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https://www.readbyqxmd.com/read/28734260/time-averaged-concentrations-are-effective-for-predicting-chronic-toxicity-of-varying-copper-pulse-exposures-for-two-freshwater-green-algae-species
#1
Brad M Angel, Stuart L Simpson, Ellissah Granger, Kathryn Goodwyn, Dianne F Jolley
Intermittent, fluctuating and pulsed contaminant discharges may result in organisms receiving highly variable contaminant exposures. This study investigated the effects of dissolved copper pulse concentration and exposure duration on the toxicity to two freshwater green algae species. The effects of single copper pulses of between 1 and 48 h duration and continuous exposures (72 h) on growth rate inhibition of Pseudokirchneriella subcapitata and Chlorella sp. were compared on a time-averaged concentration (TAC) basis...
July 19, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28734201/modification-of-chemical-properties-cu-fractionation-and-enzymatic-activities-in-an-acid-vineyard-soil-amended-with-winery-wastes-a-field-study
#2
Isabel Rodríguez-Salgado, Paula Pérez-Rodríguez, Antía Gómez-Armesto, Montserrat Díaz-Raviña, Juan Carlos Nóvoa-Muñoz, Manuel Arias-Estévez, David Fernández-Calviño
The effects of adding two winery wastes, perlite waste (PW) and bentonite waste (BW), to an acid vineyard soil were assessed using some chemical and biological soil properties in a field study that lasted 18 months. The addition of PW (up to 81 Mg ha(-1)) had neither significant nor permanent effects on soil characteristics such as the pH, organic matter content or nutrient concentrations, the amounts of copper or zinc, or the electrical conductivity. Moreover, no persistent negative effects were found on the enzymatic activities after PW application...
July 19, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/28732287/factors-affecting-the-interaction-between-carbon-nanotubes-and-redox-enzymes-in-direct-electron-transfer-type-bioelectrocatalysis
#3
Hong-Qi Xia, Yuki Kitazumi, Osamu Shirai, Hiroki Ozawa, Maki Onizuka, Takuji Komukai, Kenji Kano
The effects of three types of water-soluble carbon nanotubes (CNTs) of different lengths on the direct electron transfer (DET)-type bioelectrocatalysis of redox enzymes were investigated. Bilirubin oxidase (BOD), copper efflux oxidase (CueO), and a membrane-bound NiFe hydrogenase (H2ase) were used as model redox enzymes for four-electron dioxygen (O2) reduction (in the case of BOD and CueO) and two-electron dihydrogen (H2) oxidation (in the case of H2ase). As a result, diffusion-controlled O2 reduction in an O2-saturated neutral buffer was realized by BOD on CNTs of a length of 1μm, but the catalytic current densities decreased as the length of CNTs increased...
July 13, 2017: Bioelectrochemistry
https://www.readbyqxmd.com/read/28731683/synthesis-and-optical-properties-of-cu6e6-snph-2-pph2et-6-e-s-se-te-cluster-molecules
#4
Andreas Eichhöfer, Michael Kühn, Sergei Lebedkin, Max Kehry, Manfred M Kappes, Florian Weigend
A homologous series of three copper-tin-chalcogenide cluster molecules [Cu6E6(SnPh)2(PPh2Et)6] (E = S, Se, Te) was synthesized by reactions of CuO(O)CCH3 and PhSnCl3 with E(SiMe3)2 in the presence of PPh2Et. The cluster cage structures are similar, with slight differences in the bridging modes of the respective chalcogenide ligands E. The onset of the optical absorption displays a significant decrease of ca. 1.1 eV on going from sulfur to tellurium. The differences in bonding and electronic excitations can be rationalized by DFT and TDDFT calculations...
July 21, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28731587/reversible-pressure-controlled-depolymerization-of-a-copper-ii-containing-coordination-polymer
#5
Jack Kay Clegg, Aidan Brock, Katrina Jolliffe, Simon Parsons, Leonard Lindoy, Peter Tasker, Fraser White
A unique pressure-induced Cu-N bond breaking/bond forming reaction is reported. The variation of pressure on a single crystal of a one-dimensional copper(II)-containing coordination polymer (Cu2L2(1-methylpiperazine)2]n, where H2L is 1,1'-(1,3-phenylene)-bis(4,4-dimethylpentane-1,3-dione)), was monitored using single crystal X-ray diffraction with the aid of a diamond anvil cell. At a very low elevated pressure (~0.05 GPa) a remarkable reversible phase change was observed. The phase change results in the depolymerization of the material through the cleavage and formation of axial Cu-N bonds as well as "ring flips" of individual axially coordinated 1-methylpiperazine ligands...
