bluuebunny/crossref_metadata_2025 huggingface dataset:
Data-Centric Engineering in modern science from the perspective of a statistician, an engineer, and a software developer
Authors: Ley Christophe , Tibolt Mike , Fromme Dirk
Published: June 2020

Data-Centric Engineering is an emerging branch of science that certainly will take on a leading role in data-driven research. We live in the Big Data era with huge amounts of available data and unseen computing power, and therefore a crafty combination of Statistics (or, in more modern terms, Data Science), Computer Science and Engineering is required to filter out the most important information, master the ever more difficult challenges of a changing world and open new paths. In this paper, we will highlight some of these aspects from a combined perspective of a statistician, an engineer and a software developer. In particular, we will focus on sound data handling and analysis, computational science in Structural Engineering, data care, security and monitoring, and conclude with an outlook on future developments.
EXACT COMPLETION AND CONSTRUCTIVE THEORIES OF SETS
Authors: EMMENEGGER JACOPO , PALMGREN ERIK
Published: June 2020

In the present paper we use the theory of exact completions to study categorical properties of small setoids in Martin-Löf type theory and, more generally, of models of the Constructive Elementary Theory of the Category of Sets, in terms of properties of their subcategories of choice objects (i.e., objects satisfying the axiom of choice). Because of these intended applications, we deal with categories that lack equalisers and just have weak ones, but whose objects can be regarded as collections of global elements. In this context, we study the internal logic of the categories involved, and employ this analysis to give a sufficient condition for the local cartesian closure of an exact completion. Finally, we apply this result to show when an exact completion produces a model of CETCS.
Lexically specific vs. productive constructions in L2 Finnish
Authors: LESONEN SIRKKU , STEINKRAUSS RASMUS , SUNI MINNA , VERSPOOR MARJOLIJN
Published: June 2020

It is assumed from a usage-based perspective that learner language constructions emerge from natural language use in social interaction through exemplar learning. In L1, young learners have been shown to develop their constructions from lexically specific, formulaic expressions into more productive, abstract schemas. A similar developmental path has been shown for L2 development, with some exceptions. The aim of the current study is to explore to what extent the default assumption holds for L2 learning. The development of two constructions was traced in four adults learning L2 Finnish. Free-response data, collected weekly over a period of 9 months, were used to investigate the productivity of the constructions. The results show that, contrary to the traditional assumption, L2 learners do not start off with only lexically specific expressions, but that both lexically specific and more productive constructions are used from the beginning. Our results therefore suggest that, for educated adult L2 learners, the schema formation can happen rather quickly and even without the repetition of a specific lexical sequence.
GPS navigation apps and the price of anarchy
Authors: Wapner Leonard M.
Published: June 2020

Folded paper road maps are found next to sextants in the pile of obsolete navigation tools. GPS navigation apps like Waze and Google Maps, accurate to within a few metres, are available on all smartphones and most new cars. These apps provide drivers with real time traffic conditions and suggest minimum drive time routes, giving drivers the ability to avoid congestion and delays caused by heavy traffic, accidents, road construction and other hindrances.
Markov Chain Monte Carlo on finite state spaces
Authors: Siems Tobias
Published: June 2020

We elaborate the idea behind Markov chain Monte Carlo (MCMC) methods in a mathematically coherent, yet simple and understandable way. To this end, we prove a pivotal convergence theorem for finite Markov chains and a minimal version of the Perron-Frobenius theorem. Subsequently, we briefly discuss two fundamental MCMC methods, the Gibbs and Metropolis-Hastings sampler. Only very basic knowledge about matrices, convergence of real sequences and probability theory is required.
Human Rights are (Increasingly) Plural: Learning the Changing Taxonomy of Human Rights from Large-scale Text Reveals Information Effects
Authors: PARK BAEKKWAN , GREENE KEVIN , COLARESI MICHAEL
Published: June 2020

This manuscript helps to resolve the ongoing debate concerning the effect of information communication technology on human rights monitoring. We reconceptualize human rights as a taxonomy of nested rights that are judged in textual reports and argue that the increasing density of available information should manifest in deeper taxonomies of human rights. With a new automated system, using supervised learning algorithms, we are able to extract the implicit taxonomies of rights that were judged in texts by the US State Department, Amnesty International, and Human Rights Watch over time. Our analysis provides new, clear evidence of change in the structure of these taxonomies as well as in the attention to specific rights and the sharpness of distinctions between rights. Our findings bridge the natural language processing and human rights communities and allow a deeper understanding of how changes in technology have affected the recording of human rights over time.
HYPERSTABILITY OF GENERALISED LINEAR FUNCTIONAL EQUATIONS IN SEVERAL VARIABLES
Authors: PHOCHAI THEERAYOOT , SAEJUNG SATIT
Published: June 2020

Zhang [‘On hyperstability of generalised linear functional equations in several variables’, Bull. Aust. Math. Soc.92 (2015), 259–267] proved a hyperstability result for generalised linear functional equations in several variables by using Brzdęk’s fixed point theorem. We complete and extend Zhang’s result. We illustrate our results for general linear equations in two variables and Fréchet equations.
Cultural differences in the association between subjective age and health: evidence from the Israeli component of the Survey of Health, Ageing and Retirement in Europe (SHARE-Israel)
Authors: Bergman Yoav S. , Shrira Amit
Published: June 2020

