The influence of user expertise and prototype fidelity in usability tests

An empirical study examined the impact of user expertise and prototype fidelity on the outcomes of a usability test. User expertise (expert vs. novice) and prototype fidelity (paper prototype, 3D mock-up, and fully operational appliance) were manipulated as independent variables in a 2 × 3 between-subjects design. Employing a floor scrubber as a model product, 48 users carried out several cleaning tasks. Usability problems identified by participants were recorded. Furthermore, performance, system management strategies and perceived usability were measured. The results showed that experts reported more usability problems than novices but these were considered to be less severe than those reported by novices. Reduced fidelity prototypes were generally suitable to predict product usability of the real appliance. The implications for the running of usability tests are specific to the fidelity of the prototype.     

Efficiency improvement of dye-sensitized solar cells based on electrodeposited TiO2 films by low temperature post-treatment

Porous crystalline TiO₂ films can be prepared at low temperatures (80 °C) by surfactant-assisted electrodeposition from TiCl₃ solution. Nevertheless, up to now calcination at high temperatures (typically 450 °C) was still necessary to establish a good performance of these films in dye-sensitized solar cells (DSSC). With this study we report that water vapour treatment at much lower temperatures (150 °C) for 1 week improves the performance of the films in DSSC to the same degree as calcination although the overall crystallinity remains lower. Reason for the good efficiency is that the porous structure stays intact and thus the dye molecules can be better adsorbed. Avoiding high temperatures during the preparation process of TiO₂ films for the application in DSSC enables the use of polymer substrates for the fabrication of flexible solar cells.     

Fluorous Iminoalditols: A New Family of Glycosidase Inhibitors and Pharmacological Chaperones

A collection of new reversible glycosidase inhibitors of the iminoalditol type featuring N‐substituents containing perfluorinated regions has been prepared for evaluation of physicochemical, biochemical and diagnostic properties. The vast variety of feasible oligofluoro moieties allows for modular approaches to customised structures according to the intended applications, which are influenced by the fluorine content as well as the distance of the fluorous moiety from the ring nitrogen. The first examples, in particular in the D ‐galacto series, exhibited excellent inhibitory activities. A preliminary screen with two human cell lines showed that, at subinhibitory concentrations, they are powerful pharmacological chaperones enhancing the activities of the catalytically handicapped lysosomal D ‐galactosidase mutants associated with GM1 gangliosidosis and Morquio B disease.     

Interaction of hIAPP with Model Raft Membranes and Pancreatic β‐Cells: Cytotoxicity of hIAPP Oligomers

Type II diabetes mellitus (T2DM) is associated with β‐cell failure, which correlates with the formation of pancreatic islet amyloid deposits. The human islet amyloid polypeptide (hIAPP) is the major component of islet amyloid and undergoes structural changes followed by self‐association and pathological tissue deposition during aggregation in T2DM. There is clear evidence that the aggregation process is accelerated in the presence of particular lipid membranes. Whereas hIAPP aggregation has been extensively studied in homogeneous model membrane systems, especially negatively charged lipid bilayers, information on the interaction of hIAPP with heterogeneous model raft membranes has been missing until now. In the present study, we focus on the principles of aggregation and amyloid formation of hIAPP in the presence of model raft membranes. Time‐lapse tapping mode AFM and confocal fluorescence microscopy experiments followed membrane permeabilization and localization of hIAPP in the raft membrane. Together with the ThT and WST‐1 assay, the data revealed elevated cytotoxicity of hIAPP oligomers on INS‐1E cells.     

Absorbable polymer stent technologies for vascular regeneration

Stents are structural implants with widespread clinical use in vascular intervention to re‐open stenotic vessels for the treatment of coronary artery disease and peripheral arterial occlusive disease. Apart from their mechanical function, current drug‐eluting stents (DES) utilize local drug delivery from a drug‐incorporated permanent polymer coating to prevent in‐stent restenosis. This delayed closure of the stented vessel is considered one of the major limitations of conventional bare metal stents (BMS). The long‐term safety of DES, however, is still under debate, with reported cases of delayed healing, late thrombosis and hypersensitivity demanding further evolution in this field. A promising approach to circumvent the limitations of first generation DES is the application of degradable polymer coatings in second generation DES, and fully absorbable polymer stents. From a materials and engineering perspective, this paper provides a mini‐review of current clinically relevant DES technology and recent advancements in the development of stents from degradable polymeric materials as an alternative to permanent BMS and DES. This review, includes work on degradable stents and coatings based on blends of polylactic acid and the microbially‐produced poly(4‐hydroxybutyrate). Copyright © 2009 Society of Chemical Industry