With the increase in global demand for biodiesel, first generation feedstock has drawn the attention of governmental institutions due to the correlation with large land farming areas. The second and ...third feedstock generations are greener feedstock sources, nevertheless, they require different catalytic conditions if compared with first generation feedstock. In this work, we present the synthesis and characterization of oligoesters matrices and their functionalization to act as a pseudo-homogeneous acid catalyst for biodiesel production, named Oligocat. The main advantage of Oligocat is given due to its reactional medium interaction. Initially, oligocat is a solid catalyst soluble in the alcoholic phase, acting as a homogeneous catalyst, providing better mass transfer of the catalytic groups to the reaction medium, and as the course of the reaction happens, Oligocat migrates to the glycerol phase, also providing the advantage of easy separation of the biodiesel. Oligocat was synthesized through polymerization of aromatic hydroxy acids, followed by a chemical functionalization applying the sulfonation technique. Characterization of the catalysts was carried out by infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), and thermogravimetric analysis (TGA). The synthesized oligomers presented 5357 g·mol
(Mw) and 3909 g·mol
(Mn), with a moderate thermal resistance of approximately 175 °C. By sulfonation reaction, it was possible to obtain a high content of sulphonic groups of nearly 70 mol%, which provided the catalytic activity to the oligomeric matrix. With the mentioned physical-chemical properties, Oligocat is chemically designed to convert second generation feedstock to biodiesel efficiently. Preliminary investigation using Oligocat for biodiesel production resulted in conversion rates higher than 96.5 wt.%.
Biodiesel is a well-established biofuel that contains unsaturated and saturated fatty esters, and their contents influence oxidation stability and solidification properties, respectively. Also, these ...properties can be aggravated during use after long-term storage. In this research, a new class of antioxidant/antifreeze bifunctional additives was developed by copolymerization of monomers containing an active site for addition reactions. Hydroquinone was added to these active sites after polymerization, and this chemical modification improved the performance of the additive as an antioxidant and pour point depressant of soybean oil biodiesel. This unique class of bifunctional additives was more soluble in biodiesel than hydroquinone and polymethacrylates at the same molar concentrations. The best performance was obtained by poly(oleyl acrylate-co-stearyl acrylate hydroquinone), which improved the pour point of neat biodiesel (B100) by 10 °C using a charge of just 1000 mg/kg. Also, hydroquinone performed as good as dodecyl acrylate as the pendent group, hindering crystal growth while improving B100 oxidation stability.
Abstract To investigate the biomechanical factors associated with patellofemoral pain in children and adolescents. A cross-sectional, population-based study conducted in Brazil from 2019 to 2023, ...involving students from public schools. Adjusted prevalence ratios and their respective 95% confidence intervals for the outcome in relation to independent variables were calculated for association analysis, adopting a significance level of 5%. Out of the total of 283 students, 152 were female and 182 were aged between 16 and 18 years old. A positive association was observed between the presence of patellofemoral pain and a poor movement quality in both lower limbs (right side: p = 0.04 and left side: p = 0.04) as well as with dynamic valgus of the left lower limb ( p < 0.01). Patellofemoral pain in children and adolescents is associated with poor movement quality in the lower limbs and dynamic valgus of the left lower limb. Actions targeting these biomechanical factors may be crucial for early diagnosis and clinical treatment of this disfunction.
Summary
Low molar mass homopolymers, synthesized through free radical polymerization of acrylic acid under solvent control were reported. The polymers were characterized by FTIR, NMR, TGA, and GPC. ...The behavior as pour point improvers in biodiesel and blends biodiesel/diesel, were evaluated. By using 1000 ppm of the poly(tetradecyl acrylate) (A14) it was possible to decrease the pour point (PP) of neat biodiesel to −10°C, blend B5 to −39°C and blend B20 to −28°C, values below those reported in the literature. These results indicated that it would be possible to use higher amount of biodiesel in blends with diesel in regions where their use would not be feasible, mainly because of their poor flow properties.
Protected areas Azevedo-Santos, Valter M.; Frederico, Renata G.; Fagundes, Camila K. ...
Diversity & distributions,
03/2019, Volume:
25, Issue:
3
Journal Article
Peer reviewed
Open access
Brazil has a variety of aquatic ecosystems and rich freshwater biodiversity, but these components have been constantly damaged by the expansion of unsustainable activities. An array of different ...conservation strategies is needed, especially the creation of protected areas (PAs, hereafter). However, Brazil’s PAs are biased towards terrestrial ecosystems and we argue that current PAs have limited efficacy in the protection of freshwater biodiversity. New PAs should better consider aquatic environments, covering entire basins, rivers and other freshwater habitats. We recommend ways to implement these PAs and provide guidance to avoid social impacts. Freshwater systems in Brazil provide essential goods and services but these ecosystems are being rapidly degraded and will be lost if not adequately protected.
A variety of techniques have been employed in order to reduce problems caused by the crystallization of paraffin during the production and/or transportation of paraffin oils and derivatives. ...Methacrylate copolymers are known as additives which reduce the pour point of these oils. This paper describes the synthesis, characterization and performance evaluation of these copolymers, having as an initial step the synthesis of the alkyl methacrylate monomers by transesterification of methyl methacrylate (MMA) with C
14, C
16 and C
18 fatty alcohols. The copolymerization of these monomers with MMA was then performed, with molar ratios of 30:70, 50:50 and 70:30 for alkyl methacrylate:methyl methacrylate. All products were characterized by FTIR,
1H NMR and gel permeation chromatography (GPC). All the methacrylic copolymers lead to a large reduction in the pour point of samples of Brazilian diesel oil. Oil samples containing 50
ppm of the polymeric additive with ca. 70% octadecyl methacrylate units showed a 22
°C reduction in their pour points, thus establishing the large efficiency of the products synthesized in this work.
