Room temperature ionic liquids in electrosynthesis and spectroelectrochemical characterization of poly(para-phenylene)

Room temperature ionic liquids (RTILs) were used in electrochemical polymerization and in doping studies (oxidation and reduction) of poly(para-phenylene) (PPP). Cyclic voltammetry was used simultaneously with Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy. Electropolymerization and doping of PPP were done by potential scanning in acetonitrile (ACN + 0.1 M TBAPF₆), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF₆]) and butylmethylpyrrolidinium bis (trifluoromethylsulfonyl) imide ([BMP][Tf₂N]). The cyclic voltammograms recorded during polymerization of the PPP film indicate that the best film growth was achieved in [BMIM][PF₆]. The films made in [BMP][Tf₂N] were more stable than films made in ACN (0.1 M TBAPF₆). Results from p-doping studies show that doping can be made at higher potentials in RTILs than in ACN (0.1 M TBAPF₆). It was also found that n-doping can be performed in RTILs at higher negative potentials (−2.2 V) than in ACN (0.1 M TBAPF₆) (−1.8 V). The best n-doping response was achieved in [BMP][Tf₂N]. Also, n-doping in [BMIM][PF₆] was better than in ACN (0.1 M TBAPF₆). The in situ ATR-FTIR spectroscopy was used to study p- and n-doping of PPP films. During both p- and n-doping the spectra indicated formation of infrared active vibration bands (IRAV) in the wavenumber region 1600-800 cm⁻¹. The obtained IRAV bands correlate to the theoretical modes calculated by Zerbi and co-workers according to the effective conjugation coordinate theory (ECC). All these results indicate that RTILs are good solvents in spectroscopic and electrochemical studies of conducting polymers.     

Irreversibility of solidification and of a cyclic solidification and melting process

The specific irreversibility of solidification and of cyclic solidification–melting process was considered on a general level. The variables affecting the irreversibility most are the Biot number, the dimensionless interfacial speed during recalescense and the extent of supercooling. The process path involving supercooling can become less irreversible than the path where phase transition completely happens in an equilibrium state if a thermal conductivity ratio between solid and liquid phases is sufficiently below unity. A finite maximum and a non-zero minimum value of irreversibility can be detected. These extreme values are independent of the geometrical shape of the substance.     

On experimental characterization of polarization fluctuation dynamics in random optical beams

Polarization correlation functions that characterize the rate of change of the instantaneous polarization state of an arbitrary fluctuating electromagnetic beam were recently introduced. In this work, we describe techniques that enable the measurement of these functions leading to the determination of the so-called polarization time of a random field.     

Roll-to-roll printed resistive WORM memory on a flexible substrate

The fabrication process and the operation characteristics of a fully roll-to-roll printed resistive write-once-read-many memory on a flexible substrate are presented. The low-voltage (<10 V) write operation of the memories from a high resistivity '0' state to a low resistivity '1' state is based on the rapid electrical sintering of bits containing silver nanoparticles. The bit ink is formulated by mixing two commercially available silver nanoparticle inks in order to tune the initial square resistance of the bits and to create a self-organized network of percolating paths. The electrical performance of the memories, including read and write characteristics, is described and the long-term stability of the less stable '0' state is studied in different environmental conditions. The memories can find use in low-cost mass printing applications.     

Synthesis and properties of β type Bi(III)2?2xDy(II)2xO3 ? xx solid solution

In the present work, tetragonal β type Bi(III)_{2 − 2x}Dy(II)_2xO_{3 − x}■_x (■:,empty oxygen site) solid solutions have been synthesized in the ranges 0.06 ≤ x ≤ 0.08 at 750°C and 0.05 ≤ x ≤ 0.09 at 800°C by doping small amounts of Dy₂O₃ into monoclinic α -Bi₂O₃. X-ray powder diffraction (XRD) has been used for characterisation of the doped Dy₂O₃ powders as well as for calculation of the unit cell parameters. The polymorphic phase transitions, crystallographic properties, particle sizes, the scanning electron microscope (SEM) microprobe analysis and Dy₂O₃ content dependence of the lattice parameters of the observed β-phase has been reported. The obtained solid solutions had nonstoichiometric character and nonstoichiometry increases with the increasing amount of Dy₂O₃ addition. The experimental results suggested that oxygen vacancies are present in the crystal structure of Dy₂O₃ doped β type solid solutions.     

