Sulphur doping induced band gap narrowing and enhancement of green emission in ZnO nanorods

Journal of Materials Science: Materials in Electronics - Sulphur doped ZnO nanostructures were synthesized by a cost-effective wet chemical method. Structural characterization indicated that the...     

Effect of compressive stress inducing a band gap narrowing on the photoinduced activities of sol-gel TiO2 films

TiO₂ thin films grown on different kinds of substrates were obtained by sol-gel process. X-ray diffraction revealed that the TiO₂ lattice parameter c decreased continuously, indicating a continuous variation in the compressive stress, a negligible compressive stress of the film grown onto Soda-Lime Glass (SLG), medium compressive stress of the film grown onto BoroSilicate Glass (BSG) and large compressive stress of the film deposited onto the Quartz Substrate (QS). UV-Vis absorbance spectra exhibited a red-shift of the absorbance edge of the TiO₂ films suggesting a lowering of the band gap, which is a direct consequence of the increase of the compressive stress. X-ray photoelectron spectroscopy revealed that the surface composition of titania films was similar except for sodium-ion concentration. The rate observed during the photo-oxydation of the stearic acid on TiO₂/QS was twice as high as that of TiO₂/BSG and about 1000 times superior to that of TiO₂/SLG. The photoinduced wettability shows an identical dependence of the compressive stress. According to these results, the compressive stress could be used to tune the band gap of the titanium oxide in order to enhance the photoinduced properties.     

An investigation of the maximum experimental safe gap anomaly

The “safe gap” is defined as the maximum gap between two close-fitting, flat, machined metal surfaces that will just prevent an explosion within a vessel from producing a propagating combustion wave in the gases that surround the vessel. At present three distinctly different apparatuses are used throughout the world to determine experimentally the maximum safe gap for different combustible gases and vapors. Unfortunately, the maximum safe gap thus determined sometimes differs widely from vessel to vessel. This report investigates the nature of the processes by which the explosion is transmitted to the surrounding media, paying particular attention to the differences from apparatus to apparatus. It is found that the time constants associated with the combustion process and with vessel exhausting are markedly different for the different vessels and that the pressure levels developed inside a vessel during the test also vary markedly from vessel to vessel. Based on these observations, it is recommended that a more thorough theoretical and experimental investigation of the safe gap testing procedures and vessel design be made as the basis for a proper design for adequate safe gap testing of all combustible vapors and gases.     

Effects of major-road vehicle speed and driver age and gender on left-turn gap acceptance

Because the driver's gap-acceptance maneuver is a complex and risky driving behavior, it is a highly concerned topic for traffic safety and operation. Previous studies have mainly focused on the driver's gap acceptance decision itself but did not pay attention to the maneuver process and driving behaviors. Using a driving simulator experiment for left-turn gap acceptance at a stop-controlled intersection, this study evaluated the effects of major traffic speed and driver age and gender on gap acceptance behaviors. The experiment results illustrate relationships among drivers' left-turn gap decision, driver's acceleration rate, steering action, and the influence of the gap-acceptance maneuver on the vehicles in the major traffic stream. The experiment results identified an association between high crash risk and high traffic speed at stop-controlled intersections. The older drivers, especially older female drivers, displayed a conservative driving attitude as a compensation for reduced driving ability, but also showed to be the most vulnerable group for the relatively complex driving maneuvers.     

Band gap narrowing and electrical properties of (1-x)BaTiO3-xSrFe0.5Nb0.5O3 lead-free ceramics

Journal of Materials Science: Materials in Electronics - The composite materials in the form of (1-x)BaTiO3-xSrFe0.5Nb0.5O3((1-x)BT-xSFN) are synthesized via the solid-state reaction route....     

An investigation of gender differences in the components influencing the difficulty of spatial ability items

This study examines the role that gender differences play in the determination of the components influencing the difficulty of spatial ability items. Considerable research has examined the role of gender differences in spatial abilities, with sometimes contradictory findings. In general, the findings show that males tend to outperform females on spatial ability items. Other research has focused on determining the components of items that contribute to their difficulty. This research has usually been based on mixed-gender populations, however. The present study attempts to determine if gender influences the extent to which different components contribute to the difficulty of items. The results indicate that component difficulties show very little variation across gender. This finding supports the notion that any differences in raw scores observed for males and females are not due to differences in the manner in which males and females process spatial information or solve spatial ability items.     

An examination of gender differences in traffic accident risk perception.

