bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct observation of displacement cascades in Cu3Au
Authors: Jenkins M.L. , English C.A.
Published: June 2020

Materials within fission reactors are exposed to fluxes of fast neutrons with energy up to a few MeV, whilst the first wall of a future fusion reactor will be bombarded with neutrons of energy peaking at about 14MeV. The consequent radiation damage leads to serious problems in reactor design. For this reason one of the major objectives for much recent research has been to try to understand the mechanisms of the damage created by fast neutrons. Damage accumulates only rather slowly in fission reactors, so neutron damage effects in fission reactors have often been simulated by charged- particle bombardment using accelerators of various types. Similarly there will be a tendency in the future to extrapolate data obtained with fission-neutrons to the more energetic fusion-neutrons because no high-flux source of fusion-energy neutrons is available. One of the difficulties of the simulation approach is that the various irradiation methods produce different energy spectra of primary knock-on atoms.
Lattice defects in deformed and irradiated Zr3al
Authors: Howe L.M. , Rainville M.H.
Published: June 2020

Zr3Al is an ordered f.c.c. alloy of the Ll2 type which forms via a peritectoid reaction. It has not been possible to disorder Zr3Al by quenching and no antiphase domain boundaries have been observed, in either annealed or quenched material which indicates that Zr3Al is normally present in a highly ordered state. In deformed Zr3Al the superlattice dislocations were observed to be extended i.e. they consisted of intrinsic stacking faults on {111} bounded by partial dislocations (figure 1). The total Burgers vector is of the type <110> and the superlattice dislocations have dissociated as follows:. The Burgers vectors were determined using the criterion that the partial dislocations will be out of contrast for g.b = 0, ± 1/3 as well as for g.b = -2/3 when s > 0.

During high temperature annealing of the deformed material, dislocation networks were produced in which all of the dislocation nodes were extended: hence intrinsic (I) and extrinsic (E) stacking faults must alternate at the nodes (figure 2).
Grain boundary structure of gold analyzed by high resolution HVEM
Authors: Ichinose H. , Ishida Y. , Mori M.
Published: June 2020

For researchers involved in grain boundary studies the observation of atomic configuration at the boundary has long been a dream. Various issues of grain boundary theories should be settled by the observation. Atoms may be observed also by field-ion microscopy, but it shows only a portion of atoms protruding on the surface of the specimen tip. The boundary itself appears as a dark band a few atoms wide. Two dimensional lattice image should have a potential to carry the task instead. Not only the geometrical information of atoms but also of electron density at the boundary might be obtained. The interface structure has been observed by the lattice image for oxides, intermetallic compounds or semi-conductors, but for simple metals the work has been scarce. The unit cell is so small that a high voltage electron microscope was necessary to obtain a many-beam interference image faithful enough with the atomic structures at the boundary.
Diffraction effects from inclined grain boundaries in polycrystalline thin foils
Authors: Carter C.B. , Donald A.M. , Sass S.L.
Published: June 2020

Using thin-film gold bicrystals with the boundary plane parallel to the foil surface, it has been shown(l,2) that networks of grain boundary dislocations can act as diffraction gratings and give rise to subsidiary reflections close to the matrix reflections in electron diffraction patterns. Recently several groups of workers(3-5) have shown that inclined boundaries in polycrystalline specimens also produce extra reflections which may be due to the periodic nature of the boundaries. In general grain boundaries in polycrystalline specimens will be steeply inclined to the foil surface and additional reflections due to wave matching at the boundary(6) will also be present. The diffraction technique has the potential for providing detailed information on the structure of inclined boundaries (see, for example (5)), especially for the case where the image contains no useful information. In order to provide a firm basis for this technique, the geometry of the diffraction effects expected from inclined boundaries and the influence of these effects on the appearance of images will be examined.
The direct determination of magnetic domain wall profiles using a split detector STEM
Authors: Chapman J.N. , Batson P.E. , Waddell E.M. , Ferrier R.P.
Published: June 2020

By far the most commonly used mode of Lorentz microscopy in the examination of ferromagnetic thin films is the Fresnel or defocus mode. Use of this mode in the conventional transmission electron microscope (CTEM) is straightforward and immediately reveals the existence of all domain walls present. However, if such quantitative information as the domain wall profile is required, the technique suffers from several disadvantages. These include the inability to directly observe fine image detail on the viewing screen because of the stringent illumination coherence requirements, the difficulty of accurately translating part of a photographic plate into quantitative electron intensity data, and, perhaps most severe, the difficulty of interpreting this data. One solution to the first-named problem is to use a CTEM equipped with a field emission gun (FEG) (Inoue, Harada and Yamamoto 1977) whilst a second is to use the equivalent mode of image formation in a scanning transmission electron microscope (STEM) (Chapman, Batson, Waddell, Ferrier and Craven 1977), a technique which largely overcomes the second-named problem as well.
Pulse switching of magnetic films at low temperatures
Authors: Bostanjoglo O. , Gemünd H.P.
Published: June 2020

Magnetic wall motion is expected to keep below a maximum velocity, about 800 m/s for NiFe films (1). However, previous measurements on extraordinary viscous (2) wall motion (3), did not reveal any maximum velocity. This paper reports on vestigations extending to higher fields than in (3).The wall velocity v in uniaxial 83 at % NiFe films was determined as a function of easy axis magnetic field H and temperature. The field pulse method was used and the wall displacements were detected by electron microscopy within the range of extraordinary viscosity (4... 30 K).

