Real time laser interference microscopy for bar‐spread polystyrene/poly(methyl methacrylate) blends

We demonstrate that real‐time laser interference microscopy can be used to directly observe the dynamics of film formation and phase separation processes for a bar‐spread polystyrene/poly(methyl methacrylate) blend. The ability to dynamically image laser interference patterns allows compete drying curves and polymer content to be determined throughout the film formation process. The polymer content at which phase separation structure first is observed in the interference micrograph sequence is in good agreement with calculated spinodal curves. Morphology evolution proceeds from phase separation onward via coarsening and coalescence to arrive at the final domain structure. In comparison, spin coating the same polymer blend results in structure evolution being quenched further from equilibrium due to the faster drying rate. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 985–992     

Photocatalytic degradation of carcinogenic Congo red dye in aqueous solution,antioxidant activity and bactericidal effect of NiO nanoparticles

Journal of the Iranian Chemical Society - Face-centered cubic structure of nickel oxide (NiO) nanoparticles with 30 nm average size was synthesized by co-precipitation method with some...     

On the numerical solution of nonlinear Burgers’-type equations using meshless method of lines

In this paper, a meshless method of lines (MMOL) is proposed for the numerical solution of nonlinear Burgers’-type equations. This technique does not require a mesh in the problem domain, and only a set of scattered nodes provided by initial data is required for the solution of the problem using some radial basis functions (RBFs). The scheme is tested for various examples. The results obtained by this method are compared with the exact solutions and some earlier work.     

Comparison of the X-ray photoelectron and electron-energy-loss spectra of the nitrogen-doped hydrogenated amorphous carbon bond

The composition of nitrogen-doped hydrogenated amorphous carbon (a-C : H : N) films grown in a magnetically confined rf plasma-enhanced chemical vapour deposition system has been determined by X-ray photoelectron spectroscopy (XPS) and compared with that determined using a combination of elastic recoil detection analysis, Rutherford back-scattering and nuclear reaction analysis. The importance of nitrogen doping or 'incorporation' in hydrogenated amorphous carbon (a-C : H) films is discussed in relation to the significant variation in the sp 2 -to-sp 3 ratio that takes place. At 7 at.% N in the a-C : H matrix, a critical change in the microstructure is observed, which governs the resulting mechanical, optical and electronic properties. Finally, the correlation between the sp 2 and sp 3 fractions determined by a non-destructive method of obtaining the bond fractions (XPS) and by electron-energy-loss spectroscopy is discussed, with a view to evaluating accurately the sp 2 fraction in a-C : H : N films.     

Combining wire and coaxial powder feeding in laser direct metal deposition for rapid prototyping

Powder and wire deposition have been used separately in many laser-cladding, rapid prototyping and other additive manufacturing applications. In this paper, a new approach is investigated by simultaneously feeding powder from a coaxial nozzle and wire from an off-axis nozzle into the deposition melt pool. Multilayer parts are built from 316L steel using a 1.5 kW diode laser and different configurations of the powder and wire nozzles are compared in terms of surface roughness, deposition rate, porosity and microstructure. The parts are analysed using scanning electron microscopy (SEM), X-ray diffraction (XRD) and optical microscopy techniques. Results show that deposition efficiency increased and surface roughness decreased with the combined process; some porosity was present in samples produced by this method, but it was 20-30% less than in samples produced by powder alone. Wire injection angles into the melt pool in both horizontal and vertical planes were found to be significant for attaining high deposition efficiency and good surface quality. Reasons for the final sample characteristics and differences between the combined process and the separate powder and wire feeding techniques are discussed.     

Polymorphism in supramolecular chiral structures of R- and S-alanine on Cu(1 1 0)

A comprehensive study of the local and supramolecular adsorption structures created by the chiral R- and S-enantiomers of alanine on the Cu(1 1 0) surface has been conducted using a multi-technique approach, including reflection absorption infrared spectroscopy (RAIRS), X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and scanning tunnelling microscopy (STM). Over the entire 300–470 K temperature range studied, the amino acid is found to adsorb as an alaninate species with a local chiral adsorption motif. However, this singular preference of local chemical form contrasts sharply with the supramolecular organisation at the surface where polymorphism is exhibited. This polymorphic behaviour arises from subtle and dynamic changes in the bonding, orientation and adsorption footprints of individual molecules, leading to alterations in the molecule–metal, intermolecular and metal–metal interactions that dictate self-assembly. Thus, at low coverage, a single disordered phase is observed but at higher coverage, three other temperature dependent phases occur. At room temperature, a two-dimensional equivalent of a ‘nematic’ phase is constructed from short single- and double-chain chiral assemblies that possess a preferred chiral orientation but no long range periodicity. This ‘nematic’ phase acts as a precursor to a highly ordered chiral supramolecular assembly, created at 430 K, that consists of regular arrays of size- and shape-defined chiral clusters. This phase possesses global organisational chirality with only one chiral domain observed for each enantiomer. For both the ‘nematic’ and the highly ordered chiral phase, the organisation for the R-enantiomer is the mirror image of that seen for the S-enantiomer, i.e., there is chirality transfer from the nanoscale to the macroscale. By 470 K, both R- and S-alanine form an achirally organised (3 × 2) structure that appears to be the thermodynamically favoured phase for the alanine/Cu(1 1 0) system. The supramolecular organisation and chirality of the various structures are discussed in terms of the molecular chirality and footprint chirality of the alaninate, together with possible intermolecular interactions and reconstructions of the underlying metal surface atoms. A number of candidate models for the system are suggested, but it is clear that a full understanding of this complex adsorption system will only emerge from further careful, high level experimental and computational efforts that currently remain a challenge.     

