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Michaël Hermoso, Benjamin Lefeuvre, Fabrice Minoletti, Marc de Rafélis
The formation of the coccolith biominerals by a group of marine algae (the Coccolithophores) offers fascinating research avenues both from the biological and geological sides. It is surprising how biomineralisation by a key phytoplanktonic group remains underconstrained, yet is influential on ocean alkalinity and responsible for the built up of our paleoclimatic archive over the last 200 Myrs. Here, we report two close relative coccolith taxa exhibiting substantial bioaccumulation of strontium: Scyphosphaera and Pontosphaera grown in the laboratory or retrieved from Pliocene sediments...
2017: PloS One
Salar Farhangi-Abriz, Neda Nikpour-Rashidabad
Salt toxicity of agricultural land is a natural phenomenon which is due to agricultural irrigation. This toxicity is harmful to crop productivity via increasing oxidative stress products. In a factorial controlled trial, four levels of lignite-enriched soil (soil lignite content: none, 50, 75 and 100 g kg(-1)) were exposed to three levels of soil salinity (0, 5 and 10 dS m(-1) NaCl). Then reactive oxygen species (ROS) generation (hydrogen peroxide and superoxide radical), lipid peroxidation, antioxidant enzymes activities (peroxidase, catalase and super oxide dismutase), proline, glycine betaine, soluble sugars and soluble protein contents of soybean plants were compared across different lignite concentration and saline toxicity...
October 12, 2017: Plant Physiology and Biochemistry: PPB
Markus Schmitt, Paul R Erickson, Kristopher McNeill
Excited triplet state chromophoric dissolved organic matter (3CDOM*) is a short-lived mixture of excited state species that plays important roles in aquatic photochemical processes. Unlike the study of triplet states of well-defined molecules, which are amenable to transient absorbance spectroscopy, the study of 3CDOM* is hampered by it being a complex mixture and its low average intersystem crossing quantum yield (ΦISC). This study is an alternative approach to investigating 3CDOM* using transient absorption laser spectroscopy...
October 16, 2017: Environmental Science & Technology
Indika K Hewavitharana, Stephanie L Brock
This study demonstrates that ligand-exchange of nanocrystals (NCs) is not always an innocuous process, but can lead to facile (room temperature) ion-exchange, depending on the surface crystal faceting. Rock salt PbTe NCs prepared as cubes with neutral facets undergo room-temperature ligand exchange with sulfide ions, whereas cuboctahedron-shaped particles with neutral {100} and polar {111} facets are transformed to PbS, driven by ion-exchange along the <111> direction. Likewise, cation-exchange (with Ag+) occurs rapidly for cuboctahedra, whereas cubes remain inert...
October 16, 2017: ACS Nano
Gennady Lavrenty Gutsev, Derrick Ampadu Boateng, Puru Jena, Katharine Moore Tibbetts
Using both mass spectrometry with intense femtosecond laser ionization and high-level computational methods, we have explored the structure and fragmentation patterns of dimethyl methylphosphonate (DMMP) cation. Extensive search of the geometries of both neutral and positively charged DMMP yields new isomers that are appreciably lower in total energy than those commonly synthesized using the Michaelis-Arbuzov reaction. The stability of the standard isomer with CH3PO(OCH3)2 topology is found to be due to the presence of high barriers to isomer interconversion that involves several transition states...
October 16, 2017: Journal of Physical Chemistry. A
Stefan Holler, Michael Tüchler, Michaela C Roschger, Ferdinand Belaj, Luis F Veiros, Karl Kirchner, Nadia C Mösch-Zanetti
A novel selenium-containing pyridazinyl-based soft scorpionate ligand (KTnse) was synthesized. It reacts with CoCl2 and NiCl2, yielding the first metallaboratrane complexes with selenium in their donor positions. Further substitution with Ag(OTf) or NaN3 allows isolation of the respective triflate or azide complexes. Reaction with Ag(OTf) leads in the case of nickel to a dinuclear, dicationic complex with a short Ni-Ni distance, while cobalt gave a mononuclear cationic species. Substitution of the chloride by azide yields with both metals the respective azide complexes...
October 16, 2017: Inorganic Chemistry
Christopher Hassenrück, Rainer F Winter
Triarylamine-vinylruthenium conjugates (4-RC6H4)2N{C6H4-4-CH═CHRu(CO)Cl(P(i)Pr3)2}, with R = CHO (1-CHO), C(═O)Me (1-Ac), COOMe (1-E), and Me (1-Me), have been prepared and investigated in their neutral, mono- and dioxidized states by cyclic voltammetry, IR, and UV/vis/near-infrared spectroelectrochemistry, electron paramagnetic resonance spectroscopy, and quantum-chemical calculations. Electron-withdrawing substituents at the triarylamine moiety shift the charge and spin density toward the more electron-rich vinylruthenium site in comparison to the 4-OMe-substituted triarylamine-vinylruthenium conjugate 1-OMe...
