Stability, electronic and phononic properties of β and 1T structures of SiTex (x = 1, 2) and their vertical heterostructures

By performing first-principles calculations, we predict a novel, stable single layer phase of silicon ditelluride, 1T-SiTe2, and its possible vertical heterostructures with single layer β-SiTe. Structural optimization and phonon calculations reveal that 1T-SiTe2 structure has a dynamically stable ground state. Further analysis of the vibrational spectrum at the - point shows that single layer 1T-SiTe2 has characteristic phonon modes at 80, 149, 191 and 294 cm-1. Electronic-band structure demonstrates that 1T-SiTe2 phase exhibits a nonmagnetic metallic ground state with a negligible intrinsic spinorbit splitting. Moreover, it is shown that similar structural parameters of 1T-SiTe2 and existing β-SiTe phases allows construction of 1T-β heterostructures with a negligible lattice mismatch. In this regard, it is found that two energetically favorable stacking orders, namely AA and ATB, have distinctive shear and layer breathing phonon modes. It is important to note that the combination of semiconducting β-SiTe and metallic 1T-SiTe2 building blocks forms ultra-thin Schottky barriers that can be used in nanoscale optoelectronic device technologies.TUBITAK (116C073--114F397); The Science Academy, Turkey under the BAGEP progra

Monitoring the effect of asymmetrical vertical strain on Janus single layers of MoSSe via vibrational spectrum

Using first principles calculations, we study the structural and phononic properties of the recently synthesized Janus type single layers of molybdenum dichalcogenides. The Janus MoSSe single layer possesses 2H crystal structure with two different chalcogenide sides that lead to out-of-plane anisotropy. By virtue of the asymmetric structure of the ultra-thin Janus type crystal, we induced the out-of-plane anisotropy to show the distinctive vertical pressure effect on the vibrational properties of the Janus material. It is proposed that for the corresponding Raman active optical mode of the Janus structure, the phase modulation and the magnitude ratio of the strained atom and its first neighbor atom adjust the distinctive change in the eigen-frequencies and Raman activity. Moreover, a strong variation in the Raman activity of the Janus structure is obtained under bivertical and univertical strains. Not only eigen-frequency shifts but also Raman activities of the optical modes of the Janus structure exhibit distinguishable features. This study reveals that the vertical anisotropic feature of the Janus structure under Raman measurement allows us to distinguish which side of the Janus crystal interacts with the externals (substrate, functional adlayers, or dopants).TUBITAK (117F095); FLAG-ERA-TRANS2DTM

THE EFFECTS OF CLINICAL, LABORATORY, AND ANGIOGRAPHIC FACTORS ON STENT THROMBOSIS AND MAJOR ADVERSE CARDIAC EVENTS IN PACLITAXEL ELUTING STENTS

Background: Drug-eluting stents (DES) have higher marked efficacy and lower revascularization requirements compared to bare metal stents (BMS). We aimed to determine the mid-term outcomes of patients implanted with first-generation DES “paclitaxel-eluting stents” (PES). Methods: Patients with at least 1 PES implanted in our cardiology clinic were received in the non-randomized group. Inclusion criteria were all patients undergoing percutaneous coronary intervention and PES implantation. The mean follow-up time was 35.14 + 13.4 months. Results: A total of 302 patients (401 lesions and 337 PES) were enrolled in the study. The mean age was 61.86 + 10.27 years. Major adverse cardiac and cerebrovascular events (MACE) occurred at 17.9%, and the stent thrombosis rate was 4%. Independent predictors of stent thrombosis were serum creatinine levels [OR 1.59; 95% CI, 1.03-2.46, p=0.03] and mean platelet volume [OR 1.59; 95% CI, 1.03–2.46, p= 0.03]. Also, poor functional capacity [OR 2.46: 95% CI, 1.42- 4.26, p<0.001] and positive ischemia test [OR 3.43: 95% CI, (1.73-6.82), p<0.001] were predictors of MACE's. Conclusions: We have demonstrated that PES is safe and effective in the mid-term for use in coronary artery disease

Structural, electronic and phononic properties of PtSe2: From monolayer to bulk

The layer dependent structural, electronic and vibrational properties of the 1T phase of two dimensional (2D) platinum diselenide are investigated by means of state-of-the-art first-principles calculations. The main findings of the study are: (i) monolayer platinum diselenide has a dynamically stable 2D octahedral structure with 1.66 eV indirect band gap, (ii) the semiconducting nature of 1T-PtSe2 monolayers remains unaffected even at high biaxial strains, (iii) top-to-top (AA) arrangement is found to be energetically the most favorable stacking of 1T-PtSe2 layers, (iv) the lattice constant (layer-layer distance) increases (decreases) with increasing number of layers, (v) while monolayer and bilayer 1T-PtSe2 are indirect semiconductors, bulk and few-layered 1T-PtSe2 are metals, (vi) Raman intensity and peak positions of the A1g and Eg modes are found to be highly dependent on the layer thickness of the material, hence; the number of layers of the material can be determined via Raman measurements.TUBITAK under the project number 117F09

