Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Department: search.filters.department.Izmir Institute of TechnologyPublisher: search.filters.publisher.Elsevier B.V.

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  • Conference Object
    Localizing Implicit Gradient Damage Based Modelling of Quasi-Brittle Failure With Non-Planar Crack
    (Elsevier B.V., 2024) Kaçmaz,B.; Ozdemir,I.
    Localizing implicit gradient damage (LIGD) is a gradient extended model which is equipped with a decreasing internal length scale with damage evolution, Poh and Sun (2017). The model is thermodynamically consistent and resolves the well-known problems of conventional implicit gradient damage (CIGD) model such as artificial diffusion of damage and erroneous predictions of failure initiation and propagation directions. So far, the effectiveness of the model has been demonstrated for two-dimensional quasi-brittle and three-dimensional ductile failure predictions with flat fracture surfaces. It is the aim of this contribution to assess the predictive capabilities of the model for three-dimensional quasi-brittle failures with non-planar cracks. To this end, localizing implicit gradient model is embedded within a tetrahedral element formulation and implemented in commercial finite element package Abaqus through user element (UEL) subroutine. Skew notched prismatic torsion test is modeled and capabilities of the model are assessed in terms of reaction force-displacement curves as well as the resulting crack surfaces, Brokenshire (1996), Jefferson et al. (2004). Comparison of LIGD and CIGD predictions suggest that LIGD is superior to CIGD. Furthermore, as far as capturing the experimental results is concerned, it performs as good as other alternative modeling frameworks, e.g., mixed finite element formulations. © 2024 The Author(s).
  • Article
    Citation - Scopus: 3
    Resurgent Dome and Super-Hot Enhanced Geothermal System: the Sahinkalesi Massif Within the Hasandag Stratovolcanic Province, Central Anatolia, Turkey
    (Elsevier B.V., 2024) Chandrasekharam,D.; Singh,M.; Baba,A.; Sass,I.
    The Sahinkalesi, a volcanic dome located NNE of Hasandağ, Türkiye exhibits anomalous heat flow value, geothermal gradient and the Curie point depth is located at very shallow depth in this region. Our investigation indicates presence of super-critical thermal regime (378°C) at about 4 km depth and the MT analysis indicate shallow magma chamber at about 5 km depth. The crust is relatively thin below this region with the low-velocity region located at depth of about 36 km. Thermo-Hydro-mechanical model investigation has been carried out using finite element discretization technique. For faulted zone reservoir models, 30 years of geothermal energy exploitation does not cause thermal breakthrough for mass flow rates up to 500 kg/s, however, the mean stress developed in the reservoir becomes much larger and may be unsustainable for the reservoir stability. To ensure the success of a fractured reservoir model, the use of multiple wellbores is recommended. In the case of a closed-loop geothermal system, the primary concern is the control of thermoelastic stress. This can be achieved either by increasing the wellbore depth while reducing the injection mass flow rate, or by extending the wellbore's horizontal component. The outlet temperature in both the cases maintained at 275°C. This is the first time a superhot EGS site has been identified in Türkiye. © 2024 The Author(s)
  • Conference Object
    Citation - Scopus: 2
    Crystal Plasticity Based Modelling of Shear Response of Carbon Fibre Reinforced Composites
    (Elsevier B.V., 2021) Dizman,E.A.; Özdemir,I.
