Fundamental solution of generalized thermo-viscoelasticity using the finite element method

The present paper is aimed at an investigation of the temperature, displacement, and stress in a viscoelastic half space of Kelven–Voigt type. The formulation is applied according to three theories of generalized thermoelasticity: Lord–Shulman with one relaxation time, Green–Lindsay with two relaxation times, as well as the coupled theory. The nondimensional governing equations are solved by the finite element method. Numerical results for the temperature distribution, displacement, and thermal stress are represented graphically. Comparisons are made with the results predicted by the CD, L-S, and G-L theories in the presence and absence of the viscoelastic relaxation time.     

Metal complexes of novel Schiff base derived from the condensation of 2‐quinoline carboxaldehyde and ambroxol drug with some transition metal ions

A new Schiff base was prepared as the condensation product of the reaction of 2‐quinoline carboxaldehyde and ambroxol drug. The Schiff base ligand thus obtained (HL; trans‐4‐[(2‐(2‐quinolinoimino)‐3,5‐dibromobenzyl)amino]cyclohexanol) was further employed as a tridentate ligand for the synthesis of new complexes through reaction with Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) metal ions. The synthesized HL and its metal complexes were characterized using various physicochemical techniques including elemental analysis, Fourier transform infrared and UV–visible spectroscopies, conductimetric and magnetic susceptibility measurements, mass spectrometry and thermal analyses. ¹H NMR data indicated that complex formation was through the amino group rather than the aliphatic hydroxyl group. Thermal analysis gave an idea about the decomposition pattern of HL and its complexes. Also, it revealed the number of water molecules in the inner and outer spheres of the complexes. An octahedral geometry for all the complexes has been suggested. HL and its complexes were screened for their antimicrobial activity against various species of bacteria and fungi using the disc diffusion method. The Cr(III) complex had the highest antimicrobial activity.     

On the improvement of network resource utilization efficiency for the establishment of static dependable connections in SRLG-constrained WDM translucent networks

In this paper, we investigate the problem of establishing static connections with fault-tolerant requirements, also known as dependable connections, taking into account quality of transmission constraints. To the best of our knowledge, this is the first study that tackles the aforementioned problem under shared risk link group (SRLG) constraints in translucent WDM optical mesh networks where typically a set of strategically localized network nodes are equipped with regeneration capability to overcome physical-layer impairment effects. A novel cross-layer heuristic approach is introduced to solve the problem for an heterogeneous networked scenario relying on a cost-effective two-stage protection procedure which combines the well-known path protection and partial path protection schemes in order to ensure instantaneous recovery from any SRLG-failure event. The proposed heuristic integrates a generic auxiliary graph model that incorporates various network heterogeneity factors such as the number of transceivers at each network node, the number of wavelengths on each fiber link, and the regeneration capability of each node, represented by different edges in the constructed graph. Moreover, the integrated auxiliary graph can be applied efficiently to model either single- or mixed-line-rate translucent WDM optical networks wherein different modulation formats are employed in order to support the transmission at different line rates. Our solution approach aims at maximizing the total number of accommodated requests by reducing network resource consumption through the simultaneous use of the backup–backup and primary–backup multiplexing techniques. We, here, present extended versions of these two techniques that generalize the sharing concept to some other important node resources—specifically, regeneration equipments which constitute the major cost factor in optical transport networks—in addition to link resources (i.e., wavelength channels). As far as we know, this is the first attempt to deploy simultaneously generalized versions of the backup–backup and primary–backup multiplexing techniques when considering static traffic patterns without compromising the 100 % fault-recoverability guarantee. The performances of the proposed heuristic are evaluated and discussed through extensive numerical experiments carried out on different network topologies. Significant improvements are demonstrated, either in terms of network blocking performance or in terms of resource utilization efficiency, in comparison with previously proposed approaches.     

Structures of oxaliplatin‐oligonucleotide adducts from DNA

Oxaliplatin, [(1R,2R)‐cyclohexane‐1,2‐diamine](ethanedioato‐O,O')platinum(II) shows a great efficiency against colorectal cancer. Although the mode of action of oxaliplatin is not yet understood, it is commonly accepted that binding of oxaliplatin to DNA prevents DNA synthesis and alters protein to DNA binding. In order to elucidate the modified DNA–protein interaction and thus to understand the mechanisms leading to cellular misinterpretation of DNA information and apoptosis, we have identified the preferential binding sites and the dynamics of the oxaliplatin‐DNA intrastrand and interstrand adducts at the oligomer level using high‐performance liquid chromatography/electrospray ionization‐tandem mass spectrometry (HPLC/ESI‐MS/MS) and HPLC/inductively coupled plasma‐MS for quantitative studies. We used a combination of benzonase, alkaline phosphatase and Nuclease S1 for digestion. This digestion procedure allows the study of platinated oligomeric nucleotides and more complex interstrand adducts. The digestion products were mostly chromatographically separated and characterized using HPLC/ESI‐ion trap MS/MS experiments. We could show that the adducts to guanine and adenine are quite dynamic; that is, the ratios are changing for several days. In addition, the resulting adducts provide evidence for the action of the digesting enzymes and indicate that the adduct spectrum at the oligomeric level is different to that at the commonly studies dinucleotide level. Copyright © 2012 John Wiley & Sons, Ltd.     

