21241 research outputs found
Sort by
Investigation of the effects of different nanoparticle-reinforced liquids on the cooling performance of the battery thermal management system
Get PDFElectric vehicles are gaining importance in the transportation sector as an environmentally friendly option to replace fossil fuels and reduce carbon footprint. Battery packs, which are the power source of electric vehicles, are high-cost and thermally sensitive components. The temperature rising and temperature distribution of battery packs during charging and discharging processes affect their performance, life, and safety. Therefore, an effective cooling system is required to keep the operating temperature of the battery packs in the optimum range and to ensure homogeneous temperature distribution. In this study, a battery module containing 18 cylindrical lithium-ion batteries was placed in a labyrinth-type cooling channel. The cooling channel is made of copper. Pure water, boron nitride (BN)-water nanofluid, and titanium dioxide (TiO2)-water nanofluid were passed through the cooling channel and the thermal performances of the cooling fluids were compared. Concentrations of 0.1% by mass of BN-water nanofluid and 0.1% by mass of TiO2-water nanofluid were used. Experiments were carried out at 1C charge and 1C, 2C, and 3C discharge rates to test the battery pack under different operating conditions. In all experiments, the inlet flow rate of the refrigerants was kept constant at 790 ml/min and the inlet temperature at 25 degrees C. According to the experimental results, it was seen that BN-water nanofluid provides better cooling performance compared to other fluids and makes the temperature distribution of the battery module more homogeneous. This study aims to contribute to the development of battery thermal management systems in electric vehicles
The Characteristics and Outcomes of Contralateral Non-Concurrent Hip Fractures: A Retrospective Study in Geriatric Patients
Get PDFBackground and Objectives: This study aimed to determine the relationship between non-simultaneous contralateral hip fractures, urban and rural differences, fracture localization, time between fractures, physiotherapy applications, comorbidity, and the second fracture outcomes. Materials and Methods: We retrospectively analyzed 107 patients aged 65 and older with proximal femur fractures (PFFs) who underwent surgery at D & uuml;zce University Medical Faculty between January 2010 and December 2022. High-energy fractures, pathological fractures, and patients with a history of old fractures were excluded. Results: The study included 66 females (61.7%) and 41 males (38.3%), with a mean age of 83.76 years. The mean interval between two fractures was 28.3 months. There was no statistical difference between the localization of the first and second fractures (p = 0.107). However, there was a significant difference in the first PFF localizations of patients living in rural areas (p = 0.023). Patients with heart failure, respiratory failure, osteoporosis, and cognitive impairment had shorter intervals between fractures (p < 0.001). Conclusions: This study shows that age, female gender, place of residence, comorbid diseases, and whether physical therapy is received after the first fracture are significant risk factors for a second hip fracture in patients over 65 years of age
In Vitro’dan In Vivo’ya Yaşlılık Model Teorileri
Get PDFThe theoretical equivalence of expressing that a cell is aging to its inability to perform the assumed function is not exactly accurate, it involves a gradual decrease in cell aging mechanisms. Factors such as genetics, lifestyle, and environmental effects maintain the biological change of the cell. The concept of cellular senescence was initially introduced by Hayflick and his collaborators in 1961 when they noticed that human diploid fibroblasts cultured in vitro could undergo only a limited number of cell divisions before their ability to proliferate was permanently halted. This phenomenon, known as the 'Hayflick limit', was subsequently linked to the gradual shortening of telomeres with each successive round of cell division. Throughout the aging process, senescent cells collect in different tissues. Their involvement in age-related health issues such as neurodegenerative disorders, heart problems, cancer, kidney-related changes, chronic lung diseases, and osteoarthritis suggests that targeting senescent cells therapeutically could be promising across various health conditions. This review will discuss the available data on which cell types may undergo aging based on biological aging and how these processes may impact age-associated tissue-specific pathologies. Additionally, the markers used to characterize the physiological transition of aging cells from in vitro to in vivo settings will be evaluated. The discussed data may serve as a significant starting point for an expanded definition of the molecular and functional characteristics of aging cells in different organs, thus supporting the development and enhancement of targeting strategies in vivo. © 2024, Duzce University Medical School. All rights reserved
