Electrocatalytic performance of PbO2 films in the degradation of dimethoate insecticide

This study was performed to find the best experimental conditions for the electrochemical removal of the insecticide dimethoate (C5H12NO3PS2) from aqueous solutions using a lead dioxide niobium anode. The process was studied under galvanostatic polarisation mode. The influence of applied current density (10–50 mA·cm–2), initial chemical oxygen demand COD0 (100–550 mg·ℓ–1), temperature (30–70°C) and pH (3–11) on COD and instantaneous current efficiency (ICE) was studied. The results showed that almost 90% of COD removal was achieved under optimal experimental conditions, indicating that electrochemical oxidation on a PbO2 anode is a suitable method for treatment of water polluted with dimethoate. It was found that the decay of COD generally followed a pseudo first-order kinetic and the oxidation rate was favoured by increasing the applied current density, temperature, pH and initial COD. The greatest COD removal (90%) was obtained when using an applied current density of 50 mA·cm–2, COD0 = 320 mg·ℓ–1, pH = 11, T = 70°C and electrolysis time = 8 h.Keywords: Electrochemical degradation; hydroxyl radicals; organic pollutants; lead dioxide; wastewate

Polyamide from lactams by reactive rotational molding via anionic ring-opening polymerization: Optimization of processing parameters

A reactive rotational molding (RRM) process was developed to obtain a PA6 by activated anionic ring-opening polymerization of epsilon-caprolactam (APA6). Sodium caprolactamate (C10) and caprolactam magnesium bromide (C1) were employed as catalysts, and difunctional hexamethylene-1,6-dicarbamoylcaprolactam (C20) was used as an activator. The kinetics of the anionic polymerization of !-caprolactam into polyamide 6 was monitored through dynamic rheology and differential scanning calorimetry measurements. The effect of the processing parameters, such as the polymerization temperature, different catalyst/activator combinations and concentrations, on the kinetics of polymerization is discussed. A temperature of 150°C was demonstrated to be the most appropriate. It was also found that crystallization may occur during PA6 polymerization and that the combination C1/C20 was well suited as it permitted a suitable induction time. Isoviscosity curves were drawn in order to determine the available processing window for RRM. The properties of the obtained APA6 were compared with those of a conventionally rotomolded PA6. Results pointed at lower cycle times and increased tensile properties at weak deformation

Electrochemical behavior of Auramine O dye in aqueous solutions at lead dioxide electrode

Electrochemical behavior of Auramine O (AO) was studied by galvanostatic electrolysis at lead dioxide (Ta/PbO2) anodes. The influence of operating parameters, such as current density, initial concentration of AO, temperature and initial pH value was investigated. The oxidation kinetics of the AO was followed by HPLC, UV / visible spectrophotometry and the measurement of chemical oxygen demand (COD). The experimental results showed that the electrochemical process was suitable for almost completely removing COD, due to the production of the hydroxyl radicals at the anode surface. The oxidation of AO is dependent on its initial concentration, current density, temperature and pH. COD decay follows a pseudo first-order kinetic and the process was under mass transport control. The HPLC analysis showed that the main AO oxidation products formed during electrolysis are the hydroquinone (HQ) representing the reduced form of benzoquinone (BQ) and carboxylic acids (CA).  The proposed AO anodic oxidation into (BQ) is mainly based on an alternance of indirect monoelectronic discharge by the mediation of hydroxyl radicals and hydrolysis steps. The electrochemical oxidation of AO can be used as an economically adequate way for a pre-treatment of waters containing this dye followed by biological treatment

Hurler disease (mucopolysaccharidosis type IH): clinical features and consanguinity in Tunisian population

Mucopolysaccharidosis type I (MPS I) was a group of rare autosomal recessive disorder caused by the deficiency of the lysosomal enzyme, alpha -L -iduronidase, and the resulting accumulation of undergraded dematan sulfate and heparan sulfate. MPS I patients have a wide range of clinical presentations, that makes it difficult to predict patient phenotype which is needed for genetic counseling and also impedes the selection and evaluation of patients undergoing therapy bone marrow transplantation

Mucopolysaccharidosis type I: molecular characteristics of two novel alpha-L-iduronidase mutations in Tunisian patients

