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Fragility or habitualized corporate behavior? Corporate and macroeconomic determinants of debt dollarization: Evidence from Turkey
No full textThis study examines the firm-level and macroeconomic-level determinants of debt dollarization, which is a critical vulnerability for a key emerging market: Turkey. The study examines the firm-level and macroeconomic determinants of debt dollarization between 2005 and 2017 using the generalized method of moments and the panel vector autoregressive method, both of which are highly innovative. The results show that manufacturing firms tend to dollarize debt, while macroeconomic variables such as the real exchange rate, inflation, and credit expansion significantly affect debt dollarization. Moreover, debt dollarization was found to be a habit of manufacturing firms in the Turkish economy.Adana Alparslan Trkescedil; Science and Technology University Scientific Research Projects (BAP) Unit; Adana Alparslan Turkes Science and Technology University Scientific Research Projects (BAP) Unit [20113003]; Adana Alparslan Turkes Bilim ve Teknoloji UEniversitesiAdana Alparslan Turkes Science and Technology University Scientific Research Projects (BAP) Unit, Grant/Award Number: 20113003; Adana Alparslan Turkes Bilim ve Teknoloji UEniversitesi
Akdeniz çam ağacı (Pinus pinea) tohum kabuğundan ve plastik katalizör tohum kabuğu karışımından piroliz işlemi ile biyogaz elde edilmesi
No full textFen Bilimleri Enstitüsü, Makine Mühendisliği Ana Bilim DalıBu çalışma, akdeniz çam ağacı tohum kabuğu biyokütlesi ile polietilen katalizörünün pirolizi sonrası ortaya çıkan hidrojen ve metan gazı potansiyelinin araştırılmasını ortaya koymaktadır. Çalışmada öncelikle polietilen malzemelerin viskozitesi, yoğunluğu ve gazdan arınma noktası belirlendi. Tohum kabukları tedarik edilerek piroliz işlemi için ayıklandı. Tohumlar, belirlediğimiz oranlarda katalizör olarak seçilen polietilen malzemeler ile karıştırıldı. Piroliz, 600 °C sıcaklıkta, 50 °C/dakika hızında gerçekleştirildi. Elde edilen gazlar gaz kromatografi cihazı ile analiz edildi. Deneylerin son aşamasında optik mikroskop altında katı kalıntılar gözlemlendi ve mikro yapıları da incelendi. Sonuçlar, akdeniz çamı çekirdeği kabuğu biyokütlesinin ve bunun düşük yoğunluklu polietilen ile karışımının metan ve hidrojen gazları üretebileceğini gösterdi. En düşük viskozite değerlerinden (0,45 gr/10 dk.) ve en yüksek yoğunluk değerlerinden (0,950 gr/cm3) birine sahip olan M8 katalizörü en yüksek metan ve hidrojen gazı verimini sağlamıştır. Piroliz deneylerinde Akdeniz çam ağacı tohum kabuğu biyokütlesinden %38,44 CH4, %19,50 CO2 ve %42,06 H2 gazları elde edilmiştir. Ayrıca biyokütlenin CO2 emisyon değerleri hesaplanmış ve DEFRA değerleri ile karşılaştırılmıştır. Çalışma, piroliz işlemi yoluyla hidrojen ve metan elde edilebildiğinden, akdeniz çam ağacı tohum kabuğunun yeni bir biyokütle kaynağı olarak sınıflandırılabileceğini ve içten yanmalı motorlar için fosil bazlı yakıtlara alternatif yakıt potansiyeline sahip olduğunu gösterdi.This study reveals the investigation of the hydrogen and methane gas potential resulting from the pyrolysis of Mediterranean pine tree seed coat biomass and polyethylene catalyst. In the study, firstly, the viscosity, density and degassing point of polyethylene materials were determined. Seed shells were supplied and sorted for the pyrolysis process. The seeds were mixed with polyethylene materials selected as catalysts in the proportions we determined. Pyrolysis was carried out at a temperature of 600 °C at a rate of 50 °C/min. The obtained gases were analyzed with a gas chromatography device. In the final stage of the experiments, solid residues were observed under an optical microscope and their microstructures were also examined. The results showed that mediterranean pine core bark biomass and its blend with low-density polyethylene could produce methane and hydrogen gases. The M8 catalyst, which has one of the lowest viscosity values (0.45 g/10 min.) and the highest density values (0.950 g/cm3), provided the highest methane and hydrogen gas yield. In pyrolysis experiments, 38.44% CH4, 19.50% CO2 and 42.06% H2 gases were obtained from the Mediterranean pine tree seed coat biomass. Additionally, CO2 emission values of biomass were calculated and compared with DEFRA values. The study showed that since hydrogen and methane can be obtained through the pyrolysis process, mediterranean pine tree seed husk can be classified as a new biomass source and has potential as an alternative fuel to fossil-based fuels for internal combustion engines
Novel 3D-Printed Microfluidic Magnetic Platform for Rapid DNA Isolation