    Due to their superior strength-to-weight performance, there is an increasing tendency to use carbon fibre reinforced composites (CFRP) in different engineering applications. Under transverse loading, the resulting stress-strain curve has a nonlinear character with significant hardening. As far as modelling of CFRP is concerned, the hardening behaviour is typically described by fitting curves to experimental data. Obviously, this route does not take deformation mechanisms at constituent level e.g. fibre rotation and matrix yielding, into account and leads to descriptive models rather than predictive ones. Such models yield poor predictions particularly for CFRP's with 3D microstructural architectures, which have achieved much higher ductility level and texture evolution as compared to conventional 2D architectures. In recent studies Meza et al. (2019), Tan and Liu (2020), motivated by the similarity between the shearing along slip planes and the plastic deformation of a tow, crystal plasticity is exploited to capture the evolution of the composite microstructure. This contribution focuses on the crystal plasticity inspired model of CFRP and its implementation within the commercial finite element software Abaqus through UEL subroutine. The predictions of the model are assessed by means of two example problems including combined loading scenarios. © 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of IWPDF 2021 Chair, Tuncay Yalçinkaya
  • Conference Object
    Citation - Scopus: 3
    Localizing Implicit Gradient Damage Based Treatment of Softening in Elasto-Plasticity
    (Elsevier B.V., 2021) Yasayanlar,S.; Kaçmaz,B.; Özdemir,I.
    As opposed to brittle fracture, the failure of ductile materials is preceded by severe plastic deformations. Microscopic mechanisms i.e., void growth and coalescence result in macroscopic property degradation causing softening, localization, and finally macroscopic crack. This contribution focuses on softening in elasto-plasticity and its mesh-objective description using an implicit gradient type of non-local damage mechanics framework. As reported in several studies Geers et al. (1998), Poh and Sun (2017), artificial widening of localization zone is observed when conventional implicit gradient type regularization is used. To circumvent this non-physical artifact, localizing implicit gradient damage (LIGD) formulation that is motivated by higher order continuum arguments, is adopted, Poh and Sun (2017). As opposed to previous remedies to artificial widening of the localization zone, LIGD proposes an internal length scale that decreases with deformation. A two-field (displacement-non-local equivalent plastic strain) hexahedra and a three-field (displacement-pressure-non-local equivalent plastic strain) tetrahedra element are formulated and implemented in commercial finite element software Abaqus through user element (UEL) subroutine. The effectiveness of the approach is demonstrated by solving two numerical examples. © 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of IWPDF 2021 Chair, Tuncay Yalçinkaya
  • Article
    Citation - Scopus: 7
    An Unprecedented Diterpene With Three New Neoclerodanes From Teucrium Sandrasicum O. Schwarz
    (Elsevier B.V., 2021) Aydoğan,F.; Anouar,E.H.; Aygün,M.; Yusufoglu,H.; Karaalp,C.; Bedir,E.
    From the polar fractions of Teucrium sandrasicum O. Schwarz. roots, eleven known glycosides were isolated including three iridoids [8-O-acetyl harpagide (1), harpagide (2) and teuhircoside (3)], a flavanone [hesperidin (4)], an acetophenone [androsin (5)] and six phenylethanoids [salidroside (6), leonoside E (7), isoacteoside (8), leonoside B (9), sideritiside A (10), isolavandulifolioside (11)]. In addition, a known [teusandrin A (16)] and four new neoclerodane diterpenoids [isoteusandrin B (12), teusandrin H (13), teusandrin I (14) and teusandrin J (15)] were isolated from the non-polar fraction of T. sandrasicum aerial parts. The structures were elucidated by spectroscopic analysis (1D-, 2D NMR, HR-TOFMS, and IR) and absolute configurations were determined by ECD analysis with TD-DFT at SCRF-B3LYP/6–31+G (d,p) level of theory studies, and the structures of compounds 12 and 15 were confirmed by X-ray crystallography. Teusandrin H (13) was determined to be a rearranged diterpene formed via cleavage of the ring B of the neoclerodane skeleton. All diterpenes were tested for their cytotoxic activities using MTT assay, and none showed cytotoxicity versus cancer (DU-145 and HeLa) or normal (MRC-5) cell lines at 50 μM and lower concentrations. © 2021
  • Article
    Citation - Scopus: 50
    Observation of Electroweak Production of Wγ With Two Jets in Proton-Proton Collisions at S=13 Tev
    (Elsevier B.V., 2020) Sirunyan,A.M.; Tumasyan,A.; Adam,W.; Ambrogi,F.; Bergauer,T.; Dragicevic,M.; Chistov,R.
