Increase In Roughness Research Articles

Degradation and ultrastructural changes of resin-based pit and fissure sealants under simulated chewing conditions

BackgroundResin-based pit and fissure sealants, used to prevent dental caries, can experience abrasive wear. This study aimed to assess the abrasive wear of experimental pit and fissure sealants (DIF) compared with the other commercial pit and fissure sealants by measuring surface roughness, volume loss, and ultrastructure after chewing simulation at different time points.MethodsSpecimens were divided into five groups (n = 10): Clinpro™(CP), Teethmate™ White (TW), Teethmate™ Natural (TN), experimental sealant (DIF), and Filtek™ Supreme Flowable Restorative (FC). They underwent chewing simulation with 120,000, 240,000, and 360,000 strokes. Surface roughness and volume loss were measured with a profilometer, and ultrastructures were assessed using scanning electron microscope (SEM).ResultsAll specimens showed a significant increase in surface roughness after chewing simulation. FC had the highest roughness (p < 0.001) whereas DIF did not differ from other groups (p > 0.05). All materials experienced significant volume loss. Sealant types and chewing cycles affected volume loss, with CP showing the highest and TW the lowest (p < 0.001). SEM analysis revealed worn areas with circular or oval shapes, with CP and TN having larger diameters and TW the smallest.ConclusionsDIF showed acceptable surface roughness and wear resistance compared to other commercial products after chewing simulation.

Surface Modification of Additively Manufactured Ti6Al4V through In-Situ Nitrogen-Assisted Laser Surface Remelting

Abstract Laser surface remelting is a widely used method for surface modification of titanium and related alloys, particularly to enhance its workability in the biomedical industry through surface nitriding. The present work aims to develop the nitride surface over the LPBF-processed Ti6Al4V substrate by introducing the nitrogen environment in the build chamber during the remelting. The effects of different laser power and laser scan speeds were studied over the surface topography and elemental changes of the remelted surface. The result shows an increase in surface roughness with selective laser remelting, which could enhance cell proliferation or osseointegration, which is advantageous for biomedical applications.EDX results show a significant increase in nitrogen content in terms of weight percentage for the in-situ remelted surface. XRD phase analysis shows the presence of titanium(Ti) and aluminium(Al) nitride peaks, and X-ray Photon-electron Spectrometry (XPS) also indicates the formation of nitrogen bonds with Ti and Al, which were initially missing in the substrate. The results reported here confirm the nitride surface formation over the substrate due to the in-situ remelting under the nitrogen environment for the LPBF-processed Ti6Al4V, which could be used for improved biomedical applications.

Interfacial bond properties between polypropylene fiber mortar and rock with different roughness

Abstract Abstract: Effective reinforcement measures for the surrounding rock of the tunnel are crucial to ensure the safety of tunnel engineering. Fibers are very effective in improving the quality of the interface; however, to promote the application of fiber mortar (FM) in tunnel lining reinforcement, it is necessary to study the bonding performance between FM and rock. The mechanical properties of ordinary mortar (OM) and FM were investigated, and bonding performance tests were conducted. The effect of polypropylene (PP) fibers on the mechanical properties and the influence of PP fibers and surface with different roughness on the bond properties were analyzed in detail. A 3D printer was used to print various structural boards to characterize different roughness levels, and the shape of the printed model was effectively controlled, thereby ensuring the consistency and repeatability of the structural board. The test results indicated that the splitting tensile strength and volumetric strain of the mortar were improved significantly with the addition of PP fibers, in which the splitting tensile strength increased by 38%, the elastic modulus and Poisson’s ratio increased, and the deformation and energy absorption capacity were enhanced; however, there was little effect on its compressive strength. The bonding performance between mortar and rock surface were enhanced with the increase in roughness, and the direct shear strength recorded the highest value while the bond specimens with a surface roughness of joint roughness coefficient 18-20, also the PP fibers improved the bond properties. This study will be helpful for promoting the application of fiber mortar in tunnel surface lining engineering.