No full textThis study presents a novel miniaturized device as a 3D-printed microfluidic magnetic platform specifically designed to manipulate magnetic microparticles in a microfluidic chip for rapid deoxyribonucleic acid (DNA) isolation. The novel design enables the movement of the magnetic particles in the same or opposite directions with the flow or suspends them in continuous flow. A computational model was developed to assess the effectiveness of the magnetic manipulation of the particles. Superparamagnetic monodisperse silica particles synthesized in-house are utilized for the isolation of fish sperm DNA and human placenta DNA. It was demonstrated that the proposed platform can perform DNA isolation within 10 min with an isolation efficiency of 50% at optimum operating conditions.T?rkiye Bilimsel ve Teknolojik Arastirma Kurumu [TUBITAK-2219, 1059B191801017]; Scientific and Technological Research Council of Turkiye; Turkish Fulbright Commission; Fulbright Postdoctoral ScholarshipThis study is financially supported by the Scientific and Technological Research Council of Turkiye under grant no. TEYDEB-1170524. We also acknowledge the Turkish Fulbright Commission for a Fulbright Postdoctoral Scholarship and the Scientific and Technological Research Council of Turkiye (TUBITAK-2219 Award#1059B191801017) for Dr. G.K
Falling film hydrodynamics and heat transfer under vapor shearing from various orientations
No full textVapor shearing is a common issue encountered in the operations of falling film heat exchangers. The vapor stream effect depends on its orientation. This study investigates liquid film hydrodynamics and heat transfer performance under the influence of vapor streams from different orientations. The results indicate that both orientation and velocity of vapor determine the encountering time and position of the films on the tube's two sides. The liquid film thickness uniformity and the liquid column deflection vary significantly depending on the orientation and velocity of the vapor. Zones of accelerated liquid film, climbing liquid film, liquid stagnation, and transition of liquid film flow pattern are observed. The gradient of film thickness along the tube axis and the deflection in time-averaged peripheral film thickness increase as the vapor orientation varies from 0 degrees to 90 degrees and subsequently decrease as the vapor orientation varies from 90 degrees to 180 degrees. Vapor streams have more pronounced effects on time-averaged peripheral film thickness in regions close to the liquid inlet and outlet. Vapor streams result in changes in peripheral heat transfer coefficients toward the downstream side depending on the orientation and velocity of the vapor. The impact of vapor streams on the overall heat transfer coefficient does not directly correlate with the velocity of the vapor when maintaining the same orientation.National Natural Science Foundation of China10.13039/501100001809 [51976144]; National Natural Science Foundation of China; Youth Innovation Team of Shaanxi UniversitiesThis work was supported by the National Natural Science Foundation of China (51976144). The authors also gratefully acknowledge the support of the Youth Innovation Team of Shaanxi Universities, the International Joint Research Center for Building Service Science, and the Underground Space Environment, Shaanxi (China)
Bioactivity, DNA damage protecting, and aroma potential of oleuropein enriched olive leaf extract by optimization of ultrasound-assisted process
No full textIn this study, Box-Behnken experimental design was employed to optimize Ultrasound-assisted extraction (UAE) method to obtain oleuropein-rich extract from olive leaf. The effect of three parameters, ethanol concentration (30%-70%), amplitude (30%-50%), and ultrasonication time (5-15 min) on oleuropein content were evaluated through experimental design. The total phenolic content, antioxidant capacity, DNA damage scavenging activity, aroma profile, and antimicrobial activity of olive leaf were also investigated. The optimum extraction condition was determined as 30% amplitude, 70% ethanol, and 5 min extraction time. The amount of oleuropein was found to be 42.621 mg/g dry leaves at the optimum condition. The total phenolic content of the optimized extract was found as 45.13 mg GAE/g dry leaves while the antioxidant capacity of the optimized extract was 216 mu mol Trolox/g in DPPH and 213.19 mu mol Trolox/g in ABTS method. Twenty-three volatile compounds were identified in extracts, mainly aldehydes and alcohols. The extracts showed high antimicrobial activity against selected bacterial strains. DNA damage protecting activity of extracts on plasmid DNA was clearly demonstrated. UAE has an important effect on the phenolic content and antioxidant capacity of olive leaves. Moreover, oleuropein-rich extract can have potential as a therapeutic agent depending on its antimicrobial and DNA-protecting activity. UAE process was optimized to obtain oleuropein-enriched olive leaf extract. Bioactive, DNA damage protecting, and aroma properties of the extracts were evaluated. Regarding the high antioxidant capacity and DNA damage-protecting activity, oleuropein-rich extracts obtained optimized probe-based UAE could have the potential to be used as a natural antioxidant compound in the food industry. imageTurkiye Bilimsel ve Teknolojik Arastirma Kurumu [221O046]Turkiye Bilimsel ve Teknolojik Arastirma Kurumu, Grant/Award Number: 221O04
