Deposition Efficiency Research Articles

The effects of imposed swirling flow on the transport and deposition of particulate pollutants in the 90° industrial duct bends: An Eulerian-Lagrangian approach

Duct bend is one of the important parts of ventilation and dust removal systems, and particles deposited in curved ducts can reduce system efficiency or cause erosion on the bend wall. To investigate whether particle deposition is affected by imposed swirl on fluid flow, this article combines the RSM turbulence model and the Discrete Phase Model (DPM) to predict the deposition efficiency of particles in the bend under high Reynolds number conditions. The results show that the imposed swirl flow modifies the secondary flow initially dominated by the pressure gradient caused by the curvature effect. With the gradual increase of the swirl number ( S n), the deposition efficiency of the particles gradually decreased. However, when the swirl number is low ( S n ≤ 0.17), particles with smaller Stokes numbers are more susceptible to the intensity of turbulence. The higher the turbulence intensity near the wall, the easier it is for low inertia particles ( St ≤ 0.456) to deposit. The higher swirl intensity dominates the centrifugal force, reduces the turbulent intensity in the central region of the duct, improves the stability of the airflow and makes it easier for particles with larger inertia ( St ≥ 0.811) to pass through the bend.

Size-segregated characteristics of water-soluble oxidative potential in urban Xiamen: Potential driving factors and implications for human health

Oxidative potential (OP), defined as the ability of particulate matter (PM) to generate reactive oxygen species (ROS), has been considered as a potential health-related metric for PM. Particles with different sizes have different OP and deposition efficiencies in the respiratory tract and pose different health risks. In this study, size-segregated PM samples were collected at a coastal urban site in Xiamen, a port city in southeastern China, between August 2020 and September 2021. The water-soluble constituents, including inorganic ions, elements and organic carbon, were determined. Total volume-normalized OP based on the dithiothreitol assay was highest in spring (0.241 ± 0.033 nmol min−1 m−3) and lowest in summer (0.073 ± 0.006 nmol min−1 m−3). OP had a biomodal distribution with peaks at 0.25–0.44 μm and 1.0–1.4 μm in spring, summer, and winter and a unimodal pattern with peak at 0.25–0.44 μm in fall, which were different from the patterns of redox-active species. Variations in the seasonality of fine and coarse mode OP and their correlations with water-soluble constituents showed that the size distribution patterns of OP could be attributed to the combined effects of the size distributions of transition metals and redox-active organics and the interactions between them which varied with emissions, meteorological conditions and atmospheric processes. Respiratory tract deposition model indicated that the deposited OP and the toxic elements accounted for 47.9 % and 36.8 % of their measured concentrations, respectively. The highest OP doses and the excess lifetime carcinogenic risk (ELCR) were found in the head airway (>70 %). However, the size distributions of OP deposition and ELCR in the respiratory tract were different, with 63.9 % and 49.4 % of deposited ELCR and OP, respectively, coming from PM2.5. Therefore, attention must be paid to coarse particles from non-exhaust emissions and road dust resuspension.

Intrauterine growth restriction defined by increased brain-to-liver weight ratio affects postnatal growth and protein efficiency in pigs

Intrauterine growth restriction (IUGR) refers to impaired foetal growth during gestation, resulting in permanent stunting effects on the offspring. This study aimed to investigate the effects of IUGR on growth performance, body composition, blood metabolites, and meat quality of pigs from birth (n = 268) to slaughter (n = 93). IUGR piglets have prioritised brain development as a foetal adaptive reaction to placental insufficiency. This survival mechanism results in a higher brain-to-liver weight ratio (BrW/LW). One day (±1) after birth, computed tomography (CT) was performed on each piglet to assess their brain and liver weights. A threshold value of 0.78 (mean + SD) was chosen to divide the piglets into two categories – NORM (BrW/LW < 0.78) and IUGR (BrW/LW > 0.78). Moreover, each piglet was classified as either normal (score 1), mild IUGR (score 2), or severe IUGR (score 3) based on the head morphology. BW was recorded weekly, and average daily gain (ADG) was calculated for lactation, starter, grower, and finisher periods. Body composition was assessed after weaning (29.6 ± 0.7 d), at 20 kg (64 ± 7.2 d), 100 kg (165 ± 12.3 d), and on the carcasses using Dual-energy X-ray absorptiometry (DXA). Content and deposition rates of single nutrients, as well as energy and CP efficiency, were measured at 20 and 100 kg. Feed intake was recorded from 20 kg to slaughter. Meat quality was assessed on the carcasses. A total of 70% of the piglets assigned a score of 3 were NORM according to their BrW/LW. The IUGR category showed a lower ADG in the lactation (P < 0.01), starter (P = 0.07), and grower phases (P < 0.05) and a reduced CP efficiency in the grower–finisher period (P < 0.01) compared to the NORM group. IUGR pigs had a lower gain-to-feed ratio in the finisher period (P = 0.01) despite similar average daily feed intake, and they required more days (P < 0.01) to reach the slaughter weight. Additionally, their meat was darker (P = 0.01) than that of NORM pigs. The BrW/LW was inversely proportional to the ADG from birth to slaughter and negatively correlated with the CP deposition rate and efficiency in the grower–finisher period (P < 0.01). Furthermore, the higher the BrW/LW, the longer it took the pigs to reach the slaughter weight (P < 0.01). In conclusion, the identification of IUGR piglets based on the head morphology does not always agree with an increased BrW/LW. IUGR affects growth performance from birth to slaughter, CP efficiency in the grower–finisher period and meat quality.

