bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some Ultrastructural Aspects of Vensus’s-Flytrap
Authors: Schwab Daniel W. , Scala James , Simmons Evelyn B. 
Published: June 2020

Recently a study was begun in this laboratory on the insectivorous Venus's-flytrap (Dionaea muscipula Ellis) at all levels of microscopy, with emphasis on ultrastructure. Two features, among others, that stand out in the electron microscope after glutaraldehyde-osmium tetroxide fixation are: (1) a highly-convoluted plasmalemma in the digestive gland cells and (2) a tubular network in the cell walls of the trap lobe.The cell walls and plasmalemma of the digestive gland appear to be highly specialized, in that numerous microvilli-like outgrowths on the walls cause a myriad of invaginations in the plasmalemma (Fig. 1). Thus the plasmalemma has a tremendous surface area which would facilitate its functioning as a secretory and absorptive membrane. Also of interest in the digestive gland are the two distinctly different cell wall inclusions seen in Fig. 2. The bundle of tubular inclusions (Fig. 2, lower half) are apparently specialized plasmodesmata which do not traverse cell walls in the usual manner but run laterally around the cell.
Studies on Spontaneous Mammary Tumors in High-Leukemia-Strain Mice and on Mammary Tumors Induced by Mouse Leukemia Virus in Low-Leukemia-Strain Mice
Authors: Yumoto T. , Young L. , Williams W. C. , Dmochowski L. 
Published: June 2020

Murine leukemia type C virus particles were found in a spontaneous mammary gland medullary carcinoma of a 9-month-old high-leukemia AKR strain mouse (Fig.1). Similar virus particles were observed in a spontaneous mammary gland adenocarcinoma of a 12-month-old SJL/J high-leukemia-strain mouse (Fig.2). No virus particles could be seen in another mammary tumor of similar type in a 13-month-old SJL/J strain mouse nor in a spontaneous mammary squamous cell carcinoma of a 9-month-old NZB/BL high-leukemia-strain mouse.Mammary tumor type B virus particles were observed in a mammary gland adenocarcinoma of a 6-month-old AKR strain mouse inoculated when newborn with Moloney leukemia virus (Fig.3).No virus particles could be found in a mammary gland medullary carcinoma of a 12-month-old BALB/c low-leukemia and low-mammary-cancer-strain mouse inoculated with Moloney virus.Mammary gland medullary carcinomas developed in two BALB/c strain 5-and 6-month old mice inoculated with Rauscher leukemia virus. Murine leukemia type C virus particles were observed in both tumors (Fig.4).
Hepatic Ultrastructure Changes Induced by Lithocholic Acid
Authors: Zaki F. G. 
Published: June 2020

Addition of lithocholic acid (LCA), a naturally occurring bile acid in mammals, to a low protein diet fed to rats induced marked inflammatory reaction in the hepatic cells followed by hydropic degeneration and ductular cell proliferation. These changes were accompanied by dilatation and hyperplasia of the common bile duct and formation of “gallstones”. All these changes were reversible when LCA was withdrawn from the low protein diet except for the hardened gallstones which persisted.Electron microscopic studies revealed marked alterations in the hepatic cells. Early changes included disorganization, fragmentation of the rough endoplasmic reticulum and detachment of its ribosomes. Free ribosomes, either singly or arranged in small clusters were frequently seen in most of the hepatic cells. Vesiculation of the smooth endoplasmic reticulum was often encountered as early as one week after the administration of LCA (Fig. 1).
Microtubular Formations of Endoplasmic Reticulum in Human Pathological Tissues
Authors: Chandra S. , Kuzmic S. , Brandt P. M. , Monroe J. H. 
Published: June 2020

A certain modification of the endoplasmic reticulum has been described in liver in severe hyperlipidaemia and in cells from a culture of peripheral blood leukocytes of a leukemic patient. Recently cytoplasmic structures presumed to be related to virus synthesis have been reported in monkey kidney cells infected with rubella virus and in the Sticker sarcoma of the dog. During our studies with fifteen cell lines originating from different human tissues, similar cytoplasmic structures have been observed and interpreted as modifications of the endoplasmic reticulum (ER).A number of cell lines have been established from either the peripheral blood leukocytes, lymph nodes, or spleens and thymuses of cancerous or noncancerous patients. Both biopsy and autopsy materials have been used. Tissues of in vitro or in vivo origin were processed for electron microscopy in the usual way.
The Crystal Packing of Thyroglobulin
Authors: Labaw L. W. 
Published: June 2020

