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Copyright of Current Research in Dental Sciences is the property of Ataturk University Coordinatorship of Scientific Journals and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, nanomaterials in bitumen modification have become widespread due to their superior properties. Graphene and its derivatives are prominent examples of this. Therefore, this review study was conducted to evaluate the effect of graphene on bitumen in detail. Accordingly, by examining the literature studies, general information about graphene and its derivatives was given, and the preparation conditions of graphene-modified bitumen were evaluated. Then, the effect of graphene on the physical and rheological properties of bitumen was investigated. In addition, the effect of graphene modification on the performance of asphalt mixtures and the use of graphene in composite modification was investigated. As a result, it was determined that graphene improves the high-temperature performance of bitumen, but its effect on the lowtemperature and fatigue performance of bitumen is mostly negligible. In addition, it has been determined that graphene increases the rutting resistance of bituminous mixtures and positively affects the cracking resistance of bituminous mixtures in general.

In this review, composite studies using titanium and graphene additions to alumina as matrix materials are summarized. In the light of studies conducted in recent years, the importance of graphene reinforcement and the effects of titanium reinforcement on the properties of ceramic matrix composites have been stated. Alumina matrix composites, which are the most widely used ceramic matrix composites, have been used in the industry from past to present due to their properties such as low density, high hardness and chemical stability. However, the low fracture toughness of alumina (3.5 MPa. m1/2) limits its usage area, therefore, the existing mechanical properties are improved with second phase additions, and higher hardness and fracture toughness are obtained with the reinforcements. Although it has been stated in the reviewed studies that titanium reinforcement into alumina matrix generally results in lower hardness, fracture toughness and bending strength compared to monolithic alumina and that titanium reinforcement is an important step in improving the properties of alumina with low fracture toughness, some studies have shown that titanium addition has increased fracture toughness (4,32 MPa.m1/2) and has been reported to increase bending strength. Studies have shown that a second reinforcement material is added to the Al2O3-Ti composite in order to improve the mechanical properties obtained by reinforcing titanium into alumina matrix. It has been observed that literature studies on the addition of graphene to the Al2O3-Ti structure are limited. In a limited study, results were obtained that graphene reinforcement reduced porosity and increased conductivity, wear resistance, hardness and fracture toughness (8.7 MPa.m1/2) compared to monolithic alumina and other reinforcements. These data show that the use of graphene supplements will continue to increase. In this review, the addition of titanium and graphene powders to the alumina matrix, production methods by powder metallurgy method, and the effects of the reinforcements on microstructure and mechanical properties were examined. [ABSTRACT FROM AUTHOR]

In this study, temozolomide (TMZ), a drug used in the treatment of anaplastic astrocytoma and glioblastoma multiforme, was incorporated in multiwalled carbon nanotubes (MWCNTs) and hybrid carbon nanotubes with graphene (MWCNTs-G) functionalized by polyethylene glycol (PEG). The aim was to evaluate the potential of these nanocarriers for targeted delivery and sustained release of TMZ in brain tumor cells. Oxidized MWCNTs and MWCNTs-G were noncovalently functionalized with PEGs of different molecular weights and subsequently loaded with TMZ following standard procedures. Thorough physicochemical and biopharmaceutical characterization of the TMZ-loaded carbon nanocarriers pointed to high encapsulation efficacy (up to 67%) and drug loading (up to 18% out of 25% theoretical value) and homogeneous particle size distribution, with zaverage (160 to 300 nm) and zeta potential (-31 to -21 mV) of the particles adequate for crossing the blood-brain-tumor-barrier (BBTB) and entering into the tumor cells. Successful functionalization and TMZ loading were confirmed by SEM and TEM images, UV-Vis absorption, infrared and Raman spectroscopy, and TGA analyses. Sustained release of TMZ from the carbon nanocarriers was observed in vitro. The presented findings form a fundamental platform for further investigation of these formulations against different types of glioma cells and in adequate animal models. [ABSTRACT FROM AUTHOR]

In recent years, the detection and determination of numerous drugs and pharmaceuticals in various media have become crucial aspects of modern healthcare and environmental management. Among the available sensing techniques, electrochemical methods, particularly those utilising screen-printed electrodes (SPEs) and different portable equipment have emerged as rapid, effective, sensitive, and inexpensive. This study focuses on the detection of the anti-inflammatory drug diclofenac in neutral media. Cyclic voltammetry measurements were conducted to identify diclofenac and determine the kinetics and electrochemical mechanism of its oxidation, along with assessing the surface characteristics of the employed SPEs. Graphene and modified graphene SPEs were explored as nanosensors for this purpose. The surface of the graphene SPE was modified using polyvinylidene fluoride, applied through a drop modification procedure. The morphology of the examined SPEs was observed by means of scanning electron microscope, while the electrolyte (0.1 g of diclofenac per litre of phosphate-buffered solution, pH = 7.4) was analysed using UV-Vis spectroscopy. The results indicate that the studied SPEs exhibit promising potential for the detection of diclofenac. [ABSTRACT FROM AUTHOR]

