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https://www.readbyqxmd.com/read/28449230/metal-free-arene-and-heteroarene-borylation-catalyzed-by-strongly-electrophilic-bis-boranes
#1
Gerhard Erker, Yun-Lin Liu, Gerald Kehr, Constantin G Daniliuc
The geminal chelate bis-borylalkanes 4 and 5 featuring strongly electrophilic B(C6F5)2 and B(C6F5) groups, respectively, serve as efficient catalysts for the borylation of arenes and heteroarenes. The borylation reactions proceed under mild conditions with liberation of dihydrogen.
April 27, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28399452/design-synthesis-and-evaluation-of-curcumin-derivatives-as-nrf2-activators-and-cytoprotectors-against-oxidative-death
#2
Zhi-Shan Tu, Qi Wang, Dan-Dan Sun, Fang Dai, Bo Zhou
Activation of nuclear factor erythroid-2-related factor 2 (Nrf2) has been proven to be an effective means to prevent the development of cancer, and natural curcumin stands out as a potent Nrf2 activator and cancer chemopreventive agent. In this study, we synthesized a series of curcumin analogs by introducing the geminal dimethyl substituents on the active methylene group to find more potent Nrf2 activators and cytoprotectors against oxidative death. The geminally dimethylated and catechol-type curcumin analog (compound 3) was identified as a promising lead molecule in terms of its increased stability and cytoprotective activity against the tert-butyl hydroperoxide (t-BHP)-induced death of HepG2 cells...
April 5, 2017: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28391179/weak-coupling-between-magnetically-inequivalent-spins-the-deceptively-simple-complicated-spectrum-of-a-13-c-labeled-trimethylated-amine
#3
Ulric B le Paige, Bauke Smits, Peter 't Hart, Fons Lefeber, Nathaniel I Martin, Hugo van Ingen
Magnetic inequivalence of nuclear spins is well known to cause additional splittings that complicate spectral analysis. Here, we present an extraordinary case of magnetic inequivalence, manifested in the 13-spin system of a (13)C,(15)N-labeled trimethylated amine. All methyl group protons are chemically equivalent due to the molecular symmetry, but not all are magnetically equivalent as they have different (1)JCH and (3)JCH couplings. In general, spectra of such a large spin system can be expected to be extremely complicated by the presence of hundreds if not thousands of extra lines, caused by the strong coupling between inequivalent nuclei...
May 2017: Journal of Magnetic Resonance
https://www.readbyqxmd.com/read/28386097/phenotypic-variability-and-community-interactions-of-germinating-streptomyces-spores
#4
Ye Xu, Kalin Vetsigian
A case can be made for stochastic germination and interactions among germinating spores as beneficial germination strategies in uncertain environments. However, there is little data on how widespread, species-specific or diverse such phenomena are. Focusing on Streptomycetes, a platform was developed for quantification of germination and early growth within communities of spores. We found that the germination process is stochastic at three levels: spores vary in their germination times, mycelium networks grow at different rates, and a fraction of germlings stall their growth shortly after germination...
April 6, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28384987/a-rare-case-of-twinning-involving-primary-maxillary-lateral-incisor-with-review-of-literature
#5
Santosh Hunasgi, Anila Koneru, Vardendra Manvikar, M Vanishree, Rudraraju Amrutha
Twinning is referred to the development of two separate teeth that arose from the complete separation of one tooth bud. To the best of our knowledge very few cases of twinning in primary or permanent dentition have been previously reported. Here, we report an additional case of twinning involving primary maxillary left lateral incisor and a literature review of clinical and radiographic findings of previous reported cases of gemination and twinning is also discussed. A six-year-old male patient reported to the dental clinic with the complaint of decay in the left front teeth region of the upper jaw...
