Researcher:
Press, Daniel Aaron

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Daniel Aaron

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Press

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Press, Daniel Aaron

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2014 - 20188

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Researcher Of Publications: search.filters.isAuthorOfPublication.af832d73-d2dc-40bd-b4f6-9f4802f9deeb

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Now showing 1 - 8 of 8
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    3D coffee stains
    (Royal Soc Chemistry, 2017) N/A; N/A; Department of Electrical and Electronics Engineering; N/A; N/A; N/A; Department of Molecular Biology and Genetics; Department of Chemistry; Department of Chemistry; Department of Electrical and Electronics Engineering; Doğru-Yüksel, Itır Bakış; Söz, Çağla Koşak; Press, Daniel Aaron; Melikov, Rustamzhon; Begar, Efe; Çonkar, Deniz; Karalar, Elif Nur Fırat; Yılgör, Emel; Yılgör, İskender; Nizamoğlu, Sedat; PhD Student; PhD Student; Researcher; PhD Student; PhD Student; PhD Student; PhD Student; Faculty Member; Researcher; Faculty Member; Faculty Member; Department of Molecular Biology and Genetics; Department of Chemistry; Department of Electrical and Electronics Engineering; N/A; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); N/A; N/A; N/A; N/A; N/A; N/A; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; College of Sciences; College of Engineering; N/A; N/A; N/A; N/A; N/A; N/A; 206349; N/A; 24181; 130295
    When a liquid droplet (e.g., coffee, wine, etc.) is splattered on a surface, the droplet dries in a ring-shaped stain. This widely observed pattern in everyday life occurs due to the phenomenon known as a coffee stain (or coffee ring) effect. While the droplet dries, the capillary flow moves and deposits the particles toward the pinned edges, which shows a 2D ring-like structure. Here we demonstrate the transition from a 2D to a 3D coffee stain that has a well-defined and hollow sphere-like structure, when the substrate surface is switched from hydrophilic to superhydrophobic. The 3D stain formation starts with the evaporation of the pinned aqueous colloidal droplet placed on a superhydrophobic surface that facilitates the particle flow towards the liquid-air interface. This leads to spherical skin formation and a cavity in the droplet. Afterwards the water loss in the cavity due to pervaporation leads to bubble nucleation and growth, until complete evaporation of the solvent. In addition to the superhydrophobicity of the surface, the concentration of the solution also has a significant effect on 3D coffee stain formation. Advantageously, 3D coffee stain formation in a pendant droplet configuration enables the construction of all-protein lasers by integrating silk fibroin with fluorescent proteins. No tools, components and/or human intervention are needed after the construction process is initiated; therefore, 3D coffee-stains hold promise for building self-assembled and functional 3D constructs and devices from colloidal solutions.
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    Radiative energy transfer in color-conversion LEDs
    (Optica Publishing Group (formerly OSA), 2018) N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; N/A; Department of Electrical and Electronics Engineering; Melikov, Rustamzhon; Press, Daniel Aaron; Kumar, Baskaran Ganesh; Sadeghi, Sadra; Nizamoğlu, Sedat; PhD Student; Researcher; Other; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; N/A; 130295
    We developed a matrix method that calculates and reveals all the radiative energy transfer processes of absorption, reabsorption, inter-absorption and their iterative and combinatorial interactions in down-conversion layer of a light-emitting diode.
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    Protein integrated white LEDs for lighting
    (Optica Publishing Group (formerly OSA), 2014) N/A; Department of Electrical and Electronics Engineering; N/A; N/A; Department of Molecular Biology and Genetics; Department of Electrical and Electronics Engineering; Press, Daniel Aaron; Melikov, Rustamzhon; Çonkar, Deniz; Karalar, Elif Nur Fırat; Nizamoğlu, Sedat; Researcher; PhD Student; PhD Student; Faculty Member; Faculty Member; Department of Molecular Biology and Genetics; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Engineering; N/A; N/A; N/A; 206349; 130295
    We demonstrated a new class of white LEDs based on biologically-derived fluorescent proteins. For this we expressed eGFP and mCherry proteins, and integrated them over blue LED chips for cool-, daylight- and warm-white light generation.
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    Thermal and optical performance of eco-friendly silk fibroin proteins as a cavity encapsulation over LED systems
    (American Society of Mechanical Engineers, 2015) Tamdogan, Enes; Arik, Mehmet; Yuruker, Sevket Umut; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Melikov, Rustamzhon; Nizamoğlu, Sedat; Press, Daniel Aaron; PhD Student; Faculty Member; Researcher; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 130295; N/A