The unit of packing of thyroglobulin, the iodine-containing protein of the thyroid gland, in crystals appears to be an approximate sphere 230 Å in diameter (Figure 1). The size of this packing unit corresponds to a molecular weight of about 5,000,000 whereas the molecular weight of the thyroglobulin molecule is 660,000. The possibility that these packing units are aggregates of molecules has been examined in the electron microscope using positive staining (Figure 2), negative staining (Figure 3), and shadowing (Figure 4).Thyroglobulin crystallizes when the ammonium sulfate concentration is about 40% of saturation. The crystals can be freed of obscuring uncrystallized molecules by washing them with an ammonium sulfate solution of higher concentration. The washed crystals are then put on a substrate and air-dried (Figure 1). This high salt concentration makes examination of the packing unit for substructure difficult so the crystals were adsorbed onto substrates which were then flooded with 0.2% PTA and mopped. The resulting positively stained preparations suggest that the linear aggregates of packing units, which are associated side-by-side to make up the crystal, are actually helices. This is confirmed both by negatively staining such specimen screens by following the 0.2 PTA rinse with one of 2% before mopping (Figure 3), and by shadowing the 0.2% PTA rinsed and water washed screens with platinum (Figure 4).
The Use of the Scanning Electron Microscope for the Examination of Sectioned
Tissue
Authors: McDonald L.W. , Pease R.F.W. , Hayes T.L. 
Published: June 2020

In previous studies from this laboratory the scanning electron microscope has been used to examine biological materials in the cathodo-luminescense and secondary electron modes. In these studies intact cells or even entire insects have been examined, some in the living state. Epithelial surfaces have been exposed and examined. Prior to the work to be described, no reports of the examination of tissue sections in the scanning electron microscope have been found, although sufaces of solid one millimeter cubes of tissue have been examined.In the present work blocks of solid tissue fixed in buffered aldehyde have been dehydrated in graded alcohols, embedded in paraffin, section at 4μ and examined successfully in the scanning electron microscope. These sections have been over 1 cm square and have been stained for subsequent comparative examination with the light microscope. With the scanning electron microscope in the secondary electron mode, magnifications of X5,000 have been found useful. In addition to the increased resolution as compared to the light microscope, a three dimensional image is obtained. An advantage over the conventional electron microscope is that tissue areas 1,000 times greater may be examined in the large sections without any obscuring grid bars, again with the three dimensional image. With the cathode ray display tube used, magnifications range from X30 to over X20,000
The Optical System for the One Million Volt U.S. Steel Microscope Column
Authors: Reisner J. H. , Coleman J. W. 
Published: June 2020

The design of an optical system for million volt operation extends existing practice nearly to its limits, and certainly into the area of iron saturation, and coil power limitations. Serious design problems arise from the wide range of accelerating voltage (100 to 1000 kV) provided, which are for design purposes equivalent to corrected voltages (V*) of 110 to 2000 kV. To prevent alignment problems transverse fields have been reduced by the use of sufficient iron in magnetic circuits and by extreme care with the symmetry of all iron parts.Minimum objective focal lengths for a 1 cm bore lens (S/D=l), range from 6 mm. at 1000 kV with a k2 value of 1 to 2 mm. at 100 kV at k2 = 17. Performance characteristics are displayed in Figures 1, 2 and 3. While operation can be carried out over the whole voltage range with a 6 mm. focal length, an externally adjustable Z axis (axial) specimen position has been included in the stage, to permit operation with shorter focal lengths at lower voltages.
Injector for a 100-500 kV Linac Electron Microscopy Source
Authors: Coleman John W. 
Published: June 2020

