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Mojtaba Abdi-Jalebi, Zahra Andaji-Garmaroudi, Stefania Cacovich, Camille Stavrakas, Bertrand Philippe, Johannes M Richter, Mejd Alsari, Edward P Booker, Eline M Hutter, Andrew J Pearson, Samuele Lilliu, Tom J Savenije, Håkan Rensmo, Giorgio Divitini, Caterina Ducati, Richard H Friend, Samuel D Stranks
Metal halide perovskites are of great interest for various high-performance optoelectronic applications. The ability to tune the perovskite bandgap continuously by modifying the chemical composition opens up applications for perovskites as coloured emitters, in building-integrated photovoltaics, and as components of tandem photovoltaics to increase the power conversion efficiency. Nevertheless, performance is limited by non-radiative losses, with luminescence yields in state-of-the-art perovskite solar cells still far from 100 per cent under standard solar illumination conditions...
March 21, 2018: Nature
Jonathan D Breeze, Enrico Salvadori, Juna Sathian, Neil McN Alford, Christopher W M Kay
The maser-the microwave progenitor of the optical laser-has been confined to relative obscurity owing to its reliance on cryogenic refrigeration and high-vacuum systems. Despite this, it has found application in deep-space communications and radio astronomy owing to its unparalleled performance as a low-noise amplifier and oscillator. The recent demonstration of a room-temperature solid-state maser that utilizes polarized electron populations within the triplet states of photo-excited pentacene molecules in a p-terphenyl host paves the way for a new class of maser...
March 21, 2018: Nature
Ana Luz Muñoz-Rosas, Arturo Rodríguez-Gómez, Juan Carlos Alonso-Huitrón
Nowadays, the use of plasmonic metal layers to improve the photonic emission characteristics of several semiconductor quantum dots is a booming tool. In this work, we report the use of silicon quantum dots (SiQDs) embedded in a silicon nitride thin film coupled with an ultra-thin gold film (AuNPs) to fabricate light emitting devices. We used the remote plasma enhanced chemical vapor deposition technique (RPECVD) in order to grow two types of silicon nitride thin films. One with an almost stoichiometric composition, acting as non-radiative spacer; the other one, with a silicon excess in its chemical composition, which causes the formation of silicon quantum dots imbibed in the silicon nitride thin film...
March 22, 2018: Nanomaterials
Zahra Fakhroueian, Rouhollah Vahabpour, Mehdi Assmar, Alireza Massiha, Afshin Zahedi, Pegah Esmaeilzadeh, Fatemeh Katouzian, Sara Rezaei, Peyman Keyhanvar, Alireza Mozafari Dehshiri
Nanoformulations derived from fine porous ZnO quantum dot nanoparticles (QD NPs) can offer strong potential medical applications; especially in cancer therapy. ZnO QD NPs was synthesized by sol-gel hydrothermal process, fast cold quenching and further smart surface functionalization methods to obtain ultrasmall size (1-4 nm) NPs. ZnO nanopolymer, a wetting agent, PEG co-solvent and water/oil emulsion stabilizer were considered in our nanofluid formulation. The resulting nanofluid was characterized by SEM, FTIR, photoluminescence, band gap energy, zeta potential and UV-Vis spectroscopy...
March 22, 2018: Artificial Cells, Nanomedicine, and Biotechnology
Simone L Waite, Hua Li, Alister J Page
Deep eutectic solvents (DESs) are promising candidates as alternate media for industrial gas sequestration processes, such as denitrification via NO2 adsorption. Here, quantum chemical methods are employed to characterise NO2 solvation structure and the adsorption mechanism in choline chloride DES with urea, methylurea and thiourea hydrogen bond donors. Our results show that the solvation structure of NO2 in bulk choline chloride DES is determined by the type of hydrogen bond donor present. Changing the structure of the hydrogen bond donor not only changes its NO2 coordination mechanism, but also the coordination mechanism between NO2 and the choline and chloride ions in the DES as well...
March 22, 2018: Journal of Physical Chemistry. B
Yuannan Chen, Aimin Ren, Zhongyue Yang, Tengfei He, Xiaoli Ding, Hongxing Zhang, Luyi Zou
In this paper, we conducted DFT and TDDFT calculations on three double heteroleptic Cu(i) complexes to understand how different substituents on N^N ligands influence the phosphorescence quantum yield (PLQY). Both radiative and nonradiative decay processes were thoroughly investigated. Factors that determine the rate of radiative process (kr) were considered, including the lowest triplet excited state E(T1), the transition dipole moment MSm,j of the Sm → S0 transition, the spin-coupled matrix element SOC, and the singlet-triplet splitting energies ΔE(Sm-T1)...
