Exchange bias at low fields exhibited by the interface between epitaxial layers of ferromagnetic and charge‐ordered rare‐earth manganites

Epitaxial thin films of ferromagnetic La_0.7Sr_0.3MnO₃ (LSMO) and charge‐ordered, antiferromagnetic Y_0.5Ca_0.5MnO₃ (YCMO) were deposited on SrTiO₃ (100) substrates by pulsed laser deposition (PLD). The heterostructure undergoes tetragonal distortion due to strong biaxial tensile strain imposed by the substrate. The LSMO–YCMO bilayers exhibit significant exchange bias (EB) across the interface even in a very small remnant magnetic field (～5 Oe) present in the superconductor magnet. The unidirectional exchange anisotropy at the interface can be switched by reversing the polarity of the remnant magnetic field.

     

Trapping Pd(0) in nanoparticle-assembled microcapsules: an efficient and reusable catalyst

Pd nanoparticles dually encased by soft (polyamine) and hard (silica) materials in a microcapsule structure, obtained via a nanoparticle self-assembly method, exhibit excellent catalytic activity, with efficient catalyst recovery and reusability.     

New proaporphines from the bark of Phoebe scortechinii

The phytochemical study of the bark of Malaysian Phoebe scortechinii (Lauraceae) has resulted in the isolation and identification of two new proaporphine alkaloids; (+)-scortechiniine A (1) and (+)-scortechiniine B (2) together with two known proaporphines; (-)-hexahydromecambrine A (3), (-)-norhexahydromecambrine A (4), and one aporphine; norboldine (5). Structural elucidations of these alkaloids were performed using spectroscopic methods especially 1D and 2D (1)H and (13)C NMR.     

Quantized hydration energies of ions and structure of hydration shell from the experimental gas-phase data

With previous data on alkali metal and halide ions included [Rais, J.; Okada, T. Anal. Sci. 2006, 22, 533], we analyzed rather broad data on ionic hydration from the point of view of gaseous cluster energetics. We have now added alkaline earth cations, Zn(2+), H(+), OH(-), Cu(+), Ag(+), Bi(+), Pb(+), and alkylammonium cations. The present analysis revealed the octa-coordinated nature of alkaline earth cations, which is not fully pronounced for Be(2+) and Zn(2+), existence of Eigen protonium complex, which is trigonally hydrated, and particular property of the first OH-, H(2)O cluster. Whereas these findings are generally in accordance with theoretical model calculation studies, we have foreseen in addition tetrahedral hydration for halide anions and Rb(+) and Cs(+), as well as for alkylammonium ions. The obtained picture of the quantized solvation of ions is mirrored in the ionization potentials of outer electrons of pertinent atoms. This is a second independent phenomenon, and together, they invoked a common pattern formation ("Aufbau") obeying tetra- and octa-coordinated principles.     

Phytochemical screening and biological activities of Eminium spiculatum (Blume) Kuntze (family Araceae)

Eminium spiculatum (Blume) Kuntze (Araceae) is an indigenous plant in Jordan used as an anticancer agent. The objective of this study was to determine the chemical composition of E. spiculatum and its antimicrobial, antiplatelet and antiproliferative activities. After isolation, antimicrobial activity was tested using well-in-agar method and in vitro platelet aggregation by aggrometric method. Antiproliferative activity was evaluated by Sulphorhodamine B assay. Luteolin, luteolin-7-O-glucoside, isoorientin, vitexin, chrysoeriol-7-O-glucoside and β-sitosterol were isolated and their structures determined. Luteolin exhibited moderate antibacterial activity against Escherichia coli and resistant strains of Staphylococcus aureus in 1 μg mL(-1) concentration. Luteolin, luteolin-7-O-glucoside and vitexin inhibited ADP and collagen-induced platelet aggregation in a concentration-dependent manner. For the determination of the antiproliferative activity, MCF-7 and T47D were used. Luteolin demonstrated the highest inhibitory activity with IC(50) values of 14.92 and 18.49 μmol L(-1) for MCF-7 and T47D, respectively. This research provided evidence about the chemical composition and biological activity of E. spiculatum.     

