1H NMR Measurements of the Phase Transition of (NH₄)₃H(SO₄)₂ Single Crystals

S. H. Choi,Moohee Lee,Ae Ran Lim,K. S. Han,S. K. Kwon,S. K. Nam 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.2

$^1$H nuclear magnetic resonance (NMR) experiments have been performed in the temperature range of 30 -- 300 K at 7 T to investigate the phase-dependent nature of the dynamic network of hydrogen bonds in a ((NH₄)₃H(SO₄)₂ single crystal. The crystal has six phases, which are ferroelectric, antiferroelectric, incommensurate, antiferroelectric, ferroelastic, and superionic with the respective transition temperatures of 63, 133, 139, 256 and 413 K. The spin-lattice relaxation time, T₁, of ¹H NMR is similar for the ammonium protons and the hydrogen-bond protons over the entire range of experimental temperatures. The T₁, of ¹H NMR gradually decreases down to 120 K and starts to steeply increase below 100 K. Then, the T₁ shows an abrupt decrease below 68 K with a sharp minimum at 63 K, where the ferroelectric transition occurs. The ¹H NMR spectrum shifts to the high-frequency side at temperatures below 63 K due to the ferroelectric phase transition. This behavior of the T₁ and the spectrum confirms a dramatic change in the dynamics of hydrogen bonds associated with the ferroelectric phase transition at 63 K. $^1$H nuclear magnetic resonance (NMR) experiments have been performed in the temperature range of 30 -- 300 K at 7 T to investigate the phase-dependent nature of the dynamic network of hydrogen bonds in a ((NH₄)₃H(SO₄)₂ single crystal. The crystal has six phases, which are ferroelectric, antiferroelectric, incommensurate, antiferroelectric, ferroelastic, and superionic with the respective transition temperatures of 63, 133, 139, 256 and 413 K. The spin-lattice relaxation time, T₁, of ¹H NMR is similar for the ammonium protons and the hydrogen-bond protons over the entire range of experimental temperatures. The T₁, of ¹H NMR gradually decreases down to 120 K and starts to steeply increase below 100 K. Then, the T₁ shows an abrupt decrease below 68 K with a sharp minimum at 63 K, where the ferroelectric transition occurs. The ¹H NMR spectrum shifts to the high-frequency side at temperatures below 63 K due to the ferroelectric phase transition. This behavior of the T₁ and the spectrum confirms a dramatic change in the dynamics of hydrogen bonds associated with the ferroelectric phase transition at 63 K.

1H Nuclear Magnetic Resonance study of Ferroelectric (NH4)3H(SO4)2

S. H. Choi,K. S. Han,S. K. Kwon,S. K. Nam,H. H. Choi,Moohee Lee,Ae Ran Lim 한국자기공명학회 2007 Journal of the Korean Magnetic Resonance Society Vol.11 No.2

1H nuclear magnetic resonance (NMR) experiments have been performed at 30 - 300 K and 7 T to investigate dynamics of hydrogen bond network in the single crystal (NH4)3H(SO4)2. The two proton sites, ammonium proton and hydrogen-bond proton, are identified from the 1H NMR MAS spectrum at 340 K. As temperature decreases, the 1H NMR spectrum shifts to the higher frequency side with a larger linewidth. The spectrum at 65 K shows a distinctive change in line shape toward the ferroelectric transition at 63 K. The measured values of T1 for ammonium and hydrogen-bond protons are similar in the whole range of temperature. T1 of 1H NMR shows a gradual decrease down to 120 K and starts to steeply increase below 100 K. Then T1 shows abrupt decrease below 70 K with a sharp minimum at 63 K, where the ferroelectric transition occurs. This temperature dependence of spectrum and T1 clearly prove that the large change in the dynamics of hydrogen bond network is associated with the ferroelectric phase transition at 63 K.