Effects of the burner on SiO2 formation and deposition in the OVD process

The burner of outside vapor deposition (OVD) is of great significance for enhancing the yields and quality of the optical fiber preform. This study aims to numerically investigate the effects of the burner on silica particles formation and its corresponding deposition performance in the OVD process. This work is based on our recently developed integrated Eulerian-Eulerian multiphase OVD process model combined with a particle nucleation model. The effects of the distance between the burner and target, the horizontal offset of the target to the burner, the shape of burners, swirl burners as well as double burners are investigated. The results demonstrate that there exists an optimal value for the distance between the burner and target to yield the largest deposition efficiency. However, the deposition efficiency monotonically declines as the horizontal offset of the target to the burner increases. The elliptic burner potentially provides a better match with the target surface for particle deposition. An optimal number of helical vanes installed inside the O2–1 inlet is observed in the counter-swirling burner of O2–1 and H2 inlets, which yields the largest deposition efficiency of 33.4%. Double burners could promote the deposition rate, but could not enhance the particle deposition efficiency. The results provide a deeper understanding of the burner design and OVD process optimization.

What Are the Key Anatomical Features for the Success of Nose-to-Brain Delivery? A Study of Powder Deposition in 3D-Printed Nasal Casts.

Nose-to-brain delivery is a promising way to improve the treatment of central nervous system disorders, as it allows the bypassing of the blood-brain barrier. However, it is still largely unknown how the anatomy of the nose can influence the treatment outcome. In this work, we used 3D printing to produce nasal replicas based on 11 different CT scans presenting various anatomical features. Then, for each anatomy and using the Design of Experiments methodology, we characterised the amount of a powder deposited in the olfactory region of the replica as a function of multiple parameters (choice of the nostril, device, orientation angle, and the presence or not of a concomitant inspiration flow). We found that, for each anatomy, the maximum amount of powder that can be deposited in the olfactory region is directly proportional to the total area of this region. More precisely, the results show that, whatever the instillation strategy, if the total area of the olfactory region is below 1500 mm2, no more than 25% of an instilled powder can reach this region. On the other hand, if the total area of the olfactory region is above 3000 mm2, the deposition efficiency reaches 50% with the optimal choice of parameters, whatever the other anatomical characteristics of the nasal cavity. Finally, if the relative difference between the areas of the two sides of the internal nasal valve is larger than 20%, it becomes important to carefully choose the side of instillation. This work, by predicting the amount of powder reaching the olfactory region, provides a tool to evaluate the adequacy of nose-to-brain treatment for a given patient. While the conclusions should be confirmed via in vivo studies, it is a first step towards personalised treatment of neurological pathologies.

