Scanning electron microscopic , freeze

Fig. 1.42. Scanning electron-microscopic photographs of different freeze dried products.

Fig. 1.44. Scanning electron-microscopic photographs of a vial containing freeze dried trehalose solution, (a), collapsed product from the bottom of the product (b), shrunk product after 6 months of storage at +20 °C with a RM too high and stored at a too high a temperature (Fig. 6 from [ 1.29]).

Fig. 3.25.1. Porous structure of collagen sponge produced by freezing in a cryogenic bath at -25 °C and subsequently freeze dried (scanning electron microscope, white bar = 1 mm) (from 13.67]).

Maruyama K, Kume N, Okuda M. A scanning electron microscopic observation of chromosomes in freeze-fractured cells of Vicia faba. J Electron Microsc 1985 34 162-168. 

After quick freezing in liquid nitrogen and fracture, another etching method was used at — 90 °C for less than 1 min in a 1.33 x 10-4 Pa chamber. The etched sample was cooled to — 130°C and coated with platinum and carbon in the same vacuum chamber and transferred to the scanning electron microscope at — 130 °C. The observed structure was closer to reality than that obtained by the method previously described. This is called the cryo-SEM technique [32]. CryoSEM images are shown in Fig. 4 which presents the structural change by stretching [16]. 

Representative freeze-dried samples were mounted on aluminum stubs using conductive paint, coated with gold/palladium (60 U0) in a Technics sputter coater and examined in an ETEC Autoscan scanning electron microscope at 10 kV. 

Neat polymers and their blends were studied In dynamic shear field (using RMS) and In constant shear stress field using Rheometrlc Stress Rheometer, RSR. The molecular parameters of polymers and blends were determined by Size Exclusion Chromatography in trichlorobenzene at 14O C. The morphology of freeze-fractured specimens was characterized In Scanning Electron Microscope, SEM, Jeol JSM-35CF. 

The samples were moimted on stubs, freeze dried, coated with gold, examined, and photographed in a Scanning Electron Microscope LEICA S 360. 

The surface morphology of the granules was examined using a scanning electron microscope (Hitachi S-570). The freeze-dried granules were mounted on metal stubs, and the membranes were coated with gold for 6 min. The surfaces were then observed and photographed. 

Microscopic observations were done on a Phillips High Resolution Scanning Electron Microscope. To reveal solid material inside the microcolumn, a freeze-fracture technique was used after samples were washed with methanol and dried under normal conditions. 

Observation by a scanning electron microscope (SEM) shows the detailed porous structures of collagen scaffolds. The funnel-like collagen scaffolds prepared with an ice particulates template having a diameter of 398 jjim and a freezing temperature of -1, -3, -5, and -10°C are shown in Fig. 3.1.2. The template temperature is adjusted to be the same as that... 

Traditional electron microscopy is conducted in high vacuum, which imposes specific efforts to sample preparation. Particles from colloidal suspensions have to be deposited onto an appropriate substrate (e.g. on carbon or silica films) and dried. Alternatively, the suspensions can be shock-freezed and particles are subsequently excavated from the continuous phase by special cryo-preparation techniques (Schmidt et al. 1994, pp. 694—705). The sample preparation can be considerably reduced with environmental scanning electron microscopes (ESEM), which are operated up to 1000 Pa and, thus, even facilitate the analysis of wet surfaces. However, the ease in operation is at the expense of resolution (Danilatos 1993). 

For observing structural preservation of freeze-dried cells at greater details than provided by optical microscopy, a JOEL JSM 35 scanning electron microscope (JEOL Ltd., Tokyo, Japan) was used in this study. Eor improving the quality of SEM images, the freeze-dried cells were coated with a thin layer of Au/Pd in a sputter coater (Ted Pella Inc., Redding, CA, USA). 

At the same time, the surfactant Beycostat A B09 (an add phosphate ester of ethoxylated nonyl phenol) was mixed with a CN suspension and the pH adjusted to 7.5 before freeze-drying for apphcation in solution blending and melt compounding. Scanning electron microscope observation revealed that the Beycostat A B09-coated CNs formed a sticky mixture whereas the CNs without surfactant had a fluffy texture... 

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