966 research outputs found

    Analysis of pressure blips in aft-finocyl solid rocket motor

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    Ballistic anomalies have frequently occurred during the firing of several solid rocket motors (SRMs) (Inertial Upper Stage, Space Shuttle Redesigned SRM (RSRM) and Titan IV SRM Upgrade (SRMU)), producing even relevant and unexpected variations of the SRM pressure trace from its nominal profile. This paper has the purpose to provide a numerical analysis of the following possible causes of ballistic anomalies in SRMs: an inert object discharge, a slag ejection, and an unexpected increase in the propellant burning rate or in the combustion surface. The SRM configuration under investigation is an aft-finocyl SRM with a first-stage/small booster design. The numerical simulations are performed with a quasi-one-dimensional (Q1D) unsteady model of the SRM internal ballistics, properly tailored to model each possible cause of the ballistic anomalies. The results have shown that a classification based on the head-end pressure (HEP) signature, relating each other the HEP shape and the ballistic anomaly cause, can be made. For each cause of ballistic anomalies, a deepened discussion of the parameters driving the HEP signatures is provided, as well as qualitative and quantitative assessments of the resultant pressure signals

    Influencia de la infestación por Dacus Oleae sobre el flavor de aceites, extraídos de aceitunas atacadas, por análisis HPLC y HRGC de compuestos volátiles

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    The authors have examined the influence of the Dacus Oleae infestation on the aroma of the oils obtained from olives of Coratina and Nebbio varieties at different levels of attack. The results obtained indicated a worsening of the qualitative level of the oils obtained from increasing percentages of infested olives; these were found to have a great decrease of phenolic substances and higher contents of both volatile alcohols and aldehydes with an unpleasant sensation. Of particular interest was hexanal/total volatile alcohols ratio, in which having been well correlated with the extent of infestation, would permit one to establish in an objective manner, if and how much the olives from which an oil has been extracted have suffered a Dacus attack.Los autores han examinado la influencia de la infestación por Dacus Oleae sobre el aroma de aceites obtenidos de aceitunas de las variedades Coratina y Nebbio en diferentes estados de ataque. Los resultados obtenidos indicaron un empeoramiento de los niveles de calidad de los aceites obtenidos a medida que se incrementaba el porcentaje de aceitunas infestadas; mostrando una gran disminución de las sustancias fenólicas y altos contenidos tanto de alcoholes volátiles como de aldehídos, con una sensación desagradable. De particular interés fue la relación hexanal/alcoholes volátiles totales, la cual ha sido bien correlacionada con la extensión de la infestación, lo que permitiría establecer de una manera objetiva, sí y cuantas de las aceitunas de las cuales se ha extraído, han sufrido ataque por Dacus

    Ésteres alquílicos de ácidos grasos en aceitunas de mesa en relación con fermentaciones anormales y tratamientos tecnológicos mal realizados

