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https://www.readbyqxmd.com/read/28230297/spectroscopic-observation-of-a-hydrogenated-co-dimer-intermediate-during-co-reduction-on-cu-100-electrodes
#1
Elena Pérez-Gallent, Marta C Figueiredo, Federico Calle-Vallejo, Marc T M Koper
Carbon dioxide and carbon monoxide can be electrochemically reduced to useful products such as ethylene and ethanol on copper electrocatalysts. The process is yet to be optimized and the exact mechanism and the corresponding reaction intermediates are under debate or unknown. In particular, it has been hypothesized that the C-C bond formation proceeds via CO dimerization and further hydrogenation. Although computational support for this hypothesis exists, direct experimental evidence has been elusive. In this work, we detect a hydrogenated dimer intermediate (OCCOH) using Fourier transform infrared spectroscopy at low overpotentials in LiOH solutions...
February 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28225072/copper-treatment-during-storage-reduces-phytophthora-and-halophytophthora-infection-of-zostera-marina-seeds-used-for-restoration
#2
Laura L Govers, Els M van der Zee, Johan P Meffert, Patricia C J van Rijswick, Willem A Man In 't Veld, Jannes H T Heusinkveld, Tjisse van der Heide
Restoration is increasingly considered an essential tool to halt and reverse the rapid decline of vital coastal ecosystems dominated by habitat-forming foundation species such as seagrasses. However, two recently discovered pathogens of marine plants, Phytophthora gemini and Halophytophthora sp. Zostera, can seriously hamper restoration efforts by dramatically reducing seed germination. Here, we report on a novel method that strongly reduces Phytophthora and Halophytophthora infection of eelgrass (Zostera marina) seeds...
February 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28218001/preventing-alkyne-alkyne-i-e-glaser-coupling-associated-with-the-atrp-synthesis-of-alkyne-functional-polymers-macromonomers-and-for-alkynes-under-click-i-e-cuaac-reaction-conditions
#3
Porakrit Leophairatana, Sanjoy Samanta, Chathuranga C De Silva, Jeffrey T Koberstein
Alkyne-functional polymers synthesized by ATRP exhibit bimodal molecular weight distributions indicating the occurrence of some undesirable side reaction. By modeling the molecular weight distributions obtained under various reaction condi-tions, we show that the side reaction is alkyne-alkyne (i.e., Glaser) coupling. Glaser coupling accounts for as much as 20 per cent of the polymer produced, significantly compromising the polymer functionality and undermining the success of subse-quent click reactions in which they are used...
February 20, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28212817/in-vivo-toxicity-of-copper-oxide-lead-oxide-and-zinc-oxide-nanoparticles-acting-in-different-combinations-and-its-attenuation-with-a-complex-of-innocuous-bio-protectors
#4
Ilzira A Minigalieva, Boris A Katsnelson, Vladimir G Panov, Larisa I Privalova, Anatoly N Varaksin, Vladimir B Gurvich, Marina P Sutunkova, Vladimir Ya Shur, Ekaterina V Shishkina, Irene E Valamina, Ilya V Zubarev, Oleg H Makeyev, Ekaterina Y Meshtcheryakova, Svetlana V Klinova
Stable suspensions of metal oxide nanoparticles (Me-NPs) obtained by laser ablation of 99.99% pure copper, zinc or lead under a layer of deionized water were used separately, in three binary combinations and a triple combination in two independent experiments on rats. In one of the experiments the rats were instilled with Me-NPs intratracheally (i.t.) (for performing a broncho-alveolar lavage in 24hrs to estimate the cytological and biochemical indices of the response of the lower airways), while in the other, Me-NPs were repeatedly injected intraperitoneally (i...
February 14, 2017: Toxicology
https://www.readbyqxmd.com/read/28206675/a-multi-zoo-investigation-of-nutrient-provision-for-captive-red-crested-turacos
#5
Alexander J Hulbert, Kerry A Hunt, Paul E Rose
Turacos (Musophagidae) are common zoo birds; the 14 species of Tauraco being most often exhibited. Turacos possess unique non-structural, copper-based feather pigments, and a specialized dietary strategy. Tauraco inhabit tropical woodlands, foraging for predominantly folivorous and/or frugivorous food items. Using a study population of 16 red-crested turacos (T. erythrolophus) at seven zoos in the United Kingdom, the nutrient composition of diets from diet sheets was calculated, using Zootrition v.2.6, Saint Louis Zoo, USA for analyses of important nutrients within each diet, and compared against an example of currently available literature...
