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Santiago de Cuba, Cuba

Martinez J.D.,Federal University of Itajuba | Martinez J.D.,Pontifical Bolivarian University | Silva Lora E.E.,Federal University of Itajuba | Andrade R.V.,Federal University of Itajuba | Jaen R.L.,University of the East of Cuba
Biomass and Bioenergy | Year: 2011

This work presents an experimental study of the gasification of a wood biomass in a moving bed downdraft reactor with two-air supply stages. This configuration is considered as primary method to improve the quality of the producer gas, regarding its tar reduction. By varying the air flow fed to the gasifier and the distribution of gasification air between stages (AR), being the controllable and measurable variables for this type of gasifiers, measuring the CO, CH4 and H2 gas concentrations and through a mass and energy balance, the gas yield and its power, the cold efficiency of the process and the equivalence ratio (ER), as well as other performance variables were calculated. The gasifier produces a combustible gas with a CO, CH4 and H2 concentrations of 19.04, 0.89 and 16.78% v respectively, at a total flow of air of 20 Nm3 h-1 and an AR of 80%. For these conditions, the low heating value of the gas was 4539 kJ Nm-3. Results from the calculation model show a useful gas power and cold efficiency around 40 kW and 68%, respectively. The resulting ER under the referred operation condition is around 0.40. The results suggested a considerable effect of the secondary stage over the reduction of the CH4 concentration which is associated with the decreases of the tar content in the produced gas. Under these conditions the biomass devolatilization in the pyrolysis zone gives much lighter compounds which are more easily cracked when the gas stream passes through the combustion zone. © 2011 Elsevier Ltd.

Portuondo I.P.,University of the East of Cuba
Revista Cubana de Salud Publica | Year: 2012

Introduction: Gram positive bacterium Bacillus cereus is widely distributed in the environment. This bacterium is responsible for two food poisoning syndromes (emetic and diarrheal) and also it has been related to other diseases such as endocarditis and endophthalmitis; therefore it is recognized as opportunist pathogen. Objective: to review the information about Bacillus cereus toxins and its connection with food poisoning, as well as to address others factors influencing this bacterium's virulence. Data sources: for collecting this information, search engines such as Google and Scirus. Reviewed articles included research articles, systematic reviews on this topic and free accessed book chapters, or requested from the authors. Data synthesis: the review delved into Knowledge on diarrheal and emetic toxins, clinical symptomatology and time of occurrence, as soon as foodstuffs involved in each syndrome. This helps the clinician to look for the causes of toxin infections. A general overview of Bacillus cereus microbiology and others factors that explain its virulence and other implications in the human health was given. Conclusions: the acquired knowledge shows that Bacillus cereus is one bacterium with clinical importance rather than a mere environmental pollutant.

Reyes J.B.,University of the East of Cuba | Shapiro M.,Escuela Superior de Fisica y Matematicas
Mathematical Methods in the Applied Sciences | Year: 2010

For a positive integer n let Cl0,n be the universal Clifford algebra with the signature (0,n). The name Clifford analysis is usually referred to the function theories for functions in the kernels of the two operators: the (Cliffordian) Cauchy- Riemann operator and the Dirac operator. For n = 2, Cl0,2 becomes the skew-field of Hamilton's quaternions for which the two operators are widely known: the Moisil-Théodoresco and the Fueter operators. We establish the precise relations between the Moisil-Théodoresco operator and the Dirac operator for Cl0,3. It turns out that the case of the Cauchy- Riemann operator for Cl0,3 and the Fueter operator is more sophisticated, and we describe the peculiarities emerging here. © 2009 John Wiley & Sons, Ltd.

Speck-Planche A.,University of the East of Cuba | Kleandrova V.V.,Moscow State University of Food Production
Molecular Diversity | Year: 2012

Rational design of entry inhibitors is an active area for the discovery of new and effective anti-HIV agents. C-C Chemokine receptors represent key targets for the HIV entry process. Several of these proteins with features to be HIV co-receptors have not been sufficiently studied or used for the design of novel entry inhibitors. With the purpose to overcome this problem, we develop here a fragment-based approach for the design of multi-target inhibitors against four C-C chemokine receptors. This approach was focused on the construction of a multi-target QSAR discriminant model using a large and heterogeneous database of compounds and substructural descriptors for the classification and prediction of inhibitors for C-C chemokine receptors. The model correctly classified more than 89% of active and inactive compounds in both: training and prediction series. As principal advantage, this model permitted the automatic and fast extraction of fragments responsible for the inhibitory activity against the different C-C chemokine receptors under study and new molecular entities were suggested as possible versatile inhibitors for these proteins. © 2011 Springer Science+Business Media B.V.

Adrian T.-Q.,University of the East of Cuba | Rodolfo N.-G.,Institute Ecologia
Zootaxa | Year: 2012

The final stadium larva of Erythrodiplax bromeliicola Westfall is formally described and illustrated. The light brown scape and pedicel and creamy pale flagellum of the antenna, plus the abundant short, reddish, spiniform setae on the integument of the body surface and epiproct, comprise an exclusive combination of characters in the larva of E. bromeliicola. Information on larval habitat and a key for the larvae of the five Erythrodiplax species occurring in Cuba are provided. Details on morphological variation of an adult population from Cuba are also provided. Copyright © 2012 · Magnolia Press.

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