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Molecular adsorbant

Aparecido Nivaldo Módenes, Ana Paula de Oliveira, Fernando R Espinoza-Quiñones, Daniela Estelita Goes Trigueros, Alexander Dimitrov Kroumov, Rosângela Bergamasco
Removal of Cr(VI) species by dried biomass of the aquatic macrophyte Salvinia auriculata was studied in order to understand the involved sorption mechanisms. Kinetic tests were carried out under the conditions such as concentration range of Cr(VI) from 50 to 250 mg L(-1) and a temperature of 30 °C. Modification of the biosorbent by the presence of Cr(VI) species was assessed by analysis of its porosity, density and infrared molecular absorption spectrum. A series of experimental approaches involving directed chemical modifications on the biosorbent surface was performed...
January 5, 2017: Chemosphere
Hiroshi Yoke, Chikako Shingyoji
Oscillatory bending movement of eukaryotic flagella is powered by orchestrated activity of dynein motor proteins that hydrolyze ATP and produce microtubule sliding. Although the ATP concentration within a flagellum is kept uniform at a few mmol l(-1) level, sliding activities of dyneins are dynamically coordinated along the flagellum in accordance with the phase of bending waves. Thus, at the organellar level the dynein not only generates force for bending but also modulates its motile activity by responding to bending of the flagellum...
January 13, 2017: Journal of Experimental Biology
Song Gu, Lijie Duan, Xiuyan Ren, Guang Hui Gao
Dual physically cross-linked hydrogels, which are triggered by cationic latexes as hydrophobic association and ionic crosslinking centers, were easily fabricated via a one-pot in situ polymerization method. First, the hydrophobic alkyl chains of hydrophobic monomers are adsorbed on the surface of latex microspheres and stabilized in the presence of surfactants, forming hydrophobic association centers as the first physical crosslinking points. Meanwhile, the anionic sulfate radicals dissociated by persulphate are attracted towards the cationic molecular chains of latex microspheres through ionic interactions, forming the secondary physical crosslinking centers, and initiate the copolymerization between acrylamide and hydrophobic vinyl monomers...
January 4, 2017: Journal of Colloid and Interface Science
Jung Seung Lee, Kyuri Kim, Joseph P Park, Seung-Woo Cho, Haeshin Lee
Titanium is the most biocompatible inorganic biomaterial with a long history of use in orthopedic and dental implants. However, promoting rapid and effective bone formation and integration onto etched, rough TiO2 surfaces has been a challenging topic. Here, 21 commercially available molecules are examined that met the following criteria: (1) contain phosphonic acid for stable immobilization onto TiO2 surfaces and (2) have a molecular weight less than 500 Da for negligible coating thickness. Of these molecules, the surface immobilization of pyridoxal 5'-phosphate (PLP), an active form of vitamin B6 , dramatically increases the hemophilic property of the surface and accelerated osteointegration in vivo...
January 12, 2017: Advanced Healthcare Materials
Konstantin S Smirnov
The interaction of water with the hydroxylated (010) surface of silicalite-1 was studied by classical molecular dynamics simulations. Interatomic interactions in the system were described using a set of effective potentials combining well-tested BKS and SPC models. The extended force field is shown to correctly reproduce the structural, energy, and dynamical characteristics of the silica surface OH groups. The interaction of water with the hydrophilic silanols leads to an ordering of H2O molecules in the vicinity of the surface...
January 12, 2017: Physical Chemistry Chemical Physics: PCCP
Zonglin Gu, Phil De Luna, Zaixing Yang, Ruhong Zhou
Molybdenum disulfide (MoS2) has recently emerged as a promising nanomaterial in a wide range of applications due to its unique and impressive properties. For example, MoS2 has gained attention in the biomedical field because of its ability to act as an antibacterial and anticancer agent. However, the potential influence of this exciting nanomaterial on biomolecules is yet to be extensively studied. Molecular dynamics (MD) simulations are invaluable tools in the examination of protein interactions with nanomaterials such as MoS2...
January 12, 2017: Physical Chemistry Chemical Physics: PCCP
Sangeetha Raman, Lukas Malms, Thomas Utzig, Buddha Ratna Shrestha, Philipp Stock, Shankar Krishnan, Markus Valtiner
Barnacles exhibit superior underwater adhesion simply through sequencing of the 21 proteinogenic amino acids, without post processing or using special amino acids. Here, we measure and discuss the molecular interaction of two distinct and recurring short peptide sequences (Bp1 and Bp2) inspired from the surface binding 19kDa protein from the barnacle attachment interface. Using self-assembled monolayer (SAMs) of known physical and chemical properties on molecularly smooth gold substrates in 5mM NaCl at pH 7...