The field pulses were generated by a Helmholtz coil (fig. 1) energized by the discharge of a coaxial cable via a pulse shaping spark gap. Rectangular pulses up to 25 kA/m and of widths 10 ns... 3 us with rise/decay time below 15 ns were attained. For cooling the specimen down to 4 K and to minimize distortions of the field due to eddy currents, the specimen holder was a single crystal sapphire, gripped by a high-purity copper holder outside the magnetic field and mounted in a liquid He cooling stage for TEM.
Transformation-induced defects in α-cristobalite
Authors: Lally J.S. , Nord G.L. , Heuer A.H. , Christie J.M.
Published: June 2020

Transformation-induced twins and antiphase domain boundaries have been observed in both lunar and terrestrial cristobalite. The lunar cristobalite is from mare basalts 12038, 12053 and 70017, whereas the terrestrial material is from San Cristobal, Mexico. All of these samples contained defects resulting from the transformation of the high temperature or β polymorph, usually assumed to be face-centered cubic Fd3m, to α- cristobalite, the low temperature form which is primitive tetragonal P41 212 or P43 22 2. The distribution of defects in all samples is quite heterogeneous; the San Cristobal sample had more defects than the lunar samples. In addition, electron-beam damage is considerably slowed in the lunar cristobalite.

Two types of defects were present (Fig. 1). The first consists of twin boundaries which form because any of the three cube axes can become the tetragonal c-axis; this has been previously observed optically and by X-ray diffraction. A second defect consists of domain boundaries (Fig. 2) which appeared to have been produced after the twin boundaries were formed.
The detection of latent nuclear particle tracks in some common minerals with conventional TEM
Authors: Fraundorf P.
Published: June 2020

Although the first direct photographs of nuclear particle tracks in solids were obtained using a TEM (1), the tendency of the tracks to fade in natural micas under the electron beam, as well as the difficulty of preparing suitably thin samples, resulted in the use of optical and scanning electron microscopy to observe chemically enlarged (etched) tracks in the study of lunar soils and gas-rich meteorites in the early 1970's. However, the possibility of useful applications for conventional (100 kV) TEM in the examination of latent tracks was seldom mentioned.

More recently, the emphasis on the study of submicron-sized grains in extraterrestrial materials research has made feasible the use of conventional TEM for ultrastructural studies without the complications of, or need for, ion thinning techniques (e.g. 3, & 4). In the process, many of the minerals examined have shown that latent fission-fragment tracks are easily observed with conventional TEM. The tracks, usually introduced by spontaneous fission from a “thin” Cf2 5 2source, appear to exhibit “density” contrast from a straight core whose average width depends upon the mineral.
Clay-sized quartz produced by crushing
Authors: Mckee Thomas R. , Krinsley David
Published: June 2020

Although sand and silt-sized quartz have been studied extensively, clay-sized quartz has received scant attention, despite the fact that its nature and production are of considerable interest to sedimentologists, geochemists, and workers in the field of environmental health. Blatt and Schultz have shown that the quartz content of mudstones is about 28%, and of that portion, about 15% is clay-sized (1). The bulk of fine grained quartz in recent sediments and man's immediate environment is produced by crushing or breaking of larger particles during transport and abrasion. Comminution of quartz produces surface structural changes, disrupted lattice zones or conversion to glass (2). Experimental models of earthquake fault zones using quartz sandstone as sliding surfaces have produced quartz and glass <0.06μm in diameter (3). Larger claysized quartz particles (>1μm) have been characterized (4); however, an attempt to differentiate quartz and glass <0.5μm has met with only limited success (3). High resolution transmission electron microscopy (HRTEM) now permits new opportunities to examine very fine grained material, as indicated below.
Convenient multi-channel averaging for electron energy loss spectroscopy in the STEM
Authors: Batson P.E. , Chapman J.N. , Craven A.J. , Ferrier R.P.
Published: June 2020

Electron energy loss spectroscopy (EELS) of electrons which have produced excitation of atomic electron core states promises to provide a powerful microanalytical tool. To assess fully the range of applications of the technique and its ultimate sensitivity in any given circumstance,accurate cross-sections differential in energy and scattering angle are required for both the characteristic energy loss electrons and for those loss electrons which contribute a background. In addition there is the possibility of gaining additional information on the nature of the specimen from the fine structure at the energy loss edge (Isaacson and Johnson 1975) and from the extended fine structure (EXELFS) beyond the edge (Colliex et al 1976), although neither of these phenomena are as yet well understood.

