affected by changing tubes, however, it was shown that the tungsten and corundum tubes provided better results in terms of signals intensity, than the other ones. Additionally, the commonly used combination of glass and graphite tubes turned out to give the lowest analytes signals and relatively high DLs.

Advancement of a high-dose infant air-jet dry powder inhaler (DPI) with passive cyclic loading: Performance tuning for different formulations

There is a current medical need for a dry powder aerosol delivery device that can be used to efficiently and consistently administer high dose therapeutics, such as inhaled antibiotics, surfactants and antivirals, to the lungs of infants. This study considered an infant air-jet dry powder inhaler (DPI) that could be actuated multiple times with minimal user interaction (i.e., a passive cyclic loading strategy) and focused on the development of a metering system that could be tuned for individual powder formulations to maintain high efficiency lung delivery. The metering system consisted of a powder delivery tube (PDT) connecting a powder reservoir with an aerosolization chamber and a powder supporting shelf that held a defined formulation volume. Results indicated that the metering system could administer a consistent dose per actuation after reaching a steady state condition. Modifications of the PDT diameter and shelf volume provided a controllable approach that could be tuned to maximize lung delivery efficiency for three different formulations. Using optimized metering system conditions for each formulation, the infant air-jet DPI was found to provide efficient and consistent lung delivery of aerosols (∼45% of loaded dose) based on in vitro testing with a preterm nose-throat model and limited dose/actuation to <5 mg.

Structure and assembly of type VI secretion system cargo delivery vehicle

Type VI secretion system is widely used in Gram-negative bacteria for injecting toxic effectors into neighboring prokaryotic or eukaryotic cells. Various effectors can be loaded onto the T6SS delivery tube via its core components: Hcp, VgrG, or PAAR. Here, we report 2.8-Å resolution cryo-EM structure of intact T6SS Hcp5-VgrG-PAAR cargo delivery system and crystal structure of unbound Hcp5 from B.fragilis NCTC 9343. Loading of Hcp5 hexameric ring onto VgrG causes expansion of its inner cavity and external surface, explaining how structural changes could be propagated to regulate co-polymerization and surrounding contractile sheath. High-affinity binding between Hcp and VgrG causes entropically unfavorable structuring of long loops. Furthermore, interactions between VgrG trimer and Hcp hexamer are asymmetric, with three of the six Hcp monomers exhibiting a major loop flip. Our study provides insights into the assembly, loading, and firing of T6SS nanomachine that contributes to bacterial inter-species competition and host interactions.

Engineered Bicomponent Adhesives with Instantaneous and Superior Adhesion Performance for Wound Sealing and Healing Applications

AbstractSurgical adhesives are playing an important role in wound repair and emergency hemostasis in clinical treatment. However, the development of strong bioglue with rapid in situ adhesion, durable adhesiveness, and flexibility in dynamic and moist physiological environments is still challenging. Herein, a new type of biosynthetic protein bioadhesives with superior adhesion performance is reported by developing a protein aldimine condensation strategy. Lysine‐rich recombinant proteins are designed and massively biosynthesized to instantaneously react with aldehyde cross‐linkers to realize in situ strong adhesion. The obtained bioadhesives show an ultra‐high adhesion strength of ≈101.6 kPa on porcine skin, outperforming extant clinical bioglues. In addition, they possess super biocompatibility, flexibility, biodegradability, and compliance with the tissues. Owing to the strong and instantaneous adhesion properties, the bioadhesives are qualified for dynamic wound closure, facilitating wound repair, and noncompressible hemorrhage. Importantly, they can be industrially encapsulated into custom‐made cartridge delivery tubes at low cost for clinical use. Therefore, biosynthetic bioadhesives have great potential for biological applications and are capable of scaling up to the industrial level for clinical transformation, which will be a successful paradigm for reforming existing clinical products.

