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A Simple, Rapid, and Reliable Titrimetric Method for the Determination of Glycerol at Low Concentration
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Santos, Luana O.

; Rocha, Sheisi F. L. S.

; Barra, Cristina M.

; Tubino, Matthieu

; Rocha Junior, José G.

Journal of the Brazilian Chemical Society

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Jun 2022, Volumen 33 Nº 6 Paginas 530 - 540

Resumen: En | Texto: En | PDF: En

Glycerol can be determined in several products by various analytical techniques. Titrimetric ones have stood out for their low cost, being recommended as standards. However, reliable, simple, fast, and green methods with low quantification limits are still needed. Titration of glycerol is based on its oxidation by periodate (Malaprade reaction) producing formic acid, formic aldehyde, and iodate. Iodate and periodate are iodometrically titrated, but mutual interference between these ions has produced methods with some drawbacks. Here is proposed to mask periodate with molybdate, to eliminate interference, determining the glycerol content through iodate, employing iodometric titration. Solutions containing from 10 to 1000 µg of glycerol were analyzed (error < 3.4%). The method was successfully applied for the determination of glycerol in biodiesels from different raw materials. Recoveries were from 92.9 ± 0.4 to 111 ± 3%. Semi-micro extraction was done, providing a fast procedure for determining free glycerol in biodiesel (< 10 min).

https://doi.org/10.21577/0103-5053.20220004

COMVC-19: A Program to protect healthcare workers’ mental health during the COVID-19 Pandemic. What we have learned
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Fukuti, Pedro

; Uchôa, Caroline Louise Mesquita

; Mazzoco, Marina Flaborea

; Cruz, Isabella D'Andrea Garcia da

; Echegaray, Mariana V.F.

; Humes, Eduardo de Castro

; Silveira, Júlia Belizário

; Santi, Talita Di

; Miguel, Euripedes Constantino

; Corchs, Felipe

; Fatori, Daniel

; Campello, Guilherme

; Oliveira, Gabriel M. de

; Argolo, Felipe C.

; Ferreira, Felipe de M.

; Machado, Gustavo

; Argeu, Adriana

; Oliveira, Graça Maria Ramos de

; Serafim, Antônio de Pádua

; Siqueira, Luciana de Lima

; Rossi, Luciane de

; Rios, Izabel Cristina

; Oliveira, Talita Rodrigues de

; Antoniazzi, Leilane C. K.

; Gagliotti, Daniel Augusto Mori

; Abelama Neto, Emílio

; Oliveira Junior, Paulo Novais de

; Correia, Aline Villalobo

; Gonçalves, Luca Schilling

; Tortato, Liana Silva

; Busato, Wagner Machado Moraes

; Guimarães-Fernandes, Flávio

; Alves, Marcos

; Leite Netto, Oswaldo Ferreira

; Schoueri, Patrícia de Campos Lindenberg

; Roque, Márcio de Assis

; Merlin, Silvia Stahl

; Boer, Giovana Cardoso Machado

; Sallet, Paulo Clemente

; Malbergier, André

; Spedo, Mariana Abrahão

; Kamitsuji, Carla Satie

; Faria, Elizabeth de

; Moreira, Moacyr Vergara de Godoy

; Kaufman, Arthur

; Abdo, Carmita

; Scanavino, Marco de Tubino

; Lancman, Selma

; Tavares, Hermano

; Polanczyk, Guilherme

; Brunoni, André R.

; Forlenza, Orestes V.

