• Title/Summary/Keyword: PT Symmetry

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Effects of Isokinetic Strength Exercise of the Hemiparetic Knee Joint on Lower Extremity Sensorimotor and Gait Functions in Patients With Chronic Stroke: Open Kinetic Chain Versus Closed Kinetic Chain

  • An, Chang-man;Roh, Jung-suk
    • Physical Therapy Korea
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    • v.26 no.2
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    • pp.49-60
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    • 2019
  • Background: After stroke, in order to improve gait function, it is necessary to increase the muscle strength and to enhance the propriocetive function of the lower extremity. Objects: This study aimed to compare the effects of open kinetic chain (OKC) versus closed kinetic chain (CKC) isokinetic exercise of the hemiparetic knee using the isokinetic equipment on lower extremity sensorimotor function and gait ability in patients with chronic stroke. Methods: Thirty participants with chronic hemiplegia (> 6 months post-stroke) were randomly divided into 2 equal groups: CKC group and OKC group. Patients from both groups attended conventional physiotherapy sessions 3 times a week for 6 weeks. Additionally, subjects from the CKC group performed isokinetic exercise using the CKC attachment, while those from the OKC group performed isokinetic exercise using the OKC attachment. The isokinetic knee and ankle muscles strength, position sense of the knee joint, and spatiotemporal gait parameters were measured before and after interventions. Results: The knee muscles peak torque/body weight (PT/BW) and hamstring/quadriceps (H/Q) ratio significantly increased in both groups (p<.01). In particular, ankle plantarflexors PT/BW, position sense of the knee, gait velocity, and spatial gait symmetry significantly improved in the CKC group (p<.01, p<.05, p<.01, and p<.01, respectively). Conclusion: CKC isokinetic exercise can be an effective therapeutic intervention for the improvement of sensorimotor function of the lower extremity and gait functions, such as gait velocity and symmetry. CKC position in isokinetic strength training is effective to improve functional ability in patients with chronic stroke.

Micro-Macro Domain Switching and Thermoelastic Martensitic Transformation in $PbZrO_3$-doped $Pb(Ni_{1/3}Nb_{2/3})O_3-PbTiO_3$ System ($PbZrO_3$가 첨가된 $Pb(Ni_{1/3}Nb_{2/3})O_3-PbTiO_3$ 계의 미소-거시 분역 반전과 열탄성 마르텐사이트 변태)

  • 윤만순;장현명
    • Journal of the Korean Ceramic Society
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    • v.32 no.9
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    • pp.967-976
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    • 1995
  • The possiblity of the existence of a spontaneous relaxor-normal ferroelectric transition was proposed and examined using 1~5 mol% PbZrO3-doped Pb(Ni1/3Nb2/3)O3-PbTiO3 (PNN-PT) systems having tetragonal symmetry at rom temperature. On cooling, the system with 60mol% Pb(Ni1/3Nb2/3)O3 underwent a spontaneous transition from a relaxor to a normal ferroelectric state. A microscopic examination demonstrates that the relaxornormal ferroelectric transition corresponds to a micro-macro domain switching accompanied with thermoelastic martensitic transformation. The long-range macrodomains below the transition temperature were characterized by twinlike 90$^{\circ}$macrodomains with tetragonal symmetry. The relaxor-normal ferroelectric transition was further correlated with the rhombohedral-tetragonal first-order structural transition.

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Characterization of GaN epitaxial layer grown on nano-patterned Si(111) substrate using Pt metal-mask (Pt 금속마스크를 이용하여 제작한 나노패턴 Si(111) 기판위에 성장한 GaN 박막 특성)