[ $^1H$ ] Nuclear Magnetic Resonance Study of Ferroelectric $(NH_4)_3H(SO_4)_2$

Choi, S.H.,Han, K.S.,Kwon, S.K.,Nam, S.K.,Choi, H.H.,Lee, Moo-Hee,Lim, Ae-Ran Korean Magnetic Resonance Society 2007 Journal of the Korean Magnetic Resonance Society Vol.11 No.2

[ $^1H$ ] nuclear magnetic resonance (NMR) experiments have been performed at 30 - 300 K and 7 T to investigate dynamics of hydrogen bond network in the single crystal $(NH_4)_3H(SO_4)_2$. The two proton sites, ammonium proton and hydrogen-bond proton, are identified from the $^1H$ NMR MAS spectrum at 340 K. As temperature decreases, the $^1H$ NMR spectrum shifts to the higher frequency side with a larger linewidth. The spectrum at 65 K shows a distinctive change in line shape toward the ferroelectric transition at 63 K. The measured values of $T_1$ for ammonium and hydrogen-bond protons are similar in the whole range of temperature. $T_1$ of $^1H$ NMR shows a gradual decrease down to 120 K and starts to steeply increase below 100 K. Then $T_1$ shows abrupt decrease below 70 K with a sharp minimum at 63 K, where the ferroelectric transition occurs. This temperature dependence of spectrum and $T_1$ clearly prove that the large change in the dynamics of hydrogen bond network is associated with the ferroelectric phase transition at 63 K.

Proposed mechanism in the change of cellular composition in the outer medullary collecting duct during potassium homeostasis.

Park, E-Y,Kim, W-Y,Kim, Y-M,Lee, J-H,Han, K-H,Weiner, I D,Kim, J Gutenberg 2012 HISTOLOGY AND HISTOPATHOLOGY Vol.27 No.12

<P>Potassium depletion (K?-D) induces hypertrophy and hyperplasia of collecting duct cells, and potassium repletion (K?-R) induces regression of these changes. The purpose of this study was to examine the time courses of the changes in cellular composition, the origin of intercalated cells (ICs) and the mechanism responsible for these changes. SD rats received K?-depleted diets for 1, 7, or 14 days. After K?-D for 14 days some of the rats received normal diets for 1, 3, 5, or 7 days. In the inner stripe of the outer medulla, K?-D increased significantly the number and proportion of H?-ATPase-positive ICs, but decreased the proportion of H?-ATPase-negative principal cells (PCs). However, proliferation was limited to H?-ATPase-negative PCs. During K?-R, the cellular composition was recovered to control level. Apoptosis increased during K?-R and exclusively limited in H?-ATPase-negative PCs. Double immunolabeling with antibodies to PC and IC markers identified both cells negative or positive for all markers during both K?-D and K?-R. Electron microscopic observation showed that ultrastructure of AE1-positive some cells were similar to AE1-negative some cells during K?-R. LC3 protein expression increased significantly and autophagic vacuoles appeared particularly in PCs on days 14 of K?-D and in ICs on days 3 of K?-R. These results suggest that PCs and ICs may interconvert in response to changes in dietary K+ availability and that autophagic pathways may be involved in the interconversion.</P>

Urinary concentration of transforming growth factor-&bgr;-inducible gene-h3(&bgr;ig-h3) in patients with Type 2 diabetes mellitus

Cha, D. R.,Kim, I. S.,Kang, Y. S.,Han, S. Y.,Han, K. H.,Shin, C.,Ji, Y. H.,Kim, N. H. Blackwell Science Ltd 2005 Diabetic medicine Vol.22 No.1

