Mixed gas fuel cells

Uniform mixtures of fuel together with air can be supplied to both cathode and anode of fuel cells and generate power as proposed before. The necessary condition for this to happen is an asymmetry in the catalytic properties of the electrodes. A few experimental works have demonstrated this over the last 5 years and a basic theoretical analysis has been recently presented. We here report on I-V measurements done using mixtures of H₂+O₂+Ar as well as using mixture of CH₄+O₂+Ar and C₂H₄+O₂+Ar. The solid electrolyte used is Y₂O₃ stabilized ZrO₂. For some of the low temperature measurements Nafion 117 is used as the SE. This allows for a better understanding of the catalytic activity of the electrodes. Paper presented at the 3rd Euroconference on Solid State Ionics, Teulada, Sardinia, Italy, Sept. 15–22, 1996     

DIFFUSE SPECTRAL REFLECTANCE MODIFICATION OF SKIN BY U.V. IRRADIATION

Abstract— Irradiation of guinea pig skin in vivo with light shorter than 300 nm produced a significant decrease in 330–400 nm reflectance. A similar decrease in reflectance was seen by irradiation of excised guinea pig and human skin. Chemical or physical vasodilation had no effect on the 240–400 nm reflectance. Irradiation of guinea pig skin in vivo with light longer than 300 nm produced no change in 330–400 nm reflectance unless photosensitized with 8-MOP. U.V. irradiation of skin (in the presence of suitable endogenous or exogenous photo-sensitizers) may result in the formation of new products that effectively absorb 330–400 nm photons.     

Exploring the synthesis and impact of end‐functional poly(3‐hexylthiophene)

In recent years, end‐functional poly(3‐hexylthiophene) (P3HT) has proven to be instrumental in the continued development and innovation within the broad conjugated polymer arena, enabling a variety of applications, particularly in organic electronics. The availability of P3HT with controlled molecular weights, low polydispersity, and importantly, a wide range of reactive end‐groups not only serves as a key building block for the preparation of conjugated block copolymers but also facilitates the development of hybrid nanocomposite materials via inorganic surface modification strategies. This Highlight focuses on the synthetic approaches to end‐functional P3HT and the impact of these systems in emerging technologies. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 831–841     

A Riemannian approach to reduced plate,shell, and rod theories

We derive a dimensionally-reduced limit theory for an n-dimensional nonlinear elastic body that is slender along k dimensions. The starting point is to view an elastic body as an n  -dimensional Riemannian manifold together with a not necessarily isometric W^1,2$W^{1,2}$-immersion in n-dimensional Euclidean space. The equilibrium configuration is the immersion that minimizes the average discrepancy between the induced and intrinsic metrics. The dimensionally-reduced limit theory views the elastic body as a k  -dimensional Riemannian manifold along with an isometric W^2,2$W^{2,2}$-immersion in n-dimensional Euclidean space and linear data in the normal directions. The equilibrium configuration minimizes a functional depending on the average covariant derivatives of the linear data. The dimensionally-reduced limit is obtained using a Γ-convergence approach. The limit includes as particular cases plate, shell, and rod theories. It applies equally to “standard” elasticity and to “incompatible” elasticity, thus including as particular cases so-called non-Euclidean plate, shell, and rod theories.     

Synthetic chemoselective rewiring of cell surfaces: generation of three-dimensional tissue structures

Proper cell-cell communication through physical contact is crucial for a range of fundamental biological processes including, cell proliferation, migration, differentiation, and apoptosis and for the correct function of organs and other multicellular tissues. The spatial and temporal arrangements of these cellular interactions in vivo are dynamic and lead to higher-order function that is extremely difficult to recapitulate in vitro. The development of three-dimensional (3D), in vitro model systems to investigate these complex, in vivo interconnectivities would generate novel methods to study the biochemical signaling of these processes, as well as provide platforms for tissue engineering technologies. Herein, we develop and employ a strategy to induce specific and stable cell-cell contacts in 3D through chemoselective cell-surface engineering based on liposome delivery and fusion to display bio-orthogonal functional groups from cell membranes. This strategy uses liposome fusion for the delivery of ketone or oxyamine groups to different populations of cells for subsequent cell assembly via oxime ligation. We demonstrate how this method can be used for several applications including, the delivery of reagents to cells for fluorescent labeling and cell-surface engineering, the formation of small, 3D spheroid cell assemblies, and the generation of large and dense, 3D multilayered tissue-like structures for tissue engineering applications.     

A resource allocation queueing fairness measure: properties and bounds

Fairness is an inherent and fundamental factor of queue service disciplines in a large variety of queueing applications, ranging from airport waiting lines to computer queueing systems. We study a newly proposed measure, a Resource Allocation Queueing Fairness Measure (RAQFM), first introduced in Raz, Levy, and Avi-Itzhak (Perform. Eval. Rev. 32(1):130–141, 2004). We analyze the properties of RAQFM and tie them to intuition, provide bounds for its values, and discuss briefly how it yields to analysis. This work was supported in part by the Israeli Ministry of Science and Technology, grant number 380-801, and by EURO-NGI network of excellence.     

Direct Acylation of C(sp3)−H Bonds Enabled by Nickel and Photoredox Catalysis

Using nickel and photoredox catalysis, the direct functionalization of C(sp³)?H bonds of N‐aryl amines by acyl electrophiles is described. The method affords a diverse range of α‐amino ketones at room temperature and is amenable to late‐stage coupling of complex and biologically relevant groups. C(sp³)?H activation occurs by photoredox‐mediated oxidation to generate α‐amino radicals which are intercepted by nickel in catalytic C(sp³)?C coupling. The merger of these two modes of catalysis leverages nickel's unique properties in alkyl cross‐coupling while avoiding limitations commonly associated with transition‐metal‐mediated C(sp³)?H activation, including requirements for chelating directing groups and high reaction temperatures.     

Deterministic extractors for affine sources over large fields

An (n,k)-affine source over a finite field is a random variable X = (X ₁,..., X _n ) ∈ , which is uniformly distributed over an (unknown) k-dimensional affine subspace of . We show how to (deterministically) extract practically all the randomness from affine sources, for any field of size larger than n ^c (where c is a large enough constant). Our main results are as follows: