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https://www.readbyqxmd.com/read/28213252/multi-pumping-flow-system-for-the-determination-of-boron-in-eye-drops-drinking-water-and-ocean-water
#1
Pablo González, Alexandra Sixto, Moisés Knochen
A novel automated method for the determination of boron based on the use of pulsed flows was developed and applied to the determination of this element in samples of tap water, ocean water and eye drops. The method was implemented by means of a multi-pumping system consisting of three solenoid micropumps and a photometric detector and exploits the reaction of azomethine-H in the presence of boron. The system runs under control of an open-source microcontroller. The main operational parameters were optimized...
May 1, 2017: Talanta
https://www.readbyqxmd.com/read/28213217/selective-enrichment-of-glycopeptides-phosphopeptides-using-fe3o4-au-b-oh-2-mtio2-core-shell-microspheres
#2
Dongpo Xu, Guoquan Yan, Mingxia Gao, Chunhui Deng, Xiangmin Zhang
In this work, the bifunctional Fe3O4@Au-B(OH)2@mTiO2 core-shell core-shell microspheres were designed and synthesized for the selective enrichment of glycopeptides/ phosphopeptides. Due to the bifunctional property of the titanium dioxide and the boronic acid group, the microspheres were successfully applied to the enrichment of phosphopeptides and glycopeptides, evaluated by capturing phosphopeptides from tryptic digestion of model phosphoprotein bovine β-casein diluted to 2.0pgμL(-1) (8.0×10(-17)molμL(-1)) and glycopeptides from tryptic digestion of model glycoprotein horseradish peroxidase (HRP) diluted to 80pgμL(-1) (2...
May 1, 2017: Talanta
https://www.readbyqxmd.com/read/28213215/silica-boronate-affinity-material-for-quick-enrichment-of-intracellular-nucleosides
#3
Shuxia Wang, Huihui Li, Xiujuan Guan, Ting Cheng, Haixia Zhang
Boronic acid modified materials have been widely used to adsorb nucleosides, but their adsorption capacities require further improvement. Most cis-diol containing biomolecules are in very low abundance along with interfering components in real samples, and need to be enriched specially. In this study, we synthesize a kind of silica absorbent modified with boronic acid derivative, using amorphous silica as raw material and obtaining high adsorption capacity for adenosine. In addition, the adsorption equilibrium can be completed within 10s and 1min for the desorption...
May 1, 2017: Talanta
https://www.readbyqxmd.com/read/28211923/electrical-and-photocatalytic-properties-of-boron-doped-zno-nanostructure-grown-on-pet-ito-flexible-substrates-by-hydrothermal-method
#4
Wei Wang, Taotao Ai, Qi Yu
Boron-doped zinc oxide sheet-spheres were synthesized on PET-ITO flexible substrates using a hydrothermal method at 90 °C for 5 h. The results of X-ray diffraction and X-ray photoelectron spectroscopy indicated that the B atoms were successfully doped into the ZnO lattice, the incorporation of B led to an increase in the lattice constant of ZnO and a change in its internal stress. The growth mechanism of pure ZnO nanorods and B-doped ZnO sheet-spheres was specifically investigated. The as-prepared BZO/PET-ITO heterojunction possessed obvious rectification properties and its positive turn-on voltage was 0...
February 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28211268/asymmetric-cu-catalyzed-intermolecular-trifluoromethylarylation-of-styrenes-enantioselective-arylation-of-benzylic-radicals
#5
Lianqian Wu, Fei Wang, Xiaolong Wan, Dinghai Wang, Pinhong Chen, Guosheng Liu
A novel asymmetric radical trifluoromethyl-arylation of alkenes has been developed, which provides an efficient approach to access chiral CF3-containing 1,1-diarylmethane derivatives with good to excellent enantioselectivity. Various vinyl arenes and aryl boronic acids are compatible with these conditions. The utility of the method is demonstrated by accessing modified bioactive molecules.
February 17, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28210007/annealing-stability-study-of-co20fe60b20-mgo-co20fe60b20-perpendicular-magnetic-tunnel-junctions
#6
P J Chen, M Zhu, S Tibus, T Dyer, J Piccirillo, B Ocker, R D Shull
A full Co20Fe60B20\MgO\ Co20Fe60B20 perpendicular magnetic tunnel junction (pMTJ) with (Co\Pt) multilayers as pinning layers and different functional multilayers stacks were made and annealed at different temperatures. The tunneling magnetoresistance ratio (TMR) and MgO barrier resistance-area product (RA) were measured and analyzed as a function of annealing temperature. The TMR of pMTJs dramatically declines with increasing annealing temperatures from 320 °C to 400 °C while the RA increases with temperature from 375 °C to 450 °C...
