Yayınlar
Koleksiyondaki öğeler
- Kitap BölümüYalnız künye2023An IT2FBWM Model to Highlight the Significance of Factors Utilized in Determining Pandemic Hospital Site Selection
Aycin, Ejder; Kayapinar Kaya, Sema; Ecer, Fatih
The COVID-19 pandemic has spread to the world in a short time since its emergence in Wuhan, China, and mobilized international health authorities with its effects, continues its development seriously. Due to the fast spread of COVID-19, governments have made some decisions to build new temporary hospitals for patients infected with COVID-19. This situation increased the importance of the site selection process for a pandemic hospital during the current critical time. Site selection of a hospital can be considered as multi-criteria decision-making (MCDM) problem since it includes multiple factors. This paper applies an analytical tool for evaluating the criteria of the site selection of a pandemic hospital. For this purpose, the extended best–worst method with trapezoidal interval type-2 fuzzy numbers (IT2FBWM) is employed to determine the importance weights of the pandemic hospital site selection criteria. The paper’s findings point out that the IT2FBWM model can help decision-makers determine the importance weights of the criteria used in the pandemic hospital siting decisions.
AtıfScopus1OpenAlex2
İncele - MakaleAçık Erişim2021Influence of particle size, additive ratio and chemical structure of zinc borate on mechanical properties of poly(vinyl chloride)
İpek, Yeliz
Zinc borate (ZB) is a flame retardant and smoke supressant compound of boron. It is widely used to achieve flame resistant polymer composites. Poly(Vinyl Chloride) (PVC) is one of the commercially important polymers that is mostly used for cable insulating, windows, doors, pipes, floorings and toys etc.. On the other hand, PVC releases toxic gases during fire as decomposition products. Zinc borate addition is thought to be a solution for this problem. However, this solution leads a new problem. Zinc borate effects the mechanical properties of the PVC. In the present study, to optimize the contribution of zinc borate, with different formulations (2ZnO·3B2 O3·3.5H2 O and 4ZnO·B2 O3·H2 O), with different additive ratios (1% and 5% by weight) and different particle sizes (nano-sized and micro-sized) were added to the PVC structure and the mechanical and thermomechanical properties of each composite were investigated. Mechanical properties of composites were determined by tensile test, impact test, hardness test while thermomechanical behaviours were detected with dynamic mechanical analysis (DMA). In the perspective of mechanical strength of PVC-ZB composite, additive ratio of ZB was more effective than particle size and chemical formulation of ZB. The additive ratio more than 5% by weight can negatively affect the mechanical strength and quality of the PVC-ZB composite.
AtıfScopus2OpenAlex2
İncele - MakaleAçık Erişim2022Scopus SJRQ2DNA barcoding and phylogenetic analysis of endemic Astragalus nezaketiae and Vicia alpestris subsp. hypoleuca (Fabaceae):Evidence from nrDNA ITS and cpDNA matK and rbcL sequences
Paksoy, Mehmet Y.; Sevİndİk, Emre; Başköse, İsa
In this study, we performed DNA barcoding and phylogenetic analysis using one nuclear (ITS) and two chloroplast DNA regions (matK and rbcL) of endemic Astragalus nezaketiae A. Duran & Aytaçand Vicia alpestris Stev. subsp. hypoleuca (Boiss.) Davis taxa in Turkey. PCR reactions were performed using universal primers. Sequences of the PCR products were edited using BioEdit and FinchTV software and contigs were obtained. All contigs were Blasted at NCBI and similarities were analysed. Using the MEGA 6.0 program, maximum likelihood trees were constructed including some sequences retrieved from NCBI. For Astragalus nezaketiae; in the ITS analysis, Astragalus nezaketiae appeared separately from other species, and for matK, Astragalus nezaketiae appeared together with Astragalus cicer L. However, rbcL tree was polytomic. For Vicia alpestris subsp. hypoleuca; in ITS, rbcL and matK results Vicia alpestris subsp. hypoleuca were found together with Vicia cracca L., Vicia benghalensis L. and Vicia villosa Roth species. Analysis of the combined data revealed similar results with all barcode regions for Vicia alpestris subsp. hypoleuca while different phylogenetic results were obtained for Astragalus nezaketiae.
