Separation of plutonium and neptunium species by capillary electrophoresis-inductively coupled plasma-mass spectrometry and application to natural groundwater samples

Capillary electrophoresis (CE) was coupled to ICPMS in order to combine the good performance of this separation technique with the high sensitivity of the ICPMS for the analysis of plutonium and neptunium oxidation states. The combination of a fused-silica capillary with a MicroMist AR 30-I-FM02 nebulizer and a Cinnabar small-volume cyclonic spray chamber yielded the best separation results. With this setup, it was possible to separate a model element mixture containing neptunium (NpO2(+)), uranium (UO2(2+)), lanthanum (La3+), and thorium (Th4+) in 1 M acetic acid. The same conditions were also suitable for the separation of various oxidation states of plutonium and neptunium in different aqueous samples. All separations were obtained within less than 15 min. A detection limit of 50 ppb identical with 2 x 10(-7) M (3-fold standard deviation of a blank) was achieved. To prove the negligible disturbance of the plutonium and neptunium redox equilibria during the CE separations, plutonium and neptunium speciation by CE-ICPMS in acidic solutions was compared with the results of UV/visible absorption spectroscopy and was found to be in good agreement. The CE-ICPMS system was also applied to study the reduction of Pu(VI) in a humic acid-containing groundwater at different pH values.     

Synthesis and self-assembly of colloidal nanoparticles

We describe recent developments in the synthesis of semiconductor nanoparticles, which lead to a substantial improvement of the luminescence quantum efficiency. Concerning a theoretical model for the growth of an ensemble of nanoparticles, the highest quantum efficiencies are achieved in particles that grow under conditions of a rapid exchange of monomers at the particle surface, leading to a smooth surface structure. Selective etching, core-shell formation and doping of nanoparticles are also discussed as fluorescence-enhancing preparative techniques. Examples of self-assembly of almost-uniformly-sized nanoparticles are given, which result in two-dimensional and three-dimensional superlattices, colloidal crystals and crystalline structures built-up from particles of different sizes. Finally, the self-assembled oriented attachment of quasi-spherical ZnO nanoparticles onto single-crystalline nanorods is presented.     

Micropositioning and microscopic observation of individual picoliter-sized containers within SU-8 microchannels

We describe the fabrication and application of a bioanalytical chip, made of SU-8 photoresist, comprising integrated, high aspect-ratio microfluidic channels, suitable to manipulate and investigate vesicles, cell fragments and biological cells. A central micrometer-sized aperture allows electrical particle counting and planar membrane experiments, microfluids allow (sub)micrometer-sized objects to be transported and addressed with different chemicals. Here we show how lipid vesicles are positioned with micrometer precision within the micro-channels by means of pressure and electrophoretic movement. Our approach is suited for controlling and investigating (bio)chemical synthesis and cellular signalling processes in ultrasmall individual vesicles by electro-optical techniques.     

Mumford-Shah model for one-to-one edge matching.

This paper presents a new algorithm based on the Mumford-Shah model for simultaneously detecting the edge features of two images and jointly estimating a consistent set of transformations to match them. Compared to the current asymmetric methods in the literature, this fully symmetric method allows one to determine one-to-one correspondences between the edge features of two images. The entire variational model is realized in a multiscale framework of the finite element approximation. The optimization process is guided by an estimation minimization-type algorithm and an adaptive generalized gradient flow to guarantee a fast and smooth relaxation. The algorithm is tested on T1 and T2 magnetic resonance image data to study the parameter setting. We also present promising results of four applications of the proposed algorithm: interobject monomodal registration, retinal image registration, matching digital photographs of neurosurgery with its volume data, and motion estimation for frame interpolation.     

Monitoring post-tsunami vegetation recovery in Phang-Nga province,Thailand, based on IKONOS imagery and field investigations – a contribution to the analysis of tsunami vulnerability of coastal ecosystems

