2,551 research outputs found

    A Review on Active Packaging: An Innovation in Food Packaging

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    Innovative packaging such as active packaging is the result of consumers demand for packaging that is more advanced and creative than what is currently offered. Active packaging aiming at extending shelf life or improving safety while maintaining quality is progressing towards the incorporation of natural active agents into more sustainable packaging materials. Depending on the requirements of packed food, the application of appropriate active packaging systems can significantly reduce food quality deterioration. Different active packaging systems are Oxygen scavengers, Carbon dioxide emitters and scavenger, Ethylene scavengers, Ethanol emitters, Moisture absorbers, Antimicrobial agents, Flavour/odour absorbers, Temperature-controlled packaging

    Isotopic and Microstructural Analyses of Opaque Mineral Assemblages and Their Alteration Products Hosted in a Refractory Inclusion

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    Calcium-aluminum-rich inclusions (CAIs) hosted in primitive meteorites are the oldest solids formed in the Solar System. Some CAIs contain metal nuggets that are complex assemblages of Fe-Ni alloys, along with rare ultra-refractory metals such as platinum group elements (PGEs), and their alteration products such as magnetite, sulfides, and phosphates. Three possible mechanisms proposed to explain the origin of these metal nuggets include condensation in circumstellar settings, condensation in the solar nebula within the CAI-forming region, or crystallization from immiscible metal-silicate melt. However, secondary alteration processes may have also affected some of these assemblages. Additionally, similar metal assemblages observed in chondrules and chondritic matrix indicate that all of these metal nuggets could share common high-temperature origins. These metal assemblages record early Solar System conditions that are reflected in their distinctive chemical composition, mineralogy and microstructures. Here we report a detailed mineralogical, microstructural and oxygen isotopic study of one such metal assemblage hosted in a CAI to understand the physical and chemical settings in which it formed

    Oxygen Isotopic Imaging of Refractory Inclusions from the Miller Range (MIL) 090019 CO3 Chondrite: A Perovskite Perspective

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    Calcium-Aluminum-rich Inclusions (CAIs) in primitive meteorites are the first solids to condense in the Solar System. The oxygen isotopic compositions recorded in various mineral components of CAIs provide clues about their origins and post-formation histories, recording processes such as condensation, melting, nebular alteration, and fluidrock reactions on the parent body. MIL 090019 is similar to some rare carbonaceous chondrites such as Acfer 094, DOM 08004/6 and ALH 77303 that contain high abundances of a variety of refractory inclusions. This provides an opportunity to study the oxygen isotopic record of different types of refractory inclusions within the same meteorite. We analyzed CAIs specifically targeting primary minerals that are direct nebular condensates, such as corundum and perovskite, with the goal of gaining insights into the O isotopic composition of the nebular gas(es) from which these CAIs condensed. As MIL 090019 is a classified as CO3.1, it shows some signs of thermal metamorphism, compared to the more primitive CO3 meteorites (e.g., DOM 08004/06). A second goal of this study is to search for evidence of nebular processes in phases such as perovskite and melilite that are susceptible to parent body alteration to varying degrees. We analyzed the oxygen isotopic compositions of various CAIs from the MIL 090019 CO3 carbonaceous chondrite by ion imaging using the NanoSIMS 50L (Nano Secondary Ion Mass Spectrometer) at JSC following methods described in. An advantage of ion imaging over traditional spot analyses is that it provides spatial context to the oxygen isotopic data. This work builds on previously reported oxygen isotopic composition of two other CAIs (CAI-44 and CAI-E2) from the same meteorite thin section

    Expérience de pathologie comparée entre bovins Zébus et Ndama soumis à l'infection naturelle par des trypanosomes pathogènes

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    Les auteurs ont étudié l'évolution des trypanosomoses à T. vivax et T. congolense sur des zébus et Ndama n'ayant jamais hébergé ces parasites après les avoir exposés à l'infestation naturelle dans une région riche en Glossina morsitans submorsitans et G. palpalis gambiensis. Ils décrivent, de façon comparative, l'évolution des affections ainsi provoquées et les lésions observées, avec comme conclusion essentielle que si les zébus sont très sensibles à l'infection trypanosomienne, les Ndama qui n'ont jamais été, au préalable, en contact avec des glossines infestées le sont aussi, à un certain degré. Certains Ndama présentent une résistance remarquable et ces animaux méritent une étude immunologique très poussée ainsi que des études génétiques car de tels sujets peuvent être retenus dans la sélection ou le croisement pour créer des souches naturellement et totalement trypano-résistante

    Higher excitations of ω\omega and ϕ\phi in dilepton spectra

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    We consider lepton pair production via two-hadron annihilation through various isoscalar vector mesons within hot, baryon-free matter. This is tantamount to constructing effective form factors which we model using a vector-meson-dominance approach and compare with experiment. In particular, we consider the reactions πρe+e\pi\rho\to e^+e^- and KˉK(892)\bar K K^{*}(892) + c.c. e+e\to e^+e^-. We find that ω(1390)\omega(1390) and ϕ(1680)\phi(1680) are visible in the mass spectrum for the thermal production rate above the π+πe+e\pi^{+}\pi^{-} \to e^+e^- tail and even above the πa1e+e\pi a_{1}\to e^+e^- results---both of which were considered important in their respective mass regions.Comment: RevTeX, 9 pages, 6 (uuencoded) figures; to appear in Phys. Rev

    A tracking algorithm for the stable spin polarization field in storage rings using stroboscopic averaging

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    Polarized protons have never been accelerated to more than about 2525GeV. To achieve polarized proton beams in RHIC (250GeV), HERA (820GeV), and the TEVATRON (900GeV), ideas and techniques new to accelerator physics are needed. In this publication we will stress an important aspect of very high energy polarized proton beams, namely the fact that the equilibrium polarization direction can vary substantially across the beam in the interaction region of a high energy experiment when no countermeasure is taken. Such a divergence of the polarization direction would not only diminish the average polarization available to the particle physics experiment, but it would also make the polarization involved in each collision analyzed in a detector strongly dependent on the phase space position of the interacting particle. In order to analyze and compensate this effect, methods for computing the equilibrium polarization direction are needed. In this paper we introduce the method of stroboscopic averaging, which computes this direction in a very efficient way. Since only tracking data is needed, our method can be implemented easily in existing spin tracking programs. Several examples demonstrate the importance of the spin divergence and the applicability of stroboscopic averaging.Comment: 39 page
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