Membrane fracture

Based on the authors experience, membrane fracture frequently occurs during events when membrane is dried out the in-plane hygrothermal stress is a critical driving force in membrane mechanical failure. The in-plane hygrothermal stress can be lowered by reducing the swelling/shrinkage ratio of the membrane, i.e., the dimensional instability of the membrane. 

The sensor is installed in the air intake manifold of the car, measuring the aspirated air mass. The measuring principle requires the membrane to be exposed to the airflow and thereby also to dust and other particles, which are either not removed by the air filter or are inherent in the intake pipe. The impact of such particles on the membrane imposes a shock-type mechanical load, which can cause field failures as well as O-km failures due to membrane fracture. The task was to identify the relevant geometry and material parameters limiting the lifetime of the sensor element and to deduce a model for their effects on membrane stability [11]. 

A series of fully functional sensors were tested until failure (defined for this application as membrane fracture). A sample of the recorded survival times is shown in Figure 5.9.14. 

Compression deliquoring Membrane fracture Loss of air pressure a. Difficulty in maintaining air pressure b. Wetter cakes... 

For complimentary replica or membrane fracture studies, the two silicon pieces from both sides of the sandwich can be analyzed in the frozen hydrated state with scanning electron microscopy techniques (29). The substrate side of the sandwich contains groups of cells fractured at the plasma membrane. The apical half-membrane and the overlaying growth medium were removed to the non-substrate side of the sandwich. The cells fractured at the dorsal surface... 

The SEM is used for study of the surface and bulk structures of membranes. Membranes are prepared by attaching them to the specimen stub and applying a conductive surface coating. Bulk structures are observed for membranes fractured in air or liquid nitrogen, sectioned or critical point dried. Figures 5.24 and 5.25 are examples of the varied structures of typical membranes which can be imaged by this technique. An experimental HDPE microporous membrane has... 

FEM is also a method of determining whether membranes are asymmetric, at least as to the distribution of integral membrane proteins (IMPs). When membranes fracture along the central plane of the bllayer, two Internal... 

If we then introduce a flaw into the system, by poking a pin into the inflated balloon, the balloon will explode, and all this energy will be released. The membrane fails by fast fracture, even though well below its yield strength. But if we introduce a flaw of the same dimensions into a system with less energy in it, as when we poke our pin into a partially inflated balloon, the flaw is stable and fast fracture does not occur. Finally, if we blow up the punctured balloon progressively, we eventually reach a pressure at which it suddenly bursts. In other words, we have arrived at a critical balloon pressure at which our pin-sized flaw is just unstable, and fast fracture just occurs. Why is this ... 

Although freeze-fracture experiments have demonstrated that monomers are assembled into stable tetramers in the membranes, radiation inactivation studies and, later, expression studies revealed that each monomer is a functional water channel (Fig. lc). 

The dimer chains of Ca -ATPase can also be observed by freeze-fracture electron microscopy [119,165,166,172-174], forming regular arrays of oblique parallel ridges on the concave P fracture faces of the membrane, with complementary grooves or furrows on the convex E fracture faces. Resolution of the surface projections of individual Ca -ATPase molecules within the crystalline arrays has also been achieved on freeze-dried rotary shadowed preparations of vanadate treated rabbit sarcoplasmic reticulum [163,166,173,175]. The unit cell dimensions derived from these preparations are a = 6.5 nm b = 10.7 nm and 7 = 85.5° [175], in reasonable agreement with earlier estimates on negatively stained preparations [88]. 

Stretched Polymers MF membranes may be made by stretching (Fig. 20-68). Semicrystalline polymers, if stretched perpendicular to the axis of crystallite orientation, may fracture in such a way as to make reproducible microchannels. Best known are Goretex produced from Teflon , and Celgard produced from polyolefin. Stretched polymers have unusually large fractions of open space, giving them very high fluxes in the microfiltration of gases, for example. Most such materials are very hydrophobic. 

BJ McLaughlin, RB Caldwell, Y Sasaki, T Wood. (1985). Freeze-fracture quantitative comparison of rabbit corneal epithelial and endothelial membranes. Curr Eye Res 4 951-961. 

Figure 2 shows FFEM images of Mal3 (Phyt)2/SQDG (9 1 mol/mol) vesicle membranes in the presence (Fig. 2A, B) or in the absence (Fig. 2C, D) of BR. Small particles were observed in Figure 2A, B, whereas no such particles were observed for pure Mai (Phyt)2/SQDG vesicles. In addition, two fracture faces of the bilayer membranes, a convex surface (a hydrophobic face of an inner leaflet, Fig. 2A) and a concave surface (a hydrophobic face of an outer leaflet, Fig. 2B) exhibited intramembraneous particles, suggesting BR was incorporated into vesicles transmembraneously.

Therefore, a team, led by the University of Alaska-Fairbanks, was formed to study these practical issues (75), including the composition of the ceramic membrane, seals that would join the ceramic and metal materials, membrane performance, and development of a ceramic that would resist warping and fracturing at the high temperatures of the conversion process. 

Epi-illumination Subcellular imaging structures Freeze fracture Preparation of cellular ultrastructures in frozen-hydrated and living state for electron microscopy macromolecular organization of bilayer membranes... 

Subsequent to possible solubilization of membrane-bound proteins, solubilization must be verified. The criteria listed in Table 2 are relevant in assessing whether solubilization has been accomplished. To ascertain whether the solubilized protein has retained biological activity, membrane reconstitution (28) is attempted subsequent to detergent removal (24). Reconstitution is often visualized by electron microscopy employing either negative staining or freeze fracture. 

The process of infection of lupine nodule cells by Rhizobia was examined by the thin-section electron microscopic technique, as well as the freeze-fracture technique. Different membranes such as infection thread membranes, peribacterioid membranes, plasma membranes, membranes of cytoplasmic vesicles, and membranes of the Golgi bodies and ER were stained with uranium-lead, silver, phosphotungstic acid, and ZIO (31). ZIO stained the membranes of the proximal face of the Golgi bodies and endoplasmic reticulum. ZIO staining has given good contrast in thick sections such as a cotyledon cell, a root cell, and an aleurone layer for ER, dictyosomes cisternae, mitochondria, and nuclear envelopes (17,32-37). 

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