Synthesis of a Goethite Pigment by Selective Precipitation of Iron from Acidic Coal Mine Drainage

Conventional treatment of acid rock drainage (ARD) from coal mines generates large volumes of sludge, which requires further treatment and disposal. The aim of this work was to study the recovery of iron by selective precipitation to synthetize goethite for use as pigment. Goethite particles were successfully produced, and presented a particle distribution in the range of nano- and micro-sizes, varying from 0.04 to 5.0 µm when produced as paste suspension, or from 0.04 to 25.0 µm when dried at 60?°C and converted to a solid powder. The pigment was used to color a white cement paste, giving it a yellow ochre color. ARD treatment plants can adopt this process to reduce waste disposal issues and produce a valuable mineral (e.g., yellow pigment for concrete).     

Reaction and thermal behavior of vitrimer-like polyhydroxy esters based on polyethylene glycol diglycidyl ether

Vitrimers-like polyhydroxy esters networks were thermally synthesized from mixtures of the diepoxide monomer diglycidyl ether polyethyleneglycol (DGEPEG), citric (CA), and sebacic acids (SA), using zinc acetate in proportions of 1 to –5 mol%. as catalyst for bond exchange reactions. Reaction of DGEPEG with the acids is exothermic with enthalpy up to 326 J/g and takes place even without any catalyst. The progress of the reaction is reduced as the content of SA is increased in the formulations, but reaction enthalpy in mixtures containing 1% of Zn catalyst is higher than those with 5%mol Zn. These polyhydroxy esters networks are rubber-like materials with T_g varying from −24 to −43°C, with formulations containing SA showing the lowest T_g values. The presence of ester and hydroxyl groups and Zn catalyst in the polymers give rise to exchange reactions similar to those shown by vitrimers. However, the increase in Zn concentration from 1% to 5%, arouses a loss of thermal stability of these materials.     

Controlled release of drugs from cellulose acetate matrices produced from sugarcane bagasse: monitoring by square-wave voltammetry

In this paper, cellulose triacetate (CTA) was produced from sugarcane bagasse and used as matrices for controlled release of paracetamol. Symmetric and asymmetric membranes were obtained by formulations of CTA/dichloromethane/drug and CTA/dichloromethane/water/drug, respectively, and they were characterized by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Different morphologies of membranes were observed by SEM, and the incorporation of paracetamol was confirmed by lowering of the glass transition temperature (T_g) in the DSC curves. This indicates the existence of interactions between the matrix and the drug. The evaluation of drug release was based on the electrochemical monitoring of paracetamol through its oxidation at a glassy carbon electrode surface using square-wave voltammetry (SWV), which provides fast, precise and accurate in situ measurements. The studies showed a content release of 27% and 45% by the symmetric and asymmetric membranes, respectively, during 8?h.     

Effects of reduced levels of sulfite in wine production using mixtures with lysozyme and dimethyl dicarbonate on levels of volatile and biogenic amines

Sulphur dioxide (SO₂) is an important preservative for wine, but its presence in foods can cause allergies and this has given impetus to the research for alternatives. The aim of this study was to reduce levels of sulfite in wine production using mixtures with lysozyme and dimethyl dicarbonate and examine the influence on levels of volatile and biogenic amines. To do so, vinifications were carried out using lysozyme, dimethyl dicarbonate (DMDC) and mixtures of these with SO₂ in different concentrations (25 and 50 mg l^?1). Results were compared with a control vinification with only SO₂ (50 mg l^?1). Mixing low concentrations of SO₂ with lysozyme and DMDC reduced the concentration of biogenic amines (histamine, tyramine, putrescine, cadaverine, phenylethylamine + spermidine and spermine). In general, the total concentration of volatile amines (dimethylamine, isopropylamine, isobutylamine, pyrrolidine, ethylamine, diethylamine, amylamine and hexylamine) was higher in the sample fermented only with SO₂. The concentrations of amines with secondary amino groups (dimethylamine, diethylamine, pyrrolidine) were higher in the sample only fermented with SO₂ than those fermented with DMDC and lysozyme or with a mixture of preservatives. When SO₂ was the only preservative in wine, total amine concentration (biogenic and volatile amines) was higher than for the rest of the treatments. Lysozyme by itself, and lysozyme mixed with SO₂, both reduced the formation of biogenic amines but given the antioxidant activity of SO₂ the use of the preservative mixture seems more advisable.     

Deciphering upper respiratory tract microbiota complexity in healthy calves and calves that develop respiratory disease using shotgun metagenomics

Bovine respiratory disease (BRD) is a multifactorial disorder responsible for severe economic losses in dairy and feedlot herds. Advances in next-generation sequencing mean that microbial communities in clinical samples, including non-culturable bacteria, can be characterized. Our aim was to evaluate the microbiota of the upper respiratory tract of healthy calves and calves with BRD using whole-genome sequencing (shotgun metagenomics). We performed deep nasopharyngeal swabs on 16 Holstein heifer calves (10 healthy and 6 diagnosed with BRD during the study) at 14 and 28 d of life in 1 dairy herd near Ithaca, New York. Total DNA was extracted, and whole-genome sequencing was performed using the MiSeq Illumina platform (Illumina Inc., San Diego, CA). Samples included 5 predominant phyla: Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, and Tenericutes. At the genus level, we observed differences between groups for Pseudomonas spp. At the species level, Mannheimia haemolytica was the most abundant bacterium detected. We detected significant differences between groups of calves in the relative abundance of Pseudomonas fluorescens. Pasteurella multocida was among the 20 most abundant species, and Moraxella catarrhalis, commonly associated with pneumonia in humans, was detected in all groups. Analysis of resistance to antibiotics and compounds profiling revealed differences in cobalt-zinc-cadmium resistance. Further research to elucidate the role of Moraxella catarrhalis in BRD is warranted. Genes that were resistant to cobalt-zinc-cadmium, observed mostly in calves with BRD, might be associated with difficulties in antibiotic treatment.