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https://www.readbyqxmd.com/read/28545217/a-miniature-bird-borne-passive-air-sampler-for-monitoring-halogenated-flame-retardants
#1
Manon Sorais, Ali Rezaei, Joseph O Okeme, Miriam L Diamond, Ricardo Izquierdo, Jean-François Giroux, Jonathan Verreault
Birds have been used intensively as biomonitors of halogenated flame retardants (HFRs), and several studies have reported elevated tissue concentrations and inter-individual variability for these contaminants. While diet is known to be an important exposure pathway for HFRs in birds, it has been suggested that exposure through air may represent an underestimated source of HFRs for certain species. However, a method was not available for measuring the atmospheric exposure of individual birds to HFRs or other semi-volatile contaminants...
May 21, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28545000/occurrence-and-effects-of-plastic-additives-on-marine-environments-and-organisms-a-review
#2
REVIEW
Ludovic Hermabessiere, Alexandre Dehaut, Ika Paul-Pont, Camille Lacroix, Ronan Jezequel, Philippe Soudant, Guillaume Duflos
Plastics debris, especially microplastics, have been found worldwide in all marine compartments. Much research has been carried out on adsorbed pollutants on plastic pieces and hydrophobic organic compounds (HOC) associated with microplastics. However, only a few studies have focused on plastic additives. These chemicals are incorporated into plastics from which they can leach out as most of them are not chemically bound. As a consequence of plastic accumulation and fragmentation in oceans, plastic additives could represent an increasing ecotoxicological risk for marine organisms...
May 16, 2017: Chemosphere
https://www.readbyqxmd.com/read/28544958/impact-of-triblock-copolymers-on-the-biophysical-function-of-naturally-derived-lung-surfactant
#3
Moritz Beck-Broichsitter, Christian A Ruge, Adam Bohr
The current study aimed at investigating the general applicability of triblock copolymers consisting of poly(ethylene glycol) and poly(propylene glycol) (Pluronic(®)) as excipients for lung delivery. After thorough physicochemical characterization of the diverse polymers, their cytotoxicity was evaluated using alveolar epithelial cells. Next, a naturally-derived lung surfactant was challenged with the distinct triblock copolymers with respect to changes in microstructure, adsorption to the air/liquid interface and dynamic surface tension behavior under bubble pulsation...
May 17, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28544915/pyrrole-based-poly-ionic-liquids-as-efficient-stabilizers-for-formation-of-hollow-multi-walled-carbon-nanotubes-particles
#4
Prithwish Chatterjee, Elizabeth M Nofen, Wenwen Xu, Conrad Hom, Hanqing Jiang, Lenore L Dai
Poly(ionic liquid) (PIL) derivatives with pyrrole intrinsically conducting polymer (ICP) backbones were synthesized and utilized as novel dispersants of multi-walled carbon nanotubes (MWCNTs) in various aqueous and non-aqueous systems, including polar and nonpolar solvents. This is due to the highly tunable nature of the PIL, in which the PILs of varying polarity with the same pyrrole-based polycation can be synthesized. The dispersions are exceedingly stable over many months, and with the addition of hexane, Pickering (solid-stabilized) emulsions with the PIL-stabilized MWCNTs at the droplet interfaces were formed...
April 8, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28544851/low-ceiling-temperature-polymer-microcapsules-with-hydrophobic-payloads-via-rapid-emulsion-solvent-evaporation
#5
Shijia Tang, Mostafa Yourdkhani, Catherine M Possanza Casey, Nancy R Sottos, Scott R White, Jeffrey S Moore
We report a microencapsulation procedure based on rapid solvent evaporation to prepare microcapsules with hydrophobic core materials and low ceiling temperature polymer shell wall of cyclic poly(phthalaldehyde) (cPPA). We use and compare microfluidic and bulk emulsions. In both methods, rapid solvent evaporation following emulsification resulted in kinetically trapped core-shell microcapsules while slow evaporation resulted in acorn morphology. Through the systematic variation of encapsulation parameters, we found that polymer-to-core weight ratios higher than 1 and polymer concentration higher than 4...
May 25, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28544845/self-assembling-zwitterionic-copolymers-as-membrane-selective-layers-with-excellent-fouling-resistance-effect-of-zwitterion-chemistry
#6
Prity Bengani-Lutz, Elisha Converse, Peggy Cebe, Ayse Asatekin
Membranes with high flux, ~1 nm pore size and unprecedented protein fouling resistance were prepared by forming selective layers of self-assembling zwitterionic amphiphilic random copolymers on porous supports by a simple coating method. Random copolymers were prepared from the hydrophobic monomer 2,2,2-trifluoroethyl methacrylate (TFEMA) and four zwitterionic monomers (sulfobetaine methacrylate, sulfobetaine 2-vinylpyridine, sulfobutylbetaine 2-vinylpyridine and 2-methacryloyloxyethyl phosphorylcholine) by free radical polymerization...
