98,115 research outputs found
Joshua Davis: Author of Spare Parts
No full textCitation: K-State First (2016). Joshua Davis: Author of Spare Parts [Flier]. Manhattan, Kansas: K-State First.Flyer advertising Joshua Davis's author talk at Kansas State University
Very strong azimuthal anchoring of nematic liquid crystals on uv-aligned polyimide layers
No full textThe azimuthal anchoring energy of the nematic liquid crystal 4-n-pentyl-4 '-cyanobiphenyl (5CB) on a uv-aligned polyimide substrate with in-plane order parameter S '=0.2 is measured. The measurements are performed at temperature T=24 degrees C using simultaneously a high accuracy reflectometric method and a high accuracy transmitted light method. With both the methods, we observe an apparent surface director rotation opposite to the orienting torque that would correspond to a negative extrapolation length. It is shown that this unusual behavior is due to the relatively high birefringence of the uv-aligned polyimide layers. Taking into account for this birefringence, we find a small but positive extrapolation length. The experimental results are interpreted in terms of a simple mesoscopic model where the nematic molecules are assumed to be rigidly attached on the polymer surface and the measured extrapolation length is entirely due to the order parameter variation in a thin interfacial layer where the nematic order parameter passes from the surface value to the bulk value within a few nematic correlation lengths. Assuming the surface order parameter is S-0=0.37, the correlation length of the nematic liquid crystal is estimated to be xi(c)'=2.4 +/- 1 nm. The corresponding thermodynamic extrapolation length is d(e)=2.8 +/- 1.2 nm that corresponds to a very strong azimuthal anchoring
Steven Johnson Author Talk Poster
No full textK-State Book NetworkA poster advertising an author talk by Steven Johnson at Kansas State University on September 3, 2014. Steven Johnson's book "The Ghost Map" was the 2014-2015 common book
Controlled Ge nanowires growth on patterned Au catalyst substrate
No full textOne-dimensional semiconductor nanostructures have attracted much attention because of their potential applications in the design of novel electronic, photonic, and sensing devices. Due to their high mobility of electrons and holes, Ge nanowires are particularly attractive for high-speed field-effect transistors. Moreover, Ge nanowires are potentially useful for building quantum bits because of a long decoherence time due to a predominance of spin-zero nuclei and the advantage of a large excitonic Bohr radius (24.3 nm) which allows the quantum confinement to be observed for relatively large structures and at high temperatures. To realize these applications on a large scale, one of the key challenges is to develop a convenient and parallel method to align bottom-up nanowires into complex patterns or structures. Recently, a "pick and place" method is most widely used for integrating nanowires. However, these processes lack control in precision, repeatability, and easily induce contamination and defects in the wires. It is expected to selectively grow nanowires directly onto desired areas of the substrate and in situ fabricate the nanowire devices. In the VLS (vapor-liquid-solid) CVD process, gold catalysts initiate and guide the growth of nanowires. Hence, precise control the location of nanowires relies on the capability to control the location of Au clusters. In this paper, we demonstrate the well location-controllable Ge nanowires on SiO/sub 2/ substrate by combining top-down and bottom-up methods
Influence of the crystal orientation of substrate on low temperature synthesis of silicon nanowires from Si2H6
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