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André Wuttke, Armin Geyer
We develop templates that can be used to stabilize consistent oligomers of a bioactive peptide. In the present study, we synthesize oligomers of an antibody epitope from the amyloidogenic prion protein. Dynamic covalent chemistry is the basis for the spontaneous condensation of 2, 3, 4 or 6 peptides with qualified polyol templates presenting the required number of bioorthogonal ligation sites. To study this process in aqueous solution, the N-terminal amino acid of a 13-mer peptide is first acylated with 4-carboxy-benzoboroxole (1-hydroxy-1,3-dihydrobenzo[c][1,2] oxaborole-5-carboxylic acid) and then mixed with the template to obtain self-assembled miniamyloids of specified degree of oligomerization...
April 27, 2017: Journal of Peptide Science: An Official Publication of the European Peptide Society
Michaela Matthes, Ramón A Torres-Ruiz
Boron (B) is an essential micronutrient for organisms. In plants, B is known to stabilise the cell wall by crosslinking Rhamnogalacturonan II through ester bonds formed with cis-diols of sugar moieties. However, B is believed to be required for additional functions such as stability and function of (plasma membrane) proteins involved in signal transduction pathways. We have recently shown that boronic acids, competitors of B, efficiently induce perfect phenocopies of monopteros mutants. This effect is enigmatic because like B, boronic acids should find numerous cellular targets and thus disturb many biological processes ending in a spectrum of unspecific embryo phenotypes...
April 27, 2017: Plant Signaling & Behavior
Anagh Bhaumik, Ritesh Sachan, Jagdish Narayan
We report high-temperature superconductivity in B-doped amorphous quenched carbon (Q-carbon). This phase is formed after nanosecond laser melting of B-doped amorphous carbon films in a super undercooled state and followed by rapid quenching. Magnetic susceptibility measurements show the characteristics of type-II Bardeen-Cooper-Schrieffer superconductivity with a superconducting transition temperature (Tc) of 36.0±0.5 K for 17.0±1.0 atomic percent boron concentration. This value is significantly higher than the best experimentally reported Tc of 11 K for crystalline B-doped diamond...
April 27, 2017: ACS Nano
Sébastien Delpierre, Bertrand Willocq, Julien De Winter, Philippe Dubois, Pascal Gerbaux, Jean-Marie Raquez
Developing intrinsic self-healing polymeric materials is of great interest nowadays to extend material lifetime and/or prevent the replacement of damaged pieces. Spontaneously humidity-sensitive healable polymer network built around dynamic covalent B-O bonds was templated by using iminoboronate-based boroxine derivatives. Taking advantage of the dynamic boroxine/boronic acid equilibrium and iminoboronate chemistry, it is possible to construct polymeric materials able to self-heal without requiring any energy-demanding external activation...
April 26, 2017: Chemistry: a European Journal
Masoud Darvish Ganji, Razieh Dodangeh
Membranes have attracted much attention for the efficient separation of gas mixtures, due to their specific structural and unique properties. In this work, density functional theory (DFT) and molecular dynamic (MD) simulations have been employed to evaluate the performance of nanoporous hexagonal boron nitride (h-BN) monolayers for hydrogen purification. Various porous membranes were designed, and full structural relaxation was carried out by using DFT calculations and then MD simulations to investigate the H2 purification performance of the nanoporous h-BN membranes...
April 26, 2017: Physical Chemistry Chemical Physics: PCCP
Dongxu Han, Zongbi Bao, Huabin Xing, Yiwen Yang, Qilong Ren, Zhiguo Zhang
The Suzuki-Miyaura reaction is one of the most popular and efficient routes for the formation of carbon-carbon bonds in both laboratorial and industrial synthetic processes. Here, we report for the first time that a Au-Pd/TiO2 catalyst could be utilized efficiently for Suzuki-Miyaura reactions at ambient conditions under visible light with high activity and reusability. Mechanistic investigation by means of experimental methods revealed that through the strong local surface plasma resonance of Au under the visible light, the hot electrons of Au could be injected into Pd in the bimetallic nanoparticles, thus facilitating activation of the aryl halides...
April 26, 2017: Nanoscale
Di Gao, Shawkat M Aly, Paul-Ludovic Karsenti, Gessie Brisard, Pierre D Harvey
Two novel triads had been designed through covalent bond connection of the boron dipyrromethane (BODIPY), free base porphyrin (H2P) or zinc(ii) porphyrin (ZnP) and N-methyl-2-phenyl-3,4-fulleropyrrolidine (C60) mediated by BODIPY. This closely spaced triad arrangement where porphyrin and fullerene are placed apart is anticipated to stabilize charge separation by separating the two radicals from each other. Two model polyads were synthesized with BODIPY and H2P or ZnP to investigate interaction between the two chromophores...
