Using mathematical methods for designing optimal mixtures for building bricks prepared by solid industrial waste

This study evaluates the use of solid industrial waste generated by a water treatment plant (WTP) at a pulp mill in Brazil for manufacturing building bricks. The sludge from the WTP was mixed with three different wastes generated by the same factory (dregs, grits, and lime mud) and other wastes generated from crushing and grinding granite rock (granite fines). Mathematical and statistical methods are proposed for designing mixtures that satisfy the material properties for ceramic processing and the mechanical properties for the end product. A method for solving a linear system of equations using fewer equations than variables was required, as the number of materials exceeded the number of reference grain size distributions. This type of system is generally compatible and indeterminate. To obtain feasible solutions, a combination-of-variables method is proposed to optimize the mixture design. The formulation of the mixtures was based on the grain size distribution of the residues and the proportions of calcium, sodium, and potassium oxides in the mixtures. The nonparametric Kruskal–Wallis test and the median test were applied for all mixtures, followed by a multiple comparison test of classes. The mechanical properties of the specimens were evaluated after drying (linear shrinkage and flexural strength) and firing (ignition loss, linear shrinkage, and flexural strength) according to the Brazilian Association of Technical Standards and Brazilian Standards for red ceramics.     

Green attributes converged within multifunctional technology products

This article analyzes the way in which the convergence of green attributes in multifunctional technological products influences consumers’ purchase intentions. Due to the recent growth in convergent products, technology users and consumers must choose among numerous different applications that can be perceived as either utilitarian or hedonic. This article suggests that new products launched on the market include attributes that are connected to sustainability and provide added value to consumers in their process of decision making. The primary question addressed in this article concerns whether an increase or decrease in consumer intention is based on the perception of the product’s utility, and the consumer’s prior experience and attitude toward green products. A 2 × 2 × 2 experiment was conducted to evaluate utilitarian or hedonic convergence, green attribute integration, and predisposition for (involvement with) green products. We propose that consumer value increases for those consumers with a high perception of green integration connected to a high predisposition for green devices, which increases the utilitarian value of the product or justifies the hedonic purchase of technological equipment.     

Microwave-assisted processing of silicone/PMMA blends for maxillofacial prostheses

Maxillofacial prostheses replace soft tissues that were lost due to disease or trauma, providing the restoration of the original anatomy and protecting the injured tissue. Silicone is the most widely used material, but the crosslinking process usually takes 24 hours to be completed. In this study, silicone/poly(methyl-methacrylate) blends were prepared at room temperature and assisted by microwave irradiation. The samples were characterized by confocal Raman microscopy and scanning electron microscopy/energy-dispersive X-ray spectroscopy. The microwave-assisted crosslinking is completed within 10 minutes and leads to better adhesion between silicone and PMMA than samples processed at room temperature. The methodology was adapted for the fabrication of prostheses for 50 patients with an average lifetime of 3 years, which is higher than the averages reported earlier in the literature (6-24 months).     

Physics students’ performance using computational modelling activities to improve kinematics graphs interpretation

The purpose of this study was to investigate undergraduate students’ performance while exposed to complementary computational modelling activities to improve physics learning, using the softwares Modellus. Interpretation of kinematics graphs was the physics topic chosen for investigation. The theoretical framework adopted was based on Halloun’s schematic modelling approach and on Ausubel’s meaningful learning theory. The results of this work show that there was a statistically significant improvement in the experimental group students’ performance when compared to the control group, submitted just to a conventional teaching method. Students’ perception with respect to the concepts and mathematical relations, as well as the motivation to learn, originated by the activities, have played a fundamental role in these findings.     

Radical-scavenging activity of extracts from Cordia verbenacea DC obtained by different methods

The possibility of using the leaves of Cordia verbenacea as a new source of natural antioxidant compounds was investigated. In the present work, extracts from C. verbenacea were obtained using different extraction methods: supercritical fluid extraction (SFE), Soxhlet (SE), hydrodistillation and maceration, with the objective to evaluate the methods in terms of yield and antioxidant potential. The high-pressure technique was applied using pure CO₂ and CO₂ with co-solvent at different temperatures and pressures (30, 40 and 50 °C and 100, 200, and 300 bar). Organic solvents with different polarities were used to obtain extracts by low-pressure extraction processes. The extracts were evaluated according to their antioxidant activity using total phenolic content, scavenging abilities on DPPH radical, total antioxidant activities (ABTS^•+), superoxide anion radical-scavenging (O₂^•) and protection against lipid peroxidation in vitro (LPO). Ethyl acetate fraction obtained by maceration and extract isolated by SE using 25% aqueous mixture of ethanol possessed the highest scavenger activity against DPPH radical (IC₅₀ = 9.2 ± 0.4 μg/ml, IC₅₀ = 27.4 ± 0.1 μg/ml, respectively). The SFE with 8% ethanol as a co-solvent produced extracts with distinguished increase in the antioxidant activity. The Soxhlet extract with ethyl acetate exhibited a strong reduction of lipid peroxidation (IC₅₀ = 209 ± 3 μg/ml) value comparable to the standard rutin (IC₅₀ = 203 ± 2 μg/ml). The results indicate that extracts of C. verbenacea have important potential as a source of bioactive compounds with antioxidant activity.     

Lipase C,Hepatic Type −250A/G (rs2070895) Variant Enhances Carotid Atherosclerosis in Normolipidemic and Asymptomatic Individuals from Brazil

The common genetic variant in the promoter region of the hepatic lipase gene [LIPC −250G/A(rs2070895)] has an ambiguous association with cardiovascular disease. In this context, our study was performed to identify the relationships between the rs2070895 with carotid atherosclerosis, plasma lipids, and parameters of reverse cholesterol transport. A total of 285 normolipidemic and asymptomatic participants from an initial sample of 598,288 individuals (inclusion criteria: LDL-C ≤130 mg/dL and triglycerides ≤150 mg/dL; age: 20–75 years, both genders; confirmation of clinical, anthropometric and laboratory data; attended all visits; DNA was achieved to perform genetic analysis) were enrolled and the rs2070895 variant was genotyped by TaqMan® OpenArray® Plataform. Carotid intima-media thickness and the screening of atherosclerotic plaques were determined by B-mode ultrasonography. The rs2070895 genotype frequencies were 0.44, 0.41, and 0.15 (GG, GA, and AA, respectively). Logistic regression analysis showed that the risk of having plaques was increased in participants carrying the AA or AG genotypes (OR = 3.90; 95% CI = 1.54–10.33), despite an increase in high-density lipoprotein cholesterol levels, HDL diameter and apolipoprotein A-I, as compared to the GG genotype. Hepatic lipase and endogenous lecithin cholesterol acyl transferase activities were reduced (38% and 19%, respectively) and lipoprotein lipase was increased by 30% (AA vs GG). Our results provide evidence that the AA or AG genotypes of the rs2070895 were associated with carotid atherosclerosis in apparently healthy participants, probably as a consequence of reduced reverse cholesterol transport and accumulation of HDL subfraction 2 rich in triglycerides and depleted in cholesteryl esters that could become dysfunctional.