Uncoated Plates Research Articles

Orthogonally polarized dual-wavelength Nd:LiYF4 laser at 1777 and 1789 nm with 1:1 output power ratio

Abstract A diode-pumped continuous-wave orthogonally polarized dual-wavelength Nd:LiYF4 (Nd:YLF) laser on 4F3/2 → 4I15/2 transition is studied. The output power ratio can be adjusted using two intracavity uncoated glass plates. At an incident pump power of 20 W, a dual-wavelength laser operating at 1777 nm in π-polarization and 1789 nm in σ-polarization was realized. The total output power of the dual-wavelength laser was more than 1.16 W with a 1:1 output power ratio. The total slope efficiency and total optical conversion efficiency with respect to the incident pump power were 4.6% and 2.9%, respectively. To the best of our knowledge, this is the first work realizing mid-infrared wavelength operation in Nd:YLF lasers on 4F3/2 → 4I15/2 transition.

Inactivation kinetics of dairy phages using photocatalytic paint under diverse environmental conditions and radiation sources

This article investigates the efficacy of a photocatalytic paint for bacteriophages inactivation under various levels of incident radiation flux, relative humidity and radiation sources. Two phages that infect lactic acid bacteria were selected: J-1, infective of Lacticaseibacillus casei ATCC 27139, and M13-G1b, infective of Streptococcus thermophilus G1b. Phage suspensions were deposited on coated and uncoated plates and exposed to radiation typically used for indoor illumination (λ = 360–720 nm). A first-order inactivation kinetics was proposed with respect to the Plaque Forming Units per mL (PFU/mL) that correlates the inactivation constant with the operating conditions. The kinetic constant of this novel model combines a potential function for the incident radiation flux and a logistic function for the relative humidity. The results showed that as these variables increased, phage inactivation turned higher for both uncoated and coated plates. Photonic and quantum efficiencies were also calculated for both phages, when treated with photocatalytic paint under UV-A radiation. The photonic efficiencies were 8.03 × 1012 PFU/Einstein for J-1 and 4.05 × 1012 PFU/Einstein for M13-G1b, while the quantum efficiencies were 1.19 × 1013 PFU/Einstein for J-1 and 6.03 × 1012 PFU/Einstein for M13-G1b. Good agreement was obtained between predictions of the proposed kinetic model and experimental data, with a Root Mean Square Error of 4.43 % for J-1 and 2.98 % for M13-G1b. The developed model would be useful to predict phage inactivation under diverse combinations of operating conditions levels in environments of dairy plants, different from those tested in this work.

Experimental and numerical study on explosion resistance of polyurea-coated shelter in petrochemical industry

To reduce the number of casualties in explosion accidents, blast-resistant shelters can be used to protect personnel in high-risk areas of petrochemical processing plants. In this work, the deformation behaviours of uncoated and polyurea-coated blast-resistant plates were studied through gas explosion tests. An ANSYS/LS-DYNA model of a polyurea-coated shelter was established, and the dynamic responses of the shelter under various explosion loads were analysed. A series of fuel–air explosion tests were carried out to investigate the explosion resistance of the full-scale shelter. The results showed that compared with the uncoated blast-resistant plate, the deformation of the polyurea-coated blast-resistant plate was significantly reduced. The overall deformation of the shelter was the central depression of the wall and the inward bending of the frame. The damage effect of a typical high-overpressure, low-duration load was greater than that of typical low-overpressure, long-duration load. The shelter remained intact under three repeated explosive loads, with cracks appearing on the inner wall but no collapse or debris splashing. The shock wave attenuation rate of the shelter reached over 90%, which could significantly reduce the number of indoor casualties.

Decellularized amniotic membrane hydrogel promotes mesenchymal stem cell differentiation into smooth muscle cells.

Previous studies showed that the bladder extracellular matrix (B-ECM) could increase the differentiation efficiency of mesenchymal cells into smooth muscle cells (SMC). This study investigates the potential of human amniotic membrane-derived hydrogel (HAM-hydrogel) as an alternative to xenogeneic B-ECM for the myogenic differentiation of the rabbit adipose tissue-derived MSC (AD-MSC). Decellularized human amniotic membrane (HAM) and sheep urinary bladder (SUB) were utilized to create pre-gel solutions for hydrogel formation. Rabbit AD-MSCs were cultured on SUB-hydrogel or HAM-hydrogel-coated plates supplemented with differentiation media containing myogenic growth factors (PDGF-BB and TGF-β1). An uncoated plate served as the control. After 2 weeks, real-time qPCR, immunocytochemistry, flow cytometry, and western blot were employed to assess the expression of SMC-specific markers (MHC and α-SMA) at both protein and mRNA levels. Our decellularization protocol efficiently removed cell nuclei from the bladder and amniotic tissues, preserving key ECM components (collagen, mucopolysaccharides, and elastin) within the hydrogels. Compared to the control, the hydrogel-coated groups exhibited significantly upregulated expression of SMC markers (p ≤ .05). These findings suggest HAM-hydrogel as a promising xenogeneic-free alternative for bladder tissue engineering, potentially overcoming limitations associated with ethical concerns and contamination risks of xenogeneic materials.

Evaluation of coating materials on the characterization of size and viability of virus-laden particles collected with an Andersen cascade impactor

Airborne pathogens are typically associated with particles, and the transport behavior of these particles is largely driven by their size. To better understand airborne transmission of viral diseases and develop effective control measures, proper size characterization of virus-laden particles is essential. The Andersen cascade impactor (ACI) is an 8-stage air sampler that separates aerosol particles into 9 aerodynamic size fractions. During sampling with an ACI under certain conditions, particles may bounce upon impact with the collection plates of the ACI, leading to eventual deposition on a stage further downstream than their target stage. Coating collection plates with adhesive materials may help decrease particle bounce; however, it may also affect the viability of collected pathogens. In this study, we evaluated different materials for their ability to minimize particle bounce while conserving virus viability during the collection of viral aerosol particles with an ACI. We evaluated nine materials - Tween® 80, silicone oil, Span® 85, Brij® 35, glycerol, mineral oil, gelatin, bovine serum albumin, and virus growth media - on their effect to inactivate H1N1 influenza virus and bovine coronavirus, a surrogate of SARS-CoV-2. Plates coated with gelatin, silicone oil, and mineral oil resulted in the least reduction of viability for both viruses. These materials were then used to sample viral aerosol particles in a wind tunnel. Results of physical particle collection, viral load and viral viability from the various ACI stages revealed no significant differences in aerodynamic size distribution between coated and uncoated plates, and the size distribution was similar to that reported by an optical particle sizer. Overall, our results did not support the need to coat ACI collection plates when characterizing viral aerosol particles under the conditions of this study. However, we did identify potential coating materials which could conserve virus viability maximally, if particle bounce is of concern.

Effect of the Al/Si ratio on intumescent Na-based geopolymer

This research investigates the fire resistance properties of alkali activated Na-based geopolymers (GP), used as steel protective coatings. The effect of different Al/Si molar ratios (0–0.54) is evaluated fire test. When coated on a steel plate, GP having the smaller Al/Si ratio exhibits an intumescent behavior with the highest expansion. When Al/Si = 0, the temperature at the backside of the steel plate is 313 °C which is decreased by 347 °C compared to an uncoated steel plate (660 °C). After fire testing, the GP physico-chemical properties are characterized with optical microscopy, Electron probe micro-analysis, dynamic mechanical analysis. According to stiffness test results, when the temperature approaches 100 °C, the GP with a given Al/Si ratio (different from zero) softens and expands (intumescence). The greater the Al/Si ratio in the GP, the more rigid the structure; this phenomenon limits expansion, and hence, lowers the fire protection.

