Deformation Phenomena of Thermoplastic Materials in the Solid and Semifluid States

The deformation phenomena of a thermoplastic elastomer, a polyamide 12 and a polyketone, are analyzed to identify the polymer characteristics that enhance the processability of a material both at temperatures around the melting point (i.e., in a semifluid state) and at temperatures close to ambient conditions. Dissipation factor isotherms in the frequency range associated with hot compaction, used in conjunction with a hot-pressing technique that identifies the minimum temperature required for significant chain mobility during hot compaction, allow to evaluate the processability in the semifluid state. The experiments show that optimal processing by hot compaction is achieved when tan δ > 2 for the entire frequency range under consideration. Showing superior processability with respect to the other two polymers, the polyamide 12 is then compounded with a polyamide 12-based elastomer to tune its stiffness and toughness in tension and bending, enhancing its cold forming characteristics. POLYM. ENG. SCI., 60:535–540, 2020. © 2019 Society of Plastics Engineers     

Scouting around 1,2,3,4-Tetrahydrochromeno[3,2-c]pyridin-10-ones for Single- and Multitarget Ligands Directed towards Relevant Alzheimer's Targets

A number of 1,2,3,4-tetrahydrochromeno[3,2-c]pyridin-10-one derivatives have been synthesized and screened against different targets involved in the onset and progression of Alzheimer's disease (AD), such as acetyl- and butyrylcholinesterase (AChE and BChE), monoamine oxidases A and B (MAO A and B), aggregation of β-amyloid (Aβ) and reactive oxygen species (ROS) production. Derivatives 1 c , 3 b , 4 and 5 a showed multifaceted profiles of promising anti-AD features and returned well-balanced multitargeting inhibitory activities. Moreover, compound 1 f , a potent and selective human MAO B inhibitor (IC₅₀=0.89 μM), proved to be a safe neuroprotectant in a human neuroblastoma cell line (SH-SY5Y) by improving viability impaired by Aβ_1–42 and pro-oxidant insult. Furthermore, structure–activity relationships (SARs) and docking models were derived in order to assist further hit-to-lead optimization stage.     

Preparation,characterization, and antimicrobial activity of ferrocene-containing polymeric materials

Ferrocenyl(benzyl) imidazole (FcIm) and two related methyl-imidazolium salts (FcMIm⁺I^– and FcMIm⁺PF₆^–) were synthesized for their incorporation into plasticized PVC by solvent casting technique. The obtained materials were investigated for their thermal stability and, compared to pure polymer, films containing ionic ferrocene derivatives in 0.5% w/w loading were found slightly more stable. The pure ferrocene compounds showed antibacterial activity against Staphylococcus epidermis, but not against Escherichia coli, with a maximum for FcMIm⁺PF₆^– salt. After incorporation into PVC polymer, antibacterial activity against S. epidermis was observed (by disk diffusion test) only for PVC/FcMIm⁺PF₆^– (5% w/w) film, from which a release of 14.6% of the ferrocenilimidazolium cation in aqueous medium was measured after 24 hr.     

Deletion of Trpm4 Alters the Function of the Nav1.5 Channel in Murine Cardiac Myocytes

Transient receptor potential melastatin member 4 (TRPM4) encodes a Ca²⁺-activated, non-selective cation channel that is functionally expressed in several tissues, including the heart. Pathogenic mutants in TRPM4 have been reported in patients with inherited cardiac diseases, including conduction blockage and Brugada syndrome. Heterologous expression of mutant channels in cell lines indicates that these mutations can lead to an increase or decrease in TRPM4 expression and function at the cell surface. While the expression and clinical variant studies further stress the importance of TRPM4 in cardiac function, the cardiac electrophysiological phenotypes in Trpm4 knockdown mouse models remain incompletely characterized. To study the functional consequences of Trpm4 deletion on cardiac electrical activity in mice, we performed perforated-patch clamp and immunoblotting studies on isolated atrial and ventricular cardiac myocytes and surfaces, as well as on pseudo- and intracardiac ECGs, either in vivo or in Langendorff-perfused explanted mouse hearts. We observed that TRPM4 is expressed in atrial and ventricular cardiac myocytes and that deletion of Trpm4 unexpectedly reduces the peak Na⁺ currents in myocytes. Hearts from Trpm4^−/− mice presented increased sensitivity towards mexiletine, a Na⁺ channel blocker, and slower intraventricular conduction, consistent with the reduction of the peak Na⁺ current observed in the isolated cardiac myocytes. This study suggests that TRPM4 expression impacts the Na⁺ current in murine cardiac myocytes and points towards a novel function of TRPM4 regulating the Na_v1.5 function in murine cardiac myocytes.     