Effect of Multifunction Cavitation Treatment on Helical Gear Surface

Abstract This study proposes using multifunction cavitation (MFC) to strengthen the surface of helical gears used in transmissions. In addition, because the steel used for helical gears exhibits poor corrosion resistance in water, samples plated with electroless nickel and iron tetroxide were also investigated. In addition to using samples with modified surfaces, we used samples strengthened by carburizing and nitriding. The noncoated and plated samples showed a slight increase in surface roughness and increased compressive residual stress and hardness. The plating method that did not cause red rust during the MFC treatment was iron tetroxide plating. In the samples strengthened by carburizing and nitriding, red rust did not occur on the surface after MFC treatment, the surface roughness was suppressed, and compressive residual stress and hardness increased. The results show that the MFC treatment effectively improved the fatigue properties of gear surfaces with complex shapes.

Experimental Study on the Behavior of Gas–Water Two-Phase Fluid Flow Through Rock Fractures Under Different Confining Pressures and Shear Displacements

Understanding the flow behaviors of two-phase fluids in rock mass fractures holds significant importance for the exploitation of oil and gas resources. This paper takes rock fractures with different surface roughness characteristics as its research object and conducts experiments on the gas–water seepage laws of fractures under various confining pressures and shear displacements. The results indicate that the higher the fracture surface roughness, the larger the equivalent fracture width and the higher the single-phase permeability of gas/water in the fractures. During gas–water two-phase flow, when the water phase split flow rate is high, the influence of the confining pressure and fracture surface morphology on the water phase is significantly higher than that on the gas phase. The relative permeability at the isosmotic point of the fractures increases with the increase in confining pressure and decreases with the increase in roughness. After the dislocation of shale fractures, the interphase resistance within the fractures reduces. The relative permeability of the water phase increases more significantly compared to that of the gas phase. The water phase split flow rate at the isosmotic point does not change significantly, and the relative permeability at the isosmotic point increases. This research is helpful for guiding the protection based on the conductivity capacity of the rock mass fracture network.

Research on Laser Cleaning of Graphite Lubrication Coating on the Magnesium Alloy Surface

The lubricating coating must be removed from the forged or stamped workpieces. Developing environment-friendly and high-precision cleaning technology is necessary. In this study, a nanosecond pulsed laser was used to clean the graphite lubricating coating of 15 μm thickness on the surface of an MB15 magnesium alloy. The effects of various laser cleaning parameters on the cleaning quality and the cleaning mechanism were studied. When the laser fluence (F) increases from 1.27 to 7.64 J/cm2, the clearance rate increases, and the surface roughness initially decreases before increasing. When the pulse frequency (f) increases from 10 to 30 kHz, the single-pulse energy decreases, the clearance rate decreases, and the surface roughness increases. When the scanning speed (v) increases from 1000 to 5000 mm/s, the spot overlap rate decreases, the clearance rate decreases, and the surface roughness firstly decreases and then increases. The optimal cleaning parameter combinations are F = 3.82 J/cm2, f = 10 kHz, and v = 3000 mm/s. The graphite lubrication coating was almost completely removed without damaging the substrate surface, and the surface carbon content of the sample was decreased to 6.42%. The laser cleaning mechanism of the graphite lubricating coating on the magnesium alloy surface is dominated by thermal ablation. As the laser fluence increases, the physical and chemical reactions become more violent.

Potential Degradation of Low- and High-Density Polyethylene Films by Ochrobactrum intermedium SA1 from Sewage Sludge.

Accumulation of plastic waste is an alarming environmental concern across globe. For which, microbial degradation offers an efficient ecofriendly solution. Thus, the present study focuses on the exploration of new bacterium that can grow on and utilize polyethylene. Ochrobactrum intermedium SA1 isolated from sewage sludge (Jaipur, India) was characterized and evaluated for growth on both thermally pre-treated and untreated low-density polyethylene (LDPE) and high-density polyethylene (HDPE) films in synthetic medium at 35°C and pH 6.5 for 30 days. The bacterium was grown successfully on the polyethylene films such that 3.458 ± 0.373% and 1.586 ± 0.142% gravimetric weight loss was observed for LDPE and HDPE films, respectively. Further, LDPE and HDPE films showed highest decrease in tensile strength of 126.67% and 75.62%, respectively which was corelated with atomic force microscopy analysis depicting the increase in surface roughness after incubation with the bacterial isolate. Therefore, we believe that more detailed studies will establish Ochrobactrum intermedium SA1 as a potential tool in clearing the global burden of plastics.