July 21, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28731357/visible-light-induced-and-oxygen-promoted-oxidative-cyclization-of-aromatic-enamines-for-the-synthesis-of-quinolines-derivatives
#6
Xiao-Feng Xia, Guo-Wei Zhang, Dawei Wang, Su-Li Zhu
The dual transition metal-visible light photoredox catalysis for the synthesis of quinoline derivatives by using dioxygen as an oxygen source is developed. By using visible light, the direct oxidative cyclization of aromatic enamines with alkynes or alkenes can be achieved at mild conditions with an aide of copper or palladium catalysts, and a variety of multi-substituted quinoline derivatives could be obtained in good to moderate yields under mild reaction conditions.
July 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28731352/exploiting-the-marangoni-effect-to-initiate-instabilities-and-direct-the-assembly-of-liquid-metal-filaments
#7
Christopher A Hartnett, Ivana Seric, Kyle Mahady, Lou Kondic, Shahriar Afkhami, Jason Fowlkes, Philip D Rack
The utilization of the Marangoni effect in a liquid metal is investigated, focusing on initiating instabilities to direct material assembly via the Rayleigh-Plateau instability. Thin (2 nm) copper (Cu) films are lithographically patterned onto thick (12 nm) nickel (Ni) strips to induce a surface energy gradient at the maximum wavelength of the filament instability predicted by Rayleigh-Plateau instability analysis. The pattern is irradiated with an 18 ns pulsed-laser such that the pattern melts and the resultant Ni-Cu surface tension gradient induces Marangoni flows due to the difference in surface energies...
July 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28731322/large-scale-stretchable-semi-embedded-copper-nanowires-transparent-conductive-films-by-electrospinning-template
#8
Xia Yang, Xiaotian Hu, Qingxia Wang, Jian Xiong, Hanjun Yang, Xiangchuan Meng, Licheng Tan, Lie Chen, Yiwang Chen
With recent emergence of wearable electronic devices, the flexible and stretchable transparent electrodes are the core components to realize innovative devices. Copper nanowires (CuNWs) network is commonly chosen because of its high conductivity and transparency. However, the junction resistances and low aspect ratios still limit its further stretchable performance. Herein, a large-scale stretchable semi-embedded CuNWs transparent conductive film (TCFs) was fabricated by electrolessly depositing Cu on the electrospun poly (4-vinylpyridine) (P4VP) polymer template semi-embedded in polydimethylsiloxane (PDMS)...
July 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28731302/lead-ii-binding-in-metallothioneins
#9
Daisy L Wong, Maureen E Merrifield-MacRae, Martin J Stillman
Heavy metal exposure has long been associated with metallothionein (MT) regulation and its functions. MT is a ubiquitous, cysteine-rich protein that is involved in homeostatic metal response for the essential metals zinc and copper, as well as detoxification of heavy metals; the most commonly proposed being cadmium. MT binds in vivo to a number of metals in addition to zinc, cadmium and copper, such as bismuth. In vitro, metallation with a wide range of metals (especially mercury, arsenic, and lead) has been reported using a variety of analytical methods...
April 10, 2017: Metal Ions in Life Sciences
https://www.readbyqxmd.com/read/28731096/a-cu-i-cu-iii-prototypical-organometallic-mechanism-for-the-deactivation-of-an-active-pincer-like-cu-i-catalyst-in-ullmann-type-couplings
#10
Mireia Rovira, Lucie Jašíková, Erik Andris, Ferran Acuña-Parés, Marta Soler, Imma Güell, Ming-Zheng Wang, Laura Gómez, Josep M Luis, Jana Roithová, Xavi Ribas
Unraveling the mechanistic details of copper-catalyzed arylation of nucleophiles (Ullmann-type couplings) is a very challenging task. It is a matter of intense debate whether it is a radical-based process or an organometallic redox-based process. The ancillary ligand choice in Ullmann-type couplings plays a key role in such transformations and can strongly influence the catalytic efficiency as well as the mechanism. Here, we show how a predesigned tridentate pincer-like catalyst undergoes a deactivation pathway through a Cu(I)/Cu(III) prototypical mechanism as demonstrated by helium-tagging infrared photodissociation (IRPD) spectroscopy and DFT studies, lending a strong support to the existence of an aryl-Cu(III) species in the Ullmann couplings using this tridentate ligand...
