Lanthanum chromites partially substituted by calcium,strontium and barium synthesized by urea combustion

Because of their electrical, magnetic and catalytic properties rare earth and transition metal mixed oxides are important compounds. Lanthanum chromites have been extensively used as solid oxide fuel cell (SOFC) interconnect materials. In this work, lanthanum chromites partially substituted by alkaline earth metals were synthesized by the urea combustion process. TG and DSC techniques were used to evaluate the presence of the organic material in the powder after reaction on the hot plate. The powders were calcinated at 900°C and characterized by XRD and SEM. The results show that the particles have nanometric dimensions and the perovskite structure was formed.     

The dimeric and tetrameric octarepeat fragments of prion protein behave differently to its monomeric unit

Potentiometric and spectroscopic data have shown that octarepeat dimer and tetramer are much more effective ligands for Cu(II) ions than simple octapeptide. Thus, the whole N-terminal segment of prion protein due to cooperative effects, could be more effective in binding of Cu(II) than simple peptides containing a His residue. The gain of the Cu(II) binding by longer octarepeat peptides derives from the involvement of up to four imidazoles in the coordination of the first Cu(II) ion. This type of binding increases the order of the peptide structure, which allows successive metal ions for easier coordination.     

Spectroscopic and structural characterization of pure and FeCl<Subscript>3</Subscript>-containing tri-<Emphasis Type="Italic">n</Emphasis>-butyl phosphate

The spectroscopic properties and liquid structure of pure tri-n-butyl phosphate (TBP) and FeCl₃/TBP solutions have been investigated by Uv–Vis and Raman spectroscopies, X-ray diffraction and conductometry. Uv–Vis and Raman spectra, supported by conductometric measurements, consistently indicate that the solubilized salt is present mostly as TBP _n [FeCl_3???n ] ⁿ⁺ and FeCl₄ ^? complex ions due to specific interaction with the TBP phosphate group. Thanks to this interaction, a high amount of salt (up to 13 % w/w) can be dissolved despite the relatively low dielectric constant of TBP. The X-ray diffractogram of pure TBP has been interpreted in terms of three main contributions which can be attributed to spatial pair correlations between atoms of interacting TBP molecules. In the presence of increasing FeCl₃ amounts, it has been observed a progressive structuring effect, exerted by the dissolved salt, on the layers of opportunely oriented TBP molecules due to the formation of the complex ionic species. By simple treatment with NaBH₄, the synthesis of Fe nanoparticles has been achieved. The absence of water, the easiness of preparation, the high amount of salt which can be suspended and the peculiar physico-chemical properties of such systems are all elements worth of note for the fields of nanoparticle synthesis and for specialized technological applications.     

The Identification of a Novel Highly Condensed Pentacyclic Heteroaromatic Ring System 1,3,5,5b,6,8,10,10b‐Octaazacyclopenta[h,i]Aceanthrylene and its Application in the Synthesis of 5,7‐Substituted Pyrazolo[4,3‐d]Pyrimidines

Pyrazolo[4,3‐d]pyrimidines are of interest as potential kinase inhibitors. This article describes the formation of a novel highly conjugated, condensed, centrosymmetric heteroaromatic compound, 4,9‐dichloro‐2,7‐diisopropyl‐1,3,5,5b,6,8,10,10b‐octaazacyclopenta[h,i]aceanthrylene ( 3 ), during the chlorination of 5,7‐dihydroxypyrazolo[4,3‐d]pyrimidine ( 1 ) with phenylphosphonic dichloride. The nucleophilic attack of benzylamine on 3 afforded N‐benzyl‐5‐chloro‐3‐isopropyl‐1H‐pyrazolo[4,3‐d]pyrimidin‐7‐amine ( 6 ), which was further substituted to yield a pyrazolo[4,3‐d]pyrimidine analogue of roscovitine, a well‐known cyclin‐dependent kinase inhibitor.     

Sensitive Determination of 17β-Estradiol using a Magneto Sensor Based on Magnetic Molecularly Imprinted Polymer

The analysis of 17β-estradiol with high sensitivity and selectivity is extremely relevant to control the impacts that this compound can cause on health and the environment. Thus, we describe the development and application of a magneto carbon paste electrode based on magnetic molecularly imprinted polymer (MCPE-MMIP) for determination of 17β-estradiol. The analyte adsorbed on the MMIP was immobilized on the electrode surface by magnetic capture. The morphological and structural characterization of the obtained MMIP suggests that the material was effectively synthesized. MCPE-MMIP showed an improvement in the sensitivity for 17β-estradiol detection when compared to electrode configurations in the absence of this material. The optimum conditions (0.10 mol L⁻¹ phosphate buffer pH 7.0) were reached by differential pulse adsorptive stripping voltammetry (DPAdSV), in which the method presented linearity ranged from 0.06 to 175 μmol L⁻¹ with limits of detection and quantification of 0.02 and 0.06 μmol L⁻¹, respectively. The proposed sensor was applied effectively in the analysis of 17β-estradiol in river water and raw milk samples, exhibiting excellent recovery values (between 96.20 and 104 %), which were confirmed by HPLC analysis.     

