Resins containing α-hydroxyphosphonic acid groups used for adsorption of dyes from wastewater

The synthesis of styrene–divinylbenzene copolymers functionalized with α-hydroxyphosphonic acid groups is presented. The phosphorus content was determined in order to calculate the degree of functionalization with pendant α-hydroxyphosphonic group, with values of 0.66 for St–1%DVB_HOPHOS and 3.14 for St–6.7%DVB_HOPHOS. Their characterization by IR, thermogravimetry is reported. The kinetics of adsorption of three dyes on St–6.7%DVB_HOPHOS polymer was studied.     

The effect of arginine on gold nanoparticles in colloidal solutions and in thin films

Gold nanoparticles were prepared in aqueous colloidal solutions and their interaction with L-arginine solutions at different concentrations was investigated by UV-vis spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM). The shift towards red of the absorption maximum of gold nanoparticles with increasing L-arginine concentration and in time, and the apparition of a new large band at higher wavelength evidence the formation of assemblies of gold nanoparticles, mediated by the amino acid. TEM images present the progress in the building process of supermolecular structures. Further, the AFM images show the self assemblies of gold nanoparticles capped with L-arginine well ordered in large domains on silanized glass. As a model for the process, we suggest that the positively charged guanidinium group of L-arginine is anchored on the negative citrate capped gold nanoparticles, while the other two functionalities of L-arginine are involved in the bonding between gold nanoparticles. The ability of arginine to specifically bind gold nanoparticles could lead to an increased ability of proteins, containing arginine, to specifically bind to nanogold. Then, they bind other target proteins or different ligands underlying numerous biological and medical applications that range from nanoscale biosensors, cell-cell communications to targeted delivery of drugs to cancer cells.     

Design of experiments for statistical modeling and multi-response optimization of nickel electroplating process

The central composite experimental design and response surface methodology have been employed for statistical modeling and analysis of the results dealing with nickel electroplating process. The empirical models developed in terms of design variables (current density J (A/dm²), temperature T (°C) and pH) have been found statistically adequate to describe the process responses, i.e. cathode efficiency Y (%), coating thickness U (μm), brightness V (%) and hardness W (HV). The graphical representations consisted of 2D contour plots and 3D surface plots have been used for exploring and analysis of response surfaces in order to identify the main, quadratic and interaction effects. The multi-response optimization of nickel electroplating process has been carried out by means of desirability function approach. To this end, a genetic algorithm has been used for mathematical optimization of the multi-response problem. The optimization algorithm has conducted to a set of equivalent solutions named Pareto optimal set. The confirmation runs have been employed in order to make a decision about the optimal solution approved by experiment. Thus, the optimum conditions of nickel electroplating has been defined in this work as J* = 5.35 (A/dm²), T* = 33.44 (°C) and pH* = 6.22 and respectively the responses confirmed by experiment were Y = 79.12 ± 0.18 (%), U = 52.77 ± 0.48 (μm), V = 26.12 ± 0.45 (%) and W = 371.6 ± 1.77 (HV). In such conditions the quality of nickel electroplating deposit was the best one in accordance with experimental results.     

Solid state properties of thin films of new copoly(azomethine‐sulfone)s

A series of four copoly(azomethine‐sulfone)s have been synthesized and extensively characterized. The chemical design has been thought to obtain semiconducting properties and thermotropic behavior matching the processing of the materials from the ordered melted state, suitable for the spontaneous alignment of molecules in the active layer on a substrate. Prototypes of thin films based on this series of polymers have been electrically and structurally characterized. It was found that the respective polymers show typical semiconducting properties. The thermal properties with particular reference to their mesomorphic state were checked by using differential scanning calorimetry, polarized light microscopy, and thermogravimetric analysis techniques. Morphological characterization was realized by atomic force microscopy and X‐ray diffraction measurements. Some correlations between electrical properties and packing closeness were established. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

UV‐curable nanocomposites containing zirconium vinylphosphonate or zirconia

UV‐cured nanocomposite films were prepared from acrylic monomer and two types of nanomaterial: zirconium vinylphosphonate and zirconia, in the presence of a photoinitiator. The films were characterized by FTIR, SEM, and AFM. FTIR spectra showed the disappearance of band assigned to the CC group both of monomer and zirconium vinylphosphonate by polymerization and the presence of the phosphonate group in polymer. The influence of zirconium vinylphosphonate and zirconia content on thermooxidative degradation of polymeric films was studied by thermogravimetry. SEM and AFM images showed that nanomaterials are dispersed in polymer matrix with no macroscopic phase separation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A system analysis of technological changes in the Romanian high voltage power network

Increasing demand for energy requires large-scale construction of power plants and adequate growth of the transmission network. Currently, several high-voltage transmission subsystems (110, 220, 400, 500, and 750 kV) coexist in the same network. We investigate the mechanism of substitution of voltage for the medium-size energy system in Romania by using the Marchetti-Nakicenovic model and Romanian data of the period 1965–1981. The horizon of our prediction is up to the year 2030.     

Strong magneto-chiral dichroism in enantiopure chiral ferromagnets

As materials science is moving towards the synthesis, the study and the processing of new materials exhibiting well-defined and complex functions, the synthesis of new multifunctional materials is one of the important challenges. One of these complex physical properties is magneto-chiral dichroism which arises, at second order, from the coexistence of spatial asymmetry and magnetization in a material. Herein we report the first measurement of strong magneto-chiral dichroism in an enantiopure chiral ferromagnet. The ab initio synthesis of the enantiopure chiral ferromagnet is based on an enantioselective self-assembly, where a resolved chiral quaternary ammonium cation imposes the absolute configurations of the metal centres within chromium-manganese two-dimensional oxalate layers. The ferromagnetic interaction between Cr(III) and Mn(II) ions leads to a Curie temperature of 7 K. The magneto-chiral dichroic effect is enhanced by a factor of 17 when entering into the ferromagnetic phase.