Development of advanced cardiac progenitor cell culture system through fibronectin and vitronectin derived peptide coated plate

Cardiovascular disease remains a global health concern. Stem cell therapy utilizing human cardiac progenitor cells (hCPCs) shows promise in treating cardiac vascular disease. However, limited availability and senescence of hCPCs hinder their widespread use. To address these challenges, researchers are exploring innovative approaches. In this study, a bioengineered cell culture plate was developed to mimic the natural cardiac tissue microenvironment. It was coated with a combination of extracellular matrix (ECM) peptide motifs and mussel adhesive protein (MAP). The selected ECM peptide motifs, derived from fibronectin and vitronectin, play crucial roles in hCPCs. Results revealed that the Fibro-P and Vitro-P coated plates significantly improved hCPC adhesion, proliferation, migration, and differentiation compared to uncoated plates. Additionally, long-term culture on the coated plates delayed cellular senescence and maintained hCPC stemness. These enhancements were attributed to the activation of integrin downstream signaling pathways. The findings suggest that the engineered ECM peptide motif-MAP-coated plates hold potential for enhancing the therapeutic efficacy of stem cell-based therapies in cardiac tissue engineering and regenerative medicine.

Efficacy of lysostaphin-coated titanium plates on implant-associated MRSA osteitis in minipigs

PurposeThe growing incidence of implant-associated infections (IAIs) caused by biofilm-forming Staphylococcus aureus in combination with an increasing resistance to antibiotics requires new therapeutic strategies. Lysostaphin has been shown to eliminate this biofilm. Own studies confirm the effectiveness in a murine model. The current study characterizes the effects of lysostaphin-coated plates in an IAI minipig model.MethodsThe femur of 30 minipigs was stabilized with a five-hole plate, a bone defect was created, and in 20 cases methicillin-resistant Staphylococcus aureus was applied. Ten animals served as control group. After 14 days, local debridement, lavage, and plate exchange (seven-hole plate) were performed. Ten of the infected minipigs received an uncoated plate and 10 a lysostaphin-coated plate. On day 84, the minipigs were again lavaged, followed by euthanasia. Bacterial load was quantified by colony-forming units (CFU). Immunological response was determined by neutrophils, as well as interleukins. Fracture healing was assessed radiologically.ResultsCFU showed significant difference between infected minipigs with an uncoated plate and minipigs with a lysostaphin-coated plate (p = 0.0411). The infection-related excessive callus formation and calcification was significantly greater in the infected animals with an uncoated plate than in animals with a lysostaphin-coated plate (p = 0.0164/p = 0.0033). The analysis of polymorphonuclear neutrophils and interleukins did not reveal any pioneering findings.ConclusionThis study confirms the minipig model for examining IAI. Furthermore, coating of plates using lysostaphin could be a promising tool in the therapeutic strategies of IAI. Future studies should focus on coating technology of implants and on translation into a clinical model.

Dynamic roles of neutrophil extracellular traps in cancer cell adhesion and activation of Notch 1-mediated epithelial-to-mesenchymal transition in EGFR-driven lung cancer cells.

