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Pedro Echeveste, Jaqueline C Silva, Ana T Lombardi
Copper and Cd are natural constituents of freshwater ecosystems, both cycling influenced by microbial communities. The present research examined the impacts of environmentally relevant concentrations of Cu and Cd on the growth, viability, cell size, chlorophyll a (Chl a) content and photochemical efficiency of the tropical freshwater phytoplankton Chlorolobion braunii. Cell growth was significantly impaired by Cu and Cd, with EC50 occurring at 33.6 and 1.6µM, respectively. At sublethal levels (< EC50), cell death was already induced at 5µM Cu and 1µMCd...
May 25, 2017: Ecotoxicology and Environmental Safety
Xin Qin, Shuwen Fang, Lei Zhao, Penghui Shi, Jinchen Fan, Yulin Min, Qunjie Xu, Weifeng Yao
Cobalt super-microparticles anchored on nitrogen-doped graphene (Co-NG) were prepared using an inexpensive method and were tested for heterogeneous oxidation of aniline with peroxymonosulfate (PMS) in aqueous solutions. The crystal structure, morphology, and textural properties of Co-NG hybrids were investigated by various characterization techniques, such as X-ray diffraction, Raman spectroscopy, dark-field scanning transmission electron microscopy and X-ray photoelectron spectroscopy. Electron paramagnetic resonance and classical quenching tests were conducted to investigate the mechanism of PMS activation and aniline oxidation...
May 25, 2017: Science of the Total Environment
Jing-Xing Wu, Bing Yan
A highly fluorescent metal-organic framework (In-MOF, In(OH)bpydc (bpydc=biphenyl-5,5'-dicarboxylate)) imparting additional luminescent Eu(3+) ions has been synthesized for sensing organic molecules and anions, especially chloroform and MnO4(-), both of them have a significant spectral response. This Eu(3+)-incorporated hybrid (In-MOF-Eu) has been fully characterized, which reveals large surface area, great pore size, favorable thermal stability, excellent luminescence as well as good fluorescence stability...
May 19, 2017: Journal of Colloid and Interface Science
Zhenzhen Li, Qiyi Zhang, Huaying Huang, Changjing Ren, Si Ouyang, Qiang Zhao
In this paper, near-infrared (NIR) light emitting L-noradrenaline functionalized CdSeTe QDs (NA-CdSeTe) were synthesized and applied to the biosensing of urea. When the pH value of NA-CdSeTe solution was adjusted from neutral to alkalinity, the noradrenaline on the surface of QDs would turn to quinone, which triggered the fluorescence quenching of NA-CdSeTe probe due to the charge transfer interactions between QDs and the proximal quinone. Based on the fact that the hydrolysis of urea in the presence of urease would release OH(-) and slightly change the pH value of the solution, the fluorescence intensity of NA-CdSeTe QDs could be linked to the enzymatic degradation of urea...
August 15, 2017: Talanta
Yan Zhang, Min Li, Qinqin Niu, Pengfei Gao, Guomei Zhang, Chuan Dong, Shaomin Shuang
As a highly toxic environmental pollutant and also an important gasotransmitter in diverse physiological processes, the selective and sensitive detection of hydrogen sulfide (H2S) is very significant. In this work, acetylcysteine stabilized gold nanoclusters (ACC@AuNCs)-based fluorescent sensors had been successfully constructed for H2S perception. The sensing principle was that H2S-induced fluorescence quenching of AuNCs which attributed to both the formation of Au2S between Au(I) in the AuNCs and H2S and the increased particle size...
August 15, 2017: Talanta
Tânia Ribeiro, Carlos Baleizão, José Paulo S Farinha
Metal nanoparticles can either quench or enhance the emission of dyes in their vicinity, but the precise measurement and understanding of this effect is still hindered by experimental artifacts, especially for particles in colloidal dispersion. Here, we introduce a new methodology to correct the inner filter effect of the metal on the dye emission. To test the method, we developed new hybrid nanoparticles with a gold core and a silica shell of precise thickness (tuned from 7 to 13 nm), with a high quantum yield perylenediimide dye on the surface...
May 26, 2017: Scientific Reports
Marzieh Jafari, Javad Tashkhourian, Ghodratollah Absalan
A simple, fast and green method for chiral recognition of S- and R-naproxen has been introduced. The method was based on quenching of the fluorescence intensity of bovine serum albumin-stabilized gold nanoclusters in the presence of naproxen enantiomers. The quenching intensity in the presence of S-naproxen was higher than R-naproxen when phosphate buffer solution at pH7.0 was used. The chiral recognition occurred due to steric effect between bovine serum albumin conformation and naproxen enantiomers. Two linear determination range were established as 7...