Fretting wear modeling of bolted joint interface with microscopic roughness using the 1D microslip friction model and equivalent thin layer

In this work, an improved 1D microslip model at the frictional joint interface considering the effect of surface topography is developed, which is further used to evaluate the fretting wear performance of the joint structure. The rough surface contact of the joint interface is characterized by the micro-asperity Greenwood and Williamson statistical contact model (GW model). A thin layer with elastic tangential stiffness, exhibiting equivalent properties to accord with the micro-asperity contact of the rough interface, is supposed to connect with the two components comprising the joint interface. The nonuniform clamping pressure distribution is considered and the resulted stick-slip transitions along the interface are derived using the continuum elastic beam model. The tangential stiffness of micro-asperities for rough surface contact is derived and incorporated into the continuum beam model to obtain the relative slip displacement along the interface. Fretting wear depth resulted from the cyclic microslip at the interface is evaluated based on the relative sliding distance and the Archard wear model. Results show that the minimum tangential force causing microslip motion increases with surface roughness and preload. The slip length increases with the tangential force whilst decreases with the increased surface roughness. The wear depth progressively increases from stuck region to slip region, and decreases as the surface roughness and preload increase. Experimental validation is performed and excellent agreement is observed between model predictions and experimental results. The developed model provides important new insights into the prediction of fretting wear and loosening behavior of the bolted joints.

Comparative Analysis Between Strip and Gels Indicated for at Home Bleaching: Analysis of Color Alteration, Roughness and Microhardness of Dental Enamel.

To compare the color alteration, surface roughness and microhardness and cross-sectional microhardness of bovine enamel treated with at-home whitening strips and gels. Sixty-six pigmented specimens (n = 11) were allocated to six groups: C-cotton wool moistened with distilled water for 1 h; SDS-sodium dithionite strip, for 1 h; HPS-6.5% hydrogen peroxide strip, for 1 h; CPS-20% carbamide peroxide strip, for 1 h; HPG-7.5% hydrogen peroxide gel, for 1 h; CPG-10% carbamide peroxide gel, for 4 h. The treatments lasted 10 days, calculating the ∆E, ∆E00, and ∆WID at baseline, 5 and 10 days, and 14 days after completion. Additional 66 polished discs (n = 11) were used to analyze the surface roughness and microhardness of enamel before and after bleaching, cross-sectional microhardness and integrated mineral loss (ΔZ; %Vol × μm). Data were subjected to statistical analysis by two-way Anova RM and Tukey post-test (α = 0.05). In ∆E and ∆WID analysis, greater values were obtained in CPG (p < 0.001), followed by HPG and HPS (p = 0.271). SDS and CPS (p < 0.001) exceeded only C (p < 0.001). In ∆E00, at completion of treatments, the results were similar; however, HPG = HPS = CPS (p = 0.237). There was an increase in roughness and decrease in surface microhardness in all bleaching groups (p < 0.005). Concerning the cross-sectional microhardness, the treatments were equal to C at 150 μm, the last depth analyzed. For ΔZ, the values of SDS, CPS, HPG, and CPG groups showed similar mineral loss (p > 0.001), and the lowest value was exhibited in the Control group, followed by HPS group (p < 0.001). Although the strips were aesthetically effective, the CPG and HPG groups presented highest values in the ∆E00 and ∆WID analysis. However, all treatments influenced the enamel surface, increasing roughness and decreasing surface and transverse microhardness. The whitening gels promoted greater chromatic changes, but all treatments affected the enamel surface, increasing roughness and decreasing surface and transverse microhardness.