Ternary Dry Powder Agglomerate Inhalation Formulation of Melatonin With Air Jet Mixing to Improve In Vitro And In Vivo Performance

An improved agglomerate formulation with melatonin and fine lactose for dry powder inhalation using Turbuhaler® was developed. Co-grinding lactose with 1 % magnesium stearate prior to air jet mixing served as a key factor to improve the in vitro aerosolization and in vivo efficacy. Elevated mixing pressure facilitated the dispersion and homogenization of the cohesive mixture for even distribution of agglomerate size after spheroidization and subsequent higher emitted dose with lower variation. Magnesium stearate was employed as a tertiary component to adjust the interparticle force for better aerosolization. At optimized mixing pressure, co-grinding lactose with magnesium stearate before jet mixing displayed further improvement of fine particle fraction to 71.6 ± 3.1 %. The superior fine particle deposition efficiency contributed to rapid onset of action and a high bioavailability of 67.0 % after intratracheal administration to rats. Overall, an inhalable melatonin dry powder formulation exhibiting good aerosol property and lung deposition with clinical translation potential was developed.

Monte Carlo simulation of deposition uniformity in the triple-target magnetron co-sputtering system

Magnetron sputtering is an important technology for the preparation of optical, electronic, and mechanical coatings. In these applications, deposition uniformity has a significant impact on the film properties and performance of the devices fabricated by the film. Due to the ion bombardment, the target atoms, namely, the sputtered particles, are emitted to the background gas and finally deposited on the substrate. The film deposition uniformity, therefore, is significantly influenced by the particle transportation process. In this study, a particle transport model was proposed based on MC simulation in COMSOL to analyze the effects of working conditions and geometry parameters on deposition uniformity. It is concluded that the increase in pressure and the decrease in temperature can improve deposition uniformity. Then, the influence of geometry parameters of the triple-target magnetron co-sputtering system is further investigated on the deposition efficiency and deposition uniformity. It is found that the geometry parameters determine the zone with high particle deposition. The closer the zone is to the substrate center, the higher the deposition efficiency. The greater the particle concentration difference on the substrate, the lower the deposition uniformity. Moreover, the optimized parameters were obtained to maximize both the deposition efficiency and deposition uniformity.

Numerical study on the effect of the realistic mouth-inhaler positions on orally inhaled drug delivery in pediatric intersubject upper airways

The relative position between the pediatric upper airway and the inhalation device during real inhalation administration has significant effects on the delivery efficiency of orally inhaled drugs. Morphological variability plays an important role in this process. However, the mouth-throat differences between adults and children were usually neglected because most of the commercial inhalation devices currently are designed for adults or older adolescents. The main objective of this study is to investigate these effects by four realistic pediatric mouth-throat (RMT) geometries. In addition, an idealized mouth-throat (IMT) model was developed to validate the numerical model and to compare with the RMT models. Computational fluid dynamics (CFD) simulations were performed to investigate the flow pattern and deposition pattern in these models and the results were compared with the cascade impactor experiments, replica experiments and in vivo results. No significant correlation (p > 0.1) between the relative position parameters and inhaler insertion depth can be noticed among the RMT models. Notably, significant variability in the inhaler posture was observed in RMT models, especially for the S4 model. Airflow structure shows that the RMT model has a complex onset of turbulence, reverse flow and subsequently vortex formation when compared with the IMT model. The oral cavity is the region with the largest deposition fraction (DF) and deposition efficiency (DE). The DF and DE of the oral cavity are negatively correlated to the position parameter (Lm) when mass median aerodynamic diameter (MMAD) of indacaterol 150 μg was utilized as the input particle parameter. The relative position between the inhaler and oral cavity has significant effects on the particle transport and deposition. Furthermore, in silico results overestimated the lung deposition in comparison to the in vivo and experimental results when MMAD was used as input. To resolve the disparity between the in silico and in vivo results, a modified prediction method based on the cascade impactor and original in silico results was proposed and a good correlation of the relative contribution of pulmonary absorption to total systemic exposure (flung) was found between the predicted and observed results. The findings of present work will provide useful information in understanding the particle transport and deposition in the pediatric airways for the design of inhaler.

Combing of picogram level DNA equivalent to genomic DNA present in single human cell by self propelled droplet motion over a stable gradient surface

