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https://www.readbyqxmd.com/read/28646308/photochemical-generation-of-reactive-intermediates-from-urban-waste-bio-organic-substances-under-uv-and-solar-irradiation
#1
Marcela Prado Silva, Arlen Mabel Lastre-Acosta, Simón Mostafa, Garrett McKay, Karl G Linden, Fernando L Rosario-Ortiz, Antonio Carlos Silva Costa Teixeira
Singlet oxygen ((1)O2), hydroxyl radicals ((•)OH), and excited triplet states of organic matter ((3)OM(*)) play a key role in the degradation of pollutants in aquatic environments. The formation rates and quantum yields (Φ) of these reactive intermediates (RI) through photosensitized reactions of dissolved organic matter (DOM) have been reported in the literature for decades. Urban biowaste-derived substances (UW-BOS), a form of organic matter derived from vegetative and urban waste, have recently been shown to be efficient sensitizers in the photo-degradation of different contaminants...
June 23, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28645032/physiological-traits-and-antioxidant-metabolism-of-leaves-of-tropical-woody-species-challenged-with-cement-dust
#2
Advanio Inácio Siqueira-Silva, Eduardo Gusmão Pereira, José Pires de Lemos-Filho, Luzia Valentina Modolo, Elder Antonio Sousa Paiva
Tropical woody species occurring in limestone outcrops are frequently exposed to particulate material from cement factories. The effects of 60-day cement dust exposure on physiological traits and enzymatic antioxidant system of young plant leaves of Guazuma ulmifolia Lam., Myracrodruon urundeuva Allemão and Trichilia hirta L. were investigated. Cement dust (2.5 or 5mgcm(-2)) was applied to the leaf surface or soil or both (leaf plus soil) and plants were maintained at greenhouse. Cement dust barely affected the mineral nutrient levels, except for iron whose content was decreased in leaves/leaflets of all species studied...
June 20, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/28644849/rapid-development-of-cyanobacterial-crust-in-the-field-for-combating-desertification
#3
Chan-Ho Park, Xin Rong Li, Yang Zhao, Rong Liang Jia, Jae-Seoun Hur
Desertification is currently a major concern, and vast regions have already been devastated in the arid zones of many countries. Combined application of cyanobacteria with soil fixing chemicals is a novel method of restoring desertified areas. Three cyanobacteria, Nostoc sp. Vaucher ex Bornet & Flahault, Phormidium sp. Kützing ex Gomont and Scytonema arcangeli Bornet ex Flahault were isolated and tested in this study. Tacki-SprayTM (TKS7), which consists of bio-polysaccharides and tackifiers, was used as a soil fixing agent...
2017: PloS One
https://www.readbyqxmd.com/read/28644616/importance-of-a-fully-anharmonic-treatment-of-equilibrium-isotope-fractionation-properties-of-dissolved-ionic-species-as-evidenced-by-li-aq
#4
Romain Dupuis, Magali Benoit, Mark E Tuckerman, Merlin Méheut
Equilibrium fractionation of stable isotopes is critically important in fields ranging from chemistry, including medicinal chemistry, electrochemistry, geochemistry, and nuclear chemistry, to environmental science. The dearth of reliable estimates of equilibrium fractionation factors, from experiment or from natural observations, has created a need for accurate computational approaches. Because isotope fractionation is a purely quantum mechanical phenomenon, exact calculation of fractionation factors is nontrivial...
June 23, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28644615/fluoromodules-consisting-of-a-promiscuous-rna-aptamer-and-red-or-blue-fluorogenic-cyanine-dyes-selection-characterization-and-bioimaging
#5
Xiaohong Tan, Tudor P Constantin, Kelly L Sloane, Alan S Waggoner, Marcel P Bruchez, Bruce A Armitage
An RNA aptamer selected for binding to the fluorogenic cyanine dye, dimethylindole red (DIR), also binds and activates another cyanine, oxazole thiazole blue (OTB), giving two well-resolved emission colors. The aptamer binds to each dye with submicromolar KD values, and the resulting fluoromodules exhibit fluorescence quantum yields ranging from 0.17 to 0.51 and excellent photostability. The aptamer was fused to a second aptamer previously selected for binding to the epidermal growth factor receptor (EGFR) to create a bifunctional aptamer that labels cell-surface EGFR on mammalian cells...