Methylol‐functional benzoxazines as precursors for high‐performance thermoset polymers: Unique simultaneous addition and condensation polymerization behavior

A new class of high‐performance resins of combined molecular structure of both traditional phenolics and benzoxazines has been developed. The monomers termed as methylol‐functional benzoxazines were synthesized through Mannich condensation reaction of methylol‐functional phenols and aromatic amines, including methylenedianiline (4,4′‐diaminodiphenylmethane) and oxydianiline (4,4′‐diaminodiphenyl ether), in the presence of paraformaldehyde. For comparison, other series of benzoxazine monomers were prepared from phenol, corresponding aromatic amines, and paraformaldehyde. The as‐synthesized monomers are characterized by their high purity as judged from ¹H NMR and Fourier transform infrared spectra. Differential scanning calorimetric thermograms of the novel monomers show two exothermic peaks associated with condensation reaction of methylol groups and ring‐opening polymerization of benzoxazines. The position of methylol group relative to benzoxazine structure plays a significant role in accelerating polymerization. Viscoelastic and thermogravimetric analyses of the crosslinked polymers reveal high T_g (274–343 °C) and excellent thermal stability when compared with the traditional polybenzoxazines. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Performance evaluation of an efficient reduced-complexity time synchronization approach for OFDM systems

This paper presents a performance analysis of a recently proposed preamble-based reduced-complexity (RC) two-stage synchronization technique. The preamble, composed of two identical subsequences, is first used to determine an uncertainty interval based on Cox and Schmidl algorithm. Then, a differential correlation-based metric is carried using a new sequence obtained by element wise multiplication of the preamble subsequence and a shifted version of it. This second step is performed to fine tune the coarse time estimate, by carrying the differential correlation-based metric over the uncertainty interval of limited width around the coarse estimate, thus leading to low computational load. In this paper, we first discuss some complexity issues of the RC approach compared to previously proposed algorithms. Then, we study the effect of the training sequence class and length choices on the synchronization performance in the case of multipath channels. The impact of the uncertainty interval width on the trade-off between performance and complexity is also studied. The two-stage approach was found to provide almost equal performance to those obtained by the most efficient differential correlation-based benchmarks. However, it has a very reduced computational load, equivalent to that of sliding correlation-based approaches.     

Characterization of an Algerian diatomite by inverse gas chromatography: Specific and non-specific contribution and Lewis acid–base parameters

The fundamental understanding of the behavior of a solid is intimately related to the understanding of the interactions on the surface of the latter, a major challenge in particular if the material is natural and ecological. The infinite dilution-inverse gas chromatography was used to evaluate the surface thermodynamic properties of several phases (grafted and/or coated) diatomite. A series of non- or polar-solute probes were injected at temperatures of 45?°C and 90?°C. The dispersive surface free energies values of the supports decrease with increasing temperature and their active surface is amphoteric with predominantly acidic character.     

Catalytic activity of nickel(II), copper(II) and oxovanadium(II)‐dihydroindolone complexes towards homogeneous oxidation reactions

Three novel paramagnetic metal complexes (MH₂ID) of Ni²⁺, Cu²⁺ and VO²⁺ ions with 3‐hydroxy‐3,3’‐biindoline‐2,2’‐dione (dihydroindolone, H₄ID) were synthesized and characterized by different spectroscopic methods. The ligand (H₄ID) was synthesized via homocoupling reaction of isatin in presence of phenylalanine in methanol. Complexation of low valent Ni²⁺, Cu²⁺ ions and high valent VO²⁺ ions with H₄ID carried out in 1: 2 molar ratios. A comparison in the catalytic potential of paramagnetic complexes of low and high valent metal ion was explored in the oxidation processes of cis‐cyclooctene, benzyl alcohol and thiophene by an aqueous H₂O₂, as a green terminal oxidant, in the presence and absence of acetonitrile, as an organic solvent, at 85 °C. NiH₂ID, CuH₂ID and VOH₂ID show good catalytic activity, i.e. good chemo‐ and regioselectivity. VOH₂ID has the highest catalytic potential compared to both Ni²⁺‐ and Cu²⁺‐species in the same homogenous aerobic atmosphere. Catalytic oxidation of other alkenes and alcohols was also studied using NiH₂ID, CuH₂ID or VOH₂ID as a pre‐catalyst by an aqueous H₂O₂. A mechanistic pathway for those oxidation processes was proposed.