Empirical tail conditional allocation and its consistency under minimal assumptions

Annals of the Institute of Statistical Mathematics - Under minimal assumptions, we prove that an empirical estimator of the tail conditional allocation (TCA), also known as the marginal expected...     

Electrodeposited polyaniline/Cu2ZnSnSe4 heterojunction

Journal of Solid State Electrochemistry - One-step method for the electrodeposition of thin Cu2ZnSnSe4 (CZTSe) film onto a polyaniline/FTO/glass substrate was developed. Polyaniline film was...     

Statistical foundations for assessing the difference between the classical and weighted-Gini betas

The ‘beta’ is one of the key quantities in the capital asset pricing model (CAPM). In statistical language, the beta can be viewed as the slope of the regression line fitted to financial returns on the market against the returns on the asset under consideration. The insurance counterpart of CAPM, called the weighted insurance pricing model (WIPM), gives rise to the so-called weighted-Gini beta. The aforementioned two betas may or may not coincide, depending on the form of the underlying regression function, and this has profound implications when designing portfolios and allocating risk capital. To facilitate these tasks, in this paper we develop large-sample statistical inference results that, in a straightforward fashion, imply confidence intervals for, and hypothesis tests about, the equality of the two betas.     

Electrochemical Polymerization of Pyrrole in the Presence of Sulfoacid Polyelectrolytes

Russian Journal of Electrochemistry - The pyrrole electrochemical polymerization in the presence of salt and acid forms of flexible-chain sulfoacid polyelectrolytes is studied comparatively....     

Wide-range regulation of polyaniline conduction by interphase doping of a polyaniline film

The not-sufficient-enough conductance of semioxidized protonated polyaniline (PANI) is usually attributed to the presence of ordered quasi-metallic domains surrounded by a poorly conducting amorphous phase. The paper presents experimental results testifying to the existence, in semioxidized PANI, of multilevel redox heterogeneity that crucially effects the conductance magnitude in view of specific topology at which higher-oxidized (conducting) domains are surrounded by less oxidized (poorly conducting) domains and because the PANI conduction is extremely sensitive to the oxidation degree. It is shown experimentally that the interphase doping with metals and degenerate semiconductors of a semioxidized salt of PANI and poly(2-acrylamide-2-methyl-1-propanesulfonic acid) (PAMPSA) with a 1: 2 ratio between PANI and PAMPSA raises the PANI-PAMPSA conductivity by 3–8 orders of magnitude due to the formation near the interface of thin layers whose conductance depends on the work function of the material in contact with PANI-PAMPSA and in extreme cases substantially exceeds the conductance of gold and copper at room temperature.     

The effect of counterion in polymer sulfonates on the synthesis and properties of poly-3,4-ethylenedioxythiophene

The electrochemical polymerization of 3,4-ethylenedioxythiophene (EDOT) in the presence of the salt and acid forms of polymer sulfonates with different polymer-chain flexibility is studied. The dependence of the rate of synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) on the nature of polysulfonate counterion that determines the type and distribution density of the charge in the polyelectrolyte chain is demonstrated. For the Н⁺ form of a rigid-chain polysulfonate, it is found that the specific interactions between parts of its macromolecules lead to destabilization of EDOT?⁺ radical cations, hinder the growth of PEDOT chains, and favor the formation of structures with the high degree of charge localization.     

Laser photoelectron projection microscopy of an organic conducting polymer

A conducting organic polymer is visualized on a laser photoelectron projection microscope, which is based on Letokhov’s concept and has a nanometer spatial resolution. Photoelectron images of polyaniline (which is the most promising representative of conducting polymers) with a magnification of ∼10⁵ have been obtained when a 100-nm quartz capillary coated with a film of this material was irradiated by femtosecond laser pulses. The projection photoelectron method using 400- and 800-nm laser radiation has made it possible to directly reveal the existence of the redox heterogeneity of the organic polymer, which is due to the contact of the sections of polyaniline with different oxidation degrees and strongly affects the electric conductivity of the sample.     

On the Role Played by Dimers of Radical Cations in the Process of Electrochemical Oxidation–Reduction of Polyaniline: The Data that Were Obtained Using the Method of Cyclic Voltabsorptometry in the Presence of Counteranions of a Diverse Nature

The electrochemical oxidation–reduction of films of polyaniline is studied in the presence of various counteranions. The differential cyclic voltabsorptometric (DCVA) curves (dA/dt relative to potential, where A is the optical absorption) are recorded at characteristic wavelengths corresponding to individual spectrum components previously isolated with the Alentsev–Fok method. The DCVA curves for aqueous solutions of HCl, HClO₄, and H₂SO₄ at different potential scan rates are compared to traditional cyclic voltammograms. For the DCVA curves obtained at 665 nm discovered is one broad peak of dA/dt in the region of potentials between the first and second stages of polyaniline oxidation (0.6 V vs. Ag/AgCl). An assumption is made about a chemical nature of the process of generation of absorption in this spectral region, which, more likely than not, is connected with the emergence of dimers of radical cations of polyaniline. It is discovered that the electrochemical processes in the region of potentials that correspond to the first stage of oxidation give rise to variations in the absorption inside several regions of spectrum: 435 nm (radical cations) and 755 nm (localized polarons). An assumption is made that the first peak of the current corresponds to several successive processes that occur in a polyaniline molecule in the course of oxidation as well as to the existence of heterogeneous regions where the generation of localized polarons proceeds at different rates.     

The spectroelectrochemical behavior of films of polyaniline interpolymer complexes in the near infrared spectral region

In this work, we carry out spectroelectrochemical studies of films of interpolymer complexes of polyaniline (PANI) prepared via the chemical and electrochemical template polymerization of aniline in the presence of polyamide sulfonic acids with different structures. It is shown that their spectroelectrochemical behavior in the near infrared region depends on the rigidity of the chain of the polymer sulfonic acid matrix. Electrodeposited films of PANI complexes with a rigid-chain polyacid exhibit a more intense absorption in the near infrared region (1000–2200 nm) and a less intense absorption in the absorption region of localized polarons (around 750 nm) in comparison with complexes with a flexible-chain polyacid. The comparison of the dependence of absorption in the near infrared region on potential with the cyclic voltammetry curves suggests that the chromophores responsible for this absorption are radical cations in nature. In the spectra of the films of chemically synthesized PANI complexes with a flexible-chain polyacid, during a long-term cycling in the region of potentials of the first redox stage of PANI, the absorption in the near infrared region which corresponds to delocalized polarons is also formed. This is apparently attributed to the intensification of the intermolecular interactions under the conformational fluctuations that accompany the change in the degree of oxidation of the film during cyclic voltammetry.