bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence For a Norepinephrine Pool Enhancing Factor in Purified Adrenergic Vesicles: A Functional Macromolecular Form of Dopamine β-Hydroxylase?
Authors: Thureson-Klein Å. , Klein R. L. , Yen S. S. , Lagercrantz H. 
Published: June 2020

Highly purified, 750A, dense-core vesicles from bovine splenic nerve can be prepared with a norepinephrine(NE) content of 100 nmoles/mg protein-'. Upon incubation at 30°C, however, the NE is rapidly lost from two pools with halflives of ∼ 4 and 35 minutes, even in the presence of ATP. Loss from the slower, ATP-sensitive pool accounts for 807o of the total vesicle NE and is accompanied by decrements in vesicle matrix density viewed at the ultrastructural level. It is known that the density of the matrix substance parallels semi-quantitatively the vesicle NE content under these conditions.A search was undertaken for factors which normally stabilize vesicle NE content in vivo, but are lost with the neuroplasm or from the vesicles during purification.
The Ultrastructural Basis For Increased Prolactin Synthesis and Release From Anterior Pituitary Glands of Estrogen-Progesterone Primed Ovariectomized Rats: Correlated Electron Microscopy and Radioimmunoassay
Authors: Coates P. W. , Blake C. A. , Maxwell D. S. , Sawyer C. H. 
Published: June 2020

In rats, physiological studies show that ovariectomy results in a reduced concentration of circulating prolactin. Conversely, ovariectomized rats given estrogen have elevated serum prolactin and increased amounts of prolactin in the anterior pituitary gland. Separate electron microscopic studies suggest modifications in fine structure of prolactin producing (LTH) cells based on relatively large cumulative amounts of estrogen given alone or with comparably high doses of progesterone to adult virgin female or ovariectomized rats. This study was undertaken to provide a correlated morphological and physiological investigation of LTH cells and prolactin levels in a model commonly used by many researchers.Six to seven weeks after bilateral ovariectomy, a group of adult female rats was primed by a subcutaneous injection of 50 ng of estradiol benzoate and 25 mg of progesterone.
Crystals in Pulmonary Alveolar Macrophages in Aged Mice
Authors: Hertweck M. Sue , Loosli Clayton G. , Hung Kuen-Shan 
Published: June 2020

Crystalline deposits observed by light microscopy in the alveolar spaces and in pulmonary macrophages in old C57/bl mice breathing filtered or ambient Los Angeles air has been reported. This report describes crystalline intracellular deposits seen in macrophages for the first time by electron microscopy in old SPF Swiss mice (20-24 months) CD-I strain living in synthetic smog (SS) or filtered air (FA). More were found in the lungs of the SS exposed mice.For this study, the lungs of mice sacrificed intraperitoneaIly with diabutol injection were inflated with 2% glutaraldehyde, post-fixed in 1% osmic acid, and processed for electron microscopy. The cytoplasm of the macrophages had characteristic cell organelles and inclusions. In addition, varying numbers of elongated crystals were dispersed throughout the cytoplasm (Fig. 1).
Morphological Aspects of Spermatozoan Cytoplasmic Droplet in Some Plethodontid Salamanders
Authors: Murphy Judith A. , Wortham J.W.E. , Martan J. , Thompson Mary R. 
Published: June 2020

Ultrastructural studies of cytoplasmic droplets of various mammalian spermatozoa(bull, ram, rabbit, rat, and bat) have revealed only numerous membranous vesicles and tubules in their matrix. The simpl icity of the ultrastructure and lack of other organelles and inclusions in the droplet matrix led researchers to doubt suggestions that cytoplasmic droplets contain endogenous substrates for epididymal spermatozoa survival. Recently, however, biochemical and cytochemical analysis of cytoplasmic droplets in spermatozoa of different domestic animals showed a rather high activity of hydrolytic and glycolytic enzymes.In our study of interspecific variation in sperm morphology within the salamander family Plethodontidae, it was observed that spermatozoa of all examined plethodontid species have a characteristic cytoplasmic droplet. Cytoplasmic droplets of 16 species were examined with the light microscope and in addition, Plethodon qlutinosus was examined with the TEM.
The Pituitary Response to Stress: An Immunocytochemical - Cytophysiologic Study
Authors: Moriarty Gwen C. , Moriarty C. M. 
Published: June 2020

