Aperta Turkish Open Archive
Not a member yet
83692 research outputs found
Sort by
Hydrodynamic Cavitation-Induced Thrombolysis on a Clot-on-a-Chip Platform
No full text<p>Complications from thrombosis constitute a massive global burden for human health. Current treatment methods have limitations and can cause serious adverse effects. Hydrodynamic cavitation (HC) is a physical phenomenon where bubbles develop and collapse rapidly within a moving liquid due to sudden pressure changes. These collapsing bubbles provide high targeted energy which can be used in a controlled environment with the help of microfluidic devices. This study introduces a new clot-on-a-chip (CoC) platform based on HC, evaluated for thrombolysis efficacy. The microfluidic device, paired with a polydimethylsiloxane (PDMS) microchip, generates cavitation bubbles at low upstream pressures (<= 482 kPa), enabling microscale blood clot erosion. Different HC exposure conditions (varying pressure and duration) are assessed by changes in clot mass, diameter, and scanning electron microscopy (SEM). The largest mass reduction occurs at 482 kPa for 120 s, with a decrease of 6.1 +/- 0.12 mg, while the most erosion in diameter of blood clots is obtained 482 kPa for 120 s with complete removal. SEM results show increasing damage to clot structure from less to more intense HC exposures. The CoC platform, at controlled pressures and durations, efficiently disrupts clot structure and offers a promising drug-free alternative for thrombolysis treatment.</p>
<p>A new clot-on-a-chip platform leverages microfluidic devices to control hydrodynamic cavitation (HC) for targeted blood clot erosion. Reduction on clot mass and diameter and scanning electron microscopy analysis confirm progressive clot erosion with increasing HC intensity. By generating cavitation bubbles at low upstream pressures (<= 482 kPa), this method provides a promising drug-free alternative for thrombolysis.image (c) 2024 WILEY-VCH GmbH</p>
Novel 4-((3-fluorobenzyl)oxy)benzohydrazide derivatives as promising anti-prostate cancer agents: Synthesis, characterization and in vitro & in silico biological activity studies
No full text<p>In this study, ten novel halogenated arylidenehydrazide derivatives were synthesized and characterized through 1H, 13C APT, 19F NMR, HSQC, HMBC, HRMS, and FT-IR techniques. Cytotoxic evaluations against PC3 prostate cancer and HUVEC cell lines identified compounds 8 and 14 as lead candidates, achieving IC50 values of 4.49 mu M and 4.78 mu M, respectively, with notable selectivity indexes of 12.15 and 11.78, underscoring their specificity against PC3 cells. Molecular docking studies targeting AR, VEGFR1, EGFR, and VEGFR2 suggested potential inhibitory mechanisms, with compounds 8 and 14 displaying substantial binding affinities for AR and VEGFR1. Compound 8 achieved IFD scores of -12.900 kcal/mol for AR and -10.895 kcal/mol for VEGFR1, while compound 14 recorded scores of -10.323 kcal/mol and -10.379 kcal/mol, respectively. Complementary MM-GBSA analyses revealed favorable binding energies, with compound 8 yielding Delta G values of -76.60 kcal/mol (AR) and -78.08 kcal/mol (VEGFR1) and compound 14 showing -80.67 kcal/mol (AR) and -78.61 kcal/mol (VEGFR1). MD simulations confirmed complex stability over 50 ns, indicating that compound 14 exhibited enhanced binding stability with key residues in AR and VEGFR1. ADME predictions highlighted drug-like properties, particularly for compounds 8 and 14, with high lipophilicity and favorable absorption characteristics, despite low aqueous solubility. SAR analysis emphasized the beneficial impact of halogen substitutions on potency and selectivity, establishing compounds 8 and 14 as promising candidates for further therapeutic development.</p>
Thermopower energy waves propagation in novel generation carbon fibers/ fuel composite
No full text<p>The development of technological devices and their increasing use provide various conveniences. However, it's necessary to develop appropriate energy sources to sustain their use. A novel method has been developed for the generation of electrical energy, which differs from conventional techniques in that it relies on the propagation of thermopower waves generated by the exothermic reaction of fuels on a conductive core material. In this study, electrical energy was generated by the interaction of thermal waves with copper-coated carbon fiber core structures. Copper nanoparticles were produced via electrolysis and subsequently coated on the carbon fiber surface. X-ray diffraction (XRD) analysis demonstrated that the electrolysis process resulted in the formation of copper (Cu) and copper (I) oxide (Cu2O) crystal structures. Scanning electron microscope (SEM) analysis revealed the presence of Cu- Cu2O nanostructures on the carbon fiber (CF) surface. Furthermore, Raman analysis revealed that the D and G bands of CF were disappeared as a consequence of the Cu- Cu2O coating. In the thermopower wave measurements, picric acid-sodium azide fuel was added to the 4 cm Cu- Cu2O coated CF surface, resulting in the generation of 30.24 mV energy upon fuel ignition. Meanwhile, it was observed that the temperature reached 844 degrees C instantaneously. A consequence of modifying the length of the Cu- Cu2O coated CF was the observation of a sevenfold change in voltage. The results obtained are of great significance in terms of advancing our understanding of energy extraction from thermal power waves.</p>
