Numerical and Experimental Study on the Grinding Performance of Ti-Based Super-Alloy

The experiments of the surface grinding of Ti-6Al-4V grade 5 alloy (Ti-64) with a resin-bonded cubic Boron Nitride (cBN) grinding wheel are performed in this research to estimate the influence of cutting parameters named workpiece infeed speed, Depth of Cut (DOC), cooling condition on the grinding force, force ratio, and specific energy. A finite element simulation model of single-grain grinding of Ti-64 is also implemented in order to predict the values of grinding forces and temperature. The experimental results show that an increase of workpiece infeed speed creates higher intensified cutting forces than the DOC. The grinding experiments under wet conditions present slightly lower tangential forces, force ratio, and specific energy than those in dry grinding. The simulation outcomes exhibit that the relative deviation of simulated and experimental forces is in the range of 1-15%. The increase in feed rate considerably reduces grinding temperature, while enhancement of DOC elevates the heat generation in the cutting zone

Study on the influence of various base agents in K2TiF6 hydrolysis on morphology, structure and photocatalytic activity of TiO2

K2TiF6 was hydrolyzed by various base agents including solutions of NH3, NaOH, and KOH at the same concentration of 3 M. TiO2 material was obtained after filtering, washing, drying and calcination at 500 °C of Ti(OH)4 precipitate. The experimental results showed that there was a significant influence of base agent nature on the morphology, structure, surface area of TiO2 product. Using NH3 agent could obtain uniform TiO2 particles with about 15 nm in size and surface area of 98.93 m2.g-1, while using NaOH or KOH led to TiO2 with varying particle sizes (in the range of 15-500 nm), and decreasing surface area (less than 20 m2.g-1). The nature of base agent also significantly influenced photocatalytic activity of TiO2 product for methylene blue (MB) decomposition. The prepared TiO2 from NH3-using process showed the highest phtocatalytic activity in comparison with TiO2 from KOH/NaOH-using process or commercial TiO2 (P25). Keywords. K2TiF6, TiO2, Ti(OH)4, photocatalyst

AGING OF WATERBORNE PAINT BASED ON THE ACRYLIC RESIN EMULSION AND ORGANIC PIGMENT

Aging of waterborne paint on the base of acrylic resin emulsion with and without green Luconyl have been investigated by general appearance assessment, adhesion change, FT-IR and discoloration. The obtained results showed that the both of paint-formulas coatings had no cracks, blisters, flacks and there was no change of adhesion during the aging process. However, IR analysis indicated that there were some changes in chemical structures of coating with and without Green Luconyl during aging process. To specify, IR spectrums of initial and aged coating no containing Green Luconyl illustrated aging process led content of O-H and C=C increased significantly but baseline of spectra was fairly unchanged. For coating filled Green Luconyl, IR spectrums’ shape was fairly stable but baseline saw a clear reduce during accelerated weather exposure. Moreover, SEM images indicated that surfaces morphology of samples changed differently depending on in presence of organic pigment. Surface of aged coating without Luconyl saw rougher than surface of coating with Luconyl after aging process. Hence, the weather aging test had more significant influence on paint coating in absence of Luconyl than paint coating in presence of Luconyl. It was explained that the macroradical produced in aging process would attack into conjugated double bonds of Luconyl instead of double bonds of AC-261 leading to aged coating filled Luconyl become more opaque than initial while coating no filled Luconyl had significant changes in chemical structure during aging process. Although this was a hypothesis, it saw a suitable with the obtained results. The paint coating in presence of Luconyl illustrated significant color change, especially, showed the loss of green color while the other paint coating showed slight color change

OXIDIZED MAIZE STARCH: CHARACTERIZATION AND EFFECT OF IT ON THE BIODEGRADABLE FILMS I. CHARACTERIZATION OF MAIZE STARCH OXIDIZED BY SODIUM HYPOCHLORITE

The effects of hypochlorite level, i.e. 0.5; 1 and 2 active chlorine g/100g starch, on the structures and physicochemical properties of oxidized maize starch were investigated. The obtained results shown that oxidation degree grew up with increasing hypochlorite concentration, specially, the carboxyl content saw higher increased than the content of carbonyl. SEM images indicated that surface of oxidized maize starches were rougher than native starch. The surface of oxidized starches saw rougher with increasing hypochlorite level. However, the DSC results illustrated that there was no significant difference of gelatinization temperature between the native starch and oxidized starches

