NECTAR—A fission neutron radiography and tomography facility

NECTAR (Neutron Computerized Tomography and Radiography) is a versatile facility for radiographic and tomographic investigations as well as for neutron activation experiments using fission neutrons.The radiation sources for this facility are two plates of highly enriched uranium situated in the moderator vessel in FRM II. Thermal neutrons originating from the main fuel element of the reactor generate in these plates fast neutrons. These can escape through a horizontal beam tube without moderation. The beam can be filtered and manipulated in order to reduce the accompanying gamma radiation and to match the specific experimental tasks.A summary of the main parameters required for experimental set-up and (quantitative) data evaluation is presented. The (measured) spectra of the neutron and gamma radiations are shown along with the effect of different filters on their behavior. The neutron and gamma fluxes, dose rates, L/D-ratios, etc. and the main parameters of the actually used detection systems for neutron imaging are given, too.     

Establishment of oral mucosa phenotype in vitro in correlation to epithelial anchorage

We have identified a Saccharomyces cerevisiae protein, Cyk1p, that exhibits sequence similarity to the mammalian IQGAPs. Gene disruption of Cyk1p results in a failure in cytokinesis without affecting other events in the cell cycle. Cyk1p is diffused throughout most of the cell cycle but localizes to a ring structure at the mother-bud junction after the initiation of anaphase. This ring contains filamentous actin and Myo1p, a myosin II homologue. In vivo observation with green fluorescent protein-tagged Myo1p showed that the ring decreases drastically in size during cell division and therefore may be contractile. These results indicate that cytokinesis in budding yeast is likely to involve an actomyosin-based contractile ring. The assembly of this ring occurs in temporally distinct steps: Myo1p localizes to a ring that overlaps the septins at the G1-S transition slightly before bud emergence; Cyk1p and actin then accumulate in this ring after the activation of the Cdc15 pathway late in mitosis. The localization of myosin is abolished by a mutation in Cdc12p, implicating a role for the septin filaments in the assembly of the actomyosin ring. The accumulation of actin in the cytokinetic ring was not observed in cells depleted of Cyk1p, suggesting that Cyk1p plays a role in the recruitment of actin filaments, perhaps through a filament-binding activity similar to that demonstrated for mammalian IQGAPs.     

Design,development and in-vitro evaluation of diclofenac taste-masked orodispersible tablet formulations

Context: Fast onset of action is prerequisite for acute pain medication. A palatable orodispersible medicine of diclofenac providing rapid analgesic effect should improve patient compliance and treatment.

Objective: In the present study, diclofenac taste-masked orodispersible tablets (ODTs) with fast release characteristics were developed. Different taste-masking approaches and formulation concepts were screened in vitro for candidate selection.

Materials and methods: Diclofenac was used as free acid. Five taste-masked microgranule formulations were prepared by wet granulation and/or coating processes, and compressed to ODTs. Citric acid (pH-modifying agent) and Eudragit® E PO (amino methacrylate copolymer) were used as taste-masking agents. Evaluation criteria were (i) disintegration time, (ii) processability and (iii) in-vitro dissolution profiles in simulated saliva (pH 7.4, 5?mL, 3?min) and compendial pH-change media (paddle, 50?rpm). The prototypes were compared to reference ODTs (without taste-masking). Most suitable ODT prototypes were selected and further evaluated for taste-masking efficiency using an electronic tongue.

Results and discussion: In simulated saliva, the drug was slower released from the prototypes (between 1.1% and 15.5%) than from reference ODTs (23.7%). Less dissolved particles are thus expected in vivo for taste perception. Two ODT prototypes showed fast and complete drug release in phosphate buffer. The formulation providing the most efficient taste-masking was selected guided by electronic tongue data.

Conclusion: A novel palatable and fast acting diclofenac ODT formulation was successfully developed. Formulation design, development and in-vitro evaluation used in this study may serve as rational approach for manufacturing taste-masked orodispersible dosage forms.     

Core balance ground fault protection of motors on a low-resistancegrounded, medium-voltage system

The core balance current transformer is the basis for sensitive ground fault protection of motors. All phase conductors pass through the same opening in the current transformer so that it senses only zero sequence or ground current. Possible sources of nonfault relay current include current transformer error, harmonics, and unbalanced currents through impedances to ground, especially capacitances. The core balance connected ground fault relay is usually an instantaneous type, or a time-delay type of the short time or very inverse characteristic. The standards provide typical ranges of relay settings. They do not provide a procedure for determining the minimum settings that will not result in nuisance trips from nonfault currents nor the maximum settings that will provide adequate protection. This paper develops that procedure     

Prediction of intestinal drug absorption properties by three-dimensional solubility parameters

PURPOSE: The purpose of this study was to investigate the use of solubility parameters for the prediction of gastrointestinal absorption sites and absorption durations of drugs. METHODS: Three-dimensional solubility parameters of drug substances were calculated using an advanced parameter set based on the group contribution methods of Fedors and Van Krevelen/Hoftyzer. The results of the calculations were illustrated via Bagley diagram and related to absorption data reported in the literature. RESULTS: Solubility parameters of drugs which are known to be absorbed over a long period in human's digestive tract were found in a limited area within the Bagley diagram. From the three-dimensional solubility parameters of these substances, a region for optimal absorption with the centre coordinates delta(v)=20.3 (J x cm(-3))(0.5) and delta(h)=11.3 (J x cm(-3))(0.5) could be derived. Drugs with absorption sites along the whole gastrointestinal tract were found in this area. Drugs which are preferably absorbed from upper parts of the intestine are located in another typical region with partial solubility parameters delta(h) of more than 17 (J x cm(-3))(0.5). CONCLUSIONS: The method which is presented in this paper appears as a simple but effective method to estimate the absorption behaviour of new substances in drug research and development.     

Nanomagnetic logic: compact modeling of field-coupled computing devices for system investigations

In this paper we investigate error rates of nanomagnetic logic devices with perpendicular magnetization by compact modeling. Two different types of nanomagnets for information propagation and logic computing are introduced. The switching behavior of field-coupled nanomagnets is measured and analyzed. A compact model is derived from physics and experimental results are applied to the magnetic compact model. General requirements for fabrication parameters and clocking fields for reliable operation are extracted. We perform simulations and measurements on single devices to demonstrate the accuracy of the macromodel. Simulations on complex systems show that the error rate of a field-coupled magnetic system strongly depends on the variation of the switching field and the strength of the coupling field between the nanomagnets. The error rate of a 1-bit full adder is investigated for varying dot parameters. The results demonstrate the importance of fast simulation tools for investigations on the design of nanomagnetic computing devices and systems.     

A network multi-processor for experiments in parallelism

Although both shared memory and loosely coupled parallel computing systems are now common, many still do not offer an easy way to design, implement, and test parallel algorithms. Our system provides software tools that make possible a variety of connection structures between processes. These structures are said to form a 'Network Multi-Processor', which is implemented on a local area network of heterogeneous UNIX-based timesharing computers, plus a set of processor boards dedicated to an application so that accurate timing measurements can be made. We explain how these tools have been used both to aid parallel algorithm development and to explore the properties of different computer interconnection methods.