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Mi-Jin Jin, Seon Young Moon, Jungmin Park, Vijayakumar Modepalli, Junhyeon Jo, Shin-Ik Kim, Hyun Cheol Koo, Byoung-Chul Min, Hyun-Woo Lee, Seung-Hyub Baek, Jung-Woo Yoo
A two-dimensional electron gas emerged at a LaAlO3/SrTiO3 interface is an ideal system for "spin-orbitronics" as the structure itself strongly couple the spin and orbital degree of freedom through the Rashba spin-orbit interaction. One of core experiments toward this direction is the nonlocal spin transport measurement, which has remained elusive due to the low spin injection efficiency to this system. Here we bypass the problem by generating a spin current not through the spin injection from outside but instead through the inherent spin Hall effect and demonstrate the nonlocal spin transport...
December 9, 2016: Nano Letters
Arumugam Vignesh, Nattamai S P Bhuvanesh, Nallasamy Dharmaraj
A convenient synthesis of a library of tetrazoles through a novel and operationally simple protocol effecting the direct conversion of arylboronic acids catalyzed by a new ONO pincer-type Pd(II) complex under mild reaction conditions using the readily available reagents is reported. The palladium complex was reused up to four cycles in an open-flask condition.
December 9, 2016: Journal of Organic Chemistry
Jing Wang, Jiangnan Liu, Jonas Thomsen, Denis Selnihhin, Marianne S Hede, Freja C M Kirsebom, Oskar Franch, Søren Fjelstrup, Magnus Stougaard, Yi-Ping Ho, Finn Skou Pedersen, Birgitta R Knudsen
In the current study we describe a novel DNA sensor system that allows the detection of single catalytic DNA integration events mediated by retrovirus encoded integrase (IN) present in viral particles. This is achieved by rolling circle amplification mediated conversion of enzymatic reactions happening within nanometer dimensions to directly detectable micrometer sized DNA products. The system utilizes the unique integration reaction of IN to generate a surface anchored nicked DNA circle that serves as a substrate for rolling circle amplification and allows for specific, quantitative and sensitive detection of purified recombinant IN or virus particles with a detection limit of less than 30 virus particles per μL of sample...
December 9, 2016: Nanoscale
Qian Zhao, G R Li, Jian Song, Yulong Zhao, Yinghuai Qiang, X P Gao
In an all-solid-state perovskite solar cell, methylammonium lead halide film is in charge of generating photo-excited electrons, thus its quality can directly influence the final photovoltaic performance of the solar cell. This paper accentuates a very simple chemical approach to improving the quality of a perovskite film with a suitable amount of acetic acid. With introduction of acetate ions, a homogeneous, continual and hole-free perovskite film comprised of high-crystallinity grains is obtained. UV-visible spectra, steady-state and time-resolved photoluminescence (PL) spectra reveal that the obtained perovskite film under the optimized conditions shows a higher light absorption, more efficient electron transport, and faster electron extraction to the adjoining electron transport layer...
December 9, 2016: Scientific Reports
Sang Youn Chae, Se Jin Park, Sung Gyu Han, Hyejin Jung, Chae-Woong Kim, Chaehwan Jeong, Oh-Shim Joo, Byoung Koun Min, Yun Jeong Hwang
Chalcopyrite Cu(In,Ga)(Se,S)2 (CIGS) semiconductors are potential candidates for use in photoelectrochemical (PEC) hydrogen generation due to their excellent optical absorption properties and high conduction band edge position. In the present research, CIGS thin film was successfully prepared on a transparent substrate (F:SnO2 glass) using a solution-based process and applied for a photocathode in solar water splitting, which shows control of the surface state associated with sulfurization/selenization process significantly influences on the PEC activity...
December 7, 2016: Journal of the American Chemical Society
Peter J Waller, Steven J Lyle, Thomas M Osborn Popp, Christian S Diercks, Jeffrey A Reimer, Omar M Yaghi
The imine linkages of two layered, porous covalent organic frameworks (COFs), TPB-TP-COF ([C6H3(C6H4N)3]2[C6H4(CH)2]3, 1) and 4PE-1P-COF ([C2(C6H4N)4][C6H4(CH)2]2, 2), have been transformed into amide linkages to make the respective isostructural amide COFs 1' and 2' by direct oxidation with retention of crystallinity and permanent porosity. Remarkably, the oxidation of both imine COFs is complete, as assessed by FT-IR and (13)C CP-MAS NMR spectroscopy and demonstrates (a) the first chemical conversion of a COF linkage and (b) how the usual "crystallization problem" encountered in COF chemistry can be bypassed to access COFs, such as these amides, that are typically thought to be difficult to obtain by the usual de novo methods...
December 7, 2016: Journal of the American Chemical Society
Lijian Zuo, Shiqi Dong, Nicholas De Marco, Yao-Tsung Hsieh, Sang-Hoon Bae, Pengyu Sun, Yang Yang
Morphology is critical component to achieve high device performance hybrid perovskite solar cells. Here, we develop a vapor induced intermediate phase (VIP) strategy to manipulate the morphology of perovskite films. By exposing the perovskite precursor films to different saturated solvent vapor atmospheres, e.g., dimethylformamide and dimethylsufoxide, dramatic film morphological evolution occurs, associated with the formation of different intermediate phases. We observe that the crystallization kinetics is significantly altered due to the formation of these intermediate phases, yielding highly crystalline perovskite films with less defect states and high carrier lifetimes...
