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>

Spark plasma sintering of UO2 fuel composite with Gd2O3 integral fuel burnable absorber

Papynov E.K.,Shichalin O.O.,Belov A.A.,Portnyagin A.S.,Buravlev I.Yu,Mayorov V.Yu,Sukhorada A.E.,Gridasova E.A.,Nomerovskiy A.D.,Glavinskaya V.O.,Tananaev I.G.,Sergienko V.I. 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.8

The paper studies spark plasma sintering (SPS) of industrially used UO2-based fuel containing integral fuel burnable absorber (IFBA) of neutrons Gd2O3. Densification dynamics of pristine UO2 powder and the one added with 2 and 8 wt% of Gd2O3 under ultrasonication in liquid has been studied under SPS conditions at 1050, 1250, and 1450 C. Effect of sintering temperature on phase composition as well as on O/U stoichiometry has been investigated for UO2 SPS ceramics. Sintering of uranium dioxide added with Gd2O3 yields solid solution (U,Gd)O2, which is isostructural to UO2. SEM with EDX and metallography were implemented to analyze the microstructure of the obtained UO2 ceramics and composite UO2- Gd2O3 one, particularly, open porosity, defects, and Gd2O3 distribution were studied. Microhardness, compressive strength and density were shown to reduce after addition of Gd2O3. Obtained results prove the hypothesis on formation of stable pores in the system of UO2-Gd2O3 due to Kirkendall effect that reduces sintering efficiency. The paper expands fundamental knowledge on pros and cons of fuel fabrication with IFBA using SPS technology.

이산시간 I-PD형 제어기의 설계에 관한 연구

염만오,윤일로,김영민 경남대학교 공업기술연구소 2000 硏究論文集 Vol.18 No.-

본 연구에서는 Exact 모델매칭법에 기초한 이산시간 I-PD형 제어기를 설계한다. 보통의 모델 매칭은 이산시간 I-PD형 제어계와 경우 시스템의 지연시간 때문에 참조모델에 있어서 중요한 저차항의 매칭이 행해지지 않는 문제점이 발생된다. 따라서 임의의 참조모델에 대하여 모델매칭을 행하는 것이 불가능하다. 이것을 해결하기 위해 제어대상에 전치보상기를 새롭게 투입하고 확대계에 대하여 모델매칭을 행하는 방법에 관하여 고찰한다. 다음으로 위의 방법에 기초하여 제어기에 포함되는 PID 게인을 자동 조정한 적응 게인 조정법에 의한 I-PD형 제어기를 설계한다. 적응 게인 조정법을 사용한 오토튜닝 PID 제어계와 셀프튜닝 PID 제어계에 관한 연구가 보고되고 있지만 제어계 설계가 복잡했고 실제 장치화가 어려운 경우가 있었다. 본 연구에서 설계하는 적응 게인 조정법은 이산시간계에서의 설계방법이고 간단한 제어 알고리즘으로 구성되어 있어 실제로 제어계를 구현하는 것이 쉽다. Discrete-timeler based on exact model matching method is designed in this study. Usual discrete-time I-PD type controller leads to a matter of output errors which are due to time-delay element of the system. So it is impossible that model matching about spontaneous reference model. To settle this problem, a new I-PD type controller inserted a pre-compensator is used. According to this method, adaptive gain adjustment law is developed. Though Previous studies about auto-tuning and self-tuning PID controller by using adaptive gain adjustment method were published, they were complicated to design of controller and apply to actual plants. Adaptive gain adjustment law proposed in this paper is a method of design in discrete-time domain and it consists of simple control algorithm. Furthermore control system implementation is easy. In this study, discrete-time I-PD type controllers by model matching method and adaptive gain adjustment law are designed and simulated.

