PEGylation of SPIONs by polycondensation reactions: A new strategy to improve colloidal stability in biological media

In this study, we report on a new route of PEGylation of superparamagnetic iron oxide nanoparticles (SPIONs) by polycondensation reaction with carboxylate groups. Structural and magnetic characterizations were performed by X-ray diffractometry (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM). The XRD confirmed the spinel structure with a crystallite average diameter in the range of 3.5-4.1 nm in good agreement with the average diameter obtained by TEM (4.60-4.97 nm). The TGA data indicate the presence of PEG attached onto the SPIONs' surface. The SPIONs were superparamagnetic at room temperature with saturation magnetization (M S) from 36.7 to 54.1 emu/g. The colloidal stability of citrate- and PEG-coated SPIONs was evaluated by means of dynamic light scattering measurements as a function of pH, ionic strength, and nature of dispersion media (phosphate buffer and cell culture media). Our findings demonstrated that the PEG polymer chain length plays a key role in the coagulation behavior of the Mag-PEG suspensions. The excellent colloidal stability under the extreme conditions we evaluated, such as high ionic strength, pH near the isoelectric point, and cell culture media, revealed that suspensions comprising PEG-coated SPION, with PEG of molecular weight 600 and above, present steric stabilization attributed to the polymer chains attached onto the surface of SPIONs. © 2013 Springer Science+Business Media Dordrecht.

Resolution 624(XXXI): Support for the United Nations Stabilization Mission in Haiti

Includes bibliography

The fiscal impact of trade liberalization and commodity price fluctuation: the case of Dominican Republic, 1980-1998

Includes bibliography

The economic crisis: policies for adjustment, stabilization and growth

Includes bibliography

Business strategies under stabilization and trade openness in the 1990s

Includes bibliography

Síntese, caracterização e propriedades da matriz sílica-carbono impregnada com níquel obtida pelo método dos precursores poliméricos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The employment situation in Latin America and the Caribbean: Crisis, stabilization and reactivation: performance of the labour market in 2009

Following a five-year period during which economic and social performance in Latin America and the Caribbean surpassed anything seen in recent decades, the global economic and financial crisis not only hurt macroeconomic variables but also impacted heavily on labour markets in the region’s countries. Between 2003 and 2008 employment rates had risen considerably, especially in the formal sector, but the crisis spelled a reversal of this trend. Nevertheless, the region was better prepared than it had been in previous crises, since it had achieved a sound fiscal footing, a good level of international reserves and low rates of inflation. This meant that the authorities had the space to implement countercyclical policies on both fiscal and monetary levels. Be this as it may, faced with the worst global crisis since the Great Depression of the 1930s, these measures could only attenuate the impact on the region’s economies —they could not prevent it altogether. Furthermore, the crisis struck with notable differences among subregions and countries depending on the nature of their trade integration, and not all the countries had the fiscal space to implement vigorous countercyclical policies. As discussed in this third ECLAC/ILO bulletin, the crisis did less damage to the region’s labour markets than had been feared at the beginning of last year, thanks to the implementation of public policies geared towards employment, as reviewed in the two previous bulletins. This bulletin offers an additional analysis from the perspective of gender equality. Moreover, some countries in the region, notably Brazil, managed to rapidly stabilize and revive economic growth, with positive effects on labour variables. The fact remains, however, that millions in Latin America and the Caribbean lost their jobs or were obliged to accept more poorly paid employment in more precarious conditions. The macroeconomic data indicate that recovery is under way and is stronger and occurring more rapidly than foreseen one year ago. In fact, regional growth in 2010 may well exceed the 4.1% forecast at the end of 2009. Consequently, although the unemployment rate may be expected to record a modest drop, it may not return to pre-crisis levels. The upturn is taking many different forms in the countries of the region. In some, especially in South America, recovery has benefited from the buoyancy of the Asian economies, whose demand for natural resources has driven large increases in exports, in terms of both volume and price. Countries whose economies are closely tied to the United States economy are benefiting from the recovery there, albeit more slowly and with a certain lag. Conversely, some countries are still suffering from major disequilibria, which are hampering their economic reactivation. Lastly, Chile and Haiti were both victims of devastating earthquakes early in the year and are therefore facing additional challenges associated with reconstruction, on top of their efforts to sustain an economic upturn. Despite the relatively favourable outlook for regional growth in 2010, great uncertainty still surrounds the global economy’s recovery, which affects the region’s economic prospects over the longer term. The weakness of the recovery in some regions and the doubts about its sustainability in others, as well as shocks that have occurred in international financial markets, are warning signs which authorities need to monitor continuously because of the region’s close integration with the global economy. In addition, a return to growth does not directly or automatically mean higher employment rates —still less decent working conditions. Although some labour indicators have performed reasonably favourably since the end of last year, the countries still face daunting challenges in improving the labour market integration of millions in Latin America and the Caribbean who are not seeing the fruits of renewed growth. This is why it is important to learn the lessons arising from the policies implemented during the crisis to offset its impact on labour markets. With this third joint bulletin, ECLAC and ILO continue to pursue their objective of affording the region the information and analyses needed to face these challenges, as regards both trends in the region’s labour markets and the corresponding policy options.

