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Sakarya Üniversitesi Fen Bilimleri Enstitüsü Dergisi
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  This is an Open Access Journal Open Access journal
ISSN (Print) 1301-4048 - ISSN (Online) 2147-835X
Published by Sakarya Üniversitesi Homepage  [3 journals]
  • Characterization Of Jute/Aramid Hybrid Composite Materials with Using
           Different Resins

    • Authors: Berkay KARACOR; Mustafa ÖZCANLI
      Abstract: For the last twenty to thirty years, interest in the use of hybrid fiber-reinforced composites has gradually increased due to their potential for various applications. The balanced strength and stiffness properties of hybrid composites, along with the advantages of lighter weight and lower cost, have made them an important step toward replacing traditional materials. In this study, a hybrid composite was made from a combination of Jute fabric from natural fibers, Aramid fabric from synthetic fibers, and two different resins (polyester and vinylester). This type of study was proposed because there is little research in the literature on how the use of polyester and vinyl ester resins affects the mechanical properties of homogeneous composites and hybrid composites. The vacuum assisted resin transfer molding process was used for the fabrication. The mechanical properties of the manufactured products were determined by tensile and hardness tests, and their morphological structures were examined by taking scanning electron microscope images. The results indicate that the value of tensile strength and elastic modulus of the Jute/Aramid hybrid samples in the productions prepared with polyester resin is 37.6% and %12.28, respectively, higher than in those made with vinyl ester resin. When comparing the values for microhardness, the results of the Jute/Aramid hybrid specimens produced with polyester resin were 1.20 times higher than those produced with vinyl ester resin. Scanning electron microscope images of the samples also clearly show that the bonding between matrix and fiber is better in polyester resin samples.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • Characterization of Cobalt Oxalate Dihydrate Obtained from Spent
           Co-Mo/Al2O3 Hydrodesulfurization Catalyst

    • Authors: Ahmet Orkun KALPAKLI
      Abstract: In this study, roasted spent Co-Mo/Al2O3 hydrodesulfurization (HDS) catalyst was dissolved in oxalic acid (H2C2O4) solution and optimum conditions were determined for obtaining cobalt oxalate dihydrate (CoC2O4∙2H2O). The thermal decomposition behavior of the obtained CoC2O4∙2H2O was investigated by TG/DTG-DTA analysis. The characterization of CoC2O4∙2H2O was carried out by XRD, FT-IR and SEM-EDS analytical techniques. Optimum conditions for the production of CoC2O4∙2H2O were determined as 25 oC temperature, 0.25 M H2C2O4 concentration, 1/20 g mL-1 solid/liquid ratio and 300 rpm stirring speed. CoC2O4∙2H2O was obtained with a reaction yield of 90.9 %. TG/DTG-DTA analysis carried out in dry air atmosphere showed that CoC2O4∙2H2O decomposed in two steps. In the first step that occurs between 118-196 oC temperatures, CoC2O4∙2H2O is dehydrated. In the second step, which occurs between 248-279 oC temperatures, it was determined that metallic cobalt was formed first, and then metallic cobalt was oxidized and converted into Co3O4 compound because it was performed in the air atmosphere.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • Electrochemical Performances of NMC811 Lithium-Ion Pouch Cells under
           Dynamic Conditions

