Inverters 3-Phase

Fig. 51 Phase diagram for PS-PI diblock copolymer (Mn = 33 kg/mol, 31vol% PS) as function of temperature, T, and polymer volume fraction, cp, for solutions in dioctyl ph-thalate (DOP), di-n-butyl phthalate (DBP), diethyl phthalate (DEP) and M-tetradecane (C14). ( ) ODT (o) OOT ( ) dilute solution critical micelle temperature, cmt. Subscript 1 identifies phase as normal (PS chains reside in minor domains) subscript 2 indicates inverted phases (PS chains located in major domains). Phase boundaries are drawn as guide to eye, except for DOP in which OOT and ODT phase boundaries (solid lines) show previously determined scaling of PS-PI interaction parameter (xodt

Figure 22. Human embryonic kidney cells (A), rat vascular smooth muscle cells (B, C) and human osteoblast-like MG 63 cells (D) in cultures on micropattemed surfaces. A, B PTFE irradiated with UV light produced by a Xe2 -excimer lamp for 30 min in an ammonia atmosphere through a mask with holes 100 pm in diameter and center-to-center distance 300 pm C PE irradiated with Ar ions (energy 150 keV, ion dose lO ions/cm ) through a mask with holes 100 pm in diameter and center-to-center distance 200 pm fullerenes Qo deposited through a mask with rectangular holes with an average size of 128 3 pm per 98 8 pm on glass coverslips. Day 7 after seeding. A native cells in an inverted phase-contrast microscope B, C cells stained with hematoxylin and eosin, Olympus microscope IX 50 D cells stained with fluorescence-based LIVE/DEAD viability/cytotoxicity kit (Invitrogen), Olympus microscope IX 50. Bars 300 pm (A), 200 pm (B, D), Imm (C) [10,11].

Routine observation of cultured is usually carried out by phase contrast microscopy, utilizing the inverted phase contrast microscope. More recently, more detailed observations have become possible utilizing fluorescent tags and inverted fluorescent microscopes. Fluorescent tags currently in use permit the assessment of oxidant status and mitochondrial function as well as the intracellular concentration of sulfhydryl groups, Ca2+,H+,Na+, andK+. 

Fig. 9 Inverted phase contrast microscope equipped with a CCD camera and a laser. Galvano mirrors allow for scanning of the laser focus across the sample...

As stated, biological membranes are normally arranged as bilayers. It has, however, been observed that some lipid components of biological membranes spontaneously form non-lamellar phases, including the inverted hexagonal form (Figure 1.9) and cubic phases [101]. The tendency to form such non-lamellar phases is influenced by the type of phospholipid as well as by inserted proteins and peptides. An example of this is the formation of non-lamellar inverted phases by the polypeptide antibiotic Nisin in unsaturated phosphatidylethanolamines [102]. Non-lamellar inverted phase formation can affect the stability of membranes, pore formation, and fusion processes. So-called lipid polymorphism and protein-lipid interactions have been discussed in detail by Epand [103]. 

Fig. 7. Schematic diagrams of different phases of amphiphiles. Amphiphiles, such as detergents with large head groups (gray) containing only one small hydrophobic chain (tail), can be thought of as cones that pack together to form spherical micelles. Bilayerforming lipids are more cylindrical in shape and pack together into planes. The head groups of nonbilayer lipids occupy less area than the tails and therefore the lipids form inverted phases.

Fitting of the WAG data was not entirely satiafactory, as can be seen from Table II and from Figures 2,3,5, and 6. The trapped oil saturation vs water saturation is important in the water-wet case, so we did not use the inverted phases for the water-wet WAG case, but instead varied the mixing parameter within the range of 0.6 to 0.8 and the value of 3 in the equation ... 

Thus, in most cases a fit could be obtained with the inverted phases with caroon dioxide solubility in a narrower range than the range required of the mixing parameter if the normal phases were used and the mixing parameter was varied. On the other hand, the use of the inverted j ases with carbon dioxide solubility as the only parameter available does not make use of the other features of the Multiflood simulator such as the trapped oil curve and the simulation of the effects of fingering in the way shown successfully before. 

It must be concluded that it would be preferable to construct a new simulator, or a suitable adaptation of the Multiflood simulator or other miscible flooding simulator, to take into account the new physico-chemical aspects of foam or emulsion flow while retaining the otiier valuable capabilities of these simulators, rather than to use the inverted-phase form of the Multiflood simulator. This has been suggested to Todd, Dietrich Chase. 

