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Terahertz Phonon Modes of Highly Efficient Electro-optic Phenyltriene OH1 Crystals
Kim, Jongtaek,Lee, Seung-Heon,Lee, Seung-Chul,Jazbinsek, Mojca,Miyamoto, Katsuhiko,Omatsu, Takashige,Lee, Yoon Sup,Kwon, O-Pil American Chemical Society 2016 The Journal of Physical Chemistry Part C Vol.120 No.42
<P>Understanding the origin of the phonon modes of highly efficient electro-optic crystals is very important for designing materials and for optimizing their photonic applications. Here we investigate the origin of phonon modes in the 0.1-15 THz range of the benchmark electrooptic OH1 (2-(3-(4-hydroxystyry1)-5,5-dimethylcyclohex-2-enylidene)malononitrile) crystal, which is interesting due to its large electro-optic coefficient and high THz-wave generation efficiency. The phonon modes (and vibrational absorption properties) of OH1 crystals are evaluated theoretically by periodic density functional theory and also experimentally by THz absorption spectroscopy. The the oretical calculations are well-matched with experimental results. The THz absorption properties are highly anisotropic; the amplitude of the vibrational absorption is the largest along the polar c-axis compared to the other two crystallographic axes. For comparison, the vibrational absorption modes of the OH1 molecule in the gas phase are also calculated. The calculated vibrational absorption spectrum of OH1 crystalline powder appears similar to that of the OH1 molecule in the gas phase. However, the molecular vibrational motions in the crystalline state are coupled motions of vibrational motions in the gas phase. Interestingly, the vibrational mode of the torsion of the O-H bond with the largest absorption strength in the gas phase is in the crystal inhibited due to the crystal field effect. The origin of the intense phonon modes of OH1 crystals is mainly related to relatively strong distortions of the push pull pi-conjugated system including electron donor and acceptor groups.</P>
Jeong, Gyoung Hwa,Lee, Ilbok,Lee, Donghyun,Lee, Hea-Min,Baek, Seungmin,Kwon, O-Pil,Kumta, Prashant N,Yoon, Songhun,Kim, Sang-Wook IOP 2018 Nanotechnology Vol.29 No.19
<P>The fabrication of <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> nanorods embedded in graphene sheets and their application as electrochemical charge storage electrodes is reported. From the surfactant treatment of raw graphite, graphene was directly prepared and its nanocomposite with <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> nanorods distributed between graphene layers (<I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB>-G) was synthesized by a hydrothermal method. When applied as an anode in lithium-ion batteries, the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB>-G anode exhibits greatly improved charge and discharge capacities of 790 and 627 mAhаиаg<SUP>−1</SUP>, respectively, with unexpectedly high initial efficiency of 82%. The observed discharge capacity reflected that at least 3.7 mol of Li<SUP>+</SUP> is selectively accumulated within the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> phase (Li<SUB>x</SUB>CoV<SUB>3</SUB>O<SUB>8</SUB>, xа>а3.7), indicative of significantly improved Li<SUP>+</SUP> uptake when compared with aggregated <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> nanorods. Moreover, very distinct peak plateaus and greatly advanced cycling performance are observed, showing more improved Li<SUP>+</SUP> storage within the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> phase. As a supercapacitor electrode, moreover, our composite electrode exhibits very high peak pseudocapacitances of 2.71 Fаиаcm<SUP>−2</SUP> and 433.65 Fаиаg<SUP>−1</SUP> in the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> phase with extremely stable cycling performance. This remarkably enhanced performance in the individual electrochemical charge storage electrodes is attributed to the novel phase formation of <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB> and its optimized nanocomposite structure with graphene, which yield fast electrical conduction through graphene, easy accessibility of ions through the open multilayer nanosheet structure, and a relaxation space between the <I>β</I>-CoV<SUB>3</SUB>O<SUB>8</SUB>-G.</P>
