Quark production, Bose-Einstein condensates and thermalization of the quark-gluon plasma

In this paper, we study the thermalization of gluons and N_f flavors of massless quarks and antiquarks in a spatially homogeneous system. First, two coupled transport equations for gluons and quarks (and antiquarks) are derived within the diffusion approximation of the Boltzmann equation, with only 2 2 processes included in the collision term. Then, these transport equations are solved numerically in order to study the thermalization of the quark-gluon plasma. At initial time, we assume that no quarks or antiquarks are present and we choose the gluon distribution in the form f = f_0 theta (1-p/Q_s) with Q_s the saturation momentum and f_0 a constant. The subsequent evolution of systems may, or may not, lead to the formation of a (transient) Bose condensate, depending on the value of f_0. In fact, we observe, depending on the value of f_0, three different patterns: (a) thermalization without gluon Bose-Einstein condensate (BEC) for f_0 < f_{0t}, (b) thermalization with transient BEC for f_{0t} < f_0 < f_{0c}, and (c) thermalization with BEC for f_{0c} < f_0. The values of f_{0t} and f_{0c} depend on N_f. When f_0> 1 > f_{0c}, the onset of BEC occurs at a finite time t_c ~ 1/((alpha_s f_0)^2 Q_s). We also find that quark production slows down the thermalization process: the equilibration time for N_f = 3 is typically about 5 to 6 times longer than that for N_f = 0 at the same Q_s.Comment: 32 pages, 25 figures, minor modifications, Final version published in NP

(E)-3-(2-Eth­oxy­phen­yl)-1-{4-[(2-fluoro­phen­yl)(4-fluoro­phen­yl)meth­yl]piperazin-1-yl}prop-2-en-1-one

In the title compound, C28H28F2N2O2, the piperazine ring has a chair conformation with the pendant N—C bonds in equatorial orientations. The C=C double bond has an E conformation and the dihedral angle between the fluoro­benzene rings is 70.8 (3)°. In the crystal, mol­ecules are linked by C—H⋯O and C—H⋯F hydrogen bonds

1-[Bis(4-fluoro­phen­yl)meth­yl]-4-[2-(naphthalen-2-yl­oxy)eth­yl]piperazine

In the title mol­ecule, C29H28F2N2O, the piperazine ring adopts a chair conformation with the pendant N—C bonds in equatorial orientations. The conformation of the N—C—C—O linkage is gauche [torsion angle = −64.6 (4)°] and the dihedral angle between the fluoro­benzene rings is 64.02 (15)°

Regulation of Enzyme Activity through Interactions with Nanoparticles

The structure and function of an enzyme can be altered by nanoparticles (NPs). The interaction between enzyme and NPs is governed by the key properties of NPs, such as structure, size, surface chemistry, charge and surface shape. Recent representative studies on the NP-enzyme interactions and the regulation of enzyme activity by NPs with different size, composition and surface modification are reviewed

(E)-1-{4-[Bis(4-fluoro­phen­yl)meth­yl]piperazin-1-yl}-3-(4-eth­oxy­phen­yl)prop-2-en-1-one

In the title mol­ecule, C28H28F2N2O2, the ethene bond exhibits an E conformation and the piperazine ring adopts a chair conformation. The amide-N atom of the piperazine ring is almost planar (bond-angle sum = 358.8°) whereas the other N atom is clearly pyramidal (bond-angle sum = 330.5°). The dihedral angle between the fluoro­benzene rings is 76.36 (17)°. In the crystal, inversion dimers linked by pairs of C—H⋯O hydrogen bonds generate R 2 2(22) loops

Antioxidant and Anti-proliferative Activities of Flavonoids from Bidens pilosa L var radiata Sch Bip

Purpose: To investigate the chemical composition of Bidens pilosa L. var. radiata. Sch Bip. (BP), as well as its antioxidant and anti-proliferative activities.Methods: The whole herb of BP was extracted with 95 % ethanol, which was then partitioned sequentially with petroleum ether, ethyl acetate and n-butyl alcohol to obtain petroleum ether, ethyl acetate (EE-BP), n-BuOH and water fractions. EE-BP was further isolated and purified by repeated column chromatography. The obtained compounds were identified by comparing 1H and 13C nuclear magnetic resonance (NMR) spectra with published data for the compounds. Flavonoids were evaluated for 1,1-diphenyl-2-picrylhydrazy (DPPH) and 2, 2 -azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) free radical scavenging activity by colorimetric methods, while their anti-proliferative effect against human colon cancer RKO cells was determined by 3-(4,5) dimethylthiahiazo (-z-y1)-3,5-diphenytetrazoliumromide (MTT) method.Results: A total of 6 compounds were isolated from BP, including flavonoids or flavonoid glycosides, among which were isoquercitrin (1), vitexin (2), astragalin (3), 5,6,7,4'-tetramethoxylflavone (4), 5,3',4'- trihydroxy-3,7-dimethoxylflavone (5) and quercetin (6). The results indicate that compound 6 was the most effective in both DPPH and ABTS free radical-scavenging assays, with half maximal inhibitory concentration (IC50) of 10.7 μmol/L and 17.5 μmol/L, respectively. Both compounds 4 and 5 exhibited significant growth inhibitory effect on RKO cells with IC50 of 39.08 μmol/L and 17.68 μmol/L, respectively (p &lt; 0.01).Conclusion: BP contains a series of flavonoid compounds, possessing significant antioxidant activity and antiproliferative effect in RKO cells, thus suggesting that it is a potential health supplement and an easily available resource of natural antioxidants for use in colon cancer prevention.Keywords: Bidens pilosa, Flavonoid, Antioxidant, Anti-proliferation, Colon cance

(E)-1-(4-Benzhydrylpiperazin-1-yl)-3-(3,4-dieth­oxy­phen­yl)prop-2-en-1-one ethanol monosolvate

In the title compound, C30H34N2O3·C2H6O, the piperazine ring adopts a chair conformation and the ethene bond exhibits an E conformation. In the crystal, the two components are linked by an O—H⋯O hydrogen bond