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Öğe Anesthetic management for cesarean birth in pregnancy with the novel coronavirus (COVID-19)(Elsevier Science Inc, 2020) Yilmaz, Resul; Kilic, Fatma; Arican, Sule; Hacibeyoglu, Gulcin; Suslu, Halime; Koyuncu, Mustafa; Uzun, Sema Tuncer[Abstract Not Availabe]Öğe Investigation of electrical properties of Al/LiCoO2/n-Si photodiode by ultrasonic spray pyrolysis method(Springer Heidelberg, 2023) Hussaini, Ali Akbar; Erdal, Mehmet Okan; Doğan, Kemal; Koyuncu, Mustafa; Yıldırım, Murathere has been rising concentration on the photodiode properties of the MS devices in recent years to improve the perfor mance of light sensing devices. Therefore, in this study, LiCoO2 was synthesized via sol–gel-based electrospinning method and it is used as interlayer between Al and n-type Si to fabricate Al/LiCoO2/n-Si photodiode via ultrasonic spray pyrolysis and physical vapor deposition methods. LiCoO2 thin flm was characterized via XRD, SEM and AFM. Crystallite size for LiCoO2 was found to be 37.75 nm. Electrical characterization was performed by current–voltage (I−V) and current-transient (I−t) measurements using solar simulator under dark and various illumination conditions. I−V characteristics demonstrated that the Al/LiCoO2/n-Si exhibited good photodiode behavior and a high rectifying ratio. Moreover, LiCoO2-interlayered device has shown signifcant responsivity and detectivity. It has shown 1.79× 1010 Jones detectivity and 0.364 A/W responsivity at 100 mW light power. Thus, the results demonstrate that a device based on LiCoO2 can be employed in optoelectronic applications.Öğe The modification of the characteristics of ZnO nanofibers by TCNQ doping content(Springer, 2021) Erdal, Mehmet Okan; Koyuncu, Mustafa; Dogan, Kemal; Ozturk, Teoman; Kocyigit, Adem; Yildirim, MuratIn this study, the electrical properties of an Al/p-Si metal/semiconductor photodiodes with Tetracyanoquinodimethane-Polyvinyl chloride (TCNQ-PVC) and PVC-TCNQ:ZnO interfacial layers were investigated. Growing of the interfacial layers on p-Si were fulfilled using electrospinning method as a fiber form. Al metallic and ohmic contacts were deposited via physical vapor deposition method. Scanning electron microscopy (SEM) pictures of the devices were captured to examine the morphology of the structure. Within the scope of electrical characterization, I-V measurements of the Al/PVC-TCNQ/p-Si and Al/PVC-TCNQ:ZnO/p-Si devices were accomplished both in the dark and under illumination conditions. Various device parameters, such as ideality factor and barrier height values were determined from I-V characteristics. Although the ideality factor values were obtained as 8.47 and 6.85 for undoped and ZnO-doped Al/PVC-TCNQ/p-Si diodes, the barrier height values were calculated as 0.84 for both devices. When a comparison was made between ZnO doped and undoped Al/PVC-TCNQ/p-Si diodes, it was evaluated that the rectification and photoresponse properties of the heterojunction diode was improved with ZnO dopant.Öğe The role of right ventricular volumes and inferior vena cava diameters in the evaluation of volume status before colonoscopy(Tubitak Scientific & Technological Research Council Turkey, 2019) Arican, Sule; Dertli, Ramazan; Dagli, Cagdas; Hacibeyoglu, Gulcin; Koyuncu, Mustafa; Topal, Ahmet; Tuncer Uzun, SemaBackground/aim: Ultrasonographic measurements of inferior vena cava (IVC) diameters and right ventricle (RV) volumes are important tools for the evaluation of intravascular volume. The current study investigates the association of IVC diameters and RV volumes before colonoscopy in prediction of postanesthesia hypotension. Materials and methods: Seventy patients scheduled for colonoscopy were included in the study. Preoperatively, expirium (dIVC tnax) and inspirium (dIVC min) IVC diameters were measured using M-mode ultrasonography and the collapsibility index (IVC-CI) was calculated. Ventricular volumes and areas were also measured using transthoracic echocardiography. Postanesthesia hypotension was defined as mean arterial blood pressure of <60 mm Hg or a decrease of >30% in the mean arterial pressure after sedation. Results: Minimum and maximum IVC diameters were significantly lower (P = 0.005 and P < 0.001, respectively) and IVC-CI was significantly higher (P < 0.001) in patients who developed hypotension. Similarly, right ventricular end-diastolic area (RV-EDA), right ventricular end-systolic area (RV-ESA), right ventricular end-diastolic volume (RV-EDV), right ventricular end-systolic volume ( RVESV), and left ventricular end-systolic volume (LV-ESV) values were significantly lower in patients with hypotension (P < 0.05). Logistic regression analysis showed that dIVC min and RV-ESA were independent predictors of hypotension. Conclusion: IVC diameters and RV-ESA, RV-EDA, RV-ESV, and RV-EDV are good indicators of preoperative volume status and can be used to predict the patients at risk of developing hypotension.