Modification Mechanism and Performance of High-Content Polyurethane-Modified Asphalt

To explore the influence of the polyurethane blending ratio on the micro-characteristics of polyurethane-modified asphalt, three samples of the modified asphalt with different blending ratios (40%, 50%, and 60%) were prepared. Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were employed to elucidate the modification mechanism of polyurethane-modified asphalt. To investigate how the preparation method affects the performance of polyurethane-modified asphalt mixtures, two different preparation methods, namely internal blending and external blending, were adopted. The road performance of the polyurethane-modified asphalt mixtures was evaluated through the utilization of rutting tests, low-temperature trabecular bending tests, and freeze–thaw splitting tests. The FTIR test results indicate that during the modification of polyurethane, there is a change in both the intensity and position of the absorption peak, which affects the local arrangement of the molecular structure. Upon reaching a polyurethane blending ratio of 50%, a cross-linked network structure that is similar to polyurethane is formed. The results of the AFM test demonstrate that an increase in polyurethane content results in a corresponding increase in surface roughness. At a polyurethane content of 50%, the curing reaction is most effective, which is beneficial for enhancing the bonding performance between the asphalt and the aggregate, thereby enhancing the overall water stability of the mixture. The results of the scanning electron microscopy (SEM) tests indicate that the microstructure is more stable when the polyurethane content is 50%. The results of the performance test of the polyurethane-modified asphalt mixture indicate that the dynamic stability of the polyurethane-modified asphalt mixture is approximately four times that of the SBS-modified asphalt mixture. The flexural tensile strength and maximum flexural strain of the polyurethane-modified asphalt mixture are, respectively, 1.5 and 3.2 times those of the SBS-modified asphalt mixture, indicating that its anti-deformation ability is stronger in a low-temperature environment, and it is found that the low-temperature performance of the mixture prepared with the internal blending method is better than that with the external blending method. The splitting strength of the polyurethane asphalt mixture before and after freezing and thawing is greater than that of an SBS asphalt mixture: before freezing and thawing, by about 3.8 times; after freezing and thawing, by about 3 times. Although the freezing and thawing of the polyurethane mixture has damage, it still meets the requirements of the use of pavement materials. It can be observed that the incorporation of polyurethane alters the internal structure of the asphalt, which markedly enhances the properties of the asphalt mixture and offers a novel perspective on the development of modified asphalt materials.

Roughness Impact of Piezoelectric Dental Scaler on Two Distinct Flowable Composite Filling Materials.

Dental ultrasonic scalers are commonly employed in periodontal treatment; however, their ability to roughen tooth surfaces is a worry since roughness may increase plaque production, a key cause of periodontal disease. This research studied the influence of a piezoelectric ultrasonic scaler on the roughness of two distinct flowable composite filling materials. To do this, 10 disc-shaped samples were generated from each of the two flowable composite materials. After standardized polishing, samples were submerged in water for 24 h before the first surface examination using electron microscopy and profilometry. The ultrasonic scaler was applied to a specified location of each sample for 60 s under water cooling and regulated force. Post-scaler surface parameters were again examined. Following the application of the scaler, both composite materials exhibited a notable increase in surface roughness, as determined by profilometry (p < 0.01). Additionally, the observed surface roughness was also qualitatively visualized with scanning electron microscopy. While initial roughness levels were comparable across the two composites (p = 0.143) after scaler application, no substantial discrepancy in surface texture was noticed between them (p = 0.684). The use of a high-power piezoelectric ultrasonic scaler on routinely used flowable composite restorations might generate considerable surface roughness, possibly leading to increased plaque accumulation. Nevertheless, it might be postulated that nanohybrid flowable composite materials having conventional monomer ingredients may demonstrate comparable surface alterations within the limitations of this experiment.

Unravelling the cleavage-rate relationship from both the experimental and theoretical standpoint: The instance of fluorite dissolution.

The phenomenon of solid dissolution into a solution constitutes a fundamental aspect in both natural and industrial contexts. Nevertheless, its intricate nature at the microscale poses a significant challenge for precise quantitative characterization at a foundational level. In this work, the influence across three specific cleavage planes, namely (100), (111), and (110) on the dissolution kinetics of fluorite in aqueous environments was examined from both experimental and theoretical standpoints. For the very first time, the surface potential of fluorite planes during dissolution was measured by means of a fluorite single-crystal electrode. Experimental results indicate that the dissolution of fluorite leads to a marked increase in surface roughness as well as an augmentation in the surface area of all analyzed surfaces. The most significant alteration in roughness is observed on the (111) plane, whereas the most substantial increase in surface area occurs on the (110) plane. In comparison to the (100) crystallographic plane, which demonstrates the slowest dissolution kinetics, the (111) and (110) planes display dissolution at a comparatively expedited rate. Theoretical simulations corroborate this trend, concurrently facilitating an effective examination of the system's free-energy landscape to analyze the dynamics and rates associated with the attachment and detachment of ions to the fluorite surface. Notably, the presence of interfacial defects has the potential to influence the free energy landscape, thereby altering the transition of ions into the bulk solution. Ultimately, the interplay of correlations and discrepancies between experimental findings and theoretical predictions is critically examined.