December 26, 2016: Colloids and Surfaces. B, Biointerfaces
Pavel Marichal-Gallardo, Michael M Pieler, Michael W Wolff, Udo Reichl
Steric exclusion chromatography has been used for the purification of proteins and bacteriophages using monoliths. The operation is carried out by mixing a crude sample containing the target species with a predetermined concentration and molecular weight of polyethylene glycol (PEG) and loading it onto a non-reactive hydrophilic surface. Product capture occurs by the mutual steric exclusion of PEG between the product and the matrix. Selectivity is significantly influenced by target product size. Product elution is achieved by decreasing the PEG concentration...
December 29, 2016: Journal of Chromatography. A
Trong Pham, Raul Lobo, Matthew Hudson, Craig Brown
The CO2 adsorption properties of cation-exchanged Li-, Na-, K-, and Mg-ZK-5 zeolites are correlated to the molecular structures determined by Rietveld refinements of synchrotron powder X-ray diffraction patterns. Li-, K-, and Na-ZK-5 all exhibit high isosteric heats of adsorption (Qst) at low CO2 coverage, with Na-ZK-5 having the highest Qst (≈49 kJ/mol). Mg2+ is located at the center of the zeolite hexagonal prism, with the cation inaccessible to CO2, leading to a much lower Qst (≈30 kJ/mol) and lower overall uptake capacity...
January 9, 2017: ChemSusChem
Giacomo Levita, Maria C Righi
To date, no clear conclusion has been reached on the atomistic mechanisms that govern the observed decrease of lubricating capabilities of MoS2 in humid environments. Based on ab initio molecular dynamic calculations, we show that intercalated water molecules hinder the sliding motion of both regular and defective layers considerably, with the velocities decaying exponentially with time. However, in the presence of an applied load and exposed edge terminations, water is rapidly removed from the interface and is adsorbed on the edges either in undissociated form or as OH/H fragments...
January 9, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Miriam Candelaria Rodríguez González, Pilar Carro, Evangelina Pensa, Carolina Vericat, Roberto Salvarezza, Alberto Hernández Creus
The dynamics of the self-assembly process of thiol molecules on Au(111) is affected by the interplay between molecule-substrate and molecule-molecule interactions. Therefore, it is interesting to explore the effect of a second anchor to the gold surface, in addition to the S atom, on both the order and the feasibility of phase transitions in self-assembled monolayers. To assess the role of an additional O anchor, we have compared the adsorption of two mercaptobenzoic acid isomers, 2-mercaptobenzoic acid (2-MBA) and 4-mercaptobenzoic acid (4-MBA), on Au(111)...
January 9, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
P Capra, G Musitelli, P Perugini
OBJECTIVE: The aim of this work was to use the contact angle measurement in order to predict the behavior of ingredients and finished cosmetic products on skin to improve skin feel and product texture. METHOD: Different classes of cosmetic ingredients and formulations were evaluated. The contact angle measurements were carried out by the sessile drop methodusing an apparatus, designed and set up in laboratory. Glass, Teflon and human skin were the reference substrates...
January 9, 2017: International Journal of Cosmetic Science
C Lee, C Cottin-Bizonne, R Fulcrand, L Joly, C Ybert
The classical paradigm for osmotic transport has long related the induced-flow direction to the solute membrane interactions, with the low-to-high concentration flow a direct consequence of the solute rejection from the semipermeable membrane. In principle, the same was thought to occur for the newly demonstrated membrane-free osmotic transport named diffusio-osmosis. Using a recently proposed nanofluidic setup, we revisit this cornerstone of osmotic transport by studying the diffusio-osmotic flows generated at silica surfaces by either poly(ethylene)glycol polymers or ethanol molecules in aqueous solutions...
January 9, 2017: Journal of Physical Chemistry Letters
Sudi Jawahery, Cory M Simon, Efrem Braun, Matthew Witman, Davide Tiana, Bess Vlaisavljevich, Berend Smit
IRMOF-74 analogues are among the most widely studied metal-organic frameworks (MOFs) for adsorption applications because of their one-dimensional channels and high metal density. Most studies involving the IRMOF-74 series assume that the crystal lattice is rigid. This assumption guides the interpretation of experimental data, as changes in the crystal symmetry have so far been ignored as a possibility in the literature. Here, we report a deformation pattern, induced by the adsorption of argon, for IRMOF-74-V...