Is price dispersion always an indication of price discrimination?

It has been established for a long time that there is significant dispersion in prices charged for seemingly homogeneous goods. This may happen in competitive markets because the world is not frictionless, and certainly in other markets where price discrimination is carried out by firms with oligopolistic power. This paper is the first survey of the economic literature on price dispersion that addresses the following three key issues: i) its characteristics as a result of optimizing search behavior; ii) its relevance as a reflection of price discrimination and its consequences for social welfare and policy intervention; and iii) the empirical evidence of price dispersion. By contributing to a better understanding of price dispersion, this survey may help in the design and implementation of competition and anti-trust policies

Controle postural de idosos: efeito da perturbação visual com o uso do sistema âncora

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Molecular phylogenies, chromosomes and dispersion in Brazilian akodontines (Rodentia, Sigmodontinae)

Uma nova filogenia molecular para roedores akodontinos do Brasil é proposta. A árvore filogenética foi enriquecida com a área de ocorrência e com informações sobre o cariótipo das amostras. Baseado nisto, e com a metodologia descrita, foram propostas hipóteses sobre as características do cariótipo e sobre a área de ocorrência dos ancestrais de cada clado. Assim, foi possível discutir hipóteses sobre evolução cromossômica do grupo, e sobre eventos de dispersão a partir da área de diferenciação original dos akodontinos nos Andes. A evolução cromossômica começou com números diplóides altos (2n=52) e mostrou uma tendência a redução (até 2n=14 em clados mais recentes). Ramos independentes da árvore mostraram redução do 2n e num caso aumentou o numero diplóide. Foram propostos pelo menos quatro eventos de dispersão dos Andes até o Brasil Sul-Oriental. Os resultados indicam a direção de novos estudos em cariologia comparada.

Significant genetic differentiation among populations of Anomalocardia brasiliana (Gmelin, 1791): a bivalve with planktonic larval dispersion

Four Brazilian populations of Anomalocardia brasiliana were tested for mutual genetic homogeneity, using data from 123 sequences of the mtDNA cytochrome oxidase c subunit I gene. A total of 36 haplotypes were identified, those shared being H3 (Canela Island, Prainha and Acupe) and both H5 and H9 (Prainha and Acupe). Haplotype diversity values were high, except for the Camurupim population, whereas nucleotide values were low in all the populations, except for that of Acupe. Only the Prainha population showed a deviation from neutrality and the SSD test did not reject the demographic expansion hypothesis. Fst values showed that the Prainha and Acupe populations represent a single stock, whereas in both the Canela Island and Camurupim stocks, population structures are different and independent. The observed structure at Canela Island may be due to the geographic distance between this population and the remainder. The Camurupim population does not share any haplotype with the remaining populations in northeastern Brazil. The apparent isolation could be due to the rocky barrier located facing the mouth of the Mamanguape River. The results highlight the importance of wide-scale studies to identify and conserve local genetic diversity, especially where migration is restricted.

Partículas magnéticas: ferrita de ítrio 'Y IND. 3''FE IND. 5''O IND. 12' (YIG) recoberta com sílica ('SIO IND. 2')

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)