Coat Layer Research Articles

Features of thermal processes and the influence of pulsed heating of surface layers of titanium on the diffusion transfer of dopants during high-intensity ion implantation

Methods for modification of surface and near-surface layers of materials and coatings by ion beamshave prospects for application in many fields of science and technology. The method of high-intensityimplantation by high-power density ion beams with submillisecond duration involves significantpulsed heating of the irradiated target’s surface layer, followed by its rapid cooling due to heatremoval into the material due to thermal conductivity and the implementation of repetitively-pulsedradiation-enhanced diffusion of atoms to depths significantly exceeding the projective ion range. Thispaper considers features of thermal processes and the effect of pulsed heating of near-surface titaniumlayers on diffusion transfer under conditions of synergy of high-intensity titanium ion implantationand energy impact of a high-power density repetitively-pulsed beam on the surface to increase iondoping depth due to radiation-enhanced diffusion under conditions of limited heating of the entiresample. The paper presents the data of numerical simulation of dynamic changes in temperature fieldsin titanium and titanium self-diffusion under the action of ion beams with a submillisecond durationand a pulse power of tens of kW/cm2 and fluence of ions in a pulse 1.25×1015 ion/cm2.

Suspension High‐Velocity Oxy‐Fuel–Sprayed Dense Vertically Cracked and Suspension‐Plasma‐Sprayed Columnar Yttria‐Stabilized Zirconia Coatings: Calcia Magnesia Alumino Silicates Infiltration and Thermal Cycling Performance

The quest to increase the surface temperatures and resistance to the corrosive environment of thermal barrier coatings topcoats mean that newer coating design strategies are needed. In this study, a performance evaluation of suspension high‐velocity oxy‐fuel (SHVOF)‐sprayed dense vertically cracked (DVC) and suspension‐plasma‐sprayed (SPS) columnar structure (CS) topcoats is conducted. The calcia magnesia alumino silicate (CMAS) evaluation is conducted at 1300 °C for 30 min, whereas the furnace cycling tests (FCT) is conducted at 1135 °C for 45 min cycle dwell time. The CMAS infiltrates down to the bond coat layer, but does not induce partial or complete topcoat spallation on all studied topcoat layers. In terms of CMAS infiltration, the CMAS appears to be restricted along the vertical cracks. The FCT of the SPS CS structure indicates a failure largely at the thermally grown oxide (TGO)–topcoat interface, while the DVC topcoat layers indicate a mix‐mode failure, i.e., both material‐associated cracking and localized spallations at the TGO–topcoat interface. Overall, the SHVOF‐sprayed ethanol‐based DVC topcoat seems to offer a balanced trade‐off, i.e., a majority of the topcoat is still intact after 100 thermal cycles and exceeds the material durability and performance offered by the SPS CS structure.

Impact of bond coat types on calcium-magnesium-alumina-silicate and hot corrosion behavior in thermal barrier coatings

This study examines the corrosion behavior of thermal barrier coatings (TBCs) with bond coats (BCs) fabricated using Air plasma spraying (APS) and High velocity oxygen fuel (HVOF) against molten salt and Calcium-magnesium-alumina-silicate (CMAS) corrosion. Results show that TBCs with the APS-BC have higher resistance and experience fewer failures than those with the HVOF-BC due to the further growth of the aluminum-rich oxide layer in APS-BC coatings, causing the salt to be neutralized during the reaction with BC. The products of the reaction between CMAS and TGO lead to changes in coating interface morphology and degradation in coatings with HVOF BC.