December 7, 2016: Journal of the American Chemical Society
Alexander S Dudnik, Thomas J Aldrich, Nicholas D Eastham, Robert P H Chang, Antonio Facchetti, Tobin J Marks
A new and highly regioselective direct C-H arylation polymerization (DARP) methodology enables the reproducible and sustainable synthesis of high-performance π-conjugated photovoltaic copolymers. Unlike traditional Stille polycondensation methods for producing photovoltaic copolymers, this DARP protocol eliminates the need for environmentally harmful, toxic organotin compounds. This DARP protocol employs low loadings of commercially available catalyst components, Pd2(dba)3·CHCl3 (0.5 mol%) and P(2-MeOPh)3 (2 mol%), sterically tuned carboxylic acid additives, and an environmentally friendly solvent, 2-methyltetrahydrofuran...
December 7, 2016: Journal of the American Chemical Society
Nathan J Ray, Eduard G Karpov
Here we report on direct evidence of a correlation between hydrogen-to-water oxidation on mesoporous Pt/TiO2 nanocomposites at room temperature and the conversion of surface-released chemical energy into a stationary electrical current. The Pt phase of this heterojunction device is an electrically continuous 15 nm thick mesh deposited onto a mesoporous TiO2 substrate fabricated with a plasma electrolytic oxidation process. The H2O turnover frequency approaches an asymptotic value associated with the saturation of the Pt/TiO2 interface as the concentration of hydrogen gas is increased...
November 23, 2016: ACS Applied Materials & Interfaces
Timothy B Wright, P Andrew Evans
A highly enantioselective rhodium-catalyzed allylic alkylation of prochiral α,α-disubstituted aldehyde enolates with allyl benzoate is described. This protocol provides a novel approach for the synthesis of acyclic quaternary carbon stereogenic centers and it represents the first example of the direct enantioselective alkylation of an aldehyde enolate per se. The versatility of the α-quaternary aldehyde products is demonstrated through their conversion to a variety of useful motifs applicable to target-directed synthesis...
November 30, 2016: Journal of the American Chemical Society
Daniel M Chipman
The hemibonding interaction in the water dimer cation is studied using coupled cluster electronic structure methods. The hemibonded dimer cation geometry is a local minimum structure characterized by the two participating monomers having both a very short separation and a near parallel relative orientation. It is shown that the vertically ionized dimer at its optimum neutral geometry can convert to the hemibonded dimer cation structure with essentially no energetic hindrance. Direct conversion to the hemibonded structure is therefore an energetically facile alternative to the minimum energy path that connects the vertically ionized neutral water dimer to the global minimum proton-transferred structure...
December 8, 2016: Journal of Physical Chemistry. A
Madeline R Lederer, Allison R Staniec, Zoe L Coates Fuentes, Daryl A Van Ry, Ryan Z Hinrichs
Biogenic volatile organic compounds (BVOCs), including the monoterpene limonene, are a major source of secondary organic aerosol (SOA). While gas-phase oxidation initiates the dominant pathway for BVOC conversion to SOA, recent studies have demonstrated that biogenic hydrocarbons can also directly react with acidic droplets. To investigate whether mineral dust may facilitate similar reactive uptake of biogenic hydrocarbons, we studied the heterogeneous reaction of limonene with mineral substrates using condensed-phase infrared spectroscopy and identified the formation of irreversibly adsorbed organic products...
December 8, 2016: Journal of Physical Chemistry. A
Hoon Ji, Sunhyun Hwang, Keonmok Kim, CheolGi Kim, Nak Cheon Jeong
The fabrication of metal-organic framework (MOF) films on conducting substrates has demonstrated great potential in applications such as electronic conduction and sensing. For these applications, direct contact of the film to the conducting substrate without a self-assembled monolayer (SAM) is a desired step that must be achieved prior to the use of MOF films. In this report, we propose an in situ strategy for the rapid one-step conversion of Cu metal into HKUST-1 films on conducting Cu substrates. The Cu substrate acts both as a conducting substrate and a source of Cu(2+) ions during the synthesis of HKUST-1...
November 30, 2016: ACS Applied Materials & Interfaces
R H Holm, Wayne Lo
Synthetic iron-sulfur clusters of general formulation [FemSqLl](z) with core atoms Fe and S and terminal ligands L constitute a family of molecular clusters with remarkably diverse geometrical and electronic structures. Several structure types are also found in proteins. The large majority of research on these clusters has involved elucidation of physical properties. Here, we direct attention to reactivity in the form of cluster conversions in which the FemSq cores of reactants are transformed to new structures, usually of different nuclearity, in overall reactions such as self-assembly and fragment condensation and dissociation...
