952 resultados para vision in water
Resumo:
This paper discusses a rapid and sensitive method developed to determine trace levels of mercury in natural water samples by cold vapor atomic absorption spectrometry using a preconcentration system composed by mini-column packed with 100 mg of 2-aminothiazol modified silica gel (SiAT) coupled on-line with the spectrometer's cold vapor generator system. The optimum preconcentration conditions are also described here. The preconcentrated Hg(II) ions were eluted directly from the column to the spectrometer's cold vapor generator system using 100 µL of 2 mol L-1 hydrochloric acid and the retention efficiency achieved exceeded 95%. The enrichment factors determined were 29, 38 and 46 using 3, 4 and 5 mL of preconcentrated aqueous solutions containing 400 ng L-1 of Hg. The detection limit calculated was 5 ng L-1. The preconcentration procedure was applied to determine trace level mercury in spiked river water samples.
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Frequent traffic of tractors in agricultural soils, promotes soil compaction and affects the flow and water availability. The aim of this research was to study the effect of compaction induced by tractor traffic on water availability in the soil under different traffic intensities on the same path (0, 1, 3, 6 and 10 passages), to two tractors with 3.3 and 2.6 ton of weights, over three different surface conditions. The study was conducted in an Andisol, representative soil of the study area. It was determined the behavior of the water retention curve, obtaining the gravitational water, available water and hygroscopic water, to 10 and 30 cm of depth. The hygroscopic water is the most prevalent with values of up to 80% of the total water present in the soil. The water retention curves showed increases in the values of field capacity and wilting point and behaviors "flattened" indicating a high sensitivity to the applied treatments, representative of compacted soils, which give the surfaces studied characteristics do not suitable for normal crop development.
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Atrioventricular valve complex of 30 Jafarabadi water buffaloes, adult males were studied in this research with no heart diseases. The animals were obtained from a slaughterhouse in Brazilian State of Parana. The hearts were opened at the third portion affording access to the valve complex. The complexes had its area, number and type of tendinous cords submitted to analysis. The results showed that the complex is composed by two cusps and four accessory cusps, two or three papillary muscles in which 10-25 tendinous cords fix on the cusps that face the ventricle wall. The total area of the complex was on average 38.56cm², with a minimum of 24.96cm² and a maximum of 55.54cm². Statistically, no relation between the number of cords and the cusps' area where they are inserted or with the number of papillary muscle where they originated from was observed.
Resumo:
In this work, a controller for regulating the transients in water distribution networks is established. The control technique is the H¥ Control. The developed controller is applied to a water distribution network and the results of this application demonstrate that the technique allowed the establishment of a robust controller, capable of attenuating the disturbances in a suitable way, being effective in controlling the oscillations of the state variables in question.
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In recent decades, industrial activity growth and increasing water usage worldwide have led to the release of various pollutants, such as toxic heavy metals and nutrients, into the aquatic environment. Modified nanocellulose and microcellulose-based adsorption materials have the potential to remove these contaminants from aqueous solutions. The present research consisted of the preparation of five different nano/microcellulose-based adsorbents, their characterization, the study of adsorption kinetics and isotherms, the determination of adsorption mechanisms, and an evaluation of adsorbents’ regeneration properties. The same well known reactions and modification methods that were used for modifying conventional cellulose also worked for microfibrillated cellulose (MFC). The use of succinic anhydride modified mercerized nanocellulose, and aminosilane and hydroxyapatite modified nanostructured MFC for the removal of heavy metals from aqueous solutions exhibited promising results. Aminosilane, epoxy and hydroxyapatite modified MFC could be used as a promising alternative for H2S removal from aqueous solutions. In addition, new knowledge about the adsorption properties of carbonated hydroxyapatite modified MFC as multifunctional adsorbent for the removal of both cations and anions ions from water was obtained. The maghemite nanoparticles (Fe3O4) modified MFC was found to be a highly promising adsorbent for the removal of As(V) from aqueous solutions due to its magnetic properties, high surface area, and high adsorption capacity . The maximum removal efficiencies of each adsorbent were studied in batch mode. The results of adsorption kinetics indicated very fast removal rates for all the studied pollutants. Modeling of adsorption isotherms and adsorption kinetics using various theoretical models provided information about the adsorbent’s surface properties and the adsorption mechanisms. This knowledge is important for instance, in designing water treatment units/plants. Furthermore, the correspondence between the theory behind the model and properties of the adsorbent as well as adsorption mechanisms were also discussed. On the whole, both the experimental results and theoretical considerations supported the potential applicability of the studied nano/microcellulose-based adsorbents in water treatment applications.
