bluuebunny/crossref_metadata_2025 huggingface dataset:
Continuity or Change? (In)direct Rule in British and French Colonial Africa
Authors: Müller-Crepon Carl
Published: June 2020

Current political order in Africa is often linked to legacies of colonialism, in particular to legacies of indirect colonial rule. However, evidence about the application of indirect rule is scarce. In this paper I argue that empire-level characteristics interacted with precolonial institutions in shaping the indirectness of local rule. First, British governments ruled more indirectly than French administrations, which followed a comparatively centralized administrative blueprint, came with a transformative republican ideology, and had more administrative resources. Empirically, I find that French colonization led to the demise of the lines of succession of seven out of ten precolonial polities, twice as many as under British rule. Second, precolonial centralization was a crucial prerequisite for indirect rule. Local administrative data from eight British colonies show that British colonizers employed less administrative effort and devolved more power to native authorities where centralized institutions existed. Such a pattern did not exist in French colonies. Together, these findings improve our understanding of the long-term effects of precolonial institutions and draw attention to the interaction of characteristics of dominant and subordinate units in shaping local governance arrangements.
How Does Acquisition Experience Affect Managerial Career Outcomes?
Authors: Greene Daniel , Smith Jared
Published: June 2020

We use hand-collected data from acquisition press releases to investigate how acquisition experience affects the career outcomes of non-CEO senior managers. To address the non-random nature of gaining experience, we separately use manager and firm-year fixed effects, as well as an instrumental variable analysis. Acquisition experience is positively related to compensation, the likelihood of a future board seat, and the likelihood of promotion to chief executive officer. Further tests suggest that the effects of experience decay over time, have diminishing returns, and do not depend on deal quality. Finally, we search Securities and Exchange Commission filings to document novel information on managerial roles in mergers and acquisitions.
When art was political: Historicising decolonisation and the Cold War in Southeast Asia through curatorial practice
Authors: Peleggi Maurizio
Published: June 2020

In Asia, and in Southeast Asia in particular, the Cold War was far from cold, witnessing the most deadly conflicts and political massacres of the second half of the twentieth century. Also, the clash of ideologies there did not follow a binary logic but included a third force, nationalism, which was rooted in the anticolonialist movements of the interwar years and played a significant role even in countries that decolonised peacefully after the end of the Second World War. The Cold War thus overlapped with the twin process of decolonisation and nation-building, which had its founding moment at the Asian-African Conference at Bandung in 1955, where the non-aligned camp, which advocated a neutral position vis-à-vis the two rival blocs, coalesced (one year ealier, the anticommunist Southeast Asia Treaty Organization had been established). Postcolonial aspirations to national progress that tied socioeconomic development to the civic and cultural elevation of the citizenry were widely shared among newly decolonised countries. By the mid-1960s, however, the utopian ‘Bandung Spirit’ had lost ground to Cold War realpolitik; intra-Asian and communal conflicts fomented by Cold War enmities (the Sino–Indian War of 1962, the Indo–Pakistani War of 1965, Indonesia's anticommunist purges of 1965–66) along with the escalation of the Vietnam War and the consequent exacerbation of regional divisions, belied governments’ earlier commitment to human rights, Third World solidarity and world peace. The authoritarian involution of several Asian countries that were often American allies, redoubled by the opening of their economies to multinational corporations, led many artists and intellectuals to embrace political activism. The conception of art as a revolutionary instrument in the service of the masses had been famously articulated by Mao Zedong at the Yan'an Forum in 1942. In China, Mao's prescriptions on art were sidelined, though never officially repudiated, only in the early 1990s, following the end of the Cold War and the adoption of a socialist market economy, by acknowledging the necessity ‘to respect and guarantee the creativity of individuals’.
Diagnosis and prevalence of two new species of haplosporidians infecting shore crabsCarcinus maenas:Haplosporidium carcinin. sp., andH. crancn. sp.
Authors: Davies Charlotte E. , Bass David , Ward Georgia M. , Batista Frederico M. , Malkin Sophie H. , Thomas Jessica E. , Bateman Kelly , Feist Stephen W. , Coates Christopher J. , Rowley Andrew F.
Published: June 2020

This study provides a morphological and phylogenetic characterization of two novel species of the order Haplosporida (Haplosporidium carcinin. sp., andH. crancn. sp.) infecting the common shore crabCarcinus maenascollected at one location in Swansea Bay, South Wales, UK. Both parasites were observed in the haemolymph, gills and hepatopancreas. The prevalence of clinical infections (i.e. parasites seen directly in fresh haemolymph preparations) was low, at ~1%, whereas subclinical levels, detected by polymerase chain reaction, were slightly higher at ~2%. Although no spores were found in any of the infected crabs examined histologically (n= 334), the morphology of monokaryotic and dikaryotic unicellular stages of the parasites enabled differentiation between the two new species. Phylogenetic analyses of the new species based on the small subunit (SSU) rDNA gene placedH. crancin a clade of otherwise uncharacterized environmental sequences from marine samples, andH. carciniin a clade with other crustacean-associated lineages.
Abstracting abstraction in development and cognitive ability
Authors: Demetriou Andreas
Published: June 2020

