306 research outputs found

    Mars Express measurements of surface albedo changes over 2004 - 2010

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    The pervasive Mars dust is continually transported between the surface and the atmosphere. When on the surface, dust increases the albedo of darker underlying rocks and regolith, which modifies climate energy balance and must be quantified. Remote observation of surface albedo absolute value and albedo change is however complicated by dust itself when lifted in the atmosphere. Here we present a method to calculate and map the bolometric solar hemispherical albedo of the Martian surface using the 2004 - 2010 OMEGA imaging spectrometer dataset. This method takes into account aerosols radiative transfer, surface photometry, and instrumental issues such as registration differences between visible and near-IR detectors. Resulting albedos are on average 17% higher than previous estimates for bright surfaces while similar for dark surfaces. We observed that surface albedo changes occur mostly during the storm season due to isolated events. The main variations are observed during the 2007 global dust storm and during the following year. A wide variety of change timings are detected such as dust deposited and then cleaned over a Martian year, areas modified only during successive global dust storms, and perennial changes over decades. Both similarities and differences with previous global dust storms are observed. While an optically thin layer of bright dust is involved in most changes, this coating turns out to be sufficient to mask underlying mineralogical near-IR spectral signatures. Overall, changes result from apparently erratic events; however, a cyclic evolution emerges for some (but not all) areas over long timescales

    Achiral dye/surfactant heteroaggregates for chiral sensing of phosphocholines

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    An investigation, based on absorption and circular dichroism spectroscopy, was carried out on assemblies formed in water upon the interaction of heteroaggregates, composed of dyes (Congo Red or Evans Blue) and cetyltrimethylammonium bromide (CTAB), with four enantiopure phopshocholines (DMPC, DPPC, DOPC, and POPC) characterized by the same po- lar head and different hydrophobic tails. The results show that the nature of the lipid as well as the concentration ratios influence sensitively the absorption and chiroptical properties of the su- pramolecular structure. Intriguingly, the transfer of chirality from the lipid to the assembly may be triggered or not, depending on the nature of the lipid hydrophobic chain. These findings con- firm the fundamental role of hydrophobic interactions in the transcription of chirality from mol- ecules to complex architectures

    Metabiotic effects of Fusarium spp. on Escherichia coli O157:H7 and Listeria monocytogenes on raw portioned tomatoes.

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    The metabiotic effects of Fusarium proliferatum, F. avenaceum, and F. oxysporum on Escherichia coli O157:H7 and Listeria monocytogenes in fresh tomatoes were investigated. Tomatoes were preinoculated with the molds and incubated at 15 degrees C for 7 days; then they were inoculated separately with the pathogens, packaged in air and modified atmosphere (5% O2, 30% CO2, and 65% N2), and stored at 4, 8, and 12 degrees C for 9 days. The cell loads of pathogens and lactic acid bacteria and the pH were evaluated periodically. The data were modeled through some different mathematical models to assess the shoulder length, i.e., the time before the beginning of the exponential death phase, the 1-log reduction time (s), and the pathogen death time (deltastand). The preinoculation of tomatoes with the molds enhanced the survival of E. coli O157:H7 by prolonging shoulder length and 8 parameters; this effect, however, was not observed for L. monocytogenes. pH values did not undergo significant changes within the storage time, and the lactic acid bacteria increased from 5 to 7 log CFU/g, without significant differences among the storage temperatures or the packaging atmospheres. The results of this research showed that the use of fresh tomatoes colonized by fusaria (even if the contamination is not visible) could increase significantly the risk of outbreaks due to some pathogens that could be on the surface of fruits and vegetables as a result of cross-contamination at home or incorrect postharvest operations

    Mycochemical study of polysaccharides from the edible mushroom Cortinarius caperatus (Gypsy mushroom)

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    Among basidiomycete molecules, cell wall polysaccharides have been recognized as a major class of bioactive constituents. [1] They are safe molecules and they have a wide spectrum of biological activities, such as immunostimulatory and antioxidant, therefore they possess a prominent role in health benefits coming from mushroom consumption. These properties make mushroom polysaccharides potential candidates for nutraceutical applications and bioactive ingredients production. [2] Fractionation of the hot aqueous extract of Cortinarius caperatus led to isolation of two fractions characterized by spectroscopic analyses (1H-NMR, 13C-NMR, DEPT, 1H-1H COSY, DQCOSY, TOCSY, HSQC, HMBC and HMQC), mass spectrometry (EI-MS, ESI-MS), infrared spectroscopy (FT-IR), chemical reactions of hydrolysis and derivatization followed by GC and HPLC analyses. [3] This mycochemical study revealed a water-soluble fraction characterized as a \u3b2-(1\uf0e06)-D-glucan, whose presence inside C. caperatus has never, to the best of our knowledge, been reported before. Moreover, a water insoluble fraction purified has been characterized as a branched \uf061, (1\u21926) glucan which structure is assumed to be: [\u21926)-\u3b2-D-Glcp(1\u21926)]4-\u3b1-D-Glcp(1\u21924)-\u3b2-D-Glcp(1\u2192 6 \u2191 1 \u3b1-D-Glcp The antioxidant activity of the soluble polysaccharide fraction has been evaluated as radical-scavenging activity with the DPPH test, the \u3b2-(1\uf0e06)-D-glucan showed significative antioxidant activity

    Modelling the Survival of Escherichia coli O157:H7 on Raw Portioned Tomatoes, Inoculated with Aspergillus fumigatus and Emericella nidulans

