Search Results (5,032)

This article focuses on evaluating selected roughness parameters on samples created by material extrusion, specifically FFF (Fused Filament Fabrication). The experiment was divided into two separate phases. The first phase of the experiment involved creating a four-level model A from PLA (poly (lactic acid)) material without any additives. The variable parameter was the height of the printed layer, where each level was printed at a different print height. Subsequently, the sandblasting method was applied to the samples using a selected abrasive. The roughness parameters were evaluated using a Mitutoyo Surftest SJ-400 roughness tester. Based on the results of the roughness parameters of model A, model B was prepared, using a constant print height. Each level of model B was made with different metallic additives based on PLA material. The findings demonstrate the effectiveness of mechanical post-processing in achieving the desired surface characteristics of additively manufactured components. The experiment confirms the suitability of sanding and grinding to improve surface quality at different layer heights and for PLA-based materials with metal additives. In addition, grinding and sanding of PLA-based composites filled with metal particles can create a realistic metallic appearance comparable to conventionally manufactured metals. Full article

Concrete structures are vulnerable to sulfate attacks during their service life, as sulfate ions react with cement hydration products to form expansive phases, generating internal stresses that cause mechanical degradation. In this study, a cementitious capillary crystalline waterproofing material (CCCW) was incorporated into concrete to mitigate sulfate ingress and enhance sulfate resistance. The evolution of compressive strength, ultrasonic pulse velocity, dynamic elastic modulus, and the microstructure of concrete was investigated in sulfate-exposed concretes with varying CCCW dosages and strength grades; the sulfate ion concentration profiles were also analyzed. The results indicate that the enhancement effect of CCCW on sulfate resistance declines progressively with increasing concrete strength. The formation of calcium silicate hydrate and calcium carbonate fills the pores of concrete, hindering the intrusion of sulfate solution. Moreover, the self-healing effect of concrete further inhibits the diffusion of sulfate ions through cracks, improving the sulfate resistance of concrete. These findings provide critical insights and practical guidance for improving concrete resistance to sulfate-induced deterioration. Full article

Background/Objectives: Glidants and lubricants are commonly used pharmaceutical excipients that enhance powder flowability and reduce inter-particle friction, respectively, but they also negatively impact critical quality attributes such as tablet tensile strength and drug release rate. Quantifying these effects is essential as the pharmaceutical industry transitions from batch to continuous manufacturing. Methods: This study develops a rational-function-based modeling approach to capture the effects of lubricants and glidants on tableting. The framework automatically identifies upstream critical material attributes and process parameters, such as excipient concentration and mixing time, and describes their coupling to first and second orders. Reduced-order models were constructed to evaluate the influence of these variables on the four stages of powder compaction—die filling, compaction, unloading, and ejection—using formulations composed of 10% acetaminophen, microcrystalline cellulose, and varying small concentrations of magnesium stearate or colloidal silica. Tablets were fabricated across a wide range of relative densities by varying dosing position and turret speed. Results: The modeling approach successfully quantified the effects of lubricant and glidant mixing conditions on each compaction stage, providing mechanistic insight into how upstream conditions propagate through the tableting process and influence critical quality attributes. Conclusions: Overall, the rational-function-based framework offers a systematic approach to quantify and predict the impact of lubricants and glidants on tablet performance, thereby enhancing product and process understanding in continuous manufacturing. Full article

Nanomaterials play a beneficial role in regulating the function of cement-based materials. The effects and mechanism of graphene oxide (GO) on foam behavior in solutions and air-entraining behavior of cement mortar were studied, and its effect on the microstructure of cement mortar was also investigated. The results show that a synergy between GO’s hydrophobicity and the air-entraining agent’s hydrophobic chains drove more agent molecules to adsorb onto the GO surface, subsequently spreading and aggregating across the bubbles. GO effectively assisted the air entraining agent to refine the bubble size, improved the bubble stability of aqueous solutions, and had excellent air entraining performance in the fresh cement mortar, as well as the optimum air-void adjustment performance of hardened cement mortars. With the addition of 0.4‰ GO, the loss rate of gas content in the GO mixed mortar was 10.3%, which was 55.8% lower than that when only using AEA. The addition of 0.4‰ of GO effectively increased the volume fraction of the cement mortar system. GO reduced the pore volume in the mortar through the filling effect and nucleation effect to reduce the total porosity and refine the microstructure of the mortar. Full article

