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Seo, Jung Yoon,Praveenkumar, Ramasamy,Kim, Bohwa,Seo, Jeong-Cheol,Park, Ji-Yeon,Na, Jeong-Geol,Jeon, Sang Goo,Park, Seung Bin,Lee, Kyubock,Oh, You-Kwan The Royal Society of Chemistry 2016 GREEN CHEMISTRY Vol.18 No.14
<P>Microalgal biofuel, albeit an exciting potential fossil-fuel-replacement candidate, still requires the development of more advanced downstream processing technology for its price competitiveness. The major challenge in a microalgae-based biorefinery is the efficient separation of microalgae from low-concentration culture broth. The post-harvesting cell-disruption step necessary to render microalgae suitable for lipid extraction, moreover, further raises energy consumption and cost. For the mitigation of biorefinery complexity and costs, we suggest herein a new scheme that integrates the critical downstream processes (harvesting and cell disruption) by means of cationic surfactant-decorated Fe3O4 nanoparticles. The cationic surfactants' quaternary ammonium heads play an important role in not only flocculating negatively charged microalgae but also weakening thick cell walls. In the present study, the harvesting efficiency and cell-damaging effects of three cationic surfactants - cetrimonium bromide (CTAB), cetylpyridinium chloride (CPC), and cetylpyridinium bromide (CPB) - were evaluated. The CTAB-decorated Fe3O4 nanoparticles, which were found to be the most effective, achieved a 96.6% microalgae harvesting efficiency at a dosage of 0.46 g particle per g cell. Next, for the purposes of magnetic nanoparticle recycling and high-purity microalgal biomass obtainment, microalgae detachment from microalgae-Fe3O4 flocs was performed by addition of an anionic surfactant, sodium dodecyl sulfate (SDS). The detached CTAB-decorated Fe3O4 nanoparticles showed a steady reuse efficiency of about 80%. Furthermore, microalgae harvesting by CTAB-decorated Fe3O4 nanoparticles could contribute to a great improvement in the total extracted lipid content and greener wet extraction without the additional energy-intensive cell-disruption step, thus demonstrating the cell-disruption ability of CTAB-decorated Fe3O4 nanoparticles.</P>
Comparison of hot spot stress evaluation methods for welded structures
Seo, Jung-Kwan,Kim, Myung-Hyun,Shin, Sang-Beom,Han, Myung-Soo,Park, June-Soo,Mahendr, Mahen,Lee, Jae-Myung The Society of Naval Architects of Korea 2010 International Journal of Naval Architecture and Oc Vol.2 No.4
In this paper, different evaluation methods of Hot Spot Stresses (HSS) have been applied to four different welded structure details in order to compare them and to illustrate their differences. The HSSs at failure-critical locations were calculated by means of a series of finite element analyses. There was good overall agreement between calculated and experimentally determined HSS on the critical locations. While different methods and procedures exist for the computation of the structural hot-spot stress at welded joints, the recommendations within the International Institute of Welding (IIW) guideline concerning the 'Hot Spot Stress' approach were found to give good reference stress approximations for fatigue-loaded welded joints. This paper recommends and suggests an appropriate finite element modeling and hot spot stress evaluation technique based on round-robin stress analyses and experimental results of several welded structure details.
( Sang Jun Suh ),( Hyung Joon Yim ),( Young-sun Lee ),( Han Ah Lee ),( Tae Hyung Kim ),( Sun Young Yim ),( Young Kul Jung ),( Ji Hoon Kim ),( Yeon Seok Seo ),( Jong Eun Yeon ),( Kwan Soo Byun ),( Soon 대한간학회 2018 춘·추계 학술대회 (KASL) Vol.2018 No.1
Aims: Various models for the prediction of hepatocellular carcinoma (HCC) in the patients with chronic hepatitis B (CHB) were suggested. The aim of study is to identify if the HCC risk scores are improved as antiviral therapy is prolonged in the patients with CHB-related liver cirrhosis. Methods: The patients with CHB who received entecavir (ETV) or tenofovir (TDF) were investigated retrospectively. Patients with liver cirrhosis patients diagnosed by sonography, CT or biopsy were enrolled. We calculated the HCC risk scores at pre-antiviral therapy, and each year from year 1 to 5 of post-antiviral therapy. The models were GAG-HCC, CU-HCC, REACH-B, modified REACH-B (mREACH-B), LSM-HCC, and PAGE-B. The primary endpoint was decrease of the risk scores after antiviral therapy. The secondary endpoint was finding the best model by AUROC after antiviral therapy. Results: A total of 362 patients were enrolled, and 198 and 164 patients were treated by ETV and TDF respectively. Child- Pugh scores were 5.7±1.3 and MELD were 9.9±3.8. Fifty six patient (15.5 %) occurred HCC at median 1.6 years (0.1-9.7 years). Most HCC scores (GAG, CU-HCC, REACH-B) decreased at year 1 and plateaued from year 1 to 5. mREACH-B and LSM-HCC scores decreased until year 2 and plateaued after year 2. PAGE-B showed no decrease from pre to post-antiviral therapy. The AUROC of PAGE-B was largest at baseline (GAG-HCC 0.472, CU-HCC 0.753, REACH-B 0.633, mREACH-B 0.688, LSM-HCC 0.649, and PAGE-B 0.760). After antiviral therapy, the AUROC changed. AUROCs of models employing HBV DNA levels increased (GAG-HCC, REACH-B, and LSM-HCC), that of liver stiffness based models (mREACH-B and PAGE-B) were persistent, and that of models employing hepatic function (CU-HCC) decreased (GAG-HCC 0.582, CU-HCC 0.686, REACH-B 0.689, mREACH-B 0.689, LSM-HCC 0.716, and PAGE-B 0.755 at 1year). The decrease of scores from baseline to each years were not different between ETV and TDF (all P>0.05). AUROC were largest in PAGE-B, however the scores were not changed after antiviral therapy. Second largest AUROC is that of LSM-HCC at year 1 and its AUROC became larger after antiviral therapy Conclusions: In conclusion, HCC prediction models such as PAGE-B and LSM-based models worked well in patients with HBV-related cirrhosis and decrease of the scores was associated with effects of the antiviral therapy.
