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Harnessing biopolymers for sustainable soil improvement in geotechnical engineering: A state-of-the-art review
No full textThis study comprehensively evaluates the principles of using biopolymers for soil improvement in geotechnical engineering and the current literature. First, biopolymers are defined and classified, and their potential as an environmentally friendly, sustainable alternative to traditional improvement materials is emphasized. The interaction mechanisms with fine and coarse-grained soils are explained in detail; the microscopic examination methods used to observe these mechanisms (e.g., SEM, FESEM, ESEM, FTIR, and XRD) are briefly discussed. According to laboratory studies, the mixing method, temperature, biopolymer concentration, curing time, and water content directly affect soil behavior. The literature reports that xanthan gum (XG), a particularly widely used additive, can increase the uniaxial compressive strength (UCS) of clay soils by approximately 400-600% and improve the elasticity modulus by up to 5 times under appropriate curing conditions. In addition, a decrease in permeability coefficient from 10(-4) to 10(-6) m/s (between 10 and 100 times) and a 60-80% reduction in compression and swelling indices have been achieved. In durability studies, it was determined that more than 60% of the initial strength was retained after 5-10 wet-dry or freeze-thaw cycles. While applicability in field conditions is discussed in numerical and physical modeling studies, data on field applications, long-term performance, and dynamic soil behavior are still limited. This situation highlights the need for interdisciplinary and holistic research to fully evaluate the potential of biopolymers in engineering applications.[GRAPHICS
A study of the impact of the relationship between fiscal space and credit default swaps on emerging and developing economies
No full textIn this study, the dynamic panel data method is used to analyse the impact of fiscal space on credit default swap (CDS) premiums in thirty-two emerging and developing countries between 2015 and 2022, with a particular focus on the effects of the COVID-19 pandemic and the expansionary fiscal policies implemented during this period. Unlike the existing literature, which predominantly focuses on developed countries, this study explores the relationship between fiscal space and credit default swaps (CDSs) in developing economies during the COVID-19 pandemic, offering a novel perspective on sovereign risk in emerging markets. The System-GMM method was used in the study. The analysis reveals a negative relationship between fiscal space and CDS premiums, with a 1 % increase in fiscal space yielding a modest 0.005 % decline, indicating a limited economic impact. In addition, it was found that increases in the unemployment rate, inflation rate, and trade deficit, which were included in the analysis as control variables, exerted upward pressure on CDS premiums. In contrast, improvements in government efficiency and increases in central bank reserves contributed to a decrease in these premiums. The analysis also reveals that the COVID-19 pandemic heightened investors' risk perceptions, thereby increasing CDSs. However, the expansionary fiscal policies adopted during this period did not produce any statistically significant additional upward effect on CDS premiums
A comprehensive review on fiber surface modifications and their impact on concrete properties
No full textOne of the methods for improving of the low tensile strength behavior of concrete is the use of fiber reinforcement. Fiber-based parameters are an important factor in determining the final properties of concrete mixes. One of the conditions affecting the fiber-matrix bond is the fiber-matrix interface interaction. To enhance this interaction, various surface modifications are applied to both synthetic and natural fibers. In this review study, fiber-based parameters affecting the properties of cementitious systems and surface modifications applied to fibers are mentioned. Surface modifications applied to the fiber surface were found to improve the fiber-matrix bond. It was found that this can improve the fresh, mechanical and durability properties of concrete mixes. However, it is also important to consider the environmental impacts of these surface modifications, as they can contribute to the overall sustainability and ecological footprint of the construction materials
Comparison of acute irisin and cognitive responses to different exercise modalities among late adolescents
No full textBackground/Objectives: Exercise supports physical and cognitive health through neurotrophin-mediated pathways, with irisin playing a key role in neuroprotection and synaptic plasticity. As adolescence represents a period of heightened neuroplasticity and metabolic adaptation, determining how different exercise modalities influence neurotrophic and cognitive responses is critical for health promotion in youth. This study aimed to compare the acute effects of low-intensity continuous training (LICT), short-interval high-intensity interval training (SI-HIIT), and long-interval HIIT (LI-HIIT) on circulating irisin levels and executive function in healthy late adolescent males. Methods: Eleven participants completed all conditions in a randomized crossover design with a 7-day washout. Venous blood samples and the Trail-Making Test, Parts A and B (TMT-A, TMT-B) were assessed pre- and postexercise, with continuous heart rate monitoring. Results: Post-exercise irisin levels were significantly greater in both HIIT protocols (SI-HIIT, p < 0.001; LI-HIIT, p < 0.038) than in the LICT protocol. Only the SI-HIIT group presented significantly shorter TMT-A (vs. LICT, p < 0.001; vs. LI-HIIT, p = 0.016) and TMT-B (vs. LICT, p < 0.001; vs. LI-HIIT, p < 0.001) completion times post-exercise. Conclusions: A single HIIT session elicited greater increases in circulating irisin and executive function compared with LICT. These findings highlight exercise intensity and interval structure as key factors for enhancing neurocognitive health, offering valuable insight for developing early-life training strategies to promote brain health
Intra-articular n-acetylcysteine reduces synovitis without preventing cartilage degeneration in experimental osteoarthritis
No full textBackground/Objectives: Osteoarthritis (OA) is a multifactorial degenerative joint disease characterized by synovial inflammation, oxidative stress, and progressive cartilage degeneration. This study investigated whether intra-articular N-acetylcysteine (NAC) attenuates synovial inflammation and oxidative stress and whether these effects translate into structural cartilage protection. Methods: OA was induced in rats by anterior cruciate ligament transection (ACLT). NAC (5 mg/50 mu L) was administered intra-articularly once weekly for three weeks post-ACLT. Inflammatory cytokines (IL-1 beta, IL-6, TNF-alpha), oxidative stress markers (iNOS, TAS, TOS, OSI), and cartilage degradation markers (MMP-13, COMP, CTX-II) were quantified in synovial fluid and cartilage homogenates using ELISA. Cartilage integrity was evaluated histologically using the modified Mankin scoring system. Results: Compared with controls, NAC significantly reduced synovial IL-1 beta, IL-6, TNF-alpha, MMP-13, and iNOS levels and improved the synovial redox profile by increasing TAS and reducing TOS and OSI (all p 0.05). Conclusions: Intra-articular NAC exerts potent anti-inflammatory and antioxidative effects within the synovial compartment but fails to prevent cartilage degeneration in the ACLT model. These findings indicate a compartment-specific therapeutic profile, suggesting that NAC may function as a symptom-modifying agent in synovitis-dominant OA rather than a structure-modifying therapy. Future studies should focus on optimized delivery systems or combination strategies targeting cartilage and subchondral bone to achieve disease modification
Optimal design of a robot gripper arm using the chaotic animated oat optimizer
No full textThis study presents a modified version of the Animated Oat Algorithm (AOA), enhanced through the integration of chaotic maps, termed the Chaotic Animated Oat Algorithm (CAOA). Inspired by the seed dispersal mechanisms of the oat plant, AOA offers a population-based metaheuristic framework suitable for complex global optimization tasks. The proposed CAOA was evaluated across four real-world engineering optimization problems: pressure vessel design, bolted rim coupling, gear train cost minimization, and robot gripper arm weight reduction. Results demonstrate that CAOA consistently outperforms traditional and state-of-the-art metaheuristics in terms of solution quality, convergence stability, and robustness, affirming its potential for widespread engineering applications
Does composite repair time affect repair protocol, immediate or delayed?
No full textBackground Composite resin restorations frequently require repair due to fractures, marginal defects, or esthetic failures. The effectiveness of composite repair depends heavily on the surface treatment applied prior to bonding. This study aimed to evaluate the effects of various surface treatment protocols on the shear bond strength(SBS) between composite resin layers in same-visit immediate repair(IR) and delayed repair (DR) conditions, using bulk-fill and nanohybrid composite resins. Methods Two types of composite resin materials-NeoSpectra ST HV (nanohybrid) and Tetric N-Ceram Bulk-Fill-were tested. A total of ten surface treatment protocols were evaluated under both immediate and delayed repair conditions (n = 10 per subgroup). Following grinding with a diamond bur, the surfaces were treated with one of the following: phosphoric acid, universal adhesives (Single Bond Universal, Prime&Bond Universal), three application modes of Clearfil SE Bond (two-step, bond only without primer, or phosphoric acid application followed by bond only), Optibond FL without primer, or GC Modeling Liquid. Additionally, direct layering without any surface treatment was included as a control. SBS was measured using a universal testing machine, and failure modes were analyzed using a stereomicroscope. One-way analysis of variance and Tukey's post hoc test were used for statistical analysis (p = 0.05). Results IR groups showed significantly higher SBS than DR groups across both composite types. The highest SBS were observed with GC Modeling Liquid and hydrophobic bonding agents, particularly in the bulk-fill immediate repair groups. Phosphoric acid application alone, or in combination with self-etch adhesive, did not improve bond strength. Universal adhesives did not outperform hydrophobic agents in any condition. Direct layering without treatment resulted in the lowest bond strength, especially in delayed repair. Conclusions Surface treatment protocol significantly affects the success of composite resin repair. Hydrophobic adhesives and GC Modeling Liquid proved to be the most effective options, especially for same-visit immediate repairs. Simplified approaches avoiding unnecessary etching or priming may offer clinically efficient solutions without compromising bond strength
Eco-friendly and sustainable one-component polyurethane syntactic foams reinforced with fly ash cenospheres for acoustic and thermal insulation
