Toward efficient light diffraction and intensity variations by using wide bandwidth surface acoustic wave

Lee, Young Ok,Chen, Fu,Lee, Kee Keun Institute of Pure and Applied Physics 2016 Japanese Journal of Applied Physics Vol.55 No.6

<P>We have developed acoustic-optic (AO) based display units for implementing a handheld hologram display by modulating light deflection through wide bandwidth surface acoustic wave (SAW). The developed AO device consists of a metal layer, a ZnS waveguide layer, SAW inter digital transducers (IDTs), and a screen for display. When RF power with a particular resonant frequency was applied to IDTs, SAW was radiated and interfered with confined beam propagating along ZnS waveguide layer. The AO interacted beam was deflected laterally toward a certain direction depending on Bragg diffraction condition, exited out of the waveguide layer and then directed to the viewing screen placed at a certain distance from the device to form a single pixel. The deflected angles was adjusted by modulating the center frequency of the SAW IDT (SAW grating), the RF power of SAW, and the angles between propagating light beam path along waveguide and radiating SAW. The diffraction efficiency was also characterized in terms of waveguide thickness, SAW RF input power, and aperture length. Coupling of mode (COM) modeling was fulfilled to find optimal device parameters prior to fabrication. All the parameters affecting the deflection angle and efficiency to form a pixel for a three-dimensional (3D) hologram image were characterized and then discussed. (C) 2016 The Japan Society of Applied Physics</P>

Electro-optic characteristics and areal selective dimming method for a new highly efficient mercury-free flat fluorescent lamp (MFFL)

Jung, Jae-Chul,Lee, Ju Kwang,Seo, In Woo,Oh, Byung Joo,Whang, Ki-Woong Institute of Physics [etc.] 2009 Journal of Physics. D, Applied Physics Vol.42 No.12

<P>A highly efficient mercury-free flat fluorescent lamp (MFFL) with dielectric barrier Xe gas discharge was developed for a LCD-TV backlight source. The unit cell of the lamp has a simple structure with two main electrodes running parallel to each other and an auxiliary electrode. The adoption of the auxiliary electrode resulted in a wide, stable operating voltage margin, high luminance and efficiency. The 4 inch diagonal size lamp showed a luminous efficacy of 44 lm W<SUP>−1</SUP> at a luminance of 3400 cd m<SUP>−2</SUP> with Ne–Xe(18%) gas mixture. We demonstrated that the 4 inch unit cell can be used to construct a 5 × 8 multi-structured lamp of 32 inch diagonal size for application in a large-sized LCD backlight source by a simple repeat of the unit cell. Despite the increase in size, the 32 inch lamp showed the same discharge voltage and margin of the 4 inch unit cell. Using the proposed MFFL with the auxiliary electrode as the data electrode and the subfield method, we developed a driving scheme for 2-bit areal selective dimming control of an <I>M</I> × <I>N</I> multi-cell lamp which can be operated using only one inverter.</P>

Effects of interlayer thickness and the substrate material on the adhesion properties of CrZrN coatings

Kim, Kyu-Sung,Kim, Hoe-Kun,La, Joung-Hyun,Lee, Sang-Yul Institute of Pure and Applied Physics 2016 Japanese Journal of Applied Physics Vol.55 No.1

<P>To confirm the influence of the interlayer thickness and substrate material on adhesion properties, CrZrN coatings with various Cr interlayer thickness were deposited on AISI H13, high speed steel, and tungsten carbide using unbalanced magnetron sputtering. The adhesion strength showed maximum value at 300nm of the interlayer, but as the interlayer increased further to 450 nm, the adhesion strength decreased. The adhesion properties of the coatings were dependent upon not only interlayer thickness but also the substrate materials. The adhesion strength of the coating were measured 12, 32, 53N on the tungsten carbide, AISI H13 steel, high speed steel, respectively and three different failure modes such as buckling spallation, wedging spallation, and chipping were observed on each substrate. The difference in adhesion properties could be attributed to the difference in value of elastic strain to failure (H/E) among the CrZrN coating, the interlayer, and the substrates material. (C) 2016 The Japan Society of Applied Physics</P>

