Adhesion Characteristics Research Articles

Self-Assembly of Hemimyzon Formosanus-Inspired Crescent-Shaped Nanosucker Arrays for Reversible Adhesion.

Hemimyzon formosanus, a species of ray-finned fish, makes use of crescent-shaped abdominal suckers for adhering to irregular, rough, and slippery gravel in fast-flowing headwaters and minor tributaries. Bioinspired by the adhesion characteristics, two-dimensional non-close-packed colloidal crystals are self-assembled and serve as templates to pattern crescent-shaped shape memory polymer-based nanostructure arrays. By the manipulation of the configuration of nanosuckers through applying common solvent stimulations, the corresponding adhesion performances on glass, sandpaper, or even porcine kidney surfaces can be switched instantaneously and reversibly under ambient conditions. The biomimetic nanostructures indicate possible solutions to a variety of challenges, such as wound nursing, and so on.

Exploring fatigue characteristics of metallic boss-polymer liner adhesion in hydrogen storage tanks: Experimental insights post surface treatment

Progress in hydrogen fuel powered systems has been propelled by the implementation of secure, reliable, and cost-effective hydrogen storage and transportation technologies. The fourth category, distinguished by a polymer liner serving as a hydrogen diffusion barrier, fully encapsulated within a fiber-reinforced composite to bestow structural integrity, has garnered substantial attention from the automotive industry due to its lightweight nature and rational manufacturing process. The method of rotomolding has sparked interest among manufacturers due to its capability to directly bond the metallic component to the polymer substrate, specifically the liner, thus negating the need for welding and its attendant imperfections. In fact, a pivotal facet of fourth-generation hydrogen storage systems revolves around the interface connection between the polymer liner and the metallic boss, posing as a structural Achilles' heel. For the study's purposes, a scaled-down demonstrator was fabricated using rotomolding in which a nozzle-liner interface mimics the boss-liner interface of the actual system. This demonstrator was designed to facilitate the mechanical characterization of the interface under quasi-static and fatigue loading. The thermal cycling phases of rotational molding and the surface treatments undertaken have been optimized in order to enhance direct adhesion within the metal-polymer interface. This study commences by assessing the efficacy of two treatments (sandblasting and flaming) applied to the aluminum nozzle surface. Subsequently, we explore the adhesion microstructural and mechanical characteristics of the treated nozzle onto a medium-density polyethylene polymer (liner). Lastly, we delve into an exploration of the damage and fatigue behaviors endemic to the metal-polymer interface region. The obtained Wöhler curves disclose a linear trend for the metal-polymer interface. Moreover, the metal-polymer interface evinces heightened resilience against damage and fracture for sandblasted interfaces. This inquiry underscores the potency of innovative polymer-metal interfaces treatment in amplifying the reliability and robustness of hydrogen storage technology.

Comparison of quantitative and qualitative characteristics of the system “P-selectin — platelets — von Willebrand factor — metalloprotease ADAMTS13” in patients with sepsis, idiopathic thrombocytopenic purpura and healthy individuals

