The effect of functionalized group concentration on the stability and thermal conductivity of carbon nanotube fluid as heat transfer media

In this research, the pristine CNTs sample synthesized by the CCVD method contains catalytic particles and the carbonaceous impurities, and then the special purification procedure was done. By different methods CNT functionalized with various concentration of COOH was prepared. The carboxylated CNTs were analyzed by back titration method for determining the COOH concentrations on the surface of the oxidized CNTs. Thermal conductivity of difference carbon nanotube fluid has been measured under the stable condition by KD₂ prob. For the first time, we have compared the effect of difference COOH concentration as important parameter in stability and heat transfer behavior of nanofluid. The results show that increasing the functionalized group causes better stability and higher thermal conductivity if the surface of MWNT does not damage in functionalize process.     

A profile of bioactive compounds of Rumex vesicarius L

The present study was designed to investigate the bioactive compounds in extracts of Rumex vesicarius L. (Polygonaceae), a wild edible herb growing in Egypt. Ethyl acetate and n-butanol fractions of leaves of R. vesicarius were conducted by HPLC-PDA-MS/MS-ESI in the negative mode to analyze phenolics content. Results revealed the identification of 13 phenolic compounds: 8-C-glucosyl-apigenin, 8-C-glucosyl-luteolin, 6-C-hexosyl-quercetin, 3-O-rutinosyl-quercetin, 7-O-rhamno-hexosyl-diosmetin, 7-O-rhamno-acetylhexosyl-diosmetin, catechin, epicatechin, ferulohexoside, 6-C-glucosyl-naringenin, epicatechin gallate, 6-C-glucosyl-catechin, and epigallocatechin gallate. Quantification of the identified compounds revealed that 6-C-glucosyl-naringenin was the major compound. Also, qualitative and quantitative analysis of the hydro-ethanolic extract of leaves was carried out for ascorbic acid, α-tocopherol, β-carotene. The essential oil as well as lipids analysis of saponifiable and unsaponifiable matters. The biochemical studies were conducted to evaluate the antioxidant and hepatoprotective potential of roots (REE), leaves (LEE), and fruits (FEE) ethanolic extracts of R. vesicarius (100 mg/kg b.wt., p.o., each) against hepatotoxicity induced by CCl(4) (0.5 mL/kg b.wt., p.o., 3 times a week) compared with silymarin (50 mg/kg b.wt., p.o.) as standard drug. The results confirmed that coadministration of the tested extracts or silymarin with CCl(4) for 4 wk exhibited a marked hepatoprotective activity, attributed to their antioxidant potential, membrane stabilizing effect, and antifibrogenic activities. Practical Application: Investigation of the effect of hommad as a safe hepatoprotective diet that prospectively directs the attention to a valuable therapeutic natural herb rich in bioactive constituents.     

Automated optimized classification techniques for magnetic resonance brain images

Multimedia Tools and Applications - This paper presents automatic tumor detection and classification approaches for brain magnetic resonance images (MRI). These approaches are based on...     

The use of continuous boundary elements in the boundary elements method for domains with non-smooth boundaries via finite difference approach

A numerical method is presented in this article to deal with the drawback of boundary elements method (BEM) at corner points. The use of continuous elements instead of the discontinuous ones has been recommended in the BEM literature widely because of the simplicity and accuracy. However the continuous elements lead to certain difficulties for problems where their domains contain corners. In this paper the finite difference method (FDM) has been applied to obtain some constraints for boundary points near the corners to deal with this drawback. Because of its simplicity and capability, the new scheme is applicable on BEM problems for all geometries, all governing equations and general boundary conditions, easily. Since the Dirichlet boundary condition is more critical than the other ones, we will focus on it in the numerical implementation. The numerical results show that the new treatment improves the accuracy of BEM significantly.     

Autothermal reforming of methane over nickel catalysts supported on nanocrystalline MgAl2O4 with high surface area

In this paper autothermal reforming of methane (ATR) was carried out over MgAl₂O₄ supported Ni catalysts with various Ni loadings. MgAl₂O₄ spinel with high specific surface area, as nanocrystalline carrier for nickel catalysts was synthesized by co-precipitation method with the addition of pluronic P123 triblock copolymer as surfactant. The prepared samples were characterized by XRD, BET, TEM, SEM, TPR and TPH techniques. The results demonstrated that methane conversion is significantly increased with increasing the Ni content and methane conversion of 15% Ni/MgAl₂O₄ was higher than that of other catalysts in all operation temperatures. Furthermore the influences of H₂O/CH₄, and O₂/CH₄ molar ratio in feed and GHSV on activity of 5% Ni/MgAl₂O₄ catalyst were investigated.     

Counting dynamically synchronizing processes

International Journal on Software Tools for Technology Transfer - We address the problem of automatically establishing correctness for programs generating an arbitrary number of concurrent...     

Synthesis of Ti3SiC2 MAX phase powder through molten salt method

Titanium silicon carbide (Ti₃SiC₂) MAX phase powder was synthesized from elemental reactants using the molten salt synthesis (MSS) method. Optimum experimental parameters were also investigated to determine the purity and synthesis pathway of the Ti₃SiC₂ MAX phase. The results showed that Ti₃SiC₂ was not synthesized using carbon black as the carbon source in the starting materials because of the high quantity of TiC formed along with the TiSi₂ silicide phase. However, Ti₃SiC₂ was successfully synthesized in a relatively high purity (93%) at 1200°C for 2 h using graphite as the source of carbon because of the formation of TiC and Ti₅Si₃ intermediate phases. The Ti₅Si₃ silicide phase was found to play a crucial role in the formation of the Ti₃SiC₂ MAX phase using the MSS method. Moreover, applying a pressure of 150 MPa to the prepared samples and using the eutectic mixture of NaCl–KCl (molar ratio: 1:1) instead of NaCl also resulted in the higher formation of the Ti₃SiC₂ MAX phase. The formation mechanism of Ti₃SiC₂ was determined to be the reaction among Ti₅Si₃, TiC, and residual carbon through the template-growth and dissolution–precipitation mechanisms that occurred at different stages of the synthesis process.     

Sintering of Al2O3-SiC composite from sol-gel method with MgO, TiO2 and Y2O3 addition

Al₂O₃-SiC composite ceramics were prepared by pressureless sintering with and without the addition of MgO, TiO₂ and Y₂O₃ as sintering aids. The effects of these compositional variables on final density and hardness were investigated. In the present article at first α-Al₂O₃ and β-SiC nano powders have been synthesized by sol-gel method separately by using AlCl₃, TEOS and saccharose as precursors. Pressureless sintering was carried out in nitrogen atmosphere at 1600 °C and 1630 °C. The addition of 5 vol.% SiC to Al₂O₃ hindered densification. In contrast, the addition of nano MgO and nano TiO₂ to Al₂O₃-5 vol.% SiC composites improved densification but Y₂O₃ did not have positive effect on sintering. Maximum density (97%) was achieved at 1630 °C. Vickers hardness was 17.7 GPa after sintering at 1630 °C. SEM revealed that the SiC particles were well distributed throughout the composite microstructures. The precursors and the resultant powders were characterized by XRD, STA and SEM.