Research has demonstrated that holding a young subjective age (i.e. feeling younger than one's chronological age) has been associated with various positive aspects of physical and psychological health. However, little is known about how such associations differ between cultural sub-groups within a given society. Accordingly, the current study focused on the Israeli component of the Survey of Health, Ageing and Retirement in Europe (SHARE-Israel) and aimed to explore the moderating role of culture on the association between subjective age and objective physical health, subjective physical health and psychological health. Data were collected from 1,793 respondents, who were classified into three groups: veteran Israeli Jews, immigrants from the former Soviet Union and Israeli Arab citizens. Age ranged from 50 to 105 (mean = 69.65, standard deviation = 9.49). All participants rated their subjective age and filled out scales examining six dimensions covering psychological health, as well as objective and subjective physical health. Across all examined dimensions, an older subjective age was associated with unfavourable health outcomes. For the majority of health dimensions, the subjective age–health links were most prominent among Israeli Arabs. Results are discussed from both a general societal standpoint (i.e. group differences in access to health services), as well as from the individual's specific role in his or her culture and society.
Oral fluency in a second language: A research agenda for the next ten years
Authors: Foster Pauline
Published: June 2020

This paper reviews how the construct of oral fluency in a second language (L2) has been defined and researched over the last twenty-five years. The emerging picture is somewhat kaleidoscopic, as domains of cognitive, social, individual and linguistic influences on L2 speech have been opened up for study. L2 fluency research presents a wealth of directions for future exploration, five of which have been laid out here as an achievable, though not comprehensive, agenda for the coming decade. Four of these studies focus on the relationship between variables such as perceived fluency, utterance fluency, idiomaticity, task familiarity, vocabulary size and learner self-reflection, while the fifth focusses on supporting fluency development in the L2 classroom. As an aid to prospective researchers, the five studies are laid out in practical detail, together with suggestions on how these might need to be altered to fit the local context in which the research is undertaken.
Autonomous Intelligent Planning Method for Welding Path of Complex Ship Components
Authors: Wang Tao , Xue Zhilong , Dong Xiaoqing , Xie Senlin
Published: June 2020

Aiming at planning the welding path of complex ship components, a welding path planning optimization model was constructed with the shortest welding path and using the target and the welding process and welding starting and ending points as constraints. Based on the model, an improved ant colony algorithm with dynamic adaptive parameters was proposed to complete the path planning work. Simulation results showed that, compared with other classical optimization algorithms, the proposed algorithm improved optimization speed while ensuring optimization effect and achieving better results in path planning of complex ship components.
FILLED PAUSES ARE SUSCEPTIBLE TO CROSS-LANGUAGE PHONETIC INFLUENCE
Authors: García-Amaya Lorenzo , Lang Sean
Published: June 2020

This article investigates the effects of long-term bilingualism on the production of filled pauses (FPs; e.g., uh, um, eh, em) in the speech of Afrikaans-Spanish bilinguals from Patagonia, Argentina. The instrumental analysis draws from a corpus of sociolinguistic interviews obtained from three speaker groups: L1-Afrikaans/L2-Spanish bilinguals; L1-Spanish-comparison speakers, also from Patagonia; and L1-Afrikaans-comparison speakers from South Africa. In the data analysis, we examined relative FP usage (categorical outcomes), as well as phonetic measures of vowel quality and segmental duration (continuous outcomes). The results allude to multiple patterns of cross-language influence (e.g., L1-to-L2 influence, L2-to-L1 influence, bidirectional influence), which depend on the phonetic measure explored. Overall, the findings suggest that the patterns of cross-language phonetic influence observed in the L2 learning of traditionally understood lexical items likewise hold in the L2 learning of hesitation markers such as FPs.
Initial Healing Response of the Ocular Lens Following Eye Injury
Authors: Unakar N.J. , Bullock C. , Reddan J.R. , Weinsieder A.
Published: June 2020

Lens epithelium is diposed on the anterior lens surface as a monolayer sandwiched between an outer capsule and the inner lens fiber cells. The epithelical cells of the anterior pole, held in an extended G1 phase of the cell cycle, rarely divide. However, these cells can be coerced to re-enter the cell cycle by a variety of external stimuli: injury, explanation, and chemical injury.
DNA Isolated from Hela Cell is Highly Ordered
Authors: Sanyal A. B. , O'Brien R. L.
Published: June 2020

It is a generally held assumption that the intranuclear order of eukaryotic DNA is essential to its ordered function and replication. The means by which this order is imposed is not altogether understood, but it has been postulated that it involves association with chromatin proteins and various sites of chromatin attachment to the nuclear membrane. The attachment of chromatin to the nuclear membrane has been observed in a number of preparations and seems ordinarily to be in close proximity to the nuclear annuli. The nature of the attachment sites and the forces involved in holding the chromatin to them is not known. In studies attempting to characterize replication regions of nuclear DNA, we have made the observation that this DNA exists in a highly ordered fashion and that the order appears to be imposed upon it by its association with some structure. This communication reports for the first time the observation of a high degree of order in eukaryotic DNA.
Fractographic Studies of Biological Specimens by Scanning Electron Microscopy
Authors: Humphreys Walter J.
Published: June 2020

