Evaluation of indoor BTX in an outskirt zone of Rome (Italy)

Correlation between indoor and outdoor levels of BTX (benzene, toluene and the sum of ethyl benzene, o-xylene, m-xylene and p-xylene) has been investigated at thirteen homes, thirteen classrooms and related outdoor atmospheres. Non smoking people and low polluted sites were chosen for this campaign, in order to highlight if commonly used domestic materials could act as internal sources. Data, obtained by employing long-term diffusive samplers over a three-month period, are compared with a parallel experiment showing the day-night indoor/outdoor trend. The obtained results let us conclude that there is evidence of internal sources at homes whilst in the schools depletion phenomena prevail, probably due to the walls adsorption.     

A test case for time-dependent density functional theory calculations of electronic circular dichroism: 2-chloro-4-methoxy-6- [(R)-1-phenylethylamino]-1,3,5- triazine

The three-dimensional structure of an optically active substituted s-triazine derivative, 2-chloro-4-methoxy-6-[(R)-1-phenylethylamino]-1,3,5-triazine, has been studied by conformational analysis using density functional theory (DFT) both in vacuo and in acetonitrile solution in the polarizable continuum model integral equation formalism framework. Time-dependent DFT methods have been used to investigate the molecular electronic CD and absorption UV spectra. Comparison with experimental results allowed the reliability of the theoretical predictions to be enhanced and suggested a possible interpretation of the measured data. Electronic Supplementary Material The online version of this article doi:contains supplementary material, which is available to authorized users.     

Recombinant clotting factor VIII concentrates: Heterogeneity and high‐purity evaluation

Factor VIII is an important glycoprotein involved in hemostasis. Insertion of expression vectors containing either the full‐length cDNA sequence of human factor VIII (FLrFVIII) or B‐domain deleted (BDDrFVIII) into mammalian cell lines results in the production of recombinant factor VIII (rFVIII) for therapeutic usage. Three commercially available rFVIII concentrates (Advate^®, Helixate NexGen^® and Refacto^®), either FLrFVIII or BDDrFVIII, were investigated by 1‐ and 2‐DE and MS. The objective of this study was to compare the heterogeneity and the high purity of both rFVIII preparations before and after thrombin digestion. In particular, the 2‐D gel was optimized to better highlight the presence of contaminants and many unexpected proteins. Recombinant strategies consisting of insertion of expression vectors containing BDDrFVIII and FLrFVIII resulted in homogeneous and heterogeneous protein products, respectively, the latter consisting in a heterogeneous mixture of various B‐domain‐truncated forms of the molecule. Thrombin digestion of all the three rFVIII gave similar final products, plus one unexpected fragment of A2 domain missing 11 amino acids. Regarding the contaminants, Helixate NexGen^® showed the presence of impurities, such as Hsp70 kDa, haptoglobin and proapolipoprotein; Refacto^® showed glutathione S‐transferase and β‐lactamase, whereas Advate^® apparently did not contain any contaminants. The proteomic approach will contribute to improving the quality assurance and manufacturing processes of rFVIII concentrates. In this view, the 2‐DE is mandatory for revealing the presence of contaminants.     

Rigid-plastic structures subject to dynamic loads

Summary The one-degree-of-freedom response of rigid-plastic structures is investigated for a variety of single-parameter dynamic loading-functions. Specific results, valid for any structure under the set assumptions, are obtained for single-pulse and periodic loading. The possibility of linear strain-hardening or reduction of strength with deformation is introduced. In the concluding section, the results are reviewed, and possible future researches are indicated.

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Sommario Si sviluppa uno studio teorico del comportamento di strutture rigido-plastiche sottoposte a vari tipi di carichi dinamici; sia la deformazione che il carico si suppongono dipendenti da un singolo parametro, funzione del tempo. Si approfondisce lo studio dei carichi impulsivi e periodici, per cui si forniscono risultati più dettagliati (p. es. riguardo alla più pericolosa forma dell'impulso, ed allastabilizzazione delle oscillazioni sotto carichi periodici), validi per qualsiasi struttura che rispetti le ipotesi. Si introduce quindi la possibilità di variazione (in aumento o in diminuzione) della resistenza con la deformazione, e si studia in particolare la possibilità di completocollasso. Infine, nel paragrafo conclusivo si riassumono e discutono i risultati ottenuti, e si indicano alcuni possibili sviluppi di questa ricerca.

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(on leave at the Division of Engineering, Brown University, Providence, R. I., 1968/69).     

Conformational landscape of (R,R)-pterocarpans with biological activity in vacuo and in aqueous solution (PCM and/or water clusters)

All possible combinations of stable dihedral values have been considered in vacuo at the B3LYP/6-31G level for 3,9-dihydroxy-4,8-diprenylpterocarpan (erybraedin C), whose hydroxy out-out conformation had been examined earlier together with the conformational preferences of 3,9-dimethoxy-4-prenylpterocarpan (bitucarpin A) at the same level (Phys. Chem. Chem. Phys. 2004, 6, 2849). The structure with O5 trans with respect to H6a (O(t)) is about 2 kcal/mol less stable in vacuo than that with one of the H6 trans to it (H(t)); in aqueous solution its energy gap is nearly conserved. The in-in arrangement of the hydroxyl groups of erybraedin turns out to be preferred in vacuo (even considering zero point and thermal effects), where pseudo H-bonds are formed between hydroxy hydrogens and pi electron distributions of prenyl groups. The continuum solvent effect (water) at the IEF-PCM/B3LYP/6-31G level on the relative stability of the various rotamers is very limited both on bitucarpin and erybraedin. Considering the dihydrated derivatives, significant differences in the solvation energy are found between the distinct hydration sites, increasing in the order: methoxy O, ring O, hydroxy O, and hydroxy H. In hydroxy-water interactions, in fact, water prefers to behave as an H-bond acceptor unless nearby bulky groups prevent its approach. Interestingly enough, a bridging water molecule between the hydroxy H of erybraedin and the prenyl group can be found. The inclusion of BSSE corrections in hydroxy-water interactions decidedly favors out-out hydrated arrangements, followed by out-in and in-out ones. Bulk solvent effects with IEF-PCM about the dihydrated systems almost invert the stability order found in vacuo. When a four-water cluster is considered using QM methods, waters gather in H-bonded pairs around the solute OH groups. MD simulations, carried out on a pterocarpan solute (J. Phys. Chem. B 2005, 109, 16918), supply water adducts consistent with a liquid state that have also been embedded in the continuum solvent.     

