New Dimensions in Freeze-Etching

1969 ◽  
Vol 27 ◽  
pp. 202-203 ◽  
Author(s):  
Russell L. Steere ◽  
Michael Moseley
Keyword(s):  
Fracture Surfaces ◽  
Aluminum Specimen ◽  
Specimen Holder ◽  
Freeze Etching ◽  
The Right

A redesigned specimen holder and cap have made possible the freeze-etching of both fracture surfaces of a frozen fractured specimen. In principal, the procedure involves freezing a specimen between two specimen holders (as shown in A, Fig. 1, and the left side of Fig. 2). The aluminum specimen holders and brass cap are constructed so that the upper specimen holder can be forced loose, turned over, and pressed down firmly against the specimen stage to a position represented by B, Fig. 1, and the right side of Fig. 2.

Simultaneous Freeze-Etching of Eight Specimens

1969 ◽  
Vol 27 ◽  
pp. 398-399
Author(s):  
Russell L. Steere ◽  
Michael Moseley
Keyword(s):  
Freezing Point ◽  
Specimen Holder ◽  
Cold Stage ◽  
Freeze Etching

A specimen cap for the Denton Freeze-Etching Module has been modified (Fig. 1) to permit the easy manipulation and simultaneous freeze-etching of eight specimens. A slot has been cut in one side of the cap to permit the insertion of a brass washer and a thin copper retainer plate above the threads, but below the supporting top of the cap. The inside rims of the washer are elevated, and the end of each specimen holder flange is beveled down and out to the base to form a wedge which can be forced under the washer. Small caps are placed over the specimen in each holder. Specimens are frozen by rapid immersion in Freon 22. The assembled cap is then mounted on a stage, standing in liquid Freon near its freezing point and slightly loosened. The eight frozen specimens, with caps in place, are picked up individually with tweezers and wedged under the washer, lifting it in the process. These operations can be accomplished with cold stage and cap under a dissecting microscope, if desired.

The plasma membrane of pityrosporum has natural markers to show how the cell grows

1978 ◽  
Vol 36 (2) ◽  
pp. 404-405
Author(s):  
Kanji Takeo ◽  
Ei-Ichi Nakai
Keyword(s):  
Plasma Membrane ◽  
Spiral Groove ◽  
Left Handedness ◽  
Left Handed ◽  
Specimen Holder ◽  
Inner Surface ◽  
Freeze Etching ◽  
Pityrosporum Orbiculare ◽  
Tinea Versicolor ◽  
Spiral Grooves

Pityrosporum is a lipophilic yeast containing the causative agent of tinea versicolor, and has spiral grooves on the inner surface of the cell wall and the plasma membrane. Detailed studies on the plasma membrane of this organism revealed the existence of asymmetry around the plasma membrane, peculiar mode of the growth of this organism, mode of spiral groove formation, and a possible mechanism of groove formation. One strain each of Pityrosporum orbiculare and P. pachydermatis and ten strains of P. ovale were grown on a potato yeast extract agar, supplemented with 1% olive oil at 27-37°C for 1-20 days. Cultures were directly transferred to the specimen holder of the freeze-etching apparatus without no pretreatment. 40% glycerol was added before cooling.All the strains tested of the genus Pityrosporum had only left-handed spiral grooves of the plasma membrane. Left-handedness of the spiral grooves of Pityrosporum was confirmed by scanning electron microscopy which occasionally revealed left-handed spiral grooves on the outer surface of the wall.

A New Model of Freeze Etching Apparatus

1972 ◽  
Vol 30 ◽  
pp. 294-294
Author(s):  
Hiroshi Akahori ◽  
Sadahiko Okamura ◽  
Mitsugu Nishiura ◽  
Kenzo Uehira
Keyword(s):  
Freeze Fracture ◽  
Small Hole ◽  
Small Specimen ◽  
Block Method ◽  
New Model ◽  
Specimen Holder ◽  
Lower Block ◽  
Freeze Etching ◽  
Cold Metal ◽  
Metal Block

A new model of freeze etching apparatus has been designed which enabled us to make both freeze fracture and freeze etching replicas of the biological specimens by easy simple procedures.This model is based on the principle of Bullivant's cold metal block method. It is composed of two-wedge-like brass blocks which are combined in a shape of rectangular prism with'a base 5.5 cm x 6. 0 era and a height of 7.5 cm.The lower block has a specimen stage to which a small specimen holder made of copper can be fixed. The specimen is put in a small hole of the specimen holder, and this holder is cooled in Freon 12.

Investor-State Dispute Settlement under NAFTA Chapter 11: The Shape of Things to Come?

1998 ◽  
Vol 35 ◽  
pp. 263-290
Author(s):  
J. Anthony VanDuzer
Keyword(s):  
Free Trade Agreement ◽  
Dispute Settlement ◽  
Trade Agreement ◽  
Minimum Standards ◽  
The North ◽  
State Behaviour ◽  
Nafta Chapter 11 ◽  
To Come ◽  
The Right

SummaryRecently, there has been a proliferation of international agreements imposing minimum standards on states in respect of their treatment of foreign investors and allowing investors to initiate dispute settlement proceedings where a state violates these standards. Of greatest significance to Canada is Chapter 11 of the North American Free Trade Agreement, which provides both standards for state behaviour and the right to initiate binding arbitration. Since 1996, four cases have been brought under Chapter 11. This note describes the Chapter 11 process and suggests some of the issues that may arise as it is increasingly resorted to by investors.