Surface roughness of composite resins subjected to brushing with whitening toothpastes: an in vitro study.

The emergence of toothpastes containing different abrasive and whitening substances has been a constant concern among dental professionals. The aim of the present study was to perform an in vitro assessment of the surface topography of nanoparticle composite resins subjected to simulated brushing with dentifrices. Test samples were prepared with Filtek Universal (3M ESPE), Filtek Bulkfill (3M ESPE) and Z350 (3M ESPE), with 24 samples per resin. A testing machine was used to simulate brushing with the dentifrices Colgate Total 12, Oral B 100% and Oral B Gengiva Detox Gentle Whitening (8 samples per group). The constant speed of the machine was 250 cycles per minute, and 20.000 cycles were carried out, which corresponds to 24 months (1 hour and 20 minutes). Roughness features and qualitative surface topography were investigated. Statistical analysis involved the Kruskal-Wallis, Wilcoxon and Mann-Whitney tests. A significant increase in surface roughness was found for all the resins (p < 0.05). However, no significant difference was found among the resins in terms of final roughness values (p = 0.690). In contrast, a significant difference among dentifrices was found with respect to roughness measurements (p < 0.001). The qualitative analysis revealed an increase in surface roughness in all the samples and differences in the abrasive potential of the dentifrices. In conclusion, brushing with dentifrices increases the surface roughness parameters of composite resin restorations. Moreover, the differences in the abrasive effects of the dentifrices indicate a need for further studies to establish efficacy and safety criteria.

Influences of roughness and filling degree on the shear strength and damage evolution characteristics of cement-filled joints.

The shear resistance of filling joints is an important factor affecting the stability of rock joints. Pressure-shear tests of cement-filled joints were carried out. Combined with the acoustic emission (AE) technique, the effects of normal stress, roughness and filling degree on the shear strength, damage morphology and damage evolution of cement-filled joints were investigated. The results show that with the increase of roughness, the failure mode is more complicated. When the roughness is low, only the bonding surface of the interface between the filler and the joint surface is damaged, and the filling degree has a weak effect on the failure mode. When the roughness is high, with the increase of normal stress and filling degree, the failure of the filled joint is from the joint failure of the bonding surface and the filling material to the serious failure of the bonding surface, the filling material and the joint. The peak shear strength of filled joints is positively correlated with roughness and negatively correlated with filling degree. With the increase of filling degree, the influence of roughness will be weakened by filling material, and the normal stress will amplify the effect of roughness. The evolution characteristics of AE show that the damage degree of filled joints is positively correlated with normal stress and roughness, and negatively correlated with filling degree. The joint surface is damaged locally at first, then failure near the main raised body of the joint, and finally spreads to the whole joint surface.

Surface Roughness and Color Stability of Conventional and Bulk-Fill Resin Composite with S-PRG Fillers After Coffee Exposure: An in-vitro Study.