We focus on the theory of abstraction proposed by the target article. We suggest that abstraction varies at different levels of learning, cognitive development, or cognitive ability. We argue that this theory does not specify how abstraction is done at each of these levels. Because of these weaknesses, the theory cannot explicate how individuals differ in mental time travel at different phases of life or different levels of cognitive ability.
Cognitive representations and the predictive brain depend heavily on the environment
Authors: Fiedler Klaus
Published: June 2020

In their scholarly target article, Gilead et al. explain how abstract mental representations and the predictive brain enable prospection and time-traveling. However, their exclusive focus on intrapsychic capacities misses an important point, namely, the degree to which mind and brain are tuned by the environment. This neglected aspect of adaptive cognition is discussed and illustrated from a cognitive-ecological perspective.
Abstractions, predictions, and speech sound representations
Authors: Scharinger Mathias
Published: June 2020

Gilead et al. provide a unified account of predictive cognition in which abstract representations play an essential role. Although acknowledging the similarity to linguistic concepts toward the higher end of the proposed abstraction gradient, Gilead et al. do not consider the potential of their account to embrace phonetic and phonological speech sound representations and their neural bases.
Dynamic hierarchical cognition: Music and language demand further types of abstracta
Authors: Popescu Tudor , Fitch W. Tecumseh
Published: June 2020

Hierarchical structures are rapidly and flexibly built up in the domains of human language and music. These domains require a tree-building capacity – “dendrophilia” – to dynamically infer hierarchical structures from sensory input (or to hierarchically structure output), based on subunits stored in a lexicon. This dynamic process involves a crucial class of abstracta overlooked in the target article.
Touch me if you can: The intangible but grounded nature of abstract concepts
Authors: Borghi Anna M. , Tummolini Luca
Published: June 2020

Thinking about what the senses cannot grasp is one of the hallmarks of human cognition. We argue that “intangible abstracta” are represented differently from other products of abstraction, that goal-derived categorization supports their learning, and that they are grounded also in internalized linguistic and social interaction. We conclude by suggesting different ways in which abstractness contributes to cement group cohesion.
Mind wandering as data augmentation: How mental travel supports abstraction
Authors: Faber Myrthe
Published: June 2020

Gilead et al. state that abstraction supports mental travel, and that mental travel critically relies on abstraction. I propose an important addition to this theoretical framework, namely that mental travel might also support abstraction. Specifically, I argue that spontaneous mental travel (mind wandering), much like data augmentation in machine learning, provides variability in mental content and context necessary for abstraction.
A History of the First North American Electron Microscope
Authors: Franklin U.M. , Weatherly G.C. , Simon G.T.
Published: June 2020

North America's first Transmission Electron Microscope -- and the first
of immediate practical application anywhere -- was designed by two graduate
students in the Department of Physics at the University of Toronto over the
1937-38 Christmas holidays and was built during the first four months of
1938. By April it produced consistently promising micrographs and before the
end of the year, demonstrated magnifications of 20,000 diameters with
resolution better than 140Å. The resolving power had been pushed to less
than 608. (30 atom diameters) within another ten months. The design of this
microscope was adopted by the Radio Corporation of America and developed
into the prototype of a commercial series. It was this RCA production model,
based directly on the Toronto microscope, that was the equipment selected by
laboratories throughout the world for a generation. This represented an
extraordinary achievement for the two young Canadians: Albert Prebus and
James Hillier.
Many-Beam Lattice Images from Thicker Crystals
Authors: Iijima S.
Published: June 2020

Nearly a decade ago, the usefulness of lattice images for studying
crystal defects was reported by Allpress et al. (1969). They analyzed
abnormally spaced lattice fringes of crystals of the complex oxides and
derived successfully the nature of planar defects occurring on a unit cell
scale. Since then the method for studying atom configuration in crystals
using high resolution transmission electron microscopy (HRTEM) has been
investigated extensively. The studies have involved theoretical calculation
of the many-beam lattice images of perfect crystals and applications of the
method to solve problems in materials science.
Is there a Future for the STEM?
Authors: Crewe A.V.
Published: June 2020

By this time virtually everyone involved in electron microscopy has
heard of the STEM, many are familiar with some of its capabilities and a
few--a very few--are expert in Its use. This type of microscope has been
worthy of notice for only a very few years because it was only in 1971 that
we were able to show that it was a serious contender in the high resolution
game by demonstrating that it could produce images of heavy atoms (Crewe et
al., 1970).
Convergent Beam Electron Diffraction
Authors: Lehmpfuhl G.
Published: June 2020