DNA combing is a powerful technique for studying replication profile, fork-directionality and fork velocity. At present, there is requirement of a methodology to comb DNA present in a single human cell for studying replication dynamics at early embryonic stage. In our study, a surface having dual characteristics i.e., affinity towards negatively charged single DNA molecules and a hydrophobic gradient for self propelled droplet motion of combing solution was developed. The surface was made by coating of TCOS (trichloro-octylsilane) by vapor diffusion on APTES (Aminopropyl-triethoxysilane) coated glass slides. A gradient surface having high deposition efficiency (DE) was developed on which 5 picogram DNA equivalent to genomic DNA present in one single human cell can be combed. The gradient surface was thermostable in nature having the ability to sustain boiling temperature for two hours and sustain anisotropy in 70 % ethanol for 80 h. Applicability for multiple runs was enhanced such that the surface can be used for 13–14 times. Factors associated with gradient surface are unidirectional movement of combing solution droplet over the gradient surface for combing straight DNA molecules and a longer gradient surface of more than 1 cm such that long size DNA molecules can be combed. Ellipsometry and contact angle hysteresis confirmed the presence of hydrophobic gradient. XPS (X-ray photoelectron spectroscopy) and FTIR (Fourier Transform Infrared Spectroscopy) confirmed the presence of characteristic affinity towards negatively charged DNA molecules on the gradient surface. Combing solution was optimized for increasing deposition efficiency and for increasing the applicability of gradient surface for multiple runs. High temperature of combing solution was found to increase Deposition Efficiency. Combing solution was also optimized for combing single DNA molecules over the gradient surface. Single DNA molecules were combed by reducing pH and lowering concentration of triton-X in the combing solution. Dye: bp ratio was optimized for high fluorescent intensity and low surface background.

The effects of aerosol concentration on the evolution, transport, and deposition of hygroscopic droplets in the highly idealized MT model: A numerical study

Inhalation therapy is widely used to treat various respiratory diseases. Nebulizers have been widely adopted due to their ease of operation, high drug delivery efficiency, and low residual volume. Traditional studies on drug delivery in the respiratory tract typically use a one-way coupled method to track drug transport and deposition for non-hygroscopic drug particles. However, neglecting the concentration of nebulized hygroscopic droplet aerosols can lead to significant discrepancies in the deposition efficiency (DE) of nebulized drugs in the airways. To investigate the effect of different nebulization rates on the evolution, transport, and deposition of droplets, a highly idealized mouth-throat (MT) model was selected as a testbed for the in silico trials of drug delivery to the respiratory tract. The interaction between continuous and discrete phases was modeled using a two-way coupled model of highly concentrated droplet aerosol-water vapor interaction, innovated by the particle parcel method. The effects of different coupling methods and boundary conditions on the average droplet diameter and droplet deposition distribution pattern at the outlet of the MT model were compared using a computational fluid dynamics (CFD) method. Simulation results indicate that neglecting the effect of water vapor evaporated from the droplets on the relative humidity (RH) in the oral cavity could lead to a 2.2-fold prediction error of the average droplet diameter at the outlet of the MT model for a conventional nebulization rate of 0.386 g/min. As the nebulization rate increases, the difference in the predicted average droplet diameter at the outlet of the MT model between the one-way coupled method and the two-way coupled method also increases. Increasing the nebulization rate during inhalation therapy could lead to incomplete evaporation of drug droplets, resulting in deposition of larger diameter drug droplets in the oral cavity. In contrast, a lower nebulization rate can reduce the droplet diameter at the outlet of the MT model, allowing it to enter deeper airways.

Femtosecond Laser Preparation and Biomineralizability of ZrO2 Ceramic Woven Surfaces

Improving the biomineralization of the ZrO2 ceramics surface is of great significance for field of dentistry. A femtosecond laser is used to prepare micro–nano structures on the surface of the ZrO2 ceramics. The contact angle, micromorphology, and chemical composition of the material surface are characterized using a contact angle measurement instrument, scanning electron microscope, and energy‐dispersive spectroscopy. The changes of surface wettability of different samples areanalyzed, and the biomineralization of different micropit surfaces is evaluated through hydroxyapatite (HA) deposition experiments. The results show that the deposition effect of the femtosecond laser‐textured surface is better than that of the original surface. Femtosecond laser processing improves the surface of the material, providing additional nucleation sites for HA, which is conducive to its growth and improvement of deposition efficiency. HA deposited on hydrophobic surfaces consists of a small amount of rod‐shaped and spherical particles. While the deposition effect on hydrophilic surfaces is significantly improved, the deposited particles on hydrophilic surfaces are rod‐shaped and stacked into spherical shapes, growing into pieces after combining, and the particle number increases, the density increases, and they completely cover the textured surface. This study provides a theoretical reference and experimental basis for improving its biomineralization.