This study aimed to evaluate the in vitro effects of coffee exposure on the color and roughness of conventional and bulk-fill resin composites, with and without surface pre-reacted glass-ionomer (S-PRG) filler. Forty-eight cylindrical samples (Ø6 mm × 2 mm) were prepared and categorized as follows (n = 12 per group): conventional nano-hybrid (Tetric N-Ceram, Ivoclar); nano-hybrid with S-PRG filler (Beautifil II, Shofu); bulk-fill (Tetric N-Ceram Bulk Fill, Ivoclar); and bulk-fill with S-PRG filler (Beautifil Bulk Restorative, Shofu). The samples were assessed for surface roughness (Ra, μm), color coordinates (CIE Lab), and overall color change (ΔEab, ΔE00). Measurements were taken at baseline and after 7 days of coffee immersion (pH = 4.95). Data were analyzed using generalized linear models, Kruskal-Wallis, Dunn, and paired Wilcoxon tests (α = 0.05). After the coffee exposure, all resin composites exhibited a significant decrease in L* (towards black), an increase in a* (towards red), an increase in b* (towards yellow), and a higher Vita color score (p < 0.05). Tetric N-Ceram demonstrated the lowest roughness values post-exposure; however, a significant increase in roughness over time was observed only for Tetric N-Ceram Bulk Fill (p < 0.05). For ΔEab, Beautifil Bulk Restorative and Tetric N-Ceram showed higher values compared to Beautifil II. For ΔE00, a significant difference was noted between Beautifil Bulk Restorative and Beautifil II (p < 0.05). Resin composites with S-PRG fillers exhibited similar pigmentation dynamics to conventional composite but showed greater surface roughness after exposure to coffee. Considering the S-PRG materials, the bulk-fill version is more susceptible to staining.

Coating Agents for Resin Composites: Effect on Color Stability, Roughness, and Surface Micromorphology Subjected to Brushing Wear.

This study evaluated the influence of six resin composite coating agents on color stability and surface roughness after toothbrushing abrasion. Discs (Ø6 mm x 2 mm) of nanofilled resin composite (Filtek Z350XT) were prepared for application of coating agents (n=10): control (absence), two surface sealants (PermaSeal and BisCover LV), two adhesive systems (Scotchbond Multi-Purpose Adhesive/3M Oral Care and Single Bond Universal), and two modeling liquids (Modeling Resin and Composite Wetting Resin). CIELab*, WID, and color change (ΔEab, ΔE00, and ΔWID) were analyzed at baseline, after finishing and polishing, after application of coating agents, after coffee staining (simulating 30 days and one year of staining), and after toothbrushing abrasion. Roughness evaluations (Ra) were performed at the initial time point, after finishing and polishing, after application of coating agents, and after toothbrushing abrasion. Surface micromorphology was evaluated (2,000×) before and after toothbrushing abrasion. Generalized linear mixed models or Kruskal-Wallis and Dunn tests (α=0.05) showed that L* decreased significantly (p<0.0001) and a* increased significantly in all the groups after staining (p<0.0001). After toothbrushing, Modeling Resin showed higher ΔEab and ΔE00 than the control, Scotchbond Multi-Purpose Adhesive, Composite Wetting Resin, PermaSeal, or BisCover LV (p<0.0001). There was a significant increase in roughness for Composite Wetting Resin, Modeling Resin, and PermaSeal after application of the agents (p<0.05), but a significant decrease for BisCover LV (p<0.05), which achieved high surface smoothness. After abrasive wear, BisCover LV showed the lowest roughness values among all agents. Composite Wetting Resin and Modeling Resin showed higher roughness than the other groups (p<0.05), and surface irregularities. In conclusion, the coating agents did not prevent coffee staining, and they also led to increased surface roughness, with only BisCover LV providing greater surface smoothness after toothbrush abrasion.

Analysis of the effect of joint roughness on the failure mechanism of jointed rock mass under direct shear loading.

The mechanical properties of jointed rock bodies are important in guiding engineering design and construction. Using the particle flow software PFC2D, we conducted direct shear test simulations on joints with various inclinations and five different roughness levels to examine the models' crack extension penetration paths, damage modes, and strength characteristics. The findings indicate that the direction of the joint influences the pattern of the rock crack and its penetration route. Under forward shear, the rock bridge creates a notched through surface, whereas under reverse shear it creates two adjacent through surfaces, categorised into four types of crack consolidation between joints with different inclinations: 'end to end', 'the end is connected to the middle', 'end connection', 'first outward expansion and then rock bridge destruction'. Variations in joint inclination and roughness can alter the mechanical properties and damage patterns of joint specimens. The 'climbing' and 'gnawing' effects determine the peak shear strength of the rock body at the joint section. It is vital to consider these factors when assessing the joint's characteristics. The damage effect is determined by the joint inclination and joint roughness. When the main damage effect changes from 'creeping' slip to 'gnawing' damage, increasing joint roughness enhances the shear strength. Nevertheless, under the same 'gnawing' damage effect, augmenting joint roughness weakens the mechanical properties of the rock bridge, and as roughness increases, the shear strength decreases. For example, at a joint inclination of 30°, the shear strength increases by 20.1% as the JRC (Joint Roughness Coefficient) increases from 0 to 5. At a joint inclination of 60°, the shear strength decreases by 10.7% as the JRC increases from 0 to 10.

