Three-dimensional carbon nanotube yarn based solid state solar cells with multiple sensitizers exhibit high energy conversion efficiency

Fiber-type dye sensitized solar cells that are non-metallic, flexible, and thread-like in structure have many potential military and functional textile applications. With the use of quantum dots (QD), exciton transfer facilitators (Phenyl-C61-butyric acid methyl ester-PCBM) and Poly(3-hexylthiophene-2,5-diyl-P3HT), and careful preparation of the TiO2 oxide layer deposited on the carbon fiber working electrode, an optimized efficiency of 7.6% was obtained. Carbon nanotube yarn (CNTY) was used to prepare both the working and counter electrodes of the fabricated cells. TiCl4 annealing of the TiO2 layer was carried out and the resulting oxide layer morphology was found to be very uniform. The quantum dots, cadmium sulfide (CdS) and cadmium selenide (CdSe), were deposited directly onto the surface of the nanoporous oxide layer using chemical bath deposition (CBD). Also, the P3HT and PCBM were applied and deposited via CBD on the working electrode as a bulk heterojunction material. Potentiometric characterization of the prepared cells performed at different cell lengths and showed that the maximum efficiency was obtained for cells approximately 3.5 cm in length. Photovoltaic performance of these solid state three dimensional cells was also carried out for different cell configurations

Advanced cotton fibers exhibit efficient photocatalytic self-cleaning and antimicrobial activity

Functional cotton fibers have a wide range of applications in domestic, commercial, and military settings, and so enhancing the properties of these materials can yield substantial benefits. Herein, we report the creation of functional fibers that are self-cleaning, anti-microbial, and protective against UV radiation. A uniform, and high surface area films of TiO2 were deposited on cotton fibers and gold/silver nanoparticles were directly incorporated on the nanostructured TiO2 surface. The synthetic method is simple and the produced TiO2 film is homogenous and the nanoparticles were shown to be effectively distributed on the surface using a simple photocatalytic reduction method. The Ag/Au-TiO2 coated fibers was morphologically characterized using atomic force microscopy (AFM) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), and the self-cleaning properties of noble metal nanoparticle/TiO2 coated fibers were demonstrated by repeated staining followed by exposure to simulated solar light. The 1 mM Ag-TiO2 coated fabric was observed to have the largest improvement in rate of stain extinction compared to the untreated fibers with a methylene blue stain, and the 1 mM Au-TiO2 coated fibers were observed to have the largest improvement versus untreated fibers when stained with Congo red. The fibers maintained consistent photocatalytic activity over multiple cycles, and the resistance of the Ag/Au-TiO2 coated cotton to degradation was verified using Fourier transform infrared spectroscopy (FTIR). An efficient anti-microbial activity of the fibers was confirmed by exposure of the fibers to bacterial culture (Escherichia Coli) and direct observation of antimicrobial activity

AVONET: morphological, ecological and geographical data for all birds

Functional traits offer a rich quantitative framework for developing and testing theories in evolutionary biology, ecology and ecosystem science. However, the potential of functional traits to drive theoretical advances and refine models of global change can only be fully realised when species‐level information is complete. Here we present the AVONET dataset containing comprehensive functional trait data for all birds, including six ecological variables, 11 continuous morphological traits, and information on range size and location. Raw morphological measurements are presented from 90,020 individuals of 11,009 extant bird species sampled from 181 countries. These data are also summarised as species averages in three taxonomic formats, allowing integration with a global phylogeny, geographical range maps, IUCN Red List data and the eBird citizen science database. The AVONET dataset provides the most detailed picture of continuous trait variation for any major radiation of organisms, offering a global template for testing hypotheses and exploring the evolutionary origins, structure and functioning of biodiversity

Selective Catalytic Oxidative-Dehydrogenation of Carboxylic AcidsAcrylate and Crotonate Formation at the Au/TiO₂ Interface

The oxidative-dehydrogenation of carboxylic acids to selectively produce unsaturated acids at the second and third carbons regardless of alkyl chain length was found to occur on a Au/TiO₂ catalyst. Using transmission infrared spectroscopy (IR) and density functional theory (DFT), unsaturated acrylate (H₂CCHCOO) and crotonate (CH₃CHCHCOO) were observed to form from propionic acid (H₃CCH₂COOH) and butyric acid (H₃CCH₂CH₂COOH), respectively, on a catalyst with ∼3 nm diameter Au particles on TiO₂ at 400 K. Desorption experiments also show gas phase acrylic acid is produced. Isotopically labeled ¹³C and ¹²C propionic acid experiments along with DFT calculated frequency shifts confirm the formation of acrylate and crotonate. Experiments on pure TiO₂ confirmed that the unsaturated acids were not produced on the TiO₂ support alone, providing evidence that the sites for catalytic activity are at the dual Au–Ti⁴⁺ sites at the nanometer Au particles’ perimeter. The DFT calculated energy barriers between 0.3 and 0.5 eV for the reaction pathway are consistent with the reaction occurring at 400 K on Au/TiO₂

Mechanistic Insights into the Catalytic Oxidation of Carboxylic Acids on Au/TiO₂: Partial Oxidation of Propionic and Butyric Acid to Gold Ketenylidene through Unsaturated Acids

