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Article Citation - WoS: 1Citation - Scopus: 1The Effect of Group Behavior on the Pull-Out Capacity of Model Soil Nails in High Plasticity Clay(Springer int Publ Ag, 2024) Akis, Ebru; Bakir, Bahadir Sadik; Yilmaz, Mustafa TolgaSoil nailing technique is widely used in stabilizing roadway and tunnel portal cut excavations. The key parameter in the design of soil nail systems is the pull-out capacity. The pull-out capacity of soil nails can be estimated either from the studies involving similar soil conditions or from the empirical formulas available in the literature. Particularly, it has been documented placing nails closer than a certain minimum distance results in a reduction in the pull-out resistance of a nail placed in sand. However, this requirement has not been discussed for the nail groups located within clay formations. In order to investigate the influence of nail spacing on the pull-out resistance of nails, a series of laboratory pull-out experiments were performed in clay of high plasticity. The results of these experiments showed a remarkable trend. Specifically, there was a significant reduction in the pull-out capacity of a nail when the spacing between nails two times the nail diameter (2 & Oslash;). In contrast, the pull-out capacity of a nail embedded in clay remained unaffected by neighboring nails, provided the spacing was maintained at six times the nail diameter (6 & Oslash;). In addition, during the conducted pull-out tests, it was observed that the failure mode of a single nail and 6 & Oslash; spaced group nails near the surface results as heaving around the single nail. However, in the case of closely positioned (2 & Oslash; spaced) nails, the affected area following nail failure exhibits distinct characteristics, which operate as a group. This leads to the occurrence of failure in the form of heaving around the group of nails.Article Citation - WoS: 2Citation - Scopus: 2Assessment of Tensile Properties of Cast High Mg Containing Al-Mg Aluminum Alloy With Correlation of Computed Tomography Scans and Optical Crack Surface Analysis(Springer int Publ Ag, 2023) Gul, K. Armagan; Dispinar, Derya; Kayali, E. Sabri; Aslan, OzgurIn the casting of aluminum alloys, melt cleanliness has been crucial to achieve desirable final properties. Alloying elements, casting method and degassing procedures have been applied to obtain an internal structure free from defects. Most common defects have been double oxide metal films called bifilms. These defects have been detrimental to mechanical properties. Efforts in industry and academia have focused on removing those defects. Reduced pressure test (RPT) and optical evaluation of cross section of specimens have been the most preferred method of bifilm index evaluation method to assess melt quality. As this method is 2D cross-section analysis, there has not been a direct method to correlate mechanical properties with 3D volume analysis of both RPT and tensile specimens. Computed tomography scanning/imaging has been a promising and emerging method for 3D internal structure evaluation to evaluate internal defects. Subsequent mechanical properties fluctuation in correlation with defect quantity and size may be built in this methodology. In the present study, casting of aluminum alloys with high magnesium content and different alloying elements has been done. Effect of melt quality and defect quantities on internal structures have been investigated via RPT tests and computed tomography scans (CTS). Correlation of CTS and tensile tests has been shown. Tensile test specimen surfaces have been investigated via optical imaging, and bifilm effects have been shown. Alloy quality correlations with tensile tests have been established.Article Citation - Scopus: 1A Critical Review on Multifunctional Building Envelope Materials for Simultaneous Mitigation of Urban Heat and Noise Islands(Springer int Publ Ag, 2025) Sarul, Meltem; Kocyigit, Filiz Bal; Yilmaz, CagriRethinking urban models requires resilient designs providing solutions to environmental problems at the building scale. Urban Heat Islands (UHI) and Urban Noise Islands (UNI) often coexist and significantly affect human health and comfort. This article aims to examine dual-function building envelope materials for reducing urban heat and noise islands using the literature review method. Dual-functional building envelope materials provide versatile benefits such as increasing energy efficiency, mitigating environmental challenges in densely populated areas, and improving individual and social health and comfort, in addition to their thermal and acoustic benefits. The use of these materials