Evaluación de tecnologías de quema de biomasa en el Uruguay

The present paper analyzes the different biomass burner technologies used in Uruguay from the combustion process standpoint, seen as a system of processes with highly non linear mechanisms of mass, momentum and energy transfer phenomena. Technologies based on fixed, moving and fluidized bed are compared and contrasted, with a special emphasis on the effect that fuel quality has on the choice of technology, given the variations found in the biomass quality, in terms of its size distribution and composition. The problem of designing equipment for any given chemical process is stated and the inherent difficulty when scaling an existing installation is proven. The need to acquire knowledge of theprocesses and the relationships between them is essential for a successful scale-up. In themajority of cases, the geometry has to be altered, dramatically affecting the mechanisms within.The highly coupled non linear system renders analytical solutions impossible, so approximatenumerical solutions are sought. Numerical results of a study of the sensitivity of bed permeabilityon combustion stability are shown.El presente trabajo analiza las diferentes tecnologías de quema de biomasa usadas en el Uruguay desde el punto de vista del complejo e interrelacionado sistema de transferencia de flujo, masa y energía que comprenden al proceso de combustión. Se comparan y contrastan lastecnologías basadas en lecho fijo, lecho móvil y de lecho fluidizado. Se hace énfasis en la sensibilidad que tiene la calidad del combustible en los diferentes procesos. Este efecto es particularmente importante debido a la alta variación de la biomasa disponible en términos de su distribución de tamaño y composición. Los desafíos planteados por la transferencia de tecnología existente al nuevo combustible son elucidados. Se plantea el problema a resolver para diseñar un reactor químico genérico donde se demuestra la dificultad inherente de escalar, aún teniendo una planta piloto funcionando. La complejidad del sistema hace imperioso el conocimiento profundo de los mecanismos actuantes y la influencia que tienen las variables del proceso en los mismos. La no linealidad y grado de acoplamiento que tienen los mecanismos actuantes dificulta la solución analítica del sistema, por lo que se buscan soluciones numéricas. Se muestran resultados sobre el análisis de sensibilidad de la permeabilidad del lecho a la inestabilidad de combustión, obteniéndose así valiosas consideraciones de diseño

Problemas relacionados a cenizas de biomasas con alto contenido de sales alcalinas y su mitigación: evaluación experimental

Biomass is regarded as a renewable source of energy and is playing a role in future fuel supply trend, with great acceleration. However, due to the chemical composition of the ash of certain types of biomass (particularly short rotation crops like grasses, canes and straws), boilerrelated problems have occurred systematically in the past. These fuels are rich in alkaline metals (potassium, phosphorus, chlorine and sodium) which form complex eutectic salts that effectively lower the melting point of the ashes during combustion and cause fouling and slagging problems, especially in superheater tubes. This work reviews the latest investigations regarding the prediction of these problems through the evaluation of the ashes in the laboratory and discuss their mitigation by fuel leaching and blending. As a means to demonstrate the methodology, experimental data related to the evaluation of the Common Cane are presented, resulting from our own laboratory tests. These include fusion/sintering tests of ashes sampled from canes in the as-is and waterleached condition and the comparisons with other more traditional biomasses. The results show that the as-is state would be unacceptable to burn, but leaching with water and/or blending withmore stable ashes reduces the detrimental effects on boiler components to a tolerable level. La biomasa está considerada como una fuente renovable de energía y está jugando un papel muy importante en la búsqueda de nuevas fuentes de energía. La reciente tendencia a consumir cultivos energéticos del tipo herbáceo ha causado problemas en los sistemas industriales, debido principalmente a la composición de su ceniza rica en Potasio, Sodio, Cloro y Fósforo. Dichas sales forman eutécticos de bajo punto de fusión formando zonas líquidas que aglomeran partículas sólidas (fouling) o fundiendo por completo (slagging). Este trabajo resume las investigaciones de los últimos años en este tema, discutiendo la importancia del análisis de laboratorio. Los métodos para evitar dichos problemas en las calderas son evaluados, principalmente el baño del combustible con agua (leaching) y el agregado de sales estables a la ceniza en el quemador. Tomando el caso de la Caña Común (Arundo Donax) como un potencial combustible de alto rendimiento por hectárea, se presentan resultados de la evaluación de su ceniza y se estima su potencial de daño en calderas, como producto de nuestra investigación experimental.Se investiga en el laboratorio el efecto del baño de agua en la consecuente ceniza y el impacto quetiene mezclar su ceniza con la de corteza de Eucalyptus en cuanto a su comportamiento en fusión