Physiologic studies have shown that there is a peptide in mammalian neurointermediate lobes with immunologic and biologic properties similar to adrenocorticotropin (ACTH). Immunocytochemists have localized the peptide in the secretory granules of the intermediate lobe parenchymal cells and in rostral zone anterior lobe ACTH cells. [Moriarty, G. C. and Halmi, N. S., Z. Zellforsch 132:1 (1972)].In an attempt to determine the physiologic significance of this peptide, we rapidly removed the pituitaries from intact and adrenalectomized rats which were stressed by ether (2 minutes) or a buzzer (30 minutes). The neurointermediate lobes were separated from the anterior lobes and prepared for electron microscopy and immunocytochemistry (with the unlabeled antibody peroxidase-antiperoxidase complex technique) and ACTH bioassay (with the use of dispersed adrenal cells according to Sayers et al.) and radioimmunoassay.
Cytochemical Studies of Protein Uptake by Adrenal Cortical Cells of the Golden Hamster
Authors: Hillman J. R. , Seliger W. G. , Burk P. E. 
Published: June 2020

In a previous histochemical study, high levels of acid phosphatase were found in the developing adrenal cortex of the golden hamster. The present study describes the cytochemical localization of acid phosphatase and thiamine pyrophosphatase in the adult animal. These localizations are then related to protein uptake by adrenal cortical cells using the exogenous horseradish peroxidase as a tracer protein. Animals were sacrificed at times ranging from 15 minutes to 24 hours after injection of peroxidase. The techniques described by Novikoff et al. were utilized for localization of acid phosphatase and thiamine pyrophosphatase.In acid phosphatase preparations (Fig. 1), dense bodies containing reaction product are found in the cytoplasm of most cortical cells and are often associated with small coated vesicles near the Golgi area. Acid phosphatase activity is present in cells of the zona glomerulosa as well as those of the other two cortical zones.
Electron-acoustic microscopy-An overview
Authors: Cargill III G. S. 
Published: June 2020

Electron-acoustic microscopy is a new way of to look at materials with a scanning electron microscope. Acoustic, or more properly ultrasonic, signals are detected instead of secondary or backscattered electrons. A SEM’s electron beam which is chopped at kHz or MHz rates serves as a localized periodic heat source for the specimen being examined, as illustrated in Fig. 1. Periodic thermal expansion in the specimen generates ultrasonic waves, which are detected by a piezoelectric transducer. Contrast in electron-acoustic images results mainly from spatial variations of thermal, elastic, and dimensional properties of the specimen, rather than from variations in surface topography or average atomic number.Additions to a conventional SEM for doing electron-acoustic microscopy consist of a beam chopping system, a well shielded transducer assembly on which samples are mounted, and electronics for using the transducer output to control the brightness of the SEM’s cathode ray tube (CRT) display, as shown in Fig. 2. Squarewave or sinewave voltages applied to beam deflector plates have been used for beam chopping. PZT transducers and quartz transducers have been used for detecting the acoustic signals. The transducer output, typically several microvolts, feeds a low-noise preamplifier, which drives either an rf amplifier-rectifier or a phase-sensitive (lock-in) amplifier/detector, and a video amplifier. Output of the video amplifier is used to control the CRT display brightness. The beam chopping signal is used as reference for the lock-in. Phasesensitive detection with a lock-in amplifier allows variations of acoustic signal phase as well as acoustic signal amplitude to be used in forming images.
Visualization by STEM annular DF of intralamellar shear in polyethylene
Authors: Wade Adams W. 
Published: June 2020