May 25, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28544763/hp30-2-a-mitochondrial-prat-protein-for-import-of-signal-sequence-less-precursor-proteins-in-arabidopsis-thaliana
#7
Claudia Rossig, John Gray, Oscar Valdes, Sachin Rustgi, Diter von Wettstein, Christiane Reinbothe, Steffen Reinbothe
Chloroplasts and mitochondria contain a family of putative preprotein and amino acid transporters designated PRAT. Here, we analyzed the role of two previously characterized PRAT protein family member, encoded by At3g49560 (HP30) and At5g24650 (HP30-2), in planta using a combination of genetic, cell biological and biochemical approaches. Expression studies and GFP tagging identified HP30-2 both in chloroplasts and mitochondria, whereas HP30 was located exclusively in chloroplasts. Biochemical evidence was obtained for an association of mitochondrial HP30-2 with two distinct protein complexes, one containing the inner membrane translocase TIM22 and the other containing an alternative NAD(P)H dehydrogenase subunit (NDC1) implicated in a respiratory complex 1-like electron transport chain...
May 22, 2017: Journal of Integrative Plant Biology
https://www.readbyqxmd.com/read/28544475/thiazole-based-sigma-1-receptor-ligands-diversity-by-late-stage-c-h-arylation-of-thiazoles-structure-affinity-and-selectivity-relationships-and-molecular-interactions
#8
Bernhard Wünsch, Artur Kokornaczyk, Dirk Schepmann, Junichiro Yamaguchi, Kenichiro Itami, Erik Laurini, Maurizio Fermeglia, Sabrina Pricl
Spirocyclic thiophene derivatives represent promising sigma-1 ligands with high sigma-1 affinity and selectivity over the sigma-2 subtype. In order to increase ligand efficiency, the thiophene ring was replaced bioisosterically by a thiazole ring and the pyran ring was opened. Late-stage diversification by regioselective C-H arylation of thiazoles 9a-c resulted in a set of 53 compounds with high diversity. This set of compounds was analyzed with respect to sigma-1 affinity, sigma-1/sigma-2 selectivity, lipophilicity (logD7...
May 24, 2017: ChemMedChem
https://www.readbyqxmd.com/read/28544447/modulation-of-wetting-gradients-by-tuning-the-interplay-between-surface-structuration-and-anisotropic-molecular-layers-with-bipolar-electrochemistry
#9
Laurent Bouffier, Stéphane Reculusa, Valérie Ravaine, Alexander Kuhn
A new simple and versatile method for the preparation of surface wetting gradients is proposed. It is based on the combination of electrode surface structuration introduced by a sacrificial template approach and the formation of a tuneable molecular gradient by bipolar electrochemistry. The gradient involves the formation of a self-assembled monolayer on gold surface by selecting an appropriate thiol molecule and the subsequent reductive desorption by means of bipolar electrochemistry. Under these conditions, the completion of the reductive desorption process evolves along the bipolar surface with a maximum strength localized at the cathodic edge and a decreasing driving force toward the middle of the surface...
May 22, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28544199/benzhydryl-ethers-of-tartaric-acid-derivatives-stereochemical-response-of-dynamically-chiral-propeller
#10
Jakub Grajewski, Tomasz Mądry, Marcin Kwit, Beata Beata Warżajtis, Urszula Rychlewska, Jacek K Gawronski
The benzhydryl (diphenylmethyl) group is a molecular propeller that can acts as a chirality reporter when it is introduced nearby the stereogenic center by making the ether bond. Hydrophobic character of the benzhydryl group allows transformation of insoluble in non-polar environment natural tartaric acid derivatives into soluble entities. Electronic circular dichroism spectra, recorded within the short wavelength region of the phenyl 1B transitions (190-200 nm) showed strong bisignate Cotton effects. The signs and magnitudes of these Cotton effects are a function of absolute configuration and conformation of the molecule and primarily are not due to exciton coupling of chiral benzhydryl chromophores...