Resumo:
In the present study we evaluated the nature of angiotensin receptors involved in the antidiuretic effect of angiotensin-(1-7) (Ang-(1-7)) in water-loaded rats. Water diuresis was induced in male Wistar rats weighing 280 to 320 g by water load (5 ml/100 g body weight by gavage). Immediately after water load the rats were treated subcutaneously with (doses are per 100 g body weight): 1) vehicle (0.05 ml 0.9% NaCl); 2) graded doses of 20, 40 or 80 pmol Ang-(1-7); 3) 200 nmol Losartan; 4) 200 nmol Losartan combined with 40 pmol Ang-(1-7); 5) 1.1 or 4.4 nmol A-779; 6) 1.1 nmol A-779 combined with graded doses of 20, 40 or 80 pmol Ang-(1-7); 7) 4.4 nmol A-779 combined with graded doses of 20, 40 or 80 pmol Ang-(1-7); 8) 95 nmol CGP 42112A, or 9) 95 nmol CGP 42112A combined with 40 pmol Ang-(1-7). The antidiuretic effect of Ang-(1-7) was associated with an increase in urinary Na+ concentration, an increase in urinary osmolality and a reduction in creatinine clearance (CCr: 0.65 ± 0.04 ml/min vs 1.45 ± 0.18 ml/min in vehicle-treated rats, P<0.05). A-779 and Losartan completely blocked the effect of Ang-(1-7) on water diuresis (2.93 ± 0.34 ml/60 min and 3.39 ± 0.58 ml/60 min, respectively). CGP 42112A, at the dose used, did not modify the antidiuretic effect of Ang-(1-7). The blockade produced by Losartan was associated with an increase in CCr and with an increase in sodium and water excretion as compared with Ang-(1-7)-treated rats. When Ang-(1-7) was combined with A-779 there was an increase in CCr and natriuresis and a reduction in urine osmolality compared with rats treated with Ang-(1-7) alone. The observation that both A-779, which does not bind to AT1 receptors, and Losartan blocked the effect of Ang-(1-7) suggests that the kidney effects of Ang-(1-7) are mediated by a non-AT1 angiotensin receptor that is recognized by Losartan.
Resumo:
In this study we investigated the effects of the injection into the supraoptic nucleus (SON) of non-peptide AT1- and AT2-angiotensin II (ANG II) receptor antagonists, DuP753 and PD123319, as well as of the arginine-vasopressin (AVP) receptor antagonist d(CH2)5-Tyr(Me)-AVP, on water and 3% NaCl intake induced by the injection of ANG II into the medial septal area (MSA). The effects on water or 3% NaCl intake were assessed in 30-h water-deprived or in 20-h water-deprived furosemide-treated adult male rats, respectively. The drugs were injected in 0.5 µl over 30-60 s. Controls were injected with a similar volume of 0.15 M NaCl. Antagonists were injected at doses of 20, 80 and 180 nmol. Water and sodium intake was measured over a 2-h period. Previous administration of the AT1 receptor antagonist DuP753 into the SON decreased water (65%, N = 10, P<0.01) and sodium intake (81%, N = 8, P<0.01) induced by the injection of ANG II (10 nmol) into the MSA. Neither of these responses was significantly changed by injection of the AT2-receptor antagonist PD123319 into the SON. On the other hand, while there was a decrease in water intake (45%, N = 9, P<0.01), ANG II-induced sodium intake was significantly increased (70%, N = 8, P<0.01) following injection of the V1-type vasopressin antagonist d(CH2)5-Tyr(Me)-AVP into the SON. These results suggest that both AT1 and V1 receptors within the SON may be involved in water and sodium intake induced by the activation of ANG II receptors within the MSA. Furthermore, they do not support the involvement of MSA AT2 receptors in the mediation of these responses.
