An efficient synthesis of 3-amino-2-arylimidazo[1,2-a]pyridines

An efficient synthesis of 3-amino-2-arylimidazo[1,2-a]pyridines is described via a novel multicomponent reaction between 2-aminopyridines, benzaldehydes and imidazoline-2,4,5-trione under solvent-free conditions.     

Reaction of benzoyl chlorides with Huisgen's zwitterion: synthesis of functionalized 2,5-dihydro-1H-pyrroles and tetrasubstituted furans

The 1:1 intermediate generated by the addition of alkyl(aryl) isocyanides to dimethyl acetylenedicarboxylate is trapped by benzoyl chloride to yield functionalized 2,5-dihydro-1H-pyrroles. The presence of electron-withdrawing groups at the para position of benzoyl chloride leads to tetrasubstituted furans. The structures of these products were confirmed by single-crystal X-ray diffraction studies.     

Flow Around a Crack in a Porous Matrix and Related Problems

The equations governing plane steady-state flow in heterogeneous porous body containing cracks are presented first. Then, a general transformation lemma is presented which allows extending a particular solution obtained for a given flow problem to another configuration with different geometry, behaviour and boundary conditions. An existing potential solution in terms of discharges along the cracks, established by Liolios and Exadaktylos (J Solids Struct 43:3960–3982, 2006) for non-intersecting cracks in isotropic matrix, is extended to intersecting cracks in anisotropic matrix. The basic problem of a single straight crack in an infinite body submitted to a pressure gradient at infinity is then investigated and a closed-form solution is presented for the case of void cracks (infinite conductivity), as well as a semi-analytical solution for the case of cracks with Poiseuille type conductivity. These solutions, derived first for an isotropic matrix, are then extended to anisotropic matrices using the general transformation lemma. Finally, using the solution obtained for a single crack, a closed-form estimation of the effective permeability of micro-cracked porous materials with weak crack density is derived from a self-consistent upscaling scheme.     

Advanced Drug Delivery Micro- and Nanosystems for Cardiovascular Diseases

Advanced drug delivery micro- and nanosystems have been widely explored due to their appealing specificity/selectivity, biodegradability, biocompatibility, and low toxicity. They can be applied for the targeted delivery of pharmaceuticals, with the benefits of good biocompatibility/stability, non-immunogenicity, large surface area, high drug loading capacity, and low leakage of drugs. Cardiovascular diseases, as one of the primary mortalities cause worldwide with significant impacts on the quality of patients’ life, comprise a variety of heart and circulatory system pathologies, such as peripheral vascular diseases, myocardial infarction, heart failure, and coronary artery diseases. Designing novel micro- and nanosystems with suitable targeting properties and smart release behaviors can help circumvent crucial challenges of the tolerability, low stability, high toxicity, and possible side- and off-target effects of conventional drug delivery routes. To overcome different challenging issues, namely physiological barriers, low efficiency of drugs, and possible adverse side effects, various biomaterials-mediated drug delivery systems have been formulated with reduced toxicity, improved pharmacokinetics, high bioavailability, sustained release behavior, and enhanced therapeutic efficacy for targeted therapy of cardiovascular diseases. Despite the existing drug delivery systems encompassing a variety of biomaterials for treating cardiovascular diseases, the number of formulations currently approved for clinical use is limited due to the regulatory and experimental obstacles. Herein, the most recent advancements in drug delivery micro- and nanosystems designed from different biomaterials for the treatment of cardiovascular diseases are deliberated, with a focus on the important challenges and future perspectives.     

Meshless local Petrov-Galerkin (MLPG) approximation to the two dimensional sine-Gordon equation

During the past few years, the idea of using meshless methods for numerical solution of partial differential equations (PDEs) has received much attention throughout the scientific community, and remarkable progress has been achieved on meshless methods. The meshless local Petrov-Galerkin (MLPG) method is one of the “truly meshless” methods since it does not require any background integration cells. The integrations are carried out locally over small sub-domains of regular shapes, such as circles or squares in two dimensions and spheres or cubes in three dimensions. In this paper the MLPG method for numerically solving the non-linear two-dimensional sine-Gordon (SG) equation is developed. A time-stepping method is employed to deal with the time derivative and a simple predictor-corrector scheme is performed to eliminate the non-linearity. A brief discussion is outlined for numerical integrations in the proposed algorithm. Some examples involving line and ring solitons are demonstrated and the conservation of energy in undamped SG equation is investigated. The final numerical results confirm the ability of proposed method to deal with the unsteady non-linear problems in large domains.     