In-situ acoustic emission based technique for damage detection and identification and failure mode prediction in scarf repaired composite structures
No full text<p>One of the great challenges facing adhesively bonded repair procedures in the industry is the absence of a reliable structural health monitoring technique to ensure that the repaired region is intact during service. To this end, this paper proposes a novel in-situ acoustic emission-based methodology to detect and identify damages as well as to predict failure modes at early stages. In this essence, two tapered-scarf repaired plates are produced with different patch materials. The first patch consists of neat carbon fiber prepregs whereas in the second thermally exfoliated graphene oxide integrated carbon fiber prepregs are utilized. Testing the constituents of the repair system individually while monitoring their acoustic activity makes it possible to separate each damage type precisely. Hence, when the specimens of the repaired panel are tested, very detailed information is revealed regarding the current structural status of the specimen and probable failure scenarios. The effectiveness and robustness of the proposed methodology in detecting and identifying damages of varying severity in addition to predicting the failure scenario are verified in the composite panels repaired with pristine and graphene integrated patches.</p>
Synthesis and characterization of YBCO superconducting thin films doped with BaHfO3 via the TFA-MOD technique for potential aerospace applications
No full text<p>The study aims to improve the critical current density (Jc) and flux pinning of YBa2Cu3O7-delta (YBCO) high- temperature superconducting films. The decline in J c at high temperatures and magnetic fields is due to intrinsic crystalline anisotropy, thermal fluctuations, and lack of effective pinning centers. To tackle this, the study uses a novel approach by incorporating BaHfO3 (BHO) nanostructures (dots, rods, or particles) as artificial pinning centers in YBCO films. The objective is to augment critical current density and enhance flux pinning properties using trifluoroacetates metal organic deposition method (TFA-MOD) on SrTiO3 (STO) substrates, with a specific focus on applications in the aerospace industry. Characterization of YBCO solutions involves measuring contact angle, viscosity, and modulus. Thermal, structural, microstructural and superconducting properties of the films were scrutinized by Differential Thermal Analysis-Thermogravimetry (DTA-TG), Fourier Transform Infrared (FTIR), X-ray diffractometry (XRD), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) and Atomic Force Microscopy (AFM), Surface Profilometer (SP) and Physical Property Measurement System (PPMS). Rheological tests show viscosity decreases with temperature before stabilizing. Undoped YBCO exhibits good wetting on STO substrates. Heat treatment involves organic solvent removal and TFA decomposition, with FTIR and XRD analyses confirming decomposition of acetate complexes and strong c-axis texture. XPS results indicate consistent chemical compositions, while surface morphologies are flat and crack-free, with denser structures in BHO-doped films. Doping improves superconductivity up to a certain concentration, after which it decreases. Average film thickness is around 240 nm. Undoped YBCO films exhibit poor superconducting properties due to secondary phases, while BHO doping influences superconductivity, with an increase in critical current density up to a certain concentration, beyond which superconductivity is lost.</p>
Cybersecurity-aware log management system for critical water infrastructures