February 2017: Journal of Clinical and Diagnostic Research: JCDR
https://www.readbyqxmd.com/read/28384404/suppressing-ionic-terms-with-number-counting-jastrow-factors-in-real-space
#6
Brett Van Der Goetz, Eric Neuscamman
We demonstrate that 4-body real space Jastrow factors are, with the right type of Jastrow basis function, capable of performing successful wave function stenciling to remove unwanted ionic terms from an overabundant fermionic reference without unduly modifying the remaining components. In addition to greatly improving size consistency (restoring it exactly in the case of a geminal power), real-space wave function stenciling is, unlike its Hilbert space predecessors, immediately compatible with diffusion Monte Carlo, allowing it to be used in the pursuit of compact, strongly correlated trial functions with reliable nodal surfaces...
April 6, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28382365/methylene-bridged-intramolecular-donor-acceptor-systems-based-on-rare-earth-metals-and-phosphinomethanides
#7
Martin Pieper, Jan-Hendrik Lamm, Beate Neumann, Hans-Georg Stammler, Norbert W Mitzel
New geminally bonded intramolecular donor-acceptor systems, Cp2LnCH2PR2 (Ln = Y, Ho, Er, R = CHMe2, CMe3), were prepared by salt elimination reactions between the dicyclopentadienyl-element chlorides (Cp2LnCl, Ln = Y, Ho, Er) and diorganylphosphinomethanides (R2PCH2Li; R = CHMe2, CMe3). These compounds, 1-6, were characterized by elemental analyses, mass spectrometry and X-ray diffraction experiments and the yttrium species additionally by NMR spectroscopy. In the solid state the molecular structures differ from each other, depending on the steric demand of the phosphorus substituents...
April 19, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28380298/acetaldehyde-ammonia-interaction-a-dft-study-of-reaction-mechanism-and-product-identification
#8
Vera P Tuguldurova, Alexander V Fateev, Victor S Malkov, Oleg Kh Poleshchuk, Olga V Vodyankina
The product of acetaldehyde and ammonia reaction, namely, 2,4,6-trimethyl-1,3,5-hexahydrotriazine trihydrate, was synthesized and identified using a combination of experimental (NMR spectroscopy, IR spectroscopy, melting point determination) and DFT-based theoretical approaches. A reaction mechanism was proposed. The reaction was shown to proceed via the formation of aminoalcohol, imine, and geminal diamine intermediates accompanied by cyclization of these species. The calculation results allowed us to build a potential energy surface of the acetaldehyde and ammonia interaction and determine the most energetically favorable pathway to yield acetaldehyde ammonia trimer...
April 13, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28379259/the-elusive-silica-water-interface-isolated-silanols-under-water-as-revealed-by-vibrational-sum-frequency-spectroscopy
#9
Laetitia Dalstein, Elizaveta Potapova, Eric Tyrode
It has been long recognized that the surface chemistry of silica, and in particular the type and relative amount of surface bound silanol groups, plays a critical role in many of the properties associated with the material, where a typical example is the discrepant adsorption behavior observed depending on the pretreatment history of the surface. However, in spite of its importance, the direct probing of specific surface silanol groups under water has been hampered by instrumental limitations. Here we make use of vibrational sum frequency spectroscopy (VSFS) to first, identify under water the OH stretch of isolated surface silanols, and second, explore its acid/base behavior and dependence on the surface pretreatment method...
April 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28372061/seeing-closing-gesture-of-articulators-affects-speech-perception-of-geminate-consonants
#10
Takayuki Arai, Eri Iwagami, Emi Yanagisawa
This study tests the perception of geminate consonants for native speakers of Japanese using audio and visual information. A previous study showed that formant transitions associated with the closing gesture of articulators at the end of a preceding vowel are crucial for perception of stop geminate consonants in Japanese. In addition, this study further focuses on visual cues, to test if seeing the closing gesture affects perception of geminate consonants. Based on a perceptual experiment, it is observed that visual information can compensate for a deficiency in geminate consonant auditory information, such as formant transitions...
March 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28346750/intuitive-understanding-of-%C3%AF-delocalization-in-loose-and-%C3%AF-localization-in-tight-helical-conformations-of-an-oligosilane-chain
#11
Milena Jovanovic, Dean Antic, David Rooklin, Annika Bande, Josef Michl
Conformational effects on σ-electron delocalization in oligosilanes are addressed by Hartree-Fock and time-dependent density functional theory (B3LYP, 6-311G**) at MP2 optimized geometries of permethylated uniformly helical linear oligosilanes (all-ω-SinR2n+2) up to n = 16 and for backbone dihedral angles ω = 55 - 180̊. The extent of σ delocalization is judged by the partition ratio of the highest occupied molecular orbital and is reflected in the dependence of its shape and energy and of UV absorption spectra on n...