The influence of surfactant properties on critical supersaturations of cloud condensation nuclei

Due to the complex nature of atmospheric surfactants, their effect on cloud droplet formation is still quite unknown. Most of the earlier studies of surface tension effects on cloud formation have been done either with model compounds or by neglecting the correct thermodynamic approach thereby giving no general idea of how the partitioning of surfactant between the droplet interior and the surface layer affects droplet growth. The neglect of partitioning leads to overestimated decrease in surface tension as well as to enhanced solute effect. Here, we study the extent to which surfactant partitioning affects critical supersaturation with different types of surfactants. The idea is to systematically vary the surface tension parameters that ultimately control how the surfactant is distributed between the bulk and the surface of the droplet, and to compare the critical supersaturations calculated with and without account of the partitioning. This study shows the importance of correct thermodynamical approach to partitioning with an example of three different classes of compounds found in atmospheric aerosols.     

Expectations in Water-right Prices

Water markets are increasingly being used and promoted as an economically efficient means to transfer water rights. Knowledge of water-right price determinants and trends is important in developing markets, and in evaluating the comparative benefits and costs of water supply alternatives. Potential determinants of homogeneous water-right prices are identified, and a two-equation model based on rational expectations theory is developed. The model is tested using empirical evidence from the established market for Colorado-Big Thompson water rights. The model results support observations that returns to water in irrigation do not adequately explain the level of water-right prices. Socioeconomic and speculative factors are found to explain successfully the variations in historical prices, and appear to play a substantial role in water-right price formation. These findings have important implications in assessing the benefits of proposed water-transfer policies.     

Clinico-morphological manifestations of genital tuberculosis in women

No previous studies have examined the influences of cultural background on the provision of contraceptive services to females under 16 years of age. A research project was undertaken to investigate any differences between general practitioners trained in the United Kingdom and those trained in the Indian sub-continent in relation to contraceptive service provision to females under 16 years of age. A self-completion postal questionnaire survey was distributed to 230 unrestricted principal general practitioners across Scotland. Subjects were identified from the Medical Register. Half of the sample consisted of all those working in Scotland who had been trained in the Indian sub-continent. The other half were a comparable group that had been trained in the United Kingdom and were selected by quasi-random quota sampling. The response rate was 57 per cent (131/230). General practitioners in the study who had trained in the Indian sub-continent were found to be significantly less likely to provide contraceptive services to a female under 16 years of age than those who had trained in the United Kingdom. Cultural background may be influential in general practitioner provision of contraceptive services to females below the legal age of consent for sexual intercourse. In order to obtain more conclusive evidence a larger study is necessary. Such investigations must be undertaken with appropriate sensitivity and social awareness.     

Transmit Diversity in the WCDMA System

This document presents the transmit diversityconcept adopted for the FDD mode of the thirdgenerationWCDMA system in ETSI in 1998. The open-loop mode isbased on the space-time block code attaining full diversity order with two transmit antennas.Different feedback modes are specified. They all utilizeterminal measurements in controlling the transmitweighting in the transmit antennas. The concept is described in detail for two transmit antennas.It is shown that very limited feedback from the terminalto the base, as defined for the FDD mode, can increasedownlink performance significantly when compared to single-antenna transmission.     

A QCIF Resolution Binary I/O CNN-UM Chip

In this paper is reported a Cellular Nonlinear Network Universal Machine realization where there are 176 × 144 active cells. The size of the network is the standardized QCIF video image format and the design is aimed to be used in segmenting video images in future video applications requiring very low bit-rate for image transmission. The achieved cell density is 3000 cells/mm² with a 0.25 micron standard digital CMOS process. Different building blocks inside the cell are given in detail and also the other implemented circuitry is thoroughly discussed. The physical realization of the design is also reported.