Introduction. The blood coagulation system plays a significant role in the pathogenesis of sepsis. Aim: to evaluate changes in the quantitative and qualitative characteristics of von Willebrand factor (vWF), ADAMTS13 metalloprotease and P-selectin in patients with sepsis, comparing them with those in patients with idiopathic thrombocytopenic purpura and in healthy individuals. Materials and methods. The study included 56 patients who received inpatient treatment due to the development of sepsis of various etiologies, 12 patients with idiopathic thrombocytopenic purpura (ITP) and 50 healthy volunteers. In a venous blood sample, the following studies were performed: vWF antigen (vWF:Ag), GPIb-binding ability of vWF (vWF:GPIb), binding ability of vWF to type I collagen (vWF:CBAI), binding ability of vWF to type III collagen I (vWF:CBAIII), P-selectin, ADAMTS13 antigen (ADAMTS13:Ag), ADAMTS13 activity (ADAMTS13:AC) and antibodies to ADAMTS13 (ADAMTS13:AB). Results. The median values of vWF:Ag, vWF:GPIb, vWF:CBAI, and vWF:CBAIII were significantly higher in patients with sepsis compared to healthy individuals and patients with ITP. The median P-selectin in patients with sepsis with thrombocytopenia 1213 ng/mL [1104–1302] was statistically significantly higher than in healthy individuals 74.5 ng/mL [65.0–84.5] (p = 0.0001), and with patients with ITP 389.0 ng/ml [276.2–589.2] (p = 0.0001). Median ADAMTS13:Ag in patients with sepsis with thrombocytopenia < 100×109/l 0.49 U/ml [0.44–0.71] and in patients with ITP 0.67 U/ml [0.62–0.76] were significantly lower compared with healthy individuals 0.97 U/ml [0.84–1.08] (p = 0.001 and p = 0.034, respectively), but the median ADAMTS13:Ag in patients with sepsis with thrombocytopenia was statistically significantly lower than in patients with ITP (p = 0.038). In 19.6 % of cases in patients with sepsis, the ADAMTS13:AB index was higher than 10.0 U/ml (19.6 U/ml [12.1–26.7]), while the median P-selectin indicator in this group of patients was significantly higher when compared with a group of patients with sepsis with an ADAMTS13:AB score of less than 10.00 U/mL (3.04 [2.11–3.94]): 1342 ng/mL[1271–1374] vs. 1130 ng/mL [1087–1271], p = 0.003, respectively. Conclusion. Activation of endothelial cells may underlie the increase in quantitative and qualitative indicators of vWF. Meanwhile, the effect of the adhesive characteristics of vWF (vWF:GPIb, vWF:CBAI and vWF:CBAIII) on the number of platelets in the blood of patients with sepsis was not revealed. Adhesion of vWF to the endothelium through interaction with P-selectin through the platelet GPIb receptor can promote the transition of vWF into a conformational-active state and lead to a decrease in the concentration of ADAMTS13 in the circulation.

Investigation on dynamic adhesion characteristics and evolution mechanism of charged particles

Understanding the dynamic characteristics and evolution mechanism of charged particles adhered to the wall is of great significance for strengthening production safety and reducing the risk of explosion caused by adhesion. In this study, experiments and simulations are combined to explore the adhesion characteristics of charged particles and reveal the adhesion mechanism. According to the charge-to-mass ratio and particle size distribution of the adhered particles in the experiment and simulation, the dynamic adhesion characteristics of the adhered particles are explored to verify the accuracy of the simulation model. The evolutionary pattern of adhered particles is obtained by exploring the charge characteristics and size distributions of particles. The forces acting on the adhered particles are analyzed to reveal the adhesion mechanism of the particles. Furthermore, the probability of adhered particles with different particle charge and size is studied and the criterion of particle adhesion is proposed.

A sequential sustained-release hydrogel with potent antimicrobial, anti-inflammatory, and osteogenesis-promoting properties for the treatment of periodontitis

Periodontitis is a pathological disorder characterized by inflammation and tissue destruction; it is primarily attributed to bacterial infection and immune responses. Nevertheless, existing strategies for drug delivery in periodontal treatment are insufficient to accommodate the intricate anatomical morphology of the periodontium and the complex oral environment. Furthermore, the disordered release of antibacterial agents and bone-promoting substances are not conducive to the natural healing of periodontal tissues, thus resulting in suboptimal therapeutic outcomes for periodontitis. In this study, we successfully co-loaded methylene blue (MB) and poly(lactic-co-glycolic acid) microspheres encapsulating Sema3A into a dopamine-grafted sodium alginate hydrogel (SA-DA). Experimental evidence indicates that MB/Sema3A@SA-DA exhibits favorable injectability, adhesion, and compression resistance characteristics, thus allowing it to adapt to the intricate therapeutic conditions of the oral cavity. The prompt release of MB (within 14 h) demonstrates its high antibacterial efficacy against periodontal pathogens upon exposure to 660 nm light, thereby establishing a microenvironment conducive to osteogenesis devoid of bacterial interference. Furthermore, the protracted release of Sema3A (within 28 d) shows noteworthy osteogenic capabilities and facilitates the polarization of macrophages toward the M2 phenotype. In a rat model of periodontitis, MB/Sema3A@SA-DA can be perfectly applied in situ to local periodontal lesions, and the sequential release of MB and Sema3A effectively achieved antibacterial, anti-inflammatory, and osteogenic effects. This therapeutic system avoids the abuse of antibiotics, surgical trauma, and repetitive administration. Hence, MB/Sema3A@SA-DA emerges as a safe, effective, minimally invasive, comfortable, and cost-effective treatment strategy with considerable potential for clinical implementation in periodontitis management.

