Electrical Characterization of Individual Cesium Lead Halide Perovskite Nanowires Using Conductive AFM

Perovskite nanostructures have attracted much attention in recent years due to their suitability for a variety of applications such as photovoltaics, light-emitting diodes (LEDs), nanometer-size lasing, and more. These uses rely on the conductive properties of these nanostructures. However, electrical characterization of individual, thin perovskite nanowires has not yet been reported. Here, conductive atomic force microscopy characterization of individual cesium lead halide nanowires is presented. Clear differences are observed in the conductivity of nanowires containing only bromide and nanowires containing a mixture of bromide and iodide. The differences are attributed to a higher density of crystalline defects, deeper trap states, and higher inherent conductivity for nanowires with mixed bromide–iodide content.     

A new sustainable hydrogen clean energy paradigm

We analyze the feasibility of a novel, hydrogen fuel cell electric generator to provide power with zero noise and emissions for myriad ground based applications. The hydrogen fuel cell electric generator utilizes a novel, scalable apparatus that safely generates hydrogen (H₂) on demand according to a novel method, using a controlled chemical reaction between water (H₂O) and sodium (Na) metal that yields hydrogen gas of sufficient purity for direct use in fuel cells without risk of contaminating sensitive catalysts. The sodium hydroxide (NaOH) byproduct of the hydrogen producing reaction, is collected within the apparatus for later reprocessing by electrolysis, to recover the Na reactant. The detailed analysis shows that the novel, hydrogen fuel cell electric generator will be capable of meeting the clean power requirements for residential and commercial buildings including single family homes and light commercial establishments under a wide range of geographic and climatic conditions.     

Functional Peptide Monolayers at Interfaces

Amphiphilic peptides can be designed to form ordered supramolecular structures at hydrophilic-hydrophobic interfaces. These systems rely on the ability of peptides to fold into certain secondary structures at interfaces. This review focuses on the design of amphiphilic β-sheet peptide assemblies in monolayers at interfaces, and their relevance to inducing mineralization and interactions with specific ions. In addition, the review discusses recent studies demonstrating the applicability of designed amphiphilic β-sheet peptides to detection of specific small molecules and to elucidating intermolecular interactions relevant to drug delivery and enzyme catalysis systems.     

Deceived and distorted: Game outcome retrospectively determines the reported time of action.

Previous work suggested the association between intentionality and the reported time of action was exclusive, with intentionality as the primary facilitator to the mental time compression between the reported time of action and its effect (Haggard, Clark, & Kalogeras, 2002). In three experiments, we examined whether mental time compression could also be observed in an unintended action. Participants performed an externally cued key press task that elicited one of two possible tones. The reported time of action shifted closer to the tone when the tone was used to indicate the winner of a race (Exp.2) compared to when the tone was meaningless and did not indicate winning (Exp.1). This suggests that reported time of an unintended action could shift toward the effect in some contexts. Furthermore, the results from Exp.2 and Exp.3 (tones were substituted with verbal feedback) showed that a presumed winning action was judged to occur earlier whereas a presumed losing action was judged to be later. These findings therefore support the view that the reported time of action is reconstructed from known temporal information rather than determined by intentionality. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Aerosol Dynamics in Atmospheric Aromatic Photooxidation

Aerosol formation and growth in aromatic hydrocarbon / NO_x systems was studied in a series of outdoor smog chamber experiments. Analysis of the aerosol size distributions in those experiments that exhibited steady condensational growth provides estimates for the gas-phase partial pressures of the condensing species. Saturation ratios during these growth periods are estimated by comparing these partial pressures with vapor pressures obtained from an analysis of nucleation (Stern et al., 1987), and are found to be in the range of 5 to 20. Modeling of the size–distribution dynamics during the experiments is carried out using the sectional model ESMAP (Warren and Seinfeld, 1985). The full size-distribution model predicts more nucleation than an integral model (Stern et al., 1987), because the polydisperse aerosol representation leads to a lower condensation rate than that predicted for a monodisperse aerosol.     

Documentation services: an expanding future

The sophistication of documentation services has much increased in recent years with the advent of computerised retrieval systems. Here the author shows how this has also opened up the potential for better international information transfer by harmonising different data bases, a task already started within CIB. Mr. Stern is director of Byggdok, the Swedish Institute for Building Documentation, and is also a member of the CIB Board.     

The developmental relations between conceptual and procedural knowledge: A multimethod approach.

Interactions between conceptual and procedural knowledge influence the development of mathematical competencies. However, after decades of research, these interrelations are still under debate, and empirical results are inconclusive. The authors point out a source of these problems. Different kinds of knowledge and competencies only show up intertwined in behavior, making it hard to measure them validly and independently of each other. A multimethod approach was used to investigate the extent of these problems. A total of 289 fifth and sixth graders’ conceptual and procedural knowledge about decimal fractions was measured by 4 common hypothetical measures of each kind of knowledge. Study 1 tested whether treatments affected the 2 groups of measures in consistent ways. Study 2 assessed, across 3 measurement points, whether conceptual and procedural knowledge could be modeled as latent factors underlying the measures. The results reveal substantial problems with the validities of the measures, which might have been present but gone undetected in previous studies. A solution to these problems is essential for theoretical and practical progress in the field. The potential of the multimethod approach for this enterprise is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparison of administration procedures for the Rey-Osterrieth Complex Figure: Flowcharts versus pen switching.

The Rey-Osterrieth Complex Figure (ROCF) is commonly used to assess visuospatial skills, visuoconstruction, visual memory, and executive functioning. Two different methods are traditionally used to record the order in which the figure is drawn: the flowchart method and the pen-switching method. Although it has been suggested that pen switching may interfere with performance, to date no research has been conducted to assess whether ROCF performance significantly differs due to administration method. As part of routine neuropsychological evaluation, 100 inpatients and outpatients were randomly assigned to either method. Using the Boston Qualitative Scoring System and the traditional 36-point scoring method, the authors unexpectedly found that the pen-switching group generally performed better than the flowchart group, and productions drawn with pen switching were also significantly faster to score. (PsycINFO Database Record (c) 2010 APA, all rights reserved)