Thin films of polyethylene (PE) with high orientation have recently been prepared by “melt-drawing”. This process produces long crystalline lamellae normal to the draw direction and with the chain axis [00ℓ] parallel to the draw direction (Figure 1).Thin films were prepared from a 0.5% solution of high density PE (Marlex 6003, Mw=2×l05) in xylene, which was drawn from a glass slide at 125°C. The films were annealed on glycerol at 125°C for two hours, then were placed on specially fabricated soft copper deformation grids. In-situ deformation was performed in a tensile deformation stage of a JE0L 100CX STEM. The initial gauge length was 0.5mm, with a strain rate of 0.1min−1.Figure 1 shows a bright field (BF) CTEM image of an annealed film. Crystals properly oriented for diffraction appear black, while non-Bragg-oriented lamellar crystals are grey. The interlamellar zones (amorphous regions) appear as bright areas for underfocus conditions since innerpotential of the crystalline phase is approximately one volt larger than that of the amorphous phase. The bright white “ghosts” are diffraction images displaced by defocus from their corresponding main beam images in the direction of the appropriate diffraction vector.
The imperfections in the atomic structure of enamel crystals
Authors: Duke Lee DoSuk 
Published: June 2020

It is generally accepted that the principal inorganic component in the human and shark enamels is calcium phosphate apatite, idealized as Ca10(PO4)6 (OH)2 and Ca10(PO4)6 (F)2 respectively. Technically, because of the microcrystalline nature and the heterogeneous properties of these enamel crystals, there are some difficulties in characterizing the precise chemical content and their atomic structures. However, in recent studies, high-resolution transmission electron microscopy has provided some evidence on the morphological changes of enamel crystals during the process of carious lesion. These studies have shown that the initial stage of dissolution process is the formation of central cores in the crystals preferentially along the (1000) planes, and the presence of lattice defects or dislocations in human enamel has been attributed with the initial site of acid dissolution during caries.Through the lattice imaging technique, the present study provides clear evidence showing the presence of dislocations arising from the terminating stacking faults in the enamel apatite crystals(figures 1&2).
High-resolution imaging of oxidized stepped silicon surfaces
Authors: Mazur Jerzy H. 
Published: June 2020

The Si-SiO2 system has been the subject of extensive investigation due to its importance for MOS electronic devices. However, an understanding of the correlation between electronic processes, the structure of the Si-SiO2 interface, and the mechanism of oxidation is still lacking. This study is part of a broad research program that attempts to establish an atomistic model of the Si-SiO2 interface structure and mechanism of oxidation.In the experiment the p-type boron doped 7-17Ωcm Si wafers used for oxidation had a surface orientation 3° off [111] towards [10]. The wafers were cleaned before oxidation using the RCA procedures followed by immediate oxidation at 1000°C in dry O2 to various thicknesses ranging from 200Å to 1000Å. Cross-sections for TEM, with a normal parallel to the [10] direction of the Si substrate were prepared using standard procedures. These TEM specimens of thermally grown and native oxides were imaged with point to point resolution of 2.6Å using a JEM200CX electron microscope operating at 200 kV.
The dislocation structure of a 10° [110] tilt boundary in silicon
Authors: Cunningham B. , Ast D.G. 
Published: June 2020

There have Been a number of studies of low-angle, θ < 4°, [10] tilt boundaries in the diamond lattice. Dislocations with Burgers vectors a/2<110>, a/2<112>, a<111> and a<001> have been reported in melt-grown bicrystals of germanium, and dislocations with Burgers vectors a<001> and a/2<112> have been reported in hot-pressed bicrystals of silicon. Most of the dislocations were found to be dissociated, the dissociation widths being dependent on the tilt angle. Possible dissociation schemes and formation mechanisms for the a<001> and a<111> dislocations from the interaction of lattice dislocations have recently been given.The present study reports on the dislocation structure of a 10° [10] tilt boundary in chemically vapor deposited silicon. The dislocations in the boundary were spaced about 1-3nm apart, making them difficult to resolve by conventional diffraction contrast techniques. The dislocation structure was therefore studied by the lattice-fringe imaging technique.
The temperature dependence of EBIC contrast from defects
Authors: Ourmazd A. , Wilshaw P. R. , Booker G. R. 
Published: June 2020

The Electron Beam Induced Current (EBIC) mode of the SEM has been extensively used to reveal the presence of electrically active dislocations in semiconductor specimens. Only in recent years, however, have attempts been made to deduce quantitative information from this technique and relate such information to the details of the recombination process at individual defects. A major advantage of the EBIC technique is its high spatial resolution and thus its ability to yield electrical data from individual extended defects.Fig. 1(a) is a TEM micrograph of a widely dissociated screw dislocation, obtained with a forbidden reflection of the type 1/3 (422), where the stacking fault ribbon between the 30° partials is showing bright constrast. Fig. 1(b) is a corresponding EBIC image, where the individual 30° partials are directly resolved for the first time. Since the ultimate resolution of an electrical technique is essentially determined by the Debye screening length, which in the sample of Fig. 1 is approximately 0.1μm, it is clear that EBIC is capable of approaching this resolution limit.
Unusual microstructures in the C2 carbonaceous chondrites
Authors: Tomeoka Kazushige , Buseck Peter R. 
Published: June 2020