No full text<p>Cyber threats are increasingly targeting critical water infrastructures, requiring robust cybersecurity measures to ensure the continuous and safe delivery of water services. This paper presents a comprehensive, cybersecurity-aware log management system specifically designed for critical water infrastructures. The system leverages advanced data collection, analysis, and real-time monitoring to effectively detect and mitigate cyber threats. Key features include integration with existing infrastructure, scalability to handle large volumes of log data, and machine learning algorithms for enhanced threat detection and response. Our solution demonstrated significant improvements in threat detection accuracy, response times, and overall system resilience through rigorous testing in real-world scenarios. This paper discusses the design, implementation, and performance evaluation of the proposed log management system, highlighting its potential to strengthen the cybersecurity posture of critical water infrastructures.</p>
Investigation of the hydrogen-enriched methane combustion in a domestic boiler with porous burner on emissions and performance
No full text<p>Hydrogen is considered one of the most promising renewable fuel alternatives for decarbonizing the gas sector. The transition from fossil fuels to carbon-free alternatives is essential for achieving full carbon neutrality. Rather than a direct shift from natural gas systems to pure hydrogen, a gradual integration of hydrogen into the existing natural gas supply offers a more feasible transition pathway. In this study, the effects of utilizing a 20 % hydrogen-enriched methane mixture in a condensing boiler with a porous burner, commonly used for heating in residential and commercial applications, were investigated. Emission values for NOx, O2, CO2, and CO were obtained from experimental studies conducted at two different fan speeds. The experimental results revealed that the condensing boiler, originally designed to operate on 100 % methane, exhibited an approximate 5 % reduction in thermal power when operated with a fuel mixture of 20 % hydrogen and 80 % methane. Notably, a reduction in flue gas emissions was observed. At maximum thermal power, CO2 concentrations in the flue gas decreased from 9.3 % to 8.3 %, CO levels dropped from 71 ppm to 42 ppm, and NOx emissions reduced from 19 mg/kWh to 12 mg/kWh. Additionally, three-dimensional CFD simulations were conducted by using the AramcoMech 2.0 mechanism, which includes 25 species and 105 reactions, to further analyze the boiler's performance. A numerical comparison was conducted between the 100 % methane and the 20 % hydrogen-enriched methane fuel inputs. The porous burner was modeled using a porous media approach within the numerical framework. The numerical results were validated against experimental data, confirming the reliability of the simulations. These findings underscore the potential of hydrogen-enriched methane as a viable and environmentally friendly alternative fuel for condensing boilers equipped with porous burners.</p>
Functional biscuits with alternative protein sources
No full text<p>Functional biscuits have emerged as innovative vehicles for enhancing nutritional benefits beyond traditional energy sources. This review synthesizes recent literature on alternative protein sources for functional biscuit fortification, focusing on microalgae, legumes, insects, and dairy substitutes. Arthrospira platensis (Spirulina sp.) is highlighted for its high protein content (55–70% dry weight), comprehensive essential amino acid profile, and a rich array of bioactive compounds confer antioxidant and anti-inflammatory properties. This paper critically evaluates the nutritional composition, bioavailability, and technological implications of integrating these alternative proteins into biscuit formulations. Furthermore, it addresses sensory modifications, consumer acceptance, and regulatory considerations essential for commercial viability. Sustainability and economic feasibility are also discussed, emphasizing the role of these protein sources in promoting a circular economy and reducing environmental impact. The review concludes by identifying gaps in current research and proposing directions for future studies aimed at optimizing formulation strategies and elucidating long-term health outcomes associated with protein-enriched functional biscuits.</p>
TÜRKİYE İÇİN OPTİMUM AÇIK DENİZ ÜZERİ KOMBİNE RÜZGAR VE MAVİ ENERJİ SANTRALİ GELİŞTİRİLMESİ
