bluuebunny/crossref_metadata_2025_split huggingface dataset:
'Secondary’ Electron Detector Design and Positioning in the Variable Pressure Scanning Electron Microscope: The Colour Option
Authors: Griffin Brendan J , Browne James R , Egerton-Warburton Louise , Drouin Dominique 
Published: July 2020

Abstract
The simple models for low energy secondary electron (SE) detection in the variable pressure or environmental scanning electron microscope (ESEM) describe a gas-amplified cascade from sample to detector when a conventional biased detector is used. Recent images obtained using a modified specimen current imaging approach however have suggested that at least a portion of the image is an induced field effect, in agreement with some of the early work. Our recent aim has been to investigate a range of detector designs and positions within the chamber in both the old ElectroScan E-3 model ESEM and the current generation FEI XL30 ESEM TMP. The results support the earlier observations of induced signal components being present, with even ‘negative’ or inverted images being obtained under some detector configurations due to the noise cancellation techniques used (figure 1). These results are being quantified using the DQE measurement approach to allow an objective comparison of different designs and positions. This data will be presented for the commercially available detectors and for the ‘Griffin’ grid detector under a range of operating conditions.
Space Charge Artifacts in ESEM Images: Shadowing and Contrast Reversal
Authors: Toth M , Phillips MR 
Published: July 2020

Abstract
The environmental scanning electron microscope (ESEM) employs a series of pressure limiting apertures and a differential pumping system to allow for electron imaging at specimen chamber pressures of up to 50 torr. Images rich in secondary electron (SE) contrast can be obtained using the gaseous secondary electron detector (GSED) or ion current (Iion) signals. The GSED and Iion signals are amplified in a gas cascade. SEs emitted from a sample are accelerated through the gas in the specimen chamber by an electric field, EGSED, produced by a positively biased electrode located in the chamber, above the specimen. The accelerated SEs give rise to a cascade ionization process that can amplify the SE signal by up to three orders of magnitude. Electrons produced in the cascade are rapidly swept to the biased electrode and are efficiently removed from the gas. Positive ions produced in the cascade drift away from the electrode with a velocity that is at least three orders of magnitude lower than that of the electrons.
ESEM Studies of Surface Phenomena in Complex Fluids
Authors: Mathews R G , Stokes D J , Donald A M 
Published: July 2020

Abstract
The ability of Environmental Scanning Electron Microscopy (ESEM) to provide electron images of volatile and/or insulating samples without need for sample preparation allows imaging of liquid surface at resolutions substantially beyond those obtainable with optical microscopy.
The system chosen for study was a dispersion of di-iso-heptyl-phthalate (DHP) in water, stabilised with a mixed surfactant system comprising equal masses of Tween 20 (Polyoxyethylene sorbitan monolaurate) and Span 20 (Sorbitan monolaurate) at an effective HLB of 12.75. DHP was chosen for its unsaturated electronic structure, which improves secondary electron contrast in the ESEM, and for the similarity of its density (995 kgm-3) to water. Emulsions, containing between 25 and 80 vol% DHP and 0-3 wt% surfactant were produced in a Silverson mixer fitted with an emulsor screen. Samples were placed in a brass holder on a Peltier cooling stage and cooled to 2°C.
Imaging the Probe Skirt in the Environmental SEM
Authors: Thiel BL , Bache IC , Smith P 
Published: July 2020

Abstract
In low vacuum scanning electron microscopes, the primary beam is partially scattered by the gas present in the specimen chamber. The development of these microscopes, in particular the so-called ‘Environmental’ SEM, was initiated when it was realized that this scattering does not necessarily compromise the imaging capabilities of the instrument. Indeed, some modern commercial instruments are capable of better than 2 nanometer resolution at gas pressures of several torr. The accepted explanation for this is as follows: The mean-free-path of the high energy primary electrons is several millimeters in one torr of water vapour (for example). Because the actual pathlength of electrons travelling through the gas is only a few millimeters, most of them do not scatter at all. Those that do scatter are supposedly distributed over a relatively large area. Thus, the probe features a high-intensity central region surrounded by a slowly decaying low-intensity skirt. High resolution imaging is possible because the signal-to-(skirt)background ratio is high.
Two-Photon Microscopy of Single Molecules
Authors: Yuste R , Majewska A , Holthoff K , Holthoff K 
Published: July 2020

