Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği
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Article Citation - WoS: 50Citation - Scopus: 58Chemically Modified Optical Fibers in Advanced Technology: an Overview(Elsevier, 2019) Shukla, S. K.; Kushwaha, Chandra Shekhar; Güner, Tuğrul; Demir, Mustafa MuammerIn recent years, chemically modified optical fibers have widely used for development of several advanced chemical and biosensors, biomedical technology and environmental monitoring. The chemically modified optical fiber bears several valuable properties like energy loss, catalytic behaviour, refractive index, and mechanical strength to advance the optical fiber technology. In this article, we reviewed the chemically-modified optical fiber and their applications in different optical fiber-based technologies. The basics of optical fiber and their modification are discussed along with the adopted methodologies. The advancements in different optical fiber based technologies viz sensing, imaging, tomography, magnetic resonance imaging, photodynamic therapy, optogenics, surgery and environmental monitoring are discussed in the light of the contribution of chemically modified optical fibers. In conclusion, success and challenges for the use of chemically modified-optical fiber are presented on the basis of existing literature.Article Citation - WoS: 25Citation - Scopus: 28Colorimetric and Plasmonic Pressure Sensors Based on Polyacrylamide/Au Nanoparticles(Elsevier, 2019) Topçu, Gökhan; Güner, Tuğrul; İnci, Ezgi; Demir, Mustafa MuammerColorimetric stimuli-responsive nanomaterials have emerged as an eminent tool for sensor applications. Among this class of sensing elements, gold nanoparticle-based (Au NP) nanostructures are promising materials due to their plasmonic features. In this study, free-standing flexible polymeric films having intense optical response upon application of mechanical pressure were fabricated based on polyacrylamide (PAAm) and Au NPs. Pressure may cause plasmonic shift most probably due to the disassembly of the clusters from blue to reddish individual particles depending on the extent of pressure. Temperature, time, and extent of pressure were examined in terms of spectral change of Au particles. The sensor films depict working range up to 160 MPa, which shows minor change at elevated temperatures probably due to the stress induced crystallization of PAAm. For practical applications, a simple red-green-blue (RGB) space-based algorithm was presented for smartphone-assisted detection of applied pressure. Moreover, the PAAm/Au composite structure shows self-healing without any additive under ambient conditions even after divided into pieces. (C) 2019 Elsevier B.V. All rights reserved.Article Citation - WoS: 169Citation - Scopus: 177Thin Film Microextraction: Towards Faster and More Sensitive Microextraction(Elsevier Ltd., 2019) Ölçer, Yekta Arya; Tascon, Marcos; Eroğlu, Ahmet Emin; Boyacı, EzelThin film microextraction (TFME) is an analytical tool that has been proven to be suitable for integrated sampling and sample preparation of a wide variety of routine and on-site applications. Compared to the traditional microextraction techniques, the most important advantage of TFME is its enhanced sensitivity due to the relatively larger extractive phase spread over a larger surface area. The technique, in this way, facilitates fast extraction kinetics and high extractive capacity. Moreover, TFME offers high versatility for device development over classical SPME technologies due to the plethora of available extractive phases, coating methods and geometry options. The goal of this review is to provide a comprehensive summary of the contemporary advances in this exciting field covering novel extractive phases, technological and methodological developments, and relevant cutting-edge applications. Finally, a critical discussion of the future trends on TFME is also presented. (C) 2019 Elsevier B.V. All rights reserved.Correction Citation - Scopus: 1Corrigendum To “hierarchically Porous Polymer Derived Ceramics: a Promising Platform for Multidrug Delivery Systems”[mater. Des. 140(supplement C) (2018) 37–44](Elsevier Ltd., 2018) Ahmetoğlu, Çekdar Vakıf; Zeydanlı, Damla; Özalp, Veli Cengiz; Borsa, Barı Ata; Soraru, Gian DomenicoThe authors regret to inform that The TMTVS ratios for samples were written incorrectly. The true weight ratios for PHMS/LDH/PDMS/TMTVS blends should be as follows: Bio1 = 1/0.055/0.25/0.055, and Bio2 = 1/0.055/1/0.055. The discussion in the study is not affected by this mistype and actually the previous paper [1] cited also in the paper as ref.