Carbonaceous chondrites are among the most primitive meteoritic samples of early solar system materials that are accessible for study. One of the characteristics of these meteorites is that their mineral constituents are extremely fine grained, and so high-resolution transmission electron microscopy (HRTEM) is a powerful method to study the mineralogy of carbonaceous chondrites.The C2 type carbonaceous chondrites contain abundant amounts of an unusual “Fe-Ni-S-O” phase, which has been termed the “poorly characterized phase” (PCP). Its identity has been one of the more difficult problems of carbonaceous chondrite mineralogy. Its puzzling composition and X-ray diffraction patterns do not fit any known mineral. It may be a) related to a primordial condensate, or b) an alteration product in a parent body regolith. Detailed mineralogical characterization of PCP potentially bears on these questions and therefore is of great interest for meteorite scientists.
A new ordered phase in Mn-Al-C alloys
Authors: Gau J. S. 
Published: June 2020

Convergent beam electron diffraction (CBED) coupled with conventional diffraction studies is used to identify a new ordered phase in the Mn-Al-C ribbons produced by the melt extraction rapid quenching processing (RSP).Recently, developments in alloy chemistry and processing technique have made Mn-Al- C alloys a promising substitute for the Alnico magnets which dominate the permanent magnet market. The ferromagnetic T phase is formed through a two-stage process; from the high temperature disordered hexagonal ε phase, an ordered orthorhombic ε' phase is formed which is further shear transformed to the tetragonal ordered τ phase (L1o). The present investigation is to study the phase in the ribbons produced by the rapid liquid quenching process with a rotating copper disc at a cooling rate of about 105-9°C/sec. The ribbons have an average thickness of 50μm and are between 2mm to 40mm in length. The as cast structure exhibits a dendrite morphology with an average arm spacing of l.0μm. X-ray diffraction examination of the cast ribbons reveals that the material is quenched into the high temperature disordered ε phase.
Microstructures in 0.1 to 1 Mbar shock-loaded 200 nickel: A TEM study
Authors: Staudhammer K. P. , Johnson K. A. , Olinger B. W. 
Published: June 2020

Flyer plate techniques have been used to obtain tensile compression shocks. In the present work 200 nickel was subjected to a radial shock profile which varied in pressure from 0.1 to 1 Mbar along the axis of a cylinder. This unique shock profile produced tensile strains of up to 30% elongation at a strain rate of 106/sec.The nickel cylinder had an initial grain size of 60 μm. Post shock optical microscopy revealed minimum deformation in the bulk of the assembly. However, at the shock convergence axis of the cylinder fracture/spalation was observed, particularly at the higher pressures. Our TEM observations were taken away from these areas. The hardness measurements revealed a significant increase in hardness over that of the annealed material, 240 vs 100 dph. The uniformly high value of microhardness indicated a saturation of defects and magnetic permeability indicated much the same, with no significant variation throughout the bar.
Computation of images of dislocations meeting a free surface
Authors: Humble P. 
Published: June 2020

The surfaces of crystalline solids are interesting and important regions where the bulk properties change discontinuously. Chemical reactions, wear processes and many hardening and fracture processes occur or are initiated there. Crystal defects such as dislocations, stacking faults etc, are often thought to play a role in these processes. Although it is known theoretically that defects behave differently in the neighbourhood of surfaces, the electron microscope imaging of defects close to free surfaces has not received much attention.The computer programs which we have developed for the identification of dislocations by image matching use a displacement field which is appropriate to a straight dislocation in an infinite elastic medium. For reasons of program speed, the effects of the surfaces of the thin electron microscope specimen are not taken into account; i.e., it is as if the specimen has been cut out of the elastic medium with the stresses on the cut surfaces held at their infinite crystal values.
The development of order in a system of metal clusters
Authors: Listvan Marilyn A. 
Published: June 2020

