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Boris Itin, Ivan V Sergeyev
Solid-state NMR (SSNMR) is a powerful tool for the elucidation of structure and dynamics in biological macromolecules. Over the years, SSNMR spectroscopists have developed an array of techniques enabling the measurement of internuclear correlations, distances, and torsional angles; these have been applied to the study of a number of biological systems that are difficult to study by X-ray crystallography and solution NMR, including key biological targets such as membrane proteins and amyloid fibrils. Applications of SSNMR to other topic areas, including materials science, pharmaceuticals, and small molecules, have also flourished in recent years...
2018: Methods in Molecular Biology
Jenny Mullen, Annica Börjesson, Oscar Hopcraft, Jenny J Schulze, Magnus Ericsson, Anders Rane, Mikael Lehtihet, Lena Ekström
Micro-doping with testosterone (T) is challenging to detect with the current doping tests. Today, the methods available to detect T are longitudinally monitoring of urine biomarkers in the Athlete Biological Passport (ABP) and measuring the isotopic composition of excreted biomarkers to distinguish the origin of the molecule. In this study, we investigated the detectability of a single dose of 100 mg T gel in 8 healthy male subjects. We also studied which biomarkers were most sensitive to T gel administration, including blood biomarkers...
November 18, 2017: Drug Testing and Analysis
Zhengyi Qu, Weidan Na, Xiaotong Liu, Hua Liu, Xingguang Su
In this paper, we developed a sensitive fluorescence biosensor for tyrosinase (TYR) and acid phosphatase (ACP) activity detection based on nitrogen-doped graphene quantum dots (N-GQDs). Tyrosine could be catalyzed by TYR to generate dopaquinone, which could efficiently quench the fluorescence of N-GQDs, and the degree of fluorescence quenching of N-GQDs was proportional to the concentration of TYR. In the presence of ACP, l-Ascorbic acid-2-phosphate (AAP) was hydrolyzed to generate ascorbic acid (AA), and dopaquinone was reduced to l-dopa, resulting in the fluorescence recovery of the quenched fluorescence by dopaquinone...
January 2, 2018: Analytica Chimica Acta
Kazuo Tsutsui, Tomohiro Matsushita, Kotaro Natori, Takayuki Muro, Yoshitada Morikawa, Takuya Hoshii, Kuniyuki Kakushima, Hitoshi Wakabayashi, Kouichi Hayashi, Fumihiko Matsui, Toyohiko Kinoshita
The atomic scale characterization of dopant atoms in semiconductor devices to establish correlations with the electrical activation of these atoms is the essential to the advancement of contemporary semiconductor process technology. Spectro-photoelectron holography combined with first-principles simulations can determine the local three-dimensional atomic structures of dopant elements, which in turn affect their electronic states. In the work reported herein, this technique was used to examine arsenic (As) atoms doped into a silicon (Si) crystal...
November 17, 2017: Nano Letters
Yan-Fang Guan, Bao-Cheng Huang, Chen Qian, Han-Qing Yu
Dissolved organic matter (DOM) is ubiquitous in aqueous environments and plays a significant role in pollutant mitigation, transformation and organic geochemical circulation. DOM is also capable of forming carcinogenic by-products in the disinfection treatment processes of drinking water. Thus, efficient methods for DOM quantification are highly desired. In this work, a novel sensor for rapid and selective detection of humic substances (HS), a key component of DOM, based on fluorescence quenching of nitrogen-doped carbon quantum dots was developed...
November 17, 2017: Environmental Science & Technology
Qiubo Guo, Yifan Ma, Tingting Chen, Qiuying Xia, Mei Yang, Hui Xia, Yan Yu
Metal sulfides are promising anode materials for sodium-ion batteries due to their large specific capacities. The practical application of metal sulfides in sodium-ion batteries, however, are still limited due to their large volume expansion, poor cycling stability, and sluggish electrode kinetics. In this work, a unique two-dimensional heterostructure of CoSx (CoS and Co9S8) quantum dots embedded N/S-doped carbon nanosheets (CoSx@NSC) is prepared by a facile sol-gel method. The CoSx quantum dots are in-situ formed within ultrafine carbon nanosheets without further sulfidation, thus resulting in ultrafine CoSx particle size and embedded heterostructure...
November 17, 2017: ACS Nano
Zhi-Zhou Li, Liang-Sheng Liao, Xue-Dong Wang
Organic microcrystals are of essential importance for high fluorescence efficiency, ordered molecular packing mode, minimized defects, and smooth shapes, which are extensively applied in organic optoelectronics. The molecular packing mode significantly influences the optical/electrical properties of organic microcrystals, which makes the controllable preparation of organic microcrystals with desired molecular packing mode extremely important. In the study, yellow-emissive α phase organic microcrystals with rectangular morphology and green-emissive β phase perylene microcrystals with rhombic morphology are separately prepared by simply controlling the solution concentration...