January 9, 2017: Nature Communications
A Bénarouche, L Sams, C Bourlieu, V Vié, V Point, J F Cavalier, F Carrière
The access to kinetic parameters of lipolytic enzyme adsorption onto lipids is essential for a better understanding of the overall catalytic process carried out by these interfacial enzymes. Gastric lipase, for instance, shows an apparent optimum activity on triglycerides (TAG) at acidic pH, which is controlled by its pH-dependent adsorption at lipid-water interfaces. Since gastric lipase acts on TAG droplets covered by phospholipids, but does not hydrolyze these lipids, phospholipid monolayers spread at the air-water interfaces can be used as biomimetic interfaces to study lipase adsorption and penetration through the phospholipid layer, independently from the catalytic activity...
2017: Methods in Enzymology
Jiri Pavelec, Jan Hulva, Daniel Halwidl, Roland Bliem, Oscar Gamba, Zdenek Jakub, Florian Brunbauer, Michael Schmid, Ulrike Diebold, Gareth S Parkinson
The adsorption of CO2 on the Fe3O4(001)-(2 × 2)R45° surface was studied experimentally using temperature programmed desorption (TPD), photoelectron spectroscopies (UPS and XPS), and scanning tunneling microscopy. CO2 binds most strongly at defects related to Fe(2+), including antiphase domain boundaries in the surface reconstruction and above incorporated Fe interstitials. At higher coverages,CO2 adsorbs at fivefold-coordinated Fe(3+) sites with a binding energy of 0.4 eV. Above a coverage of 4 molecules per (2 × 2)R45° unit cell, further adsorption results in a compression of the first monolayer up to a density approaching that of a CO2 ice layer...
January 7, 2017: Journal of Chemical Physics
Insup Lee, Seungbae Son, Taeho Shin, Jae R Hahn
The transition between two conformations of pyridine molecules adsorbed on a Ag(110) surface at 13 K was investigated by performing single-molecule manipulation at a very low coverage and the track-imaging of pyridines for various surface coverages using a variable low-temperature scanning tunneling microscope. A single tilted conformer was converted to an upright conformer when another coadsorbed tilted pyridine molecule approached to within ∼2 nm. The conversion probability depends on the molecular separation...
January 7, 2017: Journal of Chemical Physics
Vanessa J Bukas, Karsten Reuter
We augment ab initio molecular dynamics simulations with a quantitative account of phononic dissipation to study the non-equilibrium aftermath of the exothermic oxygen dissociation at low-index (111), (100), and (110) Pd surfaces. Comparing the hyperthermal diffusion arising from a non-instantaneous dissipation of the released chemical energy, we find a striking difference in the resulting "hot" adatom lifetime that is not overall reflected in experimentally recorded product end distances. We rationalize this finding through a detailed mode-specific phonon analysis and identify the dominant dissipation channels as qualitatively different groups of localized surface modes that ultimately lead to intrinsically different rates of dissipation to the Pd bulk...
January 7, 2017: Journal of Chemical Physics
Liubov A Belyaeva, Wangyang Fu, Hadi Arjmandi-Tash, Grégory F Schneider
Transfer of large, clean, crack- and fold-free graphene sheets is a critical challenge in the field of graphene-based electronic devices. Polymers, conventionally used for transferring two-dimensional materials, irreversibly adsorb yielding a range of unwanted chemical functions and contaminations on the surface. An oil-water interface represents an ideal support for graphene. Cyclohexane, the oil phase, protects graphene from mechanical deformation and minimizes vibrations of the water surface. Remarkably, cyclohexane solidifies at 7 °C forming a plastic crystal phase molecularly conforming graphene, preventing the use of polymers, and thus drastically limiting contamination...
December 28, 2016: ACS Central Science
Farid Ramezany, Mahnaz Khanavi, Mohammad Reza Shams Ardakani, Börje Sellegren, Mahdieh Eftekhari, Hossein Rastegar, Maryam Shekarchi
BACKGROUND: Different parts of Colocynth, Citrullus colocynthis (L.) Schrad., are used in traditional phytotherapy and homeopathy. OBJECTIVE: In our new approach, a molecularly imprinted polymer was synthesized to absorb colocynthin, the major plant marker, and its capability was evaluated using HPLC-UV. METHOD: A new method was considered to achieve optimal conditions. FT-infrared, N2 adsorption porosimetry, fluorescent and scanning electron microscopy and thermo gravimetric profile of the polymers were studied...
January 4, 2017: Current Drug Discovery Technologies
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