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An optimization study for amino acid extraction from bee bread using choline chloride-acetic acid deep eutectic solvent and determination of individual phenolic profile
No full textIn this study, the aim was to optimize the extraction conditions (molar ratio, time, temperature) in order to maximize the total individual amino acid (TAA) yield from bee bread, which is a fermented bee product, using choline chloride-acetic acid deep eutectic solvent (DES). In addition to the phenolic profile and amino acid profile investigated by LC-MS/MS, some spectrophotometric (total phenolic content, total flavonoid content, total proanthocyanidin content) and bioactivity (antioxidant/antimicrobial activity) tests were carried out on the extracts. Optimum conditions were determined as 1:2 for molar ratio, 15 min for time and 10 degrees C for temperature with optimization based on the TAA values of the different extracts (d: 0.99). Molar ratio and temperature were found to have statistically significant effects on TAA values. At optimum conditions, the amount of TAA obtained with DES (29.678 g/kg) was found to be approximately 35.2% and 54.4% higher than that obtained with ethanol and methanol extracts, respectively. All these results indicate that choline chloride-acetic acid DES can be chosen when preparing bee bread extracts, which are evaluated for different areas of use such as food and health due to active ingredient content. Higher active ingredients can be extracted by trying different DES combinations
The impact of public debt on economic growth: The case of Turkey and PIIGS countries
No full text22.10.2024 tarihine kadar kullanımı yazar tarafından kısıtlanmıştır.Lisansüstü Eğitim Enstitüsü, İktisat Ana Bilim Dalı, İktisat Bilim DalıKüreselleşen dünyada ülkeler, büyüme ve kalkınma süreçleri için gerekli olan kamu harcamalarının finansmanında vergi ve benzeri gelirlerin yetersizliği nedeni ile borçlanma yoluna başvurmaktadır. Son dönemlerde sürekli olarak artmakta olan kamu borçlanmaları artık nitelikte kamunun olağan geliri konumuna gelmiş, bu durum kamu borçlarının ekonomik büyümeyi hangi yönde ve ne büyüklükte etkilediği konusunu günümüzde sıklıkla tartışılır hale getirmiştir. Gelişmiş ve gelişmekte olan ülkeler için kamu borçları ve ekonomik büyüme ilişkisi önemli yere sahiptir. Gelişmekte olan ülkelerde devlet borçlanmasına, öncelikle kalkınma için gerekli olan yatırımların finansmanında tasarrufların yetersiz kalması sebebiyle başvurulmaktadır. Çalışmanın amacı Avro Bölgesi'nin en kırılgan ekonomileri olarak görülen Portekiz, İrlanda, İtalya, Yunanistan ve İspanya'nın oluşturduğu PIIGS ülke grubu ile Türkiye özelinde kamu borçlarının ekonomik büyümeye olan etkilerinin tespit edilmesidir. Bu hususta kamu borçlarının ekonomik büyüme üzerindeki etkilerini araştırmak için 1998-2022 dönemi içinde yer alan istatistiki veriler ışığında panel veri analizine dayanan ekonometrik bir inceleme yapılmıştır. Elde edilen bulgulara göre Türkiye ve PIIGS ülkelerinde kamu borçları GSYH büyümesini istatistiksel anlamlı pozitif yönde etkilemektedir. Bu sonuç Türkiye ve PIIGS ülke ekonomilerinin ekonomik anlamda büyüme ve gelişme sağlayabilmelerinde, kamu borçlanması politikaların tespitinin iyi yapılması ve optimal politikanın belirlenmesinin önemine vurgu yapmaktadır.In the globalizing world, countries resort to borrowing to finance public expenditures required for growth and development processes due to the inadequacy of tax and similar revenues. Public borrowing, which has been steadily increasing in recent periods, has now become the ordinary income of the public sector, and this situation has made the issue of the direction and magnitude of the effect of public debt on economic growth frequently discussed today. The relationship between public debt and economic growth is important for both developed and developing countries. In developing countries, government borrowing is resorted to primarily because savings are insufficient to finance the investments required for development. The aim of the study is to determine the