June 23, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28644463/hypersensitive-dual-function-luminescence-switching-of-a-silver-chalcogenolate-cluster-based-metal-organic-framework
#6
Ren-Wu Huang, Yong-Sheng Wei, Xi-Yan Dong, Xiao-Hui Wu, Chen-Xia Du, Shuang-Quan Zang, Thomas C W Mak
Silver(i) chalcogenide/chalcogenolate clusters are promising photofunctional materials for sensing, optoelectronics and solar energy harvesting applications. However, their instability and poor room-temperature luminescent quantum yields have hampered more extensive study. Here, we graft such clusters to adaptable bridging ligands, enabling their interconnection and the formation of rigid metal-organic frameworks. By controlling the spatial separation and orientation of the clusters, they then exhibit enhanced stability (over one year) and quantum yield (12...
July 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28644033/direct-indirect-nature-of-the-bandgap-in-lead-free-perovskite-nanocrystals
#7
Yuhai Zhang, Jun Yin, Manas R Parida, Ghada H Ahmed, Jun Pan, Osman M Bakr, Jean-Luc Bredas, Omar F Mohammed
With record efficiencies achieved in lead halide perovskite-based photovoltaics, urgency has shifted towards finding alternative materials that are stable and less-toxic. Bismuth-based perovskite materials are currently one of the most promising candidates amongst those alternatives. However, the band structures of these materials, including the nature of the bandgaps, remain elusive due to extremely low photoluminescence quantum yield (PLQY) and scattering issues in their thin-film or bulk form. Here, we overcome those limitations and reveal the specific nature of the material's electronic transitions by realizing monodisperse colloidal nanocrystals (NCs) of hexagonal-phase Cs3Bi2X9 perovskites, which afford well-resolved PL features...
June 23, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28643778/a-decoherence-free-subspace-in-a-charge-quadrupole-qubit
#8
Mark Friesen, Joydip Ghosh, M A Eriksson, S N Coppersmith
Quantum computing promises significant speed-up for certain types of computational problems. However, robust implementations of semiconducting qubits must overcome the effects of charge noise that currently limit coherence during gate operations. Here we describe a scheme for protecting solid-state qubits from uniform electric field fluctuations by generalizing the concept of a decoherence-free subspace for spins, and we propose a specific physical implementation: a quadrupole charge qubit formed in a triple quantum dot...
June 23, 2017: Nature Communications
https://www.readbyqxmd.com/read/28643462/selenium-doped-carbon-quantum-dots-se-cqds-for-free-radical-scavenging
#9
Feng Li, Tianyu Li, Chenxing Sun, Jiahao Xia, Yang Jiao, Huaping Xu
Heteroatom doping is an effective way to adjust the fluorescent properties of carbon quantum dots. However, selenium-doped carbon dots have rarely been reported even though selenium has unique chemical properties like redox-responsive properties owing to its special electronegativity. Herein, a facile and high-output strategy to fabricate selenium-doped carbon quantum dots (Se-CQDs) with green fluorescence (quantum yield 7.6 %) is developed through the hydrothermal treatment of selenocystine under mild conditions...
June 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28642785/potassium-starvation-limits-soybean-growth-more-than-the-photosynthetic-processes-across-co2-levels
#10
Shardendu K Singh, Vangimalla R Reddy
Elevated carbon dioxide (eCO2) often enhances plant photosynthesis, growth, and productivity. However, under nutrient-limited conditions the beneficial effects of high CO2 are often diminished. To evaluate the combined effects of potassium (K) deficiency and eCO2 on soybean photosynthesis, growth, biomass partitioning, and yields, plants were grown under controlled environment conditions with an adequate (control, 5.0 mM) and two deficient (0.50 and 0.02 mM) levels of K under ambient CO2 (aCO2; 400 μmol mol(-1)) and eCO2 (800 μmol mol(-1))...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28641426/assessment-of-two-hybrid-van-der-waals-density-functionals-for-covalent-and-non-covalent-binding-of-molecules
#11
Kristian Berland, Yang Jiao, Jung-Hoon Lee, Tonatiuh Rangel, Jeffrey B Neaton, Per Hyldgaard
Two hybrid van der Waals density functionals (vdW-DFs) are developed using 25% Fock exchange with (i) the consistent-exchange vdW-DF-cx functional [K. Berland and P. Hyldgaard, Phys. Rev. B 89, 035412 (2014)] and (ii) with the vdW-DF2 functional [K. Lee et al., Phys. Rev. B 82, 081101 (2010)]. The ability to describe covalent and non-covalent binding properties of molecules is assessed. For properties related to covalent binding, atomization energies (G2-1 set), molecular reaction energies (G2RC set), and ionization energies (G21IP set) are benchmarked against experimental reference values...