Öğe Sağ internal juguler ven distansibilite indeksinin sistolik basınç değişimi ve nabız basıncı değişimi ile korelasyonu(Necmettin Erbakan Üniversitesi Meram Tıp Fakültesi, 2020) Koyuncu, Mustafa; Topal, AhmetBu çalışmada sağ internal juguler ven distansibilite indeksinin hastaların sıvı durumu değerlendirmesinde kullanılabilirliğini belirlemeyi amaçladık. Yöntem: Bu çalışmaya, Necmettin Erbakan Üniversitesi Meram Tıp Fakültesi Genel cerrahi kliniği tarafından supin nötral pozisyonda, total gastrektomi ve subtotal gastrektomi yapılan hastalar dahil edildi. Hastaların baş yüksekliği 15° olarak ayarlandı. Hastaların ASA (American Society of Anaesthesiologists) sınıflaması I-II-III yaşları 18-65 arasında yazılı onamları alınan, preoperatif açlık süresi yaklaşık 10 saat olanlar değerlendirmeye dahil edildi. Hastalara invaziv arter monitörizasyonu yapıldı. 8 mg/kg tidal volum ile mekanik ventile edilen 96 hasta belirlendi. SPV (sistolik basıç değişimi), PPV (nabız basıncı değişimi), sağ internal juguler ven inspiryum çapı (dİ), sağ internal juguler ven ekspiryum çapı (dE) ölçülerek verileri kaydedildi. Sağ internal juguler ven distansibilite indeksi (SİJV-Dİ) =(dİ-dE)/[(dİ+dE)/2 ]×100 formülü kullanılarak hesaplandı; SİJV-Dİʼnin SPV ve PPV verileri ile koralasyonu incelendi. Bulgular: SİJV-Dİ ile PPV arasında pozitif yönlü güçlü korelasyon mevcuttu. ( r=+0,72) (p <0,001). RİJV-Dİ ile SPV arasında pozitif yönlü güçlü korelasyon mevcuttu. ( r=+0,55) (p<0,001). AUC (Eğri altında kalan alan): 0.882, %95 Cl:0.809-0.955, p<0.001). ROC eğrisi analizi ile distansibilite indeksinin sıvı açığını göstermede cut-off değeri % 13,5 olarak bulundu ve sensitivite ve spesifite sırasıyla %74.4-%81,8 olarak bulduk. Sonuç: Çalışmamızda SİJV-Dİ'nin mekanik ventilatör ile solutulan hastalarda sıvı durumu değerlendirmesinde güvenilir hızlı sonuçlar verdiği kanısına vardık. SİJV-Dİ'nin yatak başında sıvı durumu değerlendirmesinde PPV ve SPV gibi invaziv ölçüm yöntemlerine alternatif veya destekleyici bir yöntem olarak kullanılabileceğini düşünmekteyiz Anahtar kelimeler: İnternal juguler ven, internal juguler ven distansibilite indeksi, nabız basıncı değişimi, sistolik basınç değişimiÖğe Takayasu Arteritine Bağlı Serebral Perioperatif Komplikasyonları Önlemede Near Infrared Spectroscopy Kullanımı(2017) Topal, Ahmet; Türk, Şeyda; Tosun, Osman Mücahit; Karaarslan, Esma; Koyuncu, Mustafa; Koç, Hasan U.; Tavlan, AybarsTakayasu arteriti (TA); idiyopatik, kronik inflamatuvar, aorta ve dallarını tutabilen nadir bir hastalıktır. %80 oranında 40 yaşın altındaki kadınlarda görülür. TA aynı zamanda periferik nabızların alınamaması ile karakterizedir. TA hastalarının anestezi yönetimi ile ilgili bilgiler, literatürde çoğunlukla sezaryen vakaları olmak üzere, izole olgu sunumları ile sınırlıdır. Bu olgu sunumunda TA’li 69 yaşında bilateral karotis, pulmoner arter ve subklavian arter tutulumu olan, laparoskopik kolesistektomi operasyonu geçirecek hastamızda Near Infrared Spectroscopy (NIRS) gibi ileri monitörizasyon yöntemi uygulanmış, TA’ya bağlı olası postoperatif komplikasyonların önlenmesi ve uygun anestezi yönetiminin seçilmesi amaçlanmıştır.Öğe Thermoelectric Properties of Nickel and Boron Co-Substituted NaCo2O4 Prepared by Electrospinning Technique(Trans Tech Publications Ltd, 2018) Erdal, Mehmet Okan; Koyuncu, Mustafa; Aksu, M. Levent; Uslu, Ibrahim; Kocyigit, SerhatIn this study nickel and boron doped sodium cobalt oxide NaCo2-xNixByO4 (0 <= x <= 0.3, 0 <= y <= 0.1) nanocrystalline thermoelectric ceramic powders were synthesized using electrospinning techniques and then consolidated into bulk ceramics. The differences in the microstructure and thermoelectric properties of the samples as a result of doping effect have been investigated. The crystalline structures of the powders and nanofibers were characterized using Xray diffraction and scanning electron microscopy and BET Analysis before and after the calcination process at different temperatures. Nanofibers prepared by the use of electrospinning technique, have a diameter of approximately 300 nm, and the diameter of the grains of calcined powders was observed to range between 150 to 500 nanometers. Thermoelectric properties of the bulk ceramics were measured by physical properties measurement system (Lot-Oriel PPMS) in a temperature range of 15-300 K. The calculated values of dimensionless figure of merit at 300 K are 4.25 x 10(-5), 5.3 x 10(-6), 8.6 x 10(-5) and 9 x 10(-6) for sintered powders from undoped, Ni and B doped powders, respectively.
