The kinetics of gold(III) extraction by pyridine-2-azo-p-dimethylaniline in water and in micellar systems

The kinetics of reaction between AuCl4−and the azo-dye pyridine-2-azo-p-dimethylaniline (PADA) havebeen investigated in water and in the presence of DTAC micelles, using classical spectrophotometryand the stopped-flow technique. PADA reacts with different chloro/hydroxo gold(III) complexes, in turnformed as the pH and Cl−concentration were changed, according to a network of parallel paths. In aqueoussolution, at low pH values, a fast step is observed which is ascribed to the ligand induced expulsion ofa labile water molecule from the reacting species Au(H2O)Cl3which forms at low pH values. At highervalues of pH, the reaction is much slower because, in the key step, PADA has to replace the more inertCl−ions in the gold coordination shell. In the presence of DTAC a remarkable catalytic effect is observed,owing to the absorption and attraction of the reactants on the micelle surface. Moreover, DTAC favors theformation of aquochloro aurates, thus inducing a change in the gold(III) speciation compared to that inwater. The analysis of the data suggests that the aquo species Au(H2O)Cl3and Au(H2O)2Cl2+play a majorrole in the reaction mechanism

The mechanism of the reaction between Au(III) and PADA in Sodium dodecylsulphate

The PADA/SDS system provides an excellent tool to selectively extract metal ions using the ligand-modified micellar-enhanced ultrafitration (LM-MEUF) technique. Application of this method to the extraction of Au(III) has required a detailed knowledge of the conditions under which the interaction of the metal ion with the extractor are optimal. For this purpose the kinetics and the equilibria of the reaction between tetrachloro-aurate ion and PADA have been investigated in water/SDS medium, exploring wide ranges of pH values and NaCl concentrations. Addition of PADA to the water/SDS medium results in the full adsorption of the ligand on the micelle and, in the presence of Au(III), the resulting Au-PADA complex is fully retained on the SDS surface. The binding process is, in fact, a ligand displacement reaction where PADA interacts with different Au(III) chloro-aquo complexes, displacing Cl− or OH− or H2O molecules, depending on pH. The reaction is biphasic and its mechanism is discussed. Experiments at different SDS concentrations show that the reaction of complex formation is retarded on going from pure water to a water/SDS mixture with [SDS] just above the cmc, while for further increases of the SDS content the reaction rate tends to stay constant. The obtained results enabled to establish that the reaction occurs on the SDS surface while the aquo-species, Au(H2O)Cl3 and Au(OH)3(H2O), which are not involved in the binding process in pure water, play an important kinetic role in the H2O/SDS medium

Gold(III) extraction and recovery and gold(III)/copper(II) separation using micelles

Gold extraction from aqueous solutions has been performed by micellar enhanced ultrafiltration (MEUF), using SDS and DTAC micelles. DTAC entraps 92-100% of the metal, which is present in form of AuCl4-, owing to electrostatic interaction. Using SDS the extraction of gold is unsuccessful. However, addition of PADA, as a metal extractor agent, according to the ligand modified micellar enhanced ultrafiltration (LM-MEUF) procedure, makes the extraction yield to approach 100% also with SDS. The recovery of gold entrapped in the micellar pseudo-phase has also been investigated. Different stripping agents have been used, the most efficient of them being a mixture of NaCl and NH3 which allowed the metal to be expelled from the micelle with a yield of 85%. Finally, Au(III)/Cu(II) separation is achieved with DTAC or SDS between pH 3 and 5. Almost 100% of Au(III) is retained on DTAC micelles while all Cu(II) remains in the aqueous medium, while the opposite occurs in SDS

Mg(II) and Ni(II) induce aggregation of poly(rA)poly(rU) to either tetra-aggregate or triplex depending on the metal ion concentration