; Barros-Filho, Tarcísio Eloy Pessoa de

Clinics

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2021, Volumen 76 elocation e2631

Resumen: En | Texto: En | PDF: En

OBJECTIVE: In 2020, the COVID-19 pandemic brought a work and stress overload to healthcare workers, increasing their vulnerability to mental health impairments. In response, the authors created the COMVC-19 program. The program offered preventive actions and mental health treatment for the 22,000 workers of The Hospital das Clinicas da Faculdade de Medicina da Universidade de São Paulo (HCFMUSP). This paper aims to describe its implementation and share what we have learned from this experience. METHODS: Workers were able to easily access the program through a 24/7 hotline. Additionally, a mobile phone app that screened for signs and symptoms of emotional distress and offered psychoeducation and/or referral to treatment was made available. Data from both these sources as well as any subsequent psychiatric evaluations were collected. RESULTS: The first 20 weeks of our project revealed that most participants were female, and part of the nursing staff working directly with COVID-19 patients. The most frequently reported symptoms were: anxiety, depression and sleep disturbances. The most common diagnoses were Adjustment, Anxiety, and Mood disorders. CONCLUSIONS: Implementing a mental health program in a multimodal intervention was feasible in a major quaternary public hospital. Our data also suggests that preventive actions should primarily be aimed at anxiety and depression symptoms, with a particular focus on the nursing staff.

https://doi.org/10.6061/clinics/2021/e2631

X-ray Scattering and Chemometrics as Tools to Assist in the Identification of Gunshot Residues by Wavelength Dispersive X-ray Fluorescence Spectrometry
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Madeira, Fernanda B.

; Saide, Victor G. P.

; Castro, Martha T. P. O.

; Barra, Cristina M.

; Rocha, Sheisi F. L. S.

; Almeida, Vanessa G. K.

; Canuto, André V. S.

; Shimamoto, Gustavo G.

; Tubino, Matthieu

; Rocha Jr., José G.

Journal of the Brazilian Chemical Society

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Dic 2020, Volumen 31 Nº 12 Paginas 2470 - 2478

Resumen: En | Texto: En | PDF: En

Wavelength dispersion X-ray fluorescence spectrometry (WDXRF) is a non-destructive technique and therefore attractive for gunshot residues (GSR) analysis. It is well known for determination of inorganic constituents of samples. However, X-ray scattering region spectral data is not commonly used, although it may provide information about organic constituents and their interactions. This work employed X-ray scattering region and inorganic elements spectral data for a better characterization of GSR. Swabs containing residues collected from the hand of people who fired (shooters group) and also from the hands of people which did not fire (control group) with guns were analyzed directly by the WDXRF. Brake pad and people who perform activities that favor the accumulation of characteristic elements of GSR on their hands were chosen to compose the control group. Principal components analysis (PCA) discriminated the GSR according to the firearm/cartridge used. However, similar GSR clustering did not occur without X-ray scatter data, showing the importance of X-ray scattering spectrum for GSR evaluation. The k-nearest neighbors (k-NN) method correctly classified all samples from shooters and control groups, employing from 1 to 5 nearest neighbors. No anomalous behavior was detected by PCA and hierarchical cluster analysis (HCA).

https://doi.org/10.21577/0103-5053.20200122 253 descargas

BACTERIAL NANOCELLULOSE BIOMEMBRANE AS A SUPPORT FOR HUMAN INSULIN AIMING AT TRANSDERMAL PERMEATION
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Jorge, Ludmilla R.

; Harada, Liliam K.

; Silva, Erica C.

; Campos, Welida F.

; Oliveira Jr., José M.

; Vila, Marta M. D. C.

; Tubino, Matthieu

; Balcão, Victor M.

Química Nova

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May 2020, Volumen 43 Nº 5 Paginas 572 - 578

Resumen: En | Texto: En | PDF: En

Production of bacterial nanocellulose was pursued as a matrix system for the stabilization of human insulin. The biomembranes produced by Gluconacetobacter hansenii were washed with 2% aqueous sodium dodecylsulfate solution, rinsed with ultrapure water and immersed in 1 mol L-1 NaOH aqueous solution at 60 °C for 90 min until neutralization. For the insulin adsorption assays, the biomembranes were soaked in a buffered solution of human insulin until no protein could be detected in the supernatant. The membranes with adsorbed insulin were characterized via mechanical resistance (resilience, relaxation, perforation), Differential Scanning Calorimetry (DSC), Thermal Gravimetrical Analysis (TGA), Fourier Transform Infrared Spectrophotometry (FTIR), X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) analyses. The FESEM photomicrographs of the surface of the biomembranes showed a rugged surface without cracks. The biomembranes exhibited adequate mechanical characteristics. The infrared spectra indicated that the chemical aspect of the protein moiety was preserved during adsorption onto the BNC biomembranes. According to the XRD analyses, the biomembranes showed a generalized amorphous behavior. Thermal analyses indicated an adequate thermal stability for a pharmaceuticals product. Hence, an elastic and malleable biomembrane was produced, suitable for incorporation of human insulin, aiming at transdermal delivery.

