1,085 research outputs found
Surface Modification of Natural Rubber by Sulfur hexafluoride (SF6) Plasma Treatment: A New Approach to Improve Mechanical and Hydrophobic Properties
Plasma treatments have faced growing interest as important strategy to modify the hydrophobic/hydrophilic characteristics of materials. However, challenges related to the plasma modification of polymers are the improvement of the chemical resistance without decreasing the mechanical resistance. In this letter, we present for the first time a plasma treatment, using Sulfur hexafluoride (SF6), analogous to vulcanization process, of natural rubber surface, which resulted in a chemical and tension resistance improvements. The natural rubber membranes were coated with glow discharge plasmas generated in sulfur hexafluoride (SF6) atmospheres at a total pressure of 160 mTorr and applying 70 W of radiofrequency. Plasma treatment increases the contact angles from 64° to 125° i.e. leading to a hydrophobic surface. The tension at rupture increased from 3.7 to 6.1 MPa compared to natural rubber without plasma treatment demonstrated by stress-strain investigation. These results provide a fast alternative approach to improve mechanical and chemical properties of rubber-based products
A simulation toolkit for electroluminescence assessment in rare event experiments
A good understanding of electroluminescence is a prerequisite when optimising
double-phase noble gas detectors for Dark Matter searches and high-pressure
xenon TPCs for neutrinoless double beta decay detection.
A simulation toolkit for calculating the emission of light through electron
impact on neon, argon, krypton and xenon has been developed using the Magboltz
and Garfield programs. Calculated excitation and electroluminescence
efficiencies, electroluminescence yield and associated statistical fluctuations
are presented as a function of electric field. Good agreement with experiment
and with Monte Carlo simulations has been obtained
Wheat Production Performance In Response To Nitrogen Sidedressing And Molybdenum Leaf Application
The application of nitrogen (N) at the appropriate time can be effective for crop productivity, changing the grain yield by increasing yield components. Thus, new alternatives that enable a better application of N fertilizer are sought. The aim of this study was to evaluate the components of yield and productivity of wheat cultivated with different doses of N sidedressing and molybdenum (Mo) via leaf application, using two cultivars, CD 150 and Quartzo. The experiment was conducted in the crop years of 2013 and 2014. The experiment used a randomized, factorial 4 x 4 block design, with four replicates. Four doses of N sidedressing in the form of urea were applied (0, 30, 60, and 90 kg ha-1) during tillering. In the same period, leaf molybdic fertilizer was applied, using four dosages of Mo in the form of potassium molybdate (0, 20, 40, and 60 g ha-1). Grain number per ear (GNPE), 1,000-grain mass (TGM), hectoliter weight (HW), and grain productivity (PROD) were evaluated. N fertilizer sidedressing did not promote the yield components of either of the wheat cultivars, although the GNPE of the Quartzo cultivar increased with increasing N doses in both crop years. The increase in N fertilizer increased the PROD of both wheat cultivars. The foliar application of Mo did not promote the yield components or wheat PROD of either cultivar. The HW was influenced by N and Mo rates, and was reduced in the absence of either of these fertilizer elements, indicating that the two nutrients were dependent on each other.3752963297
Polarization Resolved Luminescence In Asymmetric N -type Gaasalgaas Resonant Tunneling Diodes