Directed Evolution of a Bacterial Laccase (CueO) for Enzymatic Biofuel Cells

Escherichia coli's copper efflux oxidase (CueO) has rarely been employed in the cathodic compartment of enzymatic biofuel cells (EBFCs) due to its low redox potential (0.36 V vs. Ag/AgCl, pH 5.5) towards O₂ reduction. Herein, directed evolution of CueO towards a more positive onset potential was performed in an electrochemical screening system. An improved CueO variant (D439T/L502K) was obtained with a significantly increased onset potential (0.54 V), comparable to that of high‐redox‐potential fungal laccases. Upon coupling with an anodic compartment, the EBFC exhibited an open‐circuit voltage (V_oc) of 0.56 V. Directed enzyme evolution by tailoring enzymes to application conditions in EBFCs has been validated and might, in combination with molecular understanding, enable future breakthroughs in EBFC performance     

A robust-adaptive fuzzy coverage control for robotic swarms

In this paper, a decentralized adaptive control scheme for multi-robot coverage is proposed. This control method is designed based on centroidal Voronoi configuration integrated with robust adaptive fuzzy control techniques. We consider simple single integrator mobile robots used for covering dynamical environments, where an adaptive fuzzy logic system is used to approximate the unknown parts of control law. A robust coverage criterion is used to attenuate the adaptive fuzzy approximation error and measurement noises to a prescribed level. Therefore, the robots motion is forced to obey solutions of a coverage optimization problem. The advantages of the proposed controller can be listed as robustness to external disturbances, computation uncertainties, and measurement noises, while applicability on dynamical environments. A Lyapunov-function based proof is given of robust stability, i.e. convergence to the optimal positions with bounded error. Finally, simulation results are demonstrated for a swarm coverage problem simultaneous with tracking mobile intruders.     

A new approach in modeling of constant temperature boundary condition in thermal lattice‐Boltzmann method

The lattice‐Boltzmann method is being applied to a diversity of fluid flow and heat transfer problems nowadays. Because of its microscale nature, strict attention should be paid when introducing macroscopic inputs to the model. One of the challenging issues dealing with macroscale and microscale treatment is the implementation of boundary conditions. In this regard constant‐temperature boundaries are frequently used in energy transfer problems. Such boundaries are simply modeled in Navier–Stokes based solvers, but they are not so harnessed in lattice‐Boltzmann models. One of the problems is that the calculated tangential heat flux is not zero along such boundaries in most of the previous models. In the present paper, a model has been developed, which has the capability of controlling tangential heat flux along the constant‐temperature boundaries. It aims to set the heat flux nearly zero along the boundary in midplane grid schemes. Copyright © 2012 John Wiley & Sons, Ltd.     

Experimental and quantum chemical study on the IR, UV and electrode potential of 6-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-inden-2-yl)-2,3-dihydroxybenzaldehyde

Electrode potential of 6-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-inden-2-yl)-2,3-dihydroxybenzaldehyde (DPDB) in methanol have been calculated theoretically. For the achievement of this task, the density functional theory (B3LYP/6-31G(d)) was employed with the inclusion of the entropic and thermochemical corrections to yield the free energies of the redox reactions. The electrode potential was also obtained experimentally by means of an electrochemical technique (cyclic voltammetry). The geometric parameters, the vibrational frequency values and the UV spectrum of DPDB and 2-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-inden-2-yl)-5,6-dioxocyclohexa-1,3-dienecarbaldehyde (DPDD is the oxidized form of DPDB), were computed using the same methods. The calculated IR spectrum of DPDB, used for the assignment of the IR frequencies, was observed in the experimental FT-IR spectrum. The correlation between the theoretical and experimental DPDB vibrational frequencies was 0.996. This agreement mutually verified the accuracy of the experimental method and the validity of the applied mathematical model.