Surfactant-mediated desorption of polymer from the nanoparticle interface

The surfactant-mediated desorption of adsorbed poly(vinylpyrrolidone), PVP, from anionic silica surfaces by sodium dodecyl sulfate, SDS, was observed. While photon correlation spectroscopy shows that the size of the polymer-surfactant-particle ensemble grows with added SDS, a reduction in the near-surface polymer concentration is measured by solvent relaxation NMR. Volume fraction profiles of the polymer layer extracted from small-angle neutron scattering experiments illustrate that the adsorbed polymer layer has become more diffuse and the polymer chains more elongated as a result of the addition of SDS. The total adsorbed amount is shown to decrease due to Coulombic repulsion between the surfactant-polymer complexes and between the complexes and the anionic silica surface.     

Parameter estimation in exponentially fitted hybrid methods for second order differential problems

In this work we deal with exponentially fitted methods for the numerical solution of second order ordinary differential equations, whose solutions are known to show a prominent exponential behaviour depending on the value of an unknown parameter to be suitably determined. The knowledge of an estimation to the unknown parameter is needed in order to apply the numerical method, since its coefficients depend on the value of the parameter. We present a strategy for the practical estimation of the parameter, which is also tested on some selected problems.     

关于Lucas多项式平方和的恒等式

利用广义Lucas多项式L n(x,y)的性质,通过构造组合和式T n(x,y;tx2),结合Bernoulli多项式的生成函数和Euler多项式的生成函数,采用分析学中的方法,得到两个有关L2n(x,y)的恒等式.并从这一结果出发,得到了两个推论,推广了相关文献的一些结果.     

Isolation of ZnO-binding 12-mer peptides and determination of their binding epitopes by NMR spectroscopy

Inorganic-binding peptides are in the focus of research fields such as materials science, nanotechnology, and biotechnology. Applications concern surface functionalization by the specific coupling to inorganic target substrates, the binding of soluble molecules for sensing applications, or biomineralization approaches for the controlled formation of inorganic materials. The specific molecular recognition of inorganic surfaces by peptides is of major importance for such applications. Zinc oxide (ZnO) is an important semiconductor material which is applied in various devices. In this study the molecular fundamentals for a ZnO-binding epitope was determined. 12-mer peptides, which specifically bind to the zinc- or/and the oxygen-terminated sides of single-crystalline ZnO (0001) and (000-1) substrates, were selected from a random peptide library using the phage display technique. For two ZnO-binding peptides the mandatory amino acid residues, which are of crucial importance for the specific binding were determined with a label-free nuclear magnetic resonance (NMR) approach. NMR spectroscopy allows the identification of pH dependent interaction sites on the atomic level of 12-mer peptides and ZnO nanoparticles. Here, ionic and polar interaction forces were determined. For the oxygen-terminated side the consensus peptide-binding sequence (HSXXH) was predicted in silico and confirmed by the NMR approach.     

Optical soliton perturbation in non-Kerr law media: Traveling wave solution

This paper analyses the dynamics of soliton propagation through optical fibers with non-Kerr law nonlinearities. The governing nonlinear Schrödinger equation is integrated in the presence of perturbation terms. The traveling wave hypothesis is used to carry out the integration. Domain restrictions on the soliton parameters are identified in the process. The five forms of nonlinearity that are studied are Kerr-law, power-law, parabolic-law, dual-power law and the log-law nonlinearity. Numerical simulations are presented for each of these nonlinear media.     

