Highly durable fuel cell electrodes based on ionomers dispersed in glycerol.

A major, unprecedented improvement in the durability of polymer electrolyte membrane fuel cells is obtained by tuning the properties of the interface between the catalyst and the ionomer by choosing the appropriate dispersing medium. While a fuel cell cathode prepared from aqueous dispersion showed 90 mV loss at 0.8 A cm(-2) after 30,000 potential cycles (0.6-1.0 V), a fuel cell cathode prepared from glycerol dispersion exhibited only 20 mV loss after 70,000 cycles. This minimum performance loss occurs even though there was an over 80% reduction of electrochemical surface area of the Pt catalyst. These findings indicate that a proper understanding and control of the catalyst-water-ionomer (three-phase) interfaces is even more important for maintaining fuel cell durability in typical electrodes than catalyst agglomeration, and this opens up a novel path for tailoring the functional properties of electrified interfaces.

Room-temperature ferroelectricity in strained SrTiO3.

Systems with a ferroelectric to paraelectric transition in the vicinity of room temperature are useful for devices. Adjusting the ferroelectric transition temperature (T(c)) is traditionally accomplished by chemical substitution-as in Ba(x)Sr(1-x)TiO(3), the material widely investigated for microwave devices in which the dielectric constant (epsilon(r)) at GHz frequencies is tuned by applying a quasi-static electric field. Heterogeneity associated with chemical substitution in such films, however, can broaden this phase transition by hundreds of degrees, which is detrimental to tunability and microwave device performance. An alternative way to adjust T(c) in ferroelectric films is strain. Here we show that epitaxial strain from a newly developed substrate can be harnessed to increase T(c) by hundreds of degrees and produce room-temperature ferroelectricity in strontium titanate, a material that is not normally ferroelectric at any temperature. This strain-induced enhancement in T(c) is the largest ever reported. Spatially resolved images of the local polarization state reveal a uniformity that far exceeds films tailored by chemical substitution. The high epsilon(r) at room temperature in these films (nearly 7,000 at 10 GHz) and its sharp dependence on electric field are promising for device applications.

Strongly enhanced current densities in superconducting coated conductors of YBa2Cu3O7-x + BaZrO3.

There are numerous potential applications for superconducting tapes based on YBa(2)Cu(3)O(7-x) (YBCO) films coated onto metallic substrates. A long-established goal of more than 15 years has been to understand the magnetic-flux pinning mechanisms that allow films to maintain high current densities out to high magnetic fields. In fact, films carry one to two orders of magnitude higher current densities than any other form of the material. For this reason, the idea of further improving pinning has received little attention. Now that commercialization of YBCO-tape conductors is much closer, an important goal for both better performance and lower fabrication costs is to achieve enhanced pinning in a practical way. In this work, we demonstrate a simple and industrially scaleable route that yields a 1.5-5-fold improvement in the in-magnetic-field current densities of conductors that are already of high quality.

Solid-state quantum computer based on scanning tunneling microscopy.

We propose a solid-state nuclear-spin quantum computer based on application of scanning tunneling microscopy (STM) and well-developed silicon technology. It requires the measurement of tunneling-current modulation caused by the Larmor precession of a single electron spin. Our envisioned STM quantum computer would operate at the high magnetic field (approximately 10 T) and at low temperature approximately 1 K.

Direct visualization of gram-negative bacterial lipopolysaccharide self-assembly.

Bacterial lipopolysaccharides (LPS) are outer cell wall components of gram-negative bacteria that may cause septic shock in mammals. The exact morphology of LPS when interacting with macromolecular complexes of the septic shock pathway in blood is still uncertain. Here, the geometry and morphology of hydrated bacterial LPS, dispersed in solution, at and below its the critical aggregate concentration, were directly examined by tapping mode atomic force microscopy (TMAFM) and dynamic light scattering. High-resolution phase-shift TMAFM images of hydrated LPS of Salmonella minnesota Re595, Salmonella typhimurium, and Escherichia coli 0111:B4 adsorbed on mica surfaces unveiled nanosized lipidic particles with a species-specific organization. The complex hydrodynamic geometry exhibited by LPS in dilute suspensions may have consequences for the interpretation of LPS biological activity in the host immune response.

Social cognitions about adult male victims of female sexual assault.

Although men are far less likely than women to be victims of heterosexual assault, such cases have been reported with increasing frequency in recent years. We compared social judgments about male and female victims of heterosexual and homosexual rape and tested hypotheses concerning social cognitions that are assumed to underlie a male rape mythology. In a 2 × 2 × 2 design, 77 male and 89 female subjects made a series of judgments about a sexual assault case in which sex of victim and sex of assailants were manipulated. Consistent with the hypotheses, the male victim of sexual assault by females was judged more likely to have initiated or encouraged the sex acts, and more enjoyment and less stress were attributed to him. This pattern of results was more pronounced among male subjects. The results are discussed in relation to stereotypic beliefs concerning male sex roles, sexual motivation, and sexual functioning that are likely to affect the social cognitions of both observers and male victims of heterosexual assault.

Acid precipitation: natural versus anthropogenic components.

The concentrations of H(+), SO(4)(2-), and NO(3)(-) in the precipitation of eastern North America are greater now than they were historically as a result of fossil-fuel combustion. Because of a lack of data prior to 1950, the absolute increases in the concentrations of these three ions are unknown. This problem can be addressed by comparing the composition of precipitation from areas sensitive to acidic deposition with that of precipitation from remote areas. An analysis of precipitation data indicates that many areas of eastern North America receive precipitation with substantially greater H(+), SO(4)(2-), and NO(3)(-) concentrations than remote areas. For example, SO(4)(2-), the most ecologically significant indicator of change, is enriched 2 to 16 times in eastern North American precipitation relative to its concentration in remote areas.