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https://www.readbyqxmd.com/read/28445055/the-molecular-mechanism-of-overhauser-dynamic-nuclear-polarization-in-insulating-solids
#1
Svetlana Pylaeva, Konstantin L Ivanov, Marc Baldus, Daniel Sebastiani, Hossam Elgabarty
Dynamic Nuclear Polarization (DNP), a technique that significantly enhances NMR signals, is experiencing a renaissance owing to enormous methodological developments. In the heart of DNP is a polarization transfer mechanism that endows nuclei with the much larger electronic spin polarization. Polarization transfer via the Overhauser effect is traditionally known to be operative only in liquids and conducting solids. Very recently, surprisingly strong Overhauser effect DNP in insulating solids has been reported, with a DNP efficiency that increases with the magnetic field strength...
April 26, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28444846/forensic-analysis-of-latent-fingermarks-by-silver-assisted-ldi-imaging-ms-on-non-conductive-surfaces
#2
Nidia Lauzon, Martin Dufresne, Alexandre Beaudoin, Pierre Chaurand
Silver-assisted laser desorption ionization (AgLDI) imaging mass spectrometry (IMS) has been demonstrated to be a useful technology for fingermark analysis allowing for the detection of several classes of endogenous as well as exogenous compounds. Ideally, in IMS analyses, the fingermarks are deposited under controlled conditions on metallized conductive target slides. However, in forensic investigations, fingermarks are often found on a variety of non-conductive surfaces. A sputtered silver layer renders the target surface conductive, which allows the analyses of insulating surfaces by time-of-flight (TOF) IMS...
April 26, 2017: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/28443603/hard-x-ray-photoemission-study-of-yb-sub-1-x-sub-zr-sub-x-sub-b-sub-12-sub-the-effects-of-electron-doping-on-the-kondo-insulator-ybb-sub-12-sub
#3
Awabaikeli Rousuli, Hitoshi Sato, Fumitoshi Iga, Kento Hayashi, Katsuya Ishii, Toru Wada, Toshiki Nagasaki, Kojiro Mimura, Hiroaki Anzai, Katsuya Ichiki, Shigenori Ueda, Akihiro Kondo, Koichi Kindo, Toshiro Takabatake, Kenya Shimada, Hirofumi Namatame, Masaki Taniguchi
We have carried out hard x-ray photoemission spectroscopy (HAXPES) of Yb<sub>1-x</sub>Zr<sub>x</sub>B<sub>12</sub> (0 ≤ x ≤ 0.875) to study the effects of electron doping on the Kondo insulator YbB<sub>12</sub>. The Yb valences of Yb<sub>1-x</sub>Zr<sub>x</sub>B<sub>12</sub> at 300 K estimated from the Yb 3d HAXPES spectra decreased after substituting Yb with Zr from 2.93 for YbB<sub>12</sub> to 2.83 for Yb<sub>0...
April 26, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28433994/the-chs4-chromatin-insulator-reduces-the-rate-of-retroviral-vector-mediated-gene-dysregulation-associated-with-aberrant-vector-transcription
#4
Xianyao Zhou, Qiujun Liu, Da Wang, Xuemei Zhang, David W Emery, Chang L Li
Integrating gammaretroviral vectors can dysregulate the expression of cellular genes through a variety of mechanisms, leading to genotoxicity and malignant transformation. Although most attention has focused on the activation of cellular genes by vector enhancers, aberrant fusion transcripts involving cellular gene sequences and vector promoters, vector splice elements, and vector transcription termination sequences have also been mechanistically associated with dysregulated expression of cellular genes. Chromatin insulators have emerged as an effective tool for reducing the frequency of vector-mediated genotoxicity and malignant transformation and have been shown to block the activation of cellular genes by vector enhancers...
April 22, 2017: Cytogenetic and Genome Research
https://www.readbyqxmd.com/read/28430413/bioimaging-with-macromolecular-probes-incorporating-multiple-bodipy-fluorophores
#5
Ek Raj Thapaliya, Yang Zhang, Pravat Dhakal, Adrienne S Brown, James N Wilson, Kevin Collins, Françisco M Raymo
Seven macromolecular constructs incorporating multiple borondipyrromethene (BODIPY) fluorophores along a common poly(methacrylate) backbone with decyl and oligo(ethylene glycol) side chains were synthesized. The hydrophilic oligo(ethylene glycol) components impose solubility in aqueous environment on the overall assembly. The hydrophobic decyl chains insulate effectively the fluorophores from each other to prevent detrimental interchromophoric interactions and preserve their photophysical properties. As a result, the brightness of these multicomponent assemblies is approximately three times greater than that of a model BODIPY monomer...
