Synthesis,characterization, thermal properties,and antimicrobial activity of 4‐chloro‐3‐methyl phenyl methacrylate/8‐quinolinyl methacrylate copolymers

4‐Chloro‐3‐methyl phenyl methacrylate (CMPM) and 8‐quinolinyl methacrylate (8‐QMA) were synthesized through the reaction of 4‐chloro‐3‐methyl phenol and 8‐hydroxy quinoline, respectively, with methacryloyl chloride. The homopolymers and copolymers were prepared by free‐radical polymerization with azobisisobutyronitrile as the initiator at 70 °C. Copolymers of CMPM and 8‐QMA of different compositions were prepared. The monomers were characterized with IR spectroscopy and ¹H NMR techniques. The copolymers were characterized with IR spectroscopy. UV spectroscopy was used to obtain the compositions of the copolymers. The monomer reactivity ratios were calculated with the Fineman–Ross method. The molecular weights and polydispersity values of the copolymers were determined with gel permeation chromatography. The thermal stability of the polymers was evaluated with thermogravimetric analysis under a nitrogen atmosphere. The homopolymers and copolymers were tested for their antimicrobial activity againstbacteria, fungi, and yeast. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 157–167, 2005     

Thermal decomposition of hydrotalcite with chromate, molybdate or sulphate in the interlayer

The thermal decomposition of hydrotalcites with chromate, molybdate and sulphate in the interlayer has been studied using thermogravimetric analysis coupled to a mass spectrometer measuring the gas evolution. X-ray diffraction shows the hydrotalcites have a d(0 0 3) spacing of 7.98 Å with very small differences in the d-spacing between the three hydrotalcites. XRD was also used to determine the products of the thermal decomposition. For the sulphate-hydrotalcite decomposition the products were MgO and a spinel MgAl₂O₄, for the chromate interlayered hydrotalcite MgO, Cr₂O₃ and spinel. For the molybdate interlayered hydrotalcite the products were MgO, spinel and MgMoO₄. EDX analyses enabled the formula of the hydrotalcites to be determined. Two processes are observed in the thermal decomposition namely dehydration and dehydroxylation and for the case of the sulphate interlayered hydrotalcite, a third process is the loss of sulphate. Both the dehydration and dehydroxylation take place in three steps each for each of the hydrotalcites.     

A renormalization group study of the Anderson Hamiltonian for arbitrary band-filling

The Anderson hamiltonian has been studied for arbitrarily filled bands using the real space renormalization group (RSRG) method. The ground state energy is determined in one dimension for the scale factors n_s = 3 and n_s = 5. Direct application of RSRG gives, for a certain n_s, the results for only n_s number of discrete cases of band-filling. We then devise an interpolation scheme which spans the entire region of the band and gives the ground state energy for any general filling. The results, as provided by our scheme, satisfy the desired particle-hole symmetry exactly and are always an upper bound to the exact one. The non-linear dependence of the band energy on its filling is represented correctly, even for small n_s. Finally, we discuss how the results improve for large n_s.     

A cluster study of aluminum adsorption on Ga-rich GaAs(100)(2 × 1) and β (4 × 2) surfaces

Ab initio self-consistent total energy calculations using second order Møller-Plesset perturbation theory and Hay-Wadt effective core potentials with associated basis sets (HWECP’s) for gallium and arsenic have been used to investigate the chemisorption properties of atomic aluminum on the Ga-rich GaAs(100)-(2 × 1) and β(4 × 2) surfaces. Finite sized hydrogen saturated clusters with the experimental zinc-blende lattice constant of 5.654 Å and the energy optimized Ga dimer bond length of 2.758 Å have been used to model the semiconductor surface. To investigate the effects of the core electrons of aluminum in the adsorption process, we have represented the Al adatom with both HWECP’s and an all electron 6-311++G** basis set. Detailed energetics of chemisorption on the (100) surface, including chemisorption energies, nearest surface neighbor bond lengths, and Mulliken population analysis, have been reported for all considered sites of chemisorption.     

A radiochemical method of separation of carrier-free vanadium from scandium and bulk amount of titanium

A method for the separation of carrier-free vanadium from scandium and bulk amount of titanium has been developed. Vanadium has been produced through the reaction^natTi(d,n)^48,49V with 8 MeV deuterons from the Variable Energy Cyclotron, Calcutta. The separation is performed with Dowex 1×8, 50–100 mesh fluoride from anion exchange resin which retains all the scandium and titanium with 4.5M hydrofluoric acid as eluent, while vanadium(V) is easily eluted. The chemical yield of vanadium was >85%.     

Bound states of the exponential cosine screened Coulomb potential

A generalized virial theorem and the Hellman-Feynman theorem have been used to calculate perturbatively the energy levels, expectation values of an arbitrary power of the position coordinates and normalization of the wave function. The method gives excellent results for low values of the screening parameter (λ ? λ_c/4).     

Evidence of equal Jahn-Teller coupling to Eg and T2g modes in KMgF3:Fe2+ from far infrared studies

From a study of the dependence of the far infrared (f.i.r.) spectra of KMgF₃:Fe²⁺ on impurity concentration and temperature, we identify them as due to magnetic dipole transition between the J = 1 and J = 2 states of Fe²⁺ and a resonant mode. The novelty of the work lies in demonstrating that in KMgF₃:Fe²⁺ the electronic orbital triplet is equally coupled to the E_g and T_2g modes of vibration and consequently vibronic interactions maintain the J-degeneracies.     

Acceptor excitation spectra in InSb

Optical excitation spectra of Zn, Cd and Ag acceptors in InSb have been measured. Excited state energies deduced from the spectra are in good agreement with effective mass theoretical predictions. Zeeman splitting of the spectra is consistent with the identification of the excitations, and strongly resembles the results obtained for acceptors in Ge.