Introduction

In electron microscopic investigations of crystalline specimens the direct observation of the electron diffraction pattern gives additional information about the specimen. The quality of this information depends on the quality of the crystals or the crystal area contributing to the diffraction pattern. By selected area diffraction in a conventional electron microscope, specimen areas as small as 1 µ in diameter can be investigated. It is well known that crystal areas of that size which must be thin enough (in the order of 1000 Å) for electron microscopic investigations are normally somewhat distorted by bending, or they are not homogeneous. Furthermore, the crystal surface is not well defined over such a large area. These are facts which cause reduction of information in the diffraction pattern. The intensity of a diffraction spot, for example, depends on the crystal thickness. If the thickness is not uniform over the investigated area, one observes an averaged intensity, so that the intensity distribution in the diffraction pattern cannot be used for an analysis unless additional information is available.
Atom Displacement Radiation Damage in Electron Microscopes
Authors: Makin M.J.
Published: June 2020

There are inevitably two important aspects of the interaction between a
specimen and the electron beam which are fundamental to all electron
microscopy. The first of these, the alteration to the beam produced by the
specimen, is the image forming process which is the basis of the instrument.
The second aspect is the alteration to the specimen produced by the beam,
which is termed 'radiation damage'. This effect, which can be severe and
undesirable in some cases, can also be exploited to obtain much information
difficult to obtain in other ways. The unique advantage of the study of
radiation damage in electron microscopes is that both aspects mentioned
above can be used simultaneously to continuously monitor the effects as a
function of electron dose. This results in a great economy of effort
compared with the use of other sources of radiation. Radiation damage in
electron microscopes can be broadly divided into two types, that arising
from electron-electron interactions, and from electron-atom
interactions.
Characterisation of Alloys and Ceramics
Authors: Thomas G.
Published: June 2020

The properties of materials are structure-sensitive. Structure is in
turn determined by composition, heat-treatment and processing. Thus it is
necessary to characterize both composition and microstructure at the highest
levels of resolution possible in order to understand materials behavior.
Such characterization requires advanced and sophisticated methods of
analysis using microscopic, diffraction and spectroscopic techniques. For
this of course electron microscopy is particularly versatile, since we are
now routinely synthesizing structure almost at atomic levels of resolution.
The interaction between composition, heat treatment and properties is
complex but this interaction must be understood if materials are to be
improved or new materials to be designed.
The Freeze-Fracture Technique: Application to the Study of Animal Plasma Membranes
Authors: Martinez-Palomo A. , Chávez B. , González-Robles A.
Published: June 2020

During recent years, the freeze-fracture (FF) technique has become one of the most useful procedures available for the ultrastructural analysis of cell components, particularly for the study of biological membranes. The method has gradually evolved from a highly specialized and technically complex procedure to a reasonably accesible one, mainly as a consequence of improvements in commercial FF equipment, the understanding of the fracturing process and the artifacts induced, and the development of ancillary techniques for the study of cell membrane organization. Due to these advances, the FF method can be considered at present as an almost standard procedure for biological electron microscopical laboratories.
Higher Order Structures in Chromosomes
Authors: Ris H.
Published: June 2020

Chromosomes are units of the genom in eukaryotes containing a specific fraction of the DNA characteristic for the species. This DNA forms the backbone of the chromosome and usually is represented by a single DNA double helix stretching from one end of the chromosome to the other. Relative to the size of most nuclei the length of the DNA is considerable. In humans for instance the haploid set of DNA is about 1 m long and in certain amphibia can measure many meters. The analysis of chromosome structure is mainly concerned with the various levels of folding or coiling by which this DNA is compacted in a regular way into chromosomes of interphase and mitotic stages.

The electron microscope has played an important role in the discovery of chromosome organization. The 20 nm fiber was first described in 1956 as a unit of interphase chromatin (Ris, 1956). Later the 10 nm fiber was recognized as the component of chromatin dispersed in the presence of chelating agents for biochemical studies (Ris, 1961).
The Electron Microscope in Earth Sciences
Authors: Wenk H.R.
Published: June 2020

Over the last ten years the electron microscope has become
well-established in mineralogical research and what used to be an exotic
instrument has found its way into several geology departments. The rapidly
growing literature on electron microscopy in mineralogy has recently been
summarized (Wenk et al., 1976) and there is not
much point in systematically reviewing progress of the last two years.
Philosophy and techniques remained largely the same except that there is
more emphasis on high resolution, and energy dispersive X-ray detectors have
become standard attachments of electron microscopes. Instead I would like to
use some examples studied at the Geology Department at Berkeley during the
last few months to illustrate a variety of applications in materials which
could not be investigated with conventional techniques such as light
microscopy, standard chemical analyses and X-ray diffraction. Geology is a
broad science which ranges from the study of crystal structures on the
atomic scale to processes taking place during mountain building on the scale
of the size of continents. The transmission electron microscope has been
used in such diverse fields as crystallography, petrology, rock deformation,
stratigraphy and environmental geology.
Conducting a Mixed-Methods Study with Older Adults in Five Languages: Lessons from the Field
Authors: Tong Catherine E. , Sims-Gould Joanie
Published: June 2020