February 16, 2017: Zoo Biology
https://www.readbyqxmd.com/read/28195739/substrate-and-lewis-acid-coordination-promote-o-o-bond-cleavage-of-an-unreactive-l2cu-ii-2-o2-2-species-to-form-l2cu-iii-2-o-2-cores-with-enhanced-oxidative-reactivity
#6
Isaac Garcia-Bosch, Ryan E Cowley, Daniel E Díaz, Ryan L Peterson, Edward I Solomon, Kenneth D Karlin
Copper-dependent metalloenzymes are widespread throughout metabolic pathways, coupling the reduction of O2 with the oxidation of organic substrates. Small-molecule synthetic analogs are useful platforms to generate L/Cu/O2 species that reproduce the structural, spectroscopic, and reactive properties of some copper-/O2-dependent enzymes. Landmark studies have shown that the conversion between dicopper(II)-peroxo species (L2Cu(II)2(O2(2-)) either side-on peroxo, (S)P, or end-on trans-peroxo, (T)P) and dicopper(III)-bis(μ-oxo) (L2Cu(III)2(O(2-))2: O) can be controlled through ligand design, reaction conditions (temperature, solvent, and counteranion), or substrate coordination...
February 14, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28195736/oxidative-fragmentations-and-skeletal-rearrangements-of-oxindole-derivatives
#7
Hendrik F T Klare, Alexander F G Goldberg, Douglas C Duquette, Brian M Stoltz
An oxidative sequence for the conversion of oxindoles to structurally distinct heterocyclic scaffolds and aniline derivatives is disclosed by the combination of a copper-catalyzed C-H peroxidation and subsequent base-mediated fragmentation reaction. In contrast to classic enzymatic (i.e., kynurenine pathway) and biomimetic methods (i.e., Witkop-Winterfeldt oxidation) for oxidative indole cleavage, this protocol allows for the incorporation of external nucleophiles. The new transformation displays broad functional group tolerance and is applicable to tryptophan derivatives, opening potential new avenues for postsynthetic modification of polypeptides, bioconjugation, and unnatural amino acid synthesis...
February 14, 2017: Organic Letters
https://www.readbyqxmd.com/read/28191822/corrosion-resistance-of-monolayer-hexagonal-boron-nitride-on-copper
#8
F Mahvash, S Eissa, T Bordjiba, A C Tavares, T Szkopek, M Siaj
Hexagonal boron nitride (hBN) is a layered material with high thermal and chemical stability ideal for ultrathin corrosion resistant coatings. Here, we report the corrosion resistance of Cu with hBN grown by chemical vapor deposition (CVD). Cyclic voltammetry measurements reveal that hBN layers inhibit Cu corrosion and oxygen reduction. We find that CVD grown hBN reduces the Cu corrosion rate by one order of magnitude compared to bare Cu, suggesting that this ultrathin layer can be employed as an atomically thin corrosion-inhibition coating...
February 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28178840/surface-chemistry-of-group-11-atomic-layer-deposition-precursors-on-silica-using-solid-state-nuclear-magnetic-resonance-spectroscopy
#9
Peter J Pallister, Seán T Barry
The use of chemical vapour deposition (CVD) and atomic layer deposition (ALD) as thin film deposition techniques has had a major impact on a number of fields. The deposition of pure, uniform, conformal thin films requires very specific vapour-solid reactivity that is largely unknown for the majority of ALD and CVD precursors. This work examines the initial chemisorption of several thin film vapour deposition precursors on high surface area silica (HSAS) using (13)C, (31)P, and quantitative (29)Si nuclear magnetic resonance spectroscopy (NMR)...
February 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28178813/effect-of-the-nature-of-the-substrate-on-the-surface-chemistry-of-atomic-layer-deposition-precursors
#10
Yunxi Yao, Jason P Coyle, Seán T Barry, Francisco Zaera
The thermal chemistry of Cu(I)-sec-butyl-2-iminopyrrolidinate, a promising copper amidinate complex for atomic layer deposition (ALD) applications, was explored comparatively on several surfaces by using a combination of surface-sensitive techniques, specifically temperature-programmed desorption and x-ray photoelectron spectroscopy (XPS). The substrates explored include single crystals of transition metals (Ni(110) and Cu(110)), thin oxide films (NiO/Ni(110) and SiO2/Ta), and oxygen-treated metals (O/Cu(110))...
February 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28176762/systemic-serum-amyloid-a-as-a-biomarker-for-exposure-to-zinc-and-or-copper-containing-metal-fumes
#11
R Baumann, M Gube, A Markert, S Davatgarbenam, V Kossack, B Gerhards, T Kraus, P Brand
Zinc- and copper-containing welding fumes increase systemic C-reactive protein (CRP). The aim of this study was to investigate the performance of the biomarkers serum amyloid A (SAA) and soluble vascular cell adhesion molecule-1 (VCAM-1) in this regard. Fifteen male subjects were exposed under controlled conditions to welding fumes containing either zinc, or copper, or copper and zinc for 6 h. Plasma samples were collected before, 6 and 24 h after start of exposure and biomarkers therein were measured by electrochemiluminescent assay...
