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Abstract  

Bottom and sestonic sediments of Ypacarai Lake were invesetigated with XRF and Mössbauer techniques. The 120 km2 lake, depth averages 1.8 m. In addition to the lakes use for recreation, its basin has economic significance. Sediments play an important role in the distribution of trace elements in the aquatic system and as a sink for metals. Bottom and seston samples were taken from 4 different sampling stations which were selected according the morphology and population sites on the shore. The concentration of toxic metals was found to be low and no adverse ecological impact should be expected. The main metallic ion component is iron (1.68%). Mössbauer studies showed this element appears as Fe3+. Iron2+ was not detected. We suggest that Fe3+ acts as the limiting element which controls the eutrophication process.

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Cesium-137 concentrations in red, brown and green algae have been studied for the calculation of natural depuration rates. The algae species were collected from the same population of the Black Sea stations during the period of 1986–1995. The natural depuration rates are estimated as biological half-lives. The pattern of depuration results represented by a single component for each algae division. The biological half-lives of137Cs in red (Phyllophora nervosa), green (Chaetomorpha linum) and brown (Cystoceira barbata) algae are estimated to be 18.5, 21.6 and 29.3 months, respectively.137Cs and40K activity levels and their ratios in algae species in two stations in Black Sea region of Turkey have been determined during the period of 1990–1995. The results showed that the Sinop region was more contaminated than the ile region on the Black Sea coast of Turkey from the Chernobyl accident.

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The atmospheric pollution of São Paulo city is a serious problem due to the expansion of industrial area, increasing number of vehicles and population density. This work presents results obtained in the analysis of lichens collected in different sites of São Paulo city and in non-polluted areas of Atlantic Forest. Concentrations of twenty elements were determined in Canoparmelia texana species and comparisons were made between the results obtained in lichens from different sites. High concentrations of the elements As, Ba, Cd, Co, Cr, Fe, La, Mn, Sb and Zn were found for samples collected in sites located near industries and petrochemical plant. Br and Sb concentrations were also high in lichens from sites affected by vehicular emissions.

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Abstract  

It is known that in the Turkish soil Se and Zn concentrations are somewhatlower than in other countries. Lower zinc intake causes significant healthproblems mostly at rural areas. Six different population groups, total of55 subjects, consisting of children, people from rural areas, university studentsand staff members were selected and diet samples were collected by duplicateportion technique. Bread and flour samples were collected from six differentbakeries in Ankara. Zinc, selenium and other trace elements in these sampleswere analyzed mostly by INAA. Daily dietary zinc intake differs among differentgroups, ranging 5–13 mg Zn/day, and for all cases, it is lower thanRDA value of 15 mg Zn/day. Similarly, selenium daily intake is around 20–53µg Se/day, which is also lower than RDA value of 55–70 µgSe/day.

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Abstract  

Neutron activation analysis, inductively coupled plasma emission spectrometry(ICP-ES) and atomic absorption spectroscopy (AAS) have been used to determineactual daily dietary intakes of minerals and trace elements in the Iranianpopulation. This article deals with the trace elemental analysis of dailydiets of the Iranian population differentiated with respect to food habits,geographical variability, literacy and income. Three study groups in fiveregions were defined. Thirty total daily diet samples were prepared basedon the method of dietary records. Also a few samples representing the intakesof two other study groups, males and females, were prepared by the duplicatediet method. Therefore, this study not only covered representative dietarypatterns of almost all adult people in Iran in a pilot study, but it alsopermitted to check the validity of the sampling methodology for total mixeddiet simulation.

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The influence of stages of lactation on the mineral and trace elementconcentrations of breast milk collected from 20 healthy lactating women ina Nigeria population was investigated using instrumental neutron activationanalysis (INAA) and proton induced X-ray emission (PIXE) analysis. The breastmilk samples were divided into colostrum (day 1–5), transitional (day6–13) and mature milk (day 14–28). The result of the study showthat colostrum milk has a significantly higher mean concentration of Ca, Cl,Cu, Fe, Mg, Na and Zn than the transitional and mature milk. Furthermore,the mean concentrations of Fe, Mg, Na and Zn in transitional milk were foundto be significantly higher when compared with the mature milk. It was alsoobserved from the semi-log plot of the concentration of the elements againstdays of lactation that the concentration of all the elements decreased significantlythroughout the lactation period studied with Cu, Fe and Zn concentration showingthe greatest decline, particularly in the early stages of lactation.

