bluuebunny/crossref_metadata_2025 huggingface dataset:
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.
X-ray probe microanalyses and scanning x-ray microscopies
Authors: Cazaux J.
Published: June 2020

The focusing and scanning of X-ray photon beam is a difficult operation. Thus in order to obtain data concerning the elemental composition of a specimen, the analytical techniques based on incident X-ray photons have generally a poor degree of lateral localization. The aim of the present paper is to show how it is possible to develop microanalytical techniques based on X-ray excitation of inner shell electrons like X-ray photoelectron spectroscopy (XPS or ESCA)and X-ray induced Auger electron spectroscopy (XAES)for surface analysis; X-ray fluorescence spectroscopy (XRF)for bulk analysis. The same experimental arrangement is also applied to develop the corresponding scanning microscopies: Scanning X-ray Photoelectron Microscopy(SXPM), Scanning X-ray induced Auger Microscopy(SXAM)and Scanning X-ray radiography(SXR). The experimental set-up and obtained results will be presented; further improvements and comparisons with other technical solutions will be discussed.
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.
Observation of dislocation reactions in CDTE at lattice resolution
Authors: Yamashita T. , Sinclair R.
Published: June 2020

Recently, lattice resolution video-recording of dislocation motion in CdTe has been reported by Sinclair et al, using the Cambridge 500 keV microscope equipped with a TV camera. Phenomena such as the motion of Shockley partial dislocations and climb of Frank dislocations were recorded onto a video tape which has an exposure rate of 50 half-frames per second. An obvious extension of this work is to study the dislocation reactions. An example of such a reaction which was detected in CdTe is shown in Fig. 1. The micrographs were taken several seconds apart in a JEOL 200CX microscope, and they show dissociation of a Frank dislocation into a Shockley partial dislocation and a Lomer dislocation (ie., a sessile lock).
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.
Electron microscopy of semiconductor and metal interfaces
Authors: Krivanek O. L. , Fathy D. , Fortner S.L. , Liliental Z. , Lodge E.A. , Stadelman P. A.
Published: June 2020

The ability to resolve 2-3Å structurally and 20-50Å chemically has made high resolution electron microscopy (HREM) and microanalysis the preferred techniques for a number of interface studies. The interfaces are usually examined in thin cross-sections cut normal to a major crystallographic direction along which the structure at the interface appears particularly simple in projection. A large number of such studies have now been carried out in a number of different laboratories, including the studies of semiconductor-oxide, semiconductor-semiconductor, and semiconductor-metal interfaces. An exciting new aspect of the studies is exploring the chemistry at the interface using a high resolution probe-forming instrument and either energy-dispersive X-ray spectroscopy(EDXS) or electron energy loss spectroscopy(EELS), since these studies can usally be performed on the same specimens as used for HREM, and a good correlation between the detailed atomic structure and the chemical composition can be achieved.
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.
The application of convergent beam electron diffraction and selected area diffraction techniques to interfacial studies in a duplex stainless steel
Authors: Parayil T. R. , Howell P. R.
Published: June 2020

As part of a wider investigation into the mechanism of recrystallization in a Duplex stainless steel, the structure of grain boundaries and interphase interfaces has been examined. In this later study, both convergent beam electron diffraction (C.B.E.D.) and selected area electron diffraction have been employed to determine the misorientation between grain boundaries and the orientation relationships developed between austenite and ferrite. The application of C.B.E.D. in this study has been particularly beneficial since the fine-scale of the microstructures encountered (e.g. see figure 1) greatly complicates the analysis of selected area diffraction patterns. The duplex steel (based on a composition 26%Cr, 5%Ni balance Fe) was solution treated at 1400°C, to produce a single phase ferritic structure, and quenched to room temperature. Specimens were then deformed 90% by cold rolling and annealed at 900°C (in the two phase austenite plus ferrite region) for times in the range 10s-8.6×104s. Specimens for transmission electron microscopy were prepared using standard techniques and examined in either a Philips EM300 or in a JEOL 1200EX.
Are pores necessary for the inward oxidation of FeCr alloys in 1%CO-CO2?
Authors: Newcomb S.B. , Stobbs W.M.
Published: June 2020

