Direct electrochemical detection of bisphenol A at PEDOT-modified glassy carbon electrodes

The electrochemical behavior of bisphenol A (BPA) was studied on poly(3,4-ethylenedioxythiophene) (PEDOT)-modified glassy carbon electrodes by cyclic voltammetry. It was observed that BPA oxidation on PEDOT film produced a BPA polymer (pBPA) showing excellent redox activity with anodic and cathodic peaks at 0.15 and 0.01 V, respectively; the former being evaluated for BPA electrochemical sensing. The amount of deposited pBPA has been estimated by electrochemical and spectroscopic analysis by X-ray photoelectron spectroscopy. The effect of scan rate and pH on the oxidation of pBPA film has been studied. The oxidation current was found to vary linearly with BPA concentration in the range 90–410 μM, and a detection limit of 55 μM was evaluated. Results of BPA amperometric detection have also been collected by using a repetitive potential step program to give a linear response to BPA in the concentration range 40–410 μM with a detection limit of 22 μM and a sensitivity of 1.57 μAμM^?1?cm^?2. The developed sensor showed satisfactory reproducibility and anti-interference properties and was successfully applied to BPA determination in mineral water samples.     

119Sn Mössbauer characterization of self assembled organotin(IV) complexes with Schiff bases containing amino acetate skeletons

Several organotin(IV) compounds, viz., diorganotin(IV) compounds of the types Ph₂SnLH (monomer), ⁿBu₂SnLH·OH₂ (monomer), [Me₂SnLH·OH₂]₂ (centrosymmetric dimer), [ⁿBu₂SnLH]₃ (cyclic trinuclear), [Ph₂SnLH] _n (polymer), {[ⁿBu₂Sn(LH)]₂O}₂ (centrosymmetric tetranuclear), dinuclear di-/tri-mixed organotin(IV) compounds Ph₂SnLH·Ph₃SnCl (monomer) and triorganotin(IV) compounds of the types [Bz₃SnLH]₂ (centrosymmetric dimer) and [Me₃SnL¹H] _n (Polymer) (LH = Schiff base carboxylate) have been studied in the solid state at liquid nitrogen temperature using ¹¹⁹Sn Mössbauer spectroscopy. The tin coordination geometry of the compounds determined from crystallography was correlated with the ¹¹⁹Sn Mössbauer results.     

BDNF Val66Met polymorphism and protein levels in Amniotic Fluid

Background

Brain-Derived Neurotrophic Factor (BDNF) is a neurotrophin which plays survival- and growth-promoting activity in neuronal cells and it is involved in cellular plasticity mechanisms as it controls activity dependent synaptic transmission. A functional polymorphism (Val66Met) in the pro-region of BDNF, which affects the intracellular trafficking of proBDNF has been associated with memory and cognitive deficits as well as to an increased susceptibility for several psychiatric disorders especially those with a neurodevelopmental origin. To date, no study has evaluated the influence of the Val66Met polymorphism on BDNF levels in a peripheral system that may reflect fetal neurodevelopment. Therefore we investigated in amniotic fluids (AF) obtained from 139 healthy women during 15-17 week of pregnancy, BDNF protein levels in correlation with the Val66Met polymorphism.

Results

Interestingly we found a significant BDNF protein levels reduction in 55 Met carriers (Val/Met and Met/Met) (p = 0.002) as compared to 84 non carriers (Val/Val), and no effect of fetus gender, maternal age or gestation week on BDNF levels has been observed.

Conclusion

These results, although explorative, indicate that during fetal life the Val66Met genotype might influences BDNF protein levels in AF supporting the involvement of this polymorphism in behavioral and functional brain individual differences in the adulthood.     

The Sonogashira Coupling on Palladium Milling Balls—A new Reaction Pathway in Mechanochemistry

Utilizing direct mechanocatalytical conditions, the Sonogashira coupling was successfully performed on the surface of milling tools by using pure Pd and Pd coated steel balls. The optimization of co-catalyst forming additives led to a protocol, which generates quantitative yields under aerobic conditions for various substrates within as little as 90 minutes. Using state-of-the-art spectroscopic, diffractive, as well as in situ methods lead to the identification of a previously unknown and highly reactive complex of the co-catalyst copper. This new complex differs substantially from the known complexes in liquid phase Sonogashira couplings, proving that reaction pathways in mechanochemistry may differ from those in established synthetic procedures.     

Elastic Moduli: a Tool for Understanding Chemical Bonding and Thermal Transport in Thermoelectric Materials

The elastic behavior of a material can be a powerful tool to decipher thermal transport. In thermoelectrics, measuring the elastic moduli—directly tied to sound velocity—is critical to understand trends in lattice thermal conductivity, as well as study bond anharmonicity and phase transitions, given the sensitivity of elastic moduli to the chemical bonding. In this review, we introduce the basics of elasticity and explain the origin of high-temperature lattice softening from a bonding perspective. We then review elasticity data throughout classes of thermoelectrics, and explore trends in sound velocity, anharmonicity, and thermal conductivity. We reveal how experimental sound velocities can improve the accuracy of common thermal conductivity models and present a critical discussion of Grüneisen parameter estimates from elastic moduli. Readers will be equipped with tools to leverage elasticity measurements or calculations to accurately interpret thermal transport trends.     