In recent years, nanomaterials in bitumen modification have become widespread due to their superior properties. Graphene and its derivatives are prominent examples of this. Therefore, this review study was conducted to evaluate the effect of graphene on bitumen in detail. Accordingly, by examining the literature studies, general information about graphene and its derivatives was given, and the preparation conditions of graphene-modified bitumen were evaluated. Then, the effect of graphene on the physical and rheological properties of bitumen was investigated. In addition, the effect of graphene modification on the performance of asphalt mixtures and the use of graphene in composite modification was investigated. As a result, it was determined that graphene improves the high-temperature performance of bitumen, but its effect on the lowtemperature and fatigue performance of bitumen is mostly negligible. In addition, it has been determined that graphene increases the rutting resistance of bituminous mixtures and positively affects the cracking resistance of bituminous mixtures in general. [ABSTRACT FROM AUTHOR]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Problems of Mechatronics. Armament, Aviation, Safety Engineering / Problemy Mechatroniki. Uzbrojenie, lotnictwo, Inżynieria Bezpieczeństwa is the property of Index Copernicus International and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Materials & Technologies / Materiali in Tehnologije is the property of Institute of Metals & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Materials & Technologies / Materiali in Tehnologije is the property of Institute of Metals & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Graphene is a two-dimensional honeycomb material with an atomic-thick planar structure. Graphene is one of the most studied nanomaterials that can be used in nanotechnology applications. There are various methods for synthesizing or isolating graphene monolayers, but by far the most popular uses a process called chemical vapor deposition. Chemical vapor deposition, or CVD, is a process that has the potential to produce relatively high-quality graphene at scale. The CVD process is relatively straightforward with some specialized equipment. However, controlling gas volume, pressure, temperature, and timing is critical to producing good quality graphene. In this project, the synthesis of graphene was carried out at different temperatures, pressures and coating times to produce stable, controlled and durable graphene by chemical vapor deposition. The characteristics of graphene sheets obtained by SEM, AFM and Raman spectroscopy analyzes were determined, as well as the optimal parameters for a stable, sustainable and controlled production of graphene. In parallel, the electrical properties of graphene films on different thicknesses have been studied. Therefore, obtaining a thin film with suitable thickness, transmission and electrical properties of graphene, which is currently marketed worldwide, was investigated.

Bu çalışmada; yüksek yoğunluklu polietilen (YYPE) içerisine %5 oranında çinko borat ve farklı oranlarda grafen tozları katılarak bir kompozit üretilmiştir. Kompoziti oluşturan malzemeler çift vidalı ekstrüzyon makinesinde karıştırılarak beş farklı grup elde edilmiştir ve enjeksiyon makinası kullanılarak standart test numuneleri üretilmiştir. Mekanik değerleri belirlemek için çekme, sertlik ve darbe testleri yapılmıştır. Ayrıca çinko borat ve grafenin dağılımlarını belirlemek için taramalı elektron mikroskobisi (SEM) ile fotoğrafları çekilmiştir. Analizler sonucunda YYPE içerisinde çinko borat ve grafen toz ilavesiyle; elastiklik modülü, çekme mukavemeti, kopma mukavemeti ve sertlik değerlerinin arttığı diğer taraftan darbe mukavemeti kopma uzaması ve kopma uzaması değerlerinin ise düştüğü tespit edilmiştir. SEM inceleme sonucu çinko borat ve grafen tozlarının homojen dağıldığı tespit edilmiştir.

The aim of this study was to i.) obtain Graphene (G)/epoxy, Graphene Oxide (GO)/epoxy, G/carbon fiber reinforced plastic (CFRP), GO/CFRP nanocomposites by G and GO addition to epoxy and CF matrices and ii.) investigate the effect of G and GO addition on tensile strength of the nanocomposites produced. The graphene was not homogeneously distributed in polymer matrices; therefore, the G was converted into the GO using hummers method. The characterization GO was carried out by SEM, EDX, FTIR and X-RD analysis, which confirmed the successful production of the GO. The G/epoxy, GO/epoxy, G/CFRP and GO/CFRP nanocomposites were obtained by adding G and GO to epoxy and CF at a rate of 0.1, 0.2, and 0.3%. The effect of G and GO on tensile strength of the nanocomposites was determined using a tensile test. The addition of G and GO at 0.2% rate yielded the best results. The effect of GO on tensile strength was better compared to that of the G.

