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Florian Korbinian Scharnagl, Shubhankar Kumar Bose, Todd B Marder
An overview of the synthesis and chemistry of acylborane compounds is presented. Acylboranes are a rare class of boron compounds, previously proposed as intermediates in several transformations and considered to be difficult to prepare. Methodologies for the preparation of acylborane compounds are based on both electrophilic and nucleophilic sources of boron. The former methods include addition of electrophilic boron reagents to acyl-anion equivalents, while the latter methods are based on boryl anion reagents which are trapped by electrophiles, such as aldehydes, diethyl carbonate and ethyl acetate...
December 2, 2016: Organic & Biomolecular Chemistry
F Bedoya, J P Allain, R Kaita, C H Skinner, L Buzi, B E Koel
A novel Plasma Facing Components (PFCs) diagnostic, the Materials Analysis Particle Probe (MAPP), has been recently commissioned in the National Spherical Torus Experiment Upgrade (NSTX-U). MAPP is currently monitoring the chemical evolution of the PFCs in the NSTX-U lower divertor at 107 cm from the tokamak axis on a day-to-day basis. In this work, we summarize the methodology that was adopted to obtain qualitative and quantitative descriptions of the samples chemistry. Using this methodology, we were able to describe all the features in all our spectra to within a standard deviation of ±0...
November 2016: Review of Scientific Instruments
Fuming Li, Zhipeng Chen, Ge Zhuang, Hai Liu, Lizhi Zhu
The fast reciprocating magnetic probe (FRMP) system is newly developed on the Joint Texas Experimental Tokamak (J-TEXT) to measure the local magnetic fluctuations at the plasma edge. The magnetic probe array in the FRMP consists of four 2-dimensional magnetic probes arranged at different radial locations to detect local poloidal and radial magnetic fields. These probes are protected by a graphite and boron nitride casing to improve the frequency response of each probe; they are mounted on the head of a movable rod, which is oriented along radial direction at the top of the torus...
November 2016: Review of Scientific Instruments
Mark W Lee
The incorporation of polyhedral boranes into novel photoluminescent materials is an area with increasing interest. While the neutral carboranes have been widely investigated for this purpose, the dodecaborate ion has received much less attention. Herein we report a significant expansion to the scope of substitution reactions for the dodecaborate ion, whereby this cluster was observed to react directly with a wide range of arenes in a step-wise and controlled manner. In the products of these reactions, the dodecaborate ion serves as a core upon which up to nine mono- or polycyclic aromatic hydrocarbon ligands are exohedrally bonded...
December 2, 2016: Angewandte Chemie
Seda Orenay Boyacioglu, Mehmet Korkmaz, Erkan Kahraman, Hatice Yildirim, Selin Bora, Osman Yavuz Ataman
The mechanism of boron effect on human transcription and translation has not been fully understood. In the current study it was aimed to reveal the role of boron on the expression of certain transcription factors that play key roles in many cellular pathways on human subjects chronically exposed to low amounts of boron. The boron concentrations in drinking water samples were 1.57±0.06mg/l for boron group while the corresponding value for the control group was 0.016±0.002mg/l. RNA isolation was performed using PAX gene RNA kit on the blood samples from the subjects...
January 2017: Journal of Trace Elements in Medicine and Biology
Renata Dessordi, Adriano Levi Spirlandeli, Ariane Zamarioli, José Batista Volpon, Anderson Marliere Navarro
Diabetes Mellitus is a condition that predisposes a higher risk for the development of osteoporosis. The objective of this study was to investigate the influence of boron supplementation on bone microstructure and strength in control and non-obese diabetic mice for 30days. The animals were supplemented with 40μg/0,5ml of boron solution and controls received 0,5ml of distilled water daily. We evaluated the biochemical parameters: total calcium, phosphorus, magnesium and boron; bone analysis: bone computed microtomography, and biomechanical assay with a three point test on the femur...
January 2017: Journal of Trace Elements in Medicine and Biology
Alicia Rae Welden, Alexander A Rusakov, Dominika Zgid
Including finite-temperature effects from the electronic degrees of freedom in electronic structure calculations of semiconductors and metals is desired; however, in practice it remains exceedingly difficult when using zero-temperature methods, since these methods require an explicit evaluation of multiple excited states in order to account for any finite-temperature effects. Using a Matsubara Green's function formalism remains a viable alternative, since in this formalism it is easier to include thermal effects and to connect the dynamic quantities such as the self-energy with static thermodynamic quantities such as the Helmholtz energy, entropy, and internal energy...
