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Molecular adsorbant

Jixue Sun, Yang Li, Jianping Lin
DNA nanostructures can undergo large structural fluctuations and deviate from their intended configurations. In this work, two model DNA nanostructures (i.e., Nan and Kai) were designed based on the shape of the two Chinese characters of the name of Nankai University, and additional single-stranded DNA fragments were added to interact with graphene. During four 50-ns molecular dynamic simulations in aqueous solution, the DNA nanostructures adsorbed onto graphene demonstrated more stable conformations with lower root mean square deviations and smaller coordinate changes in the z-axis direction than the DNA nanostructures that were not adsorbed onto graphene...
March 9, 2017: Journal of Molecular Graphics & Modelling
J Brand, P Ribeiro, N Néel, S Kirchner, J Kröger
Charge transport has been examined in junctions comprising the normal-metal tip of a low-temperature scanning tunneling microscope, the surface of a conventional superconductor, and adsorbed C_{60} molecules. The Bardeen-Cooper-Schrieffer energy gap gradually evolves into a zero-bias peak with decreasing electrode separation. The peak is assigned to the spectroscopic signature of Andreev reflection. The conductance due to Andreev reflection is determined by the atomic termination of the tip apex and the molecular adsorption orientation...
March 10, 2017: Physical Review Letters
Ying-Juan Hao, Bing Liu, Li-Gang Tian, Fa-Tang Li, Jie Ren, Shao-Jia Liu, Ying Liu, Jun Zhao, Xiaojing Wang
Seeking a simple and moderate route to generate reactive oxygen species (ROS) for antibiosis is of great interest and challenge. This work demonstrates that molecule transition and electron rearrangement processes can directly occur only through chemisorption interaction between the adsorbed O2 and high-energy {111} facet-exposed MgO with abundant surface oxygen vacancies (SOVs), hence producing singlet oxygen and superoxide anion radicals without light irradiation. These ROS were confirmed by electron paramagnetic resonance, in-situ Raman and scavenger experiments, respectively...
March 24, 2017: ACS Applied Materials & Interfaces
Jun-Jun Shang, Qing-Sheng Yang, Xiao-Hui Yan, Xiao-Qiao He, Kim-Meow Liew
A nanorope is comprised of several carbon nanotubes (CNTs) with different chiralities. A molecular dynamic model is built to investigate the ionic adsorption and desorption of the CNT nanoropes. The charge distribution on the nanorope is obtained by using a modified gradient method based on classical electrostatic theory. The electrostatic interactions among charged carbon atoms are calculated by using the Coulomb law. It was found here that the charged nanorope can adsorb heavy metal ions, and the adsorption and desorption can be realized by controlling the strength of applied electric field...
September 28, 2016: Nanomaterials
Weiyang Tang, Fan Gao, Yue Duan, Tao Zhu, Kyung Ho Row
Novel deep eutectic solvents modified molecularly imprinted polymers (DESs-MIPs) were synthesized using acrylamide as function monomer, alcohol-based DESs as auxiliary function monomer and chloramphenicol (CAP) as the template. The DESs modified materials were characterized by Fourier transform infrared and field emission scanning electron microscope. The adsorption results that the choline chloride/ethylene glycol DESs-based MIPs had stable interactions with CAP. So the choline chloride/ethylene glycol DESs-based MIPs were applied as sorbent of minimized pipette-tip solid-phase extraction (PT-SPE) for rapid screening CAP from milk sample...
February 27, 2017: Journal of Chromatographic Science
Dominic A Esan, Michael Trenary
Adsorption and thermal chemistry of propanal, 2-propenol, and 1-propanol on Ru(001) were studied using temperature programmed reaction spectroscopy (TPRS) and reflection absorption infrared spectroscopy (RAIRS). The results show that each molecule adsorbs molecularly at 90 K and displays the same spectral features as observed for the corresponding liquids after 1.0 L exposures. 2-Propenol was found to molecularly desorb at 200 K, dehydrate to yield propene around 130 K, isomerize to propanal at 180 K, and hydrogenate to 1-propanol at 220 K...
March 22, 2017: Physical Chemistry Chemical Physics: PCCP
Yitong Bai, Zhu Ming, Yuye Cao, Shicheng Feng, Hua Yang, Lingyun Chen, Sheng-Tao Yang
The dramatically different bio-effects of graphene and graphene oxide (GO) have been widely observed in diverse biological systems, which determine the applications and toxicity of graphene materials. To elucidate the mechanism at molecular level, it is urgent to investigate the enzyme-graphene interaction and its consequences. In this study, we comparatively studied the influence of GO and reduced GO (RGO) on the activity and conformation of lysozyme to provide better understandings of their different bio-effects...