AtıfScopus3WoS2OpenAlex3
İncele - MakaleAçık Erişim2022Scopus SJRQ1Novel of (PLA/PCL blend)/Gd2O3 rare earth oxide nanocomposites: Shape memory effect, thermal, magnetic, and mechanical properties
Özen Öner, Ecem; Pekdemir, Mustafa Ersin; Ercan, Ercan; Say, Yakup; Kök, Mediha; Aydoğdu, Yıldırım
Poly ɛ-caprolactone (PCL) and poly lactic acid (PLA) stand out as biocompatible polymers. In this study, PCL and PLA were blended in 40:60 ratio, respectively, and then the Gd2O3 compound, which is an important earth element oxide, was mixed in PLA–PCL shape memory polymer (SMP) blend at different rates and polymer blend nanocomposites were obtained. First of all, the effects of Gd2O3 oxide on the thermal properties of the SMP blend were determined with a differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA), and it was determined that Gd2O3 did not have a significant effect on the melting temperature of the blend, while it significantly increased its thermal stability. As a result of the XRD (X-ray diffraction) analysis of the composites at room temperature, it was determined that the semicrystalline blend, with the addition of Gd2O3, increased its crystalline property. When the shape memory effect was examined, it was understood that the additive did not eliminate the shape memory effect. When the magnetic property of the gadolinium oxide-doped composite, which is magnetocaloric oxide, was examined, the magnetic property of the composite changed from diamagnetic to paramagnetic with increasing additives. Finally, the mechanical properties of the shape memory blend composite were investigated and no regular changes were observed in the mechanical properties with increasing Gd2O3.
AtıfScopus38OpenAlex42İncele - MakaleYalnız künye2022Scopus SJRQ2Structural, biocompatibility, and antibacterial properties of Ge–DLC nanocomposite for biomedical applications
Arslan, Mehmet Enes; Kurt, Mustafa Şükrü; Aslan, Naim; Kadi, Abdurrahim; Öner, Sena; Çobanoğlu, Şeymanur; Yazici, Ayşenur
Integrative production of new nanocomposites has been used to enhance favorable features of biomaterials for unlocking ultimate potential of different molecules. In the present study, advantageous properties of diamond like carbons (DLC) and germanium (Ge) like greater biocompatibility and antibacterial attributes were aimed to combined into a thin film. For this purpose, 400 nm DLC–Ge nanocomposite was coated on the borosilicate glasses via the magnetron sputtering and surface characteristics was analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and The Raman spectrum. Biocompatibility analysis were performed by 3-(4,5-Dimethylthiazol-2-yl) (MTT) cell viability assay and Hoechst 33258 fluorescent staining genotoxicity assessments on the human fibroblast cell line (HDFa). Finally, antibacterial properties of DLC–Ge nanocomposite coatings were investigated by Pseudomonas aeruginosa (ATCC 27853) and Staphylococcus aureus (ATCC 25923) bacterial attachment analysis. As a result of magnetron sputtering coating, nearly 400 nm thick DLC–Ge nanocomposite film showed a smooth, a non-porous, and a dense characteristic. Cell viability analysis showed that Ge–DLC coatings permits %95 cell surface growth of fibroblast cells. Also, there were no significant difference in aspect of nuclear abnormalities compared to the (−) control which showed nonmutagenic features of the thin film. Finally, antibacterial attachment analysis put forth that Ge–DLC coatings inhibits bacterial adhesion as %40 and %25 rates for P. aeruginosa and S. aureus bacterial strains, respectively. From these results, DLC–Ge nanocomposites could be proposed as a potential new biomaterial for various biomedical applications.
