Flow analysis by using solenoid valves for As(III) determination in natural waters by an on-line separation and pre-concentration system coupled to a tungsten coil atomizer

A flow system coupled to a tungsten coil atomizer in an atomic absorption spectrometer (TCA-AAS) was developed for As(III) determination in waters, by extraction with sodium diethyldithiocarbamate (NaDDTC) as complexing agent, and by sorption of the As(III)-DDTC complex in a micro-column filled with 5 mg C18 reversed phase (10 µL dry sorbent), followed by elution with ethanol. A complete pre-concentration/elution cycle took 208 s, with 30 s sample load time (1.7 mL) and 4 s elution time (71 µL). The interface and software for the synchronous control of two peristaltic pumps (RUN/ STOP), an autosampler arm, seven solenoid valves, one injection valve, the electrothermal atomizer and the spectrometer Read function were constructed. The system was characterized and validated by analytical recovery studies performed both in synthetic solutions and in natural waters. Using a 30 s pre-concentration period, the working curve was linear between 0.25 and 6.0 µg L-1 (r = 0.9976), the retention efficiency was 94±1% (6.0 µg L-1), and the pre-concentration coefficient was 28.9. The characteristic mass was 58 pg, the mean repeatability (expressed as the variation coefficient) was 3.4% (n=5), the detection limit was 0.058 µg L-1 (4.1 pg in 71 µL of eluate injected into the coil), and the mean analytical recovery in natural waters was 92.6 ± 9.5 % (n=15). The procedure is simple, economic, less prone to sample loss and contamination and the useful lifetime of the micro-column was between 200-300 pre-concentration cycles.

Monitoring of praseodymium(III) ions in aqueous solutions, soil and sediment samples by a PVC membrane sensor based on a furan-triazole derivative

A furan-triazole derivative has been explored as an ionophore for preparation of a highly selective Pr(III) membrane sensor. The proposed sensor exhibits a Nernstian response for Pr(III) activity over a wide concentration range with a detection limit of 5.2×10-8 M. Its response is independent of pH of the solution in the range 3.0-8.8 and offers the advantages of fast response time. To investigate the analytical applicability of the sensor, it was applied successfully as an indicator electrode in potentiometric titration of Pr(III) solution and also in the direct and indirect determination of trace Pr(III) ions in some samples.

Preparation and immobilization of diNOsarcobalt(III) complex in zeolite y for the catalyzed production of hydrogen peroxide

A complex cation, diNOsarcobalt(III), [Co(diNOsar)]3+, (diNOsar = 1,8-dinitro-3,6,10,13,16,19-hexaazabicyclo-[6.6.6]eicosane), was synthesized and immobilized in the cavities of a Y zeolite by the reaction of precursor species in the pores of the zeolite. The encapsulated material was compared to the compound diNOsarcobalt(III) chloride, [Co(diNOsar)]Cl3. Both diNOsarcobalt(III) chloride and the zeolite-encapsulated complex, [Co(diNOsar)]3+/zeolite, were obtained in high yield and characterized by ultraviolet-visible and infrared spectroscopy. X-ray diffraction demonstrated the incorporation of the complex cation into the pores of the zeolite. The catalytic production of hydrogen peroxide from oxygenated water confirmed the successful synthesis of the complex diNOsarcobalt(III) immobilized in the zeolite.

Preparation and evaluation of magnetic chitosan particles modified with ethylenediamine and Fe(III) for the removal of Cr(VI) from aqueous solutions

The adsorption of Cr(VI) in aqueous solution by magnetic particles of crosslinked chitosan-ethylenediamine-Fe(III) (MPCh-EDA-FeCL) was studied in a batch system. Fe3+ in the MPCh-EDA-FeCL permitted that adsorption of Cr(VI) occurred with maximum efficiency between pH 3 and 11. The maximum adsorption capacity at pH 7.0 was 81.04 mg g-1 at 25 ºC. The adsorption kinetic process was described by the pseudo-second-order model. Thermodynamic parameters indicated spontaneous, exothermic and chemical adsorption nature. The adsorbent was successively regenerated using a 0.1 mol L-1 NaOH solution. Results were satisfactory for treatment of wastewater from the electroplating industry.

