Dinuclear platinum complexes with biological relevance based on the 1,2-diaminocyclohexane carrier ligand

The synthesis of bifunctional dinuclear platinum complexes, [{PtCl(dach)}(2)-mu-Y](n+)Cl(n) (1-3; Y = H(2)N(CH(2))(3)NH(2)(CH(2))(4)NH(2), H(2)N(CH(2))(6)NH(2)(CH(2))(6)NH(2), and H(2)N(CH(2))(6)NH(2)(CH(2))(2)NH(2)(CH(2))(6)NH(2), respectively; Figure 1) is reported. There was no labilization of the polyamine linker groups of the cis-1,2-diaminocyclohexane complexes in the presence of sulfur-containing species at physiological pH, in contrast to previous studies preformed on trans complexes. Metabolism reactions are somewhat dependent on the nature of the polyamine: at physiological pH, the spermidine complex 1 forms an inert (tetraamine)platinum species in which one platinum is chelated by a central and terminal amino group. The stability of cis-geometry complexes may make them viable second-generation polynuclear platinum clinical candidates.     

Analysis of curing of diglycidyl ether of bisphenol A (BADGE n = 0) with 2‐adamantylethanamine

The epoxy resin diglycidyl ether of Bisphenol A (BADGE n = 0) has been cured with a new synthesized hardener (2‐adamantylethanamine) and the crosslinking reaction was characterized by DSC. Values of 413.3 J/g and 95°C have been obtained for the enthalpy of the reaction and the glass transition temperature, respectively. The experimental results obey Kamal's model over all conversion range of temperatures (70°C‐100°C). The activation energies of the mechanisms involved in the curing reaction have been determined for both the autocatalytic and the n‐order mechanism, the values being 63.3 and 29.8 kJ/mol, respectively. The value for T_g is 23°C higher than the one for (BADGE n = 0)/amantadine, while the activation energy for the n‐order mechanism is around 13 kJ/mol lower. This is consistent with a higher steric effect of the adamantyl group in the second hardener since it will hinder the opening the oxirane ring by the nitrogen atom of the amino group. As the polymerization reaction progress, this effect will disappear as the distance adamantyl‐oxirane increase when new oxirane groups react with the hydroxyl groups (autocatalyzed reaction). Consequently, by selecting the appropriate cross‐linking agent, it is possible to simultaneously increase T_g while reducing theactivation energy, two effects which may be desirable for some industrial applications of the material.     

Blow‐up analysis,existence and qualitative properties of solutions for the two‐dimensional Emden–Fowler equation with singular potential

Motivated by the study of a two‐dimensional point vortex model, we analyse the following Emden–Fowler type problem with singular potential: where V(x) = K(x)/|x|^2α with α∈(0, 1), 0<a?K(x)?b< + ∞, ?x∈Ω and ∥?K∥_∞?C. We first extend various results, already known in case α?0, to cover the case α∈(0, 1). In particular, we study the concentration‐compactness problem and the mass quantization properties, obtaining some existence results. Then, by a special choice of K, we include the effect of the angular momentum in the system and obtain the existence of axially symmetric one peak non‐radial blow‐up solutions. Copyright © 2007 John Wiley & Sons, Ltd.     

Analytical method for the determination of mycotoxins in indoor/outdoor airborne particulate matter by HPLC-MS-MS

An effective analytical method for the screening of mycotoxins, in indoor/outdoor airborne particulate matter, was developed and method performance data are presented. Mycotoxins are natural compounds produced, in particular conditions, as secondary metabolites by filamentous fungi and moulds, and, after their production, they can be transported far from their source. To simulate real samples, an urban dust (reference material 1649a) free from mycotoxins was used as matrix and spiked by the most common mycotoxins, chosen on the basis of studies carried out previously in other real matrices: deoxynivalenol, aflatoxin B1, ochratoxin A, T-2 toxin, zearalenone and sterigmatocystin. The analytical method was optimised and structured in four successive steps: (1) accelerated solvent extraction of the (spiked) analytes from matrix, (2) solid-phase purification (SPE) of the previous extract, (3) pre-concentration of the eluates from SPE and (4) analysis of the concentrated eluates by high performance liquid chromatography tandem mass spectrometry in multiple reaction monitoring mode. After a proper sampling campaign, the method was applied to real indoor and outdoor particulate matter samples, where the clean-up step showed to be very effective and fundamental to avoid misleading analytical results.     

Self‐Assembly Mechanism of Nanoparticles of Ni‐Based Prussian Blue Analogues at the Air/Liquid Interface: A Synchrotron X‐ray Reflectivity Study

Prussian Blue analogue (PBA) nanoparticles can be self‐assembled at air/liquid interfaces to build novel materials with interesting magnetic features. Herein, we study the influence of the size of PBA Cs_0.4Ni[Cr(CN)₆]_0.9 and K_0.25Ni[Fe(CN)₆]_0.75 nanoparticles on the self‐assembly behavior by synchrotron X‐ray reflectivity. Both nanoparticles show similar Z‐potential values. The phospholipid dipalmitoylphosphatidylcholine and the amino surfactant dimethyldioctadecylammonium have been used as Langmuir monolayers to anchor the PBA nanoparticles and study the interplay of forces directing the self‐assembly of the nanoparticles at the surfactant/liquid interface. Whereas Cs_0.4Ni[Cr(CN)₆]_0.9 nanoparticles with a diameter of 8 nm form an incomplete layer at the surfactant/water interface, the larger K_0.25Ni[Fe(CN)₆]_0.75 nanoparticles with a diameter of 20 nm generate complete layers that can be stacked to one another. The size of the PBA nanoparticles is the main parameter determining the final arrangement at the air/liquid interface, due to the different extent of interparticle interaction. This study aims at the rationale design of PBA nanoparticles for an effective interfacial self‐assembly, ultimately leading to functional materials.     

