Un estudio sobre las nociones de conservación que tienen estudiantes universitarios

En educación en ciencias, la idea de conservación y los principios asociados presentan dificultades en el aprendizaje. La idea de conservación es central en ciencias, en particular en Física, porque está implicada en principios fundamentales, los cuales resultan útiles para describir y predecir fenómenos. En este trabajo, se propone estudiar, en forma exploratoria, las ideas que tienen los estudiantes universitarios de primer año de Ingeniería, sobre el concepto de conservación. Se diseñó un cuestionario con preguntas abiertas y preguntas cerradas con justificación. Los registros se analizaron a partir de categorías emergentes y categorías encontradas en investigaciones anteriores. Los resultados preliminares muestran que la idea de conservación se asocia a “algo constante”, “inicial igual a final”; también se observa el uso del tiempo como recurso explicativo

Improvement of raw milk cheese hygiene through the selection of starter and non-starter lactic acid bacteria: The successful case of pdo pecorino siciliano cheese

This review article focuses on the technological aspects and microbiological critical points of pressed-cooked cheeses processed from raw ewe’s milk without the inoculation of starter cultures, in particular “Pecorino” cheese typology produced in Italy. After showing the composition of the biofilms adhering to the surface of the traditional dairy equipment (mainly wooden vat used to collect milk) and the microbiological characteristics of PDO Pecorino Siciliano cheese manufactured throughout Sicily, this cheese is taken as a case study to develop a strategy to improve its hygienic and safety characteristics. Basically, the natural lactic acid bacterial populations of fresh and ripened cheeses were characterized to select an autochthonous starter and non-starter cultures to stabilize the microbial community of PDO Pecorino Siciliano cheese. These bacteria were applied at a small scale level to prove their in situ efficacy, and finally introduced within the consortium for protection and promotion of this cheese to disseminate their performances to all dairy factories. The innovation in PDO Pecorino Siciliano cheese production was proven to be respectful of the traditional protocol, the final cheeses preserved their typicality, and the general cheese safety was improved. An overview of the future research prospects is also reported

Use of weaning concentrate in the feeding suckling kids: effects on meat quality

The effect of a feeding supplementation with starter concentrate on “Capretto” meat production and its qualitative characteristics was investigated. The results showed that the effect of concentrate supplementation did not influence the slaughter weight, slaughter and dissection data, tissue composition and meat chemical composition of the pelvic limb. No differences were found for rheological characteristics of LD meat, except cohesiveness values, which were higher in the concentrate group kids

Thermo-treatment affects Quercus cerris L. wood properties and the antioxidant activity and chemical composition of its by-product extracts

Nowadays, there is an increasing interest on thermo-treatment and its effects on wood structure and extraction processes, connected to the wood use for industrial application and for its use as biorefinery. The present investigation aimed to provide the main changes on wood properties (mass loss, color variation and modulus of elasticity) and a comparative analysis of the antioxidant properties and GC–MS profile of the extracts from Turkey oak (Quercus cerris L.) wood. Untreated and thermo-treated wood (170 °C x 3 h) samples were compared. Thermo-treatment induced a mass loss (5.1%) in wood, a darkening of color surface (ΔE = 7.6) and a decrease of MOE (4.1%). Moreover samples were extracted using different techniques: maceration (ME), ultrasound assisted extraction (UAE) and accelerated solvent extraction (ASE). Extracts were tested to evaluate the content of polyphenols and flavonoids along with the in vitro antioxidant activity. Results showed that extracts obtained from thermo-treated wood reported the highest Relative Antioxidant Capacity Index and extraction techniques affected the value in the following rating: UAE > ME > ASE. Qualitative and quantitative measurements of chemical compounds were carried out by GC–MS system. Taking into account the thermo-treatment and extraction techniques, principal component analysis (PCA) was performed also in order to evaluate the relationships among principal chemical compounds. According to results obtained, thermo-treatment and extraction technique had a determinant role in the antioxidant efficiency and, consequently, on the potential application of extracts

The quality of Valle del Belice sheep’s milk and cheese produced in the hot summer season in Sicily

In response to the growing consumer demand for fresh cheese in summer, this investigation was aimed to evaluate the chemical and microbiological characteristics of sheep’s milk and cheese produced in Sicily in the hot summer months. A total of 810 bulk milk samples collected from 17 farms rearing ewes of the Valle del Belice breed were analysed for chemical composition, somatic cell count, total bacterial count and clotting parameters. Samples (n=18) of Protected Designation of Origin Vastedda della valle del Belice cheese produced in six dairies were collected in summer, autumn and spring and analysed for chemical composition, microbiological profile and fatty acid (FA) composition. Univariate and multivariate analyses were performed to assess variations by season. Sheep’s milk produced in the summer had higher fat and casein contents, less lactose and urea and slightly higher total bacterial count and, similar to milk produced in winter, had a weaker clotting ability. Vastedda cheese produced in spring had less thermophilic lactococci and a high rumenic acid content. Cheese produced in summer had more fat; less saturated FA; and more linoleic acid, monounsaturated FA and omega-3 polyunsaturated FA. A dual approach to data analysis revealed a strong influence of production season on bulk milk and Vastedda cheese characteristics due to climate conditions and ewes’ feeding regimen. Although this study provides evidence of the good nutritional properties of summer sheep’s cheese, management and feeding strategies could aim to further improve the quality of milk and cheese produced in the summer months

