Thin film flow over a non-linear stretching sheet in presence of uniform transverse magnetic field

A thin viscous liquid film flow is developed over a stretching sheet under different non-linear stretching velocities in presence of uniform transverse magnetic field. Evolution equation for the film thickness is derived using long-wave approximation of thin liquid film and is solved numerically by using the Newton–Kantorovich method. It is observed that all types of stretching produces film thinning, but non-monotonic stretching produces faster thinning at small distance from the origin. Effect of the transverse magnetic field is to slow down the film thinning process. Observed flow behavior is explained physically.     

Ligand substitution in cubic clusters: surprising isolation of the cocrystallization products of Cu8(mu8-Se)[S2P(OEt)2]6 and Cu6[S2P(OEt)2]6

The cluster (Cu8(mu8-Se)[S2P(OEt)2]6)0.54(Cu6[S2P(OEt)2]6)0.46 (2) was prepared in 78% yield from the reaction of Cu8(Se)[Se2P(OPr)2]6 (1) and NH4S2P(OEt)2 in toluene. The central selenide ion in 2 was characterized by 77Se NMR at delta -976 ppm. The simulated solid-state 31P NMR spectrum shows two components with an intensity ratio close to 55:45. The peak centered at 100.7 ppm is assigned to the 31P nuclei in the hexanuclear copper cluster, and that at 101.1 ppm is due to the octanuclear copper cluster. The single-crystal X-ray diffraction analysis confirms the cocrystallization structures of Cu8(Se)[S2P(OEt)2]6 (54%) and Cu6[S2P(OEt)2]6 (46%) (2: trigonal, space group R3, a=21.0139(13) A, c=11.404(3) A, gamma=120 degrees, Z=3). While the octanuclear copper cluster possesses a 3-fold crystallographic axis which pass through the Cu2, Se, and Cu(2A) atoms, the six copper atoms having the S6 point group symmetry in Cu6[S2P(OEt)2]6 form a compressed octahedron. The Cu8(mu8-Se) cubic core in Cu8(mu8-Se)[S2P(OEt)2]6 is larger in size than the metal core in Cu8(mu8-Se)[Se2P(OPr)2]6 (1) although the bite distance of the Se-containing bridging ligand is larger than that of the S ligand. To understand the nature of the structure contraction of the metal core and metal-mu8-Se interaction, molecular orbital calculations have been carried out at the B3LYP level of density functional theory. MO calculations suggest that Cu-mu8-Se interactions are not very strong and a half bond can be formally assigned to each Cu-mu8-Se bond. Moderate Cu...Cu repulsion exists, and it is the bridging ligands that are responsible for the observed Cu...Cu contacts. Hence, the S-ligating copper clusters have greater Cu...Cu separations because each Cu carries more positive charge in the presence of the more electronegative S-containing ligands.     

Biochemically functionalized silica nanoparticles

In this report, we demonstrate the biochemical modification of silica based nanoparticles. Both pure and dye-doped silica nanoparticles were prepared, and their surfaces were modified with enzymes and biocompatible chemical reagents that allow them to function as biosensors and biomarkers. The nanoparticles produced in this work are uniform in size with a 1.6% relative standard deviation. They have a pure silica surface and can thus be modified easily with many biomolecules for added biochemical functionality. Specifically, we have modified the nanoparticle surfaces with enzyme molecules (glutamate dehydrogenase (GDH) and lactate dehydrogenase (LDH)) and a biocompatible reagent for cell membrane staining. Experimental results show that the silica nanoparticles are a good biocompatible solid support for enzyme immobilization. The immobilized enzyme molecules on the nanoparticle surface have shown excellent enzymatic activity in their respective enzymatic reactions. The nanoparticle surface biochemical functionalization demonstrates the feasibility of using nanoparticles for biosensing and biomarking applications.     

Syntheses, solid-state structures, and solution studies by VT 31P NMR of [Zn[Se2P(OEt)2]2] infinity and [Zn2[Se2P(OiPr)2]4

Complexes [Zn[Se(2)P(OEt)(2)](2)]( infinity ) (1) and [Zn(2)[Se(2)P(O(i)Pr)(2)](4)] (2) are prepared from the reaction of Zn(ClO(4))(2).6H(2)O and (NH(4))[Se(2)P(OR)(2)] (R = Et and (i)Pr) in a molar ratio of 1:2 in deoxygenated water at room temperature. Positive FAB mass spectra show m/z peaks at 968.8 (Zn(2)L(3)(+)) and 344.8 (ZnL(+)) for 1 and m/z at 1052.8 (Zn(2)L(3)(+)) for 2. (1)H NMR spectra exhibit chemical shifts at delta 1.43 and 4.23 ppm for 1 and 1.41 and 4.87 ppm for 2 due to Et and (i)Pr group of dsep ligands. While the solid-state structure of compound 1 is a one-dimensional polymer via symmetrically bridging dsep ligands, complex 2 in the crystalline state exists as a dimer. In both 1 and 2, zinc atoms are connected by two bridging dsep ligands with an additional chelating ligand at each zinc atom. The dsep ligands exhibit bimetallic biconnective (micro(2), eta(2)) and monometallic biconnective (eta(2)) coordination patterns. Thus, each zinc atom is coordinated by four selenium atoms from two bridging and one chelating dsep ligands and the geometry around zinc is distorted tetrahedral. The Zn-Se distances range between 2.422 and 2.524 A. From variable-temperature (31)P NMR studies it has been found that monomer and dimer of the complex are in equilibrium in solution via exchange of bridging and chelating ligands. However, at temperature above 40 degrees C the complex exists as a monomer and shows a very sharp peak while with lowering of the temperature the percentage of dimer increases gradually at the expense of monomer. Below -90 degrees C the complex exists as a dimer and two peaks are observed with equal intensities which are due to bridging and chelating ligands. (77)Se NMR spectra of both complexes at -30 degrees C exhibit three doublets due to the presence of monomer and dimer in solution.     

TAT conjugated, FITC doped silica nanoparticles for bioimaging applications

Water-in-oil (w/o) microemulsion synthesis of 70 nm size monodisperse TAT (a cell penetrating peptide, CPP) conjugated, FITC (fluorescein isothiocyanate) doped silica nanoparticles (TAT-FSNPs) is reported; human lung adenocarcinoma (A549) cells (in vitro) and rat brain tissue (in vivo) were successfully labeled using TAT-FSNPs.     

Hyperon production in pp collisions

We report on a study of the proton induced hyperon production reactions. We discuss the theoretical efforts made towards understanding the existing data and the uncertainties involved in the calculations. Our recent calculations of the missing mass spectra for the pp → K ⁺ Λp reaction which involve a proper coupled channel treatment of the final state Λp interaction are presented. Significant differences in the results using different models of the hyperon-nucleon interaction are found.     

Structure information from fusion barriers

It is shown that the analysis of fusion barrier distributions is not always an unambiguous test or a ‘fingerprint’ of the structure information of the colliding nuclei. Examples are presented with same fusion barrier distributions for nuclei having different structures. The fusion excitation functions for ¹⁶O+²⁰⁸Pb, using the coupled reaction channel (CRC) method and correct structure information, have been analysed. The barrier distributions derived from these excitation functions including many of the significant channels are featureless, although these channels have considerable effects on the fusion excitation function. However, a simultaneous analysis of the fusion, elastic and quasi-elastic channels would fix the structure and the reaction unambiguously.