Improved column-switching liquid chromatographic method for the determination of the enantiomers of mefloquine

A liquid chromatographic method for the determination of the enantiomers of mefloquine has been improved. The chromatography involved two columns: an achiral cyanopropyl stationary phase for the quantification of (+/-)-mefloquine and a chiral naphthyl-urea stationary phase for the determination of the enantiomeric ratio. Compared with the previous method, which needed two detectors, this one used one detector-integrator to which the two columns are connected alternately by an automated column-switching system. The method is suitable for the quantification (0.05 microgram/ml) of mefloquine and the determination of enantiomeric ratios from 500-microliters plasma samples with ultraviolet detection.     

Cisapride reduces neonatal postoperative ileus: randomised placebo controlled trial

AIM: To assess the efficacy of cisapride in reducing ileus persisting to the tenth postoperative day after neonatal abdominal surgery. METHODS: A prospective, randomised, double blind trial comparing rectal cisapride (1.4-2.3 mg/kg/day) with placebo over seven days was undertaken in 33 neonates. RESULTS: Seven of 12 (58%) patients receiving placebo and eight of 11 (73%) receiving cisapride achieved a first sustained feed during treatment. Of those receiving cisapride, the first sustained feed occurred at 2.3 days (SEM 0.6) compared with 4.7 days (SEM 0.8) with placebo. By the seventh day the mean daily net enteral balance was 69 (SEM 18) ml/kg in the cisapride subgroup and 17 (SEM 8) ml/kg for those receiving placebo. Stool was passed on 6.3 (SEM 0.4) treatment days in the cisapride subgroup compared with 4.1 (SEM 1.0) treatment days in the placebo subgroup. CONCLUSION: Cisapride is effective in neonates with a prolonged ileus after abdominal surgery.     

Brief Overview of Recent Developments on Negative Phase–Velocity Mediums (alias Left–Handed Materials)

This brief overview covers a rapidly occurring development in the area of microwave composite materials: isotropic dielectric–magnetic mediums wherein the phase velocity vector and the time–averaged Poynting vector are oppositely directed. Such materials have also been inappropriately designated as left–handed materials. Ramifications for aberration–free lenses, homogenization approaches, and complex mediums are also presented.     

Exploring aspects of cell intelligence with artificial reaction networks

The Artificial Reaction Network (ARN) is a Cell Signalling Network inspired connectionist representation belonging to the branch of A-Life known as Artificial Chemistry. Its purpose is to represent chemical circuitry and to explore computational properties responsible for generating emergent high-level behaviour associated with cells. In this paper, the computational mechanisms involved in pattern recognition and spatio-temporal pattern generation are examined in robotic control tasks. The results show that the ARN has application in limbed robotic control and computational functionality in common with Artificial Neural Networks. Like spiking neural models, the ARN can combine pattern recognition and complex temporal control functionality in a single network, however it offers increased flexibility. Furthermore, the results illustrate parallels between emergent neural and cell intelligence.     

Structural analysis and optimization of tall buildings connected with skybridges and atria

Multi-level skybridges and atria between tall buildings make possible a new urban paradigm that has the potential to dramatically reduce resource consumption, air pollution, and traffic accidents. Structural analysis and optimization methods and results are presented for tall buildings connected with roller or hinge-skybridges at multiple levels and atria between buildings. Generic building systems were studied with controlled factors such as number of buildings, equal-height vs. variable-height, skybridge connection type, site seismicity and wind intensity, and presence/absence of skybridges and atria. The 48 optimization problems held all other factors constant such as building width, shape, configuration, and spacing. A simplified lateral load analysis model is described which makes optimization of large systems possible. The simplified lateral load analysis model was compared to a finite element model for accuracy. An optimization strategy was developed involving gradient and evolutionary algorithms. Results show that atria and hinge-connected skybridges reduced the total structural volume by as much as 10 %.     

Integrated optical polarization filtration via sculptured-thin-film technology

Abstract

The viability of combining chiral sculptured thin films with a standard Mach-Zehnder fibre interferometer to produce a passive, lossless, inline, polarization router and combiner is demonstrated. The spectral response of the device is calculated with respect to the input of orthogonal polarizations which are shown to be either efficiently routed to different output ports or combined at one port.