March 8, 2017: Colloids and Surfaces. B, Biointerfaces
Wei Lin, Kelsey M Stocker, George C Schatz
Mechanistic details of catalytic reactions are critical to the development of improved catalysts. Here, we perform high quality Born-Oppenheimer molecular dynamics (BOMD) simulations of the reaction mechanisms associated with hydrogen-assisted CO2 reduction on Ni(110). The simulation results show direct theoretical evidence for both associative and redox mechanisms in the reaction of atomic hydrogen with CO¬2. Since H2 is dissociatively chemisorbed on Ni(110) with nearly unit probability, the mechanisms we find are also relevant to the RWGS reaction (H2 with adsorbed CO¬2)...
March 21, 2017: Journal of the American Chemical Society
Michał Cegłowski, Marek Smoluch, Edward Reszke, Jerzy Silberring, Grzegorz Schroeder
The application of molecularly imprinted polymers (MIPs) as molecular scavengers for ambient plasma ionization mass spectrometry has been reported for the first time. MIPs were synthesized using methacrylic acid as functional monomer; nicotine, propyphenazone, or methylparaben as templates; ethylene glycol dimethacrylate as a cross-linker; and 2,2'-azobisisobutyronitrile as polymerization initiator. To perform ambient plasma ionization experiments, a setup consisting of the heated crucible, a flowing atmospheric-pressure afterglow (FAPA) plasma ion source, and a quadrupole ion trap mass spectrometer has been used...
March 20, 2017: Analytical and Bioanalytical Chemistry
Shinichi Hirabayashi, Masahiko Ichihashi
Reactions of pure and doped rhodium cluster cations, RhnX(+) (n = 2-6; X = Al, V, Co, Rh), with NO molecules were investigated at near-thermal energy using a guided ion beam tandem mass spectrometer. We found that the doping with Al and V increases the total reaction cross section mostly. Under single collision conditions, Rh2X(+) react with NO to produce Rh2N(+) with releasing metal monoxide, XO, while RhnX(+) (n = 3-6) adsorb NO. For the specific clusters, RhnAl(+) (n = 3 and 4) and RhnV(+) (n = 4-6), the NO adsorption is often accompanied with the release of one Rh atom...
March 20, 2017: Journal of Physical Chemistry. A
Ya-Sen Sun, Chien-Fu Lin, Shih-Ting Luo, Ching-Yuan Su
The self-assembly of a block copolymer offers access to micellar nanodomains with tunable dimensions and structural diversity through control of such molecular parameters as the volume fraction and molecular mass. We fabricated hierarchical porous carbon (HPC) nanostructures with bundles of aggregated nanospheres and with nitrogen-rich functional groups through pyrolysis of diblock copolymer micelles in multiple layers. The resultant HPC nanostructures with a considerable specific surface area serve as an excellent substrate for surface-enhanced Raman spectroscopy (SERS), coupled with fluorescence quenching, for molecular sensing of physically adsorbed Rhodamine 6G...
March 20, 2017: ACS Applied Materials & Interfaces
Felix Schulze-Zachau, Björn Braunschweig
Air/water interfaces were modified by oppositely charged poly(sodium 4-styrenesulfonate) (NaPSS) and hexadecyltrimethylammonium bromide (CTAB) polyelectrolyte/surfactant mixtures and were studied on a molecular level with vibrational sum-frequency generation (SFG), tensiometry, surface dilatational rheology and ellipsometry. In order to deduce structure property relations, our results on the interfacial molecular structure and lateral interactions of PSS(-)/CTA(+) complexes were compared to the stability and structure of macroscopic foam as well as to bulk properties...
March 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Miguel A Gonzalez, Hanna M G Barriga, Joanna L Richens, Robert V Law, Paul O'Shea, Fernando Bresme
Lanthanide salts have been studied for many years, primarily in Nuclear Magnetic Resonance (NMR) experiments of mixed lipid-protein systems and more recently to study lipid flip-flop in model membrane systems. It is well recognised that lanthanide salts can influence the behaviour of both lipid and protein systems, however a full molecular level description of lipid-lanthanide interactions is still outstanding. Here we present a study of lanthanide-bilayer interactions, using molecular dynamics computer simulations, fluorescence electrostatic potential experiments and nuclear magnetic resonance...
March 20, 2017: Physical Chemistry Chemical Physics: PCCP
Zhichao Huang, Yajie Zhang, Yang He, Huanjun Song, Cen Yin, Kai Wu
This review summarizes recent research progress in the measurement and tuning of the electron spins of alien atoms and molecules adsorbed on well-defined substrates. After a brief introduction to the main experimental techniques employed to study surface electron spins, some well-explored systems consisting of atomic and molecular spin-carriers at surfaces are overviewed from a chemist's viewpoint, focusing on the experimental measurements and chemical modifications of the electron spin states of the alien entities at the surfaces on the atomic/molecular level...
