Structural development of silicated films self-assembled at the air-water interface

The development of structure perpendicular to and in the plane of the interface has been studied for mesoporous silicate films self-assembled at the air/water interface. The use of constrained X-ray and neutron specular reflectometry has enabled a detailed study of the structural development perpendicular to the interface during the pre-growth phase. Off-specular neutron reflectometry and grazing incidence X-ray diffraction has enabled the in-plane structure to be probed with excellent time resolution. The growth mechanism under the surfactant to silicate source ratios used in this work is clearly due to the self-assembly of micellar and molecular species at the air/liquid interface, resulting in the formation of a planar mesoporous film that is tens of microns thick. (C) 2003 Elsevier Science B.V. All rights reserved.

Patterns of variation within self-incompatibility loci

Diverse self-incompatibility (SI) mechanisms permit flowering plants to inhibit fertilization by pollen that express specificities in common with the pistil. Characteristic of at least two model systems is greatly reduced recombination across large genomic tracts surrounding the S-locus, which regulates SI. In three angiosperm families, including the Solanaceae, the gene that controls the expression of gametophytic SI in the pistil encodes a ribonuclease (S-RNase). The gene that controls pollen SI expression is currently unknown, although several candidates have recently been proposed. Although each candidate shows a high level of polymorphism and complete allelic disequilibrium with the S-RNase gene, such properties may merely reflect tight linkage to the S-locus, irrespective of any functional role in SI. We analyzed the magnitude and nature of nucleotide variation, with the objective of distinguishing likely candidates for regulators of SI from other genes embedded in the S-locus region. We studied the S-RNase gene of the Solanaceae and 48A, a candidate for the pollen gene in this system, and we also conducted a parallel analysis of the regulators of sporophytic SI in Brassica, a system in which both the pistil and pollen genes are known. Although the pattern of variation shown by the pollen gene of the Brassica system is consistent with its role as a determinant of pollen specificity, that of 48A departs from expectation. Our analysis further suggests that recombination between 48A and S-RNase may have occurred during the interval spanned by the gene genealogy, another indication that 48A may not regulate SI expression in pollen.

A comparison of the self-association behavior of the plant cyclotides kalata B1 and kalata B2 via analytical ultracentrifugation

The recently discovered cyclotides kalata B1 and kalata B2 are miniproteins containing a head-to-tail cyclized backbone and a cystine knot motif, in which disulfide bonds and the connecting backbone segments form a ring that is penetrated by the third disulfide bond. This arrangement renders the cyclotides extremely stable against thermal and enzymatic decay, making them a possible template onto which functionalities can be grafted.We have compared the hydrodynamic properties of two prototypic cyclotides, kalata B1 and kalata B2, using analytical ultracentrifugation techniques. Direct evidence for oligomerization of kalata B2 was shown by sedimentation velocity experiments in which a method for determining size distribution of polydisperse molecules in solution was employed. The shape of the oligomers appears to be spherical. Both sedimentation velocity and equilibrium experiments indicate that in phosphate buffer kalata B1 exists mainly as a monomer, even at millimolar concentrations. In contrast, at 1.6 mM, kalata B2 exists as an equilibrium mixture of monomer (30%), tetramer (42%), octamer (25%), and possibly a small proportion of higher oligomers. The results from the sedimentation equilibrium experiments show that this self-association is concentration dependent and reversible. We link our findings to the three-dimensional structures of both cyclotides, and propose two putative interaction interfaces on opposite sides of the kalata B2 molecule, one involving a hydrophobic interaction with the Phe(6), and the second involving a charge-charge interaction with the Asp(25) residue. An understanding of the factors affecting solution aggregation is of vital importance for future pharmaceutical application of these molecules.

Matching occupation and self: Does matching theory adequately model children's thinking?

