Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Uzun, Sevda(64)
- Merdan, Mehmet(47)
- Baltaci, Cemalettin(35)
- Kulakaç, Nurşen(28)
- Duran, Celal(27)
- Ozdes, Duygu(24)
- Turan, Ibrahim(24)
- Demir, Selim(23)
- Türkkan, Tuğba(22)
- Bayrakdaroglu, Serdar(21)
- Topal, Fevzi(21)
- Öztürk, Serkan(21)
- Ürkek, Bayram(21)
- Gücer, Mehmet Ali(20)
- Akar, Zeynep(19)
- Kaygusuz, Abdullah(19)
- Topal, Meryem(19)
- Anaç, Halil(18)
- Aydin, Aydanur(18)
- Batan, Nevzat(18)
- Erata, Hüseyin(18)
- Tuncer, Metin(18)
- Akyürek, Suat(17)
- Baltacı, Cemalettin(17)
- Karimullah, Suud Sarim(17)
- Acet, Tuba(16)
- Akar, Bülent(16)
- Ashyralyyev, Charyyar(16)
- Düzgün, Azer Özad(16)
- Hintistan, Sevilay(16)
- Yılmaz, Coşkun(16)
- Aliyazicioglu, Yuksel(15)
- Kaya, Hacer(15)
- Kurnaz, Muammer(15)
- Kurt, Kemal(15)
- Ozden, Talat(15)
- Yilmaz, Coskun(15)
- Yuksel, Ferhat(15)
- Yücel, Cem(15)
- Öz, Mehmet(15)
Yayınlar
- MakaleAçık Erişim2021Scopus SJRQ1Diagnosis of COVID-19 and non-COVID-19 patients by classifying only a single cough sound
Melek, Mesut
In the last month of 2019, a new virus emerged in China, spreading rapidly and affecting the whole world. This virus, which is called corona, is the most contagious type of virus that humanity has ever encountered. The virus has caused a huge crisis worldwide as it leads to severe infections and eventually death in humans. On March 11, 2020, it was announced by the World Health Organization that a COVID-19 outbreak has occurred. Computer-aided digital technologies, which eliminate many problems and provide convenience in people's lives, did not leave humanity alone in this regard and rushed to provide a solution for this unfortunate event. One of the important aspects in which computer-aided digital technologies can be effective is the diagnosis of the disease. Reverse transcription-polymerase chain reaction (RT-PCR), which is a standard and precise technique for diagnosing the disease, is an expensive and time-consuming method. Moreover, its availability is not the same all over the world. For this reason, it can be very attractive and important to distinguish the COVID-19 disease from a cold or flu through a cough sound analysis via smartphones which have entered into the lives of many people in recent years. In this study, we proposed a machine learning-based system to distinguish patients with COVID-19 from non-COVID-19 patients by analyzing only a single cough sound. Two different data sets were used, one accessible for the public and the other available on request. After combining the data sets, the features were obtained from the cough sounds using the mel-frequency cepstral coefficients (MFCCs) method, and then, they were classified with seven different machine learning classifiers. To determine the optimum values of hyperparameters for MFCCs and classifiers, the leave-one-out cross-validation (LOO-CV) strategy was implemented. Based on the results, the k-nearest neighbors classifier based on the Euclidean distance (kNN Euclidean) with the accuracy rate, sensitivity of COVID-19, sensitivity of non-COVID-19, F-measure, and area under the ROC curve (AUC) of 0.9833, 1.0000, 0.9720, 0.9799, and 0.9860, respectively, is more successful than other classifiers. Finally, the best and most effective features were determined for each classifier using the sequential forward selection (SFS) method. According to the results, the proposed system is excellent compared with similar studies in the literature and can be easily used in smartphones and facilitate the diagnosis of COVID-19 patients. In addition, since the used data set includes reflex and unconscious coughs, the results showed that conscious or unconscious coughing has no effect on the diagnosis of COVID-19 patients based on the cough sound.