We are currently investigating a number of aspects of EELS using a Vacuum Generators HB5 FEGSTEM at the Cavendish Laboratory, Cambridge. This is fitted with a magnetic spectrometer with air cored magnetic deflection at the magnet exit which can provide rapid energy scans without hysteresis.
In-situ observation of reversible twinning in U3Si
Authors: Kimmel G. , Admon U. , Zangvil A.
Published: June 2020

The intermetallic compound U3Si has the cubic δ' structure between 765-900°C, and the tetragonal δ structure at lower temperatures. The δ' → δ transition always results in a twinned martensitic structure. Double shear causes the appearance of bands and sub-bands (1).

Plastic deformation of martensitic U3Si is accompanied by detwinning, since only one of the twins is usually favorable from the point of view of the external stress. This was confirmed by optical metallography as well as by texture analysis (2).

The present work describes a memory effect observed during a study of plastically deformed (⩽2%) martensitic U3Si.

TEM specimens were prepared from lateral sections of standard tensile test samples. The principal stress direction was thus perpendicular to the foil.

Fig. 1 shows the twinned structure of the martensite before deformation.

Primary and secondary twins can be seen. The twinning systems are {101}<101> in FCT coordinates ({112}<111> in BCT coordinates). This was inferred from trace analyses.
Effects of a second phase on the impact strength of structural steels
Authors: Gréday T. , Mathy H.
Published: June 2020

Both steel producers and users are faced with the problem of evaluating steel toughness. This property depends on the steel microstructure and, more particularly, on the presence of second phase particles. Consequently is important the knowledge of how fracture mechanisms are related to those particles. Also, quantitative relationships between second phase particles and properties are requested. Results have been obtained using a SEM equipped with peripherals. X-ray spectrometers and image analysis (1,2) as well as a TEM working on thin foils. Studied second phases range from microprecipitates in HSLA steels to coarser particles such as : inclusions, cementite, pearlite and bainite or martensite islands. In each case, characterization has been attempted of their size, shape, nature and distribution. Toughness is defined by transition temperatures or by shelf energy. Pearlite islands can initiate, stop or deflect a local crack. Deflection brings into relief 2 facets of the pearlite island when it deflects a cleavage crack originated by 2 adjacent grains (Fig.l).
H.V.E.M. observation of the nucleation of martensite in stainless steel
Authors: Brooks J.W. , Loretto M.H. , Smallman R.E.
Published: June 2020

INTRODUCTION

The mechanisms involved in the formation of martensite nucleii are still uncertain despite extensive investigations. Earlier work (e.g. Kelly and Nutting, 1961; Mangonon and Thomas, 1970; Fujita and Ueda, 1972) had suggested that stacking faults are important in the formation of ε martensite. Mechanisms have been proposed to account for the fact that α martensite can be formed at the intersection of faulted Regions (Bogers and Burgers, 1964) and for the formation of ε martensite from 1/6<112> partials ( Mahajan et al. 1977).

In an attempt to remove the uncertainties we have observed directly the formation of ε and α martensites in stainless steels both during in situ deformation and during cooling.

EXPERIMENTAL

High purity low carbon stainless steel of various compositions which transform to a martensite and ε martensite (with c/a less than ideal), produced by induction melting under argon, were rolled down into tfiin sheets suitable for preparing electron microscope specimens. These were then annealed to reduce the dislocation density.
TEM -analysis of the BeO-dispersion in high purity Be-ingots
Authors: Migge Hans
Published: June 2020

Inclusions of BeO are of tremendous importance on the mechanical properties of Beryllium [1,2]. The BeO particle sizes of different hot pressed materials are in the range between 400 Å and 10 μm for BeO contents between 0.5 and 3.6%[3]. However, there is no investigation about the BeO dispersion in high purity (<200 ppm BeO) ingots. Information on this subject should be derived from the diffuse Debye rings of BeO, which as yet are thought to come from the very thin oxide scale on the Be-surface [3].

0.1 mm foils of Berylco IF—1 from KBI with BeO < 200 ppm were analyzed at 100 kV in the as received condition or after annealing for 1 hour at 900°C in ultrahigh vacuum. With the electron beam parallel to [00.1], [11.1], [02.1], [12.1], [03.1], [12.2] (using different grains) always four diffuse BeO rings of the type {10.0}, {10.1}, {11.0}and the unresolved {20.0}/{11.2} appear in the SAD-pattern.
Electron microscopy observations of high temperature phase transitions in incongruent subliming materials
Authors: Schiffman R.A. , Mitchell M.J.
Published: June 2020

Scanning and transmission electron microscopy investigations led to a new method of studying binary phase systems by observing the properties of samples whose composition or temperature is changing, either independently or simultaneously. The research produced a complementary method of describing complex temperature-composition diagrams. The nickel-sulfur system was chosen since it has been thoroughly investigated by other methods. The thermodynamics of binary metal systems have been described by Lundqvist, Rosenqvist and Kullerud and Yung using x-ray diffraction and thermal analysis. These methods began by preparing, at room temperature, the metal-sulfide composition desired. The temperature was then raised so that a constant composition line could be studied. As the temperature was changed, horizontal phase boundaries could be well defined. It is difficult, however, to use these methods to define vertical phase boundaries.

