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Analysis of Magnetic Force Linearity in Magnetic Levitation Systems
No full textThe important parameters of bar magnet configurations, in which the same poles are facing each other, are investigated with a focus on their potential applications in magnetic levitation. The scalar product of the magnetic field and its gradient between magnets is referred to as fz, which is a function for force calculations. The magnitude and linear range of this function are then examined. These parameters are computed for several air gap lengths between the magnets, as well as the height and thickness of the magnets, while keeping the magnet length constant. The calculations are experimentally validated by measuring the magnetic field of a magnet system. The choice of thickness and height of the magnets was found to have critical effects on both linearity and the maximum value of fz within the linear range. The results of this study can be used to guide the selection of magnet dimensions and also to evaluate the factors that can influence the measurements and sensitivity of magnetic levitation systems
IMPACT OF DIFFERENT SUBSTRUCTURE AND SUPERSTRUCTURE MATERIALS ON BONE STRESS DISTRIBUTION IN ALL-ON-4 PROSTHETIC RESTORATIONS
No full textAim: This study aimed to examine whether different framework and superstructure materials in All-on-4 prosthetic restorations affect load distribution in peri-implant bone. Materials and Methods: Four implants were placed according to the All-on-4 concept, with distal implants angled at 30 degrees. Framework materials (cobalt-chromium alloy, titanium, PEEK, zirconia) and superstructure materials (composite, zirconia) created eight combinations. 3D models were designed using Rhinoceros 4.0 (3670 Woodland Park Ave N, Seattle, Washington, USA) and VRMesh (VirtualGrid Inc, Bellevue City, Washington, USA), then imported into Algor Fempro (ALGOR, Inc., 150 Beta Drive, Pittsburgh, Pennsylvania, USA) for finite element analysis. A 150N force was applied perpendicular to the occlusal surfaces of the left first molar and premolar. Results: The PEEK framework group showed the highest maximum principal stress (HMaxPS) values in the cortical bone (CB) near the applied force. The zirconia superstructure exhibited lower maximum principal stress values than the composite superstructure. Minimum principal stress (MinPS) was lower in the composite superstructure than in the zirconia superstructure. In the cantilever section, peak MinPS values in the cortical bone decreased as the elastic modulus of the frameworks increased, following the order: PEEK > titanium > Cr-Co > zirconia. Conclusions: The PEEK framework and composite superstructure generated higher tensile forces in the cortical bone surrounding the implants. The highest compression values were observed in the PEEK framework, followed by titanium, Cr-Co, and zirconia. Greater stress accumulation occurred in the cortical bone with the composite superstructure compared to the zirconia superstructure
Endüstrilerde sürdürülebilirlik ilkeleri ve yeşil dönüşüm
No full textİklim değişikliği küresel anlamda karşı karşıya kaldığımız bugünümüzü ve geleceğimizi olumsuz yönde etkileyen ciddi bir problemdir. İklim değişikliği doğal kaynaklarımızın hızla yok olmasını sağlayan sorumsuz üretim ve tüketim alışkanlıkları olan insanın faaliyetlerinin bir neticesidir. Nitekim son yıllarda uluslararası düzeyde kamuoyu oluşmuş ve çevresel etkilerin azaltılmasına yönelik uluslararası anlaşmalar imzalanarak iklim değişikliği ile mücadele çalışmaları hız kazanmıştır. Avrupa Birliği, Yeşil Mutabakat kapsamında 2050 yılında ilk karbon nötr kıta olmayı hedeflemekle birlikte ithal ettiği ürün ve hizmetlerin de yaşam döngülerinde karbonsuzlaşmasını beklemektedir. Bu hedefe ulaşmak isteyen firmalar artık tasarım aşamasındayken ürünlerin bertarafına kadar olan tüm yaşam döngüsünü düşünmek ve çevreye en az etkisi olan faaliyetleri gerçekleştirmek zorundadırlar. Bu tez, sera gazı emisyonlarının yoğun olduğu enerji, lojistik ve otomotiv üretim sektörlerinde döngüsel ekonomi, yeşil süreçler ve yeşil teknolojiler gibi sürdürülebilir uygulamaları ele alarak çevresel etkilerin azaltılması için yenilikçi çözümler sunmaktadır.Climate change is a serious problem that we