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The resistance of an ordered 3D-Bi 2 Te 3 nanowire nanonetwork was studied at low temperatures. Below 50 K the increase in resistance was found to be compatible with the Anderson model for localization, considering that conduction takes place in individual parallel channels across the whole sample. Angle-dependent magnetoresistance measurements showed a distinctive weak antilocalization characteristic with a double feature that we could associate with transport along two perpendicular directions, dictated by the spatial arrangement of the nanowires. The coherence length obtained from the Hikami-Larkin-Nagaoka model was about 700 nm across transversal nanowires, which corresponded to approximately 10 nanowire junctions. Along the individual nanowires, the coherence length was greatly reduced to about 100 nm. The observed localization effects could be the reason for the enhancement of the Seebeck coefficient observed in the 3D-Bi 2 Te 3 nanowire nanonetwork compared to individual nanowires.

Metal single-atom catalysts (SACs) promise great rewards in terms of metal atom efficiency. However, the requirement of particular conditions and supports for their synthesis, together with the need of solvents and additives for catalytic implementation, often precludes their use under industrially viable conditions. Here, we show that palladium single atoms are spontaneously formed after dissolving tiny amounts of palladium salts in neat benzyl alcohols, to catalyze their direct aerobic oxidation to benzoic acids without ligands, additives, or solvents. With this result in hand, the gram-scale preparation and stabilization of Pd SACs within the functional channels of a novel methyl-cysteine-based metal-organic framework (MOF) was accomplished, to give a robust and crystalline solid catalyst fully characterized with the help of single-crystal X-ray diffraction (SCXRD). These results illustrate the advantages of metal speciation in ligand-free homogeneous organic reactions and the translation into solid catalysts for potential industrial implementation.

Agrochemical encapsulation agents used up to now are commonly based on polymeric compounds or metal particles, but the employment of other natural products such as host structures has not been tackled in detail. In the work reported here, fully organic nanotubes composed of human bile acid (lithocholic acid) have been synthesized. These nanotubes were employed to encapsulate potential disulfide herbicide mimics that have previously shown relevant inhibitory activity against weeds. The three-dimensional chemical information from scanning transmission electron microscope analytical tomography with subnanometer scale resolution convincingly demonstrates for the first time the occurrence of efficient encapsulation within a fully organic nanotube of different organic molecules with activity as herbicides. The encapsulation was achieved in a one-pot synthesis, in an aqueous environment and under in situ conditions without using any marker or coating with contrast materials, which renders the process greener than those routinely used. The nanotubes allow complete water solubilization, with an encapsulation percentage of up to 78% in all of the herbicide compounds. Furthermore, nanotubes showed a flattened arrangement due to the host-guest interaction. The synthetic approach represents a step forward in solving the key problem of the quite limited solubility of natural agrochemicals in aqueous environments. In addition, the process presents a breakthrough in the use of natural products produced by the human body as encapsulating agents, which expands possible future applications. The preliminary docking approach clarifies that the 2o01 transmembrane transport protein seems to be the prior channel of the organic nanotube in the delivery process to vegetable cells. The etiolated wheat coleoptile bioassay demonstrated that the encapsulated herbicides have improved the bioactivity of free compounds, keeping 60% of inhibition of the weed at least for every disulfide, a requisite for their fruitful application as agrochemicals.

Ferritin, a soluble and highly robust protein with subunits packed into well-defined helices, is a key component of the iron regulatory system in the brain and thus is widely recognized as a crucial protein for iron metabolism, but may also bear possible implications in some neurodegenerative disorders. Here, we present evidence of how human recombinant apoferritin can convert into an unusual structure from its folded native state; that is, amyloid fibrils analogue to those found in pathological disorders such as Alzheimer's and Parkinson's diseases. An extensive combination of advanced microscopy, spectroscopy and scattering techniques concur to reveal that apoferritin fibrils possess a common double stranded twisted ribbon structure which can result in a mesoscopic right-handed chirality. We highlight a direct connection between the chirality and morphology of the resulting amyloid fibrils, and the initial protein subunits composition, advancing our understanding on the possible role of misfolding in some ferritin-related pathologies and posing new bases for the design of chiral 1D functional nanostructures.

