Microstructure of milk

USDA-ARS?s Scientific Manuscript database

The fat and protein in milk may be examined by scanning electron microscopy, transmission electron microscopy, and confocal laser scanning microscopy, and any bacteria present may be viewed by light microscopy. The fat exists as globules, the bulk of the protein is in the form of casein micelles, a...

Towards native-state imaging in biological context in the electron microscope

PubMed Central

Weston, Anne E.; Armer, Hannah E. J.

2009-01-01

Modern cell biology is reliant on light and fluorescence microscopy for analysis of cells, tissues and protein localisation. However, these powerful techniques are ultimately limited in resolution by the wavelength of light. Electron microscopes offer much greater resolution due to the shorter effective wavelength of electrons, allowing direct imaging of sub-cellular architecture. The harsh environment of the electron microscope chamber and the properties of the electron beam have led to complex chemical and mechanical preparation techniques, which distance biological samples from their native state and complicate data interpretation. Here we describe recent advances in sample preparation and instrumentation, which push the boundaries of high-resolution imaging. Cryopreparation, cryoelectron microscopy and environmental scanning electron microscopy strive to image samples in near native state. Advances in correlative microscopy and markers enable high-resolution localisation of proteins. Innovation in microscope design has pushed the boundaries of resolution to atomic scale, whilst automatic acquisition of high-resolution electron microscopy data through large volumes is finally able to place ultrastructure in biological context. PMID:19916039

Hybrid fluorescence and electron cryo-microscopy for simultaneous electron and photon imaging.

PubMed

Iijima, Hirofumi; Fukuda, Yoshiyuki; Arai, Yoshihiro; Terakawa, Susumu; Yamamoto, Naoki; Nagayama, Kuniaki

2014-01-01

Integration of fluorescence light and transmission electron microscopy into the same device would represent an important advance in correlative microscopy, which traditionally involves two separate microscopes for imaging. To achieve such integration, the primary technical challenge that must be solved regards how to arrange two objective lenses used for light and electron microscopy in such a manner that they can properly focus on a single specimen. To address this issue, both lateral displacement of the specimen between two lenses and specimen rotation have been proposed. Such movement of the specimen allows sequential collection of two kinds of microscopic images of a single target, but prevents simultaneous imaging. This shortcoming has been made up by using a simple optical device, a reflection mirror. Here, we present an approach toward the versatile integration of fluorescence and electron microscopy for simultaneous imaging. The potential of simultaneous hybrid microscopy was demonstrated by fluorescence and electron sequential imaging of a fluorescent protein expressed in cells and cathodoluminescence imaging of fluorescent beads. Copyright © 2013 Elsevier Inc. All rights reserved.

Applications of microscopy to genetic therapy of cystic fibrosis and other human diseases.

PubMed

Moninger, Thomas O; Nessler, Randy A; Moore, Kenneth C

2006-01-01

Gene therapy has become an extremely important and active field of biomedical research. Microscopy is an integral component of this effort. This chapter presents an overview of imaging techniques used in our facility in support of cystic fibrosis gene therapy research. Instrumentation used in these studies includes light and confocal microscopy, transmission electron microscopy, and scanning electron microscopy. Techniques outlined include negative staining, cryo-electron microscopy, three-dimentional reconstruction, enzyme cytochemistry, immunocytochemistry, and fluorescence imaging.

Use of light, scanning electron microscopy and bioassays to evaluate parasitism by entomopathogenic fungi of the red scale insect of palms (Phoenicococcus marlatti Ckll., 1899).

PubMed

Asensio, L; Lopez-Llorca, L V; López-Jiménez, J A

2005-01-01

We have evaluated the parasitism of the red scale insect of the date palm (Phoenicococcus marlatti) by entomopathogenic fungi, using light microscopy (LM), scanning electron microscopy (SEM) and low temperature scanning electron microscopy (LTSEM). Beauveria bassiana, Lecanicillium dimorphum and Lecanicillium cf. psalliotae, were inoculated directly on the scale insects or on insect infested plant material. We found that L. dimorphum and L. cf. psalliotae developed on plant material and on scale insects, making infection structures. B. bassiana was a bad colonizer of date palm leaves (Phoenix dactylifera L.) and did not parasite the scale insects.

Correlative Light- and Electron Microscopy Using Quantum Dot Nanoparticles.

PubMed

Killingsworth, Murray C; Bobryshev, Yuri V

2016-08-07

A method is described whereby quantum dot (QD) nanoparticles can be used for correlative immunocytochemical studies of human pathology tissue using widefield fluorescence light microscopy and transmission electron microscopy (TEM). To demonstrate the protocol we have immunolabeled ultrathin epoxy sections of human somatostatinoma tumor using a primary antibody to somatostatin, followed by a biotinylated secondary antibody and visualization with streptavidin conjugated 585 nm cadmium-selenium (CdSe) quantum dots (QDs). The sections are mounted on a TEM specimen grid then placed on a glass slide for observation by widefield fluorescence light microscopy. Light microscopy reveals 585 nm QD labeling as bright orange fluorescence forming a granular pattern within the tumor cell cytoplasm. At low to mid-range magnification by light microscopy the labeling pattern can be easily recognized and the level of non-specific or background labeling assessed. This is a critical step for subsequent interpretation of the immunolabeling pattern by TEM and evaluation of the morphological context. The same section is then blotted dry and viewed by TEM. QD probes are seen to be attached to amorphous material contained in individual secretory granules. Images are acquired from the same region of interest (ROI) seen by light microscopy for correlative analysis. Corresponding images from each modality may then be blended to overlay fluorescence data on TEM ultrastructure of the corresponding region.

Neurite density from magnetic resonance diffusion measurements at ultrahigh field: Comparison with light microscopy and electron microscopy

PubMed Central

Jespersen, Sune N.; Bjarkam, Carsten R.; Nyengaard, Jens R.; Chakravarty, M. Mallar; Hansen, Brian; Vosegaard, Thomas; Østergaard, Leif; Yablonskiy, Dmitriy; Nielsen, Niels Chr.; Vestergaard-Poulsen, Peter

2010-01-01

Due to its unique sensitivity to tissue microstructure, diffusion-weighted magnetic resonance imaging (MRI) has found many applications in clinical and fundamental science. With few exceptions, a more precise correspondence between physiological or biophysical properties and the obtained diffusion parameters remain uncertain due to lack of specificity. In this work, we address this problem by comparing diffusion parameters of a recently introduced model for water diffusion in brain matter to light microscopy and quantitative electron microscopy. Specifically, we compare diffusion model predictions of neurite density in rats to optical myelin staining intensity and stereological estimation of neurite volume fraction using electron microscopy. We find that the diffusion model describes data better and that its parameters show stronger correlation with optical and electron microscopy, and thus reflect myelinated neurite density better than the more frequently used diffusion tensor imaging (DTI) and cumulant expansion methods. Furthermore, the estimated neurite orientations capture dendritic architecture more faithfully than DTI diffusion ellipsoids. PMID:19732836

High-resolution imaging by scanning electron microscopy of semithin sections in correlation with light microscopy.

PubMed

Koga, Daisuke; Kusumi, Satoshi; Shodo, Ryusuke; Dan, Yukari; Ushiki, Tatsuo

2015-12-01

In this study, we introduce scanning electron microscopy (SEM) of semithin resin sections. In this technique, semithin sections were adhered on glass slides, stained with both uranyl acetate and lead citrate, and observed with a backscattered electron detector at a low accelerating voltage. As the specimens are stained in the same manner as conventional transmission electron microscopy (TEM), the contrast of SEM images of semithin sections was similar to TEM images of ultrathin sections. Using this technique, wide areas of semithin sections were also observed by SEM, without the obstruction of grids, which was inevitable for traditional TEM. This study also applied semithin section SEM to correlative light and electron microscopy. Correlative immunofluorescence microscopy and immune-SEM were performed in semithin sections of LR white resin-embedded specimens using a FluoroNanogold-labeled secondary antibody. Because LR white resin is hydrophilic and electron stable, this resin is suitable for immunostaining and SEM observation. Using correlative microscopy, the precise localization of the primary antibody was demonstrated by fluorescence microscopy and SEM. This method has great potential for studies examining the precise localization of molecules, including Golgi- and ER-associated proteins, in correlation with LM and SEM. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Corneal collagen cross-linking: a confocal, electron, and light microscopy study of eye bank corneas.

PubMed

Dhaliwal, Jasmeet S; Kaufman, Stephen C

2009-01-01

The purpose of this study was to evaluate morphological changes induced by corneal collagen cross-linking in a human ex vivo cornea, using confocal, electron, and light microscopy. The central epithelium was partially removed from ex vivo human corneal buttons. Riboflavin 0.1% solution was applied before ultraviolet A light treatment and then for every 2 minutes for 30 minutes while the corneas were exposed to ultraviolet A light at a wavelength of 370 nm and intensity of 3 mW/cm(2). Each cornea was evaluated using confocal, electron, and light microscopy. Confocal microscopy demonstrated normal-appearing corneas on their initial pretreatment examination, with reduced stromal detail. After treatment, a superficial layer of highly reflective spherical structures (4-10 microm) was observed. Many of these hyperreflective structures appeared up to a depth of 300 microm. The remainder of the corneal stroma and endothelium appeared normal. Electron microscopy showed keratocyte apoptotic changes to a depth of 300 microm. No observable pathologic changes were seen on histology. Based on clinical studies, corneal cross-linking is a promising treatment that appears to be safe and to halt ectatic corneal disease progression. Initial European studies used animal models to extrapolate human protocols. In conjunction with clinical studies, we believe that human ex vivo corneal studies provide a means to evaluate the structural and morphological changes associated with this procedure, within human corneas, in a manner that cannot be accomplished in vivo.

Diffraction and microscopy with attosecond electron pulse trains

NASA Astrophysics Data System (ADS)

Morimoto, Yuya; Baum, Peter

2018-03-01

Attosecond spectroscopy1-7 can resolve electronic processes directly in time, but a movie-like space-time recording is impeded by the too long wavelength ( 100 times larger than atomic distances) or the source-sample entanglement in re-collision techniques8-11. Here we advance attosecond metrology to picometre wavelength and sub-atomic resolution by using free-space electrons instead of higher-harmonic photons1-7 or re-colliding wavepackets8-11. A beam of 70-keV electrons at 4.5-pm de Broglie wavelength is modulated by the electric field of laser cycles into a sequence of electron pulses with sub-optical-cycle duration. Time-resolved diffraction from crystalline silicon reveals a < 10-as delay of Bragg emission and demonstrates the possibility of analytic attosecond-ångström diffraction. Real-space electron microscopy visualizes with sub-light-cycle resolution how an optical wave propagates in space and time. This unification of attosecond science with electron microscopy and diffraction enables space-time imaging of light-driven processes in the entire range of sample morphologies that electron microscopy can access.

Comparative morphology of zebra (Dreissena polymorpha) and quagga (Dreissena bugensis) mussel sperm: Light and electron microscopy

USGS Publications Warehouse

Walker, G.K.; Black, M.G.; Edwards, C.A.

1996-01-01

Adult zebra (Dreissena polymorpha) and quagga (Dreissena bugensis) mussels were induced to release large quantities of live spermatozoa by the administration of 5-hydroxytryptamine (serotonin). Sperm were photographed alive using phase-contrast microscopy and were fixed subsequently with glutaraldehyde followed by osmium tetroxide for eventual examination by transmission or scanning electron microscopy. The sperm of both genera are of the ect-aquasperm type. Their overall dimensions and shape allow for easy discrimination at the light and scanning electron microscopy level. Transmission electron microscopy of the cells reveals a barrel-shaped nucleus in zebra mussel sperm and an elongated nucleus in quagga mussel sperm. In both species, an acrosome is cradled in a nuclear fossa. The ultrastructure of the acrosome and axial body, however, is distinctive for each species. The structures of the midpiece are shown, including a unique mitochondrial "skirt" that includes densely packed parallel cristae and extends in a narrow sheet from the mitochondria.

Advances in high-resolution imaging--techniques for three-dimensional imaging of cellular structures.

PubMed

Lidke, Diane S; Lidke, Keith A

2012-06-01

A fundamental goal in biology is to determine how cellular organization is coupled to function. To achieve this goal, a better understanding of organelle composition and structure is needed. Although visualization of cellular organelles using fluorescence or electron microscopy (EM) has become a common tool for the cell biologist, recent advances are providing a clearer picture of the cell than ever before. In particular, advanced light-microscopy techniques are achieving resolutions below the diffraction limit and EM tomography provides high-resolution three-dimensional (3D) images of cellular structures. The ability to perform both fluorescence and electron microscopy on the same sample (correlative light and electron microscopy, CLEM) makes it possible to identify where a fluorescently labeled protein is located with respect to organelle structures visualized by EM. Here, we review the current state of the art in 3D biological imaging techniques with a focus on recent advances in electron microscopy and fluorescence super-resolution techniques.

