Comparison of Acrylamide and Agar Gels by Freeze-Etching

1977 ◽  
Vol 35 ◽  
pp. 606-607
Author(s):  
Russell L. Steere ◽  
Eric F. Erbe
Keyword(s):  
Electron Microscope ◽  
Sodium Hydroxide ◽  
Sodium Hypochlorite ◽  
Chromic Acid ◽  
Distilled Water ◽  
Thin Sheets ◽  
Acid Cleaning ◽  
Agar Gels ◽  
Freeze Etching ◽  
Water Cut

Thin sheets of acrylamide and agar gels of different concentrations were prepared and washed in distilled water, cut into pieces of appropriate size to fit into complementary freeze-etch specimen holders (1) and rapidly frozen. Freeze-etching was accomplished in a modified Denton DFE-2 freeze-etch unit on a DV-503 vacuum evaporator.* All samples were etched for 10 min. at -98°C then re-cooled to -150°C for deposition of Pt-C shadow- and C replica-films. Acrylamide gels were dissolved in Chlorox (5.251 sodium hypochlorite) containing 101 sodium hydroxide, whereas agar gels dissolved rapidly in the commonly used chromic acid cleaning solutions. Replicas were picked up on grids with thin Foimvar support films and stereo electron micrographs were obtained with a JEM-100 B electron microscope equipped with a 60° goniometer stage.Characteristic differences between gels of different concentrations (Figs. 1 and 2) were sufficiently pronounced to convince us that the structures observed are real and not the result of freezing artifacts.

High Resolution Stereography of Complementary Freeze-Fracture Replicas Reveals the Presence of Depressions Opposite Membrane Associated Particles of Split Membranes

1971 ◽  
Vol 29 ◽  
pp. 442-443
Author(s):  
Russell L. Steere
Keyword(s):  
High Resolution ◽  
Cardiac Muscle ◽  
Electron Micrographs ◽  
Chromic Acid ◽  
Freeze Fracture ◽  
Distilled Water ◽  
Fine Scale ◽  
Acid Cleaning ◽  
Cleaning Solution

Complementary replicas have revealed the fact that the two common faces observed in electron micrographs of freeze-fracture and freeze-etch specimens are complementary to each other and are thus the new faces of a split membrane rather than the original inner and outer surfaces (1, 2 and personal observations). The big question raised by published electron micrographs is why do we not see depressions in the complementary face opposite membrane-associated particles? Reports have appeared indicating that some depressions do appear but complementarity on such a fine scale has yet to be shown.Dog cardiac muscle was perfused with glutaraldehyde, washed in distilled water, then transferred to 30% glycerol (material furnished by Dr. Joaquim Sommer, Duke Univ., and VA Hospital, Durham, N.C.). Small strips were freeze-fractured in a Denton Vacuum DFE-2 Freeze-Etch Unit with complementary replica tooling. Replicas were cleaned in chromic acid cleaning solution, then washed in 4 changes of distilled water and mounted on opposite sides of the center wire of a Formvar-coated grid.

Retention of 3-Dimensional Contours by Replicas of Freeze-Fracturcd Specimens

1971 ◽  
Vol 29 ◽  
pp. 242-243
Author(s):  
Russell L. Steere
Keyword(s):  
Electron Beam ◽  
Cardiac Muscle ◽  
Electron Scattering ◽  
Chromic Acid ◽  
Freeze Fracture ◽  
Distilled Water ◽  
3 Dimensional ◽  
Acid Cleaning ◽  
Ice Surface ◽  
Cleaning Solution