The engineering applicability of alkali-activated mortar (AAM) is limited by high shrinkage and fast setting time. In this study, the shrinkage performance of AAM was regulated by adding desulfurization gypsum (DG), and the effects of DG content on its workability, corrosion resistance, and mechanical properties were systematically investigated. The test included fluidity, setting time, compressive strength, drying shrinkage, water erosion resistance, and sulfate erosion resistance and was combined with microscopic analysis to reveal its phase composition and micro-morphology. The results show that DG can significantly prolong the setting time and reduce the drying shrinkage. With a DG content of 10%, alkali-activated materials exhibited a setting time similar to that of OPC, and the 56-d drying shrinkage of the AAM was reduced by 20.2%. However, the fluidity, water erosion resistance, and sulfate resistance decreased with an increase in DG content. When the DG content was 10%, the fluidity of the AAM reached 126 mm, and its setting time was equivalent to that of OPC. The mechanical properties showed a trend of increasing first and then decreasing. The optimum was reached when the DG content was 6%. The 28-d compressive strength of AAM-6 was 63.25 MPa, and after 60 days of water erosion and sulfate corrosion its residual strength was still higher than that of OPC in the same environment. Microscopic analysis showed that DG promoted the formation of ettringite, which filled pores with age and formed a dense structure, thereby improving mechanical properties and inhibiting shrinkage. This study enhances the engineering applicability of AAM while enabling high-value utilization of industrial solid waste for sustainable construction materials. Full article

Background and Objectives: Breast cancer (BC) is a complex disease requiring a comprehensive treatment approach due to its diverse characteristics. Critical molecular determinants of BC have been identified using advanced genomic, transcriptomic, and proteomic approaches. Assessing the biomarkers associated with the onset of early-stage BC may help identify the risk of metastasis and inform treatment decisions. A previous bioinformatic analysis using two large BC cohorts identified pumilio RNA binding family member 1 (PUM1) as a key gene in invasive BC. However, no study has yet examined the prognostic and predictive value of PUM1 in invasive BC and its correlation with aggressive tumor behavior. This study aimed to fill this need. Materials and Methods: Correlations between PUM1 expression and patients’ clinicopathological characteristics and outcomes were explored in publicly available BC transcriptomic data acquired using DNA microarrays (n = 10,872) and RNA sequencing (n = 4421) using BC Gene-Expression Miner v5.0. PUM1 expression in samples from 100 patients with invasive BC at King Abdul Aziz Specialist Hospital, Saudi Arabia, was assessed immunohistochemically. Correlations between PUM1 expression and patients’ clinicopathological characteristics (e.g., age, tumor grade, tumor size, and outcome) were assessed. The online platform ROC Plotter was also used to investigate the predictive significance of PUM1. Results: High PUM1 gene and protein expression correlated positively with aggressive features of BC, including high histological grade, high Ki-67 expression, negative hormone receptors, and the triple-negative BC molecular subtype. High PUM1 expression correlated with poor outcomes, and high PUM1 expression was associated with a lower pathological complete response to anti-endocrine treatment but a high response to chemotherapy. Conclusions: These results indicate that PUM1 may serve as a potential prognostic and predictive biomarker in patients with invasive BC. PUM1 may serve as a therapeutic target in BC cases with unfavorable prognoses. However, further validation in larger, multi-center cohorts and further functional assessment are required to deepen our understanding of PUM1’s role in BC. Full article