Correlated fluorescence microscopy and cryo-electron tomography of virus-infected or transfected mammalian cells

PubMed Central

Hampton, Cheri M; Strauss, Joshua D; Ke, Zunlong; Dillard, Rebecca S; Hammonds, Jason E; Alonas, Eric; Desai, Tanay M; Marin, Mariana; Storms, Rachel E; Leon, Fredrick; Melikyan, Gregory B; Santangelo, Philip J; Spearman, Paul W; Wright, Elizabeth R

2016-01-01

Correlative light and electron microscopy (CLEM) combines spatiotemporal information from fluorescence light microscopy (fLM) with high-resolution structural data from cryo-electron tomography (cryo-ET). These technologies provide opportunities to bridge knowledge gaps between cell and structural biology. Here we describe our protocol for correlated cryo-fLM, cryo-electron microscopy (cryo-EM), and cryo-ET (i.e., cryo-CLEM) of virus-infected or transfected mammalian cells. Mammalian-derived cells are cultured on EM substrates, using optimized conditions that ensure that the cells are spread thinly across the substrate and are not physically disrupted. The cells are then screened by fLM and vitrified before acquisition of cryo-fLM and cryo-ET images, which is followed by data processing. A complete session from grid preparation through data collection and processing takes 5–15 d for an individual experienced in cryo-EM. PMID:27977021

Electronic Blending in Virtual Microscopy

ERIC Educational Resources Information Center

Maybury, Terrence S.; Farah, Camile S.

2010-01-01

Virtual microscopy (VM) is a relatively new technology that transforms the computer into a microscope. In essence, VM allows for the scanning and transfer of glass slides from light microscopy technology to the digital environment of the computer. This transition is also a function of the change from print knowledge to electronic knowledge, or as…

Structural and Ultrastructural Characteristics of Bone-Tendon Junction of the Calcaneal Tendon of Adult and Elderly Wistar Rats

PubMed Central

Cury, Diego Pulzatto; Dias, Fernando José; Miglino, Maria Angélica; Watanabe, Ii-sei

2016-01-01

Tendons are transition tissues that transfer the contractile forces generated by the muscles to the bones, allowing movement. The region where the tendon attaches to the bone is called bone-tendon junction or enthesis and may be classified as fibrous or fibrocartilaginous. This study aims to analyze the collagen fibers and the cells present in the bone-tendon junction using light microscopy and ultrastructural techniques as scanning electron microscopy and transmission electron microscopy. Forty male Wistar rats were used in the experiment, being 20 adult rats at 4 months-old and 20 elderly rats at 20 months-old. The hind limbs of the rats were removed, dissected and prepared to light microscopy, transmission electron microscopy and scanning electron microscopy. The aging process showed changes in the collagen fibrils, with a predominance of type III fibers in the elderly group, in addition to a decrease in the amount of the fibrocartilage cells, fewer and shorter cytoplasmic processes and a decreased synthetic capacity due to degradation of the organelles involved in synthesis. PMID:27078690

Preservation of protein fluorescence in embedded human dendritic cells for targeted 3D light and electron microscopy

PubMed Central

HÖHN, K.; FUCHS, J.; FRÖBER, A.; KIRMSE, R.; GLASS, B.; ANDERS‐ÖSSWEIN, M.; WALTHER, P.; KRÄUSSLICH, H.‐G.

2015-01-01

Summary In this study, we present a correlative microscopy workflow to combine detailed 3D fluorescence light microscopy data with ultrastructural information gained by 3D focused ion beam assisted scanning electron microscopy. The workflow is based on an optimized high pressure freezing/freeze substitution protocol that preserves good ultrastructural detail along with retaining the fluorescence signal in the resin embedded specimens. Consequently, cellular structures of interest can readily be identified and imaged by state of the art 3D confocal fluorescence microscopy and are precisely referenced with respect to an imprinted coordinate system on the surface of the resin block. This allows precise guidance of the focused ion beam assisted scanning electron microscopy and limits the volume to be imaged to the structure of interest. This, in turn, minimizes the total acquisition time necessary to conduct the time consuming ultrastructural scanning electron microscope imaging while eliminating the risk to miss parts of the target structure. We illustrate the value of this workflow for targeting virus compartments, which are formed in HIV‐pulsed mature human dendritic cells. PMID:25786567

Structural and Ultrastructural Characteristics of Bone-Tendon Junction of the Calcaneal Tendon of Adult and Elderly Wistar Rats.

PubMed

Cury, Diego Pulzatto; Dias, Fernando José; Miglino, Maria Angélica; Watanabe, Ii-sei

2016-01-01

Tendons are transition tissues that transfer the contractile forces generated by the muscles to the bones, allowing movement. The region where the tendon attaches to the bone is called bone-tendon junction or enthesis and may be classified as fibrous or fibrocartilaginous. This study aims to analyze the collagen fibers and the cells present in the bone-tendon junction using light microscopy and ultrastructural techniques as scanning electron microscopy and transmission electron microscopy. Forty male Wistar rats were used in the experiment, being 20 adult rats at 4 months-old and 20 elderly rats at 20 months-old. The hind limbs of the rats were removed, dissected and prepared to light microscopy, transmission electron microscopy and scanning electron microscopy. The aging process showed changes in the collagen fibrils, with a predominance of type III fibers in the elderly group, in addition to a decrease in the amount of the fibrocartilage cells, fewer and shorter cytoplasmic processes and a decreased synthetic capacity due to degradation of the organelles involved in synthesis.

Grinding and polishing instead of sectioning for the tissue samples with a graft: Implications for light and electron microscopy.

PubMed

Mukhamadiyarov, Rinat A; Sevostyanova, Victoria V; Shishkova, Daria K; Nokhrin, Andrey V; Sidorova, Olga D; Kutikhin, Anton G

2016-06-01

A broad use of the graft replacement requires a detailed investigation of the host-graft interaction, including both histological examination and electron microscopy. A high quality sectioning of the host tissue with a graft seems to be complicated; in addition, it is difficult to examine the same tissue area by both of the mentioned microscopy techniques. To solve these problems, we developed a new technique of epoxy resin embedding with the further grinding, polishing, and staining. Graft-containing tissues prepared by grinding and polishing preserved their structure; however, sectioning frequently required the explantation of the graft and led to tissue disintegration. Moreover, stained samples prepared by grinding and polishing may then be assessed by both light microscopy and backscattered scanning electron microscopy. Therefore, grinding and polishing outperform sectioning when applied to the tissues with a graft. Copyright © 2016 Elsevier Ltd. All rights reserved.

Correlation of live-cell imaging with volume scanning electron microscopy.

PubMed

Lucas, Miriam S; Günthert, Maja; Bittermann, Anne Greet; de Marco, Alex; Wepf, Roger

2017-01-01

Live-cell imaging is one of the most widely applied methods in live science. Here we describe two setups for live-cell imaging, which can easily be combined with volume SEM for correlative studies. The first procedure applies cell culture dishes with a gridded glass support, which can be used for any light microscopy modality. The second approach is a flow-chamber setup based on Ibidi μ-slides. Both live-cell imaging strategies can be followed up with serial blockface- or focused ion beam-scanning electron microscopy. Two types of resin embedding after heavy metal staining and dehydration are presented making best use of the particular advantages of each imaging modality: classical en-bloc embedding and thin-layer plastification. The latter can be used only for focused ion beam-scanning electron microscopy, but is advantageous for studying cell-interactions with specific substrates, or when the substrate cannot be removed. En-bloc embedding has diverse applications and can be applied for both described volume scanning electron microscopy techniques. Finally, strategies for relocating the cell of interest are discussed for both embedding approaches and in respect to the applied light and scanning electron microscopy methods. Copyright © 2017 Elsevier Inc. All rights reserved.

Visualization of HIV T Cell Virological Synapses and Virus-Containing Compartments by Three-Dimensional Correlative Light and Electron Microscopy

PubMed Central

Wang, Lili; Eng, Edward T.; Law, Kenneth; Gordon, Ronald E.; Rice, William J.

2016-01-01

ABSTRACT Virological synapses (VS) are adhesive structures that form between infected and uninfected cells to enhance the spread of HIV-1. During T cell VS formation, viral proteins are actively recruited to the site of cell-cell contact where the viral material is efficiently translocated to target cells into heterogeneous, protease-resistant, antibody-inaccessible compartments. Using correlative light and electron microscopy (CLEM), we define the membrane topography of the virus-containing compartments (VCC) where HIV is found following VS-mediated transfer. Focused ion beam scanning electron microscopy (FIB-SEM) and serial sectioning transmission electron microscopy (SS-TEM) were used to better resolve the fluorescent Gag-containing structures within the VCC. We found that small punctate fluorescent signals correlated with single viral particles in enclosed vesicular compartments or surface-localized virus particles and that large fluorescent signals correlated with membranous Gag-containing structures with unknown pathological function. CLEM imaging revealed distinct pools of newly deposited viral proteins within endocytic and nonendocytic compartments in VS target T cells. IMPORTANCE This study directly correlates individual virus-associated objects observed in light microscopy with ultrastructural features seen by electron microscopy in the HIV-1 virological synapse. This approach elucidates which infection-associated ultrastructural features represent bona fide HIV protein complexes. We define the morphology of some HIV cell-to-cell transfer intermediates as true endocytic compartments and resolve unique synapse-associated viral structures created by transfer across virological synapses. PMID:27847357

Inducing fluorescence of uranyl acetate as a dual-purpose contrast agent for correlative light-electron microscopy with nanometre precision.

PubMed

Tuijtel, Maarten W; Mulder, Aat A; Posthuma, Clara C; van der Hoeven, Barbara; Koster, Abraham J; Bárcena, Montserrat; Faas, Frank G A; Sharp, Thomas H

2017-09-05

Correlative light-electron microscopy (CLEM) combines the high spatial resolution of transmission electron microscopy (TEM) with the capability of fluorescence light microscopy (FLM) to locate rare or transient cellular events within a large field of view. CLEM is therefore a powerful technique to study cellular processes. Aligning images derived from both imaging modalities is a prerequisite to correlate the two microscopy data sets, and poor alignment can limit interpretability of the data. Here, we describe how uranyl acetate, a commonly-used contrast agent for TEM, can be induced to fluoresce brightly at cryogenic temperatures (-195 °C) and imaged by cryoFLM using standard filter sets. This dual-purpose contrast agent can be used as a general tool for CLEM, whereby the equivalent staining allows direct correlation between fluorescence and TEM images. We demonstrate the potential of this approach by performing multi-colour CLEM of cells containing equine arteritis virus proteins tagged with either green- or red-fluorescent protein, and achieve high-precision localization of virus-induced intracellular membrane modifications. Using uranyl acetate as a dual-purpose contrast agent, we achieve an image alignment precision of ~30 nm, twice as accurate as when using fiducial beads, which will be essential for combining TEM with the evolving field of super-resolution light microscopy.

Focus on membrane differentiation and membrane domains in the prokaryotic cell.

PubMed

Boekema, Egbert J; Scheffers, Dirk-Jan; van Bezouwen, Laura S; Bolhuis, Henk; Folea, I Mihaela

2013-01-01

A summary is presented of membrane differentiation in the prokaryotic cell, with an emphasis on the organization of proteins in the plasma/cell membrane. Many species belonging to the Eubacteria and Archaea have special membrane domains and/or membrane proliferation, which are vital for different cellular processes. Typical membrane domains are found in bacteria where a specific membrane protein is abundantly expressed. Lipid rafts form another example. Despite the rareness of conventional organelles as found in eukaryotes, some bacteria are known to have an intricate internal cell membrane organization. Membrane proliferation can be divided into curvature and invaginations which can lead to internal compartmentalization. This study discusses some of the clearest examples of bacteria with such domains and internal membranes. The need for membrane specialization is highest among the heterogeneous group of bacteria which harvest light energy, such as photosynthetic bacteria and halophilic archaea. Most of the highly specialized membranes and domains, such as the purple membrane, chromatophore and chlorosome, are found in these autotrophic organisms. Otherwise the need for membrane differentiation is lower and variable, except for those structures involved in cell division. Microscopy techniques have given essential insight into bacterial membrane morphology. As microscopy will further contribute to the unraveling of membrane organization in the years to come, past and present technology in electron microscopy and light microscopy is discussed. Electron microscopy was the first to unravel bacterial morphology because it can directly visualize membranes with inserted proteins, which no other technique can do. Electron microscopy techniques developed in the 1950s and perfected in the following decades involve the thin sectioning and freeze fractioning of cells. Several studies from the golden age of these techniques show amazing examples of cell membrane morphology. More recently, light microscopy in combination with the use of fluorescent dyes has become an attractive technique for protein localization with the natural membrane. However, the resolution problem in light microscopy remains and overinterpretation of observed phenomena is a pitfall. Thus, light microscopy as a stand-alone technique is not sufficient to prove, for instance, the long-range helical distribution of proteins in membrane such as MinD spirals in Bacillus subtilis. Electron tomography is an emerging electron microscopy technique that can provide three-dimensional reconstructions of small, nonchemically fixed bacteria. It will become a useful tool for studying prokaryotic membranes in more detail and is expected to collect information complementary to those of advanced light microscopy. Together, microscopy techniques can meet the challenge of the coming years: to specify membrane structures in more detail and to bring them to the level of specific protein-protein interactions. Copyright © 2013 S. Karger AG, Basel.

