Influence of Spacer Design and Module Geometry on the Filtration Performance during Skim Milk Microfiltration with Flat Sheet and Spiral-Wound Membranes.

Spacer design in spiral-wound membranes (SWMs) significantly affects the axial pressuredrop in the flow channel but also the deposit layer removal. However, the effects of the spacerdesign and feed flow distribution in the module on the filtration performance have not yet beeninvestigated during the highly fouling-susceptible fractionation of proteins from skim milk bySWMs. Therefore, a parallel spacer with no turbulence promotion and a less homogeneous feedflow distribution in the SWM was compared to a diamond spacer with regard to its impact ondeposit formation and filtration performance. The experiments were conducted in a flat sheet testcell and in SWMs. The parallel spacer induced a more homogeneous deposit layer formation.However, no difference in filtration performance could be observed in the experiments with the testcell. Even though deposit layer formation dominates the microfiltration, its amount and spatialdistribution could not be directly linked to the filtration performance. Furthermore, both spacerswere assessed in SWM. Despite the higher crossflow velocity applicable in the more open channelsof the parallel spacer, the performance of the parallel spacer was inferior to the diamond spacer.This was independent of the viscosity of the feed. Due to the high curvature of the membrane sheetsclose to the permeate collection tube, the cross-section of the flow channels in the SWM equippedwith the parallel spacer was reduced. This resulted in a distinctly lower deposit layer control andperformance, which could not be compensated by the resulting higher crossflow velocity far fromthe permeate collection tube.

High-throughput analysis of stimulus-evoked behaviors in Drosophila larva reveals multiple modality-specific escape strategies.

All organisms react to noxious and mechanical stimuli but we still lack a complete understanding of cellular and molecular mechanisms by which somatosensory information is transformed into appropriate motor outputs. The small number of neurons and excellent genetic tools make Drosophila larva an especially tractable model system in which to address this problem. We developed high throughput assays with which we can simultaneously expose more than 1,000 larvae per man-hour to precisely timed noxious heat, vibration, air current, or optogenetic stimuli. Using this hardware in combination with custom software we characterized larval reactions to somatosensory stimuli in far greater detail than possible previously. Each stimulus evoked a distinctive escape strategy that consisted of multiple actions. The escape strategy was context-dependent. Using our system we confirmed that the nociceptive class IV multidendritic neurons were involved in the reactions to noxious heat. Chordotonal (ch) neurons were necessary for normal modulation of head casting, crawling and hunching, in response to mechanical stimuli. Consistent with this we observed increases in calcium transients in response to vibration in ch neurons. Optogenetic activation of ch neurons was sufficient to evoke head casting and crawling. These studies significantly increase our understanding of the functional roles of larval ch neurons. More generally, our system and the detailed description of wild type reactions to somatosensory stimuli provide a basis for systematic identification of neurons and genes underlying these behaviors.