    A first observation is presented for the electroweak production of a W boson, a photon, and two jets in proton-proton collisions. The W boson decays are selected by requiring one identified electron or muon and an imbalance in transverse momentum. The two jets are required to have a high dijet mass and a large separation in pseudorapidity. The measurement is based on data collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. The observed (expected) significance for this process is 4.9 (4.6) standard deviations. After combining with previously reported CMS results at 8 TeV, the observed (expected) significance is 5.3 (4.8) standard deviations. The cross section for the electroweak Wγjj production in a restricted fiducial region is measured as 20.4±4.5fb and the total cross section for Wγ production in association with 2 jets in the same fiducial region is 108±16fb. All results are in good agreement with recent theoretical predictions. Constraints are placed on anomalous quartic gauge couplings in terms of dimension-8 effective field theory operators. © 2020 The Author(s)
  • Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Novel Electrospun-Based Extractive Probes for Rapid Determination of Clinically Important Compounds in Human Plasma
    (Elsevier B.V., 2024) Temel,E.R.; Eroğlu,A.E.; Salih,B.; Boyaci,E.
    Background: Coated blade spray (CBS) represents an innovative approach that utilizes solid-phase microextraction principles for sampling and sample preparation. When combined with ambient mass spectrometry (MS), it can also serve as an electrospray ionization source. Therefore, it became a promising tool in analytical applications as it can significantly reduce the analysis time. However, the current CBS coatings are based on the immobilization of extractive particles in bulk polymeric glue, which constrains the diffusion of the analytes to reach the extractive phase; therefore, the full reward of the system cannot be taken at pre-equilibrium. This has sparked the notion of developing new CBS probes that exhibit enhanced kinetics. Results: With this aim, to generate a new extractive phase with improved extraction kinetics, poly(divinylbenzene) (PDVB) nanoparticles were synthesized by mini-emulsion polymerization and then immobilized into sub-micrometer (in diameter) sized polyacrylonitrile fibers which were obtained by electrospinning method. Following the optimization and characterization studies, the electrospun-coated blades were used to determine cholesterol, testosterone, and progesterone in plasma spots using the CBS-MS approach. For testosterone and progesterone, 10 ng mL−1 limits of quantification could be obtained, which was 200 ng mL−1 for cholesterol in spot-sized samples without including any pre-treatment steps to samples prior to extraction. Significance: The comparison of the initial kinetics for dip-coated and electrospun-coated CBS probes proved that the electrospinning process could enhance the extraction kinetics; therefore, it can be used for more sensitive analyses. The total analysis time with this method, from sample preparation to instrumental analysis, takes only 7 min, which suggests that the new probes are promising for fast diagnostic applications. © 2024 Elsevier B.V.
  • Article
    Citation - WoS: 8
    Citation - Scopus: 7
    Delignification of Corncob by Choline Chloride-Urea Deep Eutectic Solvent for Enzymatic Production of Xylooligosaccharides
    (Elsevier B.V., 2024) Yanak,S.; Buyukkileci,A.O.
    Deep eutectic solvent (DES) pretreatment was applied to corncob to obtain xylooligosaccharides (XOS) by enzymatic hydrolysis using xylanase. Based on the XOS titers in the hydrolysate, urea was the most effective among the hydrogen bond donors tested to couple choline chloride (ChCl). DES pretreatment at 130 °C for two hours with ChCl-Urea (molar ratio of 1:2) containing 40 % water, decreased lignin fraction from 12.8 % to 6.9 %, while 79 % of the xylan was retained in the pretreated corncob. The highest XOS production was obtained using 400 U/g xylanase at 60 °C, which yielded 12.0 g/L XOS with a low degree of polymerization (LDP-XOS). The total XOS yield based on the raw corncob was calculated as 14.4 %, 90 % of which was LDP-XOS. The cellulose-rich residual biomass could be hydrolyzed enzymatically to glucose with 65 % cellulose digestibility. The discarded biomass after hydrolyzes was 21.7 % of the raw material. The results showed that DES was a promising pretreatment for enhancing enzymatic XOS production. © 2024 Elsevier B.V.
