Characterization of LDH (phyllosilicate/carbonate) type compounds formed in the pozzolanic reaction of phyllosilicate-rich industrial waste

Reutilization of industrial waste products as cement additives yields a number of secondary materials, yet their identification is not always trivial. Confirmation of the formation of a LDH-type (phyllosilicate/carbonate) material is the main purpose of this study. Mineralogically, organic and inorganic compounds form some industrial wastes, among which the phyllosilicates are prominent. Crystalline and amorphous hydrated phases appeared during the pozzolanic reaction in a dehydroxylated phyllosilicate/lime system, whose controlled activation yielded dehydroxylated products with high pozzolanic properties. The LDH-type (phyllosilicate/carbonate) material was one of the reaction products; this material could be considered as the superposition type 1:1 of tetrahedral layers of silicon and aluminum and octahedral layers of aluminum (dehydroxylated kaolinite), generating a positive charge in the interlaminar region compensated by carbonate anions with a basal spacing (001) measured by XRD at 7.57Å. Therefore, several techniques were used to determine whether they could be included in the structural group named Layered Double Hydroxides (LDHs), as they are, too, laminar layers of oxides and hydroxides with a positive laminar charge in the interlayer region compensated by the presence of anions with similar basal spacing. In this research, the effects of activation temperature and calcite proportion were analyzed on the hydrated phases formed after 28 days of pozzolanic reaction in a metakaolin (MK)/lime system. The MK was obtained from a mix of 1:1; 2:1 and 3:1 kaolinite:calcite mixture, thermally activated at 750°C for 2 hours, comparing it with kaolinite activated at 600°C for 2 hours. As the most LDH-rich sample, the 1:1 LDH-type (phyllosilicate/carbonate) phase was characterized using XRD, SEM-EDX, HRTEM-EDX, FTIR, NMR-MAS, and Raman spectroscopy.     

Development of novel soy-protein-based superabsorbent matrixes through the addition of salts

The addition of salts, like sodium bicarbonate (SB) or carbonate (SC), into the formulation of bioplastic materials may alter their hydrophilic character to a significant extent. Soy protein isolate (SPI) is a byproduct of the soybean oil industry, which, when properly blended with glycerol (GL), can be further processed through a lab-scale injection molding device. A maximum in the water uptake around 2250 or 2500% is obtained for bioplastics obtained when either SB or SC content is around 1 wt %, respectively. Thus, they exceed the limit to be considered superabsorbent materials (SAMs). Regarding their mechanical properties, a higher presence of SB within the SPI/GL matrix provides materials with a higher extensibility and lower Young's modulus. A higher water uptake is observed after replacing SB for SC in the formulation, probably related to a higher alkalinization of the material as well as to the high hydrophilicity of the carbonate. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47012.     

Effect of different acids during the synthesis of urea-formaldehyde adhesives and the mechanical properties of medium-density fiberboards bonded with them

The characteristics of urea-formaldehyde (UF) adhesives condensed by catalysis with four different acids, namely formic (HCOOH), hydrochloric (HCl), phosphoric (H₃PO₄), and sulfuric (H₂SO₄) acids, under alkaline–acidic–alkaline conditions at a molar ratio F/U = 1.12 were studied. The thermal curing properties of UF adhesives catalyzed with acid were characterized by differential scanning calorimetry at 10 °C/min heating rate. The resin structure examined by ¹³C-NMR spectroscopy showed that the resin catalyzed with HCl had a lower proportion of methylol groups, resulting in a lower level of formaldehyde emission. It was interesting to note that HCOOH resulted in the best overall mechanical properties of the medium-density fiberboard (MDF) panels. The HCl catalyst resulted in the poorest performance, providing the lowest internal bond strength, modulus of elasticity, and thickness swelling, with the exception of the free formaldehyde content. The resin catalyzed with H₂SO₄ had the highest free formaldehyde and the highest formaldehyde emission. H₂SO₄ and H₃PO₄ resulted in MDF mechanical properties relatively lower than for HCOOH. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47256.     

Synthesis and characterization of cellulose acetate from royal palm tree agroindustrial waste

This study provides a novel value‐added utilization of the agroindustrial waste of royal palm tree leaf sheath to produce cellulose acetate. One of the motivations of this work was the fact that Brazil is one of the largest heart of palm producers in the world. However, as a result of extraction and processing, tons of waste are generated and discharged to the environment. Such waste is rich in lignocellulosic material, which could be reused to obtain derivatives of interest and commercial value. The synthesis of cellulose acetate was performed through a homogeneous acetylation reaction. Three different conditions were tested for delignification of the raw material, which resulted in a reduction in lignin content from 17.75 to 7.72%. The highest yield of cellulose acetate reached 99.5%, with degree of substitutions ranging between 2.08 and 2.82, which indicates satisfactory conversion. The Fourier transform infrared spectrum showed that practically all hydroxyl groups were replaced by acetate groups; this was also confirmed by nuclear magnetic resonance analysis. X‐ray diffraction analysis showed that the cellulose acetate crystallinity index was 8.9%. This demonstrates the viable potential of cellulose acetate production with low cost and use of highly available agroindustrial waste. POLYM. ENG. SCI., 59:891–898, 2019. © 2018 Society of Plastics Engineers     

A statistical model for the failure of glass plates due to nickel sulfide inclusions

Nickel Sulfide (NiS) inclusions can provoke the rupture of thermally treated glass due to a phase transformation with volume increase that stresses the surrounding glass. Starting from a Pareto statistics for the population of inclusion sizes, from an assumed kinetics of the phase transformation, a micro-mechanically motivated model provides the statistical characterization of the probability of spontaneous failure of glass during lifetime. A distinction based upon the composition of NiS is used to discuss the effects of the heat soak test (HST), where glass remains at high temperature for a certain time to speed-up the phase transformation and destroy those elements with critical inclusions. Three functions à la Weibull for the probability of spontaneous rupture during lifetime are theoretically derived for the case of no HST, short HST, and long HST. In particular, the probability of collapse for long HSTs depends upon the holding time in the oven. An explanatory example shows the potentiality of the model for optimizing the HST parameters toward a target probability of failure, but experimental campaigns are needed for a proper calibration.     

