Chelate polymers. VI. New copolymers of the some siloxane containing bis(2,4-dihydroxybenzaldehyd-imine)Me with bis(p-carboxyphenyl)diphenylsilane

New high complex polymeric structures containing metal chelate sequences alternating, through esteric bridges, with silane units were obtained. The azomethine of 2,4-dihydroxybenzaldehyde with 1,3-bis(aminopropyl)tetramethyldisiloxane has been synthesized and in situ complexed with copper (II), nickel (II), cobalt (II) and cadmium (II). The obtained bis-phenolic chelates were covalently inserted in polymeric linear structures by their polycondensation with bis(p-carboxyphenyl)diphenylsilane as a diacid chloride. The structures of the obtained polymers were confirmed by IR, UV, ¹H NMR and elemental analysis. The characterization was made by TGA, DSC, solubility tests and GPC. The electrical conductivity of both chelate monomers and their polymers was investigated, all compounds showing typical semiconducting behaviors.     

In Process Citation

Some aliphatic amines have been titrated enthalpimetrically. The heats of neutralization have been calculated from the results and correlated with the basicity of the amines and the number of hydroxyl and amine groups present. The titration curves were all plotted on Cartesian coordinates and again on oblique coordinates to eliminate secondary thermal effects. The order of basicity is ethylamine < ethanolamine, and ethylamine < diethylamine > triethylamine, the last because of steric factors reducing the basicity of the tertiary amine. The low basicity of ethanolamine relative to ethylamine is atttributed to the inductive effect of the hydroxyl group. Ethylenediamine contains two amino groups, one of which is hydrated in solution and the other protonated; the existence of the protonated group together with the electron-withdrawing power of the hydroxyl group accounts for the lower second dissociation. The ethanolamines are more feeble bases than di- and triethylamine, because of the presence of the hydroxyl group. A steric factor further reduces the basicity of triethanolamine. These facts are confirmed by the experimental heats of neutralization.     

Kinetic analysis of sequence of two consecutive reactions from thermogravimetric data under non-isothermal conditions. I. Calculated thermograms

This paper suggests a method of drawing the thermogram of a sequence of two consecutive, partially overlapping processes of a given order, run under non-isothermal conditions.     

Simultaneous impedimetric and amperometric interrogation of renal cells exposed to a calculus-forming salt

The complexity of the cellular response, induced even by the simplest experimental stimulus, requires an increased number of cellular parameters to be simultaneously monitored. An all electrochemical system allowing the simultaneous and real-time monitoring of both cell adherence and superoxide release into the extracellular space was developed to address this challenge. Cell adherence (to neighboring cells and to substrate) was monitored using non-faradaic impedance spectroscopy while the superoxide release was monitored using a cytochrome c-based amperometric biosensor. The system was used to observe for the first time how these two cellular parameters are changing in real-time for renal cells exposed to calcium oxalate, a calculus-forming salt. It was discovered that calcium oxalate crystals decrease cell adherence and in the same time induce oxidative stress by an overproduction of superoxide. Subconfluent cells, without fully developed tight junctions, appear to be more vulnerable than confluent cells with tight junctions indicating the important protective role of these junctions.     

Electrochemical deposition and characterization of polyppyrrole coatings doped with nickel cobalt oxide for environmental applications

Electrochemical depositions of hybrid polypyrrole/nickel cobalt oxide (PPy/NiCoO) coatings onto ferritic stainless steel surface were carried out with different electrochemical techniques from 0.1 M pyrrole (Py) in 0.2-M oxalic acid (OA) solution and less than 150-nanometer-sized NiCoO particles. The structural properties of the composite were investigated by using different methods such as transmission electron microscopy (TEM), scanning electron microscopy (SEM) with energy-dispersive X-ray spectrometer (EDS) and Raman spectroscopy. The embedded NiCoO particles, uniformly distributed onto the surface of the PPy film, have similar oxide ratios corresponding to a mixed oxide structure. The electrochemical characterization was done using polarization curves and linear sweep voltammetry (LSV) related to oxygen reduction reaction (ORR) in alkaline solution and hydrogen peroxide as an oxygen source. Concerning the exchange current densities for ORR, the obtained values (between 1.06 and 1.45?×?10^?3 mA cm^?2 for a total amount of NiCoO of 0.1 mg cm^?2) are comparable with other polymer films with Pt.     