Titanium–Platinum Thin Films as a Tool for the Electrooxidation of Cyanide

This paper presents a detailed study of a titanium–platinum thin film-based electrode preparation and its practical application in the electrooxidation of cyanides to help protect our environment. The novel electrochemical deposition process of Pt on nearly atomically smooth magnetron-sputtered Ti film has been used to prepare a highly effective glass|Ti|Pt composite electrode with high catalytic activity for the electrooxidation of cyanide ions. The composite electrode exhibits over a 90% electrical current efficiency in the cyanide electrooxidation process and can be used for the decontamination of highly concentrated KCN solutions (up to 0.1 M) without any chemical additives. A high current efficiency (70%) of Pt thin film deposition on a glass|Ti electrode was achieved using a potentiostatic double-pulse method. Fast Fourier transform electrochemical impedance spectroscopy revealed the oxidation kinetics for cyanide ions at the electrode. The glass|Ti electrode was prepared using the magnetron sputtering technique, which allows us to fabricate electrodes of any shape suitable for any electrochemical cell or electroplating bath. Meanwhile, electrochemical deposition of Pt on the glass|Ti electrode is an efficient and environmentally friendly method, since various salts of Pt and/or Pt-containing wastes can be used for electrodeposition instead of pure Pt, which is more expensive.

Numerical investigation of nanoparticle deposition in the olfactory region among pediatric nasal airways with adenoid hypertrophy

To understand inhaled nanoparticle transport and deposition characteristics in pediatric nasal airways with adenoid hypertrophy (AH), with a specific emphasis on the olfactory region, virtual nanoparticle inhalation studies were conducted on anatomically accurate child nasal airway models. The computational fluid-particle dynamics (CFPD) method was employed, and numerical simulations were performed to compare the airflow and nanoparticle deposition patterns between nasal airways with nasopharyngeal obstruction before adenoidectomy and healthy nasal airways after virtual adenoidectomy. The influence of different inhalation rates and exhalation phase on olfactory regional nanoparticle deposition features was systematically analyzed. We found that nasopharyngeal obstruction resulted in significant uneven airflow distribution in the nasal cavity. The deposited nanoparticles were concentrated in the middle meatus, septum, inferior meatus and nasal vestibule. The deposition efficiency (DE) in the olfactory region decreases with increasing nanoparticle size (1–10 nm) during inhalation. After adenoidectomy, the pediatric olfactory region DE increased significantly while nasopharynx DE dramatically decreased. When the inhalation rate decreased, the deposition pattern in the olfactory region significantly altered, exhibiting an initial rise followed by a subsequent decline, reaching peak deposition at 2 nm. During exhalation, the pediatric olfactory region DE was substantially lower than during inhalation, and the olfactory region DE in the pre-operative models were found to be significantly higher than that of the post-operative models. In conclusions, ventilation and particle deposition in the olfactory region were significantly improved in post-operative models. Inhalation rate and exhalation process can significantly affect nanoparticle deposition in the olfactory region.

Latest developments in coaxial multiwire high-power laser cladding

Laser cladding is widely used in the industry to precisely apply tailored surface coatings, as well as three-dimensional deposits for repair and additive manufacturing of metallic parts. However, the processing of larger components is economically challenging mainly because of low deposition rates. At Fraunhofer IWS, a Laserline fiber-coupled diode laser with 20 kW power has been employed for over a decade to develop competitive coating solutions with powder-based laser cladding. The deposition rates achieved with this technology is comparable to common PTA technique at the same time bringing significant advantages in terms of reduced heat affected zone, distortion, and savings in material resources. While high-power powder-based laser cladding is an industrially established coating technology, for example, to coat hydraulic cylinders or most recently brake discs, a high-productivity solution for wire-based processes is still challenging. Fraunhofer IWS has developed a new nozzle for high-power high-productivity laser wire cladding for coating and additive manufacturing, the so-called COAXquattro. This system enables to feed at the same time four wires into the melt pool, reaching deposition efficiencies in the same range as a powder-based laser process. For selected materials, the improvement in coating quality compared to powder laser cladding is achieved. Furthermore, with COAXquattro system simultaneous feeding of powder particles to wire cladding presents a great potential for in situ alloying and cost-effective production of new compositions on material alloying or hardmetal-reinforced composites for coating application and 3D additive manufacturing.

