Selective interaction between nanotubes and perylene‐based surfactant

We recently reported a significant deviation in the photoluminescence intensities of HiPco nanotubes solubilized with a perylene‐based surfactant, C16 , compared to bile salt surfactants. For C16 , the photoluminescence emission of chiralities (9,5), (10,3), and (11,1) is enhanced by up to 430%. Resonant Raman spectroscopy is less sensitive to bundling state and also yields disparate chirality intensity ratios: The (11,0) zigzag tube signal increases by 100% compared to (8,6), (9,4), and (10,2) after suspension with C16 . We also report the change in photoluminescence intensity distribution after the swelling of bile salt suspended nanotubes with a series of small organic chromophores in DCM. These changes are attributed to chromophore‐induced surfactant reorganization, resulting in better nanotube individualization. The chirality for which the PL intensity is most enhanced is (11,1) for all chromophores, a chirality also increased by 300% in the C16 ‐solubilized sample. Conjointly, these measurements indicate that both preferential solubilization and enhanced debundling contribute to the PL intensity distribution in the C16 ‐solubilized nanotube sample. This has wide ranging implications for the design of chirally selective surfactants and the demonstration of their selectivity, which is typically only shown through luminescence measurements. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A note on the matrix Sturm‐Liouville operators with principal functions

In this study, we take under investigation principal functions corresponding to the eigenvalues and the spectral singularities of the Operator L generated in by the differential expression and the boundary condition (A₀ + A₁λ + A₂λ²)y^′(0,λ) ? (B₀ + B₁λ + B₂λ²)y(0,λ) = 0, where Q is a matrix‐valued function and A_i,B_i,i = 0,1,2 are non‐selfadjoint matrices also A₂,B₂ are invertible.     

Morphology and properties of natural rubber with nanomatrix of non‐rubber components

The morphology of natural rubber was observed by transmission electron microscopy. Nanomatrix of non‐rubber components such as proteins and phospholipids was found to be inherently formed in natural rubber, in which natural rubber particles of about 0.5 µm in average diameter were dispersed. The nanomatrix of non‐rubber components disappeared after deproteinization of natural rubber with urea. Stress at break of serum rubber was higher than that of deproteinized natural rubber, while strain at break did not change. When the amount of the non‐rubber components increased, the stress at break became significantly dependent upon the amount of non‐rubber components. Viscoelastic properties of natural rubber were also dependent upon the nanomatrix of non‐rubber components. Storage modulus of natural rubber increased significantly, when the amount of the non‐rubber components increased. Copyright © 2010 John Wiley & Sons, Ltd.     

Synthesis of IIB group derived of N-methyl caprolactam-3-dithiocarboxylic acid complexes: thermal properties

The synthesis of N-methylcaprolactam-3-dithiocarboxylic acid complexes with the non transition metals Zn(II), Cd(II) and Hg(II) were carried out and the complexes characterized using FT–IR, Raman, XRD, SEM, EDS and elemental analyses. The IR results confirm the link between the caprolactam and the dithiocarboxylate through the C–S bond, whereas Raman spectroscopy gave information about the S–M stretch for each complex. X-ray diffraction analysis shows that the complexes adopt tetrahedral coordination geometry. The SEM showed the morphology of the complexes and the EDS gave a semi-quantitative analysis of the complexes. A comparative study was made among the complexes observing their thermal stability using TGA and DSC. Thermogravimetric study (TGA) indicated different stability of the complexes with the zinc(II) complex most stable.     