No full textIn this study, syntactic composite foams were developed by incorporating cenosphere (CS) particles recovered from recycled fly ash into a one-component polyurethane (PU) foam system. During production, CS was added to the spray-applied PU foam at specific ratios, and the foaming reaction was simultaneously initiated via manual mixing. This approach minimized particle settling caused by the filler-matrix density difference and promoted a more homogeneous structure. Two types of CS, with mean sizes of approximately 70 mu m and 130 mu m, were incorporated at five loadings ranging from 5 wt% to 15 wt%. The resulting composites were evaluated for their acoustic, mechanical, and thermal performance. Thermal analyses revealed that CS addition increased the glass-transition temperature (Tg) by approximate to 12 degrees C and delayed the 5% mass-loss temperature (T5%) by approximate to 30-35 degrees C compared with the neat N2 foam, confirming the stabilizing role of cenospheres. The refoaming process with manual mixing promoted finer cell diameters and thicker walls, enhancing the sound absorption coefficient (alpha), particularly at medium and high frequencies. Moreover, increasing the filler content improved both the sound transmission loss (STL) and compressive strength, alongside density, although further gains in alpha and STL were limited beyond a 10 wt% filler content. Significant enhancements in compressive strength were achieved at filler ratios above 12.5 wt%. Unlike conventional two-component PU foams, this study demonstrates a sustainable one-component PU system reinforced with recycled cenospheres that simultaneously achieves acoustic, mechanical, and thermal multifunctionality. To the best of our knowledge, this is the first report on incorporating recycled cenospheres into a one-component PU foam system, overcoming dispersion challenges of conventional two-component formulations and presenting an environmentally responsible route for developing versatile insulation materials
A rare case of conjunctival hibernoma in a von hippel-lindau (vhl) patient: Possible association?
No full textPurpose Ocular involvement is exceedingly uncommon, and to date, no conjunctival hibernoma has been reported in humans. We present the first such case in a patient with von Hippel-Lindau (VHL) syndrome.Case report A 32-year-old woman with genetically confirmed type 1 VHL disease presented with a long-standing, progressively enlarging, painless subconjunctival mass in her only functional eye. Systemic history included multiple cerebellar hemangioblastomas, bilateral nephrectomy for renal cell carcinoma, and an endolymphatic sac tumor. Ophthalmic examination revealed a firm, elevated, subepithelial nodular lesion on the bulbar conjunctiva of the left eye, partially prolapsing beyond the palpebral fissure. The lesion was non-tender, non-ulcerated, and showed no surface inflammation. The eye had phthisis bulbi and residual retinal hemangioblastoma. Orbital magnetic resonance imaging demonstrated a 1.2 x 0.9 x 0.7 cm homogeneous, well-circumscribed lesion, hyperintense on T2-weighted fat-suppressed images, confined to the conjunctiva without scleral, orbital, or bony involvement. Surgical excision revealed a cream-gray, lobulated mass composed of multivacuolated eosinophilic cells with granular cytoplasm. Immunohistochemistry showed strong S-100 positivity and low Ki-67, consistent with hibernoma. Despite a positive deep margin, the patient declined further surgery; no recurrence was observed at three months.Conclusion This is the first documented case of conjunctival hibernoma in humans and the second reported association with VHL. Conjunctival hibernoma should be considered in the differential diagnosis of vascular conjunctival lesions, particularly in patients with VHL
When shared humanity is anchored in identity centrality: Self-categorizations and identity motives in alevis as a minority
No full textFor some minorities, living under constant threat for an extended period requires a solution. It is evident that long-oppressed minorities often possess belief systems rooted in an inclusive notion of humanity. This study examines whether shared humanity serves as public discourse material for an ethno-religious minority group like Alevis, who have suffered collective victimhood for centuries, to prove that they share the same "symbolic universe of values" with the majority, or whether it genuinely occupies a central place in their identity driven by specific motivations. It explores which motivational principles (self-esteem, belonging, meaning, continuity, and efficacy) are active at superordinate, social, and interpersonal levels of self-categorization, based on perceived centrality. Conducted with 142Alevi participants, the study involved expressing 8 identity elements each in response to the question "Who are you?" and rating their perceived centrality and motivational levels. The findings showed that 9.6% of the identity elements are at the superordinate abstraction level of self-categorization. Hierarchical regression analyses revealed that the motivational background of the identity process was not limited to self-esteem, supporting the tenets of Motivated Identity Construction Theory, and demonstrated that the role of motivational principles can vary in relation to levels of self-categorization. Among participants who referred to shared humanity at least once in their identity repertoire, the motives of "meaning" and "continuity" positively predicted the perceived identity centrality. Findings are discussed in relation to social psychological perspectives and Alevism studies literature