One third of older adults in Canada are foreign-born, yet there is a dearth of literature on this population. When our team set out to engage in a mixed-methods study on the physical activity and mobility of foreign-born older adults (FBOAs), we found limited guidance. The objective of this Research Note is to share the lessons that we learned in implementing a mixed-methods study in five languages, with 49 visible minority FBOAs from diverse ethno-cultural groups. With an emphasis on practical implementation, here we share our reflections on early community engagement, linguistic accessibility and literacy considerations, facilitating communication with the research team, creating a support role for multilingual family members, organisational suggestions, and working with interpreters and monolingual transcribers. The older Canadian population is projected to become increasingly diverse in the coming decades, and it is our hope that this note will further facilitate research in this understudied area.
Estimation of incubation period and serial interval of COVID-19: analysis of 178 cases and 131 transmission chains in Hubei province, China
Authors: Yang Lin , Dai Jingyi , Zhao Jun , Wang Yunfu , Deng Pingji , Wang Jing
Published: June 2020

A novel coronavirus disease, designated as COVID-19, has become a pandemic worldwide. This study aims to estimate the incubation period and serial interval of COVID-19. We collected contact tracing data in a municipality in Hubei province during a full outbreak period. The date of infection and infector–infectee pairs were inferred from the history of travel in Wuhan or exposed to confirmed cases. The incubation periods and serial intervals were estimated using parametric accelerated failure time models, accounting for interval censoring of the exposures. Our estimated median incubation period of COVID-19 is 5.4 days (bootstrapped 95% confidence interval (CI) 4.8–6.0), and the 2.5th and 97.5th percentiles are 1 and 15 days, respectively; while the estimated serial interval of COVID-19 falls within the range of −4 to 13 days with 95% confidence and has a median of 4.6 days (95% CI 3.7–5.5). Ninety-five per cent of symptomatic cases showed symptoms by 13.7 days (95% CI 12.5–14.9). The incubation periods and serial intervals were not significantly different between male and female, and among age groups. Our results suggest a considerable proportion of secondary transmission occurred prior to symptom onset. And the current practice of 14-day quarantine period in many regions is reasonable.
Taking the inner route: spatial and demographic factors affecting vulnerability to COVID-19 among 604 cities from inner São Paulo State, Brazil
Authors: Fortaleza C. M. C. B. , Guimarães R. B. , de Almeida G. B. , Pronunciate M. , Ferreira C. P.
Published: June 2020

Even though the impact of COVID-19 in metropolitan areas has been extensively studied, the geographic spread to smaller cities is also of great concern. We conducted an ecological study aimed at identifying predictors of early introduction, incidence rates of COVID-19 and mortality (up to 8 May 2020) among 604 municipalities in inner São Paulo State, Brazil. Socio-demographic indexes, road distance to the state capital and a classification of regional relevance were included in predictive models for time to COVID-19 introduction (Cox regression), incidence and mortality rates (zero-inflated binomial negative regression). In multivariable analyses, greater demographic density and higher classification of regional relevance were associated with both early introduction and increased rates of COVID-19 incidence and mortality. Other predictive factors varied, but distance from the State Capital (São Paulo City) was negatively associated with time-to-introduction and with incidence rates of COVID-19. Our results reinforce the hypothesis of two patterns of geographical spread of SARS-Cov-2 infection: one that is spatial (from the metropolitan area into the inner state) and another which is hierarchical (from urban centres of regional relevance to smaller and less connected municipalities). Those findings may apply to other settings, especially in developing and highly heterogeneous countries, and point to a potential benefit from strengthening non-pharmaceutical control strategies in areas of greater risk.
Distant Immediacy: Badiou and Rancière on May ’68 and its Consequences
Authors: Benčin Rok
Published: June 2020

This article on the French May ’68 addresses the gap between the immediacy of the event and the series of consequences that are supposed to have followed from it. In the eyes of the critics of May ’68 from all sides of the political spectrum, the events in France have been considered as having no consequence at all, as having no political but merely cultural consequences, or as producing political consequences that were opposite to the intentions of their actors. To these interpretations, which all account for the distance between the event and its consequences by means of completely disjointing the latter from the former, the article opposes two reflections on May ’68 – those by Alain Badiou and Jacques Rancière – that attempt to examine the consequences of the very immediacy of the politics practised by the actors of the events, a politics that operates at a distance from mediation, representation and postponement. Badiou and Rancière propose some similar conclusions, but also two very different ways of reading the immediacy of the event.
Associations between parent and child physical activity and eating behaviours in a diverse sample: an ecological momentary assessment study
Authors: Wirthlin Rachel , Linde Jennifer A , Trofholz Amanda , Tate Allan , Loth Katie , Berge Jerica M
Published: June 2020

Objective:

This study is a secondary data analysis that examines the association between parent modelling of dietary intake and physical activity and the same child behaviours among different races/ethnicities using innovative, rigorous and objective measures.

Design:

Ecological momentary assessment surveys were sent to parents to assess whether their child had seen them exercise or consume food. Dietary recall data and accelerometry were used to determine dietary intake and physical activity behaviours of children.

Setting:

Participants were randomly selected from primary care clinics, serving low-income and racially/ethnically diverse families in Minnesota, USA.

Participants:

Participants were families with children aged 5–7 years old who lived with parents 50 % of the time and shared at least one meal together.