Sorption kinetics and intrapaticulate diffusivity of As(III) bioremediation from aqueous solution, using modified and unmodified coconut fiber

The pollution and toxicity problems posed by arsenic in the environment have long been established. Hence, the removal and recovery remedies have been sought, bearing in mind the efficiency, cost effectiveness and environmental friendliness of the methods employed. The sorption kinetics and intraparticulate diffusivity of As (III) bioremediation from aqueous solution using modified and unmodified coconut fiber was investigated. The amount adsorbed increased as time increased, reaching equilibrium at about 60 minutes. The kinetic studies showed that the sorption rates could be described by both pseudo-first order and pseudo-second order process with the later showing a better fit with a value of rate constant of 1.16 x 10-4 min-1 for the three adsorbent types. The mechanism of sorption was found to be particle diffusion controlled. The diffusion and boundary layer effects were also investigation. Therefore, the results show that coconut fiber, both modified and unmodified is an efficient sorbent for the removal of As (III) from industrial effluents with particle diffusion as the predominant mechanism.

Spectrophotometric study of the chromium(III)/azide system in the ultraviolet region and its analytical application

A sensitive and alternative method for the spectrophotometric determination of chromium(III) based on the formation of chromium(III)/azide complexes was established by investigating a new band in the ultraviolet region. The best experimental conditions for the analytical determination of this metallic ion were: ligand and perchloric acid analytical concentration = 493 and 12.0 mmol L-1, respectively; aqueous medium; T = 25.0 ºC; contact time = 1 hour. The maximum molar absorptivity coefficient occurred at 287 nm (average 1.481 ± 0.008 ´ 10(4) L mol-1 cm-1), leading to the determination of metal ion concentrations one hundred times lower than the ones formerly determined in the visible region. The system obeys Beer's Law and is suitable for chromium determination in the 0.702-2.81 mg L-1 concentration range (15-65% T, 1.00 cm-width quartz cells). Analytical applications of the current method were tested with a nutritional supplement containing chromium. Results were compared with those obtained with atomic absorption spectrometry.

Complexes of 4-chlorophenoxyacetates of Nd(III), Gd(III) and Ho(III)

The complexes of 4-chlorophenoxyacetates of Nd(III), Gd(III) and Ho(III) have been synthesized as polycrystalline hydrated solids, and characterized by elemental analysis, spectroscopy, magnetic studies and also by X-ray diffraction and thermogravimetric measurements. The analysed complexes have the following colours: violet for Nd(III), white for Gd(III) and cream for Ho(III) compounds. The carboxylate groups bind as bidentate chelating (Ho) or bridging ligands (Nd, Gd). On heating to 1173K in air the complexes decompose in several steps. At first, they dehydrate in one step to form anhydrous salts, that next decompose to the oxides of respective metals. The gaseous products of their thermal decomposition in nitrogen were also determined and the magnetic susceptibilites were measured over the temperature range of 76-303K and the magnetic moments were calculated. The results show that 4-chlorophenoxyacetates of Nd(III), Gd(III) and Ho(III) are high-spin complexes with weak ligand fields. The solubility value in water at 293K for analysed 4-chlorophenoxyacetates is in the order of 10-4mol/dm³.

Avaliação das citocinas IL-10 e IL-13 como mediadores na progressão da fibrose de Symmers em portadores de esquistossomose mansônica na forma hepatoesplênica

