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Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry

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https://www.readbyqxmd.com/read/29341365/how-and-why-helium-permeates-non-porous-arsenolite-under-high-pressure
#1
Piotr Aleksander Guńka, Michał Hapka, Michael Hanfland, Maciej Dranka, Grzegorz Chałasiński, Janusz Zachara
Investigations into the helium permeation of arsenolite, the cubic, molecular arsenic(III) oxide polymorph As₄O₆, were carried out in order to understand how and why arsenolite helium clathrate As₄O₆∙2He is formed. High-pressure synchrotron X-ray diffraction experiments on arsenolite single crystals revealed that the permeation of helium into non-porous arsenolite depends on the time during which the crystal is subjected to high pressure and on the crystal history. The single crystal was totally transformed into As₄O₆·2He within 45 h under 5 GPa...
January 17, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29334171/dft-studies-on-the-reaction-mechanism-for-direct-cyclization-of-linear-c5-c6-and-c7-alkenes-over-h-itq-13-zeolite
#2
Hong Ma, Yanyan Chen, Zhihong Wei, Sen Wang, Zhangfeng Qin, Mei Dong, Junfen Li, Jianguo Wang, Weibin Fan
Although dienes or trienes have been shown to be possible precursors for cyclization, direct cyclization of alkenes or alkoxides has not been systematically studied yet. Thus, the reaction mechanism of cyclization of linear alkenes was investigated here with H-ITQ-13 by density functional theory considering dispersive interactions (DFT-D). The similar free energy of different linear alkoxides of the same carbon number suggests that they can co-exist in the H-ITQ-13 intersection at 673.15 K during MTO process...
January 15, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29328542/towards-the-detection-of-explosive-taggants-microwave-and-millimetre-wave-gas-phase-spectroscopies-of-3-nitrotoluene
#3
Anthony Roucou, Isabelle Kleiner, Manuel Goubet, Sabath Bteich, Gaël Mouret, Robin Bocquet, Francis Hindle, W Leo Meerts, Arnaud Cuisset
The monitoring of gas phase mononitrotoluenes is crucial for defence, civil security and environmental interests since they are used as taggant for TNT detection and in the manufacturing of industrial compounds such as dyestuffs. In this study, we have succeeded to measure and analyse at high resolution a room temperature rotationally resolved millimeter-wave spectrum of meta-nitrotoluene(3-NT). Experimental and theoretical difficulties have been overcome, in particular, those related to the low vapour pressure of 3-NT and to the presence of a CH$_3$ internal rotation in an almost free rotation regime ($V_3$=6...
January 12, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29327816/brain-cortex-microglia-derived-exosomes-novel-nanoparticles-for-glioma-therapy
#4
Adriana-Natalia Murgoci, Dasa Cizkova, Petra Majerova, Eva Petrovova, Lubomir Medvecky, Isabelle Fournier, Michel Salzet
The function and integrity of nervous system require interactive exchanges among neurons and glial cells. Exosomes and other extracellular vesicles (EVs) are emerging as a key mediator of intercellular communication, capable to transfer nucleic acids, proteins and lipids, influencing numerous functional and pathological aspects of both donor and recipient cells. The immune response mediated by microglia derived exosomes are most prominently involved in the spread of neuroinflammation, neurodegenerative disorders and brain cancer...
January 12, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29327408/the-photoconversion-of-phytochrome-includes-an-unproductive-shunt-reaction-pathway
#5
Peter Hildebrandt, David Buhrke, Norbert Michael, Uwe Kuhlmann
Phytochromes are modular bimodal photoswitches that control gene expression for morphogenetic processes in plants. These functions are triggered by the photoinduced conversions between the inactive and active states of the photosensory module, denoted as Pr and Pfr, respectively. In the present time-resolved resonance Raman spectroscopic study of bacterial representatives of this photoreceptor family, we demonstrate that these phototransformations do not represent linear processes but include a branching reaction back to the initial state, prior to (de)activation of the output module...
January 11, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29323450/theoretical-investigation-of-the-ir-spectrum-of-5-bromo-2-4-pentadiynenitrile-brc5n-in-the-region-between-50-to-4500-cm-1-from-a-ccsd-t-b3lyp-anharmonic-potential
#6
Claude Pouchan, Panagiotis Karamanis, Alain Dargelos
On the grounds of a hybrid CCSD(T)/B3LYP/aug-cc-pVTZ anharmonic potential and the use of a variational and variational-perturbational methods, the IR spectra of 5-bromo-2,4-pentadiynenitrile is revisited in the mid-infrared region up to 4500 cm-1. A position and intensity analysis of our theoretical results allow us to assign the fundamental bands together with their combinations and overtones, in the aforementioned range of frequencies. The main objective of this paper is to give an 'a priori' complete IR spectrum of BrC5N which can be used as a guide of the low-intensity bands in areas not completely studied so far...
January 11, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29319220/drug-induced-micelle-to-vesicle-transition-of-a-cationic-gemini-surfactant-potential-applications-in-drug-delivery
#7
Sargam M Rajput, Sugam Kumar, Vinod K Aswal, Omar El Seoud, Naved Anjum I Malek, Suresh Kumar Kailasa
The impetus for the sustained interest in the formation of vesicles is their potential application as efficient drug delivery systems. A simple approach for ionic surfactants is to add a vesicle-inducing drug of opposite charge. In ionic gemini surfactants (GS) two molecules are covalently linked with a "spacer". Considering drug-delivery, GS are more attractive candidates than their single-chain counterparts because of their high surface activity and the effect on the physico-chemical properties of their solutions caused by changing the length of the spacer, and inclusion of heteroatoms therein...
January 10, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29316144/quantitative-comparison-of-enzyme-immobilization-strategies-for-glucose-biosensing-in-real-time-using-fast-scan-cyclic-voltammetry-coupled-with-carbon-fiber-microelectrodes
#8
Samantha K Smith, Leyda Z Lugo-Morales, Christina Tang, Saahj P Gosrani, Christie A Lee, James G Roberts, Stephen W Morton, Gregory S McCarty, Saad A Khan, Leslie A Sombers
Electrochemical monitoring of non-electroactive species requires a biosensor that is stable and selective, with sensitivity to physiological concentrations of targeted analytes. We have combined glucose oxidase-modified carbon-fiber microelectrodes with fast-scan cyclic voltammetry for real-time measurements of glucose fluctuations in brain tissue. Work presented herein quantitatively compares three approaches to enzyme immobilization on the microelectrode surface - physical adsorption, hydrogel entrapment, and entrapment in electrospun nanofibers...
January 9, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29316094/integrated-multifunctional-micelles-co-self-assembled-from-polypeptides-conjugated-with-natural-ferulic-acid-and-lipoic-acid-for-efficient-and-bioresponsive-doxorubicin-delivery
#9
Zhiyuan Zhong, Tao Chen, Min Qiu, Jian Zhang, Huanli Sun, Chao Deng
How to develop safe, easily accessible, and multifunctional nanocarriers is a big theme for nanomedicine research. Here, integrated multifunctional micelles (IMM) were developed by co-self-assembly of poly(ethylene glycol)-b-poly(L-lysine) derivatives with natural ferulic acid or lipoic acid. FA confers IMM with intrinsic antitumor activity, improved loading of doxorubicin (DOX) via π-π stacking, and reduced DOX cardiotoxicity. LA provides IMM with reversible crosslinking property which leads to a high colloidal stability with inhibited drug leakage and triggered intracellular DOX release...
January 9, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29316128/ranking-power-of-the-sqm-cosmo-scoring-function-on-carbonic-anhydrase-ii-inhibitor-complexes
#10
Adam Pecina, Jiri Brynda, Lukas Vrzal, Ramachandran Gnanasekaran, Magdalena Horejsi, Saltuk Eyrilmez, Jan Rezac, Martin Lepsik, Pavlina Rezacova, Pavel Hobza, Pavel Majer, Vaclav Veverka, Jindrich Fanfrlik
Accurate prediction of protein-ligand binding affinities is essential for hit-to-lead optimization and virtual screening. The reliability of scoring functions can be improved by implementing of quantum effects. Here, we demonstrate the ranking power of the semiempirical quantum mechanics (SQM)/implicit solvent (COSMO) scoring function using a challenging set of 10 inhibitors binding to carbonic anhydrase II via Zn2+ in the active site. This new dataset consists of the high-resolution (1.1 - 1.4 Å) crystal structures and experimentally determined Ki values...