Effect of Silica Nanoparticles on Properties of Coatings Based on Acrylic Emulsion Resin

Effect of nanosilica size on physic-mechanical properties, thermal stability and weathering durability of coating based on acrylic emulsion. Nanocomposite coating formulas were filled by 2 wt.% nanosilica particles which were used in this study, namely: nanosilica from Sigma (15-20nm), nansilica from rice husk (~70-200 nm) and nanosilica from Arosil – Belgium (7-12 nm). Obtained results showed that viscosity flow of coating formula containing nanosilica from Arosil saw the highest flow-time while coating formulas filled other nanosilica and unfilled nanosilica experienced similar flow-time. In presence of nanosilica, coating properties were improved in comparison with neat coating. However, coating filled by nanosilica from rice husk indicated the best properties in studied coating formula. It may explained that size of nanosilica from rice husk was the largest in studied nanosilica particles and thus easily dispersing into coating formula

Chemical profiles and antibacterial activity of acetone extract of two Curcuma species from Vietnam

Curcuma thorelii Gagnep. and Curcuma cotuana Luu, Škorni?k. & H.?.Tr?n are the rare species only found in Southeast Asia. The present study was the first to explore the chemical compositions and antibacterial effects of the whole plant acetone extracts of these 2 species. Altogether 41 and 31 compounds have been identified in C. thorelii and C. cotuana extracts by gas chromatography/mass spectrometry. Accordingly, the C. thorelii extract contained (E)-labda-8(17),12-diene-15,16-dial (33.37%), vitamin E (12.33%), phytol (9.83%) as the major compounds while C. cotuana extract contained predominantly (E)-labda-8(17),12-diene-15,16-dial (14.58%), n-hexadecanoic acid (10.96%), 3,7,11,15-tetramethylhexadec-2-en-1-yl acetate (8.13%), ?-sitosterol (7.97%). In addition, results from disc diffusion assay have shown that C. thorelii acetone extract had inhibitory effects on 5 out of 10 pathogenic bacterial strains such as Bacillus cereus (ATCC 11778), Listeria monocytogenes (ATCC 19111), Staphylococcus aureus (ATCC 25923), S. aureus (ATCC 29213) and S. saprophyticus (BAA750) while C. cotuana acetone extract was found to be effective only against B. cereus. The obtained results showed that the acetone extracts of C. thorelii and C. cotuana possessed several valuable bioactive compounds as well as promising antibacterial activity, which place a good foundation for future pharmaceutical product development

Papillary thyroid carcinoma with tall cell features is as aggressive as tall cell variant: a meta-analysis

There are still ongoing debates as to which cut-off percentage of tall cell (TC) should be used to define tall cell variant (TCV) papillary thyroid carcinoma (PTC). In this meta-analysis, we aimed to investigate the clinicopathological significance of PTC with tall cell features (PTC-TCF, PTC with 10–50% of TCs) in comparison with classical PTC and TCVPTC (PTC with more than 50% of TCs) to clarify the controversial issue. Four electronic databases including PubMed, Web of Science, Scopus and Virtual Health Library were accessed to search for relevant articles. We extracted data from published studies and pooled into odds ratio (OR) and its corresponding 95% confidence intervals (CIs) using random-effect modeling. Nine studies comprising 403 TCVPTCs, 325 PTC-TCFs and 3552 classical PTCs were included for meta-analyses. Overall, the clinicopathological profiles of PTC-TCF including multifocality, extrathyroidal extension, lymph node metastasis, distant metastasis and patient mortality were not statistically different from those of TCVPTC. Additionally, PTC-TCF and TCVPTC were both associated with an increased risk for aggressive clinical courses as compared to classical PTC. The prevalence of BRAF mutation in PTC-TCF and TCVPTC was comparable and both were significantly higher than that in classical PTC. The present meta-analysis demonstrated that even a PTC comprising only 10% of TCs might be associated with a poor clinical outcome. Therefore, the proportions of PTC in PTC should be carefully estimated and reported even when the TC component is as little as 10%