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981.
Wan Azelee Wan Abu Bakar Rusmidah Ali Abdul Aziz Abdul Kadir Salmiah Jamal Mat Rosid Nurul Shafeeqa Mohammad 《燃料化学学报》2012,40(7):822-830
A series of alumina supported cobalt oxide based catalysts doped with noble metals such as ruthenium and platinum were prepared by wet impregnation method.The variables studied were difference ratio and calcination temperatures.Pt/Co(10∶90)/Al2O3 catalyst calcined at 700 ℃ was found to be the best catalyst which able to convert 70.10% of CO2 into methane with 47% of CH4 formation at maximum temperature studied of 400 ℃.X-ray diffraction analysis showed that this catalyst possessed the active site Co3O4 in face-centered cubic and PtO2 in the orthorhombic phase with Al2O3 existed in the cubic phase.According to the FESEM micrographs,both fresh and spent Pt/Co(10∶90)/Al2O3 catalysts displayed small particle size with undefined shape.Nitrogen Adsorption analysis showed that 5.50% reduction of the total surface area for the spent Pt/Co(10∶90)/Al2O3 catalyst.Meanwhile,Energy Dispersive X-ray analysis(EDX) indicated that Co and Pt were reduced by 0.74% and 0.14% respectively on the spent Pt/Co(10∶90)/Al2O3catalyst.Characterization using FT-IR and TGA-DTA analysis revealed the existence of residual nitrate and hydroxyl compounds on the Pt/Co(10∶90)/Al2O3 catalyst. 相似文献
982.
Mohamad Faizal Ibrahim Suraini Abd-Aziz Mohamad Nafis Abdul Razak Lai Yee Phang Mohd Ali Hassan 《Applied biochemistry and biotechnology》2012,166(7):1615-1625
Acetone–butanol–ethanol (ABE) production from renewable resources has been widely reported. In this study, Clostridium butyricum EB6 was employed for ABE fermentation using fermentable sugar derived from treated oil palm empty fruit bunch (OPEFB). A
higher amount of ABE (2.61 g/l) was produced in a fermentation using treated OPEFB as the substrate when compared to a glucose
based medium that produced 0.24 g/l at pH 5.5. ABE production was increased to 3.47 g/l with a yield of 0.24 g/g at pH 6.0.
The fermentation using limited nitrogen concentration of 3 g/l improved the ABE yield by 64%. The study showed that OPEFB
has the potential to be applied for renewable ABE production by C. butyricum EB6. 相似文献
983.
Zhenyu Luo Chunxiao Zou Saad Syed Luthfia A. Syarbaini Guofang Chen 《Colloid and polymer science》2012,290(2):141-150
Chemically reactive particles with controllable sizes from 383 to 756 nm in very narrow size distributions (well below 5%)
have been synthesized by the modified surfactant-free emulsion homopolymerization of inhibitor-free glycidyl methacrylate
with the dropwise addition of ionic initiators during the initial reaction of 10 min. The effects of monomer concentration
and the amount of initiator were systematically studied on the particle diameter. In addition, changes of the particle diameter
and its size distribution during the whole synthesis process were also investigated. The mechanism for the formation of coalesced
and highly monodisperse chemically reactive colloidal particles was discussed based on the colloidal stability governed by
chemical reaction and physical interactions between the precursor or primary particles. Colloidal photonic crystals with different
brilliant visible colors in a large scale were prepared by shearing assembly of such chemically reactive monodisperse particles
with spin coating technique. The reflection wavelengths in the visible spectrum range are from the high-order including the
second-order light diffraction of the as-prepared PGMA photonic crystals. Such monodisperse chemically reactive particles
will be very useful in optical and sensing technologies, and in biochemical analysis. 相似文献
984.
Bakhat Ali Rashad Mehmood Uzma Rasheed Mughal Abdul Malik Muhammad Safder Riaz Hussain Muhammad Imran Rasool Bakhsh Tareen 《Helvetica chimica acta》2012,95(4):586-593
Eremosides A–C ( 1 – 3 ), three new iridoid glucosides, were isolated from the AcOEt‐soluble fraction of the EtOH extract of the whole plant of Eremostachys loasifolia, along with buddlejoside B ( 4 ), 10‐O‐benzoylcatalpol ( 5 ), and pakiside A ( 6 ) reported for the first time from this species. The structures of these compounds were elucidated by spectroscopic data including 2D‐NMR, FAB‐MS, ESI‐MS, as well as by acid and basic hydrolyses. 相似文献
985.
