This article reports the microstructural characteristics of various petroleum and pitch based nuclear graphites (IG-110, NBG-18, and PCEA) that are of interest to the next generation nuclear plant program. Bright-field transmission electron microscopy imaging was used to identify and understand the different features constituting the microstructure of nuclear graphite such as the filler particles, microcracks, binder phase, rosette-shaped quinoline insoluble (QI) particles, chaotic structures, and turbostratic graphite phase. The dimensions of microcracks were found to vary from a few nanometers to tens of microns. Furthermore, the microcracks were found to be filled with amorphous carbon of unknown origin. The pitch coke based graphite (NBG-18) was found to contain higher concentration of binder phase constituting QI particles as well as chaotic structures. The turbostratic graphite, present in all of the grades, was identified through their elliptical diffraction patterns. The difference in the microstructure has been analyzed in view of their processing conditions.

The current hypothesis of alveolar capillary membrane dysfunction fails to completely explain the severe and persistent leak of protein-rich fluid into the pulmonary interstitium, seen in the exudative phase of acute lung injury (ALI). The presence of intact red blood cells in the pulmonary interstitium may suggest mechanical failure of pulmonary arterioles and venules. These studies involved the pathological and ultrastructural evaluation of the pulmonary vasculature in Staphylococcal enterotoxin B (SEB)-induced ALI. Administration of SEB resulted in a significant increase in the protein concentration of bronchoalveolar lavage fluid and vascular leak in SEB-exposed mice compared to vehicle-treated mice. In vivo imaging of mice demonstrated the pulmonary edema and leakage in the lungs of SEB-administered mice. The histopathological studies showed intense clustering of inflammatory cells around the alveolar capillaries with subtle changes in architecture. Electron microscopy studies further confirmed the diffuse damage and disruption in the muscularis layer of the terminal vessels. Cell death in the endothelial cells of the terminal vessels was confirmed with TUNEL staining. In this study, we demonstrated that in addition to failure of the alveolar capillary membrane, disruption of the pulmonary arterioles and venules may explain the persistent and severe interstitial and alveolar edema.

Diabetes is a major health problem with an alarming increasing prevalence, and is the most frequent cause of neuropathy worldwide. Neuropathy affects 50–60% of diabetic patients, being a major life-quality impairment for a quarter of these patients. Diabetic neuropathic pain (DNP) is characterized by spontaneous pain, mechanical hyperalgesia and tactile allodynia and is accompanied by functional and neurochemical changes at the peripheral nerves, spinal cord and supraspinal pain control areas. Regarding the effects of diabetic neuropathy in the central somatossensory system, it was shown that streptozotocin (STZ)-diabetic rats present spontaneous hyperactivity and hyperexcitability of spinal nociceptive neurons, which may be subserving the exacerbated pain responses. The spinal functional changes and pain may be due to increased peripheral input(2), changes in spinal nociceptive modulatory mechanisms and altered supraspinal descending pain modulation. Noradrenergic descending pain modulation seems to be impaired since STZ-diabetic rats present decreased numbers of noradrenergic neurons at the A5 and A7 pontine cell groups, along with lower levels of noradrenaline at the spinal cord and higher behavioral responses to pain. This is consistent with the strong noradrenergic projection from A5 and A7 neurons to the spinal dorsal horn and the modulation of nociceptive transmission by local release of noradrenaline. The mechanisms underlying the decrease in noradrenergic neurons in the brainstem during diabetes remain unclear. Our recent findings that diabetes induces oxidative stress damage in neurons from those areas, lead us to hypothesize that it may contribute to their loss. Thereafter, with the present study we aimed to evaluate the effects of Epigallocathechin Gallate (EGCG), a potent antioxidant present in green tea, on spinal noradrenaline levels, on A5 and A7 noradrenergic neurons and on behavioral pain responses of STZ-diabetic rats.