Comprehensive analysis of mechanical properties, wear, and corrosion behavior of AA7075-T6 alloy subjected to cryogenic treatment for aviation and defense applications
Get PDFIt is important that the parts to be used in the aviation and defense industry have high wear, fatigue and corrosion resistance. AA7075-T6 alloys are increasingly used in every field due to their advantageous physical and mechanical properties. However, some of the materials of this alloy types exhibit excellent fatigue strength and ductility, but their surface hardness and surface roughness after processing may be poor. For this reason, the wear resistance of AA7075-T6 aluminum alloy expected to be improved in order to increase their corrosion resistance properties. In this work, cryogenic treatment was applied to AA7075-T6 alloy and the mechanical characteristics, wear and corrosion behaviors of these samples were examined. As a result of the experiments, it was determined that cryogenic treatment improved the wear behavior of AA7075-T6 alloy. The untreated sample was found to have the highest wear rate, whereas the sample with deep cryogenic treatment (DCT) had the lowest wear rate. The hardness of the DCT process increased by 5.79 %, according to macro hardness measurements, making the AA7075-T6 alloy harder from 80.16 HRB to 84.8. The SEM images revealed that, the shallow cryogenic and deep cryogenic operations had substantial effects on the microstructure by modifying the size and distribution of precipitates in the AA7075-T6 alloy. In addition, tensile and hardness tests were carried out to assess the mechanical characteristics of the samples. Accordingly, the maximum tensile strength and hardness values were obtained in the deep cryogenically treated sample. The tensile strength of the DCT sample was approximately 544.18 MPa, a considerable 11.5 % increase above the untreated sample's 488.07 MPa strength. In potentiodynamic polarization testing, the DCT treated sample was determined to have the maximum corrosion resistance. Among the materials tested, the DCT sample showed the strongest corrosion resistance, with a corrosion potential of -0.689 V and a corrosion rate of 0.021 mm/year. Wear rate analysis revealed that DCT samples experienced the least material loss, demonstrating improved abrasion resistance. Enhanced hardness and the formation of stable oxide tribo-layers contributed to these superior wear characteristic
Comparison of conventional MR arthrography and 3D volumetric MR arthrography in detection of cartilage defects accompanying glenoid labrum pathologies
Get PDFObjectivesIn this study, we aimed to compare conventional and T1-weighted volumetric magnetic resonance arthrography (MRA) in the diagnosis and grading of glenoid cartilage defects that accompany labral pathologies.Materials and methodsA total of 79 patients who were prediagnosed with labrum pathologies based on shoulder magnetic resonance imaging (MRI) had MRA and CTA between December 2021 and May 2022. CTA was regarded as reference standard. CTA images were examined by a radiologist experienced in musculoskeletal radiology, and MRA images were examined by two radiologists independently to determine presence, grade, and localization of any glenoid cartilage defect, if present. Sensitivity, specificity, and accuracy were calculated separately for conventional and T1-weighted volumetric MRA. In addition, at the last stage, two observers examined all MRAs together, and the presence of a cartilage defect was decided by consensus, and the overall sensitivity, specificity, and accuracy were calculated.ResultsCartilage defect was detected on CTAs of 48 (60.75%) cases of among 79 patients with labrum pathology. The sensitivity, specificity, and accuracy of conventional MRA for two examiners were 17-19%, 100-100%, and 49-51%, respectively, while those values were 67-65%, 92-97%, and 84-77%, respectively, for T1-weighted volumetric MRA. Inter-examiner agreement was excellent for diagnosis of cartilage defects on all MRAs. The overall sensitivity, specificity, and accuracy for detection of glenoid cartilage lesions by MRA were 69%, 97%, and 80%, respectively.ConclusionT1-weighted volumetric MRA seems to demonstrate cartilage defects accompanied with labrum pathologies accurately with high sensitivity, specificity, and excellent inter-examiner agreement
Synthesis, activatory effects, molecular docking and ADME studies as rabbit muscle pyruvate kinase activators of ureido phenyl substituted 1,4-dihydropyridine derivatives