While the characteristic oxidation resistance of iron-chromium alloys has lead to considerable interest in the way in which oxidation is inhibited in this type of material, the mechanisms by which mature oxide scales are in general formed remain controversial. Under different circumstances, oxidation can occur by the migration of cations to the outer oxide surface, or by anion movement inwards towards the metal/oxide interface. During breakaway oxidation either process would clearly be facilitated through the mechanical failure of the scale so that the associated way in which oxidation then occurs rapidly can be easily explained. Pre-breakaway inward oxidation and carburization can however occur while mature scale is present and yet without its mechanical failure. The ease of this process has prompted the formulation of models for duplex oxide scale formation in which CO2 gains access to the metal/oxide interface via pores which are maintained in the outer scale.
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.
Effect of magnetic fields on the morphology of electrodeposited copper
Authors: Takeo H. , Mal S. , Dash J.
Published: June 2020

Some effects of magnetic fields on electrodeposition of copper have been reported previously. In our more recent experiments, a cell with horizontal electrodes was used with the same electrolyte. Applied magnetic field strengths (B) were in the range zero to 12.5 kG, and current density (CD) was either 80 mA/cm2 or 160 mA/cm2. Electrolyte temperature was either 15 ± 1°C or 24.5 ± 2°C, and the charge passed was 144 coulombs for each experiment
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.
Image analysis of electron microscope images using Boolean algebra operations
Authors: Krakow William
Published: June 2020

For real time television image processing of electron microscope images it is inefficient to have image arithmetic performed on a host computer which requires considerable CPU and transfer time overhead. It is usually more efficient to use an analog preprocessor before image display such as the shading correctors used for particle analysis. These techniques can also be applied to digital TV frame stores which have simple arithmetic units as preprocessors to a digital frame store. In this case sampled images are either added, subtracted or divided much as is done in many STEM type instruments at slower scan rates. Alternatively, the digital frame store can have an arithmetic and Boolean algebra processor capability which operates on digitized images in the frame store in real time. Such processors are available commercially and one has been adapted for use on various electron microscopes at the IBM Research Center.
[001] imaging of rutile: A problem in high-resolution microscopy
Authors: Self Peter G. , Buseck Peter R.
Published: June 2020

HRTEM images of the [001] zone of rutile (fig. 1) show 0.32 nm fringes near the edge of the crystal, but these rapidly change to 0.46 nm in the thicker parts of the crystal. This change in spacing is only possible if the intensities in the dynamically forbidden {100} reflections become comparable to the intensities of the {110} reflections. The {100} reflections are dynamically forbidden because the structure has 2-fold screw axes parallel to a and b and n-glides perpendicular to a and b. The presence of 0.46 nm rather than 0.32 nm fringe spacings in images of the thicker crystal regions presents a severe problem in matching the images to computer simulations. Fig. 2 shows [001] zone axis images for thin and thick crystals. As expected from symmetry, the computed images show only 0.32 nm spacings. In an attempt to explain the mismatch between computed and experimental images several effects not normally included in image calculations, and which could cause a change in the symmetry of electron diffraction patterns, were investigated, all without success.
A micro-refraction study of the potential field outside a gold crystal
Authors: Tan C.-S. , Cowley J.M.
Published: June 2020

Previously in observations made with small MgO crystals it was shown that when an electron beam of small diameter is made to run parallel to a flat face of the crystal, it may be deflected towards thp crystal by the potential field extending from the crystal into the vacuum. The deflection of the electron beam could be seen clearly in observations of microdiffraction patterns made with the optical detector system added to the HB5 dedicated STEM instrument. The direction and magnitude of the deflection and the form of the displaced spot were shown to be consistent with reasonable models from the field distribution. Because little appears to be known concerning the form of the field for insulators such as MgO, we have chosen to use gold crystals for attempts to determine quantitatively the form of the potential field. Various models have been used for the potential field.
Computer experiments for coherent convergent-beam electron diffraction
Authors: Krakow William
Published: June 2020

Considerable effort has been expended to use convergent beam electron diffraction (CBED) from small specimen areas with an incoherent thermionic source. Here space group classification and even three dimensional analysis have proven to be possible by observing the diffraction disks and the fine detail seen within these disks. The use of a coherent convergent beam has been attempted for a field emission STEM type instrument and a number of novel interference effects have recently been observed in both crystalline and amorphous materials. Preliminary CBED computer calculations were performed for a dislocation in Si3 however no structural detail was observed in the diffraction disks because the computation only considered a 30Å thick crystal. Computations covering a wide range of materials, specimen thickness values and STEM type probe conditions has been obtained by the present author. In these papers only results for zone axis patterns and 100kV electrons were given. It is now the intent to present some new results at high voltages (200kV) and for non-symmetric crystal orientations and with larger reciprocal space sampling distributions
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.
The influence of specimen thickness in quantitative electron energy loss spectroscopy: II
Authors: Zaluzec Nestor J.
Published: June 2020