The injector to be described is a component in the Electron Injector-Linear Accelerator—Condenser Module for illumination used on the variable 100-500kV electron microscope being built at the Radio Corporation of America for the University of Virginia.The injector is an independently powered, autonomous unit, operating at a constant 6kV positive with respect to accelerator potential, thereby making beam current independent of accelerator potential. The injector provides for on-axis ion trapping to prolong filament lifetime, and incorporates a derived Einzel lens for optical integration into the overall illumination system for microscopy. Electrostatic beam deflectors for alignment are an integral part of the apparatus. The entire injector unit is cantilevered off a door for side loading, and is topped with a 4-filament turret released electrically but driven by a self-contained Negator spring motor.
Electron Microscopy of Aluminum Surfaces Prepared for Welding
Authors: Johari O. , Dragen R. , Saperstein Z. P. , Kizer D. E. 
Published: June 2020

Before aluminum alloys are welded, they are usually subjected to some kind of surface treatment. This may involve machining, solvent degreasing, chemical cleaning, anodizing, etc. Storage time until welding often means exposure to a variety of environmental conditions.It has long been known that weld quality depends on the condition of the surface. A systematic program was started in our laboratory (ref. 1) to investigate and characterize surfaces and the associated weld-defect potential as a function of different treatments. The characterization of surfaces includes topography, metallography, quantitative and qualitative determination of adsorption of contaminants, and the nature of the oxide layer by electron microscopy. The electron replication studies are reported herein.
Phenomena Associated with Oxygen in Titanium
Authors: Lee E. U. , Garner P. A. , Owens J. S. 
Published: June 2020

Evidence for ordering (1-6) of interstitial impurities (O and C) has been obtained in b.c.c. metals, such as niobium and tantalum. In this paper we report the atomic and microstructural changes in an oxygenated c.p.h. metal (alpha titanium) as observed by transmission electron microscopy and diffraction.Oxygen was introduced into zone-refined iodide titanium sheets of 0.005 in. thickness in an atmosphere of oxygen and argon at 650°C, homogenized at 800°C and furnace-cooled in argon. Subsequently, thin foils were prepared by electrolytic polishing and examined in a JEM-7 electron microscope, operated at 100 KV.
Extended Preservation of Iron for Transmission
Authors: Abrahamson II E. P. , Dumais M. W. 
Published: June 2020

In a transmission microscopy study of iron and dilute iron base alloys, it was determined that it is possible to preserve specimens for extended periods of time. Our specimens were prepunched from 5 to 8 mil sheet to microscope size and annealed for several hours at 700°C. They were then thinned in a glacial acetic-12 percent perchloric acid solution using 10 volts and 20 milliamperes, at a temperature of 8 to 14°C.It was noted that by the use of a cold stage, the same specimen can be observed for periods up to one week without excess contamination. When removal of the specimen from the column becomes necessary, it was observed that a specimen may be kept for later observation in 1,2 dichloroethene or methanol for periods in excess of two weeks.
Powder Morphology of Nuclear Ceramics by Scanning Electron Microscopy
Authors: Daniel J.L. , Mayhan S.J. , Weber E.T. , Barr M.J. 
Published: June 2020

The value of scanning electron microscopy in the study of materials’ behavior has been well established. An application of particular importance in ceramics research is the study of powder morphology and the relationships between starting powders, fabrication steps and the finished compact.Since the source powders usually comprise submicron particles accumulated into larger agglomerates, detailed information of the size, shape and general appearance has been difficult to obtain by conventional electron microscopy. While replicas reveal some detail of the outer surface, and direct transmission techniques produce silhouettes of the powder particle masses, the complete structure is not shown satisfactorily by either method.
The Scanning Electron Microscopic Observation of the Vestibular Sensory Epithelia
Authors: Lim D.J. , Lane W.C. 
Published: June 2020