Protective effects of zingerone against sodium arsenite-induced lung toxicity: A multi-biomarker approach

Objective(s): Sodium arsenite (SA) exposure is toxic to the body. Zingerone (ZNG) is a flavonoid with many biological properties found naturally in honey and plants. This study aimed to determine the effects of ZNG on SA-induced rat lung toxicity.Materials and Methods: Thirty-five male Sprague rats were divided into Control, SA, ZNG, SA+ZNG25, and SA+ZNG50 groups (n=7). SA 10 mg/kg and ZNG were administered at two doses (25 and 50 mg/kg) (orally, 14 days). Analysis of oxidative stress, inflammation damage, apoptosis damage, and autophagic damage markers in lung tissue were determined by biochemical and histological methods. Results: The administration of ZNG reduced oxidative stress by increasing SA-induced decreased antioxidant enzyme activities, increasing Nrf-2, HO-1, and NQO1, and decreasing MDA level. ZNG administration reduced inflammation marker levels. Anti-apoptotic Bcl-2 increased and apoptotic Bax and Caspase-3 decreased with ZNG. ZNG promoted the regression of autophagy by reducing Beclin-1, LC3A, and LC3B levels.Conclusion: Evaluating all data showed that SA caused toxic damage to lung tissue by increasing inflammation, apoptosis, autophagy, and oxidant levels, whereas ZNG had a protective effect by reducing this damage

Mitogenome Phylogeny Including Data from Additional Subspecies Provides New Insights into the Historical Biogeography of the Eurasian lynx Lynx lynx.

Previous molecular studies of the wide-ranging Eurasian lynx Lynx lynx focused mainly on its northern Palearctic populations, with the consequence that the reconstruction of this species' evolutionary history did not include genetic variation present in its southern Palearctic distribution. We sampled a previously not considered Asian subspecies (L. l. dinniki), added published data from another Asian subspecies (L. l. isabellinus), and reassessed the Eurasian lynx mtDNA phylogeny along with previously published data from northern Palearctic populations. Our mitogenome-based analyses revealed the existence of three major clades (A: Central Asia, B: SE Europe/SW Asia, C: Europe and Northern Asia) and at least five lineages, with diversification in Lynx lynx commencing at least 28kyr earlier than hitherto estimated. The subspecies L. l. isabellinus harbors the most basal matriline, consistent with the origin of Lynx lynx in this subspecies' current range. L. l. dinniki harbors the second most basal matriline, which is related to, and may be the source of, the mtDNA diversity of the critically endangered Balkan lynx L. l. balcanicus. Our results suggest that the Anatolian peninsula was a glacial refugium for Eurasian lynx, with previously unconsidered implications for the colonization of Europe by this species

