Coupling Effects of Electrostatic Interactions and Salt Concentration Gradient in Polymer Translocation through a Nanopore: A Coarse-Grained Molecular Dynamics Simulations Study

We study the influence of polymer pore interactions and focus on the role played by the concentration gradient of salt in the translocation of polyelectrolytes (PE) through nanopores explicitly using coarse-grained Langevin dynamics simulations. The mean translocation time is calculated by varying the applied voltage, the pH, and the salt concentration gradient. Changing the pH can alter the electrostatic interaction between the protein pore and the polyelectrolyte chain. The polymer pore interaction is weakened by the increase in the strength of the externally applied electric field that drives translocation. Additionally, the screening effect of the salt can reduce the strong charge-charge repulsion between the PE beads which can make translocation faster. The simulation results show there can be antagonistic or synergistic coupling between the salt concentration-induced screening effect and the drift force originating from the salt concentration gradient thereby affecting the translocation time. Our simulation results are explained qualitatively with free energy calculations.     

Finite Inhomogeneous Shearing Deformations of a Transversely Isotropic Incompressible Material

The present paper deals with finite inhomogeneous shearing deformations of a slab of a special anisotropic solid. Two cases according to the directions of the anisotropic director of the medium are examined. In one case the solution reduces to a quadrature and gives an exact deformation field for particular values of the material constants. In the other case an exact solution is obtained. All such solutions reduce to the same existing solution for the corresponding isotropic elastic material. This revised version was published online in August 2006 with corrections to the Cover Date.     

Simultaneous bioanalysis and pharmacokinetic interaction study of acebrophylline,levocetirizine and pranlukast in Sprague–Dawley rats

The combination of acebrophylline (ABP), levocetirizine (LCZ) and pranlukast (PRN) is used to treat allergic rhinitis, asthma, hay‐fever and other conditions where patients experience difficulty in breathing. This study was carried out with the aim of developing and validating a reverse‐phase high‐performance liquid chromatographic bioanalytical method to simultaneously quantitate ABP, LCZ and PRN in rat plasma. The objective also includes determination of the pharmacokinetic interaction of these three drugs after administration via the oral route after individual and combination treatment in rat. Optimum resolution between the analytes was observed with a C₁₈ Kinetex column (250 mm × 4.6 mm × 5 μm). The chromatography was performed in a gradient elution mode with a 1 mL/min flow rate. The calibration curves were linear over the concentration range of 100–1600 ng/mL. The intra‐ and inter‐day precision and accuracy were found to be within acceptable limits as specified in US Food and Drug Administration guideline for bioanalytical method validation. The analytes were stable on the bench‐top (8 h), after three freeze–thaw cycles, in the autosampler (8 h) and as a dry extract (?80°C for 48 h). The statistical results of the pharmacokinetic study in Sprague–Dawley rats showed a significant change in pharmacokinetic parameters for PRN upon co‐administration of the three drugs.     

Structural,electronic, and mechanical properties of cubic TiO_2:A first-principles study

We present an analysis of structural, electronic, and mechanical properties of cubic titanium dioxide(TiO_2) using an all electron orthogonalzed linear combinations of atomic orbitals(OLCAO) basis set under the framework of density functional theory(DFT). The structural property, especially the lattice constant a, and the electronic properties such as the band diagram and density of states(DOS) are studied and analyzed. The mechanical properties such as bulk moduli, shear moduli, Young's Moduli, and Poison's ratio are also investigated thoroughly. The calculations are carried out on shear moduli and anisotropy factor for cubic TiO_2. The Vickers hardness is also tested for fluorite and pyrite cubic-structured TiO_2. Furthermore, the results are compared with the previous theoretical and experimental results. It is found that DFTbased simulation produces results which are approximation to experimental results, whereas the calculated elastic constants are better than the previous theoretical and experimental values.     

Structure-Based Design,Synthesis, and Biological Evaluation of Hsp90β-Selective Inhibitors

The 90 kDa heat shock proteins (Hsp90) are molecular chaperones that are responsible for the folding and/or trafficking of ∼400 client proteins, many of which are directly associated with cancer progression. Consequently, inhibition of Hsp90 can exhibit similar activity as combination therapy as multiple signaling nodes can be targeted simultaneously. In fact, seventeen small-molecule inhibitors that bind the Hsp90 N-terminus entered clinical trials for the treatment of cancer, all of which exhibited pan-inhibitory activity against all four Hsp90 isoforms. Unfortunately, most demonstrated undesired effects alongside induction of the pro-survival heat shock response. As a result, isoform-selective inhibitors have been sought to overcome these detriments. Described herein is a structure-based approach to design Hsp90β-selective inhibitors along with preliminary SAR. In the end, compound 5 was shown to manifest ∼370-fold selectivity for Hsp90β versus Hsp90α, and induced the degradation of select Hsp90β-dependent clients. These data support the development of Hsp90β-selective inhibitors as a new paradigm to overcome the detriments associated with pan-inhibition of Hsp90.     

Leading-Order Dynamics of Gravity-Driven Flows in?Free-Standing Soap Films

We derive the leading-order equations that govern the dynamics of the flow in a falling, free-standing soap film. Starting with the incompressible Navier?CStokes equations, we carry out an asymptotic analysis using parameters that correspond to a common experimental setup. We account for the effects of inertia, surface elasticity, pressure, viscous stresses, gravity, and air drag. We find that the dynamics of the flow is dominated by the effects of inertia, surface elasticity, gravity, and air drag. We solve the leading-order equations to compute the steady-state profiles of velocity, thickness, and pressure in an experiment in which the film is in the Marangoni elasticity regime. The computational results, which include a Marangoni shock, are in good accord with the experimental measurements.     

The asymptotic iteration method applied to certain quasinormal modes and non Hermitian systems

We study the Schrödinger equation with potentials admitting quasinormal modes using the asymptotic iteration method (AIM). We also study non-Hermitian PT symmetric potentials using AIM. The spectra, in all cases, are found to be in excellent agreement with exact results.     

Synthesis and antiviral activity of novel pyrazole amides containing α‐aminophosphonate moiety

A series of novel pyrazole amides J1 , J2 , J3 , J4 , J5 , J6 , J7 , J8 , J9 , J10 , J11 , J12 , J13 , J14 , J15 containing an α‐aminophosphonate moiety were synthesized and subsequently characterized by spectral (IR, ¹H‐, ¹³C‐, ³¹P‐, and ¹⁹F‐NMR) data and elemental analysis. The racemic sample of J1 was further separated into its enantiomers under normal‐phase condition on two immobilized polysaccharide‐based chiral stationary phases (Chiralpak IA and Chiralpak IC). The synthesized compounds revealed certain degree of antiviral activity in the bioassay. The title compounds ( J3 , J10 , and J12 ) showed some curative activities (39.9%, 41.8%, 50.1%, respectively) against tobacco mosaic virus at 0.5 mg/mL. J. Heterocyclic Chem., 00 , 00 (2011).