Domain growth and the motion of grain boundaries are important processes in materials science. The behavior of grain boundaries and other boundaries between different domains is tied to many material properties, such as conductivity. In dilute systems, one boundary of interest is the domain wall between the material and vacuum. Thermodynamically unstable systems will show domain, i.e. cluster growth. This cluster growth can be studied directly by high resolution scanning transmission electron microscopy (STEM).We have examined a system of gold clusters, prepared by in vacuo vapordeposition of gold on thin amorphous carbon substrates. A complete description of methods may be found in reference 1.By simultaneously depositing metal atoms with an easily removed hydrocarbon layer, we observed small clusters (figure la.) which grew in situ without further deposition under clean conditions at room temperature in the microscope column (figure lb.). The initial projected area distribution (seen in figure 2a.) showed a good fit to a Poisson distribution of areas.
Ultrastructure of the bronchiolar epithelium in the guinea pig
Authors: Davis M. L. , Lewandowski J. , Dodson R. F. , Hurst G. A. 
Published: June 2020

The guinea pig has played an important role as an animal model in the study of respiratory pathology. However, little information has been published concerning the ultrastructure of the small airways in control animals. The present study was undertaken to provide this information and these data are necessary before morphological changes induced by experimental respiratory insult can be evaluated.Four healthy, adult guinea pigs were anesthetized with sodium pentobarbital and then killed by right ventricular perfusion with phosphate buffered glutaraldehyde. During the procedure, the lungs were ventilated with a rodent respirator. Immediately following vascular perfusion, the heart and lungs were removed intact, and the lungs were filled with fixative via the trachea. Slices of lung tissue were removed from each lobe and processed for both scanning and transmission electron microscopy.The terminal and respiratory bronchioles are the two types of small airways emphasized in the study.
Electron microscopic studies of glomerular basement membrane (GBM) challenged with antisera to GBM or streptococcal cell membrane (SCM)
Authors: R. P. Nayyar , Lange C. F. , Volini F. I. 
Published: June 2020

The main objective of this study is to evaluate the synthesis and turnover of the glomerular basement membrane under normal and induced pathologial conditions. Mice were challenged with rabbit antisera by intraperitoneal (IP) or intravenous (IV) injection of 0.1 ml of normal serum, anti-glomerular basement membrane (GBM) or anti-streptococcal cell membrane (SCM) sera followed by a 10 μC/g body weight of H-L-Proline. A cold chase of L-proline was also administered 15 minutes later. Some of the animals also received additional chases of normal serum and anti-sera 2 and 4 hours after the initial injections. The animals were sacrificed at 2, 4, 6, 8, 18, 24, 40 and 48 hours, kidneys removed and processed for light, immunofluorescent, electronmicroscopic and radioautographic studies.Immunofluorescent and electronmicroscopic studies did not reveal any significant differences in the binding capacity of anti-sera based on the route of challenge (IP or IV).
Surface ultrastructure of danazol treated rat endometrium: A SEM study
Authors: Apkarian R.P. , Sanfilippo J.S. 
Published: June 2020

The synthetic androgen danazol, is an isoxazol derivative of ethisterone. It is utilized in the treatment of endometriosis, fibrocystic breast disease, and has a potential use as a contraceptive. A study was designed to evaluate the ultrastructural changes associated with danazol therapy in a rat model. The preliminary investigation of the distal segment of the rat uterine horn was undertaken as part of a larger study intended to elucidate the effects of danazol on the female reproductive tract.Cross-sections (2-3 mm in length) of the distal segment of the uterine horn from sixteen Sprague-Dawley rats were prepared for SEM. Ten rats in estrus served as controls and six danazol treated rats were noted to have alterations of the estrus cycle i.e. a lag in cycle phase or noncycling patterns. Specimens were fixed in 3% glutaraldehyde in 0.05M phosphate buffer containing CaCl2 at pH 7.0-7.4 and chilled to 4°C. After a brief wash in distilled water, specimens were passed through a graded series of ethanol, critical point dryed in CO2 from absolute ethanol, and coated with 6nm Au. Observations were made with an IS1-40 SEM operated at 15kV.