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Peter Werner Roesky, Claude Kiefer, Sebastian Bestgen, Michael T Gamer, Michael Kühn, Sergei Lebedkin, Florian Weigend, Manfred M Kappes
Bis-phenylpropynyl-functionalized imidazolium salts and their corresponding gold and copper NHC complexes were prepared in order to investigate their potential application for the synthesis of heterometallic coinage metal compounds. By transmetallation reactions with different precious metal sources including copper and silver phenylacetylides [MCCPh]x (M = Cu, Ag), polynuclear molecules were obtained, which were further investigated for their photoluminescence properties. Additionally, one gold NHC complex was post-functionalized by autocatalytic hydration of the alkynyl side chains...
October 25, 2016: Chemistry: a European Journal
Essam Hammam, Jalal Basahi, Iqbal Ismail, Ibrahim Hassan, Talal Almeelbi
The excited state hydrogen bonding dynamics of BBVN in hydrogen donating methanol solvent was explored at the TD-BMK/cc-pVDZ level of theory with accounting for the bulk environment effects at the polarizable continuum model (PCM). The heteroatoms of the BBVN laser dye form hydrogen bonds with four methanol molecules. In the formed BBVN-(MeOH)4 complex, the A-type hydrogen bond (N…HO), of an average strength of 25kJmol(-1), is twofold stronger than the B-type (O…HO) one. Upon photon absorption, the total HB binding energy increases from 78...
October 17, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Ricardo Vega Monroy, Guillermo Salazar Cohen
In this work we present a theory, which is able to explain the non-monotonic decreasing behavior (observed in experimental data(1-11)) of the graphene terahertz conductivity with the increase of the field frequency. In this connection, the displacement of the structure of topological states inside the energy band gap, which appears in graphene due to the strong photon-electron coupling, and the narrowing of this gap, as result of electron transitions from bound photon-dressed electron states to extended states outside the energy gap driven by the field frequency, lead to a periodic change of singularities near the edge of the band gap, resulting in subtle quantum oscillations of the dynamical terahertz conductivity...
October 25, 2016: Nano Letters
Olga A Yakovina, Alexander S Lisitsyn
Metal clusters with sizes below 1 nm excite great scientific interest, but the main information on their properties still comes from quantum mechanics modeling and costly physical methods of limited availability. We have studied ultradispersed Pt/γ-Al2O3 samples with TPD and complementary adsorption/desorption techniques and observed a strong influence of H2-treatment conditions (PH2 ≤ 1 bar; 200 K ≤ T ≤ 470 K) on the H2-TPD profile of Pt/γ-Al2O3. The results corroborate recent theoretical and spectroscopic studies predicting alterations in the structure of Pt nanoclusters under H2 but reveal that the restructuring needs to overcome continuous activation barriers and leads both to an increase in surface coverage and strengthening of Pt-H bonds...
October 25, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Otmar M Ten Kate, Rong-Jun Xie, Chun-Yun Wang, Shiro Funahashi, Naoto Hirosaki
Novel Sr2-yEuyB2-2xSi2+3xAl2-xN8+x phosphors were investigated as a function of the boron and aluminum over silicon ratio and as a function of the Eu(2+) concentration. Samples were prepared via solid-state reaction synthesis by carefully controlling the synthesis conditions and composition. At high boron and aluminum content, that is, x = 0, a Eu(2+) 5d-4f emission is observed of which the maximum shifts from 595 nm for low Eu concentrations (y = 0.005) toward 623 nm for high Eu concentrations (y = 0.5). The samples can be excited by UV or blue light up to ∼475 nm...
October 25, 2016: Inorganic Chemistry
Huanli Dong, Wenping Hu
Conjugated polymers have attracted the world's attentions since their discovery due to their great promise for optoelectronic devices. However, the fundamental understanding of charge transport in conjugated polymers remains far from clear. The origin of this challenge is the natural disorder of polymers with complex molecular structures in the solid state. Moreover, an effective way to examine the intrinsic properties of conjugated polymers is absent. Optoelectronic devices are always based on spin-coated films...
October 25, 2016: Accounts of Chemical Research
Mostafa Fakhraee, Mohammad Reza Gholami
The effects of ester addition on structural and dynamic properties of biodegradable ILs composed of the 1-(alkoxycarbonyl)-3-alkylimidazolium cation ([C1COOCnC1im](+), n = 1, 2, 4) coupled with [Br](-), [NO3](-), [BF4](-), [PF6](-), [TfO](-), and [Tf2N](-) are explored using the molecular dynamics (MD) simulations and quantum theory of atoms in molecules (QTAIM) at 400 K. Formation of the intramolecular H bonds between O atoms of the ester group and H atoms of the imidazolium ring as well as the nearest H atom of the alkyl chain to the ester group are disclosed from reduced density gradient (RDG) results...
