Magnetic Properties of Carbon-Coated Ni Nanoparticles Prepared by Solid-Phase Pyrolysis of Nickel-Phthalocyanine

Aram Manukyan,Armen Mirzakhanyan,Laszlo Sajti,Ruben Khachaturyan,Egor Kaniukov,Leonid Lobanovsky,Eduard Sharoyan 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.6

Carbon-coated nickel nanoparticles with a mean diameter of 40 nm were synthesized via solid-phase pyrolysis of nickel-phthalocyanine. The composition structure and morphology of samples were investigated by scanning and transmission electron microscopy, X-ray diffraction, Raman spectroscopy and energy-dispersive X-ray microanalysis. Magnetic characteristics of samples were measured with a vibrational magnetometer and a magnetic resonance spectrometer. The main mass of Ni ferromagnetic nanoparticles have a single-domain and a vortex (pseudo-single domain) structures. We also revealed superparamagnetic Ni nanoparticles (several percent) and carbon paramagnetic centers caused by defects in the carbon matrix. We determined the main magnetic characteristics of Ni nanoparticles, their temperature and field dependences as well as the parameters of ferromagnetic resonance spectra.

The Impact of Portfolio Assessment on Learners’ Achievement

Hossein Farhady,Gayane Manukyan 한국영어평가학회 2010 영어평가 Vol.4 No.1

The purpose of the present study was to investigate the extent to which portfolio assessment may influence learners’ achievement, their learning process, and their attitude towards assessment for learning English. From the two groups involved in the study, the focus group received portfolio assessment whereas the comparison group received placebo. The instruments used were: 1) pre and post instruction tests, 2) pre and post instruction attitudinal questionnaires for students, 3) self-assessment checklists, 4) questionnaire on portfolio assessment-and 5) semi-structured interview with students on portfolio assessment. The pre and post instruction test data was analyzed through non-parametric Kruskal-Wallis test, which showed a significant difference between the comparison and the focus groups. In order to see the relationship between self-assessment checklist scores and the progress test scores, Spearman’s rank order correlation showed high correlation between the two sets of scores. Cross-case analysis of the content of the interview data was performed after categorizing the questions into “attitude” and “learning” items. Each category was analyzed separately in order to group the most common answers. The results of the questionnaires and interviews showed that portfolio assessment had positive effect on students’ achievement. The students reported that the process of portfolio assessment enabled them to be actively involved in the learning process.

Prognostic Impact of the Metastatic Lymph Node Ratio on Survival in Rectal Cancer

Wafi Attaallah,Omer Gunal,Manuk Manukyan,Gulden Ozden,Cumhur Yegen 대한대장항문학회 2013 Annals of Coloproctolgy Vol.29 No.3

Purpose: Lymph-node metastasis is the most important predictor of survival in stage III rectal cancer. The number of metastatic lymph nodes may vary depending on the level of specimen dissection and the total number of lymph nodes harvested. The aim of this study was to evaluate whether the lymph node ratio (LNR) is a prognostic parameter for patients with rectal cancer. Methods: A retrospective review of a database of rectal cancer patients was performed to determine the effect of the LNR on the disease-free survival (DFS) and the overall survival. Of the total 228 patients with rectal cancer, 55 patients with stage III cancer were eligible for analysis. Survival curves were estimated using the Kaplan-Meier method. Cox regression analyses, after adjustments for potential confounders, were used to evaluate the relationship between the LNR and survival. Results: According to the cutoff point 0.15 (15%), the 2-year DFS was 95.2% among patients with a LNR < 0.15 compared with 67.6% for those with LNR ≥ 0.15 (P = 0.02). In stratified and multivariate analyses adjusted for age, gender, histology and tumor status, a higher LNR was independently associated with worse DFS. Conclusion: This study showed the prognostic significance of ratio-based staging for rectal cancer and may help in developing better staging systems. LNR 0.15 (15%) was shown to be a cutoff point for determining survival and prognosis in rectal cancer cases.

Combustion synthesis of zero-, one-, two- and three-dimensional nanostructures: Current trends and future perspectives

Nersisyan, Hayk H.,Lee, Jong Hyeon,Ding, Jin-Rui,Kim, Kyo-Seon,Manukyan, Khachatur V.,Mukasyan, Alexander S. Elsevier 2017 Progress in energy and combustion science Vol.63 No.-

<P><B>Abstract</B></P> <P>The combustion phenomenon is characterized by rapid self-sustaining reactions, which can occur in the solid, liquid, or gas phase. Specific types of these reactions are used to produce valuable materials by different combustion synthesis (CS) routes. In this article, all three CS approaches, i.e. solid-phase, solution, and gas-phase flame, are reviewed to demonstrate their attractiveness for fabrication of zero-, one-, two-, and three-dimensional nanostructures of a large variety of inorganic compounds. The review involves five sections. First, a brief classification of combustion synthesis methods is given along with the scope of the article. Second, the state of art in the field of solid-phase combustion synthesis is described. Special attention is paid to the relationships between combustion parameters and structure/properties of the produced nanomaterials. The third and fourth sections describe details for controlling material structures through solution combustion synthesis and gas-phase flame synthesis, respectively. A variety of properties (e.g., thermal, electronic, electrochemical, and catalytic) associated with different types of CS nanoscale materials are discussed. The conclusion focuses on the most promising directions for future research in the field of advanced nanomaterial combustion synthesis.</P>

The comparison of single incision laparoscopic cholecystectomy and three port laparoscopic cholecystectomy

Ugur Deveci,Umut Barbaros,Mahmut Sertan Kapakli,Manuk Norayk Manukyan,Selcuk ?im?ek,Abut Kebudi,Selcuk Mercan 대한외과학회 2013 Annals of Surgical Treatment and Research(ASRT) Vol.85 No.6

Purpose: Laparoscopic techniques have allowed surgeons to perform complicated intra-abdominal surgery with minimal trauma. Single incision laparoscopic surgery (SILS) was developed with the aim of reducing the invasiveness of conventional laparoscopy. In this study we aimed to compare results of SILS cholecystectomy and three port conventional laparoscopic (TPCL) cholecystectomy prospectively. Methods: In this prospective study, 100 patients who underwent laparoscopic cholecystectomy for gallbladder disease were randomly allocated to SILS cholecystectomy (group 1) or TPCL cholecystectomy (group 2). Demographics, pathologic diagnosis, operating time, blood loss, length of hospital stay, complications, pain score, conversion rate, and satisfaction of cosmetic outcome were recorded. Results: Forty-four SILS cholesystectomies (88%) and 42 TPCL cholecystectomies (84%) were completed successfully. Conversion to open surgery was required for 4 cases in group 1 and 6 cases in group 2. Operating time was significantly longer in group 1 compared with group 2 (73 minutes vs. 48 minutes; P < 0.05). Higher pain scores were observed in group 1 versus group 2 in postoperative day 1 (P < 0.05). There was higher cosmetic satisfaction in group 1 (P < 0.05). Conclusion: SILS cholecystectomy performed by experienced surgeons is at least as successful, feasible, effective and safe as a TPCL cholecystectomy. Surgeons performing SILS should have a firm foundation of advanced minimal access surgical skills and a cautious, gradated approach to attempt the various procedures. Prospective randomized studies comparing single access versus conventional multiport laparoscopic cholecystectomy, with large volumes and long-term followup, are needed to confirm our initial experience. (ClinicalTrials.gov Identifier:NCT01772745.)