Corrosion Protection Behavior of Aluminate Ion-Loaded Layered Double Hydroxide Coating on AZ31 Magnesium Alloy

Effect of aluminate ion loading on the corrosion behavior of layered double hydroxide (LDH) coating of Mg-3Al-1Zn (AZ31) alloy was investigated. The corrosion inhibition performance of NaAlO2 for AZ31 was examined by immersion and polarization tests. Then, aluminate ion-loaded LDH (LDHAlO2) was synthesized from hydrotalcite (LDHCO3) and co-deposited with magnesium and aluminum double hydroxide on AZ31 by electrophoretic co-deposition. Polarization, electrochemical impedance (EI) and wet-dry cyclic corrosion tests were conducted on the LDHAlO2- and LDHCO3-coated specimens. Adding 10–50 mmol l−1 NaAlO2 to 0.1 mol l−1 NaCl solution induced a clear passive region on the polarization curves of AZ31 and shifted the breakdown potential over −1.0 V (Ag/AgCl), indicating the corrosion inhibition property of NaAlO2. In the polarization and EI tests, the aluminate ion loading did not noticeably enhance the corrosion protection ability of the LDH coating as shown by higher quasi-passive current density and lower R p than without loading. However, in the wet-dry corrosion tests, the LDHAlO2-coated AZ31 demonstrated less weight gain and fewer clusters of shallow micro-pits, while the LDHCO3-coated AZ31 showed numerous deeper pits on the entire surface. It was revealed that loading aluminate ions to the LDH coatings is promising for enhancing their corrosion protection ability in atmospheric environments.

Assessment of Novel Erythroid Signaling Pathways Modulating Hydroxyurea-Mediated Reduction of Vaso-Occlusive Adhesive Interactions in Early Precursors of Sickle Red Blood Cells (RBCs)

Sickle cell disease (SCD) affects ~100,000 Americans and millions worldwide, with healthcare costs in the U.S. exceeding $1 billion annually to treat frequent and unpredictable vaso-occlusive episodes (VOEs). In addition to fetal hemoglobin induction, hydroxyurea (HU) reduces the frequency of VOEs by increasing nitric oxide (NO) bioavailability and decreasing adhesion receptor expression and RBC-endothelial interactions. Very late antigen-4 (VLA-4), the best characterized adhesion receptor in SCD, is highly expressed on circulating reticulocytes (immature RBCs) and white blood cells (WBCs) during VOEs and in SCD patients with severe disease phenotypes and, decreased in response to HU therapy. Like other integrins, VLA-4 is functionally regulated by cell signaling pathways to modulate activity and binding affinity to a wide variety of ligands that are elevated in the SCD micro-environment. There is highly intriguing evidence showing HU modulates adhesion by upregulating a NO/cGMP-dependent pathway to decrease adhesion receptor activity however specific mechanisms remain unclear. The objective of this study was to assess rapid cell signaling pathways involved in HU-mediated reduction in VLA-4 binding to endothelial vascular cell adhesion molecule-1 (VCAM-1). Whole blood (WB) was obtained from patients with SCD at benign clinic visits according to IRB-approved protocols. WB density-gradient centrifugation was used to isolate hematopoietic stem cells (HSCs) and WBCs from the buffy coat layer and, a CD71 monoclonal antibody (Ab) coupled with magnetic beads to isolate reticulocytes from the packed RBC layer. HSCs were matured to erythroblasts (EBs) in appropriate cell culture media and flow cytometric analyses assessed purity of blood samples using CD235a (exclusive WBC marker) and CD45 (exclusive RBC marker) Abs . Blood samples were pretreated with and without a therapeutically relevant hydroxyurea concentration (50mcM) followed by perfusion through micro-fluidic channels coated with VCAM-1 during pulsatile, shear flow (1.67Hz, 1.0 dyne/cm 2). Additionally, EBs were treated with HU combined and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1- one (ODQ; NO-dependent guanylate cyclase inhibitor). Adhered cells were quantified to establish an adhesion index. The non-parametric Wilcoxon matched pairs signed rank test was used to test the statistical differences between groups. Data are presented as mean ± standard error of mean. A p-value < 0.05 was considered statistically significant. There was a significant decrease in WB (p=0.01) and reticulocyte (p<0.0001) adhesion to VCAM-1 in HU-treated samples however, there was no effect on WBC (p>0.99) adhesion suggesting reticulocytes reduce the adhesive burden of blood cells in WB adhesion assays and modulation of VLA-4 binding differs in sickle RBCs when compared to WBCs. More recently, preliminary data from my lab demonstrated that EBs pretreated with HU reduces VLA-4 binding to VCAM-1 (from 126.5 ± 29.42 to 109.5 ± 29.09) by cGMP-dependent mechanisms (HU + ODQ; from 109.5 ± 29.09 to 120.2 ± 42.80). Laboratory-based static and flow adhesion assays have been used for decades to describe adhesion in SCD since earlier studies established that sickle RBCs are more adherent than non-sickle blood cells and, adhesion correlates with SCD severity. For example, the adhesion assay described above has been used to demonstrate that VLA-4 binding can stratify SCD patients based on disease severity and predict impending VOEs. Additionally, reticulocyte and HbF levels strongly correlate with VLA-4 binding to VCAM-1 and, VLA-4-mediated adhesion is increased during patient-reported VOEs and decreased in HU-treated SCD patients. This is the first SCD study demonstrating the role of HU in modulating VLA-4 binding to endothelial VCAM-1 through rapid erythroid signaling pathways. There is also compelling evidence involving downregulation of VLA-4 activity/binding affinity through NO/cGMP dependent mechanisms and enhancement of VLA-4 binding by kinase-dependent pathways. HU has also been shown to modulate adhesion by upregulating a NO/cGMP-dependent pathway to decrease adhesion receptor activity. Collectively, these data suggest that VLA-4 mechanisms may be targeted to therapeutically inhibit vaso-occlusive adhesive events that promote VOEs in SCD.