Several classes of lipids common for the biomembranes can form inverted nonlamellar phases under physiologic conditions (4). The principle ones are phosphatidylethanolamines and monogalactosyldiglycerides. Also, cardiolipins and phos-phatidic acids can form inverted phases in the presence of divalent cations, and phosphatidylserines and phosphatidic acids both form inverted phases at low pH. Moreover, biomembrane lipid extracts and membrane-mimicking lipid compositions form nonlamellar phases if heated above physiologic temperatures, dehydrated, or treated with divalent cations (5-7). 

The propensity of membranes to fuse correlates with the fraction of inverted phase-forming lipids conversely, membrane fusability is reduced with an increase of the lipid fraction that inhibits inverted phase formation. Substantial evidence suggests that the mechanism of lipid membrane fusion is related to the mechanism of lamellar/inverted phase transitions (23). The intermediates that form in membrane fusion seem to be identical to those that form during the transformations between lamellar, bicontinuous inverted cubic and inverted hexagonal lipid liquid-crystalline phases, and these transitions can be used successfully as a model for studying the lipid membrane fusion mechanism and kinetics. 

Figure 4 The modified stalk mechanism of membrane fusion and inverted phase formation, (a) planar lamellar (La) phase bilayers (b) the stalk intermediate the stalk is cylindrically-symmetrical about the dashed vertical axis (c) the TMC (trans monolayer contact) or hemifusion structure the TMC can rupture to form a fusion pore, referred to as interlamellar attachment, ILA (d) (e) If ILAs accumulate in large numbers, they can rearrange to form Qn phases, (f) For systems close to the La/H phase boundary, TMCs can also aggregate to form H precursors and assemble Into H domains. The balance between Qn and H phase formation Is dictated by the value of the Gaussian curvature elastic modulus of the bIlayer (reproduced from (25) with permission of the Biophysical Society) The stalk in (b) is structural unit of the rhombohedral phase (b ) electron density distribution for the stalk fragment of the rhombohedral phase, along with a cartoon of a stalk with two lipid monolayers merged to form a hourglass structure (reproduced from (26) with permission of the Biophysical Society).

Siegel DP. The modified stalk mechanism of lameUar/inverted phase transitions and its implications for membrane fusion. Biophys. J. 1999 76 291-313. 

There are interesting recent reports linking membrane fusion to cubic lipid phases [9] or to reversed (or "inverted") phases [62]. So-called "inter-lamellar attachments", formed between the bilayers of liposomes on fusion, show freeze-fracture electron micrograph textures identical to those of a cubic lipid-water phase (see Fig. 5.9). The inter-lamellar attachments seem to be identical to "lipidic particles" described earlier [63]. It is also interesting to note that diacylglycerols, secondary messengers from the Pl-cycle, produce fusion in... 

The approach is to begin with 0 very small and to phase the spectrum so that the doublet lines are in antiphase. As 0 increases the doublet intensity will decrease and become zero when 0 is 90", whilst beyond this the doublet reappears but with inverted phase (Fig. 3.53). If it is necessary to perform the calibration with an AaX group, the delay A should be 1/4J and it is the outer lines of the triplet that behave as described above whilst the centre line remains unaffected. When calibrating lower powers for the purpose of broadband decoupling, it is usually more convenient to set the duration of the 0 pulse according to the decoupler bandwidth required (Section 9.2) and to vary the output attenuation to achieve the null condition. 

Figure 3.53. Indirect calibration of the proton pulse width with carbon observation using the sequence of Fig. 3.52. As the proton pulse width increases the carbon signal diminishes until it disappears at the H(90°) condition. Going beyond this causes the signal to reappear but with inverted phase (the same phase correction is used for all spectra). The sample is C-labelled methanoic acid in D2O.

Obtained by a visual estimation of lipid droplets in five microscopic fields of heart cells in culture under an inverted phase contrast microscrope (10 x 40). Range 0 to 4. 

Figure 16.1 Relationship between molecular shape, aggregate structure in dilute dispersions, phase behavior and packing parameter. Micellar phase (L,), cubic micellar phase (I), hexagonal phase (H), bicontinuous cubic phase (Q), La lamellar phase. Subscripts I and II indicate normal and inverted phases, respectively. From M. Scarzello, Aggregation Properties of Amphiphilic DNA-Carriers for Cene Delivery, Ph. D. Thesis University of Groningen, p 6, 2006...

Inverted phase-contrast microscope (e g., Nikon Diaphot)... 

Use a Pasteur pipet to transfer the dissociated cells to a 3 5-mm polystyrene Petn dish placed in the holder on the stage of the Inverted phase contrast microscope (see Note 5). 

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