Browsing by Subject "Paper"

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Kağıt sanayisine adanmış bir hayat: Mehmet Ali Kağıtçı
(Bilkent University, 2018) Mert, Veli Can; Arslan, Atakan; Keskin, İbrahim Burak; Harlak, Mehmet Yiğit; Türkyaşar, Arda
Yeni kurulan Türkiye Cumhuriyeti Devleti’nde birçok sanayi sektöründe olduğu gibi kağıt sanayisinde de dünya standartlarını yakalamak gerekliliği doğmuştur. Ġstanbul üniversitesi Fen Fakültesi Kimya Bölümünde öğrenimini tamamlayan Mehmet Ali Kağıtçı daha sonra Almanya ve Fransa’da çeşitli kağıt fabrikalarında ve enstitülerde çalışmış ve Kağıt Mühendisi unvanı almıştır. Türkiye’ye dönüşünün ardından kağıt ve karton üretiminde kullanılabilecek hammade araşıylarına başlayan ve gerekli makamlara raporlar yazan Kağıtçı bu süreçte çeşitli engelleme ve yalanlamalara maruz kalmıştır. Daha sonra kendisinin de fikri alınarak kurulan Ġzmit Kağıt Fabrikası’nda müdürlük görevinde bulunan Kağıtçı çeşitli sabotajlarla görevinden alınmıştır. Türkiye’de Kağıt Sanayisinin öncülerinden olan Mehmet Ali Kağıtçı’nın hayat hikayesi ülkede kağıt sanayisinin gelişimi ve günümüz sanayisine yansıması açısından anlatılmaya değerdir.
Open Access
One-step deposition of hydrophobic coatings on paper for printed-electronics applications
(Springer, 2019) Gözütok, Z.; Kinj, Ö.; Torun, İ.; Özdemir, A. T.; Önses, Mustafa Serdar
The ability to pattern highly conductive features on paper substrates is critically important for applications in radio frequency identification (RFID) tags, displays, sensors, printed electronics, and diagnostics. Ink-jet printing particle-free reactive silver inks is an additive, material efficient and versatile strategy for fabrication of highly conductive patterns; however, the intrinsic wetting properties of cellulose based papers are not suitable to serve as substrates for this process. This study reports one-step and practical modification of the surface of paper substrates using industrially available materials. The paper substrates were dip-coated with films of hydrocarbon and fluorocarbon based polymeric resins. Ink-jet printing particle-free reactive silver inks on the modified paper substrates followed by fast thermal annealing resulted in highly conductive patterns. The coatings improved the conductivity of the patterns and reduced the number of printing layers required to obtain conductivity. We finally demonstrated fabrication of a printed RFID tag on the coated paper substrates operating at the frequency range of 865–870 MHz.
Open Access
Rapid and alternative fabrication method for microfluidic paper based analytical devices
(Elsevier B.V., 2016) Malekghasemi, S.; Kahveci, E.; Duman, M.
A major application of microfluidic paper-based analytical devices (µPADs) includes the field of point-of-care (POC) diagnostics. It is important for POC diagnostics to possess properties such as ease-of-use and low cost. However, µPADs need multiple instruments and fabrication steps. In this study, two different chemicals (Hexamethyldisilazane and Tetra-ethylorthosilicate) were used, and three different methods (heating, plasma treatment, and microwave irradiation) were compared to develop µPADs. Additionally, an inkjet-printing technique was used for generating a hydrophilic channel and printing certain chemical agents on different regions of a modified filter paper. A rapid and effective fabrication method to develop µPADs within 10 min was introduced using an inkjet-printing technique in conjunction with a microwave irradiation method. Environmental scanning electron microscope (ESEM) and x-ray photoelectron spectroscopy (XPS) were used for morphology characterization and determining the surface chemical compositions of the modified filter paper, respectively. Contact angle measurements were used to fulfill the hydrophobicity of the treated filter paper. The highest contact angle value (141°±1) was obtained using the microwave irradiation method over a period of 7 min, when the filter paper was modified by TEOS. Furthermore, by using this method, the XPS results of TEOS-modified filter paper revealed Si2p (23%) and Si-O bounds (81.55%) indicating the presence of Si–O–Si bridges and Si(OEt) groups, respectively. The ESEM results revealed changes in the porous structures of the papers and decreases in the pore sizes. Washburn assay measurements tested the efficiency of the generated hydrophilic channels in which similar water penetration rates were observed in the TEOS-modified filter paper and unmodified (plain) filter paper. The validation of the developed µPADs was performed by utilizing the rapid urease test as a model test system. The detection limit of the developed µPADs was measured as 1 unit ml−1 urease enzyme in detection zones within a period of 3 min. The study findings suggested that a combination of microwave irradiation with inkjet-printing technique could improve the fabrication method of µPADs, enabling faster production of µPADs that are easy to use and cost-effective with long shelf lives.