June 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28641248/method-for-simulating-dose-reduction-in-digital-breast-tomosynthesis
#12
Lucas R Borges, Igor Guerrero, Predrag R Bakic, Alessandro Foi, Andrew D A Maidment, Marcelo A C Vieira
This work proposes a new method of simulating dose reduction in digital breast tomosynthesis (DBT), starting from a clinical image acquired with a standard radiation dose. It considers both signal-dependent quantum and signal-independent electronic noise. Furthermore, the method accounts for pixel crosstalk, which causes the noise to be frequency-dependent, thus increasing the simulation accuracy. For an objective assessment, simulated and real images were compared in terms of noise standard deviation, signal-to-noise ratio (SNR) and normalized noise power spectrum (NNPS)...
June 15, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28641143/spectroscopic-and-thermodynamic-studies-of-light-harvesting-perylenediimide-derivative-zinc-porphyrin-complex-in-aqueous-media
#13
Ahmed El-Refaey, Shaban Y Shaban, Maged El-Kemary, Mohamed E El-Khouly
Self-assembly of perylene derivative such as N,N'-bis(2(trimethylammonium iodide) ethylene)perylene-3,4,9,10-tetracarboxyldiimide (TAIPDI) can produce one-dimensional form (1D) in an aqueous media. The ability of one-dimensional TAIPDI to form light harvesting complex with water-soluble zinc porphyrin (ZnTPPS4) via the π-π and electrostatic interactions has been described. Owing to electronic interactions between the π-systems, the complex formation is accompanied by pronounced absorption spectral changes in the UV/Vis absorption bands...
June 15, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28640637/designing-transmitter-ligands-that-mediate-energy-transfer-between-semiconductor-nanocrystals-and-molecules
#14
Zhiyuan Huang, Ming Lee Tang
Molecular control of energy transfer is an attractive proposition because it allows chemists to synthetically tweak various kinetic and thermodynamic factors. In this Perspective, we examine energy transfer between semiconductor nano-crystals (NCs) and π-conjugated molecules, focusing on the transmitter ligand at the organic-inorganic interface. Efficient transfer of triplet excitons across this interface allows photons to be directed for effective use of the entire solar spectrum. For example, a photon upconversion system composed of semiconductor NCs as sensitizers, bound organic ligands as transmitters, and molecular annihilators has the advantage of large, tunable absorption cross-sections across the visible and near infrared wavelengths...
June 22, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28640518/a-carborane-containing-fluorophore-as-a-stain-of-cellular-lipid-droplets
#15
Andrew Wu, Jacek L Kolanowski, Badwi B Boumelhem, Kylie Yang, Rebecca Lee, Amandeep Kaur, Stuart T Fraser, Elizabeth J New, Louis M Rendina
The use of fluorescent markers and probes greatly enhances biological investigations but relies on the provision of an array of fluorophores with diverse properties. Herein we report a novel carborane-containing coumarin, 5, which is sufficiently lipophilic to localise in cellular lipid droplets. In non-polar solvents which show comparable polarities to those of a lipid environment, compound 5 exhibits a fluorescence quantum yield two orders of magnitude greater than found in aqueous solvents, adding a further degree of selectivity to lipid droplet imaging...