January 18, 2017: Journal of Physics D: Applied Physics
https://www.readbyqxmd.com/read/28209015/boron-neutron-capture-therapy-a-literature-review
#7
REVIEW
Kavitaa Nedunchezhian, Nalini Aswath, Manigandan Thiruppathy, Sarumathi Thirugnanamurthy
Boron Neutron Capture Therapy (BNCT) is a radiation science which is emerging as a hopeful tool in treating cancer, by selectively concentrating boron compounds in tumour cells and then subjecting the tumour cells to epithermal neutron beam radiation. BNCT bestows upon the nuclear reaction that occurs when Boron-10, a stable isotope, is irradiated with low-energy thermal neutrons to yield α particles (Helium-4) and recoiling lithium-7 nuclei. A large number of 10 Boron (10B) atoms have to be localized on or within neoplastic cells for BNCT to be effective, and an adequate number of thermal neutrons have to be absorbed by the 10B atoms to maintain a lethal 10B (n, α) lithium-7 reaction...
December 2016: Journal of Clinical and Diagnostic Research: JCDR
https://www.readbyqxmd.com/read/28207418/electrical-transport-and-thermoelectric-properties-of-boron-carbide-nanowires
#8
Kazuhiro Kirihara, Masakazu Mukaida, Yoshiki Shimizu
The electrical transport and thermoelectric property of boron carbide nanowires synthesized by a carbothermal method are reported. It is demonstrated that the nanowires achieve a higher Seebeck coefficient and power factor than those of the bulk samples. The conduction mechanism of the nanowires at low temperatures below 300 K is different from that of the sintered-polycrystalline and single-crystal bulk samples. In a temperature range of 200 to 450 K, there is a crossover between electrical conduction by variable-range hopping and phonon-assisted hopping...
February 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28207271/synthesis-of-benzyl-allyl-and-allenyl-boronates-via-copper-catalyzed-borylation-of-alcohols
#9
Lujia Mao, Kálmán J Szabó, Todd B Marder
Alcohols are among the most abundant and readily available organic feedstocks in industrial processes. The direct catalytic functionalization of sp(3) C-O bonds of alcohols remains the main challenge in this field. Here, we report a copper-catalyzed synthesis of benzyl-, allyl-, and allenyl-boronates from benzylic, allylic, and propargylic alcohols, respectively. This protocol exhibits a broad reaction scope (40 examples) and high efficiency (up to 95% yield) under mild conditions, including for the preparation of secondary allylic boronates...
February 16, 2017: Organic Letters
https://www.readbyqxmd.com/read/28205309/a-feasibility-study-of-a-deuterium-deuterium-neutron-generator-based-boron-neutron-capture-therapy-system-for-treatment-of-brain-tumors
#10
Mindy Hsieh, Yingzi Liu, Farshad Mostafaei, Jean M Poulson, Linda H Nie
PURPOSE: Boron neutron capture therapy (BNCT) is a binary treatment modality that uses high LET particles to achieve tumor cell killing. Deuterium-deuterium (DD) compact neutron generators have advantages over nuclear reactors and large accelerators as the BNCT neutron source, such as their compact size, low cost, and relatively easy installation. The purpose of this study is to design a beam shaping assembly (BSA) for a DD neutron generator and assess the potential of a DD-based BNCT system using Monte Carlo (MC) simulations...
February 2017: Medical Physics
https://www.readbyqxmd.com/read/28204664/genetic-factors-underlying-boron-toxicity-tolerance-in-rice-genome-wide-association-study-and-transcriptomic-analysis
#11
Joao Braga de Abreu Neto, María Clara Hurtado-Perez, Monika A Wimmer, Michael Frei
No abstract text is available yet for this article.
January 1, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28203680/b-h-functionalization-of-the-monocarba-closo-dodecaborate-anion-by-rhodium-and-iridium-catalysis
#12
Yunjun Shen, Yani Pan, Kang Zhang, Xuewei Liang, Jiyong Liu, Bernhard Spingler, Simon Duttwyler
The regioselective derivatization of the monocarba-closo-dodecaborate anion via catalytic B-H bond activation is reported. Amide directing groups in combination with rhodium and iridium catalysts allowed for the direct functionalization of cage boron vertices. Products comprising B-C, B-N and B-Cl bonds were synthesized. As a key intermediate of the B-H activation step, an iridium complex with a direct B-Ir interaction was isolated and fully characterized by spectroscopic methods as well as X-ray crystallography...
February 16, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28199942/atmospheric-contribution-to-boron-enrichment-in-aboveground-wheat-tissues
#13
Cheng Wang, Junfeng Ji, Mindong Chen, Cong Zhong, Zhongfang Yang, Patrick Browne
Boron is an essential trace element for all organisms and has both beneficial and harmful biological functions. A particular amount of boron is discharged into the environment every year because of industrial activities; however, the effects of environmental boron emissions on boron accumulation in cereals has not yet been estimated. The present study characterized the accumulation of boron in wheat under different ecological conditions in the Yangtze River Delta (YRD) area. This study aimed to estimate the effects of atmospheric boron that is associated with industrial activities on boron accumulation in wheat...
