Acceptance Threshold Hypothesis is Supported by Chemical Similarity of Cuticular Hydrocarbons in a Stingless Bee, Melipona asilvai

The ability to discriminate nestmates from non-nestmates in insect societies is essential to protect colonies from conspecific invaders. The acceptance threshold hypothesis predicts that organisms whose recognition systems classify recipients without errors should optimize the balance between acceptance and rejection. In this process, cuticular hydrocarbons play an important role as cues of recognition in social insects. The aims of this study were to determine whether guards exhibit a restrictive level of rejection towards chemically distinct individuals, becoming more permissive during the encounters with either nestmate or non-nestmate individuals bearing chemically similar profiles. The study demonstrates that Melipona asilvai (Hymenoptera: Apidae: Meliponini) guards exhibit a flexible system of nestmate recognition according to the degree of chemical similarity between the incoming forager and its own cuticular hydrocarbons profile. Guards became less restrictive in their acceptance rates when they encounter non-nestmates with highly similar chemical profiles, which they probably mistake for nestmates, hence broadening their acceptance level.     

Experimental campaign,modeling, and sensitivity analysis for the molecular distillation of petroleum residues 673.15 K+

This research activity proposes a sensitivity analysis of the molecular distillation process by focusing the attention on the response of the overall distillate flow rate under several conditions of distillation temperature and feed flow rate. Specific equations to characterize physicochemical properties of petroleum residues have been formulated by means of ASTM-based experimental campaigns combined with specific optimization techniques.     

Structure and analgesic properties of layered double hydroxides intercalated with low amounts of ibuprofen

Ibuprofen‐intercalated layered double hydroxides (LDH‐IBU) have been successfully synthesized via a coprecipitation method with a nominal [Al³⁺]/[Mg²⁺] ratio of 0.5 and a variable molar IBU/([Al³⁺]+[Mg²⁺]) ratio of 0, 0.15, 0.18, 0.24, 0.36, and 0.72. After an accurate determination of the composition, the nature of the intercalated species and the effective intercalation yield from to IBU, it is shown that the synthesis route used allows a good control of the quantity of intercalated IBU within the LDH framework. This results in different samples with full or partial IBU intercalation in the interlayer space in exchange of nitrate anions. The analysis of the X‐ray diffraction basal reflections reveals that the intercalation of IBU in the framework only increases the basal distances with no alteration of the brucite‐type layers. Also, a computational study used to model the positions and shapes of the basal reflections showed that the structure of the nonfully intercalated compounds follows a random interstratification scheme. Finally, three samples ranging from slightly to fully IBU‐intercalated galleries were selected for preliminary in vivo assays. These tests showed a strong tendency that after 24 hours the low yield of IBU‐intercalated compounds are almost as efficient as the fully intercalated sample.     

Moisture Prediction During Paste Drying in a Spouted Bed

The objective of this work was to derive and experimentally verify a hybrid CST/neural network model to determine the moisture content of the powders produced during paste drying in a spouted bed and describe the highly coupled heat and the mass transfer. The model was derived from overall energy and mass balances with effective drying kinetics given by a neural network. Simulations were performed in MatLab and drying experiments for model verification were carried out for different pastes in a conical, semi-pilot-scale spouted bed.     

Effects of low-temperature aging on AISI 444 steel

The consequences of aging at 400 and 475 °C on the mechanical properties, corrosion resistance, and magnetic properties of the ferritic stainless steel (SS) AISI 444 were investigated. Age hardening was measured as a function of aging time at both temperatures and was found to be more intense at 475 °C. The localized corrosion susceptibility increased, while the impact toughness decreased with aging time. These two effects were also more important at 475 °C. Unlike duplex SSs, AISI 444 did not present any variation in coercive force or Curie temperature with aging time. The effects on the Mössbauer spectra were also determined and analyzed.     