Fewer polymer chains but higher adhesion: How gradient-stiffness hydrogel layers mediate adhesion through network stretch.

The presence of gradient softer outer layers, commonly observed in biological systems (such as cartilage and ocular tissues), as well as synthetic crosslinked hydrogels, profoundly influences their interactions with opposing surfaces. Our prior research demonstrated that gradient-stiffness hydrogel layers, characterized by increasing elasticity with depth, control contact mechanics, particularly in proximity to the layer thickness. We postulate that the distribution of polymers within these gradient layers imparts extraordinary stretch and adhesion characteristics due to network adaptability and stress-induced reorganization. To investigate this phenomenon, we utilized Atomic Force Microscopy nanoindentation to assess the depth-dependent adhesion behavior of polyacrylamide hydrogels with varying gradient layer thicknesses. Two gradient layer thicknesses were achieved by employing different molding materials: glass and polyoxymethylene (POM). Glass-molded hydrogels exhibited a thinner gradient layer alongside a stiffer bulk layer compared to their POM-molded counterparts. In indentation experiments, the POM-molded hydrogel had larger adhesion compared to glass-molded hydrogel. We find that indenting within the gradient layer engenders increased load-unload hysteresis due to heightened fluid transport in the sparse outer polymer network. Consequently, this led to augmented adhesion and work of separation at shallow depths. We suggest that the prominent stretching capability of the sparse outer polymer network during probe retraction contributes to enhanced adhesion. The Maugis-Dugdale adhesive model only fits well to indentations on the thin layer or indentations which engage significantly with the bulk. These results facilitate a comprehensive characterization of adhesion mechanics in gradient-stiffness hydrogels, which could foster their application across emerging contexts in health science and environmental domains.

Performance characteristics of REBCO coated conductor joints fabricated by flux-free hybrid welding

Recently, the joining of rare-earth barium copper oxide coated conductor (CC) tapes using ultrasonic welding (UW) has demonstrated outstanding potential in the in-line fabrication of longer tapes required for superconducting device applications. The UW method can produce CC joints by applying ultrasonic vibration in less than one second, and hybrid welding (HW) has been adopted to improve further the joint resistance (R j) and electromechanical properties of the UW CC joints. However, conventional methods for preparing the HW and soldered CC joints involve applying solder flux to remove the oxide film, which can cause corrosion to the surface of the CC tapes and affect the joint’s lifespan during device operation. Therefore, this study aims to fabricate a robust HW CC joint of pre-solder insertion without solder flux and compare its joint strength and electromechanical properties with the traditional cases with the solder flux. While similar R j can be obtained from both cases of HW CC joints, the flux-free HW CC joint has slightly higher joint strength and superior adhesive characteristics than those with flux. The difference in fracture mechanisms after lap-shear and T-peel tests between flux-free HW and with flux was extensively discussed. Additionally, the study investigates the correlation between a decrease in R j with longer joint length in differently stabilized and processed CC tapes for flux-free HW. Overall, this study demonstrated that the flux-free HW method could efficiently produce robust CC joints with a lesser risk of corrosion and enhanced joint characteristics.

The Relationship between Annealing Temperatures and Surface Roughness in Shaping the Physical Characteristics of Co40Fe40B10Dy10 Thin Films

Co40Fe40B10Dy10 thin films, with thicknesses varying between 10 nm and 50 nm, were grown on a Si(100) substrate. Subsequently, they underwent a 1 h annealing process in an Ar atmosphere at temperatures of 100 °C, 200 °C, and 300 °C. The oxide characteristic peaks of Dy2O3(440), Co2O3(422), and Co2O3(511) were revealed by X-ray diffraction (XRD). The low-frequency alternating current magnetic susceptibility (χac) decreases with frequency. Due to thickness and the anisotropy of the magnetic crystal, the maximum χac and saturation magnetization values rise with thicknesses and annealing temperatures. As the thickness and heat treatment temperature rise, the values for resistivity and sheet resistance tend to fall. The results of atomic force microscopy (AFM) and magnetic force microscopy (MFM) show that average roughness (Ra) lowers as the annealing temperature increases, and the distribution of strip-like magnetic domain becomes more visible. As thickness and annealing temperature increase, there is a corresponding rise in surface energy. Nano-indentation testing shows that hardness initially decreases from 10 nm to 40 nm, followed by an increase at 50 nm. Notably, annealing at 300 °C leads to a significant hardening effect, marking the highest level of hardness observed. Young’s modulus increased as thicknesses and annealing temperatures increased. The magnetic, electric, and adhesive characteristics of CoFeBDy films are highly dependent on surface roughness at various annealing temperatures.