March 27, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28326102/impacted-maxillary-canine-prevalence-and-its-association-with-other-dental-anomalies-in-a-mexican-population
#12
José Rubén Herrera-Atoche, María Del Rosario Agüayo-de-Pau, Mauricio Escoffié-Ramírez, Fernando Javier Aguilar-Ayala, Bertha Arelly Carrillo-Ávila, Marina Eduviges Rejón-Peraza
Objective. We quantified the prevalence of impacted maxillary canines (IMC) and their association with other dental anomalies (DAs). Materials and Methods. A retrospective study was done with 860 patients 12 to 39 years of age. The prevalence of IMC was calculated and compared by sex. The sample was divided into a control group and an impaction group, and the prevalence was calculated in both for a series of anomalies: agenesis, supernumerary teeth, shape anomalies of the upper laterals (microdontia, peg and barrel shape, and talon cusp), fusion, gemination, other impacted teeth, transposition, and amelogenesis imperfecta...
2017: International Journal of Dentistry
https://www.readbyqxmd.com/read/28258688/synthesis-of-4-4-disubstituted-3-methylidenechroman-2-ones-as-potent-anticancer-agents
#13
Rafał Jakubowski, Dorota K Pomorska, Angelika Długosz, Anna Janecka, Urszula Krajewska, Marek Różalski, Marek Mirowski, Tomasz Bartosik, Tomasz Janecki
The synthesis of a new library of 4,4-disubstituted 3-methylidene-3,4-dihydro-2H-chroman-2-ones applying Horner-Wadsworth-Emmons methodology for the construction of an exo-methylidene moiety is reported. Corresponding 3-diethoxyphosphorylchroman-2-ones were synthesized in a three-step reaction sequence consisting of O-methylation of ethyl 2-diethoxyphosphoryl-3-oxoalkanoates, followed by reaction of the obtained 2-diethoxyphosphoryl-3-methoxy-2-alkenoates with phenols or 1-naphthol. The resulting 3-diethoxyphosphorylochromen-2-ones proved to be effective Michael acceptors in reactions with various Grignard reagents...
March 4, 2017: ChemMedChem
https://www.readbyqxmd.com/read/28244225/the-genetic-architecture-of-shoot-root-covariation-during-seedling-emergence-of-a-desert-tree-populus-euphratica
#14
Miaomiao Zhang, Wenhao Bo, Fang Xu, Huan Li, Meixia Ye, Libo Jiang, Chaozhong Shi, Yaru Fu, Guomiao Zhao, Yuejiao Huang, Kirk Gosik, Dan Liang, Rongling Wu
The coordination of shoots and roots is critical for plants to adapt to changing environments by fine-tuning energy production in leaves and the availability of water and nutrients from roots. To understand the genetic architecture of how these two organs covary during developmental ontogeny, we conducted a mapping experiment using Euphrates poplar (Populus euphratica), a so-called hero tree able to grow in the desert. We geminated intraspecific F1 seeds of Euphrates Poplar individually in a tube to obtain a total of 370 seedlings, whose shoot and taproot lengths were measured repeatedly during the early stage of growth...
February 28, 2017: Plant Journal: for Cell and Molecular Biology
https://www.readbyqxmd.com/read/28243645/chiral-crotyl-geminal-bis-silane-a-useful-reagent-for-asymmetric-sakurai-allylation-by-selective-desilylation-enabled-chirality-transfer
#15
Zhiwen Chu, Kai Wang, Lu Gao, Zhenlei Song
Enantioselective synthesis of SiMe3/SiPh2Me-substituted crotyl geminal bis(silane) has been developed. This compound is a useful reagent for Ph3C(+)B(C6F5)4(-)-catalyzed asymmetric Sakurai allylation and one-pot Sakurai allylation/Prins cyclization processes. Chemoselective desilylation of SiPh2Me leads to efficient chirality transfer.