The morphology and function of the vestibular sensory organs has been extensively studied during the last decade with the advent of electron microscopy and electrophysiology. The opening of the space age also accelerated active investigation in this area, since this organ is responsible for the sensation of balance and of linear, angular and gravitational acceleration.The vestibular sense organs are formed by the saccule, utricle and three ampullae of the semicircular canals. The maculae (sacculi and utriculi) have otolithic membranes on the top of the sensory epithelia. The otolithic membrane is formed by a layer of thick gelatin and sand-piles of calcium carbonate crystals (Fig.l).
The Elmiskop 51, A Transmission Electron-Microscope with Permanent Magnet Magnification System
Authors: Müller K. , Ruska E. , Neff H. 
Published: June 2020

For routine analyses in laboratories of variing specialities, where a large number of electron micrographs are to be obtained quickly, the Elmiskope 51 has been developed.It has an accelerating voltage of 50 kV and permits Electron microscopic magnifications in steps of 1250:1 to 12 500:1. With high-resolution photoemulsions a point to point resolution of 20 to 25 Å can be reached.
Comparative Investigations on Various TV Image Transmission Systems used with Electron Microscopes
Authors: Herrmann K. -H. , Krahl D. , Kuebler A. 
Published: June 2020

Television systems for transmitting the final image of an electron microscope offer some advantages as compared with the usual method of observing the final image on the fluorescent screen:1.The current density in the object are a can be greatly reduced, without considerable loss in resolution.2.(Electronically, in a limited range, the contrast can be increased.)3.Easy focussing and astigmatism correction at very low beam current is possible, specially in case of high electron optical magnification without necessary dark adaption.4.Several views can observe the transmitted final image at the same time.
Observations on Evaporated Tantalum Films
Authors: Berting F. M. , Lawless K. R. 
Published: June 2020

High purity tantalum was vacuum deposited by electron beam evaporation onto polished {100} surfaces of single crystal MgO heated to temperatures between 700°C and 800°C. An ion pumped vacuum system was used, giving a vacuum of from 3·10-6 to 5·10-7 torr during actual deposition.The diffraction pattern from these Ta films (Figure 1) is very similar to that observed by Hutchinson and Olsen for one-quarter hour annealed Nb films.
Electronic Deposition and Lyophilization of Sprayed Suspensions of Protein for Electron Microscopy
Authors: Stasny J. T. , Vernon S. K. , Rubin B. A. 
Published: June 2020

The use of electronic deposition as a technique for the collection of microdroplets from nebulized suspensions of protein has been previously described. This technique has been extended for use with the subsequent freezing and drying of nebulized aerosols for studies concerned with the dimensional preservation of protein structure.Considerable difficulty is encountered when attempts are made to collect a nebulized aerosol onto a pre-cooled surface. The usual method of deposition involves the high-velocity, forced-air impaction of microdrop1ets onto a substrate surface. Therefore, the aerosol is both formed and delivered to the substrate surface by the same force. Static charging created by the formation of the aerosol, plus the wind turbulence created by the use of highpressure delivery system, prevents the majority of the microdrop1ets from reaching and adhering to the substrate surface.
Effects of Steroids on Fetal Rat Liver
Authors: Zaki F. G. 
Published: June 2020

Fetal and neonatal liver injury induced by agents circulating in maternal plasma, even though well recognized, its morphological manifestations are not yet established. As part of our studies of fetal and neonatal liver injury induced by maternal nutritional disorders, metabolic impairment and toxic agents, the effects of two anti-inflammatory steroids have been recently inves tigated.Triamcinolone and methyl prednisolone were injected each in a group of rats during pregnancy at a-dosage level of 2 mgm three times a week. Fetal liver was studied at 18 days of gestation. Litter size and weight markedly decreased than those of control rats. Stillbirths and resorption were of higher incidence in the triamcinolone group than in those given the prednisolone.
Ultrastructure of Choriocarcinoma in Vitro
Authors: Garancis John C. , Pattillo R. A. 
Published: June 2020

Growth of cell system (BeWo-cell line) derived from human gestational choriocarcinoma has been established and continuously maintained in-vitro. Furthermore, it is evident from the previous studies that this cell line has retained the physiological function of the placental trophoblasts, namely the synthesis of human chorionic gonadotrophil(HCG).The BeWo cells were relatively small and possessed single nuclei, thus indicating that this cell line consists exclusively of cytotrophoblasts. In some instances cells appeared widely separated and their lateral surfaces were provided with numerous microvilli (Fig.1).
Oxygen Effects on Tissue Culture Cells
Authors: Philpott Delbert E. , Takahashi Akira , Turnbill Charles 
Published: June 2020

