An undergraduate organic chemistry experiment for oil extraction and biodiesel production using alternative biomass was developed, whereby oils of avocado, coconut and spent coffee grounds were obtained and submitted to transesterification reaction with CH3OH under NaOH catalysis. Avocado and coffee oils were obtained by typical extraction and coconut oil was obtained through water evaporation of coconut milk in a domestic microwave oven. The commercial oil of licuri (Syagrus coronate), a Brazilian native biomass, was also converted to biodiesel. All four oils and four biodiesels were characterized by 1H-NMR and FTIR, and a comparative study of these spectra reveled that FTIR analyses alone provides enough information to discriminate between oil and biodiesel and confirm transesterification reaction. Besides, the unsaturation degree of all oils was determined by 1H-NMR. A mechanistic proposal concerning the role of NaOH catalysis is presented, excluding the sodium methoxide formation.

Objectives Iodine deficiency disorder (IDD) is the result of an inadequate dietary intake of iodine, which physiological consequences are endemic goiter and thyroid dysfunction. The objective of this study was to a analyze studies that assessed the status of Brazil’s population iodine nutrition and IDD prevalence. Materials and methods Systematic review using PRISMA statement. Electronic database: PubMed, Medline, SciELO and Lilacs. Quality of studies: Newcastle-Ottawa Scale. Meta-analysis was carried out with R Core Team Statistical Software, version 3.1.0 (2014). The summary measure (WMD) and its confidence interval (CI) of 95% were calculated. The “Funnel plot” graph assessed publication bias and heterogeneity. Results Seventeen papers were eligible: pregnant women (2), school children (9), adults/elderly (4) and preschool children/infants (2). Geographic distribution: North (1), Northeast (1), Midwest (2), Southeast (13), South (3). Twenty-three thousand two hundred seventy-two subjects were evaluated between 1997 and 2013 and all have use urinary iodine (UI) measurement. However, only 7 studies could be included in meta-analysis, all from Southeast region. The overall prevalence of IDD in school children in southeast region was 15.3% (95% CI, 13-35%), however this data had an important heterogeneity, expressed by the I2 Statistic of 99.5%. Conclusion Only few studies have been performed and enrolled populations from south/southeast region of Brazil. The actual IDD prevalence analysis is complex because it was detected bias due influence of individual studies and very high heterogeneity. IDD might still be high in some areas but this remained unknown even after this meta-analysis evaluation. The generation of a national program for analysis of iodine status in all regions is urgently required. Arch Endocrinol Metab. 2015;59(1):13-22

This work reports a review on the status and technical feasibility of the application of ethanol as fuel for Solid Oxide Fuel Cells (SOFC), presenting both external reform and cell with direct utilization of ethanol. Based on this survey, both experimental results and mathematical modeling indicated the technical feasibility of power generation by ethanol SOFC, with cell units producing 450 mW/cm², sufficient for scale up to large stationary plants. The quantitative assessments in the literature show this field to be promising for researchers and private sector investment as well being a strategic technology for government policy in the short and long term.

A simple and low cost flow cell is proposed for measurements by solid-phase spectrophotometry employing a conventional spectrophotometer. The flow cell geometry allows the employment of a large amount of the solid support without causing both excessive attenuation of the radiation beam and increasing of the back-pressure. The adaptation of the flow cell in the optical path of the spectrophotometer in order to increase the precision is discussed. The flow cell characteristics were demonstrated by measurements of Co(II), employing 1-(2-tiazolylazo)-2-naphthol (TAN) immobilized on C18 bonded silica as solid support. The apparent molar absorptivity and coefficient of variation were estimated as 1.86 x 10(5) L mol-1 cm-1 and 1.4 % (n=15). A sample throughput of 40 determinations per hour and a detection limit of 15 mug L-1 (99.7 % confidence level) were achieved.