Nagamori and Ingraham; Meyer, and Rau used weight loss measurements in a gas equlibrium to study limited parts of the nickel-sulfur system.
The direct visualization of macromolecular complexes in redundant cytomembrane systems with particular reference to peripheral nerve myelin
Authors: Pease Daniel C.
Published: June 2020

A combination of little used preparative techniques permits the visualization of macromolecular complexes in peripheral nerve myelin. They can be employed effectively as well for similar particulate recognition in at least some other redundant cytomembrane systems, i.e. retinal disc membranes. The cores of the globular structures are thought to be the integral proteins of the membrane system, in glutaraldehyde-fixed myelin probably associated with phospholipid annuli.

Fixation is limited largely to aldehydes, with osmium tetroxide being particularly contraindicated. Cadmium ions, which form water-insoluable salts with lecithins, seem to offer some advantages when included with a glutaraldehyde fixation. Tannic acid as a secondary fixative has proven necessary when embedments are to be avoided.
Acetonitrile: Substitute for propylene oxide in tissue processing for transmission electron microscopy
Authors: Tarnowski Betty I. , Schonbaum Gregory R.
Published: June 2020

The use of an organic solvent is integral to tissue processing for transmission electron microscopy (TEM). Ideally, such a solvent should be (a) nontoxic, nonflammable and of low viscosity; (b) miscible with water, alcohol and epoxy resins; and (c) compatible with epoxy resin polymerization (1). Propylene oxide, a solvent commonly used in TEM studies, meets most of the above criteria; however, it is highly flammable, toxic, mutagenic, cytogenic and carcinogenic (2). Its replacement by a less hazardous compound, therefore, is desirable. Acetonitrile, like propylene oxide, is inexpensive, available in high purity, and is miscible with water, alcohols, acetone and epoxy resins. Also, acetonitrile does not interfere with polymerization and the resulting cured resins are typified by excellent cutting quality and beam stability. Most importantly, acetonitrile is noncarcinogenic (2), less toxic (3) and not as flammable as propylene oxide.
Fine structural features in tumor diagnosis
Authors: Spurlock Ben O.
Published: June 2020

The primary objective in submitting a specimen to the electron microscopy laboratory is to obtain additional information about the tissue which is not readily available employing conventional light microscopic techniques. In order for this analysis to be meaningful every effort must be taken to assure that the tissue is observed with minimal alteration of its structural components. Tissue which has been frozen, embedded in paraffin or placed in standard laboratory formalin will seldom exhibit the structural fidelity needed to justify the time and expense of an electron microscopic examination. While there are numerous reports on how tissues processed in this manner can, as a last resort, be retrieved for diagnostic use I suggest that the better method is to educate your staff on the proper selection and collection of specimens for possible ultrastructural evaluation.
The electron microscope in modern diagnostic neuropathology
Authors: Wolfe David
Published: June 2020

Despite its major historical and continuing importance in experimental neurobiology/histology, and its ongoing elucidation of ultrastructural abnormalities in human disease, the electron microscope remains at best an ancillary tool in strictly diagnostic human neuropathology. It is hard to think of any disease of the nervous system or of skeletal muscle in which a diagnosis could not be made without electron-microscopic input. Though diagnostic in many neuropathology conditions, ultrastructural appearances rarely provide the initial diagnosis under the Anatomic Pathology procedures operative in virtually all large modern medical centers. Nevertheless, I shall present three cases in which routine electron microscopy did in fact first indicate the correct diagnosis, to underscore the advisability of routinely taking representative portions of neuropathological specimens for electron microscopy both for immediate diagnostic back-up and for archival and pedagogic purposes.
Calmodulin-mediated gating of lens gap junction channels in vesicles
Authors: Peracchia Camillo , Girsch Stephen J.
Published: June 2020

The fiber cells of eye lens communicate directly with each other by exchanging ions, dyes and metabolites. In most tissues this type of communication (cell coupling) is mediated by gap junctions. In the lens, the fiber cells are extensively interconnected by junctions. However, lens junctions, although morphologically similar to gap junctions, differ from them in a number of structural, biochemical and immunological features. Like gap junctions, lens junctions are regions of close cell-to-cell apposition. Unlike gap junctions, however, the extracellular gap is apparently absent in lens junctions, such that their thickness is approximately 2 nm smaller than that of typical gap junctions (Fig. 1,c). In freeze-fracture replicas, the particles of control lens junctions are more loosely packed than those of typical gap junctions (Fig. 1,a) and crystallize, when exposed to uncoupling agents such as Ca++, or H+, into pseudo-hexagonal, rhombic (Fig. 1,b) and orthogonal arrays with a particle-to-particle spacing of 6.5 nm. Because of these differences, questions have been raised about the interpretation of the lens junctions as communicating junctions, in spite of the fact that they are the only junctions interlinking lens fiber cells.
Toward the biochemistry of individual molecules
Authors: Wall J. S. , Hainfeld J. F.
Published: June 2020

One goal of the Brookhaven STEM group is to enhance the capabilities of the electron microscope as a biochemical tool, while attempting to open up a new field: the Biochemistry of Individual Molecules. Three aspects of molecular biology seem particularly tractable with the STEM (Scanning Transmission Electron Microscope):

