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Comparative Study of Conventional and Micro WEDM based on Machining of Meso/Micro Sized Spur Gear
Mohammad Yeakub Ali,A. N. Mustafizul Karim,Erry Yulian T. Adesta,Ahmad Faris Ismail,‘Aisy Anuarin Abdullah,Mohd Nazrol Idris 한국정밀공학회 2010 International Journal of Precision Engineering and Vol.11 No.5
This paper discusses the comparison of micro machining process using conventional and micro wire electrical discharge machining (WEDM) for fabrication of miniaturized components. Seventeen toothed miniaturized spur gear of 3.5 and 1.2 mm outside diameter were fabricated by conventional and micro WEDM respectively. The process parameters for both conventional and micro WEDM were optimized by preliminary experiments and analysis. The gears were investigated for the quality of surface finish and dimensional accuracy which were used as the criteria for the process evaluation. An average surface roughness (Ra ) of 50 nm and dimensional accuracy of 0.1-1 μm were achieved in micro WEDM. Whenever applied conventional WEDM for meso/micro fabrication, a Ra surface roughness of 1.8 μm and dimensional accuracy of 2-3 μm were achieved. However, this level of surface roughness and dimensional accuracy are acceptable in many applications of micro engineering. A window of conventional WEDM consisting of low energy discharge parameters is identified for micromachining.
M.A. Hasnat,Jamil A. Safwan,M. Shariful Islam,Zidnia Rahman,Mohammad Razaul Karim,Talha J. Pirzada,Ahmed Jalal Samed,Mohammed M. Rahman 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1
Electrochemical decolorization of Methylene blue (MB) molecules was studied at Pt electrode inpresence of KNO3 and KCl as the supporting electrolytes under acidic condition. The KNO3 electrolytedisplayed MB decolorization effect, where MB molecules exhibited two redox peaks at 0.48 V and0.34 V, respectively, in cyclic voltammogram (CV). The features of redox couples indicated thedimerization ofMBmolecules. In this simple preparation technique, a less amount of sample loading wasrequired, and the method displayed high efficiency toward decolorization of MB dye. This reportindicates the possibility for improving the quality of wastewater discharged from textile and otherindustries.
Ashequl A. Rana,Mohammad Mainul Karim,Makoto Takafuji 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.1
A new high performance liquid chromatograpgy (HPLC) stationary phase that possesses an internal carbonyl functional group is synthesized by heterogeneous “graft from” method. This new stationary phase, poly (vinyl octadecanoate)grafted silica (Sil-2) is then characterized by different physico-chemical methods such as diffuse reflectance infrared fourier transform, suspension state ^1H NMR, solid state ^13C CP/MAS NMR, ^29Si CP/MAS NMR, elemental analysis and thermogravimetric analysis. Chromatographic properties of Sil-2 were evaluated under reversed phase condition by separating polycyclic aromatic hydrocarbons (PAHs) and comparing the chromatographic results with those on polymeric as well as monomeric octadecylated silica stationary phases.
Rana, Ashequl A.,Karim, Mohammad Mainul,Takafuji, Makoto Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.1
A new high performance liquid chromatograpgy (HPLC) stationary phase that possesses an internal carbonyl functional group is synthesized by heterogeneous "graft from" method. This new stationary phase, poly (vinyl octadecanoate) grafted silica (Sil-2) is then characterized by different physico-chemical methods such as diffuse reflectance infrared fourier transform, suspension state $^1H$ NMR, solid state $^{13}C$ CP/MAS NMR, $^{29}Si$ CP/MAS NMR, elemental analysis and thermogravimetric analysis. Chromatographic properties of Sil-2 were evaluated under reversed phase condition by separating polycyclic aromatic hydrocarbons (PAHs) and comparing the chromatographic results with those on polymeric as well as monomeric octadecylated silica stationary phases.
Factors associated with unrecognized cirrhosis in patients with hepatocellular carcinoma
Yi-Te Lee,Mohammad A. Karim,Hye Chung Kum,Sulki Park,Nicole E. Rich,Mazen Noureddin,Amit G. Singal,Ju Dong Yang 대한간학회 2023 Clinical and Molecular Hepatology(대한간학회지) Vol.29 No.2
Background/Aims: Cirrhosis is the most important risk factor of hepatocellular carcinoma (HCC), and patients with cirrhosis are recommended to receive semiannual surveillance for early HCC detection. However, early cirrhosis is often asymptomatic and can go undiagnosed for years, leading to underuse of HCC surveillance in clinical practice. We characterized the frequency and associated factors of unrecognized cirrhosis in a national sample of patients with HCC from the United States. Methods: HCC patients aged 68 years and older, diagnosed during 2011 to 2015 were included from the SEERMedicare Linked Database. If cirrhosis was diagnosed within 6 months immediately preceding HCC diagnosis or after HCC diagnosis, cases were categorized as unrecognized cirrhosis. Factors associated with unrecognized cirrhosis were identified using logistic regression analyses. Factors associated with overall survival were evaluated using Cox regression analyses. Results: Among 5,098 HCC patients, 74.8% patients had cirrhosis. Among those with cirrhosis, 57.4% had unrecognized cirrhosis, with the highest proportion (76.3%) among those with NAFLD-related HCC. Male sex (aOR: 2.12, 95% CI: 1.83–2.46), non-Hispanic Black race (aOR: 1.93, 95% CI: 1.45–2.57), and NAFLD etiology (aOR: 4.46, 95% CI: 3.68–5.41) were associated with having unrecognized cirrhosis. Among NAFLD-related HCC patients, male sex (aOR: 2.32, 95% CI: 1.71–3.14) was associated with unrecognized cirrhosis. Unrecognized cirrhosis was independently associated with worse overall survival (aHR: 1.17, 95% CI: 1.08–1.27) compared to recognized cirrhosis. Conclusions: Unrecognized cirrhosis is common in NAFLD-related HCC, particularly among male and Black patients, highlighting these groups as important intervention targets to improve HCC surveillance uptake and outcomes.