The chemistry of Al transformation has been well documented, though little is known about the mechanisms of structural perturbation of Al precipitates by carbonates at a molecular level. The purpose of the present study was to investigate the structural perturbation of Al precipitates formed under the influence of carbonates. Initial carbonate/Al molar ratios (MRs) used were 0, 0.1, and 0.5 after aging for 32 days, then the samples were analyzed by X-ray absorption near edge structure spectroscopy (XANES), X-ray diffraction (XRD), Fourier-transform infrared absorption spectroscopy (FTIR), and chemical analysis. The XRD data were in accord with the FTIR results, which revealed that as the carbonate/Al MR was increased from 0 to 0.1, carbonate preferentially retarded the formation of gibbsite and had relatively little effect on the formation of bayerite. As the carbonate/Al MR was increased to 0.5, however, the crystallization of both gibbsite and bayerite was completely inhibited. The impact of carbonate on the nature of Al precipitates was also evident in the increase of adsorbed water and inorganic C contents with increasing carbonate/Al MR. The Al K- and L- edge XANES data provide the first evidence illustrating the change in the coordination number of Al from 6-fold to mixed 6- and 4-fold coordination in the structural network of short-range ordered (SRO) Al precipitates formed under the increasing perturbation of carbonate. The fluorescence yield spectra of the O K-edge show that the intensity of the peak at 534.5 eV assigned to σ* transitions of Al-O and O-H bonding decreased with increasing carbonate/Al MR. The XANES data, along with the evidence from XRD, FTIR, and chemical analysis showed clearly that carbonate caused the alteration of the coordination nature of the Al-O bonding through perturbation of the atomic bonding and structural configuration of Al hydroxides by complexation with Al in the SRO network of Al precipitates. The surface reactivity of an Al-O bond is related to its covalency and coordination geometry. The present findings were, therefore, of fundamental significance in understanding the low-temperature geochemistry of Al and its impacts on the transformation, transport, and fate of nutrients and pollutants in the ecosystem.

Most research on the causes of women's underrepresentation examines one of two stages of the political pipeline: the development of nascent political ambition or specific aspects of the campaign and election process. In this article, we make a different kind of contribution. We build on the growing literature on gender, psychology, and representation to provide an analysis of what kinds of men and women make it through the political pipeline at each stage. This allows us to draw some conclusions about the ways in which the overall process is similar and different for women and men. Using surveys of the general U.S. population (N = 1,939) and elected municipal officials such as mayors and city councilors (N = 2,354) that measure the distribution of Big Five personality traits, we find that roughly the same types of men and women have nascent political ambition; there is just an intercept shift for sex. In contrast, male and female elected officials have different personality profiles. These differences do not reflect underlying distributions in the general population or the population of political aspirants. In short, our data suggest that socialization into political ambition is similar for men and women, but campaign and election processes are not.

In the atmosphere of the Sun, most spectral lines are broadened by collisions between the radiating atom and neutral particles. The interaction between two atoms is usually represented by the multipole expansion of the total interaction potential. For two neutral atoms, the first non-zero term in this expansion arises from induced dipole-induced dipole forces and is proportional to r-6. Most calculations of broadening due to neutral atoms have assumed this van der Waals interaction, V(r) = —C6 r-6, between the atoms. Such an assumption is only valid if the interatomic separation is much greater than the sum of the radii of the two atoms so that no overlap occurs and only the leading term of the multipole expansion need be considered. However, in fitting the wings of solar line profiles, O’Mara found that the value of the van der Waals constant, C6, had to be increased by up to a factor of ten in order to obtain agreement between theoretical and observed profiles.

The study of line-broadening mechanisms puts at our disposal an extremely useful tool for the investigation of physical conditions in plasmas, both stellar and laboratory.

We enhance the theoretical precision of cultural intelligence (CQ: capability to function effectively in culturally diverse settings) by developing and testing a model that posits differential relationships between the four CQ, dimensions (metacognitive, cognitive, motivational and behavioural) and three intercultural effectiveness outcomes (cultural judgment and decision making, cultural adaptation and task performance in culturally diverse settings). Before testing the model, we describe development and cross-validation (N = 1,360) of the multidimensional cultural intelligence scale (CQS) across samples, time and country. We then describe three substantive studies (N = 794) in field and educational development settings across two national contexts, the USA and Singapore. The results demonstrate a consistent pattern of relationships where metacognitive CQ and cognitive CQ predicted cultural judgment and decision making; motivational CQ and behavioural CQ predicted cultural adaptation; and metacognitive CQ and behavioural CQ predicted task performance. We discuss theoretical and practical implications of our model and findings.

