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101.
Halimah Mohamed. K ;Mahmoud Goodarz Naseri ;Amir Reza Sadrolhosseini ;Arash Dehzangi ;Ahmad Kamalianfar ;Elias B Saion ;Reza Zamiri ;Hossein Abastabar Ahangar ;Burhanuddin Y. Majlis 《中国物理快报》2014,(7):193-196
A laser ablation technique is applied for synthesis of silver nanoparticles in different concentrations of polyvinyl alcohol (PVA) aqueous solution. The ablation of high pure silver plate in the solution is carried out by a nanosecond Q-switched Nd:YAG pulsed laser. X-ray diffraction and transmission electron microscopy are implemented to explore the particles sizes. The effects of PYA concentrations on the absorbance of the silver nanoparticles are studied as well, by using a UV-vis spectrophotometer. The preparation process is carried out for deionized water as a reference sample. The comparison of the obtained results with the reference sample shows that the formation efficiency of nanoparticles in PYA is much higher and the sizes of particles are also smaller. 相似文献
102.
Habib Firouzabadi Nasser Iranpoor Arash GhaderiMaryam Ghavami 《Tetrahedron letters》2012,53(41):5515-5518
The application of cerium(IV) oxide (CeO2) as a neutral and heterogeneous catalyst for aldehyde-induced decarboxylative coupling of l-proline with triethyl phosphite and nitromethane is described. In addition, a [3+2] cycloaddition reaction of the in situ generated 1,3-dipolar intermediate with benzaldehyde in the absence of a nucleophile is also reported. 相似文献
103.
Arash Yavari Jerrold E. Marsden 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2012,63(5):921-927
In this paper we make a connection between covariant elasticity based on covariance of energy balance and Lagrangian field theory of elasticity with two background metrics. We use Kucha?’s idea of reparametrization of field theories and make elasticity generally covariant by introducing a “covariance field”, which is a time-independent spatial diffeomorphism. We define a modified action for parameterized elasticity and show that the Doyle-Ericksen formula and spatial homogeneity of the Lagrangian density are among its Euler–Lagrange equations. 相似文献
104.
Arash Sarhangi Fard Martien A. Hulsen Han E. H. Meijer Navid M. H. Famili Patrick D. Anderson 《Macromolecular theory and simulations》2012,21(4):217-240
The application of the mapping method in finite element modeling is extended to quantitatively compare mixing in different twin‐screw extruder layouts. The mapping method provides volumetric quantities, which are crucial for the analysis and optimization of mixing based on the tracking of particles in the velocity field. A new approach to the mapping method is developed to analyze mixing in complex, dynamic open geometries. Several screw configurations and different types of conveying screws are compared, changing the pitch and gap widths. The volume‐weighted intensity of segregation is used as a mixing measure.
105.
Wong JM Esfahani A Singh N Villa CR Mirrahimi A Jenkins DJ Kendall CW 《Journal of AOAC International》2012,95(1):24-30
Modulation of the gut microbiota is an area of growing interest, particularly for its link to improving and maintaining the systemic health of the host. It has been suggested to have potential to reduce risk factors associated with chronic diseases, such as elevated cholesterol levels in coronary heart disease (CHD). Diets of our evolutionary ancestors were largely based on plant foods, high in dietary fiber and fermentable substrate, and our gut microbiota has evolved against a background of such diets. Therapeutic diets that mimic plant-based diets from the early phases of human evolution may result in drug-like cholesterol reductions. In contrast, typical Western diets low in dietary fiber and fermentable substrate, and high in saturated and trans fatty acids, are likely contributors to the increased need for pharmacological agents for cholesterol reduction. The gut microbiota of those consuming a Western diet are likely underutilized and depleted of metabolic fuels, resulting in a less than optimal gut microbial profile. As a result, this diet is mismatched to our archaic gut microbiota and, therefore, to our genome, which has changed relatively little since humans first appeared. While the exact mechanism by which the gut microbiota may modulate cholesterol levels still remains uncertain, end products of bacterial fermentation, particularly the short chain fatty acids (i.e., propionate), have been suggested as potential candidates. While more research is required to clarify the potential link between gut microbiota and CHD risk reduction, consuming a therapeutic diet rich in plant foods, dietary fiber, and fermentable substrate would be a useful strategy for improving systemic health, possibly by altering the gut microbiota. 相似文献
106.
