Surface photovoltage spectroscopy on Cu(In,Ga)(S,Se)2/ZnS‐nanodot/In2S3 systems

Single layers and combined layer systems with Cu(In,Ga)(S,Se)₂, ZnS‐nanodot (nd) and In₂S₃ layers were investigated by surface photovoltage spectroscopy in the Kelvin‐probe arrangement and compared with the open‐circuit voltage (V_OC) of solar cells. The In₂S₃ and ZnS‐nd layers were prepared by the spray ion layer gas reaction (ILGAR) technique from Indium chloride (InCl₃), Indium acetylacetonate (In(acac)₃) and Zinc acetylacetonate, respectively. The surface photovoltage signals of Cu(In,Ga)(S,Se)₂ were larger for the Cu(In,Ga)(S,Se)₂/ZnS‐nd/In₂S₃ than for the Cu(In,Ga)(S,Se)₂/In₂S₃ layer system showing that a ZnS‐nd layer additionally passivated the Cu(In,Ga)(S,Se)₂ surface. ILGAR In₂S₃ deposition from InCl₃ precursor solution led to a modification of surface defects of ZnS‐nd and to generation of defect states below the band gap of Cu(In,Ga)(S,Se)₂, which has not been observed for deposition from Indium acetylacetonate precursor. Defect generation during ILGAR In₂S₃ deposition with InCl₃ precursor resulted in a lower V_OC of Cu(In,Ga)(S,Se)₂/ZnS‐nd/In₂S₃/ZnO : Al solar cells. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis of Eu-doped SrAl2O4 nanophosphors by CO2 laser vaporization

A new method of synthesizing spherical nanoparticles with photoluminescent spinel structures using a CO₂ laser co-vaporization technique (CoLAVA) is presented. The method applies homogeneous mixtures of oxidic precursors such as Al₂O₃, SrO and Eu₂O₃ and allows the fabrication of quantities exceeding 10 g h^?1. During the CoLAVA process, the educt oxides are reacted by a gas phase condensation yielding amorphous spherical particles with diameters ranging from 10 to 100 nm. The as-prepared materials exhibit red emission at 625 nm (1.98 eV) due to the incorporated Eu³⁺. Temperature treatment up to 1200 °C under a reducing atmosphere yielded crystalline particles of the same size, which were slightly sintered. These particles consisted of >90 wt.% SrAl₂O₄ with minor fractions of Sr₃Al₂O₆ and SrCO₃. The amount of the SrAl₂O₄ spinel increased with increasing temperature, whereas the accompanying phases were decreased. A strong green emission centered at 525 nm (2.36 eV) detected at RT was observed at an onset temperature of 900 °C, which is due to the presence of Eu²⁺ in the crystal lattice of SrAl₂O₄. The red emission was not observed at higher annealing temperatures. The CoLAVA method represents a fast and facile route for the fabrication of nano- to microstructured phosphor materials for a variety of engineering applications.     

Acute and chronic toxicity effects of silver nanoparticles (NPs) on Drosophila melanogaster

The use of nanoscaled materials is rapidly increasing, however, their possible ecotoxicological effects are still not precisely known. This work constitutes the first complex study focused on in vivo evaluation of the acute and chronic toxic effects and toxic limits of silver nanoparticles (NPs) on the eukaryotic organism Drosophila melanogaster. For the purpose of this study, silver NPs were prepared in the form of solid dispersion using microencapsulation method, where mannitol was used as an encapsulation agent. This newly prepared solid dispersion with a high concentration of silver NPs was exploited to prepare the standard Drosophila culture medium at a silver concentration range from 10 mg·L(-1) to 100 mg·L(-1) of Ag in the case of the acute toxicity testing and at a concentration equal to 5 mg·L(-1) in the case of the chronic toxicity testing. The acute toxic effect of silver NPs on Drosophila melanogaster was observed for the silver concentration equal to 20 mg·L(-1). At this silver concentration, 50% of the tested flies were unable to leave the pupae, and they did not finish their developmental cycle. Chronic toxicity of silver NPs was assessed by a long-term exposure of overall eight filial generations of Drosophila melanogaster to silver NPs. The long-term exposure to silver NPs influenced the fertility of Drosophila during the first three filial generations, nevertheless the fecundity of flies in subsequent generations consequently increased up to the level of the flies from the control sample due to the adaptability of flies to the silver NPs exposure.     

Molecular cloning of a novel human receptor gene with homology to the rat adrenomedullin receptor and high expression in heart and immune system

Lipopolysaccharide was isolated from strain LMG 6999 of Burkholderia vietnamiensis. Degradative and NMR spectroscopic studies established the presence of two polymeric fractions based on the following trisaccharide repeating units: I:-->3)-alpha-D-Galp-(1-->3)-beta-D-Galp-(1-->3)-beta-D-GalpNAc- (1-->; II:-->3)-alpha-D-GalpNAc-(1-->3)-beta-D-GalpNAc-(1-->4)- alpha-L-Rhap-(1-->. The same polymers have previously been found together in lipopolysaccharide from the reference strain for Burkholderia cepacia serogroup O4 and, individually, in those from B. cepacia serogroups C (I) and A (II).     

Cooperative method development

The development of methods tools and process improvements is best to be based on the understanding of the development practice to be supported. Qualitative research has been proposed as a method for understanding the social and cooperative aspects of software development. However, qualitative research is not easily combined with the improvement orientation of an engineering discipline. During the last 6 years, we have applied an approach we call ‘cooperative method development’, which combines qualitative social science fieldwork, with problem-oriented method, technique and process improvement. The action research based approach focusing on shop floor software development practices allows an understanding of how contextual contingencies influence the deployment and applicability of methods, processes and techniques. This article summarizes the experiences and discusses the further development of this approach based on several research projects in cooperation with industrial partners.

The Complexity of Parallel Multisearch on Coarse-Grained Machines

Given m ordered segments that form a partition of some universe (e.g., a two-dimensional strip), the multisearch problem consists of determining, for a set of n query points in the universe, the segments they belong to. We present the first nontrivial parallel deterministic scheme for performing multisearch on a distributed-memory machine when m=ω(n) . The scheme is designed on the BSP* model of parallel computation, a variant of Valiant's BSP which rewards blockwise communication, and relies on a suitable redundant representation of the segments. The time needed to answer the queries is analyzed as a function of the redundancy and of the BSP* parameters. We show that optimal performance can be obtained using logarithmic redundancy. We also prove a lower bound on the communication requirements of any deterministic multisearch scheme realized on a distributed-memory machine. The lower bound exhibits a tradeoff between the redundancy used to represent the segments and the performance of the scheme. Received June 1, 1997; revised March 10, 1998.     

A new approach to the synthesis of 4-bar function generatorsNeue methoden für die synthese viergliedriger funktionsgeneratoren

In the present work a new approach to the synthesis of 4-bar function generators has been presented. Using this graphical method quick and at the same time sufficiently accurate synthesis is possible in a large number of cases. The method is based on the principle of coordinating two positions and the corresponding velocities of the input and the output links. Thus four conditions are satisfied and better accuracy than that with three point synthesis may be expected. Positions of the proper accuracy points have been discussed and some guidance to the selection of the initial data has been presented in this paper. One problem has been solved as an example.