https://doi.org/10.21577/0100-4042.20170522 332 descargas

Structural and Functional Stabilization of Sericin from Bombyx mori Cocoons in a Biopolysaccharide Film: Bioorigami for Skin Regeneration
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Balcão, Victor M.

; Harada, Liliam K.

; Jorge, Ludmilla R.

; Oliveira Jr., José M.

; Tubino, Matthieu

; Vila, Marta M. D. C.

Journal of the Brazilian Chemical Society

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Abr 2020, Volumen 31 Nº 4 Paginas 833 - 848

Resumen: En | Texto: En | PDF: En

Development and optimization of a bioorigami film with silk sericin was pursued for skin regeneration. Several formulations were produced, with varying integrated sericin contents, viz. 0, 1, 2, 5, 10, 20 and 50 mgsericin mLfilm-1. The physico-chemical characteristics of the bioorigami films produced were evaluated via infrared spectrophotometry, X-ray diffraction, X-ray transmission, X-ray fluorescence, thermogravimetry, differential scanning calorimetry, transdermal protein permeation, kinetics of protein release from the bioorigami films and free radical scavenging activities. The mechanical resistance was also evaluated. The results by 2,2-diphenyl-1-picryl-hydrazil (DPPH) assay suggest that the bioorigami films integrating crude sericin extract had capacity to sequester free radicals, exhibited prolonged release of the bioactive protein, good physico-chemical characteristics and adequate mechanical resistance. Specifically, the bioorigami film with 10 mgsericin mLfilm-1 proved to be able to release all the bioactive protein in a 12 h timeframe. The results suggest potential for use in biopharmaceutical application, specifically, as material for use in hydrogels.

https://doi.org/10.21577/0103-5053.20190247 534 descargas

Biodiesel Synthesis: Influence of Alkaline Catalysts in Methanol-Oil Dispersion
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Rocha Jr., José G.

; Mendonça, Andreza D. M.

; Campos, Daniel A. R. de

; Mapele, Renilson O.

; Barra, Cristina M.

; Bauerfeldt, Glauco F.

; Tubino, Matthieu

Journal of the Brazilian Chemical Society

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Feb 2019, Volumen 30 Nº 2 Paginas 342 - 349

Resumen: En | Texto: En | PDF: En

Biodiesel synthesis from soybean oil using methanol and alkaline catalysts occurs in the following two consecutive steps: dispersion of methanol in the oil and methanolysis. The effect of the alkaline catalysts NaOCH3, KOCH3, NaOH, and KOH in the dispersion step at 30-60 ºC and under mechanical stirring at 400 rpm was evaluated. The dispersion step accounts for 44.6-73.3% of the total synthesis time and was poorly favored compared to methanolysis due to the increase in temperature. The catalysts decreased the dispersion time, although most of them increased the methanol-oil interfacial tension. K-containing catalysts were more active than their Na analogues due to higher adsorption of K+ in the methanol-oil interface and the higher production of methyl esters (which act as emulsifying agents), which promote a more favorable interfacial tension. The alkaline cation effect was more significant in the dispersion step than in the methanolysis step.

https://doi.org/10.21577/0103-5053.20180183 703 descargas

Relationships between fish and otolith dimensions of Pomatomus saltatrix (Linnaeus, 1766) (Perciformes: Pomatomidae) in southeastern Brazil
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Souza, Geysa M. de

; Tubino, Rafael de A.

