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Now showing items 1 - 16 of 144

  • Single Atomic Layer Ferroelectric on Silicon

    Dogan, Mehmet   Fernandez-Pena, Stephanie   Komblum, Lior   Jia, Yichen   Kumah, Divine P.   Reiner, James W.   Krivokapic, Zoran   Kolpak, Alexie M.   Ismail-Beigi, Sohrab   Ahn, Charles H.   Walker, Frederick J.  

    A single atomic layer of ZrO2 exhibits ferroelectric switching behavior when grown with an atomically abrupt interface on silicon. Hysteresis in capacitance-voltage measurements of a ZrO2 gate stack demonstrate that a reversible polarization of the ZrO2 interface structure couples to the carriers in the silicon. First-principles computations confirm the existence of multiple stable polarization states and the energy shift in the semiconductor electron states that result from switching between these states. This monolayer ferroelectric represents a new class of materials for achieving devices that transcend conventional complementary metal oxide semiconductor (CMOS) technology. Significantly, a single atomic layer ferroelectric allows for more aggressively scaled devices than bulk ferroelectrics, which currently need to be thicker than 5-10 nm to exhibit significant hysteretic behavior.
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  • Biological properties of PMMA/nHAp and PMMA/3-APT-nHAp nanocomposites

    Diken, Mehmet Emin   Dogan, Serap   Turhan, Yasemin   Dogan, Mehmet  

    In this study, nanocomposite-implant materials with the filler materials, which are nanohydroxyapatite (nHAp) and nHAp modified by [3-(2-aminoethilamino)propyl]trimethoxysilane, using poly(methylmethacrylate) as a matrix according to the melting method, were synthesized. The nanocomposites were characterized using X-ray diffraction, Fourier transform infrared spectroscopy-attenuated total reflectance, scanning electron microscopy, transmission electron microscopy, differential thermal analysis/thermogravimetric analysis, and differential scanning calorimetry devices. Experimental results showed that the thermal stability of nanocomposites increased, and they were hemocompatible, had no negative effect on antioxidant enzymes, and had antibacterial activity. [GRAPHICS] .
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  • A New CFOA Based Grounded Capacitance Multiplier

    Dogan, Mehmet   Yuce, Erkan  

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  • Theory of Ferroelectric ZrO2 Monolayers on Si

    Dogan, Mehmet   Ismail-Beigi, Sohrab  

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  • CFOA based a new grounded inductor simulator and its applications

    Dogan, Mehmet   Yuce, Erkan  

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  • Alternative stacking sequences in hexagonal boron nitride

    Gilbert, Stephen Matthew   Pham, Thang Toan   Dogan, Mehmet   Oh, Sehoon   Shevitski, Brian   Schumm, Gabe   Liu, Stanley   Ercius, Peter   Aloni, Shaul   Cohen, Marvin L   Zettl, Alex  

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  • Synthetic Transformer Design Using Commercially Available Active Components

    Dogan, Mehmet   Yuce, Erkan   Minaei, Shahram   Sagbas, Mehmet  

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  • Single atomic layer ferroelectric on silicon

    Dogan, Mehmet   Fernandez-Pena, Stephanie   Kornblum, Lior   Jia, Yichen   Kumah, Divine   Reiner, James   Krivokapic, Zoran   Kolpak, Alexie M   Ismail-Beigi, Sohrab   Ahn, Charles   Walker, Frederick  

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  • Ruptured mitral valve aneurysm due to infective endocarditis.

    Isilak, Zafer   Kucuk, Ugur   Ucak, Alper   Uz, Omer   Dogan, Mehmet  

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  • Relationship between neutrophil to lymphocyte ratio and slow coronary flow.

    Dogan, Mehmet   Akyel, Ahmet   Cimen, Tolga   Bilgin, Murat   Sunman, Hamza   Kasapkara, Haci Ahmet   Arslantas, Ugur   Yayla, Kadriye Gayretli   Acikel, Sadik   Yeter, Ekrem  

    OBJECTIVES: We evaluated the relationship between neutrophil to lymphocyte ratio (NLR) and slow coronary flow (SCF).; METHODS: A total of 180 participants were recruited to the present study. Of all the participants, 82 patients were with SCF and 98 participants were with normal coronary arteries. Basal characteristics were recorded. Coronary flow was quantified by thrombolysis in myocardial infarction frame count.; RESULTS: Basal characteristics were similar between the 2 groups. The NLR was significantly higher in the SCF group when compared to the control group (2.3 =C2=B1 0.8 and 1.5 =C2=B1 0.4 respectively, P < .001). In multiple logistic regression analysis, NLR remained as the independent predictor of SCF (P < 0.001).; CONCLUSIONS: Our findings showed that NLR was significantly higher in the SCF group when compared to the control group with normal coronary arteries. We also showed that NLR was related to the presence of SCF rather than the extent of SCF. Besides these findings, we also showed the NLR as an independent predictor of SCF. =C2=A9 The Author(s) 2013.
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  • Characterization,adsorption,and electrokinetic properties of modified sepiolite

    Beyli, Pinar Turan   Dogan, Mehmet   Alkan, Mahir   Turkyilmaz, Aydin   Turhan, Yasemin   Demirbas, Ozkan   Namli, Hilmi  

