Electrochemical kinetics of nanosized Ag and Ag2O thin films prepared by radio frequency magnetron sputtering

Ag and Ag₂O thin films have been prepared by radio frequency magnetron sputtering on Cu substrates and have been characterized by X-ray diffraction, scanning electron microscope and atomic force microscope. The electrochemical performance of the thin films has been studied by galvanostatic cycling and cyclic voltammetry. The potential dependence of Li-ion chemical diffusion coefficients, [(D)\tilde]_\textLi {\widetilde{D}_{\text{Li}}} , of the films has been determined by galvanostatic intermittent titration technique and electrochemical impedance spectroscopy. It is found that Li-ion chemical diffusion coefficients of the Ag film range from 10⁻¹⁶ to 3 × 10⁻¹⁴ cm² s⁻¹. The Ag/Li₂O composite that is formed from Ag₂O after the first cycle exhibits higher [(D)\tilde]_\textLi {\widetilde{D}_{\text{Li}}} values than the Ag film, especially at a low Li-intercalation content. The phase transitions in the two-phase region cause a significant decrease of chemical diffusion coefficients.     

A one‐dimensional iodine‐bridged PtII/PtIV mixed‐valence complex,catena‐poly[[[bis­(ethyl­ene­diamine)­platinum(II)]‐μ‐iodo‐[bis­(ethyl­ene­di­amine)platinum(IV)]‐μ‐iodo] hydrogenphosphate dihydrogenphosphate iodide trihydrate]

The title compound, {[Pt^IIPt^IVI₂(C₂H₈N₂)₄](HPO₄)(H₂PO₄)I·3H₂O}_n, has a chain structure composed of square‐planar [Pt(en)₂]²⁺ and elongated octa­hedral trans‐[PtI₂(en)₂]²⁺ cations (en is ethyl­ene­diamine) stacked alternately along the c axis and bridged by the I atoms; a three‐dimensionally valence‐ordered system exists with respect to the Pt sites. The title compound also has a unique cyclic tetra­mer structure composed of two hydrogenphosphate and two dihydrogenphosphate ions connected by strong hydrogen bonds [O⋯O = 2.522 (10), 2.567 (10) and 2.569 (11) Å]. The Pt and I atoms form a zigzag ⋯I—Pt^IV—I⋯Pt^II⋯ chain, with Pt^IV—I bond distances of 2.6997 (7) and 2.6921 (7) Å, inter­atomic Pt^II⋯I distances of 3.3239 (8) and 3.2902 (7) Å, and Pt^IV—I⋯Pt^II angles of 154.52 (3) and 163.64 (3)°. The structural parameters indicating the mixed‐valence state of platinum, expressed by δ = (Pt^IV—I)/(Pt^II—I), are 0.812 and 0.818 for the two independent I atoms.     

Fluorescence modification of Gb3 oligosaccharide and rapid synthesis of oligosaccharide moieties using fluorous protective group

The use of the bisfluorous chain-type propanoyl (Bfp) group as a fluorous protective group made it possible to rapidly synthesize the Gb2 and Gb3 oligosaccharide derivatives by a simple fluorous-organic extraction purification. Furthermore, the fluorescence-labeled Gb2 and Gb3 oligosaccharides were prepared as a potential Vero Toxins detecting reagent.     

Electrochemical and thermal properties of hyperbranched polymer electrolytes for batteries

Terminal-acetylated hyperbranched poly(ethylene glycol) derivatives containing diethylene, triethylene, and hexaethylene and 3,5-dioxybenzoate branching units (poly-Ac1a, poly-Ac1b, and poly-Ac1c) were synthesized. Electrochemical and thermal properties of the hyperbranched polymer electrolytes with lithium salts such as LiCF₃SO₃ and LiN(CF₃SO₂)₂, the composite hyperbranched polymer electrolytes with LiN(CF₃SO₂)₂ containing α-LiAlO₂ and γ-LiAlO₂ fillers, and the hyperbranched polymer blended poly(ethylene oxide) electrolytes with LiN(CF₃SO₂)₂ were investigated and discussed. Paper presented at the 8th EuroConference on Ionics, Carvoeire, Algarve, Portugal, Sept. 16–22, 2001.     

Large-time solutions of the two-phase Stefan problem with delay

The paper is devoted to questions of an analysis of the large-time solutions to a class of two-phase Stefan problems with delay in the source terms of the governing equations. The case of one space dimension is considered. Results on the asymptotic behaviour of the solutions at t → ∞ are established.     

DNA DAMAGE and ITS REPAIR IN Dictyostelium discoideum IRRADIATED BY HEALTH LAMP LIGHT (UV- B)

Irradiation by health lamp (HL) light (280–320 nm) more efficiently induced cell killing and mutation in a radiation sensitive mutant (TW8) of Dictyostelium discoideum as compared with the parental wild-type strain (NC4). This light as well as a germicidal lamp-light (254 nm) produced pyrimidine dimers. The dimers were removed from DNA molecules by excision repair in NC4, but more slowly in TW8. It is suggested that pyrimidine dimers are the main DNA damage caused by HL light in D. discoideum , and that this results in cell killing and induced mutation.     

Synthesis of thromboxane A2 analogs—2 : (±)-Thiathromboxane A2

The total synthesis of (±)-11a-methano- 9,11-thiathromboxane A₂(1), the sulfur analog of thromboxane A₂ is described     

Mössbauer spectroscopic study of frozen solutions of57Co using a specially designed cryostat for time differential coincidence emission Mössbauer spectroscopy of237Np

Experiments on the⁵⁷Fe Mössbauer effect in frozen solutions were carried out in order to demonstrate the capabilities of a cryostat which was developed for the emission Mössbauer spectroscopy of²³⁷Np. We confirmed the existence of an aliovalent state of⁵⁷Fe in the temperature range from 5.5 to 35 K. However, the relative amounts of Fe(II) and Fe(III) in the frozen matrix were almost constant for the temperature range from 5.5 to 150 K. The design, operation and capabilities of the cryostat are also described.