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81.
H. P. S. Abdul Khalil P. Firoozian M. Jawaid H. M. Akil A. Hassan 《Journal of Thermal Analysis and Calorimetry》2013,113(2):623-631
Activated carbon derived from oil palm empty fruit bunch (AC-EFB), bamboo stem (AC-BS), and coconut shells (AC-CNS) were obtained by pyrolysis of agricultural wastes using two chemical reagents (H3PO4 or KOH). The AC-EFB, AC-BS and AC-CNS were used as filler in preparation of epoxy nanocomposites. Epoxy nanocomposites prepared at 1, 5 and 10 % activated carbons filler loading using KOH and H3PO4 chemical agents. Transmission electron microscopy confirms better dispersion of the nano-activated carbons in the epoxy matrix at 5 % activated carbon. The presence of 5 % AC-CNS in the epoxy matrix using H3PO4 chemical reagent resulted in an improvement of the thermal stability of epoxy matrix. KOH treated AC filled epoxy nanocomposites were slightly better in thermal stability as compared to H3PO4 treated AC filled epoxy nanocomposites, may be due to better interaction of filler with epoxy matrix. Thermal analysis results showed that thermal stability of the activated carbon filled epoxy nanocomposites improved as compared to the neat epoxy matrix. The degree of crystallinity of epoxy matrix was improved by adding the activated carbon due to interfacial interaction between AC and epoxy matrix rather than loading of AC alone. Developed nanocomposites from biomass (agricultural wastes) materials will help to reduce the overall cost of the materials for its demanding applications as insulating material. 相似文献
82.
Heavy metal oxide glasses doped with 2d transition metal niobium were casted through normal melt-quench technique in the formula composition (100?x) [3Bi2O3–7GeO2 (BGO70)]?xNb2O5 where 5 ≤ x ≤ 25. Experimentally measured values of density d exp were 6.737–7.149 g/cc ± 0.06 %. Corresponding molar volume V m exp had values 29.677–31.550 cc ± 0.04 %, V pyc varied 32.28–34.71 cc ± 0.03 % and oxygen molar volume $ V_{{{\text{mO}}^{2-} }} $ increased linearly from 17.761 to 20.467 cc ± 0.06 %. Thermal coefficient of linear expansion was between 5.316 ± 0.001 × 10?6 and 8.033 ± 0.001 × 10?6 K?1. Glass transition temperature T g, onset of crystallization temperature T x, and the stability factor ΔT were noted from DTA curves. Direct allowed energy gap E g was between 1.809–2.988 eV and Urbach energy had value 0.32–1.49 eV. Maximum transmission efficiency was 74 % for glass BGO70-Nb10. FTIR spectra revealed that lattice vibration modes were active in 400–1,300 cm?1 range. A modifying behavior was assigned to Nb5+ ion in the system. 相似文献
83.
Michelle Gonçalves Mothé Cheila Gonçalves Mothé Carlos Henrique Monteiro de Carvalho Marcia Cristina Khalil de Oliveira 《Journal of Thermal Analysis and Calorimetry》2013,113(2):525-531
Present study investigates thermal behavior of two heavy crude oils with different °API values by simultaneous thermogravimetry–differential scanning calorimetry–fourier transform infrared spectroscopy (TG–DSC–FTIR), and an evaluation of the chemical element levels present in the oils’ ashes was done by energy dispersive X-ray fluorescence spectrometry. TG and DSC curves were obtained for two samples in nitrogen atmosphere. Among all inorganic components evaluated, the highest concentration in the two oils was SO3. Thus this study may contribute to a better understanding of the thermal behavior of heavy crude oils and their composition. 相似文献
84.
H. P. S. Abdul Khalil M. Jawaid P. Firoozian E. S. Zainudin M. T. Paridah 《International Journal of Polymer Analysis and Characterization》2013,18(4):247-256
Nano-activated carbons obtained from oil palm empty fiber bunch (AC-EFB), bamboo stem (AC-BS), and coconut shells (AC-CNS) were reinforced in epoxy matrix to fabricate epoxy nanocomposites. The dynamic mechanical analysis of epoxy nanocomposites was carried out, and 5% AC-CNS treated with KOH-filled epoxy composites displayed the highest storage modulus of all the activated carbon–filled epoxy composites. The incorporation of a small amount of AC-BS, AC-EFB, and AC-CNS to the epoxy matrix enhanced the damping characteristics of the epoxy nanocomposites. The 5% AC-EFB treated with H3PO4 filled epoxy composites showed the highest glass transition temperature (Tg) in all temperature ranges. 相似文献
85.
M. M. Ghorab N. E. Amin M. S. A. El Gaby N. M. H. Taha M. A. Shehab I. M. I. Faker 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2918-2928
The key intermediate diisothiocyanate 2 was allowed to react with 5-amino-3-methyl-pyrazole-4-carbonitrile 3, ethyl 5-amino-1-phenyl-pyrazole-4-carboxylate 6, 2-amino-tetrahydrobenzo[b]thiophene-3-car-bonitrile 9, ethyl-2-amino-tetra-hydrobenzo[b]thiophene-3-carboxylate 12, and/or 1,2,4-triazole 15 to give the corresponding biscompounds 4, 5, 7, 8, 10, 11, 13, 14, and 16, respectively. The structure of the synthesized compounds was elucidated by elemental analyses and spectral data. Some of the prepared compounds were tested for their antimicrobial and antitumor activities. 相似文献
86.
A. A. Fadda S. B. Bondock A. M. Khalil Eman H. Tawfik 《Journal of heterocyclic chemistry》2013,50(4):838-843
The starting N‐(2‐pyridyl)‐6‐methyl‐4‐phenyl‐2‐thioxo‐1,2,3,4‐tetrahydropyrimidine‐5‐carboxamide ( 4 ) was used as a key intermediate for the synthesis of new 1,2,3,4‐tetrahydropyrimidine‐2‐thione and their thiazolo[3,2‐a]pyrimidine, thiazino and benzothiazipen derivatives. The reaction of 4 with haloketones in ethanol catalyzed by base afforded the corresponding thiophenopyrimidine and pyrimidothiazipine derivatives 5 , 6 , 7 , 8 , 9 , 10 . Methylation and formylation of 4 led to the pyrimidine derivatives 15 and 16 , respectively. The preventative compounds were established on the basis of elemental and spectral data. 相似文献
87.
Tarek A. Salama Saad S. Elmorsy Abdel‐Galel M. Khalil Margret M. Girges Abdel‐Aziz S. El‐Ahl 《合成通讯》2013,43(8):1313-1319
A combination of tetrachlorosilane and potassium cyanide (in situ trichlorosilyl cyanide) was found to work efficiently for hydrocyanation of ketones to afford the corresponding cyanohydrins in high yield under mild conditions. 相似文献
88.
Synthesis of dibenzoxanthenes through condensation of β-naphthol with various aromatic and aliphatic aldehydes in ethanol as an ecofriendly solvent using RuIII as catalyst is reported.
89.
The complexation equilibria of Fe(III) with two buffer families, which are ubiquitous in biological system studies, were studied by potentiometric measurements at a constant ionic strength of I = 0.1 mol·dm?3 NaNO3 in aqueous solutions at 298.15 K. The members of TRIS family are tris(hydroxymethyl)aminomethane (TRIS), N-[tris(hydroxymethyl)methyl]-2-aminoethanesulfonic acid (TES), N-[tris(hydroxymethyl)methyl]-3-aminopropanesulfonic acid (TAPS), N-[tris(hydroxymethyl)methyl]-3-amino-2-hydroxypropanesulfonic acid (TAPSO), and N-tris(hydroxymethyl)methyl-4-aminobutanesulfonic acid (TABS) buffers. The members of morpholine family are 4-morpholineethanesulfonic acid (MES), 4-morpholinepropanesulfonic acid (MOPS), 3-morpholino-2-hydroxypropanesulfonic acid (MOPSO), and 4-(N-morpholino) butanesulfonic acid (MOBS) buffers. The overall stability constants were determined from pH-metric data using the least-squares curve-fitting program HYPERQUAD 2008. Based on the best-fit results, the species formed at equilibrium are ML, ML2, ML2H?1, and ML3 in the systems with TRIS family buffers. The complex species ML, ML2, ML2H?1, and MLH?1 are formed in the MOPSO-containing system, while ML, ML2, and ML2H?1 are formed in the systems with MES, MOPS, and MOBS. The stabilities of the complexes fall in the order TABS > TRIS > TAPS > TAPSO > TES and MOBS > MOPS > MOPSO > MES for the TRIS family and morpholine families, respectively. 相似文献
90.
Rabah A. Khalil 《Journal of Dispersion Science and Technology》2013,34(10):1545-1550
Binding constants between reactants molecules with micelles are considered to be important parameters particularly in micellar catalysis area. Recently, we developed a statistical method based on multiple linear regression for determining those parameters from kinetic data (Phys. Chem. Liq. 2008, 46, 34–46). In the present work, we derived further two statistical equations from the same original equation using also multiple linear regression method. A substantial difference has been found between the results of those equations and with that of the recently published one. This strongly indicates that the statistical procedures are not valid for such a purpose, that is, the available statistical and graphical methods in the literature are also not suitable for such treatment. A mathematical procedure using iterative method for evaluating the binding constants is introduced. An equation for such treatment has also been derived from the same original equation, and a computer program for this purpose has been written. Application of the developed method to the kinetic data has been found to be quite successful. It has been concluded that the presented mathematical method is simple, reliable, and accurate. 相似文献