October 16, 2017: Inorganic Chemistry
Matthew Ryan Preiss, Eily Cournoyer, Karissa L Paquin, Elizabeth A Vuono, Kayla Belanger, Edward Walsh, Niall George Howlett, Geoffrey D Bothun
We present an approach to tune the multifunctionality of iron oxide nanoparticles (IONs) using mixed self-assembled monolayers of cationic lipid and anionic polyethylene glycol (PEG) lipid. By forming stable, monodispersed lipid coated IONs (L-IONs) through a solvent exchange technique, we were able to demonstrate the relationship between surface charge, the magnetic transverse relaxivity (r2 from T2 weighted images), and the binding capacity of small interfering ribonucleic acids (siRNAs) as a function of the cationic/anionic (PEG) lipid ratio...
October 16, 2017: Bioconjugate Chemistry
Yu Liang, Hao Ding, Sijia Sun, Ying Chen
Activated sericite was prepared by thermal modification, acid activation and sodium modification, and it was characterized by X-ray diffraction (XRD) analysis, differential scanning calorimetry (DSC), N₂ adsorption test, thermo-gravimetric analysis (TGA), nuclear magnetic resonance (NMR), and scanning electron microscope (SEM). The results indicated that the crystallinity of raw sericite decreased after thermal modification; the pores with sizes between 5 nm to 10 nm of thermal-modified sericite have collapsed and the surface area increased after thermal modification...
October 16, 2017: Materials
Xiaolu Wang, Mengjia Liu, Yuqing Wang, Hongyan Fan, Jie Wu, Chao Huang, Hongwei Hou
To develop coordination polymers (CPs) as catalysts to selectively catalyze the reaction of C-H bond activation of arylalkanes to their homologous ketones, three new Cu(I)-based coordination polymers (Cu(I)-CPs) [CuI(aas-TPB)]n (1), [CuBr(ass-TPB)CH3CN]n (2), and {[Cu(ass-TPB)]Cl}n (3) (TPB = N,N,N-tris(3-pyridinyl)-1,3,5-benzenetricarboxamide) were synthesized. Structural variations from a herringbone fashion one-dimensional framework of 1 to a two-dimensional framework of 2 containing a 48-membered macrocycle and a cationic three-dimensional framework of 3 filled with Cl(-) anions were observed arising from the different halogen ions (I(-), Br(-), and Cl(-))...
October 16, 2017: Inorganic Chemistry
Ewa Daniela Raczynska, Jean-Francois Gal, Pierre-Charles Maria, Piotr Michalec, Marcin Zalewski
Substituted biguanides are known for their biological effect and a few of them are used as drugs, the most prominent example being metformin (1,1-dimethylbiguanide, IUPAC name: N,N-dimethylimidodicarbonimidic diamide). Owing to the presence of hydrogen atoms at the amino groups, biguanides exhibit a multiple tautomerism. This aspect of their structures was examined in detail for unsubstituted biguanide and metformin in the gas phase. At the DFT level {essentially B3LYP/6-311+G(d,p)}, the most stable structures correspond to the conjugated, push-pull, system (NR2)(NH2)C=N-C(=NH)NH2 (R= H, CH3), further stabilized by an internal hydrogen bond...
October 16, 2017: Journal of Physical Chemistry. A
Francesc Viñes, Gerasimos Konstantatos, Francesc Illas
The influence of cationic disorder on the electronic structure of ternary compounds, here exemplified on AgBiS2 material, is studied by means of accurate first principles periodic density functional theory based calculations. For AgBiS2 cationic disorder in going from semiconducting matildite to a metallic arrangement crystal structure is found to induce a significant decrease in the band gap, as a result of cation-disorder conduction band tail states penetrating into the matildite bandgap. Properly aligned conduction band minimum and valence band maximum show that cationic disorders lead to a noticeable drop of the former and a slight increase of the latter...
October 16, 2017: Physical Chemistry Chemical Physics: PCCP
Rui-Huan Duan, Peng-Fei Liu, Hua Lin, Shang-Xiong Huangfu, Li-Ming Wu
The desirable development of infrared nonlinear optical (IR NLO) materials is to design new compounds which exhibit wide band gaps and strong second harmonic generation (SHG) responses. Herein, we report three new sulfides, Ba4Ga4SnS12 (1), Ba12Sn4S23 (2) and Ba7Sn3S13 (3), with wide band gaps of 2.90, 2.98 and 3.0 eV, respectively, which have been successfully synthesized for the first time. Significantly, compound 1 exhibited a large SHG coefficient (34 × KDP), illustrating a good balance between the band gap and the SHG response...
October 16, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Xiaoni Fang, Yang Liu, Luis Jimenez, Yaokai Duan, Gary Brent Adkins, Liang Qiao, Baohong Liu, Wenwan Zhong
Nanomaterials have shown great promises in advancing biomedical and environmental analysis because of the unique properties originated from their ultrafine dimensions. In general, nanomaterials are separately applied to either enhance detection by producing strong signals upon target recognition; or to specifically extract analytes taking advantage of their high specific surface area. Herein, we report a dual-functional nanomaterial-based platform that can simultaneously enrich and enable sensitive detection of multiple metal ions...
