İstanbul Sağlık ve Teknoloji Üniversitesi Kurumsal Akademik Arşivi
DSpace@İSTÜN, Üniversite mensupları tarafından doğrudan ve dolaylı olarak yayınlanan; kitap, makale, tez, bildiri, rapor, araştırma verisi gibi tüm akademik kaynakları uluslararası standartlarda dijital ortamda depolar, Üniversitenin akademik performansını izlemeye aracılık eder, kaynakları uzun süreli saklar ve telif haklarına uygun olarak Açık Erişime sunar.
Güncel Gönderiler
Mechanical performance of nonabsorbable monofilament suture materials tied with different suturing techniques under various knot configurations: An in vitro study
(MDPI Publishing, 2025) Tayşi, Nuri Mert; Erten Tayşi, Ayşegül; Erçal, Pınar; Şişmanoğlu, Soner
This study compared widely used nonabsorbable and monofilament suture materials tied with three different configurations and two different suture techniques. Three su ture materials (polytetrafluoroethylene, polypropylene, and nylon) were tied with either Laurell–Gottlow or the horizontal mattress suturing techniques using three different knot configurations: A (2 = 1 = 1 = 1 = 1), B (2 × 1 = 1 = 1 = 1), and C (1 × 2 = 1 = 1 = 1) on an experimental platform manufactured using a three-dimensional printer. Specimens underwent microtensile testing to determine maximum load failure and elongation rates at baseline and after 7 days of artificial saliva immersion. The Laurell–Gottlow yielded significantly lower elongation rates and higher failure load than the horizontal mattress suturing technique using nylon and polypropylene sutures at both time points (p < 0.001). Nylon had a significantly higher failure load and elongation than polypropylene and polyte trafluoroethylene at baseline for both suturing techniques and all three knot configurations (p < 0.001). Configuration C had low failure load values following immersion for all suture materials when using horizontal mattress suturing. Configuration A demonstrated superior failure load following the immersion period for all materials using both techniques. The polytetrafluoroethylene suture remained more stable over time. These findings indicate that the Laurell–Gottlow suturing technique with Configuration A provides better mechanical resistance to external forces when using nonabsorbable monofilament suture materials.
Optimization of VA-NADES-ME for the one-step separation and determination of rhodamine B and rhodamine 6G in red pencil samples
(Taylor & Francis, 2025) Topraksever, Nükte; Özgül Artuç, Gamze
An environmentally friendly and simple method was developed for the simultaneous separation and determination of Rhodamine B (RhB) and Rhodamine 6 G (Rh6G) in red pencil samples by vortex assisted microextraction using NADES (Natural Deep Eutectic Solvent). A two-phase system was established using lactic acid-based DES (Deep Eutectic Solvent) and tetrahydrofuran (THF) for the extraction of RhB and Rh6G. In method optimization, sample amount, pH, DES type, DES volume, solvent type and solvent volume parameters were investigated. Limit of detection (LOD) and limit of quantification (LOQ) values were 4.13, 5.03 and 12.5, 15.3 µg/mL for RhB and Rh6G, respectively. The correlation coefficients obtained at concentrations ranging from 1–12 µg/mL are 0.9973 and 0.9985. Red pencil samples were spiked at two different concentrations (3–5 µg/mL). The recovery values obtained were in the range of 84.7%-107.4%. The relative standard deviation (RSD) values of the developed method are in the range of 2.77%-5.45%, indicating that the method is reproducible. The results showed that the developed microextraction method can be success fully applied for the separation and determination of RhB and Rh6G from red pencil samples.
Quantitative determination of α-tocopherol and α-tocopheryl acetate in pharmaceutical and supplementary soft capsules by high performance liquid chromatography
(İstanbul Gelisim University, 2025) Topraksever, Nükte; Özgül Artuç, Gamze
Aim: This study aims to determine the amounts of α-tocopherol (α-toc) and α-tocopheryl acetate (α-tocAc) in soft pharmaceutical capsules and supplements using a chromatographic method. Additionally, method validation parameters for both analytes were evaluated. Method: Analyses were performed using a chromatographic method. As part of the method validation, recovery (% recovery), repeatability (% RSD), linear regression coefficient (R²), limit of detection (LOD), and limit of quantification (LOQ) values were determined. Results: The recovery values were found to be above 95%. Repeatability (%RSD) was calculated as <3%. The linearity (R²) values were obtained as 0.999. For α-toc: LOD: 0.131 µg/mL and 2.228 µg/mL, LOQ: 0.396 µg/mL and 6.752 µg/mL. For α-tocAc: LOD: 0.260 µg/mL, LOQ: 0.787 µg/mL. Conclusion: The chromatographic method used in this study enabled the determination of α-toc and α tocAc with high accuracy and repeatability. This method can be considered a reliable alternative for the analysis of these compounds in pharmaceutical products.
