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김재훈,박일현,최이준 國立金烏工科大學校附設生産技術硏究所 1990 産業技術開發硏究 Vol.6 No.-
Two series of sequentially orderd and randomed aromatic copolyesters were prepared from various naphthalendiol isomer, α,ωbis(dicarboxyphenoxy) alkanes and hydroxybonzoic acid. Higer thermal transition temperaturers and crystallinity appeared in the ordered ones than in the random ones. All copolyesters formed thermotropic mesophase. Annealing increaseed copolymer molecular weights and also the degree of crystallinity.
Kim, Hee-Jin,Sohn, Kwang-Min,Shy, Michael E.,Krajewski, Karen M.,Hwang, Miok,Park, June-Hee,Jang, Sue-Yon,Won, Hong-Hee,Choi, Byung-Ok,Hong, Sung Hwa,Kim, Byoung-Joon,Suh, Yeon-Lim,Ki, Chang-Seok,Lee, Elsevier 2007 American journal of human genetics Vol.81 No.3
<P>We have identified missense mutations at conserved amino acids in the <I>PRPS1</I> gene on Xq22.3 in two families with a syndromic form of inherited peripheral neuropathy, one of Asian and one of European descent. The disease is inherited in an X-linked recessive manner, and the affected male patients invariably develop sensorineural hearing loss of prelingual type followed by gating disturbance and visual loss. The family of European descent was reported in 1967 as having Rosenberg-Chutorian syndrome, and recently a Korean family with the same symptom triad was identified with a novel disease locus CMTX5 on the chromosome band Xq21.32-q24. <I>PRPS1</I> (phosphoribosyl pyrophosphate synthetase 1) is an isoform of the <I>PRPS</I> gene family and is ubiquitously expressed in human tissues, including cochlea. The enzyme mediates the biochemical step critical for purine metabolism and nucleotide biosynthesis. The mutations identified were E43D, in patients with Rosenberg-Chutorian syndrome, and M115T, in the Korean patients with CMTX5. We also showed decreased enzyme activity in patients with M115T. <I>PRPS1</I> is the first CMT gene that encodes a metabolic enzyme, shedding a new light on the understanding of peripheral nerve-specific metabolism and also suggesting the potential of <I>PRPS1</I> as a target for drugs in prevention and treatment of peripheral neuropathy by antimetabolite therapy.</P>
Choi, E Ryoung,Park, Sung-Ji,Choe, Yeon Hyeon,Ryu, Dong Ryeol,Chang, Sung-A,Choi, Jin-Oh,Lee, Sang-Chol,Park, Seung Woo,Kim, Byoung Joon,Kim, Duk-Kyung,Oh, Jae K BioMed Central 2010 Journal of cardiovascular magnetic resonance Vol.12 No.-
<P><B>Background</B></P><P>Miyoshi myopathy (MM) is an autosomal recessive distal myopathy characterized by early adult onset. Cardiomyopathy is a major clinical manifestation in other muscular dystrophies and an important prognostic factor. Although dysferlin is highly expressed in cardiac muscle, the effect of dysferlin deficiency in cardiac muscle has not been studied. We hypothesized that early myocardial dysfunction could be detected by 2D strain echocardiography and late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR).</P><P><B>Method</B></P><P>Five consecutive MM patients (3 male) in whom we detected the DYSF gene mutation and age-matched healthy control subjects were included. None of the patients had history of cardiac disease or signs and symptoms of overt heart failure. Patients were studied using 2D strain echocardiography and CMR, with 2D strain being obtained using the Automated Function Imaging technique.</P><P><B>Results</B></P><P>All patients had preserved left ventricular systolic function. However, segmental Peak Systolic Longitudinal Strain (PSLS) was decreased in 3 patients. Global PSLS was significantly lower in patients with MM than in control subjects (p = 0.005). Basal anterior septum, basal inferior septum, mid anterior, and mid inferior septum PSLS were significantly lower in patients with MM than in control subjects (P < 0.0001, < 0.0001, 0.038 and 0.003, respectively). Four patients showed fibrosis by LGE. The reduced PSLS lesion detected by 2D strain tended to be in the same area as that which showed fibrosis by LGE.</P><P><B>Conclusions</B></P><P>Patients with MM showed subclinical involvement of the heart. 2D strain and LGE are sensitive methods for detecting myocardial dysfunction prior to the development of cardiovascular symptoms. The prognostic significance of these findings warrants further longitudinal follow-up.</P>