Some organisms remain viable even after the cytoplasm of their cells is dried out. Naturally dried cysts of the brine shrimp, Artemia, e. g. hatch normally even after further desiccation by weeks of exposure to a vacuum of 10- torr. If such organisms are fractured at the temperature of liquid nitrogen (in order to minimize mechanical deformation) direct viewing of the exposed intracellular cytoplasmic constituents by means of the SEM probably gives a faithful, unaltered picture of this cryptobiotic cytoplasm as it exists in nature. Ion etching the fractured surface can exaggerate physical differences in structural components within intracellular constituents. Certain yolk particles in Artemia cysts e. g. consists of an aggregation of very electron dense particles centered inside a less electron dense body (Fig. 1). These particles are identifiable in fractured yolk bodies (Arrow Fig. 2) but more dramatically so after ion etching (Arrows Fig. 3).
High Resolution EM Study of Wüstite
Authors: Iijima Sumio
Published: June 2020

Wüstite (Fe1-x0) has recieved considerable attention because of a wide range of variation in x. The deviation from stoichiometry is known to be due to vacancies on cation sites. Koch and Cohen, having studied this material in detail using an X-ray diffraction method, concluded that the defects present in Fe1-x0 are clusters of 13 octahedral vacancies and 4 tetrahedral ions. These clusters are arranged periodically but the repeat distance in the [100] direction is not an integral number of structures of the basic NaCl-type. The observed spacing of superstructure peaks may correspond to the average repeat distance.
Progress Towards the Sequencing of DNA by Electron Microscopy
Authors: Langmore J. P. , Crewe A. V.
Published: June 2020

The localization of chemical sites in biological molecules by electron microscopy can be achieved if a) heavy atom labels can be incorporated at specific sites on the molecules, b) these atoms remain bound at their original sites when placed on a substrate and irradiated with an electron beam and c) the heavy atom labels and their supporting biological molecules can be visualized in the microscope. Single atom mercury labels are ideal for this task since they are of high Z and their use is common in protein chemistry. We are attempting to use mercury containing base labels to sequence DNA.
A 65 keV Proton Scanning Microscope
Authors: Escovitz William H. , Fox Timothy R. , Levi-Setti Riccardo
Published: June 2020

We have constructed a prototype scanning gun microscope which uses 65 keV hydrogen ions as a probe. A field ionization ion source, consisting of a tungsten tip (∼ 1000Å radius) cooled to 78° K in an H2 atmosphere, yields H+ and H2+ ions, which are then accelerated and focused by a two-electrode accelerating lens. The spot is deflected electrostatically to scan the specimen and the transmitted particles are detected by a continuous-dynode electron multiplier.
A Quadrupole Octupole Corrector for a 100 keV STEM
Authors: Beck V. , Crewe A. V.
Published: June 2020

A corrector for third order axial aberrations is being built for use with a 100 keV STEM. According to Scherzer's theorem, third order aberrations can be corrected by using focusing fields which have sources on the optic axis or which lack cylindrical symmetry. This corrector consists of four quadruples and three octupoles and is shown in Fig. 1. The principal rays for the system are shown in the figure. The quadrupoles are arranged to have no net first order effects other than to invert the beam. Since there are three independent third order axial aberrations, three octupoles are required to achieve correction. One octupole is located in the center of the system where the beam is symmetrical, and the other two are located at the line foci.
A Liquid Nitrogen Cooled Stage for STEM
Authors: Germinario Louis T.
Published: June 2020

A liquid nitrogen stage has been developed for the JEOL JEM-100B electron microscope equipped with a scanning attachment. The design is a modification of the standard JEM-100B SEM specimen holder with specimen cooling to any temperatures In the range ~ 55°K to room temperature. Since the specimen plane is maintained at the ‘high resolution’ focal position of the objective lens and ‘bumping’ and thermal drift la minimized by supercooling the liquid nitrogen, the high resolution capability of the microscope is maintained (Fig.4).
Transmission Electron Microscopy Studies of Grain Boundary Precipitation in Spinodally Decomposed Cu-Ni-Fe Alloys
Authors: Gronsky R.
Published: June 2020

In many alloy systems the grain boundaries play an important role in controlling properties but little is known about the mechanism of grain boundary precipitation reactions. Transmission electron microscopy and diffraction are necessary to distinguish reactions such as discontinuous precipitation and preferential coarsening. The present paper describes current progress on the Cu-Ni-Fe system which is known to be embrittled at the grain boundaries. Two alloys are considered, having their compositions on a binary section through the Cu-Ni-Fe ternary with terminal values at the Cu corner and the point Ni0.7Fe0.3. Alloy A(51.5 at % Cu-33.5 at % Ni-15 at % Fe) lies very near to the center of the miscibility gap. Phase identification in the electron micrographs is facilitated by comparison with alloy B (69.3 at % Cu-19.4 at X Ni-11.1 at % Fe) of asymmetrical composition. The microstructure shown in Fig. 1 results from aging alloy B within the spinodal (650°C) for 10 hrs.
Expression of Viral Membrane Proteins from Cloned cDNA by Microinjection into Eucaryotic Cell Nuclei
Authors: Garoff H. , Kondor-Koch Cl.
Published: June 2020