Nanoencapsulation has proven to be an efficient route to increase significantly the solubility and bioavailability of organic compounds. This aspect of nanotechnology is illustrated for the case of phthalimide-lactone (PL), a recently synthesized strigolactone mimic whose very limited solubility in water, as a free chemical, precludes its practical use as an agrochemical in the fight against parasitic plants. Pluronic F-127 (P127) nanoparticles functionalized with PL have been synthesized and embedded in a polymeric matrix of poly(vinyl alcohol) (PVA). Low-voltage and medium voltage imaging and spectroscopic scanning electron microscopy (S(T)EM) techniques were combined to confirm the synthesis of multicore nanoparticles that were rich in nitrogen, a finding that is due to the successful encapsulation of PL. This PL@P127/PVA nanobiostimulator formulation has an impressive solubility in water, that is, 27 times higher than that of pure phthalimide-lactone. Also critical from the functional point of view, comparative bioassays clearly showed that the intrinsic stimulatory activity of this agrochemical is fully maintained in the nanoencapsulated formulation.

Using a method that combines experimental and simulated Aberration-Corrected High Resolution Electron Microscopy images with digital image processing and structure modeling, strain distribution maps within gold nanoparticles relevant to real powder type catalysts, i.e., smaller than 3 nm, and supported on a ceria-based mixed oxide have been determined. The influence of the reduction state of the support and particle size has been examined. In this respect, it has been proven that reduction even at low temperatures induces a much larger compressive strain on the first {111} planes at the interface. This increase in compression fully explains, in accordance with previous DFT calculations, the loss of CO adsorption capacity of the interface area previously reported for Au supported on ceria-based oxides.

A variety of advanced (scanning) transmission electron microscopy experiments, carried out in aberration-corrected equipment, provide direct evidence about subtle structural changes taking place at nanometer-sized Au||ceria oxide interfaces, which agrees with the occurrence of charge transfer effects between the reduced support and supported gold nanoparticles suggested by macroscopic techniques. Tighter binding of the gold nanoparticles onto the ceria oxide support when this is reduced is revealed by the structural analysis. This structural modification is accompanied by parallel deactivation of the CO chemisorption capacity of the gold nanoparticles, which is interpreted in exact quantitative terms as due to deactivation of the gold atoms at the perimeter of the Au||cerium oxide interface.

Bimetallic CoNi nanoparticles have been prepared within the apoferritin cavity. The protein shell controls size, prevents aggregation, and makes nanoparticles water-soluble. The CoNi series prepared in this way were structurally and magnetically characterized, the resulting magnetic properties varying accordingly with composition (Co(75)/Ni(25), Co(50)/Ni(50), Co(25)/Ni(75)). Co and Ni metals were associated in each nanoparticle, as demonstrated by high-angle annular dark field scanning electron microscopy and electron energy loss spectroscopy (EELS). After intentional oxidation, the CoNi nanoparticles were characterized by EELS, X-ray absorption near edge structure (XANES), and SQUID measurements to evaluate the importance of the oxidation on magnetic properties.

CeO(2) nanotubes have been grown electrochemically using a porous alumina membrane as a template. The resulting material has been characterized by means of scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy, high-angle annular dark-field scanning transmission electron microscopy tomography, high-resolution electron microscopy (HREM), and electron energy loss spectroscopy. According to SEM, the outer diameter of the nanotubes corresponds to the pore size (200 nm) of the alumina membrane, and their length ranges between 30 and 40 microm. HREM images have revealed that the width of the nanotube walls is about 6 nm. The catalytic activity of these novel materials for the CO oxidation reaction is compared to that of a polycrystalline powder CeO(2) sample prepared by a conventional route. The activity of the CeO(2) nanotubes is shown to be in the order of 400 times higher per gram of oxide at 200 degrees C (77.2 x 10(-2) cm(3) CO(2) (STP)/(gxs) for the nanotube-shaped CeO(2) and 0.16 x 10(-2) cm(3) CO(2) (STP)/(gxs) for the powder CeO(2)).

Transmission Electron Microscopy (TEM), X-ray Absorption Near Edge Spectroscopy (XANES), Electron Energy-Loss Spectroscopy (EELS), Small-Angle X-ray Scattering (SAXS), and SQUID magnetic studies were performed in a batch of horse spleen ferritins from which iron had been gradually removed, yielding samples containing 2200, 1200, 500, and 200 iron atoms. Taken together, findings obtained demonstrate that the ferritin iron core consists of a polyphasic structure (ferrihydrite, magnetite, hematite) and that the proportion of phases is modified by iron removal. Thus, the relative amount of magnetite in ferritin containing 2200 to 200 iron atoms rose steadily from approximately 20% to approximately 70% whereas the percentage of ferrihydrite fell from approximately 60% to approximately 20%. These results indicate a ferrihydrite-magnetite core-shell structure. It was also found that the magnetite in the ferritin iron core is not a source of free toxic ferrous iron, as previously believed. Therefore, the presence of magnetite in the ferritin cores of patients with Alzheimer's disease is not a cause of their increased brain iron(II) concentration.