A Non-Adiabatic Flamelet Progress�CVariable Approach for LES of Turbulent Premixed Flames

A progress variable/flame surface density/probability density function method has been employed for a Large Eddy Simulation of a CH₄/Air turbulent premixed bluff body flame. In particular, both mean and variance of the progress variable are transported and subgrid spatially filtered gradient contributes to model the flame surface density (that introduces the effect of the subgrid flame reaction zone) and to presume a probability density function (that introduces the effect of subgrid fluctuations on chemistry). Chemistry is preliminarly tabulated in terms of laminar premixed flames and enthalpy is included as a new coordinate in their tabulation to take into account heat losses in the flowfield. Then, the PDF is used to build a turbulent flamelet library. The filtered mass, momentum, enthalpy and scalar equations mentioned above are integrated by an explicit scheme using finite differences, 2nd?Corder accurate in space and third order in time, over a cylindrical non-uniform grid using a staggered mesh. The bluff-body geometry is modelled by using the Immersed Boundary Method. The numerical predictions are compared with the available experimental data.     

Genotoxic evaluation of a methanolic extract of Verbascum thapsus using micronucleus test in mouse bone marrow

Verbascum thapsus L. is a medicinal plant and has been used to treat numerous pulmonary diseases, asthma, inflammatory disease, spasmodic coughs and migraine headaches. Several studies have demonstrated that different extracts of V. thapsus present antimicrobial activity. Thus, the goal of this study was to evaluate the genotoxic and cytotoxic activities of a methanolic extract of Verbascum thapsus, using micronucleus test in mouse bone marrow. No toxicity in bone marrow was detected in the extract-treated groups. The methanolic extract of V. thapsus at doses of 100, 300 and 500 mg/kg, did not produce a significant increase in the frequency of MNPCE in bone marrow and neither altered the relationship PCE/NCE respect to negative control. These cytogenotoxic findings contribute the preclinical knowledge of methanolic extract of V. thapsus and provide security in its use as herbal medicine.     

Multifunctional magnetic materials obtained by insertion of spin-crossover Fe(III) complexes into chiral 3D bimetallic oxalate-based ferromagnets

The syntheses, structures, and magnetic properties of compounds of formula [Fe(III)(5-Clsal(2)-trien)][Mn(II)Cr(III)(ox)(3)]·0.5(CH(3)NO(2)) (1), [Fe(III)(5-Brsal(2)-trien)][Mn(II)Cr(III)(ox)(3)] (2), and [In(III)(5-Clsal(2)-trien)][Mn(II)Cr(III)(ox)(3)] (3) are reported. The structure of the three compounds, which crystallize in the orthorhombic P2(1)2(1)2(1) chiral space group, presents a 3D chiral anionic network formed by Mn(II) and Cr(III) ions linked through oxalate ligands with inserted [Fe(III)(5-Clsal(2)-trien)](+), [Fe(III)(5-Brsal(2)-trien)](+), and [In(III)(5-Clsal(2)-trien)](+) cations. The magnetic properties indicate that the three compounds undergo long-range ferromagnetic ordering at ca. 5 K. On the other hand, the inserted Fe(III) cations undergo a partial spin crossover in the case of 1 and 2.     

Interaction of VO2+ ion and some insulin-enhancing compounds with immunoglobulin G

Complexation of VO(2+) ion with the most abundant class of human immunoglobulins, immunoglobulin G (IgG), was studied using EPR spectroscopy. Differently from the data in the literature which report no interaction of IgG with vanadium, in the binary system VO(2+)/IgG at least three sites with comparable strength were revealed. These sites, named 1, 2, and 3, seem to be not specific, and the most probable candidates for metal ion coordination are histidine-N, aspartate-O or glutamate-O, and serinate-O or threoninate-O. The mean value for the association constant of (VO)(x)IgG, with x = 3-4, is log β = 10.3 ± 1.0. Examination of the ternary systems formed by VO(2+) with IgG and human serum transferrin (hTf) and human serum albumin (HSA) allows one to find that the order of complexing strength is hTf ? HSA ≈ IgG. The behavior of the ternary systems with IgG and one insulin-enhancing agent, like [VO(6-mepic)(2)], cis-[VO(pic)(2)(H(2)O)], [VO(acac)(2)], and [VO(dhp)(2)], where 6-mepic, pic, acac, and dhp indicate the deprotonated forms of 6-methylpicolinic and picolinic acids, acetylacetone, and 1,2-dimethyl-3-hydroxy-4(1H)-pyridinone, is very similar to the corresponding systems with albumin. In particular, at the physiological pH value, VO(6-mepic)(IgG)(OH), cis-VO(pic)(2)(IgG), and cis-VO(dhp)(2)(IgG) are formed. In such species, IgG coordinates nonspecifically VO(2+) through an imidazole-N belonging to a histidine residue exposed on the protein surface. For cis-VO(dhp)(2)(IgG), log β is 25.6 ± 0.6, comparable with that of the analogous species cis-VO(dhp)(2)(HSA) and cis-VO(dhp)(2)(hTf). Finally, with these new values of log β, the predicted percent distribution of an insulin-enhancing VO(2+) agent between the high molecular mass (hTf, HSA, and IgG) and low molecular mass (lactate) components of the blood serum at physiological conditions is calculated.