Preparation and Characterization of Sulfonated Poly(ether Sulfone) Using 4,4-Bis(4-Hydroxylphenyl)valeric Acid for Proton Exchange Membrane Fuel Cell Application

Seo, Dong Wan,Lim, Young Don,Islam Mollah, M. S.,Lee, Soon Ho,Moon, Sang Ho,Pyun, Sang Young,Kim, Whan Gi Trans Tech Publications, Ltd. 2009 Materials science forum Vol.620 No.-

<P>Poly(ether sulfone)s (PES) containing 25-75 mol % valeric acid were prepared with bisphenol A, bis(4-chlorophenyl)sulfone and 4,4-Bis(4-hydroxylphenyl)valeric acid using potassium carbonate in DMAc (dimethylacetamide) at 160 °C. Copolymers containing carboxylacid group were reduced to hydroxy group by BH3 solution 1M in THF and NaBH4 co-catalyst. Sulfonated poly(ether sulfone)s (S-PES) were obtained by reaction of 1,3-propanesultone and the reduced copolymer (PES-OH) with potassium t-butoxide. A series of copolymers were studied by 1H-NMR spectroscopy, differential scanning calorimetry (DSC), and thermo gravimetric analysis (TGA). Sorption experiments were conducted to observe the interaction of sulfonated polymers with water and methanol. The S-PES membranes exhibited proton conductivities from 1.20  10-3 to 3.40  10-3 S/cm, water swell from 12.25 to 31.50 %, IEC from 0.43 to 0.72 meq/g and methanol diffusion coefficients from 3.60  10-7 to 4.90  10-7 cm2/S at 25 °C.</P>

CD137-inducing factors from T cells and macrophages accelerate the destabilization of atherosclerotic plaques in hyperlipidemic mice

Jung, In-Hyuk,Choi, Jae-Hoon,Jin, Jing,Jeong, Se-Jin,Jeon, Sejin,Lim, Chaeji,Lee, Mi-Ran,Yoo, Ji-Young,Sonn, Seong-Keun,Kim, Young Ho,Choi, Beom Kyu,Kwon, Byoung S.,Seoh, Ju-Young,Lee, Cheol Whan,Kim, The Federation of American Societies for Experimen 2014 The FASEB Journal Vol.28 No.11

<P>CD137 (4-1BB), a member of the tumor necrosis factor receptor superfamily, has been reported to be expressed in atherosclerotic plaques, and to promote lesion formation. However, the role of CD137 in mediating atherosclerotic plaque stability and the possible underlying molecular and cellular mechanisms are poorly understood. Here, apolipoprotein E-deficient (<I>ApoE</I><SUP>−/−</SUP>) and CD137-deficient <I>ApoE</I><SUP>−/−</SUP> (<I>ApoE</I><SUP>−/−</SUP>CD137<SUP>−/−</SUP>) mice fed a chow diet for 66 wk were used. CD137 induces plaque instability, which is characterized by increased plaque necrosis, decreased collagen content, decreased vascular smooth muscle cell (VSMC) content, and increased macrophage infiltration. CD137 also increases the infiltration of effector T (T<SUB>eff</SUB>) cells into plaque lesion sites, resulting in increased interferon-γ (IFN-γ) expression. Interestingly, T<SUB>eff</SUB>-cell-derived IFN-γ inhibits collagen synthesis in atherosclerotic plaques. Furthermore, CD137 activation increases the apoptosis of VSMCs, possibly by decreasing the antiapoptotic regulator, Bcl-2, and subsequently up-regulating cleaved caspase-3. In macrophages, activation of CD137 signaling boosted the oxidized low density lipoprotein-induced expression of matrix metalloproteinase 9 <I>via</I> the p38 mitogen-activated protein kinase and extracellular signal-regulated kinase1/2 signaling pathways. In summary, activation of CD137 signaling decreases the stability of advanced atherosclerotic plaques <I>via</I> its combined effects on T<SUB>eff</SUB> cells, VSMCs, and macrophages.—Jung, I.-H., Choi, J.-H., Jin, J., Jeong, S.-J., Jeon, S., Lim, C., Lee, M.-R., Yoo, J.-Y., Sonn, S.-K., Kim, Y. H., Choi, B. K., Kwon, B. S., Seoh, J.-Y., Lee, C. W., Kim, D.-Y., Oh, G. T. CD137-inducing factors from T cells and macrophages accelerate the destabilization of atherosclerotic plaques in hyperlipidemic mice.</P>