Crystal structure of Bi_4−<i>x</i>Ce_<i>x</i>Ti₃O₁₂(<i>x</i> = 0, 0.25, 0.5 and 0.75) studied by Raman spectroscopy and neutron powder diffraction

Ku Jeon, Min,Kim, Yong-Il,Nahm, Seung-Hoon,Ihl Woo, Seong Institute of Physics [etc.] 2006 Journal of Physics. D, Applied Physics Vol.39 No.23

<P>Structural refinement using both neutron powder diffraction data and Raman spectroscopy were carried out to determine the site preference of Ce atoms and structural changes in Bi<SUB>4−<I>x</I></SUB>Ce<SUB><I>x</I></SUB>Ti<SUB>3</SUB>O<SUB>12</SUB> (<I>x</I> = 0, 0.25, 0.5 and 0.75) compounds. In the Raman spectroscopic study, the peak at 65 cm<SUP>−1</SUP> of Bi<SUB>4</SUB>Ti<SUB>3</SUB>O<SUB>12</SUB> (BTO), assigned to the Bi–O bonds in the Bi<SUB>2</SUB>O<SUB>2</SUB> layers, did not shift or shifted to 63 cm<SUP>−1</SUP> after Ce incorporation. However, the peaks of BTO at 119 and 148 cm<SUP>−1</SUP>, assigned to the Bi–O bonds in the perovskite units, became diffusive and moved to higher frequencies of (121 and 150 cm<SUP>−1</SUP>), (123 and 152 cm<SUP>−1</SUP>) and (125 and 157 cm<SUP>−1</SUP>) when <I>x</I> was 0.25, 0.5 and 0.75, respectively. From the Raman spectroscopic study, the substitution sites of the Ce atoms were determined to be only the Bi sites in the perovskite units. The peaks originated from the TiO<SUB>6</SUB> octahedrons moved to higher frequencies and merged with the neighbouring peaks, indicating relaxation of distortion of TiO<SUB>6</SUB> octahedrons with increase in <I>x</I>. Structural refinement results showed that the <I>a</I>-axis lattice parameters decreased with increase in <I>x</I>, while the <I>b</I>-axis lattice parameters did not exhibit significant changes and the <I>c</I>-axis lattice parameters decreased. Decrease in orthorhombicity with increasing <I>x</I> showed the relaxation of structural distortion of TiO<SUB>6</SUB> octahedrons. Spontaneous polarization was calculated based on the refinement results, which decreased from 35.4 to 30.4, 27.5 and 16.5 ?C cm<SUP>−2</SUP> when <I>x</I> is 0, 0.25, 0.5 and 0.75, respectively.</P>

Calculations of the resonant response of carbon nanotubes to binding of DNA

Zheng, Meng,Eom, Kilho,Ke, Changhong Institute of Physics [etc.] 2009 Journal of Physics. D, Applied Physics Vol.42 No.14

<P>We theoretically study the dynamical response of carbon nanotubes (CNTs) to the binding of DNA in an aqueous environment by considering two major interactions in DNA helical binding to the CNT side surface: adhesion between DNA nucleobases and CNT surfaces and electrostatic interactions between negative charges on DNA backbones. The equilibrium DNA helical wrapping angle is obtained using the minimum potential energy method. Our results show that the preferred DNA wrapping angle in the equilibrium binding to CNT is dependent on both DNA length and DNA base. The equilibrium wrapping angle for a poly(dT) chain is larger than a comparable poly(dA) chain as a result of dT in a homopolymer chain having a higher effective binding energy to CNT than dA. Our results also interestingly reveal a sharp transition in the wrapping angle-DNA length profile for both homopolymers, implying that the equilibrium helical wrapping configuration does not exist for a certain range of wrapping angles. Furthermore, the resonant response of the DNA–CNT complex is analysed based on the variational method with a Hamiltonian which takes into account the CNT bending energy as well as DNA–CNT interactions. The closed-form analytical solution for predicting the resonant frequency of the DNA–CNT complex is presented. Our results show that the hydrodynamic loading on the oscillating CNT in aqueous environments has profound impacts on the resonance behaviour of DNA–CNT complexes. Our results suggest that detection of DNA molecules using CNT resonators based on DNA–CNT interactions through frequency measurements should be conducted in media with low hydrodynamic loading on CNTs. Our theoretical framework provides a fundamental principle for label-free detection using CNT resonators based on DNA–CNT interactions.</P>

