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At least 955 records · Page 53Linked to original sources
PubMed1975

A novel form of diffusion battery.

A novel form of diffusion battery uses a series of 635-mesh screens instead of the customary cluster of circular tubes or holes. Fifty-five screens are arranged in series so that the amount of aerosol penetrating through different numbers of screens can be measured with a condensation nuclei counter. This "filter stack" must be calibrated because theory is not available to calculate the performance of such screens with sufficient accuracy. For calibration a polydisperse aerosol such as ambient or silver aerosol is used to compare the performance of the screens with that of the cluster-tube and collimated-holes diffusion batteries, whose performance is known from theory. It was observed that a given number of screens is equivalent to a given number of batteries independent of the size or size distribution of the aerosol. This filter stack is very compact and light in weight (0.9 kg). It is particularly useful for measurements in the field.

Aerosols↗
PubMed1978

Measurement of chromium VI and chromium III in stainless steel welding fumes with electrom spectroscopy for chemical analysis and neutron activation analysis.

Electron Spectroscopy for Chemical Analysis (ESCA) was explored as a means of studying the oxidation state of chromium in SMAC (coated electrode) stainless steel welding fume collected on Nucleopore filters in the laboratory. Chromuim VI and III (as a percent of the total chromium) obtained from ESCA analysis was applied to results from Neutron Activation Analysis (NAA) to yield an average of 69 microgram chromium VI per sample. Diphenylcarbazide/atomic absorption (DPC/AA) results are reported for samples submitted to an industrial laboratory. Possible chemical species and solubility of chromium VI in stainless steel fumes is discussed in light of analogy between the SMAC process and the manufacturing process for chromates.

Air Pollutants↗
PubMed1985

Effect of commercial formulation of four organophosphorus insecticides on the ovaries of a freshwater teleost, Mystus vittatus (bloch)--a histological and histochemical study.

The chronic effect of an exposure to a sublethal concentration of commercial formulation of 4 organophosphorus insecticides such as birlane (chlorfenvinphos), gardona (tetrachlorvinphos), phosdrin (mevinphos) and malathion on midvitellogenic ovaries of Mystus vittatus was investigated using several histological and histochemical techniques. The loss of stage II and III oocytes accompanied by a significant decline in gonadosomatic index was recorded. The vitellogenesis in treated fishes was ceased as the oocytes did not advance to further stages as evidenced by the absence of lipid yolks and the lack of a PAS positive follicular layer. The RNA content of remaining stage I oocytes of exposed fishes resembled that of the stage I oocytes of the control fishes. The absence of delta 5-3 beta-hydroxysteroid dehydrogenase suggested the lack of steroidogenesis. Reduced glucose-6-phosphate dehydrogenase activity was also observed. The significance of these observations has been discussed in light of available literature.

3-Hydroxysteroid Dehydrogenases↗
PubMed2003

Risk estimates for deterministic health effects of inhaled weapons grade plutonium.

Risk estimates for deterministic effects of inhaled weapons-grade plutonium (WG Pu) are needed to evaluate potential serious harm to (1) U.S. Department of Energy nuclear workers from accidental or other work-place releases of WG Pu; and (2) the public from terrorist actions resulting in the release of WG Pu to the environment. Deterministic health effects (the most serious radiobiological consequences to humans) can arise when large amounts of WG Pu are taken into the body. Inhalation is considered the most likely route of intake during work-place accidents or during a nuclear terrorism incident releasing WG Pu to the environment. Our current knowledge about radiation-related harm is insufficient for generating precise estimates of risk for a given WG Pu exposure scenario. This relates largely to uncertainties associated with currently available risk and dosimetry models. Thus, rather than generating point estimates of risk, distributions that account for variability/uncertainty are needed to properly characterize potential harm to humans from a given WG Pu exposure scenario. In this manuscript, we generate and summarize risk distributions for deterministic radiation effects in the lungs of nuclear workers from inhaled WG Pu particles (standard isotopic mix). These distributions were developed using NUREG/CR-4214 risk models and time-dependent, dose conversion factor data based on Publication 30 of the International Commission on Radiological Protection. Dose conversion factors based on ICRP Publication 30 are more relevant to deterministic effects than are the dose conversion factors based on ICRP Publication 66, which relate to targets for stochastic effects. Risk distributions that account for NUREG/CR-4214 parameter and model uncertainties were generated using the Monte Carlo method. Risks were evaluated for both lethality (from radiation pneumonitis) and morbidity (due to radiation-induced respiratory dysfunction) and were found to depend strongly on absorbed-dose-rate history (which depends on WG Pu solubility). The results obtained were compared to new data from animal and epidemiological studies. Our findings suggest that NUREG/CR-4214 models for assessing lethality risk from inhaled radionuclides may need some modest revision in light the new data. However, for assessing morbidity risks, major revisions may be needed.