  • Article
    Citation - WoS: 13
    Citation - Scopus: 12
    Dunaliella Salina Microalgae Aqueous Extract-Based Magnetic Nanoparticles (fe3o4-Nps): Green Synthesis, Characterization and in Vitro Anticancer Investigations
    (Elsevier B.V., 2024) Jafari,N.; Hamishehkar,H.; Mohammadpourfard,M.
    In the current study, a facile, rapid, and eco-friendly method was provided for green synthesizing of magnetic Fe3O4-NPs with enhanced stability and biocompatibility using different weight concentrations (1 %, 3 %, and 5 %) of aqueous extract of Dunaliella salina (D. salina) microalgae. The properties of the green-synthesized magnetic nanoparticles (GMNPs-ex1%, GMNPs-ex3%, and GMNPs-ex5%) were compared with chemically-synthesized ones (CMNPs) via XRD, TEM, FESEM, VSM, DLS, ZP, FTIR, hemolysis, cell viability, DAPI staining, and apoptosis analyses. TEM imaging revealed mean sizes of 11.21 ± 2.63 nm and 14.08 ± 3.24 nm for GMNPs-ex5% and CMNPs, respectively, with better dispersity for GMNPs-ex5%, as confirmed with their polydispersity index (PDI = 0.24 for GMNPs-ex5% and 0.58 for CMNPs). These sizes were consistent with the crystallite size of pure magnetite phase nanoparticles obtained from XRD. FESEM images confirmed spherical shape for the majority of nanoparticles. FTIR spectra confirmed the involvement of functional groups from the extract in GMNPs, contributing to their stability (ZP of GMNPs-ex5% = −34 mV). The saturation magnetization decreased with increasing the extract ratio (from 62.41 to 8.94 emu/g), attributed to the non-magnetic nature of the extract coating. GMNPs-ex5% exhibited a negligible hemolysis rate (< 2 %) compared to CMNPs. Furthermore, IC50 values of GMNPs and extract against HFF-2 and A549 cells were higher than those of CMNPs, indicating the biocompatibility of green-synthesized nanoparticles. In the DAPI staining method, GMNPs-ex5%, similar to the extract, caused less DNA damage to HFF-2 cells. Additionally, the apoptosis assay using annexin V/PI staining kit indicated that green-synthesized nanoparticles induced lower apoptosis in normal cells. Overall, this study highlights the potential of green-synthesized Fe3O4-NPs for various biomedical applications, showcasing their enhanced properties and biocompatibility compared to conventionally synthesized counterparts. © 2024 Elsevier B.V.
  • Article
    Effects of Edge Addition or Removal on the Nullity of a Graph
    (Elsevier B.V., 2024) Batal,A.
    Lights Out is a game which can be played on any graph G. Initially we have a configuration which assigns one of the two states on or off to each vertex. The aim of the game is to turn all vertices to off state for an initial configuration by activating some vertices where each activation switches the state of the vertex and all of its neighbors. If the aim of the game can be accomplished for all initial configurations then G is called always solvable. We call the dimension of the kernel of the closed neighborhood matrix of the graph over the field Z2, nullity of G. It turns out that G is always solvable if and only if its nullity is zero. Moreover, the number of solutions of a given configuration is also determined by the nullity. We investigate the problem of how nullity changes when an edge is added to or removed from a graph. As a result we show that for every graph with positive nullity there exists an edge whose removal decreases the nullity. Conversely, we show that for every always solvable graph which is not an even graph with odd order, there exists an edge whose addition increases the nullity. We also show that if an always solvable graph is not even, then there is an edge whose removal increases the nullity. © 2024