Introducing self-healing properties to polyethersulfone (PES) membrane via poly(vinyl alcohol)/ polyacrylic acid (PVA/PAA) surface coating

During membrane filtration, it is inevitable that a membrane will experience physical damage, leading to a loss of its integrity and a decrease in separation efficiency. Hence, the development of a water-responsive membrane capable of healing itself autonomously after physical damage is significantly important in the field of water filtration. Herein, a water-enabled self-healing composite polyethersulfone (PES) membrane was synthesized by coating the membrane surface using a mixed solution composed of poly (vinyl alcohol) and polyacrylic acid (PVA-PAA). The self-healing efficiency of the coated PES membrane was examined based on the changes in water flux at three stages which are pre-damaged, post-damaged, and post-healing. The self-healing process was initiated by the swelling of the water-responsive PVA and PAA, followed by the formation of reversible hydrogen bonds, completing the self-healing process. The coated PES membrane with three layers of PVA-PAA coatings (at 3:1 ratio) demonstrated high water flux and remarkable self-healing efficiency of up to 98.3%. The self-healing capability was evidenced by the morphology of the membrane observed via scanning electron microscope (SEM). The findings of this investigation present a novel architecture approach for fabricating self-healing membranes using PVA-PAA, in addition to other relevant parameters as reported.

A sporulation signature protease is required for assembly of the spore surface layers, germination and host colonization in Clostridioides difficile.

A genomic signature for endosporulation includes a gene coding for a protease, YabG, which in the model organism Bacillus subtilis is involved in assembly of the spore coat. We show that in the human pathogen Clostridioidesm difficile, YabG is critical for the assembly of the coat and exosporium layers of spores. YabG is produced during sporulation under the control of the mother cell-specific regulators σE and σK and associates with the spore surface layers. YabG shows an N-terminal SH3-like domain and a C-terminal domain that resembles single domain response regulators, such as CheY, yet is atypical in that the conserved phosphoryl-acceptor residue is absent. Instead, the CheY-like domain carries residues required for activity, including Cys207 and His161, the homologues of which form a catalytic diad in the B. subtilis protein, and also Asp162. The substitution of any of these residues by Ala, eliminates an auto-proteolytic activity as well as interdomain processing of CspBA, a reaction that releases the CspB protease, required for proper spore germination. An in-frame deletion of yabG or an allele coding for an inactive protein, yabGC207A, both cause misassemby of the coat and exosporium and the formation of spores that are more permeable to lysozyme and impaired in germination and host colonization. Furthermore, we show that YabG is required for the expression of at least two σK-dependent genes, cotA, coding for a coat protein, and cdeM, coding for a key determinant of exosporium assembly. Thus, YabG also impinges upon the genetic program of the mother cell possibly by eliminating a transcriptional repressor. Although this activity has not been described for the B. subtilis protein and most of the YabG substrates vary among sporeformers, the general role of the protease in the assembly of the spore surface is likely to be conserved across evolutionary distance.