Aminosilane Functionalized Aligned Fiber PCL Scaffolds for Peripheral Nerve Repair

Silane modification is a simple and cost-effective tool to modify existing biomaterials for tissue engineering applications. Aminosilane layer deposition has previously been shown to control NG108-15 neuronal cell and primary Schwann cell adhesion and differentiation by controlling deposition of ─NH₂ groups at the submicron scale across the entirety of a surface by varying silane chain length. This is the first study toreport depositing 11-aminoundecyltriethoxysilane (CL11) onto aligned Polycaprolactone (PCL) scaffolds for peripheral nerve regeneration. Fibers are manufactured via electrospinning and characterized using water contact angle measurements, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Confirmed modified fibers are investigated using in vitro cell culture of NG108-15 neuronal cells and primary Schwann cells to determine cell viability, cell differentiation, and phenotype. CL11-modified fibers significantly support NG108-15 neuronal cell and Schwann cell viability. NG108-15 neuronal cell differentiation maintains Schwann cell phenotype compared to unmodified PCL fiber scaffolds. 3D ex vivo culture of Dorsal root ganglion explants (DRGs) confirms further Schwann cell migration and longer neurite outgrowth from DRG explants cultured on CL11 fiber scaffolds compared to unmodified scaffolds. Thus, a reproducible and cost-effective tool is reported to modify biomaterials with functional amine groups that can significantly improve nerve guidance devices and enhance nerve regeneration.     

Racemic versus enantiopure alanine on Cu(110): an experimental study

The adsorption of racemic alanine on the Cu(110) surface has been compared to that of enantiopure alanine using low-energy electron diffraction (LEED), reflection absorption infrared spectroscopy (RAIRS), and scanning tunneling microscopy (STM). No evidence of chiral resolution at the surface was observed for the racemic system, indicating that the formation of separate enantiopure areas is not preferred. Also, in contrast to the enantiopure system, no chirally organized phase was observed for the racemic system. LEED shows that both systems display a common (3 x 2) phase at high coverage. However, the pathway and kinetic barriers to this phase differ markedly for the racemic and the enantiopure systems, with the racemic (3 x 2) appearing at a temperature that is more than 100 K below that required for the enantiopure system. In addition, we report intriguing complexities for the (3 x 2) LEED structure that is ubiquitous in amino acid/Cu(110) systems. First, a common (3 x 2) pattern with a zigzag distortion can be associated with both the racemic and enantiopure systems. For the racemic system, the coverage can be increased further to give a "true" (3 x 2) LEED pattern, which is a transformation that is impossible to enact for the enantiopure system. Most importantly, STM images of the "distorted" and "true" (3 x 2) structures created in the racemic system show subtle differences with neither arrangement being fully periodic over distances greater than a few molecules. Thus, the (3 x 2) phase appears to be more complicated than at first indicated and will require more complex models for a full interpretation.     

Enhanced Removal of Cu(II) and Pb(II) from Aqueous Solutions by Pretreated Biomass of Fusarium Solani

This study investigated the feasibility of Fusarium solani biomass as a biosorbent for Cu(II) and Pb(II) removal from aqueous solutions. Batch sorption experiments were carried out for Cu(II) and Pb(II) to quantify the sorption kinetics, pH, biosorbent dose and pretreatment of F. solani biomass. Biomass metal uptake clearly competed with protons present in the aqueous medium, making pH an important variable in the process. The maximum biosorption by F. solani biomass was obtained with solutions having pH 5 for both metal ions. An enhanced Cu(II) removal (96.53%) was observed for aluminum hydroxide pretreated biomass. Maximum Pb(II) removal (95.48%) was observed with native biomass. Time dependence experiments for the metal ions uptake showed that adsorption equilibrium reached almost 240 min after metal addition. The kinetic studies showed that the biosorption process followed the pseudo second‐order rate model for Cu(II) and Pb(II). The equilibrium data fitted well to the Langmiur isotherm model.     

Unique intermolecular reaction of simple porphyrins at a metal surface gives covalent nanostructures

Deposition of a porphyrin onto metallic copper followed by heating leads to an unprecedented type of linking of the molecules giving a mixture of covalent multiporphyrin nanostructures at the surface.