in building envelopes supports the climate adaptation of cities and provides resource efficiency.High albedo cool materials used for excessive heat reduction can be in the form of cool roofs or cool walls. High reflective materials, cool colored materials, retro-reflective materials, photoluminescent materials, thermochromic materials and sustainable materials are the most common among the cool material alternatives. The use of natural and local white colored gravel of various sizes on cool roofs is a low-cost and efficient approach to UHI reduction. Cool colored materials reflecting the near-infrared part of the solar spectrum bring a suitable solution for historical buildings where white color application is not appropriate. Highly reflective materials combat heat-related risks by reflecting incoming solar radiation directly back to their source due to their special content. Photoluminescent materials, which are still in the research phase, and thermochromic materials that change color when they reach a predetermined temperature are other solutions used to prevent heat-induced problems. Recycled or paraffin, biowaste oil added Phase Change Materials (PCM) also offer environmentally friendly, sustainable solutions for this case. In terms of UNI mitigating techniques, sound absorbing materials with high sound absorption coefficient and low density are widely preferred for building envelopes. Since high albedo materials generally have low sound absorption capacity, although reduction in heat- and noise-related threats is possible separately with the building envelope materials to be selected, multifunctional surface design diminishing both UHI and UNI effects simultaneously still involves various challenges. However, there are various strategies including applications of green walls and green roofs. Innovative approaches such as the use of PCM in pavements or the conversion of noise into green electricity using resonators or acoustic metamaterials also exist. While such solutions have not yet been widely found in practical applications, they are promising for the resilient smart cities of the future. Further experimental validation is needed to evaluate the long-term performance, cost-effectiveness and climate-specific applicability of multifunctional materials.HighlightsMulti functional building envelope materials that simultaneously address UHI and UNI offer great opportunities to create resilient future designs.Using cool materials in building envelopes mitigate UHI related risks.Using sound-absorbing materials in building envelopes mitigate UNI related risks.Innovative solutions such as phase-changing materials and converting harvested noise into electricity are great future opportunities.Article Citation - WoS: 1Citation - Scopus: 1Early Posterior Corneal Changes and Belin/Ambrosio Scores Following Photorefractive Keratectomy: a Pentacam Study(Springer int Publ Ag, 2025) Yakar, Konuralp; Alacamli, Goeksu; Ozgur, GoekhanIntroduction: To evaluate early postoperative changes in the posterior corneal surface, anterior chamber parameters, and Belin/Ambrosio Enhanced Ectasia Display (BAD) scores following photorefractive keratectomy (PRK) using Pentacam tomography. Methods: This observational study included 102 eyes of 51 patients (mean age 28.43 +/- 6.27 years) undergoing alcohol-assisted PRK for myopia and/or astigmatism. Preoperative and 1-month postoperative assessments were performed using the Pentacam system, measuring, anterior chamber depth (ACD), anterior chamber volume (ACV), central corneal thickness, posterior keratometry, posterior elevation, and BAD scores. PRK was conducted with a WaveLight (R) EX 500 excimer laser, followed by mitomycin-C application. Statistical analysis utilized paired t-tests and Pearson's correlation. Results: At 1 month post-PRK, ACV significantly decreased (p < 0.01), while ACD reduction was not significant (p = 0.40). Posterior keratometry (K1, K2, Kmean) and astigmatism decreased (p < 0.01), with a mean posterior elevation increase of -2.50 +/- 2.94 mu m (p < 0.01). A weak negative correlation was observed between maximum posterior elevation difference and ablation depth (p = 0.03, r = -0.20) and ablation depth/preoperative pachymetry ratio (p = 0.03, r = -0.20). BAD-D scores (Dp, Dt, Da, total D) significantly increased (p < 0.01), except for Df (p = 0.41). No correlation was found with preoperative pachymetry or residual stroma. Conclusions: PRK induces minimal posterior corneal protrusion and BAD score changes at 1 month, potentially mimicking early ectasia. Multimodal testing is advised for accurate ectasia detection. Larger, longer-term studies are needed to validate these findings.
