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Molecular adsorbant

Alba Maceira, Laura Vallecillos, Francesc Borrull, Rosa Maria Marcé
This study describes the humidity effect in the sampling process by adsorbent tubes followed by thermal desorption and gas chromatography-mass spectrometry (TD-GC-MS) for the determination of volatile organic compounds (VOCs) in air samples and evaluates possible solutions to this problem. Two multi-sorbent bed tubes, Tenax TA/Carbograph 1TD and Carbotrap B/Carbopack X/Carboxen 569, were tested in order to evaluate their behaviour in the presence of environmental humidity. Humidity problems were demonstrated with carbon-based tubes, while Tenax-based tubes did not display any influence...
May 19, 2017: Science of the Total Environment
Xuezheng Cao, Holger Merlitz, Chen-Xu Wu
Controlling the nanoparticle (NP) diffusion in polymers is a prerequisite to obtain polymer nanocomposites (PNCs) with desired dynamical and rheological properties, and to achieve targeted delivery of nanomedicine in biological systems. Here we determinate the suppression mechanism of direct NP-polymer attraction to hamper the NP mobility in adsorbing polymers, and then quantify the dependence of the effective viscosity \eta_{eff} felt by the NP on the adsorption duration \tau_{ads} of polymers on the NP, using scaling theory analysis and molecular dynamics (MD) simulations...
May 23, 2017: Journal of Physical Chemistry Letters
Peng Liu, Viktor Johansson, Herri Trilaksana, Jan Rosdahl, Gunther G Andersson, Lars Kloo
The organization of dye molecules in the dye layer adsorbed on the semiconductor substrate in dye-sensitized solar cell has been studied using a combination of theoretical methods and experimental techniques. The model system is based on the simple D--A dye L0, which has been chemically modified to replace the acceptor group -CN by -Br (L0Br) in order to offer better X-ray contrast. Experimental EXAFS data based on the Br K-edge backscattering show no obvious difference between dye-sensitised titania powder and titania film samples, thus allowing model systems to be based on powder slurrys...
May 23, 2017: ACS Applied Materials & Interfaces
Amandine Cadiau, Youssef Belmabkhout, Karim Adil, Prashant M Bhatt, Renjith S Pillai, Aleksander Shkurenko, Charlotte Martineau-Corcos, Guillaume Maurin, Mohamed Eddaoudi
Natural gas must be dehydrated before it can be transported and used, but conventional drying agents such as activated alumina or inorganic molecular sieves require an energy-intensive desiccant-regeneration step. We report a hydrolytically stable fluorinated metal-organic framework, AlFFIVE-1-Ni (KAUST-8), with a periodic array of open metal coordination sites and fluorine moieties within the contracted square-shaped one-dimensional channel. This material selectively removed water vapor from gas streams containing CO2, N2, CH4, and higher hydrocarbons typical of natural gas, as well as selectively removed both H2O and CO2 in N2-containing streams...
May 19, 2017: Science
Jan Philip Kraack, Angelo Frei, Roger Alberto, Peter Hamm
We investigate the ultrafast vibrational dynamics of monolayers from adsorbed rhenium-carbonyl CO2-reduction catalysts on a semiconductor surface (indium-tin-oxide (ITO)) with ultrafast two-dimensional attenuated total reflection infrared (2D ATR IR) spectroscopy. The complexes are partially equipped with isotope-labeled ((13)C) carbonyl ligands to generate two spectroscopically distinguishable forms of the molecules. Ultrafast vibrational energy transfer between the molecules is observed via the temporal evolution of cross-peaks between their symmetric carbonyl stretching vibrations...
May 22, 2017: Journal of Physical Chemistry Letters
Alberto Striolo, Brian Patrick Grady
Surfactant adsorption at solid-liquid interfaces is critical for a number of applications of vast industrial interest, and can also be used to seed surface-modification processes. Many of the surfaces of interest are nano-structured, as they might present surface roughness at the molecular scale, chemical heterogeneity, as well as a combination of both surface roughness and chemical heterogeneity. These effects provide 'lateral' confinement on the surfactant aggregates. It is of interest to quantify how much surfactant adsorbs on such nano-structured surfaces, and how the surfactant aggregates vary as the degree of lateral confinement changes...