April 21, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/28430121/synthesis-characterization-and-enhanced-sensing-properties-of-a-nio-zno-p-n-junctions-sensor-for-the-sf%C3%A2-decomposition-byproducts-so%C3%A2-so%C3%A2-f%C3%A2-and-sof%C3%A2
#6
Hongcheng Liu, Qu Zhou, Qingyan Zhang, Changxiang Hong, Lingna Xu, Lingfeng Jin, Weigen Chen
The detection of partial discharge and analysis of the composition and content of sulfur hexafluoride SF₆ gas components are important to evaluate the operating state and insulation level of gas-insulated switchgear (GIS) equipment. This paper reported a novel sensing material made of pure ZnO and NiO-decorated ZnO nanoflowers which were synthesized by a facile and environment friendly hydrothermal process for the detection of SF₆ decomposition byproducts. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the structural and morphological properties of the prepared gas-sensitive materials...
April 21, 2017: Sensors
https://www.readbyqxmd.com/read/28426659/three-distinct-mechanisms-of-long-distance-modulation-of-gene-expression-in-yeast
#7
Manyu Du, Qian Zhang, Lu Bai
Recent Hi-C measurements have revealed numerous intra- and inter-chromosomal interactions in various eukaryotic cells. To what extent these interactions regulate gene expression is not clear. This question is particularly intriguing in budding yeast because it has extensive long-distance chromosomal interactions but few cases of gene regulation over-a-distance. Here, we developed a medium-throughput assay to screen for functional long-distance interactions that affect the average expression level of a reporter gene as well as its cell-to-cell variability (noise)...
April 20, 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28407294/altered-tert-promoter-and-other-genomic-regulatory-elements-occurrence-and-impact
#8
Barbara Heidenreich, Rajiv Kumar
Study of genetic alterations, inherited or acquired, that increase the risk or drive cancers and many other diseases had remained mostly confined to coding sequences of the human genome. Data from genome wide associations studies, development of the Encyclopedia of DNA Elements (ENCODE), and a spurt in detection of driver somatic mutations have shifted focus towards noncoding regions of the human genome. The majority of genetic variants robustly associated with cancers and other syndromes identified through genome wide studies are located within noncoding regulatory regions of the genome...
April 13, 2017: International Journal of Cancer. Journal International du Cancer
https://www.readbyqxmd.com/read/28398029/topological-crystalline-insulator-snte-si-vertical-heterostructure-photodetectors-for-high-performance-near-infrared-detection
#9
Hongbin Zhang, Baoyuan Man, Qi Zhang
Due to the gapless surface state and narrow bulk band gap, the light absorption of topological crystalline insulators covers a broad spectrum ranging from terahertz to infrared, revealing promising applications in new generation optoelectronic devices. To date, the photodetectors based on topological insulators generally suffer from a large dark current and a weaker photocurrent especially under the near-infrared lights, which severely limits the practical application of devices. Owing to the lower excitation energy of infrared lights, the photodetection application of topological crystalline insulators in the near-infrared region relies critically on understanding the preparation and properties of their heterostructures...
April 14, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28381002/highly-n-doped-germanium-on-insulator-microdisks-with-circular-bragg-gratings
#10
Xuejun Xu, Hideaki Hashimoto, Kentarou Sawano, Takuya Maruizumi
We demonstrate germanium (Ge) microdisks surrounded by highly reflective circular Bragg gratings on highly n-doped germanium-on-insulator (GOI) substrate. The GOI substrate is fabricated by wafer bonding from Ge grown on Si substrate, and n-type doping concentration of 2.1×10<sup>19</sup> cm<sup>-3</sup> is achieved by phosphorus diffusion from a spin-on-dopant source. Very sharp Fabry-Perot resonant peaks with high contrast fringes and Q-factors up to 400 are observed near the direct band gap of Ge in photoluminescence spectra...