Contributed review: Review of integrated correlative light and electron microscopy.

PubMed

Timmermans, F J; Otto, C

2015-01-01

New developments in the field of microscopy enable to acquire increasing amounts of information from large sample areas and at an increased resolution. Depending on the nature of the technique, the information may reveal morphological, structural, chemical, and still other sample characteristics. In research fields, such as cell biology and materials science, there is an increasing demand to correlate these individual levels of information and in this way to obtain a better understanding of sample preparation and specific sample properties. To address this need, integrated systems were developed that combine nanometer resolution electron microscopes with optical microscopes, which produce chemically or label specific information through spectroscopy. The complementary information from electron microscopy and light microscopy presents an opportunity to investigate a broad range of sample properties in a correlated fashion. An important part of correlating the differences in information lies in bridging the different resolution and image contrast features. The trend to analyse samples using multiple correlated microscopes has resulted in a new research field. Current research is focused, for instance, on (a) the investigation of samples with nanometer scale distribution of inorganic and organic materials, (b) live cell analysis combined with electron microscopy, and (c) in situ spectroscopic and electron microscopy analysis of catalytic materials, but more areas will benefit from integrated correlative microscopy.

Preservation of protein fluorescence in embedded human dendritic cells for targeted 3D light and electron microscopy.

PubMed

Höhn, K; Fuchs, J; Fröber, A; Kirmse, R; Glass, B; Anders-Össwein, M; Walther, P; Kräusslich, H-G; Dietrich, C

2015-08-01

In this study, we present a correlative microscopy workflow to combine detailed 3D fluorescence light microscopy data with ultrastructural information gained by 3D focused ion beam assisted scanning electron microscopy. The workflow is based on an optimized high pressure freezing/freeze substitution protocol that preserves good ultrastructural detail along with retaining the fluorescence signal in the resin embedded specimens. Consequently, cellular structures of interest can readily be identified and imaged by state of the art 3D confocal fluorescence microscopy and are precisely referenced with respect to an imprinted coordinate system on the surface of the resin block. This allows precise guidance of the focused ion beam assisted scanning electron microscopy and limits the volume to be imaged to the structure of interest. This, in turn, minimizes the total acquisition time necessary to conduct the time consuming ultrastructural scanning electron microscope imaging while eliminating the risk to miss parts of the target structure. We illustrate the value of this workflow for targeting virus compartments, which are formed in HIV-pulsed mature human dendritic cells. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Atomic force microscopic imaging of Acanthamoeba castellanii and Balamuthia mandrillaris trophozoites and cysts.

PubMed

Aqeel, Yousuf; Siddiqui, Ruqaiyyah; Ateeq, Muhammad; Raza Shah, Muhammad; Kulsoom, Huma; Khan, Naveed Ahmed

2015-01-01

Light microscopy and electron microscopy have been successfully used in the study of microbes, as well as free-living protists. Unlike light microscopy, which enables us to observe living organisms or the electron microscope which provides a two-dimensional image, atomic force microscopy provides a three-dimensional surface profile. Here, we observed two free-living amoebae, Acanthamoeba castellanii and Balamuthia mandrillaris under the phase contrast inverted microscope, transmission electron microscope and atomic force microscope. Although light microscopy was of lower magnification, it revealed functional biology of live amoebae such as motility and osmoregulation using contractile vacuoles of the trophozoite stage, but it is of limited value in defining the cyst stage. In contrast, transmission electron microscopy showed significantly greater magnification and resolution to reveal the ultra-structural features of trophozoites and cysts including intracellular organelles and cyst wall characteristics but it only produced a snapshot in time of a dead amoeba cell. Atomic force microscopy produced three-dimensional images providing detailed topographic description of shape and surface, phase imaging measuring boundary stiffness, and amplitude measurements including width, height and length of A. castellanii and B. mandrillaris trophozoites and cysts. These results demonstrate the importance of the application of various microscopic methods in the biological and structural characterization of the whole cell, ultra-structural features, as well as surface components and cytoskeleton of protist pathogens. © 2014 The Author(s) Journal of Eukaryotic Microbiology © 2014 International Society of Protistologists.

Quantum dot immunocytochemical localization of somatostatin in somatostatinoma by Widefield Epifluorescence, super-resolution light, and immunoelectron microscopy.

PubMed

Killingsworth, Murray C; Lai, Ken; Wu, Xiaojuan; Yong, Jim L C; Lee, C Soon

2012-11-01

Quantum dot nanocrystal probes (QDs) have been used for detection of somatostatin hormone in secretory granules of somatostatinoma tumor cells by immunofluorescence light microscopy, super-resolution light microscopy, and immunoelectron microscopy. Immunostaining for all modalities was done using sections taken from an epoxy resin-embedded tissue specimen and a similar labeling protocol. This approach allowed assessment of labeling at light microscopy level before examination at super-resolution and electron microscopy level and was a significant aid in interpretation. Etching of ultrathin sections with saturated sodium metaperiodate was a critical step presumably able to retrieve some tissue antigenicity masked by processing in epoxy resin. Immunofluorescence microscopy of QD-immunolabeled sections showed somatostatin hormone localization in cytoplasmic granules. Some variable staining of tumor gland-like structures appeared related to granule maturity and dispersal of granule contents within the tumor cell cytoplasm. Super-resolution light microscopy demonstrated localization of somatostatin within individual secretory granules to be heterogeneous, and this staining pattern was confirmed by immunoelectron microscopy.

Quantum Dot Immunocytochemical Localization of Somatostatin in Somatostatinoma by Widefield Epifluorescence, Super-resolution Light, and Immunoelectron Microscopy

PubMed Central

Lai, Ken; Wu, Xiaojuan; Yong, Jim L. C.; Lee, C. Soon

2012-01-01

Quantum dot nanocrystal probes (QDs) have been used for detection of somatostatin hormone in secretory granules of somatostatinoma tumor cells by immunofluorescence light microscopy, super-resolution light microscopy, and immunoelectron microscopy. Immunostaining for all modalities was done using sections taken from an epoxy resin-embedded tissue specimen and a similar labeling protocol. This approach allowed assessment of labeling at light microscopy level before examination at super-resolution and electron microscopy level and was a significant aid in interpretation. Etching of ultrathin sections with saturated sodium metaperiodate was a critical step presumably able to retrieve some tissue antigenicity masked by processing in epoxy resin. Immunofluorescence microscopy of QD-immunolabeled sections showed somatostatin hormone localization in cytoplasmic granules. Some variable staining of tumor gland-like structures appeared related to granule maturity and dispersal of granule contents within the tumor cell cytoplasm. Super-resolution light microscopy demonstrated localization of somatostatin within individual secretory granules to be heterogeneous, and this staining pattern was confirmed by immunoelectron microscopy. PMID:22899862

Ultrafast Imaging of Chiral Surface Plasmon by Photoemission Electron Microscopy

NASA Astrophysics Data System (ADS)

Dai, Yanan; Dabrowski, Maciej; Petek, Hrvoje

We employ Time-Resolved Photoemission Electron Microscopy (TR-PEEM) to study surface plasmon polariton (SPP) wave packet dynamics launched by tunable (VIS-UV) femtosecond pulses of various linear and circular polarizations. The plasmonic structures are micron size single-crystalline Ag islands grown in situ on Si surfaces and characterized by Low Energy Electron Microscopy (LEEM). The local fields of plasmonic modes enhance two and three photon photoemission (2PP and 3PP) at the regions of strong field enhancement. Imaging of the photoemission signal with PEEM electron optics thus images the plasmonic fields excited in the samples. The observed PEEM images with left and right circularly polarized light show chiral images, which is a consequence of the transverse spin momentum of surface plasmon. By changing incident light polarization, the plasmon interference pattern shifts with light ellipticity indicating a polarization dependent excitation phase of SPP. In addition, interferometric-time resolved measurements record the asymmetric SPP wave packet motion in order to characterize the dynamical properties of chiral SPP wave packets.

HANFORD WASTE MINERALOGY REFERENCE REPORT

DOE Office of Scientific and Technical Information (OSTI.GOV)

DISSELKAMP RS

2010-06-29

This report lists the observed mineral phases present in the Hanford tanks. This task was accomplished by performing a review of numerous reports that used experimental techniques including, but not limited to: x-ray diffraction, polarized light microscopy, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, electron energy loss spectroscopy, and particle size distribution analyses. This report contains tables that can be used as a quick reference to identify the crystal phases observed in Hanford waste.

HANFORD WASTE MINEROLOGY REFERENCE REPORT

DOE Office of Scientific and Technical Information (OSTI.GOV)

DISSELKAMP RS

2010-06-18

This report lists the observed mineral phase phases present in the Hanford tanks. This task was accomplished by performing a review of numerous reports using experimental techniques including, but not limited to: x-ray diffraction, polarized light microscopy, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, electron energy loss spectroscopy, and particle size distribution analyses. This report contains tables that can be used as a quick reference to identify the crystal phases present observed in Hanford waste.

Hierarchical super-structure identified by polarized light microscopy, electron microscopy and nanoindentation: Implications for the limits of biological control over the growth mode of abalone sea shells

PubMed Central

2012-01-01

Background Mollusc shells are commonly investigated using high-resolution imaging techniques based on cryo-fixation. Less detailed information is available regarding the light-optical properties. Sea shells of Haliotis pulcherina were embedded for polishing in defined orientations in order to investigate the interface between prismatic calcite and nacreous aragonite by standard materialographic methods. A polished thin section of the interface was prepared with a defined thickness of 60 μm for quantitative birefringence analysis using polarized light and LC-PolScope microscopy. Scanning electron microscopy images were obtained for comparison. In order to study structural-mechanical relationships, nanoindentation experiments were performed. Results Incident light microscopy revealed a super-structure in semi-transparent regions of the polished cross-section under a defined angle. This super-structure is not visible in transmitted birefringence analysis due to the blurred polarization of small nacre platelets and numerous organic interfaces. The relative orientation and homogeneity of calcite prisms was directly identified, some of them with their optical axes exactly normal to the imaging plane. Co-oriented "prism colonies" were identified by polarized light analyses. The nacreous super-structure was also visualized by secondary electron imaging under defined angles. The domains of the super-structure were interpreted to consist of crystallographically aligned platelet stacks. Nanoindentation experiments showed that mechanical properties changed with the same periodicity as the domain size. Conclusions In this study, we have demonstrated that insights into the growth mechanisms of nacre can be obtained by conventional light-optical methods. For example, we observed super-structures formed by co-oriented nacre platelets as previously identified using X-ray Photo-electron Emission Microscopy (X-PEEM) [Gilbert et al., Journal of the American Chemical Society 2008, 130:17519–17527]. Polarized optical microscopy revealed unprecedented super-structures in the calcitic shell part. This bears, in principle, the potential for in vivo studies, which might be useful for investigating the growth modes of nacre and other shell types. PMID:22967319

Quadriplegic areflexic ICU illness: selective thick filament loss and normal nerve histology.