Administration, Inhalation↗
PubMed2001

[Spectrum studies on titania photocatalysts].

The nano-sized TiO2 photocatalysts were prepared by sol-gel method and characterized by FTIR spectroscopy, FT-Raman spectroscopy and diffuse reflectance spectroscopy(DRS). Photocatalytic degradation of oleic acid over the TiO2 catalysts was investigated. The result showed that calcination temperature has strong effect on crystal structure, energy band structure, optical adsorption and photocatalytic activity of the TiO2 catalysts. It was found that the TiO2 photocatalyst calcined at 400 degrees C has the best apparent optical adsorption, the biggest band edge position and the highest photoactivity. The effect of calcination temperature on photocatalytic activity of TiO2 catalysts has been ascribed to the changes in structure and optical property of catalyst such as crystal size, content of rutile, residual NO3-, and band-edge position of light adsorption.

Adsorption↗
PubMed1989

Incidence of ferruginous bodies in the lungs during a 45-year period and mineralogical analysis of the core fibres and uncoated fibres.

In order to determine the level of asbestos pollution in the lungs of members of the general population in and around Tokyo, the incidence of ferruginous bodies in autopsied or resected lungs during 5 periods over the 45 years from 1937 to 1981 was studied under a light microscope. Core fibres, after removal of their ferruginous coatings with oxalic acid, and uncoated fibres were analysed using a scanning electron microscope equipped with a Kevex energy-dispersive X-ray spectrometer. The incidence of ferruginous bodies in 5 g (wet) of digested lung tissue was shown to be 10% in period I (1937-1941), 18% in period II (1947-1951), 70% in period III (1958-1963), 74.4% in period IV (1970-1973) and 81.0% in period V (1980-1981). The major types of core fibres of ferruginous bodies were found to be asbestos, including amosite, crocidolite, chrysotile and the tremolite-actinolite series, but a small number of fibres of materials other than asbestos were also detected. In contrast, a large number of short fibres less than 5 microns in length in 1 g of wet lung tissue were classified as belonging to the Mg+Si group (the ratio of Mg to Si components being 30% or over) and presumed to be chrysotile. Thus an annual increase in asbestos deposition in the lungs of people living in and around Tokyo has been demonstrated and fine chrysotile fibres less than 5 microns in length seem to be the main type of deposited fibres.

Adult↗
PubMed1994

[The occurrence of keratinolytic fungi in the polluted environment of the Labedy District in Gliwice].

This study was undertaken to find relationships between the degree of bacteriological contamination with qualitative composition of potentially pathogenic keratinolytic fungal population in soil, sediment and air samples from the Labedy district in Gliwice (Poland). The examined soil samples were characterized by the predominance of Botryotrichum piluliferum, Chrysosporium anamorph of Arthroderma curreyi, Myceliophthora anamorph of Ctenomyces serratus, Chrysosporium pannicola and Trichphyton ajelloi. These species are typical for keratinolytic mycoflora in moderate climate soils, and their abundance was certainly resulted from the assembly of keratin remains in the soil environment. In the light of the weak bacteriological and mycological differentiation of the examined soil samples, however, it is difficult to determine categorically the extent to which the remains were originated from sewage via soil flooding by sewage or air transportation, or from the local human and animal population. Subsequently, the population of keratinolytic fungi in sediments was found to be clearly dependent of the degree of water contamination with sewage. In badly polluted sediments, Chrysosporium pannicola, Chrysosporium anamorph of Aphanoascus fulvescens, Chrysosporium keratinophilum, Trichophyton ajelloi and Microsporum cookei were prevalent species. Keratinolytic fungi were only a small part of airborne fungal population in sewage bioaerosoles. Geomyces pannorum, a soil species better known by its celullotytic than keratinolytic properties, predominated in air samples. Some pathogenic species, such as Aspergillus flavus, Aureobasidium pullulans, Chrysporium anamorph of Aphanoascus fulvescens, Candida spp., Geotrichum candidum, Microsporum canis, Sporothrix schenckii and Trichosporon beigelii, were recovered in the present study. This confirms that the sewage-contaminated environments in an important storage place of pathogenic fungi, mostly from the opportunistic subgroup.