AtıfScopus38WoS26OpenAlex45
İncele - MakaleAçık Erişim2021Scopus SJRQ1A Two-Phase Approach using Mask R-CNN and 3D U-Net for High-Accuracy Automatic Segmentation of Pancreas in CT Imaging
Dogan, Ramazan Ozgur; Dogan, Hulya; Bayrak, Coskun; Kayikcioglu, Temel
Background and objective: The size, shape, and position of the pancreas are affected by the patient characteristics such as age, sex, adiposity. Owing to more complex anatomical structures (size, shape, and position) of the pancreas, specialists have some difficulties in the analysis of pancreatic diseases (diabetes, pancreatic cancer, pancreatitis). Therefore, the treatment of the disease requires enormous time and depends on the experience of specialists. In order to decrease the rate of pancreatic disease deaths and to assist the specialist in the analysis of pancreatic diseases, automatic pancreas segmentation techniques have been actively developed in the research article for many years. Methods: Although the rapid growth of deep learning and proving satisfactory performance in many medical image processing and computer vision applications, the maximum Dice Similarity Coefficients (DSC) value of these techniques related to automatic pancreas segmentation is only around 85% due to complex structure of the pancreas and other factors. Contrary to previous techniques which are required significantly higher computational power and memory, this paper suggests a novel two-phase approach for high-accuracy automatic pancreas segmentation in computed tomography (CT) imaging. The proposed approach consists of two phases; (1) Pancreas Localization, where the rough pancreas position is detected on the 2D CT slice by adopting Mask R-CNN model, (2) Pancreas Segmentation, where the segmented pancreas region is produced by refining the candidate pancreas region with 3D U-Net on the 2D sub-CT slices generated in the first phase. Both qualitative and quantitative assessments of the proposed approach are performed on the NIH data set. Results: In order to evaluate the achievement of the recommended approach, a total of 16 different automatic pancreas segmentation techniques reported in the literature are compared by utilizing performance assessment procedures which are Dice Similarity Coefficient (DSC), Jaccard Index (JI), Precision (PRE), Recall (REC), Pixel Accuracy (ACC), Specificity (SPE), Receiver Operating Characteristics (ROC) and Area under ROC curve (AUC). The average values of DSC, JI, REC and ACC are computed as 86.15%, 75.93%, 86.27%, 86.27% and 99.95% respectively, which are the best values among well-established studies for automatic pancreas segmentation. Conclusion: It is demonstrated with qualitative and quantitative results that our suggested two-phase approach creates more favorable results than other existing approaches.
AtıfScopus70WoS55OpenAlex68İncele - MakaleAçık Erişim2021Scopus SJRQ4Quadrotor Flight System Design using Collective and Differential Morphing with SPSA and ANN
Kose, Oguz; Oktay, Tugrul
Quadrotor modeling has been done with collective and differential morphing. Quadrotor initial state and morphing states are drawn in the Solidworks program. Newton-Euler approximation was used for quadrotor modeling. The mass and moment of inertia values required for modeling and simulation were obtained from the Solidworks program. Matlab / Simulink environment and state-space model approaches are used for simulations. A simultaneous perturbation stochastic approximation (SPSA) algorithm was used to determine the quadrotor morphing rates. If the morphing state obtained by SPSA is not included in the values obtained from the drawings, here it is provided to find the moments of inertia with the method based on learning by using the data obtained with the Artificial Neural Network(ANN). Proportional Integral Derivative (PID) is used as the quadrotor control algorithm. PID coefficients are also determined by SPSA.
AtıfScopus13OpenAlex13
İncele - Kitap BölümüAçık Erişim2021Investigation of the foreign direct investment and environmental pollution nexus for developing countries
Çelik, Orkun; Korkmaz, Özge; Adalı, Zafer
In theory, the foreign direct investment and environmental pollution nexus is explained by three hypotheses. Firstly, pollution haven hypothesis assumes that there is a positive nexus between these variables. Secondly, pollution halo hypothesis supposes that there is negative connection between these variables. Lastly, neutrality hypothesis asserts the non-existence of the connection between these variables. In recent years, many researchers have frequently tested whether these hypotheses are valid for different countries. In this study, applying Westerlund panel cointegration test, the authors aim to explore the nexus between foreign direct investment and environmental pollution for 23 developing countries after global crisis. For this aim, they use annual data covering the period 2009-2019. According to the obtained empirical findings, the presence of the long-term nexus between foreign direct investment and environmental pollution is not detected for 23 developing countries. Accordingly, the authors can say that there is neutrality hypothesis.
