A time-dependent Mueller-like formulation for the study of the RF spectrum and time-resolved polarization phenomena in birefringent systems

Using a novel 4/spl times/4 Mueller-like time-dependent matrix to describe the propagation of modulated light in birefringent optical systems, a new method for characterizing the polarization dependence of the RF spectrum in systems having polarization-mode dispersion and polarization-dependent loss is proposed and demonstrated. By measuring the RF spectra for nine different input states of polarization (SOP), the spectrum of any other input SOP is accurately predicted. Another application of the general formulation allows the study of the dependence of the time-resolved characteristics of the SOP of light propagating in a birefringent medium.     

Evaluation of model compounds–polypropylene film interactions by Fourier transformed infrared spectroscopy (FTIR) method

The interactions of methyl esters, methyl ketones and aldehyde compounds with polypropylene (PP) film were investigated. PP film, placed on a glass vial, was immersed in aqueous solution containing a model flavour compound. After a determined time at 45°C, the PP film was analysed by Fourier transform infrared spectroscopy (FTIR), allowing us to follow the speed of sorption and to quantify its relative rate. For PP films, we observed that the sorption strongly depended on the structure of sorbed molecules. For each functional group of flavour compounds, the sorption increased as the carbon chain number increased. A linear chain of 12–14 carbons favours the sorption more than a linear chain of eight carbons. Concerning functions, the rate of sorption usually decreases from esters to ketones and to aldehydes. High sorption was observed for flavour compounds with a low difference of solubility parameter (SP) value between the film and flavour [(δ_polymer ? δ_flavour)² value]. Furthermore, by using the proposed thermodynamic affinity concept, represented as the contribution of three interactive molecular forces [dispersion (d_d), polar (d_p) and hydrogen bonding (d_h)] between two SP values of film and flavour, packaging materials with high flavour preservation against sorption can be designed. We have a good correlation between the kinetic sorption by FTIR and the SP concept. Copyright © 2007 John Wiley & Sons, Ltd.     

Decision making and personality in traffic offenders: a study of Israeli drivers

Traffic offences present danger to the offender, and to others. This study examines differences in decision making and personality between traffic offenders and non-offenders. Fifty-one traffic offenders participating in penalty courses were compared to a control group of 36 drivers who were not penalized for traffic offences in the 5 years prior to the study. All participants performed the Iowa Gambling Task (IGT), a popular decision task employed for assessing cognitive impulsivity, and completed the "big five" personality questionnaire. The results showed that traffic offenders made fewer advantageous choices on the IGT; and an analysis with a formal cognitive model, the Expectancy Valance model, suggests that this results from offenders' high weighting of gains compared to losses. An examination of personality factors reveals that traffic offenders were more extraverted. The predictive power of IGT performance was comparable to that of the personality factor. These results demonstrate that the IGT can be useful for studying individual differences in risk taking in a real-world task, and combined with the EV model, identify the sources of these differences.     

Detection of gaseous plumes in IR hyperspectral images using hierarchical clustering

The emergence of IR hyperspectral sensors in recent years enables their use in remote environmental monitoring of gaseous plumes. IR hyperspectral imaging combines the unique advantages of traditional remote sensing methods such as multispectral imagery and nonimaging Fourier transform infrared spectroscopy, while eliminating their drawbacks. The most significant improvement introduced by hyperspectral technology is the capability of standoff detection and discrimination of effluent gaseous plumes without need for a clear reference background or any other temporal information. We introduce a novel approach for detection and discrimination of gaseous plumes in IR hyperspectral imagery using a divisive hierarchical clustering algorithm. The utility of the suggested detection algorithm is demonstrated on IR hyperspectral images of the release of two atmospheric tracers. The application of the proposed detection method on the experimental data has yielded a correct identification of all the releases without any false alarms. These encouraging results show that the presented approach can be used as a basis for a complete identification algorithm for gaseous pollutants in IR hyperspectral imagery without the need for a clear background.     