In a previous paper it was shown that the influence of specimen thickness on quantitative electron energy loss spectroscopy (EELS) can be judged by measuring the intensity ratio of any two characteristic EEL edges as a function of thickness. If the specimen is homogeneous and thickness effects are neglegible then, one can show from Egerton’s formulation that this intensity ratio should be a constant. Any departure from a constant value indicates a breakdown of the quantitative theory due to thickness related effects. It was shown that if the ratio of Ip/IO (Ip = intensity of plasmon loss, IO = intensity of zero loss) exceeds ∼ 0.3 then quantitative analysis can be in significant error. In subsequent work Egerton showed that a better measure is the ratio of ℓn(It/IO) which is related to the ratio of t/λ. Here It is the total energy loss intensity, t the specimen thickness and λ the mean-free path for total inelastic scattering.
Three-dimensional reconstruction of the 30S E. coli ribosomal subunit
Authors: van Heel Marin
Published: June 2020

Various models of the 30S subunit have been proposed based on visual evaluation of electron micrographs. Recently, however, techniques have been developed which facilitate the evaluation of non-homogeneous populations of molecular images. Aligned images of macromolecules are thereby submitte to multivariate statistical analysis in the form of Correspondence Analysis (CA). Classes can be determined within the population of images with th aid of various automatic classification schemes. A pilot study indicated that these classes— as was expected— correlate highly to a particu lar (rotation) position of the molecules in the electron microscopical prepa ration. If we are, by some means, capable of assigning absolute angles to each projection class, a three-dimensional reconstruction of the 30S subunit becomes feasible. A first step towwards this goal is the "seriation" of the projection classes into their logical order: "the logical circle in hyperspace". For the analysis a population of 422 molecular images was selec ted including the 101 molecules used for the pilot study.
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.
Correlative microscopy of native surfaces of human lung: Color macrophotography, SEM, LM, TEM, HVEM, and low-temperature scanning electron microscopy
Authors: Bastacky J. , Hayes T. L. , von Schmidt B. , Klein S. B. , Barr J. , Finch G. L. , McKoon M. , Baskin L. , Hook G. R.
Published: June 2020

The power of microscopic analysis can be increased even though the resolution of the microscope remains constant if a native tissue surface is presented to the microscope. A surface that existsin vivobefore any cutting or handling of the tissue is a native surface. It preserves the most useful surface information present in the specimen and minimizes spurious information. in the case of human lung, the airway is dissected open as it branches, exposing its luminal surface. This preserves global properties such as connection and branching as well as local properties such as tissue and cellular structure. The surface of the airway is imaged at 100X with the scanning electron microscope (SEM) and the micrographs assembled into a montage, a 30"x40" map of the airway. These maps demonstrate the shape and branching pattern of the airway while preserving tissue detail with good resolution. The montage is a filing system for SEM micrographs that preserves positional information present in the sample. This information allows one to see patterns of ultrastructural features as a function of position along the airway, to see continuous variation without the need to break the airway down into a small number of regions. It allows precise localization of any structural feature along the airway for high magnification SEM and subsequent transmission electron microscopy (TEM) of the internal structure of the very same feature (figure 1).
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).
Structural analysis of co-crystals of actin and DNase I by electron microscopy and image processing
Authors: Fowler Walter E. , Loren Buhle E. , Aebi Ueli
Published: June 2020

Actin is known to specifically interact with a variety of intracellular proteins. Some of these interactions, for instance that of actin with myosin, are of obvious functional importance and have been extensively characterized, both biochemically and structurally. Other interactions, such as that of actin with DNase I, have not yet been correlated with specific cellular functions. In any case, the interaction between actin and DNase I has proven to be useful in both biochemical and structural studies. The two molecules form a tight 1:1 complex that inhibits the functions of both molecules: i.e. actin cannot polymerize into filaments any more and DNase I loses its enzymatic activity. The actin-DNase complex has been crystallized and a .6nm three-dimensional model of the complex has been obtained. Unfortunately, separation of the map into an actin and a DNase I part is ambiguous at this stage.
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.
Freeze-etch studies on the gametocytes of Plasmodium falciparum
Authors: Meszoely Charles A.M. , Erbe Eric F. , Steere Russell L. , Palmer Timothy , Beaudoin Richard L.
Published: June 2020