Size, shape and molecular weight

Active sites: location and environment

Interactions in complex systems

All these areas have been explored to some extent by conventional microscopy, but definitive conclusions are elusive because of low contrast and radiation damage which usually require staining or shadowing to “see” anything. Periodic features may be rendered faithfully, but detailed interpretation falls prey to arguments about positive vs. negative staining, decoration vs. shadowing, flattening, shrinkage, and other such phenomenon.
Ultrastructural changes in migrating leukocytes in the liver following lethal E. coli bacteremia in rats
Authors: Sato T. , Berezesky I.K. , Hirai F. , Nakatani T. , Trump B.F.
Published: June 2020

Hepatocellular injury and dysfunction after Gram-negative sepsis have been well recognized in both humans and experimental animal models (1,2) with circulating septic components being attributed to producing the hepatocellular injury. We have previously shown, in a lethal E. coli bacteremic rat model, the progressive migration of leukocytes and foci of hepatic lesions along with release of liver enzymes (2). In those studies, hepatic lesions were randomly scattered throughout the liver but were prominent in midzonal regions where migrated and aggregated leukocytes were frequently seen, suggesting that there may be some correlation between the presence of leukocytes and damage to hepatic parenchymal cells (2). In the same model, infiltration of leukocytes into the myocardial interstitium was also noted (3), possibly contributing to the observed myocardial dysfunction.
Electron microscopic radioautographic studies on the incorporation of 3H proline in the glomerular basement membrane (GBM) in antistreptococcal-cell-membrane (SCM) injected mice
Authors: Nayyar R.P. , Lange C.F. , Borke J. L.
Published: June 2020

Streptococcal cell membrane (SCM) antiserum injected mice show a significant thickening of glomerular basement membrane (GBM) and an increase in mesangial matrix within 4 to 24 hours of antiserum administration (1,2,3). This study was undertaken to evaluate the incorporation of 3H proline into glomerular cells and GBM under normal and anti-SCM induced conditions. Mice were administered, intraperitoneally, 0.1 ml of normal or anti-SCM serum followed by a 10 µC/g body weight injection of 3H proline. Details of the preparation of anti-SCM (Group A type 12 streptococcal pyogenes) and other sera and injection protocol have been described elsewhere (2). After 15 minutes of isotope injection a chase of cold proline was given and animal sacrificed at 20 minutes, 1,2,4,8,24 and 48 hours. One of the removed kidneys was processed for immunofluorescence, light and electron microscopic radioautographic studies; second kidney was used for GBM isolation and aminoacid analysis.
Annulate lamellae in the Sertoli cells of guinea pig testis after unilateral torsion of the spermatic cord
Authors: Chakraborty J. , Sinha Hikim A. P. , Jhunjhunwala J. S.
Published: June 2020

Although the presence of annulate lamellae was noted in many cell types, including the rat spermatogenic cells, this structure was never reported in the Sertoli cells of any rodent species. The present report is based on a part of our project on the effect of torsion of the spermatic cord to the contralateral testis. This paper describes for the first time, the fine structural details of the annulate lamellae in the Sertoli cells of damaged testis from guinea pigs.

One side of the spermatic cord of each of six Hartly strain adult guinea pigs was surgically twisted (540°) under pentobarbital anesthesia (1). Four months after induction of torsion, animals were sacrificed, testes were excised and processed for the light and electron microscopic investigations. In the damaged testis, the majority of seminiferous tubule contained a layer of Sertoli cells with occasional spermatogonia (Fig. 1). Nuclei of these Sertoli cells were highly pleomorphic and contained small chromatinic clumps adjacent to the inner aspect of the nuclear envelope (Fig. 2).
The effect of bromocriptine on mammary-gland ultrastructure of hyperprolactinemic rats
Authors: Murray I.C.
Published: June 2020

In women, hyperprolactinemia is often due to a prolactin (PRL)-secreting adenoma or PRL cell hyperplasia. RRL excess stimulates the mammary glands and causes proliferation of the alveolar epithelium. Bromocriptine, a dopamine agonist, inhibits PRL secretion and is given to women to treat nonpuerperal galactorrhea. Old female rats have been reported to have PRL cell hyperplasia or adenoma leading to PRL hypersecretion and breast stimulation. Herein, we describe the effect of bromocriptine and consequently the reduction in serum PRL levels on the ultrastructure of rat mammary glands.

Female Long-Evans rats, 23 months of age, were divided into control and bromocriptine-treated groups. The control animals were injected subcutaneously once daily with a 10% ethanol vehicle and were later divided into a normoprolactinemic control group with serum PRL levels under 30 ng/ml and a hyperprolactinemic control group with serum PRL levels above 30 ng/ml.
Effect of piperacillin on morphology and viability of gram-negative bacteria
Authors: Liss R. H.
Published: June 2020

Piperacillip (PIP) is b-[D(-)-α-(4-ethy1-2,3-dioxo-l-piperzinylcar-bonylamino)-α-phenylacetamido]-penicillanate. The broad spectrum semisynthetic β-lactam antibiotic is believed to effect bactericidal activity through its affinity for penicillin-binding proteins (PBPs), enzymes on the bacterial cytoplasmic membrane that control elongation and septation during cell growth and division. The purpose of this study was to correlate penetration and binding of 14C-PIP in bacterial cells with drug-induced lethal changes assessed by microscopic, microbiologic and biochemical methods.