Air Microbiology↗
PubMed2006

[Studies of relationships between Cu pollution and spectral characteristics of TritiZnm aestivum L].

The effect of Cu pollution on the Cu uptake by wheat, the characteristics of chlorophyll concentration, and the visible-near infrared spectra were studied under the condition of solution culture, and the relationships among the three indices were discussed. The results indicate that the content of Cu in TritiZnm aestivum L. increases and the concentration of chlorophyll reduces with the increase of Cu in solution. The spectral characteristics also take on the disciplinary diversification (the spectral reflectivity ascended in the visible light band and decreased in the near infrared band; the range of red edge shift decreased) with the increase of Cu in solution.

Chlorophyll↗
PubMed2005

Photocatalytic degradation of p-nitrophenol on nanometer size titanium dioxide surface modified with 5-sulfosalicylic acid.

The surface of nanometer size TiO(2) was simply and fast modified by chemical adsorption in saturated solution of 5-sulfosalicylic acid. After surface modification, a stable, yellow surface complex was formed quickly, the wavelength response range of TiO(2) was expanded, it has obvious absorption in the region from 320 to 450 nm; the adsorption efficiency of p-nitrophenol (PNP) by TiO(2) was enhanced from 42% to 84%. The photocatalytic activity was tested on the degradation of PNP. The influences of catalyst and its dosage, pH value, and PNP concentration on the degradation were investigated. On optimal photodegradation conditions, including initial pH 4.0, PNP 5 mg l(-1), catalyst 100 mg, irradiation time 120 min with 160 W high-pressure mercury lamp, the degradation efficiency of PNP was increased from 40% to 88% after surface modification. Surface modification led not only to an increase in the light utilization, but also improved the surface coverage of PNP in comparison with the pure TiO(2). Both of these factors are crucial for the photocatalytic activity of heterogeneous photocatalysis, especially for photodegradation of benzenoid pollutants.

Adsorption↗
PubMed2002

Comparison of black smoke and PM2.5 levels in indoor and outdoor environments of four European cities.

Recent studies on separated particle-size fractions highlight the health significance of particulate matter smaller than 2.5 microm (PM2.5), but gravimetric methods do not identify specific particle sources. Diesel exhaust particles (DEP) contain elemental carbon (EC), the dominant light-absorbing substance in the atmosphere. Black smoke (BS) is a measure for light absorption of PM and, thus, an alternative way to estimating EC concentrations, which may serve as a proxy for diesel exhaust emissions. We analyzed PM2.5 and BS data collected within the EXPOLIS study (Air Pollution Exposure Distribution within Adult Urban Populations in Europe) in Athens, Basel, Helsinki, and Prague. 186 indoor/outdoor filter pairs were sampled and analyzed. PM2.5 and BS levels were lowest in Helsinki, moderate in Basel, and remarkably higher in Athens and Prague. In each city, Spearman correlation coefficients of indoor versus outdoor were higher for BS (range rspearman: 0.57-0.86) than for PM2.5 (0.05-0.69). In a BS linear regression model (all data), outdoor levels explained clearly more of indoor variation (86%) than in the corresponding PM2.5 model (59%). In conclusion, ambient BS seizes a health-relevant fraction of fine particles to which people are exposed indoors and outdoors and exposure to which can be assessed by monitoring outdoor concentrations. BS measured on PM2.5 filters can be recommended as a valid and cheap additional indicator in studies on combustion-related air pollution and health.

Air Pollutants↗
PubMed2001

[Cellular level of the body adaptation to the environmental exposure in the large industrial city (Saint-Petersburg)].

By methods of light and electron microscopy structural disturbances of heart, kidneys, liver and pancreas were studied in rats pups who were born and kept for a year at kindergartens of city districts diverse in level of environmental pollution (air and soil). The content of micronuclei in epitheliocytes of oral mucosa in 5-6 ys old children from the kindergartens was controlled in order to detect chromosome aberrations. The examination of morphofunctional state of the organs studied and cells containing micronuclei carried out in different districts of the city allowed to reveal correlation between disorders studied and the level of environmental pollution.

Adaptation, Physiological↗
PubMed2003

Infrared optical sensors for water quality monitoring.