Chemical nano-tomography of microbial cells in their natural, hydrated state provides direct evidence of metabolic and chemical processes. Cells of the nitrate-reducing Acidovorax sp. strain BoFeN1 were cultured in the presence of ferrous iron. Bacterial reduction of nitrate causes precipitation of Fe(III)-(oxyhydr)oxides in the periplasm and in direct vicinity of the cells. Nanoliter aliquots of cell-suspension were injected into custom-designed sample holders wherein polyimide membranes collapse around the cells by capillary forces. The immobilized, hydrated cells were analyzed by synchrotron-based scanning transmission X-ray microscopy in combination with angle-scan tomography. This approach provides three-dimensional (3D) maps of the chemical species in the sample by employing their intrinsic near-edge X-ray absorption properties. The cells were scanned through the focus of a monochromatic soft X-ray beam at different, chemically specific X-ray energies to acquire projection images of their corresponding X-ray absorbance. Based on these images, chemical composition maps were then calculated. Acquiring projections at different tilt angles allowed for 3D reconstruction of the chemical composition. Our approach allows for 3D chemical mapping of hydrated samples and thus provides direct evidence for the localization of metabolic and chemical processes in situ.

In the first of two experiments designed to investigate perceived cognitive abilities of young and old targets, 80 female undergraduates estimated the performance of either a young or an old target on several subtests from the Wechsler Adult Intelligence Scale (WAIS; Wechsler, 1955). Experiment 2, with 120 respondents, extended Experiment 1 to include respondent sex and target sex variables, and additional WAIS subtests. The results of the two experiments suggest a highly differentiated view of cognitive abilities. On subtests related primarily to memory and psychomotor speed, the old targets were seen as less cognitively able than the young targets. On a subtest assessing practical judgment and common sense old targets were seen as superior to young targets. On subtests assessing computational abilities and logical abstractive thinking no reliable target age differences were found. Neither target sex nor respondent sex played a substantial role in target age perceptions. Compared to available norms estimates xvere unrealistically generous, particularly in the case of older adults. However the pattern of estimates across cognitive abilities reflected, to a substantial degree, the age-related differences in the norms.

Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005

Quench-condensed films of simple superconductors can be deposited with a morphology which is either granular (grain sizes on the scale of tens of angstroms) or homogeneous. Transport and tunneling studies of the normal and superconducting states of these films as a function of sheet resistance have revealed profound differences between them. In uniform films Tc. and the energy gap decrease continuously with decreasing film thickness. Superconductivity is destroyed by the reduction of the amplitude of the order parameter. In granular films, the grains are sufficiently large to support superconductivity in each grain. Long range phase coherence is destroyed by intergrain phase coherence breaking.

We have prepared low leakage tunnel junctions on epitaxial YBa2Cu3O7 (YBCO) films grown on SrTiO3(001) by evaporating Pb counterelectrodes onto chemically etched YBCO surfaces. Structure in the voltage dependence of the tunneling conductance is reproducible and strongly resembles what has been obtained in similarly etched junctions on YBCO single crystals.

We have fabricated tunnel junctions between chemically etched single crystals of YBa2Cu3O7-δ and evaporated metal counterelectrodes which exhibit reproducible characteristics. Above the bulk critical temperature of YBa2Cu3O7-δ, Tc, the conductance, G(V), has a linear dependence with voltage and has some asymmetry. Below Tc, additional structure associated with the superconductivity appears in G(V). At T>>Tc there is a reproducible finite zero bias conductance.

Ion implantation is widely used for doping semiconductors at low concentration, but, with the advent of a new generation of high current implanters, synthesizing new materials rather that simply doping them has become feasible. This technique has been successfully applied to fabricating silicon-on-insulator (SOI) structures with oxygen and nitrogen for several years. Since we are interested in understanding the mechanisms of formation of these layers, we have concentrated on sub-stoichiometric implantation doses of oxygen where it is easier to observe the coalescing layer. In order to determine whether this process of compound formation is more general, our studies were expanded to include implantation of the transition metals. Here, elevated substrate temperatures are necessary to minimize Si surface damage. The resulting disilicide layers are of remarkably high quality: they are single crystals in registry with the silicon wafer and they have better residual resistivities than comparable UHV-reacted silicides.

We have explored the effects of ion beam irradiation on the electrical and structural properties of superconducting thin films of YBa2Cu3O7-δ. Damage created by nuclear energy loss processes degrades the superconducting transitions. In general, the onset temperatures do not vary significantly with ion fluence, but the transition widths broaden until the resistance no longer reaches zero. This behavior is strikingly similar to that observed in granular superconducting films where islands of superconductor are progressively decoupled from each other, destroying the phase coherence. Data from resistance measurements as well as from Rutherford Backscattering and channeling measurements suggest that ion bombardment is not changing the volume fraction of superconducting material substantially.

Ion implantation is widely used for doping semiconductors at low concentration, but, with the advent of a new generation of high current implanters, synthesizing new materials rather that simply doping them has become feasible. This technique has been successfully applied to fabricating silicon-on-insulator (SOI) structures with oxygen and nitrogen for several years. Since we are interested in understanding the mechanisms of formation of these layers, we have concentrated on sub-stoichiometric implantation doses of oxygen where it is easier to observe the coalescing layer. In order to determine whether this process of compound formation is more general, our studies were expanded to include implantation of the transition metals. Here, elevated substrate temperatures are necessary to minimize Si surface damage. The resulting disilicide layers are of remarkably high quality: they are single crystals in registry with the silicon wafer and they have better residual resistivities than comparable UHV-reacted suicides.