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Wear Resistant Duplex Stainless Steels Produced by Spray Forming
Juliano Soyama,Thiago Pama Lopes,Guilherme Zepon,Claudio Shyinti Kiminami,Walter José Botta,Claudemiro Bolfarini 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.2
In this work, boron-modified duplex stainless steels were prepared by spray forming using design guidelines provided bythermodynamic calculations. Firstly, an investigation of stable phases and phase formation sequence in duplex steels containinghigh levels of boron was conducted. The calculation indicated that there was an eutectic point at around 1 wt% boron withdifferent primary phase formations upon equilibrium solidification. For hypoeutectic compositions, the primary phase wasδ-Ferrite, whereas for hypereutectic a metallic boride (M2B) should form. Additionally, eutectic reactions for both compositionsshould lead to the formation of borides M2Band M3B2. Secondly, spray forming experiments were conducted basedon the thermodynamic calculations. Sample preparation was carried out using a conventional superduplex steel (2507) asstarting material. Two different compositions were selected: one hypoeutectic (0.8 wt% B) and one hypereutectic (2.5 wt%B). The microstructural investigation revealed the formation of different types of borides embedded in an austenitic-ferriticmatrix. Finally, the wear resistance was evaluated with the dry sand/rubber wheel test and a significant improvement wasobserved for boron-containing steels in comparison with the same steel without boron. This improvement was attributed tothe presence of fine and well-distributed boride particles that protected the austenitic-ferritic matrix from material removal.
[ ] Prepared by Calciothermic Reduction-Diffusion Using Different Iron Powders
Boareto J.C.,Soyama J.,Felisberto M.D.V.,Hesse R.,Pinto A.V.A.,Taylor T.R.,Wendhausen P.A.P. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
This paper compares the effect of using different types of iron powders for the preparation of by calciothermic reduction-diffusion (CRD). Three types of iron powder were used: carbonyl, sponge and water atomized. The results show that, when immediately nitrogenated after the CRD process, prepared from sponge and water atomized iron powders yield -magnets with a high degree of texture. However, after a suitable treatment with hydrogen followed by nitrogenation, -powders made from Carbonyl iron produce magnets with the best quality regarding coercivity, remanence and degree of texture.
Inhibition of autophagy protein LC3A as a therapeutic target in ovarian clear cell carcinomas
Morikazu Miyamoto,Masashi Takano,Tadashi Aoyama,Hiroaki Soyama,Tomoyuki Yoshikawa,Hitoshi Tsuda,Kenichi Furuya 대한부인종양학회 2017 Journal of Gynecologic Oncology Vol.28 No.3
Objective: Ovarian clear cell carcinoma (CCC) is one of histological subtypes showing poor prognosis due to chemoresistance. The association of autophagy-related proteins and clinical implementation in CCC has not been determined. Methods: The present study investigated whether expression of autophagy-related protein, light chain 3A (LC3A), was related with prognoses in the patients with CCC using immuno-histochemical stainings, and whether inhibition of autophagy modified the sensitivity to cisplatin in CCC cells in vitro. Results: High expression of autophagy-related protein, LC3A, was detected in 78 cases (78%) in all CCC cases. The patients with high LC3A expression showed significantly lower response rate to primary chemotherapy (17% vs. 100%, p<0.010), and had worse progression-free survival (PFS) and overall survival (OS) compared with those with LC3A low expression. Furthermore, multivariate analyses revealed that high expression of LC3A was identified as independent worse prognostic factors for PFS and OS. Inhibition of autophagy protein LC3A using hydroxychloroquine (HCQ) increased sensitivity to cisplatin in CCC cells in vitro. Conclusion: High expression of LC3A proteins was associated with lower response to platinum therapy, leading to worse prognoses in CCC. Although further studies are needed to confirm the results, inhibition of autophagy by HCQ was associated with platinum sensitivity. Autophagy protein LC3A could be a promising target for treatment for CCC.
Morikazu Miyamoto,Masashi Takano,Tadashi Aoyama,Hiroaki Soyama,Tomoyuki Yoshikawa,Hitoshi Tsuda,Kenichi Furuya 대한부인종양학회 2018 Journal of Gynecologic Oncology Vol.29 No.2
Objective: In 2014 World Health Organization criteria, seromucinous carcinoma was defined as a new histological subtype in ovarian carcinomas, but “seromucinous carcinoma” was not defined in endometrial carcinomas. The aim of this study was to identify seromucinous carcinoma resembling ovarian seromucinous carcinoma in endometrial carcinomas, and to evaluate the clinical significance for prognoses of the patients. Methods: Central pathological review was conducted for patients with endometrioid carcinoma of the endometrium treated by primary surgery at our hospital between 1990 and 2013. Results: Among 340 cases included in the study, no case had all tumor cells resembling ovarian seromucinous carcinoma in all specimens, and 31 cases (9.1%) had seromucinous component in combination with endometrioid carcinomas. Immunohistochemical analysis revealed seromucinous component had positive reactivity for cytokeratin (CK) 7, and negative reactivity for CK20 and caudal type homeobox 2 (CDX2) in all cases. Seromucinous component showed lower immunoreactivity of estrogen receptor and progesterone receptor, compared with endometrioid carcinoma component. Progression-free survival of the cases with seromucinous component was better than those without seromucinous component (p=0.049). Conclusion: Seromucinous component was identified in approximately 10% of endometrioid carcinoma, and could be a histological predictor for prognosis.
Comparison of mechanisms of advanced mechanical surface treatments in nickel-based superalloy
Gill, A.,Telang, A.,Mannava, S.R.,Qian, D.,Pyoun, Y.S.,Soyama, H.,Vasudevan, V.K. Elsevier Sequoia 2013 Materials science & engineering. properties, micro Vol.576 No.-
Mechanical surface enhancement techniques are used to introduce compressive residual stresses to enhance the fatigue life and corrosion resistance of metallic components. In this study, we compare the effects of three advanced mechanical surface enhancements treatments: laser shock peening, cavitation shotless peening and ultrasonic nano structure modification on residual stress, hardness, plastic deformation and changes in near surface microstructure introduced in a Ni-Base superalloy, IN718 SPF(Super plastic forming). Coupons of the alloy were peened using two different conditions of each treatment and results compared to achieve a better understanding of underlying mechanisms of these techniques. Results indicate that there are significant differences in mechanisms of these surface treatments leading to differences in material response.