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https://www.readbyqxmd.com/read/28646738/the-effect-of-soil-properties-on-the-toxicity-and-bioaccumulation-of-ag-nanoparticles-and-ag-ions-in-enchytraeus-crypticus
#1
Emel Topuz, Cornelis A M van Gestel
Standard natural Lufa soils (2.2, 2.3 and 5M) with different organic carbon contents (0.67-1.61%) and pHCaCl2 (5.5-7.3) were spiked with ionic Ag (AgNO3) and polyvinyl pyrrolidone (AgNP-PVP) and citrate (AgNP-Cit) coated Ag nanoparticles (NPs). Enchytraeus crypticus were exposed for 21 days to assess effects on survival and reproduction. Soil, pore water and animals were analyzed for Ag. AgNP-Cit had a strong increasing effect on soil pH, leading to high enchytraeid mortality at concentrations higher than 60-100mg Ag/kg dry soil which made it impossible to determine the influence of soil properties on its toxicity...
June 21, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/28645036/influence-of-surface-states-on-blinking-characteristics-of-single-colloidal-cdse-cds-zns-core-multishell-quantum-dot
#2
Hao Xu, Hjalmar Brismar, Ying Fu
We carefully characterized the fluorescence blinking of single colloidal CdSe-CdS/ZnS core-multishell quantum dots (QDs) with different surface modifications, including octadecylamine (ODA) coated QDs dispersed in chloroform, aqueous 3-mercaptopropionic acids (3MPA) coated QDs in HEPES solution treated by Ca(2+) ions and ethylene glycol tetraacetic acid (EGTA, Ca(2+) chelator), and aqueous 3MPA-QDs treated by glycerol. It was found that the on- and off-state probability density distributions displayed different rules...
June 16, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28641142/optical-electrical-and-ferromagnetic-studies-of-zno-fe-diluted-magnetic-semiconductor-nanoparticles-for-spintronic-applications
#3
R Elilarassi, G Chandrasekaran
In the present investigation, diluted magnetic semiconductor (Zn1-xFexO) nanoparticles with different doping concentrations (x=0, 0.02, 0.04, 0.06, and 0.08) were successfully synthesized by sol-gel auto-combustion method. The crystal structure, morphology, optical, electrical and magnetic properties of the prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive analysis using x-rays (EDAX), ultraviolet-visible spectrophotometer, fluorescence spectroscope (FS), vibrating sample magnetometer (VSM) and broad band dielectric spectrometer (BDS)...
May 31, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28639558/exchange-interactions-in-transition-metal-oxides-the-role-of-oxygen-spin-polarization
#4
Remko Logemann, Alexander N Rudenko, Mikhail I Katsnelson, Andrei Kirilyuk
Magnetism of transition metal (TM) oxides is usually described in terms of the Heisenberg model, with orientation-independent interactions between the spins. However, the applicability of such a model is not fully justified for TM oxides because spin polarization of oxygen is usually ignored. In the conventional model based on the Anderson principle, oxygen effects are considered as a property of the TM ion and only TM interactions are relevant. Here, we perform a systematic comparison between two approaches for spin polarization on oxygen in typical TM oxides...
June 22, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28636347/the-structure-and-dynamics-of-alginate-gels-crosslinked-by-polyvalent-ions-probed-via-solid-state-nmr-spectroscopy
#5
Jiří Brus, Martina Urbanová, Jiri Czernek, Miroslava Pavelkova, Katerina Kubova, Jakub Vyslouzil, Sabina Abbrent, Rafal Konefal, Jiri Horsky, David Vetchy, Jan Vysloužil, Pavel Kulich
Alginate gels are an outstanding biomaterial widely applicable in tissue engineering, medicine, and pharmacy for cell transplantation, wound healing and efficient bioactive agent delivery, respectively. This contribution provides new and comprehensive insight into the atomic-resolution structure and dynamics of polyvalent ion-crosslinked alginate gels in microbead formulations. By applying various advanced solid-state NMR (ssNMR) spectroscopy techniques, we verified the homogenous distribution of the crosslinking ions in the alginate gels and the high degree of ion exchange...