AtıfScopus1OpenAlex4İncele - MakaleAçık Erişim2021Fuzzy inverse logic: part-2. validation and evaluation of the method; [Bulanık ters mantık: kısım-2. yöntemin doğrulanması ve değerlendirilmesi]
Öztekin, Ertekin
In the first part of this study, which consists of two parts, the introduction of the fuzzy inverse logic method, its foundations, computation and process flow and details were given. In this second part, the method was applied on a very simple mathematical problem and on a simple civil engineering design problem in order to investigate and evaluate the validity of the method easily. Fuzzy inverse logic computations have been carried out on these two simple problems for different dimension, sensitivity and acceptable error values. By comparing the obtained results with the desired outputs and mathematical results, the effective computation ability of the method was tried to be revealed. As a result, it is understood that the method developed in this study has many promising aspects in terms of theoretical computations and practical applications and can be used effectively in many scientific fields.
AtıfScopus2OpenAlex3TR Dizin1İncele - MakaleAçık Erişim2021Scopus SJRQ2Constrained adaptive backstepping control of a semi-active suspension considering suspension travel limits
Yıldız, Ali Suat; Sivrioğlu, Selim
In this article, a new constrained adaptive backstepping control design is presented for vibration suppression of the quarter car suspension system equipped with a magnetorheological (MR) damper. In the controller design, parametric uncertainties related to suspension parameter and the semi-active actuator are considered. Also, the proposed controller is investigated, along with the designed road profiles based on the International Standard Organization (ISO) 8608 classification and tested under different speed conditions. The effectiveness of the proposed controller has been validated through comparisons with uncontrolled, passive, and separately designed adaptive control cases. According to the simulation and experimental results, the proposed control approach improves ride comfort and ride safety without violating suspension rattle space constraint despite the uncertainties in suspension parameters.
AtıfScopus20WoS19OpenAlex18İncele - MakaleAçık Erişim2021Scopus SJRQ3Determination of Antimicrobial and Antioxidant Activities and Chemical Components of Volatile Oils of Atropa belladonna L. Growing in Turkey
Öz, Mehmet; Fidan, Muhammed Said; Baltaci, Cemalettin; Ücüncü, Osman; Karatas, Seyda Merve
In this study; the essential oils were obtained from the flowers and leaves of Atropa belladonna L. plants through the hydrodistillation method in a Clevenger type device. The chemical composition of volatile oils was determined by analyzing with the GC-MS/MS instrument. The antioxidant activity of the obtained volatile oils was determined according to total antioxidant content (TAC), free radical scavenging (ABTS) capacity, free radical scavenging (DPPH) amounts, total flavonoid content (TFC), total phenolic content (TPC), and ferric reducing antioxidant power (FRAP) capacity methods. Antimicrobial activities of essential oils were determined through the agar-disc diffusion method. As for the results; volatile oil yields of the A. belladonna were determined as 0.37 % in leaves and 1.57 % in flowers. The highest percentage of chemical compounds in essential oils of the A. belladonna plant were determined as (43.75 %) aldehydes in leaves and as (39.96 %) fatty acids in flowers. In addition, the main constituents found in volatile oils were eicosane (35.92 %) in the leaves and hexadecenoic acid (18.84 %) in the flowers of the A. belladonna. The highest amounts of antioxidant for the test specimens were found as 1.37-1.48 mg QE/100 mL in TFC, as 13.25-21.91 mg AA/100 mL in ABTS, as 51.49-62.87 mg GA/100 mL in TPC, and as 4.71-7.97 mg FeSO4/100 mL in FRAP capacity. As the results of the antimicrobial activities, it was determined that only the leaves of A. belladonna show antimicrobial activity against the mold-yeast and gram-positive and gram-negative bacteria microorganisms among the 17 bacteria and 6 yeast-mold types used in the study.
AtıfScopus12WoS8OpenAlex11İncele - MakaleAçık Erişim2021Scopus SJRQ3The effect of pozzolans and mineral wastes on alkali-silica reaction in recycled aggregated mortar
Külekçi, Gökhan
In this study, it was aimed to examine recycled aggregates (RA), which are considered as aggregates, in terms of alkali-silica reaction (ASR) before being used in concrete, to determine the risk status and to reduce the ASR value. In order to reduce and stop the ASR, the cement was replaced with clay brick and fly-ash by 10–40 %. Marble waste and Pb-Zn mine waste were used instead of RA in order to reduce aggregate reactivity. At the end of 28 days, compared to the control sample, it was observed that mortar bar samples containing tailings instead of fine RA has 18 % less expansion and marble waste (MW) added samples again instead of fine RA has 34 % less expansion. Furthermore, 40 % fly ash (FA) added samples decreased the level of ASR for 96 %, and in 10 % clay brick mixed samples ASR formation is decreased to 85 %. As a result, recycled aggregates were determined to be reactive for ASR. It has been determined that marble and lead-zinc mine facility wastes added as replace with to RA reduce the expansion effect by ASR in the cement paste. With this study, it has contributed to the safe use of the increasing use of RA in the world.
