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71.
Lina Jassim Umer Rashid Suraya Abdul Rashid Mohamad Amran Salleh Sonny Irawan 《Chemical Engineering Communications》2016,203(4):463-470
A stable ester was synthesized to overcome the ester hydrolysis problem during the drilling of oil or gas wells using a conventional ester-based drilling fluid. The thermal and hydrolytic stability of the produced ester was high owing to the transesterification method employed in this study. The reaction was performed using 2-ethylhexanol and methyl laureate esters in the presence of sodium methoxide as a catalyst. In order to obtain the optimum synthesis conditions, a response surface methodology (RSM) was appraised based on the central composite design (CCD). The optimum conditions were determined as follows: 0.6 wt.% catalyst, 70°C reaction temperature, 1:1.5 molar ratio, and 11.5 min of reaction time. The results of 77 wt.% 2-ethylhexyl ester (2-EH) illustrated a high agreement between the experimental and RSM models. The reaction product contained 77 wt.% 2-EH and 23% 2-ethylhexanol. The kinematic viscosity was 5 mm2/s at 40°C and 1.5 mm2/sec at 100°C; the specific gravity was 0.854, flash point was 170°C, and pour point was ?7°C. The produced product showed similar properties to the available commercial product. However, it was observed that the mud formulation using the synthesized base oil had superior rheological properties at 121°C. 相似文献
72.
A network of gold nanostructures exhibiting one-dimensional gold nanostructure properties may become a prospective novel structure for optical, electrical and catalytic applications benefited by its unusual characteristics resulting from the collective properties of individual nanostructures in the network. In this paper, we demonstrate a facile method for the formation of high-density gold nanonetwork film on the substrate surface composed of quasi-1D nanoparticles (typically fusiform) with length ca. 10 nm - via reduction of gold ions in the presence of nanoseeds attached surface, binary surfactants of cetyltrimethylammonium bromide and hexamethyleneteramine and Ag+ ions. The length of the nanonetworks can be up to ca. 100 nm, which corresponds to the aspect ratio of ca. 10. The quasi-1D gold nanostructures as well as the nanonetworks were found to be sensitive to the binary surfactants system and the Ag+ ions as they can only be formed if all the chemicals are available in the reaction. The nanonetworks exhibit unique 1D optical properties with the presence of transverse and longitudinal surface plasmon resonance absorption. Owing to their peculiar structures that are composed of small quasi-1D nanoparticles, the nanonetworks may produce unusual optical and catalytic properties, which are potentially used in surface-enhanced Raman scattering, catalysis and optical and non-linear optical applications. 相似文献
73.
Kushairi Mohd Salleh Othman Sulaiman Salim Hiziroglu Wan Noor Aidawati Wan Nadhari Norani Abd Karim 《Journal of Adhesion Science and Technology》2013,27(4):319-336
The objective of this study was to evaluate some of the mechanical and physical properties of experimental particleboard panels manufactured from rubberwood (Hevea brasiliensis) bonded using oil palm starch, wheat starch, and urea formaldehyde (UF) at a density of 0.60 g/cm3. Bending characteristics, internal bond strength, thickness swelling, and water absorptions of the samples were determined based on Japanese Industrial Standard (JIS). Overall mechanical properties for natural binder oil palm starch resulted in higher values than those made from wheat starch. The highest internal-bonding strength (IB) value of 0.41 N/mm2 was determined for the samples made from oil palm starch. Dimensional stability in the form of thickness swelling of the samples made from oil palm starch had higher values, ranging from 4.24 to 22.84% than those manufactured from wheat starch. Natural adhesive showed comparable strength with panels manufactured with UF. Overall results meet the Japanese Industrial Standard (JIS) requirements except for water absorption and thickness swelling of the samples. 相似文献
74.
Hadi Amirkhani Umer Rashid Shanti Faridah Salleh A. B. Dayang Radhiah Syafiie Syam 《Chemical Engineering Communications》2013,200(9):1235-1244
Oil palm frond (OPF) fiber, a lignocellulosic waste from the palm oil industry, contains high cellulose and hemicellulose content, thus it is a potential feedstock for simple sugars production. This paper describes the two-stage hydrolysis process focusing on the use of low-temperature dilute acid hydrolysis to convert the hemicellulose in OPF fiber to simple sugars (xylose, arabinose, and glucose). The objective of the present study was to evaluate the effect of operating conditions of dilute sulfuric acid hydrolysis undertaken in a 1 L self-built batch reactor on xylose production from OPF fiber. The reaction conditions were temperatures (100–140°C), acid concentrations (2–6%), and reaction times (30–240 min). The mass ratio of solid/liquid was kept at 1:30. Analysis of the three main sugars glucose, xylose, and arabinose were determined using high-pressure liquid chromatography. The optimum reaction temperature, reaction time, and acid concentration were found to be 120°C, 120 min, and 2% acid, respectively. Based on the potential amount of xylose (10.8 mg/mL), 94% conversion (10.15 mg/mL) was obtained under the optimum conditions with small amount of furfural (0.016 mg/mL). To enhance the effectiveness of dilute acid hydrolysis, the hydrolysis of OPF fiber was also performed using ultrasonic-pretreated OPF fiber. The effects of ultrasonic parameters power (40–80%) and ultrasonication times (20–60 min) were determined on sugar yields under optimum hydrolysis conditions (2% acid sulfuric, 120°C and 120 min). However, the use of ultrasonication was found to have detrimental effect on the yield of simple sugars due to the 10-fold increase in the formation of furfural. 相似文献
75.
