Kinetic preference for interaction of cisplatin with the G-C-rich wobble basepair region in both tRNAAla and MhAla

The anticancer active complex cisplatin interacts preferentially with the common, G-C rich, wobble base pair region of both tRNA(Ala) and Mh(Ala) in a reaction that at pH 6.3 is rate limited by the acid hydrolysis of the metal complex.     

Electrical bistability in electrostatic assemblies of CdSe nanoparticles

We report electrical bistability in electrostatic assembly of CdSe nanoparticles. We obtained thin films of the nanoparticles via layer-by-layer electrostatic assembly technique, which provided a nanoscale control to tune the thickness. Devices based on such thin films exhibit electrical bistability along with memory phenomenon. The bistability is due to charge confinement in the nanoparticles. Conduction mechanism changes from an injection-dominated to a bulk one during switching from a low- to a high-conducting state. Additionally, results from impedance spectroscopy show that the dielectric constant of the material increases during the transition. Both random-access and read-only memory applications are observed in these systems.     

Resonance Raman spectroscopic investigation of structural changes of CO‐heme in soluble guanylate cyclase generated by effectors and substrate

The influence of the effectors YC‐1 and BAY on the CO‐heme structure of bovine lung soluble guanylate cyclase (sGC) was investigated with resonance Raman spectroscopy. The effectors produced a five‐coordinate (5c) CO‐heme in addition to the His‐bound six‐coordinate (6c) CO‐heme, and both their Soret maxima were determined by simulation. On the basis of the absorption intensity, the amount of the 5c species was not dominant, in contrast to the high activity. The heme structural features common to the 5c and 6c CO‐hemes generated by effectors are that the vinyl and propionate side chains are more coplanar to the pyrrole rings. The out‐of‐plane Raman bands were observed only for the 5c species, for which the saddling and propeller distortions of heme were deduced to be large. The Fe CO stretching bands of the 5c species at 522 cm⁻¹ and of the 6c species at 488 cm⁻¹ were most enhanced upon excitation at 407 and 422 nm, respectively, which is consistent with the simulated spectra. Unexpectedly, the ¹³C¹⁸O isotope sensitivity appeared in low wavenumber porphyrin modes. From these observations, we propose that the high catalytic activity of sGC‐CO in the presence of effectors is a result of the concerted effects of protein conformational changes triggered by certain local interactions between the heme side chains and effectors/substrate in the heme pocket, which partly induce the cleavage of the Fe Hisβ 105 bond. Copyright © 2010 John Wiley & Sons, Ltd.     

Magnetic aftereffect in Co-P trilayer films

This paper reports on the results of experimental investigations of the magnetic properties of a trilayer system that consists of high-coercive polycrystalline and low-coercive amorphous magnetic Co-P layers and a nonmagnetic amorphous Ni-P interlayer. It has been established that the coercive force and the bias field of the hysteresis loop of the low-coercive layer undergo anomalous changes in the range of small thicknesses of the hard magnetic layer. In the same range of thicknesses, a magnetic aftereffect is found to manifest itself, which is unusual for this type of magnetic structures. The observed features are associated primarily with the kinetics of formation of a crystal structure of the high-coercive layer.     

Complexes of metal ions with phosphorus or arsenic containing ligands. III. Complexes of Mercury (II) halides with 1,2-ethylenebisdiphenylphosphine and 1,4-butylenebisdiphenylphosphine

Mercury(II) halides react with 1,2-ethylenebisdiphenylphosphine (DPE) and 1,4-butylenebisdiphenylphosphine (DPB) to give two types of complexes having the general formulae, [(diphos)HgX₂] and [(diphos)(HgX₂)₂]. The former seems to possess chain structure, while the latter has probably a bridged structure. In both the cases mercury(II) acquires sp³ tetrahedral configuration.     

Rheological properties of the methylcellulose gels in N,N-dimethyl formamide: Validity of scaling laws

The rheological behavior of the methylcellulose (MC) gels in N,N-dimethylformamide (DMF) was studied under dynamic compression with respect to the presence of various concentrations c (1, 2, 2.5 and 3 wt %) and different molecular weight M (4.1 × 10⁴, 6.3 × 10⁴ and 8.8 × 10⁴) of MC in the gels. The temperature scan for the 1 wt % MC gel (M = 8.8 × 10⁴) in DMF shows double crossover of the storage modulus E′ with the loss modulus E″. This indicates that two types of transitions namely the phase separated MC-DMF mixture to MC-DMF gel and MC-DMF gel to solution are present. The plot of storage modulus E′ with temperature shows almost plateau like behavior. This plateau like behavior may reflect the equilibrium between the core formation and core disintegration. In the frequency scan of MC gels, the modulus increases with an increase in the concentration. This can be explained by the increase in core structure of the gel. The core formation in the MC-DMF gel is a concentration dependent parameter. While comparing the different molecular weight grades of MC, it is observed that the storage modulus increases with an increase in the molecular weight of the MC. The validity of three scaling laws is also investigated with respect to various concentration of MC-88.000. The modified scaling law in terms of relative frequency and modulus $\left( {\eta '_r = \frac{{\left| {\frac{{E''}} {\omega } - \left( {\frac{{E''}} {\omega }} \right)_c } \right|}} {{\left( {\frac{{E''}} {\omega }} \right)_c }}andE'_r = \frac{{\left| {E' - E'_c } \right|}} {{E'_c }}} \right) $ is seemed to be applicable.     

Single-slit diffraction of an optical beam with phase singularity

Single-slit diffraction of an optical beam carrying phase singularity is presented. Due to azimuthal phase dependence, the diffraction pattern of the singular beam differs from that of a plane wave. The fringes in the diffraction pattern of singular beam undergo continuous bending, while passing through the centre of the pattern and exhibit left to right or right to left shift, depending on the sign of the topological charge of singular beam. It is shown that diffraction of a singular beam through a slit can be used to determine magnitude and sign of its topological charge.     

Theoretical investigations on structural, elastic and electronic properties of thallium halides

Theoretical investigations on structural, elastic and electronic properties, viz. ground state lattice parameter, elastic moduli and density of states, of thallium halides (viz. TlCl and TlBr) have been made using the full potential linearized augmented plane wave method within the generalized gradient approximation (GGA). The ground state lattice parameter and bulk modulus and its pressure derivative have been obtained using optimization method. Young's modulus, shear modulus, Poisson ratio, sound velocities for longitudinal and shear waves, Debye average velocity, Debye temperature and Grüneisen parameter have also been calculated for these compounds. Calculated structural, elastic and other parameters are in good agreement with the available data.     

A columnar mesophase from a disc-shaped molecule derived from triphenylamine: synthesis, mesomorphic behaviour and optical properties

The design and synthesis of a disc-like liquid crystalline compound using triphenylamine as a core has been achieved. The mesogenic properties were characterized by polarizing microscopy and differential scanning calorimetry and XRD studies. The compound existed as a hexagonal columnar mesophase. The fluorescence properties revealed the presence of intermolecular excimer formation.