Observation of Fundamental Mechanisms in Compression-Induced Phase Transformations Using Ultrafast X-ray Diffraction

As theoretically hypothesized for several decades in group IV transition metals, we have discovered a dynamically stabilized body-centered cubic (bcc) intermediate state in Zr under uniaxial loading at sub-nanosecond timescales. Under ultrafast shock wave compression, rather than the transformation from alpha-Zr to the more disordered hex-3 equilibrium omega-Zr phase, in its place we find the formation of a previously unobserved nonequilibrium bcc metastable intermediate. We probe the compression-induced phase transition pathway in zirconium using time-resolved sub-picosecond x-ray diffraction analysis at the Linac Coherent Light Source. We also present molecular dynamics simulations using a potential derived from first-principles methods which independently predict this intermediate phase under ultrafast shock conditions. In contrast with experiments on longer timescale (> 10 ns) where the phase diagram alone is an adequate predictor of the crystalline structure of a material, our recent study highlights the importance of metastability and time dependence in the kinetics of phase transformations

Codependence and conduct disorder: Feminine versus masculine coping responses to abusive parenting practices

This study supported the hypothesis that codependence reflects a stereotypically feminine coping strategy to environmental stressors, while conduct disorder represents an alternate coping response reflecting stereotypically masculine behaviors. High school students ( N = 218; 81% Anglo-American, 8% Asian-American, 5% Hispanic-American) completed measures of femininity/masculinity, codependence, conduct disorder, and unhealthy parenting practices. Multiple regression analyses revealed that codependence is related to parental abuse and femininity ( R = .50). A marginal relationship between codependence and parental alcoholism was mediated by parental abuse, calling into question the validity of the codependence construct. Conduct disorder was related to parental abuse, masculinity, parental alcoholism, and gender ( R = .62). The tendency to label stereotypically feminine coping strategies as pathological, while ignoring a more prevalent and destructive masculine coping strategy is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45612/1/11199_2005_Article_BF01548255.pd

Ethnic Identity of Older Chinese in Canada

In Canada’s multicultural society, ethnic identity is important to the elderly and can influence areas such as access to services, health promotion and care. Often, the complex nature of ethnic identity is underestimated when looking at cultural groups. This study aims to: (a) validate the factor structure of a Chinese ethnic identity measure for older Chinese in Canada, (b) examine the level of ethnic identity of the participants, and (c) examine the correlates of ethnic identity in these older individuals. Using data from a large, national research project on the elderly Chinese in Canada, this study analyzed the results gathered from a total of 2,272 participants. Principal component analysis, maximum-likelihood confirmatory factor analysis, and multiple regression analysis were performed. The results indicated that ethnic identity of the older Chinese is a multi-dimensional construct made up of three factors: (a) culture related activities, (b) community ties, (c) linkage with country of origin, and (d) cultural identification. The findings have provided a better understanding of how ethnic identity can be measured among the aging Chinese population in Canada

Photochemical Charge Separation in Poly(3-hexylthiophene) (P3HT) Films Observed with Surface Photovoltage Spectroscopy

Surface photovoltage spectroscopy (SPS) was used to probe photon induced charge separation in thin films of regioregular and regiorandom poly(3-hexylthiophene) (P3HT) as a function of excitation energy. Both positive and negative photovoltage signals were observed under sub-band-gap (<2.0 eV) and super-band-gap (>2.0 eV) excitation of the polymer. The dependence of the spectra on substrate work function, thermal annealing, film thickness, and illumination intensity was investigated, allowing the identification of interface, charge transfer (CT), and band-gap states in the amorphous and crystalline regions of the polymer films. The ability to probe these states in polymer films will aid the development and optimization of organic electronic devices such as photovoltaics (OPVs), light-emitting diodes (OLEDs), and field effect transistors (OFETs). The direction and size of the observed photovoltage features can be explained using the depleted semiconductor model. © 2013 American Chemical Society

P3HT-Based Solar Cells: Structural Properties and Photovoltaic Performance

Each year we are bombarded with B.Sc. and Ph.D. applications from students that want to improve the world. They have learned that their future depends on changing the type of fuel we use and that solar energy is our future. The hope and energy of these young people will transform future energy technologies, but it will not happen quickly. Organic photovoltaic devices are easy to sketch, but the materials, processing steps, and ways of measuring the properties of the materials are very complicated. It is not trivial to make a systematic measurement that will change the way other research groups think or practice. In approaching this chapter, we thought about what a new researcher would need to know about organic photovoltaic devices and materials in order to have a good start in the subject. Then, we simplified that to focus on what a new researcher would need to know about poly-3-hexylthiophene:phenyl-C61-butyric acid methyl ester blends (P3HT: PCBM) to make research progress with these materials. This chapter is by no means authoritative or a compendium of all things on P3HT:PCBM. We have selected to explain how the sample fabrication techniques lead to control of morphology and structural features and how these morphological features have specific optical and electronic consequences for organic photovoltaic device applications

Properties of a Thermoelectric Cell

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70757/2/JAPIAU-29-11-1611-1.pd