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Molecular adsorbant

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https://www.readbyqxmd.com/read/28221796/translational-entropy-and-dispersion-energy-jointly-drive-the-adsorption-of-urea-to-cellulose
#1
Pan Chen, Yoshiharu Nishiyama, Jakob Wohlert, Ang Lu, Karim Mazeau, Ahmed E Ismail
The adsorption of urea on cellulose at room temperature has been studied using adsorption isotherm experiments and molecular dynamics (MD) simulations. Immer5sion of cotton cellulose into bulk urea solutions with concentrations between 0.01 g/mL and 0.30 g/mL led to a decrease of urea concentration in all solutions, allowing the adsorption of urea on the cellulose surface to be measured quantitatively. MD sim8ulations suggest that urea molecules form sorption layers on both hydrophobic and hydrophilic surfaces...
February 21, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28221353/from-helical-to-planar-chirality-by-on-surface-chemistry
#2
Oleksandr Stetsovych, Martin Švec, Jaroslav Vacek, Jana Vacek Chocholoušová, Andrej Jančařík, Jiří Rybáček, Krzysztof Kosmider, Irena G Stará, Pavel Jelínek, Ivo Starý
The chirality of molecular structures is paramount in many phenomena, including enantioselective reactions, molecular self-assembly, biological processes and light or electron-spin polarization. Flat prochiral molecules, which are achiral in the gas phase or solution, can exhibit adsorption-induced chirality when deposited on surfaces. The whole array of such molecular adsorbates is naturally racemic as spontaneous global mirror-symmetry breaking is disfavoured. Here we demonstrate a chemical method of obtaining flat prochiral molecules adsorbed on the solid achiral surface in such a way that a specific adsorbate handedness globally dominates...
March 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28217797/poly-vinyl-alcohol-as-a-water-protecting-agent-for-silver-nanoparticles-the-role-of-polymer-size-and-structure
#3
Alexander Kyrychenko, Dmitry A Pasko, Oleg N Kalugin
Chemical modification of silver nanoparticles (AgNPs) with a stabilizing agent, such as poly(vinyl alcohol) (PVA), plays an important role in shape-controlled seeded-growth and colloidal stability. However, theoretical aspects of the stabilizing mechanism of PVA are still poorly understood. To gain a better understanding of the role of PVA in water protecting effects for silver nanoparticles, we developed an atomistic model of a AgNP grafted with single-chain PVA of various lengths. Our model, designed for classical molecular dynamics (MD) simulations, approximates the AgNP as a quasi-spherical silver nanocrystal with 3...
February 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28217715/sensitivity-of-photoelectron-diffraction-to-conformational-changes-of-adsorbed-molecules-tetra-tert-butyl-azobenzene-au-111
#4
A Schuler, M Greif, A P Seitsonen, G Mette, L Castiglioni, J Osterwalder, M Hengsberger
Electron diffraction is a standard tool to investigate the atomic structure of surfaces, interfaces, and adsorbate systems. In particular, photoelectron diffraction is a promising candidate for real-time studies of structural dynamics combining the ultimate time resolution of optical pulses and the high scattering cross-sections for electrons. In view of future time-resolved experiments from molecular layers, we studied the sensitivity of photoelectron diffraction to conformational changes of only a small fraction of molecules in a monolayer adsorbed on a metallic substrate...
January 2017: Structural Dynamics (Melville, N.Y.)
https://www.readbyqxmd.com/read/28214939/selective-determination-of-sulfonamides-from-environmental-water-based-on-magnetic-surface-molecularly-imprinting-technology
#5
Yang Xu, Qi Zhao, Liyan Jiang, Zhengqiang Li, Yanhua Chen, Lan Ding
In the study, a simple and selective method based on magnetic separation technology is presented for the extraction of sulfonamides (SAs) from environmental water, followed by liquid chromatography-tandem mass spectrometry. In this method, magnetic surface molecularly imprinted polymers (Fe3O4@SiO2@MIPs) with super-paramagnetic property and high selectivity toward SAs were developed as magnetic adsorbents. The Fe3O4@SiO2@MIPs were then applied to the selective extraction of SAs from environmental water. The extraction and enrichment were accomplished simultaneously in a single step by simply stirring the mixture of adsorbents and water samples...
