IYTE GCRIS Database (Izmir Institute of Technology)
Not a member yet
11968 research outputs found
Sort by
Pressureless Synthesis and Consolidation of the Entropy-Stabilized (hfsub>0.25/Sub>zrsub>0.25 Composite by Ultra-Fast High-Temperature Sintering (uhs)
No full textEntropy-stabilized Ultra High-Temperature Ceramics (UHTC) offer a groundbreaking solution to the challenges of extreme environments, showcasing enhanced mechanical properties, thermal stability, and resistance to oxidation at high temperatures. The consolidation of UHTC by ultra-fast high-temperature sintering (UHS) significantly reduces processing times and temperature and can produce dense high-performance ceramics with superior mechanical properties. This study reports the pressureless synthesis and consolidation of the entropy-stabilized (Hf0.25Zr0.25Ti0.25V0.25)B-2-B4C composite through UHS within 1 minute, starting from transition metal diboride powders. B4C acts as an effective sintering aid, promoting the densification of the system and the formation of a nearly single-phase hexagonal diboride with a diboride-eutectic phase. Furthermore, a secondary minor hexagonal phase rich in V and Zr is formed close to the eutectic regions. Sintering currents of 40 A were necessary to reach densities higher than 90 % under pressureless conditions, achieving nano hardness higher than 27.3 GPa, comparable with high-entropy diborides produced by Spark Plasma Sintering. The study highlights the entropy-stabilized phase formation, diffusion, densification, and grain growth mechanisms involved during UHS. The work contributes to the understanding of entropy-stabilized ceramics produced by UHS as a faster and less energy-consuming process than conventional sintering methods
Climate Neutrality in Local Municipalities' Action Plans: İzmir Case
No full textBu tez, yerel belediyelerin eylem planlarına iklim nötrlüğünün entegrasyonunu inceleyerek, bu planlar ile literatürde iklim nötrlüğü elde etmek için önerilen eylemler arasındaki ilişkiye odaklanmaktadır. Yerel belediyelerin iklim nötrlüğüne bağlılığı ve eylemlerinin etkinliği konusundaki belirsizliği ele alarak, çalışma, yerel düzeyde iklim nötrlüğü politikaları ve stratejilerinin etkinliğini artırmak için içgörüler sunmayı amaçlamaktadır. Kapsamlı bir literatür taraması ve Türkiye'de İzmir Büyükşehir Belediyesi'ne odaklanan bir durum çalışması yaklaşımıyla, araştırma yerel eylem planlarını değerlendirmek için bir kontrol listesi geliştirmiştir, özellikle azaltma ve uyum önlemlerine odaklanmıştır. Bu kontrol listesi kullanılarak, İzmir Sürdürülebilir Enerji ve İklim Eylem Planı (SECAP) ile Yeşil Şehir Eylem Planı (GCAP)'nın iklim nötrlüğü prensipleriyle uyumunu değerlendirir. Değerlendirme yöntemi, her planın iklim nötrlüğü kriterlerine ilişkin belirli eylemlerin varlığı veya yokluğuna dayalı olarak puanlanmasıyla ilgilidir, bu da planların literatürdeki iklim nötrlüğü eylemleriyle ilişkisinin hem nicel bulgularını hem de nitel içgörülerini sunar. Bu araştırma, yerel belediyelerin iklim değişikliğiyle mücadele çabalarında iklim nötrlüğünü nasıl önceliklendirdiğini anlamamıza katkıda bulunur ve yerel politikaların ve eylemlerin iklim nötrlüğü prensiplerini daha iyi entegre etmek için öneriler sunar.This thesis investigates the integration of climate neutrality within the action plans of local municipalities, focusing on the relationship between these plans and the actions proposed to achieve climate neutrality in the literature. Addressing the uncertainty surrounding the commitment of local municipalities to climate neutrality and the effectiveness of their actions, the study aims to provide insights for enhancing the efficacy of policies and strategies for climate neutrality at the local level. Through a comprehensive literature review and a case study approach focusing on İzmir Metropolitan Municipality in Turkey, the research develops a checklist for evaluating local action plans, with a particular emphasis on mitigation and adaptation measures. Utilizing this checklist, the study assesses the alignment of the İzmir Sustainable Energy and Climate Action Plan (SECAP) and the Green City Action Plan (GCAP) with climate neutrality principles. The evaluation methodology involves scoring each plan based on the presence or absence of specific actions related to climate neutrality criteria, providing both quantitative findings and qualitative insights into the plans' relationship with climate neutrality actions in the literature. This research contributes to understanding how local municipalities prioritize climate neutrality in their efforts to address climate change and offers recommendations for improving the integration of climate neutrality principles into local policies and action
Bond-Based Peridynamic Fatigue Analysis of Ductile Materials With Neuber's Plasticity Correction
