Multifunctional Redox Polymers: Electrochrome,Polyelectrolyte, Sensor,Electrode Modifier,Nanoparticle Stabilizer,and Catalyst Template

Simple “click” polycondensation metallopolymers of redox‐robust bis(ethynyl)biferrocene (biFc) and di(azido) poly(ethylene glycol) (PEG400 and PEG1000) were designed for multiple functions including improvement of water solubility and biocompatibility, the introduction of mixed valency and sensing capabilities, and as nanoparticle stabilizers for catalysis.     

Effects of head group size on the reaction methyl 4‐nitrobenzenesulfonate + Br− in water‐ethylene glycol cetyltrialkylammonium bromide micellar solutions

The reaction methyl 4‐nitrobenzenesulfonate + Br^? has been studied in water‐ethylene glycol cetyltrialkylammonium bromide (alkyl = methyl, ethyl, propyl, and butyl) micellar solutions by changing surfactant concentration as well as the weight percentage of ethylene glycol present in the bulk phase. The pseudophase model was adequate to rationalize quantitatively the micellar kinetic effects. Information about the influence of the head group size on the second‐order rate constant of the process and on the binding equilibrium constant of the organic substrate to the cationic micelles in water–ethylene glycol mixtures was obtained. Kinetic data taken from the literature were compared to those obtained in this work in order to examine the different effects produced by an alcohol that is localized in the bulk phase, such as ethylene glycol, with those caused by an alcohol that distributes between the bulk and micellar pseudophases, such as 1‐butanol. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 346–352, 2007     

Byzantine wall paintings from Kastoria, northern Greece: spectroscopic study of pigments and efflorescing salts

This study concerns the investigation of pigments and efflorescence phenomena on the wall paintings of Kastoria, a rural, non-metropolitan Byzantine town. A large number of representative samples were collected from the murals of three churches, dated to post-Byzantine era (14th-17th c. AD). The identified pigments for the red colour were hematite (Fe2O3), cinnabar (HgS) and minium (Pb3O4), while brown and yellow colours were attributed to mixtures of ochres (Fe-oxides and hydroxides) and lime. The utilization of admixtures of iron, lead and mercury compounds was also attested in order to render specific tones on the painted surfaces. Black and dark blue hues were prepared using black carbon and Mn in some cases. Grey colours were assigned to a mixture of black carbon and lime. Green colour is rather attributed to admixtures of Fe-rich minerals and lime and not to the commonly used green earths. Baryte (BaSO4) was also evidenced as a filler or extender. Phosphorous was detected and connected to proteinaceous material and Mo and Sb were traced which are probably affiliated to Fe-oxides. Regarding efflorescing salts, the determined compounds are: calcite, dolomite, gypsum, halite, nitratine, natron and mirabilite, all of which are related to temperature and humidity changes and moisture fluctuations inside the wall paintings.     

Experimental Study of Bacterial Penetration into Chalk Rock: Mechanisms and Effect on Permeability

Bacterial selective plugging is one of the mechanisms through which microorganisms can be applied for enhanced oil recovery, as bacteria can plug the water-swept zones of a reservoir, thus altering the flow paths and improving sweep efficiency. However, complete understanding of the penetration behavior of bacteria is lacking, especially in chalk formations where characteristic pore throat sizes are comparable with the sizes of bacterial cells. In this study, two bacterial strains, Bacillus licheniformis 421 (spore-forming) and Pseudomonas putida K12 (non-spore forming) were used to investigate the penetration of bacteria into chalk and its effect on permeability reduction. The core plugs were produced from Stevns Klint outcrop with low permeability (2–4 mD) and with pore sizes comparable to bacterial sizes. Both types of bacteria were able to penetrate and to be transported through the cores to some extent. A significantly higher number of B. licheniformis 421 was detected in the effluents as compared to P. putida K12. It was demonstrated that the spore-forming B. licheniformis 421 penetrates in the form of spores. P. putida K12 is found to penetrate the core, however, in smaller numbers compared to B. licheniformis. It was shown that both bacteria, under different injection concentrations, were capable of plugging the porous rock, as indicated by reduction of the core permeability. An incubation period of 12 days did not allow the permeability to return to initial condition. Based on the results it can be concluded that, when injected into chalk, spore forming bacteria have higher chance to survive and penetrate into deeper formation; and both types of bacteria may cause permeability reduction.     