The Effect Of Different Mineral Binder Constituents On Durability Of Concrete

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2014Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2014Bu çalışmada farklı türden ve farklı dozajlarda kullanılan mineral bağlayıcı bileşenlerin betonun dayanımına ve kalıcılığına (durabilitesine) olan etkisi incelendi. Ülkemizde betonda çimento ile beraber kullanılan farklı kaynaklardan temin edilmiş öğütülmüş granüle yüksek fırın cürufu (Ö.G.Y.F.C.) ve uçucu kül (UK) ile betonlar üretildi. Deneylerde 2 farklı kaynaktan temin edilen öğütülmüş granüle yüksek fırın cürufu (Ö.G.Y.F.C.), başka bir kaynaktan temin edilmiş öğütülmüş fırın cürufu ve tek kaynaktan temin edilen tek tip uçucu kül (UK), farklı miktarlarda kullanılarak, farklı özellikte numuneler elde edildi. Aynı zamanda çimento da farklı dozajlarda kullanıldı. Üretilen beton numune sınıfları C30/37 olup tüm numunelerde Su/Bağlayıcı oranı birbirine oldukça yaklaşık veya aynı tutuldu. Çökme ile ölçülen kıvam seviyesi aynı yapıldı. Üretilen numune karışımlarından, sülfat etkisi deneyleri için 3 er 70 mm•70 mm•280 mm boyutlarında prizmalar üretildi. Ayrıca basınç dayanımı deneyi için 6 adet, hızlı klorür geçirimliliği deneyi için 1 adet ve kılcal su emme deneyi için 1 adet olmak üzere toplam 8 adet 100 mm çapında 200 mm yüksekliğinde silindir beton numuneleri üretildi. Numuneler 20 °C ± 2°C, kirece doygun su içerisinde bekletilerek kür işlemi yapıldı. 7. ve 28. günlerde basınç dayanımları tespit edildi. 90 günün sonunda kılcallık deneyleri ve ASTM C 1202 standardına uygun olarak hızlı klorür geçirimliliği deneyleri yapıldı. Prizmalar ise 28 günlük kür işleminden sonra sülfat etkisi için magnezyum sülfat (MgSO4) çözeltisinde bekletildi. Ultra-ses hızı ölçümleri, ağırlık değişim ölçümleri belirli periyotlarda yapıldı. Fakat ultra-ses hızları kararlı bir artış veya azalış göstermedi ve deneysel çalışma süresi içerisinde yoruma elverişli sonuç elde edilemedi. Bunun yanında ağırlık değişimi çalışmanın amacına yönelik yorumlar yapılmasına elverişli eğilimler gösterdi. Hızlı klorür geçirimliliği deney sonuçları öğütülmüş granüle yüksek fırın cürufunun (Ö.G.Y.F.C.) ve uçucu külün (UK) betonun geçirimliliğini azalttığını gösterdi. Fakat buna rağmen magnezyum sülfat etkisi sonunda öğütülmüş granüle yüksek fırın cürufunun (Ö.G.Y.F.C.) kullanıldığı numunelerde basınç dayanımlarındaki artışın azaldığı, hatta bir beton numunesinde basınç dayanımının düştüğü tespit edildi. Ö.G.Y.F.C. kullanılan A200+120 ve B200+100 numunelerinde bağıl ağırlık değişimlerinde azalma görüldü. Uçucu külün betonun geçirimliliğini azalttığı basınç dayanımını arttırdığı gözlemlendi. Uçucu külün kullanıldığı beton numunelerde sülfat etkisine maruz kaldıktan sonra da basınç dayanımı artışı devam etti. Genel anlamda, bu çalışmadan elde edilen sonuçlar uçucu külün de betonun kalıcılığını (durabilitesini) iyileştirdiğini göstermektedirIn this research, different mineral constituents, in different dosages, effects on the strength and durability of concrete was investigated. In Turkey, cement and ground granulated blast furnace slag (G.G.B.S) and fly ash (FA) of different sources are used in concrete production usually in combination with CEM I. In this work, G.G.B.S. from three different sources and only one type of FA were used in various dosages to obtain different concretes as partial replacement of CEM I. The concrete strength class was set at C30/37 and the same Water/Binder ratio was used. Consistency, as measured by slump, was set at 155 mm ± 5 mm. Three 70 mm•70 mm•280 mm prism specimens were prepared for the sulphate effect test for each concrete. In addition, a total of 8 cylindrical specimens of 100 mm diameter and 200 mm height were produced, 6 for compressive strength test, one for rapid chloride permeability, one for capillary water absorption tests. All specimens were kept in tanks under water at 20 °C ± 2°C prior to tests and testing conditions. The strength tests were performed at seventh and twenty eighth days. The rapid chloride penetration and capillary water absorption tests were performed at the age of 90 days in compliance with ASTM C 1202 . The prisms were immersed in magnesium sulphate (MgSO4) solution after 28-day water curing. The prisms were tested for ultrasonic pulse velocity and weight changes, periodically. The pulse velocities did not folow any trend parallel to the expected sulphate attack. On the other hand, the weight changes gave indications of sulphate action. The rapid chloride penetration test showed that the ground granulated blast-furnace slag (G.G.B.S) and fly ash (FA) have favourable effect on concrete permeability. On the other hand, G.G.B.S. caused a reduction in compressive strength and weight due to sulphate action. The test results of A200+120 and B200+120 samples, containing crushed granulated hearth cinder, effected decrease in weights. The data showed that fly ash caused a decrease in concrete permeability, while it resulted in an increase in compressive strength, also after the sulphate effect. In brief, it is clear that FA improved the durability of concrete.Yüksek LisansM.Sc

Bilayers of Janus WSSe: Monitoring the stacking type: Via the vibrational spectrum

Motivated by the recent successful synthesis of Janus type single layers of transition metal dichalcogenides, we investigate the stability, vibrational and electronic properties of the Janus single layer structure of WSSe and its bilayers by means of density functional theory. The structural and vibrational analysis show that the Janus single layer of WSSe forms a dynamically stable structure in the 2H phase. Owing to its non-centrosymmetric structure, the Janus WSSe single layer has two in-plane (E) and two out-of-plane (A) Raman active phonon modes. The eigen-frequencies of the prominent Raman active modes are calculated to be 277 (A) and 322 (E) cm-1. Similar to single layer WS2 and WSe2, Janus WSSe is a direct band gap semiconductor that has two electronically different faces. In addition, the possible bilayer stacking orders of the Janus WSSe single layers are investigated. It is found that there are 3 stacking types of bilayer Janus WSSe and each stacking type has distinctive Raman characteristics in its vibrational spectrum. Our results show that thanks to the vibrational characteristics, which stem from the distinctive interlayer interactions at different sides, the stability and stacking types of the bilayer of WSSe Janus structure can be monitored.TUBITAK ULAK-BIM, the High Performance and Grid Computing Center (TR-Grid e-Infrastructure) and TUBITAK project number 117F09