Structural studies of NaPO3-MoO3 glasses by solid-state nuclear magnetic resonance and raman spectroscopy

Vitreous samples were prepared in the (100 - x)% NaPO3-x% MoO3 (0 <= x <= 70) glass-forming system by a modified melt method that allowed good optical quality samples to be obtained. The structural evolution of the vitreous network was monitored as a function of composition by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), Raman scattering, and solid-state nuclear magnetic resonance (NMR) for P-31, Na-23, and Mo-95 nuclei. Addition of MoO3 to the NaPO3 glass melt leads to a pronounced increase in the glass transition temperatures up to x = 45, suggesting a significant increase in network connectivity. For this same composition range, vibrational spectra suggest that the Mo6+ ions are bonded to some nonbridging oxygen atoms (Mo-O- or Mo=O bonded species). Mo-O-Mo bond formation occurs only at MoO3 contents exceeding x = 45. P-31 magic-angle spinning (MAS) NMR spectra, supported by two-dimensional J-resolved spectroscopy, allow a clear distinction between species having two, one, and zero P-O-P linkages. These sites are denoted as Q(2Mo)((2)), Q(1Mo)((2)), and Q(0Mo)((2)), respectively. For x < 0.45, the populations of these sites can be described along the lines of a binary model, according to which each unit of MoO3 converts two Q(nMo)((2)) sites into two Q((n+1)Mo)((2)) sites (n = 0, 1). This structural model is consistent with the presence of tetrahedral Mo(=O)(2)(O-1/2)(2) environments. Indeed, Mo-95 NMR data suggest that the majority of the molybdenum species are four-coordinated. However, the presence of additional six-coordinate molybdenum in the MAS NMR spectra indicates that the structure of these glasses may be more complicated and may additionally involve sharing of network modifier oxide between the network formers phosphorus and molybdenum. This latter hypothesis is further supported by Na-23{P-31} rotational echo double resonance (REDOR) data, which clearly reveal that the magnetic dipole-dipole interactions between P-31 and Na-23 are increasingly diminished with increasing molybdenum content. The partial transfer of modifier from the phosphate to the molybdate network former implies a partial repolymerization of the phosphate species, resulting in the formation of Q(nMo)((3)) species and accounting for the observed increase in the glass transition temperature with increasing MoO3 content that is observed in the composition range 0 <= x <= 45. Glasses with MoO3 contents beyond x = 45 show decreased thermal and crystallization stability. Their structure is characterized by isolated phosphate species [most likely of the P(OMo)(4) type] and molybdenum oxide clusters with a large extent of Mo-O-Mo connectivity.

Foreign Direct Investment in Latin America and the Caribbean 2007

Includes bibliography

Latin America and the Caribbean in the World Economy 2011-2012: Continuing crisis in the centre and new opportunities for developing economies

Includes bibliography

Finance for development: Latin America in comparative perspective

Includes bibliography

Economic growth with equity: challenges for Latin America

Includes bibliography

Review of Caribbean economic and social performance in the 1980's and 1990's

Includes bibliography

Globalization and development

Includes bibliography

National accounts of Caribbean countries: methodologies, sources and quality, and a comparative Caribbean study

Includes bibliography

Latin America and Asia Pacific trade and investment relations at a time of international financial crisis

Includes Bibliography

E-business innovation and customs renovation for secure supply chain management

Includes bibliography

Peru: integration, sectoral specialization and synchronization with international gross domestic product cycles

Includes bibliography

An assessment of fiscal and regulatory barriers to deployment of energy efficiency and renewable energy technologies in Guyana

Includes bibliography.

The United States subprime mortgage crisis and its implications for the Caribbean

The bursting of the property bubble – subprime mortgage crisis – in 2007 in the United States has engendered panic, recession fears and turmoil in the global financial system. Although the United States economy grew by 0.6 per cent in the last quarter of 2007, down from 4.9 per cent in the previous quarter, day by day worsening scenarios emerge, from escalating oil prices, to a depreciating dollar and financial institutions’ bailout by the Federal Reserve. Many economists and policy makers share the view that a subprime-led recession – i.e. two consecutive quarters with negative growth – is inevitable and will be much deeper and longer than the 2001 dot-com downturn. Moreover, the critical situation of the financial system has driven some analysts to argue that should the monetary policy response fails to restore confidence among investors, the outcome would be the worst crisis seen since the Great Depression. This pessimism is not only among specialists. Indeed, in late March 2008 the Consumer Confidence Index in the United States recorded its lowest level since February 1992. A recession in the United States will undoubtedly have an important impact on the world economy, despite the continuous rapid growth experienced by emerging economies, particularly China and India. The purpose of this article is threefold: first, to characterize the current situation in the United States economy; second, to discuss the economic policy responses; and finally, to elaborate on how Caribbean economies may be affected.

Global financial rulemaking and small economies

This paper addresses some unintended consequences of global financial regulation and international tax evasion prevention and their impact on small economies. It explores how failure to recognize countries’ differing access to finance and varying costs of funding as well as the high costs of complying with financial regulations may overlook some unintended consequences, especially on smaller island countries Then, it discusses the global financial architecture and governance of standard setting bodies and the actions taken to improve representation and legitimacy and remediate some of the unintended deleterious effects on emerging markets and developing economies (EMDEs). Improving governance is ever more urgent at a time when financing the post-2015 agenda will require mobilization of both public and private funds at the national, regional and global levels.

Are sustainable companies less risky and more profitable?

The purpose of this study was to determine whether there were significant differences in accounting indicators when comparing sustainable enterprises to other similar companies that are not considered as sustainable. The Corporate Sustainability Index of BM (São Paulo Stock, Commodities and Futures Exchange) was the criterion selected to break down the samples into sustainable and non-sustainable enterprises. The accounting indicators were separated into two kinds: risk (dividend payout, percentage growth of assets, financial leverage, current liquidity, asset size, variability of earnings, and accounting beta) and return (ROA, ROE, asset turnover, and net margin). We individually analyzed the companies in the energy sector, followed by those in the banking sector, as well as the entire ISE portfolio as of 2008/2009, including all the sectors. Mann-Whitney tests were performed in order to verify the difference of the means between the groups (ISE and non-ISE). The results, considering the method chosen and the time span covered by the study, indicate that there are no differences between sustainable companies and the others, when they are assessed by the accounting indicators used here.