Reactions of a Four-Membered Borete with Carbon,Silicon, and Gallium Donor Ligands: Fused and Spiro-Type Boracycles

Donor-acceptor cyclopropanes or cyclobutanes are dipolar reagents, which are widely used in the synthesis of complex organic (hetero)cycles in ring expansion reactions. Applying this concept to boron containing heterocycles, the four-membered borete cyclo-iPr₂N-BC₁₀H₆ reacted with the carbon donor ligands 2,6-xylylisonitrile and the carbene IMes :C(NMesCH)₂ with ring expansion and ring fusion, respectively. In particular, the tetracyclic structure formed with IMes displays zwitterionic character and absorption in the visible region. In contrast to the carbene IMes, the heavier carbenoids :Si(NDippCH)₂ and :Ga(AmIm) with a two-coordinate donor atom afford spiro-type bicyclic compounds, which display four-coordinate geometry at silicon or gallium. (TD-)DFT calculations provide deeper insight into the mechanism of formation and the absorption properties of these new compounds.     

Chiral Fibers Formation Upon Assembly of Tetraphenylalanine Peptide Conjugated to a PNA Dimer

Self-assembly of biomolecules such as peptides, nucleic acids or their analogues affords supramolecular objects, exhibiting structures and physical properties dependent on the amino-acid or nucleobase composition. Conjugation of the peptide diphenylalanine (FF) to peptide nucleic acids triggers formation of self-assembled structures, mainly stabilized by interactions between FF. In this work we report formation of homogeneous chiral fibers upon self-assembly of the hybrid composed of the tetraphenylalanine peptide (4F) conjugated to the PNA dimer adenine-thymine (at). In this case nucleobases seem to play a key role in determining the morphology and chirality of the fibers. When the PNA “at” is replaced by guanine-cytosine dimer “gc”, disordered structures are observed. Spectroscopic characterization of the self-assembled hybrids, along with AFM and SEM studies is reported. Finally, a structural model consistent with the experimental evidence has also been obtained, showing how the building blocks of 4Fat arrange to give helical fibers.     

Normal human dermal fibroblasts: proteomic analysis of cell layer and culture medium.

Proteins present within the cell layer and those released in the cell medium from in vitro cultured normal human dermal fibroblasts were separated and characterized in terms of their isoelectric point and molecular weight, by two-dimensional (2-D) gel electrophoresis. All spots in the synthetic gel were firstly analyzed by the Melanie 3 software and compared with those of breast cancer cells, colorectal epithelial cells, HL60, lymphoma cells, and platelets, already available on-line. From the identification of 144 spots from both the cell layer and the medium, we were able to recognize 89 different proteins, since a certain number of spots represented different isoforms of the same molecule. Identifications were performed by matching with on-line 2-D databases, and by matrix assisted laser-desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS), in order to confirm the identification by matching, or to identify new proteins. The procedure we used allows (i) to design a highly reproducible reference map of the proteome of adult human normal fibroblasts in culture, (ii) to evaluate protein species produced in the cell layer as well as those released in the culture medium, and (iii) to compare data from gel matching with those obtained by MS. This work represents an essential step for a better knowledge of mesenchymal cells, given the widespread use of this cell type in both clinical and experimental investigations.     

Shape-persistent linear, kinked, and cyclic oligo(phenylene-ethynylene-butadiynylene)s: self-assembled monolayers

Shape-persistent rigid phenylene-ethynylene-butadiynylenes form lamellar self-assembled monolayers (SAMs) at the HOPG/TCB interface, which were studied by scanning tunneling microscopy (STM) with submolecular resolution. Substitution of the terminating acetylene functions with polar cyanopropyldimethylsilyl groups leads to 2D phase separation and defined rod-rod interactions, which determine the packing distances between the rigid rods. The results stimulated the connection of rigid rods via septiarylene clamp units. They covalently link two rigid rod units and define the intramolecular rod-rod distance that matches the alkoxy substituent chain lengths. The systems can be described as half-ring structures of two rigid rods connected via a rotatable joint unit. These acetylene-terminated half-ring structures were also oligomerized under Cu and Pd catalysis to yield defined acyclic and cyclic oligomers. Detailed STM studies decoded the molecular origin of the surface patterning of such systems. The dodecyloxy side chains are adsorbed along the HOPG main axes and, together with the alkoxy backbone angle, determine the adsorption direction of the adlayers.     

Mediterranean diet in a Sicilian student population. Second part: breakfast and its nutritional profile

Abstract

Breakfast habits affect the nutritional status and health of people, in particular children and adolescents. This is the second part a previous study about the adherence to the Mediterranean diet in a Sicilian (Italy) student population. The investigation analysed both normal weight and overweight subjects in order to understand how eating habits, number of meals and daily calorie intakes could affect their body mass indexes (BMI). The aim of this second part was to analyse the breakfast nutritional profiles of this student population. The results highlighted that breakfast was regularly consumed by a percentage ranging from a maximum of 84% (in normal subjects) to a minimum value of 57.4% (in overweight/obese students). Milk, yoghurt, sugar, bread/rusk and tea contributed as main foods to the breakfast composition. The results highlighted that subjects who consumed breakfast showed lower BMI values with significant differences between normal and overweight/obese students.