#44 gives right values for the sample preparation. The authors would like to apologize for the inconvenience caused.Article Citation - WoS: 4Citation - Scopus: 4Triboluminescent Composite Microspheres Consisting of Alginate and Eud(4)tea Crystals(Elsevier, 2018) İncel, Anıl; Demir, Mustafa MuammerAlginate is utilized to obtain luminescent composite microspheres containing europium tetrakis (dibenzoylmethide) triethylammonium (EuD4TEA) triboluminescent (TL) crystals. Na alginate is initially treated with Ca(II) and then Eu (III) so that physically-crosslinked alginate microspheres were obtained. EuD4TEA crystals are precipitated in situ on the surface of the spheres upon treatment with dibenzoylmethane (DBM) and triethylamine (TEA). The EuD4TEA/alginate composite spheres are swollen in aqueous system, the diameter of the microspheres increases from 180 up to 405 pm in 48 h. TL intensity of the spheres swollen in 1 h decreases 4 folds compared to dry spheres; however, it systematically increases as the swelling time is extended step-wise to 48 h. Swelling may develop structural homogenity in the microsphere that supresses the optical scattering and may lead to better transmittance of the TL signal. (C) 2017 Elsevier B.V. All rights reserved.Article Citation - WoS: 16Citation - Scopus: 18Bacterial Detection Using Bacteriophages and Gold Nanorods by Following Time-Dependent Changes in Raman Spectral Signals(Informa Healthcare, 2018) Moghtader, Farzaneh; Tomak, Aysel; Zareie, Hadi M.; Pişkin, ErhanThis study attemps to develop bacterial detection strategies using bacteriophages and gold nanorods (GNRs) by Raman spectral analysis. Escherichia coli was selected as the target and its specific phage was used as the bioprobe. Target bacteria and phages were propagated/purified by traditional techniques. GNRs were synthesized by using hexadecyltrimethyl ammonium bromide (CTAB) as stabilizer. A two-step detection strategy was applied: Firstly, the target bacteria were interacted with GNRs in suspensions, and then they were dropped onto silica substrates for detection. It was possible to obtain clear surface-enchanced Raman spectroscopy (SERS) peaks of the target bacteria, even without using phages. In the second step, the phage nanoemulsions were droped onto the bacterial-GNRs complexes on those surfaces and time-dependent changes in the Raman spectra were monitored at different time intervals upto 40 min. These results demonstrated that how one can apply phages with plasmonic nanoparticles for detection of pathogenic bacteria very effectively in a quite simple test.Article Citation - WoS: 39Citation - Scopus: 43Tailored Electrospun Fibers From Waste Polystyrene for High Oil Adsorption(Elsevier Ltd., 2018) Isık, Tuğba; Demir, Mustafa MuammerRecent ship accidents that resulted catastrophic oil spills necessitate producing environmentally friendly, costeffective, and large-scale fabrication technology for oil-sorbent materials. Various material systems have been employed to fabricate sorbent materials; however, using fresh material components as adsorbent can lead to a secondary pollution. Therefore, recycling of plastics wastes for the fabrication of adsorbent material could be a wise approach to handle this environmental issue. In this study, foam-expanded polystyrene (f-PS), a commodity polymer used for insulation and packing materials, was electrospun from solution mixture of THF and DMF. Surface and interior porosity were achieved from individual fibers electrospun froma composition of DMF: THF (1:3) at 20-wt% of solid f-PS content. The resulting adsorbents exhibited a considerable hydrophobicity (WCA approximate to 120 degrees) and oleophilicity (CA approximate to 10 degrees), which can selectively adsorb both vegetable and engine oils from polluted waters. The porosity of the fibers has significant effect on the sorption capacity and separation efficiency up to 124 g/g and 99%, respectively. Thus, electrospun mats of the polystyrene wastes offer a promising adsorbent for the remediation of oily wastewaters. (C) 2018 Published by Elsevier B.V.Article Citation - WoS: 30Citation - Scopus: 32Perylene-Embedded Electrospun Ps Fibers for White Light Generation(Elsevier Ltd., 2019) Güner, Tuğrul; Aksoy, Erkan; Demir, Mustafa Muammer; Varlıklı, CananPerylene dyes have been employed in the fabrication of white light due to their superior photophysical properties and relatively easy synthetic methods. However, their molecular aggregation in solid state is one of the main handicaps since it causes deviation in their optical properties and quenches photoluminescence quantum yields (Phi(f)). Investigation of the photophysical properties of a green (PTE), a yellow (PDI) and a new red (DiPhAPDI) emitting perylene derivative