The bacteria used were clinical isolates of Escherichia coli and Pseudomonas aeruginosa (Figure 1). Sensitivity to the drug was determined by serial tube dilution in Trypticase Soy Broth (BBL) at an inoculum of 104 organisms/ml; the minimum inhibitory concentration of piperacillin for both bacteria was 1 μg/ml. To assess drug binding to PBPs, the bacteria were incubated with 14C-PIP (5 μg/0.09 μCi/ml); controls, in drug-free medium.
Morphological and biochemical analyses of changes in rat hepatocytes related to wine and ethanol consumption
Authors: Geyer S.M. , Mendenhall C.L. , Hung J.T. , Cardell E.L. , Drake R.L. , Cardell R.R.
Published: June 2020

Thirty-three mature male Holtzman rats were randomly placed in 3 treatment groups: Controls (C); Ethanolics (E); and Wine drinkers (W). The animals were fed synthetic diets (Lieber type) with ethanol or wine substituted isocalorically for carbohydrates in the diet of E and W groups, respectively. W received a volume of wine which provided the same gram quantity of alcohol consumed by E. The animals were sacrificed by decapitation after 6 weeks and the livers processed for quantitative triglycerides (T3), proteins, malic enzyme activity (MEA), light microscopy (LM) and electron microscopy (EM). Morphometric analysis of randomly selected LM and EM micrographs was performed to determine organellar changes in centrilobular (CV) and periportal (PV) regions of the liver. This analysis (Table 1) showed that hepatocytes from E were larger than those in C and W groups. Smooth endoplasmic reticulum decreased in E and increased in W compared to C values.
Anionic molecular organization in isolated sarcolemma of human heart muscle
Authors: Lee Y.S. , Chang C.H.
Published: June 2020

Numerous studies using ultrastructural cytochemistry techniques have been published which bring out and characterize the surface membrane of many cell types. However, few of these studies are concerned with the sarcolemma of heart muscle cells. In particular, no detailed study has been reported relating to cytochemical characterization of isolated sarcolemma from human heart muscle. Thus, the present report was designed to observe and characterize the sarcolemmal ultrastructure of human ventricular myocardium with particular emphasis on anionic molecular organization in the membrane surface by means of electron microscopic and cytochemical studies.

The present study was carried out on human heart specimens. The infundibular muscles of right ventricle were obtained during open heart surgery for total correction of 10 patients with congenital heart disease (tetralogy of Fallot). The procedures used for the isolation of cardiac sarcolemma were principally based on the method as described by McNamara et al.
Quantitation of the intramembrane particle distribution in C3H/10T½ cells treated with TPA and retinyl acetate.
Authors: Fassel T. , Hui S.W.
Published: June 2020

The mouse embryo fibroblast C3H/10T½ cells are used as a model system for the study of ultrastructural changes caused by tumor promoter and “anti-promoter” treatments. Noninitiated fibroblasts treated with tumor promoter undergo phenotypic transformation. On the other hand, the retinoid, retinyl acetate (RA), is effective in suppression of the malignant phenotype in the 10T½ cells (1). We report on the rapid freezing and freeze fracture electron microscopy study of the plasma membrane ultrastructures of noninitiated C3H/10T½ fibroblasts after treatments of retinyl acetate or a tumor promoter, 12-0-tetradecanoyl-phorbol-13-acetate (TPA).

Rapid freezing of cells enables structure to be preserved without the use of cryoprotectants and chemical fixatives, which may alter membrane structural organization. For rapid freezing, 10T½ cells were grown as monolayers on glass specimen supports. The glass-copper specimen holder sandwiches were rapidly frozen by automatic plunging into liquid propane. Freeze fracture was carried out in a Polaron-Ultek ion pump apparatus with Cressington electron guns.
Periodic acid-thiocarbohydrazide-silver methenamine(PATS) reaction: An improved silver methodology for light and electron microscopy
Authors: Giammara B. , Romaine T. , Ambrose W. , Hanker J.
Published: June 2020

Many variations of the periodic acid-Schiff(PAS) reaction have been utilized for electron microscopy based on the Gomori periodic acid-silver methenamine reaction (1) or the periodic acid-thiocarbohydrazide-osmium tetroxide(PATCO) reaction (2,3). These reactions are widely employed and have been very useful for the demonstration of one or more biomacromolecules or structures such as glycogen, basement membranes, reticular fibers or lipopolysaccharide. However, these reactions have various drawbacks such as complexity of methodology, ability to stain only a limited number of these components, or lack of adaptability for both light and electron microscopy. Our newly devised PATS reaction is relatively easy to perform. A full description of the details must await the outcome of a pending patent application. It consists essentially of a stepwise treatment of the sample with periodic acid, thiocarbohydrazide(TCH) and silver methenamine.
Bulk standards for low-temperature biological x-ray microanalysis
Authors: Echlin P. , McKoon M. , Taylor E.S. , Thomas C.E. , Maloney K.L. , Hayes T.L.
Published: June 2020

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.
Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves
Authors: Edith Taylor S. , Echlin Patrick , McKoon May , Hayes Thomas L.
Published: June 2020

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.

Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.
Application of frozen hydrated x-ray microanalysis to bulk frozen embryological tissue
Authors: Klein S. B.
Published: June 2020

The examination of bulk frozen fully hydrated tissue by secondary electron and characteristic x-ray emission presents opportunities particularly suited to the study of rapidly differentiating embryological tissue. Because of the extended magnification range of the scanning electron microscope (SEM), embryonic development can be followed from the macroscopic egg to the microscopic adult cells, maintaining familiar visual clues. Advantages such as ease of handling, preservation of morphological relationships, increased heat dissipation and reduced contamination have been discussed previously in the literature and apply to frozen hydrated tissue in general. X-ray microanalysis of fully frozen hydrated embryos may be viewed as an extention of classical dissection techniques which allows selectivity without separation. Phenomena occurring within the unicellular egg such as fertilization, polarization and yolk granule composition can be examined by x-ray microanalysis without prior physical or chemical manipulation. Chemical gradients can be detected in the unperturbed, frozen hydrated matrix.
Fine structure of the retina of the giant scallop,Placopecten magellanicus
Authors: Powell C.V.L.
Published: June 2020

The overall fine structure of the eye in Placopecten is similar to that of other scallops. The optic tentacle consists of an outer columnar epithelium which is modified into a pigmented iris and a cornea (Fig. 1). This capsule encloses the cellular lens, retina, reflecting argentea and the pigmented tapetum. The retina is divided into two parts (Fig. 2). The distal retina functions in the detection of movement and the proximal retina monitors environmental light intensity. The purpose of the present study is to describe the ultrastructure of the retina as a preliminary observation on eye development. This is also the first known presentation of scanning electron microscope studies of the eye of the scallop.
Giant mitochondria in shoot meristems of cacti
Authors: Rivera E. R.
Published: June 2020

Many unicellular organisms have only a few long mitochondria that weave around through the cytoplasm (1). Addition of antimycin A to Euglena or submission of pumpkin root cells to anaerobic conditions causes fusion of all mitochondria into one long organelle (2,4). All of these examples of large mitochondria have some common features. Usually the long mitochondrion has similar structure throughout its length or the mitochondria that fuse into one have similar morphology. A different configuration of mitochondrial ultrastructure is found in the phloem of the parasitic plant Alectra vogelii Berth. These mitochondria are much larger and differ in appearance from those in cells surrounding the phloem (3).
Electron microscopy investigation of sputtered and glow-discharge amorphous silicon-tin alloys
Authors: Jones K. M. , Williamson D. L. , Yacobi B. G.
Published: June 2020

The alloying of amorphous silicon with tin for systematic modification of the optical band gap for multijunction thin film solar cell applications has recently attracted interest. This is a comparative study of the microstructural properties of both the RF sputtered and glow discharge a-Si:Sn thin films. Sputtered films were deposited at 20 mTorr and 4 mTorr dynamic pressures of Ar-10 vol.% H2. Glow discharge films were deposited using SiH4, H2 and Sn(CH3)4 gas mixtures. Details of both the sputtering and glow discharge deposition conditions have been recently published elsewhere.

In this work, Sn precipitation was observed in all hydrogenated sputtered alloys. Figure 1 shows the increase of the density of precipitates as a function of Sn concentration. These micrographs also reveal a non-coalesced (cauliflower) microstructure in the matrix. Figure 2 shows edge on view SEM micrographs of one of the sputtered films, which shows Sn precipitates originating at the substrate and in the bulk of the growing film. In a device structure, this would lead to electrical shorting and prevent the application of this material to solar cells.
Defect Structure Analysis in Semiconductors by HREM and New Compatible Techniques
Authors: Spence J.C.H.
Published: June 2020

The determination of atomic co-ordinates from HREM images has greatly improved our understanding of semiconductor defects, but chemical and electronic structure information are also needed. Thus suitable HREM compatible techniques must be developed and this article reviews some of these.

The intimate relationship between resolution and noise has been exploited for many years in biological HREM. Since the centre of a very broad gaussion peak can be found with an accuracy which depends mainly on noise, heavy atom positions in inorganic crystals can be determined from HREM images with an accuracy of ±0.1Å (well beyond the information and point resolution limits of an HREM image) by the addition of similar unit cell images. This method makes extensive use of a-priori information (that there is only one atomic column rather than an unresolved pair, other atom co-ordinates, symmetry) and fails for isolated defects, but may be useful for semiconductor interfaces and surfaces.
Detection of subsurface cracks and delaminations in polymeric materials by electron thermoelastic acoustic microscopy
Authors: Begnoche Bruce C. , Holstein William L.
Published: June 2020

Electron Thermoelastic Acoustic Microscopy (ETEAM), also termed Electron Acoustic Microscopy and Thermal Wave Microscopy, detects subsurface cracks, delaminations, and voids at depths up to at least 100 µm, as first reported by Cargill, The technique has previously been applied only to beam-insensitive materials, since high beam currents of about 1 µamp (1000 times greater than for routine SEM) are required to obtain adequate signal intensity. We present here a procedure for extending the technique to beam-sensitive polymeric materials.