Comportamiento de cenizas y su impacto en sistemas de combustión de biomasa

Biomass as a source of energy is key to the progress of developing countries like Uruguay, since the application of a safe and efficient burning technology uses a renewable source of energy, relieves the dependence on imported crude oil, generates more employment than traditional sources and has a zero net greenhouse gas effect. Knowledge of the characteristics of the fuel and its behaviour in combustion systems is veryimportant, since the installations are subject to chemical and physical attack from its ashes. The ash content and composition must be measured and analyzed, and its impact evaluated. In particular, cereals and other short-rotation plants have ashes with a high tendency to form deposits and enhance corrosion processes. This paper focuses on the effects that some kinds of fuels have on the physical and chemical damage of boiler components, particularly Chlorine enhanced corrosion. Recommendations for the remediation of critical situations are provided.La biomasa como combustible, además de proveer energía de manera renovable, decrece la dependencia del crudo importado y genera valor agregado para los países donde se desarrollan. El conocimiento del comportamiento del combustible es imprescindible para diseñar y operar equipos de manera segura y eficiente, en particular el conocimiento de los minerales que contenga ya que su ceniza jugará un papel importante en la dinámica del sistema de generación. A través del conocimiento de la composición química y propiedades físicas de la ceniza es posible predecir la tendencia a formar depósitos en componentes de caldera y su potencial para causar corrosión, erosión y abrasión. El comportamiento de las cenizas en el sistema es altamente dependiente del combustible, en particular cuando se trata de desechos industriales o  cultivos energéticos. Estos combustibles tienen mayor contenido de minerales, en particular Sodio Potasio, Fósforo y Cloro, alto contenido de cenizas con bajo punto de fusión y alto potencial corrosivo. Este trabajo se concentra en las características de la ceniza derivada de la combustión de biomasa, con particular atención en la química de transformaciones a alta temperatura y su efecto sobre las instalaciones. Se hace énfasis en los posibles problemas que ocurren cuando se adecúan las tecnologías de quemado de madera a cultivos energéticos, por ejemplo, de manera de evitar fallas catastróficas. Se concluye con recomendaciones sobre el manejo, control y prevención de problemas asociados a cenizas

Dai dati grezzi all’interpretazione biologica: progettazione e analisi degli esperimenti di espressione genica realizzati mediante microarray

Negli ultimi venti anni la genetica e la biologia molecolare hanno contribuito significativamente al progresso scientifico-medico, fornendo strumenti per isolare, clonare e studiare molti dei geni che compongono il genoma umano. E’ ora possibile analizzare contemporaneamente l'espressione di migliaia di geni, ossia valutare quello che viene chiamato profilo genico, grazie all’uso di speciali supporti tecnologicamente avanzati denominati microarray. Un singolo esperimento di espressione genica realizzato con microarray produce migliaia di dati, per i quali è necessario un approccio rigoroso di tipo matematico e bioinformatico, sia nelle fasi di acquisizione e analisi che in quelle di interpretazione e archiviazione. A differenza delle fasi di preparazione dei campioni e ibridizzazione dei vetrini, che ormai sono regolate da protocolli sufficientemente standardizzati, i passaggi che portano dall’estrazione dei dati all’interpretazione biologica dei risultati non possono essere riassunti in un protocollo unico. Questo progetto di dottorato ha avuto lo scopo di studiare i metodi di progettazione di un esperimento di espressione genica mediante microarray e gli strumenti bioinformatici che servono a realizzare le fasi di estrazione e pre-trattamento dei dati, l’analisi statistica e l’interpretazione dei risultati. Tali metodi sono stati applicati a quattro esperimenti realizzati nel laboratorio presso il quale è stata svolta questa tesi. Sono stati individuati, fra quelli disponibili, i metodi bioinformatici per l’estrazione, il pre-trattamento e l’analisi statistica dei dati più affidabili e versatili per l’eliminazione degli errori legati alla metodica e per l’acquisizione di un dato statisticamente robusto. Il confronto critico dei metodi analizzati ha messo in luce la necessità di mettere a punto una soluzione ottimale di analisi per ciascun esperimento. La valutazione degli strumenti utili per l’interpretazione biologica dei risultati ha messo, invece, in evidenza profonde limitazioni legate essenzialmente all’assenza di informazioni ordinatamente catalogate e alla incompleta modellazione dei processi di co-regolazione genica nelle banche dati

Η καλλιέργεια της δημιουργικότητας στη μουσική μέσω αυτοσχεδιασμού σε μαθητές Γ΄ τάξης Δημοτικού Σχολείου

