895 resultados para total arsenic


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The first total synthesis of the indole alkaloids ()-aplicyanins A, B and E, plus seventeen analogs, all in racemic form is reported. Modifications to the parent compound included changing the number of bromine substituents on the indole, the groups on the indole nitrogen (H, Me or OMe), and/or the oxidation level of the heterocyclic core tetrahydropyrimidine. Each compound was screened against three human tumor cell lines, and fourteen of the newly synthesized compounds showed considerable cytotoxicity. The assay results were used to establish structure-activity relationships. These results suggest that the acetyl group moiety on the imine nitrogen, and the bromine at position 5 of the indole, are both critical to activity.

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In modern day organizations there are an increasing number of IT devices such as computers, mobile phones and printers. These devices can be located and maintained by using specialized IT management applications. Costs related to a single device accumulate from various sources and are normally categorized as direct costs like hardware costs and indirect costs such as labor costs. These costs can be saved in a configuration management database and presented to users using web based development tools such as ASP.NET. The overall costs of IT devices during their lifecycle can be ten times higher than the actual purchase price of the product and ability to define and reduce these costs can save organizations noticeable amount of money. This Master’s Thesis introduces the research field of IT management and defines a custom framework model based on Information Technology Infrastructure Library (ITIL) best practices which is designed to be implemented as part of an existing IT management application for defining and presenting IT costs.

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This study presents an automated system for potentiometric determination of free and total cyanide which employs a homogeneous membrane tubular ion-selective electrode. After the electrode is assembled, it is connected to a system composed of 3 three-way solenoid valves, sample line, carrier line, acid stream, and gas diffusion chamber. A Turbo Pascal® computer program, developed specifically for this task, automatically performs all the steps involved in data acquisition and processing. The proposed analytical procedure offers operational simplicity, since detection is performed by a tubular electrode, whose assembly is fast and easy. The system has shown reproducibility (r.s.d. < 0.5%, n=6) and high speed (30 readings/hour); it is efficient for determination of free and total cyanide in waste waters of starch processing plants. The detection limit was 1.2x10-5 and 1.5x10-5 mol L-1, for determination of free and total cyanide, respectively. The linear response range was between 1.2x10-5 and 1.0x10-2 mol L-1 for free cyanide and between 1.5x10-5 and 1.0x10-2 for total cyanide.

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Iron and arsenic oxide grains are coated with the conducting organic polymer polyaniline. The obtained samples were characterized by infrared spectroscopy, SEM, conducting measurements and thermogravimetry. The thermal stability of both oxides are increased. For As2O3 the sublimation temperature is increased from 165ºC in the pure oxide to 206ºC in the polymer modified sample. The pure Fe3O4 sample exhibits sublimation at 780ºC whereas the polyaniline coated oxide is stable until at least 1000ºC.

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A sensitive and simple system was proposed for the in situ measurement of total aldehyde in outdoor or indoor ambient. The method is based on the use of a reagent drop as an useful interface to preconcentrate the sample prior to determination of total aldehyde as formaldehyde. The drop is formed at the tip of a cylindrical tube that contains two optical fibers placed on opposite sides and in contact with the reagent solution. One optical fiber carries the red light to the drop form a light emitting diode (LED). The transmitted light is measured by a second optical fiber/photodiode system. The analytical signal is read and converted into absorbance. The reagent solution of 3-methyl-2-benzothiazoline hydrazone (MBTH) forms a blue cation during reaction with formaldehyde that can be measured at 660 nm. Some aspects of kinetics reaction formation of dye were reevaluated. The formaldehyde reacts with MBTH and forms the azine in about 12 min. The oxidation of MBTH by Fe (III) and the formation of dye requires 3 min. The absorbance of the reagent drop is proportional to the sampling time and to the analyte concentration. The absorbance signal increases with increased sample gas flow until a maximum is reached then decreases until it forms a plateau. The proposed method was evaluated using both outdoor and indoor samples, and it was shown to viable provide an accurate measure of total aldehyde.

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Infection is one of the most serious complications after total knee arthroplasty (TKA). The current incidence of prosthetic knee infection is 1-3%, depending on the series(.) For treatment and control to be more cost effective, multidisciplinary groups made up of professionals from different specialities who can work together to eradicate these kinds of infections need to be assembled. About the microbiology, Staphylococcus aureus and coagulase-negative staphylococcus were among the most frequent microorganisms involved (74%). Anamnesis and clinical examination are of primary importance in order to determine whether the problem may point to a possible acute septic complication. The first diagnosis may then be supported by increased CRP and ESR levels. The surgical treatment for a chronic prosthetic knee infection has been perfectly defined and standardized, and consists in a two-stage implant revision process. In contrast, the treatment for acute prosthetic knee infection is currently under debate. Considering the different surgical techniques that already exist, surgical debridement with conservation of the prosthesis and polythene revision appears to be an attractive option for both surgeon and patient, as it is less aggressive than the two-stage revision process and has lower initial costs. The different results obtained from this technique, along with prognosis factors and conclusions to keep in mind when it is indicated for an acute prosthetic infection, whether post-operative or haematogenous, will be analysed by the authors.