Polyetherimide nanocomposites filled with in‐situ synthesised bismaleimide‐DDE@CCTO hybrid nanofibers enabling improved dielectric and interfacial performance

AbstractMost current research of nanocomposite dielectrics for modern electronic devices and electric equipment usually focuses more on dielectric properties while in some extent ignoring the interfacial adhesion characteristics. However, the poor interfacial adhesion frequently results in serious dielectric field distortion, which would in return impair the dielectric performance enhancement. As such, how to simultaneously achieve the excellent dielectric properties and interfacial adhesion performance in organic‐inorganic nanocomposite system is worth in‐depth investigation. To realise this aim, novel hybrid nanofibers are neatly fabricated using in situ copolymerisation reaction of bismaleimide and diamino‐diphenyl ether monomers on the CCTO nanofiller surface via covalent bond connections. The resulting nanocomposites achieve high dielectric constant (9.3) and low dielectric loss (0.0185) at 1 kHz. The BMI‐DDE@CCTO/PEI yields a high discharge energy density (3.09 J/cm3) at moderate electric field (200 MV/m). Noticeably, the nanocomposites enable stable dielectric performance over a wide temperature range from room temperature to 150°C. Moreover, the binding energy for BMI‐DDE and PEI is 1052 kJ/mol according to DFT calculation. As such, the authors speculate this interesting study would inspire the broad researchers devoting to investigating bismaleimide‐coated high‐aspect‐ratio nanofillers and their dielectric materials for collaboratively improved dielectric and interfacial performance.

WO3·H2O micro-flowers decorated PVDF/Ti3C2 MXene membrane for oily wastewater treatment

Purification of the complex wastewater mandates the fabrication of multi-functional membranes that can separate oil from emulsions and remove dangerous organic contaminants. Herein, we developed a new PVDF/Ti3C2/WO3·H2O fibrous membrane through the hydrothermal growth of WO3·H2O micro-flowers onto the porous PVDF/Ti3C2 electrospun mats. WO3·H2O micro-flowers showed similar growth spanning Ti3C2 MXene sheets having good interfacial contact, which regulated the wettability and enhanced the charge separation needed for boosting photo-reactivity. The fibrous PVDF/Ti3C2/WO3·H2O membrane displayed minimal oil adhesion, superhydrophilicity, and sustained underwater superoleophobic characteristics with outstanding separation effectiveness (∼99 %) and reusable nature. Notably, membrane had the ability to successfully separate a wide variety of oil/water emulsions with a permeation flux of 1431–1542 L.m- 2.h- 1. The composite membrane is 39 times more efficient than PVDF/Ti3C2 electrospun membrane with regard to RhB degradation (∼91 %) and has good recyclability and refreshing behaviour under LED light irradiation. Such bi-functional materials with outstanding oil/water emulsion separation and photocatalytic degradation properties pave the way for treating complex oily wastewater. The present study presents a scalable method for fabricating metal-oxide-based multi-functional membranes utilising 2D MXene.

Investigating meat-borne bacterial profiles related to biofilm formation: An in situ and in vitro assessment

Foodborne spoilage bacteria may pose a serious risk to food quality by forming biofilms that adhere to food processing devices and food surfaces, thus causing cross-contamination and deterioration of food products. In order to effectively control microbial contamination, understanding the bacterial profiles related to biofilm formation in situ is crucial. Pseudomonas, Aeromonas, and Serratia are typically considered as prevalent spoilage organisms in chilled meat, which is particularly susceptible to deterioration during storage and transportation. In this study, four strains (Serratia liquefaciens F5, Aeromonas salmonicida H8, Pseudomonas saponiphila G7, and Aeromonas veronii G8) were cultured in situ in chilled chicken claws as the experimental group and in Tryptic Soy Broth (TSB) as the control group. The results showed that tested strains differed in ability to adhere, with S. liquefaciens F5 significantly exhibiting the highest biofilm formation capacity (P < 0.05). Moreover, it was discovered that higher protein and polysaccharides concentrations enhanced bacterial auto-aggregation and that the protein content of extracellular polymeric substances (EPS) positively correlated with bacterial surface hydrophobicity. On the 4th day, the protein content in EPS of each strain was significantly higher in vitro than in situ (P < 0.05). Furthermore, the rate of increase in auto-aggregation capacity and surface hydrophobicity proved faster in vitro than in situ for each strain due to higher polysaccharides and protein contents. The primary components (proteins, polysaccharides) in the EPS of the four strains increased as the biofilm formation process progressed, further confirmed by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) spectra. Scanning electron microscopy revealed that A. salmonicida H8 can create biofilms on the surface of chicken claws, which severely disrupts the tissue structure of chilled meat. These observations will offer a theoretical foundation for a thorough investigation of the spoiling outcomes and adhesion characteristics of various meat-derived spoilage bacteria.