Development and Characterization of a Multiplex Assay to Quantify Complement-Fixing Antibodies against Dengue Virus

Antibodies capable of activating the complement system (CS) when bound with antigen are referred to as “complement-fixing antibodies” and are involved in protection against Flaviviruses. A complement-fixing antibody test has been used in the past to measure the ability of dengue virus (DENV)-specific serum antibodies to activate the CS. As originally developed, the test is time-consuming, cumbersome, and has limited sensitivity for DENV diagnosis. Here, we developed and characterized a novel multiplex anti-DENV complement-fixing assay based on the Luminex platform to quantitate serum antibodies against all four serotypes (DENV1-4) that activate the CS based on their ability to fix the complement component 1q (C1q). The assay demonstrated good reproducibility and showed equivalent performance to a DENV microneutralization assay that has been used to determine DENV serostatus. In non-human primates, antibodies produced in response to primary DENV1-4 infection induced C1q fixation on homologous and heterologous serotypes. Inter-serotype cross-reactivity was associated with homology of the envelope protein. Interestingly, the antibodies produced following vaccination against Zika virus fixed C1q on DENV. The anti-DENV complement fixing antibody assay represents an alternative approach to determine the quality of functional antibodies produced following DENV natural infection or vaccination and a biomarker for dengue serostatus, while providing insights about immunological cross-reactivity among different Flaviviruses.     

Methodology to parameterize and assess the burn-zinc technique in the resistance spot welding process

To minimize the detrimental effects of zinc during resistance spot welding of galvanized plates, a technique known as Burn-Zinc is usually employed. However, there is not much information and studies available in the current literature about when and how to use this technique. The objective of this paper is to assess and understand this technique. To do so, a methodology to determine the ideal burn-zinc parameters as a function of the plates was proposed. This methodology was evaluated by a series of welds by systematically varying current and pressure at compatible levels for zinc burning. High-speed filming, synchronized with electrical signals, was employed to visualize and to analyse results. Once the burn-zinc parameters were defined, new welds were performed with and without the burn-zinc application. The proposed experimental procedure was shown to be efficient for checking and parametrizing the burn-zinc technique. However, there was evidence that the application of burn-zinc does not always lead to a reduction in operating time.     

Cyclooxygenase Inhibition Alters Proliferative,Migratory, and Invasive Properties of Human Glioblastoma Cells In Vitro

Prostaglandin E₂ (PGE₂) is known to increase glioblastoma (GBM) cell proliferation and migration while cyclooxygenase (COX) inhibition decreases proliferation and migration. The present study investigated the effects of COX inhibitors and PGE₂ receptor antagonists on GBM cell biology. Cells were grown with inhibitors and dose response, viable cell counting, flow cytometry, cell migration, gene expression, Western blotting, and gelatin zymography studies were performed. The stimulatory effects of PGE₂ and the inhibitory effects of ibuprofen (IBP) were confirmed in GBM cells. The EP2 and EP4 receptors were identified as important mediators of the actions of PGE₂ in GBM cells. The concomitant inhibition of EP2 and EP4 caused a significant decrease in cell migration which was not reverted by exogenous PGE₂. In T98G cells exogenous PGE₂ increased latent MMP2 gelatinolytic activity. The inhibition of COX1 or COX2 caused significant alterations in MMP2 expression and gelatinolytic activity in GBM cells. These findings provide further evidence for the importance of PGE₂ signalling through the EP2 and the EP4 receptor in the control of GBM cell biology. They also support the hypothesis that a relationship exists between COX1 and MMP2 in GBM cells which merits further investigation as a novel therapeutic target for drug development.     

Photoprotective Role of Photosynthetic and Non-Photosynthetic Pigments in Phillyrea latifolia: Is Their “Antioxidant” Function Prominent in Leaves Exposed to Severe Summer Drought?

Carotenoids and phenylpropanoids play a dual role of limiting and countering photooxidative stress. We hypothesize that their “antioxidant” function is prominent in plants exposed to summer drought, when climatic conditions exacerbate the light stress. To test this, we conducted a field study on Phillyrea latifolia, a Mediterranean evergreen shrub, carrying out daily physiological and biochemical analyses in spring and summer. We also investigated the functional role of the major phenylpropanoids in different leaf tissues. Summer leaves underwent the most severe drought stress concomitantly with a reduction in radiation use efficiency upon being exposed to intense photooxidative stress, particularly during the central hours of the day. In parallel, a significant daily variation in both carotenoids and phenylpropanoids was observed. Our data suggest that the morning-to-midday increase in zeaxanthin derived from the hydroxylation of ß-carotene to sustain non-photochemical quenching and limit lipid peroxidation in thylakoid membranes. We observed substantial spring-to-summer and morning-to-midday increases in quercetin and luteolin derivatives, mostly in the leaf mesophyll. These findings highlight their importance as antioxidants, countering the drought-induced photooxidative stress. We concluded that seasonal and daily changes in photosynthetic and non-photosynthetic pigments may allow P. latifolia leaves to avoid irreversible photodamage and to cope successfully with the Mediterranean harsh climate.