Results:

A 10 percentage point higher prevalence in parent modelling of fruit and vegetable intake was associated with 0·12 higher serving intake of those same foods in children. The prevalence of parent modelling of eating energy dense foods (10 % prevalence units) was associated with 0·09 higher serving intake of sugar-sweetened beverages. Furthermore, accelerometry-measured parent sedentary hours was strongly correlated with child sedentary time (0·37 child sedentary hours per parent sedentary hours). An exploratory interaction analysis did not reveal any statistical evidence that these relationships depended on the child’s race/ethnic background.

Conclusions:

Interventions that increase parent modelling of healthy eating and minimise modelling of energy dense foods may have favourable effects on child dietary quality. Additionally, future research is needed to clarify the associations of parent modelling of physical activity and children’s physical activity levels.
Determinants of weekly raw milk use by at-home meal preparers in the USA: evidence from the 2014–2016 American Time Use Survey – Eating and Health Module
Authors: Rhodes M. Taylor , Kuchler Fred
Published: June 2020

Objective:

The number of states in the USA that allows sales of raw milk for human consumption has been trending upwards and reached thirty-eight in 2016. These legislative changes could encourage raw milk consumption. The current study examined the determinants of weekly raw milk use by at-home meal preparers in the USA.

Design:

Using the 2014–2016 American Time Use Survey – Eating and Health Module, multivariate logit regressions and average marginal associations were estimated to examine how at-home meal preparer characteristics, time use and shopping choices, underlying health and the presence of at-risk individuals in households and raw milk legalisation status are associated with the probability an at-home meal preparer consumed or served raw milk during an average week.

Setting:

USA.

Participants:

At-home meal preparers aged 18 years and above.

Results:

Estimated average marginal associations suggested younger at-home meal preparers, male at-home meal preparers, larger sized households and households located in non-metropolitan areas were more likely to use raw milk during an average week. Married households and households with a person aged 62 years or above were less likely to use raw milk. Variables indicating health characteristics of at-home meal preparers or the presence of an at-risk individual in the household were not statistically significant.

Conclusions:

There are many government-sponsored information resources about the risks of raw milk currently available. Additional education may be needed to prevent illnesses from raw milk.
1 Mev Stem: A Progress Report
Authors: Lin P. S. , Schuler J. J. , Crewe A. V.
Published: June 2020

A high voltage scanning transmission electron microscope(HVSTEM) has a
number of unique features:

Compared with a high voltage conventional electron
microscope, it can provide better resolution and contrast for
thick specimens, because of the absence of the chromatic
aberration contributed by energy-loss events;

Compared with a low voltage STEM, it can collect
inelastically scattered electrons more efficiently, since the
the characteristic angle of single inelastic scattering varies
inversely with energy;

The size of the beam can be varied over a wide range for the
purpose of selected-area-diffraction. The application of this
promising technique in particular to the study of biological
molecules which form crystals too thick to be studied with low
voltage electron microscopies awaits exploration.

In addition, in theory, the spot size of a HVSTEM is better than one
Ångstrom – which undoubtly could not be achieved by a low voltage STEM
unless the spherical aberration is corrected.
Dynamical Scattering in Electron Diffraction of wet Protein
Crystals
Authors: Chang B. B. , Parsons D. F.
Published: June 2020

The significance of dynamical scattering effects remains the major
question in the structural analysis by electron diffraction of protein
crystals preserved in the hydrated state. In the few cases (single layers of
purple membrane and 400-600 Å thick catalase crystals examined at 100 kV
acceleration voltage) where electron-diffraction patterns were used
quantitatively, dynamical scattering effects were considered unimportant on
the basis of a comparison with x-ray intensities. The kinematical treatment
is usually justified by the thinness of the crystal. A theoretical
investigation by Ho et al. using Cowley-Moodie multislice formulation of
dynamical scattering theory and cytochrome b5as the
test object2 suggests that kinematical analysis of
electron diffraction data with 100-keV electrons would not likely be valid
for specimen thickness of 300 Å or more. We have chosen to work with
electron diffraction patterns obtained from actual wet protein crystals (rat
hemoglobin crystals of thickness range 1000 to 2500 Å) at 200 and 1000 kV
and to analyze these for dynamical effects.
The Influence of Specimen Thickness in Quantitative Electron Energy Loss
Spectroscopy
Authors: Zaluzec Nestor J.
Published: June 2020

The application of electron energy loss spectroscopy (EELS) to light
element analysis is rapidly becoming an important aspect of the
microcharacterization of solids in materials science, however relatively
stringent requirements exist on the specimen thickness under which one can
obtain EELS data due to the adverse effects of multiple inelastic
scattering.1,2 This study was initiated to
determine the limitations on quantitative analysis of EELS data due to
specimen thickness.
Low Energy Loss Structure of Small Aluminum Particles
Authors: Batson P.E. , Treacy M.M.J.
Published: June 2020