March 22, 2018: Physical Chemistry Chemical Physics: PCCP
Jia-Li Liu, Zhi-Ling Tang, Jia-Qi Zhang, Yaqin Chai, Ying Zhuo, Ruo Yuan
The electrochemiluminescence (ECL) properties of polycyclic aromatic hydrocarbons (PAHs) are excellent on account of the high photoluminescence quantum yield. However, the poor solubility and radical instability of PAHs in the aqueous solution severely restricted the further biological application. Here, 9,10 - diphenylanthracene (DPA) nano blocks (NBs) with good dispersibility and stability in aqueous solution were prepared according to morphology-controlled technology employing water-soluble polymers as a protectant...
March 22, 2018: Analytical Chemistry
Ashish Agnihotri, Praveen Gupta, Anuj Dwivedi, Chandra Shekhar Seth
Salicylic acid alleviates lead toxicity in Brassica juncea (L.) by promoting growth under non-stress and activating stress-defense mechanism (s) under lead stress conditions. It also boosts the ascorbate-glutathione cycle and thus helps in minimizing oxidative and DNA damage. Brassica juncea plants were exposed to different concentrations (0, 500, 1000 and 2000 mg kg-1 ) of lead (Pb) and subsequently sprayed with 0.5 mM of salicylic acid (SA) to check for morphological and leaf gas exchange parameters like transpiration rate (E), stomatal conductance (GH2 O), net photosynthetic rate (A) and maximum quantum yield of PS II (Fv /Fm )...
March 21, 2018: Planta
Anusha B Gopalan, Pramodh Vallurupalli
Carr-Purcell-Meiboom-Gill (CPMG) type relaxation dispersion experiments are now routinely used to characterise protein conformational dynamics that occurs on the μs to millisecond (ms) timescale between a visible major state and 'invisible' minor states. The exchange rate(s) ([Formula: see text]), population(s) of the minor state(s) and the absolute value of the chemical shift difference [Formula: see text] (ppm) between different exchanging states can be extracted from the CPMG data. However the sign of [Formula: see text] that is required to reconstruct the spectrum of the 'invisible' minor state(s) cannot be obtained from CPMG data alone...
March 21, 2018: Journal of Biomolecular NMR
Giuseppe Licari, Joseph S Beckwith, Saeideh Soleimanpour, Stefan Matile, Eric Vauthey
A planarizable push-pull molecular probe with mechanosensitive properties was investigated at several biomimetic interfaces, consisting of different phospholipid monolayers located between dodecane and an aqueous buffer solution, using the interface-specific surface-second-harmonic-generation (SSHG) technique. Whereas the SSHG spectra recorded at liquid-disordered interfaces were similar to the absorption spectra in bulk solutions, those measured at liquid-ordered phases exhibited a remarkable shift towards lower energies to an extent depending on the surface pressure of the phospholipid monolayer...
March 22, 2018: Physical Chemistry Chemical Physics: PCCP
Enzheng Shi, Yao Gao, Blake P Finkenauer, Akriti, Aidan H Coffey, Letian Dou
Over the last several years, there has been tremendous progress in the development of nanoscale halide perovskite materials and devices that possess a wide range of band gaps and tunable optical and electronic properties. Particularly, the emerging two-dimensional (2D) forms of halide perovskites are attracting more interest due to the long charge carrier lifetime, high photoluminescence quantum efficiency, and great defect tolerance. Interfacing 2D halide perovskites with other 2D materials including graphene and transition metal dichalcogenides (TMDs) significantly broadens the application range of the 2D materials and enhances the performance of the functional devices...
March 22, 2018: Chemical Society Reviews
Parul Bansal, Yusuf Khan, Gaurav Kumar Nim, Prasenjit Kar
We demonstrated a facile method to grow organometal halide perovskite quantum dots in a solid silica matrix. The photoluminescence measurements of the MAPbBr3 quantum dots and corresponding large particles show a shift from blue to green emission with morphological changes. The nanocrystals impregnated on the silica matrix improve the stability and may be useful as functional materials in all solid state light emitting devices.
March 22, 2018: Chemical Communications: Chem Comm
Andrei Khrennikov
Recently I posted a paper entitled "External observer reflections on QBism". As any external observer, I was not able to reflect all features of QBism properly. The comments I received from one of QBism's creators, C. A. Fuchs, were very valuable to me in better understanding the views of QBists. Some of QBism's features are very delicate and extracting them from articles of QBists is not a simple task. Therefore, I hope that the second portion of my reflections on QBism (or, strictly speaking, my reflections on Fuchs reflections on my earlier reflections) might be interesting and useful for other experts in quantum foundations and quantum information theory (especially, taking into account my previous aggressively anti-QBism position)...
2018: Foundations of Science
Ana Margarida Piloto, David S M Ribeiro, S Sofia M Rodrigues, Catarina Santos, João L M Santos, M Goreti F Sales
A highly sensitive fluorescence detection probe was developed by tailoring plastic antibodies on the external surface of aqueous soluble quantum dots (QDs). The target was Myoglobin (Myo), a cardiac biomarker that quenched the intrinsic fluorescent emission of cadmium telluride (CdTe) QDs capped with mercaptopropionic acid (CdTe-MPA-QDs). The QDs were incubated with the target protein and further modified with a molecularly-imprinted polymer (MIP) produced by radical polymerization of acrylamide and bisacrylamide...