Neutrophil extracellular traps (NETs) are complex structures released by activated neutrophils that may modulate different steps of the metastatic cascade. The aim of our study was to investigate how NETs can modulate the adhesion properties of cancer cells and whether cell exposure to NETs can activate the epithelial-to-mesenchymal transition (EMT) program thus enhancing the migratory and invasive properties of tumor cells. Different cancer cell lines were subjected to a solid-phase adhesion assay using NET-coated plates with or without the addition of antibodies against α5β1 or CCDC25 receptor. After 1-4 h of incubation, adherent cells were expressed as the percentage of total cell number. To test EMT occurrence, cells were treated with NETs for up to 48 h and then the levels of E-cadherin, vimentin, Snail, Slug, Zeb 1 and Twist 1 along with levels of Notch 1 and cleaved Notch 1 were determined by western blotting. Untreated and NET-treated cells were subjected to migration assays using 24-multiwell plates with transwell and FBS as chemoattractant. Cancer cell adhesion to NET-coated plates varied between 30% and 92.7% and was significantly higher than that obtained in uncoated plates. The addition of antibodies against α5β1 or CCDC25 caused a strong reduction of cell adhesion to NETs. The prolonged exposure of EGFR-driven cancer cell lines to NETs caused the activation of the EMT program through the upregulation and cleavage of Notch 1 and was confirmed by the enhanced expression of EMT markers. The consequent loss of the epithelial phenotype induced a strong reduction of the expression of the oncogene driver. Cell migration was significantly enhanced in NET-treated cells as compared to untreated cells. Our findings reveal the dynamic role of NETs that may provide a DNA and fibronectin rich environment for binding of many cancer cells at distant sites where the prolonged exposure to NETs triggers the EMT through the activation of Notch 1 signaling pathway with the subsequent enhancement of migratory and invasive properties of cancer cells. Furthermore, our findings provide an example of how an immune/inflammatory microenvironment may directly modulate the sensitivity of cancer cells to oncogene targeted agents.

İmalat Ön Astar Kaplamanın S235JR Çeli̇ği̇ni̇n MAG ve SAW Yöntemleriyle Kaynaklanabi̇lirliği Üzeri̇ndeki̇ Etki̇sinin Karşılaştırmalı Olarak İncelenmesi̇

The outcome of a welding process relies on various factors, one of which is the heat input at the welded joint. Consequently, the thermal conductivity of the plates to be welded holds significant importance, just like the selection of the welding technique. This research investigates the impact of applying Metal Active Gas (MAG) and Submerged Arc Welding (SAW) methods on differently coated (shop-primer) plates, as well as un-coated S235JR structural steel plates. The study explores how these applications, with varying heat inputs, affect the mechanical and microstructural properties of the materials. Filler metal of SG2/S2 non-alloy steel grade wires was employed. The variable parameters chosen included surface conditions, coating thickness, and heat input. It was observed that altering the coating thicknesses and welding methods led to welding defects. Non-destructive tests indicated that surface conditions and welding methods somewhat influenced the weld joint. Specimens with a thickness of 75 µm exhibited poor performance in tensile, impact, and bending tests. Fractography studies validated these findings.

Designing a self-healable nano-structured thin film based on sustainable cerium-loaded ZIF8-MOF particles

Progressing the anti-corrosion performance of thin-film coatings has always been the focus of researchers. In this research, a novel high-resistance inorganic coating against corrosion was developed. For this aim, the steel plates treated with the Mn ion-containing zinc phosphate conversion coating were prepared and then covered with a layer of crystalline MOF nanoparticles. A robust self-healing effect was provided by the cerium cations loaded into the MOF thin coating, pores. FE-SEM, BET, XRD, and XPS were applied as the main analyses to characterize the successful formation of the conversion coating and the MOF grown on its layer. The uniformly grown MOF single crystals (particle size: 200–300 nm) could cover the porosities of the zinc phosphate coating so that no rust was detected after 600 h of keeping the sample in a very aggressive environment (salt spray chamber). Also; based on PDP results, the modified coating (ZPMnMOFCe) showed a sixty-fold drop in the corrosion rate compared to the uncoated plate. Meantime; after 24 h of exposure, its log|Z|10mHz was two orders of magnitude higher than that for the untreated mild steel.

