Integración comercial y difusión tecnológica : el caso del África Subsahariana

El objetivo del presente artículo es analizar los efectos de la integración comercial en el crecimiento económico del África Subsahariana. Con tal fin, se define un modelo teórico que, tomando como base el trabajo de Mankiw, Romer y Weil (1992), incluye la apertura a los intercambios internacionales como variable clave para absorber la tecnología generada por los países ubi-cados en la frontera tecnológica. El modelo no contempla de forma exclusiva los factores domésticos, sino que incluye, de forma explícita, el devenir econó-mico de los países desarrollados. Para contrastar empíricamente las hipótesis planteadas se realiza una estimación de datos de panel para una muestra de 22 países del África Subsahariana, durante el periodo 1970-2003. Los resul-tados confirman la influencia positiva sobre el crecimiento económico de la inversión en capital físico y humano. El incremento de la apertura exterior y de la libertad en los mercados internos y externos constituye una pieza clave para alcanzar unas tasas de crecimiento del producto sostenidas. El crecimiento del producto per cápita en los países de renta más elevada de la OCDE repercute positivamente en la región subsahariana al activar su demanda externa y favo-recer la difusión de tecnología. ____________________________________________The main objective of this article is the analysis of the economic effects of trade integration in Sub-Saharan Africa. We define a theoretical model that use the Mankiw, Romer and Weil (1992) background, and includes trade openness as a key variable to absorb the technology generated by developed countries in the technological threshold. Not only are domestic factors considered, but also the economic performance of the most developed countries around the world. These predictions are tested using GMM technique in a panel data per-formed on a sample of 22 countries belonging to the Sub-Saharan region over the period 1970-2003. The estimations confirm that Africa’s growth rates are positively related to investment and human capital accumulation. Greater inte-gration and economic freedom in internal and external markets are the key to a sustainable growth rate. GDP growth per capita in OECD countries generates positive externalities in the Sub-Saharan region, by activating external demand and technological diffusion

Zinc Iodide Catalyzed Synthesis of Trisubstituted Allenes from Terminal Alkynes and Ketones

A straightforward, user-friendly, efficient protocol for the one pot, ZnI2-catalyzed allenylation of terminal alkynes with pyrrolidine and ketones, toward trisubstituted allenes, is described. Trisubstituted allenes can be obtained under either conventional heating or microwave irradiation conditions, which significantly reduces the reaction time. A sustainable, widely available, and low-cost metal salt catalyst is employed, and the reactions are carried out under solvent-free conditions. Among others, synthetically valuable allenes bearing functionalities such as amide, hydroxyl, or phthalimide can be efficiently prepared. Mechanistic experiments, including kinetic isotope effect measurements and density functional theory (DFT) calculations, suggest a rate-determining [1,5]hydride transfer during the transformation of the intermediate propargylamine to the final allene.The research project was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the "1st Call for H.F.R.I. Research Projects to support Faculty Members & Researchers and the procurement of high-cost research equipment grant" (Project Number: 16.Acronym: SUSTAIN). We thank Professor Thomas Mavromoustakos for his advice and support concerning the calculation of the relaxation delay times for the NMR analysis related to the kinetic isotope effect measurements. We also acknowledge the contribution of COST Action CA15106 (C-H Activation in Organic Synthesis.CHAOS). We also thank the Spanish Ministerio de Ciencia e Innovacion (PID2019-110008GB-I00) and IZO-SGI SGIker of UPV/EHU for financial and human support. The Special Account for Research Grants of the National and Kapodistrian University of Athens is also gratefully acknowledged for funding (research program 70/4/17454)

Unprecedented Multicomponent Organocatalytic Synthesis of Propargylic Esters via CO2 Activation

