A Puzzle of Quantum Phase Transition on Gd-IMC by Tuning of Conduction Electron Concentration

Based on the critical unstable of both crystal and magnetic structure of Gd-intermetallic compound near the competition of two strongly independent subsystem （＂local 4f7＂ and ＂conduction electron concentration＂）, a new QPT （quantum point transition） is predicted by calculation of： （1） The band structure and density of state by density functional theory where a strong narrowing fluidity of fermions around EF with shifted to negative value ＂-0.8 eV ＂is observable in the Gd-intermetalliccompound system while in the Y-case, it is not dominated. An antiferromagnetic state on the fluidity of conduction band can be investigated; （2） The internal magnetic field due to short range exchange interaction Jij between the nearest neighbor of local magnetic moment of stable s-state of Gd （L = 0） through the mean field approximation and of Eigenvalue-Eigenfunction ~.（k） are calculated. While a strong negative value of Jy is predicted, the eigenvalue L（k） of the system shows a strong antiferromagnetic phase in the reciprocal lattice direction 〈010〉, 〈001〉 in the correlation length 3.38 ~A. Although the antiferromagnetic state at Rc 〈_ 3.38 °A is a puzzle but it is completely dominated at Rc = 9 °A after passing through the competition between ）.λmin（O） and λmin（π） in the ranger of 3.2 °A 〈 Rc 〈 9 °A. Since both of the antiferromagnetic subsystems are sensitive to the predicted KF, the effect of decreasing of conduction electron is proposed to investigate, the change of the antiferromagnetic ordering state to the competition of ferromagnetic state （in direction 〈010〉） and antiferromagnetic state （in direction 〈001 〉 and 〈 100〉） resulted to paramagnetic state in the long range Rc = 9 °A.     

Studying the loading impact of silane grafted Fe2O3 nanoparticles on mechanical characteristics of epoxy matrix

This study investigates the loading impact of iron oxide (IO) and silane treated iron oxide (SIO) nanoparticles on thermal, mechanical and morphological behavior of epoxy matrix. Both IO and SIO nanoparticles were loaded with 1, 3 and 5?wt% from the total weight of epoxy matrix. The morphology of IO, and SIO epoxy nanocomposites are investigated by TEM. FTIR spectra are successfully able to confirm the good chemical interaction between SIO nanoparticles and epoxy matrix. Thermal resistance of epoxy IO, and SIO nanocomposites is studied by TGA. The mechanical properties of prepared nanocomposites including storage modulus, tan?δ, stress-strain curves and toughness are studied using DMA at temperature range 25?°C–100?°C. The results approved that loading 3?wt% of SIO nanoparticles improved the morphological, thermal resistance and mechanical characteristics of epoxy matrix.     

杂原子对沥青质分子间相互作用影响的计算化学研究

 沥青中大量的沥青质分子均含杂原子,通过计算化学方法,可以分析杂原子对沥青质二聚体结构及分子间相互作用的影响,并探究其影响机理。密度泛函理论计算结果表明,杂原子的存在使分子的静电势分布差别明显。对于稠环结构相似的沥青质分子,共轭硫原子使得分子的相互作用减小,含硫沥青质较远的质心距离和硫原子相对较弱的负电势使分子的取向和质心距分布更加随机。共轭氮原子作为强负电中心,强排斥增大分子取向偏离最低能量构型的能垒,从而使沥青质二聚体的构型取向更加趋于固定。同时分子动力学结果显示,含硫沥青质对温度敏感,温度升高更严重地加剧分子排列无序;而含氮沥青质在较高温度下依旧保持相对的有序排列。     

Adsorption of asphaltenes onto CaO,Co3O4, Fe3O4 and ZnO supported on 13X zeolite - An isothermal study

Abstract

Asphaltene has the highest molecular weight and the most polar organizers from petroleum. In this paper, the content of the asphaltenes from a crude oil was extracted and the amount of asphaltene in crude oil was measured to be 3.88%. Four metal oxides were added to 13X zeolite and 13X,10%CaO, 13X,10%Co₃O₄, 13X,10%Fe₃O₄ and 13X,10%ZnO were prepared. The adsorption behavior of the adsorbents was evaluated in asphaltenes adsorption. The capacity of the adsorbent for asphaltenes adsorption is as follows: 13X,10%CaO> 13X,10%Co₃O₄> 13X,10%Fe₃O₄> 13X,10%ZnO. The isotherm of adsorption of the asphaltenes over the adsorbent was studied and resulted that the experimental data could best fit with the Langmuir model, indicating that adsorption is as a monolayer.     

A Theoretical Study on the Interaction of Crown Tetraalanylpeptide with NO3- and SO4/2-

Crown peptide is a kind of special conformation found on the homodetic cyclopeptide, regular array about the main chain containing imido groups, and the monolithic conformation presents coronary analogy to crown ether. There are high symmetrical ionophores belonging to Cn point group. The channels or apertures can form easily for recognizing certain ion or molecular, and also the function of intending dual-recognition and the ability for transporting as ionophores can be possessed. Under the method of density functional theory, the geometry structures, values energy and population analysis of the combo of crown tetraalanylpeptide （C4-Ala） with NO3- and SO4/2- are calculated, based on the foundation of former studies. Compared with the structure of C4-AIa without NO3- and SO4/2- it is found that the coronary shape changes little in the complex of C4-Ala-YOm/n-, and the electrons transfer between C4-AIa and YOm/n- at the mean time. There are hydrogen bond between oxygen of YOm/n- and the hydrogen from imine groups of C4-AIa, and they become weaker when the average charge density lessens.