Fluffy layer

Careful examination of the yellowish sediment obtained after spinning down the crude mitochondrial fraction showed it was frequently overlaid with loosely packed, fluffy material —the fluffy layer. Experiments from de Duve s and, later, Novikoff s laboratories in the 1950s demonstrated that the lighter, lysosomal fraction was enriched in a number of hydrolases including acid phosphatase, aryl sulphatase, B glucuronidase, RNAase, and a peptidase, cathepsin. All the enzymes had optimal pHs in the acid range (pH 5-pH 6). Density... 

Colloid stabilization with amphiphilic polymers [2,114,115] requires the formation of a thick polymer layer around each particle in order to create a repulsive steric force that overcomes the van der Waals attraction. This is usually done by adsorbing on the colloidal particle a polymer solution in a good solvent, which builds up on the surface a fluffy layer with a thickness of the order of the radius of gyration of isolated polymer chains, in general of the order of a few hundred angstroms. 

Loffler, A., Leipe, T., Emeis, K. C., 2000. The fluffy layer in the Pomeranian Bight (western Baltic Sea) geochemistry, mineralogy and environmental aspects. Meyniana, 52, 85-100. 

The model system allows also a basin wide description of the transport of suspended particulate matter (SPM), which can be transported near the seabed within the so-called fluffy layer and is strongly affected by surface waves in coastal waters. Understanding the settling and resuspension of SPM in response to waves and currents is of great importance to assess the transports of material discharged by rivers from the coastal regions to the final deposit in the sediments of central basins. 

The simulated distribution of fluffy material at the sea bottom in the southwestern Baltic after a period of 60 days with realistic wind forcing is shown in the left panel of Fig. 19.13. Obviously, the initially homogeneous fluffy layer, which started with a density of 0.1 g/crn , is nearly completely eroded from shallow regions above 30 m. On the contrary, deposition of material has built accumulations at the rims of the adjacent deeper basins. A time series of... 

FIGURE 19.13 Redistribution of an initial fluffy layer of 0.1 g/citr after 60 days of strong wind forcing (left) and simulated frequency of occurrence of fluff resuspension (%) during 9 model months (right). 

The frequency of occurrence plot given in the right panel of Fig. 19.13 confirms that the regions shallower than 30 m are potential erosion areas, where fluffy layers are washed off with a probability of 10% or more. Naturally, the erosion area is smaller and is affected with lower frequencies if the threshold for incident movement is higher, as for example 1.2 cm/s for the bed-load transport of fine sand, or 2 cm/s for its resuspension. 

In addition, a fluffy layer sample of the 4 cm above the sediment/water boundary as well as a corresponding water sample representing the water phase directly above the sediments were obtained. Furthermore, the pore water of the first two sediment layers was separated and analysed. 

Tab. 2 Results of the organic geochemical analysis applied to fluffy-layer sample (FL), the first two sediment layers (TKS 0-2 and 2-4) of the current sediment cores and to a sample of the corresponding water column (TKS 4-0). (n.d.= below detection limit)...

The fluffy-layer sample revealed the same compounds as in the sediment samples, the screening illustrated additionally all 4 HCHs (a-5) and HCB, not detected in the water samples. 

Centrifuge this preparation at 200,000g for 40 min (fixed angle rotor rotor brake on) to remove the PercoU from the synaptosome suspension The synaptosomes sediment as a fluffy layer on a tight, glassy PercoU pellet (see Note 9). 

The crude metaphase extract is centrifuged at 55,000 rpm for 4 hr in an SW55 rotor [Beckman Instruments (Canada) Inc.], after which the supernatant, which is found between the lipid cap and the white, fluffy layer on top of the pellet, is collected. The supernatant is divided into 100-/xl samples, flash frozen in liquid nitrogen, and stored at -80 C. When equal volumes of the metaphase cytosol and extracts containing in v/tro-assembled nuclei are mixed together and incubated at 19°C, NE disassembly and chromosome condensation can be seen within 60 min (Fig. 1C). 

Fluffy layer. When the coating is partial (meaning that the deposited layer does not form dense, continuous coating), 7c comes out to be between 24 and 28 mN/m. In this case, wetting is total for silicone oils, although the surface is less sensitive to external conditions than the bare surface (which has a much higher 7c)-... 

The lysosomes in human liver had more heterogeneous migration characteristics upon fractionation than those in rat liver. A fluffy layer seen in tlie rat fractionation procedure is thus not seen so clearly marked in... 

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