July 21, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28730840/the-safety-of-available-and-emerging-options-for-emergency-contraception
#11
Jessica K Lee, Eleanor Bimla Schwarz
Emergency contraception (EC) is a way to significantly reduce the chance of becoming pregnant after an episode of unprotected intercourse. Considerable data support the safety of all available and emerging options for EC. Areas covered: This review presents a comprehensive summary of the literature regarding the safety of EC as well as directions for further study. PubMed was searched for all relevant studies published prior to June 2017. Expert Opinion: All available methods of EC (i.e., ulipristal acetate pills, levonorgestrel pills, and the copper-IUD), carry only mild side effects and serious adverse events are essentially unknown...
July 21, 2017: Expert Opinion on Drug Safety
https://www.readbyqxmd.com/read/28730363/leaching-of-cu-cd-pb-and-phosphorus-and-their-availability-in-the-phosphate-amended-contaminated-soils-under-simulated-acid-rain
#12
Hongbiao Cui, Shiwen Zhang, Ruyan Li, Qitao Yi, Xuebo Zheng, Youbiao Hu, Jing Zhou
Phosphate amendments have been used to immobilize heavy metal-contaminated soils. However, phosphate amendments contain large amounts of phosphorus, which could leach out to potentially contaminate groundwater and surface water. A laboratory column leaching experiment was designed to study the effects of simulated acid rain (SAR) on the potential release of copper (Cu), lead (Pb), cadmium (Cd), and phosphorus (P), and their availability after immobilizing with hydroxyapatite (HAP) and potassium dihydrogen phosphate (PDP)...
July 20, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28730201/copper-catalyzed-mannich-type-oxidative-%C3%AE-functionalization-of-tertiary-amines
#13
Min-Jie Zhou, Shou-Fei Zhu, Qi-Lin Zhou
A copper-catalyzed Mannich-type oxidative β-functionalization reaction of amines has been developed. In the presence of an oxidant and a copper catalyst, tertiary amines reacted with N-tosylimines, providing synthetically important 1,3-diamines and enamines, respectively. Preliminary mechanistic studies suggested that the oxidation of the tertiary amine to the enamine intermediate triggers subsequent Mannich-type reactions with N-tosylimines and thus enables the direct β-functionalization of the tertiary amines...
July 21, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28730196/photosensitization-mechanism-of-cu-ii-porphyrins
#14
Jon Uranga, Jon M Matxain, Xabier Lopez, Jesus M Ugalde, David Casanova
This work presents the mechanism of the photoinduced generation of reactive oxygen species (ROS) by paramagnetic copper porphyrins in aqueous solution. Electronic structure calculations within the framework of the (time-dependent) density functional theory, (TD)DFT, reveal the details regarding the development of the atomistic and electronic structures of the copper porphyrin in solution along the set of chemical reactions accessible upon photoactivation. This study identifies the key parameters controlling the feasibility of the various reaction pathways that drive the formation of specific reactive oxygen species, ROS, i...
July 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28730195/copper-catalyzed-stereoconvergent-cis-diastereoselective-borylative-cyclization-of-%C3%AF-mesylate-%C3%AE-%C3%AE-unsaturated-esters-and-ketones
#15
Ya-Jie Zuo, Xiao-Tong Chang, Zhi-Ming Hao, Chong-Min Zhong
The Cu(i)-catalyzed stereoconvergent borylative cyclization of ω-mesylate-α,β-unsaturated compounds is facilitated by a simple Cu-bisphosphine catalyst. This reaction provides a novel route to cis-β-boron-substituted five- and six-membered carbocycle and heterocycle esters. Mechanistic studies indicate that stereoconvergence and cis-substitution likely stem from the rapid enolation of the borylcopper adduct with the substrate double bond and the formation of a five-membered intermediate, respectively.