February 3, 2017: Chemosphere
https://www.readbyqxmd.com/read/28199104/cobalt-catalyzed-1-1-diboration-of-terminal-alkynes-scope-mechanism-and-synthetic-applications
#14
Simon Krautwald, Mate J Bezdek, Paul J Chirik
A cobalt-catalyzed method for the 1,1-diboration of terminal alkynes with bis(pinacolato)diboron (B2Pin2) is described. The reaction proceeds efficiently at 23 °C with excellent 1,1-selectivity and broad functional group tolerance. With the unsymmetrical diboron reagent PinB-BDan (Dan = naphthalene-1,8-diaminato), stereoselective 1,1-diboration provided products with two boron substituents that exhibit differential reactivity. One example prepared by diboration of 1-octyne was crystallized and its stereochemistry established by X-ray crystallography...
February 15, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28198903/a-stereoselective-synthesis-of-e-or-z-%C3%AE-arylvinyl-halides-via-a-borylative-coupling-halodeborylation-protocol
#15
Jakub Szyling, Adrian Franczyk, Piotr Pawluć, Bogdan Marciniec, Jędrzej Walkowiak
A new stereoselective method for the synthesis of (E)-β-arylvinyl iodides and (E)- or (Z)-β-arylvinyl bromides from styrenes and vinyl boronates on the basis of a one-pot procedure via borylative coupling/halodeborylation is reported. Depending on the halogenating agent as well as the mode of the halodeborylation reaction, (E) or (Z) isomers are selectively formed.
February 15, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28198115/double-stranded-helical-oligomers-covalently-bridged-by-rotary-cyclic-boronate-esters
#16
Hiroki Iida, Kenji Ohmura, Ryuta Noda, Soichiro Iwahana, Hiroshi Katagiri, Naoki Ousaka, Taku Hayashi, Yuh Hijikata, Stephan Irle, Eiji Yashima
Novel double helices covalently-bridged by cyclic boronate esters were synthesized from complementary dimers with a m-terphenyl backbone joined by a chiral or achiral phenylene linker bearing diethyl boronates and diols, respectively. The X-ray crystallographic analysis and variable-temperature NMR and circular dichroism measurements, along theoretical calculations, revealed that the double helices function as a "molecular rotor" in which the cyclic boronate ester units rotate, yielding two stable rotamers at low temperatures...
February 14, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28197566/lateral-and-flexural-phonon-thermal-transport-in-graphene-and-stanene-bilayers
#17
Yang Hong, Chongqin Zhu, Minggang Ju, Jingchao Zhang, Xiao Cheng Zeng
Stanene, a low thermal conductivity two-dimensional (2D) sheet composed of group-IV element Sn, is a prototype material with novel properties such as 2D topological insulating behavior and near-room-temperature quantum Hall effects. Monolayer graphene, on the other hand, possesses unusual thermal properties, but has a zero bandgap. By stacking stanene and graphene monolayers vertically into a hetero-bilayer, an indirect bandgap can be obtained, making the hetero-bilayer a good candidate for special applications...
February 15, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28196975/tyropeptins-proteasome-inhibitors-produced-by-kitasatospora-sp-mk993-df2
#18
REVIEW
Isao Momose, Takumi Watanabe
Tyropeptins are new proteasome inhibitors isolated from the culture broth of Kitasatospora sp. MK993-dF2. Tyropeptins permeate cell membranes, inhibit intracellular proteasomes and reduce the degradation of ubiquitinated proteins in mammalian cells. We performed structure-based drug design and structure-activity relationship studies on tyropeptin derivatives to obtain valuable information of derivatives. Among the synthesized tyropeptin derivatives, some boronic acid derivatives exhibited potent antitumor effects against human multiple myeloma...
February 15, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28195494/electrical-and-thermal-transport-in-coplanar-polycrystalline-graphene-hbn-heterostructures
#19
José-Eduardo Barrios-Vargas, Bohayra Mortazavi, Aron W Cummings, Rafael Martinez-Gordillo, Miguel Pruneda, Luciano Colombo, Timon Rabczuk, Stephan Roche
We present a theoretical study of electronic and thermal transport in polycrystalline heterostructures combining graphene (G) and hexagonal boron nitride (hBN) grains of varying size and distribution. By increasing the hBN grain density from a few percent to 100%, the system evolves from a good conductor to an insulator, with the mobility dropping by orders of magnitude and the sheet resistance reaching the MΩ regime. The Seebeck coefficient is suppressed above 40% mixing, while the thermal conductivity of polycrystalline hBN is found to be on the order of 30-120 Wm(-1)K(-1)...
February 14, 2017: Nano Letters
https://www.readbyqxmd.com/read/28195386/a-tale-of-two-elements-the-lewis-acidity-basicity-umpolung-of-boron-and-phosphorus
#20
Douglas Wade Stephan
This mini-review focuses on the Lewis acidity/basicity "umpolung" of B-based nucleophiles and P-based electrophiles.
February 13, 2017: Angewandte Chemie
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