May 18, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Tigran M Abramyan, David L Hyde-Volpe, Steven J Stuart, Robert A Latour
The use of standard molecular dynamics simulation methods to predict the interactions of a protein with a material surface have the inherent limitations of lacking the ability to determine the most likely conformations and orientations of the adsorbed protein on the surface and to determine the level of convergence attained by the simulation. In addition, standard mixing rules are typically applied to combine the nonbonded force field parameters of the solution and solid phases the system to represent interfacial behavior without validation...
May 17, 2017: Biointerphases
Adam M Davidson, Mathias Brust, David L Cooper, Martin Volk
It is demonstrated that the adsorption of bovine serum albumin (BSA) to aqueous gold colloids can be quantified with molecular resolution by differential centrifugal sedimentation (DCS). This method separates colloidal particles of comparable density by mass. When proteins adsorb to the nanoparticles, both their mass and their effective density change, which strongly affects the sedimentation time. A straightforward analysis allows quantification of the adsorbed layer. Most importantly, unlike many other methods, DCS can be used to detect chemisorbed proteins ("hard corona") as well as physisorbed proteins ("soft corona")...
May 17, 2017: Analytical Chemistry
Li Yan, Jiaying Song, Ting-Shan Chan, Chuanyong Jing
Antimony (Sb) contamination poses an emerging environmental risk, whereas its removal remains a contemporary challenge due to the lack of knowledge in its surface chemistry and efficient adsorbent. In this study, self-assembly {001} TiO2 was examined for its effectiveness in Sb removal, and the molecular level surface chemistry was studied with X-ray absorption spectroscopy and density functional theory calculations. The kinetics results show that Sb adsorption followed the pseudo-second order reaction, and the Langmuir adsorption capacity was 200 mg/g for Sb(III) and 156 mg/g for Sb(V)...
May 17, 2017: Environmental Science & Technology
Takashi Miura, Masayuki Naruto, Katsuaki Toda, Taiki Shimomura, Susumu Saito
Amides are ubiquitous and abundant in nature and our society, but are very stable and reluctant to salt-free, catalytic chemical transformations. Through the activation of a "sterically confined bipyridine-ruthenium (Ru) framework (molecularly well-designed site to confine adsorbed H2 in)" of a precatalyst, catalytic hydrogenation of formamides through polyamide is achieved under a wide range of reaction conditions. Both C=O bond and C-N bond cleavage of a lactam became also possible using a single precatalyst...
May 16, 2017: Scientific Reports
Karol Kulasinski
The diffusion coefficient of water adsorbed in hydrophilic porous materials, such as non-crystalline cellulose, depends on water activity. Faster diffusion at higher water concentrations is observed in experimental and modeling studies. In this paper, two asymptotic water concentrations, near-vacuum and fully saturated, are investigated at the surface of crystalline cellulose with molecular dynamics simulations. An increasing water concentration leads to significant changes in the free energy landscape due to perturbation of local electrostatic potential...
May 16, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Fumio Arisaka, Moh Lan Yap, Shuji Kanamaru, Michael G Rossmann
The tail of bacteriophage T4 undergoes large structural changes upon infection while delivering the phage genome into the host cell. The baseplate is located at the distal end of the contractile tail and plays a central role in transmitting the signal to the tail sheath that the tailfibers have been adsorbed by a host bacterium. This then triggers the sheath contraction. In order to understand the mechanism of assembly and conformational changes of the baseplate upon infection, we have determined the structure of an in vitro assembled baseplate through the three-dimensional reconstruction of cryo-electron microscopy images to a resolution of 3...
December 2016: Biophysical Reviews
Katherine D Krause, Sandra Roy, Dennis K Hore
Atomistic molecular dynamics simulations were used to study the influence of interfacial water on the orientation and conformation of a facewise amphipathic α-helical peptide adsorbed to hydrophilic and hydrophobic substrates. Water behavior beneath the peptide adsorbed to a hydrophilic surface was observed to vary with the height of the peptide above the surface. In general, the orientation of water close to the peptide (with the oxygen atom pointing up toward the peptide) was complementary to that observed near the hydrophilic surface in the absence of peptide...
