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Matthew A. Papanikolas Mathew D. Rogers Detchat Samart 《Mathematische Zeitschrift》2014,276(3-4):1151-1163
The aim of this paper is to prove a Mahler measure formula of a four-variable Laurent polynomial whose zero locus defines a Calabi–Yau threefold. We show that its Mahler measure is a rational linear combination of a special \(L\)-value of the normalized newform in \(S_4(\Gamma _0(8))\) and a Riemann zeta value. This is equivalent to a new formula for a \(_6F_5\)-hypergeometric series evaluated at 1. 相似文献
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本文制备了用于费托合成反应的钴改性Fe3O4-MnO2双功能催化剂,并探究了钴负载量对Fe-Co协同效应的影响以及Fe1CoxMn1催化剂的费托合成反应性能. 实验发现,在Fe3O4-Mn催化剂中加入Co可促进铁氧化物的还原、增加反应过程中铁位点的活性. 此外,Co的加入可增强Fe-Co金属间的电子转移,加强两者的协同作用,提高催化性能. Co负载较高的Fe1CoxMn1催化剂可进一步促进加氢反应能力,使产品分布向短链烃方向转移. 在280 °C、2.0 MPa和3000 h-1的最佳工况条件下,Fe1Co1Mn1催化剂的液体燃料收率最高. 相似文献
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In this paper, the deflection angle of light by traversable wormholes, which are supported by the three-form fields, are studied. The specific forms of the redshift and shape functions that produce results compatible with the energy conditions at throat of the wormholes are used. Having used the well-defined parameter sets of the three-form wormholes, the photon geodesic motion is investigated under the effective potential of the wormhole background. As a result, it is discovered that the radius of the photon sphere can be used to analyze the geometrical structures of a physical wormhole. The analytical form of the effective potential is used to figure out a deflection angle of light caused by wormholes with the three-from fields. In this work, the relativistic images generated from the wormholes are also constructed. 相似文献
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Detchat Samart 《The Ramanujan Journal》2013,32(2):245-268
In this paper we prove that the Mahler measures of the Laurent polynomials (x+x ?1)(y+y ?1)(z+z ?1)+k 1/2, (x+x ?1)2(y+y ?1)2(1+z)3 z ?2?k, and x 4+y 4+z 4+1+k 1/4 xyz, for various values of k, are of the form r 1 L′(f,0)+r 2 L′(χ,?1), where $r_{1},r_{2}\in \mathbb{Q}$ , f is a CM newform of weight 3, and χ is a quadratic character. Since it has been proved that these Mahler measures can also be expressed in terms of logarithms and 5 F 4-hypergeometric series, we obtain several new hypergeometric evaluations and transformations from these results. 相似文献
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Banjong Boonchom Samart Kongtaweelert 《Journal of Thermal Analysis and Calorimetry》2010,99(2):531-538
The kinetics and thermodynamics of the thermal dehydration of aluminum phosphate monohydrate, AlPO4 · H2O were studied using thermogravimetry (TG-DTG-DTA) at four heating rates in dry air atmosphere. The activation energies of
the dehydration step of AlPO4 · H2O were calculated through the methods of Friedman (FR) and Flynn–Wall–Ozawa (FWO) and the possible conversion function has
been estimated through the Achar and Li–Tang equations. The independent activation energies on extent of conversions and the
better kinetic model of the dehydration reaction for AlPO4 · H2O indicate single kinetic mechanism and the F
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model as a simple n-order reaction of “chemical process or mechanism no-invoking equation”, respectively. The positive values
of ΔH# and ΔG# for the dehydration reaction show that it is endothermic and non-spontaneous process and it is connected with the introduction
of heat. The kinetic and thermodynamic functions calculated for the dehydration reaction by different techniques and methods
were found to be consistent. 相似文献
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Chanatip Samart Surachai Karnjanakom Chaiyan Chaiya Prasert Reubroycharoen Ruengwit Sawangkeaw Metta Charoenpanich 《Arabian Journal of Chemistry》2019,12(8):2028-2036
The experimental parameters for biodiesel production from para rubber seed oil and methanol using a SO3H-MCM-41 catalyst were optimized statistically. The SO3H-MCM-41 catalyst was synthesized by co-condensation in the presence of tetraethyl orthosilicate, 3-mercaptopropyl (methyl) dimethoxysilane (MPMDS) and cetyl-trimethylammonium bromide. In the last step, the solid catalyst (SH-MCM41) was oxidized by H2O2 to SO3H-MCM-41. The acid capacity of the obtained SO3H-MCM-41 catalyst was quantified by back titration with 0.1 M sodium hydroxide. The physical and chemical properties of the SO3H-MCM-41 were characterized by nitrogen adsorption/desorption, X-ray diffractometry, Fourier transform infrared spectroscopy and thermogravimetric analysis. The effect of varying the catalyst loading (wt.%), reaction time (h) and temperature (°C) and molar composition of MPMDS on the biodiesel yield were investigated using a 2k factorial design. The optimal conditions to maximize the biodiesel yield, obtained from the response surface analysis using a Box–Behnken design, was a 14.5 wt.% catalyst loading, and a reaction time and temperature of 48 h and 129.6 °C. Under these conditions a fatty acid methyl ester (biodiesel) yield of 84% was predicted, and an 83.10 ± 0.39% yield experimentally obtained. 相似文献
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Phutdhawong W Kawaree R Sanjaiya S Sengpracha W Buddhasukh D 《Molecules (Basel, Switzerland)》2007,12(4):868-877
Microwave-assisted hydrodistillation was used to isolate an essential oil from the leaves of Cinnamomum iners Reinw. ex Bl., and the results compared with those obtained by conventional hydrodistillation. The composition of the oil from both methods was found to be similar, and (-)-linalool was found as the main component (30-50%). The antioxidant activity of the essential oil obtained by both methods was evaluated using DPPH, ABTS, FRAP and lipid peroxidation methods, all of which indicated the same but insignificant activity. 相似文献