An efficient and straightforward organocatalytic method for the direct, multicomponent carboxylation of terminal alkynes with CO2 and organochlorides, towards propargylic esters, is reported for the first time. 1,3-Di-tert-butyl-1H-imidazol-3-ium chloride, a simple, widely-available, stable, and cost-efficient Nheterocyclic carbene (NHC) precursor salt was used as the (pre) catalyst. A wide range of phenylacetylenes, bearing electronwithdrawing or electron-donating substituents, react with allylchlorides, benzyl chlorides, or 2-chloroacetates, providing the corresponding propargylic esters in low to excellent yields. DFT calculations on the mechanism of this transformation indicate that the reaction is initiated with the formation of an NHCcarboxylate, by addition of the carbene to a molecule of CO2. Then, the nucleophilic addition of this species to the corresponding chlorides has been computed to be the rate limiting step of the processWe acknowledge the contribution of COST Action CA15106 (C−H Activation in Organic Synthesis-CHAOS). The Special Account for Research Grants of the National and Kapodistrian University of Athens is also gratefully acknowledged for funding (Research Program 70/3/14872). Moreover, we are thankful for the technical and human support provided by IZO-SGI SGIker of UPV/EHU, and the European Funding Horizon 2020-MSCA (ITN-EJD CATMEC 14/06-721223

Quantification of the influence of the C, Cr and P contents on the permeability of hydrogen through Fe alloys

[EN] Ferritic-martensitic steels are candidate materials for blanket structural components of future thermonuclear fusion reactors. However, the tritium inventory that can be retained in different components of the reactor and its ability to migrate through the walls of any material may affect the correct operation of any fusion device. Therefore, the permeability of hydrogen isotopes through ferritic-martensitic steels, which depends on its metallurgical composition, becomes a key issue. The European Fusion Development Agreement (EFDA) supplied 9 Fe alloys with controlled chemical alloying element contents and microstructure. The main alloying elements were C, Cr and P and they appeared in various concentrations in the 9 alloys. They were experimentally analyzed by means of the gas evolution permeation technique with temperatures ranging from 423 K to 823 K and for high purity hydrogen loading pressures ranging from 5.0 x 102 Pa to 1.5 x 105 Pa. The transport regime turned out to be diffusive and it was studied in depth, so that the permeability of each alloy was characterized by an Arrhenius-type regression for the aforementioned temperature range. This work summarizes all the experimental measurements carried out for the permeability of hydrogen through the 9 alloys. It provides a quantification of the influence of the composition of the alloy on this transport parameter, posing different mathematical expressions for the variation of the permeability as a function of the contents of C, Cr and P.This work has been carried out in the framework of research projects funded by the Spanish Ministry of Science and Innovation (MEC08/98) , the University of the Basque Country (UPV/EHU-EHU08-34) and the European Fusion Development Agreement (EFDA MAT-REMEV) . The authors would also like to thank the FEMaS Coordinated Action project for the support in knowledge exchange among different research groups and Pilar Fernandez from CIEMAT for the preparation of the tested samples

Manganese-Catalyzed Multicomponent Synthesis of Tetrasubstituted Propargylamines: System Development and Theoretical Study

The importance of multicomponent reactions as an efficient tool in organic synthesis is widely recognized, as the need for sustainable, practical, atom- and step-economic methodologies is becoming a crucial concept in contemporary research. In this context, the synthesis of propargylamines via multicomponent protocols holds great promise, because of their biological action and their potential as synthons. Ketone-derived, tetrasubstituted propargylamines are a relatively unexplored subclass of compounds, while protocols to access them have only been described in the past decade, owing to the challenging nature of ketones as multicomponent coupling partners. Herein, we report a catalytic system based on the earth-abundant manganese for the ketone, amine, alkyne (KA2) reaction. The efficiency of manganese, combined with sustainable reaction conditions, comprise a useful new method for accessing various interesting propargylamines. Additionally, the use of computational methods reveals mechanistic aspects of this reaction, for the first time, raising important points regarding the reactivity of both manganese and ketones.This work was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “First Call for H.F.R.I. Research Projects to support Faculty members and Researchers and the procurement of high-cost research equipment grant” (Project Number: 16-Acronym: SUSTAIN), as well as by European Funding: Horizon 2020-MSCA (ITN-EJD CATMEC 14/06-721223). The contribution of COST Action CA15106 (C−H Activation in Organic Synthesis - CHAOS) is also gratefully acknowledged