This work presents a comprehensive study on the synthesis and application of Al₂O₃ fibers derived from an ammonium aluminum carbonate hydroxide (AACH) precursor. Through a hydrothermal route, the influence of critical synthesis parameters, including aluminum nitrate and urea concentrations, reaction temperature and time, and stirring conditions, on fiber morphology and aspect ratio was systematically investigated. The as-synthesized AACH fibers were subsequently converted into thermodynamically stable α-alumina fibers via controlled annealing. These high-aspect ratio alumina fibers were incorporated into polydimethylsiloxane (PDMS) to produce electrically insulating, thermally conductive composites. The thermal performance of fiber-filled composites was benchmarked against that of particle-filled counterparts, with the former exhibiting significantly enhanced thermal conductivity. Furthermore, the dielectrophoretic alignment of alumina fibers led to an additional increase in thermal conductivity, underlining the importance of high-aspect ratio fillers. This study uniquely combines the controlled synthesis of alumina fibers with their incorporation and alignment in a polymer matrix, presenting a novel and effective approach for engineering anisotropic, thermally conductive, and electrically insulating composite materials. Dielectrophoretic alignment of α-Al₂O₃ fibers synthesized through optimized hydrothermal conditions and incorporated into PDMS composites deliver over 95 % higher thermal conductivity than spherical fillers. Full article

Sustainability reporting has emerged as a pivotal tool for corporate accountability, integrating environmental, social, and economic performance into transparent disclosures that align with global frameworks such as the Global Reporting Initiative (GRI) Standards and the United Nations Sustainable Development Goals (SDGs). This study evaluates the environmental sustainability performance of Turkey’s automotive manufacturing sector by analyzing the extent and depth of GRI-based disclosures and their alignment with SDG targets. A mixed-method approach, combining quantitative Key Performance Indicator (KPI) coverage analysis with qualitative content assessment, was applied to sustainability reports from 12 major manufacturers. By identifying the most frequently reported indicators, assessing their coverage of economic, environmental, and social dimensions, and evaluating their direct relevance to specific SDGs, this research fills a critical gap and provides actionable insights for policymakers, industry leaders, and sustainability practitioners. The results indicate that while social indicators achieve the highest average disclosure rate (77.3%), environmental themes dominate narrative emphasis, reflecting sectoral materiality and regulatory pressures rather than proportional (KPI) coverage. Key gaps include underreporting of governance-related SDGs (e.g., SDG 5, SDG 8, SDG 16), limited target-level mapping, and a lack of measurable, outcome-based indicators. The study proposes a structured methodology for linking GRI metrics to SDG targets, enabling more consistent benchmarking and highlighting opportunities for balanced integration across all sustainability pillars. The findings contribute to both academic discourse and industry practice by demonstrating the need to bridge the gap between quantitative breadth and qualitative depth in sustainability reporting, ensuring more robust alignment with the 2030 Agenda. Full article

We synthesized the current evidence from the literature and conducted a 2 × 3 factorial experiment to quantify the impact of thermocycling on the Vickers microhardness (HV) of dental CAD/CAM materials: VITA ENAMIC (VE, polymer-infiltrated ceramic network) and CERASMART (CS, nanofilled resin-matrix). Sixty polished specimens (n = 10 per Material × Cycles cell; 12 × 2 × 2 mm) were thermocycled at 5–55 °C (0, 10,000, 20,000 cycles; 30 s dwell, ≈10 s transfer) and tested as HV0.3/10 (300 gf, 10 s; five indentations/specimen with standard spacing). Assumptions regarding the model residuals were met (Shapiro–Wilk W ≈ 0.98, p ≈ 0.36; Levene F(5,54) ≈ 1.12, p ≈ 0.36), so a two-way ANOVA (Type II) with Tukey’s HSD post hoc (α = 0.05) was applied. VE maintained consistently higher HV than CS at all cycle levels and showed a smaller drop from baseline: VE (mean ± SD): 200.2 ± 10.8 (0), 192.4 ± 13.9 (10,000), and 196.7 ± 9.3 (20,000); CS: 60.8 ± 6.1 (0), 53.4 ± 4.7 (10,000), and 62.1 ± 3.8 (20,000). ANOVA revealed significant main effects from the material (η²p = 0.972) and cycles (η²p = 0.316), plus a Material × Cycles interaction (η²p = 0.201). Results: Thermocycling produced material-dependent changes in microhardness. Relative to baseline, VE varied by −3.9% (10,000) and −1.7% (20,000), while CS varied by −12.2% (10,000) and +2.1% (20,000); from 10,000→20,000 cycles, microhardness recovered by +2.2% (VE) and +16.3% (CS). Pairwise comparisons were consistent with these trends (CS decreased at 10,000 vs. 0 and recovered at 20,000; VE only showed a modest change). Conclusions: Thermocycling effects were material-dependent, with smaller losses and better retention in VE (PICN) than in CS. These results align with the literature (resin-matrix/hybrids are more sensitive to thermal aging; polished finishes mitigate losses). While HV is only one facet of performance, the superior retention observed in PICN under thermal challenge suggests the improved preservation of superficial integrity; standardized reporting of aging parameters and integration with wear, fatigue, and adhesion outcomes are recommended to inform indications and longevity. Full article