June 21, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/28636332/new-insights-into-the-wavelength-dependence-of-maldi-mass-spectrometry
#6
Marcel Niehaus, Andreas Schnapp, Annika Koch, Jens Soltwisch, Klaus Dreisewerd
The interplay between the wavelength of the laser and the absorption profile of the matrix constitutes a crucial factor in matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). Numerous studies have shown that typically best analytical results are obtained if the laser wavelength matches the UV absorption band of the matrix in the solid state well. However, many powerful matrices exhibit peak absorptions which differ notably from the standard MALDI laser wavelengths of 337, 349, and 355 nm, respectively...
June 21, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28631243/amyloid-plaques-beyond-a%C3%AE-a-survey-of-the-diverse-modulators-of-amyloid-aggregation
#7
REVIEW
Katie L Stewart, Sheena E Radford
Aggregation of the amyloid-β (Aβ) peptide is strongly correlated with Alzheimer's disease (AD). Recent research has improved our understanding of the kinetics of amyloid fibril assembly and revealed new details regarding different stages in plaque formation. Presently, interest is turning toward studying this process in a holistic context, focusing on cellular components which interact with the Aβ peptide at various junctures during aggregation, from monomer to cross-β amyloid fibrils. However, even in isolation, a multitude of factors including protein purity, pH, salt content, and agitation affect Aβ fibril formation and deposition, often producing complicated and conflicting results...
June 19, 2017: Biophysical Reviews
https://www.readbyqxmd.com/read/28627548/tunable-photoluminescence-and-room-temperature-ferromagnetism-of-in2s3-dy-3-tb-3-nanoparticles
#8
Zhifang Li, Tianye Yang, Qi Zhao, Mingzhe Zhang
Trivalent lanthanide-doped luminescent nanomaterials have unique spectral and magnetic properties, which have been extensively investigated due to their potential application prospects in a number of new technologies. The rare earth Dy(3+) and Tb(3+) ions co-doped β-In2S3 dilute nanoparticles with different doping concentrations were successfully synthesized by a gas-liquid phase chemical deposition method. The band gap energy could be tuned by varying the doping concentration from 3.17 to 3.51 eV. The In2S3:Dy(3+),Tb(3+) nanoparticles exhibited strong photoluminescence emission peaks and room temperature ferromagnetism...
June 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28627547/probing-the-electronic-structure-of-a-copper-ii-complex-by-cw-and-pulse-epr-spectroscopy
#9
Zoi G Lada, Yiannis Sanakis, Catherine P Raptopoulou, Vassilis Psycharis, Spyros P Perlepes, George Mitrikas
Nucleophilic attack by the carbanion (-):CH2COCH3 at the carbonyl group of di-2-pyridyl ketone, (py)2CO, in the presence of Cu(II) under moderately basic conditions has yielded the cationic mononuclear complex [Cu{(py)2C(CH2COCH3)(OH)}2](NO3)2·2H2O (1·2H2O) in ∼40% yield, where (py)2C(CH2COCH3)(OH) is the ligand bis(2-pyridine-2-yl)butane-1-ol-3-one. The Cu(II) atom of the cation sits on a crystallographically imposed inversion center. The neutral molecule is coordinated to the metal ion as a tridentate fac chelating ligand through the hydroxyl oxygen atom and two 2-pyridyl nitrogen atoms...
June 19, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28626008/a-dual-role-for-the-osk5-2-ion-channel-in-stomatal-movements-and-k-loading-into-xylem-sap
#10
Thanh Hao Nguyen, Shouguang Huang, Donaldo Meynard, Christian Chaine, Rémy Michel, Rob Roelfsema, Emmanuel Guiderdoni, Herve Sentenac, Anne-Aliénor Véry
The roles of potassium channels from the Shaker family in stomatal movements have been investigated by reverse genetics analyses in Arabidopsis, but corresponding information is lacking outside this model species. Rice and other cereals possess stomata that are more complex than those of Arabidopsis. We examined the role of the outward Shaker K+ channel gene OsK5.2. Expression of the OsK5.2 gene (GUS reporter strategy) was observed in the whole stomatal complex (guard cells and subsidiary cells), in the root vasculature and root cortex...
