9,767 research outputs found
Cytotoxic Effect of Ethanol Extract of Convolvulus arvensis L (Convolvulaceae) on Lymphoblastic Leukemia Jurkat Cells
Purpose: To evaluate the cytotoxic effect of ethanol extract of aerial parts of Convolvulus arvensis against lymphoblastic leukemia, Jurkat cells.Methods: The aerial parts of C. arvensis were collected, identified, powdered and soaked in ethanol. The extract was filtered and evaporated, and the residue assessed for cytotoxic activity in Jurkat cell line. The cells were exposed to different concentrations (10, 25, 50, 75 and 100 μg/mL) of the extract to determine cell viability, cell proliferation, apoptosis using Trypan blue exclusion assay, 3-(4,5- dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and fluorescent activated cell sorter (FACS) analysis, respectively.Results: Trypan blue exclusion assay and MTS assay results indicate that the ethanol extract decreased the number of living cells in a concentration-dependent fashion. The results of FACS analysis showed that the lowest concentration of the extract (10 μg/mL) was most effective for the induction of apoptosis as it induced maximum apoptosis (85.34 %) and the highest concentration (100 μg/mL) was less effective as it induced less apoptosis (53.70 %) in Jurkat cells (p < 0.05).Conclusion: The ethanol extract of C. arvensis has significant cytotoxic activity against the selected cancer cell line. Furthermore, apoptotic effect was more prominent at lower doses and necrosis at higher doses of the extract.Keywords: Convolvulus arvensis; (MTS) 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4- sulfophenyl)-2H-tetrazolium assay; Trypan blue exclusion assay, Apoptosis, Necrosi
Brane-Bulk energy exchange and agegraphic dark energy
We consider the agegraphic models of dark energy in a braneworld scenario
with brane-bulk energy exchange. We assume that the adiabatic equation for the
dark matter is satisfied while it is violated for the agegraphic dark energy
due to the energy exchange between the brane and the bulk. Our study shows that
with the brane-bulk interaction, the equation of state parameter of agegraphic
dark energy on the brane, , can have a transition from normal state where
to the phantom regime where , while the effective equation
of state for dark energy always satisfies .Comment: 13 pages, to appear in IJMP
Anharmonicity, vibrational instability and Boson peak in glasses
We show that a {\em vibrational instability} of the spectrum of weakly
interacting quasi-local harmonic modes creates the maximum in the inelastic
scattering intensity in glasses, the Boson peak. The instability, limited by
anharmonicity, causes a complete reconstruction of the vibrational density of
states (DOS) below some frequency , proportional to the strength of
interaction. The DOS of the new {\em harmonic modes} is independent of the
actual value of the anharmonicity. It is a universal function of frequency
depending on a single parameter -- the Boson peak frequency, which
is a function of interaction strength. The excess of the DOS over the Debye
value is at low frequencies and linear in in the
interval . Our results are in an excellent
agreement with recent experimental studies.Comment: LaTeX, 8 pages, 6 figure
Frequency behavior of Raman coupling coefficient in glasses
Low-frequency Raman coupling coefficient of 11 different glasses is
evaluated. It is found that the coupling coefficient demonstrates a universal
linear frequency behavior near the boson peak maximum and a superlinear
behavior at very low frequencies. The last observation suggests vanishing of
the coupling coefficient when frequency tends to zero. The results are
discussed in terms of the vibration wavefunction that combines features of
localized and extended modes.Comment: 8 pages, 9 figure
Effect of alkali/mixed alkali metal ions on the thermal and spectralcharacteristics of Dy3+:B2O3-PbO-Al2O3-ZnO glasses
Thermal and spectroscopic features of 50 B2O3–10 PbO–10 Al2O3–10 ZnO–(x) Li2O–(y) Na2O–(z) K2O–1.0 Dy2O3 (mol %) (x = 19, y = 0, and z = 0; x = 0, y = 19, and z = 0; x = 0, y = 0, and z = 19; x = 9.5, y = 9.5, and z = 0; x = 9.5, y = 0, and z = 9.5; x = 0, y = 9.5, and z = 9.5) glasses, that were fabricated by utilizing melt-quenching approach, are investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), optical absorption, photoluminescence excitation (PLE), photoluminescence (PL), and PL decay lifetimes. PL spectra for all the Dy3 +-doped samples show emission bands at 453 nm (blue), 482 nm (blue), 573 nm (yellow), 662 nm (red), and 752 nm (red) corresponding to the 4I15/2 → 6H15/2, 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2, and 4F9/2 → 6H9/2 transitions, respectively, upon excitation at 350 nm. Here, Dy3 +: Li–Na glass shows the highest PL intensity for all identified emissions. The yellow-to-blue (Y/B) emission intensity ratio (varied within the range 1.257–1.376), CIE chromaticity coordinates (x,y) (slight variation between (0.3410, 0.3802) and (0.3495, 0.3872), and correlated color temperatures (CCTs) (changed from 4953 K to 5212 K) are calculated following the PL spectra. Dy3 +: 4F9/2 decay curves show non-exponential behavior and are fitted by the Inokuti-Hirayama (I–H) model, where S = 6 shows best fit, indicating dipole-dipole (d-d) interactions for Dy3 + excited (donor) and ground state (acceptor) ions
Decay modes of 250No
The Fragment Mass Analyzer at the ATLAS facility has been used to
unambiguously identify the mass number associated with different decay modes of
the nobelium isotopes produced via 204Pb(48Ca,xn)(252-x)No reactions.