AtıfScopus20WoS16OpenAlex19
İncele - MakaleYalnız künye2023Scopus SJRQ2The potential ameliorative impacts of rare earth element cerium in dimethoate induced toxicity in freshwater mussel Dreissena polymorpha
Serdar, Osman; Ketenalp, Zozan; Cikcikoglu Yildirim, Nuran
The purpose of this study was to measure the antioxidant parameters to examine the potential ameliorative impacts of the rare earth element (REE) cerium (Ce) in dimethoate (DM) induced toxicity in Dreissena polymorpha. Lethal concentration 50 (LC50) of DM for 96 h was measured. The antioxidant effect of Ce was investigated by exposure of 1/2 of the LC50 value of DM together with 4, 20 and, 100 mg/L of Ce to D. polymorpha. The responses of the biomarkers were determined by measuring the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione (GSH) and malondialdehyde (MDA) levels. SOD, CAT, GPX and GSH levels were reduced (p < 0.05), while the MDA levels increased significantly (p < 0.05) in mussels exposed to DM. When DM was exposured together with Ce, it was observed that the MDA levels decreased, SOD, CAT, GPX and GSH levels increased during 24 and 96 h. The results of our study showed that Ce exerted a strong antioxidant effect on toxicity induced by DM. It has been shown that Ce may have a compensatory effect with the positive change in the antioxidant response of D. polymorpha to DM. This study is the first report about Ce and insecticide effects in bivalves.
AtıfScopus1WoS1OpenAlex1İncele - Kitap BölümüYalnız künye2023Metaverse and New Narrative: Storyliving in the Age of Metaverse
Deniz, Kemal
Today, technology continues to develop rapidly. As in many fields, innovations are emerging that will change the social, cultural, and economic relations that affect people’s daily lives. The process, which started with the opening of the door of the virtual world, which is said to be more advanced than ever, with VR, seems to reach a new dimension with the introduction of the concept of the metaverse. In addition to the innovations and effects it will bring in all other economic and financial related processes such as Cryptocoin, NFT, blockchain, Web3, the metaverse will also reveal a new narrative paradigm. It will be important to consider the narrative form in the metaverse era, which can be seen as an upshift of innovations from digital storytelling to the interactive narrative that emerged with the digital transformation. It is also important to consider the grand comprehensiveness of the metanarrative regarding the whole, the specificity of the narrative in the metaverse about each subject or object, and how this will be reflected in the big picture. As stated, in the metaverse era, how will the transition of the narrative to the storyliving stage rather than storytelling affect or result in the ontology of the processes of creating a narrative, conveying it through a medium, and being experienced by individuals? This study will be research on the concept of the metaverse and the questioning of the narrative concerning the social, cultural, and economic fields transformed by technology.
AtıfScopus6OpenAlex5İncele - Kitap BölümüAçık Erişim2023Production technique–structure relationship in bioceramic-coated scaffold applications
Aslan, Naim; Topuz, Mehmet; Aksakal, Bunyamin; Dikici, Burak
It is well known that the surface of metal-based implants is very resistive in aggressive body environments due to the noble oxide layer naturally formed on their surfaces. However, their osseointegration properties are very low. By the way, specific cells attached are desired on the implant surface when the surface of an implant connects with tissue in many circumstances. Thus in parallel with technological developments, biomedical engineering focuses on the growth of new tissue on the implant surface or in the porosities of the implant. The bulk properties of metallic scaffolds, especially Young’s modulus, can be controlled by the porosity ratio of the scaffold but cannot form a bond between the implant and tissue interfaces. Thus the coating of scaffold walls with a bioactive material is required. In this chapter, bioceramic coating techniques of scaffolds, mechanical and corrosion behavior, biocompatibility, and interactions of surface/tissue interface, especially considering the last published reports, were reviewed, in detail.