Laghari AH Ali Memon A Memon S Nelofar A Khan KM Yasmin A 《Natural product research》2012,26(2):173-176
The present study comprises the determination of some phenolic acids from the leaves and flowers of Alhagi maurorum by HPLC-DAD, confirmed by LC-MS-APCI. The antioxidant properties and measurements of the total phenolic contents of the extracts were assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and Folin-Ciocalteu methods, respectively. It was found that the leaf extract had higher antioxidant potential (83.5%) than the flower extract (72.3%). The antioxidant properties and total phenolic contents of the leaves were higher than those of the flowers. 相似文献
986.
The X-ray photoelectron spectra of M(N2)2 (dppe)2, M(N2)2 (PMePh2)4 and M(N2)2 (PMe2Ph)4; where M=W or Mo, Ph is phenyl, Me is methyl and dppe is (Ph)2P-CH2-CH2-P(Ph)2; have been investigated. The N(1s), P(2p3/2), Mo(3d5/2) and W(4f7/2) binding energies do not show significant differences between these complexes. The N(1s) signals show the separation of 1.3-1.4 eV. 相似文献
987.
To study ion beam induced modifications into MOCVD grown wurtzite AlInN layers, neon ions were implanted on the samples with four doses ranging from 1014 to 9×1015 ions/cm2. Structural characterization was carried out by X-ray diffraction and Rutherford backscattering spectroscopy (RBS) techniques. XRD analysis revealed that GaN related peak for all samples remains at its usual Bragg position of 2θ=34.56° whereas a shift in AlInN peak takes place from its position of 2θ=35.51° for as-grown sample. Rutherford back scattering (RBS) analysis indicated that peak related to Ga atoms in capping layer provided evidence of partial sputtering of GaN cap layers. Moreover, Al peak position is shifted towards lower channel side and width of the signal is increased after implantation, which pointed to the inwards migration of Al atoms away from the AlInN surface. The results suggested that partial sputtering of cap layer has taken place without uncovering the underneath AlInN layer. 相似文献
988.
The spin-dependent transport through a diluted magnetic semiconductor quantum dot (QD) which is coupled via magnetic tunnel junctions to two ferromagnetic leads is studied theoretically. A noncollinear system is considered, where the QD is magnetized at an arbitrary angle with respect to the leads’ magnetization. The tunneling current is calculated in the coherent regime via the Keldysh nonequilibrium Green’s function (NEGF) formalism, incorporating the electron–electron interaction in the QD. We provide the first analytical solution for the Green’s function of the noncollinear DMS quantum dot system, solved via the equation of motion method under Hartree–Fock approximation. The transport characteristics (charge and spin currents, and tunnel magnetoresistance (TMR)) are evaluated for different voltage regimes. The interplay between spin-dependent tunneling and single-charge effects results in three distinct voltage regimes in the spin and charge current characteristics. The voltage range in which the QD is singly occupied corresponds to the maximum spin current and greatest sensitivity of the spin current to the QD magnetization orientation. The QD device also shows transport features suitable for sensor applications, i.e., a large charge current coupled with a high TMR ratio. 相似文献
989.
Zahid Ahmad Qazi Zahoor Ahmed Abdul Sami Awan 《International Journal of Theoretical Physics》2013,52(10):3598-3603
In this paper, we investigated the cylindrical gravitational collapse with heat flux by considering the appropriate geometry of the interior and exterior spacetimes. For this purpose, we matched collapsing fluid to an exterior containing gravitational waves.The effects of heat flux on gravitational collapse are investigated and matched with the results obtained by Herrera and Santos (Class. Quantum Gravity 22:2407, 2005). 相似文献
990.
Ather Farooq Khan Muhammad Awais Abdul Samad Khan Sobia Tabassum Aqif Anwar Chaudhry Ihtesham Ur Rehman 《应用光谱学评论》2013,48(4):329-355
Abstract Raman spectroscopy of natural bones and hydroxyapatites is described. In addition, how Raman spectroscopy has proved crucial in providing baseline data for the modification of synthetic apatite powders that are routinely used now as bone replacement materials is explained. It is important to understand the chemical structural properties of natural bone. Bone consists of two primary components: an inorganic or mineral phase, which is mainly a carbonated form of a nanoscale crystalline calcium phosphate, closely resembling hydroxyapatite, and an organic phase, which is composed largely of type I collagen fibers. Other constituents of bone tissue include water and organic molecules such as glycosaminoglycans, glycoproteins, lipids, and peptides. Ions such as sodium, magnesium, fluoride, and citrate are also present, as well as hydrogenophosphate. Hence, the mineral phase in bone may be characterized essentially as nonstoichiometric substituted apatite. Such a distinction is important in the development of synthetic calcium phosphates for application as skeletal implants. An understanding of bone function and its interfacial relationship to an implant clearly depends on the associated structure and composition. Therefore, it is essential to fully understand the chemical composition of bone, and Raman spectroscopy is an excellent technique for such an analysis. 相似文献