Microscopy, light section

Phospholipid molecules form bilayer films or membranes about 5 nm in thickness as illustrated in Fig. XV-10. Vesicles or liposomes are closed bilayer shells in the 100-1000-nm size range formed on sonication of bilayer forming amphiphiles. Vesicles find use as controlled release and delivery vehicles in cosmetic lotions, agrochemicals, and, potentially, drugs. The advances in cryoelec-tron microscopy (see Section VIII-2A) in recent years have aided their characterization [70-72]. Additional light and x-ray scattering measurements reveal bilayer thickness and phase transitions [70, 71]. Differential thermal analysis... 

We confine ourselves here to scanning probe microscopies (see Section VIII-2B) scanning tunneling microscopy (STM) and atomic force microscopy (AFM), in which successive profiles of a surface (see Fig. VIII-1) are combined to provide a contour map of a surface. It is conventional to display a map in terms of dark to light areas, in order of increasing height above the surface ordinary contour maps would be confusing to the eye. 

The green hairy roots cultured in the light for 3 weeks were used for the fluorescent microscopy and transmission electron microscopy (TEM). For the fluorescent microscopy, frozen sections (15 pm in thickness) were prepared using microtome cryostat (HM 500 OM, Microme, Heidelberg, Germany) and sealed with 50% glycerol on glass slides. Localization of chloroplasts was observed by fluorescent microscopy (VANOX AH-3, Olympus). 

Luminescence petrographic techniques (also luminescence microscopy) Thin section petrographic techniques utilizing luminescence or the light emitted from a solid that is excited by an incident beam of some form of energy. 

Besic et al. (1962) have examined undecalcified tooth sections in an infrared microscope in the range 0.76-1.20 n. Hypocalcification spots can be distinguished by infrared microscopy from sections of early caries when they are imbibed in media (water, glycerol, or eugenol) that show them to be similar in appearance when viewed only with visible-light and polarizing microscopes. 

Specimen preparation may be broadly classified into two main areas specimen preparation techniques for transmitted-light microscopy (thin sections, smears, fibers, particulate strews) and specimen preparation techniques for reflected-light microscopy (surface preparation of opaque and nearly opaque materials). However, they are by no means exclusive and, although metals, ores, and opaque minerals may be studied by reflected light only, thin sections, smears, etc., may be studied both by transmitted and by reflected light, e.g., transmitted-light and epifluorescence microscopy. The advantages of such dual observational techniques relate in particular to contrast enhancement (criterion (3)). 

Determinations were made by electron microscopy of sectioned cells, and of isolated PBS. Although the cell size remained the same under different growth conditions the total thylakoid area was reduced to almost half for cells grown in far-red light (Table 2). The PBS size, and possible area occupied on the thylakoid, was determined from sections and isolated PBS. The PBS of mutant 83Y, which showed maximum reduction in the amount of PC were considerably smaller (28 nm x 13 nm) than those of the WT (37 nm x 30 nm). 

Methods BF = bright field LM of tissue impression smears, wet-mounts, stained whole mounts LM = light microscopy PH = phase microscopy DF = dark-field microscopy TEM/SEM = transmission/scanning electron microscopy of sections or of purified or semi-purified virus ELISA = enzyme-linked immunosorbent assay PAb = polyclonal antibodies MAb = monoclonal antibodies DBH = dot blot hybridization ISH = in situ hybridization PCR = polymerase chain reaction RT-PCR = reverse transcription PCR. 

Two nucleation processes important to many people (including some surface scientists ) occur in the formation of gallstones in human bile and kidney stones in urine. Cholesterol crystallization in bile causes the formation of gallstones. Cryotransmission microscopy (Chapter VIII) studies of human bile reveal vesicles, micelles, and potential early crystallites indicating that the cholesterol crystallization in bile is not cooperative and the true nucleation time may be much shorter than that found by standard clinical analysis by light microscopy [75]. Kidney stones often form from crystals of calcium oxalates in urine. Inhibitors can prevent nucleation and influence the solid phase and intercrystallite interactions [76, 77]. Citrate, for example, is an important physiological inhibitor to the formation of calcium renal stones. Electrokinetic studies (see Section V-6) have shown the effect of various inhibitors on the surface potential and colloidal stability of micrometer-sized dispersions of calcium oxalate crystals formed in synthetic urine [78, 79]. 

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