AtıfScopus11WoS11OpenAlex8İncele - MakaleAçık Erişim2021Scopus SJRQ4Wear, Corrosion and Tribocorrosion Behavior of Polyurethane and Polyvinylpyrrolidone Blends as Coating for Corrosion Protection of AISI 316L Stainless Steel
Taşdemir, Muharrem; Şenaslan, Fatih; Çelik, Ayhan
Polyurethanes (PUs) are used across a widely from biomaterials to industrial applications due to their versatile properties. Polyurethane is blended with other polymers to improve their physical and thermal properties. In this study, different concentrations of polyurethane and polyvinylpyrrolidone (PVP) blends were applied to AISI 316L stainless steel using the dip coating method as protection against wear and corrosion. The effects of different concentrations of blends on the mechanical, corrosion and tribocorrosion properties of the AISI 316L stainless steel were investigated. The phase structure of polymer coatings were investigated by X-ray diffraction (XRD), and their surfaces were examined by scanning electron microscopy (SEM). Corrosion and tribocorrosion tests of the polymer coated samples were carried out in 3.5% NaCl solutions. The surface roughness and nanohardness of the polymeric coated samples were also measured. It was found that surface roughness and friction coefficient increased with raised concentration of PVP, while wear and corrosion resistance decreased with the increased of PVP concentration in the coating. As the penetration depth of the PU coated sample increased, the nanohardness and elasticity modulus decreased. Coatings containing PVP up to 25% protected the substrate surface under tribocorrosion conditions in NaCl solutions.
AtıfScopus6WoS5OpenAlex6İncele - Derleme MakaleAçık Erişim2021COVID-19 vaccine and immune response
Hintistan, Sevilay; Demirağ, Hatice
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; βCoV), the causative agent of coronavirus disease 2019 (COVID-19), causes severe lower respiratory tract infections and acute respiratory failure syndrome (ARDS). Deaths due to the ongoing COVID-19 pandemic for more than a year are still seen worldwide. Therefore, vaccine trials have gained importance. The discovery of the genome and protein structure of SARS-CoV-2 in a short time allowed the development of nucleic acid-based vaccines (mRNA and DNA vaccines), vector vaccines, inactivated virus vaccines, protein-based vaccines, virus-like particle vaccines, and live attenuated virus vaccines. Many companies, universities, and institutes around the world continue to develop effective vaccines against SARS-CoV-2. In this review, the structural features, classification, genome, and intracellular entry of SARS-CoV-2 coronaviruses, stimulation of the immune system and immunity, COVID-19 vaccine types, and the latest status of clinical trials of these vaccines have been reviewed.
AtıfScopus1OpenAlex2İncele - MakaleAçık Erişim2021Scopus SJRQ4Optimization of three-element tuned mass damper for single degree of freedom structures under ground acceleration; [Yer ivmesi etkisi altındaki tek serbestlik dereceli yapılar için üç elemanlı ayarlı kütle sönümleyicinin optimizasyonu]
Araz, Onur
Passive control devices have been used for a long time to reduce unwanted vibrations. The most commonly used of these devices are tuned mass dampers. The optimum parameters of the three-element tuned mass damper for damped main structures due to ground acceleration are investigated in this paper. Unlike the traditional tuned mass damper, the three-element tuned mass damper contains two spring elements and one of them is connected in series with the damping element. The optimum parameters are obtained by simulated annealing algorithm. Numerical results show that the three-element tuned mass damper is very effective in reducing dynamic vibrations of the damped structures.