January 8, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29316166/intraparticle-diffusional-effects-vs-site-effects-on-reaction-pathways-in-liquid-phase-cross-aldol-reactions
#11
Koushik Ponnuru, Jinesh C Manayil, Hong Je Cho, Wei Fan, Karen Wilson, Friederike Jentoft
Chemo- and regioselectivity in a heterogeneously catalyzed cross aldol reaction were directed by tuning the nature of the sites, textural properties and reaction conditions. Catalysts included sulfonic-acid functionalized resins or SBA-15 with varying particle size or pore diameter, H-BEA zeolites, and Sn-BEA zeotype; conditions were 25 °C to 170 °C in organic media. Benzaldehyde and 2-butanone yielded branched (reaction at -CH2- of butanone) and linear (reaction at -CH3) addition and condensation products; and fission of the branched aldol led to β-methyl styrene and acetic acid...
January 7, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29316116/exploring-molecular-and-thermodynamic-properties-of-zwitterions-vs-ionic-liquids-a-comprehensive-computational-analysis-to-develop-advanced-separation-processes
#12
Daniel Moreno, Maria Gonzalez-Miquel, Victor R Ferro, Jose Palomar
Zwitterions ionic liquids (ZIs) are compounds in which both counterions are covalently tethered, conferring them with unique characteristics; however, most of their properties are still unknown, remaining a bottleneck to exploit practical applications. Herein, molecular and fluid properties of ZIs and their mixtures are explored by means of quantum chemical analysis based on density functional theory (DFT) and COSMO-RS method, and compared against homologous ILs, to provide a comprehensive overview on the effect of the distinct structures on their physicochemical and thermodynamic behavior...
January 7, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29316109/a-comparative-study-on-the-photophysics-and-photochemistry-of-xanthene-dyes-in-the-presence-of-pamam-dendrimers
#13
Ernesto Arbeloa, Carlos Mario Previtali, Sonia Graciela Bertolotti
The photophysical and photochemical properties of the xanthene dyes Eosin-Y (Eos), Erythrosin-B (Ery) and Rose Bengal (RB) were evaluated in the presence of amino-terminated polyamido-amine (PAMAM) dendrimers of relatively high generations (G3-G5), in alkaline aqueous solution. UV-Vis absorption and fluorescence spectra of the dyes showed bathochromic shifts, which correlated with the size of the dendrimer. From absorption data binding constant (Kbind) were calculated. High Kbind values resulted, indicating a strong interaction between both molecules...
January 7, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29316151/sub-ensemble-monitoring-of-dna-strand-displacement-using-multiparameter-single-molecule-fret
#14
Laura Baltierra-Jasso, Michael Morten, Steven William Magennis
Non-enzymatic DNA strand displacement is an important mechanism in dynamic DNA nanotechnology. Here we show that the large parameter space that is accessible by single-molecule FRET is ideal for the simultaneous monitoring of multiple reactants and products of DNA strand exchange reactions. We monitored the strand displacement from double-stranded DNA (dsDNA) by single-stranded DNA (ssDNA) at 37 °C; the data were modelled as a second-order reaction approaching equilibrium, with a rate constant of ca. 10 M-1 s-1...
January 5, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29314603/investigating-protein-ligand-interactions-by-solution-nmr-spectroscopy
#15
Walter Becker, Krishna Chaitanya Bhattiprolu, Nina Gubensäk, Klaus Zangger
Protein-ligand interactions are of fundamental importance in almost all processes in living organisms. The ligands comprise small molecules, drugs or biological macromolecules and their interaction strength varies over several orders of magnitude. Solution NMR spectroscopy offers a large repertoire of techniques to study such complexes. Here we give an overview of the different NMR approaches available. The information they provide ranges from the simple information about the presence of binding or epitope mapping to the complete 3D structure of the complex...
