المؤلفون: Yuce, Hurriyet, Mandal, Mukunda, Yalcinkaya, Yenal, Andrienko, Denis, Demir, Mustafa M.

مصطلحات موضوعية: Physics - Applied Physics, Condensed Matter - Materials Science

الوصف: All-inorganic lead halide perovskite nanocrystals (NCs) show potential in optoelectronic devices, though their stability and efficiency have yet to improve. In this work, we explore the effect of bivalent metal site doping on the optoelectronic properties of CsPbX$_3$ (X = Br, Cl) perovskite NCs. First, the Pb$^{2+}$ ions in pristine CsPbBr$_3$ NC are partially substituted by Mn$^{2+}$ ions, and the alkaline earth metal strontium is then doped on both pristine and Mn$^{2+}$-substituted particles. The structural and photophysical properties of the pristine and the three doped NC variants have been investigated experimentally as well as exploiting first principles calculations. We found that a small percentage of Sr$^{2+}$-doping improved the photoluminescence quantum yield of the pristine particle by 8%, while it improved the Mn$^{2+}$-state emission by 7%. Perovskite NC film/poly(methyl methacrylate) composites with all four NC variants were used in a white light-emitting diode (WLED) and again both Sr$^{2+}$ doped NCs were found to increase the luminous efficiency of the WLED by ca 4 %. We attribute this performance enhancement to a reduced defect density as well as an attenuated microstrain in the local NC structure.

الوصول الحر: http://arxiv.org/abs/2201.12067Test

المؤلفون: Tonkul, Serhat, Baba, Alper, Demir, Mustafa M., Regenspurg, Simona

المصدر: Geothermics 96 (2021) 102227

مصطلحات موضوعية: Physics - Geophysics

الوصف: Turkey is located on the seismically active Alpine-Himalayan belt. Although tectonic activity causes seismicity in the Anatolian plate, it also constitutes an important geothermal energy resource. Today, geothermal energy production is heavily concentrated in Turkey's Western Anatolia region. Graben systems in this region are very suitable for geothermal resources. The B\"uy\"uk Menderes Graben (BMG) is an area of complex geology with active tectonics and high geothermal potential power. Germencik (Aydin) is located in the BMG, where the geothermal waters include mainly Na-Cl-HCO3 water types. This study examined the stibnite scaling formed in the preheater system of the Germencik Geothermal Field (GGF). The formation of the stibnite scaling on the preheater system dramatically reduces the energy harvesting of the GGF. Considering the stibnite scaling in the surface equipment, the optimum reinjection temperature was determined as 95 $^\circ$C to prevent stibnite scaling in the GGF.

الوصول الحر: http://arxiv.org/abs/2111.06626Test

المؤلفون: Sinha, Aish, Dutta, Utkarsh, Demir, Ozan M., De Silva, Kalpa, Ellis, Howard, Belford, Samuel, Ogden, Mark, Li Kam Wa, Matthew, Morgan, Holly P., Shah, Ajay M., Chiribiri, Amedeo, Webb, Andrew J., Marber, Michael, Rahman, Haseeb, Perera, Divaka

المصدر: Sinha , A , Dutta , U , Demir , O M , De Silva , K , Ellis , H , Belford , S , Ogden , M , Li Kam Wa , M , Morgan , H P , Shah , A M , Chiribiri , A , Webb , A J , Marber , M , Rahman , H & Perera , D 2024 , ' Rethinking False Positive Exercise Electrocardiographic Stress Tests by Assessing Coronary Microvascular Function ' , Journal of the American College of Cardiology , vol. 83 , no. 2 , pp. 291–299 ....