Phocatalytic dye degradation activities of chitosan film modified by green synthesized tio2 from aloe vera leaf extract
(Avestia Publishing, 2025) Kaba, İbrahim; Bozkurt, Rabia Nur; Kerkez Kuyumcu, Özge; Koca, Atıf
Recent research focuses on heterogeneous photocatalysis, an environmentally friendly and cost-effective method that uses solar energy to completely degrade pollutants without generating secondary waste. The focus is optimizing the properties of photocatalysts in terms of electronic structure, light absorption, and reduced recombination rate of photogenerated charges and easy separation of the photocatalyst from reaction media [1]. The potential for efficient, sustainable heterogeneous photocatalysis has been demonstrated by semiconductors such as TiO₂, ZnO, Fe₂O₃, CdS, CuS, and ZnS [2]. TiO₂ is regarded as one of the most effective photocatalysts. The usage of TiO₂ for the degradation of hazardous organic dyes in wastewater has significant potential. The separation of the photocatalyst from the reaction medium remains a significant challenge in photocatalytic applications. In particular, the recovery of TiO₂ after the degradation of organic dyes poses a considerable difficulty, as its fine particulate nature hampers efficient separation from the treated solution. One of the strategies in this regard is the immobilization of the photocatalyst by embedding it into a polymer matrix. This approach facilitates easier separation of the photocatalyst from the reaction medium [3]. Chitosan, a natural biopolymer widely used for its biodegradability and biocompatibility, is an attractive candidate for hydrogel development due to its functional groups that serve as cross-linking sites during hydrogel formation. It has also been combined with photocatalysts and utilized in numerous studies [4-6]. In this study, green-synthesized TiO₂-embedded chitosan films (Bio-TiO₂-CS films) prepared using aloe vera leaf extract offer the advantage of facile separation after the degradation process, as well as potential reusability following dye removal. As the goal of the study, it is believed that the obtained chitosan film hydrogels can be used as an effective bio-template material to disperse TiO2 nanostructures due to their three-dimensional porous structure and appropriate nanopore size distribution, and this feature has led us to investigate the simpler, recyclable, green approach, and biomaterial development of the use of Bio-TiO₂-CS Hydrogel Films in photocatalytic dye removal from water.
Development of an aluminum body ship shaft sealing element
(RDCONF, 2025) Ertuğrul, Hasan; Kaynar, Arda; Tanrıver, Kürşat; Ay, Mustafa
Günümüzde şaft geçişlerinde kullanılan sızdırmazlık elemanları, gemi ve endüstriyel makinelerde güvenlik ve verimlilik açısından kritik öneme sahiptir. Mevcut uygulamalar, genellikle elastomer contalar, metal muhafazalar veya yağlama destekli sistemler üzerine kuruludur. Ancak bu yapılar, montaj sırasında hizalama hatalarına karşı hassas olup birleşim noktalarında sızıntı riski barındırmakta, uzun süreli kullanımda korozyon ve aşınma sorunları ile karşılaşmaktadır. Ayrıca kauçuk veya yaylı mekanizmalara dayalı çözümler, yüksek basınç, titreşim ve sıcaklık altında deformasyona uğrayarak sızdırmazlık performansını kaybederken, yağlama gerektiren sistemler bakım maliyetlerini artırmakta ve çevresel riskler oluşturmaktadır. Bu yetersizlikler, daha dayanıklı, montajı kolay, bakım gereksinimi düşük ve korozyona dirençli yenilikçi tasarımlara olan ihtiyacı ortaya koymaktadır. Bu çalışmada, özellikle endüstriyel makine ve denizcilik uygulamalarında güvenli montaj sağlamak amacıyla kullanabilecek puzzle tipi bir sızdırmazlık elemanı tasarım, geliştirilmesi ve üretilmesi amaçlanmıştır. Bu tasarımın en önemli avantajı, denizcilik uygulamalarında sıklıkla karşılaşılan sızdırma, montaj zorlukları ve korozyon problemlerine etkili çözümler sunmasıdır. Üç parçalı puzzle tipi geçmeli tasarım, tamamlayıcı (dişi-erkek) bağlantı noktaları sayesinde parçaların montaj sırasında otomatik olarak hizalanmasını sağlayarak, işçilik kaynaklı hataları minimize eder ve montaj süresini kısaltmaktadır. Geçmeli bağlantı yapısı sayesinde birleşim noktalarındaki temas yüzeyi artırılarak sızdırmazlık performansı maksimum seviyeye çıkarılmaktadır. Dış yüzeyde bulunan kanal, O-ring, conta veya sıkıştırma teli gibi ek elemanların yerleştirilmesine olanak tanıyarak yüksek basınç ve titreşim altında dahi güvenli bir bağlantı sağlamaktadır. Kullanılan karbon grafit ve korozyona dayanıklı alüminyum alaşımı, deniz ortamındaki aşındırıcı etkiler karşısında uzun ömür ve bakım kolaylığı sunmaktadır. Ayrıca yapının hafif olması, montaj ve taşıma süreçlerini kolaylaştırırken, sistemin genel maliyetini de düşürmektedir. Tüm bu özellikler, güvenlik, dayanıklılık ve operasyonel verimlilik açısından mevcut sistemlere kıyasla önemli üstünlükler sağlamaktadır.