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    The metabiotic interactions occurring among two fungi (Aspergillus fumigatus and Emericella nidulans) and Escherichia coli O157:H7 on raw portioned tomatoes were studied. Tomatoes, preinoculated with the moulds and inoculated with the pathogen, were packaged in air and stored at 4, 8 and 12∘C for 9 days; pathogen cell number and pH were monitored throughout the storage and the data were modeled using three different equations (Geeraerd, Weibull, and modified Weibull), to assess the shoulder length, the 1-log reduction time, and the death time. Both A. fumigatus and E. nidulans increased the survival of E. coli O157:H7 through the prolongation of the shoulder length; in contrast, the death time was significantly increased. The results of this paper suggested that the metabiotic interactions aspergilli/E. coli O 157:H7 could be of public concern, as the consumption of tomatoes (or other fruits and vegetables) contaminated both by the moulds and the pathogen is a possible scenario

    Extended phenotype of an mreB-like mutant in Azospirillum brasilense

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    Tn5mutagenesis was used to generate anAzospirillum brasilenseSPF94 mutant. Genetic analysis of this mutant revealed that a homologue of themreBgene, which controls cell shape inBacillus subtilisandEscherichia coli, was inactivated. The cell-surface properties of the mutant were different from those of the parental strain. The mutant colonies were highly fluorescent when grown on plates containing Calcofluor White. Light and electron microscopy revealed that the mutant cells were round and had thicker capsules than the spiral parental strain. The mutants contained up to ten times more capsule protein than the parental strain, but lacked a 40 kDa protein that is abundant in the parental strain. The phenotype of the isolated mutant resembled that of the cyst-like differentiated forms ofAzospirillum, suggesting that themreBhomologue could be involved in differentiation

    The Comparative Exploration of the Ice Giant Planets with Twin Spacecraft: Unveiling the History of our Solar System

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    In the course of the selection of the scientific themes for the second and third L-class missions of the Cosmic Vision 2015-2025 program of the European Space Agency, the exploration of the ice giant planets Uranus and Neptune was defined "a timely milestone, fully appropriate for an L class mission". Among the proposed scientific themes, we presented the scientific case of exploring both planets and their satellites in the framework of a single L-class mission and proposed a mission scenario that could allow to achieve this result. In this work we present an updated and more complete discussion of the scientific rationale and of the mission concept for a comparative exploration of the ice giant planets Uranus and Neptune and of their satellite systems with twin spacecraft. The first goal of comparatively studying these two similar yet extremely different systems is to shed new light on the ancient past of the Solar System and on the processes that shaped its formation and evolution. This, in turn, would reveal whether the Solar System and the very diverse extrasolar systems discovered so far all share a common origin or if different environments and mechanisms were responsible for their formation. A space mission to the ice giants would also open up the possibility to use Uranus and Neptune as templates in the study of one of the most abundant type of extrasolar planets in the galaxy. Finally, such a mission would allow a detailed study of the interplanetary and gravitational environments at a range of distances from the Sun poorly covered by direct exploration, improving the constraints on the fundamental theories of gravitation and on the behaviour of the solar wind and the interplanetary magnetic field.Comment: 29 pages, 4 figures; accepted for publication on the special issue "The outer Solar System X" of the journal Planetary and Space Science. This article presents an updated and expanded discussion of the white paper "The ODINUS Mission Concept" (arXiv:1402.2472) submitted in response to the ESA call for ideas for the scientific themes of the future L2 and L3 space mission

    Predictive analysis of maxillary canine impaction through sella turcica bridging, ponticulus posticus calcification, and lateral incisor anomalies: a retrospective observational study

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    Maxillary canine impaction is an increasing dental anomaly and is often related to other dento-skeletal anomalies. The aim of this work is to support the clinician in evaluating the relationship between a displaced maxillary canine and clinical (the features of lateral incisors)/skeletal (ponticulus posticus and sella turcica bridging) anomalies through orthopanoramic radiographs, lateral cephalograms, and plaster casts to identify the parameters that best predict maxillary canine impaction. A retrospective observational study was carried out on the analysis of the medical records, radiographic findings (panoramic radiographs and lateral cephalograms), and plaster casts of 203 orthodontic patients divided into a case group, with at least one impacted maxillary canine, and a control group, without an impaction. A chi-square test and logistic regression analysis were used to analyze the data. A statistically significant association was found between the impaction of the maxillary canine and the female sex, the bridging of the sella turcica, the ponticulus posticus calcification, and the anomaly of the lateral incisor; a logistic regression revealed that these significant variables were found to be positive predictors of impacted maxillary canines, particularly in reference to the impaction in the palatal area. Finding one of these clinical and radiographic elements can represent a predictive sign of the possible impaction of the maxillary canine

    Oxygen investigation in the Galileian satellites using AFOSC

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    Spectroscopy in the visible range of the Galilean satellites is a suitable way to investigate the surface properties of these objects. In recent years, several species, like O_2, O_3, and SO_2, have been detected on the surfaces of these satellites, which were thought to be completely covered only by water ice. The recent detection of the O_2 absorption bands in the Ganymede trailing face \citep{spencer_1995} led to laboratory experiments in order to better constraint the O_2 phases trapped in the water ice surface \citep{vidal_1997}. The same features were observed also on Europa and Callisto surfaces \citep{spencer_2002}, although a better investigation of their properties and their variability with time is still not fully addressed. We proposed ground-based observations with the AFOSC instrument on the 1.8-m telescope in Asiago, to investigate the Galilean satellites? surface properties, focusing both on the leading and trailing faces of the satellites. We used the Volume Phase Holographic grism covering the spectral range 400-1000 nm, with a spectral resolution of about 5000. In this work, we show results of the observations acquired in November 2014, focusing on the leading faces of the satellites. Data were treated using standard methods of data reduction. Further observations with the same setup, scheduled for February 2015 to observe the trailing face of the Galileian satellites, will complement the program. These observations are in preparation to the future science we will be able to perform with the MAJIS spectrometer on the European JUICE mission
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