Membrane technologies for desalination and boron removal have attracted interest in recent years. Today, membranebased separation processes are preferred due to their environmental friendliness and efficiency in energy/cost consumption. One of these new technologies is membrane distillation. As a result of researches that are still at academic level, it is possible to purify and remove over 99.99% with advanced technology such as membrane distillation. In this study, pure and graphene-doped polylactic acid (PLA) membranes, which are biodegradable polymers, were produced and boron was removed from water by membrane distillation technique. The effects of temperature, boron concentration, graphene ratio on boron rejection and water flux values were determined. As a result, boron rejections above 99% were obtained at all temperatures and with all graphene-doped PLA membranes. The flux values were obtained as 13 kg/m² .h, especially with the graphene additive. [ABSTRACT FROM AUTHOR]

Copyright of Duzce University Journal of Science & Technology is the property of Duzce University Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Gazi Üniversitesi Fen Bilimleri Dergisi Part C: Tasarım ve Teknoloji is the property of Gazi University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of International Journal of Engineering Research & Development (IJERAD) is the property of International Journal of Engineering Research & Development and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study was to i.) obtain Graphene (G)/epoxy, Graphene Oxide (GO)/epoxy, G/carbon fiber reinforced plastic (CFRP), GO/CFRP nanocomposites by G and GO addition to epoxy and CF matrices and ii.) investigate the effect of G and GO addition ontensile strength of the nanocomposites produced. The graphene was not homogeneously distributed in polymer matrices; therefore, the G was converted into the GO using hummers method. The characterization GO was carried out by SEM, EDX, FTIR and X-RD analysis, which confirmed the successful production of the GO. The G/epoxy, GO/epoxy, G/CFRP and GO/CFRP nanocomposites were obtained by addingG and GO to epoxy and CF at a rate of 0.1, 0.2, and 0.3%. The effect of G and GO on tensile strength of the nanocomposites was determined using a tensile test. The addition of G and GO at 0.2%rateyielded the best results. The effect of GO on tensile strength was better compared to that of the G. [ABSTRACT FROM AUTHOR]