Free Amino Group Transfer via α-Amination of Native Carbonyls

We report herein a straightforward transfer of a free amino group (NH₂) from a commercially available nitrogen source to unfunctionalized, native carbonyls (amides and ketones) resulting in direct α-amination. Primary α-amino carbonyls are readily produced under mild conditions, further enabling diverse in situ functionalization reactions—including peptide coupling and Pictet–Spengler cyclization—that capitalize on the presence of the unprotected primary amine.     

The study of the mural painting in the 12th century monastery of Santa Maria delle Cerrate (Puglia‐Italy): characterization of materials and techniques used

A multidisciplinary research was conducted by the University of Salento in collaboration with the Lecce Provincial Museum, in order to study different forms of art widespread in the Salento peninsula (Southern Italy) very valuable from an artistic point of view and important as driving force for the tourism of the area. In this research, the archaeometrical analysis was used to study the first cycle of paintings of the church of Santa Maria delle Cerrate, an italo‐greek monastery located in the country about 15 km north‐east of Lecce, probably built in the 12th century. Microscopic, chromatographic and spectrometric techniques were used: optical microscopy was used to study samples and the relevant stratigraphy, micro‐Raman Spectroscopy to identify pigments and Gas Chromatography with Mass Spectrometric Detection to investigate the techniques masters used to decorate the monastery church. Further information on organic and inorganic materials present in the samples were obtained from Fourier transform infrared analysis in attenuated total reflectance. Materials and techniques were clearly ascertained, and, interestingly, pigments were applied both by fresco and egg‐based tempera. Among the various pigments detected, the identification of both lapis lazuli and lead white opened new perspectives both from the historical and conservative points of view. Copyright © 2013 John Wiley & Sons, Ltd.     

Immobilized Rose Bengal as Photocatalyst for Metal-Free Thiocyanation of Azaheterocycles under Continuous Flow Conditions

The immobilization of Rose Bengal onto Merrifield resin and its application in the light-driven metal-free thiocyanation of azaheterocycles in continuo were investigated. The supported photocatalyst was used in batch reactions under heterogeneous conditions, with different azaheterocycles, and proved to efficiently promote the reaction. Its recovery and recycle were also demonstrated for up to four times. The resin-supported Rose Bengal was then employed under continuous flow conditions, affording thiocyanate functionalized azaheterocycles with higher space-time-yields than the in-batch transformations, and in a shorter reaction time. The easily modification of the SCN groups was also demonstrated by synthetizing trifluoromethyl thioethers and sulfenyl tetrazoles derivates in high yields.     

Structure‐dependent conductivity and microhardness of metal‐filled PVC composites

Metal‐filled composites of a commercial PVC (polyvinyl chloride) powder (mean particle size d_p ≈ 100 microns) and a metal powder (mean particle size d_f about 100 microns for copper, Cu, and about 10 microns for nickel, Ni) prepared by mechanical mixing in a ball mill, subsequent hot‐pressing at 443 K and rapid cooling to 300 K, were characterized by the room‐temperature measurements of electrical conductivity σ, density ρ and microhardness H. The sudden jumps of about 17 orders of magnitude followed by a much slower growth up to the limiting filler fraction ϕ* on the log σ vs. ϕ plots are the evidence for the onset of percolation transitions, at filler volume contents ϕ_c1 = 0.05 and 0.04 for PVC/Cu and PVC/Ni, respectively. For both systems, the values of H exhibited an initial steep increase up to ϕ_c2 = 0.07, followed by an apparent plateau extending up to ϕ = 0.18. However, drastic differences in the patterns of composition dependence of H were observed at higher metal loadings, i.e., a continuous increase of H up to the leveling‐off at ϕ* for PVC/Cu, in contrast to a sudden drop of H at ϕ = 0.20 and subsequent slow increase for PVC/Ni. For both composites the apparent density ρ′ of a polymer matrix remained the same as that of the neat PVC in the composition interval ϕ < 0.20, while at ϕ* > 0.20 a precipitous drop of ρ₁ was observed due to the formation of polymer‐free voids between filler particles (crowding effect) as ϕ approaches ϕ*. The observed effects were analyzed in terms of a tentative model envisaging cross‐overs from “dilute suspension regime” to “semi‐dilute suspension regime” in the concentration range ϕ_c1 to ϕ_c2, and from “semi‐dilute suspension regime” to “concentrated suspension regime” above ϕ = 0.20. Different behavior in this latter regime was explained by intrinsic differences in the structure of conductive infinite clusters between mixtures of particles of about the same size (PVC/Cu) and of widely different sizes (PVC/Ni).