Microstructure and Corrosion Resistance of Quartz Sand-Modified Enamel-Coated Steel Plates

Coating, as a corrosion protection measure, not only reduces the costs of repairs due to corrosion damage but also saves lives from injuries brought by corroded facilities or equipment. The corrosion behavior of quartz sand-modified enamel (QSME)-coated carbon steel plates was evaluated in a 3.5 wt.% NaCl solution for a period of 30 days using open circuit potential, electrochemical impedance spectroscopy (EIS), and linear polarization resistance. The enamel coating was made by firing enamel slurry to the steel plate at a temperature of around 840 °C. The effect of the size and content of quartz sand on the corrosion resistance is studied, considering four different contents (5 wt.%, 10 wt.%, 20 wt.%, and 30 wt.%) and two different particle sizes (0.38–0.83 mm and 0.83–1.70 mm). The microstructure and phase composition of QSME were characterized with a scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques. SEM images show that the thickness of QSME coating ranges from 430 to 1424 µm depending on the size of quartz sand, and the quartz sand is completely embedded in the enamel matrix. The QSME coating increases the corrosion resistance of uncoated steel plates by approximately 1000 times. The corrosion performance of QSME-coated plates decreases with an increase in quartz sand content, while the effect of the quartz sand size on the corrosion behavior is not significant. The QSME coating can be used to prolong the service lives of civil infrastructures subjected to chloride attack.

Green synthesis of zirconia nanoparticles and their characterization, anticancer activity and corrosion inhibition properties

Zirconia nanoparticles (ZrO2 NPs) were synthesized using leaf extract of Parkia biglandulosa (P. biglandulosa) (PBL). The structure of ZrO2 NPs was confirmed by various spectroscopic techniques such as UV–Vis, FTIR, XRD, SEM-EDAX and HR-TEM coupled with SAED pattern. Morphology was studied with a scanning electron microscope coupled with an energy-dispersive study (EDS) and a high-resolution transmission electron microscope (HR-TEM). The crystalline phase was analyzed using a selected area electron diffraction pattern (SAED). The tetragonal phase structure of the produced NPs was authenticated by the XRD pattern. The absorption bands at 616 and 619 cm−1 confirmed the Zr–O–Zr asymmetric and Zr–O stretching modes of ZrO2 NPs. The ZrO2 NPs were evaluated for their bactericidal activity against oral bacteria such as Lactobacillus acidophilus, Staphylococcus albus and Streptococcus mutans. The toxicity of the ZrO2 NPs was assessed by MTT assay on MCF7 breast cancer cells. The electrochemical impedance spectroscopy (EIS) and the Tafel polarization technique showed that the ZrO2 NPs mild steel (MS) exhibited greater anticorrosive behavior in 3.5% NaCl electrolyte compared with the uncoated MS plate.

Nonequilibrium Casimir–Polder Interaction between Nanoparticles and Substrates Coated with Gapped Graphene

The out-of-thermal-equilibrium Casimir–Polder force between nanoparticles and dielectric substrates coated with gapped graphene is considered in the framework of the Dirac model using the formalism of the polarization tensor. This is an example of physical phenomena violating the time-reversal symmetry. After presenting the main points of the used formalism, we calculate two contributions to the Casimir–Polder force acting on a nanoparticle on the source side of a fused silica glass substrate coated with gapped graphene, which is either cooler or hotter than the environment. The total nonequilibrium force magnitudes are computed as a function of separation for different values of the energy gap and compared with those from an uncoated plate and with the equilibrium force in the presence of graphene coating. According to our results, the presence of a substrate increases the magnitude of the nonequlibrium force. The force magnitude becomes larger with higher and smaller with lower temperature of the graphene-coated substrate as compared to the equilibrium force at the environmental temperature. It is shown that, with increasing energy gap, the magnitude of the nonequilibrium force becomes smaller, and the graphene coating makes a lesser impact on the force acting on a nanoparticle from the uncoated substrate. Possible applications of the obtained results are discussed.