Copyright of Materials & Technologies / Materiali in Tehnologije is the property of Institute of Metals & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Graphene, as one of single-atom-thick carbon nanomaterial, has recently interested among researchers due to its superior optical and electrical properties. Dyes are frequently used optical materials in medical and technological applications. Optical and morphological characterization of nanocomposites that is obtained by using these materials and dyes have great importance for potential applications such as optical sensors, optoelectronic devices, etc. Xanthene derivatives are one of the best dyes used in obtaining nanocomposits since they have several characteristic features including large absorption and fluorescence, light resistance, low toxicity in-vivo, and relatively high solubility in water. In this work, reduced graphene oxide (rGO)was synthesized with modified Hummers' method. Novel composites with rGO and xanthene derivative dyes (Rhodamine 101, Florescein and Eosin Y) were synthesized in an aqueous medium. Morphological and optical properties of these composites was confirmed with X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy and steady-state fluorescence spectroscopy. The effect of rGO and dye concentrations on optical and morphological properties of synthesized composites was investigated. Various changes (such as bathochromic and hypsochromic shift, hypochromic effect) were observed in the absorption spectra of the composites depending on the amount of rGO. Also, when amounts of rGO in composites was increased, the fluorescence intensities of dyes were influentially quenched. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRAK- Penelitian ini merupakan bentuk kajian sederhana yang memanfaatkan biomassa pertanian yaitu batok kelapa yang disintesis menjadi material maju grafen. Grafen merupakan salah satu material maju dan terbarukan dalam bidang sains dan teknologi terkini karena kemanfaatannya yang multifungsi. Penelitian ini diawali dengan mengubah biomassa batok kelapa menjadi karbon melalui suatu reaksi pembakaran. Arang hasil dari pembakaran selanjutnya diberikan perlakuan dengan metode reduksi kimia atau metode Hummer tereduksi. Hasil penelitian ini memperlihatkan bentuk morfologi grafen berupa serpihan-serpihan atau dikenal dengan istilah grafen Flakes. Hasil ini terkonfirmasi melalui uji visualisasi SEM, dimana grafen Flakes diperlihatkan dalam formasi tumpukan mengindikasikan struktur multilayer. Hasil uji TEM memperlihatkan jarak antar kisi kristal yang dimilikinya yaitu berkisar pada 2,40 dan 2,46 Å. Berdasarkan pada data jarak antar kisi kristal tersebut, hasil simulasi energi menggunakan prinsip DOS didapatkan bahwan grafen hasil sintesis memiliki energi secara berturut-turut adalah 4,0 eV untuk level konduksi dan 3,3 eV untuk level valensi. Hasil uji optik sifat absorbansi dan fluoresens memperlihatkan grafen memiliki dua puncak serapan utama yang berkorelasi dengan terjadinya transisi energi dan dari bentuk ikatan C=C dan C-O-C. Adapun pendaran yang dihasilkan melalui uji fluoresensi adalah warna hijau dengan panjang gelombang 525 nm. Secara sederhana rancangan penelitian dapat dikatakan telah berhasil dalam mensintesis grafen dari arang batok kelapa, meskipun belum sempurna dan masih perlu untuk dilakukan kajian kembali. Hasil dari penelitian ini selanjutnya akan dikembangkan lagi menjadi bentuk grafen dengan morfologi yang berpori. ABSTRACT− This research is a simple study that takes an advantage of agricultural biomass that is synthesized cocconut shell to become graphene, an advanced material. Graphene is one of advanced-and-renewable material in the recent science and technology due to its multifunctional values.The research started with a changed cocconut shell being carbon through a burning reaction. Then the next procedure is given to the charcoal, produced from the burning process, by chemical reduction method or reduced hummer method.The observation showed a morphological form of graphen known as graphen flakes. It had been confirmed by SEM visualization test where the graphene flakes exhibited in a drift formafion indicated a multilayer structure. TEM test result showed a space in the owned crystal lattice approximately from 2.4 to 2.46 Å. Based on the data of the crystal lattice space, the result of energy simulation using DOS principal impressed that synthesized graphen has energy respectively 4.0 eV for a conduction and 3.3 eV for valency level. Therefore, the absorbantion and fluorecence result of the optical test showed that the graphen has two main absorptions corellated with the transitional energy of and to the form of C=C and C-O-C. However, emission resulted from fluorecence test is green with wavelength 525 nm. In a simple way, this reseach project can be resumed as a success study in the synthesized coconut from cocconut shell, while it had not been perfect, yet, and it needed to be advanced. Next, the outcome of the study will be developed more to be a porous graphen form

Polimer elektrolit membranlı (PEM) yakıt pillerinde elektrot yapısında kullanılan elektrokatalizörün verimliliğinin artırılması, maliyetinin düşürülmesi ve ticarileşmesi açısından oldukça önemlidir. Sonyıllarda, ticari olarak kullanılan karbon siyahı destekli platin (Pt/C) elektrokatalizörün aktivite ve performans gibi dezavantajlarından dolayı yeni nesil elektrokatalizörlerin kullanımı oldukça dikkatçekmektedir. Bu sebeple, bu çalışmada indirgenmiş grafen oksit (rGO) ve karbon nanofiber (KNF) esaslı hibrit karbon yapısı katalizör destek malzemesi olarak kullanılmıştır ve bu destekler üzerine Pt nanoparçacıkları sentezlenmiştir. KNF ve rGO/KNF destekli Pt elektrokatalizörlerin (Pt/KNF ve Pt/rGOKNF) sentezi için basit, çevre dostu ve düşük maliyetli bir teknik olan mikrodalga destekli (MW) sentez tekniği kullanılmıştır. Mikrodalga tekniği ile sentez sayesinde tek basamakta, hızlı ve verimli bir sentez geliştirilmiştir. Sentezlenen elektrokatalizörün fiziksel karakterizasyonu için X-ışını difraktometresi (XRD), RAMAN spektroskopisi ve geçirimli elektron mikroskopisi (TEM) teknikleri kullanılmıştır. Elektrokimyasal aktivite analizi için döngüsel voltametri (CV) ve doğrusal taramalı voltametri (LSV) tekniği kullanılmıştır. Bunun dışında, yakıt pili içinde performans testleri gerçekleştirilmiştir. Pt/rGOKNF Pt/KNF ile kıyaslandığında daha yüksek katalitik aktivite ve yakıt pili performansı (maksimum güç yoğunluğu: 447 mW.cm-2) göstermiştir. Elde edilen sonuçlar, Pt/rGO-KNF hibrit katalizörlerin oldukça umut vaat eden PEM yakıt pili elektrot malzemeleri olduğunu göstermektedir.

