HVOF-sprayed HAp/S53P4 BG composite coatings on an AZ31 alloy for potential applications in temporary implants

Bioactive thermal spray coatings produced via high-velocity oxygen fuel spray(HVOF)from hydroxyapatite(HAp)and bioactive glasses(BG)have the potential to be employed on temporary implants due to the ability of both HAp and BG to dissolve and promote osseointegration,considering that both phases have different reaction and dissolution rates under in-vitro conditions.In the present work,75%wt.HAp-25%wt.S53P4 bioactive glass powders were HVOF-sprayed to obtain HAp/S53P4 BG composite coatings on a bioresorbable AZ31 alloy.The study is focused on exploring the effect of the stand-off distance and fuel/oxygen ratio variation as HVOF parameters to obtain stable structural coatings and to establish their effect on the phases and microstructure produced in those coatings.Different characterization techniques,such as scanning electron microscopy,X-ray diffraction,and Fourier transform infrared spectroscopy,were employed to characterize relevant structural and microstructural properties of the composite coatings.The results showed that thermal gradients during coating deposition must be managed to avoid delamination due to the high temperature achieved(max 550℃)and the differences in coefficients of thermal expansion.It was also found that both spraying distance and oxygen/fuel ratio allowed to keep the hydroxyapatite as the main phase in the coatings.In addition,in-vitro electrochemical studies were performed on the obtained HAp/S53P4 BG composite coatings and compared against the uncoated AZ31 alloy.The results showed a significant decrease in hydrogen evolution(at least 98%)when the bioactive coating was applied on the Mg alloy during evaluation in simulated body fluid(SBF).

Preparation and Properties of Spray Polyurea Elastomer for Aquaculture Foam Floating Balls

[Objectives] This study was conducted to develop a polyurea elastomer which can be sprayed on the surface of expanded polystyrene (EPS) floating balls, so as to improve the surface strength and service life of the floating balls. [Methods] The effects of the types and amounts of isocyanate, chain extenders and polyether polyols on the gelation rate, adhesion and wear resistance of polyurea elastomer were investigated, and it was finally determined the preparation process of polyurea elastomer using liquid isophorone diisocyanate (IPDI) and amino-terminated polyether (D2000) as the main raw materials, dimethylthiotoluene diamine (E300) as the chain extender and silica as the wear resistance modifier through two-step solution polymerization of prepolymerization and chain extension. [Results] The physical properties and chemical resistance tests of spray polyurea elastomer showed that it had good physical properties and acid and alkali resistance, and could meet the requirements of spraying and protection of EPS floating ball surface in marine environment. [Conclusions] Polyurea elastomer coating can improve the aging resistance, wear resistance and acid and alkali resistance of EPS floating balls, and prevent them from being fragile and floating randomly to form marine floating garbage which results in "white pollution".

Effect of Spray Rails on Takeoff Performance of Amphibian Aircraft

Amphibian aircraft have seen a rise in popularity in the recreational and utility sectors due to their ability to take off and land on both land and water, thus serving a myriad of purposes, such as aerobatics, surveillance, and firefighting. Such seaplanes must be aerodynamically and hydrodynamically efficient, particularly during the takeoff phase. Naval architects have long employed innovative techniques to optimize the performance of marine vessels, including incorporating spray rails on hulls. This research paper is dedicated to a comprehensive investigation into the potential utilization of spray rails to enhance the takeoff performance of amphibian aircraft. Several spray rail configurations obtained from naval research were simulated on a bare Seamax M22 amphibian hull to observe an approximate 10% - 25% decrease in water resistance at high speeds alongside a 3% reduction in the takeoff time. This study serves as a motivation to improve the design of the reference airplane hull and a platform for detailed investigations in the future to improve modern amphibian design.