The purpose of this study is to characterize two different 3D-printed materials, glass fiber-filled polypropylene (GF-PP) and calcium carbonate-filled polypropylene (CaCO₃-PP), which make it possible to obtain surgical bone models at a reasonable cost. The methodology involved selecting two filaments, among six, which showed better processability in the fused filament fabrication (FFF) process. Then, samples of the two selected materials were 3D printed, followed by characterization in terms of dimensional error, porosity, surface roughness, and mechanical strength. The results showed that both materials can be sterilized, with an increase in dimensional error and porosity after sterilization and slight changes in roughness and tensile strength. Additionally, anatomical models of mandible and femur bones were clinically validated by surgeons. Full article

The proper selection of bioactive root-end material is one of the main prognostic factors for the successful healing outcome of apical microsurgery (AMS). The aim of the present in vitro study was to evaluate and compare the marginal adaptability of a novel calcium silicate cement (CSC), Harvard MTA Universal, and Biodentine used as root-end filling materials. The endodontic treatment of 20 extracted human maxillary central incisors was performed. The apicoectomy was simulated, and root-end cavities were prepared ultrasonically using universal retrotips. Teeth were randomly assigned into two equal groups (n = 10) according to the retrofilling cement used: Group 1—Harvard MTA Universal and Group 2—Biodentine. The specimens were stored in relative humidity for 48 h and sectioned longitudinally. The data were processed and analyzed statistically. Harvard MTA exhibited a significantly lower mean gap width (1.16 ± 0.37 µm) than Biodentine (2.48 ± 0.38 µm) (p < 0.05), indicating a more intimate interfacial adaptation. Additionally, the phenomenon of material penetration into the dentinal tubules was observed only in the Harvard MTA group. Within the limitations of this in vitro study, Harvard MTA Universal demonstrated better interfacial properties than Biodentine when applied as a root-end filling material. This novel biomaterial could be regarded as a promising alternative for earlier calcium silicate cements in the context of AMS goals. Clinical relevance: The quality of marginal adaptation is a determinative feature for the clinical performance of CSCs and the long-term prognosis of AMS. Full article

This study investigates the structural behavior of composite double-web steel beams filled with different types of concrete made from a combination of recycled concrete aggregates and normal aggregates. The research includes both experimental and numerical analyses. Seven specimens were tested under symmetrical two-point loading, all having identical geometric properties: a span length of 1100 mm, flange plates 120 mm wide and 6 mm thick, and web plates 3 mm thick and 188 mm deep. The specimens were divided into two groups, with a control beam without concrete infill. Group one included beams filled with normal concrete in different locations (middle region, two sides, and fully filled), while group two mirrored the same fill locations but used recycled concrete instead. The experimental results showed that using normal concrete improved the ultimate load by 10.19% to 55.30%, with the fully filled beam achieving a maximum increase in ductility of about 568% and a stiffness improvement ranging from 2.6% to 39% compared to the control beam. Beams filled with recycled concrete showed increases in ultimate load from 9.52% to 42.03%, ductility improvements of up to 380%, and stiffness enhancements between 4.5% and 8.03%. Numerical modeling using ABAQUS (2021) showed excellent agreement with the experimental results, with differences in ultimate load and maximum deflection averaging 5.5% and 7.9%, respectively. Full article