Electron micrographs of complementary replicas prepared by either the freeze-fracture or the freeze-etch procedure have often been disappointing. One replica may look excellent whereas the complement, produced simultaneously in the same system, may look worthless. At least part of this complication may be explained by the fact that these replicas retain much of the 3-dimensional contours of the replicated ice surface when dried on a Formvar film. If the desired part of such a replica is oriented in the microscope in such a position that it is vertical to the beam it usually looks good. However, if the desired area happens to be other than vertical to the electron beam, the resultant image may be somewhat distorted if the angle is slight, or may be completely obscurred by electron scattering if the angle is steep.Dog cardiac muscle perfused with glutaraldehyde, washed in distilled water, then transferred to 30% glycerol (furnished by Dr. Joaquim Sommer, Duke Univ.) was freeze-fractured at -196° in a Denton DFE-2 Freeze-Etch Unit, shadowed with Pt from a C point, and replicated with C. The replicas were cleaned of biological remains in chromic acid cleaning solution, then mounted on Formvar support films.

Observations on the Structure of Ta2O5

1972 ◽  
Vol 30 ◽  
pp. 540-541
Author(s):  
P. S. Kotval ◽  
C. J. Dewit
Keyword(s):  
Electron Microscope ◽  
Structural Features ◽  
Amorphous Structure ◽  
Polished Surface ◽  
Distilled Water ◽  
Anodic Films ◽  
Amorphous Films ◽  
Beam Heating ◽  
Diffraction Patterns ◽  
Hexagonal Arrays

The structure of Ta2O5 has been described in the literature in several different crystallographic forms with varying unit cell lattice parameters. Earlier studies on films of Ta2O5 produced by anodization of tantalum have revealed structural features which are not consistent with the parameters of “bulk” Ta2O5 crystalsFilms of Ta2O5 were prepared by anodizing a well-polished surface of pure tantalum sheet. The anodic films were floated off in distilled water, collected on grids, dried and directly examined in the electron microscope. In all cases the films were found to exhibit diffraction patterns representative of an amorphous structure. Using beam heating in the electron microscope, recrystallization of the amorphous films can be accomplished as shown in Fig. 1. As suggested by earlier work, the recrystallized regions exhibit diffraction patterns which consist of hexagonal arrays of main spots together with subsidiary rows of super lattice spots which develop as recrystallization progresses (Figs. 2a and b).

Scanning electron microscope evaluation of chlorhexidine gel and liquid associated with sodium hypochlorite cleaning on the root canal walls

2010 ◽  
Vol 110 (5) ◽  
pp. e82-e87 ◽  
Author(s):  
Marcia Carneiro Valera ◽  
Adriana Chung ◽  
Márcia Maciel Menezes ◽  
Carlos Eduardo Fernandes Fernandes ◽  
Cláudio Antonio Talge Carvalho ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Sodium Hypochlorite ◽  
Root Canal ◽  
Chlorhexidine Gel ◽  
Scanning Electron

CONCLUSION While cleaned silica-based glass surfaces have similar surface compositions, their susceptibility to strongly adsorbing organic contaminant s depends strongly on the glass composition and the cleaning procedure. For the three glass species exam-ined: silica, aluminoborosilicate, and sodalime glass , the glass surfaces behave similarly after chromic acid cleaning. They show significant differences in their properties followin g a dry cleaning procedure, such as pyrolysis or UV/ozone cleaning. The cleaned silica surfaces show a high susceptibility to adsorbing or-ganic contamination following pyrolysis cleaning, while the pyrolyzed sodalime glass appears to be virtually immune to strongly adsorbing organic molecules. Py-rolyzed aluminoborosilicate glass shows an intermediate susceptibility to adsorb-ing organic contaminants. The chromic acid cleaned glass surfaces all show an in-termediate susceptibility to contamination by adsorbed organic molecules. Thus, it may be an oversimplification to consider a clean glass surface as a high energy substrate that is bound to attract ambient organic contamination. The wettability behavior of the cleaned glass surfaces showed features associ-ated with their exposed chemical functions. The non-dispersive interaction energy between glass and water as a function of pH showed evidence of charging of the surface silanol groups. The point of zero charge for these surface chemical func-tions was observed at pH 3. An estimate of the non-dispersive interaction energy between glass and water at the point of zero charge enables a reasonable estima-tion of the density of surface silanol groups on the cleaned glass. The trends ob-served for the surface charge as a function of pH correlate with the observed sus-ceptibility for adsorbing organic contamination to the cleaned glass surfaces. Charge-adsorbed surfactant monolayers indicated a negative surface charge on the cleaned glass, as expected for silica-based glass surfaces at neutral pH. The wettability of grafted self-assembled octadecylsilane monolayers indicated high quality coatings on the cleaned glass surfaces. The coating quality was identical for all three glass species following chromic acid cleaning. The UV/ozone cleaned glass surfaces showed the highest coating quality on the silica surface, followed by the aluminoborosilicate surface and the sodalime glass surface. The trends in coating quality for all chromic acid cleaned surfaces and UV/ozone cleaned surfaces correlate with those seen for susceptibility to organic contamina-tion of the cleaned glass surfaces exposed to unpurified liquid octane. REFERENCES