Designing an Experimental Device for Swinging Excitation Spray Cooling

In this paper,we introduce the design principle of the oscillating excited spray cooling experimental device.We then designed an oscillating excited spray cooling experimental device.By using the device,the swaying motion can be realized through the control system,and the motion of the droplet under different vibration frequencies can be observed.By measuring the liquid flow rate and pressure,the changes in liquid flow rate,pressure,and temperature with time under different vibration frequencies were studied.The trajectory of the droplet and the temperature distribution of the droplet under different vibration frequencies could be observed.The device has a simple structure,is easy to control,and can achieve continuous observation of the spray cooling process.

Influence of Spray Gun Position and Orientation on Liquid Film Development along a Cylindrical Surface

A method combining computationalfluid dynamics(CFD)and an analytical approach is proposed to develop a prediction model for the variable thickness of the spray-induced liquidfilm along the surface of a cylindrical workpiece.The numerical method relies on an Eulerian-Eulerian technique.Different cylinder diameters and positions and inclinations of the spray gun are considered and useful correlations for the thickness of the liquidfilm and its distribution are determined using various datafitting algorithms.Finally,the reliability of the pro-posed method is verified by means of experimental tests where the robot posture is changed.The provided cor-relation are intended to support the optimization of spray-based coating applications.

Sea spray induced air-sea heat and salt fluxes based on the wavesteepnessdependent sea spray model

Sea spray,which comprises amounts of small ocean droplets,plays a significant role in the air-sea coupling,atmospheric and oceanic dynamics,and climate.However,it remains arduous to arrive at estimates for the efficiency and accuracy of the sea spray induced air-sea heat and salt fluxes.This is because the microphysical process of sea spray evolution in the air is of extreme complexity.In this study,we iteratively calculated the sea spray induced air-sea heat and salt fluxes at various weather condition.To do so,we implemented one novel wave-steepness-dependent sea spray model into a bulk air-sea fluxes algorithm and utilized other sea spray models as comparisons.Based on the improved wave-dependent bulk turbulent algorithm,we observed that despite the negative contribution of sea spray to the sensible heat fluxes,the sea spray positively contributes to the air-sea latent heat fluxes,leading to an overall increase in the total air-sea heat fluxes.The additional heat fluxes caused by sea spray may be the missing critical process that can clarify the discrepancies observed between measured and modelled Tropical Cyclone’s development and intensification.In addition to heat fluxes,we observed that sea spray has significant impacts on the air-sea salt fluxes.As the sea salt particles are one of the main sources of the atmosphere aerosol,our results imply that sea spray could impact global and regional climate.Thus,given the significance of sea spray on the air-sea boundary layer,sea spray effects need to be considered in studies of air-sea interaction,dynamics of atmosphere and ocean.

Experimental study on the improvement of spray characteristics of aero-engines using gliding arc plasma

A gliding arc plasma fuel atomization actuator suitable for aeroengines was designed,and a gliding arc plasma fuel spray experimental platform was built to address the fuel atomization problem in aeroengine combustion chambers.The spray characteristics for different airflows,fuel flows,and discharge voltages were analyzed using laser particle size analysis.The research shows that the fuel atomization effect is improved from the increased airflow.The decreased fuel flow not only reduces the injection pressure of the fuel but also changes the discharge mode of the gliding arc,which affects reductions in the discharge power and inhibits fuel atomization.Gliding arc discharges accelerate the breaking,atomization,and evaporation of fuel droplets while reducing the particle size,which increases the proportion of small droplets.Compared with the working conditions of plasma-assisted atomization without the gliding arc,the D0.5,D0.9,and average particle size of the fuel droplets are reduced by 4.7%,6.5%,and 4.1%,respectively,when the modulation voltage of the gliding arc power supply is 200 V.