October 25, 2016: Journal of Physical Chemistry. B
Jin-Shi Xu, Kai Sun, Yong-Jian Han, Chuan-Feng Li, Jiannis K Pachos, Guang-Can Guo
The realization of Majorana zero modes is in the centre of intense theoretical and experimental investigations. Unfortunately, their exchange that can reveal their exotic statistics needs manipulations that are still beyond our experimental capabilities. Here we take an alternative approach. Through the Jordan-Wigner transformation, the Kitaev's chain supporting two Majorana zero modes is mapped to the spin-1/2 chain. We experimentally simulated the spin system and its evolution with a photonic quantum simulator...
October 25, 2016: Nature Communications
Mohammad Goli, Shant Shahbazian
Recently, it has been demonstrated that the domain-averaged exchange-correlation energies, V(xc) , are capable of tracing the covalent character of atom-atom interactions unequivocally and thus pave the way for detailed bonding analysis within the context of the quantum theory of atoms in molecules (QTAIM) [M. García-Revilla, E. Francisco, P. L. Popelier, A. Martín Pendás, ChemPhysChem 2013, 14, 1211-1218]. Herein, the concept of V(xc) is extended within the context of the newly developed multicomponent QTAIM (MC-QTAIM)...
October 25, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Andrew Palii, Boris Tsukerblat
In this article we consider two coupled tetrameric mixed-valence (MV) units accommodating electron pairs, which play the role of cells in molecular quantum cellular automata. It is supposed that the Coulombic interaction between instantly localized electrons within the cell markedly inhibits the transfer processes between the redox centers. Under this condition, as well as due to the vibronic localization of the electron pair, the cell can encode binary information, which is controlled by neighboring cells...
October 25, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Tsung Sheng Kao, Yu-Hsun Chou, Kuo-Bin Hong, Jiong-Fu Huang, Chun-Hsien Chou, Hao-Chung Kuo, Fang-Chung Chen, Tien-Chang Lu
Solution-processed organic-inorganic perovskites are fascinating due to their remarkable photo-conversion efficiency and great potential in the cost-effective, versatile and large-scale manufacturing of optoelectronic devices. In this paper, we demonstrate that the perovskite nanocrystal sizes can be simply controlled by manipulating the precursor solution concentrations in a two-step sequential deposition process, thus achieving the feasible tunability of excitonic properties and lasing performance in hybrid metal-halide perovskites...
October 25, 2016: Nanoscale
Mariete B Moreira, Camila F N Da Silva, Rafaela B P Pesci, Victor M Deflon, Sofia Nikolaou
We synthesized and characterized a series of oxo-centered carbonyl-triruthenium complexes with the general formula [Ru3O(CH3COO)6(L)2(CO)], where L = 2,6-dimethylpyrazine (dmpz) (1), isonicotinamide (adpy) (2), 4-acetylpyridine (acpy) (3), 3-methylpyridine (3-pic) (4), 4-methylpyridine (4-pic) (5), 4-tert-butylpyridine (4-tbpy) (6), 4-(dimethyl)aminopyridine (dmap) (7), or 4-aminopyridine (ampy) (8); we also investigated the photoreactivity of these complexes. Single-crystal X-ray diffraction helped to elucidate the structures of 1·H2O, 7·C2H4Cl2, and 8...
October 25, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Yan Peng, Tilmann Bodenstein, Karin Fink, Valeriu Mereacre, Christopher E Anson, Annie K Powell
The single ion magnetic properties of Co(ii) are affected by the details of the coordination geometry of the ion. Here we show that a geometry close to trigonal prismatic which arises when the ligand 6,6'-((1Z)-((piperazine-1,4-diylbis(propane-3,1-diyl))bis(azanylylidene))bis(methanylylidene))bis(2-methoxyphenol) coordinates to Co(ii) does indeed lead to enhanced single-ion behaviour as has previously been predicted. Synthesis of the compound, structural information, and static as well as dynamic magnetic data are presented along with an analysis using quantum chemical ab initio calculations...
October 25, 2016: Physical Chemistry Chemical Physics: PCCP
Thomas J Hopkins, Karthik Raghunathan, Atilio Barbeito, Mary Cooter, Mark Stafford-Smith, Rebecca Schroeder, Katherine Grichnik, Richard Gilbert, Solomon Aronson
BACKGROUND: In this study, we examined the association between American Society of Anesthesiologists Physical Status (ASA PS) designation and 48-h mortality for both elective and emergent procedures in a large contemporary dataset (patient encounters between 2009 and 2014) and compared this association with data from a landmark study published by Vacanti et al. in 1970. METHODS: Patient history, hospital characteristics, anesthetic approach, surgical procedure, efficiency and quality indicators, and patient outcomes were prospectively collected for 732,704 consecutive patient encounters between January 1, 2009, and December 31, 2014, at 233 anesthetizing locations across 19 facilities in two US states and stored in the Quantum™ Clinical Navigation System (QCNS) database...
