Read by QxMD icon Read

Physical Chemistry Chemical Physics: PCCP

Jejoong Yoo, Aleksei Aksimentiev
In contrast to ordinary polymers, the vast majority of biological macromolecules adopt highly ordered three-dimensional structures that define their functions. The key to folding of a biopolymer into a unique 3D structure or to an assembly of several biopolymers into a functional unit is a delicate balance between the attractive and repulsive forces that also makes such self-assembly reversible under physiological conditions. The all-atom molecular dynamics (MD) method has emerged as a powerful tool for studies of individual biomolecules and their functional assemblies, encompassing systems of ever increasing complexity...
March 16, 2018: Physical Chemistry Chemical Physics: PCCP
Sen Xu, Xiaofeng Fan, Jialin Liu, David J Singh, Qing Jiang, Weitao Zheng
We report an investigation of the interactions of Li with silicene. We find silicene to be a promising anode material for high energy density lithium-ion batteries. Based on first-principles calculations, we study the interaction between Li and silicene and explore the microscopic mechanism of Li storage on silicene. We find that Li ion is adsorbed on hollow sites at a very low concentration of less than 1.56%. At a high concentration of Li, the Li chains with up-down pairs on top sites become popular. With the formation of the Li chains, the local structure of silicene is modulated...
March 16, 2018: Physical Chemistry Chemical Physics: PCCP
D Xie, W F Zhu, H Cheng, Z Y Yao, M Li, Y L Zhao
A sensitive, and single step reaction assay of glycoproteins in antibody-free mode was proposed on a 4-mercapto-phenylboronic acid (4-MPBA) modified silver nanoparticle film (AgNF) by using surface enhanced Raman scattering (SERS). 4-MPBA/AgNF was designed both as a glycoprotein-specific recognition biosensor and as a Raman reporter for the SERS platform. Variation in the ratio I1574/I1586 for 4-MPBA/AgNF in response to glycoprotein capture constitutes the SERS assay which exhibits high sensitivity and selectivity against nonglycoproteins and is shown to function in complex samples...
March 16, 2018: Physical Chemistry Chemical Physics: PCCP
Tadashi Sugahara, Yuichiro Takamatsu, Avinash Bhadani, Masaaki Akamatsu, Kenichi Sakai, Masahiko Abe, Hideki Sakai
In this study, we synthesize a novel oleic acid-based gemini surfactant with carboxylate headgroups, and study the effect of stereochemistry (anti- vs. syn-) on self-aggregation properties in water. We investigate these properties using phase diagrams, static surface tension, and one-dimensional and two-dimensional nuclear magnetic resonance (NMR) measurements. We find that a phase transition from a hexagonal liquid crystal (H1) phase to a lamellar liquid crystal (Lα) phase occurs at a lower surfactant concentration in the syn form, when compared with the anti form...
March 16, 2018: Physical Chemistry Chemical Physics: PCCP
Dongshuai Hou, Tiejun Yang, Jinhui Tang, Shaochun Li
Graphene oxide (GO) reinforced cement nanocomposites open up a new path for sustainable concrete design. In this paper, reactive force-field molecular dynamics was utilized to investigate the structure, reactivity and interfacial bonding of calcium silicate hydrate (C-S-H)/GO nanocomposite functionalized by hydroxyl (C-OH), epoxy (C-O-C), carboxyl (COOH) and sulfonic (SO3 H) groups with a coverage of 10%. The silicate chains in the hydrophilic C-S-H substrate provided numerous non-bridging oxygen sites and counter ions (Ca ions) with high reactivity, which allowed interlayer water molecules to dissociate into Si-OH and Ca-OH...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Sergej Friesen, Sebastian Krickl, Magdalena Luger, Andreas Nazet, Glenn Hefter, Richard Buchner
Aqueous solutions of five lanthanide salts: LaCl3 , La(NO3 )3 , La2 (SO4 )3 , Eu(NO3 )3 and Eu2 (SO4 )3 have been studied at 25 °C by dielectric relaxation spectroscopy over the frequency range 0.05 ≤ ν/GHz ≤ 89. Detailed analysis of the solvent-related modes located at higher frequencies showed that both La3+ and Eu3+ are strongly hydrated, even including partial formation of a third hydration shell similar to that of Al3+ (aq). Up to two solute-related modes could be detected at lower frequencies, due to the formation of various types of 1 : 1 ion pairs (IPs)...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Wiktor Zierkiewicz, Mariusz Michalczyk, Steve Scheiner
A series of TF4 and ZF5 molecules (T = Si, Ge, Sn and Z = P, As, Sb) were allowed to engage in tetrel and pnicogen bonds, respectively, with NH3 , pyrazine, and HCN. The interaction energies are quite large, approaching 50 kcal mol-1 in some cases. The formation of each complex is accompanied by substantial geometrical deformation of the Lewis acid to accommodate the approaching base. The energy associated with this monomer rearrangement is the largest for the smaller central atoms Si and P, where it exceeds 20 kcal mol-1 ...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Helena Passos, Teresa B V Dinis, Emanuel V Capela, Maria V Quental, Joana Gomes, Judite Resende, Pedro P Madeira, Mara G Freire, João A P Coutinho
In the past decade, the remarkable potential of ionic-liquid-based aqueous biphasic systems (IL-based ABSs) to extract and purify a large range of valued-added biocompounds has been demonstrated. However, the translation of lab-scale experiments to an industrial scale has been precluded by a poor understanding of the molecular-level mechanisms ruling the separation or partition of target compounds between the coexisting phases. To overcome this limitation, we carried out a systematic evaluation of specific interactions, induced by ILs and several salts used as phase-forming components, and their impact on the partition of several solutes in IL-based ABSs...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
A H Reshak
Comprehensive ab initio calculations from first- to second-principles methods are performed to investigate the suitability of non-centro-symmetric CdLa2 S4 and CdLa2 Se4 to be used as active photocatalysts under visible light illumination. The calculations reveal the direct band gap nature of both compounds with large absorption coefficients (104 -105 cm-1 ). The absorption edges of CdLa2 S4 and CdLa2 Se4 occur at λ = 579.3 nm and λ = 670.1 nm, and the optical band gaps are estimated to be 2.14 eV and 1.85 eV for CdLa2 S4 and CdLa2 Se4 , respectively...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Thomas J Wood, Joshua W Makepeace, William I F David
Manganese and its nitrides have recently been shown to co-catalyse the ammonia decomposition reaction. The nitriding reaction of manganese under ammonia decomposition conditions is studied in situ simultaneously by thermogravimetric analysis and neutron diffraction. Combining these complementary measurements has yielded information on the rate of manganese nitriding as well as the elucidation of a gamut of different manganese nitride phases. The neutron diffraction background was shown to be related to the extent of the ammonia decomposition and therefore the gas composition...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Milad Rayka, Mohammad Goli, Shant Shahbazian
A set of effective electronic-only Kohn-Sham (EKS) equations are derived for the muonic molecules (containing a positively charged muon), which are completely equivalent to the coupled electronic-muonic Kohn-Sham equations derived previously within the framework of the nuclear-electronic orbital density functional theory (NEO-DFT). The EKS equations contain effective non-coulombic external potentials depending on parameters describing the muon's vibration, which are optimized during the solution of the EKS equations making the muon's KS orbital reproducible...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Dehbia Benkerrou, Matteo Ceccarelli
One of the greatest health threats facing modern medicine is the emergence of new bacterial strains which are increasingly resistant to almost all currently available antibiotics. According to a CDC (Center for Disease Control and Prevention) report published in 2013, 63% of Acinetobacter species have been identified as Multidrug resistant strains. As for other Gram-negative bacteria, the presence of an outer membrane increases the intrinsic resistance of A. baumannii to most antibiotics. The outer membrane of A...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Beatriz Bernardo-Maestro, Elisa Garrido-Martín, Fernando López-Arbeloa, Joaquín Pérez-Pariente, Luis Gómez-Hortigüela
In an attempt to promote the crystallization of chiral inorganic frameworks, we explore the ability of chiral (1R,2S)-ephedrine and its diastereoisomer (1S,2S)-pseudoephedrine to act as organic building blocks for the crystallization of hybrid organo-inorganic aluminophosphate frameworks in the presence of fluoride. These molecules were selected because of their particular molecular asymmetric structure, which enables a rich supramolecular chemistry and a potential chiral recognition phenomenon during crystallization...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
M R Kholghy, G A Kelesidis, S E Pratsinis
Nucleation is an important, yet poorly understood step in soot formation. Here, the importance of reactive PAH dimerization in reducing soot nucleation reversibility is investigated by simulating soot formation in a so-called "nucleation" flame (P. Desgroux et al., Combust. Flame, 2017, 184, 153-166). There, inception of soot particles is prolonged at minimal subsequent growth. With only reversible PAH dimerization, the simulated soot concentration is negligible. Accounting however for PAH chemical bond formation after physical dimerization, stabilizes dimers by covalent bonds and increases the soot concentration by four orders of magnitude, in good agreement with Laser Induced Incandescence measurements...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
F Guégan, W Lamine, H Chermette, C Morell
In a recent article Polanco-Ramirez et al. proposed new definitions of local chemical potential and local hardness starting from the first derivative of the energy with respect to the number of electrons and a smart use of the chain rule. In this comment we show that this derivation appears naturally in the Taylor expansion of the energy, showing that the construction of Polanco-Ramirez et al. is not artificially built.