The ability of magnesium(II) and nickel(II) to induce dramatic conformational changes in the synthetic RNA poly(rA)poly(rU) has been investigated. Kinetic experiments, spectrofluorometric titrations, melting experiments and DSC measurements contribute in shedding light on a complex behaviour where the action of metal ions (Na+, Mg2+, Ni2+), in synergism with other operators as the intercalating dye coralyne and temperature, all concur in stabilising a peculiar RNA form. Mg2+ and Ni2+ (M) bind rapidly and almost quantitatively to the duplex (AU) to give a RNA/metal ion complex (AUM). Then, by the union of two AUM units, an unstable tetraaggregate (UAUA(M2)*) is formed which, in the presence of a relatively modest excess of metal, evolves to the UAUM triplex by releasing a single AM strand. On the other hand, under conditions of high metal content, the UAUA(M2)* intermediate rearranges to give a more stable tetra-aggregate (UAUA(M2)). As concerns the role of coralyne (D), it is found that D strongly interacts with UAUA(M2). Also, in the presence of coralyne, the ability of divalent ions to promote the transition of AUD into UAUD is enhanced, according to the efficiency sequence [Ni2+]≫[Mg2+]≫[Na+]

Intercalation of Zn(II) and Cu(II) complexes of the cyclic polyamine Neotrien into DNA: equilibria and kinetics

The equilibria and kinetics of the interaction of the Zn(II) and Cu(II) complexes of the macrocyclic polyamine 2,5,8,11-tetraaza[12]-[12](2,9)[1,10]-phenanthrolinophane (Neotrien) with calf thymus DNA have been investigated at pH = 7.0 and T = 25 degreesC by spectrophotometry, spectrofluorimetry and stopped-flow method. At low dye/polymer ratios both complexes bind to DNA according to the excluded site model. At high dye/polymer ratios the binding displays cooperative features. The logarithm of the binding constant depends linearly on - log[NaCl]. The kinetic results suggest the D + S reversible arrow D, S reversible arrow DS mechanism where the metal complexes (D) react with the DNA sites (S) leading to fast formation of an externally bound form (D, S) which, in turn, is converted into internally bound complex (DS) by intercalation. The binding constants, evaluated as ratios of rate constants, agree with those obtained from equilibrium binding experiments, thus confirming the validity of the proposed model. Fluorescence titrations, where the metal-Neotrien complexes were added to DNA previously saturated with ethidium bromide (EB), show that both complexes displace EB from the DNA cavities. The reverse process, i.e. the addition of excess ethidium to the DNA/metal Neotrien systems, leads to fluorescence recovery for DNA/ZnNeotrien but not for DNA/CuNeotrien. This observation suggests that the binding of CuNeotrien induces deep alterations in the DNA structure. Experiments with Poly(dA-dT) . Poly(dA-dT) and Poly(dG-dC) . Poly(dG-dC) reveal that CuNeotrien mainly affects the structure of the latter polynucleotide. (C) 2004 Elsevier Inc. All rights reserved

OFICINA BINGO DA SAÚDE: UMA EXPERIÊNCIA DE EDUCAÇÃO EM SAÚDE COM GRUPOS DE IDOSOS

RESUMO Este estudo tem como objetivo relatar a experiência de integrantes do Programa de Educação Tutorial do curso de Enfermagem no projeto de extensão "Acampavida", realizado anualmente com idosos, por meio de atividades de educação em saúde. Trata-se de um relato de oficinas lúdico-pedagógicas, planejadas e organizadas pelos acadêmicos do Programa de Educação Tutorial Enfermagem e nominadas como "bingo da saúde", balizadas na metodologia participativa. As cartelas do bingo traziam imagens que expressavam aspectos específicos que tangenciavam questões de saúde no envelhecimento. A realização de cada rodada da oficina propiciou o compartilhamento de informações, vivências e experiências relevantes, não só aos idosos, mas também aos acadêmicos participantes. Tendo em vista que o enfermeiro possui seu papel como educador em saúde, concluiu-se que a execução dessa atividade reforça a importância de sua realização, bem como empodera e motiva futuros profissionais da saúde para a disseminação de atividades similares

New aspects of the interaction of the antibiotic coralyne with RNA: coralyne induces triple helix formation in poly(rA)•poly(rU)