in solution, drop-casted films, polystyrene (PS) fibers and PS fibers embedded in poly (dimethyl siloxane) (PDMS) showed that PS:dye fibers prevent aggregation to some extend and allows high Of of dyes. The Of values of PTE, PDI and DiPhAPDI were all higher than 93.0% in solution and 84.8%, 94.3% and 73.6%, respectively in PS:dye fibers. Embedding the fibers in PDMS improved the photostabilities of the dyes two folds compared to their solution phases. The prepared dye containing fibers were combined together into a single PDMS film and utilized as a frequency conversion layer on a blue LED. Fabricated samples were found to show high color rendering index (>= 90), adjustable CCT (7500 K-5000 K), and power efficiency values exceeding 2001m/W depending on the used fiber amount in mass.Article Citation - WoS: 15Citation - Scopus: 16Monitoring the Crystal Orientation of Black-Arsenic Via Vibrational Spectra(Royal Society of Chemistry, 2019) Kandemir, Ali; İyikanat, Fadıl; Şahin, HasanIn this study, the structural, mechanical, and vibrational properties of a recently discovered anisotropic ultra-thin material, black-arsenic (b-As), are investigated by using density functional theory. Direction dependent elastic constants such as in-plane stiffness, Young's modulus and Poisson's ratio of single-layer b-As are calculated and compared with those of the structural cousin black-phosphorus (b-P). The calculated Poisson's ratio of b-As for the zigzag direction is nearly 1, which is quite higher than that of b-P, 0.65. Besides, it is found that all the three elastic constants are highly anisotropic and their values in the zigzag direction are almost three times higher than that of the armchair direction. The mechanical strength of the material is also calculated and high-toughness is seen in both armchair and zigzag directions. It is revealed that the material is quite stiff against straining along the zigzag direction; in contrast, it is quite flexible along the armchair direction. Vibrational stability analysis shows that the material is stable up to 9% biaxially applied strain, and 12% and 45% uniaxially applied strain in the zigzag and armchair directions, respectively. Furthermore, the prominent Raman active peaks of the b-As structure show strong anisotropy in the strain dependent vibrational spectra and they can also be used for easy-determination of the crystal orientation of b-As from Raman measurements.Article Citation - WoS: 63Citation - Scopus: 65Amidoxime Functionalized Polymers of Intrinsic Microporosity (pim-1) Electrospun Ultrafine Fibers for Rapid Removal of Uranyl Ions From Water(Elsevier Ltd., 2019) Satılmış, Bekir; Isık, Tuğba; Demir, Mustafa Muammer; Uyar, TamerThe Polymers of Intrinsic Microporosity (PIM-1) is considered as one of the most promising polymer candidates for adsorption applications owing to its high surface area and the ability to tailor the functionality for the targeted species. This study reports a facile method for the preparation of amidoxime functionalized PIM-1 fibrous membrane (AF-PIM-FM) by electrospinning technique and its practical use for the extraction of U(VI) ions from aqueous systems via column sorption under continuous flow. Fibrous membrane form of amidoxime functionalized PIM-1 (AF-PIM-FM) was prepared by electrospinning method owing to its excellent processability in dimethylformamide. Bead-free and uniform fibers were obtained as confirmed by SEM imaging and average fiber diameter was 1.69 +/- 0.34 mu m for AF-PIM-FM. In addition, electrospun PIM-1 fibrous membrane (PIM-FM) was prepared as a control group. Structural and thermal characterization of powder and membrane forms of the materials were performed using FT-IR, H-1 NMR, XPS, Elemental analyses, TGA, and DSC. The porosity of the samples was measured by N-2 sorption isotherms confirming amidoxime PIM-1 still maintain their porosity after functionalization. Amidoxime functionality along with membrane structure makes AF-PIM-FM a promising material for uranyl adsorption. First, a comparison between powder and membrane form of amidoxime functionalized PIM-1 was investigated using batch adsorption process. Although membrane form has shown slightly lower adsorption performance in the batch adsorption process, the advantage of using the membrane in column adsorption processes makes membrane form more feasible for real applications. In addition, amidoxime modification enhanced the uranium adsorption ability of PIM-FM up to 20 times. The effect of initial concentration and pH were investigated along with regeneration of the adsorbents. AF-PIM-FM was successfully used for five adsorption-desorption cycles without having any damage on the fibrous structure.