June 22, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28640479/visible-light-photocatalysis-of-6%C3%AF-heterocyclization
#16
Martin Derwyn Smith, Niels Münster, Nicholas Parker, Lucy van Dijk, Robert Paton
Photo-mediated 6π cyclization is a valuable method for the formation of fused heterocyclic systems. Here we demonstrate that irradiation of cyclic 2-aryloxyketones with blue LED light in the presence of an Ir(III) complex leads to efficient and high yielding arylation across a panoply of substrates by energy transfer. 2-arylthioketones and 2-arylaminoketones also cyclize effectively under these conditions. Quantum calculation demonstrates that the reaction proceeds via conrotatory ring closure in the triplet excited state...
June 22, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28640463/exciton-recombination-in-formamidinium-lead-triiodide-nanocrystals-versus-thin-films
#17
Hong-Hua Fang, Loredana Protesescu, Daniel M Balazs, Sampson Adjokatse, Maksym V Kovalenko, Maria Antonietta Loi
The optical properties of the newly developed near-infrared emitting formamidinium lead triiodide (FAPbI3 ) nanocrystals (NCs) and their polycrystalline thin film counterpart are comparatively investigated by means of steady-state and time-resolved photoluminescence. The excitonic emission is dominant in NC ensemble because of the localization of electron-hole pairs. A promisingly high quantum yield above 70%, and a large absorption cross-section (5.2 × 10(-13) cm(-2) ) are measured. At high pump fluence, biexcitonic recombination is observed, featuring a slow recombination lifetime of 0...
June 22, 2017: Small
https://www.readbyqxmd.com/read/28638777/heterobifunctional-dyes-highly-fluorescent-linkers-based-on-cyanine-dyes
#18
Virginia Wycisk, Katharina Achazi, Ole Hirsch, Christian Kuehne, Jens Dernedde, Rainer Haag, Kai Licha
Herein, we present a new synthetic route to cyanine-based heterobifunctional dyes and their application as fluorescent linkers between polymers and biomolecules. The synthesized compounds, designed in the visible spectral range, are equipped with two different reactive groups for highly selective conjugation under physiological conditions. By applying indolenine precursors with functionalized benzenes, we achieved water-soluble asymmetric cyanine dyes bearing maleimido and N-hydroxysuccinimidyl functionalities in a three-step synthesis...
June 2017: ChemistryOpen
https://www.readbyqxmd.com/read/28638470/bright-polymer-dots-tracking-stem-cell-engraftment-and-migration-to-injured-mouse-liver
#19
Dandan Chen, Qiong Li, Zihui Meng, Lei Guo, Ying Tang, Zhihe Liu, Shengyan Yin, Weiping Qin, Zhen Yuan, Xuanjun Zhang, Changfeng Wu
Stem cell therapy holds promise for treatment of intractable diseases and injured organs. For clinical translation, it is pivotal to understand the homing, engraftment, and differentiation processes of stem cells in a living body. Here we report near-infrared (NIR) fluorescent semiconductor polymer dots (Pdots) for bright labeling and tracking of human mesenchymal stem cells (MSCs). The Pdots exhibit narrow-band emission at 775 nm with a quantum yield of 22%, among the highest value for various NIR probes. The Pdots together with a cell penetrating peptide are able to track stem cells over two weeks without disturbing their multipotent properties, as confirmed by the analyses on cell proliferation, differentiation, stem-cell markers, and immunophenotyping...
2017: Theranostics
https://www.readbyqxmd.com/read/28638177/highly-luminescent-water-dispersible-nir-emitting-wurtzite-cuins2-zns-core-shell-colloidal-quantum-dots
#20
Chenghui Xia, Johannes D Meeldijk, Hans C Gerritsen, Celso de Mello Donega
Copper indium sulfide (CIS) quantum dots (QDs) are attractive as labels for biomedical imaging, since they have large absorption coefficients across a broad spectral range, size- and composition-tunable photoluminescence from the visible to the near-infrared, and low toxicity. However, the application of NIR-emitting CIS QDs is still hindered by large size and shape dispersions and low photoluminescence quantum yields (PLQYs). In this work, we develop an efficient pathway to synthesize highly luminescent NIR-emitting wurtzite CIS/ZnS QDs, starting from template Cu2-x S nanocrystals (NCs), which are converted by topotactic partial Cu(+) for In(3+) exchange into CIS NCs...
June 13, 2017: Chemistry of Materials: a Publication of the American Chemical Society
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