Eco-innovation assessment of biodigesters technology: an application in cassava processing industries in the south of Brazil,Parana state

Clean Technologies and Environmental Policy - Eco-innovations are innovations capable of helping to reduce the environmental impacts of production processes. In this sense, the adoption of models...     

A Novel Method For Fabricating Cr-Doped Alpha-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Nanoparticles: Green Approach To Nanotechnology

The aim of this work was to produce Cr-doped alpha-alumina nanoparticles using a modified sol–gel method that employs the complexation capacity of natural organic matter (NOM). For this synthesis, the initial pH of the sol was adjusted to 4.0, and final calcination of the xerogel was performed at 1100?°C for 4 h. XRD and FTIR analyses confirmed that the hexagonal α-Al₂O₃ phase was produced under these conditions. Chromaticity analyses revealed that more intense pink colors were obtained for the samples with higher Cr concentrations. XANES measurements showed that the oxidation state of chromium in the alumina matrix was strongly dependent on the dopant concentration and that it was possible to produce samples free from Cr(VI). The photo- and radioluminescence spectra of the nanoparticles were found to be sensitive to the dopant concentration. All these findings demonstrated that the synthesis procedure using NOM could provide considerable environmental, technological, and economic benefits.     

Effect of surface conditioning methods,adhesive systems and resin composite on repair strength of dimethacrylate and silorane resin composites

This study evaluated the effect of surface conditioning methods and adhesive systems on the repair bond strength of resin composites. Specimens (FLS: Filtek LS) (N = 144) were prepared using a silicone matrix. The specimens were stored in distilled water and then were randomly divided into the twelve groups (n = 12) according to the surface conditioning method (unground or diamond bur) and adhesive system (no adhesive, LS: Filtek LS, AS: Adper Scotchbond SE Plus) and resin composite (FLS: Filtek LS; FS: Filtek Supreme). The specimens were fixed in an hourglass-shaped silicone matrix and the other half of the specimen was restored. Hourglass-shaped specimens (n = 12) were used as positive control to measure the cohesive strength of the resin composite (Filtek LS). Microtensile bond test was performed (0.5 mm/min) and failure types were analyzed. Data were analyzed using two-way analysis of variance, Tukey’s and Dunnett’s tests (α = 0.05). Adhesive protocol and resin composite significantly affected the results (p < 0.05). For the FS composite, the highest results were obtained using LS adhesive with (18.4 ± 7.7) and without (18.8 ± 4.8) bur roughening. For FLS composite, the highest results were obtained using AS adhesive with (33.2 ± 7.1) and without (25.7 ± 3.6) bur roughening. Without the use of adhesive resin, significantly lower bond strength results were observed with both LS (5 ± 2.1, 4.5 ± 1.5) and FLS (2.2 ± 1.2, 4.4 ± 1.1) for unground and diamond bur roughened groups, respectively (p < 0.0001). Cohesive strength of the FLS (52.3 ± 7.6) was significantly higher than any of the repaired groups (p < 0.0001). FS–LS combination and the groups repaired without adhesive presented more adhesive (Type I) failures.     

Can the regenerative potential of an alkali-free bioactive glass composition be enhanced when mixed with resorbable β-TCP?

The addition of resorbable β-tricalcium phosphate (β-TCP) to other bone substitute materials such as hydroxyapatite (HA) has been pointed out as a suitable strategy to enhance the regenerative potential of bone grafts made thereof. To check the generalization of this hypothesis, a new synthetic composite bone graft material consisting of a mixture of 30 vol% of pure β-TCP and 70 vol% of FastOs^®BG (an alkali-free bioactive glass - BG) was prepared and tested in vivo. The in vivo performance of the new synthetic bone graft (30β-TCP-70FastOs^®BG) was compared with those of FastOs^®BG alone and of adbone^®BCP, a biphasic calcium phosphate, consisting of 75% of HA and 25% of β-TCP. Two defects with 4 mm diameter were performed in Wistar rats calvaria and filled with the bone graft materials. The animals were sacrificed after 9 weeks of implantation and the calvaria was excised. Empty bone defects were used as negative control. The percentages of new bone formed (von Kossa staining) were always higher in the treated groups (FastOs^®BG, 30β-TCP-70FastOs^®BG and adbone^®BCP) than in empty group. There were differences with statistical significance between empty and FastOs^®BG groups and between empty and adbone^®BCP groups. But the differences observed between empty and 30β-TCP-70FastOs^®BG groups were less remarkable. The results demonstrated the superior bone regeneration ability of FastOs^®BG alone, which was not further enhanced by adding β-TCP in the composition, confirming its already proven regenerative potential.     