The interaction of coralyne with poly(A)•poly(U), poly(A)•2poly(U), poly(A) and poly(A)•poly(A) is analysed using spectrophotometric, spectrofluorometric, circular dichroism (CD), viscometric, stopped-flow and temperature-jump techniques. It is shown for the first time that coralyne induces disproportionation of poly(A)•poly(U) to triplex poly(A)•2poly(U) and single-stranded poly(A) under suitable values of the [dye]/[polymer] ratio (CD/CP). Kinetic, CD and spectrofluorometric experiments reveal that this process requires that coralyne (D) binds to duplex. The resulting complex (AUD) reacts with free duplex giving triplex (UAUD) and free poly(A); moreover, ligand exchange between duplex and triplex occurs. A reaction mechanism is proposed and the reaction parameters are evaluated. For CD/CP> 0.8 poly(A)•poly(U) does not disproportionate at 25°C and dye intercalation into AU to give AUD is the only observed process. Melting experiments as well show that coralyne induces the duplex disproportionation. Effects of temperature, ionic strength and ethanol content are investigated. One concludes that triplex formation requires coralyne be only partially intercalated into AUD. Under suitable concentration conditions, this feature favours the interaction of free AU with AUD to give the AUDAU intermediate which evolves into triplex UAUD and single-stranded poly(A). Duplex poly(A)•poly(A) undergoes aggregation as well, but only at much higher polymer concentrations compared to poly(A)•poly(U)

Comparison of hormonal receptor and HER-2 status between breast primary tumours and relapsing tumours: clinical implications of progesterone receptor loss

Differences in hormone receptor and HER-2 status between primary tumour and corresponding relapse could have a substantial impact on clinical management of patients. The aim of this study was to evaluate change in expression of hormone receptors and HER-2 status between primary tumour and corresponding local recurrence or distant metastasis. We analysed 140 primary tumours and related recurrent or metastatic samples. Hormone receptors status was evaluated by immunohistochemistry, while HER-2 status by immunohistochemistry and silver in situ hybridisation. A change in HER-2 was rare; 3.7% of cases by immunohistochemistry and only 0.7% by silver in situ hybridisation analysis. A change in estrogen and progesterone receptors was seen in 6.4% and 21.4% of cases, respectively. Estrogen receptor change was not affected by adjuvant therapy, whereas progesterone receptor was influenced by adjuvant chemotherapy associated to hormone therapy (P = 0.0005). A change in progesterone receptor was more frequent in distant metastases than in local recurrences (P = 0.03). In the setting of estrogen receptor positive tumours, patients with progesterone receptor loss in local recurrence had a statistically significant lower median metastasis free survival compared to others patients; progesterone receptor positive, 112 months; progesterone receptor negative, 24 months (P = 0.005). A change between primary tumour and corresponding relapse is frequent for progesterone receptor, infrequent for estrogen receptor and rare for HER-2. In cases with changes in HER-2, it is worthwhile reassessing HER-2 status with both immunohistochemistry and in situ hybridisation analysis. Progesterone receptor loss seems to be influenced by therapy and to correlate with a worse prognosis

The Italian Draft Law on the \u2018Provisions Concerning the Safeguarding of the Intangible Cultural Heritage\u2019

Intangible cultural heritage in Italy is still in need of a unified approach, capable of providing reliable criteria for identifying its assets and for indicating timescales and means by which they should be safeguarded. In the continued absence of up-to-date, ad hoc state legislation (since the content of those laws which do implement international Conventions is too generic in nature to be sufficiently effective), the Regions have proceeded to act in a somewhat scattered manner, giving rise to an extremely fragmented and very disorderly regulatory framework. The draft law N. 4486, "Provisions Concerning the Safeguarding of the Intangible Cultural Heritage", presented on 12th May 2017 at the Chamber of Deputies of the Italian Republic - as the result of the work of an interdisciplinary and inter-university research team coordinated by Marco Giampieretti, who has drafted the final text with the collaboration of Simona Pinton - seeks to fill the serious void that exists in Italian legal system by aligning it to the principles of international and European law, by redirecting the relevant State and Regional legislation, and by satisfying the fundamental requirements of the national community

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements