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Physical Chemistry

Shashi Kant Shukla, Shubha Pandey, Siddharth Pandey
Ionic liquids (ILs) have been receiving much attention in many fields of analytical chemistry because of their various interesting properties which distinguish them from volatile organic compounds. They offer both directional and non-directional forces towards a solute molecule and therefore act as excellent solvents for a wide range of polar and non-polar compounds. Because of the presence of various possible interactions, ILs easily undergo biphasic separation with water and other less polar/non-polar organic solvents...
October 10, 2017: Journal of Chromatography. A
Bryan L Roth, John J Irwin, Brian K Shoichet
Although a plurality of drugs target G-protein-coupled receptors (GPCRs), most have emerged from classical medicinal chemistry and pharmacology programs and resemble one another structurally and functionally. Though effective, these drugs are often promiscuous. With the realization that GPCRs signal via multiple pathways, and with the emergence of crystal structures for this family of proteins, there is an opportunity to target GPCRs with new chemotypes and confer new signaling modalities. We consider structure-based and physical screening methods that have led to the discovery of new reagents, focusing particularly on the former...
November 2017: Nature Chemical Biology
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No abstract text is available yet for this article.
October 16, 2017: Angewandte Chemie
Torben Steenbock, Carmen Herrmann
Understanding (super-)exchange coupling between local spins is an important task in theoretical chemistry and solid-state physics. We show that a Green's-function approach introduced earlier (Liechtenstein et al., J. Phys. F 1984, 14, L125; Steenbock et al., J. Chem. Theory Comput. 2015, 11, 5651) can be used for analyzing exchange coupling pathways in an automated fashion rather than by visual inspection of molecular orbitals. We demonstrate the capabilities of this approach by comparing it to previously published pathway analyses for hydroxy-bridged dinuclear copper complexes and an oxo-bridged dinuclear manganese complex, and employ it for discriminating between through-space and through-bond pathways in a naphthalene-bridged bisnickelocene complex...
October 17, 2017: Journal of Computational Chemistry
Mehrdad Samadishadlou, Masoud Farshbaf, Nasim Annabi, Taras Kavetskyy, Rovshan Khalilov, Siamak Saghfi, Abolfazl Akbarzadeh, Sepideh Mousavi
Magnetic carbon nanotubes (MCNTs) have been widely studied for their potential applications in medicine, diagnosis, cell biology, analytical chemistry, and environmental technology. Introduction of MCNTs paved the way for the emergence of new approaches in nanobiotechnology and biomedicine as a result of their multifarious properties embedded within either the carbon nanotubes (CNTs) or magnetic parts. Numerous preparation techniques exists for functionalizing CNTs with magnetic nanoparticles, and these versatile strategies lay the ground for the generation of novel and versatile systems which are applicable to many industries and biological areas...
October 18, 2017: Artificial Cells, Nanomedicine, and Biotechnology
Badri Narayanan, Henry Chan, Alper Kinaci, Fatih G Sen, Stephen K Gray, Maria K Y Chan, Subramanian K R S Sankaranarayanan
A fundamental understanding of the inter-relationships between structure, morphology, atomic scale dynamics, chemistry, and physical properties of mixed metallic-covalent systems is essential to design novel functional materials for applications in flexible nano-electronics, energy storage and catalysis. To achieve such knowledge, it is imperative to develop robust and computationally efficient atomistic models that describe atomic interactions accurately within a single framework. Here, we present a unified Tersoff-Brenner type bond order potential (BOP) for a Co-C system, trained against lattice parameters, cohesive energies, equation of state, and elastic constants of different crystalline phases of cobalt as well as orthorhombic Co2C derived from density functional theory (DFT) calculations...
October 18, 2017: Nanoscale
Jonghoon Kim, Nohyun Lee, Taeghwan Hyeon
Molecular imaging enables us to non-invasively visualize cellular functions and biological processes in living subjects, allowing accurate diagnosis of diseases at early stages. For successful molecular imaging, a suitable contrast agent with high sensitivity is required. To date, various nanoparticles have been developed as contrast agents for medical imaging modalities. In comparison with conventional probes, nanoparticles offer several advantages, including controllable physical properties, facile surface modification and long circulation time...
