Optical,electrical and morphological properties of transparent binary doped polyaniline thin films synthesized by in situ chemical bath deposition

The development of polymeric thin films has attracted attention in the optoelectronics field due to their transparency. The aim of the research presented was to obtain transparent polyaniline thin films by easy in situ oxidative polymerization of aniline with ammonium persulfate in the presence of a binary doping agent–poly(vinyl alcohol) mixture. Poly(acrylic acid), 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid or sodium dodecylsulfate were mixed with hydrochloric acid to form the binary doping agents. Polyaniline thin films were produced during aniline polymerization on Corning glass slides immersed in the mixture in order to study their optical, electrical and morphological properties. The optical absorption coefficient and the energy band gap were evaluated by optical transmission of the films in the UV‐visible spectral region. The optical absorption coefficient of all polyaniline films was of the order of 10⁴ cm^?1 with a maximum transmittance up to 80% at 550 nm. In order to investigate the effect of the mixture on the surface morphology and roughness of the films, atomic force microscopy was used. In general, surface roughness was reduced threefold by adding a mixture and optical transmission was increased by 20–30% without significantly affecting the absorption coefficient and the band gap of polyaniline. Islands and needle‐like structures on the film surfaces were obtained from various mixtures affecting the conductivity; for example, 0.17 S cm^?1 was obtained from needle‐like morphology, while 1.9 × 10^?4 S cm^?1 was obtained from island morphology. Raman spectroscopy studies confirmed the presence of poly(vinyl alcohol) in the thin films. Copyright © 2011 Society of Chemical Industry     

Spanish scientific and technical journals. State of the art

This article analyses the current situation in the field of scientific and technical journals published in Spain, by determining the following scientific indicators for each: I: Specifications. II: Scientific production covered. III: Visibility and accessibility. The first section provides a qualitative and quantitative study of the journals, asking what subjects they cover, who publishes them, how often they are published, how up to data they are and whether the way they are presented meets international publishing standards. The second section analyses scientific production by research sectors and the percentage of articles collected in the ICYT database compared with the total number of papers published in the journals studied. It also studies the reference habits of the authors published therein to identify whether the literature referred to is of local origin or international. Finally, the third section deduces these journals' degree of visibility by analysing how they are distributed amongst the usual media, i.e. international periodicals directories and databases, and how efficiently they work as vehicles for the diffusion of research by foreign authors. The study covers 10 years (1980–1989), thus enabling to recognise past and current trends in Spanish scientific literature.     

Effect of Potassium Doping on the Catalytic Behavior of Mo–V–Sb Mixed Oxide Catalysts in the Oxidation of Propane to Acrylic Acid

Small addition of potassium to a Mo–V–Sb mixed oxide catalyst (previously prepared by hydrothermal synthesis) strongly modifies its catalytic behavior. Thus, while acetic acid is mainly observed in the K-free catalysts, acrylic acid is selectively obtained in K-doped catalysts. In this case, a selectivity to acrylic acid of about 30% is achieved at propane conversions of 30%. This catalytic behavior is apparently not due to modification of the crystalline phases in the K-doped catalysts but to the elimination of the acid sites of the undoped Mo–V–Sb mixed oxide catalyst.     

Use of manganese in ripe olive processing

 The use of manganese (Mn) salts in various steps of the processing of ripe olives of the Manzanilla cultivar can increase their oxidation rate and produce darker olives. The best results were obtained by adding a Mn concentration of 40 mg/l to the storage brine and allowing a period of contact of at least 15 days. Good results were also obtained when using a Mn concentration of 100–250 mg/l in a “desalting” step before darkening, as well as variable periods of contact and temperatures. When Mn was added to the washing waters after any of the lye treatments of the darkening step, especially the first one, the effect was also appreciable, although varying degrees of Mn residues in the flesh were found. Addition of Mn to the storage brine and application of the usual darkening process produced more uniform and darker ripe olives with Mn residue levels at below 30 mg/kg, which is approximately 15% of the recommended daily intake for this metal. Results suggest that this cation, recognized as GRAS in the USA, may be used as a catalyst in the darkening of ripe olives if authorized as a processing aid. Received: 25 July 1997 / Revised version: 16 October 1997     

Bactericidal effect of saffron (Crocus sativus L.) on Salmonella enterica during storage