The Influence of Sea Sprays on Drag Coefficient at High Wind Speed

Field and laboratory observations indicate that the variation of drag coefficient with wind speed at high winds is different from that under low-to-moderate winds.By taking the effects of wave development and sea spray into account,a new parameterization of drag coefficient applicable from low to extreme winds is proposed.It is shown that,under low-to-moderate wind conditions so that the sea spray effects could be neglected,the nondimensional aerodynamic roughness first increases and then decreases with the increasing wave age;whereas under high wind conditions,the drag coefficient decreases with the increasing wind speed due to the modification of the logarithmic wind profile by the effect of sea spray droplets produced by bursting bubbles or wind tearing breaking wave crests.The drag coefficients and sea surface aerodynamic roughnesses reach their maximum values vary under different wave developments.Correspondingly,the reduction of drag coefficient under high winds reduces the increasing rate of friction velocity with increasing wind speed.

Enhancing energetic performance of metal-organic complex-based metastable energetic nanocomposites by spray crystallization

Energetic metal-organic complexes have been involved in nanothermites as novel oxidants.However,the existing preparation methods often lead to mixing inhomogeneity and small contact area of ingredients,the reactivity and functionality of the novel energetic nanocomposites are still limited.In this work,spray crystallization(SC)method was used to prepare novel energetic nanocomposites,the high-energy metal-organic complex[Ni(CHZ)_(3)](ClO_(4))_(2)(CHZ=1,3-diaminourea)was composited with nanoaluminum(n-Al).Results showed that n-Al/[Ni(CH_(2))_(3)](ClO_(4))_(2)energetic nanocomposites prepared by SC method increased heat release to 2977.6 J/g and peak pressure to 3.91 MPa with higher pressurization rate(1324.06 MPa/s),decreased sensitivity thresholds(>100 mJ)to electrostatic discharge(ESD)and enhanced detonation ability compared with[Ni(CHZ)_(3)](ClO_(4))_(2)alone and physically mixed(PM)n-Al/[Ni(CHZ)_(3)](ClO_(4))_(2).These results proved that it is significant to introduce energetic metal-organic complexes with inherent high energy in new-concept n-Al/energetic metal-organic complexes nanocomposites through SC method for a better performance of its application.

Residual stress with asymmetric spray quenching for thick aluminum alloy plates

Solution and quenching heat treatments are generally carried out in a roller hearth furnace for large-scale thick aluminum alloy plates.However,the asymmetric or uneven spray water flow rate is inevitable under industrial production conditions,which leads to an asymmetric residual stress distribution.The spray quenching treatment was conducted on self-designed spray equipment,and the residual stress along the thickness direction was measured by a layer removal method based on deflections.Under the asymmetric spray quenching condition,the subsurface stress of the high-flow rate surface was lower than that of the low-flow rate surface,and the difference between the two subsurface stresses increased with the increase in the difference in water flow rates.The subsurface stress underneath the surface with a water flow rate of 0.60 m^(3)/h was 15.38 MPa less than that of 0.15 m^(3)/h.The simulated residual stress by finite element(FE)method of the high heat transfer coefficient(HTC)surface was less than that of the low HTC surface,which is consistent with the experimental results.The FE model can be used to analyze the strain and stress evolution and predict the quenched stress magnitude and distribution.

Effect of Intake Conditions and Nozzle Geometry on Spray Characteristics of Group-Hole Nozzle

The group-hole nozzle concept is proposed to meet the requirement of nozzle hole minimization and reduce the negative impact of poor spatial spray distributions.However,there are limited researches on the effects of intake conditions and nozzle geometry on spray characteristics of the group-hole nozzle.Therefore,in this study,an accurate spray model coupled with the internal cavitating flow was established and computational fluid dynamics(CFD)simulations were done to study the effects of intake conditions and nozzle geometry on spray characteristics of the group-hole nozzle.Experimental data obtained using high-speed digital camera on the high-pressure common rail injection system was used to validate the numerical model.Effects of intake conditions(injection pressure and temperature)and nozzle geometry(orifice entrance curvature radius and nozzle length)on the flow and spray characteristics of the group-hole nozzle were studied numerically.The differences in Sauter mean diameter(SMD),penetration length and fuel evaporation mass between single-hole nozzle and group-hole nozzle under different nozzle geometry were also discussed.It was found that the atomization performance of the group-hole nozzle was better than that of the single-hole nozzle under same intake conditions,and the atomization effect of the short nozzle was better than that of the long nozzle.With increase in the orifice entrance curvature radius,the average velocity and turbulent kinetic energy of the fuel increased,which was conducive to improving the injection rate and flow coefficient of the nozzle.Meanwhile,the penetration length and SMD value rose,while evaporation mass dropped.When the ratio of the orifice entrance curvature radius(R)to the diameter of injection hole(D)was 0.12,the spray characteristics reached a constant state due to elimination of cavitation.Conclusions were made based on these.This study is expected to be a guide for the design of the group-hole nozzle.