In-situ monitoring of water quality with particular emphasis on organic pollutants is a global priority topic in water analysis. Recent developments in optical sensor technology provide advanced analytical tools for continuous assessment of pollution levels in the liquid phase and in the gas phase. Infrared sensing schemes are among the most promising concepts due to inherent molecular specificity provided by absorption patterns of fundamental molecular vibrations of organic molecules. The advent of mid-infrared transparent optical fibers and waveguides, appropriate light source technology, such as quantum cascade lasers, and the potential for the development of highly integrated analytical devices based on microfabrication technology substantiates the trend towards spectroscopic sensing techniques. Chemical modification of the waveguide surface leads to enhanced analyte recognition based on tunable properties of enrichment or (bio)chemical recognition layers. Discussion of fundamental sensing technology is complemented by recent examples, highlighting the state-of-the-art in this dynamic research field.

Environmental Monitoring↗
PubMed2005

Source seasonality of polycyclic aromatic hydrocarbons (PAHs) in a subtropical city, Guangzhou, South China.

Mega-cities are large sources of air pollution on a regional base. Differences in energy structures, geographical settings and regional climate features lead to a large variety of air pollution sources from place to place. To understand the seasonality of air pollution sources is critical to precise emission inventories and a sound protection of human health. Based on a year-round dataset, the sources of PAHs in the air of Guangzhou were drawn by principal factor analysis (PCA) in combination with diagnostic ratios, and the seasonality of these sources were analyzed by PCA/MLR (multiple linear regressions) and discussed. The average total gaseous and particulate PAHs concentrations were 313 and 23.7 ng m(-3), respectively, with a higher concentration of vapor PAHs in summer and particulate PAHs in winter. In addition to vehicle exhaust, which contributed 69% of the particulate PAHs, coal combustion was still an important source and contributed 31% of the particulate PAHs. Relatively constant contribution from coal combustion was found through the year, implying that coal combustion in power plants was not a seasonally dependent source. Evaporation from contaminated ground may be an important source of light PAHs in summer, providing an average contribution of 68% to the total PAHs in this study. By comparing the PAH concentrations and meteorological parameters, we found that higher concentrations of particulate PAHs in winter resulted from enhanced vehicle exhaust under low temperature and accumulation of pollutants under decreased boundary layer, slower wind speed, and long-term dryness conditions. It is suggested that the typical subtropical monsoon climate in South China, cool and dry in winter, hot and humid in summer, may play a key role in controlling the source seasonality (by enhancing vehicle exhaust in winter, ground evaporation in summer), and hence the ambient concentrations of PAHs in the air.

Air Pollutants↗
PubMed1975

Radioactive contamination of the environment and the possible consequences.

To find the optimum solution to the problem of how to protect the environment from pollution by industrial waste, it is necessary, first and foremost, to obtain information on the existing levels of various forms of pollution and the damage caused by them. In this review data are given on all the main sources of contamination of the environment by radioactive substances. The pathways by which these substances reach and affect the human body are discussed, the doses incurred are characterized and the possible consequences of existing levels of exposure are assessed in the light of the latest data on the dose-effect relationship. The wisdom of treating the evaluation of radiation hazards arising from the use of atomic energy not in isolation but as part of a whole complex of ecological factors - including the use of conventional fuels for power generation and transport - is duly noted.

Adult↗
PubMed2001

Leaf chlorosis in oilseed rape plants (Brassica napus) grown on cadmium-polluted soil: causes and consequences for photosynthesis and growth.

Brassica napus L. (oilseed rape) was grown from seeds on a reconstituted soil contaminated with cadmium (100 mg Cd kg-1 dry soil), resulting in a marked chlorosis of the leaves which was investigated using a combination of biochemical, biophysical and physiological methods. Spectroscopic and chromatographic analyses of the photosynthetic pigments indicated that chlorosis was not due to a direct interaction of Cd with the chlorophyll biosynthesis pathway. In addition, mineral deficiency and oxidative stress were apparently not involved in the pigment loss. Leaf chlorosis was attributable to a marked decrease in the chloroplast density caused by a reduction in the number of chloroplasts per cell and a change in cell size, suggesting that Cd interfered with chloroplast replication and cell division. Relatively little Cd was found in the chloroplasts and the properties of the photosynthetic apparatus (electron transport, protein composition, chlorophyll antenna size, chloroplast ultrastructure) were not affected appreciably in plants grown on Cd-polluted soil. Depth profiling of photosynthetic pigments by phase-resolved photoacoustic spectroscopy revealed that the Cd-induced decrease in pigment content was very pronounced at the leaf surface (stomatal guard cells) compared to the leaf interior (mesophyll). This observation was consistent with light transmission and fluorescence microscopy analyses, which revealed that stomata density in the epidermis was noticeably reduced in Cd-exposed leaves. Concomitantly, the stomatal conductance estimated from gas-exchange measurements was strongly reduced with Cd. When plants were grown in a high-CO2 atmosphere (4,000 microliters CO2 l-1), the inhibitory effect of Cd on growth was not cancelled, suggesting that the reduced availability of CO2 at the chloroplast level associated with the low stomatal conductance was not the main component of Cd toxicity in oilseed rape.