Erosion wear is a major cause of surface degradation in metallic materials exposed to harsh marine environments. In this study, the erosion wear resistance of the 18Ni300 maraging steel repaired by underwater direct metal deposition (UDMD) is investigated. Results show that UDMD is successfully applied to repair the 18Ni300 samples in underwater environment. Full groove filling and sound metallurgical bonding without cracks are achieved, demonstrating its potential for underwater structural repair. Microstructural analyses reveal good forming quality with fine cellular structures and dense lath martensite in the deposited layer, attributed to rapid solidification under water cooling. Compared to in-air DMD, the UDMD sample exhibits higher surface microhardness due to increased dislocation density and microstructural refinement. Erosion wear behavior is evaluated at 30° and 90° impingement angles, showing that wear mechanisms shift from micro-cutting and plowing at 30° to indentation, crack propagation, and spallation at 90°. The UDMD samples demonstrate superior erosion wear resistance with lower mass loss, particularly at 30°, benefiting from surface work hardening and microstructural advantages. Progressive surface hardening occurs during erosion due to severe plastic deformation, reducing wear rates over time. The combination of refined microstructure, high dislocation density, and enhanced work hardening capability makes UDMD-repaired steel highly resistant to erosive degradation. These findings confirm that UDMD is a promising technique for repairing marine steel structures, offering enhanced durability and long-term performance in harsh offshore environments. Full article

Background: Late sternocutaneous fistulas (SCFs), secondary to chronic sternal osteomyelitis, are uncommon sequelae of median sternotomy and present significant therapeutic challenges. They are frequently linked to low-virulence microorganisms forming biofilms on retained foreign materials. While antibiotic-impregnated polymethylmethacrylate (PMMA) beads are established in managing chronic osteomyelitis in other anatomical locations, reports describing their use for post-sternotomy SCFs are limited to two early postoperative cases. Case Presentation: We describe a 62-year-old man with a history of triple-vessel coronary artery disease who underwent coronary artery bypass grafting via median sternotomy. Two months postoperatively, he developed an SCF in the upper sternum, initially treated with wire removal, negative pressure wound therapy, and intravenous vancomycin. Recurrence occurred one month later without systemic signs of infection. Imaging revealed inflammatory changes at the level of the manubriosternal junction. Definitive surgery included extensive sternal and costosternal debridement, bilateral anterior arthrolysis of the second ribs, and pulse lavage with 10 L of Microdacyn. The remaining defect was filled with vancomycin- and gentamicin-loaded PMMA beads. The patient had an uneventful recovery with no recurrence at six months. Conclusions: This case suggests that local antibiotic delivery via PMMA beads can be a valuable adjunct in the surgical management of recurrent, late-presenting SCFs after cardiac surgery. Full article

Wet–dry cycles are a key factor aggravating the durability degradation of foam concrete. To address this issue, this study prepared bentonite slurry–steel slag foam concrete (with steel slag and cement as main raw materials, and bentonite slurry as admixture) using the physical foaming method. Based on 7-day unconfined compressive strength tests with different mix proportions, the optimal mix proportion was determined as follows: mass ratio of bentonite to water 1:15, steel slag content 10%, and mass fraction of bentonite slurry 5%. Based on this optimal mix proportion, dry–wet cycle tests were carried out in both water and salt solution environments to systematically analyze the improvement effect of steel slag and bentonite slurry on the durability of foam concrete. The results show the following: steel slag can act as fine aggregate to play a skeleton role; after fully mixing with cement paste, it wraps the outer wall of foam, which not only reduces foam breakage but also inhibits the formation of large pores inside the specimen; bentonite slurry can densify the interface transition zone, improve the toughness of foam concrete, and inhibit the initiation and propagation of matrix cracks during the dry–wet cycle process; the composite addition of the two can significantly enhance the water erosion resistance and salt solution erosion resistance of foam concrete. The dry–wet cycle in the salt solution environment causes more severe erosion damage to foam concrete. The main reason is that, after chloride ions invade the cement matrix, they erode hydration products and generate expansive substances, thereby aggravating the matrix damage. Scanning Electron Microscopy (SEM) analysis shows that, whether in water environment or salt solution environment, the fractal dimension of foam concrete decreased slightly with an increasing number of wet–dry cycle times. Based on fractal theory, this study established a compressive strength–porosity prediction model and a dense concrete compressive strength–dry–wet cycle times prediction model, and both models were validated against experimental data from other researchers. The research results can provide technical support for the development of durable foam concrete in harsh environments and the high-value utilization of steel slag solid waste, and are applicable to civil engineering lightweight porous material application scenarios requiring resistance to dry–wet cycle erosion, such as wall bodies and subgrade filling. Full article