Preparation and optimization of macroalgae-derived solid acid catalysts

Solid acid catalysts were synthesized from macroalgae Sargassum horneri via hydrothermal carbonization followed by sulfuric acid sulfonation. A three-variable Box-Behnken design and optimization was used to maximize surface acidity. The optimal preparation conditions were found to be at the carbonization temperature of 217 °C, the carbonization time of 4.6 h and the sulfonation temperature of 108.5 °C. Under these conditions, the highest surface acidity achieved was 1.62 mmol g−1. Physical and chemical properties of prepared solid acid catalyst were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, and elemental analysis. The results proved the grafting of –SO3H groups on an amorphous carbon structure. The catalyst activity was evaluated by the esterification of oleic acid with methanol. The sample prepared achieved 96.6% esterification yield, which was higher than the 86.7% yield achieved by commercial Ambersyst-15 under the same reaction conditions

Annealing study and thermal investigation on bismuth sulfide thin films prepared by chemical bath deposition in basic medium

This is a post-peer-review, pre-copyedit version of an article published in Applied Physics A 124.2 (2018): 166. The final authenticated version is available online at: http://doi.org/10.1007/s00339-018-1584-7Bismuth sulfide thin films were prepared by chemical bath deposition using thiourea as sulfide ion source in basic medium. First, the effects of both the deposition parameters on films growth as well as the annealing effect under argon and sulfur atmosphere on as-deposited thin films were studied. The parameters were found to be influential using the Doehlert matrix experimental design methodology. Ranges for a maximum surface mass of films (3 mg cm-2) were determined. A well crystallized major phase of bismuth sulfide with stoichiometric composition was achieved at 190°C for 3 hours. The prepared thin films were characterized using Grazing Incidence X-ray diffraction (GIXRD), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDX). Second, the band gap energy value was found to be 1.5 eV. Finally, the thermal properties have been studied for the first time by means of the electropyroelectric (EPE) technique. Indeed, the thermal conductivity varied in the range of 1.20 - 0.60 W m-1 K-1 while the thermal diffusivity values increased in terms of the annealing effect ranging from 1.8 to 3.5 10-7 m2s-1This work was financially supported by the Tunisian Ministry of Higher Education and Scientific Research and by the WINCOST (ENE2016-80788-C5-2-R) project funded by the Spanish Ministry of Economy and Competitivenes

Frequency of oral mucositis and microbiological analysis in children with acute lymphoblastic leukemia treated with 0.12% chlorhexidine gluconate

Tendo em vista o potencial de morbidade das complicações orais em pacientes com leucemia, este estudo avaliou as alterações clínicas e microbiológicas que ocorrem na mucosa bucal de crianças com leucemia linfoblástica aguda (LLA), submetidas à quimioterapia antineoplásica e administração profilática do gluconato de clorexidina 0,12%. A amostra foi constituída de 17 crianças de 2 a 12 anos, as quais foram submetidas a exame clínico da mucosa oral para a detecção de lesões bucais. Além disso, foi coletado material biológico das mucosas labial e jugal para análises microbiológicas. A mucosite oral foi observada em apenas 5 (29,4%) pacientes. A análise microbiológica revelou a presença de um número reduzido de microorganismos potencialmente patogênicos, como estafilococos coagulase-negativos (47%), Candida albicans (35,3%), Klebsiella pneumoniae (5,9%), Escherichia coli enteropatogênica (5,9%) e Stenotrophomonas maltophilia (5,9%). Pacientes com mucosite oral apresentaram uma maior freqüência de estafilococos coagulase-negativos (80%) quando comparados aos pacientes que exibiam mucosa oral normal (33,3%). Em conclusão, os resultados do presente estudo sugerem que o uso profilático do gluconato de clorexidina 0,12% reduz a freqüência de mucosite oral e de patógenos orais em crianças com LLA. Além disso, os presentes achados sugerem uma possível relação entre estafilococos coagulase-negativos e o desenvolvimento de mucosite oral. _________________________________________________________________________________________ ABSTRACT: In view of the morbidity potential of oral complications in patients with leukemia, this study evaluated the clinical and microbiological alterations that occur in the oral mucosa of children with acute lymphoblastic leukemia (ALL) undergoing antineoplastic chemotherapy and prophylactic administration of 0.12% chlorhexidine gluconate. The sample consisted of 17 children aged 2 to 12 years that underwent clinical examination of the oral mucosa for the detection of oral lesions. In addition, biological material was collected from labial and buccal mucosa for microbiological analysis. Oral mucositis was observed in only 5 (29.4%) patients. Microbiological analysis revealed a reduced number of potentially pathogenic microorganisms, such as coagulase-negative staphylococci (47%), Candida albicans (35.3%), Klebsiella pneumoniae (5.9%), enteropathogenic Escherichia coli (5.9%), and Stenotrophomonas maltophilia (5.9%). Patients with oral mucositis showed a higher frequency of coagulase-negative staphylococci (80%) when compared with patients with normal oral mucosa (33.3%). In conclusion, the results of the present study suggest that the prophylactic use of 0.12% chlorhexidine gluconate reduces the frequency of oral mucositis and oral pathogens in children with ALL. In addition, the present findings suggest a possible relationship between coagulase-negative staphylococci and the development of oral mucositis