November 28, 2017: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Zhihua Sun, Jian Li, Chengmin Ji, Junliang Sun, Maochun Hong, Junhua Luo
The incommensurate (IC) behaviors of ferroelectrics have been widely investigated in inorganic oxides as an exciting branch for aperiodic materials, whereas it still remains a great challenge to achieve such intriguing effects in organic systems. Here, we present that successive ordering of dynamic dipoles in an organic molecular ferroelectric, N-isopropylbenzylaminium trichloroacetate (1), enables unusual incommensurately modulated structures between its paraelectric phase (PEP) and ferroelectric phase (FEP)...
October 16, 2017: Journal of the American Chemical Society
Romain Gaillac, Pluton Pullumbi, Kevin A Beyer, Karena W Chapman, David A Keen, Thomas D Bennett, François-Xavier Coudert
Metal-organic frameworks (MOFs) are a family of chemically diverse materials, with applications in a wide range of fields, covering engineering, physics, chemistry, biology and medicine. Until recently, research has focused almost entirely on crystalline structures, yet now a clear trend is emerging, shifting the emphasis onto disordered states, including 'defective by design' crystals, as well as amorphous phases such as glasses and gels. Here we introduce a strongly associated MOF liquid, obtained by melting a zeolitic imidazolate framework...
October 9, 2017: Nature Materials
William B Homoky, Thomas Weber, William M Berelson, Tim M Conway, Gideon M Henderson, Marco van Hulten, Catherine Jeandel, Silke Severmann, Alessandro Tagliabue
Quantifying fluxes of trace elements and their isotopes (TEIs) at the ocean's sediment-water boundary is a pre-eminent challenge to understand their role in the present, past and future ocean. There are multiple processes that drive the uptake and release of TEIs, and properties that determine their rates are unevenly distributed (e.g. sediment composition, redox conditions and (bio)physical dynamics). These factors complicate our efforts to find, measure and extrapolate TEI fluxes across ocean basins. GEOTRACES observations are unveiling the oceanic distributions of many TEIs for the first time...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
C Mark Moore
The supply of a range of nutrient elements to surface waters is an important driver of oceanic production and the subsequent linked cycling of the nutrients and carbon. Relative deficiencies of different nutrients with respect to biological requirements, within both surface and internal water masses, can be both a key indicator and driver of the potential for these nutrients to become limiting for the production of new organic material in the upper ocean. The availability of high-quality, full-depth and global-scale datasets on the concentrations of a wide range of both macro- and micro-nutrients produced through the international GEOTRACES programme provides the potential for estimation of multi-element deficiencies at unprecedented scales...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Andrew M Watkins, Timothy W Craven, P Douglas Renfrew, Paramjit S Arora, Richard Bonneau
β-Amino acids offer attractive opportunities to develop biologically active peptidomimetics, either employed alone or in conjunction with natural α-amino acids. Owing to their potential for unique conformational preferences that deviate considerably from α-peptide geometries, β-amino acids greatly expand the possible chemistries and physical properties available to polyamide foldamers. Complete in silico support for designing new molecules incorporating non-natural amino acids typically requires representing their side-chain conformations as sets of discrete rotamers for model refinement and sequence optimization...
October 12, 2017: Structure
Yu-Ting Huang, Akhil Dodda, Daniel S Schulman, Amritanand Sebastian, Fu Zhang, Drew Buzzell, Mauricio Terrones, Shien-Ping Feng, Saptarshi Das
In this paper we provide insight into an anomalous corrosion process, referred to as electro-ablation (EA), which converts multi-layer flakes of transition metal diselenides like MoSe2 into their corresponding monolayers when micromechanically exfoliated on a conductive electrode and subsequently subjected to a high anodic potential inside a conventional electrochemical cell. Photoluminescence intensity map and scanning transmission electron microscopy (STEM) images confirmed the single crystalline nature and 2H-hexagonal lattice structure of the remnant monolayer MoSe2 flakes, indicating the superior corrosion stability of the monolayers compared to the bulk counterpart...
October 13, 2017: ACS Applied Materials & Interfaces
Xing Wu, Thomas Gantner, Manuel Koller, Martin Zeppenfeld, Sotir Chervenkov, Gerhard Rempe
Ultracold molecules represent a fascinating research frontier in physics and chemistry, but it has proven challenging to prepare dense samples at low velocities. Here we present a solution to this goal by a non-conventional approach dubbed cryofuge. It employs centrifugal force to bring cryogenically cooled molecules to kinetic energies below 1 K × kB in the laboratory frame, with corresponding fluxes exceeding 10(10)/s at velocities below 20 m/s. By attaining densities higher than 10(9)/cm(3) and interaction times longer than 25 ms in samples of fluoromethane as well as deuterated ammonia, we observe cold dipolar collisions between molecules and determine their collision cross sections...