No full textThis study introduces an approach for performing bond-based (BB) peridynamic (PD) fatigue analysis of ductile materials. Existing BB PD fatigue models do not account for the effect of plastic deformation. The current approach addresses this by incorporating Neuber's plasticity correction concept into the fatigue model. Neuber's correction adjusts the stress and strain predictions of the PD elastic solution to account for local plastic deformation around crack tips. The PD fatigue simulations demonstrate the effectiveness of this method and improvements in fatigue life predictions by considering local plasticity effects. The numerical results first examine the response of a ductile plate without a crack under quasi-static monotonic loading. Subsequently, specimens exhibiting Mode I and mixed-mode crack propagation paths due to cyclic loading are analyzed. The PD predictions accurately capture the test data. Additionally, the model specifically investigates the effect of a stop hole on fatigue life
Investigating the Adhesion Problem of a Double-Sided Tape and Car Bumper Packing Materials
No full textPressure-sensitive adhesives (PSAs) are viscoelastic materials with permanent stickiness, and can adhere strongly to solid surfaces upon application of slight contact pressure under a relatively short contact time. The adhesion problem of double-sided adhesive to packing films of car bumpers was investigated by analyzing the flexible adhesive layer and two alternative packing films. The films were blue in color and one of them was opaque and the other one was transparent. Scanning electron microscopy (SEM), Fourier transfer infrared (FTIR) spectroscopy were used to characterize the samples. Water contact angle and roughness of surfaces were also determined. It was shown that the film with high surface roughness and high water contact angle adhered better to the flexible adhesive layer. © 2025 by Apple Academic Press, Inc
Machine-learning-assisted de novo design of molybdenum disulfide binding peptides
No full textKısa amino asit zincirleri, peptitler, biyolojik süreçler ve yüksek teknoloji uygulamaları için vazgeçilmez moleküllerdir. Geniş kullanım alanları arasında, moleküler tanıma özelliği ile bio-nano arayüzler oluşturmak ilgi toplayan bir araştırma konusu olmuştur. Yapılan çalışmalar sonucunda yönlendirilmiş evrim metodolojileri oluşturulmuş ve çeşitli hedeflere -enzim, antijen veya inorganik yapılar- bağlanan fonksiyonel peptit tanısı mümkün hale gelmiştir fakat bu geleneksel yaklaşım ölçeklenebilirlik ve sekans uzayındaki ilişkilerin anlaşılması konusunda zayıflıklar taşımaktadır. Bu zafiyetler, yüksek çıktılı sekanslama ve hesaplama verimlerinin artması ile beraber derin yönlendirilmiş evrim gibi daha güçlü teknolojilerinin geliştirilmesini motive etmiştir. Bu yöntemle üretilen büyük veri setleri, sekans-fonksiyon ilişkilerinin makine öğrenmesi ile modellenebilmesinin önünü açmıştır. Bu tezin amacı bu veri setlerine uygun bir makine öğrenmesi akışı oluşturmaktır. Bu düzlemde Random Forest algoritması ve derin nöral ağlar kullanılmış, eğitilen modellerin bağlanma puanı öngörüleri beraber kullanıldığında mutlak hata sırasıyla, 0.0304, Pearson korelasyon ölçütü 0.904 olarak elde edilmiştir. Bu modelleri kullanarak rastgele arama ve tekrarlayan optimizasyonlar ile güçlü bağlanan örnek bir peptit tasarlanmıştır. Bulgular alan bilgisinin makine öğrenme modeli eğitimdeki yerini vurgulamış, kullanılan örnek ağırlıklarının ve semantik amino asit vektörlerinin başarıya önemli katkıları gözlemlenmiştir. Bu çalışma çeşitli fonksiyonlara sahip peptit tasarlayabilen bir platform oluşturabilmek için temel noktaları göz önüne serer.Peptides are molecular entities with a diverse set of functionalities vital for biological processes and biotechnological applications. Among their roles, the ability of peptides to bind to solid materials has gathered attention, particularly as building blocks in constructing bio-nano interfaces and molecular linkers. Directed evolution techniques such as iterative phage display, have emerged as capable tools for identifying peptides and proteins with specific affinities for various targets despite its constraints, particularly its low-throughput nature. Those limits have motivated the work on more advanced methodologies such as deep-directed evolution, which integrates high-throughput sequencing. By collecting massive amounts of data, deep-directed evolution provides a broad landscape of sequence information, thus enabling computational modeling and optimization of peptide sequences. This thesis aims to develop machine learning workflows that capture the sequence-function relationship from the data, allowing the design of peptides with desired functionalities. Two machine learning approaches were employed: the Random Forest algorithm (RF) and deep neural networks (DNN). By aggregating binding score predictions from the two models, the predictor achieved a Pearson correlation coefficient of 0.904 and a mean absolute error of 0.0304 on the high- confidence test set and was employed to design a candidate peptide as a proof of principle. Our findings emphasize the importance of including domain knowledge via peptide abundance weighting and amino acid encoding types while designing training strategies. The procedures outlined in this work demonstrate key steps towards designing a peptide sequence-function prediction platform with broad implications for bio-nanotechnology and engineering