Pseudo-rodlike molecules with hockey-stick-shaped mesogen
Choi, E-Joon,Park, Kyung-Min,Kim, Dae-Yoon,Jeong, Kwang-Un,Lee, Ji-Hoon Taylor Francis 2016 Liquid crystals Vol.43 No.11
<P>Hockey-stick-shaped molecules were newly synthesised to obtain pseudo-rodlike molecules. The designed molecules consist of a polar terminal ring (i.e. 2,3,4-, 2,4,6- or 3,4,5-trifluorophenyl group), a rigid middle block (i.e. four rings with aligned ester linkages) and a flexible terminal chain (i.e. dodecyloxy group). We found that the compounds with 2,3,4- and 3,4,5-trifluorophenyl groups formed a smectic A mesophase with head-to-head bi-layer building blocks, whereas the compound with 2,4,6-trifluorophenyl group formed a nematic mesophase. This might be concerned with the behaviour of pseudo-rodlike molecules [GRAPHICS] .</P>
The locally polar smectic A phase in V-shaped molecules
Choi, E-Joon,Kim, Eun-Chol,Park, Sang-Byung,Zin, Wang-Cheol,Lee, You-Jin,Kim, Jae-Hoon The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.47
<P>For focusing on the polar smectic A phase derived from the V-shaped molecules, bent-core molecules with an acute-angled central core (Ar = 1,2-phenylene or 2,3-naphthylene) and a lateral halogen substituent (X = F or Cl) were synthesized. Their mesomorphic properties were investigated by DSC, polarizing microscopy, X-ray and electro-optical measurements. We found that a compound with Ar/X = 2,3-naphthylene/Cl forms the conventional smectic A phase, whereas three compounds with Ar/X = 1,2-phenylene/F, 1,2-phenylene/Cl and 2,3-naphthylene/F form the locally polar smectic A phase (SmAP<SUB>R</SUB>). According to our knowledge this is the first obvious experimental evidence that V-shaped molecules with an acute-subtended angled central core, in cooperation with a lateral halogen substituent, can form the SmAP<SUB>R</SUB>.</P> <P>Graphic Abstract</P><P>The first clear experimental evidence that V-shaped molecules with an acute-subtended angled central core (Ar), in cooperation with a lateral halogen substituent (X), can form the locally polar smectic A phase (SmAP<SUB>R</SUB>) is described. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm35530b'> </P>
Choi, E-Joon,Cui, Xin,Ohk, Chang-Woo,Zin, Wang-Cheol,Lee, Ji-Hoon,Lim, Tong-Kun,Jang, Won-Gun Royal Society of Chemistry 2010 Journal of materials chemistry Vol.20 No.18
<P>A new bent-shaped molecule which consists of an acute-angled central core and all-ester linking groups has been prepared: 2,3-naphthylene bis[4-(4-n-dodecyloxybenzoyloxy)benzoate]. Its mesomorphic properties have been investigated by DSC, polarizing microscopy, and X-ray diffraction measurements. Moreover, we have carried out detailed electro-optical investigations including birefringence, switching current response, IR dichroism, and second-harmonic generation (SHG) measurements. On the basis of the experimental data a plausible model for the mesophase alignments has been proposed.</P> <P>Graphic Abstract</P><P>As an electric field was applied to homogeneously aligned cells, a new bent-shaped molecule with an acute-angled central core, 2,3-naphthylene bis[4-(4-n-dodecyloxybenzoyloxy)benzoate], showed a ferroelectric smectic A phase (SmAP<SUB>F</SUB>; Figs c–e). <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b919404e'> </P>
Synthesis and properties of azomethine polymers with bent-core mesogens
Choi, E-Joon,Kwon, Myeong-Hoon,Ohk, Chang-Woo,Zin, Wang-Cheol 한국정보디스플레이학회 2013 Journal of information display Vol.14 No.4
Three azomethine polymers with bent-core mesogens in their main chains were synthesized via polycondensation, and the effect of the central bent-core structure (Ar = 1,2-phenylene, 2,3-naphthylene, or 2,7-naphthylene) was studied. Although polymers contain bent-shaped mesogens in their main chains, no polymer showed good solubility in common organic solvents but all polymers exhibited liquid crystalline and semi crystalline properties. Two of the three polymers showed thermal degradation before melting due to the high melting point. The polymer with 2,3-naphthylene had a $229^{\circ}C$ melting point. The optical texture of the smectic phase could be observed using quenched samples from the melt state. During heating, the smectic layer structure could be detected via X-ray diffraction.