The Monte Carlo software CASINO has been expanded with new modules for the simulation of complex beam scanning patterns, for the simulation of cathodoluminescence (CL), and for the calculation of electron energy deposition in subregions of a three-dimensional (3D) volume. Two examples are presented of the application of these new capabilities of CASINO. First, the CL emission near threading dislocations in gallium nitride (GaN) was modeled. The CL emission simulation of threading dislocations in GaN demonstrated that a better signal-to-noise ratio was obtained with lower incident electron energy than with higher energy. Second, the capability to simulate the distribution of the deposited energy in 3D was used to determine exposure parameters for polymethylmethacrylate resist using electron-beam lithography (EBL). The energy deposition dose in the resist was compared for two different multibeam EBL schemes by changing the incident electron energy.

Diabetes is an increasing public health problem that is expected to escalate in the future due to the growing incidence of obesity in the western world. While this disease is well known for its devastating effects on the kidneys and vascular system, diabetic individuals can develop cardiac dysfunction, termed diabetic cardiomyopathy, in the absence of other cardiovascular risk factors such as hypertension or atherosclerosis. While much effort has gone into understanding the effects of elevated glucose or altered insulin sensitivity on cellular components within the heart, significant changes in the cardiac extracellular matrix (ECM) have also been noted. In this review article we highlight what is currently known regarding the effects diabetes has on both the expression and chemical modification of proteins within the ECM and how the fibrotic response often observed as a consequence of this disease can contribute to reduced cardiac function.

In prior research, specimen holders that employ a novel MEMS-based heating technology (AduroTM) provided by Protochips Inc. (Raleigh, NC, USA) have been shown to permit sub-Ångström imaging at elevated temperatures up to 1,000°C during in situ heating experiments in modern aberration-corrected electron microscopes. The Aduro heating devices permit precise control of temperature and have the unique feature of providing both heating and cooling rates of 106°C/s. In the present work, we describe the recent development of a new specimen holder that incorporates the Aduro heating device into a “closed-cell” configuration, designed to function within the narrow (2 mm) objective lens pole piece gap of an aberration-corrected JEOL 2200FS STEM/TEM, and capable of exposing specimens to gases at pressures up to 1 atm. We show the early results of tests of this specimen holder demonstrating imaging at elevated temperatures and at pressures up to a full atmosphere, while retaining the atomic resolution performance of the microscope in high-angle annular dark-field and bright-field imaging modes.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Male, wild-type, FVB strain mice were fed a nutritionally complete liquid diet supplemented with 4% ethanol v/v over a time course of 1, 2, 4, 8, 12, and 14 weeks. Controls were offered an isocaloric liquid equivalent and pair fed with their ethanol counterparts. Changes in cardiac physiology were assessed at respective time points via echocardiography. Additionally, the use of histological techniques, mRNA analysis, apoptosis determination, and immunohistochemistry were employed to determine the functional and structural changes on the heart. Echocardiograph analysis revealed a compensatory phase that occurred early in the time course (1–8 weeks) and decompensation reverting toward heart failure at weeks 12 and 14. Throughout the study, an increase in cardiomyocyte hypertrophy, cardiac fibrosis, apoptosis, TGF-β, and the presence of α-SMA-positive cells were determined. A compensatory period in mice treated with ethanol occurred early followed by a transition to a dilated phenotype over time. A number of factors may be involved in this process including the activation of myofibroblasts and their fibrotic activities that is correlated with the presence of transforming growth factor beta.

The high beam current and subangstrom resolution of aberration-corrected scanning transmission electron microscopes has enabled electron energy loss spectroscopy (EELS) mapping with atomic resolution. These spectral maps are often dose limited and spatially oversampled, leading to low counts/channel and are thus highly sensitive to errors in background estimation. However, by taking advantage of redundancy in the dataset map, one can improve background estimation and increase chemical sensitivity. We consider two such approaches—linear combination of power laws and local background averaging—that reduce background error and improve signal extraction. Principal component analysis (PCA) can also be used to analyze spectrum images, but the poor peak-to-background ratio in EELS can lead to serious artifacts if raw EELS data are PCA filtered. We identify common artifacts and discuss alternative approaches. These algorithms are implemented within the Cornell Spectrum Imager, an open source software package for spectroscopic analysis.

