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https://www.readbyqxmd.com/read/28731301/lead-ii-complexes-of-amino-acids-peptides-and-other-related-ligands-of-biological-interest
#1
Etelka Farkas, Péter Buglyó
Lead(II) forms (NH2,COO-)-chelated mono- and bis-complexes with simple amino acids, while mono-complexes with pH-dependent coordination modes exist with simple dipeptides. These mostly hemidirected complexes have moderate stability. While a weak interaction of side chain imidazole and carboxylate in lead(II)-aminoacidato complexes is found, the thiolate group has an exceptionally high affinity to this metal ion. For example, tridentate (NH2,COO-,S-)-coordination of penicillamine (Pen) and cysteine (Cys) results in an extremely strong interaction with lead(II), but, owing to the sterical effect of the 6s2 pair, a second ligand is not able to coordinate in the above mentioned tridentate way...
April 10, 2017: Metal Ions in Life Sciences
https://www.readbyqxmd.com/read/28729521/influence-of-block-copolymer-feature-size-on-reactive-ion-etching-pattern-transfer-into-silicon
#2
Masoud Dialameh, Federico Ferrarese Lupi, Dario Imbraguglio, Fabio Zanenga, Alessio Lamperti, Davide Martella, Gabriele Seguini, Michele Perego, Andrea Mario Rossi, Natascia De Leo, Luca Boarino
A successful realization of sub 20 nm features on silicon is becoming the focus of many technological studies, strongly influencing the future performance of modern integrated circuits. Although reactive ion etching (RIE), at both micrometric and nanometric scale has already been the target of many studies, a better understanding of the different mechanisms involved at sub 20 nm size etching is still required. In this work, we investigated the influence of the feature size on etch rate of silicon, performed by Cryogenic RIE process through cylinder-forming polystyrene-block-polymethilmetacrhlate (PS-b-PMMA) DiBlock Copolymers (DBCs) masks with diameter ranging between 19 and 13 nm...
July 21, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28727426/fully-atomistic-a%C3%AE-40-and-a%C3%AE-42-oligomers-in-water-observation-of-pore-like-conformations
#3
Matthew John Voelker, Bogdan Barz, Brigita Urbanc
Oligomers formed by amyloid β-protein (Aβ) are central to Alzheimer's disease (AD) pathology, yet their structure remains elusive. Of the two predominant Aβ alloforms, Aβ40 and Aβ42, the latter is more strongly associated with AD. Here, we structurally characterized Aβ40 and Aβ42 monomers through pentamers which were converted from previously derived coarse-grained (DMD4B-HYDRA) simulations into all-atom conformations and subjected to explicit-solvent MD. Free energy landscapes revealed that structural differences between Aβ40 and Aβ42 conformations increase with oligomer order up to trimers...
July 20, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28726901/on-the-capacitance-of-narrow-nanotubes
#4
Wolfgang Schmickler, Douglas Henderson
The storage of ions in narrow nanotubes is investigated by grand-canonical Monte Carlo simulations. The interaction between the ions is screened by the image charge on the wall of the tube, but at close distances it is still much larger than the thermal energy. Depending on the electrochemical potential imposed by the contact with an electrolyte solution, two different regimes can be distinguished at the potential of zero charge: for low values corresponding to an ionophobic pore the tube is almost empty; for high values - ionophilic pore - a one dimensional salt is formed...
July 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28723154/interruption-of-hydrogen-bonding-networks-of-water-in-carbon-nanotubes-due-to-strong-hydration-shell-formation
#5
Yoshifumi Oya, Kenji Hata, Tomonori Ohba
We present the structures of NaCl aqueous solution in carbon nanotubes with diameters of 1, 2, and 3 nm based on an analysis performed using X-ray diffraction and canonical ensemble Monte Carlo simulations. Anomalously longer nearest-neighbor distances were observed in the electrolyte for the 1-nm-diameter carbon nanotubes; in contrast, in the 2 and 3 nm carbon nanotubes, the nearest-neighbor distances were shorter than those in the bulk electrolyte. We also observed similar properties for water in carbon nanotubes, which was expected because the main component of the electrolyte was water...
July 19, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28720500/essential-slow-degrees-of-freedom-in-protein-surface-simulations-a-metadynamics-investigation
#6
Arushi Prakash, K G Sprenger, Jim Pfaendtner
Many proteins exhibit strong binding affinities to surfaces, with binding energies much greater than thermal fluctuations. When modelling these protein-surface systems with classical molecular dynamics (MD) simulations, the large forces that exist at the protein/surface interface generally confine the system to a single minimum. Exploring the full conformational space of the protein, especially finding other stable structures, becomes prohibitively expensive. Coupling MD simulations with metadynamics (enhanced sampling) has fast become a common method for sampling the adsorption of such proteins...
July 15, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28715226/photoelectron-spectroscopic-and-computational-study-of-pyridine-ligated-gold-cluster-anions
#7
Gaoxiang Liu, Sandra M Ciborowski, Kit Hansell Bowen
Pyridine-ligated gold cluster anions were studied through a combination of negative ion photoelectron spectroscopy and density functional theory calculations. Small gold cluster anions ligated by pyridine, Aun(py) were generated with a ligation cell coupled to a laser vaporization source (LVS). We showed that pyridine is weakly bound (physisorbed) to the Au2(-) moiety of Au2(py)(-) by interactions between its gold atoms and either the hydrogen atoms or the π-ring of pyridine. We also found that pyridine's lone electron pair strongly binds (chemisorbs) to both Au3(py)(-) and Au4(py)(-) through single gold atoms on each of these clusters...
July 17, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28714253/an-off-on-off-type-fluorescent-probe-based-on-a-naphthalene-derivative-for-al-3-and-f-ions-and-its-biological-application
#8
Yanpeng Ren, Juan Han, Yun Wang, Xu Tang, Lei Wang, Liang Ni
A novel fluorescent probe-based naphthalene Schiff, 1-(C2-glucosyl-ylimino-methyl)-naphthalene-2-ol (L) was synthesized by coupling d-glucosamine hydrochloride with 2-hydroxy-1-naphthaldehyde. It exhibited excellent selectivity and highly sensitivity for Al(3+) in ethanol with a strong fluorescence response, while other common metal ions such as Pb(2+) , Mg(2+) , Cu(2+) , Co(2+) , Ni(2+) , Cd(2+) , Fe(2+) , Mn(2+) , Hg(2+) , Li(+) , Na(+) , K(+) , Fe(3+) , Cr(3+) , Zn(2+) , Ag(+) , Ba(2+) and Ca(2+) did not cause the same fluorescence response...
July 17, 2017: Luminescence: the Journal of Biological and Chemical Luminescence
https://www.readbyqxmd.com/read/28707452/on-the-dimensional-control-of-2d-hybrid-nanomaterials
#9
Alessandro Longo, Dirk-Jan Mulder, Huub P C van Kuringen, Daniel Hermida-Merino, Dipanjan Banerjee, Debarshi Dasgupta, Ivelina K Shishmanova, Anne B Spoelstra, Dirk J Broer, Albert P H J Schenning, Giuseppe Portale
Thermotropic smectic liquid crystalline polymers were used as a scaffold to create organic/inorganic hybrid layered nanomaterials. Different polymers were prepared by photopolymerizing blends of a hydrogen bonded carboxylic acid derivative and a 10% cross-linker of variable length in their liquid crystalline phase. Nanopores with dimensions close to 1 nm were generated by breaking the hydrogen bonded dimers in a high pH solution. The pores were filled with positively charged silver (Ag) ions, resulting in a layered silver(I)-polymeric hybrid material...
July 13, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28703340/core-satellite-polydopamine-gadolinium-metallofullerene-nanotheranostics-for-multimodal-imaging-guided-combination-cancer-therapy
#10
Sheng Wang, Jing Lin, Zhantong Wang, Zijian Zhou, Ruiliang Bai, Nan Lu, Yijing Liu, Xiao Fu, Orit Jacobson, Wenpei Fan, Junle Qu, Siping Chen, Tianfu Wang, Peng Huang, Xiaoyuan Chen
Integration of magnetic resonance imaging (MRI) and other imaging modalities is promising to furnish complementary information for accurate cancer diagnosis and imaging-guided therapy. However, most gadolinium (Gd)-chelator MR contrast agents are limited by their relatively low relaxivity and high risk of released-Gd-ions-associated toxicity. Herein, a radionuclide-(64) Cu-labeled doxorubicin-loaded polydopamine (PDA)-gadolinium-metallofullerene core-satellite nanotheranostic agent (denoted as CDPGM) is developed for MR/photoacoustic (PA)/positron emission tomography (PET) multimodal imaging-guided combination cancer therapy...