November 17, 2017: Small
Mario Thevis, Tiia Kuuranne, Hans Geyer
A number of high profile revelations concerning anti-doping rule violations over the past 12 months has outlined the importance of tackling prevailing challenges and reducing the limitations of the current anti-doping system. At this time, the necessity to enhance, expand and improve analytical test methods in response to the substances outlined in the World Anti-Doping Agency's (WADA) Prohibited List represents an increasingly crucial task for modern sports drug testing programs. The ability to improve analytical testing methods often relies on the expedient application of novel information regarding superior target analytes for sports drug testing assays, drug elimination profiles, alternative test matrices, together with recent advances in instrumental developments...
November 17, 2017: Drug Testing and Analysis
Jingwen Ma, Min Wang, Guangyu Lei, Guoliang Zhang, Fengbao Zhang, Wenchao Peng, Xiaobin Fan, Yang Li
The development of highly efficient and durable non-noble metal electrocatalysts for the hydrogen evolution reaction (HER) is significant for clean and renewable energy research. This work reports the synthesis of N-doped graphene nanosheets supported N-doped carbon coated cobalt phosphide (CoP) nanoparticles via a pyrolysis and a subsequent phosphating process by using polyaniline. The obtained electrocatalyst exhibits excellent electrochemical activity for HER with a small overpotential of -135 mV at 10 mA cm(-2) and a low Tafel slope of 59...
November 17, 2017: Small
Le Yuan, Xiaolong Weng, Ming Zhou, Qingyong Zhang, Longjiang Deng
Chromium-doped TiO2 pigments were synthesized via a solid-state reaction method and studied with X-ray diffraction, SEM, XPS, and UV-VIS-NIR reflectance spectroscopy. The incorporation of Cr(3+) accelerates the transition from the anatase phase to the rutile phase and compresses the crystal lattice. Moreover, the particle morphology, energy gap, and reflectance spectrum of Cr-doped TiO2 pigments is affected by the crystal structure and doping concentration. For the rutile samples, some of the Cr(3+) ions are oxidized to Cr(4+) after sintering at a high temperature, which leads to a strong near-infrared absorption band due to the (3)A2 → (3) T1 electric dipole-allowed transitions of Cr(4+)...
November 17, 2017: Nanoscale Research Letters
Tong Feng, Wenli Liao, Zhongbin Li, Lingtao Sun, Dongping Shi, Chaozhong Guo, Yu Huang, Yi Wang, Jing Cheng, Yanrong Li, Qizhi Diao
Large-scale production of active and stable porous carbon catalysts for oxygen reduction reaction (ORR) from protein-rich biomass became a hot topic in fuel cell technology. Here, we report a facile strategy for synthesis of nitrogen-doped porous nanocarbons by means of a simple two-step pyrolysis process combined with the activation of zinc chloride and acid-treatment process, in which kidney bean via low-temperature carbonization was preferentially adopted as the only carbon-nitrogen sources. The results show that this carbon material exhibits excellent ORR electrocatalytic activity, and higher durability and methanol-tolerant property compared to the state-of-the-art Pt/C catalyst for the ORR, which can be mainly attributed to high graphitic-nitrogen content, high specific surface area, and porous characteristics...
November 17, 2017: Nanoscale Research Letters
T Morlat, A C Fernandes, M Felizardo, A Kling, T A Girard, J G Marques, F P Carvalho
Superheated droplet detectors (SDDs) are traditionally employed in the detection of neutrons. In this work the focus is on the detection of alpha particles using C2ClF5 as the target liquid. The alpha-droplet interaction is examined via computational studies, and a geometric model developed to describe the expected detector response. Experiments with alpha-emitting uranium- and samarium-doped SDDs at temperatures of 5-12°C confirm that the event rate is related to the size of the droplets, and are in model agreement for temperatures below 8°C; above this temperature, the acoustic sensitivity is reduced by signal attenuation as a result of the increasing bubble population, for which the addition of an attenuation coefficient restores the agreement with experiment...
November 15, 2017: Radiation Protection Dosimetry
Meina Yu, Huai Yang, Deng-Ke Yang
When subjected to an AC electric field perpendicular to its layers, the cholesteric planar state may undergo a periodic layer undulation, known as the Helfrich deformation, which generates a color change of the reflected light. The Helfrich deformation of regular cholesteric liquid crystals is, however, unstable and easily taken over by the focal conic state, and thus the color tuning range is narrow. We demonstrated that the Helfrich deformation can be stabilized in a large electric field region by doping a bent dimer with an anomalously small bend elastic constant and dispersing a small amount of polymer network...
November 17, 2017: Soft Matter
Masayuki Suda, Hiroshi M Yamamoto
Stimulated by the discovery of high-temperature superconductivity in 1986, band-filling control of strongly correlated electron systems has been a persistent challenge over the past three decades in condensed matter science. In particular, recent efforts have been focused on electrostatic carrier doping of these materials, utilising field-effect transistor (FET) structures to find novel superconductivity. Our group found the first field-induced superconductivity in an organic-based material in 2013 and has been developing various types of superconducting organic FETs...