A major tsunami in December 2004 devastated the coastal ecosystems along the Andaman Sea coast of Thailand. Since intact coastal ecosystems provide many important services for local communities at the Andaman Sea, it is crucial to investigate to what extent (in terms of percentage area and speed) the affected ecosystems were capable of recovering after the tsunami. Field measurements and multi-date IKONOS imagery were used to estimate the recovery and succession patterns of coastal vegetation types in the Phang-Nga province of Thailand, three years after the tsunami. Thus, this study contributes to a holistic understanding of the ecological vulnerability of the coastal area to tsunamis. A zone-based change detection approach is applied by comparing two change detection techniques: the first method involves the calculation of a recovery rate based on multi-temporal TNDVI (transformed normalized difference vegetation index) images (TNDVI approach), whereas the second approach is a combined approach of the change vector analysis (CVA). Although these two methods provide different types of information (quantitative for the TNDVI approach, qualitative for the CVA), they are comparable in terms of results and accuracies. The results reveal that recovery processes vary based on the type of the ecosystem and, furthermore, are strongly influenced by human activities. Grasslands, coconut plantations and the mixed vegetation cover could recover faster than the mangroves and casuarina forests. Among the forest ecosystems, recovery rates of casuarina forests were higher than for mangroves, but the recovery area was smaller. This study also discusses the potential and some limitations and inaccuracies of applying high-resolution optical imagery for assessing vegetation recovery at a local scale.     

Stiffness degradation under fatigue in multiaxially loaded non-crimped-fabrics

In this paper results on fatigue of non-crimp-fabrics are presented. After a short introduction to non-crimped-fabrics experimental results of biaxially loaded GFRP tube specimens are presented. An analytical engineering approach for the stiffness degradation of fatigue loaded laminates under arbitrary loads is shown. This approach is based on the classical laminate theory and calculations of cracked representative volume elements, in order to describe the influence of cracks on laminates under different conditions. The application of the model is shown and results are compared with the experimental results.     

The effects of instructional support and learner interests when learning using computer simulations

Within the scope of this study, the effectiveness of two kinds of instructional support was evaluated with regard to the learner’s interests. Two versions of a simulation program about the respiratory chain were developed, differing only in the kind of tasks provided for instructional support: One version contained problem-solving tasks, the other one contained worked-out examples. The focus was on the learner’s interest in the subject and in computers. The first goal of the study was to find to what extent computer simulations incorporating the different kinds of instructional support have positive effects on situational subject-interest. The second goal was to evaluate the interactions between the learner’s interests and the instructional support with regard to the learning results (subdivided into factual knowledge and understanding). Simulations with worked-out examples were shown to have positive effects on the learner’s situational interest in the subject. This was not found to be the case in simulations with problem-solving tasks. Regardless of the kind of instructional support, learners with little interest in the subject were able to achieve significant gains in factual knowledge. However, improvement in understanding was dependent on the kind of instructional support.     

Kontinuierliche Feuchtebestimmung und- regelung bei der Spanplattenfertigung

Zusammenfassung In der Spanplattenindustrie geh?ren die Me?verfahren zur Erfassung der Feuchtigkeit nasser, getrockneter und beleimter Sp?ne zu den wesentlichsten Teilen der vollautomatischen Steuerung und überwachung des Produktionsablaufes. Trocknung, Beleimung und Verpressung sind drei kritische Punkte, an denen der Produktionsablauf mit Hilfe der Feuchtigkeits-überwachung und der daraus abgeleiteten Regelvorg?nge beeinflu?t wird. Die L?sung der damit verknüpften Me?- und Regelprobleme ist für den Fertigungsablauf und die Rentabilit?t der Spanplattenerzeugung au?erordentlich wichtig. Es werden L?sungswege gezeigt, die sich in den letzten vier Jahren praktisch bew?hrt haben.

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Continuous measurement and control of moisture content in particle board manufacture

Summary In particle board industry, the methods for measuring the moisture of wet, dried, and glued particles are the essentials of fully automized control and supervision of the production process. Drying, gluing, and pressing are those critical points affecting manufacture by means of moisture control and the controlling procedures resulting therefrom. The handling of all the measuring and controlling problems connected herewith is of great importance for the manufacturing process and profitability of particle board manufacture. Solutions which have proved reliable in practice during the past four years are dealt with in this paper.

     

Adaptive gain equalizer in high-index-contrast SiON technology

An adaptive gain equalization filter is presented. The filter is based on the resonant coupler principle, a cascade of power couplers and delay lines. Reconfigurability and tuning is achieved by varying coupling strength and delay line length via the thermo optic effect. A device consisting of seven delay line stages was realized in high-index-contrast silicon-oxynitride technology. This device flattens the ASE spectrum of an EDFA to a ripple of less than 0.5 dB over 35 nm. The on-chip losses are 2 dB     

Capacitively coupled transmission line pulsing cc-TLP––a traceable and reproducible stress method in the CDM-domain

This paper describes a new test method called capacitively coupled transmission line pulsing cc-TLP. It is applied to different test circuits which were mounted on specially designed package emulators with a defined background capacitance. The test results are compared with the ESD thresholds obtained by CDM tests. The cc-TLP results correlate well with the CDM data.