face globally and that negatively affects our present and future. Climate change is a result of the activities of people with irresponsible production and consumption habits that cause our natural resources to be rapidly destroyed. In fact, in recent years, public opinion has been formed at the international level and efforts to fight against climate change have gained momentum by signing international agreements to reduce environmental impacts. The European Union aims to become the first carbon neutral continent in 2050 within the scope of the Green Deal and also expects the products and services it imports to be decarbonized in their life cycles. Companies that want to achieve this goal must now consider the entire life cycle of the products from the design stage to their disposal and carry out activities that have the least impact on the environment. This thesis offers innovative solutions to reduce environmental impacts by addressing sustainable applications such as circular economy, green processes and green technologies in the energy, logistics and automotive manufacturing sectors where greenhouse gas emissions are intense
Is it safe to perform coronary artery bypass grafting surgery in patients with hemophilia? A case series of four patients
No full textHemophilia is a genetic disorder that mainly affects males and leads to a higher risk of bleeding. There is a lack of clarity regarding the safety of coronary artery bypass grafting (CABG) surgery in patients with hemophilia. In this case series, real-life data of four male hemophilia patients aged 45 to 66 years who underwent CABG was presented. One patient needed to undergo reexploration due to nonsurgical bleeding. However, all patients were discharged in good condition. The current experience revealed that CABG in hemophilia patients is safe to perform with a multidisciplinary approach involving hematologists, anesthesiologists, and cardiovascular surgeons
Evaluation of clinical decision-making perception of nursing students: the Aegean region case
No full textBackground: The clinical learning environment is crucial for developing essential clinical decision-making skills in nursing students. This study examined nursing students’ perceptions of clinical decision-making and the factors that impact it. Methods: A descriptive cross-sectional study was carried out using a self-administered questionnaire, which included a personal information form and the Clinical Decision-Making in Nursing Scale (CDMNS). The study was conducted across ten universities in the Aegean region. Data collection took place at times most convenient for the students, such as during class sessions or lunch breaks. Prior to participation, students were briefed on the study’s objectives and procedures. Those who agreed to participate provided informed consent before completing the questionnaire. Researchers remained present while students filled out the questionnaire to clarify any questions they had. Results: A considerable proportion of students (72.6%) had never received formal education on clinical decision-making. The average CDMNS score was 140.24 ± 17.04, aligning with findings from previous research. A statistically significant difference was observed in the total mean CDMNS score and sub-dimension scores (searching for alternatives, questioning goals and values, evaluating outcomes, seeking information, and objectively integrating new knowledge) based on the university attended (p < 0.001). Conclusions: The findings suggest that nursing students in the Aegean Region demonstrated a moderate level of perceived clinical decision-making skills. To enhance these skills further, it is recommended that alternative educational approaches, such as simulation-based training, case study discussions, and mentoring programmes, be integrated into nursing education and their effectiveness assessed. Clinical trial number: Not applicable © 2025 Elsevier B.V., All rights reserved
Nosocomial lower respiratory tract infections in patients with immunosuppression: a cohort study
No full textBackground: This post-hoc analysis of a multinational, multicenter study aimed to describe and compare clinical characteristics, microbiology, and outcomes between immunosuppressed and non-immunosuppressed patients with nosocomial lower respiratory tract infections (nLRTI). The study utilized data from the European Network for ICU-related Respiratory Infections, including 1,060 adult ICU patients diagnosed with nLRTI. Descriptive statistics were used to compare baseline characteristics and pathogen distribution between groups. A Cox proportional hazards model stratified by immunosuppression status was applied to assess 28-day mortality risk, adjusting for disease severity and key clinical variables. Results: Immunosuppression was observed in 24.9% (264/1060) of the patients, and oncological conditions were the most common etiology of immunosuppression. Chronic pulmonary and cardiovascular diseases were the most frequent comorbidities. In both groups, Pseudomonas aeruginosa was the predominant microorganism, particularly affecting patients with immunosuppression (25.3% vs. 16.7%, p = 0.032). Cox regression model adjusted for disease severity (SAPS II), polytraumatized status, altered consciousness, and postoperative status, SAPS II remained a strong independent predictor of mortality, with each one-point increase associated with a 2.3% higher risk of death (HR: 1.023, 95% CI 1.017–1.030, p < 0.001). The analysis also revealed significant heterogeneity in mortality risk among immunosuppressed patients, with hematological malignancies, recent chemotherapy, and bone marrow transplantation associated with the highest mortality. Conclusions: Immunosuppressed patients had a lower adjusted survival probability compared to non-immunosuppressed patients. Moreover, P. aeruginosa was the most frequently identified etiological pathogen in immunosuppressed patients. © 2025 Elsevier B.V., All rights reserved
Mevcut rüzgar türbini yapılarında kule-temel bağlantısı için güçlendirme yöntemi geliştirilmesi
Get PDFRüzgar enerjisine dayalı elektrik üretim tesislerinde yer alan türbin kulesi taşıyıcı sistemlerinde, gömülü çelik halka ile teşkil edilmiş temel bağlantısı yöntemi sektörün gelişim aşamasında sıklıkla uygulanmıştır. Bu bağlantı yönteminin uygun şekilde çalışabilmesi gömülü halka ile temel arasındaki sürtünme yüzeyi kalitesine bağlıdır. İnşai veya işletme koşullarındaki olası kusurlar, bu türbinleri yapısal olarak hassas hale getirmektedir. Bu tip rüzgar türbini yapılarında hasar mekanizmaları gömülü halka-temel arasındaki sıyrılma benzeri düşey hareket, temel üst yüzeyinde ezilme, çatlak oluşumu ve aşırı titreşim kaynaklı türbinin güç üretiminde aksama gibi problemler doğurmaktaıdır. Hali hazırda kule-temel bağlantıları, boşluk enjeksiyonu ile onarılmakta ancak belirli işletme süresi sonrası problem nüksetmektedir. Bu tez çalışması, gömülü halka uygulamasına sahip rüzgar türbinleri için yay tipi sönümleyicilerin kullanıldığı bir güçlendirme yöntemi önermektedir. Geliştirilen yöntemin yatay yük taşıma kapasitesi üzerindeki etkisini araştırmak ve ayrıca nümerik modellerin doğrulamasını yapabilmek için mevcut bir rüzgar türbini ve temelinin 1/15 ölçeğinde modelleri oluşturulmuştur. Prototiplerin laboratuvar ortamında yapılan testlerinde, geliştirilen güçlendirme yönteminin, mevcut kule yatay yük taşıma kapasitesinde önemli bir artış sağladığı belirlenmiştir. Ayrıca hasar verilen kule-temel modeli üzerinde, epoksi esaslı boşluk enjeksiyonu uygulanıp, bu yöntemin yatay yük – deplasman üzerindeki etkisi test edilmiştir. Böylece geliştirilen güçlendirme yöntemi ile uygulamada sıklıkla tercih edilen boşluk enjeksiyonu yöntemi karşılaştırabilmiştir. Gerçekleştirilen ölçekli model testleri ve nümerik analizler, yay tipi sönümleyiciler içeren yöntemin, rüzgar türbinlerinin güçlendirilmesinde etkin olarak kullanılabileceğini göstermektedir.In wind energy-based electricity generation facilities, the foundation connection method using embedded steel rings has been frequently used in the development phase of the industry for turbine tower support systems. The proper functioning of this connection method depends on the quality of the friction surface between the embedded ring and the foundation. Possible defects in construction or operating conditions make these turbines structurally sensitive. In such wind turbine structures, damage mechanisms such as vertical movement similar to debonding between the embedded ring and the foundation, crushing on the upper surface of the foundation, crack formation, and power production disruptions in the turbine due to excessive vibration cause problems. Currently, tower-foundation connections are repaired using void injection, but the problem recurs after a certain operational period. This thesis proposes a strengthening method using spring-type dampers for wind turbines with embedded ring applications. To investigate the effect of the developed method on horizontal load-carrying capacity and to validate numerical models, 1/15-scale models of an existing wind turbine and foundation were created. Laboratory tests on the prototypes revealed that the developed strengthening method significantly increases the existing tower's horizontal load-carrying capacity. Additionally, epoxy-based void injection was applied to the damaged tower-foundation model, and the effect of this method on horizontal load-displacement was tested. Thus, the developed strengthening method could be compared with the void injection method, which is frequently preferred in practice. The scaled model tests and numerical analyses conducted demonstrate that the method incorporating spring-type dampers can be effectively utilized in the reinforcement of wind turbines
Thiostrepton ile FoxM1 inhibisyonu, DNA hasar yanıt genlerini baskılayarak meme kanseri hücrelerinin tedaviye duyarlılığını artırır
No full textSAĞ-BAP-A-250620-65Aim: Chemotherapy resistance, often linked to the development of resistance against genotoxic agents, is a major obstacle in cancer treatment. FoxM1, a transcription factor frequently overexpressed in malignancies such as breast cancer, is strongly associated with genotoxic therapy resistance. The aim of this study is to conduct a comparative analysis of the effects of thiostrepton (THIO), a FoxM1 inhibitor, on the DNA damage response in HUVEC cells (non-malignant) and MDA-MB-231 breast cancer cells (malignant) Materials and Methods: THIO's impact on cell viability were evaluated in both cell lines using the MTT assay. Oxidative DNA damage levels were measured with the 8-OHdG kit, and apoptosis was assessed using the Caspase 3 ELISA kit. The expression levels of DNA damage response genes (BRCA-1, DNAPKC, FOXM1, RAD51, MRE11 and XRCC1) were analyzed by RT-PCR. Results: MDA-MB-231 cells exhibited greater sensitivity to the cytotoxic effects of THIO than HUVEC cells. In HUVEC cells, THIO caused a significant increase in oxidative DNA damage, whereas no such effect was observed in MDA-MB-231 cell lines. Conversely, breast cancer cells showed a significant increase in Caspase 3 levels. RT-PCR results revealed a marked downregulation of DNA damage response genes, particularly BRCA-1, DNAPKC, MRE11, FOXM1, and XRCC1, in both cell types. Conclusion: THIO has been shown to inhibit FoxM1 expression and downregulate DNA damage response genes in both malignant and non-malignant cells, demonstrating its potential to enhance the sensitivity of breast cancer cells to therapy by disrupting DNA repair pathways. However, its potential to induce oxidative damage in non-malignant cells underscores the need for further comprehensive studies to validate its therapeutic efficacy and assess its safety in normal tissues.Amaç: Kemoterapi direnci, genellikle genotoksik ajanlara karşı direnç gelişimiyle ilişkilendirilir ve kanser tedavisinde önemli bir engel teşkil eder. FoxM1, meme kanseri gibi malignitelerde sıkça aşırı eksprese edilen ve genotoksik tedavi direnci ile güçlü bir şekilde ilişkili olan bir transkripsiyon faktörüdür. Bu çalışmanın amacı, FoxM1 inhibitörü olan thiostrepton'un (THIO) malign olmayan HUVEC hücreleri ile malign MDA-MB-231 meme kanseri hücrelerinde, DNA hasar yanıtı üzerindeki etkilerini karşılaştırmalı olarak analiz etmektir. Gereç ve Yöntem: THIO'nun hücre canlılığı üzerine etkileri her iki hücre hattında MTT testi kullanılarak değerlendirildi. Oksidatif DNA hasar seviyeleri 8-OHdG kiti ile ölçülürken, apoptoz seviyeleri Caspase 3 ELISA kiti ile belirlendi. DNA hasar yanıt genlerinin (BRCA-1, DNAPKC, FOXM1, RAD5, MRE11, ve XRCC1) ekspresyon düzeyleri RT-PCR yöntemiyle analiz edildi. Bulgular: THIO’nun, MDA-MB-231 hücrelerinde HUVEC hücrelerine kıyasla daha belirgin sitotoksik etki gösterdiği gözlendi. HUVEC hücrelerinde THIO, oksidatif DNA hasarında anlamlı bir artışa neden olurken, MDA-MB-231 hücrelerinde bu tür bir etki gözlenmedi. Buna karşın, meme kanseri hücrelerinde Caspase 3 seviyelerinde belirgin bir artış saptandı. RT-PCR analizleri, DNA hasar yanıt genlerinin, özellikle BRCA-1, DNAPKC, MRE11, FOXM1, ve XRCC1’in ekspresyonunda her iki hücre hattında anlamlı bir düşüş olduğunu gösterdi. Sonuç: THIO, FoxM1 ekspresyonunu inhibe ederek DNA hasar yanıt genlerinin ekspresyonunu baskılamaktadır. Bu durum, THIO’nun DNA onarım yollarını bozarak meme kanseri hücrelerinin tedaviye duyarlılığını artırma potansiyeline sahip olduğunu göstermektedir. Kemoterapi direncinin aşılmasına katkı sağlayabilecek bu bulguların doğrulanması ve THIO’nun terapötik kullanımının araştırılması için ileri çalışmalara ihtiyaç vardır.Scientific Research Projects Coordination Unit of Giresun University [TR] Giresun Üniversitesi Bilimsel Araştırma Projeleri Birim
Heavy Metal Contamination Along the Duhok-Zakho Highway Soils: Spatial analysis, Risks, and Ecological Implications
No full textThis study investigates heavy metal contamination in soils of the Duhok-Zakho Highway of Iraq, where 20 samples were collected along a 50-km-long highway to assess Cu, Pb, Fe, Mg, Co, Ni, and Mn concentrations. Results revealed significant spatial variations in metal concentration, where the ranking of the metals followed: Fe > Mn > Mg > Ni > Co > Pb > Cu. The enrichment factor analysis indicated moderate to very high levels, while the geoaccumulation index exhibited a high level of metal enrichment, surpassing the standard background value. The ecological risk was assessed as moderate. Non-carcinogenic risk analysis revealed that Fe and Mn posed extreme non-cancer risk, with ingestion accounting for 99.95% of exposure. Children showed 10 times more vulnerability than adults to non-cancer risks. Carcinogenic risk derived from Ni and Pb exceeded the USEPA guideline threshold (1 x 10(-6)), with the children facing 25 times greater risks than the adults. The toxicity leaching test revealed substantial metals leaching (64-79%), suggesting a high potential for heavy metals to transport downstream the agricultural farmland and probable groundwater contamination. The findings highlight the impact of vehicle-induced metal pollution and industrial operations on heavy metal distribution in highway soils
Dental implants coated with BMP-2-and ?-tocopherol-loaded nanofibers enhance osseointegration
No full textDental implants are widely used to treat edentulism, but the extended osseointegration period can increase infection risk, potentially causing peri-implantitis or implant failure. Bone morphogenetic proteins (BMPs), particularly BMP-2, show promise in bone regeneration but require stability and controlled release for effectiveness. This study developed dental implants coated with polycaprolactone (PCL) nanofibers loaded with BMP2 and alpha-tocopherol. BMP-2 was encapsulated in chitosan nanoparticles (BMP-2-CNPs) with an efficiency of 76.5 +/- 1.01 %, particle size of 234.6 +/- 0.15 nm, polydispersity index (PDI) of 0.284, and zeta potential of 24.97 +/- 0.06 mV. BMP-2-CNPs and alpha-tocopherol were incorporated into PCL nanofibers using electrospinning. SEM imaging confirmed uniform nanofiber coating on implants. BMP-2 release from BMP-2-CNPs lasted 5 days with a 99 % release rate, while BMP-2 release from PCL nanofibers extended to 35 days with a 70 % release rate. alpha-Tocopherol release was 60 % within 24 h, continuing up to 96 h. The specific surface area of coated implants was 0.591-0.601 m2/g. WST-1 analysis showed over 85 % cell viability for both L929 fibroblasts and MC3T3-E1 osteoblasts after 24 and 72 h, with no cytotoxicity or increased inflammatory biomarkers TNF-alpha and IL-1 beta. MC3T3-E1 cells showed up to a 16-fold increase in Alkaline Phosphatase (ALP) activity after 7 and 14 days, and enhanced expression of Runx2, Osteocalcin (OCN), and Osteopontin (OPN) genes, confirmed by Western Blot. Increased biomineralization was observed via Alizarin Red staining. In conclusion, BMP-2-CNPs and alpha-tocopherol-loaded PCL nanofibers on dental implants are a promising strategy to accelerate osseointegration post-implantation.Scientific and Technological Research Council of Turkey (TUBITAK) [121S709]This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK; Grant No: 121S709)