November 28, 2016: Journal of Chemical Physics
J Brus, J Czernek, M Urbanova, L Kobera, A Jegorov
The difficulty in the prediction of the complicated solid-state structure of boronic acid derivatives, resulting from the complex pathway of reversible covalent interactions, represents a significant obstacle to the development of a new generation of advanced supramolecular systems such as covalent organic frameworks of efficient anticancer drugs. In this contribution, various 2D (11)B-(11)B solid-state NMR correlation techniques supported by DFT calculations were explored to formulate a reliable tool for monitoring the covalent assembly of boronic acid residues in the solid state...
December 1, 2016: Physical Chemistry Chemical Physics: PCCP
Wenlei Zhai, Louise Male, John S Fossey
Four novel bis-boronic acid compounds were synthesised via copper catalysed azide-alkyne cycloaddition (CuAAC) reactions. Glucose selectivity was observed for a particular structural motif. Moreover, a new glucose selective fluorescent sensor was designed and synthesised as a result.
December 1, 2016: Chemical Communications: Chem Comm
J Kiełtucki, M Dobrakowski, N Pawlas, B Średniawa, M Boroń, S Kasperczyk
There are no common recommendations regarding electrocardiographic monitoring in occupationally exposed workers. Therefore, the present study was designed to investigate whether exposure to lead results in an increase of selected electrocardiography (ECG) pathologies, such as QT interval prolongation and repolarization disorders, in occupationally exposed workers. The study group included 180 workers occupationally exposed to lead compounds. The exposed group was divided according to the median of the mean blood lead level (PbBmean) calculated based on a series of measurements performed during 5-year observation period (35 µg/dl) into two subgroups: low exposure (LE, PbBmean = 20...
November 30, 2016: Human & Experimental Toxicology
Jianying Chen, Xiaohu Li, Mengyu Feng, Kun Luo, Juan Yang, Bo Zhang
Development of novel materials for enrichment of glycopeptides is the key to a comprehensive analysis of the glycoproteome, which is closely related to several major diseases and biomarker findings. We synthesized phenylboronic acid (PBA) bound to SiO2 microspheres by a thiol-ene click chemistry method (this material was denoted as click PBA) and used it to separate cis-diol-containing molecules and enrich glycopeptides in hydrophilic interaction chromatography mode. Successful preparation of click PBA was confirmed by elemental analysis, X-ray photoelectron spectroscopy, N2 adsorption-desorption isotherms, and high-resolution scanning electron microscopy...
November 29, 2016: Analytical and Bioanalytical Chemistry
Kazuo Tanaka, Kenta Nishino, Shunichiro Ito, Honami Yamane, Kazumasa Suenaga, Kazushi Hashimoto, Yoshiki Chujo
This paper presents the aggregation-induced emission (AIE) properties of o-carborane derivatives and proposes a potential strategy for constructing AIE-active organoboron complexes via the enhancement of freedom of intramolecular mobility. Initially, the optical properties of o-carborane derivatives with or without the fused ring structure at the C-C bond in o-carborane in which elongation should be induced by photo-excitation according to theoretical calculations were compared. Accordingly, it was shown that large mobility at the C-C bond in o-carborane should be responsible for the annihilation of emission in solution, leading to the AIE property...
November 30, 2016: Faraday Discussions
Y Tsukahara, R Puchala, T Sahlu, A L Goetsch
Twenty Boer (6.1 mo old and 21.3 kg) and 20 Spanish (6.6 mo old and 19.7 kg) goat wethers were used to determine effects of brackish water on feed intake, digestion, heat energy, and blood constituents. Brackish water had 6,900 mg/L total dissolved salts, 1,885 mg/L Na, 75 mg/L Mg, 1,854 mg/L chloride, 2,478 mg/L sulfate, and 9 mg/L boron. Water treatments were 100% tap water (control), 100% of a brackish water source (100-BR), 33% control and 67% brackish water (67-BR), and 67% control and 33% brackish water (33-BR)...
September 2016: Journal of Animal Science
Lars A Leth, Florian Glaus, Marta Meazza, Liang Fu, Mathias K Thøgersen, Emma A Bitsch, Karl Anker Jørgensen
A novel reaction based on synergistic catalysis, combining palladium- and organocatalysis has been developed. The palladium catalyst activates vinyl benzoxazinanones via a decarboxylation to undergo a [4+2] cycloaddition with iminium-ion activated α,β-unsaturated aldehydes. The reaction is demonstrated to proceed for a number of combinations of vinyl benzoxazinanones reacting with α,β-unsaturated aldehydes, providing highly substituted vinyl tetrahydroquinolines in good to high yields, and excellent enantio- and diastereoselectivities (>98 % ee and >20:1 d...