Sulfonated polystyrene compounds (SPS) were synthesized, leading catalytically active polymeric materials with high sulfonation degree. Catalyst performance was evaluated in beef tallow and soybean ...oil transesterification reactions. The SPS leading to conversion of 85 and 75% for soybean oil and beef tallow in to ethyl esters, respectively, and 94% of the soybean oil methyl esters. Therefore, sulfonated polymeric compounds obtained from linear polystyrene are efficient catalysts.
Sulfonated polystyrene compounds (SPS) were synthesized from linear polystyrene (PS), leading to catalytically active polymeric materials with sulfonation degrees between 5.0 and 6.2
mmol SO
3H/g of dry polymer. Catalyst performance was evaluated in beef tallow and soybean oil transesterification with ethanol and methanol. The SPS were used at 20
mol% of –SO
3H groups in relation to the oil mass. Methanol:oil molar ratios of 3:1, 6:1, 9:1, and 100:1 were employed, and the reactions lasted between 3 and 18
h. The SPS samples were insoluble in the reaction media and led to conversions of 85 and 75% of refined soybean oil and beef tallow with a 53
mg KOH/g acid number, respectively. There was an increase in ester production for reactions carried out at higher methanol:oil molar ratio and, in some cases, products with as much as 94% methyl ester content were obtained. Therefore, sulfonated polymeric compounds obtained from linear polystyrene are efficient catalysts for the alcoholysis of refined vegetable oils and raw materials containing high acid numbers.
Phenolic antioxidants have limited solubility in biodiesel, so this research developed new antioxidants by addition of hydroquinone and catechol on unsaturated fatty acid esters, which improved ...significantly the oxidative stability of rapeseed biodiesel. This new compound class is more soluble in biodiesel than hydroquinone and catechol, in same molar concentrations. The aging of biodiesel was studied using Metrohm model 743 Rancimat and PetroOxy devices and it was possible to observe an improvement on oxidation stability in both testing using these new antioxidants. Especially the additives 2MB3 and 4MB3 improved the induction period (IP) of rapeseed methyl ester (RME‐B100), from 4 to 63 and 65 h, respectively, with 30 mmol/kg of additives, while hydroquinone in comparison improves the stability to 25 h in the same molar concentration. This new class of antioxidants is promising to enhance oxidative stability of biodiesel, showing the capability of such additives to be commercialized for this purpose.
Practical applications: Biodiesel is obtained by different raw materials, so the composition is different according to the source. The biodiesel with higher amounts of unsaturated fatty acids is more susceptible to oxidation than those with higher saturation. To solve problems caused by oxidative deterioration of biodiesel, this research aimed to synthesize a new class of antioxidants as an alternative for preventing and minimize oxidative damage of biofuels.
Rapeseed biodiesel without any addition of additive was out of specification according to EN 14214, which regulates oxidative stability greater or equal to 8 h. The additives herein obtained improved significantly the oxidation stability for rapeseed biodiesel by more than 100%.
Rapeseed biodiesel without any addition of additive was out of specification according to EN 14214, which regulates oxidative stability greater or equal to 8 h. The additives herein obtained improved significantly the oxidation stability for rapeseed biodiesel by more than 100%.
The executive and legislative branches of Brazilian government have either proposed or taken a variety of initiatives that threaten biodiversity and ecosystems. Opposition by the scientific community ...has largely been ignored by decision-makers. In this short essay, we present recent examples of harmful policies that have great potential to erode biodiversity, and we suggest ways to communicate scientific knowledge to decision- makers. If the current gap between conservation science and policies is not filled, the country will threaten the maintenance of its natural capital and, consequently, the sustainability of essential societal activities in the long term.
To evaluate the short term safety and potential therapeutic effect of allogenic adipose tissue-derived stromal/stem cells (ASCs) + cholecalciferol in patients with recent-onset T1D.
Prospective, ...phase II, open trial, pilot study in which patients with recent onset T1D received ASCs (1 × 10
cells/kg) and cholecalciferol 2000 UI/day for 3 months (group 1) and were compared to controls with standard insulin therapy (group 2). Adverse events, C-peptide (CP), insulin dose, HbA1c, time in range (TIR), glucose variability (continuous glucose monitoring) and frequency of CD4
FoxP3+ T-cells (flow cytometry) were evaluated at baseline (T0) and after 3 months (T3).
13 patients were included (8: group 1; 5: group 2). Their mean age and disease duration were 26.7 ± 6.1 years and 2.9 ± 1.05 months. Adverse events were transient headache (
= 8), mild local reactions (
= 7), tachycardia (
= 4), abdominal cramps (
= 1), thrombophlebitis (
= 4), mild floaters (
= 2), central retinal vein occlusion (
= 1, complete resolution). At T3, group 1 had lower insulin requirement (0.22 ± 0.17 vs. 0.61±0.26IU/Kg;
= 0.01) and HbA1c (6.47 ± 0.86 vs. 7.48 ± 0.52%;
= 0.03) than group 2. In group 1, 2 patients became insulin free (for 4 and 8 weeks) and all were in honeymoon at T3 (vs. none in group 2;
= 0.01). CP variations did not differ between groups (-4.6 ± 29.1% vs. +2.3 ± 59.65%;
= 0.83).
Allogenic ASCs + cholecalciferol without immunosuppression was associated with stability of CP and unanticipated mild transient adverse events in patients with recent onset T1D.
NCT03920397.
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