76.
In this study, carbon tubular membranes were produced by employing P84 co-polyimide as a precursor material and nanocrystalline cellulose (NCC) as an additive. The synthesized NCC which was derived from recycled newspaper was used as a pore forming agent for the membrane. Various carbonization temperatures (600, 700, 800, and 900 °C) were used while the stabilization temperature was kept at 300 °C. The measurements of pure gases' (He, H2, and N2) permeance through all carbon tubular membranes produced were carried out at feed pressure of 8 bars. The results showed that higher carbonization temperatures resulted in more selective but less productive carbon membranes. The outcome of this study suggested that carbon tubular membrane fabricated from NCC blending with P84 co-polyimide as a promising candidate for H2 and He recovery application with H2/N2 and He/N2 selectivity of 434.68 ± 1.39 and 463.86 ± 8.12, respectively. 相似文献
77.
Tengku Shafazila Tengku Saharuddin Alinda Samsuri Fairous Salleh Rizafizah Othaman Mohammad Bin Kassim Mohamed Wahab Mohamed Hisham Mohd Ambar Yarmo 《International Journal of Hydrogen Energy》2017,42(14):9077-9086
Chemical reduction behaviour of 3% chromium doped (Cr–Fe2O3) and undoped iron oxides (Fe2O3) were investigated by using temperature programmed reduction (TPR). The reduced phases were characterized by X-ray diffraction spectroscopy (XRD). The reduction processes were achieved with 10% H2 in nitrogen (%, v/v), 10% and 20% of carbon monoxide (CO) in nitrogen (%, v/v). In hydrogen atmosphere, the TPR results indicate that the reduction of Cr–Fe2O3 and Fe2O3 proceed in three steps (Fe2O3 → Fe3O4 → FeO → Fe) with Fe3O4 and FeO as intermediate states. A complete reduction to metallic iron for both samples occurred at 900 °C. As for CO reductant, the profiles show the reduction of Fe2O3 also proceeded in three steps with a complete reduction occurs at 900 °C in 10% CO with no sign of carbide formation. Nevertheless, a 20% CO was able to reduce the completely at lower temperature at 700 °C and there is a formation of iron carbide at 500 °C but the carbide disappeared as the reduction temperature increase. Meanwhile in 10% CO atmosphere, Cr–Fe2O3 shows a better reducibility compared to Fe2O3 with a complete reduction at 700 °C, which is 200 °C lower than Fe2O3. A Cr dopant in the Fe2O3 can lead to formation of various forms of iron carbides such as F2C, Fe5C2, Fe23C6 and Fe3C as the CO concentration was increased to 20%. The transformation profile of iron phases during carburization follows the following forms, Fe2O3 → Fe3O4 → iron carbides (FexC). The XRD pattern shows the diffraction peaks of Cr–Fe2O3 are more intense with improved crystallinity for the characteristic peaks of Fe2O3 compare to undoped Fe2O3. No visible sign of chromium particles peaks in the XRD spectrum that indicates the Cr particles loaded onto the iron oxide are well dispersed. The uniform dispersion with no sign of sintering effects of the Cr dopant on the Fe2O3 was confirmed by FESEM. The study shows that Cr dopant gives a better reducibility of iron oxide but promotes the formation of carbides in an excess CO concentration. 相似文献
78.
IEEE 802.11i authentication framework is composed of the 802.1x and an extensible authentication protocol (EAP) mechanism. One of the most applicable techniques in the EAP methods is EAP-transport layer security (EAP-TLS). The EAP-TLS implementation issues are high execution time; high number of data exchanges between two parties and possibility of closing connection as a result of modification in the contents of the handshake messages, which are all addressed in this paper. This research analyses the EAP-TLS in WLANs to improve this method’s efficiency in terms of the security analysis, time and memory usage. Based on the results, this research proposes an enhanced method with a discrete cryptographic mechanisms and a distinct handshake structure, which reduces the number of steps in the handshake protocol. This enhanced method also provides robust security compared to the original EAP-TLS with approximately the same level of memory usage, which reduces execution time significantly. 相似文献
79.
Abdul Rohman Anjar Windarsih Sugeng Riyanto Sudjadi Shahrel Ahmad Shuhel Ahmad Arieff Salleh Rosman 《International Journal of Food Properties》2016,19(3):680-687
Avocado oil is one of the functional oils having high quality and high price in the market. This oil shows many benefits for the human health and is applied in many cosmetic products. The authentication of avocado oil becomes very important due to the possible adulteration of avocado oil with other lower priced oils, such as palm oil and canola oil. In this study, Fourier transform infrared spectroscopy using attenuated total reflectance in combination with chemometrics techniques of partial least squares and principal component regression is implemented to construct the quantification and classification models of palm oil and canola oil in avocado oil. Partial least squares at the wavenumbers region of 1260–900 cm–1 revealed the best calibration models, having the highest coefficient of determination (R2 = 0.999) and the lowest root mean square error of calibration, 0.80%, and comparatively low root mean square error of prediction, 0.79%, for analysis of avocado oil in the mixture with palm oil. Meanwhile, the highest R2, root mean square error of calibration, and root mean square error of prediction values obtained for avocado oil in the mixture with canola oil at frequency region of 3025–2850 and 1260–900 cm–1 were 0.9995, 0.83, and 0.64%, respectively. 相似文献
80.