2시간 허혈 및 재관류에 의한 흰쥐 대퇴곧은근의 미세구조 변화에 SOD,DMTU 및 허혈양상화 처치가 미치는 영향

임재현,조원길,현성희,백두진,정호삼 한양대학교 의과대학 1998 한양의대 학술지 Vol.18 No.1

The ischemia and reperfusion injury of the skeletal muscles is caused by generation of reactive oxygen during ischemia and reperfusion. The formation of oxygen free radicals is in proportion to the time of ischemia in the skeletal muscle. It is well known that over 4 hours of ischemia injures the skeletal muscles irreversibly and less than 2 hours of ischemia injures them reversibly. The author has demonstrated the effects of SOD(superoxide dismutase), DMTU(dimethyl thiourea) and ischemic preconditioning on ultrastructural changes of the muscle fibers in the rectus femoris muscles after 2 hours or 4 hours of ischemia and timely reperfusion. A total of 120 healthy Sprague-Dawley rats weighing from 200gm to 250gm were used as experimental animals. Under urethane(1.15g/㎏, IP, 2 times) anesthesia, lower abdominal incision was done and the left common iliac artery was occluded by using vascular clamp for 2 or 4 hours. The left rectus femoris muscles were obtained at 1 and 3 days after the removal of vascular calmp. SOD(15000unit/㎏) or DMTU(500㎎/㎏) were administered intraperitoneally at 1 hour before induction of ischemia. The ischemic preconditioned group underwent three episodes of 5 minutes occlusion and 5 minutes reperfusion followed by 2 hours or 4 hours of ischemia and timely reperfusion. The specimens were sliced into 1㎣ and prepared by routine methods for electron microscopic observation. All preparations were stained with uranyl acetate and lead citrate and then observed with Hitachi-600 transmission electron microscope. The results were as follows: 1 SOD or DMTU alone did not affect the ultrastructure of muscle fibers in the rectus femoris muscles. The electron density of mitochondrial matrix was decreased by ischemic preconditioning. 2 Dilated cisternae of sarcoplasmic reticulum, dilated mitochondria with electron loose matri, dilated cristae were observed in the 2 hours ischemia and 1 day reperfused rectus femoris muscles. Myofibrilloysis, widening of interfibrillar space, segmentation or loss of myofilament in the sarcomere and transverse tubule wrapped with electron dense material were seen in the 2 hours ischemia and 3 days reperfused rectus femoris muscles. 3 Dilated cisternae of sarcoplasmic reticulum, triad, mitochondria and the loss of myofilamt in the sarcomere were observed in the 4 hours ischemia and 1 day reperfused rectus femoris muscles. Markedly changed sarcoplasmic reticulum, triad, disordered or loss of myofilament, indistinct A-band and I-band, and irregular electron lucent M-line and Z-line are seen in the 4 hours ischemia and 3 dyas reperfused rectus femoris muscles. 4 SOD reduced the changes of organelles in the muscle fibers of the 2 hours or 4 hours ischemia and 1 day reperfused rectus femoris muscles of the rats, but SOD did not affect the changes of muscle fibers in the 2 hours or 4 hours ischemia and 3 days reperfused muscles. On the other hand, DMTU markedly attenuated considerably the ultrastructural change of the 2 hours or 4 hours ischemia and 1 day or 3 days reperfused rectus femoris muscles. 5 By the ischemic preconditioning, the change was attenuated remarkably in the 2 hours or 4 hours ischemia and 1 day reperfused rectus femoris muscles. As the ischemic reperfused changes of muscle fibers were regenerted or recovered by ischemic preconditioning, the ultrastructures of them were similar to those of normal control in the 2 hours or 4 hours ischemia and 3 days reperfused rectus formoris muscles. Consequently, it is suggested that the severity of muscular damage depends on the duration of ischemia, and that DMTU is stronger inhibitor to ischemic reperfused change than SOD. The ischemia and reperfusion-induced muscular damage is remarkably inhibited by ischemic preconditioning.

윈도우 환경에서 음성인식을 이용한 인터넷 검색기 구현

임중혁,원호준,백인찬,권영헌,이건상 한양대학교 이학기술연구소 1999 이학기술연구지 Vol.1 No.-

본논문에서는 Window 상에서 웹브라우저 검색어로 영문 알파벳을 인식하도록 하였다. 음성의 특징 벡터로는 10차원의 LPC, cepstrum, LSF(Line Spectrum Frequency) 계수와, 규격화된 필터뱅크 에너지를 사용하였으며 인식 알고리즘으로는 MSVQ 모델을 사용하였다. 인식 대상 어휘는 26개의 알파벳을 사용하였으며 실험결과 필터뱅크 에너지를 사용한 인식결과가 가장 우수한 것으로 나타났다. This paper represents the speech recognizer of English alphabet for the internet explorer in Windows. We use 10-dimensional LPC, cepstrum, LSF coefficients and normalized filter bank energies as the speech feature vectors and MSVQ model as the recognition algorithm. As the results the recognizer using the normalized filter bank energies shows the better performance than that using the other feature vectors.