Deep learning-based approach to R-134a bubble detection and analysis for geothermal applications

This study utilized deep learning to analyse bubble images of R134a fluid produced on bare and novel oleophilic coated stainless steel heat exchanger plates to compare the heat transfer performance in terms of bubble parameters. This work was carried out as a part of the GeoHex project. The vapour bubbles of the boiling R134a fluid, produced on two types of heat exchanger plates, were captured with a high-speed camera during a boiling experiment. A deep learning algorithm based on the Mask R–CNN model was trained for bubble detection in the experimental videos. The algorithm achieved a bubble detection accuracy of 61.22% and 78.6% for the coated and uncoated plates, respectively. The lower accuracy for the coated plate could be attributed to the challenge of distinguishing bubbles from the complex coating pattern. The algorithm determined the number of detected bubbles, bubble sizes, and centroids per frame, tracking each bubble frame by frame. The tracking results were used to calculate the bubble parameters such as departure frequency, departure diameter, and active nucleation site density. The calculated departure diameter for both plates exhibited a difference of 3%, which corresponded closely to the experimental results showing a 4% variation in heat transfer coefficient, which was measured under identical experimental conditions utilizing the GeoHex rig. However, the calculated departure frequency and active nucleation site density exhibited a 17% disparity between the coated and uncoated plates, primarily stemming from the lower detection accuracy for the coated plate. Some limitations of the trained model were identified in accurately detecting very small, out of focus, and mutually occluded bubbles. Future research should focus on improving experimental rig designs to capture better side-view images and develop advanced machine learning or other techniques to address these limitations.

Demonstrating the absence of metal ion contamination in operando PEM fuel cells utilizing unmodified stainless steel bipolar plates

Using stainless steel as material for bipolar plates (BPPs) in proton exchange membrane fuel cells (PEMFCs) carries a perceived risk of corrosion and subsequent metal ion contamination of the membrane electrode assembly (MEA). However, assessments in literature on this hazard to PEMFC systems have been based on ex-situ corrosion studies, where general assumptions made on the BPP environment might not be a correct simulation of real on-site conditions. In this contribution, uncoated BPPs from stainless steel grades 304 L, 316 L and 904 L were subjected to in-situ hybrid endurance/stress testing to simulate realistic conditions in operating fuel cell systems and re-evaluate the need of additional corrosion protection. A post analysis of the plates showed no signs of surface dissolution on any of the tested samples and the concentration of iron in the MEA averaged 7 to 10 ppm for uncoated samples and 7 to 11 ppm for coated and graphitic reference tests, displaying a negligible amount of trace metals compared to critical thresholds found in literature. Contact resistance values were stable for all samples and observable changes in cell performance and voltage degradation was confirmed to be unrelated to the presence of uncoated bipolar plates. The combined effects of decoupling of bipolar plate surface potentials from electrode potentials and operational control of stable gas flow compositions to sustain stainless steel surface passivation, were identified as explanation for the experimentally observed corrosion resistance of uncoated stainless steel plates in PEMFCs.

Experimental Investigation and Optimization Analysis of a Designed Wastewater Treatment System

Wastewater, crude oil, gas, and solid particles are extracted from underground as products during oil production and there are various methods for treating this wastewater. In this study, a corrugated plate treatment system using the gravitational treatment method was designed as a wastewater treatment method. In the designed system, wastewater (oil–water mixture) was treated using uncoated corrugated plates and corrugated plates coated with hydrophobic material. The effects of hole diameter, length, and curvature angle of the corrugated plates; pumping speed of the mixture into the system; mounting angle of the corrugated plate sets; and the distance between the plates on treatment capacity in the case of using coated and uncoated plates were experimentally investigated. In order to statistically examine the effect of the parameters and the hydrophobic material used on the treatment capacity, the relevant parameters were optimized using the response surface method (RSM) and Box–Behnken design. It was observed that there are significant changes in the treatment capacity due to events (flow treatment, decrease in boundary layer thickness, and change in fluid energy). In addition, it was concluded that coating the plates increased the treatment capacity and the mounting angle of the plate sets in the system greatly affected the treatment capacity.

