Avalanche‐Discharge‐Induced Electrical Forming in Tantalum Oxide‐Based Metal–Insulator–Metal Structures

Oxide‐based metal–insulator–metal structures are of special interest for future resistive random‐access memories. In such cells, redox processes on the nanoscale occur during resistive switching, which are initiated by the reversible movement of native donors, such as oxygen vacancies. The formation of these filaments is mainly attributed to an enhanced oxygen diffusion due to Joule heating in an electric field or due to electrical breakdown. Here, the development of a dendrite‐like structure, which is induced by an avalanche discharge between the top electrode and the Ta₂O_5‐x layer, is presented, which occurs instead of a local breakdown between top and bottom electrode. The dendrite‐like structure evolves primarily at structures with a pronounced interface adsorbate layer. Furthermore, local conductive atomic force microscopy reveals that the entire dendrite region becomes conductive. Via spectromicroscopy it is demonstrated that the subsequent switching is caused by a valence change between Ta⁴⁺ and Ta⁵⁺, which takes place over the entire former Pt/Ta₂O_5‐x interface of the dendrite‐like structure.     

Improving SCImago Journal &; Country Rank (SJR) subject classification through reference analysis

In order to re-categorize the SCImago Journal & Country Rank (SJR) journals based on Scopus, as well as improve the SJR subject classification scheme, an iterative process built upon reference analysis of citing journals was designed. The first step entailed construction of a matrix containing citing journals and cited categories obtained through the aggregation of cited journals. Assuming that the most representative categories in each journal would be represented by the highest citation values regarding categories, the matrix vectors were reduced using a threshold to discern and discard the weakest relations. The process was refined on the basis of different parameters of a heuristic nature, including (1) the development of several tests applying different thresholds, (2) the designation of a cutoff, (3) the number of iterations to execute, and (4) a manual review operation of a certain amount of multi-categorized journals. Despite certain shortcomings related with journal classification, the method showed a solid performance in grouping journals at a level higher than categories—that is, aggregating journals into subject areas. It also enabled us to redesign the SJR classification scheme, providing for a more cohesive one that covers a good proportion of re-categorized journals.     

Accreditation of testing laboratories in dosimetry: the use of a flexible scope at the Competent Incorporation Measuring Body Jülich

The accreditation of the Competent Incorporation Measuring Body at Jülich includes incorporation monitoring by means of direct measurements of the body activity as well as by means of indirect determination of the body activity by radiochemical analysis of excreta samples. In both testing areas, it proved to be very useful to have a flexible scope. In particular, the associated freedom in choosing testing procedures supports the continual improvement process of the laboratory. The modification of existing methods as well as the development and introduction of new procedures makes an immediate reaction to changed requirements feasible. At Jülich the use made out of the flexible scope included, e.g. the introduction of mathematical calibration in whole-body counting and the automation of sample preparation in radiochemical analysis. Advantages of the new procedures and modified methods include on the one hand the reduction of processing times, downtimes and hazard potentials on the other hand enhanced detection limits and improved cost-efficiency. In the result, it can be recommended to other qualified testing laboratories to go for a flexible scope.     

Finnish radon situation analysed using national measurement database

Radiation and Nuclear Safety Authority (STUK) maintains the national indoor radon measurement database in Finland. The analysis of the database material supplements information on radon situation collected by random sampling surveys. The 92,000 dwellings in the database are not a representative sample of the Finnish housing stock. However, the bias is compensated by calculating radon parameters in 1-km(2) cells and weighting the cells by the number of dwellings in the cell. Both the database material and a recent random sampling survey show that radon concentrations in new Finnish houses have been decreasing since the 1990s. This positive trend is clearly stronger in radon-prone areas where preventive measures are nowadays commonly implemented in new construction. The changeover to mechanical supply and exhaust ventilation together with the increase in crawl-space foundations has also contributed to the decrease in the concentrations.     

Clinical audit: Development of the criteria of good practices

Clinical audit is a systematic review of the procedures in order to improve the quality and the outcome of patient care, whereby the procedures are examined against agreed standards for good medical RADIOLOGICAL procedures. The criteria of good procedures (i.e. the good practice) are thus the cornerstones for development of clinical audits: these should be the basis of assessments regardless of the type of the audit--external, internal, comprehensive or partial. A lot of criteria for good practices are available through the recommendations and publications by international and national professional societies and other relevant organisations. For practical use in clinical audits, the criteria need to be compiled, sorted out and agreed on for the particular aims of an audit (comprehensive or partial, external or internal). The national professional and scientific societies can provide valuable contribution to this development. For examination--or treatment-specific criteria--preliminary consensus needs to be obtained with the help of clinical experts, while clinical audits can be useful as a benchmarking tool to improve the criteria.     

Optische Oberflächencharakterisierung von plasmagespritzten stochastischen Strukturen

In this paper microstructures have been produced with a stochastic distribution by a thermal spraying process with different process parameters. An optical roughness measurement device has been used to measure these microstructures. Afterwards the measurement data is processed in order to identify each microstructure. Using this data several characteristics like the area, the volume and the depth of the microstructures as well as several porosities have been computed. These characteristics could be correlated to the process parameters. Furthermore, tribological experiments have been conducted with these surfaces and additional correlations between the friction value and the characteristics area, depth and the average roughness besides the structures have been performed.