Polyhedral cobalt(II) and iron(II) siloxanes: synthesis and x-ray crystal structure of [(RSi(OH)O2)Co(OPMe3)]4 and [(RSiO3)2(RSi(OH)O2)4(mu3-OH)2Fe8(THF)4] (R = (2,6-iPr2C6H3)N(SiMe3))

The cobalt(II) and iron(II) siloxane compounds were prepared by the reaction of lipophilic N-bonded silanetriol 1 with metal silylamides M[N(SiMe3)2]2 (M = Co (2), Fe (3)) in a 1:1 and 3:4 molar ratio, respectively. A plot of 1/chi versus temperature in the range of 2-300 K indicates the paramagnetic behavior of 2 and 3. The composition and molecular structures of 2 and 3 were fully determined by IR, elemental analysis, and X-ray crystal structural analyses. Compound 2 possesses a pseudo-4-fold (S4) symmetry, whereas 3 reveals an inversion center. Compound 2 represents a tetracobalt(II) drum while 3 exhibits an octairon(II) cage containing siloxane ligands.     

Symmetric binuclear complexes with an ‘end-off’ compartmental Schiff base ligand

Four binuclear transition metal(II) complexes: [Co₂L(-Cl)Cl₂] · 2H₂O, [Ni₂L(-Cl)Cl₂(H₂O)₂] · 2H₂O, [Cu₂L(-Cl)Cl₂] · 2H₂O and [Zn₂L(-Cl)Cl₂] · 2H₂O, where LH is the binucleating ligand 2,6-diformyl-4-methylphenol bis(2-hydrazino benzothiazole), were prepared. Based on the i.r. spectra, elemental analysis, conductivity measurements and thermal analysis, we propose that these complexes contain an endogenous phenoxide bridge and an exogenous chloride bridge. Magnetic and spectral data supports the existence of a weak antiferromagnetic interaction between the metal ions, and octahedral for Ni^II and a square pyramidal environment for remaining complexes. The compounds show significant growth inhibitory activity against the fungi, Aspergillus niger and Candida albicans, as compared to antibacterial activity against Bacillus cirroflagellosus and Pseudomonas auregenosa.     

Photon interaction cross sections for some amino acids in the range 30–385 keV

Total attenuation cross sections for several amino acids have been measured for Ba¹³³ photons in a narrow beam good geometry setup, using a hyper pure germanium detector. These values are compared with the values calculated using the mixture rule based on the data of Hubbell for the individual elements and found to be in good agreement.     

Bianchi .Type-I Massive String Magnetized Barotropic Perfect Fluid Cosmological Model in General Relativity

Bianchi type-I massive string cosmological model with magnetic field of barotropic perfect fluid distribution through the techniques used by Latelier and Stachel is investigated. To obtain the deterministic model of the universe, it is assumed that the universe is filled with barotropic perfect fluid distribution. The magnetic field is due to electric current produced Mong the x-axis with infinite electrical conduictivity. The behaviour of the model in the presence and absence of magnetic field together with other physical aspects is further discussed.     

Reaction of nitrosyltribromide with rhodium(I) complexes and with rhodiumtrichloride trihydrate,in the presence of triphenylphosphine and triphenylarsine

Summary Nitrosyltribromide reacts with rhodium(I) complexes and with rhodiumtrichloride trihydrate in the presence of triphenylphosphine and triphenylarsine to give rhodium(III) nitrosyl complexes and rhodium(III) hyponitrite complexes which are characterized by i.r. spectra, magnetic measurements and by elemental analyses.     

SYNERGISTIC KILLING EFFECT IN PRE-UV-IRRADIATED MICROCOCCUS RADIOPHILUS

Abstract— Both the UV- and y-radiation survival curves of Micrococcus radiophilus are distinguished by large shoulders. However, a combination radiation treatment results in an enhanced killing effect. Pre-UV treatment is found to give a synergistic kill as compared to an additive kill when the sequence of radiation treatments is reversed.     

Symmetries, vibrational instabilities, and routes to stable structures of clusters of Al, Sn, and As

We investigate the stability of small clusters using density functional theory to compute the total energy, forces, and vibrational frequencies using linear response. We exhibit an efficient and computationally low-cost route to finding stable structures, by starting with high-symmetry structures and distorting them according to their unstable modes. We illustrate this by application to 4-, 6-, and 13-atom clusters of Al, Sn, and As. This technique also naturally elucidates the origins of stability of the lower symmetry structures, which is variously due to the linear or pseudo Jahn-Teller effect, combined with a lowering of various contributions to the total energy. We show that the situation is more complex than has generally been appreciated.