Usually, configuration effects are ignored in microanalytical work. That
is, the energy loss mechanisms in small volumes are expected to be similar
to those in large volumes. However, it is shown elsewhere in these
proceedings1 that this assumption is not valid for
bulk plasmons in small Al spheres. In fact, ‘configurational’ energy loss
effects can dominate the low energy loss region when probing small volumes.
These effects include: surface plasmons, bulk plasmon spatial quantization,
Schottky barriers, and any other mechanisms that rely on the close proximity
of surfaces or interfaces. We have examined the energy loss structure for
˜200Å Al particles (formed as explained in Ref. 1) with the VG Microscopes,
Ltd. HB5 scanning transmission electron microscope at 100KeV. The particles
consist of single crystal Al cores covered by ˜40Å of
Al2O3, and possibly further
covered by 5-15Å of carbon contamination. We obtained electron energy loss
spectra (EELS), and inelastic scattering images of the particles to
correlate the observed EELS structure with the spatial structure and to make
a tentative identification of the losses. The spectra were recorded with a
probe angular diameter of 8mR (1.4Å−1) and an energy
loss resolution of 0.7eV. The images were recorded with an energy loss
resolution of 2eV.
Radiation-Induced Precipitation in Ti-6A1-4V
Authors: O'Neal J. E. , Sastry S. M. L. , Davis J. W.
Published: June 2020

The radiation-induced defect structure and nonequilibrium phase
precipitation were studied in T1-6A1-4V (an alpha-beta titanium alloy),
irradiated at 450 ± 30°C in row VII of the EBR-II to a fluence of 3.0 ×
1021 neutrons/cm2
(En > 0.1 MeV). The Irradiation-induced defect
microstructures were examined using bright-field, conventional dark-field,
and weak-beam dark-field techniques. The nature of dislocations and
dislocation loops was determined by standard-contrast experiments under
two-beam conditions, and the small defect clusters were identified using the
line-of-contrast criterion and black-white vector orientation
criterion.
In-Situ Observations of Dislocations in Lithium
Authors: Sherry W. M. , Simmonsberger P. , Prinz F.
Published: June 2020

The alkali metals, as a unique class of elements in the periodic table,
possess a number of interesting characteristics. Elements such as lithium
and sodium are amenable to in situ TEM studies since dislocations can be
generated and their motion activated by the thermal stress gradient produced
by the electron beam. Also, the low atomic number of lithium allows one to
observe relatively thick foils. The extreme chemical reactivity of these
elements, however, makes experimental investigation difficult and requires
that all experiments be performed under inert atmosphere.
Crystallographic Differences of Metastable NI2MO in a NI-MO-AL
Superalloy
Authors: Kersker Michael M. , Aigeltinger E. A. , IIren J. J.
Published: June 2020

Ni-rich alloys based on approximate ternary composition Ni-8Mo-15A1
(at%) are presently under investigation in an attempt to study the
contribution, if any, of the profusion of Mo-rich NixMo
metastable compounds that these alloys contain to their excellent mechanical
properties. One of the alloys containing metastable
NixMo precipitates is RSR 197 of composition
Ni-8.96Mo-15.06A1-1.98Ta-.015Yt. The alloy was prepared at Pratt and Whitney
Government Products Division, West Palm Beach, Florida, from rapidly
solidified powder. The powder was canned under inert conditions and extruded
as rod at 1315°C. The as-extruded rod, after air cooling, was solution
treated at 1315°C for two hours, air cooled, and heat treated for one hour
at 815°C, followed again by air cooling.
Carbon Black Test Objects
Authors: Hines R. L.
Published: June 2020

Recent studies of crystal support phase contrast electron microscopy
have in-dicated the need for test phase objects to evaluate phase contrast
enhancement. Carbon particles deposited by carbon arc evaporation in argon
appear to be good test objects and may be of more general use as test
objects for high resolution alignment and focusing. Test objects should be
amorphous, chemically inert, relatively stable in the electron beam, easy to
disperse with high surface concentrations and have high contrast for
diameters near 20 nm. The graphitized carbon black that is used to display
lattice images is difficult to disperse with high surface concentrations of
20 nm particles and the particle contrast depends strongly on orientation.
Latex particles are approximately spherical but are not stable in the
electron beam and are usually dispersed from solutions which sometimes
requires surface treatments and may leave surface residues. Carbon arc
evaporation in an argon atmosphere is discussed here as one approach for
forming carbon particle aggregates and carbon nanospheres. A carbon
nano-sphere is considered to be an approximately spherical particle of
amorphous, nonporus pure carbon with a radius of several. nanometers. Larger
carbon spheres are present in some commercial carbon blacks but it is not
known at present if they can be prepared with smaller radii and dispersed
with sufficient surface concentration to be useful as test objects. Kappler
et al.2 have described preparation of carbon black by
resistive heating of carbon in an argon atmosphere. The deposit is
characterized as nonporus and displays the typical particle aggregate
appearance of a high structure carbon black.
In-Situ Observation of Clay Minerals Hydrated and Intercalated With
Liquid Chemicals Using Film-Sealed Environmental Cell
Authors: Fukushima K. , Kohyama N. , Fukami A.
Published: June 2020

A film-sealed high resolution environmental cell(E.C) for observing
hydrated materials had been developed by us(l). Main specification of the
E.C. is as follows: 1) Accelerated voltage; 100 kV. 2) Gas in the E.C.;
saturated water vapour with carrier gas of 50 Torr. 3) Thickness of gas
layer; 50 μm. 4) Sealing film; evaporated carbon film(20 nm thick) with
plastic microgrid. 5) Resolving power; 1 nm. 6) Transmittance of electron
beam; 60% at 100 kV.

