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Advances in Electrospun Fiber-Based Flexible Nanogenerators for Wearable Applications
(Wiley-v C H verlag Gmbh, 2021) Arica, Tugce A.; Isik, Tugba; Guner, Tugrul; Horzum, Nesrin; Demir, Mustafa M.; Demir, Mustafa
In today's digital age, the need and interest in personal and portable electronics shows a dramatic growth trend in daily life parallel to the developments in sensors technologies and the internet. Wearable electronics that can be attached to clothing, accessories, and the human body are one of the most promising subfields. The energy requirement for the devices considering the reduction in device sizes and the necessity of being flexible and light, the existing batteries are insufficient and nanogenerators have been recognized a suitable energy source in the last decade. The mechanical energy created by the daily activities of the human body is an accessible and natural energy source for nanogenerators. Fiber-structured functional materials contribute to the increase in energy efficiency due to their effective surface to volume ratio while providing the necessary compatibility and comfort for the movements in daily life with its flexibility and lightness. Among the potential solutions, electrospinning stands out as a promising technique that can meet these requirements, allowing for simple, versatile, and continuous fabrication. Herein, wearable electronics and their future potential, electrospinning, and its place in energy applications are overviewed. Moreover, piezoelectric, triboelectric, and hybrid nanogenerators fabricated or associated with electrospun fibrous materials are presented.
Asthma in the context of global alliance against respiratory diseases (GARD) in Turkey
(AME Publishing Company, 2018) Yorgancioğlu,A.; Gemicioglu,B.; Ekinci,B.; özkan,Z.; Bayram,H.; Ergan,B.; Köktürk,N.
[No abstract available]
Cell proliferation and cytotoxicity assays
(Bentham Science Publishers B.V., 2016) Baran, Yusuf; Kiraz,Y.; Baran,Y.
Cell viability is defined as the number of healthy cells in a sample and proliferation of cells is a vital indicator for understanding the mechanisms in action of certain genes, proteins and pathways involved cell survival or death after exposing to toxic agents. Generally, methods used to determine viability are also common for the detection of cell proliferation. Cell cytotoxicity and proliferation assays are generally used for drug screening to detect whether the test molecules have effects on cell proliferation or display direct cytotoxic effects. Regardless of the type of cell-based assay being used, it is important to know how many viable cells are remaining at the end of the experiment. There are a variety of assay methods based on various cell functions such as enzyme activity, cell membrane permeability, cell adherence, ATP production, co-enzyme production, and nucleotide uptake activity. These methods could be basically classified into different categories: (I) dye exclusion methods such as trypan blue dye exclusion assay, (II) methods based on metabolic activity, (III) ATP assay, (IV) sulforhodamine B assay, (V) protease viability marker assay, (VI) clonogenic cell survival assay, (VII) DNA synthesis cell proliferation assays and (V) raman micro-spectroscopy. In order to choose the optimal viability assay, the cell type, applied culture conditions, and the specific questions being asked should be considered in detail. This particular review aims to provide an overview of common cell proliferation and cytotoxicity assays together with their own advantages and disadvantages, their methodologies, comparisons and intended purposes. © 2016 Bentham Science Publishers.
Challenges in the preparation of optical polymer composites with nanosized pigment particles: A review on recent efforts
(2012) Demir M.M.; Wegner, G.
Blends of nanosized pigment particles and polymers are widely believed to offer the potential for the design of novel or at least improved materials. This review critically evaluates the recent literature with regard to the following issues: (a) why and how does the size of the particles matter, (b) what are the requirements to create compatibility between amorphous polymers and nanoparticles, (c) carbon allotropes as nanosized pigments, (d) bulk polymerization of monomer/pigment mixtures, (e) interaction of growing chains with the particles in the polymerization, (f) depletion flocculation as a mechanism to counteract homogeneous distribution of the particles in the polymer matrix and ways to suppress the undesirable flocculation, and (g) optical properties of the blends as well as methods of optical characterization. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Correction to: Enhanced light–matter interaction in a hybrid photonic–plasmonic cavity (Applied Physics A, (2021), 127, 12, (907), 10.1007/s00339-021-05071-x)
(Springer Science and Business Media Deutschland GmbH, 2022) Gökbulut B.; Inanç A.; Topcu G.; Ozcelik S.; Demir M.M.; Inci, M.N.