Kwon, O-Pil,Kwon, Seong-Ji,Jazbinsek, Mojca,Brunner, Fabian D. J.,Seo, Jung-In,Hunziker, Christoph,Schneider, Arno,Yun, Hoseop,Lee, Yoon-Sup,Gü,nter, Peter WILEY-VCH Verlag 2008 Advanced functional materials Vol.18 No.20
<P>We investigate a configurationally locked polyene (CLP) crystal 2-(3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-enylidene)malononitrile (OH1) containing a phenolic electron donor, which also acts as a hydrogen bond donor. The OH1 crystals with orthorhombic space group Pna2<SUB>1</SUB> (point group mm2) exhibit large second-order nonlinear optical figures of merit, high thermal stability and very favorable crystal growth characteristics. Higher solubility in methanol and a larger temperature difference between the melting temperature and the decomposition temperature of OH1 compared to analogous CLP crystals, are of advantage for solution and melt crystal growth, respectively. Acentric bulk OH1 crystals of large sizes with side lengths of up to 1 cm with excellent optical quality have been successfully grown from methanol solution. The microscopic and macroscopic nonlinearities of the OH1 crystals are investigated theoretically and experimentally. The OH1 crystals exhibit a large macroscopic nonlinearity with four times larger powder second harmonic generation efficiency than that of analogous CLP crystals containing dimethylamino electron donor. A very high potential of OH1 crystals for broadband THz wave emitters in the full frequency range of 0.1–3 THz by optical rectification of 160 fs pulses has been demonstrated.</P> <B>Graphic Abstract</B> <P>Configurationally locked polyene OH1 crystals containing a phenolic electron donor exhibit large second-order nonlinear optical figures of merit, high thermal stability, and very favorable crystal-growth characteristics. A very high potential of OH1 crystals for broadband THz wave emitters in the full frequency range of 0.1–3 THz by optical rectification of 160 fs pulses has been demonstrated. <img src='wiley_img/1616301X-2008-18-20-ADFM200800633-content.gif' alt='wiley_img/1616301X-2008-18-20-ADFM200800633-content'> </P>
( Pil Young Jung ),( Byungchul Yu ),( Chan-yong Park ),( Sung Wook Chang ),( O Hyun Kim ),( Maru Kim ),( Junsik Kwon ),( Gil Jae Lee ) 대한외상학회 2020 大韓外傷學會誌 Vol.33 No.1
Purpose: Despite recent developments in the management of trauma patients in South Korea, a standardized system and guideline for trauma treatment are absent. Methods: Five guidelines were assessed using the Appraisal of Guidelines for Research and Evaluation II instrument. Results: Restrictive volume replacement must be used for patients experiencing shock from trauma until hemostasis is achieved (1B). The target systolic pressure for fluid resuscitation should be 80-90 mmHg in hypovolemic shock patients (1C). For patients with head trauma, the target pressure for fluid resuscitation should be 100-110 mmHg (2C). Isotonic crystalloid fluid is recommended for initially treating traumatic hypovolemic shock patients (1A). Hypothermia should be prevented in patients with severe trauma, and if hypothermia occurs, the body temperature should be increased without delay (1B). Acidemia must be corrected with an appropriate means of treatment for hypovolemic trauma patients (1B). When a large amount of transfusion is required for trauma patients in hypovolemic shock, a massive transfusion protocol (MTP) should be used (1B). The decision to implement MTP should be made based on hemodynamic status and initial responses to fluid resuscitation, not only the patient’s initial condition (1B). The ratio of plasma to red blood cell concentration should be at least 1:2 for trauma patients requiring massive transfusion (1B). When a trauma patient is in life-threatening hypovolemic shock, vasopressors can be administered in addition to fluids and blood products (1B). Early administration of tranexamic acid is recommended in trauma patients who are actively bleeding or at high risk of hemorrhage (1B). For hypovolemic patients with coagulopathy non-responsive to primary therapy, the use of fibrinogen concentrate, cryoprecipitate, or recombinant factor VIIa can be considered (2C). Conclusions: This research presents Korea's first clinical practice guideline for patients with traumatic shock. This guideline will be revised with updated research every 5 years.