PubMed

Sander, Howard W; Golden, Marianna; Danon, Moris J

2002-10-01

Areflexic quadriplegia that occurs in the intensive care unit (ICU) is commonly ascribed to critical illness polyneuropathy based upon electrophysiology or muscle light microscopy. However, electron microscopy often documents a selective thick filament loss myopathy. Eight ICU patients who developed areflexic quadriplegia underwent biopsy. Seven patients had received steroids, and 2 had also received paralytic agents. Electrodiagnostic studies revealed absent or low-amplitude motor responses in 7. Sensory responses were normal in 5 of 6 and absent in 1. Initial electromyography revealed absent (n = 3), small (n = 3), or polyphasic (n = 1) motor unit potentials, and diffuse fibrillation potentials (n = 5). In all 8, light microscopy of muscle revealed numerous atrophic-angulated fibers and corelike lesions, and electron microscopy revealed extensive thick filament loss. Morphology of sural and intramuscular nerves, and, in one autopsied case, of the obturator nerve and multiple nerve roots, was normal. Although clinical, electrodiagnostic, and light microscopic features mimicked denervating disease, muscle electron microscopy revealed thick filament loss, and nerve histology was normal. This suggests that areflexic ICU quadriplegia is a primary myopathy and not an axonal polyneuropathy. Copyright 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 499-505, 2002

Diagnostic electron microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dickersin, G.R.

1988-01-01

In this book the author presents a comprehensive reference text on diagnostic electron microscopy. Throughout the book he illustrates how ultrastructural identification can be helpful for the recognition of cell type and the identification of mechanisms of pathogenesis in various diseases. In addition to electron microscopy photographs, there are also numerous light microscopy photographs for comparison. This text presents the classification of neoplasms in the order and arrangement most familiar to the pathologist. Contents: Introduction; Diagram of a Normal Cell; Normal Cell Function; Embryology; Neoplasms; Infectious Agents; Metabolic Diseases; Renal Diseases; Skeletal Muscle and Peripheral Nerve Diseases; Index.

3D correlative light and electron microscopy of cultured cells using serial blockface scanning electron microscopy

PubMed Central

Lerner, Thomas R.; Burden, Jemima J.; Nkwe, David O.; Pelchen-Matthews, Annegret; Domart, Marie-Charlotte; Durgan, Joanne; Weston, Anne; Jones, Martin L.; Peddie, Christopher J.; Carzaniga, Raffaella; Florey, Oliver; Marsh, Mark; Gutierrez, Maximiliano G.

2017-01-01

ABSTRACT The processes of life take place in multiple dimensions, but imaging these processes in even three dimensions is challenging. Here, we describe a workflow for 3D correlative light and electron microscopy (CLEM) of cell monolayers using fluorescence microscopy to identify and follow biological events, combined with serial blockface scanning electron microscopy to analyse the underlying ultrastructure. The workflow encompasses all steps from cell culture to sample processing, imaging strategy, and 3D image processing and analysis. We demonstrate successful application of the workflow to three studies, each aiming to better understand complex and dynamic biological processes, including bacterial and viral infections of cultured cells and formation of entotic cell-in-cell structures commonly observed in tumours. Our workflow revealed new insight into the replicative niche of Mycobacterium tuberculosis in primary human lymphatic endothelial cells, HIV-1 in human monocyte-derived macrophages, and the composition of the entotic vacuole. The broad application of this 3D CLEM technique will make it a useful addition to the correlative imaging toolbox for biomedical research. PMID:27445312

In situ flat embedding of monolayers and cell relocation in the acrylic resin LR white for comparative light and electron microscopy studies.

PubMed

Steiner, M; Schöfer, C; Mosgoeller, W

1994-12-01

A simple and reliable method has been developed for the in situ LR White embedding of cell monolayers grown on glass cover-slips. Combined with cytochemical or immunological procedures, this technique allows light and/or electron microscopy investigations of a large number of cells in the same horizontal plane within a relatively short period of time. It can be applied to cells grown on microgrid finder cover-slips which allows a distinct site of even an individual cell of a monolayer to be studied at first at the light microscope level and subsequently at the electron microscope level. Hence, it is also suitable for controlling manipulation of single cells, followed by their serial sectioning after relocation in the electron microscope.

Visualization of Neutrophil Extracellular Traps and Fibrin Meshwork in Human Fibrinopurulent Inflammatory Lesions: III. Correlative Light and Electron Microscopic Study

PubMed Central

Onouchi, Takanori; Shiogama, Kazuya; Mizutani, Yasuyoshi; Takaki, Takashi; Tsutsumi, Yutaka

2016-01-01

Neutrophil extracellular traps (NETs) released from dead neutrophils at the site of inflammation represent webs of neutrophilic DNA stretches dotted with granule-derived antimicrobial proteins, including lactoferrin, and play important roles in innate immunity against microbial infection. We have shown the coexistence of NETs and fibrin meshwork in varied fibrinopurulent inflammatory lesions at both light and electron microscopic levels. In the present study, correlative light and electron microscopy (CLEM) employing confocal laser scanning microscopy and scanning electron microscopy was performed to bridge light and electron microscopic images of NETs and fibrin fibrils in formalin-fixed, paraffin-embedded, autopsied lung sections of legionnaire’s pneumonia. Lactoferrin immunoreactivity and 4'-6-diamidino-2-phenylindole (DAPI) reactivity were used as markers of NETs, and fibrin was probed by fibrinogen gamma chain. Of note is that NETs light microscopically represented as lactoferrin and DAPI-colocalized dots, 2.5 μm in diameter. CLEM gave super-resolution images of NETs and fibrin fibrils: “Dotted” NETs were ultrastructurally composed of fine filaments and masses of 58 nm-sized globular materials. A fibrin fibril consisted of clusters of smooth-surfaced filaments. NETs filaments (26 nm in diameter) were significantly thinner than fibrin filaments (295 nm in diameter). Of note is that CLEM was applicable to formalin-fixed, paraffin-embedded sections of autopsy material. PMID:27917008

Microwave Processing of Crowns from Winter Cereals for Light Microscopy.

USDA-ARS?s Scientific Manuscript database

Microwave processing of tissue considerably shortens the time it takes to prepare samples for light and electron microscopy. However, plant tissues from different species and different regions of the plant respond differently making it impossible to use a single protocol for all plant tissue. The ...

Nanocrystals of [Cu3(btc)2] (HKUST-1): a combined time-resolved light scattering and scanning electron microscopy study.

PubMed

Zacher, Denise; Liu, Jianing; Huber, Klaus; Fischer, Roland A

2009-03-07

The formation of [Cu(3)(btc)(2)] (HKUST-1; btc = 1,3,5-benzenetricarboxylate) nanocrystals from a super-saturated mother solution at room temperature was monitored by time-resolved light scattering (TLS); the system is characterized by a rapid growth up to a size limit of 200 nm within a few minutes, and the size and shape of the crystallites were also determined by scanning electron microscopy (SEM).

Correlative Light-Electron Microscopy of Lipid-Encapsulated Fluorescent Nanodiamonds for Nanometric Localization of Cell Surface Antigens.

PubMed

Hsieh, Feng-Jen; Chen, Yen-Wei; Huang, Yao-Kuan; Lee, Hsien-Ming; Lin, Chun-Hung; Chang, Huan-Cheng

2018-02-06

Containing an ensemble of nitrogen-vacancy centers in crystal matrices, fluorescent nanodiamonds (FNDs) are a new type of photostable markers that have found wide applications in light microscopy. The nanomaterial also has a dense carbon core, making it visible to electron microscopy. Here, we show that FNDs encapsulated in biotinylated lipids (bLs) are useful for subdiffraction imaging of antigens on cell surface with correlative light-electron microscopy (CLEM). The lipid encapsulation enables not only good dispersion of the particles in biological buffers but also high specific labeling of live cells. By employing the bL-encapsulated FNDs to target CD44 on HeLa cell surface through biotin-mediated immunostaining, we obtained the spatial distribution of these antigens by CLEM with a localization accuracy of ∼50 nm in routine operations. A comparative study with dual-color imaging, in which CD44 was labeled with FND and MICA/MICB was labeled with Alexa Fluor 488, demonstrated the superior performance of FNDs as fluorescent fiducial markers for CLEM of cell surface antigens.

A facile hydrothermal approach to synthesize rGO/BiVO4 photocatalysts for visible light induced degradation of RhB dye

NASA Astrophysics Data System (ADS)

Pal, Shreyasi; Dutta, Shibsankar; De, Sukanta

2018-05-01

RGO/BiVO4 composites were synthesized by a simple hydrothermal method. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) and surface analysis (BET). The photocatalytic activity of the as-prepared samples was evaluated by studying the degradation of model dyes rhodamine B (RhB) under visible light. The prepared rGO/BiVO4 composites exhibited higher photocatalytic activity for the degradation of RhB with a maximum removal rate of 86% under visible light irradiation under visible-light irradiation than pure BiVO4 nanoparticles (63%). This behavior could be associated to their higher specific surface area (BET), increased light absorption intensity and the degradation of electron-hole pair recombination in BiVO4 with the introduction of the rGO.

Direct correlations of structural and optical properties of three-dimensional GaN/InGaN core/shell micro-light emitting diodes

NASA Astrophysics Data System (ADS)

Sadat Mohajerani, Matin; Müller, Marcus; Hartmann, Jana; Zhou, Hao; Wehmann, Hergo-H.; Veit, Peter; Bertram, Frank; Christen, Jürgen; Waag, Andreas

2016-05-01

Three-dimensional (3D) InGaN/GaN quantum-well (QW) core-shell light emitting diodes (LEDs) are a promising candidate for the future solid state lighting. In this contribution, we study direct correlations of structural and optical properties of the core-shell LEDs using highly spatially-resolved cathodoluminescence spectroscopy (CL) in combination with scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM). Temperature-dependent resonant photoluminescence (PL) spectroscopy has been performed to understand recombination mechanisms and to estimate the internal quantum efficiency (IQE).

Correlative Stochastic Optical Reconstruction Microscopy and Electron Microscopy

PubMed Central

Kim, Doory; Deerinck, Thomas J.; Sigal, Yaron M.; Babcock, Hazen P.; Ellisman, Mark H.; Zhuang, Xiaowei

2015-01-01

Correlative fluorescence light microscopy and electron microscopy allows the imaging of spatial distributions of specific biomolecules in the context of cellular ultrastructure. Recent development of super-resolution fluorescence microscopy allows the location of molecules to be determined with nanometer-scale spatial resolution. However, correlative super-resolution fluorescence microscopy and electron microscopy (EM) still remains challenging because the optimal specimen preparation and imaging conditions for super-resolution fluorescence microscopy and EM are often not compatible. Here, we have developed several experiment protocols for correlative stochastic optical reconstruction microscopy (STORM) and EM methods, both for un-embedded samples by applying EM-specific sample preparations after STORM imaging and for embedded and sectioned samples by optimizing the fluorescence under EM fixation, staining and embedding conditions. We demonstrated these methods using a variety of cellular targets. PMID:25874453

ultraLM and miniLM: Locator tools for smart tracking of fluorescent cells in correlative light and electron microscopy.

PubMed

Brama, Elisabeth; Peddie, Christopher J; Wilkes, Gary; Gu, Yan; Collinson, Lucy M; Jones, Martin L

2016-12-13

In-resin fluorescence (IRF) protocols preserve fluorescent proteins in resin-embedded cells and tissues for correlative light and electron microscopy, aiding interpretation of macromolecular function within the complex cellular landscape. Dual-contrast IRF samples can be imaged in separate fluorescence and electron microscopes, or in dual-modality integrated microscopes for high resolution correlation of fluorophore to organelle. IRF samples also offer a unique opportunity to automate correlative imaging workflows. Here we present two new locator tools for finding and following fluorescent cells in IRF blocks, enabling future automation of correlative imaging. The ultraLM is a fluorescence microscope that integrates with an ultramicrotome, which enables 'smart collection' of ultrathin sections containing fluorescent cells or tissues for subsequent transmission electron microscopy or array tomography. The miniLM is a fluorescence microscope that integrates with serial block face scanning electron microscopes, which enables 'smart tracking' of fluorescent structures during automated serial electron image acquisition from large cell and tissue volumes.

Pterygodermatites (Mesopectines) quentini (Nematoda, Rictulariidae), a parasite of Praomys rostratus (Rodentia, Muridae) in Mali: scanning electron and light microscopy

PubMed Central

2013-01-01

Pterygodermatites (Mesopectines) quentini n. sp. (Nematoda, Rictulariidae) is described from the murine host Praomys rostratus in the south of the Republic of Mali. It differs from other species of the subgenus by the morphology of the head, which bears four simple cephalic papillae and a nearly axial oral opening, the number of caudal papillae, the number of precloacal cuticular formations, unequal spicules and the ratio of spicule lengths/body length. The use of scanning electron microscopy in combination with conventional light microscopy enabled us to give a detailed description of the morphological characters of this new species. PMID:24025692

Analysis of Long Bone and Vertebral Failure Patterns.