Gelatin-Containing Porous Polycaprolactone Polyhipes as Substrates for 3d Breast Cancer Cell Culture and Vascular Infiltration
No full textTumour survival and growth are reliant on angiogenesis, the formation of new blood vessels, to facilitate nutrient and waste exchange and, importantly, provide a route for metastasis from a primary to a secondary site. Whilst current models can ensure the transport and exchange of nutrients and waste via diffusion over distances greater than 200 mu m, many lack sufficient vasculature capable of recapitulating the tumour microenvironment and, thus, metastasis. In this study, we utilise gelatin-containing polymerised high internal phase emulsion (polyHIPE) templated polycaprolactone-methacrylate (PCL-M) scaffolds to fabricate a composite material to support the 3D culture of MDA-MB-231 breast cancer cells and vascular ingrowth. Firstly, we investigated the effect of gelatin within the scaffolds on the mechanical and chemical properties using compression testing and FTIR spectroscopy, respectively. Initial in vitro assessment of cell metabolic activity and vascular endothelial growth factor expression demonstrated that gelatin-containing PCL-M polyHIPEs are capable of supporting 3D breast cancer cell growth. We then utilised the chick chorioallantoic membrane (CAM) assay to assess the angiogenic potential of cell-seeded gelatin-containing PCL-M polyHIPEs, and vascular ingrowth within cell-seeded, surfactant and gelatin-containing scaffolds was investigated via histological staining. Overall, our study proposes a promising composite material to fabricate a substrate to support the 3D culture of cancer cells and vascular ingrowth
Optimizing a Bionanocomposite Film for Active Food Packaging With Pectin, Gelatin, and Chestnut Shell Extract-Loaded Zein Nanoparticles
No full textIn this research, a novel active bionanocomposite food packaging film was prepared by incorporating zein nanoparticles loaded with chestnut shell extract (CSE) into a pectin and gelatine matrix. Nanocomposite films were developed based on 28 different formulations, and were assessed focusing on physicochemical, mechanical, optical, thermal, structural, and active properties. Using D-optimal combined design, the optimal formulation was determined by considering variables like carbohydrate, protein, glycerol, and zein nanoparticle ratios. The optimum film displayed low water vapor permeability (0.276 g.mm/m2.h.kPa) and high elongation at break values (>90%). We also evaluated these films for antioxidant activity (38.47 mg Trolox/100 g dw), oxygen permeability in sunflower oil (11.47 meq O2/kg), and volatile compounds. The addition of active zein nanoparticles improved film properties and introduced functional characteristics. This study introduces an optimized active bionanocomposite film formulation for potential applications in active food packaging. © 2024 Elsevier Lt
Connexins in Epidermal Health and Diseases: Insights Into Their Mutations, Implications, and Therapeutic Solutions
No full textThe epidermis, the outermost layer of the skin, serves as a protective barrier against external factors. Epidermal differentiation, a tightly regulated process essential for epidermal homeostasis, epidermal barrier formation and skin integrity maintenance, is orchestrated by several players, including signaling molecules, calcium gradient and junctional complexes such as gap junctions (GJs). GJ proteins, known as connexins facilitate cell-to-cell communication between adjacent keratinocytes. Connexins can function as either hemichannels or GJs, depending on their interaction with other connexons from neighboring keratinocytes. These channels enable the transport of metabolites, cAMP, microRNAs, and ions, including Ca2+, across cell membranes. At least ten distinct connexins are expressed within the epidermis and mutations in at least five of them has been linked to various skin disorders. Connexin mutations may cause aberrant channel activity by altering their synthesis, their gating properties, their intracellular trafficking, and the assembly of hemichannels and GJ channels. In addition to mutations, connexin expression is dysregulated in other skin conditions including psoriasis, chronic wound and skin cancers, indicating the crucial role of connexins in skin homeostasis. Current treatment options for