323,853 research outputs found
Biohydrogen production from food waste in batch and semi-continuous conditions: evaluation of a two-phase approach with digestate recirculation for pH control
No full textThe research investigated the production of Biohythane in a two-phase anaerobic digestion process treating food waste as substrate. Preliminary batch assays were carried out at initial organic loadings of 15, 20, 25 and 30 kg TVS m?3, in stirred 1.5-l reactors at 55 °C. The results showed all hydrogen was produced within the first 24 h after feeding and the highest load tested gave the maximum hydrogen production (0.047 m3 H2 kg?1VS, H2 30%). Similar loadings were then tested in a two-phase system. Hydraulic retention times of 3 and 12 days were applied to the first and second reactor respectively. In order to keep the pH at ?5.5, either supernatant or whole digestate from the methanogenic reactor was recirculated to the first phase. Results showed that hydrogen was produced (0.117 Nm3 kg?1 VS, 47.7%) when recirculating whole digestate with an organic loading rate of 20 kg TVS m?3 day?1
Hydrocarboalkoxylation of N-vinylphtalimide catalyzed by palladium complexes
No full textThe hydrocarboalkoxylation of N-vinylphthalimide catalyzed by palladium tertiary phosphine complexes occurs with high selectivity towards the linear isomer when the alcohol is used also as the solvent but towards the branched isomer in the presence of an additional solvent. When triphenylphosphine is employed as the ligand, the yield and the regioselectivity towards the branched isomer increase with increasing pco or decreasing concentration of the phosphine. Reaction in the presence of molecular hydrogen leads to higher yields, with minor changes in regioselectivity. High regioselectivities towards either the linear or the branched isomer are observed also in the presence of chiral di- or mono-phosphines, but the degree of asymmetric induction is very low
Peripheral and total parenteral nutritions as strongest risk factors for nosocomial candidemia among elderly patients: a case-control study
No full texteP803
Abstract (eposter session)
Peripheral and total parenteral nutritions as the strongest risk factors for nosocomial candidaemia
among elderly patients: a case-control study
R. Luzzati*, S. Cavinato, G. Granà, M. Giangreco, M. Deiana, S. Centonze, F. Barbone (Trieste, Verona, Udine,
IT)
Objectives: Although the highest rates of nosocomial candidemia occur at the extremes of age spectrum, few
data on elderly patients exist. We investigate characteristics and risk factors for candidemia in such patient
population. Methods: We analyzed all consecutive nosocomial candidemia episodes occurring from January
2008 to June 2011 in an Italian referral hospital. A case-control study to identify risk factors for candidemia
including comorbidities, invasive procedures, and medical therapies was performed. For each case, 2 controls
were randomly selected among other patients admitted to the same hospital, and individually matched by sex,
age, year and month of admission, ward, and duration of hospital admission. The statistical analysis was
conducted according to matched case-control methods. The adjusted odds ratio (OR) was calculated using
multiple conditional logistic regression. Results: We identified 145 episodes of candidemia occurring in 140
patients (67 females, 48%) with a median age of 80 years (IQR 69.0-85.5 years ). The overall incidence of
candidemia was 1.56 episodes per 10,000 patient-days per year. Ninety-three (67%) patients were hospitalized
in internal medicine units, 23 (16%) in surgery units, and 24 (17%) in intensive care units. Candida albicans (80
isolates) accounted for 55% of all candidemia episodes. From the multivariate logistic regression models which
also included terms for matching variables, candidemia remained statistically significantly associated with
duration > 7 days of both total [OR = 23.40; 95% confidence interval (CI): 3.81-143.59]and peripheral
parenteral nutrition [OR = 24.82; 95%CI: 6.23-98.82], central vascular catheter [OR = 5.61; 95%CI: 1.32-
23.82], and the following antibiotics for >= 2 days: glicopeptydes [OR = 6.23; 95%CI: 1.88-20.67],
aminoglycosides [OR = 2.75; 95%CI: 0.62-12.19], metronidazole [OR = 2.71; 95%CI: 0.80-9.17], and
antianaerobic betalactams [OR = 2.44; 95%CI: 1.00-5.94]. The 30-day crude mortality was 45.0% in
candidemia cases and 20.7% in controls. Conclusion: Our data show the incidence of candidemia to be high and
elderly patients admitted into internal medicine wards to be especially affected by that infection. The longer
durations of both total and peripheral parenteral nutritions were found to be the strongest risk factors for
candidemia. Prospective studies are warranted to show whether candidemia can be prevented by earlier
application of enteral feeding in elderly patients
Geometry and kinematic evolution of the central sector of the Simbruino-Ernica catena, Lazio, central Apennines
No full textThe Simbruini-Ernici Mts. are a NW-SE striking carbonatic range bounded by the Latina Valley to the SW, Roveto Valley to the NE and partially overthrusted to the NW, by the Umbro-Sabine domain, along the Olevano-Antrodoco line. The stratigraphic framework of the range is characterized by the typical Latium-Abruzzi Mesozoic carbonate platform sequence, over 3000 meters thick, followed by the transgressive Calcari a briozoi e litotamni unit (Middle Miocene). In Upper Tortonian times, the area is involved in the Upper Miocene terrigenous units of Marne a Orbulina and flysch. In the study area, the whole Mesozoic sequence outcrops from Upper Triassic to Upper Cretaceous, locally overlain by the middle Miocene limestones. The results of the structural analysis performed in the central portion of the Simbruini-Ernici Range are presented and discussed together with other new data. -from English summar
Some didactical suggestions for a deeper embedding of DC circuits into electromagnetism
No full textUndergraduate students often encounter great difficulties in understanding Ohm's law and electrical circuits. Considering the widespread students' beliefs and their common mistakes, as they come out from the literature and our teaching experience, we think that a relevant source of these problems comes from the fact that electrical circuits are generally treated separately from the other topics of electromagnetism, with poor reference to the circulation of the electric field. We present here a way to deal with electrical circuits that could help students to overcome their difficulties. In our approach, the electric field is the protagonist and the mathematical tool the students are asked to use is its circulation. In the light of the circulation of the electric field, the experimental Ohm's law is revisited, the concept of electromotive force is discussed and some suggestions to eliminate common misconceptions about the role of a battery in a circuit are presented
First- and second-generation valorisation of wastes and residues occurring in the food supply chain
No full textDespite the high potential to increase sustainability of food systems, wastes and by-products occurring in the food supply chain are currently only partially valorised at different value-added levels. First-generation valorisation strategies that aim at utilisation of complete material streams for production of animal feed, energy, compost and/or specific consumer applications are already widely implemented and experience further dissemination and/or development (e.g. biohydrogen/biohythane production) – either in the form of single processes or as part of cascade utilisations. Second-generation valorisation strategies comprise various forms of fractionised utilisation of material streams. They rely on integration of adapted recovery and conversion procedures for specific components in order to obtain sequentially different classes of products, e.g. fine chemicals, commodity products and biofuels. Such advanced strategies are particularly suitable for wastes and by-products occurring during industrial food processing. Valorisation of food by-products for functional food is an emerging trend
Dati preliminari sull’assetto geologico-strutturale del settore sud-occidentale della struttura simbruino-ernica
No full textAn educational path for the magnetic vector potential and its physical implications
No full textWe present an educational path for the magnetic vector potential A aimed at undergraduate students and pre-service physics teachers. Starting from the generalized Ampère–Laplace law, in the framework of a slowly varying timedependent field approximation, themagnetic vector potential is written in terms of its empirical references, i.e. the conduction currents. Therefore, once the currents are known, our approach allows for a clear and univocal physical determination of A, overcoming the mathematical indeterminacy due to the gauge transformations.We have no need to fix a gauge, since for slowly varying time-dependent electric and magnetic fields, the ‘natural’ gauge for A is the Coulomb one. We stress the difference between our approach and those usually presented in the literature. Finally, a physical interpretation of the magnetic vector potential is discussed and some examples of the calculation of A are analysed
Corrigendum: An educational path for the magnetic vector potential and its physical implications
No full textThis is a Corrigendum for the article 2013 Eur. J. Phys. 34 120
Vector potential at high school: a proposal for its introduction
No full textWe describe the motivations and purposes, together with an educational reconstruction, for the effective introduction of magnetic vector potential in high schools. Although addressed to high schools, most of the content of this paper can be usefully used in undergraduate teaching, especially in what concerns the physical meaning and the importance of the concept of vector potential. In fact, magnetic vector potential can highlight unifying ideas, clarify many aspects of electromagnetism and provide a natural link to the history of physics, so often useful in physics education. In our framework, it can also help students with poor mathematical ability to visualize electromagnetic phenomena and improve their understanding of the standard concepts of circulation and flux. Moreover, it is fundamental in treating-even just at a phenomenological level-several important aspects of modern physics and superconductivity, thus avoiding the presentation of modern physics in a discursive way only. We therefore strongly recommend dealing with the vector potential in the modern high school curriculum. Furthermore, we discuss the physical meaning of the vector potential and the gauge invariance and the necessity for an educational reconstruction of topics suitable for high schools. We then present a detailed approach, well embodied in a high school presentation of classical electromagnetism, which, starting from its empirical reference (the currents), introduces the vector potential in analogy with the scalar potential using examples, hints and physical motivations
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