Mixing‐sequence controlled selective localization of carbon nanoparticles in PLA/PCL blends

This work proposes modifying the adding sequence of components during the production of poly(lactic acid) (PLA) and poly(ε‐caprolactone) (PCL) ternary systems with multiwalled carbon nanotubes (CNT) or graphene nanoplatelets (GN), in order to analyze the nanoparticles’ selective localization in terms of the competition between different factors, such as kinetics, thermodynamics, rheology, and geometry. In the studied system, the PLA's viscosity is higher than the PCL's and the difference in interactions between the CNT or the GN/PLA and the CNT or the GN/PCL is small, meaning the viscosity effects could dominate. However, other factors, such as thermodynamics and geometry, can be observed to compete with the rheological factor, depending on the mixing sequences. Depending on the processing time, a competition between thermodynamics and rheological factors could be observed when the nanoparticles had contact first with the thermodynamically favored phase. The competition between geometrical and rheological factors was observed in the presence of GN in the PLA phase, in the system in which the GN was added first to the PLA phase, which is the phase of lowest affinity. POLYM. ENG. SCI., 59:323–329, 2019. © 2018 Society of Plastics Engineers     

Microwave effect: analyzing citations from classic theories and their reinventions—a case study from a classic paper in aquatic ecology—Brooks & Dodson, 1965

Citations play an essential role in creating a knowledge network and recognizing relevant contributions during the process of scientific production. Despite the citations establishing the links between new evidence and the preceding ideas, classic articles may not be cited adequately. Our aim is to identify if classic studies are cited over time and if the recent studies are producing new knowledge or just “giving a new look” to pre-existing ideas. We evaluated whether the theory proposed by Brooks and Dodson (Science 150(3692): 28–35, 1965)-Size-efficiency Hypothesis was referenced in studies on the subject since its publication. Through the analysis of 1480 scientific papers, we quantified—from 1965 to 2018—the citation index (CI) of the original article considering the number of articles produced on the topic per year and the number of citations to other authors (intermediaries). We observed that 60% of the papers and 59% of the intermediaries do not refer to the original article. The CI was low and negatively affected by the age of the original article, showing that the frequency of citation was lower than the rate by which articles on the topic were published. There is a tendency to cite more recent articles and articles that corroborate their own findings. Our data illustrated the microwave effect, in which pre-existing ideas and theories are “reheated” by more recent articles where little of the original idea is modified. The microwave effect can create the impression of scientific advancement when there is little being added to the knowledge already produced.

     

Magnetization study in LaCr1−xAlxO3 (0 ≤ x ≤ 0.95)

The structural and magnetic properties of the Al-doped LaCrO₃ have been investigated. The samples were produced by combustion method using urea as fuel. X-ray diffraction measurement shows that all samples are formed in a single phase. It is observed that increasing the Al content induces a structural phase transition from orthorhombic to a rhombohedral structure. The magnetic measurements indicate that all samples have an antiferromagnetic order with a strong decrease in the magnetic ordering temperature with increasing Al content. The consistent variation of the magnetic moment confirms that the Al³⁺ ion replaced the Cr³⁺ ion on the B-site of the perovskite.     

Micro and Macro Network Slicing: An Experimental Assessment of the Impact of Increasing Numbers of Slices

Wireless Personal Communications - The fifth generation (5G) telecommunications network aims not only to enhance traffic performance and allow efficient management, but also to enable it to...