Development of Graphene-Based Functional Coating for the Surface Modification of Textiles

The objective of the presented research is to improve the ballistic performance of para-aramid woven fabric by deposition of graphene coatings directly on woven textile substrates. The improvement of mechanical properties of the ballistic fabric is attributed to the formation of a highly ordered layered structure and the efficient load transfer between the fabric fibers and the graphene nanosheets. The results of deposition of layered graphene coatings on woven textiles are discussed here. The pristine graphite directly subjected to a solvent treatment in this work, which resulted in the production of exfoliated graphene sheets in the form of a dispersion that allow immediate utilization obtained dispersion for deposition on the para-aramid samples. In order to prepare the dispersion, graphite flakes were first dispersed into liquid media followed by graphite intercalation (division into microlayers) and nano-layers exfoliation. Dipolar aprotic organic solvent DMAc (N,N-Dimethylacetamide) and Cyrene (Dihydrolevoglucosenone) as a bio-based alternative for dipolar aprotic solvents were used as main components of liquid media. At the final stage, a stable dispersion of isolated flakes by using two types of liquid medium was obtained. To study the effects of dip coating and rolling parameters, six kinds of samples with different pull-out speeds and compression ratios were prepared, and their functional properties were measured and compared.

The Use of Polyurethane Composites with Sensing Polymers as New Coating Materials for Surface Acoustic Wave-Based Chemical Sensors—Part I: Analysis of the Coating Results, Sensing Responses and Adhesion of the Coating Layers of Polyurethane–Polybutylmethacrylate Composites

The sensing layers for surface acoustic wave-based (SAW) sensors are the main factor in defining the selectivity and reproducibility of the responses of the sensor systems. Among the materials used as sensing layers for SAW sensors, polymers present a wide range of advantages, from availability to a large choice of chemical-sensing environments. However, depending on the physical–chemical properties of the polymer, issues about the chemical and mechanical stability of the sensing layer have been reported that can compromise the application of sensor systems in the long-term. The sensor properties are defined basically by the properties of the coating material and the quality of the coating process. The strategy used to improve the properties of polymeric coating layers for SAW technology involved the use of polyurethane (PU) in combination with a second polymer that is responsible for the sensing properties of the resulting layer; this is obtained by a reproducible and robust coating procedure. In this first part of our research, we used polymer composites of different compositions of polybutylmetacrylate (PBMA) as the sensing polymer with polyurethane. The analysis of the coating (ultrasonic parameters), the relative sensor responses and the adhesion results for the PU–PBMA composites were determined. The ultrasonic analysis and the relative sensor responses showed very reproducible and precise results, indicating the reproducibility and robustness of the coating process. Accurate correlations between the results of the ultrasonic parameters due to the coating and the relative sensor responses for the organic analytes analyzed were obtained, showing a precise quantitative relationship between the results and the constitution of the composite coating materials. The composites show practically no significant sensor responses to water. The PU–PBMA composites substantially enhanced adhesion to the surface of the piezoelectric sensor element in comparison to the coating with pure PBMA, without loss of its sensing properties. Other PU–polymer composites will be presented in the future, as well as an analysis of the selectivity for the organic analytes for these types of coating materials.