Στην παρούσα εργασία παρουσιάζουμε τα αποτελέσματα μιας σύντομης παρέμβασης, διάρκειας 2 μηνών που αφορά στο μάθημα της μουσικής με θέμα τα οφέλη του αυτοσχεδιασμού στην ανάπτυξη της δημιουργικότητας. Η παρέμβαση πραγματοποιήθηκε σε μαθητές Γ΄ τάξης ιδιωτικού δημοτικού σχολείου των βορείων προαστίων της Αθήνας. Πριν και μετά την παρέμβαση χορηγήθηκε το Εργαλείο Μέτρησης της Δημιουργικής Σκέψης στη Μουσική (Measure of Creative Thinking in Music, MCTM-II), το οποίο εξετάζει 4 Μουσικές Παραμέτρους που ορίζουν τη Δημιουργική Σκέψη στη Μουσική (Webster, 1994). Συγκεκριμένα, η Μουσική Διάρκεια (Musical Extensiveness), εξετάζει τη χρονική διάρκεια που θα αφιερώσει ένα άτομο σε μια μουσική δημιουργία. Η Μουσική Ευελιξία (Musical Flexibility), εξετάζει το εύρος της μουσικής έκφρασης με όρους δυναμικής (σιγά/δυνατά), τονικού ύψους (χαμηλά/ψηλά) και τέμπο (αργά/γρήγορα). Η Μουσική Πρωτοτυπία (Musical Originality), εξετάζει την χρήση ευφάνταστων και καινοφανών μουσικών ιδεών και τέλος η Μουσική Σύνταξη (Musical Syntax), εξετάζει τη λογική συνέπεια των μουσικών ιδεών με όρους επανάληψης, αντίθεσης και ακολουθίας αυτών (Webster, 1994). Το κύριο εύρημα μετά την ολοκλήρωση της παρέμβασης ήταν ότι οι δυο ομάδες (πειραματική – ελέγχου) είχαν διαφορά στην επίδοσή τους. Η πειραματική ομάδα σημείωσε συνολικά και για τις τέσσερις μουσικές παραμέτρους καλύτερη επίδοση από την ομάδα ελέγχου. Ωστόσο, η διαφορά μεταξύ τους δεν ήταν στατιστικά σημαντική, γεγονός που ενδεχομένως θα μπορούσε να αποδοθεί στην διάρκεια της παρέμβασης.In this paper we present the results of a short 2-month intervention on the music lesson on the benefits of improvisation in the development of creativity. The intervention took place in 3rd grade students of a private primary school in the northern suburbs of Athens. Before and after the intervention was conducted, we administered the Measure of Creative Thinking in Music, MCTM-II), which examines 4 Musical Parameters, defining Creative Thinking in Music (Webster, 1994). Specifically, Musical Extensiveness examines the length of time that a person will devote to a musical creation. Musical Flexibility examines the range of musical expression in terms of dynamic (slow/high), pitch (low/high) and tempo (slow/fast). Musical Originality examines the use of imaginative and novel musical ideas, and Musical Syntax examines the logical consequence of musical ideas in terms of repetition, contrast and sequence (Webster, 1994). The main finding after the intervention was that the two groups (experimental - control) had a difference in their performance. The experimental group scored a better overall score for the four musical parameters than the control group. However, the difference between them was not statistically significant, which could possibly be attributed to the duration of the intervention

Μεθοδολογικό πλαίσιο χωρικής ανάλυσης οικιστικών συγκεντρώσεων & προσδιορισμού αστικών συστοιχιών σε περιβάλλον ΓΣΠ

