Publications by authors named "Hong Young Chang"

Article Synopsis
  • The study investigates the harmful effects of pulsed plasma on plant leaf tissues, using Arabidopsis thaliana as a model organism.
  • Short exposure (just a few seconds) to a nanosecond-pulsed plasma jet leads to cell death in both young (cotyledon) and mature (adult) leaves, primarily due to the accumulation of reactive oxygen species (ROS) and direct damage to the epidermis.
  • Similar plasma treatment in other plants like Solanum esculentum and Nicotiana benthamiana also resulted in localized cell death, suggesting that atmospheric plasma induces oxidative stress in photosynthetic tissues, contributing to cell death.
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This paper proposes a new method for cutoff probe using a nanosecond impulse generator and an oscilloscope, instead of a network analyzer. The nanosecond impulse generator supplies a radiating signal of broadband frequency spectrum simultaneously without frequency sweeping, while frequency sweeping method is used by a network analyzer in a previous method. The transmission spectrum (S21) was obtained through a Fourier analysis of the transmitted impulse signal detected by the oscilloscope and was used to measure the electron density.

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A low temperature, high yield hydrothermal route has been discovered for the phase-pure synthesis of the multiferroic BaMF(4) (M = Mg, Mn, Co, Ni, and Zn) family. The synthesis involves the use of CF(3)COOH instead of HF in an aqueous medium and, under the correct conditions, produces pure and polycrystalline BaMF(4). In addition to the synthetic description, second-harmonic generation, thermogravimetric, and differential scanning calorimetry data are presented.

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A new noncentrosymmetric polar ternary tellurium(IV) oxide phosphate, Te(2)O(PO(4))(2), has been synthesized by a standard solid-state reaction, and the structure was determined by single crystal X-ray diffraction. The material shows a three-dimensional framework structure that is composed of slightly distorted TeO(5) square pyramids and PO(4) tetrahedra. Within the framework three-, four-, and seven-membered ring channels are observed along the [100] direction.

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A new organically templated noncentrosymmetric polar zinc chloride, [N(CH(3))(4)]ZnCl(3), has been synthesized hydrothermally, and the structure was determined by single crystal X-ray diffraction. The reported material exhibits a unidimensional crystal structure consisting of chains of anionic ZnCl(4) tetrahedra that are separated by [N(CH(3))(4)](+) cations. Second-harmonic generation (SHG) measurement on the noncentrosymmetric [N(CH(3))(4)]ZnCl(3), using 1064 nm radiation, indicate the material has a SHG efficiency of approximately 15 x alpha-SiO(2).

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We have synthesized a series of new alkali-metal or Tl(+) titanium iodates, A(2)Ti(IO(3))(6) (A = Li, Na, K, Rb, Cs, Tl). Interestingly the Li and Na phases are noncentrosymmetric (NCS) and polar, whereas the K, Rb, Cs, and Tl analogues are centrosymmetric (CS) and nonpolar. We are able to explain the change from NCS polar to CS nonpolar using cation-size arguments, coordination requirements, and bond valence concepts.

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A new polar noncentrosymmetric material, Li(2)Ti(IO(3))(6), has been synthesized and characterized. The material is built up from a TiO(6) octahedron that is linked to six IO(3) polyhedra. These polyhedral groups are separated by Li(+) cations.

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Two new Sn2+-W6+-oxides, Sn2WO5 and Sn3WO6, have been synthesized hydrothermally, and their structures have been determined by single-crystal X-ray diffraction methods. Both materials exhibit layered structural topologies consisting of two edge-shared WO6 octahedra connected to SnO3 and SnO4 polyhedra. Both the W6+ and Sn2+ cations are in locally asymmetric coordination environments attributable to second-order Jahn-Teller effects.

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