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    There are several methods to prepare table olives, and each of the steps and conditions during this processing can affect the composition and nutritional value of the product. The influence of abnormal fermentation and poorly conducted technological treatments was examined here in terms of the lipid fraction of table olives. In ‘Greek style’ olives, a low concentration of brine can allow the growth of spontaneous microflora and consequent organoleptic defects (‘putrid/butyric fermentation’, ‘winey-vinegary’). Here, the ‘Kalamata’ and ‘Moresca’ cultivars can produce methyl esters (methyl oleate/ linoleate: 553 and 450 mg·kg-1 oil, respectively) and ethyl esters (ethyl oleate/ inoleate: 4764 and 4195; palmitate: 617 and 886 mg·kg-1 oil, respectively). In ‘Sevillan style’ olives, a high NaOH concentration influences the fatty-acid composition less, but is difficult to eliminate, for a ‘soapy’ defect. The ‘Giarraffa’ and ‘Nocellara del Belice’ cultivars produce only ethyl esters (ethyl oleate/ linoleate: 222 and 289 mg·kg-1 oil, respectively). With this production of ethyl and methyl esters from the principal fatty acids in the lipid fractions of table olives, methods that provide only biological treatments (i.e., Greek style) pose more risk than methods that provide only chemical treatments (i.e., Sevillan style).H�a�y� �v�a�r�i�o�s� �m�ét�o�d�o�s� �p�a�r�a� �p�r�e�p�a�r�a�r� �l�a�s� �a�c�e�i�t�u�n�a�s� �d�e� �m�e�s�a�,� �y� �c�a�d�a� �u�n�o� �d�e� �l�o�s� �p�a�s�o�s� �y� �c�o�n�d�i�c�i�o�n�e�s� �d�u�r�a�n�t�e� �e�s�t�e� �p�r�o�c�e�s�a�m�i�e�n�t�o� �p�u�e�d�e�n� �a�f�e�c�t�a�r� �a� �l�a� �c�o�m�p�o�s�i�c�i�ón� �y� �a�l� �v�a�l�o�r� �n�u�t�r�i�c�i�o�n�a�l� �d�e�l� �p�r�o�d�u�c�t�o�.� �L�a� �i�n�f�l�u�e�n�c�i�a� �d�e� �l�a� �f�e�r�m�e�n�t�a�c�i�ón� �a�n�o�r�m�a�l� �y� �t�r�a�t�a�m�i�e�n�t�o�s� �t�e�c�n�o�l�ó�g�i�c�o�s� �m�a�l� �r�e�a�l�i�z�a�d�a�s� �s�e� �e�x�a�m�i�nó� �a�q�u�í� �e�n� �t�é�r�m�i�n�o�s� �d�e� �l�a� �f�r�a�c�c�i�ó�n� �l�i�p�í�d�i�c�a� �d�e� �a�c�e�i�t�u�n�a�s� �d�e� �m�e�s�a�.� �E�n� �l�a�s� �a�c�e�i�t�u�n�a�s� �p�r�o�c�e�s�a�d�a�s� �m�e�d�i�a�n�t�e� �e�s�t�i�l�o� �g�r�i�e�g�o�,� �l�a� �b�a�j�a� �c�o�n�c�e�n�t�r�a�c�i�.�n� �d�e� �s�a�l�m�u�e�r�a� �p�e�r�m�i�t�e� �e�l� �c�r�e�c�i�m�i�e�n�t�o� �e�s�p�o�n�tá�n�e�o� �d�e� �m�i�c�r�o�f�l�o�r�a� �y� �l�a� �c�o�n�s�i�g�u�i�e�n�t�e� �a�p�a�r�i�c�i�ó�n� �d�e� �d�e�f�e�c�t�o�s� �o�r�g�a�n�o�l�é�p�t�i�c�o�s� �(‘�f�e�r�m�e�n�t�a�c�i�ó�n� �b�u�t�í�r�i�c�a� �y� �a�v�i�n�a�g�r�a�d�o’ )�.� �L�o�s� �c�u�l�t�i�v�a�r�e�s� �d�e� �‘K�a�l�a�m�a�t�a’� �y� ‘M�o�r�e�s�c�a’� �p�u�e�d�e�n� �p�r�o�d�u�c�i�r� �é�s�t�e�r�e�s� �m�e�t�í�l�i�c�o�s� �(�o�l�e�a�t�o� �y� �l�i�n�o�l�e�a�t�o�:� �5�5�3� �y� �4�5�0� �m�g·�k�g�-1� �d�e� �a�c�e�i�t�e�,� �r�e�s�p�e�c�t�i�v�a�me�n�t�e�)� �y� �é�s�t�e�r�e�s� �e�t�í�l�i�c�o�s� �(�o�l�e�a�t�o� �y� �l�i�n�o�l�e�a�t�o�:� �4�7�6�4� �y� �4�1�9�5�;� �p�a�l�m�i�t�a�t�o�:� �6�1�7� �y� �8�8�6� �m�g·k�g�-1�,� �r�e�s�p�e�c�t�i�v�a�m�e�n�t�e�)�.� �E�n� �l�a�s� �a�c�e�i�t�u�n�a�s� �p�r�o�c�e�s�a�d�a�s� �m�e�d�i�a�n�t�e� �e�s�t�i�l�o� �s�e�v�i�l�l�a�n�o�,� �l�a� �a�l�t�a� �c�o�n�c�e�n�t�r�a�c�ió�n� �d�e� �N�a�O�H� �i�n�f�l�u�y�e� �m�e�n�o�s� �e�n� �l�a� �c�o�m�p�o�s�i�c�ión� �d�e� �ác�i�d�o�s� �g�r�a�s�o�s�,� �p�e�r�o� �e�s� �d�i�fíc�i�l� �d�e� �e�l�i�m�i�n�a�r� �e�l� �d�e�f�e�c�t�o� �j�a�b�ón�.� �L�o�s� �c�u�l�t�i�v�a�r�e�s� �d�e� �‘G�i�a�r�r�a�f�f�a’� y� �‘N�o�c�e�l�l�a�r�a� �d�e�l� �B�e�l�i�c�e’ �p�r�o�d�u�c�e�n� �s�o�l�a�m�e�n�t�e� é�s�t�e�r�e�s� �e�t�éíl�i�c�o�s� �(�o�l�e�a�t�o� �y� �l�i�n�o�l�e�a�t�o�:� �2�2�2� �y� �2�8�9� �m�g�·�k�g-1� �d�e� �a�c�e�i�t�e�,� �r�e�s�p�e�c�t�i�v�a�m�e�n�t�e�)�.� �C�o�n� �e�s�t�a� �p�r�o�d�u�c�c�ión� �d�e� �é�s�t�e�r�e�s� �e�t�í�l�i�c�o�s� �y� �m�e�t�í�l�i�c�o�s� �d�e� �l�o�s� �á�c�i�d�o�s� �g�r�a�s�o�s� �p�r�i�n�c�i�p�a�l�e�s� �e�n� �l�a�s� �f�r�a�c�c�i�o�n�e�s� �l�i�pí�d�i�c�a�s� �d�e� �l�a�s� �a�c�e�i�t�u�n�a�s� �d�e� �m�e�s�a�,� �l�o�s� �mét�o�d�o�s� �q�u�e� �p�r�o�p�o�r�c�i�o�n�a�n� �t�r�a�t�a�m�i�e�n�t�o�s� �u�n�i�c�a�m�e�n�t�e� �b�i�o�ló�g�i�c�o�s� �(�e�s� �d�e�c�i�r�,� �d�e� �e�s�t�i�l�o� �g�r�i�e�g�o�)� �p�l�a�n�t�e�a�n� �má�s� �r�i�e�s�g�o�s� �q�u�e� �l�o�s� �m�ét�o�d�o�s� �q�u�e� �p�r�o�p�o�r�c�i�o�n�a�n� �t�r�a�t�a�m�i�e�n�t�o�s� �q�uí�m�i�c�o�s� �(�e�s� �d�e�c�i�r�,� �d�e� �e�s�t�i�l�o� �s�e�v�i�l�l�a�n�o�)�

    Assessment of the energetic potential by hazelnuts pruning in Viterbo’s area

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    In this work the amount of biomass available by the hazelnuts pruning in the province of Viterbo was investigated. At present, the pruning's residues are destroyed by farmers directly in the field, at the end of the pruning; in this way a large quantity of biomass, represented by hazelnut's prunings, is lost; the residues obtained from the hazelnut's pruning, are an important source of biomass that could be used for thermal energy production. The aim of this work is to realize a map with the estimated energy potential from hazelnut pruning biomass, in the province of Viterbo. In the first phase the amount of biomass obtained from a hectare of hazelnut's cultivationwas estimated:sampling were carried out in some municipalities of Viterbo while hazelnut pruning was taking place, from January to March.In the field, biomass was weighed and some pieces of wood were collected for laboratory analysis; in particular humidity of biomass, low calorific value, ashand the content of carbon (C), hydrogen (H) and nitrogen (N) were determined. In the calculation of the biomass were considered the age of the plants and the number of plants per hectare. The results show that the amount of biomass obtained from pruning of hazelnuts varies with the age of plants, but even more so by the number of plants per hectare. The average value of biomass obtained from pruning of a hectare of land is just under 0,9 t. Knowing the net calorific value of the hazelnut wood and the number of hectares cultivated for each municipality, a map of thermal potential energy has been realized

    The heat stress for workers employed in a dairy farm

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    The Italian dairy production is characterized by high heterogeneity. The typology quantitatively more important (80% of national production) is represented by cow’s milk cheeses (Grana Padano cheese, string cheese, Parmesan cheese, etc.), while the cheese from buffalo’s milk (especially string cheese such as mozzarella) and cheese from sheep and goats represents respectively 4% and 8% of the national dairy production, and are linked to specific regional contexts. Some phases of the cycle of milk processing occur at certain temperatures that are not comfortable for the workers also in relation to possible problems due to thermal shock. The aim of this study was to evaluate the risk of heat stress on workers operating in a dairy for processing of buffalo milk. The research was conducted at a dairy farm located in the province of Viterbo, Italy, during the spring-summer period. To carry out the research were detected major climatic parameters (air temperature, relative humidity, mean radiant temperature, air velocity) and the main parameters of the individual operators (clothing thermal insulation and the energy expenditure required from the work done by employees). Subsequently, main indices of heat stress assessment provided by the main technical standards were calculated. In particular have been calculated predicted mean vote and predicted percentage of dissatisfied in moderate thermal environments (environments in which the objective, in the design and management phases, is to achieve the thermal comfort), provided by the UNI EN ISO 7730 and the wet bulb globe temperature in severe hot environments (environments in which you must protect the health of workers) required by UNI EN ISO 27243. The results show some phases of risk from heat stress especially during times of test in which the internal air temperature exceeds the threshold of 30°C and possible solutions to improve the safety of the operators