Controlled orientation in a bio-inspired assembly of Ag/AgCl/ZnO nanostructures enables enhancement in visible-light-induced photocatalytic performance

In a bio-inspired approach, polyamine-mediated mineralization of ZnO was explored to develop an environmentally benign methodology for synthesizing Ag/AgCl/ZnO nanostructures. The assembling properties displayed by the polyamines to create composite structures was utilized to have the nanocomponents effectively interact with each other in a way that is desirable for the application envisaged. The polyamines, which act as a mineralizing agent for ZnO nanoparticles, also facilitate the formation of Ag/AgCl within ZnO under ambient conditions. Thus synthesized Ag/AgCl/ZnO nanostructures represent a multi-heterojunction system in which the nanocomponents lead in a synergistic way to enhancement in the photocatalytic activity under visible-light irradiation.     

Control of surface tension at liquid-liquid interfaces using nanoparticles and nanoparticle-protein complexes

Subtle changes in the monolayer structure of nanoparticles (NPs) influence the interfacial behavior of both NPs and NP-protein conjugates. In this study, we use a series of monolayer-protected gold NPs to explore the role of particle hydrophobicity on their dynamic behavior at the toluene-water interface. Using dynamic surface tension measurements, we observed a linear decrease in the meso-equilibrium surface tension (γ) and faster dynamics as the hydrophobicity of the ligands increases. Further modulation of γ is observed for the corresponding NP-protein complexes at the charge-neutralization point.     

Theoretical studies of electron transfer through dendrimeric architecture

We have analyzed the steady-state electron transfer rate through a bridge of dendrimeric architecture. The difference between the linear chain and the dendrimeric architecture has also been demonstrated with steady-state rate as a main observable in the coherent and incoherent regimes of interactions. It is shown that generally the rate of electron transfer in dendrimeric architecture is faster than the rate associated with their linear chain counterpart with similar kind of bonding connectivities. The rate depends upon the size of the molecule, core branching, and the nature of the coupling among the different nodes on the dendrimer molecule. Depending upon the nature of the donor and acceptor, phenomenological dephasing coefficient due to environment and the geometry of the dendrimeric architecture, the modification of electron transfer rate has been studied. In the regime of fully coherent interactions where all quantum effects are considered the rate shows a multiple inversion due to the dendrimer architecture which is neither available in the regime of incoherent interaction nor in the linear chain case in similar condition. We have discussed about the applicability of our model in metal-molecule-metal junction, photoinduced electron transfer process, and molecular conductor.     

Assessment of radioactivity associated with a low ore grade open cast mine at Banduhurang, Jharkhand, India and estimation of occupational exposure to the miners

The study summarizes radiological characteristics of Banduhurang open cast mine which includes qualitative and quantitative behavior of ²²²Rn concentration, external gamma radiation level over the mine pit as well as in its adjoining environment, long-lived alpha (LLα) activity concentration associated with the respirable size of ore dust and assessment of dose to the mine workers in 2006–2008. The investigations reveal that geometric means (χ_g) of measured radon concentration were 36.39, 38.69, 26.64 and 24 Bq m^?3 with respective geometric standard deviations (σ_g) were 1.52, 1.55, 1.36 and 1.68 Bq m^?3 and χ_g of gamma absorbed dose rates were 0.54, 0.64, 0. 45 and 0.15 μGy h^?1 with respective σ_g were 1.63, 1.53, 1.52 and 1.72 μGy h^?1 over the mine pit, ore yard, waste yard and in the surrounding environment within a 10 km radius to the mine, respectively. The χ_g of LLα activity was observed to be 16 mBq m^?3 with σ_g of 1.9 mBq m^?3. The annual mean effective dose equivalent received by the member radiation workers of Banduhurang mine was estimated to 1.41 mSv y^?1, which is about 7% of the prescribed dose limits of 20 mSv y^?1.