Publications

The potential application of waste water treatment by photocatalysis is very likely to find its place in the near future. We have studied the photocatalytic degradation of three dyes (Eosin B, Rhodamine 6G, Rhodamine B) in the presence of doped n-TiO2 in water and found that anchoring groups are favorable to the photodegradation of the pollutants. Taking Rhodamine B as a model pollutant, this study points out an alternative route to enhance photodegradation in invisible light, which consumes energy to synthesize, but addition of 0.1 mM of I− or S2O32− increases the discoloration by up to three folds. For example, KI increased degradation to 36% while Na2S2O3 enhanced it by 61%, which was higher than that of pure n-TiO2 after sun light irradiation of 40 min. The enhancement of degradation by I− and S2O32− may be linked to the scavenging of the holes by the inorganic anions, thus inhibiting recombination between h+/e− after excitation of the semiconductor. The degradation is more effective in the presence of S2O32−. In the presence of 0.1 mM KI, the rate constant increased from 0.0231 s−1 to 0.0325 s−1.Peroxodisulphate increases degradation, however, this is attributed to the sulfate radicals.

Novel heterocyclic Schiff base dyes were prepared by the reaction of salicylaldehyde/2-Hydroxy-1-naphthaldehyde with different heterocyclic amines. Results of the newly synthesized compounds established by FT-IR, 1H-NMR, 13C-NMR and GC–MS spectroscopic experiments were consistent with their chemical structures. Resulted heterocyclic Schiff base dyes were found to be pure from data obtained by the elemental analysis. In addition, spectrophotometric and spectrofluorimetric studies showed that these dyes were good absorbent and fluorescent. Fluorescence polarity study data revealed that some of these compounds were sensitive to the polarity of the microenvironment provided by different solvents. Time-based fluorescence steady-state measurements also showed that these heterocyclic Schiff base dyes have high photostability against photobleaching.

Abstract Improved photochromic properties and fatigue performance of (E)‐dicyclopropylmethylene‐(2,5‐dimethyl‐3‐furylethylidene)‐succinicanhydride doped in polyurethane thin film were discussed in this study. Fulgide 1‐E doped in polyurethane polymer films was heated at various annealing temperatures. Upon irradiation with UV light (366 nm), fulgide 1‐E undergoes a conrotatory ring closure to the pink‐colored closed form 1‐C . The latter color was switched back to the original color when the films were irradiated with white light. The kinetics of photocoloration and photobleaching processes was followed spectrophotometrically by monitoring the absorbance of the ring‐closed product 1‐C at its λ max of 525 nm. The first‐order plots of photocoloration reaction show distinct linear line and the slope of which corresponding to the first‐order rate constants k . It was found that for photocoloration reaction, the rate constant of the photocoloration reaction is slower than the photobleaching reaction, and both reactions decrease with increasing the annealing temperatures. It was found that there was almost complete loss of photochemical fatigue resistance of fulgide 1 doped in polyurethane polymer film irrespective of the annealing temperature. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers

Previous studies have demonstrated greater cardiomyocyte density on carbon nanofibers (CNFs) aligned (compared to randomly oriented) in poly(lactic-co-glycolic acid) (PLGA) composites. Although such studies demonstrated a closer mimicking of anisotropic electrical and mechanical properties for such aligned (compared to randomly oriented) CNFs in PLGA composites, the objective of the present in vitro study was to elucidate a deeper mechanistic understanding of how cardiomyocyte densities recognize such materials to respond more favorably. Results showed lower wettability (greater hydrophobicity) of CNFs embedded in PLGA compared to pure PLGA, thus providing evidence of selectively lower wettability in aligned CNF regions. Furthermore, the results correlated these changes in hydrophobicity with increased adsorption of fibronectin, laminin, and vitronectin (all proteins known to increase cardiomyocyte adhesion and functions) on CNFs in PLGA compared to pure PLGA, thus providing evidence of selective initial protein adsorption cues on such CNF regions to promote cardiomyocyte adhesion and growth. Lastly, results of the present in vitro study further confirmed increased cardiomyocyte functions by demonstrating greater expression of important cardiomyocyte biomarkers (such as Troponin-T, Connexin-43, and α-sarcomeric actin) when CNFs were aligned compared to randomly oriented in PLGA. In summary, this study provided evidence that cardiomyocyte functions are improved on CNFs aligned in PLGA compared to randomly oriented in PLGA since CNFs are more hydrophobic than PLGA and attract the adsorption of key proteins (fibronectin, laminin, and vironectin) that are known to promote cardiomyocyte adhesion and expression of important cardiomyocyte functions. Thus, future studies should use this knowledge to further design improved CNF:PLGA composites for numerous cardiovascular applications.

Nanocrystalline Ni‐La‐Fe‐O catalysts having the general formula NiLa x Fe 2− x O 4 (0.00 ≤ x ≤ 2.00) were synthesized by the combustion route employing urea as a combustion fuel. The calcination process was affected at 500°C. The structural properties of the obtained catalysts were systematically investigated by X‐ray powder diffraction (XRD), scanning electronic microscopy (SEM), energy‐dispersive X‐ray spectra (EDX), and nitrogen adsorption at −196°C. Crystalline NiFe 2 O 4 and La 2 NiO 4 phases were detected for the catalysts having x = 0.00 and 2.00, respectively, as a result of solid‐solid interaction between mixtures precursors. The activity of the obtained catalysts was checked for hydrogen peroxide decomposition at 35–55°C. A synergic effect was observed for the catalysts having x ‐value of 1.00 and 1.50. Such effect was attributed to the increase in the number of the active constituents involved in the catalytic decomposition of H 2 O 2 .