A study of nerve agent model organophosphonate binding with manganese-A₂B-corrole and -A₂B₂-porphyrin systems

Kim, K.,Kim, I.,Maiti, N.,Kwon, S.J.,Bucella, D.,Egorova, O.A.,Lee, Y.S.,Kwak, J.,Churchill, D.G. Pergamon Press 2009 Polyhedron Vol.28 No.12

Herein the synthesis and binding studies of novel trans-A<SUB>2</SUB>B-corrole and trans-A<SUB>2</SUB>B<SUB>2</SUB>-porphyrin derivatives are presented in comparing manganese(III)-organophosphonate (OP) binding (e.g., M<SUP>n+</SUP>←O?PR(OR)<SUB>2</SUB>) capabilities. H<SUB>3</SUB>(PFP-VC) [PFP-VC=5,15-di(pentafluorophenyl)-10-(3-vinylphenyl)corrolate] was synthesized by way of literature procedures and was characterized by a variety of 2-D NMR spectroscopic techniques and single-crystal X-ray diffraction. These compounds represent the first example of 3-vinyl-phenyl-containing meso-substituted corroles or porphyrins. Mn(PFP-VC) (3) was treated separately with (CH<SUB>3</SUB>CH<SUB>2</SUB>O)<SUB>2</SUB>P?O(C<SUB>3</SUB>H<SUB>6</SUB>NMe<SUB>2</SUB>), (C<SUB>4</SUB>H<SUB>9</SUB>O)<SUB>2</SUB>P?O(Me), (C<SUB>2</SUB>H<SUB>5</SUB>O)<SUB>2</SUB>P?O(CH<SUB>2</SUB>COCH<SUB>3</SUB>), (CH<SUB>3</SUB>CH<SUB>2</SUB>O)<SUB>2</SUB>P?O(Me), to give 1:1 adducts, as determined by UV-Vis spectroscopy (Job Plot), giving a red shift; Ph<SUB>3</SUB>P?O, was also found to bind, but very weakly. The trans-A<SUB>2</SUB>B<SUB>2</SUB>-porphyrin analogue Mn(PFP-VP) (4) was also prepared by way of a literature procedure; related binding studies gave 1:1 organophosphonate-Mn(PFP-VP) adducts (Job Plot). A clean blue shift occurred for the Mn-porphyrins at higher organophosphonate loadings (K<SUB>a</SUB> values: 6.7 (0.9)-11.9 (0.4)M<SUP>-1</SUP>). DFT geometry optimizations of O?P(OMe)<SUB>2</SUB>Me binding and formal Mn-O or P-O cleavage products in the unsubstituted neutral Mn-corrolato and -porphyrinato systems with a range of metal-based spin states revealed greatest stability in formal phosphoryl oxygen binding (energies: 11-13kcal/mol) for the Mn-corrole (singlet); the Mn-porphyrin (sextet) was also quite stable.

각종 천연 크로마이트광의 고체탄소에 의한 환원거동에 관한 연구

이일옥,정원섭,김동의 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.3

As a fundamental research to establish an efficient process for the solid-state reduction of chromite, reduction behavior of natural chromites were investigated experimentally and interpreted in terms of thermodynamics. The results obtained were as follows; 1) The reduction of oxide components in natural chromite tended to process in the sequence of Fe₃O₄, FeCr₂O₄ and MgCr₂O₄. The tendency was pronounced at low temperatures. 2) Below 1200℃, reduction of chromite proceeded sequentially, i.e. (Mg, Fe)(Cr, Al, Fe)₂O₄→ Fe or Fe₃C+Fe-poor Non-stoichimetric chromite → (Fe, Cr)_7C₃+MgAl₂O₄ 3) Above 1200℃, reduction of chromite proceeded sequentially, i.e. (Mg, Fe)(Cr, Al, Fe)₂O₄ → (Fe, Cr)_7C₃+Non-stoichimetric chromite → (Fe, Cr)_7C₃+MgAl₂O₄ 4) Reduction degree of chromite was higher with increasing Fe/Cr ratio of chromite composition. 5) Reduction rate of various chromite ore by solid carbon is higher in order SA, RM, IH, PH and IM at the same condition.

Synthesis of Hydrazone Derivatives of 4-(2-Chloroethyl) semicarbazide : A New Class of Cytotoxic Agents

El-Sabbagh, O.I.,El-Sadek, M.E.,Aboukull, M.E.,Shallal, H.M. Korean Chemical Society 2009 대한화학회지 Vol.53 No.1