  • Kim, Jong-Ock;Lim, Kee-Young
    • Journal of the Microelectronics and Packaging Society
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    • v.21 no.3
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    • pp.67-71
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    • 2014
  • An attempt to grow high quality GaN on silicon substrate using metal organic chemical vapor deposition (MOCVD), herein GaN epitaxial layers were grown on various Si(111) substrates. Thin Platinum layer was deposited on Si(111) substrate using sputtering, followed by thermal annealing to form Pt nano-clusters which act as masking layer during dry-etched with inductively coupled plasma-reactive ion etching to generate nano-patterned Si(111) substrate. In addition, micro-patterned Si(111) substrate with circle shape was also fabricated by using conventional photo-lithography technique. GaN epitaxial layers were subsequently grown on micro-, nano-patterned and conventional Si (111) substrate under identical growth conditions for comparison. The GaN layer grown on nano-patterned Si (111) substrate shows the lowest crack density with mirror-like surface morphology. The FWHM values of XRD rocking curve measured from symmetry (002) and asymmetry (102) planes are 576 arcsec and 828 arcsec, respectively. To corroborate an enhancement of the growth quality, the FWHM value achieved from the photoluminescence spectra also shows the lowest value (46.5 meV) as compare to other grown samples.

Crystal Structure of cis-(Malonato)[(4R,5R)-4,5-bis(Aminomethyl)-2-Isopropyl-1,3-Dioxolane]Platinum(II), A Potent Anticancer Agent

  • Cho, Sang-Woo;Yongkee Cho;Kim, Dai-Kee;Wanchul Shin
    • Korean Journal of Crystallography
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    • v.11 no.1
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    • pp.22-27
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    • 2000
  • The structure of cis-(malonato)[(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]platinum(II) with a potent anticancer activity has been determined by the X-ray crystallographic method. Crystal data are as follows: Pt(C/sub 11/H/sub 20/N₂O/sub 6/), M/sub 4/=471.38, monoclinic, P2₁, a=7.112(1), b=33.615(3), c=7.135(1)Å, β=116.80(1)°, V=1522.6(3)Å, and Z=4. The two independent molecules with very similar structures are approximately related by pseudo two-fold screw axis symmetry, which makes the monolinic cell look like the orthorhombic cell with one molecule in the asymmetric unit and space group C222₁. The crystal packing mode is similar to that of the analogue with the dimethyl substituents instead of the isopropyl group. The Pt atom is coordinate to two O and two N atoms in a square planar structure. The six-membered chelate ring in the leaving ligand assumes a conformation intermediate between the half chair and the boat forms. The seven-membered ring in the carrier ligand assumes a twist-chair conformation and the oxolane ring assumes an envelope conformation. Crystal packing consists of the extensive hydrogen-bonding network in the two-dimensional molecular layers and weak van der Waals interactions between these layers.

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Effect of Coordination Environment on the Photophysical Properties of Luminescent Europium(III) Complexes

  • Baek, Nam-Seob;Kim, Yong-Hee;Lee, Dong-Hyun;Seo, Kang-Deuk;Kim, Hwan-Kyu
    • Bulletin of the Korean Chemical Society
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    • v.30 no.7
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    • pp.1553-1558
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    • 2009
  • A series of Eu(III) complexes with various neutral ligands (2,2’:6’,2"-terpyridine (T), diglyme (D), 1N-(2-dimethylamino) ethyl)-1N, 2N, 2N-trimethylethane-1,2-diamine (PT), di-(2-picolyl)-amine derivative (HT), and multidentate terpyridine derivative (DT)) were synthesized to investigate the effect of coordination environment on the sensitized luminescence of Eu(III) complexes. The nine coordination sites of the $Eu^{3+}$ ion are occupied by three bidentate carboxylate moieties and one neutral ligand. The highest emission intensity is obtained for $Eu^{3+}$- $[NA]_3$ (PT), due to the difference in energy transfer efficiency and symmetry of the first coordination sphere of $Eu^{3+}$ ion. But, the lowest emission intensity is obtained for $Eu^{3+}$-$[NA]_3$(T). Terpyridine may not play an important role antenna for photosensitizing $Eu^{3+}$ ion. It could be attributed to the weak spectral overlap integral J value between its phosphorescence band and $Eu^{3+}$ion absorption band. Therefore, different coordination environment of $Ln^{3+}$ ion play an important role in providing sensitization of lanthanide ion emission.