July 13, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28699758/resilience-of-malic-acid-natural-deep-eutectic-solvent-nanostructure-to-solidification-and-hydration
#11
Oliver S Hammond, Daniel Timothy Bowron, Andrew J Jackson, Thomas Arnold, Adrian Sanchez-Fernandez, Nikolaos Tsapatsaris, Victoria Garcia Sakai, Karen J Edler
Little is presently known about the unique nanostructure of Deep Eutectic Solvents (DES). The order of the liquid-solid phase transition is contended and whether DES-water mixtures are merely aqueous solutions, or have properties dominated by the eutectic pair, is unclear. Here, we unambiguously show the structure of choline chloride-malic acid (malicine) as a liquid, and also in solid and hydrated forms, using neutron total scattering on D/H isotope-substituted samples, and quasi-elastic neutron scattering (QENS)...
July 12, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28699523/altered-homeostatic-functions-in-reactive-astrocytes-and-their-potential-as-a-therapeutic-target-after-brain-ischemic-injury
#12
Helena Pivonkova, Miroslava Anderova
Brain ischemic injury represents one of the greatest medical challenges for the aging population in developed countries, yet despite strong efforts, possibilities to treat ischemic injury still remain poor. Stroke, the most common type of brain ischemic injury in humans, is caused by brain artery occlusion, and represents a focal form of ischemia, which leads to neuronal loss in the ischemic core, and glial scar formation in the penumbral region around the core. Such glial scar mainly comprises reactive astrocytes, reactive NG2 glia and activated microglia...
July 10, 2017: Current Pharmaceutical Design
https://www.readbyqxmd.com/read/28698651/ion-concentration-polarization-by-bifurcated-current-path
#13
Junsuk Kim, Inhee Cho, Hyomin Lee, Sung Jae Kim
Ion concentration polarization (ICP) is a fundamental electrokinetic process that occurs near a perm-selective membrane under dc bias. Overall process highly depends on the current transportation mechanisms such as electro-convection, surface conduction and diffusioosmosis and the fundamental characteristics can be significantly altered by external parameters, once the permselectivity was fixed. In this work, a new ICP device with a bifurcated current path as for the enhancement of the surface conduction was fabricated using a polymeric nanoporous material...
July 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28698586/sensitization-energy-transfer-and-infra-red-emission-decay-modulation-in-yb-3-doped-nayf4-nanoparticles-with-visible-light-through-a-perfluoroanthraquinone-chromophore
#14
Haizhou Lu, Yu Peng, Huanqing Ye, Xianjin Cui, Jianxu Hu, Hang Gu, Andrei N Khlobystov, Mark A Green, Philip J Blower, Peter B Wyatt, William P Gillin, Ignacio Hernández
Infra-red emission (980 nm) of sub 10 nm Yb(3+)-doped NaYF4 nanoparticles has been sensitized through the excitation of 2-hydroxyperfluoroanthraquinone chromophore (1,2,3,4,5,6,7-heptafluro-8-hydroxyanthracene-9,10-dione) functionalizing the nanoparticle surface. The sensitization is achieved with a broad range of visible light excitation (400-600 nm). The overall near infra-red (NIR) emission intensity of Yb(3+) ions is increased by a factor 300 as a result of the broad and strong absorption of the chromophore compared with ytterbium's intrinsic absorption...
July 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28696706/large-differences-in-the-optical-spectrum-associated-with-the-same-complex-the-effect-of-the-anisotropy-of-the-embedding-lattice
#15
José Antonio Aramburu, Pablo García-Fernández, Juan María García-Lastra, Miguel Moreno
Transition-metal complexes with a well-defined geometry are usually considered to display almost the same properties independently of the system where they are embedded. Here we show that the above statement is not true depending on the anisotropy of the host lattice, which is revealed in the form of the electric field created by the rest of lattice ions over the complex. To illustrate this concept we analyze the origin of the surprisingly large differences in the d-d optical transitions of two systems containing square-planar CuF4(2-) complexes, CaCuF4, and center II in Cu(2+)-doped Ba2ZnF6, even though the Cu(2+)-F(-)distance difference is just found to be 1%...