Green synthesis and chemical characterization of silver nanoparticles from aqueous extract of Falcaria vulgaris leaves and assessment of their cytotoxicity and antioxidant,antibacterial, antifungal and cutaneous wound healing properties

Nanotechnology encompasses the understanding of the fundamental physics, biology, chemistry and technology of nanometre‐scale objects. In recent decades, nanotechnology has grown rapidly owing to its widespread application in science and industry. The aim of the work reported was the green synthesis and chemical characterization of silver nanoparticles from aqueous extract of Falcaria vulgaris leaves (AgNPs@Falcaria) and evaluation of their cytotoxicity and antioxidant, antibacterial, antifungal and cutaneous wound healing effects under in vitro and in vivo conditions. These nanoparticles were characterized using Fourier transform infrared and UV–visible spectroscopies, scanning and transmission electron microscopies and atomic force microscopy. 2,2‐Diphenyl‐1‐picrylhydrazyl free radical scavenging experiments were conducted to evaluate the antioxidant potential, which indicated similar antioxidant potentials for AgNPs@Falcaria and butylated hydroxytoluene. The synthesized AgNPs@Falcaria had great cell viability dose‐dependently, indicating their non‐toxicity. Minimum inhibitory, minimum bactericidal and minimum fungicidal concentrations were determined by macro‐broth dilution assay. The data were analysed using SPSS software (Duncan post hoc test). AgNPs@Falcaria revealed higher antibacterial and antifungal activities than many standard antibiotics (p ≤ 0.01). Also, AgNPs@Falcaria prevented the growth of all bacteria at 2–8 mg ml^?1 concentrations and removed them at 4–16 mg ml^?1 concentrations (p ≤ 0.01). AgNPs@Falcaria inhibited the growth of all fungi at 2–4 mg ml^?1 concentrations and destroyed them at 4–8 mg ml^?1 concentrations (p ≤ 0.01). For in vivo experiments, after creating a cutaneous wound, rats were randomly divided into six groups: untreated control, treatment with eucerin basal ointment, treatment with 3% tetracycline ointment, treatment with 0.2% AgNO₃ ointment, treatment with 0.2% F. vulgaris ointment and treatment with 0.2% AgNPs@Falcaria ointment. Use of AgNPs@Falcaria ointment in the treatment groups substantially decreased (p ≤ 0.01) the wound area, total cells, neutrophils and lymphocytes and markedly raised (p ≤ 0.01) wound contracture, hydroxyproline, hexosamine, hexuronic acid, fibrocytes and fibrocyte/fibroblast ratio compared to the other groups. In summary, the synthesized AgNPs@Falcaria revealed non‐cytotoxicity and antioxidant, antibacterial, antifungal and cutaneous wound healing activities in a dose‐dependent manner.     

Numerical analysis of axisymmetric and planar sudden expansion flows for laminar regime

In this study, the Navier–Stokes equations are solved numerically for axisymmetric and planar sudden expansion flows. The flow is considered laminar and steady state, and the fluid is incompressible. Finite difference equations are obtained using a control volume method in a non‐staggered grid arrangement, and solved by line‐by‐line TDMA technique using the SIMPLEM (SIMPLEM‐Modified) algorithm. Calculations are performed for higher expansion ratios, β, ranging from 1.5 to 10 and Reynolds numbers from 0.1 to 500. Results are presented in terms of streamlines, relative eddy intensity, location of the eddy center, and the eddy reattachment length depending on Re number and β values for both axisymmetric and planar sudden expansions. It is aimed to provide a picture of the effects of high values of expansion ratio and Reynolds number on the sudden expansion flow. As a result, it is found that the flow characteristics keep their structure for both higher expansion ratios and higher Reynolds numbers. Further, correlations were developed for the nondimensional eddy reattachment length, location of the eddy center and the relative eddy intensity, which have agreeable results to the computed results available from the literature. Copyright © 2010 John Wiley & Sons, Ltd.     

Topoisomerase I inhibitory and photocleavage activity of non‐dppz DNA ‘light switches’ based on ruthenium complexes containing nitro group

A new polypyridyl ligand containing a nitro group and two new ruthenium complexes of it were synthesized. The two complexes exhibited non‐dppz DNA ‘light switch’ effects after interaction with calf thymus DNA. Introducing both electron‐withdrawing group (─ NO₂) and electron‐donating group (─ CH₃) may be the reason that the two complexes display DNA ‘light switch’ behaviors. Furthermore, one of the complexes showed higher photocleavage activity, topoisomerase I inhibition activity and DNA affinity than the other. The present work shows that the more active complex can be employed as a non‐dppz DNA ‘light switch’, DNA photocleaver and topoisomerase I inhibitor. In addition, the two complexes have no or weak cytotoxic activities against Eca‐109 and A549 cells.     