2016: Perioperative Medicine
Xiulan Zhang, Yonggang Zhu, Xie Li, Xuhong Guo, Bo Zhang, Xin Jia, Bin Dai
A simple, fast and low-cost method for dopamine (DA) detection based on turn-on fluorescence using resorcinol is developed. The rapid reaction between resorcinol and DA allows the detection to be performed within 5 min, and the reaction product (azamonardine) with high quantum yield generates strong fluorescence signal for sensitive optical detection. The detection exhibits a high sensitivity to DA with a wide linear range of 10 nM-20 μM and the limit of detection is estimated to be 1.8 nM (S/N = 3)...
November 9, 2016: Analytica Chimica Acta
Pan Deng, Li-Qiang Lu, Wei-Cheng Cao, Xi-Ke Tian
The phosphorescent l-cysteine modified manganese-doped zinc sulfide quantum dots (l-cys-MnZnS QDs) was developed for a highly sensitive detection of permanganate anions (MnO4(-)). l-cys-MnZnS QDs, which were easily synthesized in aqueous media using safe and low-cost materials, can emit intense phosphorescence even though the solution was not deoxygenated. However, the phosphorescence of l-cys-Mn-ZnS QDs was strongly quenched by MnO4(-) ascribed to the oxidation of l-cys and the increase of surface defects on l-cys-MnZnS QDs...
October 19, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
F Tumino, C S Casari, M Passoni, C E Bottani, A Li Bassi
Two-dimensional (2D) ZnO structures have been deposited on the Au(111) surface by means of the pulsed laser deposition technique. In situ scanning tunneling microscopy and scanning tunneling spectroscopy measurements have been performed to characterize morphological, structural and electronic properties of 2D ZnO at the nanoscale. Starting from a sub-monolayer coverage, we investigated the growth of ZnO, identifying different atomic layers (up to the fifth). At low coverage, we observed single- and bi-layer nanocrystals, characterized by a surface moiré pattern that is associated to a graphene-like ZnO structure...
October 24, 2016: Nanotechnology
Damián Rodríguez Sartori, Cristian R Lillo, Juan J Romero, María Laura Dell Arciprete, Alejandro Miñán, Mónica Fernández Lorenzo de Mele, Mónica C Gonzalez
Grafting of polyethylene glycol (PEG) to ultrasmall photoluminescent silicon dots (SiDs) is expected to improve and expand the applications of these particles to aqueous environments and biological systems. Herein we report a novel one-pot synthesis of robust, highly water compatible PEG-coated SiDs (denoted as PEG-SiDs) of (3.3 ± 0.5) nm size. The nanoparticles' synthesis is based on the liquid phase oxidation of magnesium silicide using PEG as reaction media and leading to high PEG density grafting. PEG-SiDs enhanced photophysical, photosensitising, and solution properties in aqueous environments are described and compared to those of 2 nm size PEG-coated SiDs with low PEG density grafting (denoted as PEG-NHSiDs) obtained from a multistep synthesis strategy...
October 24, 2016: Nanotechnology
J R Yuan, X H Yan, Y Xiao, Y D Guo, C J Dai
Motivated by recent measurement of the magnetism and conductance of the oxygen-assisted Pt nanojunctions, we performed first principle calculations of the magnetic order and electronic transport by explicitly including fully relativistic effects. Our results show that the spin alignment is a cycloidal spiral feature attributed to the Dzyaloshinskii-Moriya interaction, which indicates that the observed magnetism in experiments is of noncollinear nature. The oxygen concentration is the responsible for the switching of the rotational sense of the spiral magnetic order found in oxygen-assisted Pt nanojunctions...
October 24, 2016: Nanotechnology
Yiqian Cui, Junyou Shi, Zili Wang
The centers and radii of radial basis functions (RBFs) greatly affect the approximation capability of RBF networks (RBFNs). Traditional statistics-based approaches are widely used, but they may lack adaptivity to different data structures. Quantum clustering (QC), derived from quantum mechanics and the Schrödinger equation, demonstrates excellent capability in finding the structure and conformity toward data distribution. In this paper, a novel neural networks model called quantum local potential function networks (QLPFNs) is proposed...
October 20, 2016: IEEE Transactions on Neural Networks and Learning Systems
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