PINGU: a vision for neutrino and particle physics at the South Pole

Aartsen, M G,Abraham, K,Ackermann, M,Adams, J,Aguilar, J A,Ahlers, M,Ahrens, M,Altmann, D,Andeen, K,Anderson, T,Ansseau, I,Anton, G,Archinger, M,Arguelles, C,Arlen, T C,Auffenberg, J,Axani, S,Bai, X,B Institute of Physics Publishing 2017 Journal of Physics. G, Nuclear and Particle Physic Vol.44 No.5

<P>The Precision IceCube Next Generation Upgrade (PINGU) is a proposed low-energy in-fill extension to the IceCube Neutrino Observatory. With detection technology modeled closely on the successful IceCube example, PINGU will provide a 6?Mton effective mass for neutrino detection with an energy threshold of a few GeV. With an unprecedented sample of over 60 000 atmospheric neutrinos per year in this energy range, PINGU will make highly competitive measurements of neutrino oscillation parameters in an energy range over an order of magnitude higher than long-baseline neutrino beam experiments. PINGU will measure the mixing parameters <img ALIGN='MIDDLE' ALT='${\theta }_{23}$' SRC='http://ej.iop.org/images/0954-3899/44/5/054006/jpgaa4973ieqn1.gif'/> and <img ALIGN='MIDDLE' ALT='${\rm{\Delta }}{m}_{32}^{2}$' SRC='http://ej.iop.org/images/0954-3899/44/5/054006/jpgaa4973ieqn2.gif'/>, including the octant of <img ALIGN='MIDDLE' ALT='${\theta }_{23}$' SRC='http://ej.iop.org/images/0954-3899/44/5/054006/jpgaa4973ieqn3.gif'/> for a wide range of values, and determine the neutrino mass ordering at <img ALIGN='MIDDLE' ALT='$3\sigma $' SRC='http://ej.iop.org/images/0954-3899/44/5/054006/jpgaa4973ieqn4.gif'/> median significance within five years of operation. PINGU’s high precision measurement of the rate of <img ALIGN='MIDDLE' ALT='${\nu }_{\tau }$' SRC='http://ej.iop.org/images/0954-3899/44/5/054006/jpgaa4973ieqn5.gif'/> appearance will provide essential tests of the unitarity of the 3?×?3 PMNS neutrino mixing matrix. PINGU will also improve the sensitivity of searches for low mass dark matter in the Sun, use neutrino tomography to directly probe the composition of the Earth’s core, and improve IceCube’s sensitivity to neutrinos from Galactic supernovae. Reoptimization of the PINGU design has permitted substantial reduction in both cost and logistical requirements while delivering performance nearly identical to configurations previously studied.</P>

Multiwalled-carbon nanotubes and polyaniline coating on electro-active paper for bending actuator

Yun, Sungryul,Kim, Jaehwan Institute of Physics [etc.] 2006 Journal of physics. D, applied physics Vol.39 No.12