2003 ◽  
pp. 114-116
Keyword(s):  
Glass Surface ◽  
Chromic Acid ◽  
Point Of Zero Charge ◽  
Coating Quality ◽  
Organic Contamination ◽  
Cleaning Procedure ◽  
Silanol Groups ◽  
Acid Cleaning ◽  
Glass Surfaces ◽  
Uv Ozone

Electron microscopic observations of the envelopes of isolated algal packets of Azolla

1991 ◽  
Vol 69 (7) ◽  
pp. 1418-1419 ◽  
Author(s):  
Eiji Uheda ◽  
Shunji Kitoh
Keyword(s):  
Electron Microscope ◽  
Nitric Acid ◽  
Sodium Hydroxide ◽  
Key Words ◽  
Layer Structure ◽  
Sodium Dodecylsulfate ◽  
Electron Microscopic ◽  
Microscopic Studies ◽  
20 Nm

The envelopes of isolated algal packets from cyanobiont-containing and cyanobiont-free Azolla were examined with the electron microscope. Both types of envelope were 10–20 nm thick and composed of three layers. The three-layer structure was also observed when algal packets were treated with cellulase, pectinase, lipase, protease, sodium hydroxide, nitric acid, or sodium dodecylsulfate. Thus, the envelopes do not appear to be membrane-like in nature and the presence and ultrastructure of the envelopes are not affected by cyanobiont filaments. Key words: algal packet, cyanobiont-free Azolla, Azolla, electron microscopic studies, envelope.

scholarly journals STUDIES ON EXPERIMENTAL HYPERTENSION

1943 ◽  
Vol 78 (1) ◽  
pp. 67-74 ◽  
Author(s):  
Yale J. Katz ◽  
Harry Goldblatt
Keyword(s):  
Blood Pressure ◽  
Sodium Hydroxide ◽  
Ammonium Sulfate ◽  
Good Yield ◽  
Trichloroacetic Acid ◽  
Experimental Hypertension ◽  
Distilled Water ◽  
Successive Treatment ◽  
Physiological Properties ◽  
Hog Kidney

1. Extraction of finely ground fresh hog kidney with distilled water adjusted to pH 7.8 with sodium hydroxide, followed by successive treatment, as described, with trichloroacetic acid and acetone, gives renin in good yield of a purity suitable for physiological studies and a good starting material for further purification. It contains 15 dog units per mg. N. 2. Further successive purification of this material with ethyl alcohol and ammonium sulfate gives a preparation containing 130 dog units per mg. N. The purest preparation hitherto reported (15) contained 16.0 to 20.8 units per mg. N. Preliminary Tiselius electrophoresis studies suggest homogeneity, but further studies to establish purity are in progress. 3. The properties of the most purified renin indicate that it is a protein. Its chemical and physiological properties correspond to those of the material in crude renal extract which induces an elevation of blood pressure when it is injected intravenously.

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