AtıfScopus4OpenAlex4İncele - MakaleAçık Erişim2023Scopus SJRQ2Surface Morphology, Structural, Photovoltaic and Optoelectronic Properties of Diamond Like Carbon-Copper Nanostructures
Kara, Salih; Aslan, Naim; Kurt, Mustafa Şükrü
In this work, we produced Cu doped diomond like carbon films using the magnetron sputtering technique and assessed their structural electrical and optoelectronic characteristics. In the atomic force microscopy (AFM) measurements, it was observed that the surface of the Cu-DLC nanocomposite films was in a granular form and the presence of cluster-like formations. D and G bands, which are the characteristic peaks of the DLC structure, were observed in the Raman spectrum, while Cu and C peaks were observed in the energy dispersive (EDX) spectrum. Photocurrent, photocapacitance, photosensitivity and photoresponse values increased depending on the increasing light intensity. However, the Cu-DLC/n-Si structure displayed low photovoltaic properties. The capacitance and conductance values were considerably affected by the increase in AC signal frequency. The series resistance and the density of the interface states exhibited low frequency dependent behavior which were obtained using the electrical characteristics of the nanocomposite films.
AtıfScopus7WoS7OpenAlex6İncele - MakaleAçık Erişim2021Scopus SJRQ2Hospital Preparedness Assessment against COVID-19 Pandemic: A Case Study in Turkish Tertiary Healthcare Services
Gul, Muhammet; Yucesan, Melih
Hospitals play a critical role in providing essential health services to people in the healthcare system. Healthcare systems around the world have faced some issues in responding to patients with various disease severity levels. Nowadays, the world as a whole is combating a pandemic called COVID-19. This pandemic causes an increase in the disease spread with fluctuated patient demand that may affect the hospitals' capacity and overall functioning and risks rising based on hospital site, medical staff, patient, and healthcare process. To deal with the challenges of the COVID-19 pandemic, hospitals must have completed their preparations before these events occur. Therefore, this study proposes an integrated approach based on the decision-making concept with interval-valued spherical fuzzy sets (IVSFSs) to the hospital preparedness assessment problem. A technique for order preference by similarity to ideal solution (TOPSIS) extended with IVSFSs is used to rank hospitals from Turkish tertiary healthcare services. A checklist reported by the World Health Organization (WHO) is adapted to conform to Turkey's COVID-19 pandemic management. Ninety-nine subcomponents of the adapted checklist under ten components are weighted by interval-valued spherical weighted arithmetic mean (IVSWAM) operator. The hospitals in the problem are then ranked concerning these weighted subcomponents. With the proposed approach, a COVID-19 pandemic preparedness index is determined for the observed hospitals. In addition, a separate index based on each main component (component-based ranking) is determined. These indexes are vital indicators in determining in which aspects hospitals are ready and in what aspects hospitals are not prepared for pandemics. The proposed approach can be adaptable and applied by national policymakers in assessing all hospitals of the country against the COVID-19 pandemic.