The E.C. had been successfully applied to the study of hydrated
halloysite(2) (3). Kaolin minerals have no interlayer water and are
basically non-expandable but form intercalation compounds with some specific
chemicals such as hydrazine, formamide and etc. Because of these compounds
being mostly changed in vacuum, we tried to reveal the structure changes
between in wet air and in vacuum of kaolin minerals intercalated with
hydrazine and of hydrated state of montmori1lonite using the E.C. developed
by us.
Classification of Cotton-Plant Dusts by Microelemental Analysis
Authors: Goynes Wilton R.
Published: June 2020

Dusts produced in the processing of cotton fibers are believed to be
causative factors of the chronic respiratory ailment byssinosis (1).
Although these multicomponent dusts have been studied extensively, neither
the identity of the causative agent(s) nor its exact origin have been
determined. Differences in the physiological activity of dusts generated at
different stages of cotton processing have been reported, indicating some
variation in components. Sources are not known for all components of these
dusts but they are probably composed largely of the various crushed parts of
the cotton plant, along with a possible complex mixture of soil dusts,
pollens, and fungal materials. Cotton plant parts, especially the bract (2),
may be the responsible factor in production of byssinotic symptoms. However,
it has been difficult to identify specific sources of respirable particles
in the dusts because the various components have been mascerated beyond
recognition by anatomical or morphological structure.
High Resolution Tem of Semiconductor Defects
Authors: Spence J. C. H.
Published: June 2020

Computational techniques are now well developed for the determination of
the electronic structure of semiconductor surfaces and their line and planar
defects. These calculations depend sensitively on the atomic structure
assumed for the defect, and so provide an outstanding challenge for high
resolution electron microscopy, while it is unlikely that the details of the
charge redistribution which controls the electronic structure of defects
will be directly imaged for many years, the use of a-priori chemical
knowledge may frequently greatly limit the number of likely defect
structures. New high resolution imaging methods for the study of surface
roughness, an area of almost total ignorance, are described elsewhere in
this volume (1). It seems likely that the electronic structure of the line
and planar defects will only be solved when all the information available
from such techniques as EPR, SDP Hall effect measurements, CTS and EBIC are
considered (see (2) for a review of recent work). The unique contribution of
high resolution electron microscopy (HREM) is its non-statistical capability
of analysing isolated, well characterised defects. The outstanding problems
which semiconductor defects offer for HREM are (i) the difficulty of
obtaining three dimensional defect structure information (ii) the need to
extract information beyond the point resolution limit of current machines
(but within their information resolution limit (3)) (iii) the need for
chemical (atomic number) information. These three problems are briefly
discussed below in the light of recent work.
Characterization of Laser Annealed Semiconductors
Authors: Narayan J.
Published: June 2020

Laser radiation of visible wavelength in silicon and gallium arsenide is
strongly absorbed in a thin (~lµm) layer near the surface. The absorbed
photon energy is rapidly (≤10-9s) transferred to the
lattice, and ultimately appears as heat. The heating and subsequent cooling
rates depend inversely upon the beam-interaction time. For pulsed lasers
with pulse durations of the order of nanoseconds, the heating and cooling
rates can easily exceed
108Ks-1.1
One of the unique features of this laser-irradiation is that while surface
layers melt, underlying substrates remain close to room temperature. Crystal
growth rates associated with this rapid melting and solidification are
meters per second (compared to 10-5 m
s-1 under normal crystal-growth) with essentially
unidirectional heat flow. In this paper some of the unique microstructural
modifications in laser irradiated silicon and gallium arsenide are described
and correlation of microstructures with physical properties is
discussed.
A Comparison of Neutron and Nickel-Ion Irradiation of Some Binary Nickel
Alloys
Authors: Sprague A. , Roarty K.B. , Johnson R.A. , Smidt F.A.
Published: June 2020

High energy heavy ion irradiation has been widely applied as a tool to
study radiation damage in materials, both in attempts to simulate neutron
damage and to investigate radiation effects mechanisms. Two important
aspects of such studies are the effects of alloying elements on a metal’s
irradiation response and the influence of damaging particle type and dose
rate on these alloying effects. The present experiments examined these
aspects by studying the microstructures of a series of low-concentration
binary nickel alloys following neutron and nickel-ion irradiation.
The Study of Grain Boundaries in Ceramics by Electron Diffraction
Authors: Carter C.B.
Published: June 2020