Cardiovascular diseases (CVD) constitute a leading cause of death in the aged population. Regular intake of hyperlipidic diet and obesity can induce endothelial dysfunction that precedes the onset of atherosclerosis and CVD. High-fat diet regular consumption leads to structural modifications in heart tissue, and changes in the expression of angiogenic factors and their specific receptors. Hence, we aimed to characterize the expression pattern of vascular endothelial growth factor (VEGF) and its membrane receptor VEGFR 2 in young and aged rat hearts under high-fat diet and energy restriction.

In this article the Cu-Au binding energy in Cu3Au is determined by comparing experimental atom probe tomography (APT) results to simulations. The resulting bonding energy is supported by density functional theory calculations. The APT simulations are based on the Müller-Schottky equation, which is modified to include different atomic neighborhoods and their characteristic bonds. The local environment is considered up to the fifth next nearest neighbors. To compare the experimental with simulated APT data, the AtomVicinity algorithm, which provides statistical information about the positions of the neighboring atoms, is applied. The quality of this information is influenced by the field evaporation behavior of the different species, which is connected to the bonding energies.

BaFCl:Sm3+ is an efficient photoluminescent storage phosphor for ionizing radiation. Cathodoluminescence (CL) microanalysis enables the Sm2+ and Sm3+ oxidation states of samarium doped BaFCl to be easily identified, provides information about electron-beam and X-ray induced modification of BaFCl:Sm, and enables the synthesis dependent spatial distribution of samarium dopants of <100 ppm concentration to be determined with sub-100 nm resolution at 295 K. CL spectroscopy of BaFCl:Sm particles reveals broad CL emissions at ∼360 and ∼500 nm associated with Vk(Cl−) and oxygen-vacancy defects in the BaFCl host lattice and fine structure CL emissions associated with major 4GJ → 6HJ (Sm3+) and 5DJ → 7FJ (Sm2+) transitions. CL microanalysis shows samarium dopants are uniformly distributed in conventional sintered microcrystalline BaFCl:Sm. In contrast, CL investigations reveal that for BaFCl:Sm nanoparticles, which have been prepared using a co-precipitation method, with greatly improved Sm3+ → Sm2+ conversion efficiency, the samarium dopants are concentrated near the particle surface resulting in a BaFCl:Sm3+ shell surrounding the BaFCl core, which is stable to energetic irradiation.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

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The aim was to study the effect of solvents on the phase separation of four commercial dental adhesives. Four materials were tested: ClearfilTM SE Bond (CSE), Clearfil Protect Bond (CPB), Clearfil S3 Bond (CS3), and One-Up Bond F Plus (OUB). Distilled water or ethanol was used as a solvent (30 vol%) for microphase separation studies, by stereoscopy. For nanophase images, the mixtures were formulated with two different solvent concentrations (2.5 versus 5 vol%) and observed by atomic force microscopy. Images were analyzed by using MacBiophotonics ImageJ to measure the area of bright domains. Macrophase separations, identified as a loss of clarity, were only observed after mixing the adhesives with water. Nanophase separations were detected with all adhesive combinations. The area of bright domains ranged from 132 to 1,145 nm2 for CSE, from 15 to 285 nm2 for CPB, from 149 to 380 nm2 for CS3, and from 26 to 157 nm2 for OUB. In water-resins mixtures, CPB was the most homogeneous and OUB showed the most heterogeneous phase formation. In ethanol-resin mixtures, CSE attained the most homogeneous structure and OUB showed the most heterogeneous phase. Addition of 5 vol% ethanol to resins decreased the nanophase separation when compared with the control materials.