May 16, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Jian Zhang, Qian Zhao, Yudong Wu, Bo Zhang, Weipan Peng, Jiafang Piao, Yurui Zhou, Weichen Gao, Xiaoqun Gong, Jin Chang
Microbeads-based microchip technology has become the potential for a new generation of nucleic acids detection in a high-throughput and sensitive manner. However the specificity and operational complexity limit the microchip applied in nucleic acids detection. Herein, in this work, we designed a kind of gold-nanoparticles coated polystyrene microbeads as microplatform conjugating with the molecular beacons as probes. Due to the nanoparticle surface energy transfer of gold-nanoparticles, the fluorescence of dye on one end of molecular beacons was effectively quenched...
May 23, 2017: Biosensors & Bioelectronics
Meghan Kohne, Chen Zhu, Kurt Warncke
The kinetics of the substrate radical rearrangement reaction step in B12-dependent ethanolamine ammonia-lyase (EAL) from Salmonella typhimurium are measured over a 92 K temperature range. The observed first-order rate constants display a piecewise-continuous Arrhenius dependence, with linear regions over 295→220 K (monoexponential) and 214→203 K (biexponential) that are delineated by a kinetic bifurcation and kinks at 219 and 217 K, respectively. The results are interpreted by using a free energy landscape model and derived microscopic kinetic mechanism...
May 26, 2017: Biochemistry
J W González, T Alonso-Lanza, F Delgado, F Aguilera-Granja, A Ayuela
Organometallic clusters based on transition metal atoms are interesting because of their possible applications in spintronics and quantum information processing. In addition to the enhanced magnetism at the nanoscale, the organic ligands may provide a natural shield against unwanted magnetic interactions with the matrices required for applications. Here we show that the organic ligands may lead to non-collinear magnetic order as well as the expected quenching of the magnetic moments. We use different density functional theory (DFT) methods to study the experimentally relevant three cobalt atoms surrounded by benzene rings (Co3Bz3)...
May 26, 2017: Physical Chemistry Chemical Physics: PCCP
M Luísa Ramos, Licínia L G Justino, Rui Barata, Telma Costa, Bernardo A Nogueira, Rui Fausto, Hugh D Burrows
Multinuclear ((1)H and (13)C) NMR, and Raman spectroscopy, combined with DFT calculations, provide detailed information on the complexation between U(vi) oxoions and 8-hydroxyquinoline-5-sulfonate (8-HQS) in aqueous solution. Over the concentration region studied, U(vi) oxoions (uranyl ions) form one dominant complex with 8-HQS in water in the pH range 3-6, a mononuclear 1 : 2 (metal : ligand) complex, with the metal centre (UO2(2+)) coordinated to two 8-HQS ligands, together with one or more water molecules...
May 26, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Matthias Puhr, P V Buividovich
We demonstrate the nonrenormalization of the chiral separation effect (CSE) in quenched finite-density QCD in both confinement and deconfinement phases using a recently developed numerical method which allows us, for the first time, to address the transport properties of exactly chiral, dense lattice fermions. This finding suggests that CSE can be used to fix renormalization constants for axial current density. Explaining the suppression of the CSE which we observe for topologically nontrivial gauge field configurations on small lattices, we also argue that CSE vanishes for self-dual non-Abelian fields inside instanton cores...
May 12, 2017: Physical Review Letters
Lanhua Chen, Juan Diwu, Daxiang Gui, Yaxing Wang, Zhehui Weng, Zhifang Chai, Thomas E Albrecht-Schmitt, Shuao Wang
The oxidation state greatly affects the chemical behavior of uranium in the nuclear fuel cycle and in the environment. Phosphonate ligands, on the other hand, show strong complexation toward uranium at different oxidation states and are widely used in nuclear fuel reprocessing. Therefore, in this work, the reduction behavior of U(VI) with the presence of a phosphonate ligand is investigated under mild solvothermal conditions. By adjusting the reaction time, temperature, and counterion species, a series of uranium diphosphonates including two U(VI), seven U(IV), two mixed-valent U(IV/VI), and one distinct U(IV/V/VI) compounds were obtained...
May 26, 2017: Inorganic Chemistry
Trisha Das, Ankita Roy, Hiroshi Uyama, Partha Roy, Mahasweta Nandi
Mesoporous silica functionalized with a 2-hydroxy-naphthyl moiety has been synthesized and characterized by standard techniques like powder X-ray diffraction, N2 adsorption/desorption studies, transmission electron microscopy and spectral studies like FT-IR, UV-visible, fluorescence and (13)C and (29)Si solid state NMR. The functionalized silica material showed significant enhancement in its emission intensity in the presence of Al(3+) ions whereas other metal ions could not bring about any increase in its emission intensity...
