431 research outputs found
DESIGN, SYNTHESIS AND BIOLOGICAL EVALUATION OF SOME NEW SUCCINIMIDE, 2-IMINOTHIAZOLINE AND OXAZINE DERIVATIVES BASED BENZOPYRONE AS ANTICONVULSANT AGENTS
Objective: The objective of the present study was to synthesize novel benzopyrone derivatives with potential and safer anticonvulsant activity.Methods: New benzopyrone derivatives have been synthesized and characterized by spectral and elemental analysis. These compounds tested for anticonvulsant activity using the maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) screens (phase 1), which are the most widely employed seizure models for early identification of new anticonvulsant agents. Phase 2 including, neurotoxicity screening and quantitative determination of the median effective dose (ED50), median lethal dose (LD50) and protective index (PI) for the active compounds from phase 1.Results: Compound 12b possessed potent anticonvulsant activity with ED50 values of 94.75 and 70.7 mg/kg in the MES and scPTZ screens respectively, and had LD50 value of 2546 mg/kg after intraperitoneal injection to mice, which provide compound 12b with a wide protective index of 26.87 and 36.01 for MES and scPTZ screens respectively compared to the reference drug Phenobarbital with PI of 12.16 and 20.08, respectively. In addition, compound 12b exhibited mild neurotoxicity at the maximum administrated dose (200 mg/kg).Conclusion: Compound 12b possessed broad spectrum activity for the treatment of all types of seizures, with a wide protective index compared to Phenobarbital. Consequently, compound 12b can be selected as a new bio candidate lead for further study.Keywords: Benzopyrone, Succinimide, 2-Iminothiazoline, Oxazine; Anticonvulsant
Inhibitory Effect of Mediterranean Sage and Rosemary on Clinical and Community Isolates of Methicillin-Resistant Staphylococcus aureus
Abstract Plant extracts are traditionally used for treating many infectious and non-infectious diseases. This study aimed at assessing the inhibitory effect of the ethanol extracts of two medicinal plants; Mediterranean Sage (Salvia libanotica) and Rosemary (Rosmarinus officinalis) on clinical and community strains of methicillin-resistant Staphylococcus aureus (MRSA). Ethanol extracts of the two plants were tested for their antibacterial effect against 25 clinical (n=15, 60%) and community (n=10, 40%) strains of MRSA. Rosemary and Mediterranean Sage extracts demonstrated activity against all isolates, 50μl of 100 mg/ml of each plant extract yielded inhibition zone reaching as high as 27 and 30 mm by agar well diffusion method. Effective MICs and MBCs of ethanol extracts of Rosemary and Mediterranean Sage against MRSA were 0.125 to 0.5mg/ml and0.25 to 1 mg/ml respectively. Mixed ethanol extract of Rosemary and Mediterranean Sage showed antagonistic effect on MRSA strains. These results suggest the potential therapeutic implications of the ethanol extract from Rosemary and Mediterranean sage in the treatment of MRSA infections
Flavonoid-coated gold nanoparticles as efficient antibiotics against gram-negative bacteria—evidence from in silico-supported in vitro studies
Flavonoids are a class of bioactive plant-derived natural products that exhibit a broad range of biological activities, including antibacterial ones. Their inhibitory activity toward Gram-positive bacterial was found to be superior to that against Gram-negative ones. In the present study, a number of flavonoid-coated gold nanoparticles (GNPs) were designed to enhance the antibacterial effects of chrysin, kaempferol, and quercetin against a number of Gram-negative bacteria. The prepared GNPs were able to conjugate to these three flavonoids with conjugation efficiency ranging from 41% to 80%. Additionally, they were able to exert an enhanced antibacterial activity in comparison with the free flavonoids and the unconjugated GNPs. Quercetin-coated GNPs were the most active nano-conjugates and were able to penetrate the cell wall of E. coli. A number of in silico experiments were carried out to explain the conjugation efficiency and the antibacterial mechanisms of these flavonoids as follows: (i) these flavonoids can efficiently bind to the glutathione linker on the surface of GNPs via H-bonding; (ii) these flavonoids, particularly quercetin, were able to increase the bacterial membrane rigidity, and hence decrease its functionality; (iii) these flavonoids can inhibit E. coli’s DNA gyrase (Gyr-B) with IC(50) values ranging from 0.9 to 3.9 µM. In conclusion, these bioactive flavonoid-based GNPs are considered to be very promising antibiotic candidates for further development and evaluation
Highly efficient GaN Doherty power amplifier for N78 sub-6 GHz band 5G applications
In this paper, a high-efficiency GaN Doherty power amplifier (DPA) for 5G applications in the N78 sub-6 GHz band is introduced. The theoretical analysis of the matching networks for the peak and carrier transistors is presented, with a focus on the impact of unequal power splitting for both transistors and the recommendation of a post-harmonic suppression network. The proposed design features an unequal Wilkinson power divider at the input and a post-harmonic suppression network at the output, both of which are crucial for achieving high efficiency. The Doherty power amplifier comprises two GaN 10 W HEMTs, measured across the 3.3 GHz to 3.8 GHz band (the N78 band), and the results reveal significant improvements in gain, output power, drain efficiency, and power-added efficiency. Specifically, the proposed design achieved a power gain of over 12 dB and 42 dBm saturated output power. It also achieved a drain efficiency of 80% at saturation and a power-added efficiency of 75.2%. Furthermore, the proposed harmonic suppression network effectively attenuated the harmonics at the output of the amplifier from the second to the fourth order to more than −50 dB, thus enhancing the device’s linearity