Preparation and Characterization of Activated Carbon – nFe3O4, Activated Carbon – nSiO2 and Activated Carbon – nZnO Hybrid Materials

The preparation and physicochemical characterization of activated carbon, nano metal oxides, and activated carbon – nFe₃O₄, activated carbon – nSiO₂ and activated carbon – nZnO hybrid materials has been undertaken. The materials have been characterized by scanning and transmission electron microscopy, x‐ray diffraction, CNH analysis and Fourier transform infrared spectroscopy. Surface area and porosity, ash content, pH, and point of zero charge were also measured. The results showed that the surfaces of activated carbon, nSiO₂, activated carbon – nFe₃O₄, activated carbon – nSiO₂ and activated carbon – nZnO are suitable for the sorption of cationic complexes while the surfaces of nFe₃O₄ and nZnO are favourable to the sorption of anionic complexes of heavy metals. Results also showed that the composition of the activated carbon and nano metal oxides increased the surface and micropore areas of nano metal oxides due to the large number of micropores and crevices on the surface of the hybrid materials.     

Crude extract of Origanum vulgare L. induced cell death and suppressed MAPK and PI3/Akt signaling pathways in SW13 and H295R cell lines

Oregano (Origanum vulgare L.) is a common aromatic plant used in Mediterranean and Asian Regions for treating respiratory diseases, painful menstruation, rheumatoid arthritis, etc. Recently its role as an anticancer plant has been suggested, although oregano has been never evaluated into adrenocortical tumour cell models. This study analysed for the first time the anticancer effects of a crude extract of wild mountain oregano (Origanum vulgare L.) in SW13 and H295R cell lines. The crude extract was characterised by GC/MS and the toxic effects of oregano were first analysed by brine shrimp lethality assay. Our findings demonstrated that oregano decreased cell viability, survival, modified cell cycle and induced cell death (through necrotic process) and that the effects can be attributed to a blockade of MAPK and PI3 K/Akt pathways. These results suggest that oregano extract exerts anticancer activities in adrenocortical tumour cell lines, providing evidence for further research in higher models.     

A comparative study of pure and potassium doped cadmium mercury thiocyanate single crystals grown in silica gel

Pure and potassium doped cadmium mercury thiocyanate single crystals have been obtained from silica gel by the process of diffusion. The X‐ray diffraction studies reveal the crystal lattice of both pure and doped crystals to be tetragonal. The crystalline perfection of the grown crystals were investigated by high resolution X‐ray diffraction analysis and the quality of the crystals are found to be extremely good. Transmission and Fourier transform infrared spectra were recorded for the grown crystals. The TG/DTA analyses show that the crystals are highly thermally stable. The mechanical strength of the crystals were studied by Vickers microhardness test and a study of their second harmonic generation efficiency in comparison with urea has been made by performing Kurtz powder test. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Key physicochemical properties of nanomaterials in view of their toxicity: an exploratory systematic investigation for the example of carbon-based nanomaterial

Currently, a noncomprehensive understanding of the physicochemical properties of carbon-based nanomaterial (CBNs), which may affect toxic effects, is still observable. In this study, an exploratory systematic investigation into the key physicochemical properties of multiwall carbon nanotube (MWCNT), single-wall carbon nanotube (SWCNT), and C₆₀-fullerene on their ecotoxicity has been undertaken. We undertook an extensive survey of the literature pertaining to the ecotoxicity of organism representative of the trophic level of algae, crustaceans, and fish. Based on this, a set of data reporting both the physicochemical properties of carbon-based nanomaterial and the observed toxic effect has been established. The relationship between physicochemical properties and observed toxic effect was investigated based on various statistical approaches. Specifically, analysis of variance by one-way ANOVA was used to assess the effect of categorical properties (use of a dispersant or treatments in the test medium, type of carbon-based nanomaterial, i.e., SWCNT, MWCNT, C₆₀-fullerene, functionalization), while multiple regression analysis was used to assess the effect of quantitative properties (i.e., diameter length of nanotubes, secondary size) on the toxicity values. The here described investigations revealed significant relationships among the physicochemical properties and observed toxic effects. The research was mainly affected by the low availability of data and also by the low variability of the studies collected. Overall, our results demonstrate that the here proposed and applied approach could have a major role in identifying the physicochemical properties of relevance for the toxicity of nanomaterial. However, the future success of the approach would require that the ENMs and the experimental conditions used in the toxicity studies are fully characterized.