    • Authors: Mahmud TOKUR
      Abstract: Lithium-ion batteries have a wide range of usage areas, from transportation to the defense industry, from daily usage to space applications. The widespread use of consumer electronics day by day also increases the need for this critical strategic technology, which allows us to live at almost every point of our lives without binding factors such as cables. But this technology also has many limitations, which dominate our lives so much that it needs to be overcome. Low cycle life due to poor electrochemical efficiency of electrode materials is one of these limitations. At the same time, energy density constraints are also an obstacle to many technological developments. Therefore, finding new materials with higher capacity and higher cycle life has become inevitable to meet the demands. Moreover, developing novel production techniques suitable for the materials used in the battery is also critical. Cylindrical cells are mostly used commercially in the market due to their easy and fast production technics and relatively safe components. However, the energy density and capacity limit of this architecture pushes the market to use alternative cell designs. There are different cell structures in the lithium-ion battery industry apart from cylindrical cells, such as button type, pouch type, and prismatic type. Among them, pouch cells have rising star geometry due to their unique properties and flexible production style. But many parameters still need to be overcome in pouch cells. In this study, the NMC811 cathode has been selected to investigate some critical parameters in lithium-ion pouch cells. The effects of dynamic conditions such as electrode film thickness, variable temperatures, and current rates on electrochemical performance were analyzed. Finally, a cycle life test was performed on the cell with optimum parameters.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • First Theoretical Identification of the Magnetic Dipole Moment of the
           97.43 keV State in 153Eu

    • Authors: Emre TABAR; Elif KEMAH, Hakan YAKUT, Gamze HOŞGÖR
      Abstract: Two alternative values, +3.21±0.22 μ_N and-0.52±0.22 μ_N, for the magnetic dipole (M1) moment of the excited [532] 5/2- state at 97.43 keV in 153Eu were reported in the Mossbauer-effect study. The Quasiparticle Phonon Nuclear Model (QPNM) has been used to determine the correct value of the magnetic moment of this state. According to the QPNM calculations, the experimental 97.43 keV level is the [532] 5/2- Nilsson state occurring at 79 keV. The QPNM predicted the magnetic moment of this state to be +3.2162 μ_N, which agrees well with one of the experimental values, i.e., +3.21±0.22 μ_N. Therefore, the correct value for the magnetic moment of the 97.43 keV level of 153Eu is most probably +3.21±0.22 μ_N. The measured value (+3.4717±0.006 μ_N) of the magnetic moment of 5/2- ground-state, which is probably a [532] Nilsson state according to our QPNM calculations, supports our prediction.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • Mold Design and Analysis for Multi-Component Plastic Injection Parts with
           Contrasting Functional Features: Case Study

    • Authors: Akın Oğuz KAPTI; Erdi ERTEKİN, Uğur ACUN
      Abstract: The classical plastic injection method is based on the principle of injecting a single color of a single polymeric material into the mold cavity under high pressure. In cases where the products are expected to have contrasted functional features and different colors, the classic injection process and the conventional injection molds are not sufficient. This paper proposes a new design approach for multi-component injection molds required by products containing different polymeric materials or different colors of the same polymeric material at the same time. It also presents a case study including the design of the hot runner, electromechanical rotary-cross, cooling, and ejection systems of a two-component, eight-cavity toothbrush mold. The polymeric materials are polypropylene for the first component, and styrene based thermoplastic elastomer for the second component, which exhibit good bonding properties with each other. In addition, an analysis study covering the filling parameters and production defect generations is also provided. The adopted design approach provides a production rate of 1600 parts per hour, corresponding to 18 s cycle time and 200 cycles per hour, and makes it sufficient to rotate only the 80 kg core plate instead of 1120 kg entire core side. Compared to existing methods, the results show that the proposed multi-component injection mold design method eliminates the need for particular injection machines and robotic systems, shortens the cycle time, and reduces energy consumption.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • Keyframe Extraction Using Linear Rotation Invariant Coordinates

    • Authors: Hasan MUTLU; Ufuk ÇELİKCAN
      Abstract: Keyframe extraction is a widely applied remedy for issues faced with 3D motion capture -based computer animation. In this paper, we propose a novel keyframe extraction method, where the motion is represented in linear rotation invariant coordinates and the dimensions covering 95% of the data are automatically selected using principal component analysis. Then, by K-means classification, the summarized data is clustered and a keyframe is extracted from each cluster based on cosine similarity. To validate the method, an online user study was conducted. The results of the user study show that 45% of the participants preferred the keyframes extracted using the proposed method, outperforming the alternative by 6%.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • A Remarkable Record of Little-Known Parasitoid Wasp Helorus striolatus
           (Hymenoptera: Heloridae) from Türkiye with A Global Checklist of the this
           Family

