Search Results (98)

This study develops and assesses a hydrophobized fly ash mineral powder as a filler for dense fine-graded asphalt mixtures in Kazakhstan. Fly ash from a local TPP was dry co-milled with a stearate-based modifier to yield a free-flowing, hydrophobic powder that meets the national limits for moisture, porosity, and gradation. SEM shows cenospheres and broken shells partially armored by adherent fines, suggesting an increased micro-roughness and potential sites for binder–filler bonding. Three mixes were produced: a carbonate reference and two fly ash variants, all designed at the same optimum binder content. Compared with the reference, fly ash fillers delivered a markedly higher compressive strength (up to about five times at 20 °C), improved adhesion, and high internal friction, while the mixture density rutting resistance was essentially unchanged. Water resistance indices remained high and stable despite only modest changes in water saturation, and crack resistance improved, especially for the dry ash mixture. The convergence of microstructural, physicochemical, and mechanical results shows that surface-engineered fly ash from a Kazakhstani TPP can technically replace natural carbonate filler while enhancing durability-critical performance and supporting the more resource-efficient use of industrial by-products in pavements. Full article

Improving the operational parameters of machinery necessitates the use of materials with higher mechanical characteristics. Strength characteristics, particularly fracture toughness, are strongly linked to the material’s microstructure. This article presents the results of a study examining the effect of microstructure on the mechanical properties and fracture toughness of G17CrMo5-5 cast steel in its basic and rare-earth modified variants. The addition of rare-earth elements (REEs) to the melt resulted in a reduction and homogenization in grain size, as well as a reduction in the size and shape of non-metallic inclusions. For modified cast steel, there were no grains with a chord size above 120 μm and inclusions with a diameter above 5.5 μm. Changes in the microstructure of modified cast steel resulted in a slight increase in strength properties. It significantly increased the fracture toughness: for unmodified cast steel at a temperature of −20 °C, the fracture toughness increased from 94 kN/m to 416 kN/m for modified cast steel. Fracture fractographic analysis using non-contact microroughness measurement techniques or measuring the width of the stretch zone allowed for the calculation of fracture toughness without the need for a conventional test. Fracture toughness calculated based on fractographic analysis can be determined for brittle fracture and brittle fracture preceded by plastic growth. Numerical simulations of the loading of specimens tested for fracture toughness allowed us to determine the effect of the REE steel modification on the stress field distribution ahead of the crack front. The modification resulted in a change in the opening stress distribution and the location of its maximum at each temperature. The use of REE modification is an effective approach for homogenizing the microstructure and increasing the fracture toughness of cast steel, especially when the material operates at temperatures in the interval of the fracture mechanism change. Full article

Background: Whether nanoengineered titanium surfaces confer superior implant stability beyond modern microrough controls remains uncertain. Methods: This systematic review followed PRISMA 2020 guidance: comprehensive multi-database searching with de-duplication; dual independent screening, full-text assessment, and standardized data extraction for predefined outcomes (implant stability quotient [ISQ], mechanical anchorage by removal/push-out/pull-out torque, and histologic bone-to-implant contact). Risk of bias was appraised with RoB 2 for randomized trials, ROBINS-I for non-randomized clinical studies, and CAMARADES (animal experimentation). The certainty of clinical evidence was summarized using GRADE. Results: Across animal models, nanoengineered surfaces consistently improved early osseointegration indices (higher removal torque and bone-to-implant contact at initial healing). In clinical comparative studies, nanoengineered implants showed modest, time-limited gains in early stability (ISQ) versus microrough titanium. By 3–6 months, between-group differences typically diminished, and no consistent advantages were demonstrated for survival or marginal bone outcomes at later follow-up. Methodologic heterogeneity (surface chemistries, timepoints, outcome definitions) and small clinical samples limited quantitative synthesis. Overall, risk-of-bias concerns ranged from some concerns to high in non-randomized studies; the certainty of clinical evidence was low. Conclusions: Nanofeatured titanium surfaces improve early osseointegration but do not demonstrate a consistent long-term advantage over modern microrough implants. Current evidence supports an early osseointegration benefit without clear long-term clinical advantage over contemporary microrough implants. Adequately powered, head-to-head trials with standardized stability endpoints and ≥12-month follow-up are needed to determine whether early gains translate into patient-important outcomes. Full article