What face familiarity feelings say about the lateralization of specific entities within the core system

2019 ◽  
Vol 42 ◽  
Author(s):  
Guido Gainotti
Keyword(s):  
Temporal Lobe ◽  
Memory System ◽  
Core System ◽  
The Core ◽  
Memory Traces ◽  
Specific Memory ◽  
Target Article ◽  
Temporal Structures ◽  
The Right

Abstract The target article carefully describes the memory system, centered on the temporal lobe that builds specific memory traces. It does not, however, mention the laterality effects that exist within this system. This commentary briefly surveys evidence showing that clear asymmetries exist within the temporal lobe structures subserving the core system and that the right temporal structures mainly underpin face familiarity feelings.

Study of charge transfer in FeTi

1983 ◽  
Vol 41 ◽  
pp. 296-297
Author(s):  
J. Taft∅
Keyword(s):  
Charge Transfer ◽  
Charge Distribution ◽  
Electron Scattering ◽  
Periodic System ◽  
Electron Distribution ◽  
Scattering Amplitude ◽  
Transition Elements ◽  
Hartree Fock ◽  
Cscl Structure ◽  
The Right

It is well known that for reflections corresponding to large interplanar spacings (i.e., sin θ/λ small), the electron scattering amplitude, f, is sensitive to the ionicity and to the charge distribution around the atoms. We have used this in order to obtain information about the charge distribution in FeTi, which is a candidate for storage of hydrogen. Our goal is to study the changes in electron distribution in the presence of hydrogen, and also the ionicity of hydrogen in metals, but so far our study has been limited to pure FeTi. FeTi has the CsCl structure and thus Fe and Ti scatter with a phase difference of π into the 100-ref lections. Because Fe (Z = 26) is higher in the periodic system than Ti (Z = 22), an immediate “guess” would be that Fe has a larger scattering amplitude than Ti. However, relativistic Hartree-Fock calculations show that the opposite is the case for the 100-reflection. An explanation for this may be sought in the stronger localization of the d-electrons of the first row transition elements when moving to the right in the periodic table. The tabulated difference between fTi (100) and ffe (100) is small, however, and based on the values of the scattering amplitude for isolated atoms, the kinematical intensity of the 100-reflection is only 5.10-4 of the intensity of the 200-reflection.

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.

Adrenocorticotropin Production by a Mammary Carcinoma

1977 ◽  
Vol 35 ◽  
pp. 462-463
Author(s):  
K.S. McCarty ◽  
N.R. Wallace ◽  
W. Litaker ◽  
S. Wells ◽  
G. Eisenbarth
Keyword(s):  
Adrenocorticotropic Hormone ◽  
Small Cell ◽  
Hormone Production ◽  
Carcinoma Of The Breast ◽  
Ectopic Acth ◽  
Ultrastructural Studies ◽  
Subcutaneous Metastases ◽  
Ectopic Acth Production ◽  
The Right ◽  
Pituitary Carcinomas

The production of adrenocorticotropic hormone by non-pituitary carcinomas has been documented in several tumors, most frequently small cell carcinoma of the lung, islet cell carcinomas of the pancreas, thymomas and carcinoids. Electron microscopy of these tumors reveals typical membrane-limited "neurosecretory" granules. Confirmation of the granules as adrenocorticotropin (ACTH) requires the use of OsO4 as a primary fixative to give the characteristic cored granule appearance in conjunction with immunohistochemical demonstration of the hormone peptide. Because of the rarity of ectopic ACTH production by mammary carcinomas and the absence of appropriate ultrastructural studies in the two examples of such ectopic hormone production in the literature of which we are aware (1,2), we present biochemical and ultrastructural data from a carcinoma of the breast with apparent ACTH production.The patient had her primary tumor in the right breast in 1969. The tumor recurred as visceral and subcutaneous metastases in 1976 and again in 1977.

A Liquid Nitrogen Cooled Stage for STEM

1974 ◽  
Vol 32 ◽  
pp. 444-445
Author(s):  
Louis T. Germinario
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Liquid Nitrogen ◽  
Room Temperature ◽  
Objective Lens ◽  
Thermal Drift ◽  
Specimen Holder ◽  
Resolution Capability ◽  
Focal Position

A liquid nitrogen stage has been developed for the JEOL JEM-100B electron microscope equipped with a scanning attachment. The design is a modification of the standard JEM-100B SEM specimen holder with specimen cooling to any temperatures In the range ~ 55°K to room temperature. Since the specimen plane is maintained at the ‘high resolution’ focal position of the objective lens and ‘bumping’ and thermal drift la minimized by supercooling the liquid nitrogen, the high resolution capability of the microscope is maintained (Fig.4).

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