    • Authors: İlyas CAN
      Abstract: The Heloridae (Hymenoptera: Proctorupoidea) is a family of parasitoid wasps composed of a single genus, Helorus with eighteen extant species. For Türkiye, only two species have been reported: Helorus anomalipes (from Ankara, Central Anatolia) and H. striolatus (from Bingöl, Eastern Anatolia). In this study, a new distribution record is given for H. striolatus from Kocaeli province (Marmara region), which is the second record of this relatively little-known species in this country. In addition, an updated checklist of the family Heloridae is presented.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • Characterization of a New Thermostable Carboxylesterase from
           Aneurinibacillus sp. PDF24

    • Authors: Meral BELDUZ KOLCU; Fulya AY SAL, Ali BELDÜZ, Sabriye ÇANAKÇI
      Abstract: In this study, esterase of Aneurinibacillus sp. PDF24 strain, a thermophilic bacteria, was purified to homogenity (5.25 fold purification) by column chromotography, and characterized. The molecular weight of Aneurinibacillus sp. PDF24 esterase was determined about 40 kDa. The maximum activity of the purified esterase was analyzed at 55°C, pH 8.5. The esterase was found to be stable at 40ºC, 50ºC and 60ºC for 1 hour. Km and Vmax values for p-nitrophenyl butyrate were determined as 0.120 mM and 3164.8 U/mg, respectively. Considering Km values in the literature, Aneurinibacillus sp. PDF24 esterase was found to have a good Km value compared to other esterases. In the presence of 1 mM and 5 mM metal salts of Mg2+, Li+, Ca2+, K+, no significant change occured in enzyme activity. The activity of Aneurinibacillus sp PDF24 esterase was found to be stable also in the presence of ethanol, DMSO, EDTA, DTT and ß-mercaptoethanol. The data obtained suggest that the enzyme is a serine esterase, not a metalloprotein, and that disulfide bonds are not required to maintain enzyme conformation, and therefore, depending on its features, this esterase may be a suitable candidate for industrial applications.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • Spectroscopic Characterization and DFT Calculations on
           1H-benzimidazole-2-carboxylic acid monohydrate Molecule

    • Authors: Emine BABUR ŞAŞ; Songül ÇİFÇİ, Mustafa KURT
      Abstract: After first determining the optimized geometry of the 1H-benzimidazole-2-carboxylic acid monohydrate (1HBCM) molecule using the B3LYP/6-311+ + G (d, p) basis set, we investigated the spectroscopic properties, electronic properties and optical band gap of the molecule. We presented the fitted values of the vibrational frequencies of the molecule both as a table and as a spectrum and compared them with the experimental data. While the band gap energy (E) values of the molecule were calculated using HOMO and LUMO energies, the optical band gap (Eg) values of the molecule were obtained from the Tauc equation. We have given the Eg values of the molecule calculated for direct and indirect transmission by comparing them with the experimental data. In the article, we have also calculated and presented the data of the 1HBCM molecule such as MEP, Mulliken, and DOS.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • Mass Distributions and Neutron-Proton Ratios of Fragments in Peripheral
           Heavy-Ion Collisions

    • Authors: Hamide AVCI
      Abstract: The mass and average neutron-proton ratio (N/Z) distributions of fragments from multifragmentation of excited projectile nuclei formed in heavy-ion collisions were reproduced theoretically. The experimental measurements in peripheral heavy-ion collisions of 124Sn + 124Sn and 112Sn + 112Sn at 1 GeV/nucleon were carried out with the Fragment Separator (FRS) of GSI. The mass distribution and N/Z ratios of the produced nuclear fragments are calculated in the frame of a statistical approach. Comparisons with the experimental data show that the statistical models are successfully reproduce the mass yields and N/Z measured in the both reaction systems. The calculations in the present paper were carried out for the first time and were not published anywhere else.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • Determination of Resmethrin in Corn Silk Matrix by Gas
           Chromatography-Flame Ionization Detector (GC-FID)