Excessively optimistic judgements of driving competency and accident risk have often been implicated in the disproportionate involvement of young males in traffic crashes. In this study, young male and female drivers (ages 18-24) were asked to judge their relative driving safety, skill, and accident likelihood. Comparisons were made using both peers and the average motorist as referent groups. Subjects then rated 15 risky driving behaviors on four dimensions: frequency in everyday driving, seriousness, accident potential, and apprehension likelihood. Self-report driving experience/history data were also collected. Substantial optimism was evident in both sexes, but males tended to be more optimistic, particularly when judging their driving skill. Males were equally optimistic with respect to the two referent groups; females tended to be less optimistic when making comparisons to the average motorist. Males and females held similar perceptions concerning the frequency and accident likelihood of the risky behaviors, but males perceived the behaviors as generally less serious and less likely to results in accidents. Regression analyses showed that considerably more variance in optimism could be explained for males than females. Driving record was the single best predictor of perceived safety; its role, however, was diminished for perceived skill and subjectively estimated accident likelihood.     

Web links and gender in science: An exploratory analysis

Gender inequalities are prevalent in science despite many initiatives to try to eradicate them. Given the deep-rooted and complex nature of these inequalities there is a continuing need for research into their causes and manifestations. This study analyses one aspect of web communication, hyperlinks, to explore whether they are a potential source of insights into gender differences in this important scientific communication medium. A study of links to life sciences research groups in nine European found little evidence of gender differences, except in Germany. As a consequence, it is argued that hyperlinks are not a promising source of quantitative information about gender differences in communication strategies or online visibility, at least for senior researchers or research groups.     

Spectral narrowing phenomena in the emission from a conjugated polymer

We report a study of the morphology dependent emission properties of a liquid crystalline polyfluorene in solid thin films. Spectral narrowing (SN) is observed in spin coated films, but after thermal treatment of the same films the SN is no longer observed. For films which are spin coated on a rubbed polyimide alignment layer, the situation is different. There is then no influence of thermal treatment on the observation of SN. However, specific combinations of the pump polarization direction, film alignment direction and the long axis of the rectangular excitation area now play an important role. The spectral location of SN peaks also varies with film morphology and for different regions of the same sample. The occurrence of SN is strongly dependent on film morphology and the excitation configuration.     

An electroacoustic wave in a gap between piezoelectrics undergoing oscillatory displacement

The variation of electroacoustic-wave velocity in a vacuum gap of piezoelectric crystals under the action of homogeneous oscillatory displacement of one of the crystals along the gap boundary is considered.     

Characteristics of DUI offenders convicted in wet, dry, and moist counties

Although several studies have examined the effectiveness of local alcohol sales policies on reducing the incidence of driving under the influence (DUI), less is known about whether characteristics of DUI offenders convicted in alcohol-restricted areas differ from those convicted in areas where alcohol is more readily available. A total of 21,647 DUI assessment records were divided into four groups based on the alcohol sales policy of the county of conviction and were compared. DUI offenders convicted in counties that limit or ban the sale of alcohol were more likely to be male, have more drug problems, meet DSM-IV-TR substance abuse or dependence criteria, and have multiple DUI convictions. Implications for practitioners and policy makers are discussed.     

An evaluation of the titanium sublimation pump

Experiments have been carried out to investigate the basic characteristics of the titanium sublimator vacuum pump. For this work an apparatus has been specially designed to enable the molecular ‘sticking coefficient’ to be measured over a range from in excess of 0.99 to below 0.01. Results show that for the chemically active gases such as oxygen and carbon monoxide virtually all molecules striking a clean film, stick on their first impact. This has been observed over the temperature range 77 to 373 K. Nitrogen and hydrogen show a more complex behaviour, their sticking characteristics being more dependent upon impurities in the film and also on the temperature of the substrate, both during film deposition and gas sorption.The use of a mass spectrometer for all pressure measurements has shown that the adsorption of the active gas causes considerable desorption of molecules already held on the film surface. Methane is a good example, this gas being desorbed by all the others investigated. In a comparison of published results it is suggested that some of the considerable disagreements can be explained by replacement. This is a process which cannot fully be taken into account in experiments where the measurements of the partial pressures of the gas components in the system are not made.     