; Monteiro-Neto, Cassiano

; Costa, Marcus R. da

Neotropical Ichthyology

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2019, Volumen 17 Nº 1 elocation e180032

Resumen: Pt En | Texto: Pt En | PDF: Pt | PDF: En

RESUMO A anchova, Pomatomus saltatrix (Linnaeus, 1766), foi usada como modelo espécie-específico de relações morfométricas de otólitos e variáveis de crescimento relativo. As relações peso-comprimento entre otólito (comprimento-CO, altura-AO e peso-PO) e tamanho do peixe (comprimento total-CT e peso total-PT) foram determinadas para indivíduos capturados mensalmente durante o ano de 2015 na costa sudeste do Brasil. As análises de ANCOVA e Kruskal-Wallis não indicaram diferenças significativas para as constantes de crescimento relativo entre os sexos e distribuições de frequência de comprimento (p> 0,05). O fator de condição também não apresentou diferenças significativas entre os sexos, e medidas do otólito direito e esquerdo (p > 0,05). Um total de 398 espécimes foram amostrados: CT = 43,6-67,0 cm e PT = 365-2400 g. A RPC para peixes foi PT = 0.050CT2,55 e para os seus otólitos foi PO = 6.17E-05CO2,59, CO = 9.65-15.25 mm, AO = 3.65 - 5.45 mm and PO = 0.03-0.11 g. Os melhores ajustes foram observados para CT vs CO (r2 = 0,90); CO vs PO (r2 = 0,90); PT vs PO (r2= 0,81) e PT vs CO (r2 = 0,80). Os resultados mostraram que essas relações são ferramentas úteis na geração de estimativas de tamanho e peso dos peixes a partir dos otólitos, permitindo a sua aplicação em estudos em outras áreas, incluindo hábitos alimentares, paleontologia e manejo da pesca.

ABSTRACT The bluefish, Pomatomus saltatrix (Linnaeus, 1766), was used as a species-specific model to study morphometric relationships between otolith size and relative growth variables. Length-weight relationships between Otolith (Length-OL, Height-OH, and Weight-OW) and fish measurements (Total Length-TL and Total Weight-TW) were determined for fishes captured monthly during the year 2015 off the southeastern coast of Brazil. The ANCOVA and Kruskal-Wallis analysis did not indicate significant differences in the relative growth constants between sexes and length frequency distributions (p > 0.05). The condition factor also did not present significant differences between sexes, and right and left otolith measurements (p > 0.05). A total of 398 specimens were sampled: TL = 43.6-67.0 cm, TW = 365-2400 g, OL = 9.65-15.25 mm, OH = 3.65 - 5.45 mm and OW = 0.03-0.11 g. The LWR for grouped sexes was TW = 0.050TL2.55 and otoliths OW = 6.17E-05OL2.59. The best adjustments were TL vs OL (r2 = 0.90); OL vs OW (r2 = 0.90); TW vs OW (r2 = 0.81); and TW vs OL (r2 = 0.80). These results showed that such relationships are helpful tools for predicting the fish size and weight from otoliths, which may be used in food habits and paleontology studies, and other fisheries management applications.

https://doi.org/10.1590/1982-0224-20180032 1450 descargas

Insights into Protein-Ionic Liquid Interactions Aiming at Macromolecule Delivery Systems
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Harada, Liliam K.

; Pereira, Jorge F. B.

; Campos, Welida F.

; Silva, Erica C.

; Moutinho, Carla G.

; Vila, Marta M. D. C.

; Oliveira Jr., José M.

; Teixeira, José A.

; Balcão, Victor M.

; Tubino, Matthieu

Journal of the Brazilian Chemical Society

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Oct 2018, Volumen 29 Nº 10 Paginas 1983 - 1998

Resumen: En | Texto: En | PDF: En

Over the last few years, researchers have started to explore a particular class of compounds defined as ionic liquids (ILs) in attempts to use their unique characteristics. Since ILs have a very low vapor pressure, these fascinating compounds hold great potential as high performance chemicals for several applications in the (bio)pharmaceutical industry. In general, and unlike common organic solvents with comparable polarities, ILs are quite compatible with enzymes (enhancing their structural and chemical stability) and other proteins, since they can promote higher selectivities, faster reaction rates and greater enzyme stabilities in biocatalytic reactions providing, at the same time, a path for the structural and functional stabilization of protein entities. ILs appear to enhance the delivery of macromolecules, particularly protein entities, and their interactions with ILs will be tackled in detail in this review paper.

https://doi.org/10.21577/0103-5053.20180141 2314 descargas

Physicochemical Characterization of a Crude Anthocyanin Extract from the Fruits of Jussara (Euterpe edulis Martius): Potential for Food and Pharmaceutical Applications
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Favaro, Laura I. L.