Get PDFIn this study, the activation of pyruvate kinase enzyme in vitro via different urea substituents in the para position as functional groups of 1,4-dihydropyridine derivatives synthesized by Hantzsch reaction method was investigated. Elemental analysis, 1H-NMR, 13C-NMR and FT-IR spectroscopy were used to identify the ureido phenyl substituted 1,4-dihydropyridine derivatives. Virtual screening based on molecular docking supported the results of possible in vitro pyruvate kinase (PK) activators among the synthesized substances. The results showed that all compounds successfully activated PK. The strongest activator effect was shown by ethyl-4-(4-(4-(3-(3-methoxyphenyl)thioureido)phenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,7,8-hexahydroquinolin-3 (7) with an AC50 value of 87.70 mu M. In molecular docking studies, full compatibility (- 3016.93 FF), binding affinities (Delta G = - 8.58 kcal/mol), LUMO-HOMO energy gap (Delta E = 7.85 eV) in Density functional theory (DFT) studies and drug similarity score of the compounds were found to be 0.69. These results shed light on the therapeutic potential of the produced compounds to treat PK-related diseases
Can Artificial Intelligence Identify Reading Fluency and Level? Comparison of Human and Machine Performance
Get PDFThis study examined whether an artificial intelligence-based automatic speech recognition system can accurately assess students' reading fluency and reading level. Participants were 120 fourth-grade students attending public schools in T & uuml;rkiye. Students read a grade-level text out loud while their voice was recorded. Two experts and the artificial intelligence-based automatic speech recognition system analyzed the recordings for reading errors. Following the analysis, a word error rate was calculated for both the experts and the artificial intelligence-based automatic speech recognition system. Word error rates were converted into reading accuracy rate scores. Inter-rater agreement and linear regression analyses were used to compare the raters' reading fluency scores, and logistic regression analyses were used to compare the classification of readers according to their reading levels. Results showed that the difference between the scores of the artificial intelligence-based automatic speech recognition system and the expert scores was minimal. This is because there was a very high level of agreement between the artificial intelligence-based automatic speech recognition system and the experts scores. Linear regression analyses showed that the artificial intelligence-based automatic speech recognition system significantly predicted the scores of experts. According to the logistic regression analysis results, the artificial intelligence-based automatic speech recognition system was at least 93% as successful as human raters in classifying readers as poor and good. These results give us hope that reading assessments at classroom, school, regional, national, and even international levels can be conducted more accurately and economically by using artificial intelligence-based systems in the coming years
Influencer marketing (etkileyici pazarlama) konulu lisansüstü tezlerin bibliyometrik analizi
Get PDFİnternetin hayatımıza girmesi ile birlikte iletişim teknolojilerinde köklü değişimler yaşanmıştır. İnternet teknolojilerinin hayatımıza kattığı yeniliklerden biri de sosyal medya platformları olarak adlandırılan Facebook, Twitter, Instagram gibi platformlardır. Bu platformlar insanların sosyal hayatlarını etkilediği kadar pazarlama alanını da etkilemiştir. Eskiden geleneksel mecralarda yapılan pazarlama faaliyetleri dijital platformlara kaymaya başlamış ve bu gelişmeler influencer marketing olarak ifade edilen ve Türkçe’ye “nüfuz pazarlama” veya “etkileyici pazarlama” gibi çevirilerle isimlendirilen faaliyet alanının gelişimine katkı sağlamıştır. Günümüzde özellikle pazarlama amaçlı halkla ilişkiler faaliyetlerinin içinde önemli bir yeri olan influencer marketing konusunun Türkiye’deki lisansüstü çalışmalarda nasıl ele alındığını incelemek bu çalışmanın temel amacıdır. Bu bağlamda Türkiye’de YÖK Tez merkezine kayıtlı influencer marketing konulu 38 adet tez bibliyometrik analiz yöntemi kullanılarak analiz edilmiştir. Çalışmada nitel analizler için Nvivo programı kullanılmıştır. Türkiye’de yapılmış lisansüstü çalışmalar analiz edildiğinde tezlerin çoğunun nüfuz pazarlamanın tüketicilerin satın alma davranışına etkisini ölçmeyi amaçladığı görülmüştür. Uluslararası literatürde de çalışmaların büyük çoğunluğunun influencer marketing’in satın almaya etkisi konulu olduğu görülmüş olup lisansüstü çalışmaların uluslararası literatürle paralel ilerlediği görülmüştür. Lisansüstü çalışmaların kuramsal temellerinin “dijital pazarlama”, “WOM” (Ağızdan ağıza pazarlama) bağlamında ele alındığı görülmüştür. Tez çalışmalarının temel bulgularına bakıldığında nüfuz pazarlama tekniği kullanımının tüketicilerin satın alma davranışını olumlu yönde etkilediği ve nüfuz pazarlamanın geleneksel pazarlamadan daha etkili bir teknik olduğu ortak sonuçlarına varıldığı görülmüştür. Lisansüstü çalışmalarda görülen en temel eksikliğin çalışmaların hiçbirinde influencer marketing konusunun olumsuz boyutlarının mesela etik boyutu veya tüketici üzerindeki olumsuz etkisi gibi konulara hiç değinilmediği görülmüştür. Bu bağlamda lisansüstü çalışmalarda en temel eksiklik olarak eleştirel bakış açısından yoksunluk ve konunun sadece egemen yaklaşımlar ve endüstri ve onun çıkarları temelinde ele alınması olduğu görülmüştür