Single Spin Asymmetry in Polarized Proton-Proton Elastic Scattering at GeV
We report a high precision measurement of the transverse single spin
asymmetry at the center of mass energy GeV in elastic
proton-proton scattering by the STAR experiment at RHIC. The was measured
in the four-momentum transfer squared range \GeVcSq, the region of a significant interference between the
electromagnetic and hadronic scattering amplitudes. The measured values of
and its -dependence are consistent with a vanishing hadronic spin-flip
amplitude, thus providing strong constraints on the ratio of the single
spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated
by the Pomeron amplitude at this , we conclude that this measurement
addresses the question about the presence of a hadronic spin flip due to the
Pomeron exchange in polarized proton-proton elastic scattering.Comment: 12 pages, 6 figure
Inclusive charged hadron elliptic flow in Au + Au collisions at = 7.7 - 39 GeV
A systematic study is presented for centrality, transverse momentum ()
and pseudorapidity () dependence of the inclusive charged hadron elliptic
flow () at midrapidity() in Au+Au collisions at
= 7.7, 11.5, 19.6, 27 and 39 GeV. The results obtained with
different methods, including correlations with the event plane reconstructed in
a region separated by a large pseudorapidity gap and 4-particle cumulants
(), are presented in order to investigate non-flow correlations and
fluctuations. We observe that the difference between and
is smaller at the lower collision energies. Values of , scaled by
the initial coordinate space eccentricity, , as a function
of are larger in more central collisions, suggesting stronger collective
flow develops in more central collisions, similar to the results at higher
collision energies. These results are compared to measurements at higher
energies at the Relativistic Heavy Ion Collider ( = 62.4 and 200
GeV) and at the Large Hadron Collider (Pb + Pb collisions at =
2.76 TeV). The values for fixed rise with increasing collision
energy within the range studied (). A comparison to
viscous hydrodynamic simulations is made to potentially help understand the
energy dependence of . We also compare the results to UrQMD
and AMPT transport model calculations, and physics implications on the
dominance of partonic versus hadronic phases in the system created at Beam
Energy Scan (BES) energies are discussed.Comment: 20 pages, 12 figures. Version accepted by PR
Measurements of and Production in + Collisions at = 200 GeV
We report measurements of charmed-hadron (, ) production cross
sections at mid-rapidity in + collisions at a center-of-mass energy of
200 GeV by the STAR experiment. Charmed hadrons were reconstructed via the
hadronic decays , and their charge conjugates,
covering the range of 0.62.0 GeV/ and 2.06.0 GeV/ for
and , respectively. From this analysis, the charm-pair production cross
section at mid-rapidity is = 170 45
(stat.) (sys.) b. The extracted charm-pair cross section is
compared to perturbative QCD calculations. The transverse momentum differential
cross section is found to be consistent with the upper bound of a Fixed-Order
Next-to-Leading Logarithm calculation.Comment: 15 pages, 16 figures. Revised version submitted to Phys. Rev.
Studies of di-jet survival and surface emission bias in Au+Au collisions via angular correlations with respect to back-to-back leading hadrons
We report first results from an analysis based on a new multi-hadron
correlation technique, exploring jet-medium interactions and di-jet surface
emission bias at RHIC. Pairs of back-to-back high transverse momentum hadrons
are used for triggers to study associated hadron distributions. In contrast
with two- and three-particle correlations with a single trigger with similar
kinematic selections, the associated hadron distribution of both trigger sides
reveals no modification in either relative pseudo-rapidity or relative
azimuthal angle from d+Au to central Au+Au collisions. We determine associated
hadron yields and spectra as well as production rates for such correlated
back-to-back triggers to gain additional insights on medium properties.Comment: By the STAR Collaboration. 6 pages, 2 figure
High non-photonic electron production in + collisions at = 200 GeV
We present the measurement of non-photonic electron production at high
transverse momentum ( 2.5 GeV/) in + collisions at
= 200 GeV using data recorded during 2005 and 2008 by the STAR
experiment at the Relativistic Heavy Ion Collider (RHIC). The measured
cross-sections from the two runs are consistent with each other despite a large
difference in photonic background levels due to different detector
configurations. We compare the measured non-photonic electron cross-sections
with previously published RHIC data and pQCD calculations. Using the relative
contributions of B and D mesons to non-photonic electrons, we determine the
integrated cross sections of electrons () at 3 GeV/10 GeV/ from bottom and charm meson decays to be = 4.0({\rm
stat.})({\rm syst.}) nb and =
6.2({\rm stat.})({\rm syst.}) nb, respectively.Comment: 17 pages, 17 figure
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