A BIM Template for Construction Site Planning

Building Information Modelling is gradually becoming the standard method for building design all over the world. Its rapid development is visible not only in the many researches carried on it but also in the several standards released in different countries. The spread of the method implied continuous software improvements with the aim to comply as much as possible different design needs. Nevertheless, an insufficiency of tools specifically developed for construction site planning is still detectable among BIM panorama. The principal aim of the presented research is then to develop BIM use for making more efficient construction site design. Having defined, in an early report, the structure and the contents of the postulated Construction Site Information Model, the research goes on by customizing the available tools in order to fit the needs of a construction site designer. One of these tools is a predetermined template, useful as a starting point for the design, as it is for other design disciplines. The aim is to have at disposal, since the beginning of the project, a model completed of a series of elements, parameters, visualization tools and many other issues able to satisfy the needs of construction site design in term of information contents, level of detail and model efficiency. A step-by-step procedure is also provided to assure the correct use and guarantee the completeness of the model. In particular the research steps has been the following: (i) analysis of some software to evaluate the chances of customizing templates; (ii) creation of the template according to the defined contents and aims of the Construction Site Model; (iii) test and improvement of the tool in a project simulator specifically created for the purpose; (iv) practice in real case study and evaluation about its operation. The case study permits to evaluate how this tool make more efficient site designer task in term of time spent and mistakes avoided

factors associated with milk urea concentrations in girgentana goats

A total of 1,481 milk samples of 166 Girgentana goats, taken along the entire lactation, were utilised to evaluate the effect of non nutritional factors on milk urea (MU). Parity, stage of lactation and month of sampling significantly influenced MU, while no effect was found for born kids number. The first kidding goats produced lower MU than multiparous goats. Trend of MU was similar to milk production course with a peak found at 60 DIM. The different MU levels between several months of production are often linked to pasture chemical variations

Impiego di batteri lattici autoctoni per il miglioramento igienico-sanitario del Pecorino Siciliano DOP

Il Pecorino Siciliano DOP \ue8 considerato il pi\uf9 antico formaggio prodotto in Sicilia e, probabilmente, d\u2019Europa. Le citazioni storiche sulla sua antica origine risalgono al IX secolo a.C. in uno dei passi pi\uf9 famosi dell\u2019odissea di Omero, quando Ulisse incontra Polifemo. In seguito, anche Aristotele e Plinio esaltano il gusto unico di questo formaggio. In particolare, proprio Plinio, nella sua opera \u201cNaturalis Historia\u201d, redige una carta dei formaggi nella quale vengono citati, tra i migliori pecorini,quelli provenienti da Agrigento. Fra le caratteristiche peculiari del Pecorino Siciliano DOP vanno annoverati il sapore leggermente piccante e l\u2019incantevole profumo di pascolo. Il Pecorino Siciliano DOP \ue8 un formaggio a pasta dura, semicotto, prodotto con latte intero crudo di pecora. L\u2019areale di produzione si estende su tutta la regione Sicilia. La forma \ue8 cilindrica a facce piane o lievemente concave, pesa dai 4 ai 12 kg, lo scalzo \ue8 di 10-18 cm. La crosta \ue8 bianca-giallognola,con la superficie rugosa per la modellatura lasciata dal canestro in giunco dove avviene la formatura, spesso viene cappata con olio. La pasta \ue8 compatta, di colore bianco o giallo paglierino, con occhiatura scarsa. Il sapore \ue8 piccante e caratteristico, l\u2019aroma \ue8 intenso. La stagionatura minima prevista dal disciplinare \ue8 di 4 mesi. Il Pecorino Siciliano ha acquisito la certificazione DO nel 1955 e la DOP nel 1996 con regolamento CE n. 1107/96 della Commissione del 12 giugno 1996 (Gazzetta Ufficiale Comunit\ue0 Europea L 148 del 21/6/1996). Attualmente, le attivit\ue0 di promozione, valorizzazione e vigilanza sono affidate al Consorzio di tutela del Pecorino Siciliano DOP, che \ue8 stato riconosciuto dal ministero delle Politiche agricole, alimentari e forestali (Mi- Paaf) dal 2005 a oggi. L\u2019elevata eterogeneit\ue0 del prodotto osservata nelle forme presenti sul mercato \ue8 dovuta sia ai metodi di produzione artigianali sia al vecchissimo disciplinare di produzione, risalente al 1956. Ci\uf2 ha indotto il consorzio di tutela a intraprendere una proficua collaborazione tecnico-scientifica con l\u2019Universit\ue0 degli Studi di Palermo prima e l\u2019Istituto Zooprofilattico Sperimentale della Sicilia, il Corfilac e l\u2019Universit\ue0 di Catania successivamente, con l\u2019obiettivo di migliorare la qualit\ue0 igienico-sanitaria del formaggio Pecorino Siciliano DOP e ridurre l\u2019eccessiva variabilit\ue0 qualitativa fra le forme ottenute da differenti caseificazioni

An agent-based model to rural-urban migration analysis

In this paper we analyze the rural-urban migration phenomena as it is usually observed in economies which are in the early stages of industrialization. The analysis is conducted by means of a statistical mechanics approach which builds a computational agent-based model. Agents are placed on a lattice and the connections among them are described via an Ising like model. Simulations on this computational model show some emergent properties that are common in developing economies, such as a transitional dynamics characterized by continuous growth of urban population, followed by the equalization of expected wages between rural and urban sectors (Harris-Todaro equilibrium condition), urban concentration and increasing of per capita income.Comment: 16 pages, 9 figure