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Article Citation - Scopus: 1An Investigation on the Dna Binding Activities of Melamine, Cyanuric Acid and Uric Acid(Editura Acad Romane, 2021) Senol, Ali; Devrim, Alparslan Kadir; Sudagidan, Mert; Ozalp, Veli CengizMelamine can be added to various foods such as milk, milk powder, baby food, pet, and livestock feed for cheating purposes due to its high nitrogen content. Regarding its usage in food products, there is a need to investigate its possible interactions with DNA. Thus, this study aimed to investigate the interactions of melamine and its metabolized products, cyanuric acid and uric acid with genomic DNA, isolated from eukaryotic (calf thymus) and prokaryotic (Staphylococcus aureus) sources. UV-absorbance spectrophotometry, fluorescence spectrophotometry, and agarose gel electrophoresis techniques were used to evaluate these interactions. The five different concentrations of melamine, cyanuric acid, and uric acid were incubated with fixed DNA concentration and it was determined that the test compounds interacted with the DNA molecules. The data obtained by UV-absorbance and fluorescence spectrophotometry techniques revealed an increase in wave peaks observed with the increasing substance concentration. After the obtained data of the aforementioned techniques were evaluated together, it was concluded that melamine, cyanuric acid, and uric acid bonded to the eukaryotic and prokaryotic genomic DNA materials via groove binding.Article Citation - WoS: 6A Light Bulb in Every House the Istanbul General Electric Factory and American Technology Transfer To Turkey(Johns Hopkins Univ Press, 2022) Tunc, Tanfer Emin; Tunc, GokhanIn 1946, Turkish entrepreneur Vehbi Koc signed an agreement with the U.S. firm General Electric to build and operate its first light bulb factory in the Near/Middle East, in Istanbul. This private joint venture introduced new manufacturing techniques, business practices, and consumer habits to Turkey, opening channels of postwar technological exchange. Closer examination of the GE-Koc partnership reveals that during the early Cold War, the transfer and embedding of American technologies in Turkey was a politically complicated process of innovation that required constant adaptation. Fraught with unforeseeable obstacles, it also required cautious negotiation with multiple transnational actors. The story of the GE-Koc partnership thus adds a new dimension to historical understandings of the Turkish Cold War experience and the Americanization of the region. It illustrates how transferring a nonmilitary, soft-power, domestic technologythe light bulb-played a significant role in Turkish-American relations and therefore contributes to studies of U.S. Cold War diplomacy through transnational investment in innovation.Article Citation - WoS: 5Component Importance in Coherent Systems With Exchangeable Components(Cambridge Univ Press, 2015) Eryilmaz, SerkanThis paper is concerned with the Birnbaum importance measure of a component in a binary coherent system. A representation for the Birnbaum importance of a component is obtained when the system consists of exchangeable dependent components. The results are closely related to the concept of the signature of a coherent system. Some examples are presented to illustrate the results.Article Citation - WoS: 38Citation - Scopus: 47Understanding Key Skills for Information Security Managers(Elsevier Sci Ltd, 2018) Haqaf, Husam; Koyuncu, MuratInformation security management is a necessity for all institutions and enterprises that regard company information as valuable assets. Developing, auditing and managing information security depends upon professional expertise in order to achieve the desired information security governance. This research seeks the key skills required for the position of information security management as well as the methods to develop these skills through professional training programs. The study adopts the Delphi method which requires building a list of items through a literature survey and involves experts with certain expertise to modify the list until a consensus on less than 20% of the items is reached. Through completing three rounds of the Delphi technique - data collection, relevance voting and ranking sixteen skills are shortlisted as the key skills. In the final list, the majority belong to core information security skills, and the top two skills belong to project/process management skills and risk management skills, indicating the importance of these skills for the information security manager role. In addition, a series of related professional training programs and certifications are surveyed, the outcome of which highlights a number of most comprehensive and appropriate programs to develop these determined skills.