مصطلحات موضوعية: Humans, Female, Middle Aged, Aged, Male, Exercise Test, Coronary Artery Disease/diagnosis, Acetylcholine, Electrocardiography, Myocardial Ischemia/diagnosis, Vascular Diseases, Ischemia

الوصف: Background: Exercise electrocardiographic stress testing (EST) has historically been validated against the demonstration of obstructive coronary artery disease. However, myocardial ischemia can occur because of coronary microvascular dysfunction (CMD) in the absence of obstructive coronary artery disease. Objectives: The aim of this study was to assess the specificity of EST to detect an ischemic substrate against the reference standard of coronary endothelium-independent and endothelium-dependent microvascular function in patients with angina with nonobstructive coronary arteries (ANOCA). Methods: Patients with ANOCA underwent invasive coronary physiological assessment using adenosine and acetylcholine. CMD was defined as impaired endothelium-independent and/or endothelium-dependent function. EST was performed using a standard Bruce treadmill protocol, with ischemia defined as the appearance of ≥0.1-mV ST-segment depression 80 ms from the J-point on electrocardiography. The study was powered to detect specificity of ≥91%. Results: A total of 102 patients were enrolled (65% women, mean age 60 ± 8 years). Thirty-two patients developed ischemia (ischemic group) during EST, whereas 70 patients did not (nonischemic group); both groups were phenotypically similar. Ischemia during EST was 100% specific for CMD. Acetylcholine flow reserve was the strongest predictor of ischemia during exercise. Using endothelium-independent and endothelium-dependent microvascular dysfunction as the reference standard, the false positive rate of EST dropped to 0%. Conclusions: In patients with ANOCA, ischemia on EST was highly specific of an underlying ischemic substrate. These findings challenge the traditional belief that EST has a high false positive rate.

وصف الملف: application/pdf

الإتاحة: https://doi.org/10.1016/j.jacc.2023.10.034Test
https://kclpure.kcl.ac.uk/portal/en/publications/f842774a-32e7-47ac-9050-ad8cd509beefTest
https://kclpure.kcl.ac.uk/ws/files/246764302/Rethinking_False_Positive_Exercise_SINHA_Publishedonline8January2024_GOLD_VoR_CC_BY_.pdfTest
http://www.scopus.com/inward/record.url?scp=85181234795&partnerID=8YFLogxKTest

المؤلفون: Sinha, Aish, Rahman, Haseeb, Rajani, Ronak, Demir, Ozan M., Li KamWa, Matthew, Morgan, Holly, Ezad, Saad M., Ellis, Howard, Hogan, Dexter, Gulati, Ankur, Shah, Ajay M., Chiribiri, Amedeo, Webb, Andrew J., Marber, Michael, Perera, Divaka

المساهمون: UKRI | Medical Research Council

المصدر: Circulation: Cardiovascular Interventions ; volume 17, issue 1 ; ISSN 1941-7640 1941-7632

الوصف: BACKGROUND: Myocardial bridges (MBs) are prevalent and can be associated with acute and chronic ischemic syndromes. We sought to determine the substrates for ischemia in patients with angina with nonobstructive coronary arteries and a MB in the left anterior descending artery. METHODS: Patients with angina with nonobstructive coronary arteries underwent the acquisition of intracoronary pressure and flow during rest, supine bicycle exercise, and adenosine infusion. Coronary wave intensity analysis was performed, with perfusion efficiency defined as accelerating wave energy/total wave energy (%). Epicardial endothelial dysfunction was defined as a reduction in epicardial vessel diameter ≥20% in response to intracoronary acetylcholine infusion. Patients with angina with nonobstructive coronary arteries and a MB were compared with 2 angina with nonobstructive coronary arteries groups with no MB: 1 with coronary microvascular disease (CMD: coronary flow reserve, <2.5) and 1 with normal coronary flow reserve (reference: coronary flow reserve, ≥2.5). RESULTS: Ninety-two patients were enrolled in the study (30 MB, 33 CMD, and 29 reference). Fractional flow reserve in these 3 groups was 0.86±0.05, 0.92±0.04, and 0.94±0.05; coronary flow reserve was 2.5±0.5, 2.0±0.3, and 3.2±0.6. Perfusion efficiency increased numerically during exercise in the reference group (65±9%–69±13%; P =0.063) but decreased in the CMD (68±10%–50±10%; P <0.001) and MB (66±9%–55±9%; P <0.001) groups. The reduction in perfusion efficiency had distinct causes: in CMD, this was driven by microcirculation-derived energy in early diastole, whereas in MB, this was driven by diminished accelerating wave energy, due to the upstream bridge, in early systole. Epicardial endothelial dysfunction was more common in the MB group (54% versus 29% reference and 38% CMD). Overall, 93% of patients with a MB had an identifiable ischemic substrate. CONCLUSIONS: MBs led to impaired coronary perfusion efficiency during exercise, which was due to diminished ...