March 21, 2018: Scientific Reports
Xiaoguang Ma, Xiaoyu Li, Jianqiang Li, Cécile Genevois, Bingqian Ma, Auriane Etienne, Chunlei Wan, Emmanuel Véron, Zhijian Peng, Mathieu Allix
Transparent crystalline yttrium aluminum garnet (YAG; Y3 Al5 O12 ) is a dominant host material used in phosphors, scintillators, and solid state lasers. However, YAG single crystals and transparent ceramics face several technological limitations including complex, time-consuming, and costly synthetic approaches. Here we report facile elaboration of transparent YAG-based ceramics by pressureless nano-crystallization of Y2 O3 -Al2 O3 bulk glasses. The resulting ceramics present a nanostructuration composed of YAG nanocrystals (77 wt%) separated by small Al2 O3 crystalline domains (23 wt%)...
March 21, 2018: Nature Communications
Sophie L Mader, Alois Bräuer, Michael Groll, Ville R I Kaila
The recently discovered FeII /α-ketoglutarate-dependent dioxygenase AsqJ from Aspergillus nidulans stereoselectively catalyzes a multistep synthesis of quinolone alkaloids, natural products with significant biomedical applications. To probe molecular mechanisms of this elusive catalytic process, we combine here multi-scale quantum and classical molecular simulations with X-ray crystallography, and in vitro biochemical activity studies. We discover that methylation of the substrate is essential for the activity of AsqJ, establishing molecular strain that fine-tunes π-stacking interactions within the active site...
March 21, 2018: Nature Communications
Elena Boto, Niall Holmes, James Leggett, Gillian Roberts, Vishal Shah, Sofie S Meyer, Leonardo Duque Muñoz, Karen J Mullinger, Tim M Tierney, Sven Bestmann, Gareth R Barnes, Richard Bowtell, Matthew J Brookes
Imaging human brain function with techniques such as magnetoencephalography typically requires a subject to perform tasks while their head remains still within a restrictive scanner. This artificial environment makes the technique inaccessible to many people, and limits the experimental questions that can be addressed. For example, it has been difficult to apply neuroimaging to investigation of the neural substrates of cognitive development in babies and children, or to study processes in adults that require unconstrained head movement (such as spatial navigation)...
March 21, 2018: Nature
Hiroshi Matsui, Soichi Ito, Masayoshi Nakano
The open-shell character dependences of second hyperpolarizability γ is investigated for rectangular-shaped tetraradicaloid models such as diradical dimers, using numerically exact solutions of the extended Hubbard model. The newly-defined local diradical characters for intra- and inter-molecular interactions (referred to as yintra and yinter, respectively) are compared to conventional global ones (y0 and y1) and provide comprehensive understanding of the electronic structure of the system. The system shows two kinds of enhancements of γ components, γintra and γinter (caused, respectively, by intra- and inter-molecular diradical interactions): (i) the system with large yintra (yinter) (> ~0...
March 21, 2018: Journal of Physical Chemistry. A
Martin Michalík, Peter Poliak, Vladimír Lukeš
A systematic DFT investigation of 3-hydroxy-N-phenylnaphthalene-2-carboxamide and its sixteen para-derivatives is presented. The structural analysis showed that the energetically preferred conformation of all derivatives is practically planar and it is stabilised via intramolecular hydrogen bonds occurring between (C)O...H(3)O atomic pairs. The quantum chemically evaluated partition coefficients logarithms correlate well with Quantitative Structure-Activity Relationship models as well as with experimentally determined isocratic retention factors logarithm...
March 2018: Acta Chimica Slovenica
Salah Eddine Hachani, Zelikha Necira, Djamel Eddine Mazouzi, Nadia Nebbache
Quantum chemical calculations at DFT/B3LYP level of theory with 6-31G, 6-311G, and 6-311G(d,p) basis sets were done to correlate the inhibition of mild steel corrosion in 1 M H2SO4 by four dianiline Schiff bases namely N,N'-Bis(benzylidene)-4,4'-dianiline (DAA), N,N'-Bis (benzylidene)-4,4'-methylenedianiline (MDAA), N,N' Bis(benzylidene)-4,4'-sulphonyldianiline (SDAA) and N,N'-Bis(benzylidene)-4,4'-oxydianiline (ODAA) with their electronic and structural properties. Quantum chemical parameters such as the EHOMO, ELUMO, energy gap (ΔE), dipole moment (μ), global softness (σ), and global hardness (η) were calculated and discussed to provide valuable explanations for the reactivity and selectivity of the studied inhibitors...
March 2018: Acta Chimica Slovenica
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