Design and Biomechanical Properties of Symmetrical Lumbar Fusion Cage Based on Lightweight Titanium Alloy Flexible Microporous Metal Rubber

In recent years, the incidence rate of lumbar diseases has been progressively increasing. The conventional lumbar fusion cages used in existing lumbar interbody fusion surgery are not able to take into account the multiple characteristics of cushioning, vibration reduction, support, cell adhesion, and bone tissue growth. Therefore, in this work, based on the CT data of a lumbar intervertebral disc plain scan, a combined symmetric lumbar fusion cage structure was innovatively designed. The core was made of lightweight TC4 medical titanium alloy flexible microporous metal rubber (LTA-FMP MR), and the outer frame was made of cobalt–chromium–molybdenum alloy. Its comprehensive biomechanical performance was comprehensively evaluated through finite element simulation, static and dynamic mechanics, and impact resistance tests. The three-dimensional model of the L3/L4 lumbar segment was established by reverse engineering, and a Mises stress analysis was conducted on the lumbar fusion cage by importing it into Ansys to understand its structural advantages compared to the traditional lumbar fusion cage. Through static experiments, the influence of the internal nucleus of a symmetrical lumbar fusion cage with different material parameters on its static performance was explored. At the same time, to further explore the superior characteristics of this symmetrical structure in complex human environments, a biomechanical test platform was established to analyze its biomechanical performance under sinusoidal excitation of different amplitudes and frequencies, as well as impact loads of different amplitudes and pulse widths. The results show that under different amplitudes and frequencies, the lumbar fusion cage with a symmetrical structure has a small loss factor, a high impact isolation coefficient, and a maximum energy consumption of 422.8 N·mm, with a maximum kinetic energy attenuation rate of 0.43. Compared to existing traditional lumbar fusion cages in clinical practice, it not only has sufficient stiffness, but also has good vibration damping, support, and impact resistance performance, and has a lower probability of postoperative settlement, which has broad application prospects.

Synthesis and Application of Modified Lignin Polyurea Binder for Manufacturing a Controlled-Release Potassium Fertilizer

Conventional potassium chloride granules have inefficient applications in agricultural production due to particle irregularity and low fluidity. The application of controlled-release potassium chloride could increase the potassium-use efficiency and alleviate the shortage of potassium ore resources. In this study, a well-rounded potassium chloride fertilizer core was prepared, using the graft modification of polyurea to enhance the coating rate and release performance. The adhesive and tensile characteristics of the modified polyurea binder, as well as the granule properties of modified polyurea binder potassium chloride, were studied to determine the ideal lignin-grafted ratio. The effect of the modified polyurea binder with potassium chloride on the properties of coated fertilizer was investigated. The findings, shown by radar maps of the binder’s properties, demonstrated that the ideal mass ratio of the modified lignin polyurea binder to urea is 1:2. The Fourier-transform infrared spectroscopy results demonstrated that the amino functional groups of lignin were enhanced, improving the product’s interfacial compatibility with the polyurea matrix. Compared to humic acid (HA; 12%) and bentonite (Ben; 30%) treatments, the granule intensity of the 9.9%—1:2 treatment considerably increased by 139.10% and 38.86%, respectively, while the static angle of the granules reduced by 16.67% and 3.81%. The 28-day cumulative release rate of the modified polyurea (9.9%—2:1) with a 5% coating thickness was the lowest (28%), 42% lower than that of the lowest conventional treatment. In summary, the creation of a bio-lignin polyurea binder under the optimum conditions reduced the need for petrochemical-based materials, allowed the preparation of fertilizer with granules of increased fluidity, and enabled the successful coating of a high-salt potassium fertilizer, offering a novel technique for the high-value application of potash fertilizer coating.