conditions with mutant or altered connexins are limited and primarily focus on symptom management. Several therapeutics, including non-peptide chemicals, antibodies, mimetic peptides and allele-specific small interfering RNAs are promising in treating connexin-related skin disorders. Since connexins play crucial roles in maintaining epidermal homeostasis as shown with linkage to a range of skin disorders and cancer, further investigations are warranted to decipher the molecular and cellular alterations within cells due to mutations or altered expression, leading to abnormal proliferation and differentiation. This would also help characterize the roles of each isoform in skin homeostasis, in addition to the development of innovative therapeutic interventions. This review highlights the critical functions of connexins in the epidermis and the association between connexins and skin disorders, and discusses potential therapeutic options
Protocol for a prospective, multicentre, cross-sectional cohort study to assess personal light exposure
No full textLight profoundly impacts many aspects of human physiology and behaviour, including the synchronization of the circadian clock, the production of melatonin, and cognition. These effects of light, termed the non-visual effects of light, have been primarily investigated in laboratory settings, where light intensity, spectrum and timing can be carefully controlled to draw associations with physiological outcomes of interest. Recently, the increasing availability of wearable light loggers has opened the possibility of studying personal light exposure in free-living conditions where people engage in activities of daily living, yielding findings associating aspects of light exposure and health outcomes, supporting the importance of adequate light exposure at appropriate times for human health. However, comprehensive protocols capturing environmental (e.g., geographical location, season, climate, photoperiod) and individual factors (e.g., culture, personal habits, behaviour, commute type, profession) contributing to the measured light exposure are currently lacking. Here, we present a protocol that combines smartphone-based experience sampling (experience sampling implementing Karolinska Sleepiness Scale, KSS ratings) and high-quality light exposure data collection at three body sites (near-corneal plane between the two eyes mounted on spectacle, neck-worn pendant/badge, and wrist-worn watch-like design) to capture daily factors related to individuals' light exposure. We will implement the protocol in an international multi-centre study to investigate the environmental and socio-cultural factors influencing light exposure patterns in Germany, Ghana, Netherlands, Spain, Sweden, and Turkey (minimum n = 15, target n = 30 per site, minimum n = 90, target n = 180 across all sites). With the resulting dataset, lifestyle and context-specific factors that contribute to healthy light exposure will be identified. This information is essential in designing effective public health interventions
Origami-Inspired Microfluidic Paper-Based Analytical Device (μpad) for Microorganism Detection
No full textPathogenic microorganisms impose great risk especially in resource-limited settings due to inaccessibility of diagnostic tools and monitoring devices. This is mainly caused by current methods often being economically demanding and complex in practice; while these methods are sensitive and accurate, they rarely follow Point-of-care (POC) approaches, which is essential for rapid detection and intervention. Incorporating origami into paper-based analytical devices (mu PAD) presents an innovative alternative, offering affordability, portability, and ease of disposal. Herein, a colorimetric origami mu PAD that is suitable for use in POC applications was developed. The mu PAD was fabricated via laser ablation utilizing PVDF and cellulose membranes. In order to develop the biosensor platform, fabrication parameters were optimized and hydrophilicity of PVDF membranes was improved using various solvents. The PVDF membranes were characterized through light microscopy imaging, protein adsorption assay and contact angle measurements. Then, optimization of the assay parameters was carried out in order to improve sensitivity and resolution of the mu PAD, utilizing Box-Behnken experimental design. The responses generated by the origami mu PAD in form of visible color development were then analyzed using image processing. After optimization is concluded, E. coli detection was carried out as a model system. Resulting calculations showed a limit of detection (LoD) of 2 CFU/mL and a dynamic working range up to 106 CFU/mL for E. coli. Overall, developed origami mu PAD promises an economic advantage compared to conventional methods, and provides rapid and sensitive results without the requirement of expertise or complex equipment