Hydrogen-bonding synthons in lamotrigine salts: 3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazin-2-ium 2-[(2-carboxyphenyl)disulfanyl]benzoate in its monohydrate and anhydrous forms

Lamotrigine is a drug used in the treatment of epilepsy and related convulsive diseases. The drug in its free form is rather inadequate for pharmacological use due to poor absorption by the patient, which limits its bioavailability. On the other hand, the lamotrigine mol­ecule is an excellent hydrogen-bonding agent and this has been exploited intensively in the search for better formulations. The formulation presently commercialized (under the brand name Lamictal) is rather complex and includes a number of anions in addition to the active pharmaceutical ingredient (API). The title salts of lamotrigine, namely 3,5-di­amino-6-(2,3-di­chloro­phen­yl)-1,2,4-triazin-2-ium 2-[(2-carb­oxy­phen­yl)di­sul­fan­yl]benzoate monohydrate, C9H8Cl2N5+·C14H9O4S2-·H2O, (I), and the anhydrate, C9H8Cl2N5+·C14H9O4S2-, (II), contain a lamotriginium cation (L), a hydrogen di­thio­dibenzoate monoanion (D) and, in the case of (I), a disordered solvent water mol­ecule. Both L and D present their usual configurations severely twisted around their central C-C and S-S bonds, respectively. The supra­molecular structure generated by the many available donor and acceptor sites is characterized by a planar anti­symmetric motif of the form D-L-L-D, i.e. the structural building block. Although this characteristic motif is extremely similar in both structures, its conformation involves different donors and acceptors in its R22(8) central L-L homosynthon. The lateral R22(8) D-L hetero­synthons are, on the other hand, identical. These substructures are further connected by strong hydrogen bonds into broad two-dimensional structures, in turn weakly linked to each other. Even if the homo- and heterosynthons in (I) and (II) are rather frequent in lamotrigine structural chemistry, the composite tetra­meric synthon appears to be much less common. The occurrence of these motifs among lamotrigine salts and cocrystals is analyzed.Fil: Freire Espeleta, Eleonora. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Polla, Griselda Ines. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Baggio, Ricardo Fortunato. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentin

What happened to efficiency in electricity industries after reforms?

The last two decades have witnessed widespread power market reforms in both developed and developing countries that have cost billions of dollars. Among the key aims (and assumptions) of these reforms, there has always been realization of improvements in power sector efficiency. This paper questions the validity of this hypothesis. Using panel data from 92 countries covering the period 1982–2008, empirical models are developed and analyzed. The research findings suggest that the impact of the reforms on electricity industry performance is statistically significant but also limited. The results imply that, after controlling for country-specific variables, application of liberal market models in electricity industries slightly increases efficiency in power sector. Besides, we detect a positive relationship between reform process and the percentage share of network (transmission and distribution) losses in total electricity supplied; meaning that as countries take more reform steps the network losses as a fraction of power generated tend to increase. Moreover, the study puts forward that income level and other country specific features are more important determinants of industry efficiency than the reform process. Overall, contrary to expectations of substantial increases in sector efficiency, the paper concludes that introducing a decentralized market model with competition in the electricity sector has a limited increasing effect on power industry performance.Models with panel data (C33); model construction and estimation (C51); electric utilities (L94); power market reform; electricity industry efficiency

Benthic macrofauna and sediment reworking quantification in contrasted environments in the Thau Lagoon

As part of the Microbent-PNEC Program: ‘‘Biogeochemical processes at the wateresediment interface in eutrophicated environment’’, the aim of this work was to specifically investigate and quantify the relationships between macrobenthos and sediment reworking in the Thau Lagoon in order to provide information on the potential contaminant distribution and movements at the wateresediment interface. In order to achieve this, three cores were sampled at two stations (in the central part of the Thau Lagoon and near the shellfish farming zone) in the Thau Lagoon, in December 2001, April 2002, August 2002, January 2003 and May 2003. On the basis of quantification of macrobenthos and sediment reworking, evidence is provided of: (1) similar sediment mixing intensities for different species composition at the two stations; (2) the major role of functional bioturbation groups (e.g., biodiffusors and gallery-diffusors) modulated by seasonal variability on sediment mixing; (3) an increase of intensity in summer suggesting potentially different patterns of redistribution, bioaccumulation and chemical fate (e.g., speciation) of deposited contaminants

A general multivariate threshold GARCH model with dynamic conditional correlations

We propose a new multivariate GARCH model with Dynamic Conditional Correlations that extends previous models by admitting multivariate thresholds in conditional volatilities and correlations. The model estimation is feasible in large dimensions and the positive deniteness of the conditional covariance matrix is easily ensured by the structure of the model. Thresholds in conditional volatilities and correlations are estimated from the data, together with all other model parameters. We study the performance of our model in three distinct applications to US stock and bond market data. Even if the conditional volatility functions of stock returns exhibit pronounced GARCH and threshold features, their conditional correlation dynamics depends on a very simple threshold structure with no local GARCH features. We obtain a similar result for the conditional correlations between government and corporate bond returns. On the contrary, we ¯nd both threshold and GARCH structures in the conditional correlations between stock and government bond returns. In all applications, our model improves signi¯cantly the in-sample and out-of-sample forecasting power for future conditional correlations with respect to other relevant multivariate GARCH models.Multivariate GARCH models, Dynamic conditional correlations, Tree-structured GARCH models

A Range-Based Multivariate Model for Exchange Rate Volatility

In this paper we present a parsimonious multivariate model forexchange rate volatilities based on logarithmic high-low ranges ofdaily exchange rates. The multivariate stochastic volatility modeldivides the log range of each exchange rate into two independentlatent factors, which are interpreted as the underlying currencyspecific components. Due to the normality of logarithmic volatilitiesthe model can be estimated conveniently with standard Kalman filtertechniques. Our results show that our model fits the exchange ratedata quite well. Exchange rate news seems to be very currency-specificand allows us to identify which currency contributes most to bothexchange rate levels and exchange rate volatilities.exchange rates;multivariate stochastic volatility models;range-based volatility

Intensity of technology use and per capita real GDP across some African countries

African countries may have fared poorly compared to some countries in other regions, but relative to their own performance history some African countries have done quite well over the past eight years. In particular 2004 and 2005 were especially good years. How can such performance be made to stick and even expand? The answer to that question requires better understanding of the source of good performance. This paper proceeds on the assumption that technology was, at least partially, responsible. The result shows that a feeble technology undercuts per capita real GDP across African countries. However, the impacts of new technologies, measured by the intensities of internet and cell phone use are very strong. The policy implication of the findings speaks to the need for investment in new technologies for which productivity is high and the adoption and diffusion costs seem low. Further research can clarify the findings and policy by expanding and improving the data coverage, and examining effects on income of different kinds of technologies

An analysis of causal relations among inflation, financial structure, Tobin's Q and investment

An examination of the short- and long-run effects of inflation on financial markets and investment.Inflation (Finance) ; Corporations - Finance