Counter-based security mechanism between mobile application and API services
Get PDFBu çalışma, mobil cihazların geniş kullanımı ve beraberinde getirdiği güvenlik zorluklarına odaklanarak, mobil uygulamalar ile Uygulama Programlama Arabirimi (Application Programming Interface-API) servisleri arasındaki güvenli iletişimi güçlendirmeyi amaçlayan 'cTrust' isimli sayaç tabanlı yenilikçi bir güvenlik mekanizması geliştirmeyi hedeflemektedir. Sayaç tabanlı güvenlik mekanizması, mobil uygulamaların API servisleriyle güvenli bir şekilde iletişim kurabilmesi için kullanılan etkili bir strateji sunmaktadır. Geliştirilen mekanizma, mobil uygulamaların doğrulama süreçlerini başlatır ve tek kullanımlık token bilgisini (cToken) üreterek, sürekli değişen bir doğrulama süreci sunmaktadır. Doğrulama sürecinde kullanılan sayaç bilgisi, gizli anahtar ile şifrelenip sadece API servisi tarafında çözülerek, tek kullanımlık doğrulama mekanizmasının etkinliğini artırmaktadır. Bu strateji, API servislerinin güvenliğini artırmak adına etkili bir çözüm olarak öne çıkmaktadır. Çalışma, mevcut güvenlik yaklaşımlarına alternatif bir bakış açısı sunarak mobil uygulama ve API servisleri arasındaki güvenli etkileşimi sağlamayı amaçlamaktadır. Sayaç mekanizması, geleneksel güvenlik yöntemlerine ek olarak benzersiz bir güvenlik katmanı ekleyerek, saldırılara karşı daha dayanıklı bir yapı oluşturmaktadır. Bu bağlamda, mobil uygulama ve API servisleri arasındaki güvenliği artırarak, dijital iletişimde alternatif bir güvenlik mekanizması sunmayı amaçlamaktadır. Sonuç olarak, mobil uygulamaların ve API servislerinin güvenliği günümüzde kritik bir öneme sahiptir. Sayaç tabanlı güvenlik mekanizması cTrust, güvenliği artırmak için etkili bir çözüm sunmakta ve sektördeki güvenlik standartlarına uygun bir potansiyel içermektedir. Bu çalışma, mobil uygulamalar ile API servisleri arasındaki güvenliği artırmayı amaçlarken aynı zamanda alternatif ve bağımsız bir güvenlik stratejisi sunmayı hedeflemektedir.This study aims to develop an innovative security mechanism called 'cTrust', focusing on the widespread use of mobile devices and the security challenges it brings, to enhance secure communication between mobile applications and Application Programming Interface (API) services. The counter-based security mechanism provides an effective strategy for mobile applications to communicate securely with API services. The developed mechanism initiates authentication processes for mobile applications and generates a one-time token (cToken), offering a continuously changing authentication process. The counter information used in the authentication process is encrypted with a secret key and decrypted only by the API service, thereby enhancing the effectiveness of the one-time authentication mechanism. This strategy stands out as an effective solution to enhance the security of API services. The study aims to provide a secure interaction between mobile applications and API services by offering an alternative perspective to existing security approaches. The counter mechanism adds a unique security layer in addition to traditional security methods, creating a more resilient structure against attacks. In this context, it aims to enhance security between mobile applications and API services and provide an alternative security mechanism in digital communication. Consequently, the security of mobile applications and API services holds critical importance today. The cTrust counter-based security mechanism offers an effective solution to enhance security and holds the potential to comply with industry security standards. While aiming to enhance security between mobile applications and API services, this study also aims to provide an alternative and independent security strategy
Novel Tetrazole And 1,3,4-Oxadiazole Derivatives Synthesis, Molecular Docking, Adme, Potential Activator For Rabbit Muscle Pyruvate Kinase
Get PDF. The activation of muscle pyruvate kinase (PK) increases the conversion of phosphoenolpyruvate (PEP) to pyruvate, which results in the production of ATP. This is critical for supplying the energy needed for muscle contraction. In this study, we synthesized 1,4-dihydropyridine/pyridine compounds bearing tetrazole and 1,3,4-oxadiazole groups by using Hantzsch method and characterized by FT-IR spectroscopy, elemental analysis, and The studies revealed that all original synthesized compounds activated PK and AC50 (half-maximal activating concentration) values of the compounds were extremely effective (1.30 mu M to 14.65 mu M).SCIENTIFIC AND TECHNOLOGICAL RESEARCH INSTITUTION OF TURKEY (TUBITAK)This work was supported by a SCIENTIFIC AND TECHNOLOGICAL RESEARCH INSTITUTION OF TURKEY (TUBITAK) 2209 Project Synthesis of Penta Substituted Pyridine Compounds Containing Alkyl/Aryl and Amino Oxadiazole in the 5 -Position