DTIC Science & Technology

1982-09-30

processes further supported the findings of • :the scanning electron microscopy studies . In the impacted animals, the cartilage surface was eroded... cartilage matrix. In the six years post-impaction group, the articular cartilage had converted to fibrocartilage instead of normal hyaline cartilage . The...columns of four rhesus monkeys have been collected and are being processed for study with light microscopy and scanning electron microscopy. The baboon

A simple method for maintaining relative positions of separate tissue elements during processing for electron microscopy.

PubMed

Stirling, C A

1978-09-01

Molten (328 K) 20% gelatin is used as a 'glue' to hold together separate tissue elements or tissue elements that may be separated when cutting small blocks of tissue for plastic embedding. Standard aldehyde and osmium fixation, dehydration and epoxy embedding are compatible with this as is semi-thin sectioning for light microscopy or thin sectioning for electron microscopy.

Optimizing low-light microscopy with back-illuminated electron multiplying charge-coupled device: enhanced sensitivity, speed, and resolution.

PubMed

Coates, Colin G; Denvir, Donal J; McHale, Noel G; Thornbury, Keith D; Hollywood, Mark A

2004-01-01

The back-illuminated electron multiplying charge-coupled device (EMCCD) camera is having a profound influence on the field of low-light dynamic cellular microscopy, combining highest possible photon collection efficiency with the ability to virtually eliminate the readout noise detection limit. We report here the use of this camera, in 512 x 512 frame-transfer chip format at 10-MHz pixel readout speed, in optimizing a demanding ultra-low-light intracellular calcium flux microscopy setup. The arrangement employed includes a spinning confocal Nipkow disk, which, while facilitating the need to both generate images at very rapid frame rates and minimize background photons, yields very weak signals. The challenge for the camera lies not just in detecting as many of these scarce photons as possible, but also in operating at a frame rate that meets the temporal resolution requirements of many low-light microscopy approaches, a particular demand of smooth muscle calcium flux microscopy. Results presented illustrate both the significant sensitivity improvement offered by this technology over the previous standard in ultra-low-light CCD detection, the GenIII+intensified charge-coupled device (ICCD), and also portray the advanced temporal and spatial resolution capabilities of the EMCCD. Copyright 2004 Society of Photo-Optical Instrumentation Engineers.

Acquired Fanconi syndrome with proximal tubular cytoplasmic fibrillary inclusions of λ light chain restriction.

PubMed

Yao, Ying; Wang, Su-Xia; Zhang, You-Kang; Wang, Yan; Liu, Li; Liu, Gang

2014-01-01

Light chain proximal tubulopathy is a rarely reported entity associated with plasma cell dyscrasia that classically manifests as acquired Fanconi syndrome and is characterized by the presence of κ-restricted crystals in the proximal tubular cytoplasm. We herein present a case of multiple myeloma with Fanconi syndrome and acute kidney injury due to light chain proximal tubulopathy with light chain cast nephropathy. Prominent phagolysosomes and numerous irregularly shaped inclusions with a fibrillary matrix in the cytoplasm of the proximal tubules were identified on electron microscopy. A monotypic light chain of the λ type was detected in the distal tubular casts, proximal tubular cytoplasmic lysosomes and fibrillary inclusions on immunofluorescence and immune electron microscopy. This case underscores the importance of conducting careful ultrastructural investigations and immunocytologic examinations of light chains for detecting and diagnosing light chain proximal tubulopathy.

Correlative fluorescence microscopy and scanning transmission electron microscopy of quantum-dot-labeled proteins in whole cells in liquid.

PubMed

Dukes, Madeline J; Peckys, Diana B; de Jonge, Niels

2010-07-27

Correlative fluorescence microscopy and transmission electron microscopy (TEM) is a state-of-the-art microscopy methodology to study cellular function, combining the functionality of light microscopy with the high resolution of electron microscopy. However, this technique involves complex sample preparation procedures due to its need for either thin sections or frozen samples for TEM imaging. Here, we introduce a novel correlative approach capable of imaging whole eukaryotic cells in liquid with fluorescence microscopy and with scanning transmission electron microscopy (STEM); there is no additional sample preparation necessary for the electron microscopy. Quantum dots (QDs) were bound to epidermal growth factor (EGF) receptors of COS7 fibroblast cells. Fixed whole cells in saline water were imaged with fluorescence microscopy and subsequently with STEM. The STEM images were correlated with fluorescence images of the same cellular regions. QDs of dimensions 7x12 nm were visible in a 5 microm thick layer of saline water, consistent with calculations. A spatial resolution of 3 nm was achieved on the QDs.

Correlative Fluorescence Microscopy and Scanning Transmission Electron Microscopy of Quantum Dot Labeled Proteins in Whole Cells in Liquid

PubMed Central

Dukes, Madeline J.; Peckys, Diana B.; de Jonge, Niels

2010-01-01

Correlative fluorescence microscopy and transmission electron microscopy (TEM) is a state-of-the-art microscopy methodology to study cellular function, combining the functionality of light microscopy with the high resolution of electron microscopy. However, this technique involves complex sample preparation procedures due to its need for either thin sections or frozen samples for TEM imaging. Here, we introduce a novel correlative approach capable of imaging whole eukaryotic cells in liquid with fluorescence microscopy and with scanning transmission electron microscopy (STEM); there is no additional sample preparation necessary for the electron microscopy. Quantum dots (QDs) were bound to epidermal growth factor (EGF) receptors of COS7 fibroblast cells. Fixed whole cells in saline water were imaged with fluorescence microscopy and subsequently with STEM. The STEM images were correlated with fluorescence images of the same cellular regions. QDs of dimensions 7 × 12 nm were visible in a 5 μm thick layer of saline water, consistent with calculations. A spatial resolution of 3 nm was achieved on the QDs. PMID:20550177

Symposium N: Materials and Devices for Thermal-to-Electric Energy Conversion

DTIC Science & Technology

2010-08-24

X - ray diffraction, transmission electron microscopy, scanning electron microscopy, and dynamic light scattering. Thermal conductivity measurements...SEM), X - ray diffraction (XRD) measurements as well as Raman spectroscopy. The results from these techniques indicate a clear modification...was examined by using scanning electron microscope (SEM; HITACHI S-4500 model) attached with an energy dispersive x - ray spectroscopy. The electrical

[THE CHARACTERISTICS OF MORPHOLOGY OF BIOFILM OF PERIODONTIUM UNDER INFLAMMATORY DISEASES OF GUMS (CHRONIC CATARRHAL GINGIVITIS, CHRONIC PERIODONTITIS, CANDIDA-ASSOCIATED PERIODONTITIS) ACCORDING RESULTS OF ELECTRONIC MICROSCOPY].

PubMed

Ippolitov, E V; Didenko, L V; Tzarev, V N

2015-12-01

The study was carried out to analyze morphology of biofilm of periodontium and to develop electronic microscopic criteria of differentiated diagnostic of inflammatory diseases of gums. The scanning electronic microscopy was applied to analyze samples of bioflm of periodont from 70 patients. Including ten patients with every nosologic form of groups with chronic catarrhal periodontitis. of light, mean and severe degree, chronic catarrhal gingivitis, Candida-associated paroperiodontitis and 20 healthy persons with intact periodontium. The analysis was implemented using dual-beam scanning electronic microscope Quanta 200 3D (FEI company, USA) and walk-through electronic micJEM 100B (JEOL, Japan). To detect marker DNA of periodont pathogenic bacteria in analyzed samples the kit of reagentsfor polymerase chain reaction "MultiDent-5" ("GenLab", Russia). The scanning electronic microscopy in combination with transmission electronic microscopy and polymerase chain reaction permits analyzing structure, composition and degree of development of biofilm of periodontium and to apply differentiated diagnostic of different nosologic forms of inflammatory diseases of periodontium, including light form of chronic periodontitis and gingivitis. The electronic microscopical indications of diseases ofperiodontium of inflammatory character are established: catarrhal gingivitis, (coccal morphological alternate), chronic periodontitis (bacillary morphological alternate), Candida-associated periodontitis (Candida morphological alternate of biofilm ofperiodontium).

Research and application on imaging technology of line structure light based on confocal microscopy

NASA Astrophysics Data System (ADS)

Han, Wenfeng; Xiao, Zexin; Wang, Xiaofen

2009-11-01

In 2005, the theory of line structure light confocal microscopy was put forward firstly in China by Xingyu Gao and Zexin Xiao in the Institute of Opt-mechatronics of Guilin University of Electronic Technology. Though the lateral resolution of line confocal microscopy can only reach or approach the level of the traditional dot confocal microscopy. But compared with traditional dot confocal microscopy, it has two advantages: first, by substituting line scanning for dot scanning, plane imaging only performs one-dimensional scanning, with imaging velocity greatly improved and scanning mechanism simplified, second, transfer quantity of light is greatly improved by substituting detection hairline for detection pinhole, and low illumination CCD is used directly to collect images instead of photoelectric intensifier. In order to apply the line confocal microscopy to practical system, based on the further research on the theory of the line confocal microscopy, imaging technology of line structure light is put forward on condition of implementation of confocal microscopy. Its validity and reliability are also verified by experiments.

The EIGER detector for low-energy electron microscopy and photoemission electron microscopy.

PubMed

Tinti, G; Marchetto, H; Vaz, C A F; Kleibert, A; Andrä, M; Barten, R; Bergamaschi, A; Brückner, M; Cartier, S; Dinapoli, R; Franz, T; Fröjdh, E; Greiffenberg, D; Lopez-Cuenca, C; Mezza, D; Mozzanica, A; Nolting, F; Ramilli, M; Redford, S; Ruat, M; Ruder, Ch; Schädler, L; Schmidt, Th; Schmitt, B; Schütz, F; Shi, X; Thattil, D; Vetter, S; Zhang, J

2017-09-01

EIGER is a single-photon-counting hybrid pixel detector developed at the Paul Scherrer Institut, Switzerland. It is designed for applications at synchrotron light sources with photon energies above 5 keV. Features of EIGER include a small pixel size (75 µm × 75 µm), a high frame rate (up to 23 kHz), a small dead-time between frames (down to 3 µs) and a dynamic range up to 32-bit. In this article, the use of EIGER as a detector for electrons in low-energy electron microscopy (LEEM) and photoemission electron microscopy (PEEM) is reported. It is demonstrated that, with only a minimal modification to the sensitive part of the detector, EIGER is able to detect electrons emitted or reflected by the sample and accelerated to 8-20 keV. The imaging capabilities are shown to be superior to the standard microchannel plate detector for these types of applications. This is due to the much higher signal-to-noise ratio, better homogeneity and improved dynamic range. In addition, the operation of the EIGER detector is not affected by radiation damage from electrons in the present energy range and guarantees more stable performance over time. To benchmark the detector capabilities, LEEM experiments are performed on selected surfaces and the magnetic and electronic properties of individual iron nanoparticles with sizes ranging from 8 to 22 nm are detected using the PEEM endstation at the Surface/Interface Microscopy (SIM) beamline of the Swiss Light Source.

Ultrafast Science Opportunities with Electron Microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Durr, Hermann

X-rays and electrons are two of the most fundamental probes of matter. When the Linac Coherent Light Source (LCLS), the world’s first x-ray free electron laser, began operation in 2009, it transformed ultrafast science with the ability to generate laser-like x-ray pulses from the manipulation of relativistic electron beams. This document describes a similar future transformation. In Transmission Electron Microscopy, ultrafast relativistic (MeV energy) electron pulses can achieve unsurpassed spatial and temporal resolution. Ultrafast temporal resolution will be the next frontier in electron microscopy and can ideally complement ultrafast x-ray science done with free electron lasers. This document describes themore » Grand Challenge science opportunities in chemistry, material science, physics and biology that arise from an MeV ultrafast electron diffraction & microscopy facility, especially when coupled with linac-based intense THz and X-ray pump capabilities.« less

Correlative Super-Resolution Microscopy: New Dimensions and New Opportunities.

PubMed

Hauser, Meghan; Wojcik, Michal; Kim, Doory; Mahmoudi, Morteza; Li, Wan; Xu, Ke

2017-06-14

Correlative microscopy, the integration of two or more microscopy techniques performed on the same sample, produces results that emphasize the strengths of each technique while offsetting their individual weaknesses. Light microscopy has historically been a central method in correlative microscopy due to its widespread availability, compatibility with hydrated and live biological samples, and excellent molecular specificity through fluorescence labeling. However, conventional light microscopy can only achieve a resolution of ∼300 nm, undercutting its advantages in correlations with higher-resolution methods. The rise of super-resolution microscopy (SRM) over the past decade has drastically improved the resolution of light microscopy to ∼10 nm, thus creating exciting new opportunities and challenges for correlative microscopy. Here we review how these challenges are addressed to effectively correlate SRM with other microscopy techniques, including light microscopy, electron microscopy, cryomicroscopy, atomic force microscopy, and various forms of spectroscopy. Though we emphasize biological studies, we also discuss the application of correlative SRM to materials characterization and single-molecule reactions. Finally, we point out current limitations and discuss possible future improvements and advances. We thus demonstrate how a correlative approach adds new dimensions of information and provides new opportunities in the fast-growing field of SRM.