March 20, 2017: Optics Express
https://www.readbyqxmd.com/read/28370556/bulk-rashba-semiconductors-and-related-quantum-phenomena
#11
REVIEW
Mohammad Saeed Bahramy, Naoki Ogawa
Bithmuth tellurohalides BiTeX (X = Cl, Br and I) are model examples of bulk Rashba semiconductors, exhibiting a giant Rashba-type spin splitting among their both valence and conduction bands. Extensive spectroscopic and transport experiments combined with the state-of-the-art first-principles calculations have revealed many unique quantum phenomena emerging from the bulk Rashba effect in these systems. The novel features such as the exotic inter- and intra-band optical transitions, enhanced magneto-optical response, divergent orbital dia-/para-magnetic susceptibility and helical spin textures with a nontrivial Berry's phase in the momentum space are among the salient discoveries, all arising from this effect...
March 29, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28369051/surface-dominated-conduction-up-to-240%C3%A2-k-in-the-kondo-insulator-smb6-under-strain
#12
A Stern, M Dzero, V M Galitski, Z Fisk, J Xia
SmB6 is a strongly correlated mixed-valence Kondo insulator with a newly discovered surface state, proposed to be of non-trivial topological origin. However, the surface state dominates electrical conduction only below T(∗) ≈ 4 K (ref. ), limiting its scientific investigation and device application. Here, we report the enhancement of T(∗) in SmB6 under the application of tensile strain. With 0.7% tensile strain we report surface-dominated conduction at up to a temperature of 240 K, persisting even after the strain has been removed...
April 3, 2017: Nature Materials
https://www.readbyqxmd.com/read/28366641/metazoan-nuclear-pores-provide-a-scaffold-for-poised-genes-and-mediate-induced-enhancer-promoter-contacts
#13
Pau Pascual-Garcia, Brian Debo, Jennifer R Aleman, Jessica A Talamas, Yemin Lan, Nha H Nguyen, Kyoung J Won, Maya Capelson
Nuclear pore complex components (Nups) have been implicated in transcriptional regulation, yet what regulatory steps are controlled by metazoan Nups remains unclear. We identified the presence of multiple Nups at promoters, enhancers, and insulators in the Drosophila genome. In line with this binding, we uncovered a functional role for Nup98 in mediating enhancer-promoter looping at ecdysone-inducible genes. These genes were found to be stably associated with nuclear pores before and after activation. Although changing levels of Nup98 disrupted enhancer-promoter contacts, it did not affect ongoing transcription but instead compromised subsequent transcriptional activation or transcriptional memory...
April 6, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28358486/separation-of-semiconducting-carbon-nanotubes-for-flexible-and-stretchable-electronics-using-polymer-removable-method
#14
Ting Lei, Igor Pochorovski, Zhenan Bao
Electronics that are soft, conformal, and stretchable are highly desirable for wearable electronics, prosthetics, and robotics. Among the various available electronic materials, single walled carbon nanotubes (SWNTs) and their network have exhibited high mechanical flexibility and stretchability, along with comparable electrical performance to traditional rigid materials, e.g. polysilicon and metal oxides. Unfortunately, SWNTs produced en masse contain a mixture of semiconducting (s-) and metallic (m-) SWNTs, rendering them unsuitable for electronic applications...
March 30, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28358214/making-graphene-nanoribbons-photoluminescent
#15
B V Senkovskiy, M Pfeiffer, S K Alavi, A Bliesener, J Zhu, S Michel, A V Fedorov, R German, D Hertel, D Haberer, L Petaccia, F R Fischer, K Meerholz, P H M van Loosdrecht, K Lindfors, A Grüneis
We demonstrate the alignment-preserving transfer of parallel graphene nanoribbons (GNRs) onto insulating substrates. The photophysics of such samples is characterized by polarized Raman and photoluminescence (PL) spectroscopies. The Raman scattered light and the PL are polarized along the GNR axis. The Raman cross section as a function of excitation energy has distinct excitonic peaks associated with transitions between the one-dimensional parabolic subbands. We find that the PL of GNRs is intrinsically low but can be strongly enhanced by blue laser irradiation in ambient conditions or hydrogenation in ultrahigh vacuum...