Experimental Investigation on Macro Spray Characteristics of Octanol-Biodiesel-Diesel Ternary Fuel Blend

This study investigates the spray characteristics of ternary blends composed of octanol, biodiesel, and diesel fuel.Experiments are conducted using six materials to examine the variation in spray characteristic and to verify and compare a previously established spray tip penetration model with a modified model. The results show that the addition of OB100(30%of octanol, 70% of biodiesel) improves the spray characteristics of the fuel. Specifically, the addition of 10% or 20% of OB100 leads to a slight increase in the spray tip penetration, average spray cone angle, maximum spray width, and the spray area of the fuel blend;however, further addition of OB100 causes a corresponding decrease in these parameters. Based on previous research, this study uses kinematic viscosity instead of dynamic viscosity and density to modify the prediction model of spray tip penetration. The modified model exhibits a better fit quality and agreement with the experimental data,making it more suitable for predicting the spray tip penetration of fuel blends compared to the Hiroyasu-Arai model.

Spray Characteristics of Non-Circular Nozzle in Air-Assisted Injection System

In order to analyze the spray characteristics of non-circular nozzle holes based on the air-assisted spray system, the spray characteristics of circular and non-circular nozzles were studied under the pressure of 0.2-0.6 MPa and the spray volume of 1000-5000 mL/h. Elliptical nozzle and triangular nozzle are classified as non-circular geometries. The spray cone angle was measured by processing the spray image captured by a CCD camera. The measured spray cone angles of the circular nozzles were analyzed, and the axis switching phenomenon of minor plane of elliptical nozzle was found during the test. Among the three shapes of nozzles, the elliptical nozzle had the largest spray cone angle, and the triangular nozzle had the smallest. The velocity field obtained depended on the PIV system. The results show that for axial velocity, elliptical orifice spray has greater kinetic energy and smaller droplet size under the same working parameters. Compared with the circular and elliptical nozzles, triangular orifice reached maximum spray velocity the fastest, but its velocity decay was the fastest. For radial velocity, away from the axis, the spray velocity of the elliptical orifice was less affected by the injection parameters, and the velocity was less than that of circular orifice and triangle orifice. Increasing air pressure will weaken radial propagation. The increase of liquid spraying rate had no remarkable effect on the increase of spraying rate. The results of particle size analysis show that the particle size of the non-circular orifice is reduced compared with that of the circular orifice, which promotes the breakup of droplets to a certain extent and enhances the atomization effect.

Spray Effect on the Thermal Performances of a Dry Cooling Tower

Pre-cooling the inlet air of a dry cooling tower by means of a spray can improve the tower performance during periods of high temperature.To study the spray effect on the thermal performance of natural draft dry cooling towers(NDDCTs),in this study 3-D numerical simulations of such a process have been conducted using Fluent 16.2(a two-way coupled Eulerian-Lagrangian approach).The considered NDDCT is 120 m high and only half system is simulated due to its structural symmetry.Three different spray strategies have been investigated at a typical crosswind speed of 4 m/s,which is the most frequent wind speed.The results have shown that:(1)The three implemented spray strategies can improve the thermal performance of the studied NDDCT with a vary-ing degree of success.In one case,the heat rejection rate can be increased by 35.2%,and the tower outlet water temperature can be decreased by 2.1℃ when compared with the no spray case;(2)To improve the thermal per-formance of the NDDCT using a small amount of water,the design of the spray pre-cooling system must include more nozzles on the windward and fewer or even no nozzles on the leeward sides of the NDDCT.