The relationship between a protein's structure and its function can be explored in detail by in vitro mutagenesis of a cloned DNA molecule encoding the protein and expression of its mutagenized form in a eucaryotic cell. This will be a useful approach to study the assembly of spanning viral or plasma membrane proteins into the endoplasmic reticulum membrane and their transport to the cell surface. Questions that could be answered using this technique include:

Is the signal sequence alone sufficient for translocation of a polypeptide chain across the endoplasmic reticulum membrane? Is a cytoplasmic protein (e.g. a viral capsid protein) translocated when linked to a signal sequence?
Fibronexus-Like Adhesion Sites are Present at the Invasive Zones of Human Epidermoid Carcinomas
Authors: Singer Irwin I.
Published: June 2020

Our previous results indicate that two types of fibronectin-cytoskeletal associations may be formed at the fibroblast surface: dorsal matrixbinding fibronexuses generated in high serum (5% FBS) cultures, and ventral substrate-adhering units formed in low serum (0.3% FBS) cultures. The substrate-adhering fibronexus consists of at least vinculin (VN) and actin in its cytoplasmic leg, and fibronectin (FN) as one of its major extracellular components. This substrate-adhesion complex is localized in focal contacts, the sites of closest substratum approach visualized with interference reflection microscopy, which appear to be the major points of cell-tosubstrate adhesion. In fibroblasts, the latter substrate-binding complex is characteristic of cultures that are arrested at the G1phase of the cell cycle due to the low serum concentration in their medium. These arrested fibroblasts are very well spread, flattened, and immobile.
Views of Ribosome Tetramers and the Localization of Ribosomal Subunits
Authors: Lamvik M. K. , Zeltler E.
Published: June 2020

Carey suggested that chick-embryo ribosome tetramers attach to the substrate film preferentially in one of the two possible orientations, making them particularly appropriate for use in the three-dimensional reconstruction of ribosome structure. We have stored and analyzed tetramer images digitally as described earlier. To test for a fixed orientation, many tetramer Images were compared to a reference image that contained an arbitrarily labelled "right-handed" view. Images that correlated well with the reference were averaged, giving a right-handed result (fig. 1). To search for a left-handed view, the reference image was "turned over” in the computer to artificially create a left-handed image. Repeating the procedure with the new reference gave a result that was mostly symmetric (fig. 2), not left-handed.
Serum-Induced Hypersecretion in Isolated and Native Rabbit Endocervical Mucous Cells
Authors: Nicosia S.V. , Johnson J.H. , Streibel E.J. , Mogul L.
Published: June 2020

Mucous glycoproteins are the Theologically active components of cervical mucus. These glycoproteins are packaged within endocervical mucous cells from which they are released through poorly understood mechanisms. Recently, we have observed that serum contains a macromolecule able to induce in vitro exocytotic release of mucous granules. The purpose of this study was to compare the effect of serum on the ultrastructure and granule content of isolated and native endocervical mucous cells.
The Effect of Oxidized Cholesterol on the Aorta of Rabbits- Scanning Electron Microscopic Observations
Authors: Pena S. K. , Taylor C. B. , Hill J. , Safarik J.
Published: June 2020

Introduction: Oxidized cholesterol derivatives have been demonstrated in various cell cultures to be very potent inhibitors of 3-hvdroxy-3- methylglutaryl Coenzyme A reductase which is a principle regulator of cholesterol biosynthesis in the cell. The cholesterol content in the cells exposed to oxidized cholesterol was found to be markedly decreased. In aortic smooth muscle cells, the potency of this effect was closely related to the cytotoxicity of each derivative. Furthermore, due to the similarity of their molecular structure to that of cholesterol, these oxidized cholesterol derivatives might insert themselves into the cell membrane, alter membrane structure and function and eventually cause cell death. Arterial injury has been shown to be the initial event of atherosclerosis.
Analysis of Defects Exhibiting Fringe Contrast in Gallium Arsenide Implanted with Beryllium
Authors: Rai A. K. , Benson R. B. , Dietrich H. B. , Bentley J.
Published: June 2020

The characteristics of defects exhibiting fringe contrast in GaAs annealed after implantation with Be have been examined using weak-beam dark-field transmission electron microscopy. Semi-insulating, chromium-doped, [001] GaAs wafers were implanted with 35 keV Be ions to a fluence of 1 x 1015 ions/cm2.
Defects in Heteroepitaxial Silicon on Sapphire
Authors: Abrahams M. S.
Published: June 2020