    Social networks and labour productivity in Europe: An empirical investigation

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    This paper uses firm-level data recorded in the AMADEUS database to investigate the distribution of labour productivity in different European countries. We find that the upper tail of the empirical productivity distributions follows a decaying power-law, whose exponent α\alpha is obtained by a semi-parametric estimation technique recently developed by Clementi et al. (2006). The emergence of "fat tails" in productivity distribution has already been detected in Di Matteo et al. (2005) and explained by means of a model of social network. Here we show that this model is tested on a broader sample of countries having different patterns of social network structure. These different social attitudes, measured using a social capital indicator, reflect in the power-law exponent estimates, verifying in this way the existence of linkages among firms' productivity performance and social network.Comment: LaTeX2e; 18 pages with 3 figures; Journal of Economic Interaction and Coordination, in pres

    Influencia de un cosechado nocturno de aceitunas en “Salento” sobre la calidad del aceite de oliva virgen extra

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    In southern Italy, some olive cultivars such as ‘Ogliarola Salentina’ ripen when the day temperature is still high, at up to 28 to 30 °C. This can affect both the oil quality and the expression of its valuable characteristics. In addition, it increases the risk of undesirable fermentation that can generate off-flavors. In the present study, nocturnal olive harvesting was carried out to determine the influence that temperature can have on the characteristics of the extra virgin olive oil, and particularly on the volatile and oxidative compounds. The data obtained are encouraging: the lower temperatures that occur during the night appear to have a particular and positive impact on the organoleptic characteristics of the extra virgin olive oil produced, with enhanced formation of the volatile compounds that contribute to the ‘green’ notes of the flavor. In areas where daytime temperatures are very high, the nocturnal harvesting of olives at the correct stage of maturity therefore represents a good agronomic practice for the production of oils with high organoleptic and nutritional merit.En el sur de Italia, algunas variedades de olivo maduran cuando la temperatura del día sigue siendo alta, hasta 28 °C a 30 °C. Esto puede perjudicar la calidad del aceite y a la expresión de sus valiosas características, y aumenta el riesgo de fermentación indeseable que puede generar malos sabores. En el presente estudio, la cosecha nocturna de aceitunas se llevó a cabo para determinar la influencia que la temperatura puede tener sobre las características del aceite de oliva virgen extra, y en particular sobre los compuestos volátiles y los compuestos relacionados con la oxidación. Los datos obtenidos son alentadores: las temperaturas más bajas que se producen durante la noche parecen tener un impacto positivo en las características organolépticas del aceite de oliva virgen extra producido, con una mejora de la formación de los compuestos volátiles que contribuyen a las notas “verdes” del sabor. En las zonas donde las temperaturas diurnas son muy altas, la cosecha nocturna de aceitunas, representa, por tanto, una buena práctica agronómica para la producción de aceites con grandes ventajas organoléptica y nutritivas

    Tendon biomimetic 3D scaffold enhance amniotic epithelial stem cells biological potential

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    Tendon tissue engineering represents an emerging field whose aim focuses on the design of 3D tendon biomimetic scaffolds that should ideally combine adequate physical, mechanical, biological and functional properties of the native tissue. In this research, it was designed a bundle tendon-like PLGA 3D scaffold with highly aligned fibers on which the structure and mechanical properties were evaluated. Moreover, it was assessed scaffold’s teno-differentiative and immuno-inductive ability on amniotic epithelial stem cells (AECs). The fabricated PLGA 3D scaffolds mimic macroscopically and microscopically the structure of native tendon tissue and its biomechanical properties. Biologically, AECs seeded on the fabricated 3D scaffolds acquired a spindle tenocyte-like morphology after just 24h compared to the AECs cultured on petri dishes (CTR) which maintained their cobblestone morphology. The phenotypic change of the engineered AECs was also confirmed by visualizing TNMD protein expression, a mature tendon marker, within their cytoplasm and supported by the analysis of tendon-related genes (SCX, COL1, and TNMD) that were significantly upregulated at 7-day culture, while no TNMD protein expression or significant increase in tendon-related genes was found in CTR cells. Moreover, the 3D construct induced on AECs an upregulation of IL-10, an anti-inflammatory cytokine, maintaining basal levels of IL-12, a pro-inflammatory cytokine, showing a favorable IL10/IL12 ratio. In conclusion, the fabricated PLGA 3D scaffolds are tendon biomimetic in terms of ultrastructure and biomechanics, making them also suitable for surgical purposes. Moreover, these constructs revealed a high teno- and immuno-inductive potential on AECs and thus represent potential candidates for tendon regeneration
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