Impressive hydrophobic TiO2@Cu mesh for electromagnetic interference shielding

This study investigated the surface modification of copper mesh using modified titanium dioxide (TiO2) coatings to enhance its surface hydrophobic properties while preserving electromagnetic interference (EMI) shielding effectiveness. Silicon-coupling-agent-treated titanium dioxide particles were employed to create micro/nanostructured superhydrophobic coatings. The deposition times were found to influence the coating distribution, pore filling and surface hydrophobicity. S-TiO2@Cu mesh with a single layer of modified titanium dioxide coating exhibited the highest water contact angle compared with T-TiO2@Cu mesh with triple layer coatings and the original O-TiO2@Cu mesh. The superior self-cleaning performance and robust wear resistance of the hydrophobic coatings for S-TiO2@Cu mesh were revealed. In addition, both S-TiO2@Cu mesh and T-TiO2@Cu mesh exhibited satisfactory EMI-shielding efficiency without compromising the intrinsic properties of the copper mesh. These findings provide practical insights into surface modification of copper mesh substrates, emphasizing the balance between surface properties and EMI shielding. The hydrophobic coatings hold promise for multifunctional applications, offering enhanced surface properties without compromising EMI-shielding performance.

Evaluation of Microstructure–Porosity–Hardness of Thermal Plasma-Sprayed NiTi Coating Layers

The quality of NiTi coating influences the thermal, microstructural, and mechanical behavior of the material produced by plasma spraying. To understand the behavior of the coating, the study has been designed and planned at two different plasma powers with various feed rates. NiTi as shape memory layers emerge as promising protective coatings on the surface of substrates against corrosion or wear. In the present investigation, NiTi multilayers were produced by thermal plasma spraying using NiTi (50 at. %) powder as the feedstock material. This work illustrates the studies of the microstructure, porosity of the coating layers, phase detection, hardness values, shape memory behavior, and the formation of samples produced by different spraying parameters. The porosity within coating layers has been analyzed based on the various shape factors of pores that correlate with the hardness and mechanical behavior of the samples. This work will explore the quality of the coating in terms of its porosity and compactness, which will affect the performance of the shape memory behavior. The functional coating of NiTi will have a significant influence on the durability of the material’s performance against corrosion.

Towards Unlocking/Tuning the Mott Transition Temperature in Alkaline-Doped Vanadium Oxide Thermochromic Coatings and Potential Green Air-Conditioning via Room Temperature VxOy-V-VxOy Layered Coatings

In this contribution, we validate for the first time that the near infrared-infrared (NIR-IR) modulation of the optical transmission (DTTRANS = T(T<TMIT) - T(T>TMIT)) of vanadium oxide-based nanomaterials can be controlled or tuned via a genuine approach with a simultaneous drastic reduction of its Mott transition temperature TMIT. More accurately, we report a significant thermochromism in multilayered V2O5/V/V2O5 stacks equivalent to that of pure VO2 thin films but with a far lower transition temperature TMIT. Such a multilayered V2O5/V/V2O5 thermochromic system exhibited a net control or tunability of the optical transmission modulation in the NIR-IR (DTTRANS) via the nano-scaled thickness of the intermediate vanadium layer. In addition, the control of DTTRANS is accompanied by a noteworthy diminution of the Mott transition temperature TMIT from the bulk value of 68.8 °C to the range of 27.5–37.5 °C. The observed peculiar thermochromism in the multilayered V2O5/V/V2O5 is likely to be ascribed to a significant interfacial diffusion or an excessive interfacial stress/strain, and/or to an effective halide (Na, K, Ca) doping. This doping is driven by a significant diffusion from the borosilicate substrate surface towards the V2O5/V/V2O5 stacks. If the upscaling of this approach is validated, the current findings would contribute to advancing thermochromic nanomaterials and their applications in smart windows for managing solar heat and green air-conditioning technologies.