<P>Abstract</P><P>Aims </P><P>The expression of TGF&bgr;-inducible gene h3(&bgr;ig-h3) has been used to assess the biological activity of TGF&bgr; in the kidney. In this study, we investigated whether the urinary concentration of &bgr;ig-h3 is associated with diabetic nephropathy in patients with Type 2 diabetes mellitus. We also evaluated the relationship between the urinary concentration of &bgr;ig-3 and proteinuria and microalbuminuria (AER) in a normal healthy population and in Type 2 diabetes patients.</P><P>Methods </P><P>Four hundred and seventy-nine Type 2 diabetic patients without non-diabetic kidney diseases and 528 healthy control subjects were enrolled. The study subjects were divided into five groups: a non-diabetic healthy control group with normal ACR (<I>n</I> = 443), a non-diabetic healthy control group with microalbuminuria (<I>n</I> = 85), a normoalbuminuric diabetic group (<I>n</I> = 198), a microalbuminuric diabetic group (<I>n</I> = 155) and an overt proteinuria group (<I>n</I> = 126). Urinary levels of &bgr;ig-h3 were measured by enzyme-linked immunosorbent assay.</P><P>Results </P><P>(i) Urinary excretion of &bgr;ig-h3 was significantly higher in the diabetic groups than in the controls, even in the normoalbuminuric stage (25.02 ± 8.84 vs. 18.67 ± 6.56, <I>P</I> = 0.03). In diabetic patients, urinary &bgr;ig-h3 levels increased significantly as diabetic nephropathy advanced (25.02 ± 8.84 vs. 34.06 ± 24.55 vs. 169.63 ± 57.33, <I>P</I> < 0.001). (ii) Proteinuria was found to be significantly correlated with urinary &bgr;ig-h3 (healthy control; <I>r</I> = 0.137, <I>P</I> = 0.019, diabetic patients; <I>r</I> = 0.604, <I>P</I> < 0.001). ACR was also found to be significantly related with urinary &bgr;ig-h3 in diabetic patients (<I>r =</I> 0.383, <I>P</I> = 0.006). (iii) In diabetic patients, urinary &bgr;ig-h3 was significantly related with systolic and diastolic blood pressure (systolic blood pressure: <I>r</I> = 0.436, <I>P</I> = 0.024; diastolic blood pressure, <I>r</I> = 0.365, <I>P</I> = 0.042), total cholesterol and HbA<SUB>1c</SUB> (cholesterol: <I>r</I> = 0.169, <I>P</I> = 0.03, HbA<SUB>1c</SUB>; <I>r</I> = 0.387, <I>P</I> = 0.044). Logistic regression analyses showed that urinary &bgr;ig-h3 was associated with a significant increase in the risk of microalbuminuria and proteinuria in diabetic patients.</P><P>Conclusions </P><P>Longitudinal monitoring of urinary &bgr;ig-h3 may improve the likelihood of detecting diabetic nephropathy at an earlier stage and &bgr;ig-h3 could be a sensitive marker of diabetic kidney disease progression.</P>

Diffusion barrier coating using a newly developed blowing coating method for a thermally stable Pd membrane deposited on porous stainless-steel support

Han, J.Y.,Kim, C.H.,Lim, H.,Lee, K.Y.,Ryi, S.K. Pergamon Press ; Elsevier Science Ltd 2017 International journal of hydrogen energy Vol.42 No.17

<P>In this study, we present an intermetallic diffusion barrier coating using a newly developed blowing coating method for a thermally stable Pd-based composite membrane on porous stainless steel (PSS). A tubular PSS sample with 1/2 inch (12.7 mm) in diameter and 450 mm in length was used for the support. The support was welded with a stainless-steel cap and a 450-mm-long stainless-steel tube for each end. Before the diffusion barrier coating, the large-sized entrance pores were gradually blocked with sub-micron (similar to 500 nm) and nano (50 80 nm) yttria stabilized zirconia (YSZ). 8YSZ, i.e., 8wt.% YSZ, was used for the interdiffusion barrier material and dispersed on the surface of the pre-treated PSS using the blowing coating method. The blowing coating method has 4 steps: (i) spraying the 17 wt. % 8YSZ paste on the surface of the PSS tube,(ii) blowing the paste using compressed air,(iii) drying at room temperature, and (iv) heat treatment at 923 K for 2 h in air. Steps (i) and (ii) were repeated 3 times to have a similar to 240 nm thick 8YSZ layer. A thin palladium layer (similar to 3 mu m) was deposited on the pre-treated PSS using electroless plating, and the membrane stability was tested at 673-773 K for similar to 200 h. A hydrogen permeation flux of 9.86 x 10(-2) mol m(-2) s(-1) and an H-2/N-2 selectivity of 595 were obtained at 773 K and a transmembrane pressure difference of 20 kPa. The surface and cross-sectional SEM/EDX analysis confirmed that the 8YSZ layer sufficiently prevented the interdiffusion between Pd and PSS elements, such as Fe, Cr and Ni. (c) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.</P>