AtıfScopus30OpenAlex19TR Dizin1İncele - Kitap BölümüAçık Erişim2021Scopus SJRQ4Energy Policy Recommendations for ASEAN Countries: Empirical Evidence from the Bootstrap Panel Granger Causality Analysis
Adali, Zafer; Korkmaz, Özge; Çelik, Orkun
In social sciences, especially in the economic literature, energy has been one of the most important topics. Energy seems to be dominant on the political and economic agendas because of nearly all economic activities linked to energy. Hence, all economies have endeavored to detect and implement policies to increase their efficiency and mitigate energy’s detrimental effects on the earth. This study’s principal mission is to check the connection between economic growth, non-renewable and renewable energy consumption in ASEAN-5 countries over 1990–2014 to recommend energy-saving policies. Within this view, bootstrap panel Granger causality test is applied. The model results indicate that economic growth causes renewable energy consumption in the Philippines and economic growth induces non-renewable energy consumption in Indonesia and Malaysia. A unidirectional causality relationship operating from renewable energy consumption to economic growth is approved for Brunei Darussalam. Finally, a unidirectional causality relationship working from renewable energy consumption to Brunei Darussalam’s economic growth is confirmed.
AtıfScopus2İncele - MakaleAçık Erişim2021Scopus SJRQ2The effect of COVID-19 anxiety levels of healthcare professionals on the quality of working life and related factors
Aydın, Aykut; Kulakaç, Nurşen; Aydın Sayılan, Aylin
Aim: This study aims to determine the effect of COVID-19 anxiety levels of healthcare professionals on their working life quality. Method: The sample of the descriptive, cross-sectional and correlational study consisted of healthcare professionals working in two university hospitals in western Turkey between May and July 2021. We used the “Personal Information Form, Coronavirus Anxiety Scale, and Working Life Quality Scale” as data collection tools. We used numbers and percentage calculations, arithmetic mean, median (25th–75th percentile), Mann–Whitney U test, Spearmen correlation analysis and Linear Regression analysis to analyse the data. Results: The mean score on the Quality of Life Scale of healthcare professionals was 3.74 ± 0.28, and the mean score on the Coronavirus Anxiety Scale (CAS) was 9.66 ± 6.06 (min. 0; max. 20). We found a negative and weakly significant relationship between the mean score of the CAS of healthcare professionals and the mean score of the employee quality of life scale. According to the results of the multiple linear regression analysis, we found the factors significantly affecting the anxiety states of healthcare professionals related to the Coronavirus are the quality of working life, age, sex and the state of caring for a patient with COVID-19. Conclusion: As a conclusion of this study, it was determined that healthcare professionals experienced anxiety, and anxiety decreased as ages, working years and the number of children they have increased. In addition, it was determined that as the anxiety of healthcare professionals increased, the quality of working life decreased.
AtıfScopus9WoS6İncele - MakaleAçık Erişim2021Scopus SJRQ1Performance of AC overlays using geogrids on PCC contraction joints
Çelik, Muhammet; Seferoğlu, Mehmet Tevfik; Akpınar, Muhammet Vefa
It is widely known that vertical displacements and strains occur on the joints and these cause defects on the asphalt concrete (AC) overlays on existing Portland cement concrete (PCC) pavements. Various approaches were introduced to minimize these defects. In this study, the effect of joint support formed using the geogrid material with grout mortar on the vertical displacement of PCC and the strain at the bottom of the AC layer. Produced layers were exposed to 1,186,000 Equivalent Single Axle Load (ESAL) in an APT (Accelerated Pavement Test) facility and the results were monitored. According to the obtained results, the use of AC overlay reduces vertical displacement in the PCC by 75%. When geogrid reinforced AC overlay was used, an additional reduction in displacement by 41.2% was achieved. Geogrid reinforcement reduced strain values formed at the bottom of the AC layer from 29.5% to 92.5%. The use of geogrid at joints instead of increasing the thickness of the AC layer from 50 to 80 mm resulted a more significant reduction in both strain and displacement. Besides, the usage of a geogrid interlayer instead of increasing the thickness of the AC layer also provided a significant cost reduction of 57.9% in overall cost.
