Nanostructured bimetallic alloys prepared via mechanochemical synthesis as PEMFC electrocatalysts for automotive applications

Pt–Co alloys prepared by high energy ball milling synthesis were tested as electrocatalysts for hydrogen fueled Polymer Electrolyte Membrane Fuel Cells (PEMFC). In the present contribution we report on the first results regarding the electrochemical behaviour of two samples of Pt–Co alloys. One sample contains 20 wt.% alloy Pt:Co in the molar ratio 0.25:0.75 and C 80 wt.% and the second one Pt:Co in the molar ratio 0.75:0.25 and C 80 wt.%. The electrochemically active surface (EAS) was determined by cyclic voltammetry data while the electrocatalyst performance in a real cell was obtained by assembling Membrane Electrode Assemblies (MEAs) with the considered sample at the cathode. The results obtained, though indicating a lower performance than all-Pt catalysts, are quite interesting as they point out the importance of the C/Pt, Nafion/Pt and Pt/Co ratios that exert a deep influence onto the cell performance.     

Invited review: Dairy proteins and bioactive peptides: Modeling digestion and the intestinal barrier

Dairy products are one of the most important sources of biologically active proteins and peptides. The health-promoting functions of these peptides are related to their primary structure, which depends on the parent protein composition. A crucial issue in this field is the demonstration of a cause-effect relationship from the ingested protein form to the bioactive form in vivo. Intervention studies represent the gold standard in nutritional research; however, attention has increasingly been focused on the development of sophisticated in vitro models of digestion to elucidate the mechanism of action of dairy nutrients in a mechanistic way and significantly reduce the number of in vivo trials. On the other hand, the epithelial intestinal barrier is the first gate that actively interacts with digestion metabolites, making the intestinal cells the first target tissue of dairy nutrients and respective metabolites. An evolution of the in vitro digestion approach in the study of dairy proteins and derived bioactive compounds is the setup of combined in vitro digestion and cell culture models taking into consideration the endpoint to measure the target organism (e.g., animal, human) and the key concepts of bioaccessibility, bioavailability, and bioactivity. This review discusses the relevance and challenges of modeling digestion and the intestinal barrier, focusing on the implications for the modeling of dairy protein digestion for bioactivity evaluation.     

Human Serine Racemase Weakly Binds the Third PDZ Domain of PSD-95

Human serine racemase (hSR) is a pyridoxal-5′-phosphate (PLP)-dependent dimer that catalyzes the formation of D-serine from L-serine, as well as the dehydration of both L- and D-serine to pyruvate and ammonia. As D-serine is a co-agonist of N-methyl-D-aspartate receptors (NMDARs), hSR is a key enzyme in glutamatergic neurotransmission. hSR activity is finely regulated by Mg²⁺, ATP, post-translational modifications, and the interaction with protein partners. In particular, the C-terminus of murine SR binds the third PDZ domain (PDZ3) of postsynaptic density protein 95 (PSD-95), a member of the membrane-associated guanylate kinase (MAGUK) family involved in the trafficking and localization of glutamate receptors. The structural details of the interaction and the stability of the complex have not been elucidated yet. We evaluated the binding of recombinant human PSD-95 PDZ3 to hSR by glutaraldehyde cross-linking, pull-down assays, isothermal titration calorimetry, nuclear magnetic resonance, and enzymatic assays. Overall, a weak interaction was observed, confirming the binding for the human orthologs but supporting the hypothesis that a third protein partner (i.e., stargazin) is required for the regulation of hSR activity by PSD-95 and to stabilize their interaction.     

Rheological characteristics of bovine colostrum and their correlation with immunoglobulin G

Colostrum, the first mammary secretion after parturition, is an important source of nutrition and passive immunity. In this study, the rheological characteristics of bovine colostrum and their correlation with IgG concentration were investigated. Forty‐nine colostrum samples were collected from 21 Simmental dairy cows at different times after calving. Solid–liquid balance (SLB), macroscopic viscosity index (MVI), elasticity index (EI) and IgG were evaluated in each sample. A significant (P < 0.05) decrease in SLB and EI values as well as in the IgG concentration was observed. A suitable correlation (R² = 0.737) between the EI values and the IgG concentration was evidenced.     