Resumo:
Tavallisten hapetusmenetelmien sijasta kehittyneitä hapetusmenetelmiä (AOP) on kehitetty yhä enemmän, jotta hapetusprosessista tulisi kannattavampi, tehokkaampi, ympäristöystävällisempi ja sitä voitaisiin hyödyntää laajalti eri paikoissa. Uusi teknologia, joka käyttää otsonia ja hydroksyyliradikaalia sähköimpulssien kanssa, on yksi mahdollinen tehokkaampi vedenkäsittelymentelmä. Kyseistä menetelmää kutsutaa pulsed corona discharge (PCD) -menetelmäksi, joka käyttää prosessissa muodostuvia otsonia ja hydroksyyliradikaalia hapettavina tekijöinä. Tässä työssä tutkittiin nitraatin muodostumista vedessä, kun vettä käsiteltiin PCD-laitteessa ja, kun oksalaatti- ja formaatti-ioneja oli sekoittuneina veteen. Nitraatteja muodostuu PCD–laitteessa veteen, kun ilman typpi reagoi hapettimina toimivien otsonin ja hydroksyyliradikaalin kanssa. Aiemmissa tutkimuksissa nitraatin muodostumisen on todistettu parantuvan, kun karboksyylihapot muurahais- ja oksaalihappo ovat sekoittuneina veteen. Tässä tutkimuksessa tarkoituksena oli tutkia, miten formaatti- ja oksalaatti-ionien, joiden pitoisuudet olivat 0 ppm, 50 ppm ja 100 ppm, läsnäolo vedessä vaikuttaa nitraatin muodostumiseen. PCD-kokeista saadut näytteet analysoitiin ionikromatografilla. Kyseisessä tutkimuksessa nitraatin muodostuminen oli samansuuruista jokaisessa kokeessa hapetusajan kasvaessa samalla, kun otettujen näytteiden pH-arvot laskivat. Tuloksena voitiin pitää sitä, ettei formaatti- tai oksalaatti-ioneilla ollut vaikutusta nitraatti-ionien muodostumiseen.
Resumo:
The Graphite furnace atomic absorption spectrometry (GF AAS) was the technique chosen by the inorganic contamination laboratory (INCQ/ FIOCRUZ) to be validated and applied in routine analysis for arsenic detection and quantification. The selectivity, linearity, sensibility, detection, and quantification limits besides accuracy and precision parameters were studied and optimized under Stabilized Temperature Platform Furnace (STPF) conditions. The limit of detection obtained was 0.13 µg.L-1 and the limit of quantification was 1.04 µg.L-1, with an average precision, for total arsenic, less than 15% and an accuracy of 96%. To quantify the chemical species As(III) and As(V), an ion-exchange resin (Dowex 1X8, Cl- form) was used and the physical-chemical parameters were optimized resulting in a recuperation of 98% of As(III) and of 90% of As(V). The method was applied to groundwater, mineral water, and hemodialysis purified water samples. All results obtained were lower than the maximum limit values established by the legal Brazilian regulations, in effect, 50, 10, and 5 µg.L-1 para As total, As(III) e As(V), respectively. All results were statistically evaluated.
Resumo:
In this study, food emulsions of oil in water from sesame (Sesamum indicum) protein isolates and their oil were formulated and standardised. The effect of the concentrations of sesame (Sesamum indicum) protein isolates and base oil and the speed of the emulsification process for the food emulsion stability was studied. The protein isolates were achieved from the defatted sesame flour (DSF), obtaining a percentage of 80% ± 0.05% of protein. Emulsions were formulated through a factorial design 23. The rheological behaviour of sesame (Sesamum indicum) protein isolates-stabilised emulsions and microstructural composition were investigated. Stable emulsions with suitable rheological properties and microstructure were formulated at a concentration of 10% sesame oil and different concentrations of protein isolates, between 1.5% and 2.5%, with the best droplet distribution characteristics being shown for the 2.5% sesame protein isolates. The emulsions showed a non-Newtonian fluid behaviour, adjusting the Sisko model.
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Several automated reversed-phase HPLC methods have been developed to determine trace concentrations of carbamate pesticides (which are of concern in Ontario environmental samples) in water by utilizing two solid sorbent extraction techniques. One of the methods is known as on-line pre-concentration'. This technique involves passing 100 milliliters of sample water through a 3 cm pre-column, packed with 5 micron ODS sorbent, at flow rates varying from 5-10 mUmin. By the use of a valve apparatus, the HPLC system is then switched to a gradient mobile phase program consisting of acetonitrile and water. The analytes, Propoxur, Carbofuran, Carbaryl, Propham, Captan, Chloropropham, Barban, and Butylate, which are pre-concentrated on the pre-column, are eluted and separated on a 25 cm C-8 analytical column and determined by UV absorption at 220 nm. The total analytical time is 60 minutes, and the pre-column can be used repeatedly for the analysis of as many as thirty samples. The method is highly sensitive as 100 percent of the analytes present in the sample can be injected into the HPLC. No breakthrough of any of the analytes was observed and the minimum detectable concentrations range from 10 to 480 ng/L. The developed method is totally automated for the analysis of one sample. When the above mobile phase is modified with a buffer solution, Aminocarb, Benomyl, and its degradation product, MBC, can also be detected along with the above pesticides with baseline resolution for all of the analytes. The method can also be easily modified to determine Benomyl and MBC both as solute and as particulate matter. By using a commercially available solid phase extraction cartridge, in lieu of a pre-column, for the extraction and concentration of analytes, a completely automated method has been developed with the aid of the Waters Millilab Workstation. Sample water is loaded at 10 mL/min through a cartridge and the concentrated analytes are eluted from the sorbent with acetonitrile. The resulting eluate is blown-down under nitrogen, made up to volume with water, and injected into the HPLC. The total analytical time is 90 minutes. Fifty percent of the analytes present in the sample can be injected into the HPLC, and recoveries for the above eight pesticides ranged from 84 to 93 percent. The minimum detectable concentrations range from 20 to 960 ng/L. The developed method is totally automated for the analysis of up to thirty consecutive samples. The method has proven to be applicable to both purer water samples as well as untreated lake water samples.