There is a lack of information in the literature on the influence of technological heredity on surface integrity characteristics after diamond burnishing (DB). The present study fills this gap. Here, we present the effects of DB on the roughness parameters and surface microhardness of heat-treated C45 steel under conditions of changing initial roughness (Ra^init) due to wear on the cutting insert in the previous turning. The aim was to quantitatively assess the ability of DB to maintain sustainable surface integrity characteristics. We found that the service life of the cutting insert up to complete wear or fracture when operating at an optimal feed rate and cutting velocity was 163 min, at which point the roughness changed unevenly from an average roughness (Ra) value of 0.38 to 1.31 μm and an average height of the profile microroughness (Rz) value of 2.21 to 6.13 μm. Under conditions of an artificially created Ra^init (through different combinations of feed rate and cutting velocity) of 0.308 to 10.688 μm, DB provided Ra values in the range of 0.042 to 0.316 μm, with the surface microhardness varying from 461 to 568 HV. Stable Ra values were maintained from 0.042 μm to 0.089 μm, after which the Ra^init increased to 3.379 μm. Under production conditions, where the previous turning was performed at an optimal feed rate of 0.05 mm/rev and a cutting velocity of 180 m/min, DB provided a stable Ra of ≤0.059 μm of a resulting mirror-like surface during the first 90 min of operation of a new (unused) cutting insert, after which the Ra values increased linearly from 0.059 to 0.133 μm in the 150th minute. After 30 min of operation, until the cutting insert was completely worn, the microhardness after DB varied from 676 to 795 HV, the high surface microhardness resulting from a complex process of surface thermo-mechanical strengthening (including strain and transformation hardening) in the previous turning due to wear on the cutting insert. Full article

This review addresses four controversial aspects of shot blasting in the surface treatment of titanium dental implants. Shot blasting, which involves the projection of abrasive particles onto the titanium surface, is widely used to achieve surface roughness that promotes osteoblastic activity and, consequently, high levels of osseointegration. The first issue examined is the effect of residual alumina particles that remain embedded in the titanium surface after blasting. It has been shown that these residues—typically not exceeding 8% of the surface—can actually enhance osseointegration and even exhibit mild bactericidal properties. The second issue concerns the use of titanium dioxide particles for blasting. Our findings indicate that due to its low abrasiveness, titanium dioxide produces minimal surface roughness and low surface energy, resulting in limited osteoblastic adhesion, inferior fatigue performance, and reduced osseointegration compared to alumina-blasted surfaces. The third topic focuses on the role of compressive residual stress induced by grit blasting. Residual stress contributes to increased surface hydrophilicity, enhancing osteoblast adhesion and mineralization, as evidenced by elevated alkaline phosphatase levels. Finally, the fourth issue involves the effect of acid etching following grit blasting. This treatment introduces microroughness superimposed on the macroroughness generated by grit blasting. In vivo studies demonstrate that grit blasting is the primary driver of osseointegration, while acid etching provides only a marginal improvement in bone–implant contact. Full article

Background/Objectives: Gingival recession poses significant challenges in periodontal therapy, particularly in procedures aimed at achieving predictable root coverage and long-term stability of grafts. Conditioning of the root surface plays a crucial role in improving biomaterial adhesion and facilitating periodontal regeneration. This in vitro study aimed to evaluate the morphological and microroughness alterations of root cementum following different mechanical and chemical conditioning protocols commonly used in mucogingival surgery. Methods: Forty extracted human single-rooted teeth were randomly allocated into eight groups: untreated control, mechanical scaling alone, and scaling combined with ethylenediaminetetraacetic acid (EDTA), citric acid, phosphoric acid, tetracycline, doxycycline, or saline. Surface roughness was measured using contact profilometry, while structural modifications were analyzed via scanning electron microscopy. Results: Statistically significant intergroup differences (p < 0.05) were observed. Baneocin treatment produced the most conservative changes, with limited surface roughness and minimal structural alteration, whereas phosphoric acid, tetracycline, and EDTA caused pronounced demineralization and surface porosity. Citric acid and doxycycline induced moderate alterations, with partial preservation of cementum integrity. The null hypothesis assuming no surface or morphological changes was rejected. Conclusions: These findings indicate that low-aggressiveness agents may achieve an optimal balance between surface decontamination and cementum preservation, which is critical for enhancing graft integration and improving clinical outcomes in root coverage surgery. Full article

