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Ki Seok Kim, You Jin Ji, Yeonsig Nam, Ki Hyun Kim, Eric Singh, Jin Yong Lee, Geun Young Yeom
The electronic and optical properties of graphene are greatly dependent on the the number of layers. For the precise control of the graphene layers, atomic layer etching (ALE), a cyclic etching method achieved through chemical adsorption and physical desorption, can be the most powerful technique due to barely no damage and no contamination. In this study, we demonstrated the ALE process of graphene layers without noticeably damaging the graphene by using a controlled low energy oxygen (O2(+)/O(+))-ion for chemical adsorption and a low energy Ar(+)-ion (11...
May 26, 2017: Scientific Reports
Hidetsugu Shiozawa, Bernhard C Bayer, Herwig Peterlik, Jannik C Meyer, Wolfgang Lang, Thomas Pichler
Coordination polymerization leads to various metal-organic frameworks (MOFs) with unique physical properties and chemical functionalities. One of the challenges towards their applications as porous materials is to make MOFs optimally conductive to be used as electronic components. Here, it is demonstrated that Co-MOF-74, a honeycomb nano-framework with one-dimensionally arranged cobalt atoms, advances its physical properties by accommodating tetracyanochinodimethan (TCNQ), an acceptor molecule. Strong intermolecular charge transfer reduces the optical band gap down to 1...
May 26, 2017: Scientific Reports
Yan-Qiang Cao, Bing Wu, Di Wu, Ai-Dong Li
In situ-formed SiO2 was introduced into HfO2 gate dielectrics on Ge substrate as interlayer by plasma-enhanced atomic layer deposition (PEALD). The interfacial, electrical, and band alignment characteristics of the HfO2/SiO2 high-k gate dielectric stacks on Ge have been well investigated. It has been demonstrated that Si-O-Ge interlayer is formed on Ge surface during the in situ PEALD SiO2 deposition process. This interlayer shows fantastic thermal stability during annealing without obvious Hf-silicates formation...
December 2017: Nanoscale Research Letters
Marc Jovaní, Héctor Beltrán-Mir, Eloisa Cordoncillo, Anthony R West
Cubic, fluorite-structured solid solutions Zr1-xYxO2-x/2 (YSZ; x = 0.4-0.7) were prepared by sol-gel synthesis. Impedance measurements on pellets of 85% approximate density sintered at 1300 °C for 24 h showed strong evidence of oxide ion conduction with an inclined Warburg spike at low frequencies and capacitance values of ∼10(-6) F cm(-1) at 40 Hz. Arrhenius plots of total pellet conductivities were linear with activation energies of 1.4-1.56 eV. The conductivity decreased with x and was 2-4 orders of magnitude lower than that with optimized YSZ, x = 0...
May 26, 2017: Inorganic Chemistry
Xuelong Wang, Ruijuan Xiao, Hong Li, Liquan Chen
Through first-principles calculations and crystal structure prediction techniques, we identify a new layered oxysulfide LiAlSO in orthorhombic structure as a novel lithium superionic conductor. Two kinds of stacking sequences of layers of AlS_{2}O_{2} are found in different temperature ranges. Phonon and molecular dynamics simulations verify their dynamic stabilities, and wide band gaps up to 5.6 eV are found by electronic structure calculations. The lithium migration energy barrier simulations reveal the collective interstitial-host ion "kick-off" hopping mode with barriers lower than 50 meV as the dominating conduction mechanism for LiAlSO, indicating it to be a promising solid-state electrolyte in lithium secondary batteries with fast ionic conductivity and a wide electrochemical window...
May 12, 2017: Physical Review Letters
Zhuping Fei, Yang Han, Eliot Gann, Thomas Hodsden, Anthony Chesman, Christopher R McNeill, Thomas D Anthopoulos, Martin Heeney
We report the synthesis of two new selenophene containing ladder-type monomers, cyclopentadiselenophene (CDS) and indacenodiselenophene (IDSe), via a twofold and fourfold Pd catalyzed coupling with a 1,1-diborylmethane derivative. Co-polymers with benzothiadiazole (BT) were prepared in high yield by Suzuki polymerization to afford co-polymers which exhibited excellent solubility in a range of non-chlorinated solvents. The CDS co-polymer exhibited a band gap of just 1.18 eV, which is amongst the lowest reported for donor-acceptor polymers...
May 26, 2017: Journal of the American Chemical Society
JingWen Huang, Huiqiang Liu, Bo Jin, Min Liu, Qingchun Zhang, Liqiong Luo, Shijin Chu, Sheng Chu, Rufang Peng
This study explores the large-area synthesis of controllable morphology, uniform, and high-quality monolayer. MoSe2 is essential for its potential application in optoelectronics, photocatalysis, and renewable energy sources. In this study, we successfully synthesized snow-like MoSe2 monolayers using a simple chemical vapor deposition method. Results reveal that snow-like MoSe2 is a single crystal with a hexagonal structure, a thickness of ~0.9 nm, and a lateral dimension of up to 20 μm. The peak position of the photoluminescence spectra is ~1...