Resumo:
An efficient way of synthesizing the deuterium labelled analogues of three methoxypyrazine compounds: 2-d3-methoxy-3-isopropylpyrazine, 2-d3-methoxy-3- isobutylpyrazine, and 2-d3-methoxy-3-secbutylpyrazine, has been developed. To confirm that the deuterium labels had been incorporated into the expected positions in the molecules synthesized, the relevant characterization by NMR, HRMS and GC/MS analysis was conducted. Another part of this work involved quantitative determination of methoxypyrazines in water and wines. Solid-phase extraction (SPE) proved to be a suitable means for the sample separation and concentration prior to GC/MS analysis.Such factors as the presence of ethanol, salt, and acid have been investigated which can influence the recovery by SPE for the pyrazines from the water matrix. Significantly, in this work comparatively simple fractional distillation was attempted to replace the conventional steam distillation for pre-concentrating a sample with a relatively large volume prior to SPE. Finally, a real wine sample spiked with the relevant isotope-labelled methoxypyrazines was quantitatively analyzed, revealing that the wine with 10 beetles per litre contained 138 ppt of 2-methoxy-3-isopropylpyrazine. Interestingly, we have also found that 2-methoxy-3-secbutylpyrazine exhibits an extremely low detection limit in GC/MS analysis compared with the detection limit of the other two methoxypyrazines: 2- methoxy-3-isopropylpyrazine and 2-methoxy-3-isobutylpyrazine.
Resumo:
Flow injection analysis (FIA) was applied to the determination of both chloride ion and mercury in water. Conventional FIA was employed for the chloride study. Investigations of the Fe3 +/Hg(SCN)2/CI-,450 nm spectrophotometric system for chloride determination led to the discovery of an absorbance in the 250-260 nm region when Hg(SCN)2 and CI- are combined in solution, in the absence of iron(III). Employing an in-house FIA system, absorbance observed at 254 nm exhibited a linear relation from essentially 0 - 2000 Jlg ml- 1 injected chloride. This linear range spanning three orders of magnitude is superior to the Fe3+/Hg(SCN)2/CI- system currently employed by laboratories worldwide. The detection limit obtainable with the proposed method was determin~d to be 0.16 Jlg ml- 1 and the relative standard deviation was determined to be 3.5 % over the concentration range of 0-200 Jig ml- 1. Other halogen ions were found to interfere with chloride determination at 254 nm whereas cations did not interfere. This system was successfully applied to the determination of chloride ion in laboratory water. Sequential injection (SI)-FIA was employed for mercury determination in water with the PSA Galahad mercury amalgamation, and Merlin mercury fluorescence detection systems. Initial mercury in air determinations involved injections of mercury saturated air directly into the Galahad whereas mercury in water determinations involved solution delivery via peristaltic pump to a gas/liquid separator, after reduction by stannous chloride. A series of changes were made to the internal hardware and valving systems of the Galahad mercury preconcentrator. Sequential injection solution delivery replaced the continuous peristaltic pump system and computer control was implemented to control and integrate all aspects of solution delivery, sample preconcentration and signal processing. Detection limits currently obtainable with this system are 0.1 ng ml-1 HgO.
Resumo:
Campylobacter jejuni cause gastroenteritis in humans. The main transmission vector is the consumption or handling of contaminated chicken meat, since chicken can be colonized asymptomatically by C. jejuni. However, water has been implicated as the transmission vector in a few outbreaks. One possibility is the contamination of water effluent by C. jejuni originating from chicken farm. The ability of C. jejuni to be transmitted by water would be closely associated to its ability to survive in water. Therefore, in this study, we have evaluated the ability of reference strains and chickenisolated strains to survive in water. Defined water media were used, since the composition of tap water is variable. We showed that some isolates survive better than others in defined freshwater (Fraquil) and that the survival was affected by temperature and the concentration of NaCl. By comparing the ability of C. jejuni to survive in water with other phenotypic properties previously tested, we showed that the ability to survive in water was negatively correlated with autoagglutination. Our data showed that not all chicken isolates have the same ability to survive in water, which is probably due to difference in genetic content.