Preparing a bioactive surface with a hierarchical micro/nanostructure can improve the osseointegration of titanium implants. In this study, titanium was sand blasted and etched in H₂SO₄ solution to obtain micro-rough morphology. The samples were then hydrothermally treated in the concentrated CaHPO₄ solution at 120–200 °C for 24 h to grow films consisting of anatase TiO₂ and hydroxyapatite nanoparticles (size 80–240 nm). The hydrothermally calcified (200 °C) sample exhibited much better corrosion resistance in the salt solution, as well as similar cellular viability and a higher alkaline phosphatase level in the cell tests using MC3T3-E1 cells, in comparison with the polished titanium sample. The hybrid treatment is a facile and effective method to a form bioactive surface with a hierarchical micro/nanostructure on titanium. Full article

This study investigates the potential of Selective Laser Melting (SLM) to tailor the surface characteristics of Ti6Al4V directly during fabrication, eliminating the need for post-processing treatments potentially for dental implants. By adjusting the Volumetric Energy Density (VED) through controlled variations in the laser scanning speed, we achieved customized surface textures at both the micro- and nanoscale levels. SLM samples fabricated at moderate VED levels (50–100 W·mm³/s) exhibited optimized dual-scale surface roughness—a macro-roughness of up to 25.5–27.6 µm and micro-roughness of as low as 58.8–64.2 nm—resulting in significantly enhanced hydrophilicity, with water contact angles (WCAs) decreasing to ~62°, compared to ~80° on a standard grade 5 machined Ti6Al4V plate. The XPS analysis revealed that the surface oxygen content remains relatively stable at low VED values, with no significant increase. The surface topography plays a significant role in influencing the WCA, particularly when the VED values are low (below 200 W·mm³/s) during SLM, indicating the dominant effect of surface morphology over chemistry in these conditions. Biological assays using osteoblast-like MG-63 cells demonstrated that these as-built SLM surfaces supported a 1.5-fold-higher proliferation and improved cytoskeletal organization relative to the control, confirming the enhanced early cellular responses. These results highlight the capability of SLM to engineer bioactive implant surfaces through process-controlled morphology and chemistry, presenting a promising strategy for the next generation of dental implants suitable for immediate placement and osseointegration. Full article

This paper focuses on the coupling relationships between the optical constants (n: refractive index; k: extinction coefficient) and Mueller matrix elements, as well as between the morphological parameters (σ: root mean square roughness; τ: correlation length) and Mueller matrix elements, of randomly micro-rough surfaces. The electromagnetic response of randomly micro-rough surfaces was simulated by the finite-difference time-domain method, so that the rough surfaces’ reflection coefficients of incident light in the p and s directions could be obtained. According to the formula for the Jones-to-Mueller matrix conversion, we obtained a 4 × 4 Mueller matrix of rough surfaces. The simulation method was validated with experimental results measured by Mueller matrix spectroscopic ellipsometry. It was found that the Mueller matrix element m₁₂ has great potential to invert the optical constants of the rough surfaces, whose refractive indices, n, and extinction coefficients, k, are in the ranges of 0 ≤ n ≤ 4 and 0 ≤ k ≤ 10, respectively. The Mueller matrix element m₃₄ is proportional to the morphological parameters σ/λ (λ: incident wavelength) or σ/τ. Moreover, the expressions (S + β₂) ∝ σ/λ and (S + β₂) ∝ σ/τ can be applied to predict the morphologies of rough surfaces within morphological parameter ranges of 0.003 ≤ σ/λ ≤ 0.015 and 0.125 ≤ σ/τ ≤ 0.75. This research signifies a key step toward the ability to invert the morphological parameters or optical constants of micro-rough surfaces through a Mueller matrix. Full article