Backscattered electron SEM imaging of resin sections from plant specimens: observation of histological to subcellular structure and CLEM.

PubMed

Rizzo, N W; Duncan, K E; Bourett, T M; Howard, R J

2016-08-01

We have refined methods for biological specimen preparation and low-voltage backscattered electron imaging in the scanning electron microscope that allow for observation at continuous magnifications of ca. 130-70 000 X, and documentation of tissue and subcellular ultrastructure detail. The technique, based upon early work by Ogura & Hasegawa (1980), affords use of significantly larger sections from fixed and resin-embedded specimens than is possible with transmission electron microscopy while providing similar data. After microtomy, the sections, typically ca. 750 nm thick, were dried onto the surface of glass or silicon wafer and stained with heavy metals-the use of grids avoided. The glass/wafer support was then mounted onto standard scanning electron microscopy sample stubs, carbon-coated and imaged directly at an accelerating voltage of 5 kV, using either a yttrium aluminum garnet or ExB backscattered electron detector. Alternatively, the sections could be viewed first by light microscopy, for example to document signal from a fluorescent protein, and then by scanning electron microscopy to provide correlative light/electron microscope (CLEM) data. These methods provide unobstructed access to ultrastructure in the spatial context of a section ca. 7 × 10 mm in size, significantly larger than the typical 0.2 × 0.3 mm section used for conventional transmission electron microscopy imaging. Application of this approach was especially useful when the biology of interest was rare or difficult to find, e.g. a particular cell type, developmental stage, large organ, the interface between cells of interacting organisms, when contextual information within a large tissue was obligatory, or combinations of these factors. In addition, the methods were easily adapted for immunolocalizations. © 2015 The Author. Journal of Microscopy published by John Wiley & Sons, Ltd on behalf of the Royal Microscopical Society.

Light, electron microscopic and immunohistochemical study of the effect of low-dose aspirin during the proestrus phase on rat endometrium in the preimplantation period.

PubMed

Ateş, Utku; Baka, Meral; Turgut, Mehmet; Uyanikgil, Yiğit; Ulker, Sibel; Yilmaz, Ozlem; Tavmergen, Erol; Yurtseven, Mine

2007-04-01

To evaluate structural alterations in rat endometrium at preimplantation following treatment with aspirin beginning from proestrus by light microscopy, electron microscopy and immunohistochemical techniques. Twenty rats were divided into control (n = 10) and experimental (n = 10) groups. Experimental rats were treated with low-dose aspirin daily (2 mg/kg/day) during estrus, beginning from the proestrus phase, mated at end of cycle and treated with aspirin. Untreated pregnant rats were the control group. Rats in both groups were sacrificed at the 84th pregnancy hour; the uterus was rapidly removed and dissected free of surrounding adipose tissue. Uteri specimens from nonpregnant rats were transferred into fixative solution and processed for light, electron microscopic and immunohistochemical study. Light and electron microscopy of endometrium from control rats conformed to mid-diestrus phase; endometrial histology of the aspirin-treated group conformed to late diestrus phase. The endometrial layer was significantly thicker in the aspirin-treated group compared to the untreated control group (p <0.001). No significant difference was found in vessel number between groups. Staining with alphaV integrin was more dense in the aspirin-treated group. Based on histologic findings, we suggest low-dose aspirin has positive effects on preparing endometrium before implantation.

Preparation, characterization, physical properties, and photoconducting behaviour of anthracene derivative nanowires

NASA Astrophysics Data System (ADS)

Xiao, Jinchong; Yin, Zongyou; Yang, Bo; Liu, Yi; Ji, Li; Guo, Jun; Huang, Ling; Liu, Xuewei; Yan, Qingyu; Zhang, Hua; Zhang, Qichun

2011-11-01

Organic nanowires of 9,10-dibromoanthracene (DBA) and 9,10-dicyanoanthracene (DCNA) were obtained by adding the THF solution of DBA/DCNA into water containing P123 surfactants. The as-prepared nanowires were characterized by UV-vis, fluorescence spectra, Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy (TEM). We found that DBA and DCNA nanowires emitted green light rather than blue light for molecules in THF solution. The red-shift UV and fluorescent spectra of DBA and DCNA nanowires implied that these nanowires were formed through J-aggregation. The photoconducting study of DBA/DCNA nanowire-based network on rGO/SiO2/Si shows different photocurrent behaviors upon irradiation, which displayed that electron transfer from DCNA nanowire to rGO was stronger than that of DBA nanowires to rGO.Organic nanowires of 9,10-dibromoanthracene (DBA) and 9,10-dicyanoanthracene (DCNA) were obtained by adding the THF solution of DBA/DCNA into water containing P123 surfactants. The as-prepared nanowires were characterized by UV-vis, fluorescence spectra, Field Emission Scanning Electron Microscopy (FESEM), and Transmission Electron Microscopy (TEM). We found that DBA and DCNA nanowires emitted green light rather than blue light for molecules in THF solution. The red-shift UV and fluorescent spectra of DBA and DCNA nanowires implied that these nanowires were formed through J-aggregation. The photoconducting study of DBA/DCNA nanowire-based network on rGO/SiO2/Si shows different photocurrent behaviors upon irradiation, which displayed that electron transfer from DCNA nanowire to rGO was stronger than that of DBA nanowires to rGO. Electronic supplementary information (ESI) available: XRD patterns and simulations, and FT-IR spectra. CCDC reference numbers 840471. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c1nr10655d

Balamuthia mandrillaris: Further morphological observations of trophozoites by light, scanning and transmission electron microscopy.

PubMed

González-Robles, Arturo; Lares-Villa, Fernando; Lares-Jiménez, Luis Fernando; Omaña-Molina, Maritza; Salazar-Villatoro, Lizbeth; Martínez-Palomo, Adolfo

2015-10-01

Additional morphological features of Balamuthia mandrillaris observed by light and electron microscopy are reported. Trophozoites were extremely pleomorphic: their cell shapes ranged from rounded to elongated and sometimes they appeared exceptionally stretched out and branched. By transmission electron microscopy it was possible to observe two different cytoplasmic areas, the ectoplasm and the endoplasm and often sections of rough endoplasmic reticulum were found in the transition zone. The cytoplasm was very fibrogranular and most of the organelles typically found in eukaryotic cells were observed. A particular finding was the presence of numerous mitochondria with a different structure from those of other free-living amoebae. The observations reported here may reinforce the morphological knowledge of this amoeba and provide a background for further analyses. Copyright © 2015 Elsevier Inc. All rights reserved.

Transmission Electron Microscopy Analysis of Skin Lesions from Sporotrichosis Epidemic in Rio de Janeiro, Brazil

PubMed Central

Porto Ferreira, Cassio; Oliveira de Almeida, Ana Cristina; Corte-Real, Suzana

2015-01-01

Transmission electron microscopy can yield useful information in a range of scientific fields; it is capable of imaging at a significantly higher resolution than light microscopes and has been a very useful tool in the identification of morphological changes of the dermis as well as assessment of changes in the extracellular matrix. Our aim is to characterize by electron microscopy the cellular profile of lesions caused by Sporothrix schenckii from the sporotrichosis epidemic in its zoonotic form that occurs in Rio de Janeiro, Brazil. PMID:25653392

Low-cost cryo-light microscopy stage fabrication for correlated light/electron microscopy.

PubMed

Carlson, David B; Evans, James E

2011-06-05

The coupling of cryo-light microscopy (cryo-LM) and cryo-electron microscopy (cryo-EM) poses a number of advantages for understanding cellular dynamics and ultrastructure. First, cells can be imaged in a near native environment for both techniques. Second, due to the vitrification process, samples are preserved by rapid physical immobilization rather than slow chemical fixation. Third, imaging the same sample with both cryo-LM and cryo-EM provides correlation of data from a single cell, rather than a comparison of "representative samples". While these benefits are well known from prior studies, the widespread use of correlative cryo-LM and cryo-EM remains limited due to the expense and complexity of buying or building a suitable cryogenic light microscopy stage. Here we demonstrate the assembly, and use of an inexpensive cryogenic stage that can be fabricated in any lab for less than $40 with parts found at local hardware and grocery stores. This cryo-LM stage is designed for use with reflected light microscopes that are fitted with long working distance air objectives. For correlative cryo-LM and cryo-EM studies, we adapt the use of carbon coated standard 3-mm cryo-EM grids as specimen supports. After adsorbing the sample to the grid, previously established protocols for vitrifying the sample and transferring/handling the grid are followed to permit multi-technique imaging. As a result, this setup allows any laboratory with a reflected light microscope to have access to direct correlative imaging of frozen hydrated samples.

A correlative optical microscopy and scanning electron microscopy approach to locating nanoparticles in brain tumors.

PubMed

Kempen, Paul J; Kircher, Moritz F; de la Zerda, Adam; Zavaleta, Cristina L; Jokerst, Jesse V; Mellinghoff, Ingo K; Gambhir, Sanjiv S; Sinclair, Robert

2015-01-01

The growing use of nanoparticles in biomedical applications, including cancer diagnosis and treatment, demands the capability to exactly locate them within complex biological systems. In this work a correlative optical and scanning electron microscopy technique was developed to locate and observe multi-modal gold core nanoparticle accumulation in brain tumor models. Entire brain sections from mice containing orthotopic brain tumors injected intravenously with nanoparticles were imaged using both optical microscopy to identify the brain tumor, and scanning electron microscopy to identify the individual nanoparticles. Gold-based nanoparticles were readily identified in the scanning electron microscope using backscattered electron imaging as bright spots against a darker background. This information was then correlated to determine the exact location of the nanoparticles within the brain tissue. The nanoparticles were located only in areas that contained tumor cells, and not in the surrounding healthy brain tissue. This correlative technique provides a powerful method to relate the macro- and micro-scale features visible in light microscopy with the nanoscale features resolvable in scanning electron microscopy. Copyright © 2014 Elsevier Ltd. All rights reserved.

Crystal morphology of sunflower wax in soybean oil organogel

USDA-ARS?s Scientific Manuscript database

While sunflower wax has been recognized as an excellent organogelator for edible oil, the detailed morphology of sunflower wax crystals formed in an edible oil organogel has not been fully understood. In this study, polarized light microscopy, phase contrast microscopy, scanning electron microscopy ...

Evaluation of laser ablation microtomy for correlative microscopy of hard tissues.

PubMed

Boyde, A

2018-02-27

Laser ablation machining or microtomy (LAM) is a relatively new approach to producing slide mounted sections of translucent materials. We evaluated the method with a variety of problems from the bone, joint and dental tissues fields where we require thin undecalcified and undistorted sections for correlative light microscopy (LM) and backscattered electron scanning electron microscopy (BSE SEM). All samples were embedded in poly-methylmethacrlate (PMMA) and flat block surfaces had been previously studied by BSE-SEM and confocal scanning light microscopy (CSLM). Most were also studied by X-yay microtomography (XMT). The block surface is stuck to a glass slide with cyanoacrylate adhesive. Setting the section thickness and levelling uses inbuilt optical coherence tomographic imaging. Tight focusing of near-infrared laser radiation in the sectioning plane gives extreme intensities causing photodisruption of material at the focal point. The laser beam is moved by a fast scanner to write a cutting line, which is simultaneously moved by an XY positioning unit to create a sectioning plane. The block is thereby released from the slide, leaving the section stuck to the slide. Light, wet polishing on the finest grade (4000 grit) silicon carbide polishing paper is used to remove a 1-2 μm thick damaged layer at the surface of the section. Sections produced by laser cutting are fine in quality and superior to those produced by mechanical cutting and can be thinner than the 'voxel' in most laboratory X-ray microtomography systems. The present extensive pilot studies have shown that it works to produce samples which we can study by both light and electron microscopy. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

Minimal resin embedding of multicellular specimens for targeted FIB-SEM imaging.

