3,010 research outputs found
Non-hexagonal-ring defects and structures induced by strain in graphene and in functionalized graphene
We perform {\textit ab initio} calculations for the strain-induced formation
of non-hexagonal-ring defects in graphene, graphane (planar CH), and graphenol
(planar COH). We find that the simplest of such topological defects, the
Stone-Wales defect, acts as a seed for strain-induced dissociation and
multiplication of topological defects. Through the application of inhomogeneous
deformations to graphene, graphane and graphenol with initially small
concentrations of pentagonal and heptagonal rings, we obtain several novel
stable structures that possess, at the same time, large concentrations of
non-hexagonal rings (from fourfold to elevenfold) and small formation energies
On a stationary spinning string spacetime
The properties of a stationary massless string endowed with intrinsic spin
are discussed. The spacetime is Minkowskian geometrically but the topology is
nontrivial due to the horizon located on the surface , similar with
Rindler's case. For less than the Planck length , has the
same sign as and closed timelike curves are possible.
We assume an elementary particles' spin originates in the frame dragging
effect produced by the rotation of the source. The Sagnac time delay is
calculated and proves to be constant.Comment: revised version of hep-th/0602014 v1, 7 pages, title changed, sec.5
removed, talk given at "Recent Developments in Gravity" (NEB XII), Nafplio,
Greece, 29 June 200
How hot can mitochondria be? Incubation at temperatures above 43 °C induces the degradation of respiratory complexes and supercomplexes in intact cells and isolated mitochondria
Mitochondrial function generates an important fraction of the heat that contributes to cellular and organismal temperature maintenance, but the actual values of this parameter reached in the organelles is a matter of debate. The studies addressing this issue have reported divergent results: from detecting in the organelles the same temperature as the cell average or the incubation temperature, to increasing differences of up to 10 degrees above the incubation value. Theoretical calculations based on physical laws exclude the possibility of relevant temperature gradients between mitochondria and their surroundings. These facts have given rise to a conundrum or paradox about hot mitochondria.
We have examined by Blue-Native electrophoresis, both in intact cells and in isolated organelles, the stability of respiratory complexes and supercomplexes at different temperatures to obtain information about their tolerance to heat stress. We observe that, upon incubation at values above 43 °C and after relatively short periods, respiratory complexes, and especially complex I and its supercomplexes, are unstable even when the respiratory activity is inhibited. These results support the conclusion that high temperatures (>43 °C) cause damage to mitochondrial structure and function and question the proposal that these organelles can physiologically work at close to 50 °C
Methane aromatization in a fluidized bed reactor: Parametric study
Methane aromatization is a promising technology for the transformation of natural gas into liquid products, but suffers from the problem of catalyst deactivation by coke. A two-zone fluidized bed reactor has been proposed as a tool to counteract the catalyst deactivation, by providing continuous catalyst regeneration in the same vessel where the main reaction is carried out. This work shows the effect of the main operating conditions (carburization temperature, reaction temperature, carburization time, nature of regenerating agent and feed flow and height of the hydrocarbon entry point). Optimal reduction time and temperature were 1 h and 350°C. Best conversion and selectivity were achieved at 700°C without catalyst deactivation in the TZFBR
Simulação do crescimento e desenvolvimento do trigo irrigado utilizando o modelo CERES-Wheat na região de Campinas - SP.