October 12, 2017: Science
Jennifer R Lamb, Jason P Holland
The advent of hybrid cameras that combine magnetic resonance imaging with either single-photon emission computed tomography (SPECT/MRI) or positron-emission tomography (PET/MRI) has stimulated growing interest in developing multi-modality imaging probes. Countless options are available for fusing magnetically active species with positron- or gamma-ray emitting radionuclides. The initial problem is one of choice: which chemical systems are a suitable basis for developing hybrid imaging agents? Any attempt to answer this question must also address how the physical, chemical, and biological properties of a unified imaging agent can be tailored to ensure that optimum specificity and contrast is achieved simultaneously for both imaging modalities...
October 12, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
Paweł Myciński, Joanna Zarzecka, Agnieszka Skórska-Stania, Agnieszka Jelonek, Krzysztof Okoń, Maria Wróbel
The growing demand for various kinds of bone regeneration material has in turn increased the desire to find materials with optimal physical, chemical, and biological properties. The objective of the present study was to identify the proportions of ceramic and polylactide components in a bone substitute material prepared in collaboration with the Crystal Chemistry of Drugs Team of the Faculty of Chemistry at the Jagiellonian University, which would be optimal for bone regeneration processes. Another goal was to provide a histological analysis of the influence of a ceramic-polylactide composite on the healing of osseous defects in rabbits...
2017: Polish Journal of Pathology: Official Journal of the Polish Society of Pathologists
Carina A Dehner, Varun Kumar
A 23-year old graduate student presented with constant right upper quadrant pain, associated with nausea, fever chills and bilateral knee pain. On physical exam, splenomegaly, scleral icterus, and a maculopapular rash on the lower extremities were present. Laboratory results indicated an elevation in liver chemistries but preserved synthetic liver function. Detailed travel history revealed a recent trip along the east coast to visit dairy farms for a new business venture. After ruling out common etiologies for RUQ pain with elevated liver chemistries, a diagnosis of Brucellosis was made based on serum antibody titers and antibiotics were initiated...
October 9, 2017: International Journal of Infectious Diseases: IJID
Andreas Hirsch, Frank Hauke
The current state of the chemical functionalization of three types of single sheet 2D materials, namely, graphene, molybdenum disulfide (MoS2), and black phosphorus (BP) is summarized. Such 2D sheet polymers represent currently an emerging field at the interface of synthetic chemistry, physics, and materials science. Both covalent and non-covalent functionalization of sheet architectures allows for a systematic modification of their properties, i.e. an improvement of solubility and processability, the prevention of re-aggregation or a band gap tuning...
October 10, 2017: Angewandte Chemie
Sergey S Streltsov, Alexey O Shorikov, Sergey L Skornyakov, Alexander I Poteryaev, Daniel I Khomskii
Recent discovery of the pyrite FeO2, which can be an important ingredient of the Earth's lower mantle and which in particular may serve as an extra source of water in the Earth's interior, opens new perspectives for geophysics and geochemistry, but this is also an extremely interesting material from physical point of view. We found that in contrast to naive expectations Fe is nearly 3+ in this material, which strongly affects its magnetic properties and makes it qualitatively different from well known sulfide analogue - FeS2...
October 11, 2017: Scientific Reports
Geelsu Hwang, Bernard Koltisko, Xiaoming Jin, Hyun Koo
Surface-grown bacteria and production of an extracellular polymeric matrix modulate the assembly of highly cohesive and firmly attached biofilms, making them difficult to remove from solid surfaces. Inhibition of cell growth and inactivation of matrix-producing bacteria can impair biofilm formation and facilitate removal. Here, we developed a novel non-leachable antibacterial composite with potent antibiofilm activity by directly incorporating polymerizable imidazolium-containing resin (Anti Bacterial Resin with Carbonate linkage; ABR-C) into a methacrylate-based scaffold (ABR Modified Composite; ABR-MC) using an efficient yet simplified chemistry...
October 11, 2017: ACS Applied Materials & Interfaces
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