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Effects of Ag Seed on Synthesis of FeCo Nano-Particles Prepared via the Polyol Method

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Journal of Materials Science & Technology 2010年第7期26卷 660-664页

作者： Uk-Rae Cho Geun-Woo Kim Bon-Heun koo School of Nano and Advanced Materials Engineering Changwon National UniversityChangwonGyeongnam641-773Korea

Nano-particles have several interesting properties which are not shown in bulk materials because of their high ratio of surface area to volume. FeCo alloy nano-particles with soft magnetic properties are demanded for various applications such as optics, eletronics and magnetics. Through the polyol method, highly purified particles with mono-dispersibility in various sizes can be produced and used as high-tech functional materials. In this study, the magnetic characteristics of FeCo alloy with Ag seed added in the production process of mono-dispersed nano-particles through the polyol method were investigated.

关键词： Polyol method FeCo Ag Seed

维普期刊数据库

All-fiber acousto-optic modulator based on a cladding-etched optical fiber for active mode-locking

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Photonics Research 2017年第5期5卷 391-395页

作者： JIHWAN KIM JOONhoi koo JU HAN LEE School of Electrical and Computer Engineering University of Seoul

An all-fiber acousto-optic modulator(AOM), which features a compact structure and a low-driving voltage, is experimentally demonstrated for the active mode-locking of a fiber laser. The proposed AOM is based on the short length of the cladding-etched fiber, the ends of which are fixed on a slide glass. On top of the cladding-etched fiber, a piezoelectric transducer was overlaid. A chemical wet-etching technique, which is based on a mixed solution of NH_4F and (NH_4)2SO_4, is used to reduce the fiber diameter down to ～25 μm, and the length of the etched section is only 0.5 cm. The fabricated device exhibited a modulation depth of 73.10% at an acoustic frequency of 918.9 kHz and a peak-to-peak electrical voltage of 10 V, while a laser beam was coupled at 1560 *** using the prepared AOM within an erbium-doped-fiber ring cavity, the mode-locked pulses with a temporalwidth of 2.66 ps were readily obtained at a repetition rate of 1.838 MHz.

关键词： All-fiber acousto-optic modulator based on a cladding-etched optical fiber for active mode-locking

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DNA-directed assembly of copper nanoblocks with inbuilt fluorescent and electrochemical properties： Application in simultaneous amplification-free analysis of multiple RNA species

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Nano Research 2018年第2期11卷 940-952页

作者： Kevin M. koo Laura G. Carrascosa Matt Trau Centre for Personalized Nanomedicine Australian Institute for Bioengineering and Nanotechnology (AIBN) The University of Queensland Brisbane Australia School of Chemistry and Molecular Biosciences The University of Queensland Brisbane Australia

The intrinsic affinity of DNA molecules toward metallic ions can drive the specific formation of copper nanostructures within the nucleic acid helix structure in a sequence-dependent manner. The resultant nanostructures have interesting fluorescent and electrochemical properties, which are attractive for novel biosensing applications. However, the potential of using DNA-templated nano- structures for precision disease diagnosis remains unexplored. Particularly, DNA- templated nanostructures show high potential for the universal amplification-free detection of different RNA biomarker species. Because of their low cellular levels and differing species-dependent length and sequence features, simultaneous detection of different messenger RNAs, microRNAs, and long non-coding RNAs species with a single technique is challenging. Here, we report a contemporary technique for facile in situ assembly of DNA-templated copper nanoblocks （CuNBs） on various RNA species targets after hybridization-based magnetic isolation. Our approach circumvents the typical limitations associated with amplification and labeling procedures of current RNA assays. The synthesized CuNBs enabled amplification-free fM-level RNA detection with flexible fluorescence or electrochemical readouts. Furthermore, our nanosensing technique displays potential for clinical application, as demonstrated by non-invasive analysis of three diagnostic RNA biomarkers from a cohort of 10 prostate cancer patient urinary samples with 100%-concordance （quantitative reverse transcription- polymerase chain reaction （PCR） validation）. The good analytical performance and versatility of our method may be useful in both diagnostics and research fields.

关键词： prostate cancer RNA detection DNA-templated coppernanostTuctures amplification-free fluorescence detection electrochemical detection

Structure descriptor for surface passivation in the simulation of atomistic models

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Science China(Information Sciences) 2017年第3期60卷 68-77页

作者： Li CAO Siukong koo Jian SUN Guanhua CHEN Wenping WANG Department of Computer Science The University of Hong Kong Department of Chemistry The University of Hong Kong

Surface passivation is an essential step for atomistic simulations. There can be many possible surface passivation results for a given device model, such as semiconductor devices that consist of Si, Ga As, or other materials because the bonding directions of the surface atoms may not be unique. Based on the structure analysis of the given model, a generation method with structure descriptor(SDG) is proposed for surface *** with other existing solutions, the SDG method not only provides trimmer results, but also reduces the torsion angle energy of the model, which is preferred in the simulation of atomistic models. The efficiency of this method was validated through test results from several applications.

