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PubMed1996

Effects of modified atmosphere and vacuum packaging on the growth of spoilage and inoculated pathogenic bacteria on fresh poultry.

Fresh chicken breast meats inoculated with Yersinia enterocolitica and Aeromonas hydrophila were packaged in glass jars either containing different compositions of modified atmospheres (MA) (100% CO2; 80% CO2/20% N2), or in vacuo or containing air, and were stored at 3 +/- 1 degrees C and 8 +/- 1 degrees C. The changes in gas composition as well as Y. enterocolitica, A. hydrophila, total aerobic bacterial, total psychotropic, Lactobacilli and Enterobacteriaceae counts were determined after 0, 1, 3, 7, 9, 11 and 14 days of storage. The results show that while the growth of Y. enterocolitica and A. hydrophila were retarded following MA storage, the pathogens were capable of growth in MA and vacuum storage at both temperatures, for the inoculation levels studied. For total aerobic bacterial counts, there were no differences between the values for chicken breast meats kept in different atmospheres. Being packaged in CO2 had the greatest inhibitory effect on the growth of psychotropic aerobic bacteria during the first 3 days. Lactic acid bacteria levels of samples stored in MA conditions and in vacuo increased rapidly when compared to those levels of samples stored in air. It was also found that the effect of MA storage increased at 3 +/- 1 degrees C.

Aeromonas hydrophila↗

PubMed1995

Influence of the incubation atmosphere on the production of slime by Staphylococcus epidermidis.

The influence of various incubation atmospheres on the growth and slime production of 23 Staphylococcus epidermidis strains was studied. The atmospheres evaluated were aerobiosis (control), anaerobiosis, candle jar, 5% CO2 and 10% CO2. As compared to the aerobic control, growth was 55.7 +/- 19% (p < 0.01) in anaerobic incubation, 113.7 +/- 12% (p < 0.01) in 5% CO2, 112.8 +/- 13% (p < 0.01) in 10% CO2 and 106.4 +/- 7% (p > 0.1) in the candle jar. The slime production in relation to the aerobic control was 20.3 +/- 19% in anaerobiosis (p < 0.01), 22.3 +/- 27% (p < 0.01) in 5% CO2, 29.4 +/- 39% (p < 0.01) in 10% CO2 and 68.3 +/- 26% (p > 0.1) in the candle jar. The results of this study may explain the discrepancies which have been noted on occasion between slime formation data and pathogenicity.

Aerobiosis↗

PubMed1985

Effects of incubation in an atmosphere of 20% CO2 in air on the Syrian hamster embryo clonal transformation assay.

An atmosphere containing 10% CO2 has been generally accepted as optimal for the growth of Syrian hamster embryo cells in a clonal transformation assay. Data presented in this paper show that 10% CO2 may not be the optimum environment for this assay. Using 10 or 20% (analytically measured) CO2 in air (1 atm pressure), hamster embryo cell pools were examined for clonal growth characteristics and transformability using five known carcinogens and a single noncarcinogenic compound. At 10% CO2, only 2 of 11 pools were transformed by the five carcinogens but not by the noncarcinogen. At 20% CO2, six of seven pools were transformed by the five carcinogens and not by the noncarcinogen. Further, the transformation frequencies were found to be greater in cultures incubated in an atmosphere consisting of 20% CO2 in air. The data also show that 20% CO2 increased the cloning efficiency of these cells. A comparison of the 10 and 20% CO2 data to results reported from other laboratories suggests that conflicting interlaboratory results with this assay system may be due, in part, to variations of CO2 concentrations. In some instances, the CO2 levels indicated by incubator flow meters vary considerably from analytically determined CO2 values. To prevent these CO2 discrepancies and their resultant effects on transformation and cloning efficiency, methods for monitoring the CO2 environment other than flow meters are recommended. The observation of increased cloning efficiencies and transformation rates strongly suggests that culture incubation at 20% CO2 is a preferred environment for the conduct of this assay.

Animals↗

PubMed1990

Keratinophilic and other fungi isolated from combine harvester wheat and sorghum dusts and from the atmosphere of winnow sites in Egypt.

