제올라이트 여재의 암모니아성 질소 이온교환 능력에 따른 ZBAF의 질산화 효율 비교

김진수 ( Jin-su Kim ),최승규 ( Seung-kyu Choi ),주천 ( Qian Zhu ),신관우 ( Gwan-woo Shin ),양창환 ( Chang-hwan Yang ),원경자 ( Kyoung-ja Weon ),이상일 ( Sang-ill Lee ) 한국수처리학회 2020 한국수처리학회지 Vol.28 No.2

This study was conducted to investigate nitrification by measuring the ammonia nitrogen adsorption ability of zeolite media. Zeolite adsorbs ammonia nitrogen through cation exchange. When zeolite is used as the filteration media in biological aerated filters (BAF), nitrifying bacteria can be easily attached. Using two types of zeolite that have different calcination temperatures, it was confirmed differences in nitrification rate relative to the ammonium ions exchange capacity of the zeolite media. The strength of the zeolite media was higher as calcination temperature was higher, while BET specific surface area was decreased. The ammonia nitrogen adsorption of the zeolite media at 600℃ was higher than at 900℃, but nitrification rates were similar when either media was used for the zeolite biological aerated filter (ZBAF). During the entire operation period, the 600℃ zeolite had an ammonia nitrogen removal rate of 0.31 kg/m³/d, and the 900℃ zeolite media had a rate of 0.28 kg/m³/d (p>0.05). When the influent was held on shutdown for a month and processing began again, the nitrification rate of the ZBAFs showed a similar amount of NO_x-N (sum of the concentration of nitrite and nitrate nitrogen) production within two days of reoperation that was similar to the rate before shutdown. The effect of water temperature had little effect on rate. Ammonia nitrogen removal by ZBAFs was maintained in water temperatures as low as 5℃. However, the ammonia nitrogen removal and nitrification rate were decreased in 600℃ zeolite media after 3 months of operation because media’s morphology changed.

Regulating exocytosis of nanoparticles <i>via</i> host–guest chemistry

Kim, Chaekyu,Tonga, Gulen Yesilbag,Yan, Bo,Kim, Chang Soo,Kim, Sung Tae,Park, Myoung-Hwan,Zhu, Zhengjiang,Duncan, Bradley,Creran, Brian,Rotello, Vincent M. The Royal Society of Chemistry 2015 Organic & Biomolecular Chemistry Vol.13 No.8

<P>Prolonged retention of internalized nanoparticulate systems inside cells improves their efficacy in imaging, drug delivery, and theranostic applications. Especially, regulating exocytosis of the nanoparticles is a key factor in the fabrication of effective nanocarriers for chemotherapeutic treatments but orthogonal control of exocytosis in the cellular environment is a major challenge. Herein, we present the first example of regulating exocytosis of gold nanoparticles (AuNPs), a model drug carrier, by using a simple host–guest supramolecular system. AuNPs featuring quaternary amine head groups were internalized into the cells through endocytosis. Subsequent <I>in situ</I> treatment of a complementary cucurbit[7]uril (CB[7]) to the amine head groups resulted in the AuNP-CB[7] complexation inside cells, rendering particle assembly. This complexation induced larger particle assemblies that remained sequestered in the endosomes, inhibiting exocytosis of the particles without any observed cytotoxicity.</P> <P>Graphic Abstract</P><P>Regulating exocytosis of AuNPs by using host–guest interactions between AuNPs and CB[7] molecules. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4ob02433h'> </P>

Effect of heat treatment on cyclic fatigue resistance, thermal behavior and microstructures of K3 NiTi rotary instruments

Chang, Seok Woo,Kim, Yu-Chan,Chang, Hyejung,Jee, Kwang-Koo,Zhu, Qiang,Safavi, Kamran,Shon, Won-Jun,Bae, Kwang-Shik,Spangberg, Larz Sw,Kum, Kee-Yeon Informa Healthcare 2013 Acta odontologica scandinavica Vol.71 No.6

<P><B><I>Objective.</I></B> The aim of this study was to investigate the effect of heat treatment on the cyclic fatigue resistance, thermal behavior and microstructural changes of K3 NiTi rotary instruments. <B><I>Materials and methods.</I></B> Twelve control (as-received) and 12 experimental (heat-treated) K3 NiTi rotary instruments were compared in this study. Those experimental K3 instruments were heated in a furnace for 30 min at 450°C and then quenched in water. The cyclic fatigue resistance was measured with a fatigue tester. The thermal characteristic and the microstructures of both instruments were investigated by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM), respectively. <B><I>Results.</I></B> There was a significant increase in the cyclic fatigue resistance between the heat-treated instruments and the as-received instruments (<I>T</I>-test, <I>p</I> < 0.05). DSC showed that the as-received and heat-treated samples were different, with an increased A<SUB>f</SUB> (austenite-finish temperature) for the latter. TEM analysis revealed that both as-received and heat-treated instruments were composed mainly of an austenite phase. However, the heat-treated samples had an increased appearance of larger grains, twinning martensite, TiO<SUB>2</SUB> surface layer and a Ni-rich inner layer. <B><I>Conclusions.</I></B> Heat treatment increased the cyclic fatigue resistance of NiTi files and changed the thermal behavior of the instruments without marked changes in the constituting phases of NiTi alloy.</P>

