Improvement of photon collection in Cu(In,Ga)Se2 solar cells and modules by fluorescent frequency conversion

Fluorescent photon down conversion for the improvement of the blue response of ZnO/CdS/Cu(In,Ga)Se₂ heterojunction solar cells and modules is investigated. Fluorescent dyes of the series Lumogen® F are analyzed by optical transmission and reflection as well as by photoluminescence measurements. A spectral transfer matrix formalism is introduced that allows to predict the suitability of a luminescent dye as a down-converter for a given solar cell from its absorption/emission properties. We find that Lumogen® F Violet 570 and Lumogen® F Yellow 083 as well as a combination of both yields improvements for Cu(In,Ga)Se₂ solar modules. Particularly, we find that the short circuit current density of a Cu(In,Ga)Se₂ mini-module is improved by 1.5 mA cm^− 2 when applying a varnish with a combination of Lumogen® F Violet and Yellow. About 0.5 mA cm^− 2 of this improvement is due to a reduced overall reflectance and an improvement of 1 mA cm^− 2 results from the frequency conversion by the dyes.     

Sigmatek fördert Hightech-Nachwuchs

AktuellLaborausstattung für HTL Salzburg

Sigmatek f?rdert Hightech-Nachwuchs     

Experience with Widening Based Equivalence Checking in Realistic Multimedia Systems

The application of loop and data transformations to array and loop intensive programs is crucial to obtain a good performance. Designers often apply these transformations manually or semi-automatically. For the class of static affine programs, automatic methods exist for proving the correctness of these transformations. Realistic multimedia systems, however, often contain constructs that fall outside of this class. We present an extension of a widening based approach to handle the most relevant of these constructs, viz. accesses to array slices, data dependent accesses and data dependent assignments, and report on some experiments with non-trivial applications.     

A comparative study of a fluidised bed reactor and a gas lift loop reactor for the IBE process: Part I. Reactor design and scale down approach

For the continuous production of isopropanol-butanol mixtures by immobilised Clostridium spp. (the IBE process) two reactor types were studied: a fluidised bed reactor with liquid recycling (FBR) and an external loop gas lift reactor (GLR). A large scale design (50–65 m³) was made for both reactors. A regime analysis, by evaluating the time constants for e.g. mixing and conversion, identified the ruling regime. Via the scale down approach two representative model reactors were developed: a 10 dm³ FBR reactor (H/D=25, D=0.08 m) and a 15 dm³ external loop GLR (H/D = 12.5, D_r=D_d=0.08 m). For both reactors the hydrodynamical behaviour and the total reactor performance were studied and are described in parts II and III of this study.     

Private financing in the dutch public housing sector: The rise and fall of the accumulative loan

The author wishes to thank miss Barbara den Boer for her translation.     

Controlling Chiral Spin States of a Triangular‐Lattice Magnet by Cooling in a Magnetic Field

Magnetic materials with a non‐collinear and non‐coplanar arrangement of magnetic moments hosting a nonzero scalar spin‐chirality exhibit unique magnetic and spin‐dependent electronic transport properties. The spin chirality often occurs in materials where competing exchange interactions lead to geometrical frustrations between magnetic moments and to a strong coupling between the crystal lattice and the magnetic structure. These characteristics are particularly strong in Mn‐based antiperovskites where the interactions and chirality can be tuned by substitutional modifications of the crystalline lattice. This study presents evidence for the formation of two unequal chiral spin states in magnetically ordered Mn_3.338Ni_0.651N antiperovskite based on density functional theory calculations and supported by magnetization measurements after cooling in a magnetic field. The existence of two scalar spin‐chiralities of opposite sign and different magnitude is demonstrated by a vertical shift of the magnetic‐field dependent magnetization and Hall effect at low fields and from an asymmetrical magnetoresistivity when the applied magnetic field is oriented parallel or antiparallel to the direction of the cooling field. This opens up the possibility of manipulating the spin chirality for potential use in the emerging field of chiral spintronics.     

Thin-layer chromatography of aliphatic γ — and δ -lactones

Homologous aliphatic γ- or δ-lactones are separated by thin-layer chromatography on a mixture of kieselguhr G and silica gel G (1:8). The thin-layer plates are chromatographically impregnated with methanol as the stationary phase and developed 3 times with light petroleum (bp 80–100C) saturated with methanol. γ- And δ-lactones can be separated from each other on the same adsorbent with a 1:1 mixture of light petroleum (bp 30–40C) and isopropyl ether. The systems can be combined 2-dimensionally. The lactones are detected by spraying the chromatoplates either with a 2% solution of iodine in methanol or with alkaline hydroxylamine followed by ferric chloride and acetic acid. These methods were used for the tentative identification of δ-C_10–16 lactones in commercial Australian butteroil.     

Flotation of Sulfide Components of Copper Ore in the Presence of n-Dodecane

Influence of n-dodecane aqueous emulsion on flotation of sulfide minerals present in the copper ore from the Legnica-Glogow Copper Basin (LGOM), carried out on the laboratory scale, was investigated. Five flotation experiments performed in the presence of different doses of n-dodecane were conducted and compared. Next, mineral analysis of selected flotation products were conducted and discussed. The best flotation selectivity was obtained for bornite, tennantite and chalcocite using 600 g/t of n-dodecane. In the case of non-copper sulfides, the maximum selectivity was observed for sphalerite and galena. Measurements of the rest potential of copper sulfide conducted to explain the differences between recoveries of each sulfide mineral were performed. It was observed, that with increasing sulfide rest potential, the recovery was decreasing. The study provided information hitherto poorly available in literature on flotation of sulfides from the LGOM area with n-dodecane.     

Recognizing Age at Slaughter of Cattle from Beef Samples Using GC/MS–SPME Chromatographic Method

Beef from cattle less than 30 months old at the point of slaughter are generally sold in meat markets. Though the age of the animal can generally be estimated by dentition, this method cannot be applied to a carcass or a piece of meat from which the teeth have been removed. Since gas chromatography of volatile organic compounds has been used to classify biological samples, this technique was used for classifying meat obtained from cattle aged over 30 months (OTM) at point of slaughter. Volatile organic compounds of fresh meat (M. longissimus dorsi) samples obtained from cattle of different age and dentition (two, four, and six teeth) at point of slaughter were analyzed using gas chromatography/mass spectrum (GC/MS). Six volatile organic compounds were selected (hexanoic acid, benzoic acid, octanoid acid, tridecane, tetradecane, and 4-formylbenzoic acid) and confirmed by using chemical standards and Kovat’s indexes. The chromatogram data were used to train two classifiers, one based on the partial least square (PLS) method and another based on support vector machine (SVM), but only SVM showed high accuracy. Data exploration based on the principal component analysis allowed for comprehension of the data distribution, proposing a new version of PLS in a parallel configuration. This modified version of the PLS algorithm showed better accuracy than the SVM classifier. In conclusion, volatile organic compounds analyzed by GC/MS–solid-phase microextraction can be used to recognize OTM beef.