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 Covid-19 Salgınının Bölgesel Borsa Turizm Endekslerine Etkilerinin Araştırılması(2023) Tümer, Tolga; Tengilimoğlu, DilaverBu çalışmada, bölgesel borsa turizm endekslerinin COVID-19’dan etkilenme düzeyleri araştırılmıştır. Bu amaçla çalışmada, Kuzey Amerika, Avrupa ve Asya Pasifik bölgelerini kapsayan borsa turizm endeksleri kullanılarak istatistiki analizler yapılmıştır. Çalışmanın kapsamı COVID-19’un dünyaya yayılmaya başladığı dönemden itibaren 22 Ocak 2020-22 Ocak 2022 tarihleri arasındaki iki yıllık süreci kapsamaktadır ve çalışmada bu süreç çeyrek dilimlere ayrılarak sekiz dönem kapsamında analiz edilmektedir. Günlük veriler kullanılan araştırmada hem dünyadaki hem de kullanılan endekslerin kapsadığı bölgelerdeki COVID-19 verileri dikkate alınmıştır. COVID-19 verileri olarak günlük vaka, günlük ölüm, toplam vaka ve toplam ölüm sayıları toplanmıştır. Araştırmanın sonucunda, borsa turizm endekslerini negatif yönde en fazla COVID-19 kaynaklı bölgesel günlük ölümlerin etkilediği bulunmuştur. Bu çalışma, geniş kapsamı, bölgesel ve dönemsel karşılaştırma sunan bulguları ile alanyazına katkı sunmaktadır.Article DOĞRUSAL OLMAYAN SINIR KOŞULLARINA SAHİP ISI TRANSFERİ PROBLEMLERİNİN SINIR ELEMAN YÖNTEMİ İLE ANALİZİNE YÖNELİK YENİ BİR FORMÜLASYON(2019) Baranoğlu, BesimBu çalışmada Fourier denklemi ile ifade edilen ısı transferi problemlerinin bir ya da daha fazla bölgesinde tanımlı doğrusal olmayan sınır koşulları altında çözümüne yönelik sınır eleman yöntemi tabanlı etkili bir sayısal çözüm sunulmaktadır. Çözüm, sınır eleman yöntemi sistem matrislerinin üzerinde yapılan matematiksel işlemler ile bilinmeyenleri sadece doğrusal olmayan sınır bölgesindeki sıcaklık farkı olan indirgenmiş matris denklemleri elde etmektedir. Bu sayede doğrusal olmayan sınır koşullarına dayalı iterasyonlar daha hızlı gerçekleştirilebilmektedir. Doğrusal olmayan sınır koşullarının tanımlı olduğu bölgelerde çözüm elde edildikten sonra tüm sınır çözümü tanımlı bir son-işlem ile gerçekleştirilebilmektedir. Gerçek çözümü elde edilmiş bir örnek kullanılarak elde edilen sonuçlar değerlendirilmiştir.Article Alzheimer hastalığında Kallikrein-6, 7 ve potasyum kanal proteinlerinin olası rolü(2021) Bulduk, Erkut; Yıldırım, Filiz; Yıldırım, ZuhalAmaç: Alzheimer hastalığının (AH) oluşum mekanizması kesin olarak bilinmemekle birlikte AH’dan sorumlu başlıca iki protein, senile plakların yapısındaki beta amiloid ve nörofibriler yumakların yapısındaki tau proteinidir. Hastalığa yol açan en önemli etmenlerden biri çözünür olmayan amiloid çökeltilerin oluşumu, diğeri ise artmış tau fosforillenmesidir. Kallikreinler, nöronal hasar ve işlev kaybı ile belirgin AH’nın etiyolojisinde rol oynayan, serin proteazların bir alt familyasıdır. Kallikrein (KLK)-6 ve KLK-7’nin merkezi sinir sisteminde (MSS) yüksek seviyelerde bulunan yaşa bağlı proteaz olduğu bilinmektedir. Daha once AH’ı gibi nörodejeneratif hastalıklarda yer alan hücre dışı proteinlerin proteolizine karıştığı gösterilmiştir. Bu çalışmada KLK-6 ve KLK-7’nin AH patogenezindeki olası rolünü ve potasyum kanal proteinleri arasındaki ilişkiyi araştırmayı amaçladık. Yöntem: Çalışmaya Polatlı Duatepe Devlet Hastanesinde takip edilen yaşları 65’in üzerinde olan 35 AH ve rutin tarama amacıyla nöroloji polikliniğine başvuran kognitif durumu normal olarak değerlendirilen 35 sağlıklı birey (control grubu) dahil edildi. 