Grain boundaries are particularly important in polycrystalline ceramics
since it is found experimentally that the properties of the grain boundary
region control many properties of the material. In ceramic materials, most
interfaces between adjacent grains appear to take one of two forms: they can
have a periodic structure if the two grains are in intimate contact - such
boundaries would be similar to boundaries observed in metals; or there may
be a film of amorphous material present in the interface - the width of such
a film may be as little as ~lnm. it is also possible that a second
crystalline phase is present at the boundary or, of course, the structure of
the interface may consist of a combination of these. Until recently the main
techniques used for studying grain boundaries in ceramics have been the
strong-beam bright-field and weak-beam dark-field modes of diffraction
contrast and lattice-fringe imaging techniques. Diffraction contrast
techniques are particularly valuable for studying grain boundaries composed
of dislocations where the dislocation spacing is greater than ~15nm or ~4nm
for strong-beam and weak-beam respectively. The lattice-fringe imaging
technique has been particularly valuable for the identification of
boundaries which contain thin films of amorphous material. An additional
technique using diffuse scattered electrons to study such boundaries has
been shown to be susceptible to misinterpretation when the specimen is
coated to prevent charging in the microscope.
Identification of some Crystallographic Features of Martensite in Steels
by Microdiffraction
Authors: Sarikaya M. , Rao B.V.N. , Thomas G.
Published: June 2020

Considerable attention should be paid to the interpretation of electron
diffraction, such as the understanding of the extra reflections and other
effects in an SAD pattern obtained from lath martensite by making allowances
for spatial resolution limitations in the SAD patterns. These difficulties
can be overcome by utilizing the convergent beam electron diffraction (CBED)
method which permits the use of different probe sizes to obtain
crystallographic information from very small regions. In the present study
some crystallographic features of lath martensite in low and medium C steels
have been Identified and some others verified by using CBED.
A STEM Microstructural Analysis of Rapidly Solidified High-Sulfur
Austenitic Steel
Authors: Kelly Thomas F.
Published: June 2020

Rapid solidification processing (RSP) has been viewed as a means of
obtaining better properties from (crystalline) metal alloys where the
improvements are a result of the various effects of high cooling rates (>
105°K/sec) on the “as solidified” structure. Described herein are the
results of an investigation into the microstructural and microchemical
nature of a rapid solidification processed high sulfur, 303 stainless steel
using a dedicated scanning transmission electron microscope (STEM).

The RSP material of this study was prepared by forced convective
cooling, in helium, of centrifugally atomized metal droplets to achieve
cooling rates on the order of 105°K/sec. The resultant powder, of n 50 ym
average particle size, was consolidated to a fully dense state. Equivalent
conventionally processed 303 SS material was obtained from Carpenter
Technology Corporation. The 303 SS material of this investigation was
therefore studied in three processed states:the rapidly solidified powder,
the rapidly solidified and consolidated bar stock, and the conventionally
processed material.
Precipitation Reactions in a Beryllium-Bearing Stainless Steel
Authors: Carr Martin J. , Heiple C. R.
Published: June 2020

Precipitation reactions in a beryllium-bearing stainless steel alloy
have been studied by TEM and electron diffraction for ageing temperatures
between 400° and 900°C. The nominal composition of the alloy was 38% Ni -
21% Cr - 1% Mn - 0.5% Be - Bal Fe. Specimens were solutionized for one hour
at 1150°C and water quenched. The ageing reaction was studied by hardness
measurements for times between 0.5 and 16 hours. The TEM specimens discussed
herein were made from samples aged one hour.

The ageing reactions in this alloy were similar to those reported for
Cu-Be1, Ni-Be2, and
Fe-Ni-Be3, except that no evidence of cellular
precipitation was observed.
An Electron Microscopic Study of Hydrogen Dissolution in FeTi
Authors: Pande C. S.
Published: June 2020

The intermetallic compound FeTi (with CsC1 structure) is a candidate
material for hydrogen storage systems. FeTi forms iron titanium hydride
(FeTiHx, where x represents a variable number of hydrogen atoms, up to about
2). In this study, electron microscopy has been used to study (a) the nature
of the ‘activation’ process i.e. introduction of hydrogen in FeTi, (b) the
morphology and structure of hydride phases and (c) the microstructure of the
material after the subsequent removal of hydrogen. For this purpose the same
region of the specimens were observed in the electron microscope (a) before
the dissolution of hydrogen, (b) after the dissolution of hydrogen and (c)
after the removal of hydrogen.
Ultrastructural Changes Due to Toxaphene Insecticide
Authors: Caceci T. , Chapman G. B.
Published: June 2020

The deleterious effects of agricultural insecticides on non-target
organisms have been under investigation for a number of years. Most studies
have dealt with the degree of toxicity, mechanism of action, metabolism, or
distribution in the biosphere. There has been comparatively little interest
in morphological effects of an insecticide at its site of entry.

Toxaphene, a general-purpose organochlorine insecticide that is widely
and heavily applied in the U.S. is quite toxic to fish. It can be absorbed
via the gills or the gut. This study examined the effects of Toxaphene on
the absorptive cells of the anterior intestinal bulb in goldfish (Carassius
auratus). These cells are involved in the uptake of dietary lipids; since
Toxaphene is lipid-soluble, this was considered the likeliest region of the
digestive tract to exhibit damage due to its presence.