An Algorithmic Approach to the Conley Index Theory

We introduce a class of representable sets which is closed under the operations of set theoretical union, intersection, difference, and topological interior and closure. We use this class to construct an algorithm which verifies if for a given dynamical system a given set is an isolating neighborhood. In the case of a positive answer the algorithm constructs an index pair.     

Additive property of secondary relaxation processes in di-n-octyl and di-isooctyl phthalates: signature of non-Johari-Goldstein relaxation

Broadband dielectric spectroscopy was used to study relaxation dynamics of supercooled di-n-octyl phthalate, di-isooctyl phthalate, and their mixtures. Additionally, low temperature measurements were performed to investigate the nature of the secondary relaxation processes in both glass formers. The authors found that the secondary relaxation observed in the mixture is the additive sum of the secondary relaxations of the two components. This experimental evidence indicates that these secondary relaxation processes are intramolecular in origin, and they are non-Johari-Goldstein secondary relaxations.     

Non-Debye response for the structural relaxation in glass-forming liquids: test of the Avramov model

The experimentally observed characteristic features of the alpha-relaxation process in glass-forming liquids are the non-Arrhenius behavior of the structural relaxation times and the non-Debye character of the macroscopic relaxation function. The Avramov model in which relaxation is considered as an energy activation process of surmounting random barriers in liquid energy landscape was successfully applied to describe the temperature and pressure dependences of the macroscopic relaxation times or viscosity. In this paper, we consider the dielectric spectrum associated with Avramov model. The asymmetrical broadening of the loss spectra was found to be related directly to dispersion of the energy barrier distribution. However, it turns out that temperature dependence of the spectrum broadening as predicted by the Avromov model is at odds to experimental observation in glass-forming liquids.     

On possible microscopic origins of the swelling of neutral lipid bilayers induced by simple salts

It was recently suggested that the swelling of neutral multilipid bilayers upon addition of a salt can be simply explained only by the electrolyte screening of the van der Waals attractions, while assuming that the hydration force and the repulsion due to thermal undulations of membranes are unaffected by the salt. While we agree that the screening of the van der Waals interactions plays a role, we suggest that the increase in the hydration force upon addition of a salt has also to be taken into account. In a statistical model, which accounts for the membrane undulations, parameters could be found to explain the multibilayer swelling even when the van der Waals attraction is considered unaffected by the electrolyte screening. These results point out that the decrease by a factor of three of the Hamaker constant upon addition of a salt, suggested recently to be responsible for the swelling of neutral multilipid bilayers, is perhaps too large, and a smaller decrease in Hamaker constant, coupled with the above mentioned effects might explain the swelling.     

Studies on hydrogen diffusivity in iron aluminides using the Devanathan–Stachurski method

An electrolytic method for cathodic hydrogen saturation developed by Devanathan and Stachurski was successfully used to study hydrogen diffusivity in iron aluminides. Both an appropriate electrolyte and a saturating current density are required for this method. A proper form of the saturation curve was only obtained with 35% NaCl electrolyte, which removed the oxide film blocking hydrogen penetration without further corrosive destruction of the iron aluminide. The optimum saturation current density for determining the most reliable diffusivity was 1.91 A/cm², yielding D_eff,H = 4.81 × 10⁻⁶ cm²/s for Fe–40 at.% Al.     

Complete classification of surfaces with a canonical principal direction in the Euclidean space \mathbb{E} 3

In the present paper we classify all surfaces in $ \mathbb{E} $ \mathbb{E} ³ with a canonical principal direction. Examples of this type of surfaces are constructed. We prove that the only minimal surface with a canonical principal direction in the Euclidean space $ \mathbb{E} $ \mathbb{E} ³ is the catenoid.     

Self-assembled hydrogen-bonded coordination networks in two copper(II) carboxylates with 4-pyridylmethanol

The crystal and molecular structure of [Cu(nif)₂(4-PM)₂]·CH₃OH (1) and [Cu(2-Clbz)₂(4-PM)₂(H₂O)] (2), (where nif = niflumate anion, 2-Clbz = 2-chlorobenzoate anion and 4-PM is the 4-pyridylmethanol), have been determinated by X-ray crystallography. The Cu²⁺ cation in (1), is coordinated by two pairs of oxygen atoms from asymmetric bidentate niflumate anions and by a pair of pyridine nitrogen atoms from monodentate 4-pyridylmethanol ligands in trans position forming an extremely elongated bipyramid. The Cu²⁺ cation in (2), is coordinated by a pair of oxygen atoms from monodentate 2-chlorobenzoate anions, further by a pair of pyridine nitrogen atoms from monodentate 4-pyridylmethanol ligands and finally by a water oxygen atom forming a tetragonal-pyramidal coordination polyhedron. The molecules of both complexes in crystal structures are linked by O-H…O hydrogen bonds, which created a three-dimensional hydrogen-bonding networks. The Π-Π stacking interactions are also observed in crystal structures of complex 2. The spectral properties (IR and electronic spectra) of both complexes were also investigated.     

Drag reduction via wall-normal oscillations in turbulent flat plate boundary layer flow at very high Reynolds number

The effects of wall-normal single point oscillations in turbulent boundary layers at very high Reynolds number are investigated by numerical simulation. The impact on the friction drag and on the turbulent structures is analyzed. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Characterization,optical and thermal properties of new azomethines based on heptadecafluoroundecyloxy benzaldehyde

New thermotropic liquid crystals containing a long alkoxysemiperfluorinated chain (-O-(CH₂)₃-(CF₂)₇-CF₃), one linking unit in mesogenic cores (HC=N-) and different functional end-groups such as 4-hexadecyl-, 4-n-hexadecyloxy- chain, or biphenyl-4-carbonitrile, 4-diazenyl-N,N-dimethylbenzene or pyren were synthesized via a one-step route. The methods of nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), ultraviolet–visual (UV-vis) and photoluminescence (PL) spectroscopy as well as differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) were used. The absorption (UV-vis) and PL features of all compounds are documented. The amine had an effect on the mesomorphic properties of the azomethines. An enantiotropic smectic phase was observed for all of the systems studied. As a result of DSC and POM investigations, it is shown that liquid crystalline properties of the azomethines exhibit a strong dependence of the end-groups. The mesomorphic behaviour of the compounds was investigated also by FTIR(T) and UV-vis(T) spectroscopy. Current–voltage measurements were performed on an ITO/compound/Alq₃/Al device.     

Synthesis and Biological Activity of New Resveratrol Derivative and Molecular Docking: Dynamics Studies on NFkB

Resveratrol (RVS) is a naturally occurring antioxidant, able to display an array of biological activities. In the present investigation, a new derivative of RVS, RVS(a), was synthesized, and its biological activity was determined on U937 cells. It was observed that RVS(a) showed pronounced activity on U937 cells than RVS. RVS(a) is able to induce apoptosis in tumor cell lines through subsequent DNA fragmentation. From the EMSA results, it was evident that RVS(a) was able to suppress the activity of NFkB by interfering its DNA binding ability. Furthermore, the molecular interaction analysis (docking and dynamics) stated that RVS(a) has strong association with the IkB-alpha site of NFkB compared with RVS; this binding nature of RVS(a) might be prevent the NFkB binding ability with DNA. The present findings represent the potential activity of propynyl RVS on U937 cells and signifying it as a one of putative chemotherapeutic drugs against cancer.