The significance of defect chemistry for the rate of gas–solid reactions: three examples

Three examples are revisited in which the reaction rate could be reliably correlated with point defect chemistry highlighting the role of point defects as acid–base active centers. In the case of dehydrohalogenation of tertiary butyl chloride, AgCl becomes increasingly active as heterogeneous catalyst, if AgCl is homogeneously or heterogeneously doped. By such a procedure the silver vacancy concentration is adequately increased. The oxygen incorporation into SrTiO₃ offers an example in which the surface mechanism in terms of adsorbed species, oxygen vacancies and electronic centers has been elucidated. Appropriate surface coatings give rise to significant catalytic effects. Increasing iron (acceptor) doping not only changes the point defect chemistry but also the nature of the rate determining step. Lastly, the electrocatalytic function of Sr-doped LaMnO₃ is considered as regards oxygen reduction reaction and O²⁻ incorporation into Y-doped ZrO₂ in the context of solid oxide fuel cells. Again the defect chemistry is of prime importance for the reaction rate.     

Mass Transport in the Presence of Internal Defect Reactions—Concept of Conservative Ensembles: IV, Tracer Diffusion and Intercorrelation with Chemical Diffusion and Ion Conductivity

The tracer diffusion coefficient is analyzed for the case in which internal ionization equilibria have to be considered, using the concept of conservative ensembles. The relationships of the tracer diffusion coefficient with other phenome-nological parameters, viz., the chemical diffusion coefficient and the diffusion coefficient derived from the ionic conductivity, as well as with the defect diffusivities are given. The importance of mobile partially ionized or neutral defects is highlighted. In this respect the formulation of the tracer diffusion as an ambipolar diffusion of the different isotopes is helpful.     

Aerodynamics and aerosol particle deaggregation phenomena in model oral-pharyngeal cavities

The results of numerical simulations of the aerodynamics and of solid aerosol deaggregation phenomena arising in the process of airflow through various model human oropharyngeal cavities are reported. Special attention is given to the relevance of these simulations to the inhalation of dry-powder therapeutic aerosols. Several two- and three-dimensional mouth and throat geometries (terminating just beyond the larynx) are considered. Cross-sectional area-averaged viscous stress values are numerically determined as a function of distance from the mouth opening. These values, ranging from approximately 10 to 500 dyn cm⁻², are compared with estimates of Van der Waals attractive forces per unit area of particle-particle contact so as to evaluate the ability of the flowing airstream to deaggregate aerosol particles that enter the mouth in an aggregated state (held together principally by Van der Waals attractive forces). Estimates of airstream viscous stress differ markedly depending on whether the geometry is two- or three-dimensional. Quantitative differences between flow in a 90°-bend model and an oropharyngeal geometry numerically reconstructed from a cast of a human mouth and throat are especially significant in regards to the ability of the airstream to break apart particle agglomerates. For all geometries it is observed that increasingly smaller particle agglomerates may potentially be separated as the airflow rate increases from 30 to 2001 min⁻¹. At the highest airflows, aggregated particles of diameter near to or even below 1 μm may potentially be separated by the airflow. If separation of particle agglomerates is to occur, it appears far more likely to take place in the throat than in the mouth. This is especially apparent for the more physiologically faithful oropharyngeal geometries considered.     

Ethik-Cafés in der geriatrischen Langzeitpflege: halten sie,was sie versprechen?

Definition of the problem Ethics cafés in long-term geriatric care are considered as ethical education. They allow the participants to have an open discourse in a casual setting about moral issues related to daily work. In the literature, various characteristics are attributed to ethics cafés, e.g., improving analytical skills and communication, increasing ethical sensitivity and authority for making decisions. These characteristics primarily result from theory-based models. Arguments The goal of this study is the empirical investigation of the effectiveness of ethics cafés in the Nursing Homes Mattenhof–Irchelpark, Zurich. Furthermore, the study examined whether the subjective evaluation of characteristics of nurses and other professional groups are different. To capture the characteristics, a questionnaire was constructed in which the participants rated 16 statements during the survey period. A 5-point Likert scale was used for the analysis. One subgroup distinguished between “nursing staff” and “non-nursing staff”. Conclusion The postulated characteristics were confirmed with a very high approval. Therefore, the ethics cafés provide important input which enable the staff to analyze more clearly in difficult situations or to let them decide ethically in a more sensitive manner and to justify decisions made. The interdisciplinary approach supports an understanding of the views and arguments among the various areas and hierarchies. The differences between the two professionals groups are partially highly significant. It can be noted that the assigned characteristics in the questionnaire are generally perceived stronger and more significantly by the nursing staff. Therefore, a distinction must be made when interpreting the results of this study concerning the participants.     

Giving too much social support: social overload on social networking sites

As the number of messages and social relationships embedded in social networking sites (SNS) increases, the amount of social information demanding a reaction from individuals increases as well. We observe that, as a consequence, SNS users feel they are giving too much social support to other SNS users. Drawing on social support theory (SST), we call this negative association with SNS usage ‘social overload’ and develop a latent variable to measure it. We then identify the theoretical antecedents and consequences of social overload and evaluate the social overload model empirically using interviews with 12 and a survey of 571 Facebook users. The results show that extent of usage, number of friends, subjective social support norms, and type of relationship (online-only vs offline friends) are factors that directly contribute to social overload while age has only an indirect effect. The psychological and behavioral consequences of social overload include feelings of SNS exhaustion by users, low levels of user satisfaction, and a high intention to reduce or even stop using SNS. The resulting theoretical implications for SST and SNS acceptance research are discussed and practical implications for organizations, SNS providers, and SNS users are drawn.     

MALDI-TOF MS: an upcoming tool for rapid detection of antibiotic resistance in microorganisms

MALDI-TOF MS profiling for microorganism detection has already been demonstrated in the 1990s, but has evolved to the first-line identification method in many laboratories just during the past five years. While this application of MALDI-TOF MS has proven its broad applicability, accuracy, robustness, and cost-effectiveness it is of particular interest to expand the capabilities of the mass spectrometric platform. Resistance detection is the most desirable further application of MALDI-TOF MS in microbiology, but maybe also the most challenging. Different approaches have been published regarding diverse antibiotic drugs and distinct microorganism classes. The current review shall give an overview about the developments of the recent years and their potential to get transformed in clinical useful assays in the future.     

Displaying a boundary in graphic and symbolic “wait” displays: Duration estimates and users’ preferences

Two experiments assessed the effect of displaying a boundary on duration estimates and preference ratings for dynamic displays that were shown while users waited for the system's response. Displays were either symbolic (changing numbers) or graphic (increasing rectangles) and could contain a boundary that indicated when the interval was expected to be over. Duration estimates were similar for symbolic and graphic displays and for displays with and without a boundary. However, when the displays were encountered successively, participants assessed the graphic displays as having shorter durations than the symbolic displays. Faster rates of change in both types of displays led to increased duration estimates. Although displaying a boundary did not affect duration estimates, participants preferred displays in which a boundary was shown and preferred the graphic displays over the symbolic displays. Hence, bounded graphic displays are recommended as “wait” displays for computerized applications.