The Erythrocytic stages of the Honduras strain of the malarial parasite Plasmodium falciparum were maintained in tissue culture medium RPMI 1640. Red blood cells containing gametocytes and other erythrocytic stages were fixed in 2% glutaraldehyde, and cryoprotected in 30% glycerol in H2O. This preparation was freeze-etched for one minute at -98°C in a modified Denton DFE-2 freeze-etch module. Stereo pairs with specimen tilt of 10 between electron micrographs were obtained with a JEM-100B transmission electron microscope equipped with a 60° top entry goniometer stage.

The fine structure of the gametocytes of malarial parasites has been studied by conventional electron microscopic methods [stained ultrathin sections (2 and 3)], but this stage of the life cycle has not been demonstated previously with freeze-fracture studies.

Since the red blood cells in our preparation also contained other stages of the life cycle, the following combination of characteristics were used to differentiate the gametocytes: presence of microtubules; food vacuoles; and large size.

Microtubules are not found in trophozoites, and merozoites are relatively small and do not contain food vacuoles.
Multilamellar body size comparison from lung of embryos and hatchlings of chick
Authors: Blystone Robert V. , Souder Genny , Hass Dawn
Published: June 2020

The functional lung of a newborn animal requires surfactant for the purpose of reducing the surface tension at the airtissue interface. Reduced surface tension prevents the lung from collapsing due to high pressures associated with ventilation and lung geometry; and also lowered tension assists in the movement of respiratory gases in and out of the lung tissue. Surfactant first appears late in lung development and correlates with the appearance of a morphological structure in Type II alveolar cells called a multilamellar body. The multilamellar body (LAM) is comprised mainly of phospholipids which serve as the principal ingredient of lung surfactant. The study here reported involves a comparison of multilamellar body size just before and after hatching of white leghorn chick.

Eggs of Gallus domesticus, white leghorn breed, were incubated at 99 3/4°F at a relative humidity of 50-56%. Fertile eggs weighing between 50 and 70 grams were divided into two groups: 1) group one eggs were incubated nineteen 24-hour periods before sacrifice and 2) group two eggs were allowed to hatch and sacrificed twenty-two 24-hour periods after the onset of incubation.
Cell adhesion molecules in Dictyostelium: Identification with monoclonal antibodies
Authors: Baronde S. H. , Springer W. R.
Published: June 2020

Cells in multicellular organisms occupy specific positions in relation to each other. This is brought about by a complex series of factors, one of which is believed to be the interaction of molecules on cell surfaces with those on other cells or the extracellular matrix. The molecules presumed to mediate these functions have been designated cell adhesion molecules and cell recognition molecules. The former indicates that they play a direct role in the adhesion process, while the latter indicates that they mediate the selectivity of adhesion. One molecule might serve both a recognition and an adhesion function but, given the complexity of cell surfaces, recognition and adhesion could also be separate, and possibly sequential, processes.

We have chosen to study the problem of cell-cell adhesion in cellular slime molds because these relatively simple eukaryotic organisms have many properties that facilitate experimental work on this complex problem:
Cell surface antigens in early mammalian development
Authors: Johnson Lincoln V. , Calarco Patricia G. , Ploack-Charcon Syivia
Published: June 2020

Cell surface molecules are known to be functionally important In a number of developmental systems. Molecular components of the cell surface may participate in Intercellular adhesion, recognition and communication. Reactions occur r Ing at the cell surface may also influence developmental events by Induci ng i ntracelIular changes In cellular metabolism and gene expression which may, In turn, alter the composition and/or organization of surface components. Sequences of reactions mediated by cell surface molecules are probably Important In directing undifferentiated embryonic cells along specific dlfferentlatlve pathways.