103 σ.Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) "Γεωπληροφορική"Σκοπό της παρούσας μεταπτυχιακής διπλωματικής εργασίας αποτελεί η δημιουργία ενός μεθοδολογικού πλαισίου ανάλυσης οικιστικών συγκεντρώσεων & προσδιορισμού αστικών συστοιχιών στον Ελλαδικό χώρο σε περιβάλλον ΓΣΠ. Αφού προσδιορίζεται η βασική έννοια της «αστικής συστοιχίας», κατηγοριοποιούνται οι Οργανισμοί Τοπικής Αυτοδιοίκησης (ΟΤΑ) Α’ βαθμού σε τρία επίπεδα και με τη βοήθεια μεθόδων και τεχνικών της Γεωγραφικής Ανάλυσης προσδιορίζονται οι αποστάσεις από τους γειτονικούς ΟΤΑ, ορίζονται οι ζώνες εξυπηρέτησης με βάση των οποίων υπολογίζονται οι γεωστατιστικοί δείκτες και το χωροθετικό πηλίκο, σε περιβάλλον Γεωγραφικών Συστημάτων Πληροφοριών. Ακολούθως δημιουργείται ο δείκτης συστοιχίας (Ι) για τους ΟΤΑ του μεσαίου επιπέδου με βάση τις αποστάσεις από τους γειτονικούς ΟΤΑ των άλλων επιπέδων. Στη συνέχεια με τα δεδομένα της Στατιστικής που αφορούν τους μετακινούμενους εργαζόμενους υπολογίζονται οι εισερχόμενοι, οι εξερχόμενοι, το ισοζύγιο των ροών εργαζομένων καθώς και ένας δείκτης μετακίνησης. Ακολούθως, η εφαρμογή του μεθοδολογικού πλαισίου οδηγεί στον προσδιορισμό ενός υποδείγματος συσχέτισης του δείκτη μετακίνησης με το δείκτη συστοιχίας, πληθυσμιακές και γεωμορφολογικές μεταβλητές. Τέλος, γίνεται αναφορά στα θετικά και αρνητικά σημεία της μεθοδολογίας και προτείνονται τρόποι μελλοντικής διερεύνησης και εναλλακτικής προσέγγισης του προβλήματος.The aim of present dissertation constitutes the assessment of methodological frame of analysis of urban clusters and determination of urban concentrations of Greece. Primarily the meaning of ‘urban cluster’ was defined. Aftermaths, the Local Administrative Unit (LAU1- municipalities/communities) were categorized in three levels. Different methods and techniques of Geographic Analysis were combined in environment of Geographical Information Systems (GIS). Nearest Neighbor Analysis, delimitation of service areas, Geostationary Indicators and Locational Quotient. Followingly was determined the cluster indicator of intermediate LAU1 basically to the Nearest Neighbor LAU1 of other levels. Then, concerning the commuting workers, the balance of entering and coming-out workers, as well as a commuting indicator were calculated. Moreover, the application of methodological frame leads to the determination of a model of cross- correlation of commuting indicator with cluster indicators, demographic and geomorphological variables. Finally, the positive and negative points of methodology are assessed and proposed ways of future investigation and alternative approach of problem.Σοφία Μ. Μελισσάρ

Effects on human transcriptome of mutated BRCA1 BRCT domain: A microarray study

BACKGROUND: BRCA1 (breast cancer 1, early onset) missense mutations have been detected in familial breast and ovarian cancers, but the role of these variants in cancer predisposition is often difficult to ascertain. In this work, the molecular mechanisms affected in human cells by two BRCA1 missense variants, M1775R and A1789T, both located in the second BRCT (BRCA1 C Terminus) domain, have been investigated. Both these variants were isolated from familial breast cancer patients and the study of their effect on yeast cell transcriptome has previously provided interesting clues to their possible role in the pathogenesis of breast cancer. METHODS: We compared by Human Whole Genome Microarrays the expression profiles of HeLa cells transfected with one or the other variant and HeLa cells transfected with BRCA1 wild-type. Microarray data analysis was performed by three comparisons: M1775R versus wild-type (M1775RvsWT-contrast), A1789T versus wild-type (A1789TvsWT-contrast) and the mutated BRCT domain versus wild-type (MutvsWT-contrast), considering the two variants as a single mutation of BRCT domain. RESULTS: 201 differentially expressed genes were found in M1775RvsWT-contrast, 313 in A1789TvsWT-contrast and 173 in MutvsWT-contrast. Most of these genes mapped in pathways deregulated in cancer, such as cell cycle progression and DNA damage response and repair. CONCLUSIONS: Our results represent the first molecular evidence of the pathogenetic role of M1775R, already proposed by functional studies, and give support to a similar role for A1789T that we first hypothesized based on the yeast cell experiments. This is in line with the very recently suggested role of BRCT domain as the main effector of BRCA1 tumor suppressor activity

Gender differences and aging: Effects on the human heart

Objectives.This study investigated the changes in myocyte size and number in the left and right ventricles that occur with aging in the female and male heart.Background.Differences in life span between women and men may be related to a better preservation of myocardial structure in the female heart with aging. On this basis, the hypothesis was advanced that the aging process has a different impact on the integrity of the myocardium in the two genders.Methods.Morphometric methodologies were applied to analyze the changes in number and size of ventricular myocytes in the hearts of 53 women and 53 men. The changes in mononucleated and binucleated myocytes with age were determined in enzymatically dissociated cells. The age interval examined varied from 17 to 95 years.Results.Aging was associated with a preservation of ventricular myocardial mass, aggregate number of mononucleated and binucleated myocytes, average cell diameter and volume in the female heart. In contrast, nearly 1 g/year of myocardium was lost in the male heart, and this phenomenon accounted for the loss of ∼64 million cells. This detrimental effect involved the left and right sides of the heart. In the remaining cells, myocyte cell volume increased at a rate of 158 μm3/year in the left and 167 μm3/year in the right ventricle.Conclusions.Aging does not lead to myocyte cell loss and myocyte cellular reactive hypertrophy in women, indicating that gender differences may play a significant role in the detrimental effects of the aging process on the heart