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21.
Li Wan Yoon Gek Cheng Ngoh Adeline Seak May Chua Mohd. Ali Hashim 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(10):1342-1348
BACKGROUND: Much attention has been given to applying ionic liquids (ILs) as an alternative pretreatment method for lignocellulosic biomass. This study aims to select the most suitable type of IL for pretreating sugarcane bagasse (SCB). The potential of ILs for pretreatment was evaluated and compared with conventional pretreatment media, acids and alkalis. The performance of the pretreatment media was evaluated based on the amount of reducing sugar produced from enzymatic saccharification, the energy requirement, and changes in the chemical structure and crystallinity index of the pretreated bagasse. RESULTS: 1‐ethyl‐3‐methylimidazolium acetate [EMIM]oAc was selected as the most suitable IL for SCB pretreatment. The optimum yields of reducing sugar obtained from [EMIM]oAc‐, alkali‐, and acid‐pretreated SCB were 69.5%, 92.8% and 41.3%, respectively. Although a lower yield of reducing sugar was obtained, [EMIM]oAc pretreatment required the least energy to pretreat 1 kg of SCB. Moreover, the percentage of SCB loss during [EMIM]oAc pretreatment was the lowest. [EMIM]oAc‐pretreated SCB also had the lowest crystallinity index (CI) with the most amorphous structure. CONCLUSION: [EMIM]oAc appears to be another option for pretreating SCB, and other issues such as the recyclability of [EMIM]oAc is worth investigating. Copyright © 2011 Society of Chemical Industry 相似文献
22.
Khamirul Amin Matori Loy Chee Wah Mansor Hashim Ismayadi Ismail Mohd Hafiz Mohd Zaid 《International journal of molecular sciences》2012,13(12):16812-16821
We report on a recycling project in which α-Al2O3 was produced from aluminum cans because no such work has been reported in literature. Heated aluminum cans were mixed with 8.0 M of H2SO4 solution to form an Al2(SO4)3 solution. The Al2(SO4)3 salt was contained in a white semi-liquid solution with excess H2SO4; some unreacted aluminum pieces were also present. The solution was filtered and mixed with ethanol in a ratio of 2:3, to form a white solid of Al2(SO4)3·18H2O. The Al2(SO4)3·18H2O was calcined in an electrical furnace for 3 h at temperatures of 400–1400 °C. The heating and cooling rates were 10 °C/min. XRD was used to investigate the phase changes at different temperatures and XRF was used to determine the elemental composition in the alumina produced. A series of different alumina compositions, made by repeated dehydration and desulfonation of the Al2(SO4)3·18H2O, is reported. All transitional alumina phases produced at low temperatures were converted to α-Al2O3 at high temperatures. The X-ray diffraction results indicated that the α-Al2O3 phase was realized when the calcination temperature was at 1200 °C or higher. 相似文献
23.
Structural adhesives are gaining wide recognition by industry as they offer engineering designers greater flexibility to achieve economic and technical advantages. In the marine industry there are potential applications for adhesives in various types of construction, for example, thick steel and composite adherends, (typically 5-15 mm thick). The applications include panels and large pipes. This article is largely concerned with the use of two-part epoxy adhesives. The purpose of this article is to understand and evaluate the weaknesses of adhesives and adherends, in relation to specific applications and to use design and material selection to alleviate them. This understanding can be extended to other thick adherend applications. This article will also highlight the impact of structural epoxy adhesive technology on the design and fabrication of steel, composite, and hybrid constructions. The benefits and inherent limitations that can accrue are quantified through three case studies related to thick adherend connections. 相似文献
24.
Styrene-based deproteinized natural rubber (SNR) latex was synthesized by in situ polymerization. Three pre-vulcanization systems [conventional-cured (CV), semi-efficient-cured (Semi-EV), and efficient-cured (EV)] were studied in terms of tensile and adhesion properties. Good tensile properties were observed for CV and EV SNR. The Semi-EV SNR showed the best adhesion properties based on the good anchorage performance in all substrate pairings (polystyrene–polystyrene, polystyrene–rubber, and rubber–rubber). The pH modification on SNR latex via KOH addition has beneficial effects of removing protein layers, resulting in more styrene grafting sites in the rubber molecules. Consequently, the tensile and adhesion properties of the SNR are improved as more styrene polymers are grafted onto the rubber matrix. Semi-EV SNR with pH 12 has superior adhesive performance; hence, it is suitable for use as a pressure-sensitive adhesive. 相似文献
25.
26.