Exploring the Impact of Infusion Parameters and In Vitro Digestion on the Phenolic Profile and Antioxidant Capacity of Guayusa (Ilex guayusa Loes.) Tea Using Liquid Chromatography, Diode Array Detection, and Electrospray Ionization Tandem Mass Spectrometry
No full textGuayusa tea is derived from the leaves of the Ilex guayusa Loes. plant, which is native to the Amazon rainforest. Beyond its pleasant sensory properties, Guayusa tea is rich in antioxidants, phenolics, and minerals. In this study, the effects of infusion time, temperature, and solvent conditions on the color, antioxidant capacity, total phenolic content, phenolic profile, and antimicrobial activity of Guayusa (Ilex guayusa Loes.) tea were investigated. Guayusa tea samples were prepared using two different solvents, ethanol and water, with 4, 6, and 8-h infusions at 60 and 70 degrees C. Liquid chromatography, diode array detection, and electrospray ionization tandem mass spectrometry (LC-DAD-ESI-MS/MS) were used to determine a comprehensive profile of phenolic compounds and to detect differences due to infusion conditions. Moreover, after the Guayusa tea infusion with the highest bioactive properties was determined, the effects of in vitro gastrointestinal digestion on the total phenolic content, antioxidant capacity, and phenolic compounds of the Guayusa tea infusion were measured. Phenolic profile analysis identified 29 compounds, among which chlorogenic acid and its derivatives were predominant. The increase in infusion time was correlated with an elevation in total phenolic content. Significant differences were observed between water and ethanol infusions of Guayusa in terms of phenolics and antioxidants. The total amount of phenolic compounds in the samples prepared with both solvents was found to increase after oral intake, depending on the digestion stage; meanwhile, the amounts of flavonoid compounds and di-O-caffeoylquinic acid derivatives decreased during digestion
Optimisation of exhaust emissions, vibration, and noise of unmodified diesel engine fuelled with canola biodiesel-diesel blends with natural gas addition by using response surface methodology
No full textThe paper presents methods to determine the optimum input parameters of CNG addition, biodiesel blend ratio, and engine speed to improve engine responses in terms of exhaust emissions, vibration, and noise of CNG-biodiesel-diesel fuelled engines. Box-Behnken based on response surface methodology was used to predict and optimise input parameters. Variance analysis was applied to determine the significant relationship between the input parameters and engine responses. At optimum input parameters (CNG addition = 9.24 L/min, biodiesel blend ratio = 40%, engine speed = 1524.24 rpm), the optimum engine responses of NOx, CO, CO2, O2, engine vibration acceleration, and noise were 93.77 ppm, 438.05 ppm, 1.47%, 18.59%, 37.17 m/s2 and 91.34 dB[A], respectively. In terms of coefficient determination of R2, the values were 99.11%, 99.22%, 99.41%, 99.70%, 98.65%, and 98.60% respectively. The correlation between the optimised result and the engine test result showed an acceptable error limit for NOx, CO, CO2, O2, engine vibration acceleration, and noise as 4.2%, 3.8%, 4.9%, 0.25%, 4.12%, and 0.17%, respectively
Neopterin imprinted nanofilm decorated SPR sensors: Sensitive neopterin detection from human serum
No full textNeopterin (Np) is a valuable marker for monitoring infectious diseases and predicting prognosis. This study developed Np-imprinted surface plasmon resonance (SPR) sensors, specifically designed to detect Np in human serum. Characterization of the Np-imprinted (Np-MIP) and non-imprinted (NIP) SPR sensors was carried out using various techniques. The contact angle measurements revealed increased hydrophilicity of the gold sensor with the nanofilm covering, reducing the contact angles from 60.5 degrees to 45.87 degrees and 32.7 degrees for NIP and Np-MIP SPR sensors, respectively. The nanofilm thickness was determined as approximately 14 nm through AFM studies. Real-time Np detection was successfully achieved with the Np-MIP SPR sensors at different concentrations. The selectivity of Np-MIP was confirmed by testing