April 26, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Alain C Tagne Kuate, Roger A Lalancette, F Jäkle
The synthesis of ferrocenylphosphine-borane adducts 1,2-fc(E)(PPh2·BH3) (E = SnR2R', HgX; 1,2-fc = 1,2-ferrocenediyl) that are substituted with organotin or organomercury Lewis acid moieties in ortho-position is presented. Several compounds that feature two ferrocenylphosphine-borane moieties bridged by Sn or Hg are also introduced. The products are fully characterized by multinuclear NMR spectroscopy, high-resolution MALDI-TOF mass spectrometry and elemental analysis. The attachment of the Lewis acid substituent to the same Cp ring of the ferrocene results in planar-chirality and the close proximity between the boron hydride group and the Lewis acid is expected to allow for agostic-type B-HE (E = Sn, Hg) interactions...
April 26, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Takuya Kubo, Hayato Furuta, Toyohiro Naito, Tomoharu Sano, Koji Otsuka
Selective adsorption of carbohydrates and glycoproteins was effectively achieved by molecularly imprinted hydrogels (MIHs) with a poly(ethylene glycol) (PEG)-based crosslinker and 4-vinylphenylboronic acid. In addition, an MIH with a novel boronic acid monomer provided selective adsorption and enabled visible detection of fructose.
April 26, 2017: Chemical Communications: Chem Comm
Tomoaki Nishino, Hiroshi Shiigi, Manabu Kiguchi, Tsutomu Nagaoka
Scanning tunneling microscopy tips were functionalized with a boronic acid derivative. In combination with a similarly modified substrate, the molecular tip forms a supramolecular complex selectively with a glucose molecule. The conductance of the resulting single complex allows one to achieve the specific single-molecule detection of glucose.
April 26, 2017: Chemical Communications: Chem Comm
Naresh K Jena, Rafael B Araujo, Vivekanand Shukla, Rajeev Ahuja
Borophene, single atomic-layer sheet of boron (Science, 2015, 350, 1513), is a rather new entrant into the burgeoning class of 2D materials. Borophene exhibits anisotropic metallic properties whereas its hydrogenated counterpart borophane is reported to be a gapless Dirac material lying on the same bench with the celebrated graphene. Interestingly, this transition of borophane also rendered stability to it considering the fact that borophene was synthesized under ultra-high vacuum conditions on a metallic (Ag) substrate...
April 26, 2017: ACS Applied Materials & Interfaces
Haamid Rasool Bhat, Prakash Chandra Jha
The anion binding selectivity and the recognition mechanism of two isomeric boranes namely 4-[bis(2,4,6-trimethylphenyl)boranyl]-N,N,N-trimethylaniline ([p-(Mes2B)C6H4(NMe3)]+, 1, where 'Mes' represents mesitylene and 'Me' represents methyl) and 2-[bis(2,4,6-trimethylphenyl)boranyl]-N,N,N-trimethylaniline ([o-(Mes2B)C6H4(NMe3)]+, 2) has been investigated using density functional theory (DFT) and time dependent-density functional theory (TD-DFT) methods. Natural population analysis indicates that the central boron atoms in 1 and 2 are the most active centers for nucleophilic addition of anions...
April 26, 2017: Journal of Physical Chemistry. A
Liang Ma, Xiao Cheng Zeng
Transition-metal (TM) nanoparticle catalyzed cutting has been proven to be an efficient approach to carve out straight channels in graphene to produce high-quality nanoribbons. However, applicability of such a catalytic approach to hexagonal boron nitride (h-BN) is still an open question due to binary element compositions. Here, our ab initio study indicates that long/straight channels along either zigzag or armchair direction of the BN sheet can be carved out, driven by the energetically favored TM-zigzag or TM-armchair BN interface, regardless of roughness of TM particle surface...
April 25, 2017: Nano Letters
Sanjay Behura, Phong Nguyen, Rousan Debbarma, Songwei Che, Michael R Seacrist, Vikas Berry
Hexagonal boron nitride (h-BN) is an ideal platform for interfacing with two-dimensional (2D) nanomaterials to reduce carrier scattering for high-quality 2D electronics. However, scalable, transfer-free growth of hexagonal boron nitride (h-BN) remains a challenge. Currently, h-BN based 2D heterostructures require exfoliation or chemical transfer of h-BN grown on metals resulting in small areas or significant interfacial impurities. Here, we demonstrate a surface-chemistry influenced transfer-free growth of large-area, uniform, and smooth h-BN directly on silicon (Si)-based substrates including Si, silicon nitride (Si3N4), and silicon dioxide (SiO2) via low-pressure chemical vapor deposition...