Muhammad Kashif Md Eaqub Ali Syed M Usman Ali Uda Hashim Sharifah Bee Abd Hamid 《Nanoscale research letters》2013,8(1):68
ZnO nanorods were synthesized using a low-cost sol-gel spin coating technique. The synthesized nanorods were consisted of hexagonal phase having c-axis orientation. SEM images reflected perpendicular ZnO nanorods forming bridging network in some areas. The impact of different hydrogen concentrations on the Pd-sensitized ZnO nanorods was investigated using an impedance spectroscopy (IS). The grain boundary resistance (Rgb) significantly contributed to the sensing properties of hydrogen gas. The boundary resistance was decreased from 11.95 to 3.765 kΩ when the hydrogen concentration was increased from 40 to 360 ppm. IS gain curve showed a gain of 6.5 for 360 ppm of hydrogen at room temperature. Nyquist plot showed reduction in real part of impedance at low frequencies on exposure to different concentrations of hydrogen. Circuit equivalency was investigated by placing capacitors and resistors to identify the conduction mechanism according to complex impedance Nyquist plot. Variations in nanorod resistance and capacitance in response to the introduction of various concentrations of hydrogen gas were obtained from the alternating current impedance spectra. 相似文献
27.
The application of supercritical fluid chromatography (SFC) coupled with a UV variable-wavelength detector to isolate the
minor components (carotenes, vitamin E, sterols, and squalene) in crude palm oil (CPO) and the residual oil from palm-pressed
fiber is reported. SFC is a good technique for the isolation and analysis of these compounds from the sources mentioned. The
carotenes, vitamin E, sterols, and squalene were isolated in less than 20 min. The individual vitamin E isomers present in
palm oil were also isolated into their respective components, α-tocopherol, α-tocotrienol, γ-tocopherol, γ-tocotrienol, and
δ-tocotrienol. Calibration of all the minor components of palm as well as the individual components of palm vitamin E was
carried out and was found to be comparable to those analyzed by other established analytical methods. 相似文献
28.
Al-Hashimi HM 《Chembiochem : a European journal of chemical biology》2005,6(9):1506-1519
The ever-increasing cellular roles ascribed to RNA raise fundamental questions regarding how a biopolymer composed of only four chemically similar building-block nucleotides achieves such functional diversity. Here, I discuss how RNA achieves added mechanistic and chemical complexity by undergoing highly controlled conformational changes in response to a variety of cellular signals. I examine pathways for achieving selectivity in these conformational changes that rely to different extents on the structure and dynamics of RNA. Finally, I review solution-state NMR techniques that can be used to characterize RNA structural dynamics and its relationship to function. 相似文献
29.
S.A. Hashim 《International Journal of Adhesion and Adhesives》2009,29(3):294-301
The inherited adhesion limitation of polyester and vinyl ester resin-based pultruded GFRP makes pultrusions difficult to bond, especially when a thixotropic adhesive is used. While such an adhesive is necessary for gap filling, it has a limited wettability. Therefore, coating the adherend with low-viscosity epoxy resin, prior to bonding, improves wetting and hence increases joint strength. The paper describes the experimental methodology to achieve this, using double lap-shear (DLS) joints with various materials combinations. A significant strength improvement was reached as a result of coating the inner adherend in conjunction with using a “high adhesion” outer adherend. To further understand the effect of coating, numerical stress analysis was undertaken, including preliminary micro-models representing the composite/adhesive interface as well as overall DLS models. 相似文献
30.
Application of FTIR Spectroscopy for the Determination of Virgin Coconut Oil in Binary Mixtures with Olive Oil and Palm Oil 总被引:1,自引:0,他引:1
Abdul Rohman Yaakob B. Che Man Amin Ismail Puziah Hashim 《Journal of the American Oil Chemists' Society》2010,87(6):601-606
Rapid Fourier transform infrared (FTIR) spectroscopy combined with attenuated total reflectance (ATR) was applied for quantitative
analysis of virgin coconut oil (VCO) in binary mixtures with olive oil (OO) and palm oil (PO). The spectral bands correlated
with VCO, OO, PO; blends of VCO and OO; VCO and PO were scanned, interpreted, and identified. Two multivariate calibration
methods, partial least square (PLS) and principal component regression (PCR), were used to construct the calibration models
that correlate between actual and FTIR-predicted values of VCO contents in the mixtures at the FTIR spectral frequencies of
1,120–1,105 and 965–960 cm−1. The calibration models obtained were cross validated using the “leave one out” method. PLS at these frequencies showed the
best calibration model, in terms of the highest coefficient of determination (R
2) and the lowest of root mean standard error of calibration (RMSEC) with R
2 = 0.9992 and RMSEC = 0.756, respectively, for VCO in mixture with OO. Meanwhile, the R
2 and RMSEC values obtained for VCO in mixture with PO were 0.9996 and 0.494, respectively. In general, FTIR spectroscopy serves
as a suitable technique for determination of VCO in mixture with the other oils. 相似文献