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Daniel T Allen, Nikou Damestani, Yussif Saaka, M Jayne Lawrence, Christian D Lorenz
A series of atomistic molecular dynamics simulations were performed for investigating the interactions between three different testosterone-based compounds (testosterone (T), testosterone propionate (TP) and testosterone enanthate (TE)) and sodium dodecyl sulphate (SDS) and ammonium dodecyl sulphate (ADS) monolayers, which vary only in the sodium or ammonium counterions used to neutralise the sulphate headgroup. These simulations were used to investigate how the structural and interfacial properties of the monolayer were affected by changing the number of drug molecules present per monolayer, and the chemical nature of the surfactant counterions and the testosterone-based compounds...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Chiho Watanabe, Miho Yanagisawa
Micrometric membrane confinements and macromolecular crowding of cytoplasm are key factors that regulate molecular diffusion in live cells. Previous studies have shown that macromolecular crowding delays molecular diffusion. However, the effect of cell-size confinement on diffusion in the crowding environment is yet to be elucidated. Using fluorescence correlation spectroscopy (FCS), we analyzed protein diffusion in microdroplets containing polymer solution covered with lipid membranes that mimic cells. As a result, we found that a synergistic condition of crowding and micrometric confinement results in accelerated protein diffusion on a sub-millisecond time scale...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
A S Vikulina, N A Feoktistova, N G Balabushevich, A G Skirtach, D Volodkin
Porous vaterite CaCO3 crystals are nowadays extensively used as high-capacity bio-friendly sacrificial templates for the fabrication of such protein-containing nano- and micro-particles as capsules and beads. The first step in the protein encapsulation is performed through loading of the protein molecules into the crystals. Co-synthesis is one of the most useful and simple methods proven to effectively load crystals with proteins; however, the loading mechanism is still unknown. To understand the mechanism, in this study, we focus on the loading of a model protein catalase into the crystals by means of adsorption into pre-formed crystals (ADS) and co-synthesis (COS)...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Krzysztof B Beć, Yusuke Morisawa, Kenta Kobashi, Justyna Grabska, Ichiro Tanabe, Erika Tanimura, Harumi Sato, Marek J Wójcik, Yukihiro Ozaki
We investigated the surface (<50 nm) of poly(3-hydroxybutyrate) (PHB) and its nanocomposite with graphene by attenuated total reflection far- and deep-ultraviolet (ATR-FUV-DUV; 145-300 nm; 8.55-4.13 eV) spectroscopy and quantum mechanical calculations. The major absorption of polymers occurs in FUV and is related to Rydberg transitions. ATR-FUV-DUV spectroscopy allows for direct measurements of these transitions in the solid phase. Using ATR-FUV-DUV spectroscopy, periodic density functional theory (DFT) and time-dependent DFT (TD-DFT), we explained the origins of the FUV-DUV absorption of PHB and provided insights into structural changes of PHB which occur upon formation of a graphene nanocomposite and upon heating of the pure polymer...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Esther Heid, Patricia A Hunt, Christian Schröder
Ground and excited state dipoles and polarizabilities of the chromophores N-methyl-6-oxyquinolinium betaine (MQ) and coumarin 153 (C153) in solution have been evaluated using time-dependent density functional theory (TD-DFT). A method for determining the atomic polarizabilities has been developed; the molecular dipole has been decomposed into atomic charge transfer and polarizability terms, and variation in the presence of an electric field has been used to evaluate atomic polarizabilities. On excitation, MQ undergoes very site-specific changes in polarizability while C153 shows significantly less variation...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"