Researcher:
Yüce, Mehdi Yavuz

Profile Picture
ORCID

Job Title

PhD Student

First Name

Mehdi Yavuz

Last Name

Yüce

Name

Name Variants

Yüce, Mehdi Yavuz

Email Address

Birth Date

Filters

2005 - 200932010 - 20126

Advanced Search

Filter by

Settings

Researcher Of Publications: search.filters.isAuthorOfPublication.b9c2b280-5832-419b-84f6-309c5fb5aa8b

Search Results

Now showing 1 - 9 of 9
  • Placeholder
    PublicationMetadata only
    The effect of nanoparticles on the surface hydrophobicity of polystyrene
    (Springer, 2008) N/A; Department of Chemistry; Yüce, Mehdi Yavuz; Demirel, Adem Levent; PhD Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 6568
    The surface hydrophobicity of polystyrene-nanoparticle nanocomposites has been investigated as a function of the nanoparticle content. The addition of hydrophobically coated nanoparticles in polystyrene increased the contact angle θ of a water drop with respect to that on polystyrene surface due to change of surface composition and/or surface roughness. When the nanoparticles dispersed well in the polymer, cos θ decreased linearly with increasing amount of nanoparticles indicating a composite surface consisting of smooth polystyrene regions and rough nanoparticle regions. In case of formation of nanoparticle aggregates in polystyrene, cos θ decreased sharply at a critical concentration of nanoparticles. The observed behaviour was modeled in terms of a transition from Wenzel regime to Cassie-Baxter regime at a critical roughness length scale below which the Laplace pressure prevented the penetration of the water drop into the surface undulations. We argue that multiple length scales are needed below the critical roughness length scale to increase the contact angle further by decreasing the fraction of surface area of solid material (increasing the fraction of surface area of air) underlying the water drop.
  • Placeholder
    PublicationMetadata only
    Single-molecule fluorescence of terrylene embedded in anthracene matrix: a room temperature study
    (Elsevier Science Bv, 2012) N/A; Department of Physics; Yüce, Mehdi Yavuz; Kiraz, Alper; PhD Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; N/A; 22542
    We characterized room-temperature fluorescence properties of single terrylene molecules embedded in anthracene thin films that were prepared by spin-coating on glass substrates. Our results show that terrylene molecules embedded in anthracene matrix are oriented nearly parallel to the substrate. Typical measured fluorescence lifetime of terrylene was 3.6 ns and photon count rate at saturation was 750 kHz. Our analyses of 104 molecules indicate that we can detect on average 1.6 x 10(6) photons from a single terrylene molecule before it photobleaches. These results make terrylene-anthracene a promising guest-host system for room temperature single molecule experiments.
  • Placeholder
    PublicationMetadata only
    Prolonged Raman lasing in size-stabilized salt-water microdroplets on a superhydrophobic surface
    (Optical Soc Amer, 2010) N/A; N/A; N/A; N/A; N/A; Department of Physics; Department of Physics; Karadağ, Yasin; Gündoğan, Mustafa; Yüce, Mehdi Yavuz; Çankaya, Hüseyin; Sennaroğlu, Alphan; Kiraz, Alper; PhD Student; Master Student; PhD Student; Researcher; Faculty Member; Faculty Member; Department of Physics; Graduate School of Sciences and 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; N/A; N/A; N/A; N/A; 23851; 22542
    We demonstrate prolonged Raman lasing from individual salt-water microdroplets with 10-20 mu m diameters located on a superhydrophobic surface. The mechanism is based on the absorption heating of a 1064 nm cw IR laser and the resonant heating of a 532 nm pulsed, pump laser. A clear hysteresis is observed in the lasing intensity as the droplet size is photothermally tuned by the IR laser, indicating a self-stabilization mechanism due to the resonant absorption of the pump laser. Using this mechanism, Raman lasing near 650 nm is sustained for up to 25 min, similar to 1000 times longer than lasing durations reported in previous studies.
  • Placeholder
    PublicationMetadata only
    Tuning the surface hydrophobicity of polymer/nanoparticle composite films in the wenzel regime by composition
    (Amer Chemical Soc, 2005) Menzel, F.; N/A; Department of Chemistry; Yüce, Mehdi Yavuz; Demirel, Adem Levent; PhD Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 6568
    Surface hydrophobicity of composite films containing polymer and nanoparticles has been studied as a function of composition. We show that the hydrophobicity can be tuned by adjusting the amount of particles in the two-component system. A sharp transition from a polymer-rich surface to a nanoparticles-rich surface was observed with increasing mass fraction of particles in spin-coated thin films. Water drops on the films did not slide down even at tilt angles of 90 degrees. Contact angle hysteresis increased with the mass fraction of particles indicating that the surface roughness increased as the surfaces remained in the Wenzel regime. Contact angle hysteresis data were quantitatively consistent with predictions of a recent theory.
  • Placeholder
    PublicationMetadata only
    Prolonged raman lasing in the size-stabilized salt-water microdroplets on a superhydrophobic surface
    (Optical Society of America, 2010) Department of Physics; N/A; Department of Physics; N/A; N/A; N/A; Sennaroğlu, Alphan; Çankaya, Hüseyin; Kiraz, Alper; Karadağ, Yasin; Gündoğan, Mustafa; Yüce, Mehdi Yavuz; Faculty Member; Researcher; Faculty Member; PhD Student; Master Student; PhD Student; Department of Physics; College of Sciences; Graduate School of Sciences and Engineering; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 23851; N/A; 22542; N/A; N/A; N/A