In the early development of the mammal Ian embryo, important events occurring during the preimplantation period are likely to require the participation of specific cell surface molecules. For example, these are likely to Include sperm-egg attachment and fusion, Interbl astomere adhesion, blastulatlon, and attachment of the blastocyst to the uterine epithelium. During preimplantation mouse development, specific stage-relaged changes in the qual itatlve and quantitative nature of the proteins synthesized and those expressed on the cell surface have been documented.
Ultrastructural imaging of whole cells by cryo-HVEM
Authors: Fotino Mircea , Giddings Thomas H.
Published: June 2020

A cryostage cooled by liquid nitrogen has been recently completed and activated on the top-entry 1 MV JE0L JEM-1000 of the National Facility for high-voltage electron microscopy in Boulder, Colorado. It provides continuous and controlled cooling of a specimen during observation at an arbitrary temperature in the range 78K to room temperature. Good thermal stability of about ± 0.1K can be achieved by maintaining an appropriate balance between refrigerant flow and heat provided by an automatically controlled built-in heater. Consequently the overall specimen drift is reduced so that high-resolution lattice images of graphitized carbon (spacing 0.34 nm) and Sn/SnTe alloy (spacing 0.31 nm) can be obtained throughout the temperature range.

The interest of such cryoimaging is primarily to view hydrated specimens in frozen form, to explore the advantages of fast freezing and freeze-drying as an alternative to chemical fixation and dehydration, and possibly to benefit from a certain reduction in radiation damage known to take place at low temperatures. Frozen specimens are placed onto the cold cryostage in about 5 minutes with a mechanism developed specifically for this purpose. Thus the specimens are kept continuously immersed in liquid nitrogen, and unexposed to the atmosphere, between freezing and insertion into the air lock leading into the instrument column.
Observation of reconstituted Lumbricus terrestris hemoglobin with the STEM
Authors: Kapp O. H. , Ohtsuki M. , Crewe A. V. , Vinogradov S. N.
Published: June 2020

The annelid extracellular hemoglobins are giant heme containing respiratory proteins (3-4x106 MW) possessing an extraordinary range of physiological function, Their electron microscopic appearance is that of two superimposed hexagons with approximate dimensions of 300 x 200Å by STEM. These unusual proteins are composed of multiple copies of as many as six distinct polypeptides ranging in size from 13 to 37,000 MW as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Possessing approximately 150 hemes per molecule, they represent an alternate solution to the demand for increased efficiency of oxygen transport imposed by the evolution of multicellular organisms.

The hemoglobin of Lumbricus terrestris dissociates at alkaline pH yielding a broad overlapping distribution of molecular weight species ranging in size from 25 to 300K. Exposure to 0.05M sodium borate buffer, pH 9.0, for 24 hours, followed by gel filtration on a column of Sepharose C1-6B equilibrated in the same buffer, gives the elution profile shown in Fig. 1.
Imaging of the alpha-chain extensions of fibrinogen
Authors: Price Todd M. , Rudee M. L.
Published: June 2020

Amorphous carbon, as well as a few polymeric materials, are used routinely as substrates for the electron microscopic examination of macrorno1ecules. Replication of molecules from a cleaved mica surface is also used. The choice is ty pically made on the basis of convenience, and limited to commonly used materials.

In the course of research on the interaction of plasma proteins with several non-biological materials we observed that the use of substrate materials that were not typical in electron microscopy produced images that revealed hitherto unobserved features of certain macromolecules. This paper will describe the techniques we have developed to image additional features of fibrinogen, give some additional results, and describe some experiments undertaken to elucidate the basis of the technique.
Colloidal gold double labeling of two secretory proteins in bacterial cell
Authors: Tinglu Guan , Ghosh Arati , Ghosh Bijan K.
Published: June 2020

Secretory proteins have been localized in bacterial cells by inmunoelectron-microscopy and cytochemical methods. Although ferritin-antibody technique is satisfactory for the localization of single antigenic sites, multiple labelling is not possible by this technique. However, such multiple labelling is possible using colloidal gold antibody because colloidal gold of widely varying sizes can be prepared by simple laboratory manipulation. We prepared colloidal gold of two different sizes and labelled these with anti-penicillinase and anti-alkaline phosphatase antibodies. These labels were used to determine the location of penicillinase and alkaline phosphatase in secreting Bacillus licheniformis 749/C cells.

Large colloidal gold particles (150Å) were prepared by 10% sodium citrate treatment of 0.01% HAuCl4; the pH of this colloidal gold suspension was adjusted to 7.6 with 0.2 M K2CO3. Small colloidal particles (50A) were prepared by treating 0.01% HAuCl4, after pH was adjusted to 8.0 with 0.2M K2CO3, withphosphorous saturated ether. The large or small gold particles (1010 in 10 ml) were treated with 100μg of anti-alkaline phosphatase or anti-penicillinase antibodies; after thorough mixing unbound antibodies were removed by centrifugation.
Golgi processed foot-and-mouth disease virus proteins
Authors: Wool S. H. , Polatnick J.
Published: June 2020