성인 천식환자에서 도메난(염산 오자그렐)의 임상적 효과와 안전성

최인선,고영일,임호,명보현,홍서나,오봉석,이삼용 최신의학사 2000 最新醫學 Vol.43 No.9-10

천명이 있으면서 정상 폐환기 기능 성적을 보인 천식 환자의 임상 분석

최인선,임호,고영일,정세웅 대한천식 및 알레르기학회 2004 천식 및 알레르기 Vol.24 No.1

Background : Wheezing is one of the characteristics of asthma. Intensity of wheezing is correlated with the severity of airway obstruction. However, some asthmatic patients may show wheezing despite normal ventilatory function. Objective : To determine the cause of wheezing in asthmatic patients with normal ventilatory function. Methods : Thirty-eight consecutive asthmatic patients with wheezing despite FEV 180% of predicted value were retrospectively examined for clinical data. Results : Twenty-seven patients (71.1%) were women. Sixteen patients (42.1%) showed airway obstruction based on the Intermountain Thoracic Society criteria. Patients with airway obstruction had significantly lower FEF50% than did those without it (F<.001). When the patients with no wheezing were re-examined by the pulmonary function test, 14 patients (48.3%) showed a significant bronchodilation. In patients without airway obstruction, FEF50/FIF50 was significantly higher than in those with it(F<.01). and FEF50/FIF50 >1 suggesting upper airway obstruction was observed in 7 of 16 (43.8%) patients. Associated diseases were rhinitis in 21 (55.3%) patients, sinusitis in 18 (47.4%), and postnasal drip syndrome in 3 (7.9%). Conclusions : Wheezing despite normal ventilatory function in asthma occurs more often in women. It may be related to reversible airway obstruction in nearly half patients and to upper airway obstruction such as rhinitis, in considerable numbers of the remaining patients. (J Asthma Allergy Clin Immunol 24 : 85-93, 2004)

Magnetic and magnetocaloric properties of La_0.6Ca_0.4−xCe_xMnO₃

Ho, T.A.,Lim, S.H.,Kim, C.M.,Jung, M.H.,Ho, T.O.,Tho, P.T.,Phan, T.L.,Yu, S.C. Elsevier 2017 Journal of magnetism and magnetic materials Vol.438 No.-

<P><B>Abstract</B></P> <P>La<SUB>0.6</SUB>Ca<SUB>0.4−</SUB> <I> <SUB>x</SUB> </I>Ce<I> <SUB>x</SUB> </I>MnO<SUB>3</SUB> (<I>x</I> =0, 0.03, 0.06, and 0.09) compounds are fabricated by a solid-state reaction, and their structural, magnetic, and magnetocaloric properties are investigated. The Curie temperature at which a ferromagnetic–paramagnetic transition occurs decreases from 260 to 221K as <I>x</I> increases from 0 to 0.09. The saturation magnetization also decreases with the increase of <I>x</I>. The experimental results for the magnetization with respect to the temperature and magnetic field are analyzed using the Banerjee criterion, revealing that all the samples undergo the second-order magnetic phase transition. The maximum magnetic entropy change measured at a magnetic-field span of 50kOe, which occurs near the Curie temperature, slightly increases from 6.31 to 7.62J/kg K as <I>x</I> increases from 0 to 0.09.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Magnetic and MCE of La<SUB>0.6</SUB>Ca<SUB>0.4−x</SUB>Ce<SUB>x</SUB>MnO<SUB>3</SUB> are investigated. </LI> <LI> All the samples underwent the second-order magnetic transition. </LI> <LI> Ce dopant favored the enhancement of the MCE. </LI> </UL> </P>

Universal curves in assessing the order of magnetic transition of La_0.7−xPr_xCa_0.3MnO₃ compounds exhibiting giant magnetocaloric effect

Ho, T.A.,Lim, S.H.,Phan, T.L.,Yu, S.C. Elsevier 2017 Journal of alloys and compounds Vol.692 No.-

