Carbon nanohorns-coated microfibers for use as free-standing electrodes for electrochemical power sources

We report the first direct laser based synthesis of carbon nanohorns onto carbon microfibrous, for the straightforward fabrication, of free-standing (binderless) electrodes. These carbon nanohorns have diameters as small as 2–4 nm and were found to cover uniformly the microfibrous substrates. The carbon nanohorns-based electrodes developed here are shown to open new prospects for the development of advanced electrochemical power sources. In particular, their possible applications in either lithium-ion batteries or supercapacitors or fuel cell technologies are demonstrated.     

Cyclophane porphyrins and their metal complexes: Biomimetic study on receptor site of hemoprotein oxygen binding

A new symmetric porphyrin, 7,8,17,18-tetraethyl-3,13-dimethylporphyrin-2, 12-dipropionic acid and its derivatives were synthesized by the a,c-biladiene route. Condensation of the dipropionic acid with diamine, [H₂N(CH₂)_nNH₂, n= 6,7,8,9,10,12, and14], afforded the corresponding cyclophane porphyrins. The bridged groups were characterized by the ¹H-NMR spectra of their zinc complexes. The spin state of the Fe(III) complexes of the cyclophane porphyrins was investigated by changing the size of the bridged chain or size of axial ligand. The cyclophane-porphyrinato (III) perchlorate complexes in a mixture of MeOH and CHCl₃, with 4-benzylpyridine provide a model for methemoproteins. Steric constraint between an axial ligand and the bridge group, [-CH₂CH₂CONH(CH₂)_nNHCOCH₂CH₂]at the bridged face determines the ratio of the penta- and hexa-coordinated ferric complexes. The rate of O-binding to the Co(II) cyclophane porphyrins is mar present result indicates that removal of a solvent molecule or sixth axial ligand from the near proximity of the Co(II) complex increases the rate of O- binding.     

Conductivity of polydiacetylene with π-conjugation between polymer backbone and substituents

Poly-1,4-bis(3-acetamidephenyl)-1,3-butadiyne, i.e., a topochemically obtained polydiacetylene for which one can expect π-conjugation between polymer backbone and substituents, has been examined as a candidate of conducting polymers. Upon iodine doping, the polymer film attained the conductivity of 4.8 × 10^?2 S/cm, i.e., about three orders of magnitude greater than those of other polydiacetylene films which have no such π-conjugation.     

Epitaxial polymerization of 1,3-butadiyne by chemical vapor deposition

1,3-Butadiyne was epitaxially polymerized on the graphite basal plane by chemical vapor deposition to form a homogeneous thin film. The film thickness varied from 100 to 3000 Å depending on the polymerization condition. The films on the graphite showed a variety of interference colors such as blue, purple, or gold depending on the film thickness. Raman spectra revealed that the polymerized film was mainly composed of ? C?C? bonds. Electron diffraction pattern and the ESCA spectrum of the film were quite similar to those of graphite, suggesting that butadiyne was polymerized in an epitaxial manner.     

Resonance Raman spectra of 15N enriched metallooctaethylorphyrins. Characterization of the oxidation state marker bands of hemoproteins

Resonance Raman spectra of ¹⁵N enriched metallooctaethylporphyrins [M(OEP) ? ¹⁵N₄] [M = Ni²⁺, Fe³⁺ (high spin), and Fe³⁺ (low spin)] were observed. Polarized Raman lines corresponding to the oxidation state marker band of hemoproteins were observed at 1377 (Ni), 1369 (Fe high spin) and 1372^?1 (Fe low spin) which were shifted to lower frequency from those of the ¹⁴N compounds by 6, 5, and 6 cm^?1, respectively. The vibrational mode for this band was shown to include an appreciable contribution of the C_αN symmetric stretching vibration and to be associated with ca. 0.01 Å of in-phase displacement of the four pyrrole nitrogens toward the metal ion.     

Investigation into the surface relief grating mechanism via XPS in new azobenzene based optical material

Research into azobenzene and its compounds focuses on the molecules ability to cis‐trans isomerize, this photoisomerization enables surface relief gratings (SRGs) to be formed on the azobenzene functionalized polymer films. SRG allows information to be written and then erased, an essential requirement of most modern electrical products. The interest into SRG photofabrication is thus rapidly increasing and is emerging at the forefront of photonic and nanotechnology research. The surface relief grating mechanism, however, is not fully understood, a photoplasticization process is postulated, which is thought to occur via the azo‐chromophores photoisomerization, so encouraging polymer chain migration to the surface. In comparison, suggestions have shown the SRG process does not involve a change in the film surface profile but in the local refractive index. Currently, no research has yet established the surface relief grating mechanism, this paper sets out to determine the mechanism and investigate those theories already postulated by observing the thin film surfaces prior to and after SRG using X‐ray photoelectron spectroscopy (XPS). By identifying the surface components, greater insight and understanding of the SRG mechanism can be achieved. In this paper, poly(4‐(N‐(2‐methacryloyloxyethyl)‐N‐ethylamino)‐4′‐nitroazobenzene)₉₀‐co‐(methylmethacrylate)₁₀ 50 : 50 PMMA blend was exposed to SRGs. Using XPS the surface composition was determined prior to and after SRG. Following SRG, the spectra for O 1s, N 1s and C 1s using XPS expressed a change in the components at the surface. This is most evident in the N 1s spectra, with PMMA not containing nitrogen, the N 1s becomes the determining factor. The nitrogen absence combined with a significant increase in the carbon and oxygen peak intensity concludes the azobenzene lies not on the surface but, in fact, within the bulk after SRG. The initial light irradiation process must be a consideration. However, on X‐ray analysis the sample showed the same spectra as the one prior to SRG. Copyright © 2002 John Wiley & Sons, Ltd.     

Weighted inequalities for iterated maximal functions in Orlicz spaces

Let M be the classical Hardy‐Littlewood maximal operator. The object of our investigation in this paper is the iterated maximal function M^kf(x) = M(M^k?1f) (x) (k ≥ 2). Let Φ be a φ‐function which is not necessarily convex and Ψ be a Young function. Suppose that w is an A′_∞ weight and that k is a positive integer. If there exist positive constants C₁ and C₂ such that ((I)) then there exist positive constants C₃ and C₄ such that ((II)) where the functions a(t) and b(t) are the right derivatives of Φ(t) and Ψ(t), respectively. Conversely, if w is an A₁ weight, then (II) implies (I). Another necessary and sufficient condition will be given. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)