Development of shape memory alloy fiber reinforced debondable adhesive

This study introduces an innovative debondable adhesive approach by incorporating shape-memory alloy (SMA) fibers within an epoxy adhesive matrix. Employing meticulous techniques, such as winding machinery and other apparatuses, exceedingly thin Nitinol SMA fibers have been successfully integrated into the adhesive layer. Notably, this adhesive exhibits the dual functionality of a fiber-reinforced composite at operational temperatures, conferring heightened joint strength. Upon disassembly at elevated temperatures, the shape-memory effect of the fibers induces stress concentration within the adhesive layer, thereby facilitating effortless debonding and significantly enhancing the recycling efficacy.Various configurations of fiber volume fractions (2.5 %, 5.0 %, 10.0 %) and orientations (0°/0°, 0°/90°, 90°/90°) were explored to assess their impact on joint strength across ambient and elevated temperatures. The investigation reveals that the 0°/0° fiber orientation yields optimal debondable adhesive characteristics. Additionally, higher volumetric percentages generally correlate with improved adhesive strength and debonding capability. This study further elucidates the underlying mechanisms governing the observed effects on joint debonding strength.

Atomistic insights into adhesion characteristics of tungsten on titanium nitride using steered molecular dynamics with machine learning interatomic potential

As transistor integration accelerates and miniaturization progresses, improving the interfacial adhesion characteristics of complex metal interconnect has become a major issue in ensuring semiconductor device reliability. Therefore, it is becoming increasingly important to interpret the adhesive properties of metal interconnects at the atomic level, predict their adhesive strength and failure mode, and develop computational methods that can be universally applied regardless of interface properties. In this study, we propose a method for theoretically understanding adhesion characteristics through steering molecular dynamics simulations based on machine learning interatomic potentials. We utilized this method to investigate the adhesion characteristics of tungsten deposited on titanium nitride barrier metal (W/TiN) as a representative metal interconnect structure in devices. Pulling tests that pull two materials apart and sliding tests that pull them against each other in a shear direction were implemented to investigate the failure mode and adhesive strength depending on TiN facet orientation. We found that the W/TiN interface showed an adhesive failure where they separate from each other when tested with pulling force on Ti-rich (111) or (001) facets while cohesive failures occurred where W itself was destroyed on N-rich (111) facet. The adhesion strength was defined as the maximum force causing failure during the pulling test for consistent interpretation and the strengths of tungsten were predicted to be strongest when deposited onto N-rich (111) facet while weakest on Ti-rich (111) facet.

Friction and wear characteristics of β‐Sialon prepared from secondary aluminum dross

AbstractThis study investigates the properties of β‐Sialon synthesized from secondary aluminum dross. High‐purity β‐Sialon powders were synthesized through nitriding reduction, followed by spark plasma sintering to obtain dense sintered bodies. The phase composition, microstructure, microhardness, and friction and wear characteristics of the sintered bodies were analyzed using X‐ray diffractometry, scanning electron microscopy, a microhardness tester, and a friction and wear tester, respectively. Fracture analysis revealed a combination of through‐crystal and along‐crystal fractures, with fracture occurrence correlated to crack expansion. The crystalline fractures exhibited a toughening effect. The friction and wear test of the sintered bodies demonstrated a decrease in the friction coefficient with increasing load and speed. The wear behavior of the sintered bodies encompassed abrasive wear, adhesive wear, and fatigue wear. Abrasive wear dominated at low speed and low load, while adhesive wear was prominent at high speed and high load. Increasing speed accentuated adhesive wear characteristics, while increasing load led to the formation of a material layer on the friction ball surface, delaying wear initiation.

Adhesion and tribological characteristics of modified polyurethane coating on composite substrate

ABSTRACT In the present study, glass-epoxy composites were used as a substrate to study the performance of modified polyurethane coating. Two-layer coating (180–200 µm) wherein the epoxy primer as the first coat and polyurethane as the top coat was applied using an air-assisted spray gun to increase the service life of the composite. The analysis of coating was performed using gloss, contact angle, FTIR, TGA, tensile test and SEM. The bonding strength between coating and substrate was evaluated by cross-hatch cut, 180 deg peel strength and pull-off adhesion tests. Scratch, Taber abrasion and Pin-on-disc tests were also performed to evaluate the wear resistance. In addition, a rain erosion test was performed to check the stability of the coating. From the above tests, it is concluded that the applied coating well adhered to the composite substrate. The data generated from different tests can be used to estimate the service life of polymer composites and coatings.

An injectable carboxymethyl chitosan hydrogel scaffold formed via coordination bond for antibacterial and osteogenesis in osteomyelitis

The intricate, hostile, and diverse nature of osteomyelitis (OM) poses a challenge for complete bacterial eradication and osteogenesis promotion via conventional treatment. Recently, functional hydrogels exhibiting antibacterial and osteogenic properties emerge as a promising avenue for OM wound healing in clinical practice. However, the preparation procedures and associated costs on cytokine and cell therapies for certain functional hydrogels can be complex and prohibitively expensive. In our research, a hybrid hydrogel dressing has been formulated utilizing carboxymethyl chitosan (CMCS) as the base material, and designed with inherent antibacterial, adhesion, proliferation, and differentiation characteristics, showing promise as a candidate for eradicating infection and promoting bone regeneration. The hybrid hydrogel is composed of interconnected networks of Fe3+-induced self-assembled CMCS and the antibacterial drug ciprofloxacin (CIP), resulting in excellent injectability and moldability. Notably, the CMCS/Fe3+/CIP hybrid hydrogel is capable of regulating antibacterial responses and stimulating osteogenesis in infected microenvironments without additional additives. This injectable antibacterial and osteogenic-promoting hydrogel establish a high-potential platform for low-cost, safe and effective treatment of OM by expediting the initial stages of infected bone wound repair.

Effects of Short-Term Exposure of Chloramine-T Solution on the Characteristics of Light-Cured and Chemical-Cured Adhesives.

This study evaluated the effect of a 0.5% chloramine T solution on a chemical-cured universal adhesive by comparing the light-cured, one-step, self-etch adhesive for the bonding performance, mechanical properties, and resin-dentin interfacial characteristics. Caries-free human molars were randomly assigned into eight groups based on the bonding systems employed (Bond Force II, BF and Bondmer Lightless, BL), the immersion solutions used before bonding (0.5% chloramine T solution and distilled water), and the immersion durations (5 and 60 min). Microtensile bond strength (μTBS), nanoleakage evaluation, and nanoindentation tests were performed, and the surface morphology of the resin-dentin interface was examined using a focus ion beam/scanning ion microscopy system. Immersion in chloramine-T for 5 min significantly decreased the μTBS of Bondmer Lightless (from 22.62 to 12.87 MPa) compared with that in distilled water. Moreover, there was also a decreasing trend after immersing in chloramine-T for 60 min (from 19.11 to 13.93 MPa). Chloramine T was found to have no effect on the hardness, elastic modulus, or morphological characteristics of the ion-beam milled resin-dentin interfacial surfaces in the tested adhesives, suggesting that chloramine T might reduce the bond strength by interfering with the interaction and the sealing between the adhesive resin and dentin in the chemical-cured universal adhesive, albeit without affecting the mechanical properties.

Adhesive characteristics of novel greener engineered cementitious composite with conventional concrete substrate

Engineered cementitious composite (ECC) is a high-graded advanced construction material that can be used to strengthen and repair structural composites owing to its high mechanical and durability properties. Nevertheless, the ability of ECC to strengthen and repair concrete surfaces depends on the interfacial bond between the conventional concrete (CC) substrate texture and ECC overlay. It ensures sufficient adhesive or bonding ability over a lifetime under various loading and environmental conditions. The present study investigates the bond strength between CC substrate and modified ECC with agro-industrial by-products, such as ground granulated blast furnace slag (GGBS), bagasse ash (BA), and rice husk ash (RHA). The bond strength is determined using three types of tests, namely the slant shear, split cylinder, and split prism tests. A mathematical model has also been developed to predict the bond strength of the different ECC mixtures. The results indicate that incorporating 40% GGBS, 10% BA, and 10% RHA in ECC helps in attaining the maximum interfacial bond strength with cross-hatched textures under all types of testing. According to the ACI standard, ECC with agro-industrial by-products ranging from 10% to 55% achieved the required bond strength in all three tests. Correspondingly, the outcomes of the present research are compared with those obtained from previous studies to gain further insights into various applications, which are highly relatable. Furthermore, the experimental outcomes were strongly correlated with the mathematical modeling with great accuracy.