关键词： computer aided design structure analysis torsion angle universal force field surface passivation atomistic model

New prognostic model for patients with advanced gastric cancer:Fluoropyrimidine/platinum doublet for first-line chemotherapy

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World Journal of Gastroenterology 2021年第48期27卷 8357-8369页

作者： Dong-Hoe koo Min-Hee Ryu Mi-Yeon Lee Mee-Sun Moon Yoon-koo Kang Division of Hematology/Oncology Department of Internal MedicineKangbuk Samsung HospitalSungkyunkwan University School of MedicineSeoul 03181South Korea Department of Oncology Asan Medical CenterUniversity of Ulsan College of MedicineSeoul 05505South Korea Division of Biostatistics Department of R&D ManagementKangbuk Samsung HospitalSeoul 03181South Korea

BACKGROUND New prognostic factors have been reported in patients with metastatic or recurrent gastric cancer(MRGC),necessitating modifications to the previous prognostic *** To develop a new model,MRGC patients who received fluoropyrimidines/platinum doublet chemotherapy between 2008 and 2015 were *** A total of 1883 patients was divided into a training set(n=937)and an independent validation set(n=946).RESULTS Multivariate analysis showed that the following six factors were associated with poor overall survival(OS)in the training set:Eastern Cooperative Oncology Group performance score≥2 and bone metastasis(2 points each),peritoneal metastasis,high alkaline phosphatase level,low albumin level,and high neutrophil-lymphocyte ratio(1 point each).A prognostic model was developed by stratifying patients into good(0-1 point),moderate(2-3 points),and poor(≥4 points)risk *** the validation set,the median OS of the three risk groups was 15.8,10.1,and 5.7 mo,respectively,and those differences were significant(P<0.001).CONCLUSION We identified six factors readily measured in clinical practice that are predictive of poor prognosis in patients with *** new model is simpler than the old and more easily predicts OS.

关键词： Stomach neoplasms Chemotherapy Prognosis Validation Gastric cancer

Fabrication of sintering-free flexible copper nanowire/ polymer composite transparent electrodes with enhanced chemical and mechanical stability

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Nano Research 2016年第7期9卷 2162-2173页

作者： Cho Rong Chu Changsoo Lee Jahyun koo Hyuck Mo Lee Department of Materials Science and Engineering KAIST 291 Daehak-ro Yuseong-gu Daejeon 305-701 Republic of Korea

The thermal decomposition synthesis of long copper nanowires （CuNWs） was achieved by controlling the synthesis parameters. A detailed study was performed to determine the effect of the molar ratio of copper chloride to nickel acetylacetonate, temperature, and stirring rate on the final shape of the products. Transparent electrodes （TEs） were fabricated by wet treatment with acetic acid （AA）, without using a sintering process. The low oxidation stability and high surface roughness are the main disadvantages of the CuNW TEs, which limit their applications. In order to overcome these issues, we prepared CuNW/polymer composite TEs by partial embedding of the CuNWs into poly（methyl methacrylate）（PMMA） on poly（ethylene terephthalate）（PET） substrates. The CuNW/PMMA composite TEs exhibit excellent optoelectronic performance （91.3% at 100.7 ff2/sq）, low surface roughness （4.6 nm in height）, and good mechanical and chemical stability as compared with CuNW TEs. On the basis of these properties, we believe that CuNW-based composite TEs could serve as low-cost materials for a wide range of new optoelectronic devices.

关键词： copper nanowires nanowire/polymercomposite transparent electrode chemical stability mechanical stability

Radiation therapy for extrahepatic bile duct cancer: Current evidences and future perspectives

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World Journal of Clinical Cases 2019年第11期7卷 1242-1252页

作者： Taeryool koo Hae Jin Park Kyubo Kim Department of Radiation Oncology Hallym University Sacred Heart Hospital Anyang 14068 South Korea Department of Radiation Oncology Hanyang University College of Medicine Seoul 04763 South Korea Department of Radiation Oncology Ewha Womans University College of Medicine Seoul 07985 South Korea

Extrahepatic bile duct cancer (EBDC) is a rare malignancy that involves neoplastic changes extending from both hepatic ducts to the common bile duct. The treatment of choice is surgical resection, but the predominant pattern of initial treatment failure is locoregional recurrence. Accordingly, adjuvant radiotherapy has been administered after surgical resection based on these rationales. At this time, there is minimal evidence supporting adjuvant radiotherapy, because there have been no phase III trials evaluating its benefit. Relatively small retrospective studies have tried to compare outcomes associated with EBDC treated with or without radiotherapy. We aimed to review studies investigating adjuvant radiotherapy for resected EBDC. Because less than onethird of EBDC cases are amenable to curative resection at diagnosis, other locoregional treatment modalities need to be considered, including radiotherapy. The next aim of this review was to summarize reports of definitive radiotherapy for unresectable EBDC. Patients with advanced EBDC often experience biliary obstruction, which can lead to jaundice and progress to death. Biliary stent insertion is an important palliative procedure, but stents are prone to occlusion after subsequent ingrowth of the EBDC. Radiotherapy can be effective for maintaining the patency of inserted stents. We also reviewed the benefit of palliative radiotherapy combined with the biliary stent insertion. Lastly, we discuss the existing gaps in the evidence supporting radiotherapy in the management of EBDC.