Chemical,thermal and structural properties of alkaline-cooked (nixtamalised) chickpea (Cicer arietinum) flours

The present study examined how the alkaline cooking process affects the chemical, thermal and structural properties of the chickpea, evaluating different lime concentrations. Cooking was carried out at 94 °C, with two times of water for 15 min with five different lime concentrations. Regarding chemical composition, a decrease in protein and fat was observed: from 23.64% to a range of 18.26–19.93% for protein and from 8.20% to a range of 6.05–7.74% for fat. However, an increase was observed for ash and mineral content. The same pattern was observed for potassium. Raw chickpea did not present endotherm retrogradation, but a higher endotherm retrogradation was presented in chickpea cooked without lime, denoting that nixtamalisation decreased retrogradation. Additionally, V-amylose relative crystallinity increased with concentration of lime. Protein digestibility increases by β-sheet dismissing structure. Finally, it was observed that steeping time plays a key role in the nixtamalisation process.     

PLLA–silver nanoparticles bionanocomposite membranes: Preparation,antibacterial activity,and in vitro hydrolytic degradation assessment

Silver nanoparticles (AgNp) were synthesized in aqueous phase and transferred to chloroform using a fatty amine as phase transfer agent. Poly(l -lactic acid) (PLLA) membranes were prepared using the “functionalized” chloroform. The amount of AgNp in the chloroform was determined by atomic absorption spectroscopy. Thermogravimetric analysis, differential scanning calorimetry, and field emission scanning electron microscopy were used to characterize the membranes. A decrease of the thermal stability of the membranes was observed upon the addition of AgNp; meanwhile, the polymer crystallinity degree increased, making the membranes more fragile and brittle. The in vitro degradation assessments of the membranes in artificial saliva suggested that the time necessary to degrade the PLLA reduced by raising the concentration of the nanostructures. Additionally, the antibacterial assays demonstrated that the addition of only 13 ppm of AgNp were enough to inhibit the formation of biofilm over the bionanocomposite membranes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47998.     

Technical note: A novel approach to estimate dry matter intake of lactating dairy cows through multiple on-cow accelerometers

The objective of this study was to evaluate the feasibility of using multiple 3-dimensional accelerometers to estimated individual dry matter intake (DMI) of lactating dairy cows. Twenty-four Holstein cows in late lactation were assigned into 2 groups, a calibration group (n = 12) and a validation group (n = 12). All cows were fitted with 3 sensors that recorded 3-dimensional acceleration (i.e., x, y, and z) at 10-s intervals, 1 on the lateral side of the left hind leg and 2 attached directly to a halter over the nose and jaw area on the left side. Then, 3 accelerations were generated from each accelerometer (e.g., Leg-X, Leg-Y, and Leg-Z). Six new variables were created based on the change in acceleration in the nose and jaw accelerometers between 2 consecutive time points (e.g., LagJaw-X). For both groups (i.e., calibration and validation), cows were continuously video recorded while data on acceleration and intake of total mixed ration were collected for 10 consecutive days. Cows were fed once daily using an individual gate system, and individual refusals were recorded next day before morning feeding. Cows were fed a common lactating cow diet (17.9% crude protein; 1.70 Mcal/kg of dry matter). In the calibration group, individual eating bouts were obtained based on video recordings and merged with the corresponding accelerometer data. Then, a stepwise regression analysis was conducted using the REG procedure of SAS (SAS Institute, Cary, NC) to determine the ranges in acceleration that accounted for the highest variation in DMI (highest R²) in each acceleration variable. All 32,767 potential acceleration combinations were tested in the validation group using the acceleration ranges predetermined in the calibration group. The CORR procedure of SAS was used to test the Pearson correlation coefficient (r) between the type of DMI [i.e., based on accelerations (DMI_accel) or actual DMI (DMI_actual)]. The MIXED procedure of SAS was used to perform a repeated-measures analysis with type (DMI_accel vs. DMI_actual), day, and their interaction (T × D) in the model. From this analysis, 8 candidate acceleration models were selected based on high r and similarity (P > 0.15) in terms of T and T × D between DMI_accel and DMI_actual. A simulated effect on DMI_actual was artificially created in the validation group by dividing this group (n = 12) into high and low intake cows (n = 6/group; DMI of 24.1 vs. 18.7 kg/d), and the candidate models were tested to determine whether they were sensitive enough to detect this effect. From these candidate models, AEN (Leg-X + Jaw-Z + LagJaw-Z) showed a weak correlation (r = 0.36) between DMI_accel and DMI_actual, but DMI_accel and DMI_actual were highly similar (21.2 vs. 21.4 kg/d of DMI). In addition, this was the only model that could detect the simulated effect on DMI_actual (22.1 vs. 20.3 kg/d of DMI) in the validation group. The fact that the simulated effect on DMI_actual was detected based only on accelerations is highly significant, and models such as AEN could be substantially improved if they were derived from a greater sample size and included different physiological stages in dairy cows.