Copyright of Erzincan University Journal of Science & Technology is the property of Erzincan Binali Yildirim Universitesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of the study is to histologically evaluate the effect of mixtures formed by adding different ratios of graphene nanoplatelet (GNP) to Mineral Trioxide Aggregate (MTA) on rat dental pulps. 0.1% and 0.3% by weight GNP (Nanography, Ankara, Turkey) which were weighed on precision scales were added to pure Angelus MTA (Angelus, Londrina, PR, Brazil) and mixed in agate mortar until a homogeneous mixture was obtained. 16 female Wistar Albino rats were divided into 4 groups. Angelus MTA+0.1% GNP, Angelus MTA+0.3% GNP, calcium hydroxide (Dycal, Dentsply, Germany), and pure Angelus MTA were used as direct capping material on pulp perforation areas of the classV cavities of the lower two incisors of the rats (n=8). The teeth were histologically examined for dentin bridge formation and pulpal tissue responses at 1st and 4th weeks. The data of the study were analyzed with IBM SPSS Statistics V22 for Windows (SPSS Inc., Chicago, IL, USA). A regenerative dentin bridge was seen from the 1st week. In the 4th week, the inflammatory reaction was mildest in the Angelus MTA+0.3% GNP group. At 4th week, the mildest hyperemia was seen in Angelus MTA+0.1%GNP and Angelus MTA+0.3%GNP groups. No significant difference was found between the groups in terms of inflammatory reaction and presence of hyperemia at 1st and 4th weeks (p>0.05). The inclusion of GNP in Angelus MTA may increase the success of the treatment by alleviating the pulpal tissue response in direct pulp capping. [ABSTRACT FROM AUTHOR]

Bazı metallere canlı organizmaların düzenli fonksiyonlarında çok az miktarda da olsa ihtiyaç duyulmakta bu nedenle bu metallerin varlığı önem kazanmaktadır (bakır, çinko, demir, vb. gibi). Fakat bazıları zehirli olup bu zehirli metaller insanların yaşadığı çevre ve yiyecekler için tehlikeli eser metaller olarak kabul edilmektedir. Bu metaller (kurşun, cıva, kadmiyum, arsenik, çinko, demir, bakır, mangan, krom) yüksek derişimlerde zehirli bileşenlerine dönüşmesi nedeniyle zararlı olabilmektedir. Bu nedenle modern analitik kimyada, eser metallerin tayini için basit, çevre için güvenli, duyarlı ve seçici yöntemlerin geliştirilmesine doğru bir eğilim vardır. Eser metallerin düşük derişimleri nedeniyle genellikle bir ayırma ve zenginleştirme tekniği gerekmektedir. Bu tekniklerden en yaygın olarak kullanılanlardan birisi de katı faz özütleme (SPE) tekniğidir. Katı faz özütleme alanındaki yeni çalışmalar, asit ve bazlara dayanıklılık, analite seçicilik, geniş yüzey alanı ve yüksek adsorpsiyon kapasitesi gibi iyi performanslı yeni katı fazların sentezlenmesiyle ilgilidir. Grafen (G) ve grafen oksit (GO)’in maksimum adsorpsiyon kapasiteleri şimdiye kadar rapor edilenlere göre çok daha yüksek olması nedeni ile G ve GO nanotabakaları hem organik bileşikler hem de metal türler için klasik SPE’de başarılı bir şekilde uygulanabilmektedir.

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, the exergy analysis of graphene-based nanofluids in a compact heat exchanger is examined. In experiments using distilled water as the base fluid, graphene nano-ribbon and graphene oxide nanofluids were used at 0.01% and 0.02% of the volume concentrations. The experiments were carried out at 36, 40, and 44 oC fluid inlet temperatures and 0.6, 0.7, 0.8, and 0.9 m3/h mass flow rates. As a result of the calculations made for all temperature and flow rates, it was found that the exergy efficiency values of 0.01% by volume GO nanofluid were higher than the exergy efficiency of the other nanofluids used. Also, the exergy destruction values calculated for %0.01 GO were lower than the value of exergy destruction calculated for other nanofluids. It was concluded that the exergy efficiencies of nanofluids increased with the increase of the fluid flow rates and the inlet temperature of the heat exchanger. When the exergy efficiencies were compared according to the nanofluid concentrations, it was found that the exergy efficiencies decreased with the increase of the fluid concentration. It was examined that the exergy destruction values also increases with the increase of nanofluid flow rates, as well as exergy efficiency. When the exergy destructions were compared to the nanofluid concentrations, it was concluded that the exergy destructions increased with the increase of the nanofluid concentration. It was determined that the amount of increase in exergy destruction of GO nanofluid was higher than that of GNR. [ABSTRACT FROM AUTHOR]

