Waveguide-modulated surface plasmon-coupled emission of Nile blue in poly(vinyl alcohol) thin films

Surface plasmon-coupled emission (SPCE) phenomenon is the coupling of excited fluorophores near a silver film with surface plasmons, resulting in directional emission into the underlying glass substrates. We report a complex coupling of Nile Blue fluorophore with 50 nm silver mirror, resulting in emission at several angles in the glass substrate, with either s or p polarization. This complex pattern of directional and polarized emission appears to be due to optical waveguide effects occurring when the sample thickness becomes comparable to the emission wavelength. We expect waveguide-modulated SPCE to have applications to biophysics and sensing.     

Pentachlorophenol sorption in nylon fiber and removal by immobilized Rhizopus oryzae ENHE

This study describes pentachlophenol (PCP) sorption in nylon fiber in which Rhizopus oryzae ENHE was immobilized to remove the chemical compound. The experimental sorption data were analyzed using the Langmuir, Freundlich, and Redlich-Peterson isotherm models using non-linear error functions to fit the experimental data to the three models. Results showed that the isotherm obtained from the data fitted the three models used. However, the g parameter from Redlich-Peterson model showed that the isotherm obtained approaches the Freundlich model. This support reached the sorption equilibrium concentration at 3mg PCPg(-1)nylon. To study PCP removal capability by R. oryzae ENHE and to eliminate the error caused by PCP sorbed by the nylon fiber during its quantification, nylon fiber at PCP equilibrium sorption concentration was used to immobilize R. oryzae ENHE. It was found that this fungus grew within nylon fiber cubes in presence or not of PCP, even when PCP caused growth inhibition. Maximum biomass accumulated into nylon cubes without PCP was of 32 mg biomass g(-1)nylon and into nylon cubes at PCP equilibrium concentration was of 18 mg g(-1)nylon. The results showed that R. oryzae ENHE immobilized into nylon fiber removed 88.6% and 92% of PCP in cultures with 12.5 and 25 mg PCPL(-1), as initial concentration, respectively. This is the first work to report that a zygomycete, such as R. oryzae ENHE, immobilized into nylon fiber kept its potential to remove PCP.     

Photolytic breakdown of fullerene C60 cages in an aqueous suspension

Fullerene C60, a class of carbon nanomaterials, is widely used and is likely to reach the environment. The degradation and transformation of C60 aqueous suspensions exposed to simulated sunlight were studied. C60 aqueous suspensions prepared by stirring pristine C60 in water under sunlight exposure undergo breakdown with formation of a mixture of compounds with unknown chemical structure. The mass and infrared spectrometric analysis of the breakdown products shows the presence of broken C60 cages, as well as of oxygen and hydrogen atoms in their structure. The presence of oxygen in the breakdown products indicates a possible interaction of C60 molecule with oxygen from the air as well as with water. Interaction with water could also explain the presence of H atoms in the breakdown products. This demonstrates that fullerenes C60 are not stable in the environment and that the breakdown products should be considered when evaluating the environmental impact of fullerenes C60.     

Investigations of pitting corrosion of magnesium by means of DEIS and acoustic emission

The paper presents methodology and results of electrochemical examination of magnesium in 0.1 M NaCl solution with different pH. The measurements were conducted under potentiodynamic conditions using Dynamic Electrochemical Impedance Spectroscopy (DEIS). Analysis of DEIS results was performed based on electrical equivalent circuit. As the result of analysis changes of separate parameters of the equivalent circuit vs. potential for different pH values of the environment were obtained. Simultaneously with DEIS measurements an investigation using acoustic emission was conducted. The results showed that for pH higher than 12.50 the properties of layers on the surface of magnesium change significantly. One can observe a stable passive state that has properties considerably different from those of the layers that form in solutions with lower alkalinity. In such conditions the beginning of pitting corrosion process can be unequivocally determined by the level of acoustic emission and the values of electrochemical parameters.     

Chemical stability and electrical properties of BaCe0.85Y0.15O3−δ–Ce0.85Y0.15O2−δ composite bulk samples for use as central membrane materials in dual PCFC–SOFC fuel cells

The goal of the presented research was to determine the physicochemical properties of composite samples obtained by mixing BaCe_0.85Y_0.15O_3−δ (BCY15) and Ce_0.85Y_0.15O_2−δ (YDC15) in different ratios, and to achieve a better understanding of how these ratios affect the electrical conductivity, chemical stability and morphology of BCY15–YDC15 composite materials. It was determined that the samples are chemically stable in H₂O-containing atmospheres at 600 °C. Furthermore, the porosity of the samples increases with the addition of YDC15 to BCY15. Both the porosity and the BCY15/YDC15 ratio affect the stability of the studied samples. The total activation energy (E_t) values of the composite samples, determined via resistance measurements conducted in air at temperatures between 200 and 800 °C, are in the range of 0.590 ± 0.017 eV (E_t of BCY15) to 1.132 ± 0.008 eV (E_t of YDC15). This indicates that the properties of activation energy for composite materials are additive; the presence of both BCY15 and YDC15 affects the activation energy values. The different morphologies of the samples also influence the conductivity within the respective samples. The electrical conductivity values of the composite samples obtained at temperatures from 200 to 500 °C are in the order of magnitude of 10⁻⁷–10⁻³ S/cm. These values are between those determined for pure BCY15 and YDC15 at the respective measuring temperatures. Consequently, the materials show promise for application as porous central membranes (CM) in dual PCFC–SOFC fuel cells operating in the temperature range 600–700 °C.     

Oviductal Oxygen Homeostasis in Patients with Uterine Myoma: Correlation between Hypoxia and Telocytes

Oxygen balance is crucial for angiogenesis, immunity, and tissue repair. The human oviduct is essential for reproductive function, and any imbalance in homeostasis leads to fertility disturbances and might be a reason for ectopic pregnancy development. Uterine myoma is a widespread benign tumour, which is often accompanied by infertility. Telocytes have been discussed in the contexts of motility, fibrosis development, and angiogenesis. We observed the oviducts from patients with and without uterine myoma, comparing the expression of HIF-1, HO, VEGF and its receptor, NOS, oestrogen, and progesterone receptors by immunolabeling. The myometrial and oviductal telocytes were also compared in both groups. Biochemical analyses were conducted for FSH, LH, AMH, sFlt, oestrogen, and progesterone in blood samples. Patients with uterine myoma have different expressions of sex steroid receptors and an increased number of telocytes. The decreasing VEFG expression was compensated by the rise in the HIF-1 and NOS expression. Blood biochemical analyses revealed a higher progesterone level and lower AMH in patients with uterine myoma. No differences in sFlt, FSH, and LF were observed. Uterine myoma impacts oviduct oxygen homeostasis and might cause fertility disturbances (uterine and oviductal infertility factors).     

Texture and rheological properties of meat from pigs of different halothane genotypes

The effects of halothane genotype (NN, Nn and nn) in pigs on meat texture, rheological properties, fibre diameter, area of intramuscular fat, pH, colour, drip loss, cooking loss and yield of cooked and of smoked loin were examined. Cooked and smoked meat of NN pigs exhibited lower hardness, gumminess, chewiness, elasticity moduli, greater cohesiveness and a longer relaxation time compared to meat from pigs with genotype Nn or nn. Meat from pigs of the nn genotype exhibited the greatest hardness and elasticity, the shortest relaxation time and the lowest viscosity and cohesiveness, while meat from genotype Nn was intermediate regarding these parameters. Significant correlations were found between parameters of texture, and rheological properties and pH, structure, drip and cooking loss. © 1998 SCI.     

Intensive culture of Chlorella vulgaris/AA as the second stage of biological purification of nitrogen industry wastewaters

A method for the two-stage removal of nitrogen from highly loaded nitrogenous wastewaters carrying varying proportions of nitrates, nitrites and ammonium is presented. The method combines denitrification (stage 1 of purification) and intensive algal culture (stage II of purification). Denitrification in an anaerobic packed bed reactor removed all the oxidized forms of nitrogen from the wastes enriched in methanol and phosphorus. Ammonium remaining in the denitrified wastewaters was removed by intensive culture of algae. The use of this method resulted in 94.0–99.9% removal of nitrogen from the wastes. The application of the proposed method is limited, however, by the concentration of ammonium nitrogen in the wastewaters.     

Navigational facilities for relational data base

Charles Bachman's great idea of navigation in a data base is applied to the relational data model. This idea, understood as a way of user thinking, is formulated in such a manner, that no physical concepts are introduced to the user's awareness. Thus the demanded level of data independence is not reduced.A concept of “navigational statement” is defined. The navigational statements may be used to improve other relational languages, for example SEQUEL. It is shown that navigational statements simplify the grammar structure of language expressions and make them shorter and more readable. Elliptic (incomplete) navigational statements are also defined. Such statements may be regarded as a good tool for the casual user.This paper may be viewed as a (not necessarily complete) review of possibilities related to the idea of navigation in a relational data base.     

The mechanism of dry friction of polyoxymethylene against steel

The mechanism of friction between polyoxymethylene and steel was investigated. The coefficient of friction was determined, and the effects of the hardness of the steel, the roughness of the sliding surface, the temperature, the relative sliding velocity and the contact pressure were examined. Additional investigations were carried out to explain the mechanism of friction between the polymer and steel. Structural changes in the friction surfaces were investigated by microscope examination. Five fundamental types of friction were identified and are discussed.