Lipid domain morphologies in phosphatidylcholine−ceramide monolayers

In cells, one of the main roles of ceramide-enriched membrane domains is to recruit or exclude intracellular signaling molecules and receptors, thereby facilitating signal transduction cascades. Accordingly, in model membranes, even low contents of ceramide segregate into lateral domains. The impact of the N-acyl chain on this segregation and on the morphology of the domains remains to be explored. Using Langmuir monolayers, we have systematically studied binary mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and ceramide (2:1, molar ratio) and varied the N-acyl chain length of ceramide from 2 to 24 carbon atoms (Cer2 to Cer24). Fluid Cer2, Cer6, and Cer8/DMPC mixtures were miscible at all surface pressures. Longer ceramides, however, formed surface pressure-dependent immiscible mixtures with DMPC. The domain morphology under fluorescence microscopy after including a trace amount of fluorescent NBD-phosphatidylcholine into DMPC/Cer mixtures was found to be very sensitive to the N-acyl chain length. Shorter ceramides (Cer10-Cer14) formed flower-like (seaweed) domains, whereas longer ceramides (N-acyl chain length >14 carbon atoms) formed round and regular domains. We attribute the formation of the flower patterns to diffusive morphological instabilities during domain growth

Classification of Spruce and Pine Trees Using Active Hyperspectral LiDAR

Most forest inventories based on the use of remote-sensing data produce the required species-specific information by fusing data from different sources (e.g., Light Detection And Ranging (LiDAR) and spectral data). We tested an active hyperspectral LiDAR instrument in a laboratory measurement of spruce and pine trees to find out whether these species could be separated by means of combined range and reflectance measurements. An analysis focused on those pulses that had penetrated through the foliage improved the classification accuracies of the species with otherwise highly similar reflectance properties. Based on a careful selection of the classification features, 18 spruce and pine trees could be classified with accuracies of 78%-97% using independent training and validation data acquired by separate scans. The results denote the potential of using active hyperspectral measurements for species classification

Lipid removal enhances separation of oat grain cell wall material from starch and protein

v2011o