The Golgi apparatus was isolated from infected baby hamster kidney cells by centrifugation through discontinuous sucrose gradients. Tritium-labeled protein samples were analyzed by polyacrylamide gel electrophoretic autoradiograms. Pulse-chase studies showed that the viral-induced RNA polymerase passed through the Golgi as infection progressed. Some viral coat proteins were also associated with the Golgi as were other as yet unidentified viral proteins (Fig. 1). Immune labeling of isolated and in situ Golgi confirmed the presence of viral RNA polymerase. The isolated (Fig. 2) and in situ Golgi were labeled with guinea pig antipolymerase antibody and ferritin-labeled goat anti-guinea pig sera to show the presence of viral RNA polymerase.

Earlier work in this laboratory established that the RNA polymerase was bound to membranes of newly formed smooth vacuoles during infection with FMDV. The smaller protein on the gel in Fig. 1 (arrow) corresponds in size to VPg (a nonstructural protein bound to the 5' end of viral RNA) has also been shown to be membrane bound.
Ultrastructural changes in sciatic nerve tissue: Effects of passive maternal smoking
Authors: K.S. Amankwah , Weberg A.D. , Kaufmann R.C.
Published: June 2020

Previous research has revealed that passive (involuntary inhalation) tobacco smoking during gestation can have adverse effects upon the developing fetus. These prior investigations did not concentrate on changes in fetal morphology. This study was undertaken to delineate fetal neural abnormalities at the ultrastructural level in mice pups exposed in utero to passive maternal smoking.

Pregnant study animals, housed in a special chamber, were subjected to cigarette smoke daily from conception until delivery. Blood tests for determination of carbon monoxide levels were run at 15-18 days gestation. Sciatic nerve tissue from experimental and control animals were obtained following spontaneous delivery and fixed in 2.5% gluteraldehyde in 0.1M cacodylate buffer pH 7.3. The samples were post-fixed in osmium ferrocyanide (1:1 mixture of 1.5% aqueous OSO4 and 2.5% K4 Fe(CN)6). Following dehydration, the tissues were infiltrated with and embedded in Spurr. Sections were stained with uranyl acetate and lead citrate.
Extracellular matrices and the control of cell proliferation and differentiation in vitro
Authors: Gospodarowicz D.
Published: June 2020

Recent investigations suggest that, in vitro, cell-substratum interactions may play other roles in addition to cell anchorage. The extracellular matrix (ECM) that cells can produce and upon which they rest can be held responsible for the final shape the cells will adopt. This shape in turn may play a role in the cell's response to serum factors and its differential response to various growth factors. Components of the ECM produced by cells have also been shown to be involved in cell differentiation and the control of gene expression, as well as in cell attachment. Even soluble matrix components can affect cell shape and the organization of their basal surface and cytoskeleton by stimulating ECM synthesis.

One of the major limitations of tissue culture techniques currently in use is that cells rest on plastic. Unless cultured cells can produce their own ECM, the possibility exists that contact with plastic could inhibit them from proliferating or could cause them to lose rapidly their ability to express their correct phenotype. In the present review, we will outline recent studies of the behavior of cells maintained on dishes coated with ECM of known composition. The use of such a substrate for the long-term culture of normal diploid and tumor cells will be described.
The response of a mixed cell population in mouse testes to x-ray and HZE irradiation
Authors: Philpott D. E. , Sapp W. , Williams C. , Stevenson J. , Black S. , Corbett R.
Published: June 2020

The testes sperraatogonial population differentiates from a stem cell (As) which, via a series of mitotic divisions, gives rise to spermatocytes. The spermatocytes undergo reductional meiotic divisions and mature into sperm. Short cellular life cycles make the testes an excellent tissue for quantitative studies of radiation effects.

Brown B6D2F1 mice, aged 14 weeks, were exposed to Helium particle radiation (227 MeV) in the Berkeley 184 inch synchocyclotron and to x rays at 225 KvP and 15 mA. Doses ranged from 1 to 100 rads. Tissues were fixed in Triple Fix and embedded. Two-micron sections were stained with Toluidine Blue, and ultra-thin sections were stained in the standard manner for electron microscopy. All studies were done on the tissues 72 hrs after irradiation.

Our previous work, on cell survival after graded doses of radiation, has shown a steeper slope (more sensitive response) in the low dose range below 20 rads. By convention, the resulting points were plotted by linear regression resulting in a "best fit" straight line.