The silicon on sapphire heteroepitaxial system is used extensively in the manufacture of high-performance and/or radiation-hard integrated circuits. It is considered to be a major contender as a basis for future extremely complicated circuits (VLSI). Since the exact structure of the heteroepitaxial interface is not currently known with good accuracy and since the properties of the devices can depend on the properties of the interface more detailed examination was attempted.
The Effect of Surface Layers on Thin Foil Standards on the Accuracy of Quantitative E.D.S. Analysis
Authors: Brown J.M. , Fraser H.L.
Published: June 2020

Quantitative X-ray microanalysis of thin foils may be achieved either by calculation or by making use of standards. This paper, although advocating the use of pure elemental standards for accurate quantification, points out some of the problems involved in the choice of good standards. Specifically, the presence of surface films on as-prepared thin foil standards must be removed or accounted for during data analysis.
Precipitate Chemistry in an 18Cr-2Mo-Ti Stabilized Ferritic Stainless Steel
Authors: Ritter A. M. , Hall E. L. , Devine T. M.
Published: June 2020

Sensitization in an 18Cr-2Mo-Ti stabilized ferritic stainless steel is associated with precipitation of grain boundary phases, which form during quenching of solution-annealed material. Changes in Ti and Cr concentrations in these phases occur during aging, causing Cr depletion near boundaries, and subsequent sensitization. To better define the chemistry of the precipitates, a combination of EDS and EELS on thin foils and extraction replicas was used.
Microstructural Analysis of SiO2-Al2O3 Glasses
Authors: Jantzen C. M. , Howitt D. G.
Published: June 2020

The mullite-SiO2 liquidus has been extensively studied, and it has been shown that the flattening of the liquidus is related to the existence of a metastable region of liquid immiscibility at sub-liquidus temperatures which is detectable by transmission electron microscopy (TEM) (Fig. 1).
Radiation-Induced Precipitation at Thin Foil Surfaces in Ni-Be Alloys
Authors: Mukai T. , Mitchell T. E.
Published: June 2020

Radiation-induced homogeneous precipitation in Ni-Be alloys was recently observed by high voltage electron microscopy. A coupling of interstitial flux with solute Be atoms is responsible for the precipitation. The present investigation further shows that precipitation is also induced at thin foil surfaces by electron irradiation under a high vacuum.
Bilateral Structure of Developing Cotton Fibers
Authors: Boylston E. K. , Hebert J. J.
Published: June 2020

It has long been established that cotton fibers possess an asymmetric cross-sectjon with respect to accessibility and packing density. Kassenbeck reported in 1969 differences in packing density of the lamella structure as revealed by layer expansion during polymerization of methacrylate. He summarized that the characteristic bean shaped cross-section of cotton fibers could be subdivided into the more accessible part--the concave segment, and the less accessible or convex segment along with the highly curved ends of the fiber section. These differences in the cotton structure appear during swelling with methacrylate, and by enzymatic degradation of fiber cross-section as well as differential uptake of electron dense staining materials. In all cases, this phenomenon has been attributed to the collapse of the fiber upon drying, resulting in a differential stress distribution thereby creating a variation in density.
Differential Averaging of Single Molecule Images using Multivariate Statistical Classification
Authors: Frank Joachim
Published: June 2020

It has been shown that averaging of single molecules or molecular assemblies visualized in the electron microscope is capable of giving reproducible results at the resolution level allowed by negative staining. The resolution achieved for a given specimen is, however, dependent upon the range of variation that the molecule exhibits in the electron microscope (fig. 1). A new technique, differential or local averaging, promises to overcome this limitation in fully utilizing the information contained in the experimental images.
High Resolution, Low Accelerating Voltage Scanning Electron Microscopy of Uncoated, Non-Conducting Surfaces
Authors: Coates Vincent J.
Published: June 2020

Recent improvements in the design of the Coates and Welter field emission electron gun have resulted in very small probe sizes (less than 50A) with low voltage (0.5 to 2 KV) electron beams operated at probe currents in excess of 1 nanoampere. Such weak electrons do not penetrate deeply into the sample. This results in images which often show more topographical detail of surface features than can be obtained using conventional high voltage scanning electron microscopy. At low voltages, the number of secondary electrons produced for each primary electron in the beam is often greater than one.
Electron Microscopy and Chemistry
Authors: Turkevich John
Published: June 2020

During the last twenty-five years there has been a marked increase in the number of chemical problems that have been attacked by the various methods of electron microscopy. In addition there has been a development of sophistication in the diverse techniques of sample preparation. The electron microscope has been used in fundamental studies to characterize the texture of matter—that state of organization of matter more complex than that of larger molecules and smaller than the details that can be revealed by optical microscopy. This has brought about an understanding of the size and shape of colloidal particles, the pore distribution of membranes, the topology of surfaces and the density and character of dislocations in solids. Particle size distribution curves obtained with the electron microscope have found widespread practical application in the pigment manufacture, rubber reinforcement, fiber studies, catalyst characterization, and polymer research.
Evaporated Titanium Films on Rocksalt
Authors: Wawner Frank E. , Lawless Kenneth R.
Published: June 2020