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Larnellarins are a group of marine natural products isolated from the prosobranch mollusc Lamellaria sp., the ascidian Didemnum sp., and the sponge Dendrilla Cactos. Several of them exhibit interesting biological activities. Natural as well as synthetic lamellarins should be excellent candidates for the development of new drugs due to their unique skeletal structure and their important biological activities especially as antitumor agents. Lamelarin O has been recently characterized as a topoisomerase 1-targeted anti tumor agent. A variety of synthetic approaches have been developed for this family of alkaloids. Herein we describe a new route to the synthesis of Lamellarin D, from a methyl 2-pyrrolecarboxylate. Transformation of the starting material into the scaffold, a substituted 5,6-dihydropyrrolo (2,l ­a)isoquinoline (5,6-DHPl), was afforded by N-alkylation followed by intramolecular Heck cyclization. From this scaffold the synthetic strategy is based on two sequential regioselective bromination!Suzuki cross-coupling reactions which permitted the introduction of differently substituted aryl groups on positions 1 and 2 followed by oxidation, deprotection, and lactonization.

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This paper investigates the extent to which the gap in total factor productivity between small and large firms is due to differences in the endowment of factors determining productivity and to the returns associated with these factors. We place particular emphasis on the contribution of differences in the propensity to innovate and in the use of skilled labor across firms of different size. Empirical evidence from a representative sample of Spanish manufacturing firms corroborates that both differences in endowments and returns to innovation and skilled labor significantly contribute to the productivity gap between small and large firms. In addition, it is observed that the contribution of innovation to this gap is caused only by differences in quantity, while differences in returns have no effect; in the case of human capital, however, most of the effect can be attributed to increasing differences in returns between small and large firms.

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The monitoring of the pollution status of the Brazilian coast is hampered by the lack of a consistent environmental indicator. We propose Hg as an environmental proxy to anthropogenic pollution of coastal regions due to its absence in the Brazilian geology, its ubiquity in anthropogenic effluents, and its toxicity. Available data suggest Hg "backgrounds" in coastal sediments of 1-10 ng g-1, in the East and 15-30 ng g-1 in the South. We suggest short sediment cores to establish these values estimating a geo-accumulation index to compare all areas. The distribution of index values showed the majority of southern coast at least moderately contaminated whereas many eastern areas are still pristine.

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Thermospray flame furnace Atomic Absorption Spectrometry (TS-FF-AAS) was used for the total determination of Cd, Pb and Zn in fresh water and seawater samples at µg L-1 levels, and in marine sediment samples at µg g-1 levels. Using a sample loop of 50 µL and a peristaltic pump the samples were transported into the metallic tube placed over an air/acetylene flame, through a ceramic capillary (o.d. = 3.2 mm) containing two parallel internal orifices (i.d = 0.5 mm). The detection limits determined for Cd, Pb and Zn using a synthetic water matrix (2.5% m/v NaCl, 0.5% m/v MgCl2 and 0.8% m/v CaCl2) were 0.32 µg L-1; 2.6 µg L-1 and 0.21 µg L-1 respectively. The methodology by TS-FF-AAS was validated by determination of Cd, Pb and Zn in certified reference materials of water and marine sediment, and the t-test for differences between means was applied. No statistically significant differences were established in fresh water and seawater (p>0.05), whereas differences became apparent in marine sediment (p<0.03).

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Several extraction procedures are described for the determination of exchangeable and fixed ammonium, nitrate + nitrite, total exchangeable nitrogen and total nitrogen in certified reference soils and petroleum reservoir rock samples by steam distillation and indophenol method. After improvement of the original distillation system, an increase in worker safety, a reduction in time consumption, a decrease of 73% in blank value and an analysis without ammonia loss, which could possibly occur, were achieved. The precision (RSD < 8%, n = 3) and the detection limit (9 mg kg-1 NH4+-N) are better than those of published procedures.

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In this work a fast method for the determination of the total sugar levels in samples of raw coffee was developed using the near infrared spectroscopy technique and multivariate regression. The sugar levels were initially obtained using gravimety as the reference method. Later on, the regression models were built from the near infrared spectra of the coffee samples. The original spectra were pre-treated according to the Kubelka-Munk transformation and multiplicative signal correction. The proposed analytical method made possible the direct determination of the total sugar levels in the samples with an error lower by 8% with respect to the conventional methodology.