Seo, Ju Hee,Park, Jun Chul,Kim, Yu Jin,Shin, Sung Kwan,Lee, Yong Chan,Lee, Sang Kil S. Karger AG 2010 Digestion Vol.81 No.1
<P><I>Background:</I> Endoscopic resection (endoscopic mucosal resection, EMR, and endoscopic submucosal dissection, ESD) has been accepted worldwide as a less invasive standard treatment for early gastric cancer (EGC). However, the risk of synchronous and metachronous gastric cancer developing in the post-endoscopic resection patient has become a major problem. We investigated the incidence and characteristics of synchronous and metachronous multiple gastric cancers in a retrospective study of patients with EGC after endoscopic resection. <I>Patients and Methods:</I> We studied the clinicopathological features of 235 patients with EGC who had undergone endoscopic resection and were periodically followed up using endoscopic examinations (181 with a single lesion, 34 synchronous multiple lesions, and 20 metachronous multiple lesions). <I>Results:</I> The overall incidence of synchronous and metachronous multiple gastric cancer was 14.5 and 8.5%, respectively, during a follow-up of 12-77 (median 26.5) months. Undifferentiated histology of the primary lesion was related to the occurrence of synchronous gastric cancer (p < 0.001). Undifferentiated histology and upper location of the primary lesion were correlated with the occurrence of metachronous gastric cancer (p = 0.002, 0.001). Most synchronous and metachronous lesions were well to moderately differentiated (82.4 and 80.0%); however, the proportion with undifferentiated histology (including poorly differentiated carcinoma and signet ring cell carcinoma) in synchronous and metachronous gastric cancer was significantly higher than in single gastric cancer (p = 0.008). <I>Conclusions:</I> Undifferentiated histology of EGC may predict the occurrence of synchronous and metachronous lesions after endoscopic resection.</P><P>Copyright © 2009 S. Karger AG, Basel</P>
( Sang Jun Suh ),( Jong Eun Yeon ),( Sun Jae Lee ),( Hyun Jung Lee ),( Eileen L. Yoon ),( Ji Hoon Kim ),( Yeon Seok Seo ),( Hyung Joon Yim ),( Kwan Soo Byun ) 대한간학회 2012 춘·추계 학술대회 (KASL) Vol.2012 No.1
Background: Current guidelines suggest the criteria for discontinuation of nucleos(t)ide analogues (NA) in selected patients. However treatment induced virological response is not permanent. Aim of our study is to evaluate the clinical significance of HBsAg titer in predicting sustained virologic response after NA therapy discontinuation. Methods: From Jun 1998 to Dec 2010, medical record of 81 chronic hepatitis B patients who discontinued NA was analyzed retrospectively. Sustained virologic response (SVR) was arbitrarily defined as undetectable HBV DNA by real-time PCR(with lower limit of detection of 116 copies/mL, 20 IU/mL) persisted more than 12 months after treatment discontinuation. Results: Median age was 51 years, 54 (67%) patients were male, and 50 (62%)patients were HBeAg positive. Median baseline ALT, HBV DNA and HBsAg were 292 IU/mL, 7.1log10 IU/mL and 3.3log10 IU/mL. NA were lamivudine (n=53), adefovir (n=15), lamivudine combined with adefovir (n=4), and entecavir (n=9). Median treatment duration and follow-up period were 26 and 27 months. 11/81 (14%) patients had SVR. The cumulative relapse rates were 37/81 (46%) at 6 months and 42/81 (52%) 12 months after treatment discontinuation. The baseline ALT, HBV DNA and presence of HBeAg were not different between patients with or without SVR. In univariate analysis, age, treatment duration and HBsAg level at treatment discontinuation were different in patients with or without SVR; 51 vs. 43 years, p=0.033; 53 vs. 25 months, p=0.011; 2.1 vs. 3.3log10 IU/mL, p=0.003. In multivariate analysis, only HBsAg level at treatment discontinuation remained as an independent factor associated with SVR (p=0.019). The cutoff value of HBsAg level <2log10 IU/mL was predictive of SVR [(AUROC, 0.991; 95% confidence interval[CI], 0.000-1.000; p<0.05); sensitivity, 100%; specificity, 93%; positive predictive value, 69%; negative predictive value, 100%]. Conclusions: Large proportion of patients treated with oral antivirals relapsed after the treatment discontinuation. In the decision of the treatment discontinuation, HBsAg level <2log10 IU/mL at treatment discontinuation can predict sustained viral suppression in selected patients.