Non-Contact Sensing Method using PT Symmetric Circuit with Cross-Coupled NDR Circuits (크로스-결합구조의 부성 미분 저항 회로를 이용한 페리티-시간 대칭 구조의 비접촉 센서 구동 회로에 대한 연구)

  • Hong, Jong-Kyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.4
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    • pp.10-16
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    • 2021
  • This paper proposes a model that considers the parity-time symmetric structure as a state detection circuit for sensor applications using a stretchable inductor. In particular, to obtain a more practical computer simulation result, the stretchable inductor model was applied to this study model by referring to previously reported experimental results. The resistance component and phase component were controlled through the negative differential resistance circuit used in this study. In addition, the imbalance of the circuit caused by a change in the characteristics of the stretchable inductor could be compensated for using a negative differential resistance circuit. In particular, an analysis of the frequency characteristics of the sensor driving circuit of the parity-time symmetric structure proposed in this study confirmed that the Q-factor could be increased up to 20 times compared to the conventional resonant circuit.

Field Induced Phase Transition in $0.6Pb(Ni_{1/3}Nb_{2/3})O_3-0.31PbTiO_3-0.09PbZrO_3$ Relaxor Ferroelectrics ($0.6Pb(Ni_{1/3}Nb_{2/3})O_3-0.31PbTiO_3-0.09PbZrO_3$ 완화형 강유전체의 전계 유기 상전이 현상)

  • 윤만순;장현명;정회승;최병철
    • Journal of the Korean Ceramic Society
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    • v.34 no.6
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    • pp.620-628
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    • 1997
  • The possibility of the existence of a field-induced micro-macrodomain switching was proposed and examined using 9 mol % PbZrO3-doped 0.6Pb(Ni1/3Nb2/3)O3-PbTiO3 (PNN-PT) systems having rhombohedral symmetry at room temperature. the thermally depoled (freshly prepard) specimens prepared from the rhombohedral side of the system exhibited a relaxor behavior for the whole range of temperature examined (for T

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Two Possible Space Groups of Ttis(tekaethylammonium) [bis(trimetaphosphate $\kappa^3O, O^', O^{"}$)] Vanadate(3-),$[V(P_3O_9)_2](NC_8H_{20})3$ (Tris(tetraethylammnnium) [bis(trimetaphosphate $\kappa^3O, O^', O^{"}$)] Vamdate(3-),$[V(P_3O_9)_2](NC_8H_{20})_3$,의 두가지 가능한 공간군)

  • 서일환;이진호
    • Korean Journal of Crystallography
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    • v.5 no.1
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    • pp.1-6
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    • 1994
  • Two possible space groups of the comfound, VP6N3018C24H:60, are: P 1, a=14.022(1), b=12.644(2), c= 12.640(1)A, a=8038(1), B=102.12(1), r=102.16(1), V=2124.1A3, Z=2, μ=0.47cm-1, d=1.46g/cm3, R=0.083 for 3350 independent reflections with Fo>4o IFI, and C2/c, a=19.32(2), b=16.32(2), c=14.02(1)A, B=105.98(5), β=105.98(5), V=4248.2A3, Z=4 R=0.083 for 1590 independent reflections with Fo>4c IFoI . In the space group P T, there are two monlecules in a unit cell. Vanadium atoms in the two monlecules occupy the two different special positions such that the complete monlecules are accomplished by the two independent center of symmetry. Therefore two different half molecules of bis(trimetaphosphate)vanadate and three molecules of tetraethylammonium are the asymmetric unit in a unit cell. In the space group C2/c, however, the vanadium atom is located at a special position with centrosymmetry, and a two-fold symmetry axis passes through C2/c, N2 and C25 atoms. Therefore the asymmrtic unit in a unit cell consists of a half molecule of bis(trimetaphosphate)vanadate and one and a half molecules of tetraethylammonium. All the molecular conformations in both space groups are very similar: six oxygen atoms coordinated to a vanadium atom in the bi s(trimetaphosphate)vanadate molecule form an octahedron and the four carbon atoms bonded to a nitrogen atom in the tetraethylammonium molecule are disordered so that the eight carbon atoms around nitrogen atom exhibit an irregular dodecahedral form.

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