Abstract
Two-photon excitation has enabled investigators to image living cells in highly scattering media like the central nervous system (1). We have used a custom-built two-photon microscope to image dendritic spines from living cortical pyramidal neurons. Pyramidal cells form the majority of the neuron in the mammalian cortex and they receive practically all their synaptic contacts through dendritic spines. Dendritic spines are small (&lt;1 μm diameter) appendages that have been practically inaccessible to physiological measurements until the application of two-photon excitation to their study (2). We have concentrated in two questions:
A- Calcium compartmentalization of spines: Mechanisms of calcium decay kinetics.
Dendritic spines can compartmentalize calcium (2). Although the mechanisms of calcium influx into spines have been explored (3), it is unknown what determines the calcium decay kinetics in spines. We investigate calcium dynamics in spines from rat CA1 pyramidal neurons in slices.
The Response of Maize Protoplasts to High Intensity Illumination in Multi-Photon Fluorescence Microscopy
Authors: Lin B L , Kao F J , Cheng P C , Cheng P C 
Published: July 2020

Abstract
Multi-photon fluorescence microscopy has been cited for its advantage in increased depth penetration due to low linear absorption coefficient of biological specimen in the near infrared (NIR) range. Using a pulsed laser, it is possible to efficiently excite two-photon fluorescence with a high peak power while keeping the average power low to avoid thermal and photochemical damages to the specimen. Currently, mode-locked Ti-sapphire and Cr-Forsterite lasers that generate sub-picosecond pulses are used as the light source for multi-photon fluorescence microscopy. Because of the need of high peak power for efficiently exciting two-photon fluorescence, the relationship between cell damage and peak power has become an interesting and much debated topic in the application of multi-photon fluorescence microscopy. It is conceivable that at high illumination intensity, non-linear photochemical processes may have impacts on cell physiology and viability in ways much different from low illumination in the linear domain.
Multi-photon Fluorescence Micro-spectroscopy of Plant Tissues
Authors: Kao F J , Lin B L , Cheng P C 
Published: July 2020

Abstract
Considering its non-linear nature, two-photon excitation may generate very different spectral response in samples when compared with single photon excitation. It is thus necessary to measure the two-photon spectra of samples, so that the two-photon fluorescence microscopic images can be properly interpreted. Fluorescence spectra obtained from bulk samples may not provide useful information for microscopy. For instance, due to the relatively small contribution to the total fluorescence intensity, a small number of fluorescent particles in a generally fluorescing specimen may escape detection when the spectrum of the specimen as a whole is obtained. Under two-photon excitation, the background noise can be greatly reduced due to the naturally limited excitation volume of focused laser beam. In addition, signals resulted from second harmonic generation (SHG) may be mixed with low level broad-band background autofluorescence which is commonly found in biological specimen. Therefore, measuring fluorescence spectrum from a micro-focused volume is essential for the proper interpretation of multi-photon fluorescence images.
Use of Confocal Imaging for Arthropod Morphological Studies
Authors: Klaus Angela V , Kulasekera Varuni L , Platnick Norman 
Published: July 2020

Abstract
Morphological studies in spider and insect groups (Phylum Arthropoda) have historically relied upon traditional imaging techniques such as light microscopy (LM) and scanning electron microscopy (SEM). It has often been difficult, however, to examine some structural details of certain specimens due to limitations of the techniques. Light microscopy does not always provide adequate depth of focus for visualizing the true three-dimensional structure of a specimen, and out-of-focus light in the image can obscure detail. SEM is not applicable if the specimen is too delicate to undergo critical point drying. Additionally, SEM is a surface technique and does not provide any information about internal structure.
If a specimen is transparent to light, information about the morphology of internal structures, and connections between structures, can easily be obtained using confocal microscopy without the problems associated with traditional LM. In this study, we used confocal laser scanning microscopy (CLSM) to study the morphology of chitinous arthropod structures by taking advantage of their autofluorescent properties.
High Resolution Optical Microscopy Will Play a Major Role in Functional Assessments and the Prevention of Disease
Authors: Bradford, Chairman Robert W , Oversight Curriculum 
Published: July 2020