An improved measurement of the absolute efficiency of magnetic heads by saturating the gap field

A method that can be used to measure the absolute efficiency of narrow-track magnetic heads such as video heads (gap area <10³(μm)²) is described. The method is based on the detection of the gap flux by means of a subsidiary coil wound around the gap. Usually a considerable amount of leakage flux is detected together with the gap flux, which obviously would impair the accuracy of the results. Therefore, measures were taken by raising the current through the main coil progressively and thus determining the saturation value of the gap flux. In this way it was possible to distinguish between the gap flux and leakage flux components. With this method the efficiency can be measured with an accuracy of better than 10 percent at frequencies of up to 10 MHz. As a second result, the gap area can thus be determined magnetically as well. A comparison of the magnetic and optical gap area offers a check on the reliability of the efficiency measurement. The merits of this measuring method are discussed with the aid of results obtained for a typical ferrite video head.     

波束锐化技术在多波束测深声呐中的应用

针对常规波束形成器的分辨性能和旁瓣性能间的矛盾,研究了超波束形成器的波束特征以及空间分辨性能。通过计算机仿真验证了加权超波束形成器既有较高的空间分辨力,又有良好的旁瓣特性。通过对外场实验数据的处理,验证了该算法对于多波束测深声呐测量结果中存在的"隧道效应"假象具有明显的抑制作用。针对算法实现结构进行了优化,进一步减小了算法复杂度。利用DSP进行了算法实现,算法具有较好的实时性和工程实用性。     

Attitudes do matter: The role of attitudes and personality in DUI offenders

Several studies have related personality variables with antisocial behavior. Among antisocial behaviors, driving under the influence (DUI) has received growing attention in recent years, particularly in relation to the role of personality. However, it has been shown that personality alone is not sufficient to accurately predict DUI. As a result, there is growing interest in identifying other types of individual differences that might predict this behavior better, such as attitudinal variables. The aim of this study was to examine differences in personality dimensions and attitudes between a group of DUI offenders and a comparison group. Ninety-eight subjects were assessed: 51 subjects who had been convicted of a DUI offense following a diversion program, and 47 drivers without criminal records. Personality was measured with the NEO-Five Factor Inventory (NEO-FFI) and antisocial attitudes were assessed with the Jesness Inventory-Revised. Results indicated that offenders were more prone to show antisocial attitudes (p < .001) than comparisons. In terms of personality, there were no significant differences between the two groups. These findings suggest that attitudes may be useful predictors of DUI and should be taken into account in interventions designed to avoid recidivism.     

The impact of remedial intervention on 3-year recidivism among first-time DUI offenders in Mississippi

This study examines the impact of the Mississippi Alcohol Safety Education Program (MASEP), a court-mandated intervention program, on 3-year recidivism rates among first-time DUI offenders (i.e. those convicted of a first offense for driving under the influence of alcohol or another drug). It also examines whether a new version of the curriculum that incorporates activities to enhance motivation for change further ameliorates recidivism. Cox proportional hazard regression models are used to compare recidivism rates among DUI offenders who completed MASEP with those who did not complete or who failed to enroll in the program. Recidivism rates were also compared for MASEP participants across time periods during which curriculum revisions were introduced. The hazard of recidivism was lower for individuals who completed the program than for individuals who did not complete or did not enroll in the program. Recidivism rates were further reduced following the introduction of curriculum revisions. Attendance of court-mandated remedial intervention programs lower subsequent DUI arrests and program content is associated with lower rates.     

Spectral narrowing of self-trapped exciton emission in anatase thin films

Self-trapped excition (STE) emission of TiO₂ (anatase) thin films grown by atomic layer deposition technique on single crystal α-Al₂O₃ (0 1 2) substrates were studied at temperatures 5–120 K. An in-plane preferential orientation of anatase crystallites was detected in the films by using the dependence of the emission polarisation on the observation angle. The STE emission recorded in the direction perpendicular to the film surface had a wide spectrum with the maximum at approximately 2.3 eV. The spectrum recorded from a cleaved edge in the direction nearly parallel to the film surface, showed two sharp peaks (spectral width as low as 0.03 eV) on the top of the broad STE emission band. The beam divergence determined at the wavelengths of these peaks was 6–10°. The effect was interpreted as a constructive interference of the emission leaving the film at the angle that is close to the angle of total internal reflection.     

Effect of gap anisotropy in superconductors containing paramagnetic impurities with local states within the gap

The Shiba model for the paramagnetic impurities in a superconductor has been generalized to include the effect of gap anisotropy. The calculated properties are the transition temperatureT _c and the specific heat jump atT _c. The changes brought in these properties by anisotropy are significant.Work supported in part by the Natural Sciences and Engineering Research Council of Canada.