<P>Multi-walled carbon nanotubes (MWNT) and polyaniline are coated on an electro-active paper (EAPap) to improve the performance of the bending actuator, and its performance is tested. EAPap actuators made with cellulose paper have merits in terms of large bending displacement, ultra-lightweight, dryness, low actuation voltage and power consumption, low cost and biodegradability. However, the force output of actuators is small and the actuation frequency is low. Thus, MWNT and emeraldine salt polyaniline (PANI) are coated on the EAPap material to improve the force and the actuation frequency. The MWNT and PANI solution is made by sonication, and the sonication time and the weight per cents of the MWNT and PANI are optimized to improve the hybrid actuator performance. The optimum condition is associated with conversion of the partial conductive state PANI into the emeraldine formed PANI by the chemical bonding between the MWNT and PANI. The performance improvement of the EAPap actuator coated with MWNT/PANI is investigated in terms of displacement, blocking force and efficiency. In the presence of an electric field (0.35 V µm<SUP>−1</SUP>) on the hybrid EAPap actuator, 250% of the output force, 160% of the resonance frequency and 50% of efficiency are improved.</P>

Underwater acoustic source localization using closely spaced hydrophone pairs

Sim, Min Seop,Choi, Bok-Kyoung,Kim, Byoung-Nam,Lee, Kyun Kyung Institute of Pure and Applied Physics 2016 Japanese Journal of Applied Physics Vol.55 No.7

<P>Underwater sound source position is determined using a line array. However, performance degradation occurs owing to a multipath environment, which generates incoherent signals. In this paper, a hydrophone array is proposed for underwater source position estimation robust to a multipath environment. The array is composed of three pairs of sensors placed on the same line. The source position is estimated by performing generalized cross-correlation (GCC). The proposed system is not affected by a multipath time delay because of the close distance between closely spaced sensors. The validity of the array is confirmed by simulation using acoustic signals synthesized by eigenrays. (C) 2016 The Japan Society of Applied Physics</P>

Nonthermal-plasma-mediated animal cell death

Kim, Wanil,Woo, Kyung-Chul,Kim, Gyoo-Cheon,Kim, Kyong-Tai Institute of Physics [etc.] 2011 Journal of Physics. D, Applied Physics Vol.44 No.1

<P>Animal cell death comprising necrosis and apoptosis occurred in a well-regulated manner upon specific stimuli. The physiological meanings and detailed molecular mechanisms of cell death have been continuously investigated over several decades. Necrotic cell death has typical morphological changes, such as cell swelling and cell lysis followed by DNA degradation, whereas apoptosis shows blebbing formation and regular DNA fragmentation. Cell death is usually adopted to terminate cancer cells <I>in vivo</I>. The current strategies against tumour are based on the induction of cell death by adopting various methods, including radiotherapy and chemotherapeutics. Among these, radiotherapy is the most frequently used treatment method, but it still has obvious limitations. Recent studies have suggested that the use of nonthermal air plasma can be a prominent method for inducing cancer cell death. Plasma-irradiated cells showed the loss of genomic integrity, mitochondrial dysfunction, plasma membrane damage, etc. Tumour elimination with plasma irradiation is an emerging concept in cancer therapy and can be accelerated by targeting certain tumour-specific proteins with gold nanoparticles. Here, some recent developments are described so that the mechanisms related to plasma-mediated cell death and its perspectives in cancer treatment can be understood.</P>

Controlled light emission from white organic light-emitting devices with a single blue-emitting host and multiple fluorescent dopants

Chin, Byung Doo,Kim, Jai Kyeong,Park, O Ok Institute of Physics [etc.] 2007 Journal of Physics. D, Applied Physics Vol.40 No.15

<P>In this work, we fabricated white organic light-emitting devices (WOLEDs) containing a layered light-emitting region composed of a single blue-emitting host and different fluorescent dopant materials. The effects of varying the dye-doping ratio and emitting layer thickness on the efficiency, lifetime, spectral voltage-dependence and white balance were investigated for devices with a blue/orange stacked layer structure. Addition of a blue host layer doped with a green-emitting dopant, to give a blue/green/orange emitter, resulted in a broadband white spectrum without the need for a charge-blocking interlayer. The composition of blue, green and orange dopants in the host and the thickness of each emitting layer were optimized, resulting in a device efficiency of 9–11 cd A<SUP>−1</SUP> even at a high brightness of 10 000 cd m<SUP>−2</SUP> (achieved at a bias voltage of less than 9 V) with an emission spectrum suitable for lighting applications.</P>