December 5, 2016: Angewandte Chemie
Andrew J Warner, Anna Churn, John S McGough, Michael J Ingleson
BCl3 -induced borylative cyclization of aryl-alkynes possessing ortho-EMe (E=S, O) groups represents a simple, metal-free method for the formation of C3-borylated benzothiophenes and benzofurans. The dichloro(heteroaryl)borane primary products can be protected to form synthetically ubiquitous pinacol boronate esters or used in situ in Suzuki-Miyaura cross couplings to generate 2,3-disubstituted heteroarenes from simple alkyne precursors in one pot. In a number of cases alkyne trans-haloboration occurs alongside, or instead of, borylative cyclization and the factors controlling the reaction outcome are determined...
November 29, 2016: Angewandte Chemie
Liangzhi Kou, Yandong Ma, Liujiang Zhou, Ziqi Sun, Yuantong Gu, Aijun Du, Sean Smith, Changfeng Chen
Recent reports of successful synthesis of atomically thin boron films have raised great prospects of discovering novel electronic and transport properties in a new type of 2D materials. Here we show by first-principles calculations that monolayer and bilayer γ-B28 films are intrinsically metallic while the thicker films possess intriguing electronic states that exhibit moderate to large bandgaps in all the interior layers but are nearly gapless at the surface. Remarkably, these surface electronic states are tunable by strain, allowing the outermost layer to transition between a semimetal and a narrow-gap semiconductor...
November 29, 2016: Nanoscale
Joshua Gild, Yuanyao Zhang, Tyler Harrington, Sicong Jiang, Tao Hu, Matthew C Quinn, William M Mellor, Naixie Zhou, Kenneth Vecchio, Jian Luo
Seven equimolar, five-component, metal diborides were fabricated via high-energy ball milling and spark plasma sintering. Six of them, including (Hf0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, (Hf0.2Zr0.2Ta0.2Mo0.2Ti0.2)B2, (Hf0.2Zr0.2Mo0.2Nb0.2Ti0.2)B2, (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2, (Mo0.2Zr0.2Ta0.2Nb0.2Ti0.2)B2, and (Hf0.2Zr0.2Ta0.2Cr0.2Ti0.2)B2, possess virtually one solid-solution boride phase of the hexagonal AlB2 structure. Revised Hume-Rothery size-difference factors are used to rationalize the formation of high-entropy solid solutions in these metal diborides...
November 29, 2016: Scientific Reports
Johannes Jobst, Alexander J H van der Torren, Eugene E Krasovskii, Jesse Balgley, Cory R Dean, Rudolf M Tromp, Sense Jan van der Molen
High electron mobility is one of graphene's key properties, exploited for applications and fundamental research alike. Highest mobility values are found in heterostructures of graphene and hexagonal boron nitride, which consequently are widely used. However, surprisingly little is known about the interaction between the electronic states of these layered systems. Rather pragmatically, it is assumed that these do not couple significantly. Here we study the unoccupied band structure of graphite, boron nitride and their heterostructures using angle-resolved reflected-electron spectroscopy...
November 29, 2016: Nature Communications
Bingping Liu, Shihai Yan, Zhongqian Song, Mengli Liu, Xuqiang Ji, Wenrong Yang, Jingquan Liu
Herein, a conceptually new and straightforward aqueous route is described for the synthesis of hydroxyl- and amino-functionalized boron nitride quantum dots (BNQDs) with quantum yields (QY) as high as 18.3 % by using a facile bottom-up approach, in which a mixture of boric acid and ammonia solution was hydrothermally treated in one pot at 200 °C for 12 h. The functionalized BNQDs, with excellent photoluminescence properties, could be easily dispersed in an aqueous medium and applied as fluorescent probes for the detection of ferrous (Fe(2+) ) and ferric (Fe(3+) ) ions with excellent selectivity and low detection limits...
November 29, 2016: Chemistry: a European Journal
Tony Low, Andrey Chaves, Joshua D Caldwell, Anshuman Kumar, Nicholas X Fang, Phaedon Avouris, Tony F Heinz, Francisco Guinea, Luis Martin-Moreno, Frank Koppens
In recent years, enhanced light-matter interactions through a plethora of dipole-type polaritonic excitations have been observed in two-dimensional (2D) layered materials. In graphene, electrically tunable and highly confined plasmon-polaritons were predicted and observed, opening up opportunities for optoelectronics, bio-sensing and other mid-infrared applications. In hexagonal boron nitride, low-loss infrared-active phonon-polaritons exhibit hyperbolic behaviour for some frequencies, allowing for ray-like propagation exhibiting high quality factors and hyperlensing effects...
November 28, 2016: Nature Materials
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