May 23, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28544090/functional-tuning-of-the-catalytic-residue-pka-in-a-de-novo-designed-esterase
#11
Katharina Hiebler, Zsófia Lengyel, Carlos A Castañeda, Olga V Makhlynets
AlleyCatE is a de novo designed esterase that can be allosterically regulated by calcium ions. This artificial enzyme has been shown to hydrolyze p-nitrophenyl acetate (pNPA) and 4-nitrophenyl-(2-phenyl)-propanoate (pNPP) with high catalytic efficiency. AlleyCatE was created by introducing a single histidine residue (His(144) ) into a hydrophobic pocket of calmodulin. In this work, we explore the determinants of catalytic properties of AlleyCatE. We obtained the pKa value of the catalytic histidine using experimental measurements by NMR and pH rate profile and compared these values to those predicted from electrostatics pKa calculations (from both empirical and continuum electrostatics calculations)...
May 24, 2017: Proteins
https://www.readbyqxmd.com/read/28544043/identification-of-v-type-nerve-agents-in-vapor-samples-using-a-field-portable-capillary-gas-chromatography-membrane-interfaced-electron-ionization-quadrupole-mass-spectrometry-instrument-with-tri-bed-concentrator-and-fluoridating-conversion-tube
#12
Yasuhiko Ohrui, Tomoki Nagoya, Naoko Kurimata, Manabu Sodeyama, Yasuo Seto
A field-portable gas chromatography-mass spectrometry (GC-MS) system (Hapsite ER) was evaluated for the detection of nonvolatile V-type nerve agents (VX and Russian VX (RVX)) in the vapor phase. The Hapsite ER system consists of a Tri-Bed concentrator gas sampler, a nonpolar low thermal-mass capillary gas chromatography column and a hydrophobic membrane-interfaced electron ionization quadrupole mass spectrometer evacuated by a non-evaporative getter pump. The GC-MS system was attached to a VX-G fluoridating conversion tube containing silver nitrate and potassium fluoride...
May 25, 2017: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/28544028/subcellular-compartmentation-interdependency-and-dynamics-of-the-cyclic-amp-dependent-pka-subunits-during-pathogenic-differentiation-in-rice-blast
#13
Poonguzhali Selvaraj, Tham Hong Fai, Ravikrishna Ramanujam, Naweed I Naqvi
The cAMP-dependent PKA signaling plays a central role in growth, asexual development and pathogenesis in fungal pathogens. Here, we functionally characterized RPKA, the regulatory subunit of cAMP/PKA and studied the dynamics and organization of the PKA subunits in the rice blast pathogen Magnaporthe oryzae. The RPKA subunit was essential for proper vegetative growth, asexual sporulation and surface hydrophobicity in M. oryzae. A spontaneous suppressor mutation, SMR19, that restored growth and conidiation in the RPKA deletion mutant was isolated and characterized...
May 20, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28544020/porous-poly-ionic-liquid-membranes-as-efficient-and-recyclable-absorbents-for-heavy-metal-ions
#14
Yongyuan Ren, Jiandong Zhang, Jiangna Guo, Fei Chen, Feng Yan
Heavy metal ion pollution has become a serious environmental problem. Herein, this study reports the synthesis of poly(ionic liquid) (PIL) membranes via in situ photo-crosslinking of vinyl imidazole with both hydrophilic and hydrophobic ionic liquid monomers. The resultant amphiphilic polymer membranes are porous and exhibit high absorption capacity of metal ions (including Hg(2+) , Pb(2+) , Cu(2+) , Cd(2+) , and Zn(2+) ) in both high (1000 mg L(-1) ) and low (10 mg L(-1) ) concentration metal ion solutions...
May 22, 2017: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/28543996/self-assembly-of-perylenediimide-single-strand-dna-conjugates-employing-hydrophobic-interactions-and-dna-base-pairing-to-create-a-diverse-structural-space
#15
Frederick Lewis, Ashutosh Kumar Mishra, Haim Weissman, Elisha Krieg, Kevin A Voltaw, Martin McCullagh, Boris Rybtchiinski
The self-assembly behavior of DNA conjugates possessing a perylenediimide (PDI) head group and a single N-oligonucleotide tail has been investigated using a combination of optical spectroscopy and cryogenic transmission electron microscopy (cryo-TEM) imaging. In order to obtain insight into the interplay between DNA base pairing and PDI hydrophobic interactions we employed systematic variation in the length and composition of the oligo tails. Conjugates with short (TA)n or (CG)n oligo tails (n ≤ 3) form fibers (helical or nonhelical) constructed from -stacked PDI head groups with pendent oligo tails at room temperature in aqueous solution...