Perinatal Exposure to Phthalates: From Endocrine to Neurodevelopment Effects

Phthalates, as other endocrine disrupting chemicals (EDCs), may alter the homeostasis and the action of hormones and signaling molecules, causing adverse health outcomes. This is true especially for infants, who are both more exposed and sensitive to their effects. Phthalates are particularly harmful when the exposure occurs during certain critical temporal windows of the development, such as the prenatal and the early postnatal phases. Phthalates may also interfere with the neuroendocrine systems (e.g., thyroid hormone signaling or metabolism), causing disruption of neuronal differentiation and maturation, increasing the risk of behavioral and cognitive disorders (ADHD and autistic behaviors, reduced mental, psychomotor, and IQ development, and emotional problems). Despite more studies being needed to better understand the role of these substances, plenty of evidence suggests the impact of phthalates on the neuroendocrine system development and function. This review aims to update the knowledge on the neuroendocrine consequences of neonatal and perinatal exposure to phthalates.     

Gene-Delivery Ability of New Hydrogenated and Partially Fluorinated Gemini bispyridinium Surfactants with Six Methylene Spacers

The pandemic emergency determined by the spreading worldwide of the SARS-CoV-2 virus has focused the scientific and economic efforts of the pharmaceutical industry and governments on the possibility to fight the virus by genetic immunization. The genetic material must be delivered inside the cells by means of vectors. Due to the risk of adverse or immunogenic reaction or replication connected with the more efficient viral vectors, non-viral vectors are in many cases considered as a preferred strategy for gene delivery into eukaryotic cells. This paper is devoted to the evaluation of the gene delivery ability of new synthesized gemini bis-pyridinium surfactants with six methylene spacers, both hydrogenated and fluorinated, in comparison with compounds with spacers of different lengths, previously studied. Results from MTT proliferation assay, electrophoresis mobility shift assay (EMSA), transient transfection assay tests and atomic force microscopy (AFM) imaging confirm that pyridinium gemini surfactants could be a valuable tool for gene delivery purposes, but their performance is highly dependent on the spacer length and strictly related to their structure in solution. All the fluorinated compounds are unable to transfect RD-4 cells, if used alone, but they are all able to deliver a plasmid carrying an enhanced green fluorescent protein (EGFP) expression cassette, when co-formulated with 1,2-dioleyl-sn-glycero-3-phosphoethanolamine (DOPE) in a 1:2 ratio. The fluorinated compounds with spacers formed by six (FGP6) and eight carbon atoms (FGP8) give rise to a very interesting gene delivery activity, greater to that of the commercial reagent, when formulated with DOPE. The hydrogenated compound GP16_6 is unable to sufficiently compact the DNA, as shown by AFM images.     

Influence of sucrose on cold gelation of heat‐denatured whey protein isolate

A solution of heat‐denatured whey proteins was prepared by heating 100 g kg⁻¹ whey protein isolate (WPI) at pH 7.0 to 75 °C for 15 min in the absence of salt. Heat treatment caused the globular protein molecules to unfold, but electrostatic repulsion opposed strong protein–protein aggregation and so prevented gel formation. When the heat‐denatured whey protein solution was cooled to room temperature and mixed with 15 mM CaCl₂, it formed a gel. We investigated the influence of the presence of sucrose in the protein solutions prior to CaCl₂ addition on the gelation rate. At relatively low concentrations (0–100 g kg⁻¹), sucrose decreased the gelation rate, presumably because sucrose increased the aqueous phase viscosity. At higher concentrations (100–300 g kg⁻¹), sucrose decreased the gelation rate, probably because sugar competes for the water of hydration and therefore increases the attraction between proteins. These data have important implications for the application of cold‐setting WPI ingredients in sweetened food products such as desserts. © 2000 Society of Chemical Industry