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Guangqing Wang, Jiang Zhou
Let H be Monge-Ampère singular integral operator, [Formula: see text], and [Formula: see text]. It is proved that the commutator [Formula: see text] is bounded from [Formula: see text] to [Formula: see text] for [Formula: see text] and from [Formula: see text] to [Formula: see text] for [Formula: see text]. For the extreme case [Formula: see text], a weak estimate is given.
2017: Journal of Inequalities and Applications
Patrícia Dias Games, Elói Quintas Gonçalves daSilva, Meire de Oliveira Barbosa, Hebréia Oliveira Almeida-Souza, Patrícia Pereira Fontes, Marcos Jorge deMagalhães-Jr, Paulo Roberto Gomes Pereira, Maura Vianna Prates, Gloria Regina Franco, Alessandra Faria-Campos, Sérgio Vale Aguiar Campos, Maria Cristina Baracat-Pereira
BACKGROUND: Antimicrobial peptides from plants present mechanisms of action that are different from those of conventional defense agents. They are under-explored but have a potential as commercial antimicrobials. Bell pepper leaves ('Magali R') are discarded after harvesting the fruit and are sources of bioactive peptides. This work reports the isolation by peptidomics tools, and the identification and partially characterization by computational tools of an antimicrobial peptide from bell pepper leaves, and evidences the usefulness of records and the in silico analysis for the study of plant peptides aiming biotechnological uses...
December 15, 2016: BMC Genomics
Kathia L Jiménez-Monroy, Nicolas Renaud, Jeroen Drijkoningen, David Cortens, Koen Schouteden, Christian van Haesendonck, Wanda J Guedens, Jean V Manca, Laurens D A Siebbeles, Ferdinand C Grozema, Patrick H Wagner
Determining the mechanism of charge transport through native DNA remains a challenge as different factors such as measuring conditions, molecule conformations, and choice of technique can significantly affect the final results. In this contribution, we have used a new approach to measure current flowing through isolated double-stranded DNA molecules, using fullerene groups to anchor the DNA to a gold substrate. Measurements were performed at room temperature in an inert environment using a conductive AFM technique...
February 16, 2017: Journal of Physical Chemistry. A
W Ngwa
Many efforts have been made to increase diversity in the science workforce. In order for us to be competitive in innovation and ingenuity we need to reach out to any source of intellectual talent. Having greater diversity can only increase the creativity in medical physics. In order for students to succeed academically they need role models and mentors with whom they can identify. Literature has shown that racial and ethnic diversity has both direct and indirect positive effects on the educational outcomes, career advancement and motivation of students...
June 2016: Medical Physics
Marcy C Purnell, Terence J Skrinjar
Chloride channels represent ubiquitously expressed proteins that regulate fundamental cellular processes including membrane potential, maintenance of intracellular pH, and regulation of cell volume. However, mechanisms to modulate this large family of ion channels have remained elusive to date. This large chloride channel family does not appear to operate with selectivity similar to the sodium and potassium channels. These unique channels appear to be bi-directional cotransporters of two or more different molecules or ions across a bilayer phospholipid membrane...
November 2016: Discovery Medicine
Lingzheng Bu, Nan Zhang, Shaojun Guo, Xu Zhang, Jing Li, Jianlin Yao, Tao Wu, Gang Lu, Jing-Yuan Ma, Dong Su, Xiaoqing Huang
Compressive surface strains have been necessary to boost oxygen reduction reaction (ORR) activity in core/shell M/platinum (Pt) catalysts (where M can be nickel, cobalt, or iron). We report on a class of platinum-lead/platinum (PtPb/Pt) core/shell nanoplate catalysts that exhibit large biaxial strains. The stable Pt (110) facets of the nanoplates have high ORR specific and mass activities that reach 7.8 milliampere (mA) per centimeter squared and 4.3 ampere per milligram of platinum at 0.9 volts versus the reversible hydrogen electrode (RHE), respectively...
December 16, 2016: Science
Benedict A Murphy, Andrew J Vick, Marjan Samiepour, Atsufumi Hirohata
An all-metal lateral spin-valve structure has been fabricated with a medial Copper nano-ring to split the diffusive spin-current path. We have demonstrated significant modulation of the non-local signal by the application of a magnetic field gradient across the nano-ring, which is up to 30% more efficient than the conventional Hanle configuration at room temperature. This was achieved by passing a dc current through a current-carrying bar to provide a locally induced Ampère field. We have shown that in this manner a lateral spin-valve gains an additional functionality in the form of three-terminal gate operation for future spintronic logic...