Study of short-wavelength pass dichroic laser mirror coatings with hafnia–silica mixture layers

Hafnia/silica (HfO2/SiO2) short-wavelength pass dichroic laser mirror (DLM) coatings are widely utilized in high-power laser systems. However, the half-wave hole effect resulting from the refractive index inhomogeneity of HfO2 severely restricts the spectra and potential applications of these coatings. To address this issue, an investigation was conducted on HfO2–SiO2 mixture coatings with different proportions, which were produced by electron beam co-evaporation. Compared to the inhomogeneous growth characteristics observed in pure HfO2 coatings, the introduction of 10 % or higher SiO2 admixing in HfO2–SiO2 mixture coatings results in an amorphous structure characterized by excellent refractive index homogeneity and improved surface smoothness. Leveraging this, different DLM coatings with the objective of achieving high transmittance across the 400 to 900 nm range were designed and prepared, while ensuring high reflectance at 1064 nm. The incorporation of HfO2–SiO2 mixture layers instead of pure HfO2 layers in the mirror coatings led to a fundamental inhibition of the half-wave hole effect throughout the entire broad transmission band, resulting in a substantial improvement in the optical performance of the coatings. Moreover, by incorporating several types of HfO2–SiO2 mixture layers with different proportions in the coating stacks, the transmittance of DLM coatings in the pass band can be further increased, and the transmission fluctuations at different wavelengths can be further compressed. Additionally, compared to traditional DLM coatings with HfO2 layers, DLM coatings incorporating HfO2–SiO2 mixture layers exhibit lower roughness, higher laser-induced damage threshold (LIDT) at 532 nm, and similar LIDT at 1064 nm. These results indicate a promising strategy for fabricating DLM coatings tailored for high-power laser systems.

Optimizing Platelet-Rich Plasma: Spin Time and Sample Source.

The buff-colored layer separating the plasma from red blood cells (RBCs) in centrifuged blood was named the "buffy coat" in the late 19th century. The division of platelets (PLTs) and leukocytes (WBCs) between the buffy coat, plasma, and RBC layers in centrifuged blood has not been described before. In this study, we centrifuged 8.5 mL anticoagulated blood samples at 1000× g for 1, 2, 3, 5, 10, and 20 min. We then divided each sample into ten layers and analyzed each layer for cellular composition and mean platelet volume (MPV). Our results show that even after 20 min of centrifugation, about 15% of platelets remain in the plasma layers and 65% in the RBC layers. We found that the platelet count achieved from aspiration of 1 mL volume was optimal, with aspiration beginning 1/2 mL below the buffy coat and extending 1/2 mL above the buffy coat rather than beginning at the buffy coat itself and aspirating only plasma. Using this method of aspiration, we found that the total platelet count means reached a maximum in the 1 mL around the buffy coat after only 5 min of centrifugation.

Facile Solid-State Synthesis to In Situ Generate a Composite Coating Layer Composed of Spinel-Structural Compounds and Li3PO4 for Stable Cycling of LiCoO2 at 4.6 V.

Due to its high energy density, high-voltage LiCoO2 is the preferred cathode material for consumer electronic products. However, its commercial viability is hindered by rapid capacity decay resulting from structural degradation and surface passivation during cycling at 4.6 V. The key to achieving stable cycling of LiCoO2 at high voltages lies in constructing a highly stable interface to mitigate surface side reactions. In this study, we present a facile in situ coating strategy that is amenable to mass production through a simple wet-mixing process, followed by high-temperature calcination. By capitalizing on the facile dispersion characteristics of nano-TiO2 in ethanol and the ethanol dissolubility of LiPO2F2, we construct a uniform precoating layer on LiCoO2 with nano-TiO2 and LiPO2F2. The subsequent thermal treatment triggers an in situ reaction between the coating reagents and LiCoO2, yielding a uniform composite coating layer. This composite layer comprises spinel-structured compounds (e.g., LiCoTiO4) and Li3PO4, which exhibit excellent chemical and structural stability under high-voltage conditions. The uniform and stable coating layer effectively prevents direct contact between LiCoO2 and the electrolyte, thereby reducing side reactions and suppressing the surface passivation of LiCoO2 particles. As a result, coated LiCoO2 maintains favorable electronic and ionic conductivity even after prolonged cycling. The synergistic effects of spinel-structured compounds and Li3PO4 contribute to the superior performance of LiCoO2, demonstrating a high capacity of 202.1 mA h g-1 (3.0-4.6 V, 0.5 C, 1 C = 274 mA g-1), with a capacity retention rate of 96.7% after 100 cycles.