February 8, 2017: Journal of Exposure Science & Environmental Epidemiology
https://www.readbyqxmd.com/read/28174087/adsorption-and-kinetic-studies-on-the-removal-of-chromium-and-copper-onto-chitosan-g-maliec-anhydride-g-ethylene-dimethacrylate
#12
M R Gopal Reddi, T Gomathi, M Saranya, P N Sudha
The present work was designed to remove toxic metals chromium and copper using the double grafted copolymer Chitosan-g-Maleic anhydride-g-ethylene dimethacrylate. The graft copolymer was synthesized through chain polymerization reaction using ceric ammonium nitrate as the initiator. Prepared Chitosan-g-Maleic anhydride-g-ethylene dimethacrylate was used in order to remove the heavy metals chromium and copper from aqueous solutions of 200ppm/L concentration proceeding batch adsorption process by varying the parameters such as adsorbent dose, contact time, pH and initial concentration of the metal solution...
February 4, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28159235/commercial-gold-nanocolloid-inhibits-synthesis-of-il-2-and-proliferation-of-porcine-t-lymphocytes
#13
Joanna Małaczewska, Roman Wójcik, Edyta Kaczorek, Wojciech Rękawek, Andrzej Krzysztof Siwicki
Recent intensive development of nanotechnology has broadened the use of noble metal nanocolloids in alternative medicine. Meanwhile, silver and copper nanoparticles are tested as potential feed additives in pig farming. Experiments on rodents prove that metal nanocolloids easily interact with macrophages and lymphocytes, although the specific nature of pigs' immune system means that rodent tests may not reflect fully the responsiveness of porcine T cells. Our purpose was to demonstrate the effect of a commercial gold nanocolloid on percentages and proliferation of T lymphocyte subpopulations and on IL-2 and IL-10 synthesis in porcine peripheral blood mononuclear cells tested in vitro...
February 2017: Research in Veterinary Science
https://www.readbyqxmd.com/read/28154851/sterically-directed-nitronate-complexes-of-2-6-di-tert-butyl-4-nitrophenoxide-with-cu-ii-and-zn-ii-and-their-h-atom-transfer-reactivity
#14
Thomas R Porter, Ellen C Hayes, Werner Kaminsky, James M Mayer
The bulky 2,6-di-tert-butyl-4-nitrophenolate ligand forms complexes with [Tp(tBu)Cu(II)](+) and [Tp(tBu)Zn(II)](+) binding via the nitro group in an unusual nitronato-quinone resonance form (Tp(tBu) = hydro-tris(3-tert-butyl-pyrazol-1-yl)borate). The Cu complex in the solid state has a five-coordinate κ(2)-nitronate structure, while the Zn analogue has a four-coordinate κ(1)-nitronate ligand. 4-Nitrophenol, without the 2,6-di-tert-butyl substituents, instead binds to [Tp(tBu)Cu(II)](+) through the phenolate oxygen...
February 3, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28150941/automated-resin-based-method-to-enhance-the-specific-activity-of-fluorine-18-clicked-pet-radiotracers
#15
Federica Pisaneschi, Lindsay E Kelderhouse, Amanda Hardy, Brian J Engel, Uday Mukhopadhyay, Carlos Gonzalez-Lepera, Joshua P Gray, Argentina Ornelas, Terry T Takahashi, Richard W Roberts, Stephen V Fiacco, David Piwnica-Worms, Steven W Millward
Radiolabeling of substrates with 2-[(18)F]fluoroethylazide exploits the rapid kinetics, chemical selectivity, and mild conditions of the copper-catalyzed azide-alkyne cycloaddition reaction. While this methodology has proven to result in near-quantitative labeling of alkyne-tagged precursors, the relatively small size of the fluoroethylazide group makes separation of the (18)F-labeled radiotracer and the unreacted precursor challenging, particularly with precursors >500 Da (e.g., peptides). We have developed an inexpensive azide-functionalized resin to rapidly remove unreacted alkyne precursor following the fluoroethylazide labeling reaction and integrated it into a fully automated radiosynthesis platform...
