Electro-Oxidation of Titanium Carbide Nanoparticles in Aqueous Acid Creates TiC@TiO2 Core-Shell Structures

Titanium carbide (TiC) is an attractive support material used in electro-catalysis and sensing. We report the electrochemistry of TiC nanoparticles (NPs, 35–50 nm in diameter) in different electrolytes in the pH range of 0 to 8. The TiC NPs undergo irreversible oxidation in acidic, basic, and neutral media, attributed to the partial conversion into titanium dioxide (TiO2) with the amount of oxidation highly dependent on the pH of the solution. In H2SO4 (pH 0), multiple voltammetric scans revealed the conversion to be partial but repeated scans allowed a conversion approaching 100% to be obtained with 20 scans generating a ca 60% level of oxidation. The process is inferred to lead to the formation of TiC@TiO2 core-shell nanoparticles (~12.5 nm core radius and ~5 nm shell width for a 60% conversion) and this value sharply decreases with an increase of pH. Independent measurements were conducted at a single NP level (via nano-impact experiments) to confirm the oxidation of the NPs, showing consistent agreement with the bulk measurements

Quantitative localized proton-promoted dissolution kinetics of calcite using scanning electrochemical microscopy (SECM)

Scanning electrochemical microscopy (SECM) has been used to determine quantitatively the kinetics of proton-promoted dissolution of the calcite (101̅4) cleavage surface (from natural “Iceland Spar”) at the microscopic scale. By working under conditions where the probe size is much less than the characteristic dislocation spacing (as revealed from etching), it has been possible to measure kinetics mainly in regions of the surface which are free from dislocations, for the first time. To clearly reveal the locations of measurements, studies focused on cleaved “mirror” surfaces, where one of the two faces produced by cleavage was etched freely to reveal defects intersecting the surface, while the other (mirror) face was etched locally (and quantitatively) using SECM to generate high proton fluxes with a 25 μm diameter Pt disk ultramicroelectrode (UME) positioned at a defined (known) distance from a crystal surface. The etch pits formed at various etch times were measured using white light interferometry to ascertain pit dimensions. To determine quantitative dissolution kinetics, a moving boundary finite element model was formulated in which experimental time-dependent pit expansion data formed the input for simulations, from which solution and interfacial concentrations of key chemical species, and interfacial fluxes, could then be determined and visualized. This novel analysis allowed the rate constant for proton attack on calcite, and the order of the reaction with respect to the interfacial proton concentration, to be determined unambiguously. The process was found to be first order in terms of interfacial proton concentration with a rate constant k = 6.3 (± 1.3) × 10–4 m s–1. Significantly, this value is similar to previous macroscopic rate measurements of calcite dissolution which averaged over large areas and many dislocation sites, and where such sites provided a continuous source of steps for dissolution. Since the local measurements reported herein are mainly made in regions without dislocations, this study demonstrates that dislocations and steps that arise from such sites are not needed for fast proton-promoted calcite dissolution. Other sites, such as point defects, which are naturally abundant in calcite, are likely to be key reaction sites

Development of a Catastrophe Model for Managing the Risks of Urban Flash Flooding in Vienna

This report provides a case study examining flood risks in the city of Vienna. The purpose is to illustrate an interdisciplinary approach to flood risk analysis, combining hydrological flood risk assessment and simulation modeling with the finances of flood risk management. Three scenarios were preliminarily identified for analysis: catastrophic flooding on a major European river (the Danube) that flows through Vienna; storm flooding due to failure of storm drainage systems; and flash flooding of a small tributary (the Vienna River) that flows into the Danube. Our initial efforts revealed that the Vienna River flash flooding scenario was a credible, significant, and tractable problem for analysis. The wealth of data available also made this scenario a useful test case for developing and illustrating interdisciplinary work, which is a significant aspect of the project activity. The focus of this report is, therefore, on the flash-flooding scenario. This report does not include discussion of the other scenarios, as they were not completed in an interdisciplinary fashion either because of lack of adequate data and models for all aspects of an interdisciplinary study, or because there were judged to be non-credible and therefore of limited use as an illustrative example. In the course of developing an interdisciplinary approach to examining catastrophic flood risks, we found that the concept of risk used in flood management varied subtly but significantly between the disciplines contributing to the study. An important result of this study is the integration of these different disciplinary concepts of risk within a single interdisciplinary analysis. A fuller accounting for uncertainty in a way that is consistent between the component disciplines, and the appropriate distinction between various different types of uncertainty, form a second major aspect of the study. Our primary finding is that an approach that integrates perspectives on risk characteristic of the different technical disciplines contributing to this study is feasible and that it provides a useful framework for comparing the characteristics of different mitigation strategies. The results of simulations suggest alternatives for combining different mitigation measures such that the characteristics of different components of an overall strategy complement each other to lower total costs and to reduce both the likelihood and the uncertainties of catastrophic financial losses

Uncertainty and Disaster Risk Management: Modeling the Flash Flood Risk to Vienna and Its Subway System