A rapid and simple assay for lamotrigine in serum/plasma by HPLC,and comparison with an immunoassay

Monitoring serum/plasma concentrations of lamotrigine may be useful under certain circumstances. An HPLC column packed with strong cation‐exchange (SCX)‐modified microparticulate silica together with a 100% methanol eluent containing an ionic modifier permits direct injection of sample extracts. An HPLC‐UV method developed using this principle for the measurement of serum/plasma lamotrigine is simple, sensitive and selective. The analysis time is less than 5 min. Intra‐ and inter‐assay precision and accuracy meet acceptance criteria, and sample stability, and potential interferences from other compounds have been evaluated. There was good agreement with consensus mean results from external quality assessment samples (n = 32). Analysis of patient samples (n = 115) using the HPLC method and the Seradyn QMS® Lamotrigine immunoassay showed that the immunoassay over‐estimated lamotrigine by 21% on average. Copyright © 2010 John Wiley & Sons, Ltd.     

A horizontally curvilinear non‐hydrostatic model for simulating nonlinear wave motion in curved boundaries

A horizontally curvilinear non‐hydrostatic free surface model that embeds the second‐order projection method, the so‐called θ scheme, in fractional time stepping is developed to simulate nonlinear wave motion in curved boundaries. The model solves the unsteady, Navier–Stokes equations in a three‐dimensional curvilinear domain by incorporating the kinematic free surface boundary condition with a top‐layer boundary condition, which has been developed to improve the numerical accuracy and efficiency of the non‐hydrostatic model in the standard staggered grid layout. The second‐order Adams–Bashforth scheme with the third‐order spatial upwind method is implemented in discretizing advection terms. Numerical accuracy in terms of nonlinear phase speed and amplitude is verified against the nonlinear Stokes wave theory over varying wave steepness in a two‐dimensional numerical wave tank. The model is then applied to investigate the nonlinear wave characteristics in the presence of dispersion caused by reflection and diffraction in a semicircular channel. The model results agree quantitatively with superimposed analytical solutions. Finally, the model is applied to simulate nonlinear wave run‐ups caused by wave‐body interaction around a bottom‐mounted cylinder. The numerical results exhibit good agreement with experimental data and the second‐order diffraction theory. Overall, it is shown that the developed model, with only three vertical layers, is capable of accurately simulating nonlinear waves interacting within curved boundaries. Copyright © 2011 John Wiley & Sons, Ltd.     

The non‐reflective interface: an innovative forcing technique for computational acoustic hybrid methods

The present article concerns a commonly used methodology for the numerical simulation of acoustic emission and propagation phenomena. We consider the so‐called multi‐stage hybrid acoustic approach, in which a given noise problem is simulated via a sequence of weakly coupled computations of noise generation and acoustic propagation stages, wherein the simulation of the propagation stage is based on advanced Computational AeroAcoustics (CAA) techniques. The paper introduces an original forcing technique, namely, the Non‐Reflective Interface (NRI), to enable the transfer of an acoustic signal from an a priori noise generation stage into a CAA‐based acoustic propagation phase. Unlike most existing forcing techniques, the NRI is non‐reflective (or anechoic) in nature and, therefore, can properly handle the backscattering effects arising during the noise propagation stage. This attribute makes the NRI‐based weak‐coupling procedure and the associated CAA‐based hybrid approach compatible with a larger variety of realistic noise problems (such as those involving installed configurations in wind tunnel experiments, for instance). The NRI technique is first validated via several test cases of increasing complexity and is then applied to two aerodynamic noise problems. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.