Analysis and Experimental of Seeding Process of Pneumatic Split Seeder for Cotton

In order to study the working mechanism and sowing effect of seed delivery pipes and their associated cavity seeders, the factors affecting the sowing test were first derived through pressure loss theory and force analysis of cotton seed particles in the gas-solid coupling field. Secondly, Ansys fluent was used to simulate the flow field of seed delivery pipe joints to study the effect of seed delivery pipe joints on the overall pressure loss and uniformity of air pressure distribution and to determine the optimal structure of seed delivery pipe joints. Then, the EDEM was simulated for the overall seed delivery pipe and its associated cavity seeders in the absence of positive pressure to analyze the transport pattern of each cotton seed. Finally, CFD-DEM gas-solid coupling simulation experiments were conducted on the center of two rows of seed delivery pipes and their connected cavity seeders to analyze the trajectory of cotton seeds under different rotational speeds of cavity seeders and different positive seed delivery pressures and to deeply analyze the causes of Multiple seeding and Miss-seeding. At the same time, the seeding performance was evaluated by coupling simulation values with single seeding rate and multiple seeding rate as seeding performance evaluation indexes and compared with bench test. The results show that in the coupling simulation, when the speed of the cavity seeders is 20~40 rev/min and the seed delivery tube is passed into 50~150 Pa positive pressure airflow, the single seeding rate is not less than 83.06%, and the missed seeding rate is not more than 9.23%. In the bench test, the single seeding rate was not less than 80.64%, and the missed seeding rate was not more than 9.86% under the same cavity seeders speed and positive pressure, and the results of the bench test and the simulation test were close and consistent, which verified the feasibility of the simulation.

MODIFICATION AND PERFORMANCE EVALUATION OF AN IMPORTED THREE-ROW ANIMAL-DRAWN MAIZE PLANTER FOR PLANTING SOYBEANS

Increase in demand of functional and affordable planters and the inability of the peasant farmers in Nigeria to purchase imported planters stressed the need for development of a locally produced planters that could address the challenges encountered in grain planting. A three row imported animal-drawn maize planter was modified having identified its deficiencies. The modified planter consists of hopper, seed metering device, delivery tube, furrow opener, covering device, pressing wheel, frame, handle and traction wheel. It was evaluated in the laboratory and field using maize and Soybean as test crops. Parameters determined are planting speed, seedling emergence, plant to plant spacing, effective field capacity, germination count, planting efficiency, seed delivery rate, number of seeds per hole and percent seed damage. A combination of three planting speeds (2, 1.1 and 0.8m/s) and three seed weights (2.9, 2.2 and 1.1kg) were used for the performance evaluation. Results obtained were analyzed in a Completely Randomized Block Design. It showed that seed delivery rate was 24.8kg/ha and effective field capacity was 0.12ha/ha while the highest germination count of 83% was obtained at 0.8m/s planting speed and 2.9kg seed weight. The best of planting efficiency of 86.4% was obtained at 1.1m/s planting speed and 2.9kg seed weight. Plant to plant distance of 26.4cm was obtained at 2m/s planting speed and 2.2kg seed weight. One seed per hill was obtained at the all combinations. The modified planter has proved to be suitable for eliminating the limitations associated with the imported planter.

Nasal Cytology on 241 Children: From Birth to the First 3 Years of Life and Association with Common Airways Diseases.

Nasal cytology at birth and in the pediatric age is barely investigated regarding its association with the onset of common pediatric diseases. We enrolled 241 newborns within their first 24 h of life, studying their nasal cellular composition and repeating this at 1 and 3 years of life. We collected anamneses of perinatal factors and external factors (parental smoking, passive smoking, breastfeeding), and the prevalence of otitis, rhinosinusitis, bronchitis, asthma, and allergy at all timepoints. 204 children completed the study. At birth, there was a prevalence of ciliated cells and rare neutrophils. At 1 and 3 years, ciliated cells started reducing in favor of muciparous cells and neutrophils. We found that caesarian delivery and nasogastric tube usage for choanal patency are significantly related to a certain cellular nasal composition. Additionally, development of upper respiratory tract infections, AOM (acute otitis media) and allergy correlates with specific cytological compositions which may predict those pathologies. Our study is the first to show the normal nasal mucosa cellular composition and development in the first 3 years of life in a large cohort. Nasal cytology may be a tool for early risk assessment in the occurrence of upper airway disease.