May 26, 2017: Nanotechnology
Ali Kachmar, Marcelo Carignano, Teodoro Laino, Marcella Iannuzzi, Jürg Hutter
The understanding of lithium solvation and transport in ionic liquids is important due to the possible applications in electrochemical devices. Using first principles simulations aided with the metadynamics approach we study the free energy landscape for lithium at infinite dilution conditions in ethylammonium nitrate, a protic ionic liquid. We analyze the local structure of the liquid around the lithium cation and find a quantitative picture in agreement with experimental findings. Our simulations show that the lowest two free energy minima correspond to conformations with the lithium solvated either by 3 or 4 nitrates ions with a transition barrier between them of 0...
May 26, 2017: ChemSusChem
Vinila N Viswanathan, Arun D Rao, Upendra K Pandey, Arul Varman Kesavan, Praveen C Ramamurthy
A series of low band gap, planar conjugated polymers, P1 (PFDTBT), P2 (PFDTDFBT) and P3 (PFDTTBT), based on fluorene and benzothiadiazole, was synthesized. The effect of fluorine substitution and fused aromatic spacers on the optoelectronic and photovoltaic performance was studied. The polymer, derived from dithienylated benzothiodiazole and fluorene, P1, exhibited a highest occupied molecular orbital (HOMO) energy level at -5.48 eV. Density functional theory (DFT) studies as well as experimental measurements suggested that upon substitution of the acceptor with fluorine, both the HOMO and lowest unoccupied molecular orbital (LUMO) energy levels of the resulting polymer, P2, were lowered, leading to a higher open circuit voltage and short circuit current with an overall improvement of more than 110% for the photovoltaic devices...
2017: Beilstein Journal of Organic Chemistry
Shijie Liu, Bo Liu, Xuhan Shi, Jiayin Lv, Shifeng Niu, Mingguang Yao, Quanjun Li, Ran Liu, Tian Cui, Bingbing Liu
Two-dimensional (2D) crystals exhibit unique and exceptional properties and show promise for various applications. In this work, we systematically studied the structures of a 2D boronphosphide (BP) monolayer with different stoichiometric ratios (BPx, x = 1, 2, 3, 4, 5, 6 and 7) and observed that each compound had a stable 2D structure with metallic or semiconducting electronic properties. Surprisingly, for the BP5 compounds, we discovered a rare penta-graphene-like 2D structure with a tetragonal lattice...
May 25, 2017: Scientific Reports
Alba Zanini, Vicente Ciancio, Monica Laurenza, Marisa Storini, Adolfo Esposito, Juan Carlos Terrazas, Paolo Morfino, Alessandro Liberatore, Gustavo Di Giovan
The preliminary results obtained in the first environmental radiation dosimetry campaign performed in the Antarctic region are presented. This experiment is carried out in the framework of CORA (COsmic Rays in Antarctica) Project, a collaboration between Argentine and Italian institutions. After a feasibility study performed in the Antarctic summer 2013, a new campaign has been carried out, started in March 2015, to measure various components of cosmic ray induced secondary atmospheric radiation at the Argentine Marambio Base (Antarctica; 196 m a...
May 22, 2017: Journal of Environmental Radioactivity
Thomas P Senftle, Emily A Carter
Knowledge of a semiconductor electrode's band edge alignment is essential for optimizing processes that occur at the semiconductor/electrolyte interface. Photocatalytic processes are particularly sensitive to such alignments, as they govern the transfer of photo-excited electrons or holes from the surface to reactants in the electrolyte solution. Reconstructions of a semiconductor surface during operation, as well as its interaction with the electrolyte solution, must be considered when determining band edge alignment...
May 25, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Thomas Tolhurst, Justin Andrews, Brett Leedahl, Peter Marley, Sarbajit Banerjee, Alexander Moewes
Recently, V2O5 nanowires have been synthesized as several different polymorphs, and as correlated bronzes with cations intercalated between the layers of edge- and corner-sharing VO6 octahedra. Unlike extended crystals, which tend to be plagued by substantial local variations in stoichiometry, nanowires of correlated bronzes exhibit precise charge ordering, thereby giving rise to pronounced electron correlation effects. These developments have greatly broadened the scope of research, and promise applications in several frontier electronic devices that make use of novel computing vectors...
May 21, 2017: Chemistry: a European Journal
Junlin Jiang, Amani A Alsam, Shanshan Wang, Shawkat M Aly, Zhenxing Pan, Omar F Mohammed, Kirk S Schanze
A series of -conjugated oligomer-acceptor dyads were synthesized that feature oligo(phenylene ethynylene) (OPE) conjugated backbones end-capped with a naphthalene diimide (NDI) acceptor. The OPE segments vary in length from 4 to 8 phenylene ethynene units (PEn-NDI, where n = 4, 6 and 8). Fluorescence and transient absorption spectroscopy reveals that intramolecular OPE NDI charge transfer dominates the deactivation of excited states of the PEn-NDI oligomers. Both charge separation (CS) and charge recombination (CR) are strongly exothermic (G0CS ~ -1...