The present exploratory-descriptive cross-national study focused on the career development of 11- to 14-yr.-old children, in particular whether they can match their personal characteristics with their occupational aspirations. Further, the study explored whether their matching may be explained in terms of a fit between person and environment using Holland's theory as an example. Participants included 511 South African and 372 Australian children. Findings relate to two items of the Revised Career Awareness Survey that require children to relate personal-social knowledge to their favorite occupation. Data were analyzed in three stages using descriptive statistics, i.e., mean scores, frequencies, and percentage agreement. The study indicated that children perceived their personal characteristics to be related to their occupational aspirations. However, how this matching takes place is not adequately accounted for in terms of a career theory such as that of Holland.

Self-assembled naphthalenediimide derivative films for light-assisted electrochemical reduction of oxygen

This naphthalene diimide derivative, DC18, forms highly conjugated semiconducting stacked assemblies over electrodes after electrochemical conditioning. These molecular materials are very efficient towards electrochemical photoreduction of oxygen under visible light.

Self-assembled films from WO(3): Electrochromism and lithium ion diffusion

WO(3)/chitosan and WO(3)/chitosan/poly(ethylene oxide) (PEO) films were prepared by the layer-by-layer method. The presence of chitosan enabled PEO to be carried into the self-assembled structure, contributing to an increase in the Li(+) diffusion rate. On the basis of the galvanostatic intermittent titration technique (GITT) and the quadratic logistic equation (QLE), a spectroelectrochemical method was used for determination of the ""optical"" diffusion coefficient (D(op)), enabling analysis of the Li(+) diffusion rate and, consequently, the coloration front rate in these host matrices. The D(op) values within the WO(3)/chitosan/PEO film were significantly higher than those within the WO(3)/chitosan film, mainly for higher values of injected charge. The presence of PEO also ensured larger accessibility to the electroactive sites, in accordance with the method employed here. Hence, this spectroelectrochemical method allowed us to separate the contribution of the diffusion process from the number of accessible electroactive sites in the materials, thereby aiding a better understanding of the useful electrochemical and electrochromic properties of these films for use in electrochromic devices. (C) 2010 Elsevier B.V. All rights reserved.

Spectroelectrochemical Properties and Lithium Ion Storage in Self-Assembled Nanocomposites from TiO(2)

Layer-by-layer (LbL) nanocomposite films from TiO(2) nanoparticles and tungsten-based oxides (WO(x)H(y)), as well as dip-coating films of TiO(2) nano particles, were prepared and investigated by electrochemical techniques under visible light beams, aiming to evaluate the lithium ion storage and chromogenic properties. Atomic force microscopy (AFM) images were obtained for morphological characterization of the Surface of the materials, which have similar roughness. Cyclic voltammetry and chronoamperometry measurements indicated high storage capacity of lithium ions in the LbL nanocomposite compared with the dip-coating film, which was attributed to the faster lithium ion diffusion rate within the self-assembled matrix. On the basis of the data obtained from galvanostatic intermittent titration technique (GITT), the values of lithium ion diffusion coefficient (D(Li)) for TiO(2)/WO(x)H(y) were larger compared with those for TiO(2). The rate of the coloration front in the matrices was investigated using a spectroelectrochemical method based oil GITT, allowing the determination of the ""optical"" diffusion coefficient (D(op)) as a function of the amount of lithium ions previously inserted into the matrices. The Values of D(Li) and D(op) suggested the existence of phases with distinct contribution to lithium ion diffusion rates and electrochromic efficiency. Moreover, these results aided a better understanding of the temporal change of current density and absorbance during the ionic electro-insertion, which is important for the possible application of these materials in lithium ion batteries and electrohromic devices.