PEI/Super P Cathode Coating: A Pathway to Superior Lithium–Sulfur Battery Performance

Lithium–sulfur batteries exhibit a high energy density of 2500–2600 Wh/kg with affordability and environmental advantages, positioning them as a promising next-generation energy source. However, the insulating nature of sulfur/Li2S and the rapid capacity fading due to the shuttle effect have hindered their commercialization. In this study, we propose a method to boost the performance of lithium–sulfur batteries by modifying the sulfur cathode with a coating layer composed of polyethyleneimine (PEI) and Super P conductive carbon. The PEI/Super P-modified electrode retained 73% of its discharge capacity after 300 cycles at the 2 C scan rate. The PEI/Super P coated layer effectively adsorbs lithium polysulfides, suppressing the shuttle effect and acting as an auxiliary electrode to facilitate the electrochemical reactions of sulfur/Li2S. We analyzed the PEI/Super P-modified electrodes using symmetric cells, electrochemical impedance spectroscopy, and cyclic voltammetry. The battery manufacturing method presented here is not only cost-effective but also industrially viable due to its compatibility with the roll-to-roll process.

Investigation on wear behaviour of TiC/Co/Y2O3 metal matrix composite coating developed on AZ91D Mg alloy by plasma transferred arc cladding process

A high wear resistant TiC/Co/Y2O3 composite coating was synthesized on the surface of AZ91D Mg alloy by plasma transferred arc (PTA) coating process. The results showed that the major phases present in the coating were TiC, Al2O3, Y2C3, Y2Al, TiCo3 and Co2Ti. The coatings had a sound metallurgical bonding to AZ91 Mg alloy substrate. The maximum average surface hardness of TiC/Co/Y2O3 composite coated layer was found to be around 3374 HV0.05, which is about 49 times higher than that of AZ91D Mg alloy (68 HV0.05). The wear rate of the coatings was 8.48 × 10-8 g/N-m, which was reduced about seven times as compared to AZ91D Mg (58 × 10-8 g/N-m). It was concluded that the wear resistance of TiC/Co/Y2O3 composite coating was enhanced as compare to the AZ91D Mg alloy. This type of TiC/Co/Y2O3 coating may increase the application of AZ91D Mg alloy in the automotive industries for manufacturing of tribological components.

Fitness and Hard Seededness of F2 and F3 Descendants of Hybridization between Herbicide-Resistant Glycine max and G. soja.

The commercial cultivation of herbicide-resistant (HR) transgenic soybeans (Glycine max L. Merr.) raises great concern that transgenes may introgress into wild soybeans (Glycine soja Sieb. et Zucc.) via pollen-mediated gene flow, which could increase the ecological risks of transgenic weed populations and threaten the genetic diversity of wild soybean. To assess the fitness of hybrids derived from transgenic HR soybean and wild soybean, the F2 and F3 descendants of crosses of the HR soybean line T14R1251-70 and two wild soybeans (LNTL and JLBC, which were collected from LiaoNing TieLing and JiLin BaiCheng, respectively), were planted along with their parents in wasteland or farmland soil, with or without weed competition. The fitness of F2 and F3 was significantly increased compared to the wild soybeans under all test conditions, and they also showed a greater competitive ability against weeds. Seeds produced by F2 and F3 were superficially similar to wild soybeans in having a hard seed coat; however, closer morphological examination revealed that the hard-seededness was lower due to the seed coat structure, specifically the presence of thicker hourglass cells in seed coat layers and lower Ca content in palisade epidermis. Hybrid descendants containing the cp4-epsps HR allele were able to complete their life cycle and produce a large number of seeds in the test conditions, which suggests that they would be able to survive in the soil beyond a single growing season, germinate, and grow under suitable conditions. Our findings indicate that the hybrid descendants of HR soybean and wild soybean may pose potential ecological risks in regions of soybean cultivation where wild soybean occurs.