This report describes an interdisciplinary approach to flood risk analysis and management that was developed by investigating flood risks in the city of Vienna, Austria. The purpose of the research was to analyze different policy paths (including both flood-prevention measures and risk-sharing financial provisions) in the presence of major uncertainties. A preliminary analysis resulted in the identification of two major methodological issues that needed to be resolved, namely: -- The concept of risk used in flood management varied subtly but significantly across the disciplines contributing to the assessment. -- Current assessment procedures did not give a full account of uncertainties and their different types. For those reasons an approach was developed that allows the analyst: (1) to integrate the different diciplinary concepts of risk within a single interdisciplinary analysis; and (2) to take into account uncertainties in a way that not only allows their many characteristics to be distinguished but is also consistent across the component disciplines. The focus of this report is the phenomenon of flash flooing of the Vienna River. Our analysis demonstrated that, in this case, the greatest damage from flash flooding was to be expected in the Vienna city subway system. The report thus describes a detailed assessment of the flood risk to the subway and of related management measures, on which research to date has been scarce. The results show that an approach based on catastrophe modeling and Monte Carlo simulation can not ony integrate the risk perspectives of the different technical disciplines contributing to this study but also provide a useful framework for comparing the characteristics of different mitigation strategies. The results of the simulations suggest alternatives for combining different mitigation measures to ensure complementarity among the characteristics of different components of an overall strategy, and thereby decrease total costs and reduce the likelihood and the uncertainties of catastrophic financial losses

Factor Analysis of the Milwaukee Inventory for Subtypes of Trichotillomania-Adult Version

The Milwaukee Inventory for Subtypes of Trichotillomania-Adult Version (MIST-A; Flessner et al., 2008) measures the degree to which hair pulling in Trichotillomania (TTM) can be described as “automatic” (i.e., done without awareness and unrelated to affective states) and/or “focused” (i.e., done with awareness and to regulate affective states). Despite preliminary evidence in support of the psychometric properties of the MIST-A, emerging research suggests the original factor structure may not optimally capture TTM phenomenology. Using data from a treatment-seeking TTM sample, the current study examined the factor structure of the MIST-A via exploratory factor analysis. The resulting two factor solution suggested the MIST-A consists of a 5-item “awareness of pulling” factor that measures the degree to which pulling is done with awareness and an 8-item “internal-regulated pulling” factor that measures the degree to which pulling is done to regulate internal stimuli (e.g., emotions, cognitions, and urges). Correlational analyses provided preliminary evidence for the validity of these derived factors. Findings from this study challenge the notions of “automatic” and “focused” pulling styles and suggest that researchers should continue to explore TTM subtypes

Photographic Assessment of Change in Trichotillomania: Psychometric Properties and Variables Influencing Interpretation

Although photographic assessment has been found to be reliable in assessing hair loss in Trichotillomania, the validity of this method is unclear, particularly for gauging progress in treatment. The current study evaluated the psychometric properties of photographic assessment of change in Trichotillomania. Photographs showing hair loss of adults with Trichotillomania were taken before and after participating in a clinical trial for the condition. Undergraduate college students (N = 211) rated treatment response according to the photos, and additional archival data on hair pulling severity and psychosocial health were retrieved from the clinical trial. Photographic assessment of change was found to possess fair reliability (ICC = 0.53), acceptable criterion validity (r = 0.51), good concurrent validity (r = 0.30–0.36), and excellent incremental validity (ΔR2 = 8.67, p \u3c 0.01). In addition, photographic measures were significantly correlated with change in quality of life (r = 0.42), and thus could be considered an index of the social validity of Trichotillomania treatment. Gender of the photo rater and pulling topography affected the criterion validity of photographic assessment (partial η2 = 0.05–0.11). Recommendations for improving photographic assessment and future directions for hair pulling research are discussed

Clarifying the Relationship Between Trichotillomania and Anxiety

Although research has consistently linked unidimensional anxiety with Trichotillomania (TTM) severity, the relationships between TTM severity and anxiety dimensions (e.g., cognitive and somatic anxiety) are unknown. This knowledge gap limits current TTM conceptualization and treatment. The present study examined these relationships with data collected from ninety-one adults who participated in a randomized clinical trial for TTM treatment. Based on prior research, it was hypothesized that TTM severity would be related to the cognitive anxiety dimension and that psychological inflexibility would mediate the association. Hypotheses were not made regarding the relationship between TTM severity and somatic anxiety. Regression analyses indicated that only cognitive dimensions of anxiety predicted TTM severity and that psychological inflexibility mediated this relationship. Implications for the conceptualization and treatment of TTM are discussed

Literacy practices of primary education children in Andalusia (Spain): a family-based perspective

Primary school children develop literacy practices in various domains and situations in everyday life. This study focused on the analysis of literacy practices of children aged 8–12 years from the perspec- tive of their families. 1,843 families participated in the non-experimental explanatory study. The children in these families speak Spanish as a first language and are schooled in this language. The instrument used was a self-report questionnaire about children’s home-literacy practices. The data obtained were analysed using categorical principal components analysis (CATPCA) and analysis of variance (ANOVA). The results show the complex relationship between literacy practices developed by children in the domains of home and school and the limited development of a literacy-promoting ‘third space’. In conclusion, the families in our study had limited awareness of their role as literacy- promoting agents and thought of literacy learning as restricted to formal or academic spaces

Deeply Virtual Compton Scattering

We study in QCD the physics of deeply-virtual Compton scattering (DVCS)---the virtual Compton process in the large s and small t kinematic region. We show that DVCS can probe a new type of off-forward parton distributions. We derive an Altarelli-Parisi type of evolution equations for these distributions. We also derive their sum rules in terms of nucleon form-factors of the twist-two quark and gluon operators. In particular, we find that the second sum rule is related to fractions of the nucleon spin carried separately by quarks and gluons. We estimate the cross section for DVCS and compare it with the accompanying Bethe-Heitler process at CEBAF and HERMES kinematics.Comment: 20 pages, 2 figures, replaced with the version to appear in Phys. Rev.