Graphene (GrF) doped elastomer based pressure sensors (PgS) were obtained in two stages. These materials were analyzed in the SEM device and the interaction between the distribution of filler materials and the resistance was examined. By applying cyclic loads for different displacement values to PgS, changes in resistance values due to the internal structure of the samples were observed. The surface area, mechanical properties and distribution shape of the conductive filler material in the matrix determine the conductivity of PgS. The decrease in resistance and increase in conductivity due to the pressure-resistance relationship is higher at 3 mm compression. The resistance change of GrF doped PgS varies as a function of the load. Although some resistance increases with the increase in force, the resistance tends to decrease as a result of the transfer of the load to the filler material. Cyclic loading-unloading tests were performed on PgS at 1mm, 2mm and 3mm displacements, and compression forces of 85 N, 273 N and 601 N were obtained, respectively. The highest resistance value was determined as 5.29Ex06 ohm after 3 mm compression. In our study, by making use of this unique feature of PgS, in the tests we made with the application of air suspension bellows on the damping bumper, which is the secondary suspension element, estimates were made about the working conditions of the bellows. [ABSTRACT FROM AUTHOR]

In this article, thermal stability, viscosity, density and surface tension of graphene nano-platelet dispersed in sunflower oil are experimentally determined by varying the graphene concentration (0.1-1.1 wt.%) and temperature (40-100 °C). The SEM micrograph and the EDS spectra are used to characterize the graphene. Nanofluids are prepared by ultrasonication technique (two-step method) and the maximum thermal stability of about 280 °C is achieved at 1.1 wt.% graphene nanofluids. The dynamic viscosity diminishes in an exponential shape in acquiescence with the Arrhenius equation and the densities of samples are characteristic with linear decrement in the estimated temperature range. Density and surface tension increase with the graphene concentration, while a reverse trend is observed with temperature raise. The maximum thermal stability, viscosity, density and surface tension is obtained in the nanofluid with 1.1 wt.% concentration and the minimum is obtained in the nanofluid with 0.1 wt.% concentration. [ABSTRACT FROM AUTHOR]

Copyright of Karaelmas Science & Engineering Journal / Karaelmas Fen ve Mühendislik Dergisi is the property of Karaelmas Science & Engineering Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polimer elektrolit membranlı (PEM) yakıt pillerinde elektrot yapısında kullanılan elektrokatalizörün verimliliğinin artırılması, maliyetinin düşürülmesi ve ticarileşmesi açısından oldukça önemlidir. Son yıllarda, ticari olarak kullanılan karbon siyahı destekli platin (Pt/C) elektrokatalizörün aktivite ve performans gibi dezavantajlarından dolayı yeni nesil elektrokatalizörlerin kullanımı oldukça dikkat çekmektedir. Bu sebeple, bu çalışmada indirgenmiş grafen oksit (rGO) ve karbon nanofiber (KNF) esaslı hibrit karbon yapısı katalizör destek malzemesi olarak kullanılmıştır ve bu destekler üzerine Pt nanoparçacıkları sentezlenmiştir. KNF ve rGO/KNF destekli Pt elektrokatalizörlerin (Pt/KNF ve Pt/rGO-KNF) sentezi için basit, çevre dostu ve düşük maliyetli bir teknik olan mikrodalga destekli (MW) sentez tekniği kullanılmıştır. Mikrodalga tekniği ile sentez sayesinde tek basamakta, hızlı ve verimli bir sentez geliştirilmiştir. Sentezlenen elektrokatalizörün fiziksel karakterizasyonu için X-ışını difraktometresi (XRD), RAMAN spektroskopisi ve geçirimli elektron mikroskopisi (TEM) teknikleri kullanılmıştır. Elektrokimyasal aktivite analizi için döngüsel voltametri (CV) ve doğrusal taramalı voltametri (LSV) tekniği kullanılmıştır. Bunun dışında, yakıt pili içinde performans testleri gerçekleştirilmiştir. Pt/rGO-KNF Pt/KNF ile kıyaslandığında daha yüksek katalitik aktivite ve yakıt pili performansı (maksimum güç yoğunluğu: 447 mW.cm-2) göstermiştir. Elde edilen sonuçlar, Pt/rGO-KNF hibrit katalizörlerin oldukça umut vaat eden PEM yakıt pili elektrot malzemeleri olduğunu göstermektedir.