Three methods were used for the isolation of fungi in the present investigation: the dilution-plate method, hair-baiting technique with horse hairs and the "exposed plate" method. Sabouraud's glucose agar at 28 degrees C was also used as isolation medium. 102 species and 2 species varieties belonging to 36 genera were collected from combine harvester wheat and sorghum dusts and from the atmosphere of hay or winnow sites. Chrysosporium was represented by 6 species: C. asperatum, C. indicum, C. keratinophilum, C. merdarium, C. pannorum and C. tropicum. Several filamentous fungi tolerating high levels of cycloheximide and other moulds were frequently encountered in the two types of dusts and in the two atmospheres, such as members of Acremonium, Alternaria, Aspergillus, Cladosporium, Emericella, Eupenicillium, Fusarium, Paecilomyces, Penicillium, Piedraia, Rhizopus, Scopulariopsis and others.

Air Microbiology↗

PubMed2002

Volatile hydrocarbons in the atmosphere of Athens, Greece.

This work presents the results of one-year monitoring study of Volatile Hydrocarbons, VHCs, in the atmosphere of Athens. It is the first systematic attempt to determine the VHC levels in the Athens' atmosphere with the very well known photochemical pollution problems. The purpose of this work was to create a database concerning VHCs in order to evaluate the photochemical pollution in this area (ozone creation, case studies and meteorology). Totally, 308 samples were collected at three different sites used in the state-monitoring programme involving the criteria pollutants. Air samples were collected on Tenax TA tubes and analysed by thermal desorption and dual column GC dual FID. Fifteen selected compounds were studied; 6 alkanes and 9 benzenoid compounds. The measured values of individual alkanes ranged from 0.39 pg m(-3) to 33 pg m(-3), and those of aromatics from 0.20 pg m(-3) to 616 pg m(-3). The sum of all 15 VHC concentrations ranged between 16 and 1697 pg m(-3). The time and spatial variations in the concentration of these compounds were assessed. Volatile hydrocarbons exhibited a clear seasonal and time cycle, showing higher concentrations during winter and early morning hours. Study of the spatial variations of VHC levels showed higher concentrations at the center of the city. The variation of toluene/benzene ratio and the correlation between VHCs, criteria pollutants (CO, NOx and O3) and meteorological parameters were also assessed. It was demonstrated that a trip-line of the VHCs concentration at the city center doubles the ozone concentration at peripheral areas under favourable meteorological conditions.

Air Pollutants↗

PubMed2004

Determination of polychlorobiphenyls and polycyclic aromatic hydrocarbons in the atmospheric aerosol of the Venice Lagoon.

An analytical method for simultaneous determination of "particle"-associated and "gaseous"-phase concentrations of polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) in atmospheric aerosol samples obtained by high-volume samplers using polyurethane foam adsorbent (PUF) and quartz fibber filters (QFF) has been investigated. Quality control of the analytical procedure was carried out by blank control and by evaluating limits of detection, recoveries, accuracy, and repeatability. The proposed method was subsequently used to determine PAH and PCB in the "gaseous" and "particulate" phases of the aerosols that enter the Venice Lagoon atmosphere. The highest concentrations of sigma PCB and sigma PAH were predominantly in the "gaseous" phase. In both "particulate" and "gaseous" phases the penta-CB congeners dominated total PCB concentrations whereas phenanthrene, fluoranthene, and pyrene dominated the sigma PAH concentrations. Total ("gaseous" plus "particulate") PCB and PAH concentrations were higher at the site directly influenced by the industrial plants but the concentrations in marine aerosol samples were lower by a factor four only and must be taken into consideration when studying the chemical contamination of the Venice Lagoon.

Aerosols↗

PubMed1996

Laser spectroscopy for atmospheric chemistry: selected applications involving the fluorescence technique.

The application of laser-based techniques to the study of different problems related to atmospheric chemistry is well established. Among the various laser spectroscopic methods, the focus here is directed towards selected applications of the laser photofragmentation and fluorescence techniques, which are used to investigate the complex chemistry of tropospheric sulphur species, with particular emphasis on the oxidation of dimethyl sulphide (DMS) and the consequent formation of sulphuric acid, and to the possibility of detecting with very high sensitivity and selectivity a particular element (e.g., gold) in size-segregated aerosol particles in view of its possible release as a tracer in the atmosphere. The atomic fluorescence technique is also applied to the real time detection of lead in a miniature air-acetylene flame, in which monodisperse aerosol particle are introduced.

Journal Article↗

PubMed1996

Determination of ultra-trace levels of gold in size-segregated atmospheric particulate samples by laser induced fluorescence: towards an aerosol tracer.