No full text<p>Türkiye üç yanı denizlerle çevrili Mavi Vatan doktrini ile 462 000 km2 deniz alanına sahip bir ülkedir. Bu kapsamda Türkiye’nin deniz saha planlamasını gerçekleştirerek söz konusu bu alandan en verimli şekilde faydalanması gerekmektedir. Çalışma dahilinde, Deniz Saha Planlamasına (DSP) yönelik öncü bir ÇKKV (Çok Kriterli Karar Verme) modeli geliştirilmiştir. Model kapsamında DSP kullanımı, çevresel etki ve ekolojik – biyolojik çeşitlilik altında üç ana kriter belirlenerek hem sürdürülebilirlik hem de fayda sağlama ilkeleri göz önünde bulundurulmuştur. Alt kriterler belirlenen dağılımlarla Monte Carlo Simülasyonu (MCS) ile modellenerek bir Stratejik Planlama Modeli (SPM) ortaya konmuştur. Mavi enerji, gelgit, dalga ve açık deniz rüzgarı gibi deniz ve hidrokinetik bazlı enerji kaynaklarını ifade eder ve Türkiye’nin doğal gaz ve petrol gibi dışa bağımlı birincil enerji kaynaklarına olan bağımlılığını azaltarak, ulusal enerji karışımındaki yerli enerji kaynaklarının çeşitliliğini artırmak için önemli bir fırsat sunar. Türkiye’nin açık deniz mavi enerji kapasitesinin araştırılması, enerji politikası hedefleriyle uyum sağlamak açısından kritik bir öneme sahiptir. Özellikle Yenilenebilir Enerji Kaynak Alanı Kapsamında (YEKA) aday bölgelerden biri olan Karadeniz’deki Kıyıköy kıyıları, açık deniz mavi enerji geliştirme için elverişli alanlar arasında yer almakta olup, ülkenin açık deniz mavi enerji potansiyelinin yaklaşık 1700 MW olduğu tahmin edilmektedir. Rüzgar, dalga ve hidrokinetik türbinlerinin birleştirildiği hibrit tasarım modeli, DSP aracılığıyla yeni projeler için altyapı sağlayarak sürdürülebilir bir mavi ekonomi oluşturulmasına katkı sunmayı amaçlamıştır. Açık Deniz Üzeri Kombine Rüzgar ve Mavi Enerji Santrali için tezde geliştirilen hibrit tasarım modelinin temel deformasyon analizinde basitleştirilmiş üçlü yay yöntemine MCS analizi uygulanarak literatürde API (2014) ve DNV (2014) tarafından önerilen p – y yöntemleriyle Bryne ve diğ. (2015) tarafından önerilen 3 boyutlu sonlu elemanlar modelini kapsayıcı bir çözüm yolu ortaya konmuştur. Kombine hibrid sistemin en önemli tasarım kriterlerinden biri olan yapının doğal frekans analizinde ise hibrit sistem literatürde verilenin aksine birinci dereceden serbestliğe değil ikinci dereceden serbestliğe göre çözülmüştür. Öncelikle, geliştirilen bu yeni çözüm literatürle kıyaslanmış ve mutlak bağıl fark %1,84 bulunarak çözüm metodolojisi gerçekleniştir. Bunun yanında, yeni hibrit yapının doğal frekans değeri birinci dereceden serbestliğe ve ikinci dereceden serbestliğe göre ayrı ayrı çözülerek, aradaki mutlak bağıl farkın %48,64 gibi yadsınamaz bir fark olduğu görülmüştür. Çalışmanın son kısmında ise fizibilite çalışması yapılarak elektrik maliyetinin düzeylendirilmiş değeri (LCOE) 52,90 Eur/MWh olarak elde edilmiştir. Sonuç olarak bu tezde, sistemin sürdürülebilirliği, fizibilitesi ve operasyonel ömrü açısından Karadeniz koşullarında özgün bir mavi enerji tasarım modeli geliştirilmiştir. Hibrit sistemlerin tek dereceli çözümlerinin hatalı olacağı, iki dereceli serbestliğe göre çözümlerin yapılması gerektiği literatürde ilk defa ortaya konmuştur. Toplamda kombine sistemin üreteceği elektrik miktarı 1,68 MW saat olarak bulunmuştur. Dalga enerji üreteci için B/C fizibilite değeri 2,17 deniz üzeri rüzgar türbini için ise 1,39 bulunmuştur. Bu sistemlerin kombine kullanılması ile de bu değer B/C=1,40 olarak hesaplanmıştır. Görüldüğü üzere tezde Türkiye’ye özgü geliştirilen yerli ve milli kombine mavi enerji santrali aynı zamanda verimli ve ekonomik açıdan yapılabilirdir. Bu yapıların tasarımı için de çift dereceli serbestliğe dayalı yeni bir tasarım modeli geliştirilmiştir.</p>
Atıksu Arıtma Tesislerinin Performans Değerlendirmesi ve Hidrolik Modellemesinde İstatistiksel ve Yapay Zekâ Tabanlı Yaklaşımlar
No full text<p>Su kaynaklarının korunması ve atıksu arıtma tesislerinin sürdürülebilir işletimi, hidrolik ve biyolojik süreçlerin karmaşıklığı nedeniyle ileri modelleme tekniklerine ihtiyaç duymaktadır. Bu çalışma, atıksu yönetiminde kullanılan deneysel analizler ile veri odaklı yapay zekâ yaklaşımlarını sentezleyerek, tesis performansının ve çevresel etkilerin değerlendirilmesindeki güncel metodolojileri ortaya koymaktadır. Arıtılmış atıksuların tarımsal sulamada yeniden kullanımı, toprak gözenekliliğini ve doymuş hidrolik iletkenliği değiştirerek drenaj ve yüzey akış dinamiklerini etkileyebilmektedir. Tesis içi süreçlerin izlenmesinde ise Temel Bileşen Analizi gibi çok değişkenli istatistiksel yöntemler, büyük ve karmaşık veri setlerini basitleştirerek mevsimsel yük değişimlerini ve arıtma verimliliğini karakterize etmede kritik rol oynamaktadır. Çalışma ayrıca, giriş debisi ve çıkış suyu kalitesinin tahmin edilmesinde yapay zekâ algoritmalarının etkinliğini vurgulamaktadır. Destek vektör makineleri ve genetik algoritma destekli hibrit modellerin, klasik mekanistik modellere kıyasla debi dalgalanmalarını ve şok yüklemeleri daha yüksek doğrulukla tahmin ettiği görülmüştür. Bununla birlikte, faktör analizi ile entegre edilen makine öğrenmesi modelleri, veri gürültüsünü minimize ederek toplam azot gibi hassas parametrelerin gerçek zamanlı tahminini iyileştirmektedir. Sonuç olarak, hidroloji ve hidrolik prensiplerin büyük veri analitiği ve yapay zekâ teknolojileri ile entegrasyonu; arıtma tesislerinin operasyonel güvenilirliğini artırmak, enerji maliyetlerini optimize etmek ve alıcı ortam kalitesini korumak için önemli bir yaklaşım olarak öne çıkmaktadır.</p>