In this article the statement in the Funding information section was incorrect. The correct Funding information is as follows. ‘Dr Belkıs Gökbulut acknowledges TUBITAK for the financial support provided under Contract Number 120F323’. © The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature 2022.
Dynamic response of single and multi-span beams under a moving load using dynamic stiffness formulations and Galerkin's method
(European Association for Structural Dynamics, 2020) Bozyigit,B.; Acikgoz,S.; Yesilce,Y.
This paper is concerned with the dynamic response analysis of single and multi-span beams under moving point loads. The Dynamic Stiffness Method (DSM) is used to calculate the mode frequencies and shapes of single, two and four-span Bernoulli-Euler beams. The exact mode shapes obtained from dynamic stiffness formulations are used to derive generalized mass, stiffness and force terms for normal modes using Galerkin 's method. This enables efficient and accurate calculation of the time-history response of the investigated structures. This is demonstrated by comparing the results from this study with advanced finite element simulations of the same problem from the literature. The results validate the accuracy of this approach and demonstrate how this technique can be used to model dynamic amplification of bridges under the influence of moving loads. © 2020 European Association for Structural Dynamics. All rights reserved.
Endogenous miRNA Sponges
(Humana Press Inc., 2022) Akgül, Bünyamin; Akgül,B.
MicroRNAs (miRNAs) are a class of noncoding RNAs of 17–22 nucleotides in length with a critical function in posttranscriptional gene regulation. These master regulators are themselves subject to regulation both transcriptionally and posttranscriptionally. Recently, miRNA function has been shown to be modulated by exogenous RNA molecules that function as miRNA sponges. Interestingly, endogenous transcripts such as transcribed pseudogenes, long noncoding RNAs (lncRNAs), circular RNAs (circRNAs) and mRNAs may serve as natural miRNA sponges. These transcripts, which bind to miRNAs and competitively sequester them away from their targets, are naturally existing endogenous miRNA sponges, called competing endogenous RNAs (ceRNAs). Here we present a historical background of miRNAs, exogenous and endogenous miRNA sponges as well as some examples of endogenous miRNA sponges involved in regulatory mechanisms associated with various diseases, developmental stages, and other cellular processes. © 2022, Springer Science+Business Media, LLC, part of Springer Nature.
Epitranscriptomics Changes the Play: m6A RNA Modifications in Apoptosis
(Springer, 2022) Akçaöz,A.; Akgül, Bünyamin; Akgül,B.
Apoptosis is a form of programmed cell death that is essential for cellular and organismal homeostasis. Any irregularities that disturb the balance between apoptosis and cell survival have severe implications, such as improper development or life-threatening diseases. Thus, it is highly critical to maintain a proper rate of apoptosis throughout development. In fact, several complex transcriptional and posttranscriptional mechanisms exist in eukaryotes to critically regulate the rate of apoptotic processes. Recent studies suggest that not only RNA sequences but also their modifications, such as m6A methylation, play a fundamental role in these transcriptional and posttranscriptional processes. A specific set of proteins, called writer, eraser, and reader of m6A marks, modulate the rate of apoptosis by determining the m6A repertoire and the fate of certain transcripts associated with apoptosis. In this Review, we will cover the dynamic m6A RNA modifications and their impact on modulation of apoptosis. © 2022, Springer Nature Switzerland AG.
Experimental MicroRNA Detection Methods
(Humana Press Inc., 2022) Akgül, Bünyamin; Akgül,B.
MicroRNAs (miRNAs) are considerably small yet highly important riboregulators involved in nearly all cellular processes. Due to their critical roles in posttranscriptional regulation of gene expression, they have the potential to be used as biomarkers in addition to their use as drug targets. Although computational approaches speed up the initial genomewide identification of putative miRNAs, experimental approaches are essential for further validation and functional analyses of differentially expressed miRNAs. Therefore, sensitive, specific, and cost-effective microRNA detection methods are imperative for both individual and multiplex analysis of miRNA expression in different tissues and during different developmental stages. There are a number of well-established miRNA detection methods that can be exploited depending on the comprehensiveness of the study (individual miRNA versus multiplex analysis), the availability of the sample and the location and intracellular concentration of miRNAs. This review aims to highlight not only traditional but also novel strategies that are widely used in experimental identification and quantification of microRNAs. © 2022, Springer Science+Business Media, LLC, part of Springer Nature.