비육중인 HOLSTEIN 수소에 있어서 저질 조사료의 에너지 이용성에 관한 연구

한인규,김홍대,하종규,김완영,Yanglian, Feng 한국영양사료학회 1999 韓國營養飼料學會誌 Vol.23 No.5

본 연구는 저질 조사료의 에너지 가치 및 이용성을 평가하기 위해서 평균체중이 400㎏인 비육중인 Holstein 수소 4두를 공시하여 수행하였다. 공시동물은 각각 호흡대사실에서 4가지 사료를 4×4 Latin square 방법으로 공급받았다. 대조구는 농후사료(50%)와 Chinese wildrye hay(50%) 사료를 사용하였으며, 처리구는 저질 조사료구로서 무처리 볏짚(100%). 요소처리 볏짚(100%) 및 Chinese wildrye 건초(100%) 등 3가지 사료를 이용하였다. 처리구간의 에너지소화율에 있어서는 유의적 차이가 나타나지 알았지만, 대조구는 처리구에 비하여 에너지소화율이 유의적으로 높게 나타났다(P<0.05). Chinese wildrye 건초만을 에너지 섭취수준을 달리하여 급여한 결과, 에너지섭취가 증가할수록 에너지소화율은 감소하였다. 또한 같은 시험에서, 조사료 입자가 감소할수록 에너지소화율이 증가하는 경향을 보였다. 메탄과 뇨를 통한 에너지 손실에 있어서 처리구 및 대조구간에 차이는 없었지만, 사료중의 NDF가 증가할수록 메탄생성이 증가하였다. 요소처리 볏짚과 Chinese wildrye 건초 처리구간에 K_m과 K_f 모두 비슷하였으며, 대조구의 K_f가 가장 높게 나타났다. 단백질과 지방의 체내축적은 대조구, Chinese wildrye 건초구, 요소처리 볏짚구 및 무처리 볏짚구 순으로 높았다(P<0.05). 본 연구 결과는 화학처리 볏짚이 에너지소화율과 이용성에 면에서 무처리 볏짚보다 우수하게 나타났으며, 특히 값비싼 Chinese wildrye 건초를 에너지 이용성 면에서 값싼 화학처리 볏짚으로 대체할 수 있는 가능성을 보였다. Four steers weighing average of around 400㎏ were used in a 4 × 4 Latin square design to study energy values of low quality roughages. The energy digestibilities of rice straw, treated rice straw, and Chinese wildrye hay were not significantly different. However, the digestibility of control diet (concentrate + Chinese wildrye hay) was significantly higher (P<0.05) than those of low-quality roughages. The energy digestibility of rice straw was not improved due to the treatment of urea-Ca(OH)₂. The result showed N digestibility tended to be higher in the steer fed treated rice straw. When effects of particle sizes of low quality roughage, Chinese wildrye hay, on energy digestibility were determined, there were no significant differences in GE intakes among the treatments of four particle sizes of the hay. Results also showed that energy digestibility tended to slightly increase as the particle size reduced. Methane production in relation to DE was the highest in the treatment of untreated rice straw, and the lowest with control diet. However, there were no significant differences among four feeding treatments. Urine excretion showed similar trends with methane production. Total energy loss via methane and urine against DE were 12.26, 22.93, 16.35, and 14.88 % in control diet, untreated rice straw, treated rice straw, and Chinese wildrye hay, respectively. The efficiency of utilization of DE was not significantly different among the treatments, but untreated rice straw showed the lowest efficiency. The results also showed that K_m, among untreated rice straw, treated rice straw, and wildrye hay were similar. These data also showed that both the K_m, and K_f from treated rice straw and Chinese wildrye hay were remarkably similar. This similarity clearly showed that treated rice straw had no effect on the efficiency of ME utilization for either K_m and K_f in fattening steers. The K_f of control diet was the highest among the treatment. With regard to body deposition of protein and fat, the results showed the higher values in the order of control diet, Chinese wildrye hay, treated rice straw, and rice straw. Based on these observations, this study regarding energy utilization clearly shows that a portion of expensive forages in the diet could be replaced with low-quality roughages such as treated rice straw.