The nature of early self-recognition

In studies of mirror-self-recognition subjects are usually surreptitiously marked on their head, and then presented with a mirror. Scores of studies have established that by 18 to 24 months, children investigate their own head upon seeing the mark in the mirror. Scores of papers have debated what this means. Suggestions range from rich interpretations (e.g., the development of self-awareness) to lean accounts (e.g., the development of proprioceptivevisual matching), and include numerous more moderate proposals (e.g., the development of a concept of one's face). In Study 1, 18-24-monthold toddlers were given the standard test and a novel task in which they were marked on their legs rather than on their face. Toddlers performed equivalently on both tasks, suggesting that passing the test does not rely on information specific to facial features. In Study 2, toddlers were surreptitiously slipped into trouser legs that were prefixed to a highchair. Toddlers failed to retrieve the sticker now that their legs looked different from expectations. This finding, together with the findings from a third study which showed that self-recognition in live video feedback develops later than mirror selfrecognition, suggests that performance is not solely the result of proprioceptive-visual matching.

Effects of Self-Assembled Materials Prepared from V(2)O(5) for Lithium Ion Electroinsertion

Self-assembled materials consisting of V(2)O(5), polyallylamine (PAR) and silver nanoparticles (AgNPs) were obtained by the layer-by-layer (LbL) method, aiming at their application as electrodes for lithium-ion batteries and electrochromic devices. The method employed herein allowed for linear growth of visually homogeneous films composed of V(2)O(5), V(2)O(5)/PAH, and V(2)O(5)/PAH/AgNP with 15 bilayers. According to the Fourier transform infrared spectra, interaction between the oxygen atom of the vanadyl group and the amino group should be responsible for the growth of these films. This interaction also enabled establishment of an electrostatic shield between the lithium ions and the sites with higher negative charge, thereby raising the ionic mobility and consequently increasing the energy storage capacity and reducing the response time. According to the site-saturation model and the electrochemical and spectroelectrochemical results, the presence of PAH in the self-assembled host matrix decreased the number of V(2)O(5) electroactive sites. Thus, AgNPs were stabilized in PAR and inserted into the nanoarchitecture, so as to enhance the specific capacity. This should provide new conducting pathways and connect isolated V(2)O(5) particles in the host matrix. Therefore, new nanoarchitectures for specific interactions were formed spontaneously and chosen as examples in this work, aiming to demonstrate the potentiality of the adopted self-assembled method for enhancing the charge transport rate into the host matrices. The obtained materials displayed suitable properties for use as electrodes in lithium batteries and electrochromic devices.

Extra-curricular involvement and self-regulation in children

The research investigated the relationship between extra-curricular involvement (ECI) and self-regulated behaviours in 8 to 9 year old children, and identified sex, location, and socio-economic status (SES) differences in their ECI and self-regulatory behaviours. 550 children from 44 schools in Queensland and New South Wales completed the Child Self-Regulatory Process Inventory and questions about their ECI. Nearly 90 percent of students were involved in at least one extra-curricular activity with the mean number of activities being 1.27. Girls and urban children were significantly more involved in school-based extra- curricular activities than their male and rural counterparts; there were no significant differences among SES groups. Urban children and children in the high SES group reported significantly greater involvement for non-school based activities. For the three self- regulation strategies, girls scored significantly higher than boys. Moreover, children in the high ECI group reported significantly greater use of self-regulation strategies than children in both the low and medium ECI groups. Implications of findings are discussed in light of the need for quality extra-curricular programs, especially in terms of emotional climate and self-directed activities.

Individual differences in motivated social cognition: The case of self-serving information processing

Three experiments examined the hypothesis that people show consistency in motivated social cognitive processing across self-serving domains. Consistent with this hypothesis, Experiment 1 revealed that people who rated a task at which they succeeded as more important than a task at which they failed also cheated on a series of math problems, but only when they could rationalize their cheating as unintentional. Experiment 2 replicated this finding and demonstrated that a self-report measure of self-deception did not predict this rationalized cheating. Experiment 3 replicated Experiments 1 and 2 and ruled out several alternative explanations. These experiments suggest that people who show motivated processing in ego-protective domains also show motivated processing in extrinsic domains. These experiments also introduce a new measurement procedure for differentiating between intentional versus rationalized cheating.