    The metal ion adsorption and electrokinetic properties of sepiolite modified by 3-(trimetoxysilyl)propyl metaacrylate was studied. The characterization of modified sepiolite was made by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning electron micrograph (SEM), and differential thermal analysis/thermogravimetry (DTA/TG). The adsorption behavior of Fe(III), Mn(II), Co(II), Zn(II), Cu(II), and Cd(II) metal ions on modified sepiolite from aqueous solutions was investigated as a function of equilibrium pH, temperature, and ionic strength. The adsorption experiments were carried out using a batch method. The initial and final concentrations of heavy metals were determined by means of atomic absorption spectrophotometry. The zeta potential of the modified sepiolite suspensions was measured as a function of metal ion concentration and equilibrium pH using a Zeta Meter 3.0. The results showed that the amount of adsorbed metal ions increased with solution pH, and that the modified sepiolite adsorbed Cu(II) and Mn(II) ions more than other metal ions. It was found that the temperature had an important effect on metal ion adsorption and that the adsorption process was endothermic in nature. Equilibrium isotherms for the adsorption of metal ions were measured experimentally. Results were analyzed by the Freundlich and Langmuir equations and determined the characteristic parameters for each adsorption isotherm. The isotherm data were reasonably well correlated by Langmuir isotherm. Maximum monolayer adsorption capacity of modified sepiolite for Cu(II), Mn(II), Zn(II), Fe(III), Co(II), and Cd(II) metal ions was calculated from 12.3x10(-5), 11.7x10(-5), 9.0x10(-5), 8.2x10(-5), 5.7x10(-5), and 1.8x10(-5)molL(-1), respectively. The affinity order of adsorption was Cu(II)>Mn(II)>Zn(II)-Fe(III)>Co(II)>Cd(II). The results indicate that modified sepiolite is good adsorbent for the removal of metal ions from aqueous solutions.
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  • Two Photon Absorption in High Power Broad Area Laser Diodes

    Dogan, Mehmet   Michael, Christopher P.   Zheng, Yan   Zhu, Lin   Jacob, Jonah H.  

    Recent advances in thermal management and improvements in fabrication and facet passivation enabled extracting unprecedented optical powers from laser diodes (LDs). However, even in the absence of thermal roll-over or catastrophic optical damage (COD), the maximum achievable power is limited by optical non-linear effects. Due to its non-linear nature, two-photon absorption (TPA) becomes one of the dominant factors that limit efficient extraction of laser power from LDs. In this paper, theoretical and experimental analysis of TPA in high-power broad area laser diodes (BALD) is presented. A phenomenological optical extraction model that incorporates TPA explains the reduction in optical extraction efficiency at high intensities in BALD bars with 100 mu m-wide emitters. The model includes two contributions associated with TPA: the straightforward absorption of laser photons and the subsequent single photon absorption by the holes and electrons generated by the TPA process. TPA is a fundamental limitation since it is inherent to the LD semiconductor material. Therefore scaling the LDs to high power requires designs that reduce the optical intensity by increasing the mode size.
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  • Flame retardant effect of aluminum hypophosphite in heteroatom-containing polymers

    Savas, Lemiye Atabek   Hacioglu, Firat   Hancer, Mehmet   Dogan, Mehmet  

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  • Red cell distribution width: a novel prognostic factor of pulmonary embolism?

    Karagoz, Ergenekon   Dogan, Mehmet   Tanoglu, Alpaslan  

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  • Improve power conversion efficiency of slab coupled optical waveguide lasers

    Fan, Jiahua   Zhu, Lin   Dogan, Mehmet   Jacob, Jonah  

    The slab coupled optical waveguide laser (SCOWL) is a promising candidate for high power, single mode emitter for a number of reasons, including its near diffraction limited optical quality, large modal size and near circular output pattern. Current SCOWL designs have limited electrical-optical power conversion efficiency (PCE) around 40%, which is lower than conventional RWG laser and broad area laser that are known to have much higher PCEs. To improve the SCOWL PCE, we theoretically optimize its structure by reducing Al content, increasing doping concentration and introducing a GRIN layer to prevent carrier leakage. Numerical simulations predict that an optimized SCOWL design has a maximum PCE of about 57% at room temperature. (C) 2014 Optical Society of America
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  • Association Between Platelet to Lymphocyte Ratio and Saphenous Vein Graft Disease

    Yayla, Cagri   Akyel, Ahmet   Yayla, Kadriye Gayretli   Yilmaz, Samet   Acikgoz, Sadik Kadri   Ozcan, Firat   Turak, Osman   Dogan, Mehmet   Yeter, Ekrem   Aydogdu, Sinan  

    Atherosclerosis plays an important role in saphenous vein graft disease (SVGD). Previous trials showed that inflammatory blood cells play a role in this process. The platelet to lymphocyte ratio (PLR) has been proposed as a novel predictor for cardiovascular risk and indicator of atherosclerosis. The aim of this study was to assess the relationship between SVGD and PLR. A total of 220 patients with SVG were enrolled (n =3D 87 with SVGD and n =3D 133 with patent SVG). A 50% stenosis within the SVG was defined as clinically significant. Median PLR (P < .001) and mean platelet volume (MPV; P =3D .043) were significantly higher in patients with SVGD. Also, PLR showed significantly positive correlation with age of SVG (P < .05). Median age of SVGs was also higher in the SVGD group (P =3D .025). In multivariate logistic regression analyses, the PLR and MPV were independent predictors of SVGD. Using a cutoff level of 106.3, the PLR predicted SVGD with a sensitivity of 87.4% and a specificity of 80.3%. To the best of our knowledge, this study showed, for the first time, that PLR was independently associated with SVGD. Both PLR and MPV might predict SVGD.
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