Spray Prediction Model for Aonla Rust Disease Using Machine Learning

Disease prediction in plants has acquired much attention in recent years.Meteorological factors such as:temperature,relative humidity,rainfall,sunshine play an important role in a plan’s growth only if they are present in adequate amounts as required by the plant.On the other hand,if the factors are inadequate,they may also support the growth of a disease in the plants.The current study focuses on the Rust disease in Aonla fruits and leaves by utilizing a real time dataset of weather parameters.Fifteen different models are tested for spray prediction on conducive days.Two resampling techniques,random over sampling(ROS)and synthetic minority oversampling technique(SMOTE)have been used to balance the dataset and five different classifiers:support vector machine(SVM),logistic regression(LR),k-nearest neighbor(kNN),decision tree(DT)and random forest(RF)have been used to classify a particular day based on weather conditions as conducive or non-conducive.The classifiers are then evaluated based on four performance metrics:accuracy,precision,recall and F1-score.The results indicate that for imbalanced dataset,kNN is appropriate with high precision and recall values.Considering both balanced and imbalanced dataset models,the proposed model SMOTE-RF performs best among all models with 94.6%accuracy and can be used in a real time application for spray prediction.Hence,timely fungicide spray prediction without over spraying will help in better productivity and will prevent the yield loss due to rust disease in Aonla crop.

Cost Efficient Automated Fog Spraying Machine: A Covid-19 Hand Sanitization Solution

As a result of the introduction of new infectious illnesses,key infection prevention measures were implemented.Now,a new coronavirus(SARS-CoV-2)epidemic has expanded swiftly,causing the coronavirus illness 2019(COVID-19).Many microorganisms spread illness via hospital surfaces due to environmental pollution.This virus has been associated to close contact between persons in tight situations such as houses,hospitals,assisted living,and residential institutions.Aside from health care settings,public buildings,faith-based community centers,marketplaces,transportation,and corporate environments are prone to COVID-19 transmission.Physical contact to the sanitizer device may cause for spread Covid virus.That’s why we have pro-posed an automatic fogger mechanism-based hand sanitizer that may able to reduce covid risk.Disinfectant fog will flow when object will pass through the machine.This project will save cost,time and wastage along with Covid spreading risk.This project is about designing a good healthcare system.In recent years,sophisticated automation has influenced the health industry.Health care in poor nations is costly.So,the project is an attempt to tackle this issue.

Study on the Attack of Molten Silicates on Plasma-Sprayed Thermal Barrier Coatings

Thermal barrier coating (TBC) revolutionized the industry by allowing higher operating temperatures for equipment, such as gas turbines in the aeronautical industry. However, at high temperatures, the TBC is exposed to the attack of molten silicates, known as CMAS (Calcium-Magnesium-Alumino-Silicate), which are particles from the environment that infiltrate the TBC, causing delamination. In this study, samples coated with TBC by thermal spray and covered with CMAS were evaluated at temperatures of 1200˚C and 1250˚C. For each temperature, exposure times of 1 h and 5 h were used. Samples with longer exposure time had a considerable volume increase. The main contribution of this work was to demonstrate the non-wettability of the CMAS, even in the 5-h heat treatments, which prevented its infiltration in the deeper regions. The conditions to guarantee the formation of the silicate and its consequent wettability are also discussed.