February 18, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28214121/a-molecular-zoom-into-soil-humeome-by-a-direct-sequential-chemical-fractionation-of-soil
#6
Marios Drosos, Antonio Nebbioso, Pierluigi Mazzei, Giovanni Vinci, Riccardo Spaccini, Alessandro Piccolo
A Humeomics sequential chemical fractionation coupled to advanced analytical identification was applied directly to soil for the first time. Humeomics extracted ~235% more soil organic carbon (SOC) than by the total alkaline extraction traditionally employed to solubilise soil humic molecules (soil Humeome). Seven fractions of either hydro- or organo-soluble components and a final unextractable humic residue were separated from soil. These materials enabled an unprecedented structural identification of solubilised heterogeneous humic molecules by combining NMR, GC-MS, and ESI-Orbitrap-MS...
February 14, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28211966/formation-of-organometallic-intermediate-states-in-on-surface-ullmann-couplings
#7
Dennis Barton, Hong-Ying Gao, Philipp Alexander Held, Armido Studer, Harald Fuchs, Nikos L Doltsinis, Johannes Neugebauer
Possible origins of the formation of organometallic intermediates in on-surface Ullmann couplings have been investigated by surface tunneling microscopy (STM) and density functional theory (DFT) calculations. We consider the case of iodobenzenes on the coinage metals Au, Ag and Cu. We found experimental evidence for the formation of surface vacancies and the presence of metal adatoms in these coupling reactions, which are taken as a hint for the reactive extraction of surface atoms by adsorbates. In a second step, we demonstrate by ab initio molecular dynamics calculations for aryl-iodides on copper that metal atoms can be pulled out of the surface to form metalorganic species...
February 17, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28210716/a-nonmonotonic-dependence-of-the-contact-angles-on-the-surface-polarity-for-a-model-solid-surface
#8
Chonghai Qi, Bo Zhou, Chunlei Wang, Yujun Zheng, Haiping Fang
Based on molecular dynamics simulations, we found a nonmonotonic relationship between the contact angle of water droplets and the surface polarity on a solid surface with specific hexagonal charge patterns at room temperature. The contact angle firstly decreases and then increases as polarity (denoted as charge q) increases from 0 e to 1.0 e with a vertex value of q = 0.5 e. We observed a different wetting behavior for a water droplet on a conventional nonwetted solid surface when q ≤ 0.5 e, and a water droplet on an ordered water monolayer adsorbed on a highly polar solid surface when q > 0...
February 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28209350/n-decyl-s-trityl-r-cysteine-a-new-chiral-selector-for-green-ligand-exchange-chromatography-applications
#9
Andrea Carotti, Federica Ianni, Emidio Camaioni, Lucia Pucciarini, Maura Marinozzi, Roccaldo Sardella, Benedetto Natalini
In search for new enantioselectivity profiles, the N-decyl-S-trityl-(R)-cysteine [C10-(R)-STC] was synthesized through a one-step procedure and then hydrophobically adsorbed onto an octadecylsilica surface to generate a stable chiral stationary phase for ligand-exchange chromatography (CLEC-CSP) applications. The CLEC analysis was carried out on underivatized amino acids, by using a Cu(II) sulphate (1.0mM) containing aqueous eluent system. Most of the analysed compounds (34 out of 45) were enantiodiscriminated by the C10-(R)-STC-based CSP, with resolution factor (RS) values up to 8...
February 5, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28208081/molecular-synergy-in-biolubrication-the-role-of-cartilage-oligomeric-matrix-protein-comp-in-surface-structuring-of-lubricin
#10
Akanksha Raj, Min Wang, Chao Liu, Liaquat Ali, Niclas G Karlsson, Per M Claesson, Andra Dėdinaitė
HYPOTHESIS: Synovial surfaces are lubricated by biomolecular aggregates that act in synergy, and lubricin is one key biolubricant. Its molecular structure allows extensive hydration and this is conducive to its lubrication performance. However, in order to fullfil its lubrication function it needs to be anchored and oriented on the surface in a proper way. We suggest that cartilage oligomeric matrix protein (COMP) is one of the biomolecules that promotes anchoring of lubricin in a fashion that facilitates lubrication...