<p>Abstract</p> <p>Background</p> <p>Mucopolysaccharidosis type I (MPS I) is an autosomal storage disease resulting from defective activity of the enzyme α-L-iduronidase (IDUA). This glycosidase is involved in the degradation of heparan sulfate and dermatan sulfate. MPS I has severe and milder phenotypic subtypes.</p> <p>Aim of study: This study was carried out on six newly collected MPS I patients recruited from many regions of Tunisia.</p> <p>Patients and methods: Mutational analysis of the IDUA gene in unrelated MPS I families was performed by sequencing the exons and intron-exon junctions of IDUA gene.</p> <p>Results</p> <p>Two novel IDUA mutations, p.L530fs (1587_1588 insGC) in exon 11 and p.F177S in exon 5 and two previously reported mutations p.P533R and p.Y581X were detected. The patient in family 1 who has the Hurler phenotype was homozygous for the previously described nonsense mutation p.Y581X.</p> <p>The patient in family 2 who also has the Hurler phenotype was homozygous for the novel missense mutation p.F177S. The three patients in families 3, 5 and 6 were homozygous for the p.P533R mutation. The patient in family 4 was homozygous for the novel small insertion 1587_1588 insGC. In addition, eighteen known and one unknown IDUA polymorphisms were identified.</p> <p>Conclusion</p> <p>The identification of these mutations should facilitate prenatal diagnosis and counseling for MPS I in Tunisia.</p> <p>Background</p> <p>Mucopolysaccharidosis type I (MPS I) is an autosomal recessive lysosomal storage disorder caused by the deficient activity of the enzyme of α-L-iduronidase (IDUA, EC 3.2.1.76). This glycosidase is involved in the degradation of heparan sulfate and dermatan sulfate. The clinical phenotype of MPS I ranges from the very severe in Hurler syndrome (MPS IH) to the relatively benign in Scheie syndrome (MPS IS), with an intermediate phenotype designated Hurler/Scheie (MPS IH/S) <abbrgrp><abbr bid="B1">1</abbr></abbrgrp>. Isolation of complementary and genomic DNAs encoding human α -L- iduronidase <abbrgrp><abbr bid="B2">2</abbr><abbr bid="B3">3</abbr></abbrgrp> have enable the identification of mutations underlying the enzyme defect and resulting in MPS I clinical phenotype. More than 100 mutations have been reported in patients with the MPS I subtypes (Human Gene Mutation Database; <url>http://www.hgmd.org</url>). High prevalence of the common mutations p.W402X and p.Q70X has been described; both of them in the severe clinical forms <abbrgrp><abbr bid="B4">4</abbr><abbr bid="B5">5</abbr></abbrgrp>. A high prevalence of common mutation p.P533R has also been described in MPS I patients with various phenotypes <abbrgrp><abbr bid="B5">5</abbr><abbr bid="B6">6</abbr></abbrgrp>. In addition, rare mutations including single base substitution, deletion, insertion and splicing site mutation have been identified <abbrgrp><abbr bid="B7">7</abbr></abbrgrp>, indicating a high degree of allelic heterogeneity in IDUA gene.</p> <p>Here, we described two novel IDUA mutations in MPS I Tunisian patients. These lesions were homoallelic in all the patients of the six families investigated as consanguineous marriages are still frequent in Tunisia <abbrgrp><abbr bid="B8">8</abbr></abbrgrp>.</p

Smectite clay KSF as effective catalyst for oxidation of m-tyrosol with H 2 O 2 to hydroxytyrosol

A successful procedure to demonstrate the ability to produce high-added value phenolic hydroxytyrosol by oxidation of m-tyrosol was developed, using clay KSF/H 2 O with peroxide hydrogen to afford excellent yields (more than 60%). Three different operating parameters, including m-tyrosol, H 2 O 2 concentration and amount of catalyst were performed using an experimental design methodology “Box–Behnken” for hydroxytyrosol production. All derivative compounds in reaction mixture during reaction time were identified using mass spectrometry. Hydroxytyrosol 3,4-dihydroxystyrene; 3-hydroxyphenyl acetic acid and 2.5-dihydroxyphenylethanol were the major compounds. By means of 2,2-diphenyl-1-picrylhydrazyl DPPH method, the antioxidant activity was realized, indicating that the strongest antiradical activity (IC 50% = 21.57 mg/mL) was detected when the concentration of hydroxytyrosol is higher. The developed synthesis, investigated for the first time, is operationally simple and could find application for industrial purposes. © 2019, Akadémiai Kiadó, Budapest, Hungary