الإتاحة: https://doi.org/10.1161/circinterventions.123.013657Test

المؤلفون: Sinha, Aish, Rahman, Haseeb, Douiri, Abdel, Demir, Ozan M., De Silva, Kalpa, Clapp, Brian, Webb, Ian, Gulati, Ankur, Pinho, Pedro, Dutta, Utkarsh, Ellis, Howard, Shah, Ajay M., Chiribiri, Amedeo, Marber, Michael, Webb, Andrew J., Perera, Divaka

المصدر: Circulation ; volume 149, issue 1, page 36-47 ; ISSN 0009-7322 1524-4539

الوصف: BACKGROUND: Angina with nonobstructive coronary arteries is a common condition for which no effective treatment has been established. We hypothesized that the measurement of coronary flow reserve (CFR) allows identification of patients with angina with nonobstructive coronary arteries who would benefit from anti-ischemic therapy. METHODS: Patients with angina with nonobstructive coronary arteries underwent blinded invasive CFR measurement and were randomly assigned to receive 4 weeks of amlodipine or ranolazine. After a 1-week washout, they crossed over to the other drug for 4 weeks; final assessment was after the cessation of study medication for another 4 weeks. The primary outcome was change in treadmill exercise time, and the secondary outcome was change in Seattle Angina Questionnaire summary score in response to anti-ischemic therapy. Analysis was on a per protocol basis according to the following classification: coronary microvascular disease (CMD group) if CFR<2.5 and reference group if CFR≥2.5. The study protocol was registered before the first patient was enrolled (International Standard Randomised Controlled Trial Number: ISRCTN94728379). RESULTS: Eighty-seven patients (61±8 years of age; 62% women) underwent random assignment (57 CMD group and 30 reference group). Baseline exercise time and Seattle Angina Questionnaire summary scores were similar between groups. The CMD group had a greater increment (delta) in exercise time than the reference group in response to both amlodipine (difference in delta, 82 s [95% CI, 37–126 s]; P <0.001) and ranolazine (difference in delta, 68 s [95% CI, 21–115 s]; P =0.005). The CMD group reported a greater increment (delta) in Seattle Angina Questionnaire summary score than the reference group in response to ranolazine (difference in delta, 7 points [95% CI, 0–15]; P =0.048), but not to amlodipine (difference in delta, 2 points [95% CI, –5 to 8]; P =0.549). CONCLUSIONS: Among phenotypically similar patients with angina with nonobstructive coronary arteries, only ...

الإتاحة: https://doi.org/10.1161/circulationaha.123.066680Test

المؤلفون: Demir S. M., Marzano L., Ros P. M., Fachechi L., Demarchi D., De Vittorio M.

المساهمون: Demir, S. M., Marzano, L., Ros, P. M., Fachechi, L., Demarchi, D., De Vittorio, M.

