Bayesian Nonparametric Estimation for Reinforced Markov Renewal Processes

Starting from the definitions and the properties of reinforced renewal processes and reinforced Markov renewal processes, we characterize, via exchangeability and de Finetti’s representation theorem, a prior that consists of a family of Dirichlet distributions on the space of Markov transition matrices and beta-Stacy processes on distribution functions. Then, we show that this family is conjugate and give some estimate results.

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Surface chemical composition and fibrinogen adsorption-retention of fluoropolymer films deposited from an RF glow discharge

Fluoropolymer films have been deposited in the glow and afterglow regions of radio frequency glow discharges fed with C₂F₆−H₂ mixtures. Structure, growth rate, composition, and wettability of the films have been investigated by means of atomic force microscopy, electron spectroscopy for chemical analysis, secondary ion mass spectrometry, and water contact angle measurements.¹²⁵I labeled baboon fibrinogen in baboon plasma has been used to study the adsorption of the protein onto the films. Protein retention, i.e., the binding affinity of the adsorbed protein, has been examined by elution with a sodium dodecyl sulfate solution. Adsorption and retention of fibrinogen were correlated using multivariate statistical methods with the wettability, the degree of film fluorination, and the CF _x (1≤x≤3) group distribution of the coatings. This correlation identified the influence of each variable on the adsorption and retention of fibrinogen onto these substrates. These variables or surface properties can be easily balanced by properly tuning the experimental conditions of the glow discharge deposition process.     

Method for superposing reconstructed images from digital holograms of the same object recorded at different distance and wavelength

A method for allowing direct perfect superimposition and comparison of Fresnel-transform reconstructions of digital holograms recorded of the same object at different distances and wavelengths is proposed and demonstrated. The method takes into account the dependence of the reconstruction pixel on the distance and the wavelength by the Fresnel-transform algorithm. The method avoids the need for image scaling at the end of the reconstruction process that usually is performed in multi-wavelength digital holography. Demonstration is given by superposing the numerical reconstructions of holograms recorded at different distances and wavelengths. The method can be potentially very useful for real-time monitoring in biological processes or for recognition and ranging by multiple wavelengths of a target with fast movements or finally for very fast investigation and study of very fast processes.     

New π‐stacked benzofulvene polymer showing thermoreversible polymerization: Studies in macromolecular and aggregate structures and polymerization mechanism

The macromolecular and aggregate structures of poly[ethyl 1‐methylene‐3‐(4‐methylphenyl)‐1H‐indene‐2‐carboxylate] (poly‐ BF1 ; a new polymer based on a functionalized benzofulvene moiety showing interesting properties, i.e., thermoreversible polymerization/depolymerization behavior, high solubility in the most common organic solvents, and susceptibility to molecular manipulation) have been investigated with NMR spectroscopy, absorption and emission spectrophotometry, and transmission electron microscopy (TEM). Moreover, the polymerization mechanism has been studied to obtain further information on the polymer structure. The collected evidence is consistent in indicating for poly‐ BF1 a vinyl (1,2) polymer structure stabilized by means of aromatic stacking interactions. Furthermore, TEM studies performed on metal replicas have shown that the polymer is liable to give nanostructured aggregates. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3289–3304, 2005     

Selective grafting of amine groups on polyethylene by means of NH3−H2 RF glow discharges

Plasma treatments in Radio Frequency Glow Discharges fed with NH₃−H₂ mixtures have been performed for modifying polyethylene surfaces. Treatment kinetics and the role of species present in the glow have been investigated. Actinometric Optical Emission Spectroscopy has been utilized as a plasma diagnostic technique. Electron Spectroscopy for Chemical Analysis has been utilized for studying surface composition of treated substrates, which have been examined both astreated and after derivatization of amine-functionalities with 4-trifluoromethylbenzaldehyde vapors. It has been found that experimental plasma parameters and plasma density of active species can be controlled to achieve selective grafting of-NH₂ among all other nitrogen-containing groups.     

Synthesis and characterization of multifunctional polymers via atom transfer radical polymerization of N‐(ω′‐alkylcarbazolyl) methacrylates initiated by Ru(II) polypyridyl chromophores

A series of poly(N‐(ω′‐alkylcarbazoly) methacrylates) tris(bipyridine) Ru‐centered bifunctional polymers with good filming, thermal, and solubility properties were synthesized and characterized. Atom transfer radical polymerization (ATRP) of N‐(ω′‐alkylcarbazoly) methacrylates in solution was used, where Ru complexes with one and three initiating sites acted as metalloinitiators with NiBr₂(PPh₃)₂ as a catalyst. ATRP reaction conditions with respect to polymer molecular weights and polydispersity indices (PDI) of the target bifunctional polymers were examined. Electronic absorption and emission spectra of the resultant functional polymers provided evidence of chromophore presence within a single polymeric chain. The thermal properties of all polymers were also investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), and these analyses have indicated that these polymers possess higher thermal stabilities than poly(methyl methacrylate) (PMMA) obtained via free radical polymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6057–6072, 2005     

On first order congruences of lines in ℙ4 with irreducible fundamental surface

In this article we study congruences of lines in ?ⁿ, and in particular of order one. After giving general results, we obtain a complete classification in the case of ?⁴ in which the fundamental surface F is in fact a variety, i.e. it is integral, and the congruence is the irreducible set of the trisecant lines of F. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)