Self-assembled lamellar MoS2, SnS2 and SiO2 semiconducting polymer nanocomposites

Lamellar nanocomposites based on semiconducting polymers incorporated into layered inorganic matrices are prepared by the co-assembly of organic and inorganic precursors. Semiconducting polymer-incorporated silica is prepared by introducing the semiconducting polymers into a tetrahydrofuran (THF)/water homogeneous sol solution containing silica precursor species and a surface-active agent. Semiconducting polymer-incorporated MoS(2) and SnS(2) are prepared by Li intercalation into the inorganic compound, exfoliation and restack in the presence of the semiconducting polymer. All lamellar nanocomposite films are organized in domains aligned parallel to the substrate surface plane. The incorporated polymers maintain their semiconducting properties, as evident from their optical absorption and photoluminescence spectra. The optoelectronic properties of the nanocomposites depend on the properties of both the inorganic host and the incorporated guest polymer as demonstrated by integrating the nanocomposite films into light-emitting diodes. Devices based on polymer-incorporated silica and polymer-incorporated MoS(2) show no diode behaviour and no light emission due to the insulating and metallic properties of the silica and MoS(2) hosts. In contrast, diode performance and electroluminescence are obtained from devices based on semiconducting polymer-incorporated semiconducting SnS(2), demonstrating that judicious selection of the composite components in combination with the optimization of material synthesis conditions allows new hierarchical structures to be tailored for electronic and optoelectronic applications.     

Reducing the formation of glucose degradation products in peritoneal dialysis solutions by ultrahigh temperature ohmic heating

Peritoneal dialysis (PD) is commonly performed by using preprepared dialysis solutions containing glucose, which are thermally treated to achieve commercial sterilization. A series of glucose degradation products (GDPs) are being formed, which react with the tissue during the dialysis procedure, thus baring a negative effect on the patient and the dialysis process. The present study tested the efficacy of ohmic heating as an alternative thermal treatment for continuous sterilization of PD solutions. The process was compared to conventional retort treatment, and GDPs accumulation was measured. Thermal treatments using the ohmic heating system were performed at three temperatures (105, 125, and 150 degrees C) with residence time at each temperature ranging from 0.84 to 12.0 s. The resulting concentrations of glyoxal (GO), methylglyoxal (MGO), and 3-deoxyglucosone (3-DG) in the PD solutions were measured. None of these GDPs were found in PD fluids treated by ohmic heating at 105 degrees C. The concentration of 3-DG, after a standard sterilization treatment (121 degrees C, 20 or 40 min) was one order of magnitude higher (approximately 140 and 242 microM) than after ohmic heating treatment at 125 degrees C. The results of the present study suggest that this technique can be used to produce solutions with much lower content of GDPs. It also demonstrates the advantage of using the ohmic heating technology as a tool for high temperature short time treatment of PD fluids.     

Single‐Plasmid‐Based System for Efficient Noncanonical Amino Acid Mutagenesis in Cultured Mammalian Cells

We describe a new expression system for efficient non‐canonical amino acid mutagenesis in cultured mammalian cells by using the pyrrolysine tRNA synthetase/tRNA_CUA^Pyl pair. A significant improvement in the incorporation of non‐canonical amino acids into proteins was obtained by combining all the required genetic components into a single and compact vector that can be efficiently delivered to different mammalian cell lines by conventional transfection reagents.     

New Process for Recovery of Zinc Sulfate and Sulfuric Acid from Zinc Electrowinning Bleed Solutions

Acid-base couple extractants extract sulfuric acid and zinc sulfate efficiently, selectively and reversibly. Their properties allowed development of a new, solvent extraction process for treating zinc electrowinning waste streams. In this process, about 95% of the sulfuric acid and 95% of the zinc can be recovered at concentrations high enough to be directly recycled to zinc production. Lime consumption and gypsum formation are substantially reduced. Only one extractant is used in the process, and zinc is recovered as zinc sulfate.     

Anodes for glucose fuel cells based on carbonized nanofibers with embedded carbon nanotubes

Electrodes made of carbonized polyacrylonitryle (cPAN) nanofibers, with and without embedded multiwall carbon nanotubes (MWCNTs) were fabricated by the electrospinning (ES) process and evaluated as anodes in glucose fuel cell (FC) application. The effect of several processing and structural characteristics, such as the presence of MWCNTs, polymer concentration in the ES solution and silver electroless plating on FC performance were measured. The carbon electrodes were successful as anodes showing significant activity even without additional silver catalyst, with noticeable improvement by the incorporation of MWCNTs. The orientation of graphitic layers along the fiber axis and the coherence of layer packing were shown to be important for enhanced electrode activity. The maximal values of open circuit voltage (OCV) and peak of power density (PP_D) of unmetalized electrodes, 0.4 V and 30 μW/cm² respectively, were found to be for composite cPAN/CNT electrode. Electroless silver metallization of the carbon nanofiber electrodes leads to much better FC performance. Maximal values of OCV and PP_D of silvered carbon electrodes were measured to be about 0.9 V and 400 μW/cm², respectively. Thus, carbonized nanofibers with embedded MWCNTs may form a good basis for glucose FC anodes, but better metallization and cell-configuration allowing proper mixing are required.