Effect of process modes on microstructure and mechanical properties of CMT wire arc additive manufactured WE43 magnesium alloy

The traditional WE43 magnesium alloy (WE43-Mg) manufacturing process faces challenges in producing large and complex structures. The cold metal transfer wire arc additive manufacturing (CMT-WAAM) offers a promising solution due to its flexibility, high deposition efficiency and low heat put. However, energy transfer and mass transfer are highly coupled in the CMT additive manufacturing process. Under different working modes, the local thermal processes are quite different for the same transition metals, which can produce different microstructures and mechanical properties. Therefore, it is necessary to study the effect of working modes on microstructure and mechanical properties. This study successfully deposited single-pass multi-layer WE43-Mg components using four CMT processes: CMT, CMT-Pulse, CMT-Advance, and CMT-Pulse + Advance. The microstructure and mechanical properties of these deposited samples were compared. Results revealed equiaxed grains with uniform sizes in the top and middle regions, with fine-grain regions between layers in the four CMT modes. Compare the microstructure characterization results, the higher the line energy, the narrower the width of the remelted fine grain zone. Four CMT modes deposited components exhibited superior mechanical properties compared to as-cast WE43-Mg. The CMT pulse mode shows the best results due to its low porosity. The average yield strength is 149.0 MPa, tensile strength is 222.9 MPa, and elongation is 6.4 %.

Influence of mesh nebulizer characteristics on aerosol delivery in non-human primates

Non-Human Primates (NHPs) are particularly relevant for preclinical studies during the development of inhaled biologics. However, aerosol inhalation in NHPs is difficult to evaluate due to a low lung deposition fraction and high variability. The objective of this study was to evaluate the influence of mesh nebulizer parameters to improve lung deposition in macaques. We developed a humidified heated and ventilated anatomical 3D printed macaque model of the upper respiratory tract to reduce experiments with animals. The model was compared to in vivo deposition using 2D planar scintigraphy imaging in NHPs and demonstrated good predictivity. Next, the anatomical model was used to evaluate the position of the nebulizer on the mask, the aerosol particle size and the aerosol flow rate on the lung deposition. We showed that placing the mesh-nebulizer in the upper part of the mask and in proximal position to the NHP improved lung delivery prediction. The lower the aerosol size and the lower the aerosol flow rate, the better the predicted aerosol deposition. In particular, for 4.3 ± 0.1 µm in terms of volume mean diameter, we obtained 5.6 % ± 0.2 % % vs 19.2 % ± 2.5 % deposition in the lung model for an aerosol flow rate of 0.4 mL/min vs 0.03 mL/min and achieved 16 % of the nebulizer charge deposited in the lungs of macaques. Despite the improvement of lung deposition efficiency in macaques, its variability remained high (6–21 %).

Fe doped γ-MnO2 of anode for lead release inhibition in zinc electrowinning

Lead (Pb) anode has caused serious environmental pollution and resource waste problems in zinc (Zn) electrowinning. A novel functional Pb-based (Pb/MnO2) anode had been prepared successfully to reduce hazardous wastes of Pb-containing anode slime in our earlier published research. However, the impurity Fe2+ detected in the industrial preparation of this Pb/MnO2 anode was a tricky problem that cannot be ignored. Here, a Fe2+ doped MnO2 (Pb/Fe-MnO2) anode with its controllable preparation was studied. The results showed that Fe2+ participated in the transformation equilibrium reaction between Mn2+ and γ-MnO2, which reduced the deposition efficiency and crystal size of γ-MnO2. The internal structure of γ-MnO2 film had been reconstructed by Fe2+, which increased the concentration of oxygen vacancy (1.6 times) and Mn3+ (5.5 times) on the surface of the composite anode. During 20 d of continuous Zn electrowinning, the anode slime accumulation of the Pb/Fe-MnO2 anode was reduced by 90 % and 40 %, respectively, compared with the traditional Pb anode and Pb/MnO2 anode. The impurity Fe2+ is generally thought to be harmful, but studies have shown that it can promote the OER of the anode surface and improve the reduction of Pb-containing anode slime. The mechanism of reconstruction engineering has revealed that two pathways of Fe2+ may affect the deposition efficiency of MnO2: electrochemical and chemical, while Fe could be involved in the film structure along with γ-MnO2 co-deposition. The controlled impurity Fe2+ effect of MnO2 film anode will have a future application prospect for Pb release inhibition in industrial Zn electrowinning and related hydrometallurgy industries.