A method is described for measuring the gold content of integral and size-segregated samples of atmospheric particulate matter. After acid digestion and a liquid/ liquid extraction, the sample are analysed by Two-Colour Laser Induced Fluorescence in a graphite furnace. An absolute instrumental detection limit of 1 fg is achieved. Assuming a sampled volume of 1 m(3), this corresponds to an atmospheric concentration of 50 fg m(-3). Due to blank limited noise, the above limits increase to 20 fg and 1 pg m(-3), respectively. Results of the analysis of filter samples as well as of size-segregated impactor samples are presented.

Journal Article↗

PubMed2006

Atmospheric deposition of polycyclic aromatic hydrocarbons in an urban and a suburban area of Korea from 2002 to 2004.

Atmospheric bulk samples (wet and dry) were collected monthly during 2002 to 2004 from an urban and a suburban area in Korea for assessment of depositional flux and seasonal variations in the concentrations of polycyclic aromatic hydrocarbons (PAHs). PAH depositional flux ranged from 64.1 to 610 microg/m2/y for the urban area and from 65 to 460 microg/m2/y for the suburban area. The fluxes of PAHs measured in this study were comparable with those reported for urban and suburban areas in other countries. The fluxes of particulates and PAHs were higher in winter than in summer, consistent with the greater per capita consumption of fossil fuel in winter than in summer. Ambient temperature played a major role in the seasonal variability in PAH fluxes. Photochemical degradation of PAHs appears to occur during the summer months. The relationship of PAH depositional fluxes with major air pollutants, such as ozone, sulfur dioxide, carbon monoxide, nitrogen dioxide, and presence of particulate matter up to 10 microm in size (PM10), was also investigated. Dominant PAH compounds in both the urban and the suburban locations were benzo[g,h,i]perylene, pyrene, and indeno[1,2,3-c,d]pyrene. Based on the PAH diagnostic ratios and a factor analysis, the major sources of PAHs in the urban and the suburban regions were found to be similar. Diesel exhaust, coal combustion, and gasoline emissions contributed predominantly to atmospheric PAH contamination.

Korea↗

PubMed2006

A combined MOIP-MCDA approach to building and screening atmospheric pollution control strategies in urban regions.

This article presents a methodological approach for the formulation of control strategies capable of reducing atmospheric pollution at the standards set by European legislation. The approach was implemented in the greater area of Thessaloniki and was part of a project aiming at the compliance with air quality standards in five major cities in Greece. The methodological approach comprises two stages: in the first stage, the availability of several measures contributing to a certain extent to reducing atmospheric pollution indicates a combinatorial problem and favors the use of Integer Programming. More specifically, Multiple Objective Integer Programming is used in order to generate alternative efficient combinations of the available policy measures on the basis of two conflicting objectives: public expenditure minimization and social acceptance maximization. In the second stage, these combinations of control measures (i.e., the control strategies) are then comparatively evaluated with respect to a wider set of criteria, using tools from Multiple Criteria Decision Analysis, namely, the well-known PROMETHEE method. The whole procedure is based on the active involvement of local and central authorities in order to incorporate their concerns and preferences, as well as to secure the adoption and implementation of the resulting solution.

Air Pollution↗

PubMed2004

Effects of elevated atmospheric CO2 on the nutritional ecology of C3 and C4 grass-feeding caterpillars.

It is plausible that the nutritional quality of C3 plants will decline more under elevated atmospheric CO2 than will the nutritional quality of C4 plants, causing herbivorous insects to increase their feeding on C3 plants relative to C4 plants. We tested this hypothesis with a C3 and C4 grass and two caterpillar species with different diet breadths. Lolium multiflorum (C3) and Bouteloua curtipendula (C4) were grown in outdoor open top chambers at ambient (370 ppm) or elevated (740 ppm) CO2. Bioassays compared the performance and digestive efficiencies of Pseudaletia unipuncta (a grass-specialist noctuid) and Spodoptera frugiperda (a generalist noctuid). As expected, the nutritional quality of L. multiflorum changed to a greater extent than did that of B. curtipendula when grown in elevated CO2; levels of protein (considered growth limiting) declined in the C3 grass, while levels of carbohydrates (sugar, starch and fructan) increased. However, neither insect species increased its feeding rate on the C3 grass to compensate for its lower nutritional quality when grown in an elevated CO2 atmosphere. Consumption rates of P. unipuncta and S. frugiperda were higher on the C3 grass than the C4 grass, the opposite of the result expected for a compensatory response to the lower nutritional quality of the C4 grass. Although our results do not support the hypothesis that grass-specialist insects compensate for lower nutritional quality by increasing their consumption rates more than do generalist insects, the performance of the specialist was greater than that of the generalist on each grass species and at both CO2 levels. Mechanisms other than compensatory feeding, such as increased nutrient assimilation efficiency, appear to determine the relative performance of these herbivores. Our results also provide further evidence against the hypothesis that C4 grasses would be avoided by insect herbivores because a large fraction of their nutrients is unavailable to herbivores. Instead, our results are consistent with the hypothesis that C4 grasses are poorer host plants primarily because of their lower nutrient levels, higher fiber levels, and greater toughness.