12 saat açlığı takiben antekübital venden alınan kan örnekleri 4°C’de 2500xg’de 10 dakika santrifüj edilerek, serum örneklerinde KLK-6 ve KLK-7 ile içeri doğru düzeltici potasyum kanalı (KCNJ3) ve iki gözenekli potasyum kanalı (KCNK9) protein düzeyleri enzim-bağımlı immunosorbent assay (ELISA) ile ölçüldü. Gruplar arasındaki fark T-test ile incelendi. p<0.05 istatistiksel olarak anlamlı kabul edildi. Bulgular: Gruplar arasında yaş ve cinsiyet açısından bir fark saptanmadı (p>0.05). Alzheimer grubu control grubu ile karşılaştırıldığında serum KLK-6 ve KLK-7 düzeyleri anlamlı olarak artarken (p<0.05), KCNJ3 ve KCNK9 protein düzeylerinde bir fark saptanmadı (p>0.05). Sonuç: Beyinde anormal protein katlanmasının ve birikmesinin önüne geçilememesinin AH’ye yol açtığı düşünülmektedir. Bu araştırmanın bulgularına göre KLK- 6 ve KLK-7 düzeyleri ile AH’nın patolojisi arasında bir ilişki saptandı.Article Citation - WoS: 12Skeletonization-based beam finite element models for stochastic bicontinuous materials: Application to simulations of nanoporous gold(Cambridge Univ Press, 2018) Soyarslan, Celal; Argeso, Hakan; Borgmann, SwantjeAn efficient representative volume element generation strategy is developed in modeling nanoporous materials. It uses periodic 3D beam finite element (FE) models derived from skeletonization of spinodal-like stochastic microstructures produced by a leveled random field. To mimic stiffening with agglomeration of the mass at junctions, an increased Young's modulus is assigned to the elements within the junction zone. The effective Young's modulus, Poisson's ratio, and universal anisotropy index are computed. A good agreement of the Young's modulus predictions with those obtained from experimental results for phase volume fractions 0.20 < phi(B) < 0.50 is observed. Moreover, the elastic anisotropy index of the generated beam networks shows sufficient proximity to isotropy. Finally, it is demonstrated that, as compared to the simulation statistics of voxel-FE models, for the beam-FE models over 500-fold computational acceleration with 250-fold less memory requirement is provided.Article Citation - WoS: 13Citation - Scopus: 13Evaluation of procedural and clinical outcomes of transcatheter aortic valve implantation: A single-center experience(Kare Publ, 2020) Karaduman, Bilge Duran; Kayaoğlu, Hüseyin Ayhan; Keleş, Telat; Bozkurt, EnginObjective: Transcatheter aortic valve implantation (TAVI) is an established alternative to surgical aortic valve replacement. Our study aimed to evaluate the implementation of TAVI at our large-volume center, having an all-comer patient population with short and long-term follow-ups. Methods: This retrospective, single-center analysis included 556 consecutive patients with symptomatic severe aortic stenosis (AS) who underwent TAVI between July 2011 and December 2019. Results: The mean age of the entire population was 77.6±7.9 years, and 54.9% were women. The Society of Thoracic Surgeons (STS) mean score of the cohort was 6.0%±3.5%. The balloon-expandable valve (Sapien XT, Sapien 3; Edwards Lifesciences, Irvine, California) was the most frequently used valves in this cohort (94.6%). Transfemoral access was used in 96.3% of patients. Implantation success was achieved in 96.6% of cases. During the TAVI procedure, 7.2% of patients required permanent pacemaker implantation, with 37.5% in the Lotus valve group needing the most permanent pacemakers. The mean length of hospital stay for the entire cohort was 4.5±2.3 days. Overall, 22 (3.9%) in-hospital deaths occurred before hospital discharge. The mean follow-up period was 15.1±14.9 months for all patients, and a significant improvement was noted in all echocardiographic parameters and functional capacity. Paravalvular leak (PVL) was documented in 18.9% patients, mild in 17.9%, and moderate in 1% at discharge. No cases with severe PVL, necessitating additional procedures. The multiple logistic regression analysis revealed that sex, STS score, baseline SYNTAX score, bicuspid valve morphology, common femoral artery diameter, and post-TAVI PVL were independent predictors of overall mortality. Conclusion: To our knowledge, this study, which is the largest single-center real-world experience of TAVI in Turkey, demonstrated low complication rates with favorable short- and mid-term THV performance in patients undergoing TAVI.