Isotopically pure (>99.7%) 204Pb targets were used to reduce background from
more favored reactions on heavier lead isotopes. Two spontaneous fission
half-lives (t_1/2 = 3.7+1.1-0.8 us and 43+22-15 us) were deduced from a total
of 158 fission events. Both decays originate from 250No rather than from
neighboring isotopes as previously suggested. The longer activity most likely
corresponds to a K-isomer in this nucleus. No conclusive evidence for an alpha
branch was observed, resulting in upper limits of 2.1% for the shorter lifetime
and 3.4% for the longer activity.Comment: RevTex4, 10 pages, 5 figures, submitted to PR
Non-linear electromagnetic response of graphene
It is shown that the massless energy spectrum of electrons and holes in
graphene leads to the strongly non-linear electromagnetic response of this
system. We predict that the graphene layer, irradiated by electromagnetic
waves, emits radiation at higher frequency harmonics and can work as a
frequency multiplier. The operating frequency of the graphene frequency
multiplier can lie in a broad range from microwaves to the infrared.Comment: 5 pages, 3 figure
A texture of neutrino mass matrix in view of recent neutrino experimental results
In view of recent neutrino experimental results such as SNO, Super-Kamiokande
(SK), CHOOZ and neutrinoless double beta decay , we
consider a texture of neutrino mass matrix which contains three parameters in
order to explain those neutrino experimental results. We have first fitted
parameters in a model independent way with solar and atmospheric neutrino mass
squared differences and solar neutrino mixing angle which satisfy LMA solution.
The maximal value of atmospheric neutrino mixing angle comes out naturally in
the present texture. Most interestingly, fitted parameters of the neutrino mass
matrix considered here also marginally satisfy recent limit on effective
Majorana neutrino mass obtained from neutrinoless double beta decay experiment.
We further demonstrate an explicit model which gives rise to the texture
investigated by considering an gauge group with two
extra real scalar singlets and discrete symmetry. Majorana
neutrino masses are generated through higher dimensional operators at the scale
. We have estimated the scales at which singlets get VEV's and M by
comparing with the best fitted results obtained in the present work.Comment: Journal Ref.: Phys. Rev. D66, 053004 (2002
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Challenges in QCD matter physics --The scientific programme of the Compressed Baryonic Matter experiment at FAIR
Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (sNN= 2.7--4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials (μB> 500 MeV), effects of chiral symmetry, and the equation of state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2024, in the context of the worldwide efforts to explore high-density QCD matter
Seesaw tau lepton mass and calculable neutrino masses in a 3-3-1 model
In a version of the 3-3-1 model proposed by Duong and Ma the introduction of
the scalar sextet for giving mass to the charged leptons is avoided by adding a
singlet charged lepton. We show that in this case the lepton gains mass
through a seesaw--like mechanism. Besides we show how to generate neutrino
masses at the tree and at the 1-loop level with the respective
Maki-Nakagawa-Sakata leptonic mixing matrices.Comment: revtex, 5 pages and one eps figure. Published versio
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