June 16, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28625050/new-insight-into-the-chemical-nature-of-the-plasmonic-nanostructures-synthesized-by-reduction-of-au-iii-with-sulfide-species
#11
Maria Ana Huergo, Lisandro J Giovanetti, Mario Sergio Moreno, Christoph M Maier, Felix G Requejo, Roberto C Salvarezza, Carolina Vericat
We have studied the products of the controversial synthesis of HAuCl4 with Na2S, which include gold nanostructures (Au NSs) that absorb in the near-infrared (NIR) and are highly promising for photothermal therapies and other nanomedical applications. From high resolution transmission electron microscopy, X-ray absorption spectroscopy and small angle X-ray scattering we have found that only metallic gold nanostructures are formed as a result of this synthesis, with no detectable amount of gold sulfide or other oxidized gold species that could account for the NIR absorption...
June 18, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28613836/design-and-performance-of-a-novel-interface-for-combined-matrix-assisted-laser-desorption-ionization-at-elevated-pressure-and-electrospray-ionization-with-orbitrap-mass-spectrometry
#12
Mikhail E Belov, Shane R Ellis, Marialaura Dilillo, Martin R L Paine, William F Danielson, Gordon A Anderson, Eric L De Graaf, Gert B Eijkel, Ron M A Heeren, Liam A McDonnell
Matrix-Assisted Laser Desorption Ionization, MALDI, has been increasingly used in a variety of biomedical applications, including tissue imaging of clinical tissue samples, and in drug discovery and development. These studies strongly depend on the performance of the analytical instrumentation and would drastically benefit from improved sensitivity, reproducibility and mass / spatial resolution. In this work, we report on a novel combined MALDI/ESI interface, which was coupled to different Orbitrap mass spectrometers (Elite™ and Q Exactive™ Plus) and extensively characterized with peptide and protein standards, and in tissue imaging experiments...
June 14, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28612484/ph-sensing-properties-of-flexible-bias-free-graphene-microelectrodes-in-complex-fluids-from-phosphate-buffer-solution-to-human-serum
#13
Jinglei Ping, Jacquelyn E Blum, Ramya Vishnubhotla, Amey Vrudhula, Carl H Naylor, Zhaoli Gao, Jeffery G Saven, Alan T Charlie Johnson
Advances in techniques for monitoring pH in complex fluids can have a significant impact on analytical and biomedical applications. This study develops flexible graphene microelectrodes (GEs) for rapid (<5 s), very-low-power (femtowatt) detection of the pH of complex biofluids by measuring real-time Faradaic charge transfer between the GE and a solution at zero electrical bias. For an idealized sample of phosphate buffer solution (PBS), the Faradaic current is varied monotonically and systematically with the pH, with a resolution of ≈0...
June 14, 2017: Small
https://www.readbyqxmd.com/read/28612342/effect-of-glycine-nitrogen-on-lettuce-growth-under-soilless-culture-a-metabolomics-approach-to-identify-the-main-changes-occurred-in-plant-primary-and-secondary-metabolism
#14
Xiao Yang, Lei Feng, Li Zhao, Xiaosong Liu, Danial Hassani, Danfeng Huang
BACKGROUND: Lettuce is a significant source of antioxidants and bioactive compounds. Nitrate is a cardinal fertilizer in horticulture and influences vegetable yield and quality; however, the negative effects of nitrate on the biosynthesis of flavonoids require further study. It is expected that using fertilizers containing organic N could promote the synthesis of health-promoting compounds. RESULTS: Lettuces were hydroponically cultured in media containing 9 mM nitrate or 9 mM glycine for 4 weeks...
June 14, 2017: Journal of the Science of Food and Agriculture
https://www.readbyqxmd.com/read/28609093/disilicate-assisted-iron-electrolysis-for-sequential-fenton-oxidation-and-coagulation-of-aqueous-contaminants
#15
Jiaxin Cui, Xu Wang, Jing Zhang, Xiaoyu Qiu, Dihua Wang, Ying Zhao, Beidou Xi, Akram Alshawabkeh, Xuhui Mao
Sodium disilicate (SD), an inorganic and environmentally friendly ligand, is introduced into the conventional iron electrolysis system to achieve an oxidizing Fenton process to degrade organic pollutants. Electrolytic ferrous ions, which are complexed by the disilicate ions, can chemically reduce dioxygen molecules via consecutive reduction steps, producing H2O2 for the Fenton-oxidation of organics. At the near-neutral pH (from 6 to 8), the disilicate-Fe(II) complexes possess strong reducing capabilities; therefore, a near-neutral pH rather than an acid condition is preferable for the disilicate-assisted iron electrolysis (DAIE) process...