In this study, the change of some dielectric properties such as dielectric constant, dielectric loss and loss tangent of films prepared by casting method by adding graphene (G) in different proportions (% wt 0.5, 1, 2) to potato starch (PS) films plasticized with glycerol were investigated. Dielectric constant (έ), dielectric loss (ε՛՛) and loss tangent (tanδ) values of pure PS and its composites prepared with G (PSG0.5, PSG1 and PSG2) were determined by impedance analyzer as a function of frequency (between 100 Hz and 10 kHz) at room temperature. The dielectric constant, dielectric loss factor and loss tangent values of the starch were found to be 9.20, 4.45 ve 0.48 at 1 kHz constant frequency and at room temperature. In addition, the effect of different proportions of G (0.5%, 1% and 2% by weight) on the dielectric properties of films were investigated. (0.5%, 1% and 2% by weight) of the starch on the dielectric properties was investigated. It was observed that as the G concentration increased, the dielectric constant, dielectric loss and loss tangent values significantly increased compared to the pure starch. [ABSTRACT FROM AUTHOR]

Teknolojinin hızla gelişmesi ile birlikte, imalat, havacılık ve otomotiv sektörlerinde yaygın olarak kullanılan standart malzemeler yerini yeni nesil yüksek mukavemete ve hafifliğe sahip malzemelere bırakmaktadır. Özellikle, Tungsten karbür (WC) ve Grafenin sahip olduğu yüksek termal ve elektriksel özellikler, yüksek elastisite modülü, yüksek mukavemet gibi üstün özellikleri sayesinde alüminyum matrisli kompozit malzeme üretiminde büyük etki ve avantajlara sahiptir. Bu çalışmada, WC ve Grafen takviyelerinin alüminyum matrisli kompozit malzemelerin mekanik özelliklerine etkisi ile ilgili çalışmalar incelenerek sunulmuştur. Alüminyum matrisli kompozitlerin mekanik özelliklerinin iyileştirilmesinde %20'ye kadar WC ve %0.7'ye kadar grafen katkısının etkili olduğu raporlanmıştır. Grafen ilavesinin %0.5’ten fazla arttırılması topaklanmalara, WC ilavesinin %30’dan fazla arttırılması ise gözenekliğin artmasına ve mekanik özelliklerin azalmasına neden olmaktadır.

Titanium has the most useful properties of the metal are corrosion resistance strength-to-density ratio, the highest of any metallic element. In its unalloyed condition, titanium is as strong as some steels but less dense. Due to its good features titanium can be used in the composite as a matrix material. Titanium matrix composites (TiMCs) can be used in various industries such as automotive, airplanes and especially biomaterials. Today, as carbon reinforcing material carbon nanotube (CNT), graphite and graphene are used as reinforcing materials. The graphene has the most remarkable properties in this reinforced material due to its extraordinary mechanical features, low friction and high abrasion resistance. Composite materials produced by using titanium and graphene may have remarkable mechanical and microstructural properties. This is conspicuous subject in recent years. In the present study, graphene (Gr) reinforced titanium composites were produced by powder metallurgy method. The effect of various percentages of graphene (0-0,15-0,30-0,45-0,60 wt.%) on the microstructure, density, hardness and compressive strength of Ti composites have been investigated. From the mechanical tests after sintering at 1100oC for 120min. The highest hardness and the greatest compressive strength were obtained for 0,30 wt.% Gr reinforced composites (520.2 HV and 1137 MPa) when compared to pure titanium (419.8 HV and 780 MPa). The crystal phase and microstructure of the composites were detected by scanning electron microscopy (SEM) and X-ray diffractometer (XRD). Better mechanical properties were observed for Ti-Gr composite materials when compared pure Ti. These kinds of composites promise the future for using especially the field of biomaterials.