Abstract
The typical aging processes can be characterized by a gradual alteration and essential breakdown of the functional systems of the body. Numerous factors play important roles in the alterations of these pathways from biochemical individuality and genetic predisposition to environmental insults and deficiency states.1 Clinical research, as but one example, has clearly documented the role of free radicals (ROS) or oxidative injury in disease and aging affecting the body's basic cellular structures.
The objective of functional or health assessments is to be able to detect in vivo stresses and imbalances in the biological systems, while the patient is asymptomatic, so that early therapeutic intervention can resolve the problems prior to disease onset or accelerated aging. The ability to assess risk factors and treat the sub-clinical metabolic toxicities, deficiency states, hormonal imbalances, oxidative injury (ROS), immunodeficiencies, enzyme down regulations, antioxidant status, metal toxicities, cardiovascular stresses, organ reserves/stresses and detox systems in a low-complexity, cost-effective office procedure is true preventive medicine.
Laser Capture Microscopy as an Aid to Ultrastructural Analysis
Authors: Grant K W , Anderson N J , Hammarback J A , Sweatt A , Dawson B , Moore P , Jerome W G 
Published: July 2020

Abstract
Laser capture microdissection (LCM) is a technique that provides homogenous cell populations for molecular and light microscopic analysis. During viewing by a standard wide-field microscope, a specific cell is selected. Heat from a near-infrared laser melts an ethylene vinyl acetate (EVA) transparent film which bonds to the individual selected cell. Several thousand cells can be selected and captured using this method. A homogeneous subpopulation of cells may be collected, one at a time, by histologic characteristics and/or histochemical staining from frozen sections, deparaffinized tissue, cell cultures or a blood smear.
Previously, this technique has primarily been used to capture cells for DNA or RNA analysis. This study was undertaken to investigate the possibility of capturing a subpopulation of cultured cells in order to study their ultrastructure with the transmission electron microscope (TEM). We report here that cultured cells can be processed, captured and embedded for electron microscopy, in such a manner as to maintain ultrastructure.
Ultrastructural and Histological Analysis of the Bone-Implant Interface
Authors: Steflik DE , Corpe RS , Young TR , Parr GR , Sisk AL 
Published: July 2020

Abstract
The bone interface to implanted biomaterials (both orthopaedic and dental implants) is the critical component for initial fixation of these uncemented biomedical devices. The mechanism of osteogenesis at the biomaterial surface after surgical placement is critical to understand to enhance osseointegration, and thereby implant success. The purpose of this paper is to report comprehensive and correlative electron and light microscopic observations from a five-year study involving the bone interface to 120 implants placed into 30 adult animals.
As a model system to evaluate bone and associated tissue interfaces to implanted biomaterials, 120 endosteal dental implants were placed into the mandibles of 30 adult mongrel dogs. Premolars were extracted and the sites were allowed to heal for 2 months prior to implantation. Surgery employed low speed drilling, copious internal and external irrigation and followed manufacturer recommendations for these commercially available implants.
Genistein Inhibits Cell Proliferation and Induces Mitochondrial and Nuclear Alterations That Indicate Mechanisms Involved in Apoptosis
Authors: Gobert Geoffrey , Curren Ed , Welshons Wade , Sun Qing-yuan , Schatten Heide 
Published: July 2020

Abstract
A highly significant correlation between reduced incidence of breast cancer in Asian countries and consumption of soy suggests that specific components in soy may have anticarcinogen activity. The soy ingredients genistein and daidzein have been found to inhibit induced breast tumors in animal and cell culture models. These isoflavones are known to be both agonists and antagonists of estrogen activity but only genistein is also a potent inhibitor of tyrosine kinases which are the primary intracellular signalling mechanisms associated with the regulation of cell proliferation.
Genistein promotes cell proliferation in breast cancer cells at low concentrations in its function as estrogen agonist but inhibits cell proliferation at high concentrations (30 μM). In order to investigate the underlying mechanisms by which high concentration of genistein inhibit cell proliferation we treated MCF-7 cells with increasing concentrations of genistein and analyzed cells by immunofluorescence and transmission electron microscopy (TEM).
Effects of Co60 Irradiation on Muscle Fiber Types of the Grass Frog
Authors: Cohen Glenn M , Scott Margaret F 
Published: July 2020

