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https://www.readbyqxmd.com/read/29346527/progesterone-effects-on-extracellular-vesicles-in-the-sheep-uterus
#1
Gregory W Burns, Kelsey E Brooks, Eleanore V O'Neil, Darren E Hagen, Susanta K Behura, Thomas E Spencer
Progesterone (P4) acts via the endometrium to promote conceptus growth and implantation for pregnancy establishment. Many cells release extracellular vesicles (EVs) that are membrane-bound vesicles of endosomal and plasma membrane origin. In sheep, endometrial-derived EVs were found to traffic to the conceptus trophectoderm. Thus, EVs are hypothesized to be an important mode of intercellular communication by transferring select RNAs, proteins, and lipids between the endometrium and conceptus. Electron microscopy analysis found that the endometrial luminal and glandular epithelia were the primary source of EVs in the uterus of cyclic sheep...
January 16, 2018: Biology of Reproduction
https://www.readbyqxmd.com/read/29345954/irradiation-induced-palladium-catalyzed-decarboxylative-heck-reaction-of-aliphatic-n-acyloxy-phthalimides-at-room-temperature
#2
Guang-Zu Wang, Rui Shang, Yao Fu
It is reported that Pd(PPh3)2Cl2 in combination with 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos) under irradiation of blue LEDs efficiently catalyzes a decarboxylative Heck reaction of vinyl arenes and vinyl heteroarenes with aliphatic N-(acyloxy)phthalimides at room temperature. A broad scope of secondary, tertiary, and quaternary carboxylates, including α-amino acid derived esters, can be applied as amenable substrates with high stereoselectivity. The experimental observation was explained by excitation-state reactivity of the palladium complex under irradiation to induce single-electron transfer to activate N-(acyloxy)phthalimides, and to suppress undesired β-hydride elimination of alkyl palladium intermediates...
January 18, 2018: Organic Letters
https://www.readbyqxmd.com/read/29345943/oxycyanation-of-vinyl-ethers-with-2-2-6-6-tetramethyl-n-oxopiperidinium-enabled-by-electron-donor-acceptor-complex
#3
Jia-Li Liu, Ze-Fan Zhu, Feng Liu
An efficient and mild oxycyanation of vinyl ethers with 2,2,6,6-tetramethyl-N-oxopiperidinium and TMSCN is described. The mechanistic studies indicated that the formation of an electron donor-acceptor complex and subsequent single-electron-transfer process could be involved in the reaction.
January 18, 2018: Organic Letters
https://www.readbyqxmd.com/read/29345699/theoretical-investigations-on-the-unsymmetrical-effect-of-%C3%AE-link-zn-porphyrin-sensitizers-on-the-performance-for-dye-sensitized-solar-cells
#4
Miao Xie, Fu-Quan Bai, Jinjian Wang, Yue-Qing Zheng, Zhenyang Lin
Dye sensitizers play an important role in dye-sensitized solar cells (DSSCs). As a promising strategy for the design of novel porphyrin sensitizers, the asymmetric modification of the porphyrin ring to meso-link porphyrin sensitizer has emerged in recent years, which can improve the light-harvesting properties and enhance the electron distribution. In this work, in order to reveal the essence of the effect of unsymmetrical substitution on the performance of β-link porphyrin dyes in DSSCs, four kinds of common β-link porphyrin dyes with different structures are calculated by using density functional theory (DFT) and time-dependent density functional theory (TD-DFT)...
January 18, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29345637/structural-basis-of-rna-polymerase-iii-transcription-initiation
#5
Guillermo Abascal-Palacios, Ewan Phillip Ramsay, Fabienne Beuron, Edward Morris, Alessandro Vannini
RNA polymerase (Pol) III transcribes essential non-coding RNAs, including the entire pool of transfer RNAs, the 5S ribosomal RNA and the U6 spliceosomal RNA, and is often deregulated in cancer cells. The initiation of gene transcription by Pol III requires the activity of the transcription factor TFIIIB to form a transcriptionally active Pol III preinitiation complex (PIC). Here we present electron microscopy reconstructions of Pol III PICs at 3.4-4.0 Å and a reconstruction of unbound apo-Pol III at 3.1 Å...
January 17, 2018: Nature
https://www.readbyqxmd.com/read/29345472/current-driven-motion-of-domain-boundaries-between-skyrmion-lattice-and-helical-magnetic-structure
#6
Kiyou Shibata, Toshiaki Tanigaki, Tetsuya Akashi, Hiroyuki Shinada, Ken Harada, Kodai Niitsu, Daisuke Shindo, Naoya Kanazawa, Yoshinori Tokura, Taka-Hisa Arima
To utilize magnetic skyrmions, nano-scale vortex-like magnetic structure, experimental elucidation of their dynamics against current application in various circumstances such as in confined structure and mixture of different magnetic phases is indispensable. Here, we investigate the current-induced dynamics of the coexistence state of magnetic skyrmions and helical magnetic structure in a thin plate of B20-type helimagnet FeGe in terms of in-situ realspace observation using Lorentz transmission electron microscopy (TEM)...
January 18, 2018: Nano Letters
https://www.readbyqxmd.com/read/29345462/fluorescent-zn-pdc-tb3-coordination-polymer-nanostructure-a-candidate-for-highly-selective-detections-of-cefixime-antibiotic-and-acetone-in-aqueous-system
#7
Hong Pan, Sufan Wang, Xiaoyao Dao, Yonghong Ni
Tb3+-doped zinc-based coordination polymer nanospindle bundles (Zn-PDC/Tb3+, or [Zn(2,5-PDC)(H2O)2]·H2O/Tb3+) were synthesized by a simple solution precipitation route at room temperature, employing Zn(NO3)2, Tb(NO3)3, and 2,5-Na2PDC as the initial reactants, and a mixture of water and ethanol with the volume ratio of 10:10 as the solvent. The as-obtained nanostructures presented strong fluorescent emission under the excitation of 298 nm light, which was attributed to the characteristic emission of the Tb3+ ion...
January 18, 2018: Inorganic Chemistry
https://www.readbyqxmd.com/read/29345248/photo-assisted-hysteresis-of-electronic-transport-for-zno-nanowire-transistors
#8
Qianqian Du, Jiandong Ye, Zhonghua Xu, Shunming Zhu, Kun Tang, Shulin Gu, Youdou Zheng
Recently, ZnO nanowire field effect transistors (FETs) have received renewed interest due to their extraordinary low dimensionality and high sensitivity to external chemical environment and illumination conditions. These prominent properties have the promising potential in the nanoscale chemical and photo-sensors. In this article, we have fabricated ZnO nanowire FETs and have found hysteresis behaviors in their transfer characteristics. The mechanism and dynamics of the hysteresis phenomena have been investigated in detail by varying the sweeping rate and range of the gate bias with and without light irradiation...
January 18, 2018: Nanotechnology
https://www.readbyqxmd.com/read/29345246/graphene-based-stretchable-and-transparent-moisture-barrier
#9
Sejeong Won, DoVan Lam, Jin Young Lee, Hyun-June Jung, Min Hur, Kwang-Seop Kim, Hak-Joo Lee, Jae-Hyun Kim
We propose an alumina-deposited double-layer graphene as a transparent, scalable, and stretchable barrier against moisture; this barrier is indispensable for foldable or stretchable organic displays and electronics. Both the barrier property and stretchability were significantly enhanced through the introduction of double-layer graphene between alumina and a polymeric substrate. Double-layer graphene with negligible polymeric residues was coated on the polymeric substrate via a scalable dry transfer method in a roll-to-roll manner; an alumina layer was deposited on the graphene via atomic layer deposition...
January 18, 2018: Nanotechnology
https://www.readbyqxmd.com/read/29345243/electronic-and-mechanical-response-of-graphene-on-batio-sub-3-sub-at-martensitic-phase-transitions
#10
Tim Verhagen, Vaclav Vales, Martin Kalbac, Jana Vejpravova
Graphene is extremely sensitive to optical, electrical and mechanical stimuli, which cause a significant variation of the band structure, thus physiochemical properties. In our work, we report on changes of strain and doping in graphene grown by chemical vapor deposition (CVD) and transferred onto a BaTiO3(100) (BTO) single-crystal. The BTO is known as a ferroelectric material, which undergoes several thermoelastic martensitic phase transitions when it is cooled from 300 K to 10K. In order to enhance the very weak Raman signal of the graphene monolayer (ML) on the BTO, a 15 nm thin gold layer was deposited on top of the graphene ML to benefit from the surface enhanced Raman scattering (SERS)...