The objective of the study is to determine the thermophysical property variations (such as viscosity, density, specific heat capacity and thermal conductivity) of graphene suspended base fluid (ethylene glycol (EG)/water (W)), with respect to graphene nanoparticle concentration and hot fluid inlet temperature. Graphene nanoparticle concentrations (0.2, 0.4, 0.6, 0.8 and 1 vol.%) and the base fluid of 30:70 vol.% of EG: Water is prepared initially. The impact of graphene nanoparticle addition on base fluids based on experimentation in the commercial plate heat exchanger was studied. In this experiment, the hot fluid inlet temperature was varied at 55, 65 and 75 °C. The experimental results of thermophysical properties were compared with the selected models proposed in the literature. Einstein (1956), Kitano (1981) and Bachelor models (1977) have been used to consider the effect of viscosity. The measured density and specific heat capacity were validated with Pak and Cho and Xuan models, respectively. To consider the effect of thermal conductivity, three different models (Maxwell (1954), Vajjah (2010) and Sahoo (2012)) have been used. Study revealed that the thermophysical properties of base fluid significantly affect the graphene nanoparticle suspension. [ABSTRACT FROM AUTHOR]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Industria Textila is the property of Institutul National de Cercetare-Dezvoltare pentru Textile si Pielarie and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Interest in graphene, which is a new material, is increasing day by day due to its unique mechanical, electrical, and thermal properties. Graphite oxide (GRO), which is synthesized as a result of a series of chemical processes of graphite, was used as the primary material in the production of graphene film. In this study, firstly, graphene oxide (GO) dispersions with different exfoliation degrees were prepared from de-ionized water (DI-water) and repeatedly washed GRO mixture at different ultrasound times. Then, GO films with the same film thickness were produced by casting of the prepared GO dispersions. GO films with different exfoliation degrees were thermally reduced to graphene at 1100 oC, and the change in reduced graphene film (RGO) properties was investigated. XRD, SEM, and FTIR measurements were made for the characterization of thermally reduced graphene and GO films. While the maximum degree of exfoliation was obtained for GO films in 8 hours of ultrasound, the maximum degree of exfoliation was obtained even in 3 hours of ultrasound duruationby thermal reduction of GO films at 1100 oC. [ABSTRACT FROM AUTHOR]

The chitosan / cellulose biopolymer matrix was filled with graphene and a cross-linked ternary absorbent composite system was produced in an easy and practical way. Chitosan is the second most abundant biopolymer material after cellulose, with many functional groups and wide usage areas, showing good film properties. Chitosan with having many functional groups and wide usage areas, showing good film properties is the second most abundant biopolymer material after cellulose. The chitosan/cellulose blend was prepared in order to change the brittle structure of chitosan and to obtain the more flexible material network. Biopolymer blend was filled with graphene to increase the mechanical strength of produced composite material and to produce a conductive and widely used material. In this context, the effect of pH and the amount of crosslinker on the liquid absorption properties of composites prepared with three different amount of crosslinker was investigated by swelling tests. Glutaraldehyde was used as the crosslinker. It was observed that swelling and absorbed liquid ratio decreased with increasing amount of crosslinker and pH. The mechanical properties of the prepared composites were investigated by tensile tests and it was determined the increasing amount of crosslinker increases the tensile strength of the composite and this increase is not proportional to the amount of crosslinker. The structural and molecular properties of the prepared composite were determined by FT-IR and FESEM analysis. As a result of these analyzes, it has been shown the three components were well dispersed in this composite system. Besides them, it was figure out a strong interaction between these components due to the intramolecular and intermolecular bonds and synergistic effect. [ABSTRACT FROM AUTHOR]

Some metals are needed in the regular functions of living organisms, albeit in very small amounts, so the presence of these metals becomes important (such as copper, zinc, iron, etc.). However, some of them are toxic and these toxic metals are accepted as dangerous trace metals for the environment and food in which people live. These metals (lead, mercury, cadmium, arsenic, zinc, iron, copper, manganese, chromium) can be harmful due to their conversion to toxic components at high concentrations. Therefore, in modern analytical chemistry there is a tendency to develop simple, environmentally safe, sensitive and selective methods for the determination of trace metals. Due to the low concentration of trace metals, a separation and preconcentration technique is often required. One of the most commonly used techniques is the solid phase extraction (SPE) technique. Recent tendency in the field of solid phase extraction is related to synthesis of the new sorbent materials with good performance, such as high resistance to acids and bases, selective for analytes, large surface area and high adsorption capacity. Because of the maximum adsorption capacities of graphene (G) and graphene oxide (GO) are much higher than those of the recently reported sorbents, G and GO nanosheets can be used in classical SPE of both organic compounds and metal species, with successfully. [ABSTRACT FROM AUTHOR]

Copyright of SDU Journal of Engineering Sciences & Design / Mühendislik Bilimleri ve Tasarım Dergisi is the property of Journal of Engineering Sciences & Design and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Dicle University Journal of Engineering / Dicle Üniversitesi Mühendislik Dergisi is the property of Dicle Universitesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Materials & Technologies / Materiali in Tehnologije is the property of Institute of Metals & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)