Effects of Gamma Irradiation on Structural, Chemical, Bioactivity and Biocompatibility Characteristics of Bioactive Glass-Polymer Composite Film.

Gamma irradiation is an effective technique for biocomposite films intended for application in tissue engineering (TE) to ensure sterility and patient safety prior to clinical applications. This study proposed a biocomposite film composed of natural polymer chitosan (CS) and synthetic polymer poly-Ɛ-caprolactone (PCL) reinforced with sol-gel-derived bioactive glass (BG) for potential application in TE. The BG/PCL/CS biocomposite film was sterilized using 25 kGy gamma rays, and subsequent changes in its characteristics were analyzed through mechanical and physical assessment, bioactivity evaluation via immersion in simulated body fluid (SBF) and biocompatibility examination using human primary dermal fibroblasts (HPDFs). Results indicated a homogeneous distribution of BG particles within the BG/PCL/CS polymer matrix which enhanced bioactivity, and the polymer blend provide a structurally stable film. Gamma irradiation induced an increase in the film's surface roughness due to photo-oxidative degradation; however, this did not adversely affect the integrity of glass particles and polymer chains. Invitro assessments demonstrated hydroxyapatite formation on the film's surface, suggesting bioactivity. Biocompatibility testing confirmed enhanced cell adhesion and proliferation. These multifunctional properties highlight the potential of the fabricated BG/PCL/CS biocomposite film for TE and regenerative medicine applications.

Dynamic characteristics of droplets' impact on solid surfaces with varied roughness

Probing into the process of droplets impacting solid surfaces and revealing their underlying behavioral characteristics is paramount across diverse fields. A high-speed camera capable of recording at 10,000 frames per second is utilized to capture the impact process of droplets on various rough surfaces. The effects of the droplets' properties, surface roughness, and surface wettability on the dynamic spread of droplets on solid surfaces are investigated. The research demonstrates that the addition of surfactants reduces the surface tension of droplets and dampens their vertical oscillations on surfaces, leading to decrease in the time required to achieve equilibrium. The increase in surface roughness leads to the decrease in droplet retraction degree and the decrease in maximum spreading coefficient. The surface wettability also influences the maximum spread coefficient and equilibrium time. The equations for the maximum spreading coefficient of the droplets on a solid surface with respect to the Weber number (We) and the revised capillary number (Ra*) are obtained by quantitative analysis.

Optimization of surface roughness for titanium alloy based on multi-strategy fusion snake algorithm.

Titanium alloy is known for its low thermal conductivity, small elastic modulus, and propensity for work hardening, posing challenges in predicting surface quality post high-speed milling. Since surface quality significantly influences wear resistance, fatigue strength, and corrosion resistance of parts, optimizing milling parameters becomes crucial for enhancing service performance. This paper proposes a milling parameter optimization method utilizing the snake algorithm with multi-strategy fusion to improve surface quality. The optimization objective is surface roughness. Initially, a prediction model for titanium alloy milling surface roughness is established using the response surface method to ensure continuous prediction. Subsequently, the snake algorithm with multi-strategy fusion is introduced. Population initialization employs an orthogonal matrix strategy, enhancing population diversity and distribution. A dynamic adaptive mechanism replaces the original static mechanism for optimizing food quantity and temperature, accelerating convergence. Joint reverse strategy aids in selecting and generating individuals with higher fitness, fortifying the algorithm against local optima. Experimental results across five benchmarks employing various optimization algorithms demonstrate the superiority of the MSSO algorithm in convergence speed and accuracy. Finally, the multi-strategy snake algorithm optimizes the objective equation, with milling parameter experiments revealing a 55.7 percent increase in surface roughness of Ti64 compared to pre-optimization levels. This highlights the effectiveness of the proposed method in enhancing surface quality.