effects of public debt on economic growth in the PIIGS country group, which consists of Portugal, Ireland, Italy, Greece and Spain, which are seen as the most fragile economies of the Eurozone, and Turkey in particular. In this respect, in order to investigate the effects of public debt on economic growth, an econometric analysis based on panel data analysis was conducted in the light of statistical data for the period 1998-2022. According to the findings, public debt has a statistically significant positive effect on GDP growth in Turkey and PIIGS countries. This result emphasizes the importance of determining public borrowing policies well and determining the optimal policy in order for Turkey and PIIGS countries to achieve economic growth and development
Optimization of mechanochemical surface modification parameters on planetary mill using an I-optimal experimental design
No full textSeveral micro -particle -size additives and filler minerals are added to many industrial products, especially plastic, in order to reduce cost and improve mechanical properties and appearance. Also, grinding and surface modification are two fundamental properties of the filler minerals used in plastic products. Notably, Bayburt stone (BS) used as a natural raw material from Bayburt, Turkiye contains 76% SiO2 and 15% Al2O3. In this paper, the hydrophilic surface structure of micronized Bayburt stone (MBS) was made hydrophobe by mechanochemical surface modification using calcium stearate [Ca(C17H35COO)2] in a laboratory -type planetary mill. Next, the optimum conditions of the surface modification design factors, which are (1) ball filling ratio = 30.53%, (2) powder filling ratio = 10.43%, (3) mill speed = 475.91 rpm, (4) chemical dosage = 1.99% of powder, and (5) modification time = 4.83 min., were obtained using the proposed I -optimal design -focused optimization model when predicting the model parameters. In addition, a coated micronized Bayburt stone (CMBS) product with an active ratio (AR) of 99.90% and d10, d50, and d90 values of 1.32 mu m, 3.48 mu m and 9.55 mu m were achieved. Finally, particle size distribution (PSD), thermo-gravimetric and differential thermal analyzer (TG -DTA), Fourier transform infrared (FTIR), scanning electron microscope (SEM), electron dispersive spectrum (EDS), and contact angle analyses were performed on the CMBS product
Evaluation of lavender essential oils and by-products using microwave hydrodistillation and conventional hydrodistillation
No full textThis study investigated the impact of two extraction methods, traditional hydrodistillation (TDH) and microwave-assisted hydrodistillation (MAH), on the essential oil yield and chemical profile of Lavandula angustifolia L., as well as the bioactive potential of the resulting wastewater. Essential oil composition was analyzed via GC–MS, revealing similar qualitative and quantitative profiles for both methods, with ?-terpinolene and (–)borneol as major constituents. Wastewater analysis via LC–MS/MS and spectrophotometric assays demonstrated the presence of significant total phenolic content (3.29–1.78 mg GAE/g) and 32 individual phenolics (463.1 µg/kg for TDH; 479.33 µg/kg for MAH). These findings suggest that both essential oil and wastewater obtained by either method possess considerable bioactive potential, with the MAH method potentially offering advantages over TDH for essential oil extraction. Further exploration of wastewater applications in various industrial sectors is warranted. © The Author(s) 2024.Istanbul Üniversitesi, (39099); Istanbul Üniversites
Makrîzî’nin İsmâilî Fâtımî Halifelerin Nesebi Hakkındaki Görüşlerine Dair Bir Değerlendirme