May 25, 2017: Journal of Physical Chemistry. A
Ewa Erdmann, Marie-Christine Bacchus-Montabonel, Marta Łabuda
Investigations of collision-induced processes involving carbon ions and molecules of biological interest, in particular DNA building blocks, are crucial to model the effect of radiation on cells in order to improve medical treatments for cancer therapy. Using carbon ions appears to be one of the most efficient ways to increase biological effectiveness to damage cancerous cells by irradiating deep-seated tumors. Therefore, interest in accurate calculations to understand fundamental processes occurring in ion-molecule collision systems has been growing recently...
May 25, 2017: Physical Chemistry Chemical Physics: PCCP
Juhi Sharma, Jeffrey M Hampton, Giancarlo R Valiente, Takuma Wada, Holly Steigelman, Matthew C Young, Rachel R Spurbeck, Alisa D Blazek, Steffi Bösh, Wael N Jarjour, Nicholas A Young
Since being discovered over half a century ago, mesenchymal stem cells (MSCs) have been investigated extensively to characterize their cellular and physiological influences. MSCs have been shown to possess immunosuppressive capacity through inhibiting lymphocyte activation/proliferation and proinflammatory cytokine secretion while simultaneously demonstrating limited allogenic reactivity, which subsequently led to the evaluation of therapeutic feasibility to treat inflammatory diseases. Although regulatory constraints have restricted MSC development pharmacologically, limited clinical studies have shown encouraging results using MSC infusions to treat systemic lupus erythematosus (SLE); but, more trials will have to be performed to conclusively determine the clinical efficacy of MSCs to treat SLE...
2017: Frontiers in Immunology
Yuwei Weng, Wei Chen, Wenxiang He, Meng Huang, Ying Zhu, Yansheng Yan
BACKGROUND Hand, foot, and mouth disease (HFMD) is a common contagious disease in infants; it is caused by multiple serotypes of human enterovirus (EV), which belongs to the enterovirus genus of the picornavirus family. According to sentinel surveillance, infection with EVs other than EV71 and CVA 16 have become increasingly common in recent years among HFMD patients, posing new challenges for HFMD control. This study aimed to explore the spectrum of serotypes in the other EVs (non-EV71 and non-CVA16) in Fujian province in southeastern China...
May 25, 2017: Medical Science Monitor: International Medical Journal of Experimental and Clinical Research
Takahide Murasawa, Masao Takahashi, Masahiro Myojo, Arihiro Kiyosue, Atsushi Oguri, Jiro Ando, Issei Komuro
Previous research revealed that, in patients with coronary pressure-derived fractional flow reserve (FFR) in the 'grey zone' (0.75-0.85), repeated FFR assessments sometimes yield conflicting results. One of the causes of the fluctuations in FFR values around the grey zone may be imprecise identification of the point where maximal hyperemia is achieved. Identification of the state of maximal hyperemia during assessment of FFR can be challenging. This study aimed to determine whether non-invasive electrical velocimetry (EV) can be used to identify the state of maximal hyperemia...
May 23, 2017: International Heart Journal
Katherine S Yang, Hyungsoon Im, Seonki Hong, Ilaria Pergolini, Andres Fernandez Del Castillo, Rui Wang, Susan Clardy, Chen-Han Huang, Craig Pille, Soldano Ferrone, Robert Yang, Cesar M Castro, Hakho Lee, Carlos Fernandez Del Castillo, Ralph Weissleder
Pancreatic ductal adenocarcinoma (PDAC) is usually detected late in the disease process. Clinical workup through imaging and tissue biopsies is often complex and expensive due to a paucity of reliable biomarkers. We used an advanced multiplexed plasmonic assay to analyze circulating tumor-derived extracellular vesicles (tEVs) in more than 100 clinical populations. Using EV-based protein marker profiling, we identified a signature of five markers (PDAC(EV) signature) for PDAC detection. In our prospective cohort, the accuracy for the PDAC(EV) signature was 84% [95% confidence interval (CI), 69 to 93%] but only 63 to 72% for single-marker screening...
May 24, 2017: Science Translational Medicine
Gillian Coakley, Jana L McCaskill, Jessica G Borger, Fabio Simbari, Elaine Robertson, Marissa Millar, Yvonne Harcus, Henry J McSorley, Rick M Maizels, Amy H Buck
Recent studies have demonstrated that many parasites release extracellular vesicles (EVs), yet little is known about the specific interactions of EVs with immune cells or their functions during infection. We show that EVs secreted by the gastrointestinal nematode Heligmosomoides polygyrus are internalized by macrophages and modulate their activation. EV internalization causes downregulation of type 1 and type 2 immune-response-associated molecules (IL-6 and TNF, and Ym1 and RELMα) and inhibits expression of the IL-33 receptor subunit ST2...
May 23, 2017: Cell Reports
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