Platinum–polytyramine composite material with improved performances for methanol oxidation

Polytyramine (PTy) is shown to be a possible alternative to other conducting polymers as a support material for fuel cell electrocatalysts such as platinum. In this work, a Pt–PTy composite was prepared via potentiodynamic deposition of polytyramine on graphite substrate, followed by the electrochemical deposition of Pt nanoparticles. The material obtained by this straightforward method exhibited, for platinum loadings as low as ca. 0.12 mg cm⁻², a specific electrochemically active surface area of the electrocatalyst of ca. 54 m² g⁻¹, together with a good electrocatalytic activity for methanol oxidation in acidic media, thus ensuring better efficiency of Pt utilization. The system Pt–PTy appears to be worthy of development for methanol fuel cell applications also because the results suggested that, when deposited as small particles in a PTy matrix, platinum is less sensitive to fouling during CH₃OH oxidation.     

Keggin Polyoxotungstoborate with Uranium(IV)

A new uranium tungstoborate heteropolyanion K₁₂[U(BW₁₁O₃₉H)₂]·23 H₂O has been prepared and investigated by thermal analyses, IR, UV-Vis spectroscopy and magnetic susceptibility measurements. The compound obtained from Keggin monolacunary anions is 1:2 sandwich-type and exhibits a square antiprismatic stereochemistry for uranium (IV) ion.     

Suppression of plasma turbulence during optimized shear configurations in JET

Correlation of density turbulence suppression and reduced plasma transport is observed in the internal transport barrier (ITB) region of JET tokamak discharges with optimized magnetic shear. The suppression occurs in two stages. First, low frequency turbulence and ion transport are reduced across the plasma core by a toroidal velocity shear generated by intense auxiliary heating. Then with the ITB formation, high frequency turbulence and electron transport are reduced locally within the steep pressure gradient region of the ITB.     

Synthesis of a new siloxane-crown ether polyamide

The synthesis of a siloxane-crown ether polyamide by solution polycondensation of 4,4′-diaminodibenzo-18-crown-6 with a carboxypropyl-terminated siloxane oligomer is presented. The polymer is characterized by IR and ¹H NMR spectroscopy as well as by differential thermal analysis and differential scanning calorimetry.     

Assessment of Murine Colon Inflammation Using Intraluminal Fluorescence Lifetime Imaging

Inflammatory bowel disease (IBD) is typically diagnosed by exclusion years after its onset. Current diagnostic methods are indirect, destructive, or target overt disease. Screening strategies that can detect low-grade inflammation in the colon would improve patient prognosis and alleviate associated healthcare costs. Here, we test the feasibility of fluorescence lifetime imaging (FLIm) to detect inflammation from thick tissue in a non-destructive and label-free approach based on tissue autofluorescence. A pulse sampling FLIm instrument with 355 nm excitation was coupled to a rotating side-viewing endoscopic probe for high speed (10 mm/s) intraluminal imaging of the entire mucosal surface (50–80 mm) of freshly excised mice colons. Current results demonstrate that tissue autofluorescence lifetime was sensitive to the colon anatomy and the colonocyte layer. Moreover, mice under DSS-induced colitis and 5-ASA treatments showed changes in lifetime values that were qualitatively related to inflammatory markers consistent with alterations in epithelial bioenergetics (switch between β-oxidation and aerobic glycolysis) and physical structure (colon length). This study demonstrates the ability of intraluminal FLIm to image mucosal lifetime changes in response to inflammatory treatments and supports the development of FLIm as an in vivo imaging technique for monitoring the onset, progression, and treatment of inflammatory diseases.