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71.
Chiraz Youssef Hamed Ben Ammar Mohamed Belhouchet Kassem Beydoun Ridha Ben Salem Henri Doucet Pierre H. Dixneuf 《Journal of heterocyclic chemistry》2011,48(5):1126-1131
2‐(Arylidene)cyanomethylbenzoxazoles have been prepared in water from benzoxazole‐2‐ylacetonitriles. Using multi‐component reactions, a variety of heterocycles containing benzoxazole and nitrile functionality has been prepared. J. Heterocyclic Chem., (2011). 相似文献
72.
Ataee-Esfahani H Nemoto Y Wang L Yamauchi Y 《Chemical communications (Cambridge, England)》2011,47(13):3885-3887
Here we report a facile and efficient method to prepare Pt spheres with hollow interior and nanosponge shell with high surface area. Such a unique Pt nanostructure can effectively improve the electrocatalytic performance of Pt catalysts by facilitating the access of electroactive species to the full-extent Pt surface. 相似文献
73.
Hanif MA Al-Maskri AY Al-Mahruqi ZM Al-sabahi JN Al-Azkawi A Al-Maskari MY 《Natural product communications》2011,6(10):1451-1454
Three wild Omani plants, Moringa peregrina, Acacia nilotica and Rhazya stricta, were selected for the present study. Na, K and Ca contents were determined using flame photometric analysis. M. peregrina seeds (22.5 mg/g) and pods (27.7 mg/g) had higher Na contents than A. nilotica (0.33 mg/g) and R. stricta (0.30 mg/g), whereas the K and Ca contents of R. stricta were significantly higher than those of the other two plants. The protein content was lowest in R. stricta (9.8%) and highest in M peregrina seeds (21.0%). The highest total phenolic contents (TPC) were found in M. peregrina seeds (350.3 mg/g) and the lowest in A. nilotica (66.1 mg/g). The major component of M. peregrina seed oil was oleic acid (74.7%). Gas chromatographic-mass spectrometric analysis (GC-MS) revealed that octadecanal (30.9%) was the major compound in A. nilotica. The presence of various phenolics and flavonoids in M. peregrina, A. nilotica and R. stricta were confirmed by high performance liquid chromatography (HPLC). 相似文献
74.
We investigated the influence of solid-state polymerization (SSP) process on the reactions that could be taken place at the
interphase of polycondensation polymer blends to stabilize the structure obtained after melt mixing. Polyethylene terephthalate
(PET) and polyamide 66 (PA66) were melt blended in a mixer, and subsequent SSP process was performed for each sample. FTIR
spectra indicated reactions between two polymers. Viscosity behavior and interfacial slip were investigated by measuring shear
viscosity of components and blends before and after SSP and then compared with the viscosity calculated from the log-additivity
model. The results showed that after SSP, there was no sign of interfacial slip, the slope of viscosity reduction with increasing
shear rate became smaller, and the viscosity of blends showed positive deviation at all examined shear rate from the log-additivity
model while this deviation was negative at higher shear rate before SSP. SEM micrographs, which were taken after shear stress
was imposed on the samples, also indicated the morphological stability after SSP. Furthermore, we studied the effect of functional
groups concentration on the reactions at the interphase by using hydrolyzed PET as a precursor for blends. The results showed
that slip at the interface would decrease with increasing functional groups of the precursors. These results are particularly
valuable for using recycled polymers. 相似文献
75.
In this article we are interested in the density of small linear structures (e.g. arithmetic progressions) in subsets A of the group
\mathbbFpn{\mathbb{F}_{p}^n} . It is possible to express these densities as certain analytic averages involving 1
A
, the indicator function of A. In the higher-order Fourier analytic approach, the function 1
A
is decomposed as a sum f
1 + f
2 where f
1 is structured in the sense that it has a simple higher-order Fourier expansion, and f
2 is pseudo-random in the sense that the k-th Gowers uniformity norm of f
2, denoted by ||f2||Uk{\|{f_2}\|_{U^k}}, is small for a proper value of k. 相似文献
76.
Hamed Taghavian 《Mathematical Methods in the Applied Sciences》2019,42(7):2169-2189
This paper presents an analytical method towards Laplace transform inversion of composite functions with the aid of Bell polynomial series. The presented results are used to derive the exact solution of fractional distributed order relaxation processes as well as time‐domain impulse response of fractional distributed order operators in new series forms. Evaluation of the obtained series expansions through computer simulations is also given. The results are then used to present novel series expansions for some special functions, including the one‐parameter Mittag‐Leffler function. It is shown that truncating these series expansions when combined with using potential partition polynomials provides efficient approximations for these functions. At the end, the results are shown to be also useful in studying asymptotical behavior of partial Bell polynomials. Numerical simulations as well as analytical examples are provided to verify the results of this paper. 相似文献
77.
Mergen H. Ghayesh Hamed Farokhi Marco Amabili 《Applied Physics A: Materials Science & Processing》2013,112(2):329-338
The nonlinear resonant behaviour of a microbeam, subject to a distributed harmonic excitation force, is investigated numerically taking into account the longitudinal as well as the transverse displacement. Hamilton’s principle is employed to derive the coupled longitudinal-transverse nonlinear partial differential equations of motion based on the modified couple stress theory. The discretized form of the equations of motion is obtained by applying the Galerkin technique. The pseudo-arclength continuation technique is then employed to solve the discretized equations of motion numerically. Different types of bifurcations as well as the stability of solution branches are determined. The numerical results are presented in the form of frequency-response and force-response curves for different sets of parameters. The effect of taking into account the longitudinal displacement is highlighted. 相似文献
78.
Hamed Farokhi Mergen H. Ghayesh Marco Amabili 《Applied Physics A: Materials Science & Processing》2013,113(2):297-307
The present study investigates the nonlinear resonant behavior of a microbeam over its buckled (non-trivial) configuration. The system is assumed to be subjected to an axial load along with a distributed transverse harmonic load. The axial load is increased leading the system to lose the stability via a pitchfork bifurcation; the postbuckling configuration is obtained and the nonlinear resonant response of the system over the buckled state is examined. More specifically, the nonlinear equation of motion is obtained employing Hamilton’s principle along with the modified couple stress theory. The continuous system is truncated into a system with finite degrees of freedom; the Galerkin scheme is employed to discretize the nonlinear partial differential equation of motion into a set of ordinary differential equations. This set of equations is solved numerically employing the pseudo-arclength continuation technique; first a nonlinear static analysis is performed upon this set of equations so as to obtain the onset of buckling (supercritical pitchfork bifurcation) and the buckled configuration of the microbeam. The frequency-response and force-response curves of the system are then constructed over the buckled configurations. A comparison is made between the frequency-response curves obtained by means of the modified couple stress and the classical theories. The effect of different system parameters on the frequency-response and force-response curves is also examined. 相似文献
79.
We present an application of an improved speckle photography technique for spatially extended phase objects. A contour mapping of a thin lens displaying its phase variation is presented. A theoretical analysis is investigated followed by the experimental presentation. Reasonable interference fringes are obtained and compared with the fringes obtained for hot air. The phase information of the object is extracted using the point-by-point technique. 相似文献
80.
B. Z. Gunesin D. N. Schulz J. W. Kang A. R. Cain G. R. Hamed 《Journal of polymer science. Part A, Polymer chemistry》1984,22(2):353-363
A new convenient route to metal containing polymers is described. This method involves emulsion co(ter) polymerization of a polar hydrocarbon soluble monomer, N-isobutoxymethylacrylamide (IBMA), with styrene or styrene/butadiene, followed by addition of metals. Metal incorporation is effected by latex or solution techniques. Preparative, atomic adsorption, spectroscopic, film observation, and dilute solution data are presented in support of metal complexation. Structures for the complexes are proposed. 相似文献