The partial oxidation of model C₂–C₄ (acetic, propionic, and butyric) carboxylic acids on Au/TiO₂ catalysts consisting of Au particles ∼3 nm in size was investigated using transmission infrared spectroscopy and density functional theory. All three acids readily undergo oxidative dehydrogenation on Au/TiO₂. Propionic and butyric acid dehydrogenate at the C2–C3 positions, whereas acetic acid dehydrogenates at the C1–C2 position. The resulting acrylate and crotonate intermediates are subsequently oxidized to form β-keto acids that decarboxylate. All three acids form a gold ketenylidene intermediate, Au₂CCO, along the way to their full oxidation to form CO₂. Infrared measurements of Au₂CCO formation as a function of time provides a surface spectroscopic probe of the kinetics for the activation and oxidative dehydrogenation of the alkyl groups in the carboxylate intermediates that form. The reaction proceeds via the dissociative adsorption of the acid onto TiO₂, the adsorption and activation of O₂ at the dual perimeter sites on the Au particles (Au–O–O-Ti), and the subsequent activation of the C2–H and C3–H bonds of the bound propionate and butyrate intermediates by the weakly bound and basic oxygen species on Au to form acrylate and crotonate intermediates, respectively. The CC bond of the unsaturated acrylate and crotonate intermediates is readily oxidized to form an acid at the beta (C3) position, which subsequently decarboxylates. This occurs with an overall activation energy of 1.5–1.7 ± 0.2 eV, ultimately producing the Au₂CCO species for all three carboxylates. The results suggest that the decrease in the rate in moving from acetic to propionic to butyric acid is due to an increase in the free energy of activation for the formation of the Au₂CCO species on Au/TiO₂ with an increasing size of the alkyl substituent. The formation of Au₂CCO proceeds for carboxylic acids that are longer than C₂ without a deuterium kinetic isotope effect, demonstrating that C–H bond scission is not involved in the rate-determining step; the rate instead appears to be controlled by C–O bond scission. The adsorbed Au₂CCO intermediate species can be hydrogenated to produce ketene, H₂CCO­(g), with an activation energy of 0.21 ± 0.05 eV. These studies show that selective oxidative dehydrogenation of the alkyl side chains of fatty acids can be catalyzed by nanoparticle Au/TiO₂ at temperatures near 400 K

Visible Light-Induced Reactivity of Plasmonic Gold Nanoparticles Incorporated into TiO2 Matrix towards 2-Chloroethyl Ethyl Sulfide

Inexpensive strategies for efficient decontamination of hazardous chemicals are required. In this study, the effect of visible light (λ > 400 nm) on the decomposition of 2-chloroethyl ethyl sulfide (2-CEES, a sulfur mustard (HD) simulant) on Au/TiO2 photocatalyst under anaerobic and aerobic conditions has been investigated in situ by diffuse reflectance infrared Fourier –transformed spectroscopy (DRIFTS). Under anaerobic conditions, 2-CEES partially desorbs from the Au/TiO2 surface likely due to the photothermal effect, induced by photo-excited plasmonic Au nanoparticles. In the aerobic experiment, no visible light effect is observed. We attribute this behavior to 2-CEES consumption by hydrolysis to 2-ethylthio ethanol in the dark, prior to visible light excitation. Oxygen activates water molecules in the dark, resulting in accelerated 2-CEES hydrolysis

Inhibition at Perimeter Sites of Au/TiO₂ Oxidation Catalyst by Reactant Oxygen

TiO₂-supported gold nanoparticles exhibit surprising catalytic activity for oxidation reactions compared to noble bulk gold which is inactive. The catalytic activity is localized at the perimeter of the Au nanoparticles where Au atoms are atomically adjacent to the TiO₂ support. At these dual-catalytic sites an oxygen molecule is efficiently activated through chemical bonding to both Au and Ti⁴⁺ sites. A significant inhibition by a factor of 22 in the CO oxidation reaction rate is observed at 120 K when the Au is preoxidized, caused by the oxygen-induced positive charge produced on the perimeter Au atoms. Theoretical calculations indicate that induced positive charge occurs in the Au atoms which are adjacent to chemisorbed oxygen atoms, almost doubling the activation energy for CO oxidation at the dual-catalytic sites in agreement with experiments. This is an example of self-inhibition in catalysis by a reactant species

An oral alpha-galactosylceramide adjuvanted Helicobacter pylori vaccine induces protective IL-1R- and IL-17R-dependent Th1 responses

Helicobacter pylori causes chronic gastric infection that can lead to peptic ulcers and is an identified risk factor for gastric cancer development. Although much effort has been put into the development of a Helicobacter pylori vaccine over the last three decades, none has yet reached clinical application. Specific challenges pertaining to effective H. pylori vaccine development include the lack of proven vaccine-effective antigens and safe mucosal adjuvants to enhance local immune responses as well as the lack of accepted correlates of protection. Herein, we demonstrate that prophylactic intragastric immunisation with a whole-cell killed H. pylori antigen administered together with the non-toxic oral adjuvant ?-galactosylceramide (?-GalCer) induced effective immune protection against H. pylori infection in mice, which was of similar magnitude as when using the ?gold standard? cholera toxin as adjuvant. We further describe that this ?-GalCer-adjuvanted vaccine formulation elicited strong intestinal and systemic Th1 responses as well as significant antigen-specific mucosal and systemic antibody responses. Finally, we report that the protective intestinal Th1 responses induced by ?-GalCer are dependent on CD1d, IL-1R as well as IL-17R signalling. In summary, our results show that ?-GalCer is a promising adjuvant for inclusion in an oral vaccine against H. pylori infection