Engineering detonation nanodiamond - Polyaniline composites by electrochemical routes: Structural features and functional characterizations

Novel detonation nanodiamond (DND) - polyaniline (PANI) composite systems have been prepared by electrochemical polymerization techniques. Thanks to the use of two different electrochemical methods, i.e. cyclic voltammetry and chronoamperometry, it has been possible to emphasize the influence of DND particles on the nucleation mechanism of the conducting polymer. In particular, the presence of DND into the reaction environment has proven to modulate the organization of the aniline oligomers into π-stacked aggregates and to induce the production of one-dimensional nanostructures. Scanning and transmission electron microscopy was used to investigate the morphology of the final composites. The protonated conducting form of the PANI matrix has been evidenced by Raman spectroscopy and the ionic/electronic transport of the PANI-DND systems was tested by means of electrocatalysis measurements toward the iodine/iodide redox couple. Based on the present experimental data, the use of nanodiamond as filler for conducting polymer based nanocomposite represents not only a fascinating challenge for the production of advanced technological applications but it can also be exploited for the controlled growth of polymeric units and for the fabrication of tailored polymeric architectures.     

Parametric classification based on technico-economic approaches to optimize the design and manufacturing of hot forged parts

The design and manufacturing of hot forged parts, using proposed of feasibility and optimization approaches that, based on technico-economics considerations, allow to evaluate numerically the rate of adaptation of the different morphologies at the forging process, is analyzed in this work. The integration of these approaches in an unique global adaptation coefficient, carried out considering the technical and economic importance of each factor, facilitates the selection of the best alternative. Also, the use of this coefficient allows, in studies of general nature, to make quantitative classifications of the analyzed parts, in studies facilitating a hierarchical order of the different alternatives, when groups and sub-groups according to characteristic parameters of each family, are established.     

Exploring contributions of public resources in social bookmarking systems

Our study examines whether users’ contributions of public resources to social bookmarking sites are circumstantial (a side effect of bookmarking for oneself), or motivational (intentional bookmarking for others). We develop a research model based on these two explanations and test it using survey data from users of two bookmarking sites. Our results suggest that public contributions are mainly driven by intentional bookmarking of resources for other users. In addition, we found that users deliberately bookmark resources for others when they believe that their bookmarks are valuable to other users and when they perceive that other users are contributing as well.     

Preparation of a versatile precursor of novel functionalized polymers: the influence of polymerization conditions on the structure of poly [1‐(2‐hydroxyethyl)aziridine]

The cationic polymerization of 1‐(2‐hydroxyethyl)aziridine was approached by means of several catalytic systems under various conditions in order to obtain a versatile hydroxylated starting material for chemical modification reactions. Largely regular polymers were obtained using BF₃·EtNH₂ and the selected conditions. The expected head and end groups, a secondary amine and a cyclic or branched quaternary ammonium, respectively, were identified with the aid of NMR. However, in all cases we observed the participation of the primary hydroxyl group in chain transfer reactions, leading to morpholine end groups. Kinetic studies performed during the first 120 min of the reactions showed that the more active the catalytic system, the more irregular the polymer structure. The best results were obtained when polymerization was performed with 1 mol% BF₃·EtNH₂ in the absence of solvent at 45^°C, which yielded a polymerization degree of about 44 monomeric units. POLYM. ENG. SCI., 54:579–591, 2014. © 2013 Society of Plastics Engineers     

Hydrogenation reactions catalyzed by colloidal palladium nanoparticles under flow regime

A glycerol colloidal solution of palladium nanoparticles stabilized by PVP (PdPVP, mean diameter of 2.2 ± 0.8 × 10⁻⁹ m) was employed under flow conditions for hydrogenation reactions. After optimization, we selected the tube-in-tube flow reactor as the more suitable system for this catalytic process due to its ability to regulate the addition of hydrogen. PdPVP nanoparticles were synthesized and fully characterized ((HR)-TEM, PXRD, EA, and ICP) both in glycerol solution and at solid state. The reduction of different substrates, including nitrobenzene, 4-phenylbut-3-en-2-one, and isophorone, was achieved under relatively smooth conditions (5–7 × 10⁵ Pa of H₂) in short times (<600 s). Unfortunately, the reduction of 1-dodecene was not possible due to the faster isomerization reaction. The optimal effusion of hydrogen in the colloidal phase together with the catalytic efficiency of this system is noteworthy.     