Fabrication of polymer nanofiber-conducting polymer fabric and noncontact motion sensing platform
(Trans Tech Publications Ltd, 2018) Mutlu M.U.; Akin O.; Demir M.M.; Yildiz, Ü.H.
Conductive polymer-electrospun polymer nanofiber network was combined to host iron oxide nanoparticles providing micrometer thick sensing interface. The sensor has fabricated as freestanding fabric exhibiting 10 to 100 KOhm base resistivity upon bias applied. The moving object has been sensed through the electrostatic interactions between fibers and object. The sensing range has been found to be 1-5 cm above the surface of fabric. By the controlled combination of conductive polymers electrospun polymer nanofibers effective device miniaturization has been provided without loss of performance. The noncontact motion sensor platform has unique flexibility and light weight holding a potential for wearable sensor technology. © 2018 Trans Tech Publications, Switzerland.
Foreword
(CRC Press, 2023) Baran, Yusuf
[No abstract available]
Free vibration analysis of arch-frames using the dynamic stiffness approach
(EXTRICA, 2020) Bozyigit,B.; Yesilce,Y.; Acikgoz,S.
The aim of this study is to investigate free vibration characteristics of arch-frames which consist of two columns and an arch. Firstly, an exact formulation of the problem is presented using the Dynamic Stiffness Method (DSM). The end forces and displacements of column elements are obtained analytically using Timoshenko beam theory (TBT). These are then combined with the end forces and displacements of the semi-circular arch, which is modeled with exact curved beam elements that consider axial and shear deformations and rotational inertia. By employing standard assembly and bisection based root finding procedures, exact free vibration analysis of the whole vibrating system is carried out. Then, in an effort to simplify the formulations, an approach based on approximating the arch as assembly of linear straight beam segments is presented. The calculated natural frequencies using DSM for both exact and approximate results are then tabulated for comparison purposes. The mode shapes are also compared. The results show that the proposed model simplification is effective and produces accurate mode frequency and shape estimations. © 2020 Baran Bozyigit, et al.
Green electrospinning
(De Gruyter, 2019) Horzum N.; Muñoz-Espí R.; Hood M.A.; Demir M.M.; Crespy, D.
In the last two decades, electrospinning has grown in popularity; however, the majority of the setups are based on solution processing from toxic organic solvents. As green processing and environmental stewardship have also become important in recent years, for political and economic reasons, the subsequent increase in demand for the scaling up of electrospinning requires that an environmentally toxin-free process be championed. This book comprehensively addresses clean and safe electrospinning for the fabrication of green nanofibers and evaluates their potential applications. © 2019 Walter de Gruyter GmbH, Berlin/Boston. All rights reserved.
Green processes and green fibers
(De Gruyter, 2019) Horzum N.; Muñoz-Espí R.; Hood M.A.; Demir M.M.; Crespy, D.
"Green Electrospinning" not from only non-toxic solvents but also from biopolymer solutions has become popular in recent years. Green fibers are particularly interesting for biomedical applications such as tissue engineering, drug delivery, biocompatible scaffolds, biosensors, and for photovoltaics, supercapacitors, fuel cells, battery components as energy fields, and for filtration membranes as environmental applications. In this chapter, we classified green electrospinning into two groups: (i) green processes as polymer free, solvent free, solution, and colloid electrospinning, (ii) green fibers from natural polymers and blends. © 2019 Walter de Gruyter GmbH, Berlin/Boston. All rights reserved.
Intracytoplasmic Re-localization of miRISC Complexes
(Frontiers Media Sa, 2018) Akgul, Bunyamin; Erdogan, Ipek; Akgül, Bünyamin
MicroRNAs (miRNAs) are a conserved class of non-coding RNAs of 22 nucleotides that post-transcriptionally regulate gene expression through translational repression and/or mRNA degradation. A great progress has been made regarding miRNA biogenesis and miRNA-mediated gene regulation. Additionally, an ample amount of information exists with respect to the regulation of miRNAs. However, the cytoplasmic localization of miRNAs and its effect on gene regulatory output is still in progress. We provide a current review of the cytoplasmic miRNA localization in metazoans. We then discuss the dynamic changes in the intracytoplasmic localization of miRNAs as a means to regulate their silencing activity. We then conclude our discussion with the potential molecules that could modulate miRNA localization.
