Reactivity of N-cyanoalkyl-substituted imidazolium halide salts by simple elution through an azide anion exchange resin

Certain N-cyanoalkyl-functionalized imidazolium halide salts unexpectedly undergo nitrile hydrolysis to amides, as well as dipolar cycloaddition to tetrazoles when eluted on azide anion exchanged resin.     

Isotope effect and bond-stretching phonon anomaly in high-Tc cuprates

We analyse a model where the anomalies of the bond-stretching LO phonon mode are caused by the coupling to electron dynamic response in the form of a damped oscillator and explore the possibility to reconstruct the spectrum of the latter from the phonon measurements. Preliminary estimates point to its location in the mid infrared region and we show how the required additional information can be extracted from the oxygen isotope effect on the phonon spectrum. The model predicts a significant measurable deviation from the “standard value” of the isotope effect even if the phonon frequency is far below the electron excitation spectrum, provided the latter is strongly incoherent. In this regime, which corresponds to the “mid infrared scenario”, the phonon linewidth becomes a sensitive and informative probe of the isotope effect.     

An electrochemical and structural investigation of silicon nanowires as negative electrode for Li-ion batteries

The electrochemical and structural responses of silicon nanowires deposited by chemical vapor deposition are investigated. Transmission electron microscopy and X-ray diffraction experiments show the electrochemical lithiation of SiNWs is not a quantitative process in good agreement with cycling experiments performed as a function of cycling limits. The SiNWs are not deeply lithiated as revealed by TEM micrographs. Our results suggest the existence of two well-defined lithiation steps, first at ∼0.2 V into amorphous silicon and then into crystalline silicon at ∼0.1 V. Cycling SiNWs above 100 mV avoid the lithiation of c-Si which preserves the silicon 3-D architecture and results in good cycling performances. A stable capacity value of ∼500 mAh g⁻¹ is achieved over at least 50 cycles.     

Continuity of solutions for parametric variational inequalities in Banach space

We consider here a type of pseudo-monotone parametric variational inequalities on a class of Banach spaces and show that such problems admit continuous (with respect to the parameter) solutions, as long as generic existence and uniqueness conditions for these solutions are satisfied. In particular, we show that such results are valid on a class of Banach spaces whenever we deal with strong pseudo-monotonicity, while others are valid in Hilbert spaces, whenever strict monotonicity is present. We also provide examples to illustrate the new results.     

Electrodeposition of Au/nanosized diamond composite coatings

Ultra-dispersed diamond UDD particles were codeposited in gold matrix coatings from a sulphite electrolyte, changing bath load and key operating parameters. The influence of electrolyte pH, current density and bath load on current efficiency, particle co-deposition, surface morphology and microhardness of composite coatings was investigated. UDD incorporation is mainly affected by bath load; however, particle embedding is specifically sensitive to electrolyte pH and deposition current density. The maximum mass fraction of carbon in the coating, about 0.55%, is obtained by depositing from ultrasonically pre-treated electrolytes with UDD concentration 20 g l⁻¹, pH 9.5 and 3 mA cm⁻² . Au/UDD composites are characterised by an increased microhardness and improved wear resistance. When compared to pure gold coatings which are notoriously weak, Au/UDD electrodeposits from sulphite electrolytes represent a significant improvement. Presented at the 4th Baltic Conference on Electrochemistry, Greifswald, 13–16, 2005     

Elemental analysis through X-ray techniques applied in archeological gold authentication — the case of Transylvanian gold and of the Dacian bracelets

To identify the provenance of gold archeological metallic artifacts, trace elements are more significant than the main components. The most promising elements are Platinum Group Elements (PGE), Sn, Sb, Hg, Pb, Te, and Cu. Several minute fragments of natural Transylvanian gold – placers and primary – were studied by micro Particle Induced X-ray Emission (micro-PIXE) at Forschungszentrum Dresden-Rossendorf, Germany and micro Synchrotron Radiation X-Ray Fluorescence (micro SR-XRF) at ANKA Synchrotron Radiation Facility of the Forschungszentrum Karlsruhe, Germany. The goal of the study was to identify the trace elements characterizing Transylvanian gold, especially Sn, Sb, Pb and Te. A spectacular application of these measurements to the authentication of nine Dacian gold bracelets is presented.     

Tuning a two-dimensional photonic crystal resonance via optical carrier injection

We report on wide wavelength tuning through optical injection of carriers of a photonic resonance observed in reflectivity at 1543 nm in an InP-based two-dimensional photonic crystal slab. An 8-nm blueshift, which represents 20 times the resonance linewidth, is observed when a 4-kW/cm2 intense optical pump is incident on the sample. An analytical model that we developed, based on a coupled-mode nonlinear approach, allows us to describe this phenomenon in detail.     

Reductions of an elliptic curve and their Tate-Shafarevich groups

In this paper we study the Tate-Shafarevich groups III_p of the reductions modulo primes p of an elliptic curve E/ considered as being defined over their function fields. Assuming GRH when E has no CM, we show that III_p is trivial for a positive proportion of primes p, provided E has an irrational point of order two.Research supported in part by an NSERC postdoctoral fellowship.Research supported in part by NSF grant DMS-98-01642.     

Projected Dynamical Systems and Evolutionary Variational Inequalities via Hilbert Spaces with Applications<Superscript>1</Superscript>

In this paper, we make explicit the connection between projected dynamical systems on Hilbert spaces and evolutionary variational inequalities. We give a novel formulation that unifies the underlying constraint sets for such inequalities, which arise in time-dependent traffic network, spatial price equilibrium, and a variety of financial equilibrium problems. We emphasize the importance of the results in applications and provide a traffic network numerical example in which we compute the curve of equilibria. ¹This research was funded by the Rockefeller Foundation, Bellagio Center Program. The first author was also supported by NSERC Discovery Grant 045997 and the third author by NSF Grant IIS-0002647. The authors thank Professors George Isac, Antonino Maugeri, and Panos Pardalos for support and inspiration; they are indebted to Professor Antonino Maugeri for assistance throughout their residency at Bellagio, Italy in March 2004.