    • Authors: Hakan SERBEST
      Abstract: The use of pesticides provides benefits such as growing food products necessary for life, sustainability of production efficiency and prevention of diseases caused by pests. However, these benefits can turn into negative effects for humans and other living organisms with the use of pesticides in inappropriate doses and application methods. In this study, it was aimed to determine resmethrin, which belongs to the insecticide class, by gas chromatography-flame ionization detector (GC-FID) method. Hence, a suitable temperature program was utilized to determine resmethrin at a certain retention time. Limit of detection (LOD) and limit of quantification (LOQ) values were recorded as 0.02 and 0.08 mg/L under the proposed conditions, respectively. After corn silk sample was extracted using acetonitrile, analytical measurements were carried out to investigate the presence of resmethrin. There was no analytical signal detected that belonged to resmethrin in the analyzed sample. Recovery experiments were performed using external calibration method with spiked samples at three different concentrations and good percent recovery results were obtained between 93 and 97%.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • Some Electrical and Photoelectrical Properties of Conducting Polymer
           Graphene Composite /n-Silicon Heterojunction Diode

    • Authors: Elif DAŞ
      Abstract: In this study, polythiophene-graphene (PTh-G) composite thin film was prepared on the n-type silicon (n-Si) semiconductor wafer by the spin coating method. Subsequently, the current-voltage (I-V) measurements were made on the fabricated Au/PTh-G/n-Si/Al device to ascertain the impact of the PTh-G interfacial layer on the device performance. The main device parameters such as ideality factor (n), barrier height (b), series resistance (Rs) were calculated by using the thermionic emission (TE) and Norde functions, and then, the obtained results were discussed in detail. Additionally, the capacitance-voltage (C-V) characteristic of the device was examined as a function of the frequency, and the device parameters such as diffusion potential (Vd), Fermi energy level (Ef), carrier concentration (Nd), b were detemined. Finally, the light intensity-dependent I-V measurements were taken to obtain information about the photoelectrical characteristics of the fabricated device. The obtained results have shown that the prepared composite material has a good potential to be used in optoelectronic applications such as photodiode, and photodetector.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • 24 January 2020 Sivrice-Elazığ Earthquake: Assessment of Seismic
           Characteristics of Earthquake, Earthquake Territory and Structural
           Performance of Reinforced Concrete Structures

    • Authors: İbrahim Özgür DEDEOĞLU; Musa YETKIN, Yusuf CALAYIR
      Abstract: An earthquake with a magnitude of 6.8 (Mw) has occurred in Sivrice district of Elazığ province in Eastern Turkey, on January 24, 2020. The main shock and long-term aftershocks felt fairly by near vicinities. Many structures have been damaged severely or demolished at this moderate earthquake that occurred on East Anatolia Fault (EAF) zone. Also resulted in sum 41 casualties, including 37 people in Elazığ and 4 people in Malatya. The purpose of this paper is to give information of the tectonic characteristics of the EAF zone, the seismic characteristics of the earthquake territory, the general characteristics of the main shock and after-shocks. In addition, another purpose of this article is to reveal the damages caused by the earthquake in the reinforced concrete (RC) buildings in Elazığ, with the post-earthquake field observations. The main reasons of damages have presented and discussed. The most important reason for damages of structures is the lack of engineering services, in other words, not being constructed properly with respect to the available building codes.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • Copper(II) Complexes of a New Hydrazones with Aliphatic Groups: Synthesis,
           Characterisation and Nuclease Activity