We have investigated the polarized emission from a n -type GaAsAlGaAs resonant tunneling diode under magnetic field. The GaAs contact layer emission shows a large constant negative circular polarization. A similar result is observed for the quantum well, but only when electrons are injected from the substrate, while for inverted biases, the polarization tends to become positive for small voltages and large laser excitation intensities. We believe that the quantum well polarization may be associated to the partial thermalization of minority carriers on the well subbands and is thus critically dependent on the bias-controlled density of carriers accumulated in the well. © 2008 American Institute of Physics.9214Hanbicki, A., Van Erve, O.M.J., Magno, R., Kioseoglou, G., Li, C.H., Jonker, B.T., Itskos, G., Petrou, A., (2003) Appl. Phys. Lett., 82, p. 4092Jiang, X., Wang, R., Shelby, R.M., MacFarlane, R.M., Bank, S.R., Harris, J.S., Parkin, S.S.P., (2005) Phys. Rev. Lett., 94, p. 056601Motsnyi, V.F., Van Dorpe, P., Van Roy, W., Goovaerts, E., Safarov, V.I., Borghs, G., De Boeck, J., (2003) Phys. Rev. B, 68, p. 245319Fiederling, R., Keim, M., Reuscher, G., Ossau, W., Schmidt, G., Waag, A., Molenkamp, L.W., (1999) Nature (London), 402, p. 787Ohno, Y., Young, D.K., Beschoten, B., Matsukura, F., Ohno, H., Awschalom, D., (1999) Nature (London), 402, p. 790Oestreich, M.J., Hübner, M.J., Hägele, D., Klar, P.J., Heimbrodt, W., Rühle, W.W., Ashenford, D.E., Lunn, B., (1999) Appl. Phys. Lett., 74, p. 1251Jonker, B.T., Park, Y.D., Bennett, B.R., Cheong, H.D., Kioseoglou, G., Petrou, A., (2000) Phys. Rev. B, 62, p. 8180Braden, J.G., Parker, J.S., Xiong, P., Chun, S.H., Samarth, N., (2003) Phys. Rev. Lett., 91, p. 056602Mattana, R., George, J.-M., Jaffr̀s, H., Nguyen Van Dau, F., Fert, A., Ĺpine, B., Guivarc'H, A., J́źquel, G., (2003) Phys. Rev. Lett., 90, p. 166601Gruber, T., Keim, M., Fiederling, R., Reuscher, G., Ossau, W., Schmidt, G., Molenkamp, M., Waag, A., (2001) Appl. Phys. Lett., 78, p. 1101Slobodskyy, A., Gould, C., Slobodskyy, T., Becker, C.R., Schmidt, G., Molenkamp, L.W., (2003) Phys. Rev. Lett., 90, p. 246601De Carvalho, H.B., Galvão Gobato, Y., Brasil, M.J.S.P., Lopez-Richard, V., Marques, G.E., Camps, I., Henini, M., Hill, G., (2006) Phys. Rev. B, 73, p. 155317De Carvalho, H.B., Brasil, M.J.S.P., Galvão Gobato, Y., Marques, G.E., Galeti, H.V.A., Henini, M., Hill, G., (2007) Appl. Phys. Lett., 90, p. 062120Dos Santos, L.F., Galvão Gobato, Y., Marques, G.E., Brasil, M.J.S.P., Henini, M., Airey, R., (2007) Appl. Phys. Lett., 91, p. 073520Snelling, M.J., Blackwood, E., MacDonagh, C.J., Harley, R.T., Foxon, C.T.B., (1992) Phys. Rev. B, 45, p. 392
Spectral method for the time-dependent Gross-Pitaevskii equation with a harmonic trap
We study the numerical resolution of the time-dependent Gross-Pitaevskii
equation, a non-linear Schroedinger equation used to simulate the dynamics of
Bose-Einstein condensates. Considering condensates trapped in harmonic
potentials, we present an efficient algorithm by making use of a spectral
Galerkin method, using a basis set of harmonic oscillator functions, and the
Gauss-Hermite quadrature. We apply this algorithm to the simulation of
condensate breathing and scissors modes.Comment: 23 pages, 5 figure
Transdermal delivery of bisphosphonates using dissolving and hydrogel-forming microarray patches: Potential for enhanced treatment of osteoporosis
As of 2023, more than 200 million people worldwide are living with osteoporosis. Oral bisphosphonates (BPs)are the primary treatment but can cause gastrointestinal (GI) side effects, reducing patient compliance. Microarray (MAP) technology has the potential to overcome GI irritation by facilitating the transdermal delivery ofBPs. This study examines the delivery of alendronic acid (ALN) and risedronate sodium (RDN) using dissolvingand hydrogel-forming MAPs for osteoporosis treatment. In vivo testing on osteoporotic female Sprague Dawleyrats demonstrated the efficacy of MAPs, showing significant improvements in mean serum and bone alkalinephosphatase levels, bone volume, and porosity compared to untreated bilateral ovariectomy (OVX) controls.Specifically, MAP treatment increased mean bone volume to 55.04 ± 2.25 % versus 47.16 ± 1.71 % in OVXcontrols and reduced porosity to 44.30 ± 2.97 % versus 52.84 ± 1.70 % in the distal epiphysis of the femur. Inthe distal metaphysis, bone volume increased to 43.32 ± 3.24 % in MAP-treated rats compared to 24.31 ± 3.21% in OVX controls, while porosity decreased to 55.39 ± 5.81 % versus 75.69 ± 3.21 % in OVX controls. Thisproof-of-concept study indicates that MAP technology has the potential to be a novel, patient-friendly alternativefor weekly osteoporosis management
IKKβ targeting reduces KRAS-induced lung cancer angiogenesis in vitro and in vivo: A potential anti-angiogenic therapeutic target