OBJETIVO: Investigar os níveis de IL-10 e IL-13 no soro de portadores da esquistossomose mansônica na forma hepatoesplênica (EHE), avaliando o papel destas citocinas no desenvolvimento da fibrose hepática. MÉTODOS: O estudo foi prospectivo e analítico, desenvolvido no Departamento de Cirurgia da Universidade Federal de Pernambuco, Laboratório de Imunologia Keizo Asami. Foram estudados três grupos: Grupo I - 25 portadores de esquistossomose mansônica na forma hepatoesplênica e não submetidos a tratamento cirúrgico; Grupo II - 30 submetidos à esplenectomia e ligadura da veia gástrica esquerda; Grupo III - 33 indivíduos sem esquistossomose mansônica na forma hepatoesplênica ou qualquer outra doença ou agravo que comprometesse a reserva funcional hepática. As concentrações séricas de IL-10 e IL-13 foram obtidas pelo método ELISA. Considerando-se a natureza não paramétrica, todas as concentrações foram analisadas pelo teste de Kruskal-Wallis. p<0,05 foi usado para rejeição da hipótese de nulidade. RESULTADOS: As médias das concentrações de IL-10, em ng/mL, no soro foram: GI 50,0 ± 59,0; GII 38,0 ± 270; GIII 38,0 ± 20,0. As concentrações de IL-13, em ng/mL, no soro dos pacientes foram respectivamente: GI 41,0 ± 93,0; GII 16,0 ± 17,0; GIII 18,0 ± 34,0. Não se observou diferença significante entre as médias das concentrações de IL-10 e IL-13 entre os grupos de estudo (p>0,05). CONCLUSÃO: As médias das concentrações séricas de IL-10 e IL-13 foram similares nos três grupos estudados, indicando que, possivelmente, estas citocinas no soro não estejam associadas aos diferentes graus de fibrose de Symmers nos pacientes.

Câncer de vesícula biliar: experiência de 10 anos em um hospital de referência da Amazônia

OBJETIVO: Analisar os aspectos epidemiológicos-cirúrgicos dos pacientes com câncer de vesícula biliar (CAVB) atendidos em um Hospital Universitário de Belém/PA, no período de 1999-2009. MÉTODOS: estudo observacional, retrospectivo, descritivo-analítico de fonte secundária dos pacientes com diagnóstico de CAVB, no período de 1999-2009. Foram analisados 75 prontuários, sendo 34 pacientes estudados. As informações coletadas foram utilizadas para o estadiamento tumoral TNM do CAVB e para a caracterização clínico-cirúrgica da população estudada. RESULTADOS: 79% eram do sexo feminino, com média de idade de 66,2±11 anos e tempo de sintomatologia de 10,8±17,2 meses, não obtendo relação estatística com o estadio da doença. Dor no hipocôndrio direito, náuseas e icterícia predominaram como sinais/sintomas. A litíase biliar esteve presente em 91% dos casos, sendo positiva em 100% dos pacientes com estadios I/II. A sensibilidade ultrassonográfica para sugestionar o CAVB no pré-operatório foi 14,28%. A operação mais executada foi a colecistectomia simples, tendo como achado intra-operatório predominante, invasão hepática. O adenocarcinoma foi o tipo histológico preponderante, com destaque para os estadios III e IV. CONCLUSÃO: A série estudada apresentou alta incidência de litíase biliar, o adenocarcinoma com estadio avançado foi o mais prevalente. acarretando um pequeno índice de operações com intenção curativa, 30% dos pacientes operados, e uma taxa de mortalidade de 21%. A valorização dos sintomas e a investigação precoce por exames de imagem poderiam favorecer o tratamento, em fases iniciais do CAVB, proporcionando um melhor prognóstico para os pacientes operados.

The calcium-modulated proteins, S100A1 and S100B, as potential regulators of the dynamics of type III intermediate filaments

The Ca2+-modulated, dimeric proteins of the EF-hand (helix-loop-helix) type, S100A1 and S100B, that have been shown to inhibit microtubule (MT) protein assembly and to promote MT disassembly, interact with the type III intermediate filament (IF) subunits, desmin and glial fibrillary acidic protein (GFAP), with a stoichiometry of 2 mol of IF subunit/mol of S100A1 or S100B dimer and an affinity of 0.5-1.0 µM in the presence of a few micromolar concentrations of Ca2+. Binding of S100A1 and S100B results in inhibition of desmin and GFAP assemblies into IFs and stimulation of the disassembly of preformed desmin and GFAP IFs. S100A1 and S100B interact with a stretch of residues in the N-terminal (head) domain of desmin and GFAP, thereby blocking the head-to-tail process of IF elongation. The C-terminal extension of S100A1 (and, likely, S100B) represents a critical part of the site that recognizes desmin and GFAP. S100B is localized to IFs within cells, suggesting that it might have a role in remodeling IFs upon elevation of cytosolic Ca2+ concentration by avoiding excess IF assembly and/or promoting IF disassembly in vivo. S100A1, that is not localized to IFs, might also play a role in the regulation of IF dynamics by binding to and sequestering unassembled IF subunits. Together, these observations suggest that S100A1 and S100B may be regarded as Ca2+-dependent regulators of the state of assembly of two important elements of the cytoskeleton, IFs and MTs, and, potentially, of MT- and IF-based activities.