October 16, 2017: Analytical Chemistry
Rocío Cuervo-Rodríguez, Fátima López-Fabal, José L Gómez-Garcés, Alexandra Muñoz-Bonilla, Marta Fernández-García
Herein, contact active antimicrobial films are prepared by simply blending cationic amphiphilic block copolymers with commercial polystyrene (PS). The copolymers are prepared by combining atom transfer radical polymerization and "click chemistry." A variety of copolymers are synthesized, and composed of a PS segment and an antimicrobial block bearing flexible side chain with thiazole and triazole groups, 4-(1-(2-(4-methylthiazol-5-yl)ethyl)-1H-1,2,3-triazol-4-yl) butyl methacrylate (TTBM). The length of the TTBM block is varied as well as the alkylating agent...
October 16, 2017: Macromolecular Bioscience
Marinella Mazzanti, Rory Kelly, Laurent Maron, Rosario Scopelliti
Organometallic multiple-decker sandwich complexes containing f-elements remain rare in spite of their attractive magnetic and electronic properties. The reduction of the CeIII siloxide complex, [KCeL4] (1; L = OSi(OtBu)3) with excess potassium in a THF/toluene mixture affords a rare tetradecker arene-bridged complex [K(2.2.2-crypt)]2[{(KL3Ce)(µ-η6:η6-C7H8)}2Ce] (3). The structure of 3 features a [Ce(C7H8)2] sandwich capped by [KL3Ce] moieties with a linear arrangement of the Ce ions. Structural parameters, UV-Vis data and DFT studies indicate the presence of CeII ions involved in δ bonding between the Ce cations and toluene dianions...
October 16, 2017: Angewandte Chemie
Neil Burford, Riccardo Suter, Christopher Frazee, Robert McDonald, Michael Ferguson
We present new cationic coordination complexes of antimony with the 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (DippBIAN) ligand system. The fluoroantimony complexes [SbF(DippBIAN)][OTf]2 and [SbF2(DippBIAN)][OTf] have been successfully isolated and characterized. The fluorine substituent in the Lewis acidic complex [SbF(DippBIAN)][OTf]2 can be selectively replaced without degradation of the Sb-DippBIAN interaction to give the first dicationic azido and cyano derivatives, [Sb(CN)(DippBIAN)][OTf]2 and [Sb(N3)(DippBIAN)][OTf]2, which have been isolated and structurally characterized...
October 15, 2017: Chemistry: a European Journal
Neil Burford, Maximillian Poller, Konstantin Karaghiosoff
Salts of diphosphoniumdiselenide dications ([R3PSeSePR3][OTf]2) have been isolated from reactions of trialkylphosphine selenides with triphenylantimony bistriflate. The redox process is speculated to proceed via a cationic coordination complex [Ph3SbL2][OTf]2 (L = Me3PSe, iPr3PSe), which is also formed in the reaction of [R3PSeSePR3][OTf]2 with Ph3Sb. The observations indicate that the reductive elimination of [R3PSeSePR3]2+ from [Ph3Sb(SePR3)2]2+ is reversible through the oxidative addition of [R3PSeSePR3]2+ to Ph3Sb...
October 16, 2017: Chemistry: a European Journal
Anne K Dettmar, Thorsten Wiech, Markus J Kemper, Armin Soave, Michael Rink, Jun Oh, Rolf A K Stahl, Elion Hoxha
BACKGROUND: Membranous nephropathy (MN) is a common cause of nephrotic syndrome in adults, but is less frequent in children. Antibodies against four antigens leading to MN have been described in children: phospholipase A2 receptor 1 (PLA2R1), thrombospondin type-1 domain-containing 7A (THSD7A), neutral endopeptidase (NEP), and cationic bovine serum albumin (BSA). METHODS: Twelve children with MN were included in this study. Sera of all patients were analyzed for antibodies against PLA2R1, THSD7A, NEP, and BSA...
October 15, 2017: Pediatric Nephrology: Journal of the International Pediatric Nephrology Association
Mathias Dimde, Falko Neumann, Felix Reisbeck, Svenja Ehrmann, Jose Luis Cuellar-Camacho, Dirk Steinhilber, Nan Ma, Rainer Haag
In the present study, a pH sensitive nanogel platform for gene delivery was developed. The cationic nanogels based on dendritic polyglycerol (dPG) and low molecular weight polyethylenimine units were able to encapsulate siRNA during the manufacturing process. The thiol-Michael nanoprecipitation method, which operates under mild conditions and did not require any catalyst or surfactant, was used to develop tailor-made nanogels in the sub-100 nm range. The incorporation of pH sensitive benzacetal-bonds inside the nanogel network enables the controlled intracellular release of the cargo...
October 16, 2017: Biomaterials Science
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