The dust generated during the sandblasting process of the sandblasted and acid-etched (SLA) method, commonly used to treat the surface of Ti dental implants, poses significant challenges in maintaining a clean manufacturing environment and ensuring safe working conditions. Nevertheless, surface modification remains crucial for improved performance of Ti dental implants. To address this problem and propose a clean and simple surface modification process to potentially replace SLA modification, this study aimed to characterize the surfaces of commercially pure Ti (cp-Ti) samples treated by acid etching and compare them with SLA-treated samples in terms of surface roughness (R_q), wettability (assessed through contact angle measurements), mineralized matrix deposition (evaluated through simulated body fluid [SBF] soaking), cell viability, cell differentiation (assessed based on alkaline phosphatase activity), and mineralization (assessed using MTT assay). Acid-etched surfaces exhibited nano- and micro-roughness and higher hydrophilicity than SLA surfaces, which is conducive to forming a highly bioactive TiO₂ surface. Moreover, acid-etched samples exhibited earlier hydroxyapatite deposition after SBF soaking than SLA samples. Furthermore, the acid-etched surfaces were nontoxic and displayed significantly higher cell viability and differentiation after seven days than SLA surfaces. These findings suggest that acid etching is a viable alternative to the SLA method, likely offering superior surface bioactivity and biocompatibility. Full article

The handling and fluidization of amorphous soft solids, such as emulsions, foams, or gels, is crucial in many technological processes. This is generally achieved by applying mechanical stress that overcomes a critical threshold, known as yield stress, below which these systems behave as elastic solids. However, the interaction with the walls can facilitate the transition from solid to fluid by activating rearrangements of the fluid constituents close to the wall, resulting in increased fluidity of the system up to distances greater than the spatial scale of the rearrangements. We address the impact of wedge-shaped microroughness on activating the fluidization of emulsion droplets in pressure-driven flow through microfluidic channels. We realize the micro wedges by maskless photolithography to texture one wall of the channel and measure the velocity profiles for flow directed accordingly and against the increasing ramp of the wedge-shaped grooves. We report the enhancement of the emulsion flow in the direction of the climbing ramp of the wedge activated by increasing the magnitude of the pressure gradient. A gain for the volumetric flow rate is registered with respect to the opposite direction as being to $30\%$, depending on the pressure drop. Full article

Background: The physicochemical changes of the surface aim to improve cell adhesion, proliferation, and differentiation, that is, better biological interaction with the cells and, consequently, with the peri-implant tissues. In the present study, implants with the same macrogeometry were compared in vitro and in vivo, but with two different surfaces: micro-rough and a new micro-nano-rough surface. Materials and Methods: A total of 90 implants were used, 10 of which were used for in vitro surface characterization (n = 5 per group) through scanning electron microscopy (SEM), atomic force microscopy (AFM), and surface roughness measurements. For in vivo tests, 80 implants (n = 40 per group) were used in 20 rabbits (n = 2 implants per tibia). Two experimental groups were created: a control group, where the implants had a surface treated by sandblasting with titanium oxide microparticles, and a test group, where the implants were sandblasted using the same process as the previous group plus acid conditioned. The implant stability quotient (ISQ) was measured by resonance frequency (initially and at both euthanasia times). Animals were euthanized 3 and 5 weeks after implantation (n = 10 animals per time). Ten samples from each group at each time point were evaluated by removal torque (RTv). Another ten samples from each group were evaluated histologically and histomorphometrically, measuring the percentage of bone-to-implant contact (%BIC) and the bone area fraction occupancy (%BAFO). Results: In vitro, it was possible to observe a more homogeneous surface for the test group compared to the control group. ISQ values showed statistical differences at both 3 and 5 weeks (test > control). For RTv, the values were: 44.5 ± 4.25 Ncm (control group) and 48.6 ± 3.17 Ncm (test group) for the time of 3 weeks; 64.3 ± 4.50 Ncm (control group) and 76.1 ± 4.18 Ncm (test group) at 5 weeks. The %BIC and %BAFO values measured in both groups and at both times did not show significant differences (p > 0.05). Conclusions: The higher removal torque and ISQ values presented in the samples from the test group compared to the control group indicate that there was an acceleration in the mineralization process of the newly formed bone matrix. Full article

