Porosity-moderated ultrafast electron transport in Au nanowire networks

We demonstrate for first time the ultrafast properties of a newly formed porous Au nanostructure. The properties of the porous nanostructure are compared with those of a solid gold film using time-resolved optical spectroscopy.The experiments suggest that under the same excitation conditions the relaxation dynamics are slower in the former. Our observations are evaluated by simulations based on a phenomenological rate equation model. The impeded dynamics has been attributed to the porous nature of the structure in the networks, which results in reduced efficiency during the dissipation of the laser-deposited energy. Importantly,the porosity of the complex three-dimensional nanostructure is introduced as a geometrical control parameter of its ultrafast electron transport

Zato što je političko znanje bitno: utjecaj deliberacije na mišljenje mladih građana

This paper addresses the importance of “knowledge” and “access to information” in the formation of young citizens’ opinion through deliberative procedures. The research presented in this paper is grounded in the theoretical framework of deliberative democracy as a democratic model and procedure that allows participants to be engaged in a rational and open dialogue before deciding on a particular issue. Our research draws empirically upon a deliberative event that took place in October 2014 at the Western Macedonia University of Applied Sciences in Greece. The topic of deliberation was “Political Public Opinion Polls.” The results of this study are commensurate with the dominant thesis in the relevant literature, which underlines that the deliberative procedure enriches the knowledge of citizens and thus enables them to participate effectively in the decision making process.Ovaj rad bavi se važnošću „znanja“ i „pristupa informacijama“ u formiranju mišljenja mladih građana o pojedinim temama kroz deliberativne procedure. Deliberativna demokracija, kao demokratski model i demokratska procedura koja dopušta sudionicima uključivanje u racionalan i otvoren dijalog prije odlučivanja o određenoj temi, teorijski je okvir na kojem se temelji istraživanje predstavljeno u ovom radu. Empirijski dio našeg rada temelji se na deliberativnom događaju koji se odvio u listopadu 2014. na instituciji za visoko obrazovanje Western Macedonia University of Applied Sciences u Grčkoj. Tema deliberacije bila je „Anketna istraživanja javnog mnijenja o politici“. Rezultati ovog istraživanja potvrđuju tezu iz relevantne literature koja naglašava kako deliberativne procedure obogaćuju znanje građana i tako im omogućavaju da učinkovito sudjeluju u procesu donošenja odluka

Nanocomposite pattern-mediated magnetic interactions for localized deposition of nanomaterials.

We present a method to create, align, and locate magnetic wires throughout and on the surface of patterned polymer matrices, following the magnetophoretic transport and self-assembly of ferromagnetic nanoparticles under a static magnetic field during laser photopolymerization of monomer/nanoparticle casted solutions. The resulting films have the ability to attract and immobilize small quantities of magnetic nanomaterials locally on the ferromagnetic wires, as proved by a detailed topography study. Magnetic studies on the films before and after the spontaneous deposition, demonstrate that the deposited nanomaterials alter significantly the magnetic character of the system, making thus possible their macroscopic identification. This offers the possibility to realize sensing devices based on hybrid materials with magnetic properties

Influence of magnetic interaction between impurity and impurity-liberated spins on the magnetism in the doped Haldane chain compounds PbNi{}_{2-x{A}x{}_{x}V2{}_{2}O8{}_{8} (A = Mg, Co)

A comprehensive study of impurity-induced magnetism in nonmagnetically (Mg${}^{2+}$) and magnetically (Co${}^{2+}$) doped PbNi${}_{2}$V${}_{2}$O${}_{8}$ compounds is given, using both macroscopic dc susceptibility and local-probe electron spin resonance (ESR) techniques. Magnetic coupling between impurity-liberated spins is estimated from a linewidth of low-temperature ESR signal in Mg-doped samples. In addition, in the case of magnetic cobalt dopants the impurity-host magnetic exchange is evaluated from the Co-induced contribution to the linewidth in the paramagnetic phase. The experimentally observed severe broadening of the ESR lines in the magnetically doped compounds with respect to nonmagnetic doping is attributed to a rapid spin-lattice relaxation of the Co${}^{2+}$ ions, which results in a bottleneck-type of temperature dependence of the induced linewidth. The exchange parameters obtained from the ESR analysis offer a satisfactory explanation of the observed low-temperature magnetization in doped samples.Comment: 8 pages, 6 figure

Heat-Up Colloidal Synthesis of Shape-Controlled Cu-Se-S Nanostructures-Role of Precursor and Surfactant Reactivity and Performance in N Electroreduction

Copper selenide-sulfide nanostructures were synthesized using metal-organic chemical routes in the presence of Cu- and Se-precursors as well as S-containing compounds. Our goal was first to examine if the initial Cu/Se 1:1 molar proportion in the starting reagents would always lead to equiatomic composition in the final product, depending on other synthesis parameters which affect the reagents reactivity. Such reaction conditions were the types of precursors, surfactants and other reagents, as well as the synthesis temperature. The use of 'hot-injection' processes was avoided, focusing on 'non-injection' ones; that is, only heat-up protocols were employed, which have the advantage of simple operation and scalability. All reagents were mixed at room temperature followed by further heating to a selected high temperature. It was found that for samples with particles of bigger size and anisotropic shape the CuSe composition was favored, whereas particles with smaller size and spherical shape possessed a CuSe phase, especially when no sulfur was present. Apart from elemental Se, AlSe was used as an efficient selenium source for the first time for the acquisition of copper selenide nanostructures. The use of dodecanethiol in the presence of trioctylphosphine and elemental Se promoted the incorporation of sulfur in the materials crystal lattice, leading to Cu-Se-S compositions. A variety of techniques were used to characterize the formed nanomaterials such as XRD, TEM, HRTEM, STEM-EDX, AFM and UV-Vis-NIR. Promising results, especially for thin anisotropic nanoplates for use as electrocatalysts in nitrogen reduction reaction (NRR), were obtained

Hydration-induced spin-glass state in a frustrated Na-Mn-O triangular lattice

Birnessite compounds are stable across a wide range of compositions that produces a remarkable diversity in their physical, electrochemical, and functional properties. These are hydrated analogs of the magnetically frustrated, mixed-valent manganese oxide structures, with general formula, NaxMnO2. Here we demonstrate that the direct hydration of layered rock-salt type ?-NaMnO2, with the geometrically frustrated triangular lattice topology, yields the birnessite type oxide, Na0.36MnO2?0.2H2O, transforming its magnetic properties. This compound has a much-expanded interlayer spacing compared to its parent ?-NaMnO2 compound. We show that while the parent ?-NaMnO2 possesses a Néel temperature of 45 K as a result of broken symmetry in the Mn3+ sublattice, the hydrated derivative undergoes collective spin freezing at 29 K within the Mn3+/Mn4+ sublattice. Scaling-law analysis of the frequency dispersion of the ac susceptibility, as well as the temperature-dependent, low-field dc magnetization confirm a cooperative spin-glass state of strongly interacting spins. This is supported by complementary spectroscopic analysis [high-angle annular dark-field scanning transmission electron miscroscopy (TEM), energy-dispersive x-ray spectroscopy, and electron energy-loss spectroscopy] as well as by a structural investigation (high-resolution TEM, x-ray, and neutron powder diffraction) that yield insights into the chemical and atomic structure modifications. We conclude that the spin-glass state in birnessite is driven by the spin frustration imposed by the underlying triangular lattice topology that is further enhanced by the in-plane bond-disorder generated by the mixed-valent character of manganese in the layers