Tissue culture cells of two varieties, L-929 mouse fibroblasts and Don Chinese Hamster lung, were exposed to 100% oxygen at one atmosphere and one-third of one atmosphere. When exposed to oxygen, the pH of the medium rose rapidly from 7.4 to about 8.4 and remained at this level. The organelles and general appearance of the cytoplasm were altered.In the control cells two or three small Golgi apparatus (G.A.) are usually observed. However, after oxygen exposure the G.A. appears dilated, in closer proximity to the nucleus, larger and apparently decreased in number. The endoplasmic reticulum decreases in amount and size. Concurrently, the number of ribosomes also decreases giving the cytoplasm a lighter appearance.
A Field Emission Electron Microscope
Authors: Tonomura A. , Komoda T. 
Published: June 2020

We have developed a field emission electron microscope. Although field emission gun requires ultra high vacuum and skillful technique, it brings about the favorable characteristics of high brightness and small energy spread. This characteristics will enable a significant progress in coherent electron optics and high resolution electron microscopy, especially in electron beam holography.Its column is Hitachi HU-11C Electron Microscope modified for ultra high vacuum operation, and it is evacuated with five ion pumps. Field emission gun is divided into two parts and is evacuated differentially with two ion pumps and a sublimation pump. The final pressures in these rooms are 5x10-10 Torr and 5x10-8 Torr respectively.
Quadrupole-Octopole and Foil Lens Corrector Systems
Authors: Thomson M. G. R. , Jacobsen E. H. 
Published: June 2020

The theorem due to Scherzer which states, in essence, that a conventional axially symmetric, magnetic or electrostatic lens can never be free from third order spherical aberration is well known. Attempts to circumvent this limitation have been carried out over the past thirty years with little result, but meanwhile the ill effects have been minimized by using magnetic lenses of very short focal length.The most studied alternative is the use of doubly symmetric strong focusing lenses. The first order imaging is performed with three or more quadrupoles, and the third order aberrations corrected with three octopoles. The design by Deltrap for example has no first order effect other than to invert the image, and has a third order spherical aberration coefficient which exactly cancels out that of the magnetic objective lens with which it us used. To avoid chromatic aberration this magnetic objective lens must have a very short focal length (2 mm for 100 kv operation with a resolution of 1 Å), and the overall system then has so much coma that the field of view is limited to 50 Å diameter.
Quantitative Analysis in High Resolution Transmission Scanning Microscopy
Authors: Crewe A. V. , Wall J. 
Published: June 2020

The scanning microscope is ideally suited for gathering quantitative information about an object, since its outputs are voltage signals which are measures of the interactions of the incident beam with the volume of the specimen struck by the beam. These signals vary in real time as the beam scans and can be processed electronically to assign a “number” to each element of the scanned matrix.Elastic and inelastic scattering cross sections have been selected as the two useful numbers to characterize a specimen since both are 1) additive functions of specimen composition, 2) unambiguously measurable with high efficiency, 3) Independent of microscope parameters, and 4) measurable with high spatial resolution (<5Å).
High Resolution Electron Microscopy Using Phase Plates
Authors: Thon F. , Willasch D. 
Published: June 2020

The phase contrast transfer properties of objective lenses used in electron microscopy are not at all satisfactory and therefore the interpretation of phase contrast images is quite limited in the high resolution field. Phase contrast, however, is the dominant factor in creating contrast in high resolution electron microscopy. This is why methods which promise to improve the transfer conditions are of great importance.A series of experiments has been reported to improve the contrast transfer conditions by zonal or semicircular filtering in the back focal plane of the objective lens or in subsequent light optical reconstruction. By these methods the transfer properties can be improved only to a certain degree.For ideal imaging a transfer function would be desirable that is of constant value for the whole spatial frequency spectrum relevant to high resolution microscopy. This should in principle be attainable by inserting a phase shifting foil of varying thickness into the back focal plane.