AtıfScopus45WoS33OpenAlex44İncele - MakaleYalnız künye2022Scopus SJRQ1In vivo and in vitro evolution of the effects of cypermethrin on turbot (Scophthalmus maximus, Linnaeus, 1758) spermatozoa
Beken, Atife Tuba; Saka, Şahin; Aydın, İlhan; Fırat, Kürşat; Suzer, Cüneyt; Benzer, Fulya; Erişir, Mine; Özden, Osman; Hekimoğlu, Müge Aliye; Engin, Serhat
Synthetic pyrethroid pesticide is commonly used in agricultural activities in the Black Sea region during reproduction period of turbot. In this sense, in vivo and in vitro studies have shown that cypermethrin (CYP) could be one of the environmental factors affecting decreasing turbot stocks. In this study, effects of in vivo and in vitro administration of CYP, a synthetic pyrethroid, on sperm kinematics motility (MOT), progressive motility (PM), curvilinear velocity (VCL), straight line velocity (VSL), average path velocity (VAP), linearity (LIN), straight line velocity (STR), amplitude of lateral head (ALH), beat cross frequency (BCF), oxidative stress biomarkers malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and lipid peroxidation (LPO) and also histopathological alterations in gonads were investigated in spermatazoa of turbot (Schopthalmus maximus). Broodstock was supplied from culture origin and used in spawning season, additionally, two (0, 0.187 and 0.218 ppb) and three (0, 1.025, 2.05 and 4.1 ppb) different CYP concentrations were performed for in vivo and in vitro studies, respectively. In vivo and in vitro studies, significant reductions were found in sperm MOT, PM, VCL, VSL, VAP, LIN, and ALH properties depend on the increase in CYP concentrations (p < 0.05). Besides, activities of GSH, GPx, SOD, and CAT increased. In terms of histological alterations, no difference was observed among groups (0, 0.187 and 0.218 ppb) in the maturity stage of the germ cells. According to obtained results, sperm kinematics was affected significantly with increased the dose levels of CYP (p < 0.05).
AtıfScopus6OpenAlex8İncele - MakaleAçık Erişim2023Scopus SJRQ3Performance evaluation of steel-concrete composite structures designed in poorly graded soils
Etli, Serkan
In this study, the seismic behavior of steel concrete composite buildings in a specific region was investigated. For this purpose, 5-, 10-, 15- and 20-storey composite moment-resisting framed structures were designed. Moment-resist-ing composite framed structures are modeled with concrete-filled steel tube columns and designed and modeled using composite beams. The buildings are designed according to ÇYTHYE-2016 and TBEC-2018 regulations at design levels with high ductility. In the design of the designed structures, the peak ground acceleration value is 0.79 g, and the design ground is planned as ZE class. SeismoStruct software was used for the design and performance evaluation of the structures. During the performance evaluations of the structures, nonlinear static pushover and incremental dynamic analyzes were used. Uniform and triangular load distributions are adopted in the static pushover analysis and 16 earthquake ground mo-tions are used in the incremental dynamic analysis. Evaluation of the effect of the number of stories on the earthquake behavior of composite moment-resisting framed structures was investigated using the non-linear analyzes mentioned. Ac-cordingly, lateral response, overstrength factors, ductility, and dynamic behavior factor values for composite frame struc-tures were calculated and presented using the relevant analysis results. It has been calculated that the behavior factor of all moment-resisting composite framed structures can perform well above the design assumptions, whereas moment-resistant composite framed structures absorb seismic energy by using inelastic deformations. Ductility is almost 30% higher than the design assumption for international standards. As a result, it was concluded that these structures could continue to serve theoretically.
AtıfScopus6WoS3OpenAlex9İncele - MakaleYalnız künye2023Scopus SJRQ3Thermal Device Beyond the Carnot Limit
Zengin, B.; Askin, M.; Salti, M.; Aydogdu, O.
Based on the Carnot cycle, we construct a theoretical heat engine working through the agency of the generalized polytropic gas. A heat engine described by using a thermodynamic equation-of-state defines a thermodynamical relation among state quantities such as internal energy U, volume V, entropy S, temperature T and heat capacity C. Investigating the thermal efficiency of the constructed heat engine shows that more efficient heat engine is obtained from the Carnot heat engine when the pressure of the working material takes certain values.