Short communication: Space allocation in intensive Mediterranean buffalo production influences the profile of functional biomolecules in milk and dairy products

The aim of the present study was to determine if space allocation influenced the concentration of biomolecules in buffalo milk and dairy products. Intensively housed buffaloes (n = 96) were randomly assigned to 2 groups according to days in milk, parity, and milk yield: group S10 had a space allocation of 10 m² per buffalo and group S15 had a space allocation of 15 m² per buffalo. Individual milk yield was recorded daily. Twice a month, a bulk milk sample was collected for each group, as well as whey, ricotta, and mozzarella cheese, to assess cheese yield and to conduct HPLC-electrospray ionization-tandem mass spectrometry, milk antioxidant activity, and cell viability analyses. We tested milk extracts from the 2 groups in vitro to evaluate their efficacy in counteracting endothelial oxidative damage induced by high glucose. We evaluated reproductive function in 28 buffaloes from each group using the Ovsynch-timed artificial insemination program. We observed no differences in milk quantity or quality in terms of fat, protein, or lactose, and reproductive function did not differ between the 2 groups. Compared with group S10, group S15 had higher concentrations of carnitine (56.7 ± 1.1 vs. 39.8 ± 0.7 mg/L in milk and 40.9 ± 0.8 vs. 31.7 ± 0.7 mg/L in whey), acetyl-l-carnitine (51.9 ± 0.3 vs. 39.7 ± 0.7 mg/L in milk and 41.1 ± 1.7 vs. 28.7 ± 2.6 mg/L in whey), propionyl-l-carnitine (34.8 ± 1.0 vs. 21.0 ± 0.9 mg/L in milk and 26.9 ± 0.8 vs. 17.6 ± 1.2 mg/L in whey), glycine betaine (23.1 ± 1.9 vs. 13.5 ± 1.6 mg/L in milk and 10.7 ± 0.4 vs. 7.9 ± 0.5 mg/L in whey), and δ-valerobetaine (24.2 ± 0.5 vs. 16.7 ± 0.5 mg/L in milk and 22.0 ± 0.9 vs. 15.5 ± 0.7 mg/L in whey). Group S15 also had higher total antioxidant activity than group S10 (56.7 ± 1.9 vs. 46.4 ± 1.13 mM Trolox equivalents). Co-incubation of high-glucose-treated endothelial cells with milk extracts from group S15 improved cell viability compared with cells treated with high glucose only; it also reduced intracellular lipid peroxidation (144.3 ± 0.4 vs. 177.5 ± 1.9%), reactive oxygen species (141.3 ± 0.9 vs. 189.3 ± 4.7 optical density units), and cytokine release (tumor necrosis factor-α, IL-1β, IL-6). Greater space allocation was associated with higher levels of biomolecules in buffalo milk. This could have been the result of improved welfare in buffaloes that were allocated more space.     

Accumulation parameters and seasonal trends for PCBs in temperate and boreal forest plant species

The concentration of polychlorinated biphenyls (PCBs) in the air and vegetation was measured periodically in two alpine forests, during the growing season. Foliage samples from nine plant species typical of the temperate and boreal environment were collected and analyzed. Leaf concentrations of tri- and tetra-CBs showed fast response times with changing temperature and gas-phase concentrations, suggesting that a partitioning equilibrium is approached relatively rapidly (few days) in the field. Heavier compounds showed kinetically limited accumulation trends, not reaching equilibrium during the growing season. Results were used to estimate the bioconcentration factors or equilibrium plant/air partition coefficient (KPA) for each species. Values of log KPA (calculated on a mass/volume basis) ranged between 0.78 and 1.96 and were correlated to the log KOA. Uptake trends of the higher chlorinated compounds showed intraspecific differences which were partially explained by the specific leaf area (SLA).     

Fitting of colony diameter and ergosterol as indicators of food borne mould growth to known growth models in solid medium

Growth of a range of 14 common food spoilage fungal species was evaluated along time as a function of both colony diameter and ergosterol content on malt extract agar. Growth was assessed under different environmental conditions following a central composite design. The suitability of using either linear, Gompertz's or Baranyi's models for primary modelling of the results was tested. Regarding colony diameters, using either linear or asymptotic Baranyi's function gave better estimations of growth rate and lag phase when no asymptotic trend was observed. When a decrease in growth rate was observed with time, standard Baranyi's model was chosen, although the search for new mechanistic models specific for moulds would probably improve the estimations. The use of Gompertz equation led, in general, to overestimated parameters. Ergosterol showed good performance as a fungal growth indicator for the whole range of species. Finally, significant correlation coefficients were found between ergosterol and colony diameters, suggesting that both parameters may be useful for primary modelling and thus for subsequent secondary modelling.