Micro- and macro deformation measurement by extension of correlation technique

In this work, we present the implementation of Electronic Speckle Pattern Interferometry (ESPI), Digital Speckle Photography (DSP) and Digital Image Correlation (DIC) as complementary techniques to measure in-plane micro and macro displacement. The main advantage of ESPI is its great sensitivity to small displacements (smaller than the size of the speckle). However, the contrast of fringes in this technique is severely affected by de-correlation effects when the in-plane displacement exceeds the size of the speckle. To eliminate the de-correlation effects, we use the DSP technique. It is possible to generate artificial speckles, usually bigger than those generated by means of illumination of the sample with laser light. By combining DSP and DIC the displacement field can be obtained when the ESPI method cannot be applied due to image de-correlation. The experimental results show that the combination of these techniques is useful to analyze deformations over a wider range.     

Vibrations of rod-rigid element systems with a local non-linearity

The paper deals with vibrations of systems consisting of non-coaxial rods connected by rigid bodies and of a local non-linearity. The motion of the rods is described by classical wave equation and the solution of the d’Alembert type is applied in the study. This leads to solving ordinary differential equations with a retarded argument. The local non-linearity is described through irrational functions and in a special case it includes the polynomial of the third degree. Detailed considerations are given for a system consisting of three rods and two rigid bodies. In numerical analysis non-linear effects are discussed. The results concerning harmonic vibrations are presented for the local non-linearities having characteristics of a soft type as well as of a hard type.     

Vibration Problems in Selected Torsional Mechanical Systems

The paper deals with vibrations of mechanical systems torsionally deformed. These problems can be discussed using two-dimensional or one-dimensional models. After the presentation of basic equations for two-dimensional problems, the study is focused on one-dimensional problems for discrete-continuous systems with a local nonlinearity and on the effect of the local nonlinearity on the behaviour of these systems.     

Consecutive two-photon absorption of azulene in solution utilizing dye lasers

We report a spectroscopic study of consecutive two-photon absorption of azulene excited in the range 32800–42000 cm^?1, which provides information concerning the cross sections for the S₁ → S₃ and the S₁ → S₄ transitions.     

Study of the ligand substitution reaction Fe (CN)5H2O3− + pyrazine in micellar solutions

The ligand substitution reaction Fe(CN)₅H₂O³⁻ + pyrazine → Fe(CN)₅ pyrazine³⁻ + H₂O has been studied in sodium dodecyl sulfate SDS, hexadecyltrimethylammonium bromide, CTAB, and salt aqueous solutions at 298.2 K. Kinetics were studied in dilute and concentrated salt solutions and in SDS and CTAB solutions at surfactant concentrations below and above the critical micelle concentration. Experimental results show that salt effects can be explained by considering the interaction between the cations present in the working media which come from the background electrolyte, and the Fe(CN)₅H₂O³⁻ species in the vicinity of the cyanide ligands. This interaction makes the release of the aqua ligand from the inner-coordination shell of the iron(II) complex to the bulk more difficult resulting in a decrease of the reaction rate when the electrolyte concentration increases. Kinetic data in surfactant solutions show that not only micellized surfactants are operative kinetically, but also nonmicellized surfactants are influencing the reactivity. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 377–384, 1997     

Computational Study of Benzosultam Formation through Gold(I)-Catalyzed Ammoniumation/Nucleophilic Substitution Reaction

The Au(I)-catalyzed reactions of (2-alkynyl)phenylsulfonyl azetidines bearing terminal and non-terminal alkynes in the presence of methanol as protic nucleophile to form benzosultams derivatives were studied by density functional theory (DFT) calculations. Our study highlights that gold(I) catalyzed nucleophilic addition of the nitrogen on the alkyne is favored over the direct ring opening of the azetidine by methanol, confirming the ammonium-based mechanism. In addition, the reverse regioselectivity observed experimentally where non-terminal alkynes favors the formation of 6-endo-dig-benzosultams while terminal alkynes favor 5-exo-dig products is also explored through two different scenarios. The first one embraces the classical activation of the alkyne by a single Au(I) species while the second one tackles the formation of a σ,π-digold acetylide complex. Calculations identify both pathways as competitive although only mono Au(I) complexes can lead to final products, in good agreement with experimental observation. Further details on the importance of the presence of an excess of the protic nucleophile on the protodemetallation step and the final aminal formation is also discussed.