    The demand for high power LEDs for illumination applications is increasing. LED package encapsulation is one of most critical materials that affect the optical path of the generated light by LEDs, and may result in lumen degradation. A typical encapsulation material is a mixture of phosphor and a polymer based binder such as silicone. After LED chips are placed at the base of a cavity, phosphor particles are mixed with silicone and carefully placed into the cavity. One of the important technical challenges is to ensure a better thermal conductivity than 0.2 W/m-K of current materials for most of the traditional polymers in SSL applications. In this study, we investigated an unconventional material of the silk fibroin proteins for LED applications, and showed that this biomaterial provides thermal advantages leading to an order of magnitude higher thermal performance than conventional silicones. Silk fibroin is a natural protein and directly extracted from silk cocoons produced by Bombyx mori silkworm. Therefore, it presents a "green" material for photonic applications with its superior properties of biocompatibility and high optical transparency with a minimal absorption. Combining these properties with high thermal performance makes this biomaterial promising for future LED applications. An experimental and computational study to understand the optical and thermal performance is performed. A computational fluid dynamics study with a commercial CFD software was performed and an experimental set-up was developed to validate the computational findings to determine the thermal conductivity of the proposed material.
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    Fluorescent protein integrated white LEDs for displays
    (Iop Publishing Ltd, 2016) N/A; Department of Electrical and Electronics Engineering; N/A; N/A; Department of Molecular Biology and Genetics; Department of Electrical and Electronics Engineering; Press, Daniel Aaron; Melikov, Rustamzhon; Çonkar, Deniz; Karalar, Elif Nur Fırat; Nizamoğlu, Sedat; Researcher; PhD Student; PhD Student; Faculty Member; Faculty Member; Department of Molecular Biology and Genetics; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Engineering; N/A; N/A; N/A; 206349; 130295
    The usage time of displays (e.g., TVs, mobile phones, etc) is in general shorter than their functional life time, which worsens the electronic waste (e-waste) problem around the world. The integration of biomaterials into electronics can help to reduce the e-waste problem. In this study, we demonstrate fluorescent protein integrated white LEDs to use as a backlight source for liquid crystal (LC) displays for the first time. We express and purify enhanced green fluorescent protein (eGFP) and monomeric Cherry protein (mCherry), and afterward we integrate these proteins as a wavelength-converter on a blue LED chip. The protein-integrated backlight exhibits a high luminous efficacy of 248 lm/W-opt and the area of the gamut covers 80% of the NTSC color gamut. The resultant colors and objects in the image on the display can be well observed and distinguished. Therefore, fluorescent proteins show promise for display applications.
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    Eco-friendly silk-hydrogel lenses for LEDs
    (Optica Publishing Group (formerly OSA), 2018) N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; N/A; N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Melikov, Rustamzhon; Press, Daniel Aaron; Kumar, Baskaran Ganesh; Doğru-Yüksel, Itır Bakış; Sadeghi, Sadra; Chirea, Mariana; Yılgör, İskender; Nizamoğlu, Sedat; PhD Student; Researcher; Other; PhD Student; PhD Student; Researcher; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Engineering; N/A; N/A; N/A; N/A; N/A; N/A; 24181; 130295
    In this study, silk fibroin in hydrogel form is analyzed as an eco-friendly alternative to conventional polymers for lens applications in light-emitting diodes. The intensity profile was controlled via dome- and crater-type lenses.
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    All-protein 3D coffee stain lasers
    (Optica Publishing Group (formerly OSA), 2018) N/A; N/A; Department of Electrical and Electronics Engineering; N/A; N/A; N/A; Department of Molecular Biology and Genetics; Department of Chemistry; Department of Chemistry; Department of Electrical and Electronics Engineering; Doğru-Yüksel, Itır Bakış; Söz, Çağla Koşak; Press, Daniel Aaron; Melikov, Rustamzhon; Begar, Efe; Çonkar, Deniz; Karalar, Elif Nur Fırat; Yılgör, Emel; Yılgör, İskender; Nizamoğlu, Sedat; PhD Student; PhD Student; Researcher; PhD Student; PhD Student; PhD Student; Faculty Member; Researcher; Faculty Member; Faculty Member; Department of Molecular Biology and Genetics; Department of Chemistry; Department of Electrical and Electronics Engineering; N/A; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); N/A; N/A; N/A; N/A; N/A; N/A; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; College of Sciences; College of Engineering; N/A; N/A; N/A; N/A; N/A; N/A; 206349; N/A; 24181; 130295
    The transition from a 2D to a 3D coffee stain that has a well-defined and hollow spherelike structure is demonstrated. Self-assembled all-protein lasers are constructed by 3D coffee stains.
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    PublicationOpen Access
    Unravelling radiative energy transfer in solid-state lighting
    (American Institute of Physics (AIP) Publishing, 2018) Department of Electrical and Electronics Engineering; Melikov, Rustamzhon; Press, Daniel Aaron; Kumar, Baskaran Ganesh; Sadeghi, Sadra; Nizamoğlu, Sedat; PhD Student; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; N/A; N/A; N/A; N/A; 130295
    Today, a wide variety of organic and inorganic luminescent materials (e.g., phosphors, quantum dots, etc.) are being used for lighting and new materials (e.g., graphene, perovskite, etc.) are currently under investigation. However, the understanding of radiative energy transfer is limited, even though it is critical to understand and improve the performance levels of solid-state lighting devices. In this study, we derived a matrix approach that includes absorption, reabsorption, inter-absorption and their iterative and combinatorial interactions for one and multiple types of fluorophores, which is simplified to an analytical matrix. This mathematical approach gives results that agree well with the measured spectral and efficiency characteristics of color-conversion light-emitting diodes. Moreover, it also provides a deep physical insight by uncovering the entire radiative interactions and their contribution to the output optical spectrum. The model is universal and applicable for all kinds of fluorophores.