AtıfOpenAlex1İncele - MakaleYalnız künye2022Scopus SJRQ2Data-driven predictive modeling of Hubble parameter
Salti, Mehmet; Ciger, Emel; Kangal, Evrim Ersin; Zengin, Bilgin
We redesign the generalized pressure dark energy (GPDE) model, which is covering three common types of pressure parameterizations, with the help of a caloric framework to construct a theoretical ground for the machine learning (ML) analysis of cosmic Hubble parameter. The theoretical setup was optimized to find out appropriate values of its arbitrary parameters with the help of genetic neural network (GNN) algorithm and the most recent observational measurements of Hubble parameter. Since there is a shortcoming that the GNN process does not provide a direct method to calculate errors on the optimized values of free model parameters, we therefore take the Fisher Information Matrix (FIM) algorithm into account to deal with this issue. We see that the best-fitting value of Hubble constant and dimensionless dark energy density are in very good agreement with the most recent observations. Also, we discussed the optimized model from a cosmological perspective by making use of the evolutionary behavior of some cosmological parameters to present additional cosmological aspects of our theoretical proposal. It is concluded that our model implies physically meaningful results. In summary, the constructed model can explain the current accelerated expansion phase of the cosmos via Hubble parameter successfully.
AtıfScopus7WoS5İncele - MakaleAçık Erişim2022Scopus SJRQ1Newly synthesized NiCoFeCrW High-Entropy Alloys (HEAs): Multiple impacts of B4C additive on structural, mechanical, and nuclear shielding properties
Gul, Ali Oktay; Kavaz, Esra; Basgoz, Oykum; Guler, Omer; ALMisned, Ghada; Bahceci, Ersin; Albayrak, M. Gokhan; Tekin, H.O.
High-Entropy Alloys (HEAs) are regarded as potential structural materials for fusion and next-generation fission reactors, which will be required to fulfil growing nuclear energy demands. In this study, a HEA-composite was synthesized by adding B4C to an HEA containing Ni. The microstructure of the obtained HEA-composite was examined and the changes in its mechanical properties were revealed. Additionally, the nuclear radiation shielding properties of the Ni-containing HEA, and the HEA-composite are investigated using experimental and theoretical methods. Our initial findings showed that with the addition of 2.5% B4C to the alloy, the hardness increased more than two times. The addition of B4C to the HEA matrix resulted in a more than 90% and a nearly twofold increase in compressive strength. The shielding qualities of gamma-ray and neutron radiation were investigated using experimental and theoretical approaches. Our findings demonstrated that increasing the B4C reinforcement considerably enhanced the composite material's neutron attenuation capabilities. On the other hand, no significant change in the gamma-ray shielding characteristics of HEA and HEA-composite samples was observed. The gamma-ray shielding characteristics of HEA and HEA-composite samples were compared to those of other alloy shields and commercial products. Our findings indicate that both HEA and HEA-composite samples exhibit superior gamma-ray shielding characteristics when compared to the control samples. It can be concluded that increasing B4C reinforcement may be a multifunctional tool in terms of improving the mechanical properties as well as neutron attenuation properties for advanced applications in nuclear radiation facilities and next-generation fission reactors. Additionally, due to their promising material features and higher gamma-ray shielding capabilities compared to other kinds of alloys and commercial shields, HEAs may be beneficial materials.
AtıfScopus33OpenAlex31İncele - MakaleYalnız künye2022Scopus SJRQ2Theoretical Models for Tie Bar Maximum Axial Force Demand in Composite Plate Shear Walls–Concrete Filled
Polat, Erkan
This paper presents theoretical models developed for the prediction of the maximum axial force demands of tie bars of planar composite plate shear walls–concrete filled (C-PSW/CF). In the development of the theory, a previously benchmarked finite element (FE) wall model was used with some modifications. The results from the FE models were used to demonstrate the formation of the tie bar axial force demands, passive lateral confining pressure, concrete confinement, effectively confined concrete core and to develop theoretical models for the prediction of tie bar maximum force demands. The proposed method accounts for various aspects of wall geometry such as horizontal and vertical tie bar spacings, steel plate thickness, and wall thickness. The predictions of the proposed theoretical models were compared with the predictions of FE analyses by performing a parametric study involving C-PSW/CF having different tie bar spacings, plate thickness, wall thickness, and wall depths. Past experimental research available in the literature were used to evaluate the significance of the theoretical model in predicting tie bar maximum axial force demands. Tie bar axial force demand due to the confinement effect is not currently considered in the design of tie bars and there is no theoretical approach in the literature that considers the effect of confinement on the tie bar axial force demand. The theoretical models presented in this study allow the determination of the maximum axial force demands due to the confinement effect on planar C-PSW/CF tie bars without the need for complex and costly numerical analysis.