March 20, 2017: Chemical Society Reviews
Giuseppe Licari, Lukasz Cwiklik, Pavel Jungwirth, Eric Vauthey
The adsorption of a DNA fluorescent probe belonging to the thiazole orange family at the dodecane/water and dodecane/phospholipid/water interfaces has been investigated using a combination of surface-second harmonic generation (SSHG) and all-atomistic molecular dynamics (MD) simulations. Both approaches point to a high affinity of the cationic dye for the dodecane/water interface with a Gibbs free energy of adsorption of the order of -45 kJ/mol. Similar affinity was observed with a monolayer of negatively charged DPPG (1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1-glycerol)) lipids...
March 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Shin Wakiyama, Hitoshi Watarai
The role of an external force on chemical equilibria is an important subject in mechanobiochemistry. The effect of an electromagnetophoretic force for the stretching of cysteamine molecules was examined by using SERS spectrometry. Polystyrene particles modified with cysteamine were bound to silver nanoparticles adsorbed on the wall of a silica capillary cell. Under a constant magnetic field, when an electric current was applied to the conductive medium in the capillary, the shift of SERS bands and the increase of the trans/gauche ratio of cysteamine were observed, suggesting a molecular conformation change of cysteamine due to the stretching force...
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Wael A Fouad, Lourdes F Vega
The use of hydrofluorocarbons (HFCs) as alternative non-ozone depleting refrigerants for chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) has grown during the last couple of decades. Owing to their considerable global warming potential, a global deal has been reached recently to limit the production and consumption of HFCs. For rational design of new refrigerants that are environmentally friendlier, the thermodynamics of current ones need to be well understood first. In this work, we examine the phase behavior of azeotropic refrigerants obtained by mixing HFCs with normal alkanes...
March 16, 2017: Physical Chemistry Chemical Physics: PCCP
Adam Kecskemeti, Jozsef Bako, Istvan Csarnovics, Eva Csosz, Attila Gaspar
Herein, a microfluidic device (MD) containing immobilized trypsin for rapid and efficient proteolysis was described. Trypsin was immobilized via non-specific protein adsorption onto the hydrophobic poly(dimethylsiloxane) (PDMS) channel wall of the MD. Peptide mapping of bovine serum albumin (BSA) samples was carried out to estimate the stability of trypsin adsorbed on PDMS surface. Peptide maps of BSA samples were obtained by capillary zone electrophoresis (CZE), the RSD% for migration times were under 1%. Several proteins (hemoglobin, myoglobin, lysozyme, and BSA) in a wide molecular size range (15-70 kDa) were digested efficiently with ∼50 s contact time...
March 15, 2017: Analytical and Bioanalytical Chemistry
Mi Young Jeon, Donghun Kim, Prashant Kumar, Pyung Soo Lee, Neel Rangnekar, Peng Bai, Meera Shete, Bahman Elyassi, Han Seung Lee, Katabathini Narasimharao, Sulaiman Nasir Basahel, Shaeel Al-Thabaiti, Wenqian Xu, Hong Je Cho, Evgenii O Fetisov, Raghuram Thyagarajan, Robert F DeJaco, Wei Fan, K Andre Mkhoyan, J Ilja Siepmann, Michael Tsapatsis
A zeolite with structure type MFI is an aluminosilicate or silicate material that has a three-dimensionally connected pore network, which enables molecular recognition in the size range 0.5-0.6 nm. These micropore dimensions are relevant for many valuable chemical intermediates, and therefore MFI-type zeolites are widely used in the chemical industry as selective catalysts or adsorbents. As with all zeolites, strategies to tailor them for specific applications include controlling their crystal size and shape...
March 15, 2017: Nature
Vanessa Quaranta, Matti Hellström, Jörg Behler
The dissociation of water is an important step in many chemical processes at solid surfaces. In particular, water often spontaneously dissociates near metal oxide surfaces, resulting in a mixture of H2O, H(+), and OH(-) at the interface. Ubiquitous proton-transfer (PT) reactions cause these species to dynamically interconvert, but the underlying mechanisms are poorly understood. Here, we develop and use a reactive high-dimensional neural-network potential based on density functional theory data to elucidate the structural and dynamical properties of the interfacial species at the liquid-water-metal-oxide interface, using the nonpolar ZnO(101̅0) surface as a prototypical case...
March 20, 2017: Journal of Physical Chemistry Letters
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