January 4, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29314565/modelling-the-interaction-of-co-with-flexible-graphene-from-coupled-cluster-calculations-to-molecular-dynamics-simulations
#16
Jake Wilson, Noelia Faginas-Lago, Jelle Vekeman, Inmaculada García Cuesta, José Sánchez-Marín, Alfredo Sánchez de Merás
The interaction of CO with graphene has been studied at different theoretical levels. Quantum mechanical calculations on finite graphene models using coronene for coupled cluster calculations and circumcoronene for B97D calculations showed that there exists no preferential site for adsorption and that the most important factor is the orientation of CO relative to graphene. The parallel orientation is preferred, with binding energies around 9 kJ mol-1 at the CCSD(T) and B97D levels, in good agreement with experimental findings...
January 4, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29314507/improved-photoactivity-of-pyroxene-silicates-by-cation-substitutions
#17
Merid Legesse Belayneh, Heesoo Park, Fedwa El Mellouhi, Sergey N Rashkeev, Sabre Kais, Fahhad H Alharbi
We investigated the possibility of band structure engineering of pyroxene silicates with chemical formula A+1B+3Si2O6 by proper cation substitution. Typically, bandgaps of naturally formed pyroxene silicates such as NaAlSi2O6 are quite high (~5 eV). Therefore, it is important to find a way to reduce bandgaps for these materials below 3 eV to make them usable for optoelectronic applications operating at visible light range of the spectrum. Using first-principles calculations, we found that appropriate substitutions of both A+ and B3+ cations can reduce the bandgaps of these materials to as low as 1...
January 4, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29314466/covalent-bonding-of-chlorogenic-acid-induces-structural-modifications-on-sunflower-proteins
#18
Costas Nikiforidis, Dimitris Karefyllakis, Stavroula Salakou, J Harry Bitter, Atze Jan Van der Goot
Proteins and phenols coexist in the confined space of plant cells leading to reactions between them which result in new covalently bonded complex molecules. This kind of reactions has been widely observed during storage and processing of plant materials. However, the nature of the new complex molecules and their physico-chemical properties are largely unknown. Therefore we investigated the structural characteristics of covalent bonded complexes between highly pure sunflower protein isolate (SFPI, 94 wt%) and the dominant phenol in the confined space of a sunflower seed cell (chlorogenic acid, CGA)...
January 4, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29314623/mapping-perfluoroalkyl-effects-in-togni-type-reagents-by-thermolysis
#19
Nico Santschi, Dmitry Katayev, Roxan Calvo, Benson J Jelier
We present the thermolysis of cyclic hypervalent iodine(III) perfluoroalkyl transfer reagents carried out in standard GC-MS instrumentation. Through heating, these structures undergo fragmentation to afford perfluoroalkyl radicals F2n+1Cn* and each reagent can be characterized by means of a threshold temperature, TIP(n). This parameter TIP(n) not only reflects the stability of the F2n+1Cn-I bond, but potentially also carries information regarding fundamental properties of the linear perfluoroalkyl chains.
January 3, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29314495/simple-green-and-high-yield-production-of-boron-based-nanostructures-with-diverse-morphologies-by-dissolution-and-recrystallization-of-layered-magnesium-diboride-crystals-in-water
#20
Harini Gunda, Saroj Kumar DAS, Kabeer Jasuja
Layered metal diborides that contain metal atoms sandwiched in between boron honeycomb planes offer a rich opportunity to access graphenic forms of boron. We have recently demonstrated that Magnesium diboride (MgB₂) can be exfoliated by ultrasonication in water to yield boron-based nanosheets. However, the knowledge on the fate of metal boride crystals in an aqueous phase is still in its incipient stages. This work presents our preliminary findings on the discovery that MgB₂ crystals can undergo dissolution in water under ambient conditions to result in precursors, which upon aging, undergo a non-classical crystallization preferentially growing in lateral directions by two-dimensional (2D) oriented attachments...
January 3, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
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