Optical properties of ZnO nanocrystals synthesized by sol-gel method

Ho Jung Chang,Chang-Sik Son,Cheng Zhu Lu,In-Hoon Choi,Seong-Il Kim,Yongsheng Wang,Young-Hwan Kim 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.1

ZnO nanocrystals were synthesized by using a sol-gel method and their optical properties were investigated as functions of the ZnO nanoparticle size. The photoluminescence spectrum showed two peaks: one was an ultraviolet (UV) exciton emission at around 363 nm, and the other was a visible emission at around 500 nm that originated from deep-band traps. As the particle size was increased, the intensity of the visible emission decreased, while that of the UV emission increased. Both the UV and the visible emissions shifted to a lower energy with increasing particle size. The band-edge emission exhibited a red-shift in relation to the absorption edge due to the Stokes shift. Exciton emission was observed at a slightly red-shifted wavelength with an energy of 180 meV in respect to the absorption onset, as observed in other II-VI semiconductor nanocrystals.

Hepatitis B virus reactivation in B-cell lymphoma patients treated with rituximab: Analysis from the Asia Lymphoma Study Group

Kim, S.J.,Hsu, C.,Song, Y.Q.,Tay, K.,Hong, X.N.,Cao, J.,Kim, J.S.,Eom, H.S.,Lee, J.H.,Zhu, J.,Chang, K.M.,Reksodiputro, A.H.,Tan, D.,Goh, Y.T.,Lee, J.,Intragumtornchai, T.,Chng, W.J.,Cheng, A.L.,Lim, Pergamon Press 2013 European journal of cancer Vol.49 No.16

Background: Hepatitis B virus (HBV) reactivation is increasing, as rituximab has become widely used for B-cell lymphoma. Thus, prevention and management of HBV reactivation are important in HBV-endemic areas. Methods: Hepatitis B virus (HBV) reactivation in HBV surface antigen (HBsAg)-positive patients and HBsAg-negative/HBV core antibody (HBcAb)-positive patients who received rituximab-containing chemotherapy was investigated by the Asia Lymphoma Study Group via retrospective (n=340), and the results were compared to cross-sectional analysis with patients who were prospectively monitored in a single institute (n=127). The goal of the study was to define the frequency of HBV reactivation and the efficacy of antiviral prophylaxis. Results: HBV reactivation was found in 27.8% of HBsAg-positive patients (45/162) in the retrospective analysis, being significantly less frequent in patients receiving antiviral prophylaxis than those not (22.9%, 32/140 versus 59.1%, 13/22; p<0.001). Lamivudine was most commonly used (96/162, 59.3%), but more than 20% of HBsAg-positive patients showed breakthrough HBV reactivation. In the cross-sectional analysis, a reduced rate of HBV reactivation occurred for entecavir as compared with lamivudine prophylaxis (6.3% versus 39.3%; p<0.05). HBV DNA monitoring of HBsAg-negative/HBcAb-positive patients in the cross-sectional analysis showed HBV reactivation in only 2.4% of cases. Conclusions: This is the largest study of HBV reactivation in patients receiving rituximab-containing chemotherapy to date, and we defined the probability of HBV reactivation in an HBV-endemic region.

Macrodispersion of multi-walled carbon nanotubes for conductive films.

Kim, Duckjong,Zhu, Lijing,Kim, Jae-Hyun,Han, Chang-Soo,Baik, Seunghyun American Scientific Publishers 2012 Journal of Nanoscience and Nanotechnology Vol.12 No.4

<P>Understanding of the effect of the multi-walled carbon nanotube (MWCNT) dispersion process on physical properties of MWCNT film is crucial in process optimization of MWCNT film-based products. In the present work, the electrical conduction property of MWCNT films according to various conditions in MWCNT dispersion is investigated. Spectroscopic analysis of dispersed MWCNTs show that the electrical resistance of the MWCNT conductive film is affected by an increase in the electrical contacts between adjacent CNTs due to CNT debundling and physical damage caused by ultrasonic processing. Based on the two conflicting parameters, dispersion guidelines for highly conductive MWCNT film are presented.</P>

Changes in Dietary Fiber Content of Flesh and Peel in Three Cultivars of Asian Pears during Growth

Xian Zhang,Chang-Su Na,Jeong-Sang Kim,Fan-Zhu Lee,Jong-Bang Eun 한국식품과학회 2003 Food Science and Biotechnology Vol.12 No.4

IDD10 is Involved in the Interaction between NH4+ and Auxin Signaling in Rice Roots