Myofibroblasts are differentiated fibroblasts that hold a key role in wound healing and remodeling following myocardial infarction (MI). A large repertoire of stimuli, such as mechanical stretch, growth factors, cytokines, and vasoactive peptides, induces myofibroblast differentiation. Myofibroblasts are responsible for the production and deposition of collagen, leading to the establishment of a dense extracellular matrix that strengthens the infarcted tissue and minimizes dilatation of the infarct area. In addition, cells contributing to fibrosis act on sites distal from the infarct area and promote collagen deposition in noninfarcted tissue, thus contributing to adverse remodeling and consequently to the development of congestive heart failure (CHF). Current drugs that are used to treat post-MI CHF do influence fibroblasts and myofibroblasts; however, their therapeutic efficacy is far from being regarded as ideal. Novel therapeutic agents targeting (myo)fibroblasts are being developed to successfully prevent the cardiac remodeling of sites remote from the infarct area and therefore hinder the establishment of CHF. The purpose of this review article is to discuss the basic concepts of the myofibroblasts' actions in cardiac wound healing processes, factors that influence them, currently available pharmacological agents, and future challenges in this area.

The cardiac extracellular matrix (ECM) is the three-dimensional scaffold that defines the geometry and muscular architecture of the cardiac chambers and transmits forces produced during the cardiac cycle throughout the heart wall. The cardiac ECM is an active system that responds to the stresses to which it is exposed and in the normal heart is adapted to facilitate efficient mechanical function. There are marked differences in the short- and medium-term changes in ventricular geometry and cardiac ECM that occur as a result of volume overload, hypertension, and ischemic cardiomyopathy. Despite this, there is a widespread view that a common remodeling “phenotype” governs the final progression to end-stage heart failure in different forms of heart disease. In this review article, we make the case that this interpretation is not consistent with the clinical and experimental data on the topic. We argue that there is a need for new theoretical and experimental models that will enable stresses acting on the ECM and resultant deformations to be estimated more accurately and provide better spatial resolution of local signaling mechanisms that are activated as a result. These developments are necessary to link the effects of structural remodeling with altered cardiac mechanical function.

Recent developments in the technology of laser-pulsed local-electrode atom-probe (LEAP) tomography include a picosecond ultraviolet (UV) laser system having a 355 nm wavelength and both external and in-vacuum optics. This approach ensures focusing of the laser beam to a smaller spot diameter than has heretofore been obtained using a green (532 nm wavelength) picosecond laser. We compare the mass spectra acquired, using either green or UV laser pulsing, from nickel-based superalloy specimens prepared either electrochemically or by lifting-out from bulk material using ion-beam milling in a dual-beam focused ion beam microscope. The utilization of picosecond UV laser pulsing yields improved mass spectra, which manifests itself in higher signal-to-noise ratios and mass-resolving power (m/Δm) in comparison to green laser pulsing. We employ LEAP tomography to investigate the formation of misoriented defects in nickel-based superalloys and demonstrate that UV laser pulsing yields better accuracy in compositional quantification than does green laser pulsing. Furthermore, we show that using a green laser the quality of mass spectra collected from specimens that were lifted-out by ion milling is usually poorer than for electrochemically-sharpened specimens. Employing UV laser pulsing yields, however, improved mass spectra in comparison to green laser pulsing even for ion-milled microtips.

TEAM I is the final product of the Transmission Electron Aberration-corrected Microscope (TEAM) Project, a collaborative project funded by the Department of Energy with the goal of designing and building a platform for a next generation aberration-corrected electron microscope capable of image resolution of up to 50 pm. The TEAM instrument incorporates a number of new technologies, including spherical- and chromatic-aberration correction, an all-piezo-electric sample stage and an active-pixel direct electron detector. This article describes the functionality of this advanced instrumentation, its response to changes in environment or operating conditions, and its stability during daily operation within the National Center for Electron Microscopy user facility.