; Balcão, Victor M.

; Rocha, Liliam K. H.

; Silva, Erica C.

; Oliveira Jr., José M.

; Vila, Marta M. D. C.

; Tubino, Matthieu

Journal of the Brazilian Chemical Society

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Oct 2018, Volumen 29 Nº 10 Paginas 2072 - 2088

Resumen: En | Texto: En | PDF: En

In the present research effort, production of a crude anthocyanin extract from the fruits of jussara (Euterpe edulis Martius) was pursued. The physico-chemical characteristics of the crude anthocyanin extracts were evaluated via Fourier transform infrared spectrophotometry, X-ray diffraction, X-ray fluorescence, computed tomography via X-ray transmission, UV-Vis spectrophotometric scannings, differential scanning calorimetry, antimicrobial activity, anthocyanin quantification, total phenolic content, thin layer chromatography for sugars and pigments, free radical 2,2-diphenyl-1-picryl-hydrazil (DPPH) scavenging activity and antioxidant activity via the molybdenum phosphate complex. The results gathered suggest that the crude anthocyanin extracts had both obvious antioxidant activity and radical scavenging effects with the DPPH assay, and light antibacterial activity against Staphylococcus aureus, further suggesting that this crude pigment extract might be a valuable addition for either food or pharmaceutical applications.

https://doi.org/10.21577/0103-5053.20180082 3978 descargas

10.

Influence of Water and Ultraviolet Irradiation on the Induction Period of the Oxidation of Biodiesel
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Silva, Willian L. G. da

; Salomão, Acacia A.

; Vila, Marta M. D. C.

; Tubino, Matthieu

Journal of the Brazilian Chemical Society

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Abr 2017, Volumen 28 Nº 4 Paginas 676 - 680

Resumen: En | Texto: En | PDF: En

Biodiesel degrades due to oxidative processes, causing a decrease in its quality. In the present work, it has been clearly shown that the incidence of ultraviolet radiation on biodiesels obtained from soy, canola, linseed and microalgae oils initiate oxidative processes which lead to the decrease in the induction period (IP) of the fuel. The influence of the residual water content of the same biodiesels on the oxidation process was also investigated with and without the incidence of ultraviolet radiation. Between 190 and 850 ppm of water in the biodiesel and without UV irradiation, no significant change in the IP values was observed under the experimental conditions.

https://doi.org/10.5935/0103-5053.20160202 1040 descargas

11.

Simple Methods via Mid-IR or 1H NMR Spectroscopy for the Determination of the Iodine Value of Vegetable Oils
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Shimamoto, Gustavo G.

; Favaro, Martha M. A.

; Tubino, Matthieu

Journal of the Brazilian Chemical Society

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Jul 2015, Volumen 26 Nº 7 Paginas 1431 - 1437

Resumen: En | Texto: En | PDF: En

Two methods for determining the iodine value in vegetable oils are described. One employs mid-infrared (mid-IR) spectroscopy and the other uses hydrogen nuclear magnetic resonance (1H NMR). The determination of the iodine value is based on either the transmittance intensity of mid-IR signals or on the 1H NMR signal integration and multivariate calibration. Both of the methods showed adequate coefficients of determination (r2 = 0.9974 and 0.9978, respectively) when compared to Wijs method, which is recommended by the norm EN 14111. A statistical comparison between the results from the proposed methods and from Wijs method shows that both instrumental methods offer equivalent results and greater precisions compared to Wijs method. The regressions obtained from the constructed models were considered statistically significant and useful for making predictions. The proposed methods present several advantages compared to Wijs method because they significantly reduce analysis time, reagent consumption and waste generation. Furthermore, an analyst can choose between the mid-IR or 1H NMR to determine the iodine value.

https://doi.org/10.5935/0103-5053.20150111 5913 descargas

12.