July 11, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28695858/rapid-cadmium-sad-phasing-at-the-standard-wavelength-1%C3%A2-%C3%A3
#16
Saravanan Panneerselvam, Esa Pekka Kumpula, Inari Kursula, Anja Burkhardt, Alke Meents
Cadmium ions can be effectively used to promote crystal growth and for experimental phasing. Here, the use of cadmium ions as a suitable anomalous scatterer at the standard wavelength of 1 Å is demonstrated. The structures of three different proteins were determined using cadmium single-wavelength anomalous dispersion (SAD) phasing. Owing to the strong anomalous signal, the structure of lysozyme could be automatically phased and built using a very low anomalous multiplicity (1.1) and low-completeness (77%) data set...
July 1, 2017: Acta Crystallographica. Section D, Structural Biology
https://www.readbyqxmd.com/read/28695314/bacterial-production-and-reconstitution-in-proteoliposomes-of-solanum-lycopersicum-cat2-a-transporter-of-basic-amino-acids-and-organic-cations
#17
Teresa Maria Rosaria Regina, Michele Galluccio, Mariafrancesca Scalise, Lorena Pochini, Cesare Indiveri
The vacuolar SlCAT2 was cloned, over-produced in E. coli and reconstituted in proteoliposomes. Arg, Ornithine and Lys were identified as substrates. Unexpectedly, also the organic cations Tetraethylammonium and Acetylcholine were transported indicating involvement of SlCAT2 in signaling. In land plants several transporters are involved in ion and metabolite flux across membranes of cells or intracellular organelles. The vacuolar amino acid transporter CAT2 from Solanum lycopersicum was investigated in this work...
July 10, 2017: Plant Molecular Biology
https://www.readbyqxmd.com/read/28693731/simple-area-determination-of-strongly-overlapping-ion-mobility-peaks
#18
Lucie Borovcová, Martina Hermannová, Volodymyr Pauk, Matěj Šimek, Vladimír Havlíček, Karel Lemr
Coupling of ion mobility with mass spectrometry has brought new frontiers in separation and quantitation of a wide range of isobaric/isomeric compounds. Ion mobility spectrometry may separate ions possessing the identical molecular formula but having different molecular shapes. The separation space in most commercially available instruments is limited and rarely the mobility resolving power exceeds one hundred. From this perspective, new approaches allowing for extracting individual compound signals out of a more complex mixture are needed...
August 15, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28693594/the-impact-of-phosphate-balanced-crystalloid-infusion-on-acid-base-homeostasis-palance-study-study-protocol-for-a-randomized-controlled-trial
#19
Judith-Irina Pagel, Nikolai Hulde, Tobias Kammerer, Michaela Schwarz, Daniel Chappell, Alexander Burges, Klaus Hofmann-Kiefer, Markus Rehm
BACKGROUND: This study aims to investigate the effects of a modified, balanced crystalloid including phosphate in a perioperative setting in order to maintain a stable electrolyte and acid-base homeostasis in the patient. METHODS/DESIGN: This is a single-centre, open-label, randomized controlled trial involving two parallel groups of female patients comparing a perioperative infusion regime with sodium glycerophosphate and Jonosteril® (treatment group) or Jonosteril® (comparator) alone...
July 10, 2017: Trials
https://www.readbyqxmd.com/read/28691724/gas-phase-hydration-of-halogenated-benzene-cations-is-it-hydrogen-or-halogen-bonding
#20
Kyle A Mason, Adam C Pearcy, Isaac K Attah, Sean P Platt, Saadullah G Aziz, M Samy El-Shall
Halogen bonding (XB) non-covalent interactions can be observed in compounds containing chlorine, bromine, or iodine which can form directed close contacts of the type R1-XY-R2, where the halogen X acts as a Lewis acid and Y can be any electron donor moiety including electron lone pairs on hetero atoms such as O and N, or π electrons in olefin double bonds and aromatic conjugated systems. In this work, we present the first evidence for the formation of ionic halogen bonds (IXBs) in the hydration of bromobenzene and iodobenzene radical cations in the gas phase...
July 10, 2017: Physical Chemistry Chemical Physics: PCCP
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