Bi-objective optimisation with multiple decision-makers: a convex approach to attain majority solutions

An interactive approach for solving bi-objective optimisation problems with multiple decision-makers in a context where the decisions are made via the strict majority voting rule is proposed. An adequate use of projection and decomposition techniques leads to a hierarchical algorithm in which the upper level is represented by a relaxed version of the bi-objective problem in the objective space. The feasibility of the partial consensus obtained in the upper (decision) level by the strict majority voting rule is tested in the lower (analysis) level of the algorithm. Some properties of the relaxed bi-objective problem allow that different preference structures of the decision-makers can be represented by appropriate multiobjective methods. The paper includes numerical examples that illustrate the characteristics of the approach proposed.51333334

Factorial design in the optimization of preconcentration procedure for lead determination by FAAS

The present paper proposes a preconcentration procedure for lead determination using flame atomic absorption spectrometry (FAAS). It is based on lead(11) ions extraction as brilliant cresyl blue (BCB) complex and its sorption onto Diaion HP-2MG, a methacrylic ester copolymer. The optimization step was carried Out using factorial design and the variables studied were pH, shaking time and reagent concentration. In the established experimental conditions, lead can be determinate with a limit of detection of 3.7 mug L-1 lead (N = 20) and a relative standard deviation of 7% for a lead concentration of 100 mug L-1. The accuracy was confirmed by analysis of a certified reference material, the stream sediment furnished by National Research Centre for Certified Reference Materials (NRCCRM), China (GBW 073 10). Effect of other ions in the procedure proposed was also Studied. The method was applied for lead determination in real samples of water, tea, soil and dust. Tests of addition/recovery in the experiments for lead determination in water samples revealed that the proposed procedure Could be applied satisfactorily for analysis of these samples. (C) 2004 Elsevier B.V. All rights reserved

Factorial design in the optimization of preconcentration procedure for lead determination by FAAS

WOS: 000227002900010PubMed ID: 18969885The present paper proposes a preconcentration procedure for lead determination using flame atomic absorption spectrometry (FAAS). It is based on lead(11) ions extraction as brilliant cresyl blue (BCB) complex and its sorption onto Diaion HP-2MG, a methacrylic ester copolymer. The optimization step was carried Out using factorial design and the variables studied were pH, shaking time and reagent concentration. In the established experimental conditions, lead can be determinate with a limit of detection of 3.7 mug L-1 lead (N = 20) and a relative standard deviation of 7% for a lead concentration of 100 mug L-1. The accuracy was confirmed by analysis of a certified reference material, the stream sediment furnished by National Research Centre for Certified Reference Materials (NRCCRM), China (GBW 073 10). Effect of other ions in the procedure proposed was also Studied. The method was applied for lead determination in real samples of water, tea, soil and dust. Tests of addition/recovery in the experiments for lead determination in water samples revealed that the proposed procedure Could be applied satisfactorily for analysis of these samples. (C) 2004 Elsevier B.V. All rights reserved

Determination of Cd, Cu, and Pb after cloud point extraction using multielemental sequential determination by thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS)

In the present paper a procedure for simultaneous preconcentration of Cd, Cu, and Pb using cloud point extraction (CPE) and multielemental sequential determination by thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) is proposed. This preconcentration procedure is based on the metals extraction into micellar media of octylphenoxypolythoxyethanol (Triton X-114) after their reaction with 1-(2-pyridylazo)-2-naphtol (PAN). A Box-Behnken design was used to optimize the variables (pH, buffer concentration and volume of NaCl) involved in the extraction procedure. Enrichment factors were calculated as the ratio between the slopes of calibration equations with and without the preconcentration procedure in the TS-FF-AAS, with values of 59, 25, and 21 respectively for Cd, Cu, and Pb. Limits of detection (LOD) (3s(b), n = 10) were also calculated as 0.025, 0.38, and 0.43 mu g L(-1) to Cd, Cu, and Pb, respectively. The precision (repeatability) expressed as relative standard deviation (RSD, n = 10) for reference standards of 10.0 and 20.0 mu g L(-1) were 6.1 and 4.5% for Cd, 7.2 and 3.4% for Cu and 5.2 and 8.7% for Pb. The accuracy was confirmed through the analysis of certified reference material (NIST 1643d, Trace elements in water). The developed procedure was also applied to Cd, Cu, and Pb determinations in mineral water samples.43481582