The neutron-proton pairing and the moments of inertia of the rare earth even-even nuclei

In this study, the possible effect of the neutron-proton pairing interaction in the heavy nuclei has been investigated in the framework of the BCS model by making a simple approximation. This effect has been searched realistically by calculating the moments of inertia of deformed even-even nuclei. Calculations show that the moments of inertia of rare earth nuclei changed dramatically and approached the experimental values.     

Synthesis,characterization and catalytic properties of cationic N-heterocyclic carbene silver complexes

Three new dibenzimidazolium salts bridged by 2-methylenepropane-1,3-diyl group were synthesized. Their dinuclear N-heterocyclic carbene Ag(I) complexes were prepared by the reactions of these salts with Ag₂O. The structures of the synthesized compounds were defined by nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FT-IR), elemental analysis, and LC-MSMS (for complexes) techniques. Stability of the silver complexes was confirmed by ¹H NMR spectroscopy. Catalytic activities of Ag(I) compounds were tested for three-component coupling reaction of some aldehydes, amines, and phenylacetylene.     

Indium phosphide nanofibers prepared by electrospinning method: Synthesis and characterization

Nine sets of (3 × 3) InP nanofiber samples have been successfully prepared at three different voltages (20, 25, 30 kV) and at three separate heights (5, 7, 10 cm) by electrospinning with a constant precursor flow rate of 0.3 mLh⁻¹. The crystalline structure, thermal, morphologies and nanostructure, electrical, and optical properties of the samples are characterized by X‐ray powder diffractometer (XRD) and thermal gravity‐differential scanning calorimeter (TG‐DSC), scanning electron microscopy (SEM), by Four‐Point Probe Technique (FPPT,) and ultraviolet/visible spectrometry (UV/VIS), respectively. From these measurements, we have found the formation of stoichiometric nanostructured InP with zinc‐blende structure and having lattice parameter of a = 5.874 Å, weight loss of 64.59% and crystallization temperature of 500°C, average fiber diameter of 65.82 nm, the activation energies, E_a, of the samples, and band gap energy, E_g, of the nanofibers developed at constant applied voltage 30 kV. The band gap energies determined at different distances 5, 7, and 10 cm are found to be as 1.29, 1.37, and 1.30 eV, respectively.     

Self-assembly of doublets from flattened polymer colloids

Bottom-up fabrication methods are used to assemble strong yet flexible colloidal doublets. Part of a spherical particle is flattened, increasing the effective interaction area with another particle having a flat region. In the presence of a moderate ionic strength, the flat region on one particle will preferentially "bond" to a flat region on another particle in a deep (≥10 kT) secondary energy minimum. No external field is applied during the assembly process. Under the right conditions, the flat-flat bonding strength is ≥10× that of a sphere-sphere interaction. Not only can flat-flat bonds be quite strong, but they are expected to remain freely rotatable and flexible, with negligible energy barriers for rotation because particles reside in a deep secondary energy minimum with a ~20-30 nm layer of fluid between the ~1 μm radius particles. We present a controlled technique to flatten the particles at room temperature, the modeling of the interparticle forces for flattened spheres, and the experimental data for the self-assembly of flat-flat doublets.     

A notion of robustness and stability of manifolds

Starting from the notion of thickness of Parks we define a notion of robustness for arbitrary subsets of Rk and we investigate its relationship with the notion of positive reach of Federer. We prove that if a set M is robust, then its boundary ∂M is of positive reach and conversely (under very mild restrictions) if ∂M is of positive reach, then M is robust. We then prove that a closed non-empty robust set in Rk (different from Rk) is a codimension zero submanifold of class C¹ with boundary. As a partial converse we show that any compact codimension zero submanifold with boundary of class C² is robust. Using the notion of robustness we prove a kind of stability theorem for codimension zero compact submanifolds with boundary: two such submanifolds, whose boundaries are close enough (in the sense of Hausdorff distance), are diffeomorphic.     