June 13, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28603966/silver-alginate-hydrogel-micro-and-nano-containers-for-theranostics-synthesis-encapsulation-remote-release-and-detection
#16
Ekaterina Lengert, Mariia Saveleva, Anatolii Abalymov, Vsevolod Atkin, Pieter C Wuytens, Roman Kamyshinsky, Alexander L Vasiliev, Dmitry A Gorin, Gleb B Sukhorukov, Andre G Skirtach, Bogdan Parakhonskiy
We have designed multifunctional silver alginate hydrogel microcontainers referred to as loaded microcapsules with different sizes by assembling them via a template assisted approach using a natural, highly porous calcium carbonate cores. Sodium alginate was immobilized into the pores of calcium carbonate particles of different sizes followed by cross-linking via addition of silver ions, which had a dual purpose: on one hand, the were used as a crosslinking agent, albeit in the monovalent form, while on the other hand they have led to formation of silver nanoparticles...
June 12, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28593204/steering-patchy-particles-using-multivalent-electrolytes
#17
Alexei I Abrikosov, Björn Stenqvist, Mikael Lund
Proteins and many recently designed colloids can be regarded as patchy particles where directional interactions strongly influence and govern assembly behavior. Using explicit ion implicit solvent Metropolis Monte Carlo simulations, we investigate spherical model particles, carrying both charge and electric patches, in dilute aqueous 1 : 1, 1 : 3, and 3 : 1 electrolyte solutions. Striking differences in pair interaction free energies and orientational correlations are induced by three different salts which are discussed and rationalized in terms of ion-binding to surface groups, ion-ion correlations, and double layer forces...
June 8, 2017: Soft Matter
https://www.readbyqxmd.com/read/28591602/configurational-preference-of-the-glutamate-receptor-ligand-binding-domain-dimers
#18
Michael Yonkunas, Maiti Buddhadev, Jose C Flores Canales, Maria G Kurnikova
Ionotropic glutamate receptors are a family of tetrameric ion channels with functional states consisting of nonconducting, conducting, and desensitized states that are starting to become well characterized by electrophysiological and biophysical studies. However, the structure and relative energetics of these states beyond the general structure of the receptor are still not well understood. It is known that the interface between monomeric subunits of the tetramer plays a major role in distinguishing these functional states...
June 6, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28590526/gas-phase-fragmentation-of-1-adamantylbisimidazolium-salts-and-their-complexes-with-cucurbit-7-uril-studied-using-selectively-2-h-labeled-guest-molecules
#19
Andrea Čablová, Michal Rouchal, Barbora Hanulíková, Jan Vícha, Lenka Dastychová, Zdeňka Prucková, Robert Vícha
RATIONALE: Bisimidazolium salts (BIMs) represent an interesting family of ditopic ligands that are used in the construction of supramolecular systems with hosts based on cyclodextrins or cucurbit[n]urils. Understanding the fragmentation mechanism of individual BIMs and how this mechanism changes after complexation with cucurbit[n]urils can bring new insight into the intrinsic host-guest relationship, thereby allowing utilization of mass spectrometry to describe binding behavior. METHODS: Selectively (2) H-labeled bisimidazolium salts were prepared and fully characterized by spectroscopic methods...
June 7, 2017: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28589973/the-effect-of-a-membrane-mimicking-environment-on-the-interactions-of-cu-2-with-an-amyloidogenic-fragment-of-chicken-prion-protein
#20
Aleksandra Hecel, Sara Draghi, Daniela Valensin, Henryk Kozlowski
Prion proteins (PrP) from different species have the ability to tightly bind Cu(2+) ions. Copper coordination sites are located in the disordered and flexible N-terminal region which contains several His anchoring sites. Among them, two His residues are found in the so called amyloidogenic PrP region which is believed to play a key role in the process leading to oligomer and fibril formation. Both chicken and human amyloidogenic regions have a hydrophobic C-terminal region rich in Ala and Val amino acids. Recent findings revealed that this domain undergoes random coil to α-helix structuring upon interaction with membrane models...
June 7, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
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