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SEKA Taşucu kağıt fabrikası
(Bilkent University, 2023) Coşan, Berkin Mert; Güven, Utku; Alabaş, Cem; Kaya, Emirhan; Ardıç, Simay
SEKA Taşucu Fabrikası, Türkiye'nin kağıt üretimindeki dışa bağımlılığını azaltma misyonu doğrultusunda Taşucu Limanı'nda konumlanmış önemli bir tesistir. Fabrika, SEKA'nın yıllar içinde kurduğu bir dizi fabrikadan sadece biridir. SEKA Taşucu Fabrikası, bir dönem kağıt üretimine ara vermiştir. Bir süre sonra tekrardan seri kağıt üretimine başlayan fabrikanın özelleştirilmesi kararlaştırılmıştır. Özelleştirilmesinden kısa bir süre sonra ise fabrikanın kalıcı olarak kapatılmasına karar verilmiştir. Fabrikanın seri kağıt üretimi yaptığı zaman aralıklarında çalıştırdığı yüzlerce personeli ile ülkenin kağıt endüstrisine ve bölge ekonomisine büyük faydaları dokunmuştur.
Open Access
SPM management using markov chain based data access prediction
(IEEE, 2008-11) Yemliha, T.; Srikantaiah, S.; Kandemir, M.; Öztürk, Özcan
Leveraging the power of scratchpad memories (SPMs) available in most embedded systems today is crucial to extract maximum performance from application programs. While regular accesses like scalar values and array expressions with affine subscript functions have been tractable for compiler analysis (to be prefetched into SPM), irregular accesses like pointer accesses and indexed array accesses have not been easily amenable for compiler analysis. This paper presents an SPM management technique using Markov chain based data access prediction for such irregular accesses. Our approach takes advantage of inherent, but hidden reuse in data accesses made by irregular references. We have implemented our proposed approach using an optimizing compiler. In this paper, we also present a thorough comparison of our different dynamic prediction schemes with other SPM management schemes. SPM management using our approaches produces 12.7% to 28.5% improvements in performance across a range of applications with both regular and irregular access patterns, with an average improvement of 20.8%.
Open Access
Transferring the structure of paper for mechanically durable superhydrophobic surfaces
(Elsevier, 2020-10-24) Torun, İ.; Celik, N.; Ruzi, M.; Önses, Mustafa Serdar
Solution-phase deposition of nanomaterials represents a highly promising technology with strong industrial application potential for the fabrication of superhydrophobic surfaces. An important barrier towards the adaptation of such materials and processes in a broad range of applications is the limited mechanical durability of the nanostructures. Herein, we present a universal solution to this challenge by benefiting from the unique micro-structure of paper. Our approach is based on transferring the structure of paper into a target material, to form a mechanical protection layer for nanomaterials that were deposited from solution-phase, i.e. spray-coating. We demonstrate this concept through the transfer of the structure of paper to a free-standing PDMS film using a simple molding process. Spraying a dispersion of alkyl-silane functionalized silica nanoparticles on the structured free-standing film results in a hierarchically structured superhydrophobic surface with a water contact angle of 175° ± 2° and a sliding angle <2° ± 1°. The fabricated superhydrophobic surface displays high levels of mechanical, chemical and thermal stability. The robust, inexpensive, scalable, flexible, and environmentally friendly nature of the presented approach may be a key enabler in superhydrophobic coating applications.