No full textKuzey Afrika, Mısır ve Suriye’de 909-1171 yılları arasında hüküm süren İsmâîlî Fâtımîler, Sünnî Abbâsî hilâfetinin en büyük siyasal rakibi olmuştur. Hâkim oldukları coğrafya üzerinde tesis ettikleri iktidarın temel dayanaklarından biri de şüphesiz Ehl-i Beyt mensubu oldukları yönündeki iddialarıdır. Buna rağmen imâmetlerinin meşrûiyet zeminini oluşturan Hz. Fâtıma soyundan olmaları yönündeki tezleri dönemin birçok tarihçisi tarafından kabul edilmemiştir. Nesebî aidiyetin toplumun zihin dünyasını şekillendirme ve meşrûiyeti temellendirmedeki etkisi muhâlif Abbâsî iktidarının da dikkatinden kaçmamış, Fâtımîler’in soy ağacında uydurma ve tahrifin olduğunu ileri sürmüşlerdir. Bu bağlamda tarihçilerin mezhebi aidiyetlerinin de etkisi altında kalmalarıyla tarihsel süreçte bazı tartışmalar yaşanmıştır. Orta Çağ İslam tarihçiliğinde en önemli yazarlardan biri ve tarihin farklı dallarında birçok eser kaleme almış olan Makrîzî, bu tartışmaya ışık tutacak hacimli bir eser de yazmıştır. Alışılagelmiş Sünnî tarih tasavvurunun dışında olaylara farklı yönlerden bakabilmeyi başarabilmiş olan Makrîzî İtti?â?u’l-?unefâ adlı eserinde Fâtımîler tarihini bütün yönleri ile incelemiştir. Makrîzî, objektif olma anlayışını yansıtmaya çalıştığı eserinde dönemin hâkim anlayışına göre “öteki” durumunda olan Fâtımîlerin neseplerinin sahih olduğunu ispatlamaya çalışması, onun Şiîlikle ithâm edilmesine de sebebiyet vermiştir. Bu noktada Abbâsî halifesinin varlığı üzerine inşâ edilmiş Memlükler döneminde Fâtımîler’in tarihini farklı bir tarzda yazabilmek, Memlük tarihçiliğinin farklı yönlerini görebilmek adına çarpıcı bir örnektir. Çalışmamız Makrîzî'nin temel eserleri merkezinde araştırma ve yayın etiğine uygun olarak yapılmıştır
Kahramanmaraş Depreminden Etkilenen Ergenlerin İyi Oluş Düzeylerinin Bazı Değişkenler Açısından İncelenmesi
No full textAmaç: Bu çalışma depremden etkilenen ergenlerin iyi oluş düzeylerinin bazı değişkenler açısından incelenmesini amaçlamıştır. Yöntem: Tanımlayıcı nitelikte olan araştırma, Türkiye’de deprem yaşanılan illerin birinde liselere devam eden 154 öğrenci ile Nisan 2023- Haziran 2023 tarihleri arasında yapıldı. Veriler “Kişisel Bilgi Formu” ve “Ergenler İçin Beş Boyutlu İyi Oluş Ölçeği (EPOCH)” ile toplandı. Verilerin analizinde bağımsız gruplar t test ve One-Way ANOVA kullanıldı. Bulgular: Çalışmada Ergenler İçin Beş Boyutlu İyi Oluş Modeli: EPOCH Ölçeği toplam puanı 65,30±11,59 bulundu. Ölçeğin alt boyut puanları sırasıyla bağlılık 3,17±0,77, kararlılık 3,35±0,69, iyimserlik 3,03±0,94, ilişkililik 3,86±0,88 ve mutluluk 2,89±0,83 bulundu. Ölçeğin iyimserlik ve ilişkililik alt boyut puanları ile ergenlerin okul başarı durumları arasında anlamlı fark bulundu (
Drought analysis using innovative trend analysis and machine learning models for Eastern Black Sea Basin
No full textThis study aims to assess the Eastern Black Sea Basin drought conditions. For this purpose, the trend changes in SPI values of 6, 9, 12, and 24 months using innovative trend analysis were examined. Additionally, four machine learning models, including Multiple Linear Regression, Artificial Neural Networks, K Nearest Neighbors, and XGBoost Regressor, are employed to forecast SPI with rainfall data between 1965 and 2020 from eight rainfall stations. The input data for each model was SPI values from lead times of 1 to 6, resulting into 768 unique scenarios. The ML models estimated SPI values better as the SPI duration increased, with the 24-month SPI showing the highest accuracy. The results of SPI forecast indicated that the optimal model and number of input variables varied for each SPI and station, indicating that further studies are required to improve SPI predictions
Refractive Index Sensor Based on Terahertz Metamaterial Absorber with High Sensitivity and Quality Factor for Sensing Applications
No full textThis research describes and assesses a terahertz metamaterial absorber (TMA) with a simple and easy-to-produce structure consisting of gold-silicon (optical)-gold design as a refractive index sensing. Due to the high field limitation in the detection regime, electromagnetic (EM) wave’s absorption reaches 99.40% at a frequency of 3.719 THz, including a significant quality factor (Q-Factor) of 65.77 and a figure of merit, FoM, of 21.49. The TMA has an remarkable sensitivity of 1.215 THz/RIU and can be used as a refractive index sensor (RIS). The proposed metamaterial absorber-based sensor is susceptible to refractive index changes (1.00 to 1.05) in the surrounding medium. For the physical absorption mechanism, the fundamental absorption peak is mainly due to the simultaneous occurrence of electric and magnetic dipole resonances. The proposed absorber has the feature of being an excellent RIS due to its sensing and detection applications