PubMed

Schieber, Nicole L; Machado, Pedro; Markert, Sebastian M; Stigloher, Christian; Schwab, Yannick; Steyer, Anna M

2017-01-01

Correlative light and electron microscopy (CLEM) is a powerful tool to perform ultrastructural analysis of targeted tissues or cells. The large field of view of the light microscope (LM) enables quick and efficient surveys of the whole specimen. It is also compatible with live imaging, giving access to functional assays. CLEM protocols take advantage of the features to efficiently retrace the position of targeted sites when switching from one modality to the other. They more often rely on anatomical cues that are visible both by light and electron microscopy. We present here a simple workflow where multicellular specimens are embedded in minimal amounts of resin, exposing their surface topology that can be imaged by scanning electron microscopy (SEM). LM and SEM both benefit from a large field of view that can cover whole model organisms. As a result, targeting specific anatomic locations by focused ion beam-SEM (FIB-SEM) tomography becomes straightforward. We illustrate this application on three different model organisms, used in our laboratory: the zebrafish embryo Danio rerio, the marine worm Platynereis dumerilii, and the dauer larva of the nematode Caenorhabditis elegans. Here we focus on the experimental steps to reduce the amount of resin covering the samples and to image the specimens inside an FIB-SEM. We expect this approach to have widespread applications for volume electron microscopy on multiple model organisms. Copyright © 2017 Elsevier Inc. All rights reserved.

New hardware and workflows for semi-automated correlative cryo-fluorescence and cryo-electron microscopy/tomography.

PubMed

Schorb, Martin; Gaechter, Leander; Avinoam, Ori; Sieckmann, Frank; Clarke, Mairi; Bebeacua, Cecilia; Bykov, Yury S; Sonnen, Andreas F-P; Lihl, Reinhard; Briggs, John A G

2017-02-01

Correlative light and electron microscopy allows features of interest defined by fluorescence signals to be located in an electron micrograph of the same sample. Rare dynamic events or specific objects can be identified, targeted and imaged by electron microscopy or tomography. To combine it with structural studies using cryo-electron microscopy or tomography, fluorescence microscopy must be performed while maintaining the specimen vitrified at liquid-nitrogen temperatures and in a dry environment during imaging and transfer. Here we present instrumentation, software and an experimental workflow that improves the ease of use, throughput and performance of correlated cryo-fluorescence and cryo-electron microscopy. The new cryo-stage incorporates a specially modified high-numerical aperture objective lens and provides a stable and clean imaging environment. It is combined with a transfer shuttle for contamination-free loading of the specimen. Optimized microscope control software allows automated acquisition of the entire specimen area by cryo-fluorescence microscopy. The software also facilitates direct transfer of the fluorescence image and associated coordinates to the cryo-electron microscope for subsequent fluorescence-guided automated imaging. Here we describe these technological developments and present a detailed workflow, which we applied for automated cryo-electron microscopy and tomography of various specimens. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Phase contrast scanning transmission electron microscopy imaging of light and heavy atoms at the limit of contrast and resolution.

PubMed

Yücelen, Emrah; Lazić, Ivan; Bosch, Eric G T

2018-02-08

Using state of the art scanning transmission electron microscopy (STEM) it is nowadays possible to directly image single atomic columns at sub-Å resolution. In standard (high angle) annular dark field STEM ((HA)ADF-STEM), however, light elements are usually invisible when imaged together with heavier elements in one image. Here we demonstrate the capability of the recently introduced Integrated Differential Phase Contrast STEM (iDPC-STEM) technique to image both light and heavy atoms in a thin sample at sub-Å resolution. We use the technique to resolve both the Gallium and Nitrogen dumbbells in a GaN crystal in [[Formula: see text

Microscopy and microanalysis 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bailey, G.W.; Corbett, J.M.; Dimlich, R.V.W.

1996-12-31

The Proceedings of this Annual Meeting contain paper of members from the three societies. These proceedings emphasizes the common research interests and attempts to eliminate some unwanted overlap. Topics covered are: microscopic analysis of animals with altered gene expression and in-situ gene and antibody localizations, high-resolution elemental mapping of nucleoprofein interactions, plant biology and pathology, quantitative HREM analysis of perfect and defected materials, computational methods for TEM image analysis, high-resolution FESM in materials research, frontiers in polymer microscopy and microanalysis, oxidation and corrosion, micro XRD and XRF, molecular microspectroscopy and spectral imaging, advances in confocal and multidimensional light microscopy, analyticalmore » electron microscopy in biology, correlative microscopy in biological sciences, grain-boundary microengineering, surfaces and interfaces, telepresence microscopy in education and research, MSA educational outreach, quantitative electron probe microanalysis, frontiers of analytical electron microscopy, critical issues in ceramic microstructures, dynamic organization of the cell, pathology, microbiology, high-resolution biological and cryo SEM, and scanning-probe microscopy.« less

Simultaneous Correlative Scanning Electron and High-NA Fluorescence Microscopy

PubMed Central

Liv, Nalan; Zonnevylle, A. Christiaan; Narvaez, Angela C.; Effting, Andries P. J.; Voorneveld, Philip W.; Lucas, Miriam S.; Hardwick, James C.; Wepf, Roger A.; Kruit, Pieter; Hoogenboom, Jacob P.

2013-01-01

Correlative light and electron microscopy (CLEM) is a unique method for investigating biological structure-function relations. With CLEM protein distributions visualized in fluorescence can be mapped onto the cellular ultrastructure measured with electron microscopy. Widespread application of correlative microscopy is hampered by elaborate experimental procedures related foremost to retrieving regions of interest in both modalities and/or compromises in integrated approaches. We present a novel approach to correlative microscopy, in which a high numerical aperture epi-fluorescence microscope and a scanning electron microscope illuminate the same area of a sample at the same time. This removes the need for retrieval of regions of interest leading to a drastic reduction of inspection times and the possibility for quantitative investigations of large areas and datasets with correlative microscopy. We demonstrate Simultaneous CLEM (SCLEM) analyzing cell-cell connections and membrane protrusions in whole uncoated colon adenocarcinoma cell line cells stained for actin and cortactin with AlexaFluor488. SCLEM imaging of coverglass-mounted tissue sections with both electron-dense and fluorescence staining is also shown. PMID:23409024

Identification of light elements in silicon nitride by aberration-corrected scanning transmission electron microscopy.

PubMed

Idrobo, Juan C; Walkosz, Weronika; Klie, Robert F; Oğüt, Serdar

2012-12-01

In silicon nitride structural ceramics, the overall mechanical and thermal properties are controlled by the atomic and electronic structures at the interface between the ceramic grains and the amorphous intergranular films (IGFs) formed by various sintering additives. In the last ten years the atomic arrangements of heavy elements (rare-earths) at the Si(3)N(4)/IGF interfaces have been resolved. However, the atomic position of light elements, without which it is not possible to obtain a complete description of the interfaces, has been lacking. This review article details the authors' efforts to identify the atomic arrangement of light elements such as nitrogen and oxygen at the Si(3)N(4)/SiO(2) interface and in bulk Si(3)N(4) using aberration-corrected scanning transmission electron microscopy. Published by Elsevier B.V.

The sea urchin egg jelly coat is a three-dimensional fibrous network as seen by intermediate voltage electron microscopy and deep etching analysis.

PubMed

Bonnell, B S; Larabell, C; Chandler, D E

1993-06-01

The egg jelly (EJ) coat which surrounds the unfertilized sea urchin egg undergoes extensive swelling upon contact with sea water, forming a three-dimensional network of interconnected fibers extending nearly 50 microns from the egg surface. Owing to its solubility, this coat has been difficult to visualize by light and electron microscopy. However, Lytechinus pictus EJ coats remain intact, if the fixation medium is maintained at pH 9. The addition of alcian blue during the final dehydration step of sample preparation stains the EJ for visualization of resin embedded eggs by both light and electron microscopy. Stereo pairs taken of thick sections prepared for intermediate voltage electron microscopy (IVEM) produce a three-dimensional image of the EJ network, consisting of interconnected fibers decorated along their length by globular jelly components. Using scanning electron microscopy (SEM), we have shown that before swelling, EJ exists in a tightly bound network of jelly fibers, 50-60 nm in diameter. In contrast, swollen EJ consists of a greatly extended network whose fibrous components measure 10 to 30 nm in diameter. High resolution stereo images of hydrated jelly produced by the quick-freeze/deep-etch/rotary-shadowing technique (QF/DE/RS) show nearly identical EJ networks, suggesting that dehydration does not markedly alter the structure of this extracellular matrix.

A simple procedure to analyze positions of interest in infectious cell cultures by correlative light and electron microscopy.

PubMed

Madela, Kazimierz; Banhart, Sebastian; Zimmermann, Anja; Piesker, Janett; Bannert, Norbert; Laue, Michael

2014-01-01

Plastic cell culture dishes that contain a thin bottom of highest optical quality including an imprinted finder grid (μ-Dish Grid-500) are optimally suited for routine correlative light and electron microscopy using chemical fixation. Such dishes allow high-resolution fluorescence and bright-field imaging using fixed and living cells and are compatible with standard protocols for scanning and transmission electron microscopy. Ease of use during cell culture and imaging, as well as a tight cover render the dishes particularly suitable for working with infectious organisms up to the highest biosafety level. Detailed protocols are provided and demonstrated by showing two examples: monitoring the production of virus-like particles of the Human Endogenous Retrovirus HERV-K(HML-2) by HeLa cells and investigation of Rab11-positive membrane-compartments of HeLa cells after infection with Chlamydia trachomatis. © 2014 Elsevier Inc. All rights reserved.

Breaking resolution limits in ultrafast electron diffraction and microscopy.

PubMed

Baum, Peter; Zewail, Ahmed H

2006-10-31

Ultrafast electron microscopy and diffraction are powerful techniques for the study of the time-resolved structures of molecules, materials, and biological systems. Central to these approaches is the use of ultrafast coherent electron packets. The electron pulses typically have an energy of 30 keV for diffraction and 100-200 keV for microscopy, corresponding to speeds of 33-70% of the speed of light. Although the spatial resolution can reach the atomic scale, the temporal resolution is limited by the pulse width and by the difference in group velocities of electrons and the light used to initiate the dynamical change. In this contribution, we introduce the concept of tilted optical pulses into diffraction and imaging techniques and demonstrate the methodology experimentally. These advances allow us to reach limits of time resolution down to regimes of a few femtoseconds and, possibly, attoseconds. With tilted pulses, every part of the sample is excited at precisely the same time as when the electrons arrive at the specimen. Here, this approach is demonstrated for the most unfavorable case of ultrafast crystallography. We also present a method for measuring the duration of electron packets by autocorrelating electron pulses in free space and without streaking, and we discuss the potential of tilting the electron pulses themselves for applications in domains involving nuclear and electron motions.

The e-evolution of microscopy in dental education.

PubMed

Farah, Camile S; Maybury, Terrence S

2009-08-01

Recent technological innovation has now made it possible to turn the computer into a microscope. This has entailed a shift from light microscopy to virtual microscopy. This development then foregrounds the issue of the pedagogy involved in this move from the analogue technology of the light microscope to the digital, computerized instance of virtual microscopy. In order to address this issue, undergraduate students enrolled in the Bachelor of Dental Science program at the University of Queensland School of Dentistry were surveyed to ascertain their preference for light or virtual microscopy. The value of this study is that it was conducted on the same cohort of students in two separate courses in 2006 and 2008, giving it longitudinal validity. The responses were overwhelmingly in favor of virtual microscopy. When it came to completely replacing the light microscope with virtual microscopy, however, students were much more ambivalent about such a wholesale change although this was less of an issue in the senior year. This shift from light to virtual microscopy signals larger changes in the tertiary sector from print-literate to electronic forms of knowledge and from teacher-centered to student-focused frames of learning. In short, we are in the midst of the e-evolution of microscopy in dental education.

Multi-modal Registration for Correlative Microscopy using Image Analogies

PubMed Central

Cao, Tian; Zach, Christopher; Modla, Shannon; Powell, Debbie; Czymmek, Kirk; Niethammer, Marc

2014-01-01

Correlative microscopy is a methodology combining the functionality of light microscopy with the high resolution of electron microscopy and other microscopy technologies for the same biological specimen. In this paper, we propose an image registration method for correlative microscopy, which is challenging due to the distinct appearance of biological structures when imaged with different modalities. Our method is based on image analogies and allows to transform images of a given modality into the appearance-space of another modality. Hence, the registration between two different types of microscopy images can be transformed to a mono-modality image registration. We use a sparse representation model to obtain image analogies. The method makes use of corresponding image training patches of two different imaging modalities to learn a dictionary capturing appearance relations. We test our approach on backscattered electron (BSE) scanning electron microscopy (SEM)/confocal and transmission electron microscopy (TEM)/confocal images. We perform rigid, affine, and deformable registration via B-splines and show improvements over direct registration using both mutual information and sum of squared differences similarity measures to account for differences in image appearance. PMID:24387943

Transmission electron microscopy analysis of skin lesions from sporotrichosis epidemic in Rio de Janeiro, Brazil.