Antifeedant Effects of Some Novel Terpenoids on Chrysomelidae Beetles: Comparisons with Alkaloids on an Alkaloid-Adapted and Nonadapted Species

Structure–dose–feeding deterrency relationships were compared between the Colorado potato beetle, Leptinotarsa decemlineata (Say), and the western corn rootworm, Diabrotica virgifera virgifera LeConte, using 15 alkaloids, terpenoids, and phenolic derivatives. The former species, a specialist herbivore on selected alkaloid-rich Solanaceae species, was on average 100-times less sensitive to the antifeedant effects of alkaloids, but more similarly sensitive to the terpenoids and phenolics than the latter species, a generalist flower herbivore predominantly on Graminae, Cucurbitaceae, and Compositae species. Antifeedant ED₅₀ values for the potato beetle and corn rootworm, each from closely related subfamilies of Chrysomelidae, ranged over four orders of dose magnitude among the 15 compounds with major species differences in stereosensitivity to -hydrastines and analog sensitivity with the silphinenes. Extremes in sensitivity ranged from silphinene, a rare tricyclic sesquiterpene that is 53 times more active on the potato beetle to aconitine, which is 430 times more antifeedant to the corn rootworm. Among silphinene and its two hydrolysis derivatives, there was not a strong correlation between antifeedant potency and injected toxicity for the two beetle species, but there was correlation between behavioral activity and galeal taste cell electrophysiological threshold and frequency responses. That all of the established GABA- and glycinergic compounds tested were antifeedant for both species suggests a shared molecular mechanism for antifeedant taste chemoreception in these divergent Chrysomelidae species. Moreover, the wide differences in antifeedant sensitivities among these and other chrysomelids to a suite of ligand-gated ion channel antagonists implicate a common protein neuroreceptor type with extraordinary heterogeneity in beetle taste.     

Endothelial Dysfunction Accelerates Impairment of Mitochondrial Function in Ageing Kidneys via Inflammasome Activation

Chronic kidney disease is a common problem in the elderly and is associated with increased mortality. We have reported on the role of nitric oxide, which is generated from endothelial nitric oxide synthase (eNOS), in the progression of aged kidneys. To elucidate the role of endothelial dysfunction and the lack of an eNOS-NO pathway in ageing kidneys, we conducted experiments using eNOS and ASC-deficient mice. C57B/6 J mice (wild type (WT)), eNOS knockout (eNOS KO), and ASC knockout (ASC KO) mice were used in the present study. Then, eNOS/ASC double-knockout (eNOS/ASC DKO) mice were generated by crossing eNOS KO and ASC KO mice. These mice were sacrificed at 17−19 months old. The Masson positive area and the KIM-1 positive area tended to increase in eNOS KO mice, compared with WT mice, but not eNOS/ASC DKO mice. The COX-positive area was significantly reduced in eNOS KO mice, compared with WT and eNOS/ASC DKO mice. To determine whether inflammasomes were activated in infiltrating macrophages, the double staining of IL-18 and F4/80 was performed. IL-18 and F4/80 were found to be co-localised in the tubulointerstitial areas. Inflammasomes play a pivotal role in inflammaging in ageing kidneys. Furthermore, inflammasome activation may accelerate cellular senescence via mitochondrial dysfunction. The importance of endothelial function as a regulatory mechanism suggests that protection of endothelial function may be a potential therapeutic target.