CO2 Atmosphere (co2 + atmosphere)

Distribution by Scientific Domains


Selected Abstracts


Shelf Life and Microbial Quality of Fresh-cut Mango Cubes Stored in High CO2 Atmospheres

JOURNAL OF FOOD SCIENCE, Issue 1 2005
Jutatip Poubol
ABSTRACT: Fresh-cut,Carabao'and,Nam Dokmai'mango cubes were stored in air or in high CO2 atmospheres (3%, 5%, and 10%) at 5 °C and 13 °C. Freshly sliced,Carabao'mango cubes had a lower respiration rate and total bacterial count and higher L-ascorbic acid content and firmness than,Nam Dokmai'mango cubes. The shelf life of fresh-cut mango, based on browning discoloration and water-soaked appearance, was 6 d at 5 °C and 4 d at 13 °C for,Carabao'and 2 d at 5 °C and less than 1 d at 13 °C for,Nam Dokmai'. High CO2 atmospheres retarded the development of water-soaked,Carabao'cubes at 5 °C and 13 °C and,Nam Dokmai'cubes at 5 °C. Texture of,Carabao'cubes was enhanced by high CO2, but ethanol and L-ascorbic acid contents were not affected at 5 °C and 13 °C. Total bacterial count was lower in,Carabao'cubes than in,Nam Dokmai'cubes during storage at both temperatures, and a 10% CO2 only reduced the bacterial count on,Carabao'and,Nam Dokmai'cubes stored at 13 °C. Bacterial flora in,Nam Dokmai'mango cubes consisted mostly of Gram-negative rods assigned primarily to phytopathogenic bacteria such as Pantoea agglomerans and Burkholderia cepacia. The genera of bacteria isolated from cubes stored in 10% CO2 were similar to those from cubes on the initial day. [source]


Barium Non-Stoichiometry Role on the Properties of Ba1+xCe0.65Zr0.20Y0.15O3,, Proton Conductors for IT-SOFCs

FUEL CELLS, Issue 5 2008
S. Barison
Abstract Proton conducting perovskite oxides have been widely investigated because of their potential as electrolytes for intermediate temperature solid oxide fuel cells. Among them, BaCeO3 - based materials exhibit good proton conductivity under a humidified hydrogen-containing atmosphere, but rather poor chemical stability in CO2 atmosphere. The substitution with Zr for Ce improves the chemical stability but reduces proton conductivity due to difficulties in fabricating dense materials. In the present work, single phase nanostructured powders of Ba1+xCe0.65Zr0.20Y0.15O3,, (x,=,0, 0.05, 0.10) solid solutions have been prepared by a modified sol,gel Pechini method with the final aim of evaluating the role of barium on their chemical and electrical properties. A significant influence of barium excess on the preparation and on properties of these materials has been demonstrated. In fact, density measurements evidenced that a 5 or 10,mol% nominal barium excess sensibly favoured the sintering process. Impedance analyses of sintered pellets confirmed the necessity of barium excess in order to avoid the lowering of proton conductivity, which has been evidenced for samples having stoichiometric barium content. Moreover, an unforeseen increase in chemical stability in CO2 -containing atmosphere with the growth of the barium excess was detected by thermogravimetric analyses. [source]


Synthesis of Various LaMO3 Perovskites in Molten Carbonates

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2006
Toshikatsu Kojima
Lanthanum-containing perovskites, LaMO3 (M=Al, Sc, Cr, Mn, Fe, Co, Ni, Ga, and In), have been synthesized in molten carbonates from a mixture of lanthanum carbonate and an M-containing oxide or an acetate, or from a co-precipitation mixture of metal (M) and lanthanum. Metal aluminum, chromium, and iron, immersed in a mixture of molten (Li0.52Na0.48)2CO3 and lanthanum carbonate at 923 K, were covered, respectively, with LaAlO3, LaCrO3, and LaFeO3. Ceramic and single-crystal ,-Al2O3, immersed in molten (Li0.52Na0.48)2CO3 mixed with lanthanum carbonate, were also covered with LaAlO3. In situ X-ray diffractometry revealed that La2O2CO3 reacted with ,-LiAlO2 to yield LaAlO3; the reaction proceeded faster under N2 than under a CO2 atmosphere. [source]


Quality changes of treated fresh-cut tropical fruits in rigid modified atmosphere packaging containers

PACKAGING TECHNOLOGY AND SCIENCE, Issue 1 2007
Vanee Chonhenchob
Abstract There has been increasing demand for various fresh-cut tropical fruits. However, their short shelf-life has limited the market increase of this product. Quality changes (firmness, colour, total soluble solids (TSS), titratable acidity (TA), sensory quality and microbial safety) of fresh-cut mangoes, pineapples, melons and mixes of these fruits were evaluated. Chemical treatments to reduce browning, firmness loss and decay of fresh-cut tropical fruits were investigated. The most effective agents for fresh-cut mangoes, pineapples and melons were 0.1m ascorbic acid, 0.2m ascorbic acid and 0.2m ascorbic acid + 0.2m calcium chloride, respectively. Fresh-cut tropical fruits were packaged in various rigid containers (PET, OPS and OPLA). Gas composition in the package headspace and time to reach steady-state condition varied among fresh-cut packaging systems and affected their quality and shelf-life. The effects of package permeability of O2 and CO2 on quality and shelf-life of the fresh-cut products are discussed. Extended shelf-life was observed in fresh-cut mangoes, pineapples and mixes packaged in PET due to reduced O2 and elevated CO2 atmosphere. A modified atmosphere of 6% O2 and 14% CO2 achieved in PET extended the shelf-life of fresh-cut pineapples from 6 to 13 days. Accumulation of CO2 may impart an off-odour of fresh-cut fruits. The results suggested that the shelf-life of fresh-cut fruits could be extended by using proper rigid containers. Suitable mixes to create optimal equilibrium modified atmosphere had a potential to extend shelf-life of short shelf-life fresh-cut tropical fruits. Copyright © 2006 John Wiley & Sons, Ltd. [source]