July 21, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28729961/understanding-dual-precipitation-strengthening-in-ultra-high-strength-low-carbon-steel-containing-nano-sized-copper-precipitates-and-carbides
#16
M P Phaniraj, Young-Min Shin, Woo-Sang Jung, Man-Ho Kim, In-Suk Choi
Low carbon ferritic steel alloyed with Ti, Mo and Cu was hot rolled and interrupt cooled to produce nano-sized precipitates of copper and (Ti,Mo)C carbides. The steel had a tensile strength of 840 MPa, an increase in yield strength of 380 MPa over that of the plain carbon steel and reasonable ductility. Transmission electron microscopy and small angle neutron scattering were used to characterize size and volume fraction of the precipitates in the steels designed to form only copper precipitates and only (Ti,Mo)C carbides...
2017: Nano Convergence
https://www.readbyqxmd.com/read/28729818/a-cooperative-copper-metal-organic-framework-hydrogel-system-improves-wound-healing-in-diabetes
#17
Jisheng Xiao, Siyu Chen, Ji Yi, Hao Zhang, Guillermo A Ameer
Chronic non-healing wounds remain a major clinical challenge that would benefit from the development of advanced, regenerative dressings that promote wound closure within a clinically relevant time frame. The use of copper ions has shown promise in wound healing applications possibly by promoting angiogenesis. However, reported treatments that use copper ions require multiple applications of copper salts or oxides to the wound bed, exposing the patient to potentially toxic levels of copper ions and resulting in variable outcomes...
January 5, 2017: Advanced Functional Materials
https://www.readbyqxmd.com/read/28729697/identification-and-structural-characterization-of-lytu-a-unique-peptidoglycan-endopeptidase-from-the-lysostaphin-family
#18
Vytas Raulinaitis, Helena Tossavainen, Olli Aitio, Jarmo T Juuti, Keiichi Hiramatsu, Vesa Kontinen, Perttu Permi
We introduce LytU, a short member of the lysostaphin family of zinc-dependent pentaglycine endopeptidases. It is a potential antimicrobial agent for S. aureus infections and its gene transcription is highly upregulated upon antibiotic treatments along with other genes involved in cell wall synthesis. We found this enzyme to be responsible for the opening of the cell wall peptidoglycan layer during cell divisions in S. aureus. LytU is anchored in the plasma membrane with the active part residing in the periplasmic space...
July 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28728754/copper-based-reactions-in-analyte-responsive-fluorescent-probes-for-biological-applications
#19
Ho Yu Au-Yeung, Chung Ying Chan, Ka Yan Tong, Zuo Hang Yu
Copper chemistry has been capitalized on in a wide spectrum of biological events. The central importance of copper in biology lies in the diverse chemical reactivity of the redox-active transition metal ranging from electron transfer, small molecule binding and activation, to catalysis. In addition to its many different roles in natural biological systems, the diverse chemical reactivity of copper also represents a rich opportunity and resource to develop synthetic bioanalytical tools for the study of biologically important species and molecules...
July 4, 2017: Journal of Inorganic Biochemistry
https://www.readbyqxmd.com/read/28728354/spatial-assessment-of-potential-ecological-risk-of-soil-heavy-metals-from-informal-e-waste-recycling-in-ghana
#20
Vincent Nartey Kyere, Klaus Greve, Sampson Atiemo, James Hawkins Ephraim
The rapidly increasing annual global volumes and the inherently valuable fractions of e-waste have created an avenue for individuals in Agbogbloshie, Accra, Ghana to make a living by utilizing unconventional, uncontrolled, primitive and crude procedures to recycle and recover valuable metals from these wastes. The current form of recycling procedures releases hazardous fractions such as heavy metals into the soils posing a significant risk to ecology and human health. 132 soil samples based on 100 m grid intervals were collected using handheld GPS and analyzed for Cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), lead (Pb) and zinc (Zn) heavy metals...
July 10, 2017: Environmental Health and Toxicology
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