Polarization-dependent ablation of silicon using tightly focused femtosecond laser vortex pulses

We demonstrate experimentally that, in a tight focusing geometry, circularly polarized femtosecond laser vortex pulses ablate material differently depending on the handedness of light. This effect offers an additional degree of freedom to control the shape and size of laser-machined structures on a subwavelength scale.     

A coordinating contract for transshipment in a two-company supply chain

We study a supply chain with two independent companies producing an identical product and cooperating through transshipment. Previous studies of this chain show that only under certain conditions, linear transshipment prices could be found that induce the companies to choose the first best production quantities. Moreover, even if such transshipment prices do exist, they result in a unique division of total expected profit and thus they cannot accommodate arbitrary divisions of the profit. Using the Generalized Nash Bargaining Solution, we derive coordinating transshipment prices that always give rise to a coordinating contract for the chain. This contract relies on an implicit pricing mechanism.     

A variety generated by a finite algebra with 2x 0 subvarieties

As was indicated to me by Prof. A. Wroński, the following problem was suggested by Prof. B. Jónsson: is every subvariety of the variety of a finite algebra generated by a finite algebra? In this paper we solve this problem in the negative by constructing a finite algebra that generates a variety having 2^x ₀ subvarieties.     

Determination of As,Bi, Sb and Sn in conifer needles from various locations in Poland and Norway by hydride generation inductively coupled plasma atomic emission spectrometry

Hydride generation inductively coupled plasma atomic emission spectrometry (HG-ICP-AES) in the system with aerosolised sample introduction has been employed for the first time for analysis of conifer needles. Arsenic, bismuth, antimony and tin along with other trace elements were simultaneously determined in pine, spruce, yew and thuja foliage sampled from various locations in Poland and Norway. Quality of the measurements was assured by examination of two attested plant reference materials. The application of different analyte introduction techniques and interference effects from matrix elements, i.e. Na, K, Mg, Ca and transition metals in the analysis of needles are discussed.     

Dielectric Studies of the Ordering Due to an External DC Electric Field in Nematic 4,4′-di-n-hexyloxyazoxybenzene

Studies of dielectric permittivity changes under the action of a DC electric field on nematic 4,4′-di-n-hexyloxyazoxybenzene (DHAB) have been performed. Observations of time dependent processes occurring during the application of a voltage were made for samples of 0.5–2 mm thickness as a function of the applied voltage. The dielectric permittivity changes which are related to changes in the ordering of the samples were interpreted in dielectric as well as in electrohydrodynamic terms. Three voltage regions were distinguished which are characterised by ordering due to dielectric orientation, hydrodynamic laminar flow and turbulent flow.     

Linear-sweep voltammetry at a dropping mercury electrode in continuous flow systems

Linear-sweep voltammetry at a dropping mercury electrode is examined in flowing systems with parallel, opposite and normal mercury and fluid flow. The influence of fluid velocity (0–12 cm s^?1) on current and potential parameters of linear-sweep voltammograms is described. The ranges of fluid velocity in which current parameters are independent of flow, were determined by analysis of variance. It is shown that at certain sweep rates, the current does not depend on fluid velocity up to 12 cm s^?1.     

Electron transfer and dynamic infrared-band coalescence: it looks like dynamic NMR spectroscopy, but a billion times faster

Broadening and coalescence of infrared bands can occur due to chemical exchange processes occurring on very fast, femtosecond-to-picosecond timescales. One such fast process of recent investigation is intramolecular electron transfer in transition-metal complexes with strong communication between electron-donor and -acceptor sites. The observation of partial coalescence of metal-carbonyl stretching bands in hexanuclear ruthenium mixed-valence complexes due to electron-transfer rates on the order of 10(11)-10(12) s(-1) is chronicled here. Several important advances have been made with the aid of dynamic infrared-band coalescence in these complexes, including the observation of dynamic solvent relaxation effects on electron-transfer rates, the determination of the equilibrium constant between charge-transfer isomers, and a reconsideration of the theory of electron transfer and delocalization in bridged, near-delocalized electron-transfer systems.