Air↗

PubMed2003

Free amino acids and biogenic amines in red and white muscle of tuna stored in controlled atmospheres.

This paper analyses the presence of and changes in free amino acids and biogenic amines in red and white muscle of bigeye tuna during storage in controlled atmospheres with 2 gas mixes containing different concentrations of CO(2) and O(2). Levels of amines were generally higher in white than in red muscle, with the exception of putrescine and spermidine. Levels of biogenic amines increased (p<0.05) throughout storage, commencing later in red than in white muscle. A correlation between the amino acid histidine and the biogenic amine histamine was observed, but only in white muscle. Only in the case of tryptophan did white and red muscle differ (p<0.05) in terms of essential free amino acid content. They also differed in anserine content. Concentrations of the non-essential FAAs glutamic acid, glycine and alanine were higher in red than in white muscle. The effectiveness of the atmospheres was reflected in the evolution of both biogenic amines and FAAs. Gas mix 1, containing a higher concentration of CO(2), was the more effective.

Amino Acids↗

PubMed2006

Lichens as bioindicators of atmospheric heavy metal pollution in Singapore.

Lichens have been used as bioindicators in various atmospheric pollution assessments in several countries. This study presents the first data on levels of heavy metals (As, Cd, Cu, Ni, Pb, and Zn) in lichens at different locations in Singapore, Southeast Asia. Singapore is a fully industrialised island nation, with a prevailing tropical climate and a population of 4 million people within a confined land area of less than 700 km2. The ubiquitous lichen species, Dirinaria picta was collected from six sample sites across Singapore and analysed for heavy metals using inductively coupled plasma mass spectrometry (ICPMS). No significant relationship existed between metal levels in lichen and soil, indicating that accumulated metals in lichen are primarily derived from the atmosphere. Peak concentrations of zinc (83.55 microg g(-1)), copper (45.13 microg g(-1)) and lead (16.59 microg g(-1)) in lichens were found at Sembawang, Jurong and the National University of Singapore campus which are locations associated with heavy petroleum and shipping industries, and road traffic respectively. The mean heavy metal levels of lichen samples in Singapore were found to be at the upper range of values reported in the literature for temperate countries.

Air Pollution↗

PubMed2004

The wear and fracture behaviour of ultra high molecular weight polyethylene subjected to gamma-irradiation in an atmosphere of acetylene.

The wear and mechanical properties of GUR 1020 (Perplas IMP 2000-2) Ultra High Molecular Weight Polyethylene (UHMWPE) subjected to gamma-irradiation in an atmosphere of acetylene, were evaluated for a range of processing conditions of irradiation, annealing and ageing. The results were compared with those obtained for the virgin UHMWPE material and material processed using conventional gamma-irradiation in nitrogen. Cross-linking produced by irradiation in acetylene, followed by subsequent annealing was found to be significantly more effective in improving the mechanical and wear properties of UHMWPE compared to when the material was irradiated in nitrogen. Gel fraction analysis on its own, while being able to detect the degree of cross-linking, was found to be insufficient in determining the effectiveness of the cross-links and the resulting mechanical properties of the UHMWPE material. The results suggest that gamma-irradiation in an atmosphere of acetylene may provide significant advantages over conventional UHMWPE processing and irradiation cross-linking techniques.

Acetylene↗

PubMed2005

The effect of inert atmospheric packaging on oxidative degradation in formulated granules.