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The sensitivity of environmental sampling and analysis for the estimated atmospheric concentrations of radionuclides in effluents from clandestine nuclear facilities may require many sampling sites and exorbitant costs to monitor such large areas. An assessment has been made of the key factors necessary to support the operation of a nuclear facility, e.g., the existence of a nearby transportation network, main electrical power supply, and population centers. Screening, the subject of this paper, evaluates how cartographic data and satellite imagery can be used to identify areas most capable of supporting undeclared nuclear operations. As a result, large geographical areas can be eliminated from environmental monitoring and sampling. This leads to reduced costs, a reduction in the number of sampling sites required, and a reduction in the overall level of effort required to accomplish effective environmental monitoring. The screening methodology and techniques are described and examples given.

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Differential scanning calorimetry (DSC) and electron paramagnetic resonance spectroscopy (EPR, both conventional and saturation transfer EPR) were used to study the motional dynamics and segmental flexibility of myosin in muscle fibres in the presence of free radical generating system. Muscle fibre bundles isolated from psoas muscle of rabbit were spin-labelled with maleimide- and isothiocyanate-based probe molecules at the reactive sulfhydryl sites (Cys-707) of the motor domain. In the presence of hydroxyl free radicals the spectral intensity of the maleimide probe molecules decreased with time following a single exponential curve. MgADP and MgATP plus orthovanadate that produce flexibility changes in the multisubunit structure of myosin enhanced the reduction of the attached nitroxide molecules in free radical generating system. The analysis of the EPR spectra of spin-labelled and oriented fibres showed that the narrow distribution of spin labels changed in the presence of hydroxyl free radicals. Spectrum analysis by computer subtraction showed that short irradiation by UV light resulted in the enhancement of the ordered population at the expense of the disordered population. This suggests a transition of myosin heads from weak- binding state into strong-binding state. DSC measurements performed on calf cardiac myosin resulted in two main transitions at 49.4 and 54.1°C, respectively. Addition of MgADP produced a decrease of the 49.4°C transition, whereas a shift towards higher temperature was detected at the 54.1°C transition. It shows that there is an inter-site communication between the domains of the myosin. Hydroxyl free radicals induced further shifts of the transition temperatures and affected the width of the heat absorption curves.

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The effect of AMP.PNP on the thermal stability and dynamics of myosin head were investigated by using DSC and different spin label technique for chemically skinned muscle fibres prepared from rabbit. The thermal unfolding of the fibres in rigor, strong as well as weak-binding state showed a complex process characterizing at least three discrete domain regions with different stability (T m =54, 58.4 and 62.3°C). The unfolding at 54°C refers to the catalytic domain of myosin, whereas transition at T m =58.4°C represents the rod-like region. In the presence of AMP.PNP only the parameters of the last transition changed significantly (T m =70.4°C) showing an increased interaction between actin and myosin heads being attached to actin. Measurements on MSL-fibres (labelled at Cys-707 of myosin) in the presence of AMP.PNP showed that about half of the cross-bridges dissociated from actin. This fraction had a dynamic disorder, the other population had the same spectral feature as in rigor. In contrast, on TCSL-fibres AMP.PNP increased the orientational disorder of myosin heads, a random population of spin labels was superimposed on the ADP-like spectrum showing conformational and motional changes in the internal structure of myosin heads. ST EPR measurements reported increased rotational mobility of spin labels in the presence of AMP.PNP. The DSC and EPR results suggest that in the presence of AMP.PNP the attached heads have the same global orientation as in rigor, but the internal structure undergoes a local conformational change.

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Abstract  

The original purpose of this investigation started in 1996 was to study the radiological impact on the local population of the village of Chichiviriche de La Costa. But, soon after the major earthquake (Ms=6.8) in the state of Sucre on July 9, 1997, the objective was changed to study the fluctuation of radon (222Rn) to see if it could be correlated to seismic activity and/or if the amonlous change just before the earthquake can be considered a precusor for it. Measurements of222Rn by simply de-gassing about 250 ml of natural thermal water employing a Pylon AB-5 radiation monitor and counting the radiation after it reached equilibrium were performed. The values for four sampling periods in the first half of 1996 were about 17 Bq/l of222Rn, a month before the earthquake they were less than 15 Bq/l and increased about 70% to 25 Bq/l two days before the seismic event. In about two weeks, they returned to about 18 Bq/l. But, surprisingly, they have gradually increased to about 35 Bq/l, before leveling off at about 27 Bq/l.

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