Advancement in biological and mechanical behavior of 3D printed poly lactic acid bone plates using polydopamine coating: Innovation for healthcare

The metallic biomaterials have been proclaimed to exhibit stress shielding with discharge of toxic ions, leading to polymeric implants attracting interest in 3D Printing domain. In this study, Poly Lactic Acid based 336 bone plates are fabricated using Fused Filament Fabrication with printing parameters being varied. Polydopamine, being biocompatible, is deposited on fabricated bone plates at varying submersion time, shaker speed and coating solutions concentration. The study involves witnessing the effect of printing and coating parameters on biological behavior of bone plates upon preservation in Simulated Body Fluid and Hank's Balanced Salt Solution. The findings propose the close relation of degradation with apatite growth. The highest degradation rate with significant reduction in mechanical characteristics are shown by uncoated bone plates. These bone plates have porous structure at 20% infill density, 0.5 mm layer height, 0.4 mm wall thickness and 100 mm/s print speed which could result in complete degradation with partial healing of bone fracture. The study suggests the preservation of bone plates coated at 120 h' submersion time and 120 RPM shaker speed in 3 mg/ml concentrated solution which showed lower apatite formation. Thus, the coating would slow down degradation of PLA bone plates, resulting in complete healing of bone fracture.

Study on the penetration resistance of a honeycomb composite structure coated with polyurethane elastomer

In this study, the ballistic performance of the composite structure was investigated and studied by experiment and finite element analysis in order to study the anti-penetration performance of a polyurethane elastomer-coated honeycomb sandwich construction. Six kinds of target plate structures with different configurations were prepared by changing the hard segment content and coating position of polyurethane elastomer. The first-stage light gas gun device is used to conduct impact experiments at various speeds, and the finite element simulation computation is performed using LS-DYNA. Based on the experimental and finite element results, the ballistic limit velocity and specific energy absorption of different target configurations were analyzed, and the failure forms, damage areas, and failure mechanisms were discussed. The findings demonstrate that the polyurethane elastomer coating enhances the honeycomb sandwich structure’s ballistic limit performance by 40.6% to 51% and that the honeycomb core of the target plate with the coating on the front panel has a larger area of collapse. This fully exploits the benefits of the honeycomb structure in the energy absorption process and makes up for the weaknesses of the honeycomb sandwich structure’s subpar energy absorption effect under local impact loads. Therefore, the front panel coating has better ballistic limit performance. The coated polyurethane with medium hardness demonstrated the best ballistic limit performance for the various polyurethane hardness. The ballistic limit speeds of the front panel and back panel coatings increased by 51% and 48.8% respectively, in comparison to the uncoated target plate. After comparing the structure of polyurea coating, it is found that the ballistic limit performance of polyurethane coating with medium hardness is higher than that of polyurea coating structure, and the negative growth of the ballistic limit performance of the whole structure caused by the coating of rigid polyurea on the back panel is effectively avoided.

Experimental Characterization of the Wettability of Coated and Uncoated Plates for Indirect Evaporative Cooling Systems

Indirect Evaporative Cooling (IEC) is a very promising technology to substitute and/or integrate traditional air conditioning systems, due to its ability to provide cooling capacity with limited power consumption. Literature studies proved that a higher wettability of the IEC plates corresponds to better performance of the system. In this work, wettability of three different surfaces used for IEC systems plates—uncoated aluminum alloy (AL), standard epoxy coating (STD), and a hydrophilic lacquer (HPHI)—is studied and characterized in terms of static and dynamic contact angles. The static contact angle resulted to be the lowest for the HPHI surface (average 69°), intermediate for the STD surface (average 75°), and the highest for the AL surface (average 89°). The analysis of the dynamic contact angles showed that their transient behavior is similar for all the surfaces, and the advancing and receding contact angles obtained are consistent with the results of the static analysis. These results will be useful as input parameters in models aimed at predicting the IEC system performance, also using computational fluid dynamics.