مصطلحات موضوعية: wearable device, piezoelectric sensor, aluminum nitride, remote health monitoring, heart sound, heart rate, respiration, deglutition

الوصف: Remote monitoring of vital body signals has drawn the attention of late, particularly with the burst of COVID-19. Wearable devices are started to be widely used for non-invasive health monitoring tasks. This work presents a wearable system for multiple body signal monitoring using only one biocompatible aluminum nitride piezoelectric sensor and a custom wireless electronic device for data acquisition and transmission. The proposed sensor has been customized for the suprasternal notch, where we can simultaneously extract heart rate, respiration rate, and deglutition events. These parameters are helpful for the remote diagnosis of multiple diseases like cardiac arrhythmia, asthma, and dysphagia. Moreover, heart sound components have been derived from the same signal, providing critical information about heart health and insight into possible heart diseases. The preliminary experimental results show that the proposed wearable system can be used for personalized healthcare applications and offers a promising solution for unobtrusive remote health monitoring.

وصف الملف: ELETTRONICO

العلاقة: info:eu-repo/semantics/altIdentifier/isbn/978-1-6654-5109-3; info:eu-repo/semantics/altIdentifier/wos/WOS:001038214600007; ispartofbook:International Symposium on Circuits and Systems; IEEE International Symposium on Circuits and Systems (ISCAS) 2023; volume:2023; firstpage:1; lastpage:5; numberofpages:5; serie:IEEE INTERNATIONAL SYMPOSIUM ON CIRCUITS AND SYSTEMS PROCEEDINGS; https://hdl.handle.net/11583/2982087Test; info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-85167710267; https://ieeexplore.ieee.org/abstract/document/10181333Test

الإتاحة: https://doi.org/10.1109/ISCAS46773.2023.10181333Test
https://hdl.handle.net/11583/2982087Test
https://ieeexplore.ieee.org/abstract/document/10181333Test

المؤلفون: Guner, Tugrul, Kus, Anilcan, Ozcan, Mehmet, Genc, Aziz, Sahin, Hasan, Demir, Mustafa M.

مصطلحات موضوعية: Condensed Matter - Materials Science

الوصف: Phosphors serve as color conversion layers to generate white light with varying optical features including CRI, CCT, and luminous efficacy. However, they have been produced in harsh synthesis conditions such as high temperature, high pressure, and/or employing a huge amount of solvents. In this work, facile, water-based and a rapid method has been proposed to fabricate lanthanide doped hydroxide-based phosphors. In this sense, submicrometer-sized Y(OH)3:Eu3+ particles, as red phosphor, were synthesized in water at ambient conditions in <60 min reaction time. The doping ratio is controlled from 2.5 to 20% in terms of mole. Meanwhile, first principle calculations were also performed on Y(OH)3:Eu3+ to understand the preferable doping scenario and its optoelectronic properties. As an application, these fabricated red phosphors were integrated into PDMS/YAG:Ce3+ composite to generate white light. The resulting white light showed a remarkable improvement (~24%) for LER, a slight reduction of CCT (from 3900K to 3600K), and an unchanged CRI (~60) as the amount of Y(OH)3:Eu3+ increases.

الوصول الحر: http://arxiv.org/abs/1811.09478Test

المؤلفون: Sezgin, Serra, Binark, Mutlu, Demir, Erman M., Özsu, Gökçe

المصدر: REFLEKTIF Journal of Social Sciences; Vol. 4 No. 3 (2023): October; 723-735 ; REFLEKTİF Sosyal Bilimler Dergisi; Cilt 4 Sayı 3 (2023): Ekim; 723-735 ; 2718-0344 ; 2717-9842

مصطلحات موضوعية: reflexive formation, story, research problematic, field, sharing with the academic community, düşünümsel teçhizatlanma, hikâye, araştırma sorunsalı, saha, akademik topluluk ile paylaşım