February 8, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28206764/host-guest-chemistry-at-integrated-porous-space-formed-by-molecular-self-assembly-at-liquid-solid-interfaces
#11
Kohei Iritani, Kazukuni Tahara, Steven De Feyter, Yoshito Tobe
Host-guest chemistry in two-dimensional space, that is physisorbed monolayers of a single atom or a single molecular thickness on surfaces, has become a subject of intense current interest because of perspectives for various applications in molecular-scale electronics, selective sensors, and tailored catalysis. Scanning tunneling microscopy, with which we can visualize molecules in actual space, has been used as a powerful tool. For more than a decade, we have been investigating the self-assembly of a series of triangle-shaped molecules with a phenylene-ethynylene macrocycle, called dehydrobenzo[12]annulenes (DBAs), substituted by six flexible alkyl chains, forming hexagonal porous 2D molecular networks via van der Waals interactions between interdigitated alkyl chains at the interface of organic solvent and graphite...
February 16, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28206762/influence-of-lafeo3-surface-termination-on-water-reactivity
#12
Kelsey A Stoerzinger, Ryan B Comes, Steven R Spurgeon, Suntharampillai Thevuthasan, Kyuwook Ihm, Ethan J Crumlin, Scott A Chambers
The polarity of oxide surfaces can dramatically impact their surface reactivity, in particular with polar molecules such as water. The surface species that result from this interaction change the oxide electronic structure and chemical reactivity in applications such as photoelectrochemistry, but are challenging to probe experimentally. Here we report a detailed study of the surface chemistry and electronic structure of the perovskite LaFeO3 in humid conditions using ambient pressure X-ray photoelectron spectroscopy...
February 16, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28205651/metal-support-interaction-on-cobalt-based-ft-catalysts-a-dft-study-of-model-inverse-catalysts
#13
Tracey van Heerden, Eric van Steen
It is challenging to isolate the effect of metal-support interactions on catalyst reaction performance. In order to overcome this problem, inverse catalysts can be prepared in the laboratory and characterized and tested at relevant conditions. Inverse catalysts are catalysts where the precursor to the catalytically active phase is bonded to a support-like ligand. We can then view the metal-support interaction as a ligand interaction with the support acting as a supra-molecular ligand. Importantly, laboratory studies have shown that these ligands are still present after reduction of the catalyst...
February 16, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28199948/biosorption-removal-of-benzene-and-toluene-by-three-dried-macroalgae-at-different-ionic-strength-and-temperatures-algae-biochemical-composition-and-kinetics
#14
Carlos E Flores-Chaparro, Luis Felipe Chazaro Ruiz, Ma Catalina Alfaro de la Torre, Miguel Angel Huerta-Diaz, Jose Rene Rangel-Mendez
Release of low-molecular aromatic hydrocarbons (HC) into natural waters brings severe consequences to our environment. Unfortunately very limited information is available regarding the treatment of these pollutants. This work evaluated the use of brown, green and red macroalgae biomass as biosorbents of benzene and toluene, two of the most soluble HC. Raw seaweed biomasses were completely characterized, then evaluated under different temperatures and ionic strengths to assess their potential as biosorbents and to elucidate the biosorption mechanisms involved...
February 12, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/28195715/interfacial-interaction-of-titania-nanoparticles-and-ligated-uranyl-species-a-relativistic-dft-investigation
#15
Hong-Bo Zhao, Ming Zheng, Georg Schreckenbach, Qing-Jiang Pan
To understand interfacial behavior of actinides adsorbed onto mineral surfaces and unravel their structure-property relationship, the structures, electronic properties, and energetics of various ligated uranyl species adsorbed onto TiO2 surface nanoparticle clusters (SNCs) were examined using relativistic density functional theory. Rutile (110) and anatase (101) titania surfaces, experimentally known to be stable, were fully optimized. For the former, models studied include clean and water-free Ti27O64H20 (dry), partially hydrated (Ti27O64H20)(H2O)8 (sol) and proton-saturated [(Ti27O64H20)(H2O)8(H)2](2+) (sat), while defect-free and defected anatase SNCs involving more than 38 TiO2 units were considered...