Thin single crystal films of high purity titanium were needed in our laboratory for investigations of the early stages of the oxidation of titanium. Experiments were carried out to determine the feasibility of preparing single crystal titanium films of different orientations by evaporation onto the (100), (110) and (111) surfaces of rocksalt. The structures of these films were investigated by transmission electron microscopy and electron diffraction.
Scanning Electron Microscopic Study of the Cell Surface
Authors: Kuwabara Toichiro
Published: June 2020

Although scanning electron microscopy has a great potential in biological application, there are certain limitations in visualization of the biological structure. Satisfactory techniques to demonstrate natural surfaces of the tissue and the cell have been reported by several investigators. However, it is commonly found that the surface cell membrane is covered with a minute amount of mucin, secretory substance or tissue fluid as physiological, pathological or artefactual condition. These substances give a false surface appearance, especially when the tissue is fixed with strong fixatives. It seems important to remove these coating substances from the surface of the cell for demonstration of the true structure.
Observations on Ordering in Ni2V
Authors: Tanner Lee E.
Published: June 2020

At temperatures greater than Tc=920°C Ni2V exists as a disordered f.c.c. solid solution; below Tc its stable form is an orthorhombic superlattice. This study is concerned with the transformation to long-range order of this alloy as a function of heat treatment. Current results indicate that the transition invariably proceeds by means of nucleation and growth, though mode and morphology vary markedly with reaction temperature.
Growth and Structure of Tin Films Evaporated Onto Rock Salt
Authors: Shimaoka G. , Komoriya G.
Published: June 2020

Recent electron optical studies of evaporated tin films have demonstrated the importance of deposition rate and vacuum pressure as well as substrate temperature in determining film structure and growth. The purpose of this study is to investigate growth and structure of tin thin films, about 100Å thick, evaporated onto rock salt substrate under carefully controlled conditions, in particular, effects of deposition rate and an electric field applied to the substrate during the evaporation.
Microbulldozing and Microchiseling
Authors: Ramsey J.N. , Cameron D.P. , Schneider F.W.
Published: June 2020

As computer components become smaller the analytical methods used to examine them and the material handling techniques must become more sensitive, and more sophisticated. We have used microbulldozing and microchiseling in conjunction with scanning electron microscopy, replica electron microscopy, and microprobe analysis for studying actual and potential problems with developmental and pilot line devices. Foreign matter, corrosion, etc, in specific locations are mechanically loosened from their substrates and removed by “extraction replication,” and examined in the appropriate instrument. The mechanical loosening is done in a controlled manner by using a microhardness tester—we use the attachment designed for our Reichert metallograph. The working tool is a pyramid shaped diamond (a Knoop indenter) which can be pushed into the specimen with a controlled pressure and in a specific location.
Electron Diffraction Studies of Pure SiC Polytypes
Authors: Gibbon Donald L.
Published: June 2020

Single crystal electron diffraction patterns have been obtained for three pure SiC polytypes, 4H, 6H, and 15R. The purity of the samples was determined by optical and x-ray techniques (Hannum and Shaffer, 1969). Diffracted intensity distributions for single crystals of these polytypes have been computed using the Busing-Levy ORFLS program. The samples were prepared by crushing and dispersing the powders on carbon substrates, shadowed with Pt. In scanning these dispersions, crystals were sought which were oriented with an a axis vertical.
Comparison of Deformation Microtwins in Planar and Cylindrical Explosive Loaded Type 304 Stainless Steel
Authors: Foltz J. V. , Murr L. E.
Published: June 2020

It is well known that the passage of a planar shock wave through a metallic solid causes in general a considerable change in the microstructure of the crystalline matrix and a corresponding change in the residual mechanical properties of the material. For example, a number of investigators have confirmed the presence of deformation faults with a pronounced twin character in the face centered cubic metals deformed under planar shock wave loading conditions. For the purpose of studies of shock induced defects, experiments are usually designed so that geometrical constraints prevent lateral flow of the specimen during shock loading. Such a deformation is termed one-dimensional strain. It is of interest to investigate the nature of the defects generated in a metal under impulsive loading for a geometry other than uniaxial strain.
Morphological Aspects of a New “C”-type Viral Agent of Reptilian Origin
Authors: Zeigel R. F. , Clark H. F.
Published: June 2020

Because of current interest in the association of viruses with tumors and the stimulus toward utilizing technology derived from biological studies on lower vertebrate cells, it was deemed pertinent to screen available specimens by E. M. A specimen of a species of asian snake, Vipera Russelli, which had been maintained at the Buffalo Zoo, was found to harbour a 180 gm myxofibroma tumor at autopsy. Intravascular clusters of cells were observed in other visceral organs which were thought to be of neoplastic origin. Tissues from "normal" Russell's vipers have been acquired for comparative study and will be reported elsewhere. Primary cultures were made from liver, spleen, kidney and tumor of the tumorbearing snake. The spleen cultures were the only ones that survived.
Nodes on Insect Sensory Dendrites
Authors: Slifer Eleanor H. , Sekhon Sant S.
Published: June 2020