PURPOSE: Oxidative degradation of drug substances in pharmaceutical products is well documented and is thought to occur in many cases via autoxidative processes involving headspace molecular oxygen in the primary package. Reducing the headspace oxygen concentration inside a package could thus be an option for reducing oxidative degradation in pharmaceutical products. The purpose of this study is to examine the effect of headspace oxygen concentration and relative humidity (RH) on the oxidative degradation of a model pharmaceutical formulation. METHODS: Model formulations, including a drug substance known to exhibit oxidative degradation, at two different drug/excipient ratios were packaged in stoppered glass vials maintained at different oxygen concentrations, (from 0% to 20.9%) and headspace relative humidities and were stored at 40 degrees C. The oxidative degradation was quantified as a function of time. RESULTS: The results clearly show dependence of oxidative degradation on headspace oxygen concentration, relative humidity, drug loading and time. CONCLUSIONS: The results provided insight into the effectiveness of inert atmospheric packaging (IAP) for protecting oxidation-labile products. In light of these observations, a few strategies for practically implementing inert atmosphere packaging are also presented.

Chemistry, Pharmaceutical↗

PubMed1983

A prospective atmospheric emission inventory for cadmium--the European community as a study area.

The quantities of cadmium emitted to the atmosphere from natural and human sources have been estimated for the member states of the European Community, allowing the construction of an atmospheric emission inventory for cadmium at the regional level. A survey of the available emission data was used to calculate an emission factor (g cadmium emitted tonne -1 material consumed or produced) for each source. This value was applied to the most recent consumption or production data for the region to obtain an annual discharge estimate. Predictions of future trends in cadmium emissions from human sources over the next two decades were based on economic forecasts for the process in question. The iron and steel industries and refuse incineration are the two largest sources of airborne cadmium in the region, followed by volcanic action and zinc production. It is forecast that there will be an increase in cadmium emissions over the next two decades due mainly to the iron and steel industries and zinc production. A comparison of the emission estimates obtained in this study with those given in previously published inventories reveal disparities in the source strengths for some processes. In particular, it would appear that cadmium emissions from coal combustion and non-ferrous metal production have been overestimated in some past studies.

Air Pollutants↗

PubMed1988

Size distribution of atmospheric aerosols in urban sites in India.

Particle size distribution of atmospheric aerosols was measured at different locations in Moradabad and Bombay, India, using an Andersen cascade impactor. The size distributions of lead, cadmium, copper and zinc were found to be bimodal. The respirable fraction of the particulates (less than 4.7 microns) was calculated. The fraction of fine particles was found to be greater in Bombay than in Moradabad. The mass median aerodynamic diameter (MMAD) for lead, cadmium, copper and zinc was calculated. The atmospheric concentrations of these elements were also measured at the two locations. The analysis of samples was carried out by differential pulse anodic stripping voltammetry.

Air Pollutants↗

PubMed1992

Sources and atmospheric concentrations of polycyclic aromatic hydrocarbons and heavy metals in two Italian towns (Genoa and La Spezia).

The same sampling and analytical methods were used to compare atmospheric pollution due to polycyclic aromatic hydrocarbons (PAHs) and heavy metals (Tl, Pb, Mn, Fe, Cr, V, Zr, Ni Cd) in two towns in Italy, Genoa and La Spezia, whose populations are 746, 785 and 112,602 respectively. Knowledge of the organic and inorganic composition of airborne particulates permits a reliable identification of the main sources of pollution which is required in order to identify populations at risk. In the urban area of Genoa and in La Spezia, traffic appears to provide a diffuse source of carcinogenic and toxic compounds in the atmosphere producing high and constant exposures to PAHs and lead along busy streets. In Genoa approximately 70,00 people (10% of residents) are considered to be exposed to the highest concentrations of toxic and cancerogenic pollutants emitted from this source. The highest daily PAH concentrations were found in the industrial areas; in Genoa, coke ovens were identified as the main localised sources of these compounds. According to meteorlogical and orographic characteristics for this area, for approximately 25,00 people (3% of the general population) may be exposed to pollutants emitted from this source over a maximum period equivalent to approximately 3 months each year. The highest individual doses of PAHs due to urban pollution inhaled by the population of Genoa and La Spezia were comparable to those produced by high exposure to passive smoke; the exposure to carcinogenic metals (Cr, NI, Cd) was relatively low. The mean concentrations of the analysed pollutants appeared to depend strictly on urban characteristics; no correlations were found with the size of the town.

Air Pollutants↗