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Mohammad Ardestani 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.6
Copper/chromium oxide (75%wt) nanocomposite powders were synthesized via chemical precipitation process. The processwas included chemical precipitation of Cr-Cu containing precipitates, calcination and reduction of the precipitates. Based onthermogravimetric analysis of the precipitates, the optimum calcination temperature was determined as 700 oC. Thesynthesized powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Theobservations revealed that the powder particles were agglomerated and their shape was mainly spherical. The powders weredensified via spark plasma and presssureless sintering at 1000 oC and 1100 oC, respectively. The microstructural evaluation ofthe spark plasma sintered samples confirmed a near dense structure with a fine dispersion of the constituents. However, themicrostructure of the pressureless sintered specimen showed a large number of pores between the powder particles. Therelative density and micro-hardness of the spark plasma sintered samples were 95.8% and 1600 HV, respectively.
Mehdi Naghikhani,Mohammad Ardestani,Mohammad Moazami‑Goudarzi 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6
Tungsten carbide reinforced brass matrix composites with 30 and 70 wt% brass were synthesized by mechanical milling anddensification of brass/tungsten carbide powder mixtures. Two different sintering methods included pressureless and sparkplasma sintering were applied for densification of the milled powders. The relative density of the spark plasma sinteredsamples was much higher than those of the pressureless sintered ones confirming higher microstructural densification duringspark plasma sintering. The hardness of the spark plasma sintered composites containing 30 and 70 wt% brass were 303 and175 Vickers, respectively which was about five times more than those of the pressureless sintered composites with similarweight percent of brass. In addition, the wear performance of the composites was investigated by the pin on disc method. The spark plasma sintered samples with 30 wt% brass showed the highest wear resistant among the processed samplesowing to their higher hardness. The microscopic observations revealed that delamination and adhesion were the dominantwear mechanisms for the pressureless and spark plasma sintered composites, respectively. The bending strength of the sparkplasma sintered samples with 30 and 70 wt% brass were 329 and 453 MPa, respectively.
Seyed Davar Siadat,Farzam Vaziri,Mamak Eftekhary,Maryam Karbasian,Arfa Moshiri,Mohammad R. Aghasadeghi,Mehdi S. Ardestani,Meghdad Abdollahpour Alitappeh,Amin Arsang,Abolfazl Fateh,Shahin Najar Peeraye 질병관리본부 2015 Osong Public Health and Research Persptectives Vol.6 No.1
Objectives: Development of an efficacious vaccine against brucellosis has been a challenge for scientists for many years. At present, there is no licensed vaccine against human brucellosis. To overcome this problem, currently, antigenic determinants of Brucella cell wall such as Lipopolysaccharide (LPS) are considered as potential candidates to develop subunit vaccines. Methods: In this study, Brucella abortus LPS was used for conjugation to Neisseria meningitidis serogroup B outer membrane vesicle (OMV) as carrier protein using carbodiimide and adipic acid-mediated coupling and linking, respectively. Groups of eight BALB/c mice were injected subcutaneously with 10 ㎍LPS alone, combined LPS + OMV and conjugated LPS-OMV on 0 days, 14 days, 28 days and 42 days. Anti-LPS IgG was measured in serum. Results: The yield of LPS to OMV in LPS-OMV conjugate was 46.55%, on the basis of carbohydrate content. The ratio for LPS to OMV was 4.07. The LPS-OMV conjugate was the most immunogenic compound that stimulated following the first injection with increased IgG titer of ~ 5-fold and ~1.3-fold higher than that produced against LPS and LPS in noncovalent complex to OMV (LPS + OMV), respectively. The highest anti-LPS IgG titer was detected 2 weeks after the third injection (Day 42) of LPS-OMV conjugate. The conjugated compound elicited higher titers of IgG than LPS + OMV, that showed a 100-120-fold rise of anti-LPS IgG in mice. Conclusion: These results indicate that our conjugated LPS-OMV can be used as a brucellosis vaccine, but further investigation is required.