Crosstalk Reduction in High-Density Radio Frequency Printed Circuit Boards: Leveraging FR4 Coating Layers

The escalating component density in radio frequency (RF) systems presents a growing challenge related to the coupling of adjacent microstrip lines in high-density printed circuit boards (PCBs). As a result, to tackle this prominent issue, there is a continuous pursuit of innovative techniques to effectively minimize the coupling effects among closely spaced microstrip lines. This paper proposes a reduction in the coupling of adjacent lines by utilizing a coating (stiffener) layer, which is commonly used in rigid-flex PCB fabrication. For this purpose, a reference 50 Ohm coupled line performance was compared to three coupled lines with track widths of 1.39 mm, 1.30 mm, and 1.25 mm, respectively, all at a fixed distance between the tracks. These decreasing widths were used to achieve the same 50 Ohm impedance for the coupled lines when covered with different coating layers. Each of these three coupled lines was covered with different coating (stiffener) layers, measuring 0.1 mm, 0.3 mm, and 0.5 mm in thickness, respectively. The manufactured device under test (DUT) structures underwent time-domain reflectometry (TDR) and S-parameter measurements. The TDR measurements of the DUT structures with coating layers demonstrated excellent conformity to the 50 Ohm reference coupled line. Meanwhile, the S21 measurements indicated a significant decrease in the crosstalk. For example, for a coating layer thickness of 0.3 mm, the crosstalk decreased by approximately 5–6 dB within the frequency range up to 5 GHz. When the coating layer thickness was 0.5 mm, the crosstalk decreased by approximately 10 dB or more.

Structure and Properties of Multilayer Nanocomposite Coatings of Polyvinyl Alcohol with Aluminum Oxide Nanoparticles

The nanocomposite polymer – inorganic materials formation, the study of their morphology and mechanical properties at the nanolevel is acute in the development of new materials for various functional purposes, including medical ones. As a result of the research the technique for producing singleand multilayer films of polyvinyl alcohol and composite polymer coatings with aluminum oxide nanoparticles by the spin coating method has been developed. It is shown that the optimal mass content of aluminum oxide nanoparticles in suspension for the formation of uniform composite coatings is 0.625 %. Based on experimental data on the structuralmorphological and mechanical properties of the formed coatings obtained by atomic force microscopy, it has been found that an increase in the number of layers of composite coatings leads to an increase in the number of conglomerates which, in turn, increases the surface roughness of the films. The modulus of elasticity of single-layer films of polyvinyl alcohol is (509.5 ± 10 %) MPa. In the case of composite coatings with aluminum oxide nanoparticles, changes in the elastic modulus have been established for multilayer coatings: an increase to 559.0 MPa (5 layers) and a decrease to 415.2 MPa (10 layers). The modulus of elasticity of the investigated single-layer coatings is significantly reduced in the range of 20−40 ºС. The smallest values after exposure to temperatures have been determined for films with nanoparticles (236.2 ± 10 %) MPa. Nanocomposites demonstrate an increase in the contact angle with an increase in the number of layers of composite coatings up to 20. A subsequent increase in the thickness of the coatings (the number of layers) leads to an increase in the hydrophilicity of the nanocomposites. The developed compositions of nanocomposite films are promising as sorption coatings.