Abstract
Striated skeletal muscle has been considered radioresistant because it is highly differentiated and post-mitotic. Striated muscle does, however, respond to irradiation with morphological and biochemical changes after short and long latency periods; vascular and/or neurological impairments might contribute to the delayed responses to irradiation.
The objective of the present study was to determine the susceptibility of three amphibian muscle fiber types to Co60 irradiation. In amphibians, the three major fiber types are 1) large twitch fibers, which contain low levels of mitochondrial enzymes and lipids, but intermediate levels of glycogen; 2) small twitch fibers, which contain high levels of both glycolytic and mitochondrial enzymes (FIG. 1); and tonic fibers, which contain low levels of all three histochemical markers. Thus, the determination of susceptibility of different amphibian fiber types to irradiation might indicate whether the metabolic characteristics of the fibers, rather than morphological or electrical properties, could serve as an early indicator of radiation damage.
Electron Microscopic Evaluation of Vector Quality for Gene Therapy
Authors: Yu Qian-Chun , Ma Xiaokui , Croyle Maria , Qu Guang , Huang James , Gao Guangping , Hughes Joe , Wilson James 
Published: July 2020

Abstract
Successful gene therapy is dependent upon well regulated, long-term expression of transgenes in the target tissue. The development and production of very high quality vectors are one of the most important steps leading to delivery of the desired genes. Although several types of vectors have been used for the delivery of transgene to the target cells of the host, our institute routinely uses recombinant viral vectors including adenovirus and adeno-associated virus (rAAV) for gene therapy studies. To assure high quality of the viral vectors being used for animal experiment as well as clinical trials, a number of quality control protocols, including electron microscopy, was developed and implemented to monitor the overall purity, and density of the vectors.
Transmission electron microscopy (TEM), combined with optimized procedure of negative staining for virus, offers a unique means to generate visual data of the vector preparation; and it has gained increasing application to help assess the quality of vectors.
Mineralization of Collagen in Avian Tendon Examined by Tapping Mode Atomic Force Microscopy
Authors: Siperko L M , Landis W J 
Published: July 2020

Abstract
Type I collagen fibrils provide a structural framework for mineral nucleation, growth, and development during calcification of tissues such as bone, dentin and tendon of many vertebrates. Previous work has described a general mechanistic model of normal collagen- mineral interaction in which nucleation events take place on collagen surfaces and in channels or gaps defined by periodic (64-70 nm) collagen hole and overlap regions. These sites are created in early collagen molecular and macromolecular assembly. The model suggests that, once nucleated, the mineral within channel spaces grows into irregularly shaped platelets of small size and these develop into larger platelets whose detectable crystallographic c-axis direction parallels the long axis direction of the collagen fibrils with which they associate. The fate of mineral nucleated on collagen surfaces is unclear, although it is known that the volume of extracellular tissue space between adjacent collagen fibrils, like that within the fibrils, also becomes mineralized.
Stylet Length of Silverleaf Whitefly Adults and Nymphs And The Mechanism of Stylet Insertion Into the Leaves of Host Plants
Authors: Freeman Thomas P , Buckner James S , Nelson Dennis R 
Published: July 2020

Abstract
Silverleaf whiteflies, Bemisia argentifolii Bellows and Perring, feed on a wide variety of plants and are capable of causing significant economic damage. Host selection may be determined by a wide variety of factors. Adult whiteflies may feed on one leaf and then move to another, however, their feeding and oviposition choices may well determine the success of egg hatch and nymph survival. Current theory suggests that whiteflies feed (Fig. 1) and oviposit on the abaxial surface of leaves due to the closer proximity of phloem tissue. This is believed to be particularly important for nymphs which are stationary during much of their development and have shorter stylets than adults. We examined whitefly stylet penetration into cotton and hibiscus leaves using both light and scanning electron microscopic techniques.
Adult silverleaf whitefly stylets were found to range from 100 urn to more than 300 um in length.
Light and Electron Microscopy Study of the Metacestode (Coenurus) of Taenia multiceps
Authors: Ramirez-Bon Enrique , S. Daniel Gonzalez 
Published: July 2020