AtıfScopus7WoS6OpenAlex6İncele - MakaleAçık Erişim2023Scopus SJRQ1An Integrated Approach for Assessing Suppliers Considering Economic Sustainability Innovation
Ahmadi, Hadi Badri; Pamucar, Dragan; Pourhejazy, Pourya; Kaya, Sema Kayapinar; Liou, James J. H.
Innovation plays a key role for improving the sustainability performance of corporations. A truly sustainable innovative firm needs to take the social, environmental, and economic aspects of sustainable innovation into consideration. However, limited studies have investigated the economic aspect of sustainable innovation, especially in the context of supplier evaluation from emerging economies. To deal with this issue, this manuscript puts forward a criteria decision framework for evaluating economic sustainable innovative suppliers. A new methodology based on fuzzy Full Consistency Method (FFUCOM) and Improved Combinative Distance-based Assessment (ICODAS) is developed and extended using interval rough Dombi-Bonferroni operators. In the developed approach, the FFUCOM is employed to determine the criteria weights, and the ICODAS is responsible for assessing and ranking the suppliers. A case study from the manufacturing sector of an emerging economy is considered for validating the developed framework and decision model. The findings introduce the 'financial resumption of products' as the most critical economic innovation criterion for evaluating suppliers. This article significantly helps decision-makers and practitioners to better comprehend the underpinnings of sustainable innovation economic dimension, particularly when assessing their suppliers. Furthermore, the applicability and validity of the proposed model was confirmed by the results of sensitivity analysis. Findings demonstrated that the proposed method is a solid and useful MCDM framework, and its outputs are precise and acceptable.
AtıfScopus9OpenAlex6İncele - MakaleAçık Erişim2021Scopus SJRQ1Carbon and water balance of an afforested shallow drained peatland in Iceland
Bjarnadottir, Brynhildur; Aslan Sungur, Guler; Sigurdsson, Bjarni D.; Kjartansson, Bjarki T.; Oskarsson, Hlynur; Oddsdottir, Edda S.; Gunnarsdottir, Gunnhildur E.; Black, Andrew
Drainage of peatlands increases the depth of the oxic peat layer and can turn them into a carbon (C) source to the atmosphere. Afforestation of drained peatlands could help to reverse this process since the trees may enhance C sequestration. We followed the C and water dynamics of an afforested drained peatland in S-Iceland during a 2 year period, during which the Black Cottonwood (Populus balsamifera ssp. trichocarpa) plantation was 23–25 year old. Net ecosystem exchange (NEE) of carbon dioxide (CO2) was measured with the eddy covariance method and C pools of trees and ground vegetation were measured using the stock change method. Lateral losses of dissolved and particulated organic C (DOC, POC) were estimated from weekly water-runoff samples. Unexpectedly, the afforested drained peatland was a strong sink of carbon during the two years, with an average NEE value of 714 g C m−2 yr−1. Only 0.5% of the total NEE was lost through lateral DOC and POC transport, leaving 710 g C m−2 yr−1 as the total net ecosystem production (NEP). Ca. 91% of the observed NEP could be explained by the annual biomass increment of the Black Cottonwood trees and 1.3% by the ground vegetation. This means that the remaining 7.5% of the total NEP most likely accumulated in peat soil and litter, contributing to the soil C stocks. The dormant-season CO2 emissions were unexpectedly low, which was explained by a high groundwater level at this drained site outside the ca. 5 months of the active growing season. On average, 66% of the annual measured precipitation was estimated to have evaporated back to the atmosphere. This left 416 mm for potential runoff, which was somewhat lower value than the measured runoff (662 mm). These results indicate that during the age span of ca. 20–25 years, afforestation was a valid method to reverse the expected negative C-balance of this drained grassland pasture in Iceland. Although the site is currently a soil C sink, simulation studies with process models are needed to test whether such sites could remain C sinks when managed for forestry over several tree-stand rotations.