Este trabalho tem como objetivos apresentar de forma sucinta o funcionamento do modelo CERES-Wheat inserido na plataforma DSSAT 3.5, assim como apresentar os resultados obtidos das simulações realizadas com o modelo e os observados em experimento de campo, em especial a sua capacidade de detectar os efeitos da aplicação de N sob a fenologia e produtividade de grãos do trigo sob irrigação.bitstream/CNPTIA/9961/1/circtec2.pdfAcesso em: 28 maio 2008
Baby MIND: A magnetised spectrometer for the WAGASCI experiment
The WAGASCI experiment being built at the J-PARC neutrino beam line will
measure the difference in cross sections from neutrinos interacting with a
water and scintillator targets, in order to constrain neutrino cross sections,
essential for the T2K neutrino oscillation measurements. A prototype Magnetised
Iron Neutrino Detector (MIND), called Baby MIND, is being constructed at CERN
to act as a magnetic spectrometer behind the main WAGASCI target to be able to
measure the charge and momentum of the outgoing muon from neutrino charged
current interactions.Comment: Poster presented at NuPhys2016 (London, 12-14 December 2016). Title +
4 pages, LaTeX, 6 figure
Synchronization of the Distributed Readout Frontend Electronics of the Baby MIND Detector
Baby MIND is a new downstream muon range detector for the WGASCI experiment. This article discusses the distributed readout system and its timing requirements. The paper presents the design of the synchronization subsystem and the results of its test
Baby MIND Experiment Construction Status
Baby MIND is a magnetized iron neutrino detector, with novel design features,
and is planned to serve as a downstream magnetized muon spectrometer for the
WAGASCI experiment on the T2K neutrino beam line in Japan. One of the main
goals of this experiment is to reduce systematic uncertainties relevant to
CP-violation searches, by measuring the neutrino contamination in the
anti-neutrino beam mode of T2K. Baby MIND is currently being constructed at
CERN, and is planned to be operational in Japan in October 2017.Comment: Poster presented at NuPhys2016 (London, 12-14 December 2016). 4
pages, LaTeX, 7 figure
Baby MIND: A magnetized segmented neutrino detector for the WAGASCI experiment
T2K (Tokai-to-Kamioka) is a long-baseline neutrino experiment in Japan
designed to study various parameters of neutrino oscillations. A near detector
complex (ND280) is located 280~m downstream of the production target and
measures neutrino beam parameters before any oscillations occur. ND280's
measurements are used to predict the number and spectra of neutrinos in the
Super-Kamiokande detector at the distance of 295~km. The difference in the
target material between the far (water) and near (scintillator, hydrocarbon)
detectors leads to the main non-cancelling systematic uncertainty for the
oscillation analysis. In order to reduce this uncertainty a new
WAter-Grid-And-SCintillator detector (WAGASCI) has been developed. A magnetized
iron neutrino detector (Baby MIND) will be used to measure momentum and charge
identification of the outgoing muons from charged current interactions. The
Baby MIND modules are composed of magnetized iron plates and long plastic
scintillator bars read out at the both ends with wavelength shifting fibers and
silicon photomultipliers. The front-end electronics board has been developed to
perform the readout and digitization of the signals from the scintillator bars.
Detector elements were tested with cosmic rays and in the PS beam at CERN. The
obtained results are presented in this paper.Comment: In new version: modified both plots of Fig.1 and added one sentence
in the introduction part explaining Baby MIND role in WAGASCI experiment,
added information for the affiliation
Reduced graphene oxide multilayers for gas and liquid phases chemical sensing
Graphene oxide (GO) multilayers were produced by the layer-by-layer technique after successive immersions of quartz slides into aqueous suspensions of cationic poly(diallyldimethyl ammonium chloride) (PDAC) and anionic GO. The adsorbed amount of GO within the multilayers measured ex situ by UV-vis spectroscopy was found to increase linearly with the number of PDAC-GO bilayers. UV-vis and Raman spectra confirmed the conversion of GO to its reduced form, namely reduced graphene oxide (RGO), when the multilayers were subjected to hot hydrazine. According to AFM images, multilayers are flat with GO sheets forming edge structures. Additionally, impedance spectroscopy provided information regarding the multilayer growth mechanism, which starts with isolated GO sheets that bridge each other after deposition of five PDAC-GO bilayers. As a proof of principle, it was demonstrated that a sensor array composed by reduced multilayers deposited onto interdigitated microelectrodes and interrogated by impedance spectroscopy is capable of discriminating vapours of volatile solvents, including toluene, gasoline, ethanol, chloroform, and acetone, as well as chemicals in aqueous solutions, such as hydrochloric acid, sodium chloride, ammonium hydroxide, and sucrose. This capability was made possible only because the LbL assembly permitted one to tune the sensors' sensitivity with the number of PDAC-GO bilayers. The results presented herein suggest that the reduced PDAC-GO multilayers are promising elements for non-specific chemical sensors.CNPq (308038/2012-6)CAPE
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