May 15, 2017: Biointerphases
Yunxiao Lin, Xuanfeng Jiang, Samuel T Kim, Sampath B Alahakoon, Xisen Hou, Zhiyun Zhang, Christina M Thompson, Ronald A Smaldone, Chenfeng Ke
A crystalline microporous hydrogen-bonded cross-linked organic framework has been developed through covalent photo-cross-linking of molecular monomers that are assembled in a crystalline state. The elastic framework expands its void space to adsorb iodine rapidly with a high uptake capacity in an aqueous environment as well as recovering its crystalline form after the release of iodine.
May 19, 2017: Journal of the American Chemical Society
J Haase, S Bagiante, H Sigg, J A van Bokhoven
We report the enhancement of infrared absorption of chemisorbed carbon monoxide on platinum in the gap of plasmonic nanoantennas. Our method is based on the self-assembled formation of platinum nanoislands on nanoscopic dipole antenna arrays manufactured via electron beam lithography. We employ systematic variations of the plasmonic antenna resonance to precisely couple to the molecular stretch vibration of carbon monoxide adsorbed on the platinum nanoislands. Ultimately, we reach more than 1500-fold infrared absorption enhancements, allowing for an ultrasensitive detection of a monolayer of chemisorbed carbon monoxide...
May 15, 2017: Optics Letters
Melika Sarem, Daniel Vonwil, Steffen Lüdeke, V Prasad Shastri
Understanding the composition of the adsorbed protein layer on a biomaterial surface is of an extreme importance as it directs the primary biological response. Direct detection using labeled proteins and indirect detection based on enzymatic assays or changes to mass, refractive index or density of a surface have been so far established. Nevertheless, using current methodologies, detection of multiple proteins simultaneously and particularly in a three-dimensional (3D) substrates is challenging, with the exception of radiolabeling...
May 11, 2017: Acta Biomaterialia
William L Hoffeditz, Michael J Pellin, Omar K Farha, Joseph T Hupp
Often key to boosting photovoltages in photoelectrochemical and related solar-energy-conversion devices is the preferential slowing of rates of charge recombination - especially recombination at semiconductor/solution, semiconductor/polymer, or semiconductor/perovskite interfaces. In devices featuring TiO2 as the semiconducting component, a common approach to slowing recombination is to install an ultrathin metal-oxide barrier layer or trap-passivating layer atop the semiconductor, with the needed layer often being formed via atomic layer deposition (ALD)...
May 12, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Jozsef Kupai, Mayamin Razali, Sibel Buyuktiryaki, Rustem Kecili, Gyorgy Szekely
Molecularly imprinted materials are man-made mimics of biological receptors. Their polymer network has recognition sites complementary to a substrate in terms of size, shape and chemical functionality. They have diverse applications in various chemical, biomedical and engineering fields such as solid phase extraction, catalysis, drug delivery, pharmaceutical purification, (bio)sensors, water treatment, membrane separations and proteomics. The stability and reusability of molecularly imprinted polymers (IPs) have crucial roles in developing applications that are reliable, economic and sustainable...
January 28, 2017: Polymer Chemistry
Xiaoxia Li, Kyung Ho Row
Deep eutectic solvents (DES) are potential ecofriendly surfactants for the preparation of materials. In this study, both molecularly imprinted polymers (MIPs) and mesoporous siliceous materials (MSMs) were modified by betaine-based DES. Six materials were employed as solid phase extraction (SPE) adsorbents for the rapid purification of levofloxacin. The DES-based materials showed better selective adsorption than the conventional materials. The adsorption curves of DES-MIP showed superior molecular recognition ability and binding capability for levofloxacin compared to the other materials...
2017: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Chen Tan, Zhiyun Zhang, Yanqi Qu, Lili He
Surface-enhanced Raman spectroscopy (SERS) and surface-enhanced infrared absorption spectroscopy (SEIRAS) are complementary and powerful techniques for molecular characterization and detection. However, studies on substrates that can enhance both Raman and IR singles are extremely scanty. Here, we reported a hybrid semiconductor material (Ag2O/TiO2) coupled with a portable solid support served as a dual functional platform for both SERS and SEIRAS applications. A facile two-step deposition method was used to synthesize Ag2O/TiO2 nanocomposite on a flexible polymeric membrane without bringing any external chemical capping agent and background signal...
May 22, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
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