Iridoid glycosides from Globularia davisiana

From the ethanolic extract of the aerial parts of Globularia davisiana, a new iridoid glycoside, davisioside (1), was isolated. Davisioside (1) comprises a rare iridoid aglycone structure with a saturated double bond between C-3 and C-4. Nine known iridoid glycosides, asperuloside (2), alpinoside (3), geniposide (4), globularin (5), globularicisin (6), 10-O-benzoylcatalpol (7), lytanthosalin (8), melampyroside (9), agnuside (10), and three known phenylethanoid glycosides, verbascoside, isoacteoside and leucosceptoside A were also isolated and characterized. The structures of the isolates were established by spectroscopic methods (one-dimensional (1D)- and two-dimensional (2D)-NMR, MS).     

Thermal Investigations of nBABAs

The phase transitions occurring in nBABAs (n = 1 to 5), especially those involving the nematic phase, have been studied by DSC. Schemes of transition are presented and the chain length (n) dependences of the the transition temperatures and entropies are discussed.     

Solvent-free microwave extraction and hydrodistillation of essential oils from endemic Origanum husnucanbaseri H. Duman, Aytac & A. Duran: comparison of antibacterial activity and contents

The essential oils (EOs) obtained by solvent-free microwave extraction (SFME) and hydrodistillation (HD) from endemic Origanum husnucanbaseri H. Duman, Aytac & A. Duran were investigated using the gas chromatography-mass spectrometry system. The main constituents of both oils obtained from SFME and HD from O. husnucanbaseri are borneol (15.2-12.8%), α-terpineol (12.3-10.8%) and trans-sabinene hydrate (11.8-9.92%). The EO obtained from SFME contained substantially higher amounts of oxygenated compounds and lower amounts of monoterpenes than that from HD. The antibacterial activities of the EOs from SFME and HD were evaluated by the disc diffusion method against six bacterial strains. The EO extracted by SFME was more effective than the EO extracted by HD against the tested bacteria, except for Klebsiella pneumoniae American type culture collection (ATCC) 13883. Streptococcus pyogenes ATCC 19615 and Staphylococcus aureus ATCC 25923 in particular were more sensitive against the EO extracted by SFME.     

Surfactant-induced healing of tough hydrogels formed via hydrophobic interactions

Different reversible molecular interactions have been used in the past few years to generate self-healing in synthetic hydrogels. However, self-healing hydrogels synthesized so far suffer from low mechanical strength which may limit their use in any stress-bearing applications. Here, we present a simple technique to heal mechanically strong polyacrylamide hydrogels formed via hydrophobic interactions between stearyl groups. A complete healing in the hydrogels was achieved by the treatment of the damaged areas with an aqueous solution of wormlike sodium dodecyl sulfate micelles. The micelles in the healing agent solubilize the hydrophobes in the cut surfaces, so that they easily find their partners in the other cut surface due to the hydrophobic interactions. Surfactant-induced healing produces high toughness (～1 MPa) gels withstanding 150 kPa of stress at a deformation ratio of 1,100 %. The healing technique developed here is generally applicable to the physical gels formed by hydrophobic associations.     

Quantum mechanical calculations of tryptophan and comparison with conformations in native proteins

We report a detailed analysis of the potential energy surface of N-acetyl-l-tryptophan-N-methylamide, (NATMA) both in the gas phase and in solution. The minima are identified using the density-functional-theory (DFT) with the 6-31g(d) basis set. The full potential energy surface in terms of torsional angles is spanned starting from various initial configurations. We were able to locate 77 distinct L-minima. The calculated energy maps correspond to the intrinsic conformational propensities of the individual NATMA molecule. We show that these conformations are essentially similar to the conformations of tryptophan in native proteins. For this reason, we compare the results of DFT calculations in the gas and solution phases with native state conformations of tryptophan obtained from a protein library. In native proteins, tryptophan conformations have strong preferences for the beta sheet, right-handed helix, tight turn, and bridge structures. The conformations calculated by DFT, the solution-phase results in particular, for the single tryptophan residue are in agreement with native state values obtained from the Protein Data Bank.