Systematic head and neck physical examination as a predictor of obstructive sleep apnea in class III obese patients

Our aim was to determine if anatomical abnormalities of the upper airway (UA) and facial skeleton of class III severely obese patients are related to the presence and severity of obstructive sleep apnea syndrome (OSAS). Forty-five patients (69% females, mean age 46.5 ± 10.8 years) with a body mass index (BMI) over 40 kg/m² underwent UA and facial skeletal examinations as well as polysomnography. Mean BMI was 49 ± 7 kg/m² and mean neck circumference was 43.4 ± 5.1 cm. Polysomnographic findings showed that 22% had a normal apnea-hypopnea index (AHI) and 78% had an AHI over 5. The presence of OSAS was associated with younger age (P = 0.02), larger neck circumference (P = 0.004), presence of a voluminous lateral wall (P = 0.0002), posteriorized soft palate (P = 0.0053), thick soft palate (P = 0.0014), long uvula (P = 0.04), thick uvula (P = 0.0052), and inferior turbinate hypertrophy (P = 0.04). A larger neck circumference (P = 0.02), presence of a voluminous lateral wall (P = 0.04), posteriorized soft palate (P = 0.03), and thick soft palate (P = 0.04) were all associated with OSAS severity. The prevalence of OSAS in this group was high. A larger neck circumference and soft tissue abnormalities of the UA were markers for both the presence and severity of OSAS. Conversely, no abnormalities in the facial skeleton were associated with OSAS in patients with morbid obesity.

Collagen content, but not the ratios of collagen type III/I mRNAs, differs among hypertensive, alcoholic, and idiopathic dilated cardiomyopathy

Cardiac interstitial fibrosis may contribute to ventricular dysfunction and the prognosis of patients with dilated cardiomyopathy. The objective of the present study was to determine if total myocardial collagen content and collagen type III/I (III/I ratio) mRNAs differ in hypertensive, alcoholic, and idiopathic dilated cardiomyopathy subjects. Echocardiography and exercise cardiopulmonary testing were performed in patients with idiopathic (N = 22), hypertensive (N = 12), and alcoholic (N = 11) dilated cardiomyopathy. Morphometric analysis of collagen was performed in fragments obtained by endomyocardial biopsy with picrosirius red staining. The collagen III/I ratio was determined by reverse transcription polymerase chain reaction. Samples of controls (N = 10) were obtained from autopsy. Echocardiographic variables and maximal oxygen uptake were not different among dilated cardiomyopathy groups. Collagen was higher in all dilated cardiomyopathy groups (idiopathic, hypertensive and alcoholic, 7.36 ± 1.09%) versus controls (1.12 ± 0.18%), P < 0.05. Collagen was lower in idiopathic dilated cardiomyopathy (4.97 ± 0.83%) than hypertensive (8.50 ± 1.11%) and alcoholic (10.77 ± 2.09%) samples (P < 0.005 for both). The collagen III/I ratio in all samples from dilated cardiomyopathy patients was higher compared to that in controls (0.29 ± 0.04, P < 0.05) but was the same in the samples from idiopathic (0.77 ± 0.07), hypertensive (0.75 ± 0.07), and alcoholic (0.81 ± 0.16) dilated cardiomyopathy groups. Because of the different physical properties of the types of collagen, the higher III/I ratio may contribute to progressive ventricular dilation and dysfunction in dilated cardiomyopathy patients.

Optimization and validation of a methodology to determine total arsenic, As(III) and As(V), in water samples, through graphite furnace atomic absorption spectrometry

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.