Interactive effect of oxygen diffusion and volatiles advection on transient thermal degradation of poly methyl methacrylate (PMMA) 总被引:1,自引:0,他引:1
A transient, one-dimensional model has been presented to formulate the substantial role of polymer gasification in the early
stages of fire growth. The present model comprises the interaction between the oxygen diffusion and the released volatiles
on the rate of polymer gasification, when the polymeric sample is subjected to an external radiative source. The model also
includes different mechanisms affecting the degradation process such as in-depth thermal and oxidative decomposition, in-depth
absorption of radiation and heat and mass transfer in the both gas and solid phases. The results for two different radiative
heat sources (17 and 40 kW m−2) are reported and yielded realistic results, comparing to the published experimental data. It was found that an increase
in the oxygen concentration will lead to a considerable decrease in the surface temperature as well as significant increase
of gasification rate at 17 kW m−2; nevertheless this effect is less apparent at 40 kW m−2. 相似文献
107.
Arash Naghib-Lahouti Horia Hangan 《International Journal of Heat and Fluid Flow》2010,31(6):1096-1106
Vortex shedding in the wake of two-dimensional bluff bodies is usually accompanied by three dimensional instabilities. These instabilities result in streamwise and vertical vorticity components which occur at a certain spanwise wavelength. The spanwise wavelength of the instabilities (λZ) depends on several parameters, including profile geometry and Reynolds number. The objective of the present work is to study the three dimensional wake instabilities for a blunt trailing edge profiled body, comprised of an elliptical leading edge and a rectangular trailing edge, and to manipulate these instabilities to control the aerodynamic forces. Results of numerical simulations of flow around the body at Re(d) = 400, 600, and 1000, as well as planar Laser Induced Fluorescence (LIF) flow visualizations at Re(d) = 600 and 1000 are analyzed to determine the wake vorticity structure and λZ. Based on the findings of these analyses, an active flow control mechanism for attenuation of the fluctuating aerodynamic forces on the body is proposed. The flow control mechanism is comprised of a series of trailing edge injection ports distributed across the span, with a spacing equal to λZ. Injection of a secondary flow leads to amplification of the three dimensional instabilities and disorganization of the von Kármán vortex street. Numerical simulations indicate that the flow control mechanism can attenuate the fluctuating aerodynamic forces at lower Reynolds numbers (Re(d) = 400 and 600) where λZ is constant in time. However, the control mechanism loses its effectiveness at Re(d) = 1000, due to the temporal variations of λZ. 相似文献
108.
Mourad Benlamri Kyle M. Bothe Alex M. Ma Gem Shoute Amir Afshar Himani Sharma Arash Mohammadpour Manisha Gupta Kenneth C. Cadien Ying Y. Tsui Karthik Shankar Douglas W. Barlage 《固体物理学:研究快报》2014,8(10):871-875
A high effective electron mobility of 33 cm2 V–1 s–1 was achieved in solution‐processed undoped zinc oxide (ZnO) thin films. The introduction of silicon nitride (Si3N4) as growth substrate resulted in a mobility improvement by a factor of 2.5 with respect to the commonly used silicon oxide (SiO2). The solution‐processed ZnO thin films grown on Si3N4, prepared by low‐pressure chemical vapor deposition, revealed bigger grain sizes, lower strain and better crystalline quality in comparison to the films grown on thermal SiO2. These results show that the nucleation and growth mechanisms of solution‐processed films are substrate dependent and affect the final film structure accordingly. The substantial difference in electron mobilities suggests that, in addition to the grain morphology and crystalline structure effects, defect chemistry is a contributing factor that also depends on the particular substrate. In this respect, interface trap densities measured in high‐κ HfO2/ZnO MOSCAPs were about ten times lower in those fabricated on Si3N4 substrates. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)
109.
Ghorbani-Choghamarani Arash Sahraei Rokhsareh Taherinia Zahra 《Research on Chemical Intermediates》2019,45(5):3199-3214
Research on Chemical Intermediates - Here we report the synthesis of Ni(II) immobilized on modified boehmite nanostructures as an environmentally friendly heterogeneous catalyst for the one-pot... 相似文献
110.
A new Pd‐Schiff‐base complex on boehmite nanoparticles: Its application in Suzuki reaction and synthesis of tetrazoles 下载免费PDF全文
Boehmite nanoparticles are not air or moisture sensitive, therefore have been prepared in water without inert atmosphere using inexpensive materials. Pd‐isatin‐boehmite was synthesized and used as heterogeneous organometallic catalyst for the synthesis of 5‐substituted 1H‐tetrazoles and C‐C band formation. Pd‐isatin‐boehmite characterized by XRD, TGA, SEM and ICP‐OES techniques. This catalyst was reused for several times without significant loss of its catalytic efficiency or palladium leaching. Heterogeneity of this catalyst has been studied using ICP‐OES technique. 相似文献