January 18, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29345133/stable-organic-radicals-as-hole-injection-dopants-for-efficient-optoelectronics
#11
Zhengyang Bin, Haoqing Guo, Ziyang Liu, Feng Li, Lian Duan
Precursors of reactive organic radicals have been widely used as n-dopants in electron-transporting materials to improve electron-conductivity and enhance electron-injection. However, the utilization of organic radicals in hole-counterparts has been ignored. In this work, stable organic radicals have been proved for the first time to be efficient dopants to enhance hole injection. From the absorbance spectra and the ultraviolet photoelectron spectra, we could observe an efficient electron transfer between the organic radical (4-N-carbazolyl-2,6-dichlorophenyl)bis(2,4,6-trichlorophenyl)methyl, TTM-1Cz) and the widely used hole injection material (1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile, HAT-CN)...
January 18, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29344598/hot-kinetic-model-as-a-guide-to-improve-organic-photovoltaic-materials
#12
Andrey Yu Sosorev, Dmitry Yu Godovsky, Dmitry Yu Paraschuk
The modeling of organic solar cells (OSCs) can provide a roadmap for their further improvement. Many OSC models have been proposed in recent years; however, the impact of the key intermediates from photons to electricity-hot charge-transfer (CT) states-on the OSC efficiency is highly ambiguous. In this study, we suggest an analytical kinetic model for OSC that considers a two-step charge generation via hot CT states. This hot kinetic model allowed us to evaluate the impact of different material parameters on the OSC performance: the driving force for charge separation, optical bandgap, charge mobility, geminate recombination rate, thermalization rate, average electron-hole separation distance in the CT state, dielectric permittivity, reorganization energy and charge delocalization...
January 18, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29343758/electronic-properties-of-synthetic-shrimp-pathogens-derived-dna-schottky-diodes
#13
Nastaran Rizan, Chan Yen Yew, Maryam Rajabpour Niknam, Jegenathan Krishnasamy, Subha Bhassu, Goh Zee Hong, Sridevi Devadas, Mohamed Shariff Mohd Din, Hairul Anuar Tajuddin, Rofina Yasmin Othman, Siew Moi Phang, Mitsumasa Iwamoto, Vengadesh Periasamy
The exciting discovery of the semiconducting-like properties of deoxyribonucleic acid (DNA) and its potential applications in molecular genetics and diagnostics in recent times has resulted in a paradigm shift in biophysics research. Recent studies in our laboratory provide a platform towards detecting charge transfer mechanism and understanding the electronic properties of DNA based on the sequence-specific electronic response, which can be applied as an alternative to identify or detect DNA. In this study, we demonstrate a novel method for identification of DNA from different shrimp viruses and bacteria using electronic properties of DNA obtained from both negative and positive bias regions in current-voltage (I-V) profiles...
January 17, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29343612/structural-and-functional-characterisation-of-the-cytochrome-p450-enzyme-cyp268a2-from-mycobacterium-marinum
#14
Stella A Child, Elise F Naumann, John B Bruning, Stephen G Bell
Members of the cytochrome P450 monooxygenase family CYP268 are found across a broad range of Mycobacterium species including the pathogens Mycobacterium avium, M. colombiense,M. kansasii and Mmarinum CYP268A2, from M. marinum , which is the first member of this family to be studied, was purified and characterised. CYP268A2 was found to bind a variety of substrates with high affinity, including branched and straight-chain fatty acids (C10-C12), acetate esters, and aromatic compounds. The enzyme was also found to bind phenylimidazole inhibitors but not larger azoles, such as ketoconazole...
January 17, 2018: Biochemical Journal
https://www.readbyqxmd.com/read/29343059/top-down-characterization-of-heavily-modified-histones-using-193-nm-ultraviolet-photodissociation-uvpd-mass-spectrometry
#15
Sylvester M Greer, Jennifer S Brodbelt
The characterization of protein post-translational modifications (PTMs) remains a significant challenge for traditional bottom-up proteomics methods owing to the lability of PTMs and the difficulty of mapping combinatorial patterns of PTMs based on analysis of small peptides. These shortcomings have accelerated interest in top-down MS/MS methods which focus on analysis of intact proteins. Mapping all protein PTMs simultaneously requires the ability to obtain extensive sequence coverage to allow confident localization of the modifications...