The mechanism of hydrogen embrittlement in intercritically annealed medium Mn TRIP steel

Han, J.,Nam, J.H.,Lee, Y.K. Elsevier Science 2016 Acta materialia Vol.113 No.-

<P>The objective of this study was to investigate the mechanisms of hydrogen embrittlement (HE) in intercritically annealed medium Mn steel. For this purpose, both hot-rolled and cold-rolled Fe-7Mn-0.1C-0.5Si (wt.%) steels were annealed at 640 degrees C for 30 min. The annealed specimens had a dual-phase microstructure of retained austenite (gamma R) and ferrite (alpha) with different morphologies; a lath shape for the hot-rolled and annealed (HRA) specimen and a globular shape for the cold-rolled and annealed (CRA) specimen. Although the difference in microstructural morphology did not influence the H permeation, it significantly affected the HE behavior. The H-charged HRA (HRA(H)) specimen was fractured by inter granular cracking occurring along the boundaries of prior gamma grains by the H-enhanced decohesion (HEDE) mechanism. The intergranular cracking leaved both flat and rugged facets, which appeared at the prior gamma grain boundaries without and with gamma R, respectively. The H-charged CRA (CRA(H)) specimen was fractured to leave both dimples filled with grains and empty dimples at the fractured surface. The dimples filled with grains were generated by intergranular cracking occurring along the boundaries of gamma R grains by the HEDE mechanism. The empty dimples were made by intragranular cracking occurring inside the alpha grains by the H-enhanced local plasticity (HELP) mechanism. The CRA(H) specimen exhibited a smaller elongation loss than the HRA(H) specimen because cracks were propagated by frequently changing their direction along the boundaries of nano-sized gamma R grains or into alpha grains. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.</P>