November 21, 2016: Scientific Reports
Mufan Li, Zipeng Zhao, Tao Cheng, Alessandro Fortunelli, Chih-Yen Chen, Rong Yu, Qinghua Zhang, Lin Gu, Boris V Merinov, Zhaoyang Lin, Enbo Zhu, Ted Yu, Qingying Jia, Jinghua Guo, Liang Zhang, William A Goddard, Yu Huang, Xiangfeng Duan
Improving the platinum (Pt) mass activity for the oxygen reduction reaction (ORR) requires optimization of both the specific activity and the electrochemically active surface area (ECSA). We found that solution-synthesized Pt/NiO core/shell nanowires can be converted into PtNi alloy nanowires through a thermal annealing process and then transformed into jagged Pt nanowires via electrochemical dealloying. The jagged nanowires exhibit an ECSA of 118 square meters per gram of Pt and a specific activity of 11.5 milliamperes per square centimeter for ORR (at 0...
December 16, 2016: Science
Abraham Mansouri, Peyman Taheri, Larry W Kostiuk
Magnetic fields induced by currents created in pressure driven flows inside a solid-state charged nanopore were modeled by numerically solving a system of steady state continuum partial differential equations, i.e., Poisson, Nernst-Planck, Ampere and Navier-Stokes equations (PNPANS). This analysis was based on non-dimensional transport governing equations that were scaled using Debye length as the characteristic length scale, and applied to a finite length cylindrical nano-channel. The comparison of numerical and analytical studies shows an excellent agreement and verified the magnetic fields density both inside and outside the nanopore...
November 11, 2016: Scientific Reports
Tuomo Tanttu, Alessandro Rossi, Kuan Yen Tan, Akseli Mäkinen, Kok Wai Chan, Andrew S Dzurak, Mikko Möttönen
Semiconductor-based quantum dot single-electron pumps are currently the most promising candidates for the direct realization of the emerging quantum standard of the ampere in the International System of Units. Here, we discuss a silicon quantum dot single-electron pump with radio frequency control over the transparencies of entrance and exit barriers as well as the dot potential. We show that our driving protocol leads to robust bidirectional pumping: one can conveniently reverse the direction of the quantized current by changing only the phase shift of one driving waveform with respect to the others...
November 8, 2016: Scientific Reports
Dong Rak Kwon, Hyunjung Kwon, Woo Ram Lee, Joonsoo Park
BACKGROUND: Fungi are eukaryotic microorganisms including yeast and molds. Many studies have focused on modifying bacterial growth, but few on fungal growth. Microcurrent electricity may stimulate fungal growth. OBJECTIVE: This study aims to investigate effects of microcurrent electric stimulation on Trichophyton rubrum growth. METHODS: Standard-sized inoculums of T. rubrum derived from a spore suspension were applied to potato dextrose cornmeal agar (PDACC) plates, gently withdrawn with a sterile pipette, and were applied to twelve PDACC plates with a sterile spreader...
October 2016: Annals of Dermatology
Mayank V Jog, Robert X Smith, Kay Jann, Walter Dunn, Belen Lafon, Dennis Truong, Allan Wu, Lucas Parra, Marom Bikson, Danny J J Wang
Transcranial direct current stimulation (tDCS) is an emerging non-invasive neuromodulation technique that applies mA currents at the scalp to modulate cortical excitability. Here, we present a novel magnetic resonance imaging (MRI) technique, which detects magnetic fields induced by tDCS currents. This technique is based on Ampere's law and exploits the linear relationship between direct current and induced magnetic fields. Following validation on a phantom with a known path of electric current and induced magnetic field, the proposed MRI technique was applied to a human limb (to demonstrate in-vivo feasibility using simple biological tissue) and human heads (to demonstrate feasibility in standard tDCS applications)...
October 4, 2016: Scientific Reports
E O Haberal, A SalmanOgli, B Nasseri
In this article, a patch-clamp low noise current amplification based on nanoparticles plasmonic radiation is analyzed. It is well-known, a very small current is flowing from different membrane channels and so, for extra processing the current amplification is necessary. It is notable that there are some problems in traditional electronic amplifier due to its noise and bandwidth problem. Because of the important role of the patch-clamp current in cancer research and especially its small amplitude, it is vital to intensify it without adding any noises...
