A Lefschetz hyperplane theorem for Mori dream spaces

Let X be a smooth Mori dream space of dimension ?? 4. We show that, if X satisfies a suitable GIT condition which we call small unstable locus, then every smooth ample divisor Y of X is also a Mori dream space. Moreover, the restriction map identifies the Néron?CSeveri spaces of X and Y, and under this identification every Mori chamber of Y is a union of some Mori chambers of X, and the nef cone of Y is the same as the nef cone of X. This Lefschetz-type theorem enables one to construct many examples of Mori dream spaces by taking ??Mori dream hypersurfaces?? of an ambient Mori dream space, provided that it satisfies the GIT condition. To facilitate this, we then show that the GIT condition is stable under taking products and taking the projective bundle of the direct sum of at least three line bundles, and in the case when X is toric, we show that the condition is equivalent to the fan of X being 2-neighborly.     

Compound nucleus contribution and even-odd effect for (3He,p) reactions in the Ni region

The compound nucleus contributions to the proton spectra from 8 MeV and 10 MeV ³He induced (³He, p) reactions on even-A Ni isotopes were obtained. The relative cross sections for ⁵⁸Ni/⁶⁰Ni/⁶²Ni in the high excitation region are in fair agreement with predictions of statistical theory, but the absolute cross sections in the same region are smaller than the prediction by a factor of 3 to 8, and the shapes of the measured spectra for heavier isotopes do not agree with the prediction. These discrepancies between experiment and theory are in sharp contrast to the situation in (p, p′), (p, α), (α, p) and (α, α′), where good agreement was found.The proton spectra from (³He, p) reactions on nuclei in the A = 54–68 mass range have a systematic difference in slope between even-A targets and odd-A targets; it is similar to the systematic difference found previously in (p, p′) and (α, p) reactions, but none of these is readily explainable by theory.     

Okounkov bodies and restricted volumes along very general curves

Given a big divisor D on a normal complex projective variety X, we show that the restricted volume of D along a very general complete-intersection curve C⊂X can be read off from the Okounkov body of D with respect to an admissible flag containing C. From this we deduce that if two big divisors D₁ and D₂ on X have the same Okounkov body with respect to every admissible flag, then D₁ and D₂ are numerically equivalent.     

The effective cone of the space of parametrized rational curves in a Grassmannian

We determine the effective cone of the Quot scheme parametrizing all rank r, degree d quotient sheaves of the trivial bundle of rank n on ${\mathbb{P}^1}$ . More specifically, we explicitly construct two effective divisors which span the effective cone, and we also express their classes in the Picard group in terms of a known basis.     

Mesoporous Nickel Electrode for the Detection of Alcohol

Mesoporous nickel electrodes have been shown to be excellent amperometric sensors for alcohol detection over a wide‐range of concentrations. At a higher electrolyte concentrations (NaOH, 4 M), the electrodes exhibited a remarkably higher sensitivity (1072.7 μA mM^?1 cm^?2) than conventional nickel based electrodes, within an alcohol concentration range 0.5–3 M. Additionally, electrodeposited Ni electrodes formed with Brij 56 as a template, have significantly higher roughness than similar electrodes made without template. Higher roughness factors correlated with higher sensitivities for alcohol sensing, but needed longer times to remove the template from the Ni film.     

Analysis of the FePO4 to LiFePO4 phase transition

The electrochemical phase transformation of carbon coated nanophase (60–70 nm) FePO₄ to LiFePO₄ was investigated by use of the Avrami–Johnson–Mehl–Eroofev equation. The analysis at three temperatures showed an Avrami exponent equal to one. Based upon reinterpretation and in agreement with recent microstructural evidence, a two-dimensional growth mechanism for the phase transformation is proposed in which the new phase grows in a direction perpendicular to the direction of lithium ion transport. Furthermore, the relatively low value of the activation energy for the phase transformation of 13 kJ/mol suggests that the phase transition is controlled by lithium ion diffusion along the phase boundary.     

Alkaline composite film as a separator for rechargeable lithium batteries

We report a new type of separator film for application in rechargeable lithium and lithium-ion batteries. The films are made of mainly alkaline calcium carbonate (CaCO₃) and a small amount of polymer binder. Owing to porosity and capillarity, the composite films show excellent wettability with non-aqueous liquid electrolytes. Typically, the composite films composed of CaCO₃ and Teflon and wetted with 1 M LiPF₆ dissolved in a solvent mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (30:70 wt%) exhibit an ionic conductivity as high as 2.5–4 mS/cm at 20 °C, in a comparable range with that (3.4 mS/cm) of the commercial Celgard membrane. In the batteries, the composite film not only serves as a physical separator but also neutralizes acidic products, such as HF formed by LiPF₆ hydrolysis, as well as those formed by solvent oxidative decomposition. A Li/LiMn₂O₄ test cell was employed to examine the electrochemical compatibility of the composite film. We observed that the composite film cell showed an improved cycling performance since the alkaline CaCO₃ neutralizes the acidic products, which otherwise promote dissolution of the electrode active materials. More importantly, the composite film cell displayed a superior performance on high-rate cycling, which was probably the result of the less resistive interface formed between the electrode and the composite film.     

Liquid crystals derived from 2-phenylisoindoles: synthesis and characterization

2-Phenylisoindole was investigated as the rigid core unit in a series of asymmetric mesogenic molecules. When the 2-phenylisoindole core was terminated with a hexyl tail, no mesophase formation could be observed. When 4- n -(tridecafluorohexyl) was used, however, both monotropic and enantiotropic phase behaviour were observed. It was found that most functionalities at the anhydride 5-position results in the formation of smectic A (SmA) phases in the temperature range 70-180°C. Functionalities at the anhydride 4-position suppress mesophase formation. Large substituents (-Br, -NO2) and symmetric substitution patterns (5,6-dichloro, 4,7-dichloro and 4,5,6,7-tetrachloro) on the anhydride moiety increase the melting point and destabilize the mesophase. Temperature dependent X-ray diffraction experiments suggest an interdigitated SmA packing for this family of compounds.     

Electrophoretic deposition of network-like carbon nanofiber as a conducting substrate for nanostructured nickel oxide electrode

A vapor-grown carbon nanofiber (VGCF) film with network-like architecture was fabricated by electrophoretic deposition (EPD) in the isopropanol suspension containing Ni(NO₃)₂ additive. Nickel ions adsorbed on the VGCFs increase the zeta potential of VGCFs, consequently, the EPD rate and nanofiber dispersion are remarkably improved. Nickel deposition is accompanied by reducing the nickel ions on the surface of VGCFs. Nickel appears to be suitable as a conducting metal binder for attaching the VGCFs. EPD of the nickel oxide on VGCF-coated film exhibits excellent capacitive behavior compared with that bare NiO electrode, resulting from the reduced electron conducting and charge-transfer resistances.