We propose a model for an anisotropic dark energy star where we assume that the radial pressure exerted on the system due
to the presence of dark energy is proportional to the isotropic perfect fluid matter density. We discuss various physical
features of our model and show that the model satisfies all the regularity conditions and is stable as well as singularity-free. 相似文献
PS grafted silica nanoparticles have been prepared by a tandem process that simultaneously employs RAFT polymerization and click chemistry. In a single pot procedure, azide‐modified silica, an alkyne functionalized RAFT agent and styrene are combined to produce the desired product. As deduced by thermal gravimetric and elemental analysis, the grafting density of PS on the silica in the tandem process is intermediate between analogous “grafting to” and “grafting from” techniques for preparing PS brushes on silica. Relative rates of RAFT polymerization and click reaction can be altered to control grafting density.
We report, herein, a palladium-catalyzed cascade comprising carbopalladation, 1,4-Pd-migration and C(sp2)−C(sp2) bond formation to construct a variety of bis-heterocyclic frameworks in a single operational step. The methodology provides a direct approach to introduce an oxadiazole core at a remote location without any functional group obligation, with moderate to good yields. 相似文献
An expedient one-pot sequential three-component synthesis of a series of diverse spiroindenoquinoxaline pyrrolidine fused nitrochromene derivatives following 1,3-dipolar cycloaddition of azomethine ylides generated in situ by the condensation of indenoquinoxalone and α-amino acids (L-proline and L-phenyl alanine) with 3-nitrochromenes as dipolarophile under classical as well as microwave irradiation is described. The protocol provides a mild reaction condition, high yield of the products, high regioselectivity, and operational simplicity to assemble complex structural entity in a single operation with good to excellent yield. The regio and stereochemical outcome of the cycloaddition reaction is ascertained by spectroscopic and single crystal X-ray analysis. 相似文献
A new ligand, 1-(2-furanthiocarbo)-3-thiosemicarbazide (H2ftsc), prepared from thiosemicarbazide and carboxymethyl-2-furandithioate, forms complexes [Mn(ftsc)(H2O)2], [Pd(ftsc)] · 2H2O, [M(Hftsc)(acac)2] (M=CoIII or CrIII), [M(Hftsc)2(acac)] (M=MnIII or FeIII) and [Zn(Hftsc)2] · 2H2O, which were characterized by elemental analyses, magnetic susceptibility, i.r., electronic and n.m.r. spectral data. The Mössbauer spectra of [Fe(Hftsc)2(acac)] at 298K and 80K suggest the presence of high-spin iron(III) with an S=5/2 state. In vivo and in vitro antitumour activity of the ligand and the complexes have been screened towards several tumour cell-lines. 相似文献
In this paper we present a comparative study of inelastic interactions of C12-Em and p-Em at 4·5 GeV/c per nucleon. The multiplicity distributions and their correlations have been studied. The results show a strong correlation of ns onnh in the case of C12-Em but not in the case of p-Em. It is also shown that the ns increases with the increase of the projectile mass. The angular distribution of the target fragments in C12-Em shows a massive forward collimation. Comparison is also made in the pseudorapidity distribution of both C12-Em and p-Em, the result shows many interesting features. 相似文献
The debromination of α-bromoketones with an easily accessible ionic liquid, 1-methyl-3-pentylimidazolium tetrafluoroborate, [pmIm]BF4 under microwave irradiation has been investigated. By controlling the reaction time gem-α-dibromoketones are selectively debrominated to either monobromo or debromoketones. The α-monobromo- and α-monoiodoketones are dehalogenated while the corresponding chloroketones remain inert. The activated vic-bromoacetates are converted to the corresponding (E)-alkenes by the same procedure. These reactions do not require any organic solvent, any metal or any conventional reducing agent. The ionic liquid works here as catalyst as well as reaction medium and is recycled without any appreciable loss of its catalytic efficiency. 相似文献
Experimental determination of density, ultrasonic velocity and viscosity of two pyrimidine bases thymine and cytosine along with their respective nucleosides, thymidine and cytidine has been carried out in aqueous urea solutions in the presence of different concentrations of three salts, viz. NaCl, KCl and CaCl2. The experimental data have been used for the
computation of various thermodynamic parameters, viz. apparent molar volume, apparent molar compressibility, coefficients A and B of the Jones-Dole equation, internal pressure, acoustic impedance, etc. Structural studies of solutions under investigation have also been carried out by ultraviolet spectroscopy, and an attempt has been made to collaborate the
findings of ultraviolet spectroscopy with results obtained thermodynamically. 相似文献