May 24, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28543992/surface-modification-of-two-dimensional-metal-organic-layers-creates-biomimetic-catalytic-microenvironments-for-selective-oxidation
#16
Wenjie Shi, Lingyun Cao, Hua Zhang, Xin Zhou, Bing An, Zekai Lin, Ruihan Dai, Jianfeng Li, Cheng Wang, Wenbin Lin
Microenvironments in enzymes play crucial roles in controlling the activities and selectivities of reaction centers. Herein we report the tuning of the catalytic microenvironments of metal-organic layers (MOLs), a two-dimensional version of metal-organic frameworks (MOFs) with thickness down to a monolayer, to control product selectivities. By modifying the secondary building units (SBUs) of MOLs with monocarboxylic acids such as gluconic acid, we successfully changed the hydrophobicity/hydrophilicity around the active sites and fine-tuned the selectivity in photocatalytic oxidation of tetrahydrofuran (THF) to exclusively afford butyrolactone (BTL), likely via prolonging residence time of reaction intermediates in the hydrophilic microenvironment of catalytic centers...
May 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28543088/3d-quantitative-structure-activity-relationship-and-docking-studies-of-coumarin-derivatives-as-tissue-kallikrein-7-inhibitors
#17
Xin Zheng, Mengxi He, Xiao Tan, Jun Zheng, Fangyu Wang, Sen Liu
OBJECTIVES: Kallikrein 7 (KLK7) is a secreted serine protease that plays important roles in skin desquamation and tumour progression, which makes it an attracting drug target. To guide the design of KLK7 inhibitors, a series of coumarin-based inhibitors were used to perform 3D-quantitative structure-activity relationship analysis. METHODS: 3D conformations of 37 inhibitors were generated and used to construct CoMFA and CoMSIA models. Then a complex model between the inhibitors and KLK7 was built with molecular docking...
May 23, 2017: Journal of Pharmacy and Pharmacology
https://www.readbyqxmd.com/read/28542493/the-in-vivo-structure-of-biological-membranes-and-evidence-for-lipid-domains
#18
Jonathan D Nickels, Sneha Chatterjee, Christopher B Stanley, Shuo Qian, Xiaolin Cheng, Dean A A Myles, Robert F Standaert, James G Elkins, John Katsaras
Examining the fundamental structure and processes of living cells at the nanoscale poses a unique analytical challenge, as cells are dynamic, chemically diverse, and fragile. A case in point is the cell membrane, which is too small to be seen directly with optical microscopy and provides little observational contrast for other methods. As a consequence, nanoscale characterization of the membrane has been performed ex vivo or in the presence of exogenous labels used to enhance contrast and impart specificity...
May 2017: PLoS Biology
https://www.readbyqxmd.com/read/28541666/unveiling-the-molecular-structure-of-pulmonary-surfactant-corona-on-nanoparticles
#19
Qinglin Hu, Xuan Bai, Guoqing Hu, Yi Y Zuo
The growing risk of human exposure to airborne nanoparticles (NPs) causes a general concern on the biosafety of nanotechnology. Inhaled NPs can deposit in the deep lung at which interacting with the pulmonary surfactant (PS). Despite the increasing study of nano-bio interactions, detailed molecular mechanisms by which inhaled NPs interact with the natural PS system remain unclear. Using coarse-grained molecular dynamics simulation, we studied the interaction between NPs and the PS system in the alveolar fluid...
May 25, 2017: ACS Nano
https://www.readbyqxmd.com/read/28541041/self-assembled-zno-nanoparticle-capsules-for-carrying-and-delivering-isotretinoin-to-cancer-cells
#20
Wei Zhao, Ji-Shi Wei, Peng Zhang, Jie Chen, Ji-Lie Kong, Lian-Hua Sun, Huan-Ming Xiong, Helmuth Möhwald
ZnO@polymer core-shell nanoparticles are assembled into novel capsule shells with diameters of about 100 nm to load isotretinoin (ISO) with a capacity as high as 34.6 wt %. Although ISO, a widely used drug for acne treatment, by itself is not suitable for treating cancer because of its hydrophobicity, our ZnO-ISO composite showed much stronger anticancer activity. The improved cytotoxicity is ascribed to the synergistic effects of the ZnO@polymer and ISO, where the ZnO@polymer helps in the accumulation of ISO in cancer cells on the one hand, and on the other hand, ISO is released completely through ZnO decomposition under acidic conditions of cancer cells...
May 25, 2017: ACS Applied Materials & Interfaces
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