No presente trabalho apresenta-se um método seletivo e sensível para rápida determinação de urânio usando o 2-(2-Tiazolilazo)-p-Cresol (TAC). O TAC reage com o urânio(VI) em pH 6,5 formando um complexo estável por pelo menos 3 h. Brometo de N-cetil-N,N,N-trimetil amônio (CTAB) e triton X-100 foram usados para aumento da sensibilidade e solubilidade do sistema respectivamente. O método permite a determinação de urânio na faixa de 0,30 a 12,0 mig mL-1 com absortividade molar estimada em 1,31 x 10(4) L mol-1 cm-1 e limite de detecção de 26 ng mL-1 em 588 nm. O uso do ácido 1,2-ciclohexilenodinitrilo tetraacético (CyDTA) como agente mascarante aumenta a seletividade do reagente para a determinação de urânio. O método proposto foi aplicado para determinação de urânio em água drenada de mina onde a precisão (R.S.D. < 2%) e exatidão obtidas foram satisfatórias.

A sensitive and selective spectrophotometric method is proposed for the rapid determination of uranium using 2-(2- Thiazolylazo)-p-Cresol (TAC). The reaction between TAC and uranium (VI) is instantaneous at pH 6.5 and the absorbance remains stable for over 3 h. N-cetyl-N,N,N-trimethylamonium bromide (CTAB) and triton X-100 are used for increasing the sensitivity and solubility of the system respectively. The method allows the determination of uranium in the range from 0.30 to 12.0 mug mL-1 with a molar absorptivity of 1.31 x 10(4) L mol-1 cm-1 and features a detection limit of 26 ng mL-1 at 588 nm. The selectivity of the reagent was improved by the use of (1,2-cyclohexylenedinitrilo) tetraacetic acid (CyDTA) as masking agent. The proposed method has been successfully applied to the determination of uranium in mine drainage waters. The precision (R.S.D. < 2%) and the accuracy obtained were satisfactory.

In this paper a general view about the modern molecular structure theory is developed discussing the ionized hydrogen molecule. We introduce some necessary approximation methods for the electronic and nuclear spectra study adopting a systematic approach. In addition though, we have performed calculations in order to illustrate these methods.

Cr(III) slowly forms a violet complex with EDTA at pH 2.5-5.0 under normal conditions. The complex formation can be accelerated by irradiating the reacting mixture with microwave energy. The complex Cr(III)-EDTA is completely formed within 3 minutes of microwave irradiation and followed by a simple and rapid method for spectrophotometric determination of chromium. The method may be successfully applied to determination of chromium in catalyst.

Um novo método espectrofotométrico para determinação de zinco(II) é proposto usando um derivado da 8-hidroxiquinolina, o ácido 7-(4-nitrofenilazo)-8-hidroxiquinolina sulfônico (p-NIAZOXS). A reação entre o p-NIAZOXS e o zinco(II) é rapida em pH 9,2 e o complexo formado é estável por pelo menos 24 h. O método permite a determinação de zinco na faixa de 0,05 a 1,0 mig mL-1 com absortividade molar de 3,75 x 10(4) L mol-1 cm-1 e limite de detecção de 15 ng mL-1. O método proposto foi aplicado na determinação de zinco em produtos farmacêuticos e ligas de cobre, onde a precisão (R. S. D. < 2%) e exatidão obtidas foram satisfatórias.

A sensitive and selective spectrophotometric method is proposed for the rapid determination of zinc(II) using an 8-hydroxyquinoline derivative, 7-(4-nitrophenylazo)-8-hydroxyquinoline-5-sulfonic acid (p-NIAZOXS), as a new spectrophotometric reagent. The reaction between the p-NIAZOXS and zinc(II) is instantaneous at pH 9.2 (borax buffer) and the absorbance remains stable for over 24 h. The method allows the determination of zinc over the range of 0.05-1.0 mug mL-1 with a molar absorptivity of 3.75x10(4) L mol-1 cm-1 and features a detection limit of 15 ng mL-1. The proposed method has been successfully applied to the determination of zinc in several pharmaceutical preparations and copper alloys. The precision (R.S.D. < 2%) and the accuracy obtained were satisfactory.