AtıfScopus18OpenAlex21İncele - MakaleYalnız künye2021Scopus SJRQ1Using Ochrobactrum thiophenivorans and Sphingomonas melonis for bioremediation of Imidacloprid
Erguven, Gokhan Onder; Demirci, Ulas
To solve the environmental problems of the pesticides, bioremediation methods are commonly useful for their environment friendly properties. These methods are more cheap, useful and have more advantages for remediate receiving environments In this study, imidacloprid which is one of the selective insecticide in all over the world is chosenfor bioremediation studies with two soil bacteria. The imidacloprid used in the Mediterranean climate for cotton, pistachios, tomatoes, peppers and eggplant cultivation. The bioremediation of this insecticide was investigated via the performance of O.thiophenivorans and S. melonis in agitated culture media. The agricultural soil used for the isolation of these two bacteria was taken from the cotton cultivated agricultural area in Adana province in Turkey. For this purpose, the isolated and enriched bacteria were added to the recommended insecticide concentrations, and the Imidacloprid active material, Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD5), Total Organic Carbon (TOC), pH and dissolved oxygen (DO) parameters were determined for two weeks on each day of the study. O. thiophenivorens and S. melonis bioremediate the Imidacloprid insecticide with high efficiency (over 90%). According to these results, it is understood that these bacteria can be preferred in the bioremediation of receiving environments that are contaminated with such pesticides and can be useful for scientists to handle the opposite effects of such persistent organic pollutants and COD, BOD5 and TOC parameters can easily give opinions about decreasing of pesticides like the active materials
AtıfScopus28WoS27OpenAlex30İncele - MakaleAçık Erişim2022Scopus SJRQ2Stability Analysis of Buoyancy Magneto Flow of Hybrid Nanofluid through a Stretchable/Shrinkable Vertical Sheet Induced by a Micropolar Fluid Subject to Nonlinear Heat Sink/Source
Khan, Umair; Zaib, Aurang; Ishak, Anuar; Alotaibi, Abeer M.; Eldin, Sayed M.; Akkurt, Nevzat; Waini, Iskandar; Madhukesh, Javali Kotresh
The utilization of hybrid nanofluids (HNs) to boost heat transfer is a promising area of study, and thus, numerous scientists, researchers, and academics have voiced their admiration and interest in this area. One of the main functions of nanofluids is their dynamic role in cooling small electrical devices such as microchips and associated gadgets. The major goal of this study is to perform an analysis of the buoyancy flow of a shrinking/stretching sheet, whilst considering the fascinating and practical uses of hybrid nanofluids. The influence of a nonlinear heat source/sink induced by a micropolar fluid is also inspected. Water-based alumina and copper nanoparticles are utilized to calculate the fine points of the fluid flow and the features of heat transfer. The governing equations are framed with acceptable assumptions and the required similarity transformations are used to turn the set of partial differential equations into ordinary differential equations. The bvp4c technique is used to solve the simplified equations. Dual solutions are presented for certain values of stretching/shrinking parameters as well as the mixed convective parameter. In addition, the shear stress coefficient in the first-branch solution (FBS) escalates and decelerates for the second-branch solution (SBS) with the superior impact of the magnetic parameter, the mass transpiration parameter, and the solid nanoparticles volume fraction, while the contrary behavior is seen in both (FB and SB) solutions for the larger values of the material parameter.
AtıfScopus22OpenAlex27İncele
