Improved photovoltaic performances by post-deposition acidic treatments on tetrapod shaped colloidal nanocrystal solids

The ligand exchange reaction with pyridine is the standard procedure for the integration of colloidal semiconductor nanocrystals (NCs) in photovoltaic devices; however, for large sized and irregularly shaped branched NCs, such as CdSe@CdTe tetrapods, this procedure can lead to a considerable waste of materials and the aggregation of NCs in the colloidal solution, therefore resulting in the formation of an inhomogeneous film and low device performances. Here, we report on alternative post-deposition treatments with carboxylic acids on films of CdSe@CdTe tetrapod shaped NCs. This approach guarantees the removal of the insulating surfactant, necessary to obtain good charge transport among NCs, while preserving the film integrity. We perform a complete characterization of the nanocrystalline films treated with different carboxylic acids and demonstrate the successful integration of such films in photovoltaic devices, showing a doubled efficiency with respect to the standard ligand exchange procedure. Our approach represents a general route towards the development of NC based devices with improved performances and minimized waste of material.     

MRI of the occipital cortex, red nucleus, and substantia nigra during visual aura of migraine

PURPOSE: Although radical nephrectomy is the standard treatment for localized unilateral renal cell carcinoma with a normal contralateral kidney, there is ongoing interest in the use of nephron sparing surgery or partial nephrectomy in such cases. The extent of radical surgery in such cases has also been reconsidered in view of the uncertainty regarding the malignant or benign nature. MATERIALS AND METHODS: Of 14,793 autopsies in Jena from 1985 until 1995 there were 260 renal cell carcinomas. Of the 260 renal cell carcinomas the diameter was 40 mm. or less in 104. These 104 tumors were divided into group 1-20 mm. or less (33 cases), group 2-21 to 30 mm. (28) and group 3-31 to 40 mm. (43). RESULTS: Grade 1 renal cell carcinomas decreased in frequency with increasing tumor diameter, while an opposite result was noted for grade 3. Lymph node and distant metastases were well correlated with tumor size. With an increase in tumor size the frequency of venous involvement increased as well. Significantly more multifocal malignant renal cell carcinomas were seen in tumors between 21 and 40 mm. compared to those 20 mm. or less in diameter. CONCLUSIONS: The metastatic potential and biology of these small nodules are not yet known. To lower the risk of local recurrence the results of our study suggest that nephron sparing surgery might be advisable in patients with renal cell carcinoma 20 mm. or less in diameter.     

Conformational transitions in poly(butyl methacrylate)

Summary Temperature dependence of viscosity data was investigated on poly(butyl methacrylate) fractions in dilute solution. A discontinuity in intrinsic viscosity was observed in the 25°C–35°C temperature range. Sharp changes of unperturbed dimensions were visualized from this behaviour. The phenomenon can be accounted for by assuming conformational changes of the chain in different solvents.     

A comparative study of many-objective evolutionary algorithms for the discovery of software architectures

During the design of complex systems, software architects have to deal with a tangle of abstract artefacts, measures and ideas to discover the most fitting underlying architecture. A common way to structure such complex systems is in terms of their interacting software components, whose composition and connections need to be properly adjusted. Along with the expected functionality, non-functional requirements are key at this stage to guide the many design alternatives to be evaluated by software architects. The appearance of Search Based Software Engineering (SBSE) brings an approach that supports the software engineer along the design process. Evolutionary algorithms can be applied to deal with the abstract and highly combinatorial optimisation problem of architecture discovery from a multiple objective perspective. The definition and resolution of many-objective optimisation problems is currently becoming an emerging challenge in SBSE, where the application of sophisticated techniques within the evolutionary computation field needs to be considered. In this paper, diverse non-functional requirements are selected to guide the evolutionary search, leading to the definition of several optimisation problems with up to 9 metrics concerning the architectural maintainability. An empirical study of the behaviour of 8 multi- and many-objective evolutionary algorithms is presented, where the quality and type of the returned solutions are analysed and discussed from the perspective of both the evolutionary performance and those aspects of interest to the expert. Results show how some many-objective evolutionary algorithms provide useful mechanisms to effectively explore design alternatives on highly dimensional objective spaces.     

A study of the suitability of the KENTORT II eastern shale oil for asphalt paving applications

The uncertain future of petroleum reserves has fuelled the search for alternative resources. A feasibility study was conducted to determine potential paving applications of the oil extracted from eastern shale by the KENTORT II process. The eastern shale oil (ESO) in this study was separated into two drastically different viscosity portions, designated as ‘hard’ and ‘soft’ ESO. It was hypothesized that the ‘hard’ portion might enhance the asphalt performance by increasing the stiffness. It was discovered that the ‘hard’ ESO modified asphalt properties deteriorate significantly with time. On the other hand, the ‘soft’ ESO was found to exhibit desirable properties in an asphalt recycling application. Further studies are recommended to fully characterize the binder and mixture properties of ESO modified/rejuvenated asphalts.     

Unusual Lipid A from a Cold‐Adapted Bacterium: Detailed Structural Characterization

Colwellia psychrerythraea 34H is a Gram‐negative cold‐adapted microorganism that adopts many strategies to cope with the limitations associated with the low temperatures of its habitat. In this study, we report the complete characterization of the lipid A moiety from the lipopolysaccharide of Colwellia. Lipid A and its partially deacylated derivative were completely characterized by high‐resolution mass spectrometry, NMR spectroscopy, and chemical analysis. An unusual structure with a 3‐hydroxy unsaturated tetradecenoic acid as a component of the primary acylation pattern was identified. In addition, the presence of a partially acylated phosphoglycerol moiety on the secondary acylation site at the 3‐position of the reducing 2‐amino‐2‐deoxyglucopyranose unit caused tremendous natural heterogeneity in the structure of lipid A. Biological‐activity assays indicated that C. psychrerythraea 34H lipid A did not show an agonistic or antagonistic effect upon testing in human macrophages.