새로운 종류의 히드라존 유도체는 4-(2-chloroethyl) semicarbazides로 부터 합성되었고, 인간 두 뇌(U251)와 간(Hepg2)의 암세포 에 대해 항증식성을 보였다. 히드라존 화합물은 벤즈알데히드, 아세토 페논, 3-formylindole 유도체이다. 아세토페논 유도체중에 3e (p-methoxy substituted)와 and 3f (p-nitro substituted)는 Hepg2 세포 (각각I$C_{50}$ = 6 ,8 $\mu$g/mL) 에 대해 가장 높은 세포독성활성을 보인다. 3-Formylindole 유도체중에 4a (hydrazone of 3-formylindole)은 U251 (I$C_{50}$ = 21 $\mu$g/mL)와 Hepg2 (I$C_{50}$ = 7 $\mu$g/mL)에 강한 세포독성활성을 보인다. A new series of hydrazone derivatives were synthesized from 4-(2-chloroethyl)semicarbazide and their antiproliferative activity against human brain (U251) and liver (Hepg2) carcinoma cell lines were evaluated. The hydrazone compounds are benzaldehyde (2a-2g), acetophenone (3a-3f), and 3-formylindole derivatives (4a-4d). Among the acetophenone derivatives, 3e (p-methoxy substituted) and 3f (p-nitro substituted) showed the highest cytotoxic activity against Hepg2 cell line (I$C_{50}$ = 6 and 8 $\mu$g/ml, respectively). Among the 3-formylindole derivatives, 4a (hydrazone of 3-formylindole itself) showed a pronounced cytotoxic activity against both U251 (I$C_{50}$ = 21 $\mu$g/ml) and Hepg2 (I$C_{50}$ = 7 $\mu$g/ml).

Excluded vertex-minors for graphs of linear rank-width at most k

Jeong, J.,Kwon, O.j.,Oum, S.i. Academic Press 2014 European journal of combinatorics : Journal europ& Vol.41 No.-

Linear rank-width is a graph width parameter, which is a variation of rank-width by restricting its tree to a caterpillar. As a corollary of known theorems, for each k, there is a finite obstruction set O<SUB>k</SUB> of graphs such that a graph G has linear rank-width at most k if and only if no vertex-minor of G is isomorphic to a graph in O<SUB>k</SUB>. However, no attempts have been made to bound the number of graphs in O<SUB>k</SUB> for k≥2. We show that for each k, there are at least 2<SUP>Ω(3^k)</SUP> pairwise locally non-equivalent graphs in O<SUB>k</SUB>, and therefore the number of graphs in O<SUB>k</SUB> is at least double exponential. To prove this theorem, it is necessary to characterize when two graphs in O<SUB>k</SUB> are locally equivalent. A graph is a block graph if all of its blocks are complete graphs. We prove that if two block graphs without simplicial vertices of degree at least 2 are locally equivalent, then they are isomorphic. This not only is useful for our theorem but also implies a theorem of Bouchet (1988) stating that if two trees are locally equivalent, then they are isomorphic.

Combustion properties of gaseous CH₄/O₂ coaxial jet flames in a single-element combustor

Kim, T.Y.,Choi, S.,Kim, H.K.,Jeung, I.S.,Koo, J.,Kwon, O.C. Butterworths [etc.] ; Elsevier Science Ltd 2016 Fuel Vol.184 No.-

Fundamental combustion properties of gaseous methane (CH<SUB>4</SUB>)/oxygen (O<SUB>2</SUB>) coaxial jet flames in a single-element combustor are experimentally evaluated as a preliminary step for subsequent studies of injection at very low temperature or using liquid O<SUB>2</SUB> for CH<SUB>4</SUB>/O<SUB>2</SUB> bipropellants, recently appearing to be the oncoming liquid bipropellant. A combustion chamber with quartz windows, a single shear coaxial injector and an exhaust nozzle on the downstream of the chamber is considered for the present study. Focusing on the measurements of the ignition and combustion stability limits of the coaxial jet flames in the chamber, flame visualization is also conducted by OH<SUP>*</SUP> chemiluminescence, schlieren imaging and direct imaging. Results show the ignition limits restricted than the combustion stability limits. Flame behaviors are largely classified into two, the stably attached flame and the oscillating, liftoff (near-blowout) flame. Due to cooling effects on the wall of the chamber, stably liftoff flame is not observed. The stability of the flame is greatest at fuel-rich condition (based on the injected amounts of CH<SUB>4</SUB> and O<SUB>2</SUB>). From the flame visualization flame thickness is found to be smaller than the injector lip thickness and insensitive to injection conditions. The laminar-flow behavior near the injector exit due to the strong burning of pure O<SUB>2</SUB> is observed even for high Reynolds numbers (Re). The flame visualization also exhibits the recirculating O<SUB>2</SUB> that enhances burning in the combustor through the reaction with the outer fuel jet. The results of ignition limits, combustion stability limits and flame visualization can be used as a database for researches of modeling the gaseous CH<SUB>4</SUB>/O<SUB>2</SUB> jet flames in the combustion chamber.