Investigation of lithium sorption efficiency using swcnt functionalized electrospun fiber mats from the hypersaline geothermal brine
(Trans Tech Publications Ltd, 2018) Çelik A.; Topçu G.; Isik T.; Baba A.; Horzum N.; Demir, M.M.
Geothermal mining from brines becomes increasingly important with the increasing demand for rare earth elements in various engineering applications. Geothermal fluids contain valuable minerals and metals such as silica, zinc, lithium, and other materials that can be processed to recover these products. Solution mining by nature is challenging because of variable composition as well as the concentration of the interfering ions, particularly calcium and magnesium, and the presence of interfering ions increases the recovery costs requiring additional steps. The aim of this study is the fabrication of single-walled carbon nanotube functionalized electrospun chitosan, poly(methyl methacrylate) (PMMA), and polyacrylonitrile (PAN) fiber mats. Effect of polymer type, dilution factor, and surface modification on the sorption of lithium (Li+) ions was investigated. The maximum sorption performance was obtained with SWCNT functionalized PAN (15 wt%) fiber mats and they have sorption percentage as 55% at diluted (1/100) brine samples. © 2018 Trans Tech Publications, Switzerland.
Long Noncoding RNAs in Human Cancer and Apoptosis
(Bentham Science Publ Ltd, 2023) Erdogan, Ipek; Sweef, Osama; Akgul, Bunyamin; Akgül, Bünyamin
Genome annotations have uncovered the production of at least one transcript from nearly all loci in the genome at some given time throughout the development. Surprisingly, many of these transcripts do not code for proteins and are relatively long in size, thus called long noncoding RNAs (lncRNAs). Next- and third-generation sequencing technologies have amassed numerous lncRNAs expressed under different phenotypic conditions, yet many remain to be functionally characterized. LncRNAs regulate gene expression by functioning as scaffold, decoy, signaling, and guide molecules both at the transcriptional and post-transcriptional levels, interacting with different types of macromolecules, such as proteins, DNA, and RNA. Here, we review the potential regulatory role of lncRNAs in apoptosis and cancer as some of these lncRNAs may have the diagnostic and therapeutic potential in cancer.
Macromol. Mater. Eng. 7/2016
(Wiley-VCH Verlag, 2016) Isık T.; Horzum N.; Yıldız Ü.H.; Liedberg B.; Demir, M.M.
[No abstract available]
Major apoptotic mechanisms and genes involved in apoptosis
(Sage Publications Ltd, 2016) Kiraz, Yagmur; Adan, Aysun; Yandim, Melis Kartal; Baran, Yusuf; Baran, Yusuf
As much as the cellular viability is important for the living organisms, the elimination of unnecessary or damaged cells has the opposite necessity for the maintenance of homeostasis in tissues, organs and the whole organism. Apoptosis, a type of cell death mechanism, is controlled by the interactions between several molecules and responsible for the elimination of unwanted cells from the body. Apoptosis can be triggered by intrinsically or extrinsically through death signals from the outside of the cell. Any abnormality in apoptosis process can cause various types of diseases from cancer to auto-immune diseases. Different gene families such as caspases, inhibitor of apoptosis proteins, B cell lymphoma (Bcl)-2 family of genes, tumor necrosis factor (TNF) receptor gene superfamily, or p53 gene are involved and/or collaborate in the process of apoptosis. In this review, we discuss the basic features of apoptosis and have focused on the gene families playing critical roles, activation/inactivation mechanisms, upstream/downstream effectors, and signaling pathways in apoptosis on the basis of cancer studies. In addition, novel apoptotic players such as miRNAs and sphingolipid family members in various kind of cancer are discussed.
Message from TAIN Symposium Organizing Committee
(IEEE Computer Society, 2015) Tuglular, T.; Cai, Y.; Dustdar, S.; Yamazaki, K.; Tuğlular, Tuğkan; Bilgisayar Mühendisliği Bölümü
[No abstract available]

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