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Various examples of composite titania-based nanostructured materials exhibiting cooperative functionalities between different active components are presented. The fabrication of these integrated composite materials is based on one-pot supramolecular templating techniques combined with acidic sol−gel chemistry. The defined 3-D nanoscale organization and integration of various functional components results in advanced optoelectronic and photonic applications such as visible light sensitization of mesoporous titania photocatalysts with cadmium sulfide nanocrystals acting as sensitizing integral part of the mesopore wall structure, narrow bandwidth emission from rare earth ion activated nanocrystalline mesoporous titania films, and mirrorless lasing in dye-doped hybrid organic/inorganic mesostructured titania waveguides.

Thin films of ordered mesoporous anatase have been prepared using a dip-coating procedure. Silver nanoparticles were introduced into the mesopores using wet impregnation followed by heat treatment. The cubic structured mesoporous titania had higher stability than the hexagonal structure and could be formed with a high content of nanocrystalline anatase with conservation of the meso-order. The high crystallite content was monitored by both X-ray diffraction and electron diffraction together with dark field transmission electron microscopy (TEM). The meso-order was studied using low-angle X-ray diffraction and TEM. The incorporated silver was formed within the mesopores of the titania, which acted as a template for the silver nanoparticles. X-ray photoelectron spectroscopy showed that both anatase and silver were present on the surface of the silver-loaded mesoporous titania. The synthesized titania films were evaluated for their photocatalytic activity for oxidation of stearic acid. It was found that the meso-ordered titania had a sufficiently high crystallite content to be photoactive and that the reaction mechanism resembled that of a non-meso-ordered titania sample. Upon incorporation of silver nanoparticles an apparent difference in reaction mechanism was found together with a higher apparent initial activity.

The temperature-dependent current−voltage and capacitance−voltage characteristics of interfaces between InP and a polypyrrole−phosphomolybdate hybrid material (PMH) are reported as a function of the redox potential, EPMH, of the PMH (as controlled by its extent of oxidation or p-type doping level). The current−voltage characteristics of the interfaces are sensitive to EPMH and can be controlled over a much wider range than possible with analogous InP|metal interfaces. For the n-InP|PMH interfaces, the ability to tune the current−voltage characteristics by controlling EPMH stems from control over the interfacial potential barrier φb characteristically present at semiconductor interfaces. The spatially averaged φb from capacitance−voltage measurements shifts from 0.59 to 1.05 V with a shift in EPMH from −0.05 to +0.99 V vs SCE, leading to an index of interface behavior of S = dφb/dEPMH = 0.39. For the n-InP|PMH interfaces, heterogeneous electron transfer is slower than at the semiconductor|metal interfaces:  the transmission coefficient κ, describing the probability that a carrier with sufficient thermal energy to surmount φb will actually cross the interface, is observed to be 0.003, independent of EPMH and less than the semiconductor|metal limit of κ = 1. For the p-InP|PMH interfaces, the extent to which the current−voltage characteristics can be controlled through manipulation of EPMH depends on both φb and κ. The S value for the p-InP interfaces is nearly identical with that for the n-InP|PMH interfaces:  the spatially averaged capacitance−voltage φb shifts from 0.83 to 0.49 V with a shift of EPMH from −0.07 to +0.65 V vs SCE, leading to S = 0.37. Over the same range of EPMH, the value of κ decreases from the range of 1−0.1 to the range 0.05−0.0001 as EPMH increases, suggesting that the majority carrier transfer rate depends on the details of the electronic structure of the PMH. The S values and empirical ideality factors observed for both the n-InP and p-InP interfaces are inconsistent with classic interface state models describing Fermi-level pinning. Nearly all of the interfaces demonstrate characteristic signatures of a heterogeneous barrier potential, such as, (1) ideality factors greater than unity and a decreasing function of temperature and (2) disagreement between the φb extracted from capacitance−voltage and temperature-dependent current−voltage measurements (Richardson plots). The quantitative application of Tung's barrier inhomogeneity model and the influence of heterogeneity on the extraction of κ and φb are discussed.

Vegetation may affect earthworm populations directly through inputs of litter and leachates, and indirectly through alteration of soil properties. This study examined the characteristics of earthworm populations on an area where small‐scale spatial patterns in soil properties were previously shown to be due to the influence of individual trees and understory species. Earthworm densities in the O horizon and in the upper 20 cm of mineral soil ranged from 0 to 20 and from 0 to 80 individuals/m2, respectively. Density was significantly lower in mineral soils under both yellow poplar (Liriodendron tulipiferaL.) and eastern hemlock (Tsuga canadensis[L.] Carr.) when rhododendron (Rhododendron maximumL.) was present in the understory, compared with under the same two tree species when rhododendron was absent. Bimastos parvusEisen, a species characteristic of inhospitable sites, was dominant on rhododendron plots, but was replaced by Komarekiona eatoniGates and Eisenoides carolinensisMichaelsen in the absence of rhododendron, especially on plots under yellow poplar. In mixed‐species forests, abundance and species composition of earthworm assemblages are spatially variable in correspondence with patterns of soil properties and of the occurrence of tree and understory plant species.

We use a one-dimensional random walk on D-dimensional hyper-spheres to determine the critical behavior of statistical systems in hyper-spherical geometries. First, we demonstrate the properties of such walk by studying the phase diagram of a percolation problem. We find a line of second and first order phase transitions separated by a tricritical point. Then, we analyze the adsorption-desorption transition for a polymer growing near the attractive boundary of a cylindrical cell membrane. We find that the fraction of adsorbed monomers on the boundary vanishes exponentially when the adsorption energy decreases towards its critical value. We observe a crossover phenomenon to an area of linear growth at energies of the order of the inverse cell radius.

A significant challenge for energy storage technologies is to realize battery-level energy density and capacitor-level durability and power density in one device. By introducing an electrolyte composed of an anionic catholyte and a cationic anolyte into a symmetric carbon-based supercapacitor configuration, a hybrid electrochemical battery-supercapacitor system using soluble redox species delivers significantly improved energy density from 20 to 42 W•h/kg (based on the electrode mass) and stable capacities for > 104cycles. The ionic species formed in the electrolyte are studied by UV-Vis, Raman and mass spectroscopy to probe the energy storage mechanism. The strategy is general and may provide a route to critically-needed fast-charging devices with both high energy density and power.