October 2016: IET Nanobiotechnology
Jacob Rubinstein, Gershon Wolansky
The problem of phase retrieval from intensity measurements is examined for the case of dissipative wave equations. Unlike the conservative case, it is not clear if and when the problem is solvable at all. We provide two solutions. First, it is shown that, for a certain class of dissipating potentials, the problem can be fully solved by converting it through a simple transformation to the framework of the weighted least action principle. Second, for all other dissipating potentials, a deep result from the theory of elliptic partial differential equations is used to show that the problem is always solvable up to a scaling of one of the measured intensities...
August 1, 2016: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Dustin T Offermann, Dale R Welch, Dave V Rose, Carsten Thoma, Robert E Clark, Chris B Mostrom, Andrea E W Schmidt, Anthony J Link
Fusion yields from dense, Z-pinch plasmas are known to scale with the drive current, which is favorable for many potential applications. Decades of experimental studies, however, show an unexplained drop in yield for currents above a few mega-ampere (MA). In this work, simulations of DD Z-Pinch plasmas have been performed in 1D and 2D for a constant pinch time and initial radius using the code Lsp, and observations of a shift in scaling are presented. The results show that yields below 3 MA are enhanced relative to pure thermonuclear scaling by beamlike particles accelerated in the Rayleigh-Taylor induced electric fields, while yields above 3 MA are reduced because of energy lost by the instability and the inability of the beamlike ions to enter the pinch region...
May 13, 2016: Physical Review Letters
Zhen Zhang, Lixin Yan, Yingchao Du, Zheng Zhou, Xiaolu Su, Lianmin Zheng, Dong Wang, Qili Tian, Wei Wang, Jiaru Shi, Huaibi Chen, Wenhui Huang, Wei Gai, Chuanxiang Tang
High-intensity trains of electron bunches with tunable picosecond spacing are produced and measured experimentally with the goal of generating terahertz (THz) radiation. By imposing an initial density modulation on a relativistic electron beam and controlling the charge density over the beam propagation, density spikes of several-hundred-ampere peak current in the temporal profile, which are several times higher than the initial amplitudes, have been observed for the first time. We also demonstrate that the periodic spacing of the bunch train can be varied continuously either by tuning launching phase of a radio-frequency gun or by tuning the compression of a downstream magnetic chicane...
May 6, 2016: Physical Review Letters
P Veltri, V Antoni, P Agostinetti, M Brombin, K Ikeda, M Kisaki, H Nakano, E Sartori, G Serianni, Y Takeiri, K Tsumori
At National Institute for Fusion Science (NIFS), a multi-ampere negative ion source is used to support the R&D on H(-) production, extraction, and acceleration. In this contribution, we study the characteristics of the acceleration system of this source, in order to characterize the beam optics at different operational conditions. A dedicated experimental campaign was carried out at NIFS, using as main diagnostic the infra-red imaging of the beam profiles. The experimental measurements are also compared with 3D numerical simulations, in order to validate the codes and to assess their degree of reliability...
February 2016: Review of Scientific Instruments
E M Oks, M V Shandrikov, A V Vizir
An ion source based on a hollow-cathode Penning discharge was switched to a high-current pulsed mode (tens of amperes and tens of microseconds) to produce an intense hydrogen ion beam. With molecular hydrogen (H2), the ion beam contained three species: H(+), H2(+), and H3(+). For all experimental conditions, the fraction of H2 (+) ions in the beam was about 10 ÷ 15% of the total ion beam current and varied little with ion source parameters. At the same time, the ratio of H(+) and H3(+) depended strongly on the discharge current, particularly on its distribution in the gap between the hollow and planar cathodes...
February 2016: Review of Scientific Instruments
N Pilan, V Antoni, A De Lorenzi, G Chitarin, P Veltri, E Sartori
A scheme of a neutral beam injector (NBI), based on electrostatic acceleration and magneto-static deflection of negative ions, is proposed and analyzed in terms of feasibility and performance. The scheme is based on the deflection of a high energy (2 MeV) and high current (some tens of amperes) negative ion beam by a large magnetic deflector placed between the Beam Source (BS) and the neutralizer. This scheme has the potential of solving two key issues, which at present limit the applicability of a NBI to a fusion reactor: the maximum achievable acceleration voltage and the direct exposure of the BS to the flux of neutrons and radiation coming from the fusion reactor...
February 2016: Review of Scientific Instruments
G Yu Yushkov, A G Nikolaev, E M Oks, V P Frolova
High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam...
February 2016: Review of Scientific Instruments
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