In 1968 Ghiradella, Case and Cronshaw described periodic swellings or nodes on the dendrites of the aesthetasc hairs of the antennules of several species of decapod Crustacea. They noted that the microtubules in the dendrites traversed the swellings. Similar expanded regions have now been found on the branches of the dendrites in longitudinal sections of the olfactory pegs of Contarinia sorghicola (Fig. 1). In cross sections the number of microtubules present within a dendrite branch is not closely correlated with its diameter.
The Fine Structure of Cockroach Campaniform Sensilla
Authors: Moran D. T. , Chapman K. M. , Ellis R. A.
Published: June 2020

Insects are equipped with mechanoreceptors, sense organs that transduce a mechanical stimulus into a nerve impulse. Among the mechanoreceptors associated with the cuticle of the cockroach are the proprioceptive campaniform sensilla. To provide correlation of structure with the function of these mechanoreceptors, the proprioceptive campaniform sensilla on the tibia of the cockroach, Blaberus cranifer, have been investigated with the light and electron microscopes.
Ultrastructure of the Basement Membrane of the Uterine Cervix During the Estrous Cycle on the Rat
Authors: Baccarini Iracema M.
Published: June 2020

The EM studies of the basememt membrane of the uterine cervix was made to determine the variations during the estrous cycle.

Material and Methods. Animals were sacrificed under ether anesthesia when the vaginal smears showed different stages of the estrous cycle. The uterine cervix was removed and it was put into cold 3% glutaraldehyde for 6 hours; during the fixation the uterine cervix was divided in half under the dissection microscope. The tissue was embedded in vestopal. Thick sections were stained with toluidine blue to select the horizontal part of the epithelium. Thin sections were stained,by uranyl acetate and lead citrate.

Results. Proestrous stage. The cytoplasmic membrane is thick, dark and tortuous. Numerous dense desmosomes having different sizes are seen symmetrically on the cytoplasmic membrane, and also, on the amorphous material. Large and abundant digitations have irregular shapes. Dense and uniform amorphous material about 580 A wide is on the borderline of the connective tissue. Light space about 466 A show light and dilated areas.
Further Comparative Phase and Electron Microscopic Observations of the Hippocampal Mossy Fiber Layer Due to Treatment with Antimetabolites
Authors: Niklowitz Werner J.
Published: June 2020

In a previous publication we have shown a useful application of phase microscopy in cytological studies of nervous tissue. Using this method it has been possible to identify the axon terminals of the hippocampal mossy fiber layer with phase microscopy and to corroborate its identification with electron microscopy using the same material Further combined phase and electron microscopic investigations of this specific region of the hippocampus give additional insight into the possible chemical nature of the transmitters in the mossy fiber boutons in rabbits.
Ferritin Labeled Antibody Staining of Thin Sections
Authors: McLean J. D. , Singer S. J.
Published: June 2020

The successful application of ferritin labeled antibodies (F-A) to ultrathin sections of biological material has been hampered by two main difficulties. Firstly the normally used procedures for the preparation of material for thin sectioning often result in a loss of antigenicity. Secondly the polymers employed for embedding may non-specifically absorb the F-A. Our earlier use of cross-linked polyampholytes as embedding media partially overcame these problems. However the water-soluble monomers used for this method still extract many lipids from the material.
A 100 KV Transmission Scanning Microscope
Authors: Crewe A. V.
Published: June 2020

A 100 kv transmission scanning microscope is now being constructed which should have a point resolution of 2.5 to 3 Å. The design of this microscope is similar to the design of our existing 30 kv 5 Å microscope, but there are several significant changes which are based upon some difficulties and sources of inflexibility of that microscope.

A field emission electron gun of our usual design will be used as the source of electrons, the only difference being that the spacing between the anodes has been increased from 2 to 3 cm. The electron beam will then pass through a condenser lens which will produce a parallel beam of electrons. This parallel beam will then be focused onto the specimen by means of a short focal length lens (approximately 1 mm focal length). The reason for using a condenser lens to produce the parallel beam of electrons is that in the future a quadrupole-octupole correction system will be installed in this section of the microscope in order to attempt to correct the spherical aberrations of the objective lens and thereby improve its resolution.
Scanning Electron Microscopy and Thin Section Microanalysis of Plant Cells
Authors: Thurston E. Laurence , Russ John C.
Published: June 2020

Thin sections (2000 Å) of the filamentous blue-green alga, Fischerella ambigua, containing large (0.6μ) structured granules (fig. 1, 2), stinging cell walls of Urtica dioica (common nettle), and isolated bean mitochondria were examined with a scanning electron microscope equipped with a transmitted electron detector and an energy dispersive x-ray spectrometer. Specimens were fixed in unbuffered 3% glutaraldehyde at 4° C for 2 hours, dehydrated in ethanol, and embedded in an Araldite/Epon mixture for microanalysis. Sections were cut at 2000 Å and mounted unstained on 75 mesh Formvar coated copper grids, or 300 mesh uncoated copper grids. Specimen contrast was excellent without post-staining, and specimen resolution when viewed with the transmitted electron detector was approximately 100 Å.