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Total Hg content in soils of Baixada Santista, affected by different sources of pollution, and Cardoso Island, which is almost free of anthropogenic activities, were determined by CVAAS. To explain the fate of Hg in the ecosystem, pH, Eh, AVS, Stotal and Total Organic Carbon were also obtained throughout the soil profiles. With the exception of two sampling sites the average content of Hg in samples obtained for Baixada Santista was 0.34 ± 0.20 mg kg-1, which was close to the average data at Cardoso Island (0.30 ± 0.21 mg kg-1). Both of them were below the limit established by CETESB - 0.50 mg kg-1.

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Valtimotautiriskin arviointi verenpainepotilailla Valtimotaudit ovat yleisin kuolinsyy koko maailmassa. Väestön elintapojen muuttuminen ja ikääntyminen uhkaavat edelleen lisätä valtimotautien esiintyvyyttä. Kokemäenjokilaakson valtimotautien ehkäisyprojektin tavoitteena oli löytää 45–70-vuotiaasta väestöstä henkilöt, joilla on kohonnut riski sairastua valtimotauteihin. Kaksivaiheisen seulontamenetelmän avulla voitiin terveydenhoitajan antama elintapaneuvonta kohdistaa riskihenkilöihin ja rajoittaa lääkärin vastaanoton tarve niihin potilaisiin, jotka todennäköisesti hyötyvät ennaltaehkäisevästä lääkityksestä. Suomalainen tyypin 2 diabeteksen sairastumisriskin arviointikaavake ja hoitajan toteama kohonnut verenpaine osoittautuivat käytännöllisiksi menetelmiksi seuloa väestöstä riskihenkilöitä. Valtimotautien ehkäisyprojektissa Harjavallassa ja Kokemäellä todettiin verenpainetauti 1 106 henkilöllä, jotka eivät sairastaneet valtimotautia tai aiemmin todettua diabetesta. Heidän tutkimustulostensa avulla voidaan arvioida kohonneen verenpaineen vaikutusta sokeriaineenvaihduntaan ja verenpaineen aiheuttamiin kohde-elinvaurioihin. Sokeriaineenvaihdunnan häiriöt ovat verenpainetautia sairastavilla yleisempiä kuin väestössä muutoin. Käyttämällä metabolisen oireyhtymän kriteerejä sokerirasituskokeen suorittamisen edellytyksenä voidaan tutkimusten määrää vähentää kolmanneksella ja silti löytää lähes kaikki diabetesta tai sen esiastetta sairastavat verenpainepotilaat. Verenpainepotilaista etenkin metabolista oireyhtymää sairastavilla naisilla on suurentunut munuaisten vajaatoiminnan riski. Jos verenpainepotilaan munuaisten toimintaa arvioidaan pelkästään plasman kreatiniini -arvon perusteella, kolme neljästä munuaisten vajaatoimintaa potevasta jää toteamatta verrattuna laskennallisen glomerulusten suodattumisnopeuden määritykseen seulontamenetelmänä. Joka kolmannella verenpainetautia sairastavalla voidaan todeta alaraajavaltimoiden kovettumista; useammin niillä, joiden ylä- ja alaverenpaineen erotus, pulssipaine on yli 65 mmHg. Verenpainetauti on itsenäinen perifeerisen valtimotaudin vaaratekijä. Tutkimuksessa käytetty menetelmä nilkka-olkavarsipainesuhteen määrittämiseksi soveltunee hyvin perusterveydenhuollon käyttöön riskihenkilöiden löytämiseksi. Valtimotautien kokonaisriskin arviointimenetelmät tai uuden riskitekijän, herkän C-reaktiivisen proteiinin määritys eivät voi korvata kohde-elinvaurioiden mittaamista verenpainepotilaan valtimotautiriskin huolellisessa arvioinnissa.

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The present work investigated the effect of coprecipitation-oxidant synthesis on the specific surface area of perovskite-type oxides LaBO3 (B= Mn, Ni, Fe) for total oxidation of ethanol. The perovskite-type oxides were characterized by X-ray diffraction, nitrogen adsorption (BET method), thermogravimetric analysis (TGA-DTA), TPR and X-ray photoelectron spectroscopy (XPS). Through method involving the coprecipitation-oxidant was possible to obtain catalysts with different BET specific surface areas, of 33-51 m²/g. The results of the catalytic test confirmed that all oxides investigated in this work have specific catalytic activity for total oxidation of ethanol, though the temperatures for total conversion change for each transition metal.