Penguin diagrams for the HYP staggered fermions

We present results of the one-loop corrections originating from the penguin diagrams for the improved staggered fermion operators constructed using various fat links such as Fat7, Fat7+Lepage, $\bar{\rm Fat7}$, HYP (I) and HYP (II). The main results include the diagonal/off-diagonal mixing coefficients and the matching formula between the continuum and lattice operators.Comment: 4 figures, Contribution to Lattice 200

Topological domain walls and quantum valley Hall effects in silicene

Silicene is a two-dimensional honeycomb lattice made of silicon atoms, which is considered to be a new Dirac fermion system. Based on first-principles calculations, we examine the possibility of the formation of solitonlike topological domain walls (DWs) in silicene. We show that the DWs between regions of distinct ground states of the buckled geometry should bind electrons when a uniform electric field is applied in the perpendicular direction to the sheet. The topological origin of the electron confinement is demonstrated based on numerical calculations of the valley-specific Hall conductivities, and possible experimental signatures of the quantum valley Hall effects are discussed using simulated scanning tunneling microscopy images. Our results strongly suggest that silicene could be an ideal host for the quantum valley Hall effect, thus providing a pathway to the valleytronics in silicon-based technology.close12

Doctoral thesis recital (piano (lecture))

[Analysis of: Suite "Les douze signes" for piano / Eun-hye Kim]Musi

Doctoral thesis recital (piano)

All mein Gedanken; Ich schwebe; Morgen / Richard Strauss -- Eight Hungarian folksongs / Bela Bartok -- Zdes' khorosho / Sergei Rachmaninoff -- Horn trio in E-flat major, op.40 / Johannes Brahms.Musi

Controlling the Structural Robustness of Zirconium-Based Metal Organic Frameworks for Efficient Adsorption on Tetracycline Antibiotics

Tetracyclines (TCs) are the most widely used antibiotics for the prevention and treatment of livestock diseases, but they are toxic to humans and have frequently been detected in water bodies. In this study, the physical and chemical properties of the zirconium-based metal organic framework (MOF) UiO-66 and its NH2-functionalized congener UiO-66-NH2 were investigated along with batch TC adsorption tests to determine the effect of functionalization on TC removal. TC removal was highest at pH 3 and decreased with increasing pH. Pseudo-1st and pseudo-2nd-order kinetic models were used to study the adsorption equilibrium times, and Langmuir isotherm model was found to be more suitable than Freundlich model. The maximum uptake for UiO-66 and UIO-66-NH2 was measured to be 93.6 and 76.5 mg/g, respectively. Unexpectedly, the TC adsorption capacity of UiO-66-NH2 was observed to be lower than that of UiO-66. Density functional theory calculations revealed that the pore structures are irrelevant to TC adsorption, and that the -NH2 functional group could weaken the structural robustness of UiO-66-NH2, causing a reduction in TC adsorption capacity. Accordingly, robust MOFs with zirconium-based metal clusters can be effectively applied for the treatment of antibiotics such as TC in water

Mechanistic insights into the simultaneous removal of As(V) and Cr(VI) oxyanions by a novel hierarchical corolla-like MnO2-decorated porous magnetic biochar composite: A combined experimental and density functional theory study

A novel hierarchical corolla-like MnO2-decorated porous magnetic biochar composite (c-PMB/MnO2) was synthesized and used for the removal of As(V) and Cr(VI) from aqueous solutions. The experimental results indicated that the adsorption affinity order of c-PMB/MnO2 in the single-component system was As(V) (0.414 mmol/g) < Cr(VI) (0.421 mmol/g), whereas it was reversed in the binary-component system as As(V) (0.446 mmol/g) >> Cr (VI) (0.185 mmol/g), which were more pronounced in sequential adsorption systems. XPS results revealed that all components of c-PMB/MnO2 (i.e., Fe3O4, MnO2, and biochar) contributed to As(V) and Cr(VI) adsorption, while the selective reduction of adsorbed Cr(VI) to Cr(III) occurred via the redox reaction between Fe3O4 and Cr (VI). Density functional theory calculations further indicated that As(V) and Cr(VI) compete for the available binding sites in binary-component system, although the presence of reduced Cr(III) as a majority species serves as a strong binding site for As(V) via the formation of covalent bonding between Cr(III) and the O atom in As(V) with binding energies of - 123.1 and - 125.6 kcal/mol, thereby enhancing competitive As(V) adsorption in binary-component and sequential adsorption systems. These results may provide important information to better understand the competitive adsorption mechanisms for the simultaneous removal of As(V) and Cr(VI) in water

Progress on first-principles-based materials design for hydrogen storage

This article briefly summarizes the research activities in the field of hydrogen storage in sorbent materials and reports our recent works and future directions for the design of such materials. Distinct features of sorption-based hydrogen storage methods are described compared with metal hydrides and complex chemical hydrides. We classify the studies of hydrogen sorbent materials in terms of two key technical issues: (i) constructing stable framework structures with high porosity, and (ii) increasing the binding affinity of hydrogen molecules to surfaces beyond the usual van der Waals interaction. The recent development of reticular chemistry is summarized as a means for addressing the first issue. Theoretical studies focus mainly on the second issue and can be grouped into three classes according to the underlying interaction mechanism: electrostatic interactions based on alkaline cations, Kubas interactions with open transition metals, and orbital interactions involving Ca and other nontransitional metals. Hierarchical computational methods to enable the theoretical predictions are explained, from ab initio studies to molecular dynamics simulations using force field parameters. We also discuss the actual delivery amount of stored hydrogen, which depends on the charging and discharging conditions. The usefulness and practical significance of the hydrogen spillover mechanism in increasing the storage capacity are presented as well.close14