Site-selective guest inclusion in molecular networks of butadiyne-bridged pyridino and benzeno square macrocycles on a surface

We present here the formation of a modular 2D molecular network composed of two different types of square-shaped butadiyne-bridged macrocycles, having intrinsic molecular voids, aligned alternately at the solid-liquid interface. Site-selective inclusion of a guest cation took place at every other molecular void in the molecular network with two different recognition sites.     

The influence of X-ray resonant Raman scattering effects on the detection of copper(II) tetrasulphonated phthalocyanine (CuTSPc) thin-films deposited on gold electrodes

The influence of X-ray resonant Raman scattering on the detection capabilities of copper(II) tetrasulphonated phthalocyanine (CuTSPc) thin-films on gold electrodes has been investigated by means of synchrotron radiation X-ray fluorescence. In particular the paper focuses on the influence of the excitation energy in the relative narrow energy region of 9.2 to 11.7 keV on the detection limits and the peak-to-background ratios of copper.     

Fast-diffusion limit with large noise for systems of stochastic reaction-diffusion equations

We consider a class of a stochastic reaction-diffusion equations with additive noise. In the limit of fast diffusion, one can approximate solutions of the stochastic reaction–diffusion equations by the solution of a suitable system of ordinary differential equation only describing the reactions, but due to nonlinear interaction of large diffusion and fluctuations in the limit new effective reaction terms appear. We focus on systems with polynomial nonlinearities and illustrate the result by applying it to a predator-prey system and a cubic auto-catalytic reaction between two chemicals.     

Synthesis and antitumor activity evaluation of some N-heterocycles derived from pyrazolyl-substituted 2(3H)-furanone

Pyrazolyl-substituted 2(3H)-furanone was allowed to react with different nitrogen nucleophiles such as hydrazine hydrate, ethylenediamine, ethanolamine, and anthranilic acid to give pyrrolone and benzoxazinone derivatives. The acid hydrazide 3 was reacted with some carbonyl compounds such as 4-chlorobenzaldehyde, chloroacetyl chloride, and acetic anhydride to give thiazolidinone, oxadiazole, and pyridazinone derivatives. Selected examples of the synthesized compounds were evaluated as anticancer agents against three types of carcinoma cell lines (HePG 2, HCT116, and PC3), using Doxorubicin as a reference drug. The result revealed that some of the new compounds showed high activities. Compound 6a was more potent than the standard drug. A docking study using MOE 2008.10 program was performed.     

Ultrasound mediated green synthesis of rhodanine derivatives: Synthesis,chemical behavior,and antibacterial activity

A variety of rhodanine derivatives were synthesized via a three-component reaction of carbon disulfide, amines, and dialkyl acetylenedicarboxylate in polyethylene glycol under conventional stirring or ultrasound irradiation. The sonochemical-assisted procedure provides an improved and accelerated conversion when compared to the conventional reaction, with increased rate of reaction and quality of product obtained. The product formed, 2a, could be readily converted to bis-rhodanine under microwave conditions. Moreover, the pyranothiazoles 9a,b were prepared from the corresponding rhodanines 2a,b and malononitrile. Fifteen compounds were screened for their antibacterial activities against nine human, animal and plant pathogenic Gram-positive and Gram-negative bacteria using the agar well diffusion method. Out of these derivatives, compounds 2g and 2h were the most effective against all tested bacteria.     

Coexistence of homochiral and heterochiral adenine domains at the liquid/solid interface

In this work, the self-assembly of the DNA base molecule adenine (A) is imaged with high-resolution scanning tunneling microscopy (STM) at the liquid (1-octanol)/solid (HOPG) interface at room temperature. Rather surprisingly, the STM results reveal, for the first time, the spontaneous formation of two coexisting distinct (homo- and heterochiral) domains of adenine, which are formed at the liquid/solid interface without changing any experimental conditions. Ab initio density functional theory (DFT) calculations support our STM findings and suggest the existence of various A networks of nearly similar stability that all are constructed from the most stable A dimer.     

Thermomechanical coupling in shape memory alloys under cyclic loadings: Experimental analysis and constitutive modeling

In this paper, we examine the influence of thermomechanical coupling on the behavior of superelastic shape memory alloys subjected to cyclic loading at different loading rates. Special focus is given to the determination of the area of the stress-strain hysteresis loop once the material has achieved a stabilized state. It is found that this area does not evolve monotonically with the loading rate for either transient or asymptotic states. In order to reproduce this observation analytically, a new model is developed based on the ZM model for shape memory alloys which was modified to account for thermomechanical coupling. The model is shown to predict the non-monotonic variation in hysteresis area to good accord. Experimentally observed variations in the temperature of SMA test samples are also correctly reproduced for lower strain rates.     

A constitutive model for shape memory alloys accounting for thermomechanical coupling

This paper presents a generalized Zaki-Moumni (ZM) model for shape memory alloys (SMAs) [cf. Zaki, W., Moumni, Z., 2007a. A three-dimensional model of the thermomechanical behavior of shape memory alloys. J. Mech. Phys. Solids 55, 2455-2490 accounting for thermomechanical coupling. To this end, the expression of the Helmholtz free energy is modified in order to derive the heat equation in accordance with the principles of thermodynamics. An algorithm is proposed to implement the coupled ZM model into a finite element code, which is then used to solve a thermomechanical boundary value problem involving a superelastic SMA structure. The model is validated against experimental data available in the literature. Strain rate dependence of the mechanical pseudoelastic response is taken into account with good qualitative as well as quantitative accuracy in the case of moderate strain rates and for mechanical results in the case of high strain rates. However, only qualitative agreement is achieved for thermal results at high strain rates. It is shown that this discrepancy is mainly due to localization effects which are note taken into account in our model. Analyzing the influence of the heat sources on the material response shows that the mechanical hysteresis is mainly due to intrinsic dissipation, whereas the thermal response is governed by latent heat. In addition, the variation of the area of the hysteresis loop with respect to the strain rate is discussed. It is found that this variation is not monotonic and reaches a maximum value for a certain value of strain rate.     

Urban air pollutants and their micro effects on medieval stained glass windows

Levels of urban gaseous and particulate pollutants were investigated in the Cathedral of Cologne, Germany in the framework of the EU-project “VIDRIO”. The purpose of this study was to evaluate the influence of a protective double glazing system on the preservation of ancient stained glass windows by sampling at protected and unprotected windows (indoors, in the interspace and outdoor of the Cathedral). The interspace between the ancient stained glass window and the protective glazing is flushed in the Cathedral by indoor air, hence isolating the historic glass from the outdoor air and exposing it to indoor air on both sides of the glass panels. Concentrations of aggressive gaseous pollutants such as NO₂, SO₂, O₃ and CO₂ as well as elemental concentrations of bulk particles and relative abundances of single particles were surveyed at all sampling locations. Elemental concentrations in bulk particulate matter were found to be significantly lower inside the Cathedral in comparison to the outdoor air. This result is advantageous for the stained glass windows. Single particle analysis of the samples from Cologne showed also soil dust and organic particles as well as sulphates and nitrates, from which the latter two compounds are dangerous for the stained glass windows. On the base of the obtained results, it can be concluded that the protective glazing system in the Cathedral of Cologne can be considered as predominantly advantageous from both the gases' point of view (except for NO₂-candles burning) and from the particles' point of view.     

Building layer-by-layer 3D supramolecular nanostructures at the terephthalic acid/stearic acid interface

By using the layer-by-layer deposition method, we build three dimensional (3D) supramolecular nanostructures by stacking small molecular species on top of the first buffer layer, which can be utilized to fabricate novel 3D supramolecular functional nanostructures.