    • Authors: Cansu TOPKAYA
      Abstract: Two new copper(II) complexes of bidentate arylhydrazone ligands have prepared and studied. Elemental analysis, SEM-EDS, thermal gravimetric analysis (TGA), powder X-ray diffraction (XRD), and a number of spectroscopic techniques were used to determine the structures of the compounds (FTIR, UV-Vis, 1H and 13C-NMR). Using agarose gel electrophoresis, the DNA cleavage activities of the produced copper complexes were investigated in the absence and presence of hydrogen peroxide. It was also investigated the influence of compound dose on the DNA cleavage process. The results show that in the presence of an oxidant agent, all of the complexes break pBR322 DNA. At the concentration of 10 µM, [Cu(L1)2] converted the supercoil DNA into two forms, while [Cu(L1)2] formed only the nicked form. The mechanistic analyses show that the active oxidative species for DNA breakage is a species generated by hydrogen peroxide and the copper(II) metal. The compounds also cleaveged pBR322 DNA in the absence of H2O2, marginally.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • An Innovative Application On Supermarket Selection Through Using
           Intuitionistic Fuzzy TOPSIS Method

    • Authors: Feride TUĞRUL
      Abstract: Multi-criteria decision making methods have recently attracted the attention of researchers and have had a large share in multidisciplinary fields. In this study, using the intuitionistic fuzzy TOPSIS method, supermarket chains were evaluated in the consumer context and the most preferred supermarket was determined. Consumers' opinions were expressed using linguistic term. The reason why the intuitionistic fuzzy TOPSIS method is preferred; it is the ability of consumers to express their opinions easily, to take into account the undecided situations with the help of intuitionistic fuzzy sets, and thus to create an objective decision making mechanism.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • A Case Study on the Relationship between Water Quality Parameters: Bursa

    • Authors: Ergun GUMUS
      Abstract: Monitoring the quality of mains water in residential areas where industrialization is intense is of vital importance in terms of human health. For this purpose, quality parameters expressing the physical, chemical and biological properties of water are periodically observed through laboratory tests. During the evaluation of water quality, these parameters can be assessed individually or as a group by considering their interrelations. In this context, by using water quality reports of Bursa province which is an industrial city, answers to two questions were sought. The first of these questions is, getting evaluated on a group basis, which groups of water quality parameters are found to be highly correlated. The second question is whether the correlation between these interrelated parameter groups can be maintained in different measurement periods. For these purposes, analyzes were made using an approach which utilizes canonical correlation analysis, exhaustive scanning, and sliding window methods. As a result of these analyzes, it was observed that used approach gave successful results in terms of determining interrelated parameter groups and the differences in terms of interrelations between the measurement periods over these groups.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • An Experimental Study of a Pico Hydro Turbine

    • Authors: Ümit BEYAZGÜL; Ufuk DURMAZ, Orhan YALÇINKAYA, Mehmet Berkant ÖZEL, Ümit PEKPARLAK
      Abstract: Today, the storage and transporting of electricity from one place to another is still an unsolved problem. Besides, it is not economical to install power lines everywhere for low-voltage electronic circuits such as valves which are used to reduce leakage in water lines. When water demand is lower, it is a practical solution to use the pico hydro turbines to supply the required electrical energy for the electronic circuits of the valves used to reduce the losses in the water discharge lines. For this purpose, it is experimentally investigated electricity production in a pico hydro turbine and validated with experimental data that a pico hydro turbine (PHT) generates 1 W electricity under a water flow velocity of 0.53 m/s. It is concluded that the higher resistances were used in the test rig, the less turbine power produced. As the voltage increased, the current obtained decreased, and the turbine power reached its maximum at a resistance of 130 Ω.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • Conformational Analysis and DFT Investigations of
           1-(4-Fluorophenyl)Piperazine by ELF and LOL, Inhibitory activity against
           Alzheimer’s Disease, and ADME Prediction

    • Authors: Sibel ÇELİK
      Abstract: This study reports 1-(4-Fluorophenyl)Piperazine molecule structural and electronic properties calculated at the DFT/B3LYP level. A potential energy surface scan along the rotational bonds discovered the most stable minimum energy conformer of the title compound. Frontier molecular orbital (FMO) analyses, density of state (DOS), molecular electrostatic potential (MEP), and global and chemical reactivity descriptors were also used to investigate the reactivity of the pFPP molecule. In addition, ELF and LOL analysis were performed. In silico biological studies such as drug-likeness, ADME, and toxicity properties were also performed. Molecular docking studies are performed to predict the anti-Alzheimer agent enzyme (AChE) active site of the pFPP. The docking predicts the possibility of a potential drug to improve Alzheimer's disease (AD) treatment.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • Performance Analysis of MIMO Techniques for a Pyramid Receiver in an
           Indoor MIMO-VLC System

    • Authors: Aamir Ullah KHAN; Sultan ALDIRMAZ ÇOLAK, Yasin ÇELİK
      Abstract: In an indoor multiple-input multiple-output (MIMO) visible light communication (VLC) system, line of sight (LoS) channel links are present between a light-emitting diode (LED) based transmitter and a photodetector (PD) based receiver. The PDs in the receiver are closely packed resulting in a high channel correlation. To overcome channel correlation and improve the performance of the MIMO-VLC system, angle diversity receivers (ADRs) are commonly employed. The channel matrix entries depend on the normal vectors of the PDs, which in turn depend on the elevation angle (EA) of the PDs. Thus, by having normal vectors pointing in different directions, the channel correlation can be considerably reduced. This paper considers a special type of ADR called pyramid receiver (PR) and employs a 4x4 MIMO-VLC system. In this paper, different MIMO algorithms such as repetition coding (RC) and spatial multiplexing (SMP) are considered to exhibit and compare the bit-error-rate (BER) performance of the fixed and variable EA MIMO-VLC systems. The results show that an SMP-employed MIMO-VLC system outperforms the RC-employed MIMO-VLC system. SMP results in an spatial multiplexing gain that varies linearly with the number of LEDs whereas RC does not yield any spatial multiplexing gain. To attain the same spectral efficiency i.e. 4 bit/s/Hz, a larger signal constellation size is required for RC employed MIMO-VLC system to achieve the same BER as of an SMP employed MIMO-VLC system. Similarly, the BER performance of variable EA MIMO-VLC systems is better as compared to fixed EA MIMO-VLC systems.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
  • Effect of Glutaraldehyde Crosslinking Parameters on Mechanical and Wetting
           Properties of PVA/NaAlg Electrospun Mat

    • Authors: Ayben PAKOLPAKÇIL
      Abstract: Electrospun alginate-based materials are used in a wide range of applications, including wound dressings, tissue engineering, batteries, water treatment, bioremediation, and food packaging. However, they have low resistance to water. Crosslinking is usually used to enhance the mechanical properties of water-soluble polymers. Process parameters also play a key role in the crosslinking process. In this study, materials from sodium alginate (NaAlg) and poly (vinyl alcohol) (PVA) were prepared using the electrospinning method. To investigate the effect of the process parameters on the mechanical properties of the materials, different concentrations (1.25, 2.5 and 5 v %) and different application times (10 min, 60 min and 24 h) of the crosslinking agent were used. The wettability and mechanical properties of the electrospun mats were evaluated using a water contact angle device and a tensile strength tester, respectively. The maximum tensile strength was measured at 7 MPa which is the sample treated at 5% glutaraldehyde (GA) concentration and 60 min of application time. The sample treated with 2.5% GA concentration and 60 min of treatment time had the highest measured elongation of 11.5%. The sample treated with 2.5% GA concentration and for 10 min had the lowest water contact angle, which was measured at 27.5°. The intended usage of the materials should be considered, as the concentration of the crosslinking process and duration might affect the water-soluble polymers' mechanical and wetting properties.
      PubDate: Thu, 20 Oct 2022 00:00:00 +030
       
 
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