Determination of Total Sulfur Content in Fuels: A Comprehensive and Metrological Review Focusing on Compliance Assessment.

Sulfur-containing compounds are naturally found in crude oil, and they can be partially removed during the refining process. The wide use of fossil fuels has a significant contribution to sulfur emissions into the atmosphere, and Governments are striving to reduce the amount of the fuels by environmental regulations. The reduction of sulfur levels in diesel and other transportation fuels is beneficial from economic and environmental points, but meeting this standard represents a major operational and economic challenge for the oil and gas industry. Quantitative measurement of the sulfur amount must be taken along the oil refining chains guided by standards of measurement and recommended analytical methods such as various American Society for Testing and Materials methods (ASTM D2622, ASTM D5453, ASTM D7039, and ASTM D7220). Advancement in the refining processes and environmental regulations also require reliable measurements and well-defined criteria for compliance assessment. This work presented a brief review of the ASTM Standards used in the laboratories of the Brazilian oil and gas industry to determine the total sulfur content in fuels. We also presented an approach based on the reproducibility of the measurement methods and the guard band concept to evaluate the conformity statement.

Desafios dos laboratórios públicos da área de saúde ambiental para implantação e manutenção dos requisitos de normativas da qualidade para monitoramento da água de consumo humano / Challenges for public laboratories in the environmental health area for implementation and maintenance of quality regulatory requirements for monitoring human consumption water

Resumo Introdução O Ministério da Saúde (MS) é responsável pela vigilância da qualidade da água de consumo humano. A confiabilidade nos resultados do monitoramento de parâmetros analíticos minimiza riscos à saúde pública. Objetivo Retratar aspectos funcionais, a aplicação de ferramentas da qualidade e a aderência dos laboratórios públicos que atuam no monitoramento da água de consumo humano aos requisitos da norma ABNT NBR ISO/IEC 17025. Método A pesquisa foi realizada com 30 laboratórios públicos de todas as regiões do país, respondendo a um questionário elaborado com 49 perguntas sobre a formação e capacidade dos profissionais, garantia da validade dos resultados e sobre a determinação de parâmetros da qualidade da água. Resultados Dos 161 profissionais, 46% possuem mais de 10 anos de experiência e 65% têm formação superior. Capacitações específicas foram requeridas por todos. A validação dos métodos analíticos não foi realizada por 59%. Materiais de referência certificados são acessados por 41% e apenas 18% têm facilidade em adquiri-los. A participação em ensaios de proficiência foi reportada por 68% dos laboratórios, mas com poucos parâmetros avaliados e dificuldades em contratar provedores. Conclusão Evidenciou-se a necessidade de ações para fortalecimento da metrologia em laboratórios públicos que atuam na vigilância da qualidade da água.

Abstract Background The Ministry of Health (MS) is responsible for drinking water quality surveillance. Reliability in the results of monitoring analytical parameters minimizes public health risks. Objective To present functionals aspects and the application of quality tools by public laboratories that work to monitor the quality of drinking water. Method A survey was conducted with 30 public laboratories from all regions of the country, answering a questionnaire elaborated with 49 questions about the training and capacity of professionals, guaranteeing the validity of the results and about the determination of basic parameters of water quality. Results Of the 161 professionals, 46% have more than 10 years of experience and 65% have higher education. Specific training was required by everyone. The validation of the analytical methods was not performed by 59%. Reference materials are accessed by 41% and only 18% can acquire them easily. Participation in proficiency tests was reported by 68% of the laboratories, but with few parameters evaluated and difficulties in hiring providers. Conclusion The need for actions to strengthen metrology in public laboratories that work in water quality surveillance was highlighted.

Ionic concentration in periradicular medium after dissolution of endodontic file fragments: an in vitro study.

The aim of this study was to obtain ionic quantification in periradicular medium after diffusion tests of the solution used inside root canals during the electrochemical dissolution of endodontic file fragments and the NiTi-containing dissolution product via an apical foramen. Thirty single-rooted extracted human teeth had root canals prepared and were attached to Eppendorf tubes filled with sterile saline. The samples were divided into 3 groups (n = 10) according to the solution used inside the root canal during the diffusion tests: Group 1: [NaF 12 g/L + NaCl 1 g/L]; Group 2: [NaF 12 g/L + NaCl 1 g/L + NiTi 0.50 g/L]; Group 3: [NaF 6 g/L + NaCl 0.5 g/L + NiTi 0.25 g/L]. The sample in each Eppendorf tube was then analyzed to assay the ionic quantification in periradicular medium. The groups were compared in relation to ionic quantifications (Kruskal-Wallis and Dunn's tests, p ≤ 0.05). Group 2 showed significantly higher F-, Ni and Ti quantities than groups 1 and 3 (p < 0.05). Group 3 showed significantly higher Ti and Ni quantities than group 1, where no measurable quantities of Ti and Ni were observed (p < 0.05). The conclusions were that a 50% dilution of the NiTi-containing dissolution product resulted in significantly lower F-, Ni and Ti quantities compared to the undiluted product. The quantifications observed here suggest that irrigation is recommendable during the electrochemical dissolution process to reduce the resultant ion concentrations in both the root canal and the periradicular medium.

