fax 01-972-952-9435. AbstractFoams used for gas or acid diversion exhibit two flow regimes, depending on foam quality. Two foam simulators, one the most widely used commercial foam simulator and the other developed at our university, fit steady-state foam behavior in both regimes. A simple procedure is described for fitting simulator parameters to a set of steady-state coreflood data and examples are shown. Fitting model parameters to a single coreflood data can err by fitting this datum to the wrong flow regime.Shear-thinning reported in the "low-quality regime" can increase foam injectivity in radial flow. Foams in lowquality regime fit the same correlation for overcoming gravity override previously derived for foam in the highquality regime. The flow regime does greatly affect the effect of capillary crossflow on foam diversion between layers differing in permeability, however.Capillary crossflow harms diversion between adjacent layers, as found earlier, but the magnitude of the effect is much less for foam in the low-quality regime, and no single correlation matches all the results. Capillary crossflow can actually increase (by a small amount) diversion from adjacent layers differing somewhat in permeability to distant layers with muchdifferent permeability.

Ni foam supported-Co3O4 nanowire arrays are prepared by a template-free growth method, followed by a thermal treatment in air, and are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, infrared spectroscopy, and thermogravimetric and differential thermal analysis. The Co3O4 nanowires have a diameter of about 250 nm, a length up to 15 μm, and a Brunauer-Emmett-Teller surface area of 78.4 m2 g−1. They grow almost vertically from the surface of Ni foam skeleton, pack densely, and uniformly cover the entire surface of Ni foam skeleton. Electroreduction of H2O2 on Co3O4 nanowire arrays in alkaline medium is investigated by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The Co3O4 nanowire electrode exhibits superior activity, stability, and mass transport property for H2O2 electroreduction. A current density of 90 mA cm−2 is achieved at −0.4 V in 0.4 mol dm−3 H2O2 and 3.0 mol dm−3 NaOH at room temperature. The per gram current density measured at −0.4 V on Co3O4 nanowires is about 1.5 times of that on Co3O4 nanoparticles.

No abstract

Supramolecular polymers based on host−guest molecular recognition have emerged as promising platforms for the development of smart materials. However, the studies on them are primarily conducted in solution and/or in the gel state. In contrast, little is known about dynamic properties and applications of supramolecular polymers in bulk. Herein, we present a selfcross-linking supramolecular polymer network (SPN) as a model system to understand the bulk properties controlled by noncovalent interactions. Specifically, the SPN monomer is composed of two benzo-21-crown-7 (B21C7) host units and two dialkylammonium salt guest moieties on a four-arm core, wherein complementary host−guest complexation drives the formation of the SPN with [2]pseudorotaxane linkages between B21C7 and ammonium motifs. The dynamic and reversible behaviors of the linkages are evaluated by measurement of viscoelasticity. The results indicate that the host−guest molecular recognition becomes highly dynamic at elevated temperature. Moreover, the relatively high activation energy of the SPN manifests itself as a new type of thermoplastic material with network topology freezing glass transition. Finally, we demonstrate how these findings provide insights into the malleability and processability of the SPN by simple demos. The fundamental understanding gained from the research on this SPN in bulk will facilitate the advancement and application of supramolecular materials.

Oxygen vacancies (OVs) are reported for the first time as an effective strategy to boost the electrochemical performance for amorphous electrode materials of sodium-ion batteries (SIB). Amorphous SnO2 is used as a model anode material to demonstrate the significant impact of OVs owing to the high attention it has received in the SIB field. Amorphous SnO2 ordered arrays are fabricated using the nanoimprinted anodic aluminum oxide (AAO) template and atomic layer deposition, and OVs are confined in the material by annealing the arrays in the N2 atmosphere. The OVs-containing amorphous SnO2 ordered arrays, used as binder-and conductive additive-free anodes, exhibit high reversible capacity and good cycle life by retaining the capacities of 376 mAh g-1 after 100 cycles at 0.05 A g-1 and 220 mAh g-1 after 800 cycles at 1 A g-1 as well as great rate capability by maintaining the capacities of 210 mAh g-1 at 10 A g-1 and 200 mAh g-1 at 20 A g-1. Electrochemical kinetic study reveals that the presence of OVs greatly enhances charge transfer/transport in the amorphous SnO2, thereby boosts the performance comparing with the OVs-free counterpart. This work highlights the importance of modulating defects in amorphous electrode materials towards promoted sodium storage.