Objectives: The ability of tumor cells to drive angiogenesis is an important cancer hallmark that positively correlates with metastatic potential and poor prognosis. Therefore, targeting angiogenesis is a rational therapeutic approach and dissecting proangiogenic pathways is important, particularly for malignancies driven by oncogenic KRAS, which are widespread and lack effective targeted therapies. Based on published studies showing that oncogenic RAS promotes angiogenesis by upregulating the proangiogenic NF-κB target genes IL-8 and VEGF, that NF-κB activation by KRAS requires the IKKβ kinase, and that targeting IKKβ reduces KRAS-induced lung tumor growth in vivo, but has limited effects on cell growth in vitro, we hypothesized that IKKβ targeting would reduce lung tumor growth by inhibiting KRAS-induced angiogenesis. Materials and methods: To test this hypothesis, we targeted IKKβ in KRAS-mutant lung cancer cell lines either by siRNA-mediated transfection or by treatment with Compound A (CmpdA), a highly specific IKKβ inhibitor, and used in vitro and in vivo assays to evaluate angiogenesis. Results and conclusions: Both pharmacological and siRNA-mediated IKKβ targeting in lung cells reduced expression and secretion of NF-κB-regulated proangiogenic factors IL-8 and VEGF. Moreover, conditioned media from IKKβ-targeted lung cells reduced human umbilical vein endothelial cell (HUVEC) migration, invasion and tube formation in vitro. Furthermore, siRNA-mediated IKKβ inhibition reduced xenograft tumor growth and vascularity in vivo. Finally, IKKβ inhibition also affects endothelial cell function in a cancer-independent manner, as IKKβ inhibition reduced pathological retinal angiogenesis in a mouse model of oxygen-induced retinopathy. Taken together, these results provide a novel mechanistic understanding of how the IKKβ pathway affects human lung tumorigenesis, indicating that IKKβ promotes KRAS-induced angiogenesis both by cancer cell-intrinsic and cancer cell-independent mechanisms, which strongly suggests IKKβ inhibition as a promising antiangiogenic approach to be explored for KRAS-induced lung cancer therapy
The scintillation and ionization yield of liquid xenon for nuclear recoils
XENON10 is an experiment designed to directly detect particle dark matter. It
is a dual phase (liquid/gas) xenon time-projection chamber with 3D position
imaging. Particle interactions generate a primary scintillation signal (S1) and
ionization signal (S2), which are both functions of the deposited recoil energy
and the incident particle type. We present a new precision measurement of the
relative scintillation yield \leff and the absolute ionization yield Q_y, for
nuclear recoils in xenon. A dark matter particle is expected to deposit energy
by scattering from a xenon nucleus. Knowledge of \leff is therefore crucial for
establishing the energy threshold of the experiment; this in turn determines
the sensitivity to particle dark matter. Our \leff measurement is in agreement
with recent theoretical predictions above 15 keV nuclear recoil energy, and the
energy threshold of the measurement is 4 keV. A knowledge of the ionization
yield \Qy is necessary to establish the trigger threshold of the experiment.
The ionization yield \Qy is measured in two ways, both in agreement with
previous measurements and with a factor of 10 lower energy threshold.Comment: 8 pages, 9 figures. To be published in Nucl. Instrum. Methods
Mean-field description of collapsing and exploding Bose-Einstein condensates
We perform numerical simulation based on the time-dependent mean-field
Gross-Pitaevskii equation to understand some aspects of a recent experiment by
Donley et al. on the dynamics of collapsing and exploding Bose-Einstein
condensates of Rb atoms. They manipulated the atomic interaction by an
external magnetic field via a Feshbach resonance, thus changing the repulsive
condensate into an attractive one and vice versa. In the actual experiment they
changed suddenly the scattering length of atomic interaction from positive to a
large negative value on a pre-formed condensate in an axially symmetric trap.
Consequently, the condensate collapses and ejects atoms via explosion. We find
that the present mean-field analysis can explain some aspects of the dynamics
of the collapsing and exploding Bose-Einstein condensates.Comment: 9 Latex pages, 10 ps and eps files, version accepted in Physical
Review A, minor changes mad
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