장기 저장연료의 열안정성 및 연료접촉 고무오링의 수명예측 연구

정근우(K. W. Chung),홍진숙(J. S. Hong),김영운(Y. W. Kim),한정식(J. S. Han),정병훈(B. H. Jeong),권태수(T. S. Kwon),서동욱(D. O. Suh),성민준(M. J. Sung),권영일(Y. I. Kwon) 한국트라이볼로지학회 2018 한국윤활학회지(윤활학회지) Vol.34 No.5

Thermal deterioration of fuel due to long-term storage influences engine performance and causes malfunctions. Fuel stability is usually evaluated via heat resistance and thermal stability during a brief heat shock at high temperature; storage stability in this scenario means that there is very little change in the quality of the fuel during long-term storage. In addition, rubber-based products such as oil seals, O-rings, and rubber hoses can influence the quality of the fuel. When these rubber products are in contact with fuel, they can swell, mechanically weaken, and occasionally crack, thus leaking low molar weight rubber and additives including plasticizer and antioxidant into the fuel to degrade its properties and shorten its useful lifetime. This study determines the thermal stabilities of three kinds of synthetic fuels by evaluating their low temperature kinematic viscosities, chemical composition changes via GC analyses, gross heat of combustion, and color changes. We evaluate the compression set of O-rings by immersing one NBR and two FKM rubber O-rings in the three synthetic fuel samples in airtight containers at variable storage temperatures for six months; from this, we estimate the lifetimes of the O-rings using the Power law model. There were very little changes in the chemical compositions and gross heat of combustion after six months of the experiment. The lifetimes are thus dependent on the materials of the rubber products, and in particular, the FKM O-ring was calculated to have a theoretical lifetime of 200 to 5,700 years. These results indicate that the synthetic fuels maintain their physical properties even after long-term storage at high temperatures, and the FKM O-ring is suitable for long-term sealing of these fuels.

Self-standing and shape-memorable UV-curing epoxy polymers for three-dimensional (3D) continuous-filament printing

Sun, H.,Kim, Y.,Kim, Y. C.,Park, I. K.,Suhr, J.,Byun, D.,Choi, H. R.,Kuk, K.,Baek, O. H.,Jung, Y. K.,Choi, H. J.,Kim, K. J.,Nam, J. D. The Royal Society of Chemistry 2018 Journal of materials chemistry. C, Materials for o Vol.6 No.12

<P>In the development of three-dimensional printable materials for high-speed and high-resolution printing, UV-curing polymers can guarantee fast and precise printing of high performance load-bearing structures, but the injected drops of the monomers tend to spread over the substrates due to their low viscosity. In this study, we imposed the self-standing and shape-memorable capability of an epoxy acrylate (EA) monomer to ensure continuous filamentary 3D printing while maintaining its low viscosity nature. Using octadecanamide (ODA) with EA, strong hydrogen-bond networks (−N−H⋯OC−, −N−CO⋯H-O-, -N-H⋯N-) were additionally achieved in the material system and the developed material distinctively exhibited rheological duality at different processing stages: a low-viscosity liquid-like behavior (viscosity of ∼50 Pa) while passing through the nozzle and a self-standing solid-like behavior (static yield stress of ∼364 Pa) right after being printed. This reversible liquid-to-solid transitional capability was quantified by viscoelastic complex moduli provided a dynamic yield stress (<I>τ</I>y,G) of 210 Pa corresponding to the upright stacking up to ∼3.2 cm (3 wt% of ODA). The time (<I>t</I>y,G) required for conformational rearrangement was evaluated to be as fast as ∼10<SUP>−2</SUP> s. After UV curing, the 3D printed layers exhibited no air pockets or weld lines at the stacked interfaces, which could guarantee excellent mechanical performance and structural integrity.</P>