Adaptation, Physiological↗
PubMed2000

[Endocrine disruption agents: environment, health, public policies, and the precautionary principle].

The already substantial body of evidence and growing web of suspicions as to the scale and severity of the cascade effects of endocrine disrupters (related to persistent organic pollutants or POPs) on the health of ecosystems and humans have sparked such concern that in June 1998, representatives of 94 countries meeting in Montreal under the aegis of UNEP signed a draft international agreement to phase out the most harmful POPs. Related to particular persistent organic pollutants--toxic semi-volatile and persistent chemical compounds now found everywhere in the environment, such as BPCs, organochlorine pesticides, dioxins and furans, that build up in the bodies of organisms that consume other contaminated organisms along the food chain--endocrine disrupters are strongly suspected of affecting the health of animals and adversely impacting the health, fertility and even intellectual faculties of humans. For example, very low-level exposure to some POPs is associated with some hormone-dependent cancers, damage to the central and peripheral nervous systems, impaired immune system function, reproductive disorders and developmental disruptions in newborns and infants, who can be affected in utero or through breast-feeding. Considering the extreme complexity of the scientific and socio-economic effects of POP-related endocrine disrupters, there are those who, advocate a wait-and-see approach, claiming that there is not enough formal scientific proof. There are others who use the available evidence to advance the research, press for bans on incriminated substances and look for global, integrated and viable alternatives. And there are other still who, with careless disregard for the Precautionary Principle, are quite prepared to talk about the perverse effects of POPs in order to justify the increased use of artificial means of reproduction or the replacement of chemical pesticides by pest-resistant genetically modified organisms (GMOs), thereby opening the door to "solutions" that are potentially more biologically and ethically dangerous than the problems they purport to remedy. This paper provides an overview of the current understanding of the main sources and suspected effects of POPs on animal life and human health, explores the complexity of the scientific, economic and political issues involved in any international process to do away with the incriminated products, discusses the risks and perverse consequences of some of the proposed alternatives, and stresses the importance, in the light of these risks and consequences, of placing renewed emphasis on public and environmental health approaches based on the Precautionary Principle.

Endocrine System Diseases↗
PubMed2006

Cytomorphological alterations of the thymus, spleen, head-kidney, and liver in cardinal fish (Apogonidae, Teleostei) as bioindicators of stress.

Morphological and cytological alterations at the light microscope (LM) and transmission electron microscope (TEM) levels were observed in the thymus, spleen, head-kidney, and liver of cardinal fishes (Apogonidae, Teleostei) from the Gulf of Aqaba, Red Sea, sampled from a strongly polluted site at the northern end of the gulf, and compared to similar samples from a clean, reference site. At the polluted site, the most prominent change was the formation of numerous deposits of cells rich in phagosomes with lipofucin, melanin granules, and phagocytosed debris, including a high increase in number and dimensions of Hassall's corpuscles and melano-macrophage centers. The number of Hassall's corpuscles was 20 (+/-8.0)/mm(2) and of melano-macrophage centers 18 (+/-4.0)/mm(2) at the polluted site, and 7.0 (+/-4.0)/m(2) vs. 5.0 (+/-2.0)/mm(2) respectively at the reference site. In numerous instances the head kidney's melano-macrophage centers in fishes from the polluted site were encapsulated by reticulocytes, a phenomenon recognized as a marker of neoplasmosis and possible malignancy. In the spleens of fishes from the polluted site, numerous deposits of cell debris, peroxisomes, and enlarged lysosomes were also observed. The livers (hepatopancreas) of fishes from polluted waters demonstrated very strong hyperlipogeny. Many of their hepatocytes were laden with lipid vesicles, fragmented endoplasmic reticulula, and aberrant mitochondria. Although the observed alterations in the glands and liver do not indicate any immediate threat to the life of the fish, they can become crucial with respect to energy turnover and fecundity trajectories. This study strongly suggests the use of cytological alterations in vital organs, such as were observed, as pathological biomarkers to environmental stress.

Animals↗