    We show prolonged Raman lasing from individual salt-water microdroplets located on a superhydrophobic surface using a self-stabilization mechanism based on the absorption heating of an infrared laser and resonant heating of a green laser.
  • Placeholder
    PublicationMetadata only
    Single molecule tracking with Kalman filtering
    (Optical Society of America, 2011) N/A; Department of Physics; Department of Physics; Department of Electrical and Electronics Engineering; N/A; Kiraz, Alper; Jonas, Alexandr; Erdoğan, Alper Tunga; Yüce, Mehdi Yavuz; Faculty Member; Other; Faculty Member; PhD Student; Department of Physics; Department of Electrical and Electronics Engineering; College of Sciences; College of Sciences; College of Engineering; Graduate School of Sciences and Engineering; 22542; N/A; 41624; N/A
    Kalman filtering has been applied to single molecule tracking. Position and velocity of the molecules constitute the state of the process. They are measured from single frame data by maximum likelihood estimation.
  • Placeholder
    PublicationMetadata only
    Velocity estimation of mobile single molecules for improved position accuracy
    (IEEE, 2011) Department of Electrical and Electronics Engineering; Department of Physics; N/A; Erdoğan, Alper Tunga; Kiraz, Alper; Yüce, Mehdi Yavuz; Faculty Member; Faculty Member; PhD Student; Department of Electrical and Electronics Engineering; Department of Physics; College of Engineering; College of Sciences; Graduate School of Sciences and Engineering; 41624; 22542; N/A
    Imaging of single molecules has been modeled as a non-homogenous Poisson process. Model parameters including molecule's velocity are estimated from individual frames with maximum likelihood estimation. Velocity information is shown to improve the position accuracy. © 2011 IEEE.
  • Thumbnail Image
    PublicationOpen Access
    Video-based tracking of single molecules exhibiting directed in-frame motion
    (Cambridge University Press (CUP), 2012) Department of Physics; Yüce, Mehdi Yavuz; Jonas, Alexandr; Kiraz, Alper; Erdoğan, Alper Tunga; Faculty Member; Department of Physics; College of Sciences; N/A; N/A; 22542; 41624
    Trajectories of individual molecules moving within complex environments such as cell cytoplasm and membranes or semiflexible polymer networks provide invaluable information on the organization and dynamics of these systems. However, when such trajectories are obtained from a sequence of microscopy images, they can be distorted due to the fact that the tracked molecule exhibits appreciable directed motion during the single-frame acquisition. We propose a new model of image formation for mobile molecules that takes the linear in-frame motion into account and develop an algorithm based on the maximum likelihood approach for retrieving the position and velocity of the molecules from single-frame data. The position and velocity information obtained from individual frames are further fed into a Kalman filter for interframe tracking of molecules that allows prediction of the trajectory of the molecule and further improves the precision of the position and velocity estimates. We evaluate the performance of our algorithm by calculations of the Cramer-Rao Lower Bound, simulations, and model experiments with a piezo-stage.We demonstrate tracking of molecules moving as fast as 7 pixels/frame ~12.6 mm/s! within a mean error of 0.42 pixel ~37.43 nm!.
  • Thumbnail Image
    PublicationOpen Access
    Single glycerol/water microdroplets standing on a superhydrophobic surface: optical microcavities promising original applications
    (Society of Photo-optical Instrumentation Engineers (SPIE), 2007) Department of Physics; Department of Chemistry; Kiraz, Alper; Dündar, Mehmet Ali; Demirel, Adem Levent; Doğanay, Sultan; Kurt, Adnan; Sennaroğlu, Alphan; Yüce, Mehdi Yavuz; Faculty Member; Faculty Member; Undergraduate Student; Teaching Faculty; Faculty Member; Department of Physics; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; 22542; N/A; 6568; N/A; 194455; 23851; N/A
    Glycerol/water microdroplets take almost spherical shapes when standing on a superhydrophobic surface. Hence they are suitable to function as optical microcavities. Using Rhodamine B doped water microdroplets, large spectral tunability of the whispering gallery modes (WGMs) (>5 nm) was observed. Tunability was achieved by evaporation/condensation in a current controlled mini humidity chamber. Experiments revealed a mechanism stabilizing the volume of these microdroplets with femtoliter resolution. The mechanism relied on the interplay between the condensation rate that was kept constant and the size dependent laser induced heating. The radii of individual water microdroplets (>5 mu m) stayed within a few nanometers during long time periods (several minutes). By blocking the laser excitation for 500 msec, the stable volume of individual microdroplets were changed stepwise. Laser emission was also observed from Rhodamine B doped glycerol/water microdroplets using a pulsed, frequency-doubled Nd:YAG laser (lambda=532 nm) as the excitation source. The observed largely tunable WGMs and laser emission can pave way for novel applications in optical communication systems. Besides due to the sensitivity of the WGMs to the size and shape of the microdroplets, the results can find applications in characterizing superhydrophobic surfaces and investigating liquid-solid surfaces.