against pterin and glucose, with Np recognition being 11 and 8.25 times higher than those of pterin and glucose, respectively. Np detection from human serum yielded a detection limit of 3 ng/mL. Furthermore, the synthesized Np-MIP SPR sensors demonstrated reusability over 10 cycles without any loss in Np binding capacity. These findings indicate that Np-MIP SPR sensors possess selective detection capabilities for Np in aqueous solutions and human serum.Scientific Research Projects Coordination Unit of Adana Alparslan Turkes Science and Technology University [21303001]; Nanotechnology Research and Application Laboratory in Adana Alparslan Turkes Science and Technology University/Cukurova Development Agency/Turkey [TR62/18UERET/0032]This work was supported by the Scientific Research Projects Coordination Unit of Adana Alparslan Turkes Science and Technology University (grant number: 21303001) and completed in the Nanotechnology Research and Application Laboratory in Adana Alparslan Turkes Science and Technology University/Cukurova Development Agency/Turkey (TR62/18UERET/0032)
Analyzing aroma-active compounds of traditional herbal coffee (Mırra) using the headspace-solid phase microextraction method combined with GC-MS/O
No full textM & imath;rra is a widely consumed herbal coffee brew (HCB) in T & uuml;rkiye and Arabic countries due to its bitter taste and health benefits. In this study, headspace-solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry/olfactometry (GC-MS/O) used to analyze the aroma-active compounds of m & imath;rra coffee brew. A total of fourteen aroma-active compounds were identified. Among them, alpha-Terpinyl acetate (TA)(Pleasant), alpha-Terpinyl formate (Mildly herbaceous, spicy), furfuryl alcohol (Caramellic, smoky, and burned sugar), and 1,8-cineole (Minty) were the key aroma-active compounds. Furthermore, chlorogenic acids (CGA), phloridzin dihydrate, catechin hydrate, gallic acid, rutin, and naringenin are the most abundant polyphenols in m & imath;rra. Citric, malic, acidic, and succinic acid were determined to be important organic acids in m & imath;rra. The limit of detection (LOD) and limit of quantification (LOQ) of organic acids were in the range of 0.03 to 0.63 and 0.09-1.90 mu g/mL, respectively. Recovery of the applied method was found between 83.51% and 102.53%.The authors express their special thanks to Prof. Dr. Serkan SELLI, Assoc. Prof. Dr. Erdal AGCAM and his team (University of Cukurova Faculty of Agriculture, Department of Food Engineering) for their assistance in aroma, antioxidant, pH, total acidity, and color analysis. The authors also express their special gratitude to Asst. Prof. Dr. Turgay Cetinkaya (Department of Aquatic Biotechnology, Faculty of Aquatic Sciences, Istanbul University) for reviewing the article
Room temperature biosynthesis of ZnO nanoparticles using avocado seed extract with antimicrobial and anticancer properties
No full textIn this study, methanol-water extract of Hass avocado seed was used as a reducing agent for the room temperature biosynthesis of crystalline ZnO nanoparticles (ZnONPs). XRD, ATR-FTIR, DLS, SEM analysis and UV-Vis spectroscopy results demonstrated that crystalline ZnONPs can be synthesized in the presence of avocado seed extract at 1, 3 and 5 mg/mL concentrations. Nanoparticles showed hexagonal crystalline structure with crystallite sizes in the 17-20 nm range and ZnONPs synthesized with 3 mg/mL avocado seed extract content (ZnONPs-3) showed the smallest crystallite size (16.9 nm). Flower like structures of ZnONPs agglomerates were observed in SEM images. The most uniform size distribution with the lowest PdI value (0.140) was determined for ZnONPs-3 by DLS analysis. All ZnONPs exhibited high antimicrobial activity with minimum inhibitory concentrations between 7.81 and 125 mu g/mL. Cytotoxicity of ZnONPs-3 was investigated with human normal skin (BJ) and brain glioblastoma cancer (T98G) cell lines. IC50 values for BJ and T98G cells were determined as 36.05 and 23.60 mu g/mL at 24 h, respectively; which decreased to 31.07 mu g/mL and 18.05 mu g/mL at 48 h. Additionally, ZnONPs-3 showed anticancer activity against T98G cancer cells after 24 and 48 h of exposure at non-toxic doses for BJ normal cells. The results indicate that ZnONPs synthesized in the presence of avocado seed extract are promising bioactive agents that can be used in various fields such as biomedicine, drug delivery and cosmetics due to their antimicrobial and anticarcinogenic properties.Adana Alparslan Turkes Science and Technology University Scientific Research Projects Coordination Unit; [BAP-20103011]This work was supported by Adana Alparslan Turkes Science and Technology University Scientific Research Projects Coordination Unit with project number BAP-20103011