Determination of metals, metalloids and non-volatile ions in airborne particulate matter by a new two-step sequential leaching procedure Part A: Experimental design and optimisation

The optimisation of a micro-analytical two-step sequential leaching procedure for the determination of non-volatile ions (NO₃⁻, SO₄²⁻, Cl⁻, Na⁺, Mg²⁺, NH₄⁺ and Ca²⁺) and of 17 elements (Al, As, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, S, Se, V, Zn, Sb, Si and Ti) in two fractions—extract and residue—on the same sample of air particulate matter is described. The two-step method was tested on the SRM NIST 1648 for equivalence with two reference methods, the EMEP procedure for ions extraction and the EN 12341 standard for the elemental determination of the PM₁₀ and is suitable for application to small sample amounts (less than 1 mg of particulate matter is needed), i.e. those collected by daily low volume filter-sampling. Performance times of the procedure were optimised to meet the target of routine application for large scale monitoring samples. A single ultrasonic-assisted extraction of air particulate matter is performed in 0.01 M acetate buffer at pH 4.5, followed by IC ions analysis and ICP-OES elemental analysis of the extract and by ICP-OES elemental analysis of the mineralized residue after dissolution by microwave-assisted digestion with a HNO₃/H₂O₂ mixture. Using a pH buffered extracting solvent was preferred to water or diluted acid solutions to improve the reproducibility of metals extraction with respect to existing leaching methods; the influence of pH, nature and concentration of the buffer solution and extraction time on analytes concentration in the extract is discussed. Values of ions extraction and elements recoveries resulted fairly equivalent with those obtained by the reference methods. The study was also extended to some non-certified elements (Mg, S, Sb, Si and Ti) for their environmental significance. Elements recoveries were obtained as sum of the extract and residue fractions and were comparable with those obtained by direct dissolution. Standard deviations were within 10% for almost all detected ions and elements.     

Homoleptic complexes of cobalt(0) and nickel(0,I) with 1,1'-bis(diphenylphosphino)ferrocene (dppf): synthesis and characterization

Reduction of Co(dppf)Cl2 with 2 equiv of sodium naphthalenide in THF, in the presence of dppf, affords the homoleptic complex Co(dppf)2, 1, isolated in 65% yield as a brick red solid, extremely air sensitive. In solution, under inert atmosphere, 1 slowly decomposes into Co and dppf, following a first-order kinetic law (t1/2 = 21 h at 22 degrees C). Similarly to the Rh and Ir congeners, 1 undergoes a one-electron reversible reduction to [Co(dppf)2]-. Attempts to obtain this d10 species by chemical as well as electrochemical reduction of 1 lead to the hydride HCo(dppf)2, 2, as the only product that can be isolated. Reduction of Ni(dppf)Cl2 with sodium in the presence of dppf and catalytic amounts of naphthalene affords Ni(dppf)2, 3, isolated in 60% yield as a yellow air stable solid. The stoichiometric oxidation of 3 with [FeCp2]PF6 forms the d9 complex [Ni(dppf)2]PF6, 4, which represents the second example of a structurally characterized Ni(I) complex stabilized by phosphines. A single-crystal X-ray analysis shows for the metal a distorted tetrahedral environment with a dihedral angle defined by the planes containing the atoms P(1), Ni, P(2) and P(3), Ni, P(4) of 78.2 degrees and remarkably long Ni-P bond distances (2.342(3)-2.394(3) A). The EPR spectroscopic properties of 1 (at 106 K in THF) and 4 (at 7 K in 2-methyl-THF) have been examined and g tensor values measured (1, gx = 2.008, gy = 2.182, gz = 2.326; 4, gx = 2.098, gy = 2.113, gz = 2.332). A linear dependence between the hyperfine constants and the Ni-P bond distances has been evidenced. Finally, the change with time of the EPR spectrum of 4 indicates that it very slowly releases dppf.     

Olefin oligomerization,homopolymerization and copolymerization by late transition metals supported by (imino)pyridine ligands

In this review, the key advances achieved over more than 10 years on the design and development of (imino)pyridyl transition metal complexes as catalyst precursors for the transformation of ethylene, higher α-olefins and cyclic olefins into either linear/branched homopolymers or oligomers are highlighted. Particular attention has been paid to the relationships between the catalytic activity exhibited by the catalysts and their electronic and geometrical structure.     

Synthesis and molecular modelling studies of resorcin[4]arene-capped porphyrins

Three new resorcin[4]arene-capped porphyrins (3, 5 and 7) different in the porphyrin skeleton, in the linking arms and in the cavity dimensions, have been synthesised. Molecular modelling calculations explored the conformations and the cavity size of the three compounds and showed that their hydrophobic pockets can accommodate one molecule of water or methane (3 and 5), or benzene (7) without any distortion. Notably, the capped porphyrin 5 was able to inhibit the oxidation of Co(II) to Co(III), whereas compound 7 did it only partially.