关键词： Extrahepatic bile duct cancer Patterns of failure Adjuvant radiotherapy Definitive radiotherapy Palliative radiotherapy Biliary stent

Stress and sleep quality in doctors working on-call shifts are associated with functional gastrointestinal disorders

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World Journal of Gastroenterology 2017年第18期23卷 3330-3337页

作者： Soo-kyung Lim Seung Jin Yoo Dae Lim koo Chae A Park Han Jun Ryu Yong Jin Jung Ji Bong Jeong Byeong Gwan Kim kook Lae Lee Seong-Joon Koh Department of Internal Medicine Seoul National University College of MedicineSeoul National University Boramae Hospital Department of Neurology Seoul National University Boramae HospitalSeoul National University College of Medicine

To investigate the role of sleep quality and psychosocial problems as predictors of functional gastrointestinal disorders (FGIDs) in doctors that work 24 hour-on-call *** this cross-sectional observation study, using the Rome III Questionnaire and Pittsburgh Sleep Quality Index (PSQI), we analyzed 170 doctors with 24 hour-on-call *** the participants that had experienced a 24 hour-on-call shift within the last 6 mo, 48 (28.2%) had FGIDs. Overall prevalence of irritable bowel syndrome (IBS) and functional dyspepsia (FD) were 16.5% and 17.1%, respectively, with 5.3% exhibiting both. Sleep scores (PSQI) (8.79 ± 2.71 vs 7.30 ± 3.43, P = 0.008), the presence of serious psychosocial alarm (83.3% vs 56.6%, P = 0.004), and the proportion of doctors who experienced over two months of recent on-call work (81.2% vs 68.9%, P = 0.044) were significantly different between individuals with or without FGIDs. Multivariate analysis revealed that presenting serious psychosocial alarm was an independent risk factor for prevalence of FD (OR = 5.47, 95%CI: 1.06-28.15, P = 0.042) and poor sleep quality (PSQI ≥ 6) was a predictor of IBS (OR = 4.17, 95%CI: 1.92-19.02, P = 0.016).CONCLUSIONPhysicians should recognize the role of sleep impairment and psychological stress in the development of FGIDs and a comprehensive approach should be considered to manage patients with FGIDs.

关键词： Psychosocial stress Sleep 24 hour-on-call shift Doctors Functional gastrointestinal disorders

Expression of E-cadherin and α-catenin in a varicocele-induced infertility rat model

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Asian Journal of Andrology 2011年第3期13卷 470-475,514页

作者： Hong koo Ha Hyun Jun Park Nam Cheol Park Department of Urology Pusan National University School of Medicine Busan 602739 Korea Medical Research Institute Pusan National University Hospital Busan 602739 Korea

The roles of E-cadherin and α-catenin were evaluated in the development of varicocele-induced infertility. Analysis of the association between the expression of E-cadherinla-catenin and clinical/pathological parameters was performed. Thirty lO-week-old male rats （experimental group） were used for the experiments; the left renal vein was ligated to form a varicocele. The abdomen was incised in 30 rats （control group） and no procedure was performed on 10 rats （baseline group）. The weights of the left testis, serum reactive oxygen species （ROS）, testosterone, luteinizing hormone （LH）, follicle-stimulating hormone （FSH） and degenerative changes in the seminiferous tubules after 4 and 8 weeks were recorded. The expression of E-cadherin and α-catenin was evaluated by immunohistochemical （IHC） staining and Western blot analysis. The ROS increased in the 8-week experimental group, compared with the baseline and control groups （P〈0.001 for both）. Additionally, FSH significantly increased in the 4- and 8-week experimental group compared with the control groups （P= 0.013 and P= 0.032, respectively）. The ratio of degenerative changes in the seminiferous tubules of the experimental groups increased. The IHC staining showed that the expression of E-cadherin and a-catenin decreased in the 4- and 8-week experimental groups. Similar to the IHC staining, the experimental group had decreased reactivity on Western blot analysis. The expression of E-cadherin and a-catenin was significantly associated with the ROS and degenerative changes in the seminiferous tubules. The results of this study suggest that damage to the blood-testis barrier （BTB） is associated with varicocele-induced male infertility, and that ROS may cause damage to the BTB.

关键词： α-catenin blood-testis barrier E-cadherin varicocele infertility