AtıfScopus2WoS2OpenAlex3İncele - MakaleAçık Erişim2021Scopus SJRQ3Satellite-derived shallow wetland bathymetry using different classification algorithms and datasets
Dervisoglu, Adalet; Yagmur, Nur; Bilgilioglu, Burhan Baha
Remote sensing (RS) effectively identifies, analyzes, and monitors wetlands. In addition to these two-dimensional studies, RS is used with several techniques in determining shallow water depths. The primary purpose of this study is to obtain shallow wetland bathymetry utilizing spectral reflections obtained at different water depths by field study and satellite images. Machine learning (ML) algorithms, which are widely used in remote sensing, are used in this study. Four algorithms were selected as random forest (RF), support vector machine (SVM), Neural Networks (NN), and Maximum Likelihood Classification (MLC). Since machine learning algorithms use training samples/datasets, the classification accuracy is directly related to selecting these data. The effect of pixel counts on classification was investigated by using two different training data set also. Duden (Kulu) Lake, which is a shallow wetland, was chosen as the study area. The Iterative Self-Organizing Data Analysis Technique (ISODATA) classification algorithm divided into as many clusters as possible was applied on Sentinel-2 multispectral images. All classes were rede-fined using measured spectral signatures and were created a bathymetric map. This map was used as reference data in creating training sets and the accuracy assessment of ML algorithms. When the water surface areas obtained from algorithms were compared with the bathymetric map and Normalized Difference Water Index, the best result was obtained with RF. According to the accuracy assessment results, it was seen that the number of training data affects the accuracy, and the best results were obtained with SVM and RF algorithms with training data containing more pixels (overall accuracy 93.87% and 92.64, kappa 0.89 and 0.87, respectively).
AtıfScopus1WoS1OpenAlex1İncele - MakaleAçık Erişim2021Scopus SJRQ3The Curricular Practical Training Rotation Problem Formulation and the Assessment of Rotation Strategies
Şimşek, Ahmet Bahadır
This study addresses the curricular practical training rotation problem, which is a type of staff assignment problem. Many educational institutions require theoretical knowledge to be complemented by practical training. Although the details of the implementation differ from institution to institution, it is necessary to prepare a rotation plan that determines how long the trainees will practice in which unit in which training period. Because of the complexity of the problem and humanistic reasons, the manual rotation plan can not reach the optimal level that satisfies all stakeholders and takes time. This study defines a general Curricular Practical Training Rotation Planning Problem specific to the curriculum-based trainee assignment process carried out in a university department and proposes an integer mathematical model for its solution. It is one of the important contributions of this study. It also provides a methodological approach to identify the most appropriate rotation strategy that will satisfy stakeholders. The methodological approach followed is a structure that can be adapted to different perspectives. The study has the potential to guide practitioners and researchers in the field and to lead a rich literature that will be formed with different side constraints and purposes to the problem.
- MakaleAçık Erişim2021Scopus SJRQ3Comparison of field and laboratory result of fiber reinforced shotcrete application
Külekçi, Gökhan
Synthetic fibers, which have become one of the main components of shotcrete, have been studied by many researchers in the laboratory environment. Unfortunately, the results obtained as a result of these researches are not suitable for underground chimneys due to the differences in ambient conditions and application differences. In this study, it is aimed to compare the results of the experiment samples prepared and kept in the laboratory with the mechanical properties of the shotcrete applied in underground conditions. For this purpose, keeping the slump and cement proportions constant, 35 cubic samples were prepared using 2 and 6 kg synthetic fiber for 1 m3 in the laboratory, and 30 cylinder samples and 6 plate samples were prepared for underground. While mechanical experiments were carried out on prepared cube and cylinder samples, the EFNARC plate test and freeze-thaw test were carried out on plate samples. It was observed that the set accelerator made a significant increase in resistance at the end of the 28 days and that the resistance of the samples prepared with polyester fibers in the laboratory environment were very high. As a result of the EFNARC panel tests performed, it was determined that the energy absorption of synthetic fibers increased with fiber amount. Thanks to this study, the energy absorption of the synthetic fiber used has been measured, and the reliability and practicality of the experiments carried out in the laboratory have been increased by evaluating the field conditions and laboratory conditions.