January 18, 2018: Journal of Proteome Research
https://www.readbyqxmd.com/read/29342351/organic-mixed-valence-compounds-derived-from-cyclic-alkyl-amino-carbenes
#16
Max M Hansmann, Mohand Melaimi, Guy Bertrand
Readily available room temperature stable organic mixed valence compounds are prepared by one-electron reduction of cyclic bis(iminium) salts [derived from cyclic (alkyl)(amino)carbenes] bridged by various spacers. These compounds show characteristic intervalence charge transfer (IV-CT) bands in the near-infrared (NIR). Cyclic voltammetry, EPR, IR, UV-VIS and X-ray studies, as well as DFT calculations, show that depending on the nature of the spacer, these mixed valence compounds range from class III to borderline class I/II...
January 17, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29341630/terahertz-sum-frequency-excitation-of-a-raman-active-phonon
#17
Sebastian Maehrlein, Alexander Paarmann, Martin Wolf, Tobias Kampfrath
In stimulated Raman scattering, two incident optical waves induce a force oscillating at the difference of the two light frequencies. This process has enabled important applications such as the excitation and coherent control of phonons and magnons by femtosecond laser pulses. Here, we experimentally and theoretically demonstrate the so far neglected up-conversion counterpart of this process: THz sum-frequency excitation of a Raman-active phonon mode, which is tantamount to two-photon absorption by an optical transition between two adjacent vibrational levels...
September 22, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29341626/hierarchically-patterned-noncovalent-functionalization-of-2d-materials-by-controlled-langmuir-schaefer-conversion
#18
Tyson C Davis, Jae Jin Bang, Jacob T Brooks, David G McMillan, Shelley A Claridge
Noncovalent monolayer chemistries are often used to functionalize 2D materials. Nanoscopic ligand ordering has been widely demonstrated (e.g., lying-down lamellar phases of functional alkanes); however, combining this control with micro- and macroscopic patterning for practical applications remains a significant challenge. A few reports have demonstrated that standing phase Langmuir films on water can be converted into nanoscopic lying-down molecular domains on 2D substrates (e.g., graphite), using horizontal dipping (Langmuir-Schaefer, LS, transfer)...
January 17, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29341612/stabilization-of-nabh4-in-methanol-using-a-catalytic-amount-of-naome-reduction-of-esters-and-lactones-at-room-temperature-without-solvent-induced-loss-of-hydride
#19
Prasanth C P, Ebbin Joseph, Abhijith A, Nair D S, Ibrahim Ibnusaud, Jevgenij Raskatov, Bakthan Singaram
Rapid reaction of NaBH4 with MeOH precludes its use as a solvent for large-scale ester reductions. We have now learned that a catalytic amount of NaOMe (5 mol %) stabilizes NaBH4 solutions in methanol at 25 °C and permits the use of these solutions for the reduction of esters to alcohols. The generality of this reduction method was demonstrated using 22 esters including esters of naturally occurring chiral γ-butyrolactone containing dicarboxylic acids. This method permits the chemoselective reductions of esters in the presence of cyano and nitro groups and the reductive cyclization of a pyrrolidinedione ester to a fused five-membered furo[2,3-b]pyrrole and a (-)-crispine A analogue in high optical and chemical yields...
January 17, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29341596/core-shell-zif-8-zif-67-derived-cop-nanoparticles-embedded-n-doped-carbon-nanotube-hollow-polyhedron-for-efficient-over-all-water-splitting
#20
Yuan Pan, Kaian Sun, Shoujie Liu, Xing Cao, Konglin Wu, Weng-Chon Cheong, Zheng Chen, Yu Wang, Yang Li, Yunqi Liu, Dingsheng Wang, Qing Peng, Chen Chen, Yadong Li
The construction of highly active and stable non-noble metal electrocatalysts for hydrogen and oxygen evolution reactions electrocatalysts is a major challenge for overall water splitting. Herein, we report a novel hybrid nanostructure with CoP na-noparticles (NPs) embedded in N-doped carbon nanotube hollow polyhedron (NCNHP) through a pyrolysis-oxidation-phosphidation strategy derived from core-shell ZIF-8@ZIF-67. Benefiting from the synergistic effects between highly active CoP NPs and NCNHP, the CoP/NCNHP hybrid exhibited outstanding bifunctional electrocatalytic performances...
January 17, 2018: Journal of the American Chemical Society
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