Flow Injection Analysis System for Screening Organophosphorus Pesticides by their Inhibitory Effect on the Enzyme Acethylcholinesterase
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Silva, Marcos P.

; Tubino, Matthieu

; Elsholz, Tereza C. R.

; Elsholz, Olaf

; Khan, Sabir

; Vila, Marta M. D. C.

Journal of the Brazilian Chemical Society

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Mar 2015, Volumen 26 Nº 3 Paginas 484 - 489

Resumen: En | Texto: En | PDF: En

A flow-injection spectrophotometric procedure was developed for screening organophosphorus pesticides. The method is based on the inhibition of acetylcholinesterase immobilized on controlled porous glass beads with acetylcholine chloride as the substrate. Methyl parathion, chlorpyrifos, malathion and dichlorvos have been tested. The analytical peak height for a given acetylcholine chloride concentration correlates linearly with the logarithmic concentration of the pesticides between 1.0 × 10-3 mol L-1 and 1.0 × 10-6 mol L-1. If bromine water is added to the pesticide solution, a dramatic increase is observed in the analytical signal, and correlations with the logarithm of the concentrations are observed from 1.0 × 10-3 to 1.0 × 10-10 mol L-1.

https://doi.org/10.5935/0103-5053.20150301 1463 descargas

13.

Mineral processing and characterization of coal waste to be used as fine aggregates for concrete paving blocks
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Santos, C. R.

; Tubino, R. M. C.

; Schneider, I. A. H.

Revista IBRACON de Estruturas e Materiais

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Feb 2015, Volumen 8 Nº 1 Paginas 14 - 24

Resumen: Pt En | Texto: Pt En | PDF: Pt | PDF: En

A produção de carvão mineral na região sul do Brasil vem ocorrendo desde o início do século XX. Devido às características geológicas da região, grandes quantidades de resíduos sólidos são gerados. O objetivo deste trabalho foi avaliar a utilização de rejeito de carvão para a produção de blocos de pavimentação de concreto. O rejeito de carvão foi beneficiado com o objetivo de reduzir o teor de enxofre e ajustar o tamanho das partículas do material para as especificações de distribuição granulométrica de agregado miúdo. A metodologia considerou os seguintes passos: (a) amostragem do rejeito de carvão mineral; (b) separação gravimétrica da fração com densidade entre 2,4 e 2,8; (c) cominuição do material e análise da distribuição granulométrica; (d) caracterização tecnológica do material e produção de blocos de concreto para pavimentação; e (e) predição da geração de acidez (viabilidade ambiental). Os resultados mostraram que o rejeito de carvão utilizado neste trabalho pode ser utilizado para substituir a areia convencional como um agregado miúdo na produção de blocos de concreto para pavimentação numa proporção de até 50%. Esta prática pode colaborar com a produção mais limpa de carvão mineral e reduzir a demanda de exploração de jazidas de areia.

Commercial coal production in the southern region of Brazil has been occurring since the beginning of the twentieth century. Due to the geological characteristics of the region, large amounts of solid wastes are generated. The aim of this work was to evaluate the use of coal waste to produce concrete paving blocks. A procedure to process the coal waste with the purpose of reducing the sulfur content and changing the particle size distribution of the material to meet the specification of fine aggregates was developed. The methodology considered the following steps: (a) sampling of a coal mining waste; (b) gravity separation of the fraction with specific gravity between 2.4 and 2.8; (c) comminution of the material and particle size analysis; (d) technological characterization of the material and production of concrete paving blocks; and (e) acidity generation prediction (environmental feasibility). The results showed that the coal waste considered in this work can be used to replace conventional sand as a fine aggregate for concrete paving blocks in a proportion of up to 50%. This practice can result in cleaner coal production and reduce the demand for exploitation of sand deposits.

https://doi.org/10.1590/S1983-41952015000100004 3509 descargas

14.