الوصف: In this study, we describe how the phenomenon of platformization in the music industry in Turkey is understood by different actors of the industry, the story of our research, our questions, our field preparation, our field experience, where and with whom we shared the research. This storytelling is an attempt at a reflexive approach to research, and it can be an eye-opener for new researches in discussing the creative industries, especially the music industry, at the intersection of cultural political economy and cultural policy. As a researcher, what we have learned in this process has also led us to new questions and phenomena for creative industry and cultural policy studies. ; Bu çalışmada Türkiye’de müzik endüstrisinde platformlaşma olgusunun endüstrinin farklı aktörleri tarafından nasıl kavrandığını, araştırmamızın hikâyesini, sorularımızı, saha hazırlığımızı, saha deneyimimizi, araştırmayı nerede ve kimlerle nasıl paylaştığımızı anlatıyoruz. Bir araştırmaya düşünümsel bakış denemesi olan bu hikâyelendirmenin, yaratıcı endüstrileri ve özellikle müzik endüstrini kültürel ekonomi politik ve kültür politikası kesişiminde tartışmada yeni araştırmalar için zihin açıcı olabileceğini düşünüyoruz. Araştırmacı olarak bu süreçte öğrendiklerimiz bizi de yaratıcı endüstri ve kültür politikaları çalışmaları için yeni sorulara ve olgulara yönlendirdi.

وصف الملف: application/pdf

العلاقة: https://dergi.bilgi.edu.tr/index.php/reflektif/article/view/266/169Test; https://dergi.bilgi.edu.tr/index.php/reflektif/article/view/266Test

الإتاحة: https://doi.org/10.47613/reflektif.2023.135Test
https://dergi.bilgi.edu.tr/index.php/reflektif/article/view/266Test

المؤلفون: Tokkan, Melike, Demir, Mustafa M., Adem, Umut

مصطلحات موضوعية: Polymer nanocomposites, Nanoparticles, Electrocaloric effect, Ferroelectricity, BaTiO3, Fillers

الوصف: We report on the enhancemenent of electrocaloric effect in solution cast polymer nanocomposites based on Poly (vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE) 55-45] with Ca and Sn co-substituted BaTiO3 ceramic fillers (Ba0.94Ca0.06Ti0.925Sn0.075O3, BCST). Saturated hysteresis loops and normal ferroelectric behaviour of the copolymer-based nanocomposites-as opposed to the relaxor ferroelectric nature of the terpolymer-based ones-allow the utilization of the indirect method to estimate the electrocaloric properties. Both the dielectric constant and electrocaloric temperature change (AT) increases as the particle content increases. Maximum adiabatic temperature change was obtained as 6.96 K under 900 kV/cm for the 10 vol % BCST containing polymer composite around the Curie temperature of the copolymer (70 degrees C). This relatively large electrocaloric strength is slightly lower than those obtained for terpolymer-based nanocomposites. ; This work is supported IZTECH Scientific Research Funds with the project number BAP2019IYTE0249. We acknowledge IZTECH Center for Materials Research for the use of XRD and SEM instruments, Geothermal Energy Research and Application Center for the DSC and Biotechnology and Bioengineering Application and Research Center for the FTIR measurements. We also thank Ceren As ? k?n and Prof. Ender Suvac? for the complementary XRD measurements.

العلاقة: Ceramics International; Makale - Uluslararası Hakemli Dergi - Kurum Öğretim Elemanı; https://doi.org/10.1016/j.ceramint.2022.09.275Test; https://hdl.handle.net/11147/12872Test; 49; 2904; 2910; WOS:000904718200001; 2-s2.0-85139300957

الإتاحة: https://doi.org/10.1016/j.ceramint.2022.09.275Test
https://hdl.handle.net/11147/12872Test

المؤلفون: Imaoka, Takuro, Mitomo, Satoru, Demir, Ozan M., Nakamura, Sunao

المصدر: JACC: Case Reports ; volume 24, page 102044 ; ISSN 2666-0849

مصطلحات موضوعية: Cardiology and Cardiovascular Medicine

الإتاحة: https://doi.org/10.1016/j.jaccas.2023.102044Test
https://api.elsevier.com/content/article/PII:S2666084923003789?httpAccept=text/xmlTest
https://api.elsevier.com/content/article/PII:S2666084923003789?httpAccept=text/plainTest