February 28, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28228681/discovery-of-a-new-species-of-hermit-crab-of-the-genus-pylopaguropsis-alcock-1905-from-the-caribbean-den-commensal-or-cleaner-crustacea-anomura-paguridae
#16
Rafael Lemaitre
A new secretive, yet brightly colored hermit crab species of the family Paguridae, Pylopaguropsis mollymulleraesp. n., is fully described based on specimens from the reefs of Bonaire, Lesser Antilles, southern Caribbean Sea. Populations of this new species were discovered and photographed in the Bonaire National Marine Park under a large coral ledge, at a depth of 13.7 m, living in crevices known by scuba divers to serve as den to a pair of "flaming reef lobsters" Enoplometopus antillensis, or a "broad banded moray" Channomuraena vittata...
2017: ZooKeys
https://www.readbyqxmd.com/read/28190675/effectiveness-of-exergaming-in-improving-functional-balance-fatigue-and-quality-of-life-in-parkinson-s-disease-a-pilot-randomized-controlled-trial
#17
REVIEW
Camila Gemin Ribas, Letícia Alves da Silva, Marina Ribas Corrêa, Hélio Ghizone Teive, Silvia Valderramas
Although motor symptoms in Parkinson's disease (PD) are well established, few studies have described the effects of exergaming on the clinical and functional outcomes of PD. OBJECTIVES: To analyze the effectiveness of exergaming in improving functional balance, fatigue, functional exercise capacity and quality of life in PD. METHODS: The study population consisted of 20 patients (12 males and 8 females) aged 61 ± 9.11 years allocated into two groups: an exergaming group (EGG) (n = 10) and a conventional exercise, or control, group (CG) (n = 10)...
February 7, 2017: Parkinsonism & related Disorders
https://www.readbyqxmd.com/read/28178840/surface-chemistry-of-group-11-atomic-layer-deposition-precursors-on-silica-using-solid-state-nuclear-magnetic-resonance-spectroscopy
#18
Peter J Pallister, Seán T Barry
The use of chemical vapour deposition (CVD) and atomic layer deposition (ALD) as thin film deposition techniques has had a major impact on a number of fields. The deposition of pure, uniform, conformal thin films requires very specific vapour-solid reactivity that is largely unknown for the majority of ALD and CVD precursors. This work examines the initial chemisorption of several thin film vapour deposition precursors on high surface area silica (HSAS) using (13)C, (31)P, and quantitative (29)Si nuclear magnetic resonance spectroscopy (NMR)...
February 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28178798/geminate-electron-hole-recombination-in-organic-photovoltaic-cells-a-semi-empirical-theory
#19
Mariusz Wojcik, Artur Nowak, Kazuhiko Seki
We propose a semi-empirical theory which describes the geminate electron-hole separation probability in both homogeneous systems and donor-acceptor heterojunction systems applicable in organic photovoltaics. The theory is based on the results of extensive simulation calculations, which were carried out using various lattice models of the medium and different charge-carrier hopping mechanisms, over the parameter ranges typical for organic solar cells. It is found that the electron-hole separation probability can be conveniently described in terms of measurable parameters by a formula whose functional form is derived from the existing recombination theories, and which contains only one empirical parameter...
February 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28173754/genome-wide-analyses-of-four-major-histone-modifications-in-arabidopsis-hybrids-at-the-germinating-seed-stage
#20
Anyu Zhu, Ian K Greaves, Elizabeth S Dennis, W James Peacock
BACKGROUND: Hybrid vigour (heterosis) has been used for decades in cropping agriculture, especially in the production of maize and rice, because hybrid varieties exceed their parents in plant biomass and seed yield. The molecular basis of hybrid vigour is not fully understood. Previous studies have suggested that epigenetic systems could play a role in heterosis. RESULTS: In this project, we investigated genome-wide patterns of four histone modifications in Arabidopsis hybrids in germinating seeds...
February 7, 2017: BMC Genomics
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