Because of limited space this discussion is restricted mostly to the analysis of the structured granules in Fischerella.
Identification of Particulate Air Pollutants and Contaminants by Scanning Electron Microscopy and X-ray Spectrometry
Authors: Price J. L. , Shirley T. L.
Published: June 2020

Although our knowledge of the effects of gaseous air pollutants on plants is expanding rapidly, little is known about the identification and effects of particulate air pollutants on plant surfaces. Accordingly, a two-phase study was undertaken: (a) to identify and characterize the various particulate pollutants and contaminants found on leaf surfaces; and (b) to determine their physical and chemical effects. This report describes the progress made in the first phase of this study.

Using a Jeolco JSM-U3 scanning electron microscope with double dispersive X-ray spectrometers, observations were made on intact leaf surfaces (upper and lower) and on various particulate samples. Studies were made on various crop plants as well as on native chaparral and desert plants. Most of the samples were coated with approximately 50-100 Å of gold-palladium metal, since “charging” is a definite problem with particulate specimens.
Ion Implantation in Silicon
Authors: Magee T. J. , Comer J. J.
Published: June 2020

The use of ion-implantation in the formation of active semiconductor devices has proved to be an area of fruitful investigation over the past few years. The obvious technological significance of such studies has provided the impetus for increased utilization of known implantation techniques for doping many of the more difficult semiconductor materials. Silicon, nevertheless has remained as one of the more widely utilized semiconductors for implantation investigations. In the present study, 200 ohm-cm, n-type Lopex wafers of (111) orientation were implanted in a 3 MeV Van de Graaf accelerator with 0.9-1.0 MeV P+ ions to fluences of 5x1015 -6x1016 ions/cm2. An aluminum stopping layer was utilized on a number of samples to control the implantation depth. After implantation the silicon wafers were cut into small 0.3 cm diameter discs for electron microscopy examination. Layers of silicon were stripped frwm samples in 500 Å steps by anodic oxidation and subsequent etching. The samples were then thinned from the opposite side by conventional jet-etching techniques.
The Origin of Deformation Twinning in Polycrystalline γ'Containing Nickel-Base Alloys
Authors: Oblak J. M. , Duvall D. S.
Published: June 2020

As in certain other γ' containing nickel-base alloys, twinning is observed after the intermediate temperature deformation of polycrystalline IN-100, Figure 1. The presence of twinning is dependent upon grain orientation and is favored in grains oriented with an <011> pole near the tensile creep axis. (All foils were taken transverse to the tensile axis.) This is to be expected since <011> is near a single slip orientation of high Schmid factor for {111} <112> shear.

Previously it had been suggested that the dislocations required for {111} <112>.shear and twinning were produced by interaction of 1/2 <110> dislocations. Yet, twinning is observed at the earliest stage of deformation in polycrystalline IN-100, Figure 2. Further examination demonstrated that the grain boundaries are sources for the initiation of twinning. A typical example is shown in Figure 3 where faulted configurations associated with twinning extend from the grain boundary into the γ' containing matrix.
Electron Microscopy of Hafnium-Modified Superalloys
Authors: Kotval P. S. , Calder R. W.
Published: June 2020

Cast nickel-base superalloys, used in turbine hardware, are typically composed of ~ 60 vol.% γ' phase coherently precipitated in an f.c.c. matrix, eutectic phases, and one or more carbide phases. These alloys are not heat-treatable in the sense of being able to re-solution and reprecipitate the γ' phase. Hence, the properties are governed by the as-cast microstructure which has become increasingly more complex as higher elevated-temperature strength has been required. This improvement in strength has an associated penalty in that the ambient and intermediate temperature ductility of cast superalloys is poor.

Recently, it has been shown that additions of hafnium in nickel-base superalloys result in substantial improvements in ductility. The results presented here are from a study undertaken to define the role of hafnium in modifying microstructure in nickel-base alloys and the effect of this modification on properties.
Lattice Images of Non-Integer Planes in Gold
Authors: Bottoms W. R. , Ban L. L.
Published: June 2020

A common growth habit for gold microcrystals is a thin (111) platelet of hexagonal or trigonal symmetry. It has been shown that such microcrystals contain coherent faults in the ABCABC stacking sequence giving rise to non-zero structure factors for lattice planes of index 1/3(422). Transmission electron diffraction patterns from these crystals such as shown in Figure 2 confirm the existence of this non-zero structure factor by exhibiting reflections whose spacing and orientation correspond to lattice planes of the type 1/3(422). The diffraction pattern in Figure 2 has been superimposed on the polycrystalline ring pattern of gold for reference and the spacings of the inner-most spots is equal to the 2.497Å of the 1/3(422) planes to within the experimental error. Additional confirmation of the indexing of these spots has been obtained by electron diffraction at various angles of tilt.

Phase contrast lattice images of the non-integer planes shown in Figure 1 were obtained with axial illumination of the sample by defocusing the objective lens of a Philips EM-300 electron microscope.
Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio
Authors: Shaw G. G.
Published: June 2020

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.

When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.

In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.