February 14, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28195175/chemical-and-entropic-control-on-the-molecular-self-assembly-process
#16
Daniel M Packwood, Patrick Han, Taro Hitosugi
Molecular self-assembly refers to the spontaneous assembly of molecules into larger structures. In order to exploit molecular self-assembly for the bottom-up synthesis of nanomaterials, the effects of chemical control (strength of the directionality in the intermolecular interaction) and entropic control (temperature) on the self-assembly process should be clarified. Here we present a theoretical methodology that unambiguously distinguishes the effects of chemical and entropic control on the self-assembly of molecules adsorbed to metal surfaces...
February 14, 2017: Nature Communications
https://www.readbyqxmd.com/read/28193466/three-dimensional-ionic-liquid-functionalized-magnetic-graphene-oxide-nanocomposite-for-the-magnetic-dispersive-solid-phase-extraction-of-16-polycyclic-aromatic-hydrocarbons-in-vegetable-oils
#17
Yun Zhang, Hua Zhou, Zhe-Hua Zhang, Xiang-Lun Wu, Wei-Guo Chen, Yan Zhu, Chun-Fu Fang, Yong-Gang Zhao
In this paper, a novel three-dimensional ionic liquid functionalized magnetic graphene oxide nanocomposite (3D-IL@mGO) was prepared, and used as an effective adsorbent for the magnetic dispersive solid phase extraction (MSPE) of 16 polycyclic aromatic hydrocarbons (PAHs) in vegetable oil prior to gas chromatography-mass spectrometry (GC-MS). The properties of 3D-IL@mGO were characterized by scanning electron micrographs (SEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM). The 3D-IL@mGO, functionalized by ionic liquid, exhibited high adsorption toward PAHs...
February 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28192642/theoretical-rationalization-for-reduced-charge-recombination-in-bulky-carbazole-based-sensitizers-in-solar-cells
#18
Yaowarat Surakhot, Viktor Laszlo, Chirawat Chitpakdee, Vinich Promarak, Taweesak Sudyoadsuk, Nawee Kungwan, Tim Kowalczyk, Stephan Irle, Siriporn Jungsuttiwong
The search for greater efficiency in organic dye-sensitized solar cells (DSCs) and in their perovskite cousins is greatly aided by a more complete understanding of the spectral and morphological properties of the photoactive layer. This investigation resolves a discrepancy in the observed photoconversion efficiency (PCE) of two closely related DSCs based on carbazole-containing D-π-A organic sensitizers. Detailed theoretical characterization of the absorption spectra, dye adsorption on TiO2 , and electronic couplings for charge separation and recombination permit a systematic determination of the origin of the difference in PCE...
February 13, 2017: Journal of Computational Chemistry
https://www.readbyqxmd.com/read/28191926/double-recognition-and-selective-extraction-of-glycoprotein-based-on-the-molecular-imprinted-graphene-oxide-and-boronate-affinity
#19
Jing Luo, Jing Huang, Jiaojiao Cong, Wei Wei, Xiaoya Liu
Specific recognition and separation of glycoproteins from complex biological solutions is very important in clinical diagnostics considering the close relationship between glycoproteins with the occurrence of diverse diseases, but the lack of materials with high selectivity and superior capture capacity still makes it a challenge. In this work, graphene oxide (GO) based molecularly imprinted polymers (MIPs) possessing double recognition abilities have been synthesized and applied as highly efficient adsorbents for glycoprotein recognition and separation...
February 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28191584/sizable-dynamics-in-small-pores-co2-location-and-motion-in-the-%C3%AE-mg-formate-metal-organic-framework
#20
Yuanjun Lu, Bryan E G Lucier, Yue Zhang, Pengju Ren, Anmin Zheng, Yining Huang
Metal-organic frameworks (MOFs) are promising materials for carbon dioxide (CO2) adsorption and storage; however, many details regarding CO2 dynamics and specific adsorption site locations within MOFs remain unknown, restricting the practical uses of MOFs for CO2 capture. The intriguing α-magnesium formate (α-Mg3(HCOO)6) MOF can adsorb CO2 and features a small pore size. Using an intertwined approach of (13)C solid-state NMR (SSNMR) spectroscopy, (1)H-(13)C cross-polarization SSNMR, and computational molecular dynamics (MD) simulations, new physical insights and a rich variety of information have been uncovered regarding CO2 adsorption in this MOF, including the surprising suggestion that CO2 motion is restricted at elevated temperatures...
February 13, 2017: Physical Chemistry Chemical Physics: PCCP
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