May 26, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Haamid R Bhat, Prakash C Jha
The binding selectivity and recognition mechanism of a series of mono-, di- and triphosphonium substituted triarylboranes: (4-(dimesitylboryl)-3,5-dimethylphenyl)phosphonium ([Mes2BAr(P)](+), 1), 1,1'-mesitylboranediylbis(3,5-dimethylphenyl)phosphonium ([MesBAr(P)2](2+), 2) and 1,1',1''-boranetriyltris(3,5-dimethylphenyl)phosphonium ([BAr(P)3](3+), 3) where Ar(P) = 4-(H3P)-2,6-Me2-C6H2, for various anions has been investigated by employing density functional theory (DFT) and time dependent-density functional theory (TD-DFT) methods...
May 26, 2017: Physical Chemistry Chemical Physics: PCCP
Yizhe Sun, Yibin Jiang, Huiren Peng, Jiangliu Wei, Shengdong Zhang, Shuming Chen
Efficient inverted quantum-dot (QD) light-emitting diodes (LEDs) are demonstrated by using 15% Mg doped ZnO (Zn0.85Mg0.15O) as an interfacial modification layer. By doping Mg into ZnO, the conduction band level, the density of oxygen vacancies and the conductivity of the ZnO can be tuned. To suppress excess electron injection, a 13 nm Zn0.85Mg0.15O interlayer with a relatively higher conduction band edge and lower conductivity is inserted between the ZnO electron transport layer and QD light-emitting layer, which improves the balance of charge injection and blocks the non-radiative pathway...
May 26, 2017: Nanoscale
Diana Imhof, Amelie Wißbrock
A genetically encoded protein sensor based on HRP2 was used to detect heme in the human malaria parasite Plasmodium falciparum using fluorescence-quenching after heme binding. Protein labels ECFP and EYFP were attached to the termini to allow for a FRET signal as the initial detection parameter before heme binding. The sensor was eventually used to investigate alterations of the labile heme pool during the parasite's life cycle as well as under the influence of the drug chloroquine.
May 26, 2017: Chembiochem: a European Journal of Chemical Biology
Kaixin Xia, Guowen Zhang, Song Li, Deming Gong
Vanillin (VAN) and ethyl vanillin (EVA) are widely used food additives as flavor enhancers, but may have a potential security risk. In this study, the properties of binding of VAN or EVA with calf thymus DNA (ctDNA) were characterized by multi-spectroscopic methods, multivariate curve resolution-alternating least-squares (MCR-ALS) algorithm and molecular simulation. The concentration profiles for the components (VAN or EVA, ctDNA and VAN-ctDNA or EVA-ctDNA complex) by the MCR-ALS analysis showed that VAN or EVA interacted with ctDNA and formed VAN-ctDNA or EVA-ctDNA complex...
May 25, 2017: Journal of Fluorescence
Seong-Eun Kim, Sung Duk Jo, Koo Chul Kwon, You-Yeon Won, Jeewon Lee
Hepatitis B virus capsid (HBVC), a self-assembled protein nanoparticle comprised of 180 or 240 subunit proteins, is used as a cage for genetic encapsulation of fluorescent proteins (FPs). The self-quenching of FPs is controlled by varying the spacing between FPs within the capsid structure. Double-layered FP nanoparticle possessing cancer cell-targeting capabilities is also produced by additionally attaching FPs and cancer cell receptor-binding peptides (affibodies) to the outer surface of the capsid. The generically modified HBVC with double layers of mCardinal FPs and affibodies (mC-DL-HBVC) exhibit a high fluorescence intensity and a strong photostability, and is efficiently internalized by cancer cells and significantly stable against intracellular degradation...
May 2017: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Shaqayeq Roqanian, Ali Akbar Meratan, Shahin Ahmadian, Mahshid Shafizadeh, Atiyeh Ghasemi, Leila Karami
Increasing body of evidence suggests that polyphenols frequently interacting with amyloid aggregates and/or interfering with aggregate species to bind biomembranes may serve as a therapeutic approach for the treatment of amyloid-related diseases. Hence, in the present study, the possible effects of three naturally occurring polyphenols including Curcumin, Quercetin, and Resveratrol on mitochondrial membrane permeabilization induced by Hen Egg White Lysozyme (HEWL) oligomers were investigated. Our results indicated that pre-incubation of mitochondrial homogenate with polyphenols considerably inhibit membrane permeabilization in a concentration dependent manner...
May 22, 2017: International Journal of Biological Macromolecules
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