Evaluation of the seismic performance pre- and post-restoration of a masonry clock tower's FE model updated via experimental and optimization methods
No full textThis article presents comprehensive numerical and partial experimental studies to determine the seismic performance of the recently restored masonry clock tower in Bayburt before and after restoration. The numerical dynamic characteristics of the structure are obtained by free vibration analysis conducted on the preliminary finite element model, while the experimental ones are determined through ambient vibration testing. The ultimate finite element models reflecting the actual state of the structure pre- and post-restoration are created through a model updating process based on the principle of minimizing the differences between numerical and experimental dynamic properties via the Tabu Search Algorithm. Dynamic analyses of the models are carried out by the mode superposition method in the time domain, using eleven earthquake ground motion records selected considering the tectonic structure of the region and scaled to the design spectrum explicitly established to the site. Seismic responses are evaluated based on displacement, maximum-minimum principal stress, and maximum-minimum principal strain. The maximum principal stress value, the most critical parameter jeopardizing the safety of masonry structures, is 2.069 MPa before the restoration reaches 2.489 MPa, with an increase of approximately 20.3 % after the restoration. Since this value is less than the tensile strength of the masonry material, 3.120 MPa, it is not at a level that poses any risk to the structure. Other structural reactions also remain below the limit values. Therefore, according to today's seismic hazard analysis criteria, it can be said that the clock tower is safe. However, the North Anatolian Fault Zone, with high tectonic activity passing just south of the city, has the potential to produce severe earthquakes that may affect the region in the future. Therefore, it is necessary to periodically monitor the seismic behaviors of the historical masonry structures in Bayburt and take essential precautions based on the results
Thermal and energy analysis of a novel solar updraft tower design with divergent chimney and convergent collector concept: CFD analysis with experimental validation
No full textThe fact that energy sources are heavily dependent on fossil fuels increases the need for alternative energy day by day. Solar energy is the most popular alternative energy source with massive potential. Solar chimney power plants (SCPP) are one of the systems of interest based on solar energy. SCPP systems are rare systems that can provide 24-hour power output. Their performance has been the subject of constant research since the first pilot plant in Manzanares. Design is crucial for performance figures of SCPPs, and the limitation of climatic parameters causes the system to be approached with different designs. This study makes a 3D CFD model by combining the divergent chimney and convergent collector structure based on the first pilot plant. The solar ray tracing algorithm and the RNG k-e turbulence model are applied and the model equations are solved under dynamic conditions with the reliable software ANSYS FLUENT. After the mesh-independent solution of the model is complete, it is validated with experimental data. The two cases are compared for solar radiation of 1000 W/m2 and environmental temperature of 293 K. A power output of 50.51 kW is achieved for standard pilot sizing. With the new model, the power output rises to 146.34 kW. It is seen that the divergent chimney and convergent collector affect the airflow in the system, increasing the maximum air velocity to 19.363 m/s. In parallel with the experimental data, it is seen that the temperature on the ground exceeds 360 K in the CFD results