In the ETEAM technique, a periodic electron beam (frequency V = 10 kHz-10 MHz) generates an acoustic wave, leading to a periodic force on a transducer attached to the specimen. The ETEAM image is derived from the transducer voltage output as the electron beam is scanned over the sample in an SEM. The inability of an acoustic wave to travel through a delamination results in it being transmitted around the delamination as a transverse shear wave (Fig. 1).
Mechanical microthinning: An alternative to chemical or ion-beam thinning for TEM specimen preparation
Authors: Plummer H.K. , Shinozaki S.S.
Published: June 2020

Recent publications(1-3) have indicated a number of cautions to be observed when interpreting electron transparent foils prepared by ion beam thinning. Some of the cited problems which could be encountered are: atom rearrangement creating new concentration gradients, final foil thickness variations due to original surface irregularities, specimen inhomogenieties or selective rates of etching by the ion beam, and blind side redeposition of matter when single gun ion beam thinning is employed to thin from the reverse side to preserve surface coated layers. Publications 2 and 3 both indicate that mechanical ‘prethinning’ the specimen discs to ≤20/μm prior to ion thinning in a device called a Dimpler(VCR Group, San Francisco, Cal.) would eliminate or highly retard many of the stated problems.
Electron microscopy of selected manganese oxide concretions
Authors: Chen Cy-Chain
Published: June 2020

Four manganese oxide samples representing different oxidation-reduction environments were examined by transmission electron microscopy (TEM) to observe the morphology and by electron diffraction (ED) to identify the mineral species. Samples selected were:

Manganese oxide concretion in Nada subsoil.

Manganese oxide concretion in Crockett subsoil.

Concretion formed in topsoil at a trickle irrigation water outlet.

Weathering product of siderite (FeCO3) as a black coating on the exterior surface of the rock.

Fine clay fractions (<0.2 μm) were obtained by ultrasonication followed by repreated washing and centrifugation. Dilute suspensions were deposited on Formvar coated grids. All observations were made on a Zeiss 10C TEM at 60kV. Magnesium oxide and synthetic hematite (α-Fe2O3) were used as ED standards. Supplementary data were obtained by x-ray diffraction (XRD).
Crystal structure images of large gold clusters and growing crystals by HRTEM
Authors: Wallenberg L.R. , Bovin J.-O. , Schmid G.
Published: June 2020

Metallic clusters are interesting from various points of view, e.g. as a mean of spreading expensive catalysts on a support, or following heterogeneous and homogeneous catalytic events. It is also possible to study nucleation and growth mechanisms for crystals with the cluster as known starting point.

Gold-clusters containing 55 atoms were manufactured by reducing (C6H5)3PAuCl with B2H6 in benzene. The chemical composition was found to be Au9.2[P(C6H5)3]2Cl. Molecular-weight determination by means of an ultracentrifuge gave the formula Au55[P(C6H5)3]Cl6 A model was proposed from Mössbauer spectra by Schmid et al. with cubic close-packing of the 55 gold atoms in a cubeoctahedron as shown in Fig 1. The cluster is almost completely isolated from the surroundings by the twelve triphenylphosphane groups situated in each corner, and the chlorine atoms on the centre of the 3x3 square surfaces. This gives four groups of gold atoms, depending on the different types of surrounding.
SEM at Low Beam Voltage
Authors: Pawley James
Published: June 2020

Operation of the SEM with V0 = l-3kV (LVSEM) was early recognized to reduce charging artefacts and increase topographic contrast. This early promise was not pursued because several theoretical and practical considerations made it difficult to produce a small probe diameter (d0) at low voltage. Recently, the necessity of using low V0 to image uncoated semiconductors without damaging them has prompted a re-evaluation of LVSEM. This re-evaluation has taken the form of efforts to eliminate the practical constraints and to alleviate the theoretical ones. In the process, some heretofore neglected theoretical advantages of LVSEM have emerged. These problems and possibilities will now be discussed in more detail.
Experimental determination of the critical cavity radius in Fe-10% Cr for ion irradiation
Authors: Horton L. L.
Published: June 2020

A major problem associated with the design of fusion reactors is high energy neutron damage to structural materials. The combination of vacancies formed by atomic displacements with gases produced by transmutation reactions can cause the formation of cavities. An important parameter in the theory of cavity growth is the radius above which the cavity exhibits bias-driven growth. If the cavity radius is less than this “critical radius,” cavities lose as many vacancies due to thermal processes as are gained from the bias-induced influx of vacancies. When bias-driven growth occurs, large amounts of cavitational swelling can result, leading to severe dimensional instability. Cavities can attain the critical radius either by an abnormally high random influx of vacancies or by absorption of gas atoms. The addition of gas atoms to a cavity reduces the value for the critical radius. If the number of gas atoms exceeds a critical number of gas atoms, then the critical radius vanishes. There is then no barrier to bias-driven growth.