The aim of this study was to compare the effect of increasing concentrations (0, 1, 2, 4%) of sea buckthorn oil (SBO) on the structural, physicochemical, release, and antioxidant properties of glycerol-plasticized sodium casein (NaCAS) and gelatin (GEL) films. Ultrasonic treatment ensured effective homogenization of SBO in both types of emulsions, resulting in yellow-tinted semi-opaque films with relatively low micro-roughness. Generally, GEL films demonstrated lower UV barrier properties and solubility but exhibited higher compactness, crystallinity, transparency, surface hydrophobicity, oxygen barrier performance, strength, and antiradical activity compared to their NaCAS-based counterparts. In a concentration-dependent manner, SBO decreased the solubility and water absorption of the gelatin-based film and enhanced its oxygen permeability. Conversely, SBO improved the water vapor barrier properties of both films in a concentration-independent manner. At the highest SBO concentration, the tensile strength of NaCAS- and GEL-based films decreased by 27% and 20%, respectively, while their antiradical activity increased by 9.3× and 4.3× (based on the time required for the half-neutralization of 2,2-diphenyl-1-picrylhydrazyl radicals). Migration studies showed that at the lowest concentration, SBO was released (into 95% ethanol) approximately 2× faster from the GEL-based film than from the NaCAS film, whereas at higher concentrations, the trend reversed. Full article

The surface topography and chemistry of titanium–aluminum–vanadium (Ti6Al4V) implants play critical roles in the osteoblast differentiation of human bone marrow stromal cells (MSCs) and the creation of an osteogenic microenvironment. To assess the effects of a microscale/nanoscale (MN) topography, this study compared the effects of MN-modified, anodized, and smooth Ti6Al4V surfaces on MSC response, and for the first time, directly contrasted MN-induced osteoblast differentiation with culture on tissue culture polystyrene (TCPS) in osteogenic medium (OM). Surface characterization revealed distinct differences in microroughness, composition, and topography among the Ti6Al4V substrates. MSCs on MN surfaces exhibited enhanced osteoblastic differentiation, evidenced by increased expression of RUNX2, SP7, BGLAP, BMP2, and BMPR1A (fold increases: 3.2, 1.8, 1.4, 1.3, and 1.2). The MN surface also induced a pro-healing inflammasome with upregulation of anti-inflammatory mediators (170–200% increase) and downregulation of pro-inflammatory factors (40–82% reduction). Integrin expression shifted towards osteoblast-associated integrins on MN surfaces. RNA-seq analysis revealed distinct gene expression profiles between MSCs on MN surfaces and those in OM, with only 199 shared genes out of over 1000 differentially expressed genes. Pathway analysis showed that MN surfaces promoted bone formation, maturation, and remodeling through non-canonical Wnt signaling, while OM stimulated endochondral bone development and mineralization via canonical Wnt3a signaling. These findings highlight the importance of Ti6Al4V surface properties in directing MSC differentiation and indicate that MN-modified surfaces act via signaling pathways that differ from OM culture methods, more accurately mimicking peri-implant osteogenesis in vivo. Full article

The distribution of voids in ceramic topcoats (TC) and the micro-roughness of metallic bond coat (BC) interfaces are important for the structure design and coating life of thermal barrier coating (TBC) systems. In this study, finite elemental (FE) models were built by considering those two structural factors to investigate their influence on the stress distribution in TBCs in quenching processes under thermal shock conditions. According to the simulation analyses, the function of the voids in TCs includes the dilution effect of the stress concentration at the macro-scale, the releasing effect of the tensile stress along the vertical direction above the TC peak, and the “stress trapping” effect bringing higher stress at the horizontal tips of the voids on the micro-scale. The micro-roughness of the TC/BC interface did not have much effect on the stress values in the TC, aside from at the TC peak, but had a significant influence on the stress value along the interface due to the “stress trapping” effect. The TBC samples that were experimentally tested under water-cooling thermal shock conditions were also analyzed in this paper to verify the modelling results. Full article