Curative Effect of 30% Supramolecular Salicylic Acid Combined with Yufa Spray Dressing on Moderate to Severe Scalp Seborrheic Dermatitis

Objective:To observe the clinical efficacy of 30%supramolecular salicylic acid combined with Yufa spray dressing in the treatment of moderate to severe seborrheic dermatitis(seborrheic dermatitis of the scalp,SDS).Methods:From January 2020 to December 2021,150 patients with SDS,who were treated in the Dermatology Clinic of the First Affiliated Hospital of Xi’an Medical University,were randomly divided into two groups,a treatment group and a control group,with 75 cases in each group.The treatment group was given 30%supramolecular salicylic acid combined with Yufa spray dressing on the basis of external medicine given to the control group,while the control group was given oral medicine combined with external medicine.Results:The difference in scores of erythema,scales,pruritus,and folliculitis of the treatment group before and after treatment was significant(P<0.01),indicating that supramolecular salicylic acid combined with Yufa spray dressing can relieve the symptoms of SDS.The difference in scores of erythema of the control group before and after treatment was significant as well(P<0.05),indicating that traditional antibiotics are also effective in treating SDS;however,there was no significant difference(P>0.05)in the scores of other signs and symptoms,such as scales,pruritus,and folliculitis,before and after treatment,indicating that traditional antibiotics have no obvious curative effect on SDS.After 12 weeks of treatment,the improvement in erythema,scaling,and folliculitis was significantly greater in the treatment group compared with the control group(P<0.05).Curative effect comparison showed that the total effective rate of the treatment group was 80.00%,compared with 25.67%of the control group,and the difference was statistically significant(P<0.05).Conclusion:30%supramolecular salicylic acid combined with Yufa spray dressing can significantly improve the therapeutic effect in moderate to severe SDS;the recurrence rate is lower,the course of treatment is shorted,and patients generally feel better;thus,it is a new option for the treatment of dermatitis.

Coordination of distinctive pesticide adjuvants and atomization nozzles on droplet spectrum evolution for spatial drift reduction

Pesticide adjuvants,as crop protection products,have been widely used to reduce drift loss and improve utilization efficiency by regulating droplet spectrum.However,the coordinated regulation mechanisms of adjuvants and nozzles on droplet spectrum remain unclear.Here,we established the relationship between droplet spectrum evolution and liquid atomization by investigating the typical characteristics of droplet diameter distribution near the nozzle.Based on this,the regulation mechanisms of distinctive pesticide adjuvants on droplet spectrum were clarified,and the corresponding drift reduction performances were quantitively evaluated by wind tunnel experiments.It shows that the droplet diameter firstly shifts to the smaller due to the liquid sheet breakup and then prefers to increase caused by droplet interactions.Reducing the surface tension of sprayed liquid facilitates the uniform liquid breakup and increasing the viscosity inhibits the liquid deformation,which prolong the atomization process and effectively improve the droplet spectrum.As a result,the drift losses of flat-fan and hollow cone nozzles are reduced by about 50%after adding organosilicon and vegetable oil adjuvants.By contrast,the air induction nozzle shows a superior anti-drift ability,regardless of distinctive adjuvants.Our findings provide insights into rational adjuvant design and nozzle selection in the field application.

Advancements in hemostatic strategies for managing upper gastrointestinal bleeding: A comprehensive review

Upper gastrointestinal(GI)hemorrhage presents a substantial clinical challenge.Initial management typically involves resuscitation and endoscopy within 24 h,although the benefit of very early endoscopy(<12 h)for high-risk patients is debated.Treatment goals include stopping acute bleeding,preventing rebleeding,and using a multimodal approach encompassing endoscopic,pharmacological,angiographic,and surgical methods.Pharmacological agents such as vasopressin,prostaglandins,and proton pump inhibitors are effective,but the increase in antithrombotic use has increased GI bleeding morbidity.Endoscopic hemostasis,particularly for nonvariceal bleeding,employs techniques such as electrocoagu-lation and heater probes,with concerns over tissue injury from monopolar electrocoagulation.Novel methods such as Hemospray and Endoclot show promise in creating mechanical tamponades but have limitations.Currently,the first-line therapy includes thermal probes and hemoclips,with over-the-scope clips emerging for larger ulcer bleeding.The gold probe,combining bipolar electrocoagulation and injection,offers targeted coagulation but has faced device-related issues.Future advancements involve combining techniques and improving endoscopic imaging,with studies exploring combined approaches showing promise.Ongoing research is crucial for developing standardized and effective hemorrhage management strategies.