Effect of gas Mach number on the flow field of close-coupled gas atomization, particle size and cooling rate of as-atomized powder: Simulation and experiment

Gas velocity is a key parameter regulating the particle size and the cooling rate of the gas atomized powder applied in additive manufacturing, metal injection molding, thermal spraying, and soft magnetic composites. In this paper, on basis of the well-designed close-coupled nozzles with different gas Mach numbers at the outlet, the gas field structure was simulated by Computational Fluid Dynamics (CFD) software, and the process of cooling and solidification of Fe-6.5 wt% Si metal droplets was calculated by finite difference method. The results show that with the increase of Mach number, both the gas velocity downstream and the pressure at the base of melt delivery tube tip rise, whereas the mass flow rate of the melt decreases. The nozzles with high Mach number can produce finer powder with higher cooling rate. The median diameter of the powder prepared by the nozzle with Mach numbers of 1.0, 1.5, 2.0, and 2.5 is 44.9, 39.0, 32.5, and 29.1 μm, respectively, and the corresponding cooling rate of the metal droplet with a diameter of 80 μm is 2.85 × 104, 2.98 × 104, 3.32 × 104, and 3.50 × 104 K/s, respectively. This work provides new ideas and suggestions for the preparation of metal powder with small particle size at high cooling rate.

Nozzle clogging in vacuum induction melting gas atomisation: influence of gas pressure and melt orifice diameter coupling

ABSTRACT The clogging problem of close-coupled nozzles in the vacuum induction melting gas atomisation (VIGA) process is studied by numerical simulation and industrial experiments. To understand the factors affecting lick back on the nozzle, volume of fluid (VOF) multiphase flow model simulation was adopted to visualise the motion of alloy melt around the outer wall of the delivery tube in the primary atomisation process. When the melt orifice diameter is 4 mm and the atomisation pressure is close to 3.5 MPa, the atomisation process is continuous, the powder particle size is fine, and the atomiser can be reused. When the orifice diameter is 5 mm, and the atomisation pressure is greater than 2.5 MPa, the risk of nozzle clogging is avoided, the powder size is relatively coarse. In the case of using the same atomiser structure, this study explains the mechanism of lick-back and the resulting nozzle damage in VIGA units.

Trends in emergency medicine resident procedural reporting over a 10-year period.

Procedural competency is expected of all emergency medicine (EM) residents upon graduation. The ACGME requires a minimum number of essential procedures to successfully complete training. However, data are limited on the actual number of procedures residents perform and prior studies are limited to single institutions over short time periods. This study sought to assess the number of Key Index Procedures completed during EM residency training and evaluate trends over time. We conducted a retrospective review of graduating EM resident procedure logs across eight ACGME accredited residency programs over the last 10 years (2013-2022). Sites were selected to ensure diversity of program length, program type, and geography. All data from EM residents graduating in 2013-2022 were eligible for inclusion. Data from residents from combined training programs, those who did not complete their full training at that institution (i.e., transferred in/out), or those who did not have data available were excluded. We determined the list of procedures based upon the ACGME Key Index Procedures list. Sites obtained totals for each of the identified procedures for each resident upon graduation. We calculated the mean and 95% CI for each procedure. We collected data from a total of 914 residents, with 881 (96.4%) meeting inclusion criteria. The most common procedures were point-of-care ultrasound, adult medical resuscitation, adult trauma resuscitation, and intubation. The least frequent procedures included pericardiocentesis, cricothyroidotomy, cardiac pacing, vaginal delivery, and chest tubes. Most procedures were stable over time with the exception of lumbar punctures (decreased) and point-of-care ultrasound (increased). In a national sample of EM programs, procedural numbers remained stable except for lumbar puncture and ultrasound. This information can inform residency training curricula and accreditation requirements.

Study on the Atomization Ability of the Annular Slit Nozzle Assembly with the Delivery Tube of Lower-limiting Flow

Study on the Atomization Ability of the Annular Slit Nozzle Assembly with the Delivery Tube of Lower-limiting Flow