New model for performance prediction in fixed-bed reactors based on the approach of the unused bed zone.

In the present study a practical model useful for designers dealing with pilot scale reactors for pollutant control has been developed. Investigations were undertaken for a single-component lead study on New Zealand clinoptilolite at the temperature of 25+/-1 degrees C. Fifteen runs under different operating conditions such as particle characteristics (expressed as d*(p)/D), column geometry (as l*/D) and flow speed (as R*e) have been performed. The results were interpreted by a response surface method (RSM) from which an equation giving the unused bed zone (UBZ) was obtained. From those dimensionless parameters, a sequence of contour plots was drawn, making it easy for a designer to choose optimum design parameters while controlling the operation performance. The flow rate (R*e) range was established over the laminar flow conditions from 1 to 8, (l/D*) was extended from 7 to 20 and (d(p)/D*) varied from 3% to 10%. Optimization of performance of the reactor as UBZ could vary from 10% to 40% of the material operating capacity.

Matemone, a new bioactive bromine-containing oxindole alkaloid from the indian ocean sponge Iotrochota purpurea.

A new bioactive bromine-containing oxindole alkaloid, matemone (1), was isolated from the Indian Ocean sponge Iotrochota purpurea, together with the known 6-bromoindole-3-carbaldehyde. The structures were elucidated on the basis of spectral and chemical data. Compound 1 shows mild cytotoxicity against three cancer cell lines and marginal antibacterial activity against Staphyloccocus aureus. DNA intercalant screening demonstrated DNA interactions with 1. Both compounds inhibit division of sea-urchin eggs.

Dipole localization in patients with epilepsy using the realistically shaped head model.

Dipole sources were localized in 3 patients with epilepsy using both the realistically shaped head model and the 3-sphere model. Interictal spikes were recorded from 63 closely spaced scalp electrodes. The scalp, skull, and brain surfaces were digitized from a MRI of each patient's head, and each surface was tessellated by 1600 triangles. Single dipole fits to the EEG were performed using both the realistically shaped head model and the 3-sphere model. The 2 models localized dipoles to positions that differed from one another by 1-3 cm. For dipoles localized to the temporal lobe, the most important difference between models was that the realistically shaped head model localized the dipole lower in the brain than the 3-sphere model. The realistically shaped head model was more in accordance with the ECoG findings than the 3-sphere model.

Relationship between muscle tone changes, sawtooth waves and rapid eye movements during sleep.

'Sawtoothed' waves occur during rapid eye movement (REM) sleep, but their source as well as their function is not known. We studied the onset of sawtooth waves (STW) in relation to the onset of muscle tone reduction (MTR) and to REM during 20 polysomnographic recordings in 11 normal volunteers. Seventy-seven (85%) of a total of 91 REM sleep cycles were used for further analysis, because within a 1000 s interval they showed a relatively stereotyped sequence of events: a generalized body movement, followed by MTR, then the appearance of STW, and ending with the first REM. The first STW often occurred during the electrographic stage II period prior to the beginning of the REM, by which time muscle tone was either already at or close to the tone level of the REM sleep period in all subjects. The overall mean onset time of MTR was 267 s (range 89-660 s), STW was 378 s (range 169-779), and REM was 448 s (range 265-849); their differences were highly significant (F = 27.1, df 2,20, P < 0.001). Our data suggest that a predictable sequence of muscle tone reduction, then STW, and then REM, precedes the generally accepted onset of the REM sleep period, and may have implications for the redesignation of physiologic REM sleep onset.