Chang-Deok Han,Yuan Hu Xuan,Vikranth Kumar,Xiao Feng Zhu,Byoung Il Je,Chul Min Kim,Jin Huang,Jun Hyeon Cho,Gihwan Yi 한국식물학회 2018 Journal of Plant Biology Vol.61 No.2

NH4+ is an important nitrogen resource for rice plantsin paddy soil. Therefore, it is likely that NH4+-triggered plantgrowth interacts with phytohormone-mediated developmentalmechanisms. Our previous transcriptomic analysis revealedthat many genes involved in auxin signaling and efflux aresensitive to NH4+. In the current study, we found that NH4+treatment causes a delayed gravity response in rice roots. Tofurther elucidate the interlocking relationship between NH4+and auxin signaling during root development, we utilizedmutants and overexpressors of a key NH4+ signaling transcriptionfactor INDETERMINATE DOMAIN 10 (IDD10), encoding atranscription factor that regulates the expression of NH4+uptake and N-assimilation genes. We obtained several linesof evidence that auxin affects NH4+-mediated gene expressionand root development in rice plants via IDD10. First, thegravity response was delayed in idd10 roots and acceleratedin IDD10 overexpressor (IDD10 OX) roots in the absenceand (especially) presence of NH4+. Second, idd10 plantsshowed strong root coiling only in the presence of NH4+. However, treatment of 1-N-naphthylphthalamic acid (NPA),a polar auxin transport inhibitor suppressed the NH4+-specific root phenotype of idd10. Third, the expression ofNH4+-responsive auxin-related genes was affected in idd10and IDD10 overexpressors. Finally, IDD10 expression wasinduced by IAA and suppressed by NPA. These findingssuggest that the gene expression patterns and phenotypestriggered by NH4+ are influenced by the actions of auxinduring root development, pointing to a regulatory circuitbetween NH4+ and auxin signaling that functions in rootdevelopment in rice.

Antimicrobial effect of alexidine and chlorhexidine against <i>Enterococcus faecalis</i> infection

Kim, Hyun-Shik,Woo Chang, Seok,Baek, Seung-Ho,Han, Seung Hyun,Lee, Yoon,Zhu, Qiang,Kum, Kee-Yeon Nature Publishing Group 2013 International journal of oral science. Vol.5 No.1

<P>A previous study demonstrated that alexidine has greater affinity for the major virulence factors of bacteria than chlorhexidine. The aim of this study was to compare the antimicrobial activity of 1% alexidine with that of 2% chlorhexidine using <I>Enterococcus faecalis</I>-infected dentin blocks. Sixty bovine dentin blocks were prepared and randomly divided into six groups of 10 each. <I>E. faecalis</I> was inoculated on 60 dentin blocks using the Luppens apparatus for 24 h and then the dentin blocks were soaked in 2% chlorhexidine or 1% alexidine solutions for 5 and 10 min, respectively. Sterile saline was used as a control. The antimicrobial efficacy was assessed by counting the number of bacteria adhering to the dentin surface and observing the degradation of bacterial shape or membrane rupture under a scanning electron microscope. Significantly fewer bacteria were observed in the 2% chlorhexidine- or 1% alexidine-soaked groups than in the control group (<I>P</I><0.05). However, there was no significant difference in the number of bacteria adhering to the dentinal surface between the two experimental groups or between the two soaking time groups (<I>P</I>>0.05). Ruptured or antiseptic-attached bacteria were more frequently observed in the 10-min-soaked chlorhexidine and alexidine groups than in the 5-min-soaked chlorhexidine and alexidine groups. In conclusion, 10-min soaking with 1% alexidine or 2% chlorhexidine can be effective against <I>E. faecalis</I> infection.</P>

Raman Characterization of Thermal Conduction in Transparent Carbon Nanotube Films

Kim, Duckjong,Zhu, Lijing,Han, Chang-Soo,Kim, Jae-Hyun,Baik, Seunghyun American Chemical Society 2011 Langmuir Vol.27 No.23

<P>Using materials with high thermal conductivity is a matter of great concern in the field of thermal management. In this study, we present our experimental results on two-dimensional thermal conductivity of carbon nanotube (CNT) films obtained by using an optical method based on Raman spectroscopy. We use four kinds of CNTs in film preparation to investigate the effect of CNT type on heat spreading performance of CNT films. This first comparative study using the optical method shows that the arc-discharge single-walled carbon nanotubes yield the best heat spreading film. We also show that the Raman method renders reasonable thermal conductivity value as long as the sample is a transparent film by testing CNT films with various transmittance. This study provides useful information on characterization of thermal conduction in transparent CNT films and could be an important step toward high-performance carbon-based heat spreading films.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2011/langd5.2011.27.issue-23/la203007y/production/images/medium/la-2011-03007y_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la203007y'>ACS Electronic Supporting Info</A></P>