Spot-test identification and rapid quantitative sequential analysis of dipyrone
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Tubino, M.

; Biondo, A. C.

; Vila, M. M. D. C.

; Pezza, L.

; Pezza, H. R.

Eclética Química

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2010, Volumen 35 Nº 1 Paginas 41 - 46

Resumen: Pt En | Texto: Pt En | PDF: Pt | PDF: En

Um método "spot-test" qualitativo e seqüencialmente quantitativo é proposto para análise de dipirona em fármaco "puro" e em preparações farmacêuticas. A formação de coloração vermelho-violeta indica um resultado qualitativo positivo. Na seqüência, um procedimento quantitativo pode ser realizado no mesmo frasco. Os resultados quantitativos obtidos foram comparados estatisticamente com os resultados obtidos pelo método indicado pela Farmacopéia Brasileira, utilizando o teste t de Student e o teste F. Considerando a concentração em uma alíquota de 100 µL, o limite qualitativo visual de detecção foi de cerca 5×10-6 g; instrumentalmente o limite de detecção foi de LOD ≅ 1.4×10-4 mol L-1 e o limite de quantificação de LOQ ≅ 4.5×10-4 mol L-1.

A qualitative spot-test and tandem quantitative analysis of dipyrone in the bulk drug and in pharmaceutical preparations is proposed. The formation of a reddish-violet color indicates a positive result. In sequence a quantitative procedure can be performed in the same flask. The quantitative results obtained were statistically compared with those obtained with the method indicated by the Brazilian Pharmacopoeia, using the Student's t and the F tests. Considering the concentration in a 100 µL aliquot, the qualitative visual limit of detection is about 5×10-6 g; instrumental LOD ≅ 1.4×10-4 mol L-1 ; LOQ ≅ 4.5×10-4 mol L-1.

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15.

Flow injection analysis of vancomycin
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Vila, M. M. D. C.

; Salomão, A. A.

; Tubino, M.

Eclética Química

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- Sobre o periódico
- SciELO Analytics

2008, Volumen 33 Nº 2 Paginas 67 - 72

Resumen: Pt En | Texto: Pt En | PDF: Pt | PDF: En

Este trabalho apresenta um método de análise por injeção em fluxo para determinação quantitativa de cloridrato de vancomicina, C66H75Cl2N9O24.HCl (HVCM), baseado na reação com íons cobre (II). ? HVCM na presença de íons cobre, em pH≅4,5 e solução aquosa forma um complexo azullilás, com absorção máxima em 555 nm. O limite de detecção estimado foi de 8.5×10-5 mol L-1; e o limite de quantificação de 2.5×10-4 mol L-1 com cerca de 30 determinações por hora. A exatidão do método foi determinada através de ensaio de recuperação na presença de quatro diferentes excipientes na proporção de 1:1 p/p. Os resultados do método espectrofotométrico por injeção em fluxo foram comparados com resultados obtidos pelo método espectrofotométrico por batelada e por HPLC, através de método estatístico t de Student. Obteve-se completa concordância com nível de significância de 0,95 e similar precisão (RSD: 2,1 % vs. 1,9%).

A flow injection method for the quantitative analysis of vancomycin hydrochloride, C66H75Cl2N9O24.HCl (HVCM), based on the reaction with copper (II) ions, is presented. HVCM forms a lilac-blue complex with copper ions at pH≅4.5 in aqueous solutions, with maximum absorption at 555 nm. The detection limit was estimated to be about 8.5×10-5 mol L-1; the quantitation limit is about 2.5×10-4 mol L-1 and about 30 determinations can be performed in an hour. The accuracy of the method was tested through recovery procedures in presence of four different excipients, in the proportion 1:1 w/w. The results were compared with those obtained with the batch spectrophotometric and with the HPLC methods. Statistical comparison was done using the Student's procedure. Complete agreement was found at a 0.95 significance level between the proposed flow injection and the batch spectrophotometric methods, which present similar precision (RSD: 2.1 % vs. 1.9%).

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