November 17, 2017: Physical Chemistry Chemical Physics: PCCP
Tim Senden, Robin G Geitenbeek, Andries Meijerink
Mn(4+)-activated hexafluoroaluminates are promising red-emitting phosphors for white light emitting diodes (w-LEDs). Here, we report the synthesis of Na₃AlF₆:Mn(4+), K₃AlF₆:Mn(4+) and K₂NaAlF₆:Mn(4+) phosphors through a simple two-step co-precipitation method. Highly monodisperse large (~20 μm) smoothed-octahedron shaped crystallites are obtained for K₂NaAlF₆:Mn(4+). The large size, regular shape and small size distribution are favorable for application in w-LEDs. All Mn(4+)-doped hexafluoroaluminates show bright red Mn(4+) luminescence under blue light excitation...
November 17, 2017: Materials
Jiyong Liang, Yizhuo Gu, Zhenchong Zhang, Shaokai Wang, Min Li, Zuoguang Zhang
The compacting structure of chlorine-doped continuous CNT sheet/polyvinylidene fluoride (Cl-CNT sheet/PVDF) was successfully optimized by means of hot-press treatment to improve mechanical and dielectric properties with high densification degree. Then, the densified Cl-CNT sheet/PVDF dielectric layer was inserted between two PVDF insulating layers to fabricate sandwich composite. It is found that the dielectric and mechanical properties are effectively enhanced, with the dielectric permittivity of 40.4 (@102 Hz), dielectric loss of 0...
November 17, 2017: Nanotechnology
Leonid L Rusevich, Guntars Zvejnieks, Alessandro Erba, Roberto Dovesi, Eugene E Kotomin
An enhancement of the piezoelectric properties of lead-free materials, which allow conversion of mechanical energy into electricity, is a task of great importance and interest. Results of first-principles calculations of piezoelectric/electromechanical properties of the Ba(1-x)SrxTiO3 (BSTO) ferroelectric solid solution with perovskite structure are presented and discussed. Calculations are performed within the linear combination of atomic orbitals (LCAO) approximation and periodic-boundary conditions, using advanced hybrid functionals of the density-functional-theory (DFT)...
November 17, 2017: Journal of Physical Chemistry. A
Wei Tian, Jialiang Liu, Yixian Wang, Jingyan Liu, Yanpeng Li, Mingbo Wu
Porous carbons generated from the direct pyrolysis of metal organic frameworks (MOFs) have showed great potential as a kind of promising electrode materials for lithium-ion batteries (LIBs). However, several common drawbacks, such as the inevitable structural damage during carbonization process and intrinsic micropore-dominated feature of MOFs-derived products, largely impede the exposure of active sites and mass transfer, thus usually resulting in inferior electrochemical performances. In this work, an effective and controllable approach was reported to construct nitrogen-doped hierarchical porous carbon nanoframes (N-HPCFs) through in situ pyrolysis transformation of small-sized zeolitic imidazolate frameworks (ZIFs) that are in advance combined with a two-dimensional substrate templated from g-C3N4...
November 17, 2017: ACS Applied Materials & Interfaces
Hongyang Shao, Xiaoming Zhang, Hao Huang, Kan Zhang, Menglong Wang, Cai Zhang, Yifan Yang, Mao Wen, Weitao Zheng
The idea of a core-shell structure can promote the utilization of nonprecious metallic catalysts by enhancing their activity and stability for the oxygen reduction reaction (ORR). Developing a low-cost, high-efficiency, and high-reproducibility method for synthesizing core-shell-structured materials represents an urgent challenge. Here, we fabricate encapsulated Cu nanoparticles with nitrogen-doped onion-like graphite nanoshells (Cu@onion-like N-C) as an efficient ORR catalyst by magnetron sputtering, in which the graphite shells grow by an in situ self-assembly process activated by the surface-catalyzed behavior with Cu nanoparticles...
November 17, 2017: ACS Applied Materials & Interfaces
Yanhong Shi, Lin-Lin Zhang, Tyler B Schon, Huan-Huan Li, Chao-Ying Fan, Xiao-Ying Li, Hai-Feng Wang, Xing-Long Wu, Haiming Xie, Haizhu Sun, Dwight S Seferos, Jingping Zhang
A novel kind of biomass-derived high oxygen containing carbon materials doped with nitrogen that have willow leaf shaped pores was synthesized. The obtained carbon materials have an exotic hierarchical pore structure composed of bowl shaped macropores, willow leaf shaped pores, and an abundance of micropores. This unique hierarchical porous structure provides an effective combination of high current densities with high capacitance due to a pseudocapacitive component that is afforded by the introduction of nitrogen and oxygen dopants...
November 17, 2017: ACS Applied Materials & Interfaces
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