Cationic exchange in nanosized ZnFe2O4 spinel revealed by experimental and simulated near-edge absorption structure

The non-equilibrium cation site occupancy in nanosized zinc ferrites (6-13 nm) with different degree of inversion (0.2 to 0.4) was investigated using Fe and Zn K-edge x-ray absorption spectroscopy XANES and EXAFS, and magnetic measurements. The very good agreement between experimental and ab-initio calculations on the Zn K-edge XANES region clearly show the large Zn2+(A)--Zn2+[B] transference that takes place in addition to the well-identified Fe3+[B]--Fe3+(A) one, without altering the long-range structural order. XANES spectra features as a function of the spinel inversion were shown to depend on the configuration of the ligand shells surrounding the absorbing atom. This XANES approach provides a direct way to sense cationic inversion in these spinel compounds. We also demonstrated that a mechanical crystallization takes place on nanocrystalline spinel that causes an increase of both grain and magnetic sizes and, simultaneously, generates a significant augment of the inversion.Comment: 5 pages, 5 eps figures, uses revtex4, corrected table

Influenza vaccination among multiple sclerosis patients during the COVID-19 pandemic

In the context of the COVID-19 pandemic, the co-circulation of influenza and SARS-CoV-2 viruses may have severe complications for vulnerable populations. For this reason, the World Health Organization pointed to the 2020–2021 anti-influenza campaign as being of special relevance. Our aim was to assess the 2020–2021 influenza vaccination coverage, and its associated factors, among patients in a Spanish multiple sclerosis (MS) unit. A cross–sectional study was conducted. People attending the MS unit of the Clinical Hospital of Zaragoza during 2020 were included. Variables were obtained by reviewing records. Associations with 2020–2021 influenza vaccination were analyzed using bivariate analysis and a multiple logistic regression model. A total of 302 patients were studied; 62.6% were women, whose mean age (standard deviation) was 47.3 (11.5) years. The 2020–2021 influenza vaccination coverage was 55.3% (59.8% in women and 47.8% in men). A total of 89.7% had at least one other indication for vaccination (e.g., immunosuppressive treatment in 225 patients). The variables associated with getting vaccinated were being female (adjusted odds ratio (95% confidence interval) (aOR (95%CI) = 2.12 (1.12–3.99)), having received the 2019–2020 influenza vaccine (aOR (95%CI) = 31.82 (14.71–68.86)) and being born in Spain (aOR (95%CI) = 12.91 (1.07–156.28)). Coverage is moderate compared to other countries. It is necessary to develop strategies to improve it, especially in men and those born outside Spain

Relational Goods and Endurance of Voluntary Associational Participation: The Mapuche Indigenous Case in Santiago de Chile.

In this article, I analyse the reasons for sustaining membership in voluntary ethnic associations of Mapuche people living in Santiago de Chile. By following a relational goods approach, I suggest that the constructed nature of ethnicity leads the Mapuche to create and join ethnic associations in an urban milieu. This study reveals that the main motivations for sustaining an active associational engagement in Santiago are based on three accounts: identity recovery struggle, leaving an identity legacy and bonding with their ethnic peers; all of these identified as relational goods. This investigation is based on an eight-month ethnographic fieldwork conducted in Santiago.This work was supported by the University of Cambridge Sociology Graduate Education Committee (GEC) Fieldwork Funding; Newnham College, University of Cambridge Fieldwork Grant; and under the Programme Becas de Doctorado con Acuerdo Bilateral en el Extranjero Becas Chile-Cambridge (Grant Fondecyt: N° 84140015)