Orbital hybridization and charge transfer in carbon nanopeapods

We investigate the electronic structure of the fullerenes encapsulated inside carbon nanotubes, the so-called nanopeapods, using the first-principles study. The orbital hybridization of LUMO+1 (the state above the lowest unoccupied molecular orbital) of C60, rather than LUMO as previously proposed, with the nanotube states explains the peak at approximately 1 eV in recent scanning-tunneling-spectroscopy (STS) data. For the endohedral metallofullerenes nested in the strained nanotube, the charge transfer shifts the relative energy levels of the different states and produces a spatial modulation of the energy gap in agreement with another STS experiment.     

Stabilization of LiBH4 superionic phase by halide doping and H disordering

We performed first-principles density-functional theory calculations to investigate the structural properties and the effect of halide ion doping to the superionic-conducting, high-temperature phase and the effect of halide doping on the phase of LiBH₄. It is computationally demonstrated that the superionic phase is stabilized owing to the halide doping with the large ions which fill the interlayer space of the superionic phase. The H-disordered phase is observed in the structure and is found to contribute to the stabilization of the superionic phase.     

Penalized expectile regression: an alternative to penalized quantile regression

Annals of the Institute of Statistical Mathematics - This paper concerns the study of the entire conditional distribution of a response given predictors in a heterogeneous regression setting. A...     

Guaiacol as an Organic Superoxide Dismutase Mimics for Anti-ageing a Ru-based Li-rich Layered Oxide Cathode

High-capacity Li-rich layered oxides using oxygen redox as well as transition metal redox suffer from its structural instability due to lattice oxygen escaped from its structure during oxygen redox and the following electrolyte decomposition by the reactive oxygen species. Herein, we rescued a Li-rich layered oxide based on 4d transition metal by employing an organic superoxide dismutase mimics as a homogeneous electrolyte additive. Guaiacol scavenged superoxide radicals via dismutation or disproportionation to convert two superoxide molecules to peroxide and dioxygen after absorbing lithium superoxide on its partially negative oxygen of methoxy and hydroxyl groups. Additionally, guaiacol was decomposed to form a thin and stable cathode-electrolyte interphase (CEI) layer, endowing the cathode with the interfacial stability.     

Face-driven corner-linked octahedral nanocages: M6L8 cages formed by C3-symmetric triangular facial ligands linked via C4-symmetric square tetratopic Pd(II) ions at truncated octahedron corners

The face-driven corner-linked truncated octahedral nanocages, [Pd6L8]12+ (1, L1 = N,N',N' '-tris(3-pyridinyl)-1,3,5-benzenetricarboxamide; 2, L2 = N,N',N' '-tris(4-pyridinylmethyl)-1,3,5-benzenetricarboxamide), were prepared with eight C3-symmetric tridentate ligands and six square planar tetratopic palladium(II) ions. The combination of the nitrogen donor atom at a approximately 120 degrees kink position of the carboxamido pyridinyl group and the tilted pyridyl versus the facial plane of the ligands can provide the needed curvature for the formation of octahedral cages. The nitrogen atoms can coordinate to the square planar palladium(II) ions to form kinks with approximately 120 degrees angles at the C4-symmetric square planar corners of the truncated octahedron. Depending on the conformation of the ligand, L1, two different truncated octahedral cages of around 2.4 nm in diameters were formed. The major form of 1 with syn-conformational ligands has a cavity volume of approximately 1600 A3. The cage has 12 ports (3.4 x 3.5 A2) at all edges of the octahedron. The minor form of cage 1 with anti-conformational ligands has a slightly increased cavity volume ( approximately 1900 A3) and port size (3.3 x 8.0 A2). The insertion of a methylene group in L2 has not only increased the cavity volume of 2 to approximately 2200 A3 but also enlarged the port size to 4.1 x 8.0 A2. However, an atomic force microscopy (AFM) study of cage 2 showed that the cages had a height of 1.8 +/- 0.1 nm. This value is about 30% smaller than the calculated size of 2.6 nm from the crystal structure. This tip-induced decrease in height in cage 2 suggests the nonrigidity of cage 2.     

As(V) remediation using electrochemically synthesized maghemite nanoparticles

Maghemite nanoparticles were electrochemically synthesized from environmentally benign solutions in ambient conditions and utilized to remediate As(V) from aqueous solution. The average size and surface area of the maghemite nanoparticles were controlled to be 11–23 nm and 41–49 m² g^?1, respectively, by adjusting applied current density. The point of zero charge and crystallinity were independent of size. The effect of size and environmental conditions (i.e., maghemite nanoparticles content, contact time, and solution pH) on the adsorption of As(V) were systematically investigated. Similar to As(V) remediation using zero valent iron nanoparticles (NZVI), the kinetics of adsorption were best described by the pseudo first order model where the remediation is limited by the mass transfer of As(V) to adsorption sites of maghemite. The adsorption was spontaneous and endothermic which fitted with the Langmuir and Freundlich isotherms. The results observed in batch study indicate that maghemite nanoparticles were suitable adsorbent for remediating As(V) concentration to the limit (10 μg l^?1) recommended by the World Health Organization (WHO).     

Controllable synthesis, characterization, and magnetic properties of nanoscale zerovalent iron with specific high Brunauer–Emmett–Teller surface area

This article reports a novel approach for the controllable synthesis of nanoscale zerovalent iron (NZVI) particles with specific high Brunauer–Emmett–Teller (BET) surface areas. Borohydride reduction is a primary and effective liquid phase reduction method for the synthesis of zerovalent iron nanoparticles. However, previous methods for synthesizing NZVI did not suggest a standard technique for controlling the size of particles during the synthesis process; in addition, previous literature generally reported that NZVI had a BET surface area of <37 m²/g. In this communication, a novel approach for the controllable synthesis of NZVI particles with specific high BET surface areas is presented. As a result, the BET surface areas of the NZVI particles synthesized increased to 47.49 and 62.48 m²/g, and the particle sizes decreased to 5–40 and 3–30 nm. Additionally, the physical and chemical properties of the synthesized NZVI particles were investigated by a series of characterizations, and magnetic analysis indicated that the synthesized NZVI particles had super-paramagnetic properties.