Study of the magnetic disaccommodation in La doped YIG

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2005
C. Torres
Abstract The relaxation of the initial magnetic permeability of La doped yttrium iron garnet (YIG) samples with nominal composition Y3,xLaxFe5O12 (0< x <0.6) is analysed in this work. The results show a very different behaviour depending on the sintering atmosphere used for the fabrication of the samples. Concretely, for the samples sintered in air, it just have been detected the usual relaxation peak found in YIG at 130 K. However, a new relaxation peak appears around room temperature for the samples sintered in CO2 atmosphere when the La content is at least of 0.3. These results have been interpreted in terms of the formation of a secondary perovskite phase when the La solubility limit is reached. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


In vitro Capacitation and Acrosome Reaction of Dog Spermatozoa can be Feasibly Attained in a Defined Medium Without Glucose

REPRODUCTION IN DOMESTIC ANIMALS, Issue 3 2004
JL Albarracín
Contents Incubation of dog spermatozoa in a medium without glucose and in the presence of lactate and pyruvate (l-CCM) for 4 h at 38.5°C in a 5% CO2 atmosphere induced in vitro capacitation of these cells. This was verified after the combined specific capacitation-like changes in percentages of viability and altered acrosomes, motility characteristics, sperm location of reactivity against Pisum sativum, Arachis hypogaea and Helix pomatia lectins and the tyrosine phosphorylation pattern. Furthermore, a feasible acrosome reaction (AR) was induced when spermatozoa incubated in l-CCM for 4 h were further co-incubated for 1 h with canine oocytes. This was demonstrated by AR-like changes in percentages of viability, altered acrosomes, motility characteristics and sperm location of reactivity against P. sativum, A. hypogaea and H. pomatia lectins. All these results clearly indicate that in vitro capacitation, and subsequent AR, can be feasibly achieved without the presence of sugars. This ability can be related to the specific characteristics of energy-metabolism regulation reported in dog spermatozoa. [source]


Shelf Life and Microbial Quality of Fresh-cut Mango Cubes Stored in High CO2 Atmospheres

JOURNAL OF FOOD SCIENCE, Issue 1 2005
Jutatip Poubol
ABSTRACT: Fresh-cut,Carabao'and,Nam Dokmai'mango cubes were stored in air or in high CO2 atmospheres (3%, 5%, and 10%) at 5 °C and 13 °C. Freshly sliced,Carabao'mango cubes had a lower respiration rate and total bacterial count and higher L-ascorbic acid content and firmness than,Nam Dokmai'mango cubes. The shelf life of fresh-cut mango, based on browning discoloration and water-soaked appearance, was 6 d at 5 °C and 4 d at 13 °C for,Carabao'and 2 d at 5 °C and less than 1 d at 13 °C for,Nam Dokmai'. High CO2 atmospheres retarded the development of water-soaked,Carabao'cubes at 5 °C and 13 °C and,Nam Dokmai'cubes at 5 °C. Texture of,Carabao'cubes was enhanced by high CO2, but ethanol and L-ascorbic acid contents were not affected at 5 °C and 13 °C. Total bacterial count was lower in,Carabao'cubes than in,Nam Dokmai'cubes during storage at both temperatures, and a 10% CO2 only reduced the bacterial count on,Carabao'and,Nam Dokmai'cubes stored at 13 °C. Bacterial flora in,Nam Dokmai'mango cubes consisted mostly of Gram-negative rods assigned primarily to phytopathogenic bacteria such as Pantoea agglomerans and Burkholderia cepacia. The genera of bacteria isolated from cubes stored in 10% CO2 were similar to those from cubes on the initial day. [source]


Melanin as a Target for Melanoma Chemotherapy: Pro-oxidant Effect of Oxygen and Metals on Melanoma Viability

PIGMENT CELL & MELANOMA RESEARCH, Issue 3 2003
Patrick J. Farmer
Melanoma cells have a poor ability to mediate oxidative stress, which may be attributed to constitutive abnormalities in their melanosomes. We hypothesize that disorganization of the melanosomes will allow chemical targeting of the melanin within. Chemical studies show that under oxidative conditions, synthetic melanins demonstrate increased metal affinity and a susceptibility to redox cycling with oxygen to form reactive oxygen species. The electron paramagnetic resonance (EPR)-active 5,5,-dimethyl-pyrollidine N-oxide spin adduct was used to show that binding of divalent Zn or Cu to melanin induces a pro-oxidant response under oxygen, generating superoxide and hydroxyl radicals. A similar pro-oxidant behaviour is seen in melanoma cell lines under external peroxide stress. Melanoma cultures grown under 95% O2/5% CO2 atmospheres show markedly reduced viability as compared with normal melanocytes. Cu- and Zn-dithiocarbamate complexes, which induce passive uptake of the metal ions into cells, show significant antimelanoma activity. The antimelanoma effect of metal- and oxygen-induced stress appears additive rather than synergistic; both treatments are shown to be significantly less toxic to melanocytes. [source]