Abstract
Introduction:- The metacestode (larval stage) of Taenia multiceps, it is characterized by its big bladder fluid filled and multiple scoleces. Affect very frequently herbivorous mammals like sheeps, hares and rabbits (1); and occasionally humans (2), causing disorders very similars to that caused by Cysticercus cellulosae (3), the larval stage of Taenia solium. The adult parasite, Taenia multiceps, it is found in the intestine of domestic and wild carnivorous like dogs, wolves and coyotes.
In this paper we describe the morphology at the optical and electron microscope level of coenuri collected from hares.
Material and Methods.- Coenuri collected from hares, were dissected from muscle tissues and fixed in glutaraldehyde 2.5% in 0.1M phosphate buffer pH 7.4, postfixed in 1% osmium tetroxide in the same buffer. Inclusion in medcast resin (Pelco). Sections were stained with uranyl acetate and lead citrate, and observed in a Zeiss EM 109 electron microscope.
Pulmonary Neuroepithelial Bodies in Neonatal Rats Chronically Exposed to Nitric Oxide
Authors: Hung Kuen-Shan , Her Xay K 
Published: July 2020

Abstract
Pulmonary neuroepithelial bodies (NEBs) consist of clusters of innervated endocrine cells localized in human and animal lungs. They are prominent in late fetal and neonatal lungs and their density declines with increased postnatal age. Gas sensing functions of these structures have been suggested by Lauweryns and Cokelaere. Subsequent experiments show that chronic hypoxia leads to an increase in the size or number of NEBs, and prolonged hyperoxia also causes elevation of NEB numbers. Animals exposed to cigarette smoke also had an increased number of immunoreactive NEBs.
Inhaled nitric oxide (NO) can reverse pulmonary vasoconstriction induced by hypoxic breathing or ligation of ductus arteriosus in newborn and young animals. These studies led to clinical use of NO for treatment of pediatric patients with pulmonary hypertension. However, direct effects of inhaled NO on various components of the lung are not clearly understood.
Ultrastructure of the Stomach of Aphanius Dispar (Cyprinodontidae), With Special Reference to Stress from Starvation
Authors: Ba-Omar T A , Victor R 
Published: July 2020

Abstract
The effect of starvation on the mucosa of the Aphanius dispar stomach is investigated. The gastric erosion resulting from stress due to starvation over a period of 24 - 120 hours has been described at the ultrastructural level.
Specimens of A. dispar with a total length (TL) range of 30.4-46.3 mm, weighing from 0.43-0.70 gm were collected from Wadi Al-Khod, Sultanate of Oman (Lat. 23° 30’ N; Long. 58 ° 40'E). Thirty six fish were acclimatized for two weeks and were fed with Tetramin flakes, ad libitum, twice daily. Thirty of these fish were subsequently starved in a chamber separated from the six control fish that were fed normally in the same tank. Six starving fish were randomly sacrificed at 24, 48, 72, 96 and 120 hr intervals for histological studies. At the end of the experiment, the six control fish were also sacrificed. Stomachs were fixed and processed for TEM.
Immunocytochemistrical Studies on Cytoskeletal Change in Cultured Cardiomyocyte of Tilapia
Authors: Tung L C 
Published: July 2020

Abstract
In the present study, the myofibril regeneration in the long-term cultured fish cardiomyocytes was studied with immunocytochemistry.
Adult Tilapia heart was dissociated into a single-cell suspension with collagenase and protease-minced tissue method. The culture medium was Eagle's minimal essential medium (MEM) with Earle's salts, supplemented with 10% fetal calf serum, 1 x nonessential amino acid mixture, 100 IU/ml penicillin G, and 100 μg/ml streptomycin. The cultured cells were grown in a humidified CO2 incubator at 28°Cand in a medium without glutamine for eliminating fibroblast contamination. In the initial 24 h culture, the elongated-shape cells gradually shortened from their both ends and rounded up. Over 5 to 6 days postcultivation, the cells attached to the bottom of the culture flask and began to protrude pseudopodia. The cells could not be subcultured and also proliferated indefinitely. The life span of cells in culture was 30 to 60 days.