The presence of pathogenic bacteria in spices represents a public health risk as a possible cause of food contamination. Salmonella has been found in several spices and it has been involved in food-borne outbreaks, but this bacterium has not been reported as a contaminant of saffron (Crocus sativus L.). We examined a possible antibacterial effect of saffron using samples from Iran, Greece and Spain which were artificially contaminated with clinical isolates belonging to five different serovars of Salmonella. We detected a loss of viability during the room-temperature storage of the saffron samples, with bacteria being undetectable at day 16 except in the case of the DT104 strain of the Typhimurium serovar, in all of the samples, and of the Hadar serovar in the Iranian sample, both of which gave negative culture at day 32. The laboratory strain LT2 of the Typhimurium serovar was undetectable at day 4. To gain an insight into the basis for this bactericidal effect, we measured the inhibitory and bactericidal concentrations of safranal and crocin, the main compounds responsible for the flavouring and colouring capabilities of saffron. They were in the order of 8–16 mg/mL and 64–128 mg/mL for safranal and crocin, respectively. These data suggest that these compounds, and probably their chemical relatives, are involved in the antibacterial activity of saffron, and that this effect can significantly reduce the risk of food contamination with Salmonella by this spice.     

Bread staling assessment of enzyme-supplemented pan breads by dynamic and static deformation measurements

Dynamic mechanical analysis and thermal mechanical analysis techniques were used in order to evaluate the effect of amylolytic-, non-amylolytic- and gluten-cross-linking enzymes on the viscoelastic properties of fresh and stored pan breads. The relationships between dynamic and static compression measurements in bread staling characterization and the correlations between sensory firmness and thermomechanical properties were also investigated. Rheological changes in bread associated with recipe and storage time were successfully detected via dynamic thermomechanical analysis (DTMA) in the compression mode. Relationships between the dynamic (DTMA) and static (texture analysis) methods were found. All the bread quality indicators measured by static methods were negatively correlated with the viscoelastic dynamic parameters.     

Antioxidant properties,radical scavenging activity and biomolecule protection capacity of flavonoid naringenin and its glycoside naringin: a comparative study

BACKGROUND: This study was designed to evaluate and compare antioxidant capacity and radical scavenging activity of naringin and its aglycone by different in vitro assays. The effects of flavanones on lipid peroxidation, glutathione (GSH) oxidation and DNA cleavage were also assessed. RESULTS: The results showed that naringenin exhibited higher antioxidant capacity and hydroxyl and superoxide radical scavenger efficiency than naringin. Our results evidenced that glycosylation attenuated the efficiency in inhibiting the enzyme xanthine oxidase and the aglycone could act like a more active chelator of metallic ions than the glycoside. Additionally, naringenin showed a greater effectiveness in the protection against oxidative damage to lipids in a dose‐dependent manner. Both flavanones were equally effective in reducing DNA damage. However, they show no protective effect on oxidation of GSH. CONCLUSION: The data obtained support the importance of characterizing the ratio naringin/naringenin in foods when they are evaluated for their health benefits. Copyright © 2010 Society of Chemical Industry     

Synthesis,Structural Analysis,and Biological Evaluation of Thioxoquinazoline Derivatives as Phosphodiesterase 7 Inhibitors

PDE7 inhibitors regulate pro‐inflammatory and immune T‐cell functions, and are a potentially novel class of drugs particularly useful for treatment of a wide variety of immune and inflammatory disorders. Structural optimization of thioxoquinazoline derivatives led to new compounds with very interesting profiles as PDE7 or PDE7/PDE4 dual inhibitors, which may be further developed as new drugs for inflammatory and neurological diseases.

     

Alpha-Galactosides: Antinutritional Factors or Functional Ingredients?

This review focuses on updated information about alpha-galactosides, their chemical structure, biosynthesis, plant physiological functions, occurrence in foods, positive and negative physiological effects in animals, changes during food processing, and their potential application as prebiotics in the food industry. Although alpha-galactosides are considered as the main flatus-causing factors, they are also involved in several important functions during plant and seed development and beneficially stimulate the growth and activity of living bifidobacteria and lactobacilli in the human colon. We focus here also on legumes as a source of this kind of prebiotics as potential health promoters.