April 3, 2017: Nano Letters
https://www.readbyqxmd.com/read/28353107/enhancing-anti-microbial-properties-of-wood-plastic-composites-produced-from-timber-and-plastic-wastes
#16
Lei Wang, Season S Chen, Daniel C W Tsang, Chi Sun Poon, Yong Sik Ok
Considering the resource waste and environmental burden for timber and plastic materials ending up at landfills, this study proposed upcycling wood and plastic waste into value-added wood-plastic composites (WPCs), complying with the standard requirements of flexural strength, thickness swelling, water absorption and thermal insulation. Biological deterioration is a major concern of WPCs. Bacterial survival, fungal attack and algal growth of bactericide-treated WPCs were holistically analysed. Melamine resin was adopted for impregnating anti-microbial agents on the surface...
March 28, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28345012/enhanced-telecom-emission-from-single-group-iv-quantum-dots-by-precise-cmos-compatible-positioning-in-photonic-crystal-cavities
#17
Magdalena Schatzl, Florian Hackl, Martin Glaser, Patrick Rauter, Moritz Brehm, Lukas Spindlberger, Angelica Simbula, Matteo Galli, Thomas Fromherz, Friedrich Schäffler
Efficient coupling to integrated high-quality-factor cavities is crucial for the employment of germanium quantum dot (QD) emitters in future monolithic silicon-based optoelectronic platforms. We report on strongly enhanced emission from single Ge QDs into L3 photonic crystal resonator (PCR) modes based on precise positioning of these dots at the maximum of the respective mode field energy density. Perfect site control of Ge QDs grown on prepatterned silicon-on-insulator substrates was exploited to fabricate in one processing run almost 300 PCRs containing single QDs in systematically varying positions within the cavities...
March 15, 2017: ACS Photonics
https://www.readbyqxmd.com/read/28336835/improving-powder-magnetic-core-properties-via-application-of-thin-insulating-silica-nanosheet-layers-on-iron-powder-particles
#18
Toshitaka Ishizaki, Hideyuki Nakano, Shin Tajima, Naoko Takahashi
A thin, insulating layer with high electrical resistivity is vital to achieving high performance of powder magnetic cores. Using layer-by-layer deposition of silica nanosheets or colloidal silica over insulating layers composed of strontium phosphate and boron oxide, we succeeded in fabricating insulating layers with high electrical resistivity on iron powder particles, which were subsequently used to prepare toroidal cores. The compact density of these cores decreased after coating with colloidal silica due to the substantial increase in the volume, causing the magnetic flux density to deteriorate...
December 23, 2016: Nanomaterials
https://www.readbyqxmd.com/read/28333439/top-down-strategy-to-synthesize-mesoporous-dual-carbon-armored-mno-nanoparticles-for-lithium-ion-battery-anodes
#19
Wei Zhang, Jiannian Li, Jie Zhang, Jinzhi Sheng, Ting He, Meiyue Tian, Yufeng Zhao, Changjun Xie, Liqiang Mai, Shichun Mu
To overcome inferior rate capability and cycle stability of MnO-based materials as a lithium-ion battery anode associated with the pulverization and gradual aggregation during the conversion process, we constructed robust mesoporous N-doped carbon (N-C) protected MnO nanoparticles on reduced graphene oxide (rGO) (MnO@N-C/rGO) by a simple top-down incorporation strategy. Such dual carbon protection endows MnO@N-C/rGO with excellent structural stability and enhanced charge transfer kinetics. At 100 mA g(-1), it exhibits superior rate capability as high as 864...
March 31, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28332818/in-situ-preparation-of-metal-halide-perovskite-nanocrystal-thin-films-for-improved-light-emitting-devices
#20
Lianfeng Zhao, Yao-Wen Yeh, Nhu L Tran, Fan Wu, Zhengguo Xiao, Ross A Kerner, YunHui L Lin, Gregory D Scholes, Nan Yao, Barry P Rand
Hybrid organic-inorganic halide perovskite semiconductors are attractive candidates for optoelectronic applications, such as photovoltaics, light-emitting diodes, and lasers. Perovskite nanocrystals are of particular interest, where electrons and holes can be confined spatially, promoting radiative recombination. However, nanocrystalline films based on traditional colloidal nanocrystal synthesis strategies suffer from the use of long insulating ligands, low colloidal nanocrystal concentration, and significant aggregation during film formation...
April 25, 2017: ACS Nano
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