AtıfScopus13WoS12OpenAlex11İncele - MakaleAçık Erişim2021Scopus SJRQ1Land subsidence and its relations with sinkhole activity in karapınar region, turkey: A multi-sensor insar time series study
Orhan, Osman; Oliver-Cabrera, Talib; Wdowinski, Shimon; Yalvac, Sefa; Yakar, Murat
The Karapinar basin, located in the Central Anatolian part of Turkey, is subjected to land subsidence and sinkhole activity due to extensive groundwater withdrawal that began in the early 2000s. In this study, we use Interferometric Synthetic Aperture Radar (InSAR), Global Navigation Satellite System (GNSS), and groundwater level data to monitor and better understand the relations between groundwater extraction, land subsidence, and sinkhole formation in the Karapinar basin. The main observations used in the study are InSAR-derived subsidence velocity maps calculated from both Sentinel-1 (2014–2018) and COSMO-SkyMed (2016–2017) SAR data. Our analysis reveals broad areas of subsidence with rates exceeding 70 mm/yr. The InSAR-derived subsidence was compared with GNSS data acquired by a continuously operating GNSS station located in the study area, which show a similar rate of subsidence. The temporal characteristic of both InSAR and GNSS time series indicate a long-term subsidence signal superimposed by seasonal variability, which follows the overall groundwater level changes, with over 80% cross-correlation consistency. Our results also indicate that sinkhole activity is limited to slow subsidence areas, reflecting strong cohesion of near-surface rock layers that resist subsidence but yield to collapse in response to aquifer system deformation induced by groundwater extraction.
AtıfScopus63WoS55OpenAlex70İncele - MakaleAçık Erişim2021Scopus SJRQ2Geochemistry and Pb isotopic proof for sources of heavy metal(loid)s in Late Cretaceous sandstones from Eastern Pontides (NE Turkey)
Saydam Eker, Çiğdem
Upper Cretaceous sedimentary rocks are widely exposed around Trabzon, Giresun and Gümüşhane in the eastern Pontides. The sedimentary rocks are mainly composed of sandstones and marls, and the thicknesses of these rocks range from 170 to 400 m. This paper focused on Late Cretaceous sandstones of Trabzon, Giresun and Gümüşhane regions to identify the concentrations, sources, deposition environment and conditions of certain heavy metal(loid)s (Zn, Pb, Cu, Ni, As, Co, Mo and V). Enrichment factor (EF), geo-accumulation index (Igeo), Pollution index (Pi), Pollution load index (Pln), Pb isotope and multivariate statistical analysis were performed to elucidate the pollution levels and sources. In general, the evaluation indices exhibited that the sandstones were moderately polluted by As in the Trabzon area, and strongly polluted by Ni and As, moderately polluted by Co and V in the Giresun and Gümüşhane areas. The results of multivariate statistical analyses indicated that As and partly Pb might be originated from anthropogenic sources, whereas other metals were derived from geogenic origin. Lead isotopic analysis demonstrated two characterized signatures of the pollution sources in the sandstones, one related to geogenic origin and the other to coal, gasoline and pesticides. The sandstones were deposited in transition—marine environment under oxic—weak oxic conditions and paleoclimatic conditions ranged from arid to moist during Late Cretaceous period.
AtıfScopus7WoS6OpenAlex10İncele - MakaleAçık Erişim2021Production and characterization of zinc oxide nanoparticles in microsystems via green synthesis; [Yeşil sentez yoluyla mikrosistemlerde çinko oksit nanopartiküllerin üretimi ve karakterizasyonu]
Akay, Şeref; Sefaoğlu, Melike
Nanoparticles (NP), which can be produced for many different fields and purposes; are at size vary from nanometer to a micrometer. These particles can be prepared by different approaches such as chemical, physical and biological methods. However, the biological approach is the most promising approach among other methods due to its simplicity and environmentally friendly conditions. The production of the nanoparticle by means of a biological approach does not require any high temperature, acidic/basic conditions and hazardous chemicals. Therefore, this method is named “green synthesis”. Development in microtechnology has had profound effects in many areas such as drug discovery, biology, diagnosis, and tissue engineering. Microfluidics which focuses on the processing of liquids in microscale systems has attracted wide attention in the production process of nanoparticles due to precise control and fast mixing. The main purpose of this study is to produce and characterize metal nanoparticles by combining microsystems and green synthesis approaches. For this purpose, in the first step, the design of microsystems that suitable for the flow of different phases was performed. In the second step, ZnO nanoparticle synthesis was carried out using the red cabbage (Brassica oleracea var.capitata f. Rubra) extracts. The synthesis of nanoparticles achieved by optimizing different parameters such as; extract: zinc ratio, zinc solution concentration, flow rates, and flow rates ratio in the microsystem and temperature. The results showed that the herbal red cabbage components can be used for the green synthesis of ZnO nanoparticles.
AtıfScopus1OpenAlex2TR Dizin1İncele