February 2, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/28140578/crystal-structures-of-two-new-gold-copper-bimetallic-nanoclusters-cuxau25-x-pph3-10-phc2h4s-5cl2-2-and-cu3au34-pph3-13-t-buphch2s-6s2-3
#16
Sha Yang, Jinsong Chai, Tao Chen, Bo Rao, Yiting Pan, Haizhu Yu, Manzhou Zhu
Herein, we report the synthesis and atomic structures of the cluster-assembled CuxAu25-x(PPh3)10(PhCH2CH2S)5Cl2(2+) and Cu3Au34(PPh3)13((t)BuPhCH2S)6S2(3+) nanoclusters (NCs). The atomic structures of both NCs were precisely determined by single-crystal X-ray crystallography. The CuxAu25-x(PPh3)10(PhC2H4S)5Cl2(2+) NC was assembled by two icosahedral M13 via a vertex-sharing mode. The Cu atom partially occupies the top and waist sites and is monocoordinated with chlorine or thiol ligands. Meanwhile, the Cu3Au34(PPh3)13((t)BuPhCH2S)6S2(3+) NC can be described as three 13-atom icosahedra sharing three vertexes in a cyclic fashion...
February 20, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28139760/ice-core-evidence-of-earliest-extensive-copper-metallurgy-in-the-andes-2700-years-ago
#17
A Eichler, G Gramlich, T Kellerhals, L Tobler, Th Rehren, M Schwikowski
The importance of metallurgy for social and economic development is indisputable. Although copper (Cu) was essential for the wealth of pre- and post-colonial societies in the Andes, the onset of extensive Cu metallurgy in South America is still debated. Comprehensive archaeological findings point to first sophisticated Cu metallurgy during the Moche culture ~200-800 AD, whereas peat-bog records from southern South America suggest earliest pollution potentially from Cu smelting as far back as ~2000 BC. Here we present a 6500-years Cu emission history for the Andean Altiplano, based on ice-core records from Illimani glacier in Bolivia, providing the first complete history of large-scale Cu smelting activities in South America...
January 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28130743/effects-of-zinc-glycinate-on-productive-and-reproductive-performance-zinc-concentration-and-antioxidant-status-in-broiler-breeders
#18
Ling Zhang, Yong-Xia Wang, Xue Xiao, Jiang-Shui Wang, Qian Wang, Kai-Xuan Li, Tian-Yu Guo, Xiu-An Zhan
An experiment was conducted to investigate the effects of zinc glycinate (Zn-Gly) supplementation as an alternative for zinc sulphate (ZnSO4) on productive and reproductive performance, zinc (Zn) concentration and antioxidant status in broiler breeders. Six hundred 39-week-old Lingnan Yellow broiler breeders were randomly assigned to 6 groups consisting of 4 replicates with 25 birds each. Breeders were fed a basal diet (control group, 24 mg Zn/kg diet), basal diet supplemented with 80 mg Zn/kg diet from ZnSO4 or basal diet supplemented with 20, 40, 60 and 80 mg Zn/kg diet from Zn-Gly...
January 27, 2017: Biological Trace Element Research
https://www.readbyqxmd.com/read/28127937/antifouling-biocides-in-german-marinas-exposure-assessment-and-calculation-of-national-consumption-and-emission
#19
Dagmar Daehne, Constanze Fürle, Anja Thomsen, Burkard Watermann, Michael Feibicke
The authorization of biocidal antifouling products for leisure boats is subject of the EU Biocides Regulation 528/2012. National specifics may be regarded by the member states in their assessment of environmental risks. The aim of this survey was to collect corresponding data and to create a data base for the environmental risk assessment of antifouling active substances in German surface waters. Water concentrations of current antifouling active substances and selected break-down products were measured in a single-sampling campaign covering 50 marinas at inland and coastal areas...
January 27, 2017: Integrated Environmental Assessment and Management
https://www.readbyqxmd.com/read/28127691/toxic-metals-in-tissues-of-fishes-from-the-black-sea-and-associated-human-health-risk-exposure
#20
Gabriel Plavan, Oana Jitar, Carmen Teodosiu, Mircea Nicoara, Dragos Micu, Stefan-Adrian Strungaru
The anthropogenic activities in the Black Sea area are responsible for toxic metal contamination of sea food products. In this study, several toxic metals: cadmium, lead, nickel, chromium, and copper were quantified in different tissues (digestive tract, muscle, skeleton, skin) of nine fish species (Neogobius melanostomus, Belone belone, Solea solea, Trachurus mediterraneus ponticus, Sardina pilchardus, Engraulis encrasicolus, Pomatomus saltatrix, Sprattus sprattus, Scorpaena porcus) by using atomic absorption spectrometer with a high-resolution continuum source and graphite furnace technique (HR-CS GF-AAS), and the risk of fish meat consumption by the young human population was evaluated...
January 27, 2017: Environmental Science and Pollution Research International
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