<P><B>Abstract</B></P> <P>The magnetic properties of La<SUB>0.7-<I>x</I> </SUB>Pr<SUB> <I>x</I> </SUB>Ca<SUB>0.3</SUB>MnO<SUB>3</SUB> (<I>x</I> = 0.0, 0.2, 0.3, 0.4, and 0.5) compounds fabricated by a solid-state reaction are studied by using Arrott plots and universal curves. The Arrott plots near the Curie temperature show negative slopes over the entire magnetic field range up to 50 kOe, indicating a first-order magnetic phase transition (according to Banerjee's criterion) for the <I>x</I> = 0.0, 0.2, 0.3, and 0.4 samples. For the <I>x</I> = 0.5 sample, however, the plots show positive slopes at low magnetic fields below 10 kOe, indicating a second-order transition. These results are further checked by universal curves of the normalized entropy change versus reduced temperature. The universal curves show a divergence among the curves with different magnetic fields for a first-order magnetic transition, but for a second-order transition, they collapse onto the same curve. The Curie temperature, around which the maximum magnetic entropy change occurs, decreases continuously from 260 to 110 K as <I>x</I> increases from 0.0 to 0.5. In the same <I>x</I> range, the maximum entropy change measured at a magnetic field span of 50 kOe decreases from 10.70 to 7.14 J/kg K, but the relative cooling power increases from 278 to 380 J/kg under the same magnetic field span.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Magnetic and magnetocaloric properties of manganites are investigated. </LI> <LI> Universal curves are used to assess the magnetic transition order of manganites. </LI> <LI> Pr is substituted for La in LCMO to optimize the magnetocaloric properties. </LI> </UL> </P>

Chemical Degradation of Commercial Polymer Electrolyte Membrane for Vanadium Redox Flow Battery (VRFB)

Lim, Min-Hwa,Park, Mi-Jung,Kim, Sang-Chai,Roh, S. H.,Jung, Seung-Hun,Kim, Hee Tak,Jung, Ho-Young American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.8

<P>Durability test of commercial polymer electrolyte membranes investigated because longer performance of VRFB depends on the membrane's chemical stability. For hydrolytic stability test, distilled water and membrane was placed in the pressurized container, activated for 24 h at 200 degrees C to check the weight loss, and distilled water's pH change. To confirm the chemical degradation, the membrane was impregnated in 0.1 M V(V) solution for 72 h and concentration change was measured by UV-vis Spectrum. Through this experiment, anion exchange membrane in VRFB is considered in terms of chemical degradation.</P>

Magnetic and magnetocaloric properties of La_0.7Ca_0.3Mn_1−xZn_xO₃

Ho, T.A.,Lim, S.H.,Tho, P.T.,Phan, T.L.,Yu, S.C. Elsevier 2017 Journal of magnetism and magnetic materials Vol.426 No.-

<P><B>Abstract</B></P> <P>The magnetic Mn<SUP>3+</SUP> ions in La<SUB>0.7</SUB>Ca<SUB>0.3</SUB>MnO<SUB>3</SUB> are partially replaced by nonmagnetic Zn<SUP>2+</SUP> ions to form La<SUB>0.7</SUB>Ca<SUB>0.3</SUB>Mn<SUB>1−x</SUB>Zn<SUB>x</SUB>O<SUB>3</SUB> compounds (<I>x</I>=0.0, 0.06, 0.08, and 0.1), and their magnetic and magnetocaloric properties are investigated. The Curie temperature decreases drastically from 245 to 70K as <I>x</I> increases from 0 to 0.1. An analysis using the Banerjee's criterion of the experimental results for magnetization as a function of temperature and magnetic field indicates that the first-to-second order magnetic phase transformation occurs at a threshold composition of <I>x</I>=0.06, which is further supported by the universal curves of the normalized entropy change versus reduced temperature. The maximum magnetic entropy change measured at a magnetic field span of 50kOe, which occurs near the Curie temperature, decreases from 10.30 to 2.15J/kgK with the increase of <I>x</I> from 0.0 to 0.1. However, the relative cooling power, an important parameter for practical applications, shows a maximum value of 404J/kg at <I>x</I>=0.08, which is 1.5 times greater than that observed for the undoped sample.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Magnetic and MCE of La<SUB>0.7</SUB>Ca<SUB>0.3</SUB>Mn<SUB>1−x</SUB>Zn<SUB>x</SUB>O<SUB>3</SUB> are investigated. </LI> <LI> Order of magnetic phase transition is dependent on the Zn doping concentration. </LI> <LI> Although the |∆<I>S</I> <SUB>max</SUB>| decreases with increasing <I>x</I>, <I>RCP</I> increase remarkably. </LI> </UL> </P>