Improving the deposition efficiency and mechanical properties of additive manufactured Inconel 625 through hot wire laser metal deposition

This study focuses on the advantages of hot wire laser metal deposition (HW-LMD) compared to cold wire deposition technology (CW-LMD) for fabricating Inconel 625 alloy. Initially, a comparative study was conducted through single-pass deposition experiments to evaluate the process characteristics of HW-LMD and CW-LMD. The results showed that by increasing the additional resistance heat by 20% during HW-LMD, a significant 92.5% increase in wire deposition rate and a 60.3% increase in energy efficiency were achieved. Additionally, the wire deposition rate of HW-LMD was 1.5 times as high as that of CW-LMD with the identical total energy input. Subsequently, well-formed Inconel 625 bulks were fabricated using both CW-LMD and HW-LMD techniques. The microstructures and mechanical properties of the as-deposited samples manufactured by the two different processes were comparatively studied. Due to the accelerated solidification rate of the molten pool, the columnar dendrites in Inconel 625 samples prepared by HW-LMD were refined, resulting in an average grain size of 12 µm. Furthermore, the precipitation of the Laves phase at the inter-dendrite regions was suppressed. Consequently, an increased microhardness of 258 HV1.0 for HW-LMD samples was obtained. In addition, the HW-LMD samples also exhibited superior tensile strength and elongation, measuring at 837.4 MPa and 55.2% respectively. Based on the aforementioned findings, HW-LMD has demonstrated outstanding capability in improving productivity and mechanical properties, indicating a promising option for efficient additive repair and manufacturing.

Effect of Nanoparticles Deposition on Cooling Performance of Photovoltaic Panels

Abstract The current research aims to investigate the deposition and dispersion of nanoparticles for thermally developing laminar flow inside a cooling channel of a photovoltaic (PV) panel. The particle transport is modeled in an Eulerian-Lagrangian framework using a two-way coupling approach to perform the particle trajectories. In the absence of turbulent fluctuations, Brownian diffusion is the main force that contributes to particles deposition due to the small size of the particles used in the current study (below 100 nm). Several parameters were investigated such as inlet temperature, Reynolds number, nanoparticle size, and concentration in order to record the subsequent effects on the deposition efficiency, heat transfer coefficient, and pressure drop. There is no direct particle deposition model available in commercial computational packages such as Fluent, so a deposition model was developed and programmed in C-language using the User-Defined Functions (UDF) capabilities available in the Fluent solver to model how the particles are affected by wall impacts. Model validation was performed against the experimental studies found in the literature and showed good agreement. The efficiency of particle deposition on the channel wall was found to increase with decreasing nanoparticle size and/or Reynolds number. Furthermore, the deposition efficiency increased with the increase in fluid inlet temperature and nanofluid concentration. Moreover, the heat transfer rate was decreased as a result of decreasing nanofluid concentration caused by nanoparticle deposition on the channel walls, while the pumping power was also decreased due to concentration loss.

Application of heliox for optimized drug delivery through respiratory tract

Understanding the transportation and deposition (TD) of inhaled particles in the upper respiratory tract is crucial for predicting health risks and treating pulmonary diseases. The available literature reports highly turbulent flow in the extrathoracic (ET) region during normal breathing, which leads to higher deposition of the drug aerosol in this region. To improve the targeted deposition of inhaled drugs, in the tracheobronchial airways, it is essential to understand the flow and particle transport dynamics and reduce the turbulence behavior at the ET region. The less-dense heliox gas could reduce the turbulence behavior at the ET; however, the knowledge of heliox inhalation therapies in drug aerosol TD remains underachieved to realize the full potential for assisted breathing and drug delivery. Additionally, the impact of the inhalation of heliox mixed with other gases on particle deposition is missing in the literature. Therefore, this study aims to develop a mixture model to advance the knowledge of inhalation therapy. A heliox (78% helium and 22% oxygen) and a mixture of heliox and air are used to understand the flow behavior and particle TD in airways. The impact of different inhalation and Stokes numbers on the deposition efficiencies in the ideal and age-specific upper airways is studied. The study reports that less-dense heliox gas has lower turbulence intensity and results in lower deposition efficiency in the G3–G5 lung airways compared to air and mixture inhalations. Moreover, slightly higher deposition efficiencies during mixture inhalation as compared to air inhalation are found in the upper airways. The deposition patterns of different inhalations obtained in this study could help improve targeted drug delivery into the upper and deeper lung airways.