April 25, 2017: ACS Nano
Pablo Andres Denis, Saif Ullah, Fernando Sato
We have investigated the structure, stability, electronic properties and chemical reactivity of X/B/N triple doped graphene systems, X= Al, Si, P and S, by means of density functional periodic calculations. For the triple doped graphene (TDG) systems studied the dopants prefer to be bonded instead of separated. In general, the XNB pattern is preferred, with the exception of sulfur which favors the SBN motif. The introduction of a third dopant results in a negligible decrease of the cohesive energies with respect to their dual doped graphene (DDG) counterparts...
April 25, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Tadashi Watabe, Kohei Hanaoka, Sadahiro Naka, Yasukazu Kanai, Hayato Ikeda, Masanao Aoki, Eku Shimosegawa, Mitsunori Kirihata, Jun Hatazawa
PURPOSE: The purpose of this study was to establish a practical method to estimate the absolute boron concentrations in the tissues based on the standardized uptake values (SUVs) after administration of 4-borono-phenylalanine (BPA) using 4-borono-2-(18)F-fluoro-phenylalanine ((18)F-FBPA) PET. METHODS: Rat xenograft models of C6 glioma (n = 7, body weight 241 ± 28.0 g) were used for the study. PET was performed 60 min after intravenous injection of (18)F-FBPA (30...
April 24, 2017: Annals of Nuclear Medicine
Peter Jacobson, Matthias Muenks, Gennadii Laskin, Oleg Brovko, Valeri Stepanyuk, Markus Ternes, Klaus Kern
Spin-bearing molecules can be stabilized on surfaces and in junctions with desirable properties, such as a net spin that can be adjusted by external stimuli. Using scanning probes, initial and final spin states can be deduced from topographic or spectroscopic data, but how the system transitions between these states is largely unknown. We address this question by manipulating the total spin of magnetic cobalt hydride complexes on a corrugated boron nitride surface with a hydrogen-functionalized scanning probe tip by simultaneously tracking force and conductance...
April 2017: Science Advances
Hongxia Dai, Wenjuan Lü, Xianwei Zuo, Qian Zhu, Congjie Pan, Xiaoying Niu, Juanjuan Liu, HongLi Chen, Xingguo Chen
In this work, we report a durable and sensitive H2O2 biosensor based on boronic acid functionalized metal-organic frameworks (denoted as MIL-100(Cr)-B) as an efficient immobilization matrix of horseradish peroxidase (HRP). MIL-100(Cr)-B features a hierarchical porous structure, extremely high surface area, and sufficient recognition sites, which can significantly increase HRP loading and prevent them from leakage and deactivation. The H2O2 biosensor can be easily achieved without any complex processing. Meanwhile, the immobilized HRP exhibited enhanced stability and remarkable catalytic activity towards H2O2 reduction...
April 18, 2017: Biosensors & Bioelectronics
Claudia Ojeda-Aristizabal, Elton J G Santos, Seita Onishi, Aiming Yan, Haider Imad Rasool, Salman Kahn, Yinchuan Lv, Drew Latzke, Jairo Velasco, Michael F Crommie, Matthew Sorensen, Kenneth Gotlieb, Chiu-Yun Lin, Kenji Watanabe, Takashi Taniguchi, Alessandra Lanzara, Alex Zettl
Charge transfer at the interface between dissimilar materials is at the heart of electronics and photovoltaics. Here we study the molecular orientation, electronic structure, and local charge transfer at the interface region of C60 deposited on graphene, with and without supporting substrates such as hexagonal boron nitride. We employ ab initio density functional theory with van der Waals (vdW) interactions, and experimentally characterize interface devices using high-resolution transmission electron microscopy and electronic transport...
April 24, 2017: ACS Nano
Guo-Yu Yang, Qi Wei, Shi-Jia Sun, Jie Zhang
Two novel alkali/alkaline-earth borates, Ba6[B6O9 (OH)6]2(H3BO3) (1) and Li7MAlB12O24 (M = Ba, Sr, Ca) (2a-c), with 1- and 3-D structures have been hydrothermally made and characterized. 1 features a rarely 1-D anionic chain built by hexaborate clusters of B6O11(OH)6 made of six BO4/ BO2(OH)2 tetrahedra. The anionic chains are embedded in the channels of Ba6-based wheel cluster open-framework. On the basis of the structural analyses of 1, by incorporating the rational Al atoms as the linkers and tuning the reaction conditions, the anhydrous borates 2a-c have been success-fully obtained, showing novel 3-D aluminoborates (ABOs) constructed from B6O14-based cluster chains and AlO6 octa-hedra...
April 24, 2017: Chemistry: a European Journal
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