Ionic concentration in periradicular medium after dissolution of endodontic file fragments: an in vitro study

Abstract The aim of this study was to obtain ionic quantification in periradicular medium after diffusion tests of the solution used inside root canals during the electrochemical dissolution of endodontic file fragments and the NiTi-containing dissolution product via an apical foramen. Thirty single-rooted extracted human teeth had root canals prepared and were attached to Eppendorf tubes filled with sterile saline. The samples were divided into 3 groups (n = 10) according to the solution used inside the root canal during the diffusion tests: Group 1: [NaF 12 g/L + NaCl 1 g/L]; Group 2: [NaF 12 g/L + NaCl 1 g/L + NiTi 0.50 g/L]; Group 3: [NaF 6 g/L + NaCl 0.5 g/L + NiTi 0.25 g/L]. The sample in each Eppendorf tube was then analyzed to assay the ionic quantification in periradicular medium. The groups were compared in relation to ionic quantifications (Kruskal-Wallis and Dunn's tests, p ≤ 0.05). Group 2 showed significantly higher F-, Ni and Ti quantities than groups 1 and 3 (p < 0.05). Group 3 showed significantly higher Ti and Ni quantities than group 1, where no measurable quantities of Ti and Ni were observed (p < 0.05). The conclusions were that a 50% dilution of the NiTi-containing dissolution product resulted in significantly lower F-, Ni and Ti quantities compared to the undiluted product. The quantifications observed here suggest that irrigation is recommendable during the electrochemical dissolution process to reduce the resultant ion concentrations in both the root canal and the periradicular medium.

Effect of the Electric Field on DNA Bases as Pigments for Nanodevices: A First-Principles Study.

In this work we used Density Functional Theory to simulate the molecular electronics behavior of the nitrogenous bases of human DNA under electric field effects. The results can describe some internal effects in the use of DNA-based as photoconductor or semiconductor nanodevices. For this investigation, calculations were performed to predict structural deformations, HOMO and LUMO orbitals, and thermodynamic properties of each one of the following nitrogenous bases: adenine, thymine, guanine and cytosine. All the quantities were calculated as functions of the electric field. This analysis allows us to verify the influence of the electric field in the molecular geometry of nitrogenous bases, enabling us to determine that adenine, thymine and guanine are those bases most susceptible to presenting substantial deformations when DNA is submitted to the action of an external electric field, while the molecular structure of cytosine is highly resistant to this effect.

A simple method based on the application of a CCD camera as a sensor to detect low concentrations of barium sulfate in suspension.

The development of a simple, rapid and low cost method based on video image analysis and aimed at the detection of low concentrations of precipitated barium sulfate is described. The proposed system is basically composed of a webcam with a CCD sensor and a conventional dichroic lamp. For this purpose, software for processing and analyzing the digital images based on the RGB (Red, Green and Blue) color system was developed. The proposed method had shown very good repeatability and linearity and also presented higher sensitivity than the standard turbidimetric method. The developed method is presented as a simple alternative for future applications in the study of precipitations of inorganic salts and also for detecting the crystallization of organic compounds.

Restauração de dilaceração coronária e hipoplasia do esmalte / Restoration of crown dilaceration and enamel hypoplasia

Os traumatismos dos dentes decíduos resultam, na maioria das vezes, de acidentes caseiros, e na maioria dos casos afetam os incisivos centrais superiores. Os incisivos decíduos são altamente suscetíveis às luxações, sendo que 4,4 a 22 por cento delas são luxações intrusivas. Este tipo de trauma pode resultar em danos tanto para o decíduo quanto para o germe do permanente, que apresentam vários tipos de anomalias de desenvolvimento. Andreasen et al. (1971) relataram que, após trauma dos dentes decíduos, quase 50 por cento dos permanentes sucessores mostraram distúrbios nos diferentes estágios da odontogênese. A paciente citada neste relato de caso apresentava os dentes 31 e 41 com dilaceração coronária associada à descoloração branco-amarelada do esmalte. A descoloração é devida a um distúrbio interno da mineralização, acarretando hipoplasia e hipocalcificação. A dilaceração constutui-se de uma angulação aguda no longo eixo da coroa. Mesmo sem a presença de lesões cariosas, dentes dilacerados podem tardiamente desenvolver necrose pulpar seguida de periodontite apical e abcesso crônico. Para evitar essa complicação, a parte dilacerada da coroa foi removida e os dentes foram devidamente tratados. A estética e a anatomia funcional foram restabelecidas através de restauração em resina composta fotopolimerizada, associada a pino de fibra de vidro intra-radicular. Essa técnica apresenta como vantagens a simplicidade de execução, o baixo custo e a possibilidade de ser realizada em uma única sessão, além do excelente resultado estético-funcional