희토류 금속을 첨가한 적철광의 자기상 전이

한경훈,신경호,김정기,정재윤 漢陽大學校 自然科學硏究所 2000 自然科學論文集 Vol.19 No.-

다결정시료(Fe₂O₃)1-x(Eu₂O₃)x (x=0.04와 0.06)계의 자기상 전이를 연구하기 위해 상온에서의 X선 회절, 액체질소온도에서 상온에 이르는 온도구간에서의 Mossbauer 분광과 약 8K에서 300K의 온도구간에서의 자기능률 측정방법을 사용하였다. X선 회절은 본 연구의 다결정시료가 a-Fe₂O₃와 동일한 rhombohedral결정구조를 가짐을 보인다. X선 회절선의 결과를 이용하여 비선형최소자승법을 써서 각 시료의 격자상수값을 구하였다. Mossbauer 분광결과는 자기상 전이가 255K<T<265K 온도 영역에서 일어남을 보인다. 온도영역 T<255K에서의 초미세 자기장의 온도 의존성에 반강자성 spinwave이론이 잘 적용됨을 보인다. 온도에 따른 magnetization의 변화로 자기상전이 온도를 관찰하였으며, 이 결과는 Mossbauer 분광 결과와 잘 일치 하였다. 상온에서의 hysteresis 곡선은 Eu농도가 증가함에 따라서 보자력이 증가하지만 자화와 잔류자화는 감소했음을 알 수 있었다. A study of magnetic transition for the polycrystalline (Fe₂O₃)1-x(Eu₂O₃)x (x=0.04 and 0.06) has been performed by the methods of X-ray diffraction at room temperature, Mossbauer spectroscopy within the temperature range from liquid nitrogen to room temperature, and a measurement of magnetic moment within temperature range of 8K∼300K. X-ray diffraction shows that the samples are in the same rhombohedral crystal structure as that of a-Fe₂O₃. The lattice parameter of the samples has been determined from X-ray diffraction patterns using computer with a progam of nonlinear square-fit. The Mossbauer results tell us that the magnetic transition of the samples occurs in the temperature region of 255K<T<265K. The temperature dependence of magnetic hyperfine field of the samples is in good agreement with a spin-wave theory for a antiferromagnetic phase within the temperature range from liquid nitrogen to 255K. The magnetic phase transition was observed by a temperature dependence of magnetization and the result was in good agreement with that of Mossbauer. Magnetic hysteresis curves indicated that the values of coercivity increase but that of magnetization and remanence of the samples decrease as increasing the concentration of Eu.

Diagnostic usefulness of a T cell-based assay for latent tuberculosis infection in kidney transplant candidates before transplantation

Kim, S.-H.,Lee, S.-O.,Park, I.-A.,Park, S.J.,Choi, S.-H.,Kim, Y.S.,Woo, J.H.,Park, S.-K.,Park, J.S.,Kim, S.C.,Han, D.J. Blackwell Publishing Inc 2010 Transplant infectious disease Vol.12 No.2

<P>S.-H. Kim, S.-O. Lee, I.-A. Park, S.J. Park, S.-H. Choi, Y.S. Kim, J.H. Woo, S.-K. Park, J.S. Park, S.C. Kim, D.J. Han. Diagnostic usefulness of a T cell-based assay for latent tuberculosis infection in kidney transplant candidates before transplantation.Transpl Infect Dis 2010: <B>12:</B> 113–119. All rights reserved</P><P>Background</P><P>The presence of latent tuberculosis (TB) infection (LTBI) should be evaluated before kidney transplantation. Although a new T cell-based assay for diagnosing LTBI gave promising results, this assay has not yet been compared with the tuberculin skin test (TST) for diagnosing LTBI in renal transplant candidates before transplantation.</P><P>Patients and methods</P><P>All adult patients admitted to a single institute for renal transplantation over a 1-year period were prospectively enrolled. A clinically predictive risk of LTBI was defined as: (i) recent close contact with a person with pulmonary TB; (ii) abnormal chest radiography; (iii) a history of untreated or inadequately treated TB; or (iv) a new infection (i.e., a recent conversion of TST).</P><P>Results</P><P>Of 209 renal recipients, 47 (22%) had a positive TST≥5 mm, 21 (10%) had a positive TST≥10 mm, 65 (30%) had a positive T-SPOT.<I>TB</I> test, and 25 (12%) had an indeterminate T-SPOT.<I>TB</I> test. The induration size of TST was significantly associated with a high positivity rate on T-SPOT.<I>TB</I> (<I>P</I><0.001). Agreement between T-SPOT.<I>TB</I> test and TST≥10 mm was fair (<I>k</I>=0.24, 95% confidence interval 0.11–0.36). However, neither univariate nor multivariate analysis showed any association between the clinical risk for LTBI and positivity on T-SPOT.<I>TB</I> or TST.</P><P>Conclusion</P><P>T-SPOT.<I>TB</I> test was more frequently positive than TST in renal transplant candidates. However, further longitudinal studies are awaited to determine whether the ability of T-SPOT.<I>TB</I> assay to detect LTBI in renal transplant recipients can better predict the development of TB than can TST after transplantation.</P>