Seeking for reliable double-hybrid density functionals without fitting parameters: The PBE0-2 functional

Without the use of any empirical fitting to experimental or high-level ab initio data, we present a double-hybrid density functional approximation for the exchange-correlation energy, combining the exact Hartree-Fock exchange and second-order Moller-Plesset (MP2) correlation with the Perdew-Burke-Ernzerhof (PBE) functional. This functional, denoted as PBE0-2, is shown to be accurate for a wide range of applications, when compared with other functionals and the ab initio MP2 method. The qualitative failures of conventional density functional approximations, such as self-interaction error and noncovalent interaction error, are significantly reduced by PBE0-2.Comment: accepted for publication in Chem. Phys. Lett., 5 pages, 5 figures, 1 table, supplementary material not include

On the microstructure and mechanical property of as-extruded Mg-Gd-Y-Zn alloy with Sr addition

In this study, microstructure evolutions of Mg-6Gd-3Y-0.1Zn-xSr (x=0, 0.2, 0.6) alloys (named as sample 0Sr, 0.2Sr, 0.6Sr) during heat-treatment and extrusion were investigated. As-cast sample 0Sr contains typical long period stacking ordered (LPSO) phases and MgRE. With Sr addition, amounts of LPSO phases decrease and are gradually replaced by the MgSr phases. After homogenization and annealing treatment, profuse strip LPSO phases readily precipitate in grain interiors of sample 0Sr, while only MgSr and MgRE phases are detected in samples 0.2Sr and 0.6Sr. It suggests that the Sr addition would inhibit LPSO phases. After extrusion, the bimodal grain structures, the bulk and strip LPSO phases are detected in sample 0Sr, which can contribute to providing strengthening and extra strain hardening. In as-extruded sample 0.2Sr, finer recrystallized grain size, bulk MgSr and LPSO phases (micron-scale) and MgRE phase (nano-scale) are found due to the pre-annealing treatment. However, lower amounts of both nano-sized and macro-sized LPSO phases lead to the low ultimate strength (300 MPa). In sample 0.6Sr, the strip LPSO phases are readily formed even though the length and total amounts of LPSO phases decrease. More bulk MgSr phases and LPSO phases are also precipitated, which lead to the more superior yield and ultimate strengths of 0.6Sr sample under higher temperature, as compared with the 0Sr sample

Single nucleotide polymorphisms of complement component 5 and periodontitis

BACKGROUND AND OBJECTIVE: Polymorphisms of host defence genes might increase one's risks for periodontitis. This study investigated whether tagging single nucleotide polymorphisms (SNPs) of the gene encoding complement component 5 (C5) are associated with periodontitis in a Hong Kong Chinese population. MATERIAL AND METHODS: Eleven tagging SNPs of 229 patients with at least moderate periodontitis and 207 control subjects without periodontitis were genotyped using an i-plexGOLD MassARRAY mass-spectrometry system. RESULTS: Genotype AG of SNP rs17611 was more prevalent in the group of periodontitis patients than in the controls (54.6% vs. 41.7%, p = 0.007). The haplotype CGCA of the haplotype block consisting of rs1035029, rs17611, rs25681 and rs992670 was significantly associated with periodontitis in a dominant model (p = 0.001). The SNP rs17611 showed high linkage disequilibrium with rs1035029, rs25681 and rs992670. Smoking was also significantly associated with periodontitis (p = 0.006). CONCLUSION: The tagging SNP rs17611 of the C5 gene and smoking may be associated with periodontitis among the Hong Kong Chinese population.postprin

Genetic polymorphisms and periodontitis in Hong Kong Chinese

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catena-Poly[[(1,10-phenanthroline-κ2 N,N′)copper(I)]-μ2-iodido]

The solvothermal reaction of copper(I) iodide and 1,10-phenanthroline (phen) in ethanol yielded the title polymeric compound, [CuI(C12H8N2)]n. The asymmmetric unit comprises one Cu+ cation, one I− anion and one phen ligand. Each Cu+ cation is in a distorted tetrahedral coordination by two iodide anions and two N atoms from a bidentate chelating phen ligand. The Cu+ cations are bridged through the iodide anions, leading to a zigzag chain structure extending parallel to [100]. There are π–π inter­actions among adjacent phen ligands of one chain [centroid–centroid distance = 3.693 (3) Å]

NUMERICAL ANALYSIS OF THE EFFECT OF SURCHARGE ON THE MECHANICAL BEHAVIOR OF GEOCELL REINFORCED RETAINING WALL

Geocell reinforced retaining structure has been widely used in civil engineering for theprotection of slopes due to its advantages. In this paper, the effects of surcharge on the horizontaldisplacement of the wall back, the size of the sliding wedge and the factor of safety of geocellreinforced retaining wall are numerically analyzed by employing the geotechnical finite elementmethod software Plaxis. The research results show that, when the distance of surcharge from thewall face is small, the maximum and the minimum deformation of the wall back takes place nearthe top of the wall and the wall bottom respectively. After the distance of surcharge from the wallface exceeds about 13% of the wall height, the surcharge has little effect on the horizontaldeformation of the wall back, the size of the sliding wedge and the safety factor of geocellreinforced retaining wall. The horizontal deformation of the wall back gradually increases with theincrease of the length of the surcharge until it reaches a certain value. The effect of the length ofthe surcharge on the failure surface is not significant. Besides, the factor of safety of the wallgradually decreases with the increase of length of the surcharge. However, with the increase of thedistance of the surcharge from the wall face, the influence of the length of the surcharge on thesafety factor gradually becomes small. The study results can supplement theoretical basis for thedesign of geocell reinforced retaining walls in engineering practices