November 23, 2016: Chemical Reviews
Vincent F Scalfani, Antony J Williams, Valery Tkachenko, Karen Karapetyan, Alexey Pshenichnov, Robert M Hanson, Jahred M Liddie, Jason E Bara
BACKGROUND: Three-dimensional (3D) printed crystal structures are useful for chemistry teaching and research. Current manual methods of converting crystal structures into 3D printable files are time-consuming and tedious. To overcome this limitation, we developed a programmatic method that allows for facile conversion of thousands of crystal structures directly into 3D printable files. RESULTS: A collection of over 30,000 crystal structures in crystallographic information file (CIF) format from the Crystallography Open Database (COD) were programmatically converted into 3D printable files (VRML format) using Jmol scripting...
2016: Journal of Cheminformatics
Marina E Lodovicho, Tássia R Costa, Carolina P Bernardes, Danilo L Menaldo, Karina F Zoccal, Sante E Carone, José C Rosa, Manuela B Pucca, Felipe A Cerni, Eliane C Arantes, Jan Tytgat, Lúcia H Faccioli, Luciana S Pereira-Crott, Suely V Sampaio
Cysteine-rich secretory proteins (CRISPs) are commonly described as part of the protein content of snake venoms, nevertheless, so far, little is known about their biological targets and functions. Our study describes the isolation and characterization of Bj-CRP, the first CRISP isolated from Bothrops jararaca snake venom, also aiming at the identification of possible targets for its actions. Bj-CRP was purified using three chromatographic steps (Sephacryl S-200, Source 15Q and C18) and showed to be an acidic protein of 24...
December 5, 2016: Toxicology Letters
M G Zampino, E Magni, P S Ravenda, C A Cella, G Bonomo, P Della Vigna, S Galdy, F Spada, G M Varano, G Mauri, N Fazio, F Orsi
A major challenge for the management of advanced-colorectal-cancer is the multidisciplinary approach required for the treatment of liver metastases. Reducing the burden of liver metastases with liver-directed therapy has an important impact on both survival and health-related quality of life. This paper debates the rationale and current liver-directed approaches for colorectal liver metastases based on the evidence of literature and new clinical trials. Surgery is the gold standard, when feasible, and it's the main treatment goal for patients with potentially-resectable disease as a means of prolonging progression-free survival...
December 2016: Critical Reviews in Oncology/hematology
Tonderai Mabuto, Salome Charalambous, Christopher J Hoffmann
BACKGROUND: Early in the global response to HIV, health communication was focused toward HIV prevention. More recently, the role of health communication along the entire HIV care continuum has been highlighted. We sought to describe how a strategy of interpersonal communication allows for precision health communication to influence behavior regarding care engagement. METHODS: We analyzed 1 to 5 transcripts from clients participating in longitudinal counseling sessions from a communication strategy arm of a randomized trial to accelerate entry into care in South Africa...
January 1, 2017: Journal of Acquired Immune Deficiency Syndromes: JAIDS
Kyu-Tae Lee, Yuan Yao, Junwen He, Brent Fisher, Xing Sheng, Matthew Lumb, Lu Xu, Mikayla A Anderson, David Scheiman, Seungyong Han, Yongseon Kang, Abdurrahman Gumus, Rabab R Bahabry, Jung Woo Lee, Ungyu Paik, Noah D Bronstein, A Paul Alivisatos, Matthew Meitl, Scott Burroughs, Muhammad Mustafa Hussain, Jeong Chul Lee, Ralph G Nuzzo, John A Rogers
Emerging classes of concentrator photovoltaic (CPV) modules reach efficiencies that are far greater than those of even the highest performance flat-plate PV technologies, with architectures that have the potential to provide the lowest cost of energy in locations with high direct normal irradiance (DNI). A disadvantage is their inability to effectively use diffuse sunlight, thereby constraining widespread geographic deployment and limiting performance even under the most favorable DNI conditions. This study introduces a module design that integrates capabilities in flat-plate PV directly with the most sophisticated CPV technologies, for capture of both direct and diffuse sunlight, thereby achieving efficiency in PV conversion of the global solar radiation...
December 5, 2016: Proceedings of the National Academy of Sciences of the United States of America
Asuka Eguchi, Matthew J Wleklinski, Mackenzie C Spurgat, Evan A Heiderscheit, Anna S Kropornicka, Catherine K Vu, Devesh Bhimsaria, Scott A Swanson, Ron Stewart, Parameswaran Ramanathan, Timothy J Kamp, Igor Slukvin, James A Thomson, James R Dutton, Aseem Z Ansari
Artificial transcription factors (ATFs) are precision-tailored molecules designed to bind DNA and regulate transcription in a preprogrammed manner. Libraries of ATFs enable the high-throughput screening of gene networks that trigger cell fate decisions or phenotypic changes. We developed a genome-scale library of ATFs that display an engineered interaction domain (ID) to enable cooperative assembly and synergistic gene expression at targeted sites. We used this ATF library to screen for key regulators of the pluripotency network and discovered three combinations of ATFs capable of inducing pluripotency without exogenous expression of Oct4 (POU domain, class 5, TF 1)...
December 5, 2016: Proceedings of the National Academy of Sciences of the United States of America
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