PubMed

Ferreira, Cassio Porto; Oliveira de Almeida, Ana Cristina; Corte-Real, Suzana

2015-02-01

Transmission electron microscopy can yield useful information in a range of scientific fields; it is capable of imaging at a significantly higher resolution than light microscopes and has been a very useful tool in the identification of morphological changes of the dermis as well as assessment of changes in the extracellular matrix. Our aim is to characterize by electron microscopy the cellular profile of lesions caused by Sporothrix schenckii from the sporotrichosis epidemic in its zoonotic form that occurs in Rio de Janeiro, Brazil. © The American Society of Tropical Medicine and Hygiene.

Freezing without Ice Crystal Damage: Semithin and Ultrathin Frozen Sections of Ethanol-Infiltrated Tissue for Microscopy, with Applications to Immunocytochemistry

NASA Astrophysics Data System (ADS)

Christensen, A. Kent; Lowry, Terry B.

1995-10-01

Ethanol (ethyl alcohol) has long been a standard reagent used in preparing tissues for light and electron microscopy. After fixation, tissues are usually dehydrated with ethanol before being embedded in paraffin or plastic. In this study we show that the ethanol-infiltrated tissue can be frozen and sectioned directly without embedding. When tissue impregnated with ethanol is cooled below about [minus sign]117°C with liquid nitrogen, the ethanol solidifies without appreciable crystallization. The frozen tissue can then be sectioned in a commercial cryoultramicrotome that is set at [minus sign]155 to [minus sign]170°C to produce semithin frozen sections (0.5 to 3 [mu]m thick) for light microscopy or ultrathin frozen sections (50 to 100 nm thick) for electron microscopy. Sections are picked up and mounted on glass slides or EM grids by means that are in current use for ice ultrathin frozen sectioning. Because there is no apparent freezing damage, the morphology in these ethanol frozen sections of unembedded tissue appears generally quite good, often resembling that obtained by conventional EM techniques. Examples are provided that illustrate the use of this material for immunocytochemistry at the light and electron microscope levels.

Detection of local chemical states of lithium and their spatial mapping by scanning transmission electron microscopy, electron energy-loss spectroscopy and hyperspectral image analysis.

PubMed

Muto, Shunsuke; Tatsumi, Kazuyoshi

2017-02-08

Advancements in the field of renewable energy resources have led to a growing demand for the analysis of light elements at the nanometer scale. Detection of lithium is one of the key issues to be resolved for providing guiding principles for the synthesis of cathode active materials, and degradation analysis after repeated use of those materials. We have reviewed the different techniques currently used for the characterization of light elements such as high-resolution transmission electron microscopy, scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). In the present study, we have introduced a methodology to detect lithium in solid materials, particularly for cathode active materials used in lithium-ion battery. The chemical states of lithium were isolated and analyzed from the overlapping multiple spectral profiles, using a suite of STEM, EELS and hyperspectral image analysis. The method was successfully applied in the chemical state analyses of hetero-phases near the surface and grain boundary regions of the active material particles formed by chemical reactions between the electrolyte and the active materials. © The Author 2016. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Catalytic Graphitization of Coal-Based Carbon Materials with Light Rare Earth Elements.

PubMed

Wang, Rongyan; Lu, Guimin; Qiao, Wenming; Yu, Jianguo

2016-08-30

The catalytic graphitization mechanism of coal-based carbon materials with light rare earth elements was investigated using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, selected-area electron diffraction, and high-resolution transmission electron microscopy. The interface between light rare earth elements and carbon materials was carefully observed, and two routes of rare earth elements catalyzing the carbon materials were found: dissolution-precipitation and carbide formation-decomposition. These two simultaneous processes certainly accelerate the catalytic graphitization of carbon materials, and light rare earth elements exert significant influence on the microstructure and thermal conductivity of graphite. Moreover, by virtue of praseodymium (Pr), it was found that a highly crystallographic orientation of graphite was induced and formed, which was reasonably attributed to the similar arrangements of the planes perpendicular to (001) in both graphite and Pr crystals. The interface between Pr and carbon was found to be an important factor for the orientation of graphite structure.

Synthesis of CdS/BiOBr nanosheets composites with efficient visible-light photocatalytic activity

NASA Astrophysics Data System (ADS)

Cui, Haojie; Zhou, Yawen; Mei, Jinfeng; Li, Zhongyu; Xu, Song; Yao, Chao

2018-01-01

The efficient charge separation action and visible-light responding could enhance the photocatalytic property of photocatalysts. In the present study, novel CdS/BiOBr nanosheets composites were synthesized by a three-step process. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (FE-SEM), diffuse reflection spectroscopy (DRS), Raman spectroscopy and photoluminescence (PL). Under visible-light irradiation, the as-prepared CdS nanoparticles decorated BiOBr nanosheets exhibited the excellent photocatalytic activity and high stability for malachite green (MG) degradation. The photodegradation achieved maximum degradation efficiency (99%) using CdS/BiOBr-3 composites as photocatalyst. Furthermore, the possible photocatalytic mechanism upon CdS/BiOBr composites was also discussed through radical and holes trapping experiments. The heterostructure between CdS and BiOBr improved photocatalytic activity dramatically, which greatly promoted migration rate of the photoinduced electrons besides limiting the recombination of photogenerated electron-hole pairs.

Ultrastructural effects of silicone oil on the clear crystalline lens of the human eye.

PubMed

Soliman, Wael; Sharaf, Mohamed; Abdelazeem, Khaled; El-Gamal, Dalia; Nafady, Allam

2018-03-01

To evaluate light and electron microscopic changes of the anterior capsule and its epithelium after clear lens extraction of vitrectomized myopic eyes with silicone oil tamponade. This prospective, controlled, non-randomized, interventional study included 20 anterior lens capsular specimens that were excised during combined clear lens extraction and silicone oil removal from previously vitrectomized highly myopic patients with silicone oil tamponade for previous retinal detachment surgeries. The specimens were examined via light microscopy and electron microscopy and compared with 20 anterior capsule specimens removed during clear lens extraction of non-vitrectomized highly myopic eyes. Light microscopic examination of clear lens anterior capsule specimens of vitrectomized myopic eyes filled with silicone oil showed relatively more flat cells with irregular outline of lens' epithelial cells with wide intercellular spaces, deeply stained nuclei, and multiple intracytoplasmic vacuoles. Scanning electron microscopy revealed collagenous surfaces filled with multiple pits, depressions, and abnormal deposits. Transmission electron microscopy revealed lens epithelial cells with apoptotic changes, many cytoplasmic vacuoles, and filopodia-like protrusions between lens epithelial cells and the capsule. Epithelial proliferation and multilayering were also observed. silicone oil may play a role in the development of apoptotic and histopathological changes in clear lens epithelial cells. Clarity of the lens at the time of silicone oil removal does not indicate an absence of cataractous changes. We found justification of combined clear lens extraction and silicone oil removal or combined phacovitrectomy when silicone oil injection is planned, but further long-term studies with larger patient groups are required.

[Electron microscopic study of the An-750 strain of Powassan virus isolated in the Soviet Union].

PubMed

Sobolev, S G; Shestopalova, N M; Linev, M B; Rubin, S G

1978-01-01

Electron microscopic examinations of brains of white mice inoculated with the An 750 strain isolated for the first time from adult mosquitoes and with the prototype LB strain of Powassan virus were carried out. The method of combination of light and electron microscopy used in the study permitted to compare ultrastructural changes in one cell with the results of light microscopy. Sizes of virions and their localizations in the brain cells were determined. Virus particles were found in large and small neurons as well as in glial elements. Subcellular changes in neurons associated with virus multiplication are described. The causes of differences in sizes of virions measured in ultrathin sections are discussed.

Transmission electron microscopy of the preclinical phase of experimental phytophotodermatitis.

PubMed

Almeida, Hiram Larangeira de; Sotto, Miriam Nakagami; Castro, Luis Antonio Suita de; Rocha, Nara Moreira

2008-06-01

To examine the epidermis in induced phytophotodermatitis using transmission electron microscopy in order to detect histologic changes even before lesions are visible by light microscopy. In the first six hours after the experimental induction of phytophotodermatitis, no changes are detectable by light microscopy. Only after 24 hours can keratinocyte necrosis and epidermal vacuolization be detected histologically, and blisters form by 48 hours. The dorsum of four adult rats (Rattus norvegicus) was manually epilated. After painting the right half of the rat with the peel juice of Tahiti lemon, they were exposed to sunlight for eight minutes under general anesthesia. The left side was used as the control and exposed to sunlight only. Biopsies were performed immediately after photoinduction and one and two hours later, and the tissue was analyzed by transmission electron microscopy. No histological changes were seen on the control side. Immediately after induction, vacuolization in keratinocytes was observed. After one hour, desmosomal changes were also observed in addition to vacuolization. Keratin filaments were not attached to the desmosomal plaque. Free desmosomes and membrane ruptures were also seen. At two hours after induction, similar changes were found, and granular degeneration of keratin was also observed. The interaction of sunlight and psoralens generates a photoproduct that damages keratinocyte proteins, leading to keratinocyte necrosis and blister formation. Transmission electron microscopy can detect vacuolization, lesions of the membrane, and desmosomes in the first two hours after experimental induction of phytophotodermatitis.

Capturing the Surface Texture and Shape of Pollen: A Comparison of Microscopy Techniques

PubMed Central

Sivaguru, Mayandi; Mander, Luke; Fried, Glenn; Punyasena, Surangi W.

2012-01-01

Research on the comparative morphology of pollen grains depends crucially on the application of appropriate microscopy techniques. Information on the performance of microscopy techniques can be used to inform that choice. We compared the ability of several microscopy techniques to provide information on the shape and surface texture of three pollen types with differing morphologies. These techniques are: widefield, apotome, confocal and two-photon microscopy (reflected light techniques), and brightfield and differential interference contrast microscopy (DIC) (transmitted light techniques). We also provide a first view of pollen using super-resolution microscopy. The three pollen types used to contrast the performance of each technique are: Croton hirtus (Euphorbiaceae), Mabea occidentalis (Euphorbiaceae) and Agropyron repens (Poaceae). No single microscopy technique provided an adequate picture of both the shape and surface texture of any of the three pollen types investigated here. The wavelength of incident light, photon-collection ability of the optical technique, signal-to-noise ratio, and the thickness and light absorption characteristics of the exine profoundly affect the recovery of morphological information by a given optical microscopy technique. Reflected light techniques, particularly confocal and two-photon microscopy, best capture pollen shape but provide limited information on very fine surface texture. In contrast, transmitted light techniques, particularly differential interference contrast microscopy, can resolve very fine surface texture but provide limited information on shape. Texture comprising sculptural elements that are spaced near the diffraction limit of light (∼250 nm; NDL) presents an acute challenge to optical microscopy. Super-resolution structured illumination microscopy provides data on the NDL texture of A. repens that is more comparable to textural data from scanning electron microscopy than any other optical microscopy technique investigated here. Maximizing the recovery of morphological information from pollen grains should lead to more robust classifications, and an increase in the taxonomic precision with which ancient vegetation can be reconstructed. PMID:22720050

Microcircuit testing and fabrication, using scanning electron microscopes

NASA Technical Reports Server (NTRS)

Nicolas, D. P.

1975-01-01

Scanning electron microscopes are used to determine both user-induced damages and manufacturing defects subtle enough to be missed by conventional light microscopy. Method offers greater depth of field and increased working distances.

Degradation of Methylammonium Lead Iodide Perovskite Structures through Light and Electron Beam Driven Ion Migration

PubMed Central

2016-01-01

Organometal halide perovskites show promising features for cost-effective application in photovoltaics. The material instability remains a major obstacle to broad application because of the poorly understood degradation pathways. Here, we apply simultaneous luminescence and electron microscopy on perovskites for the first time, allowing us to monitor in situ morphology evolution and optical properties upon perovskite degradation. Interestingly, morphology, photoluminescence (PL), and cathodoluminescence of perovskite samples evolve differently upon degradation driven by electron beam (e-beam) or by light. A transversal electric current generated by a scanning electron beam leads to dramatic changes in PL and tunes the energy band gaps continuously alongside film thinning. In contrast, light-induced degradation results in material decomposition to scattered particles and shows little PL spectral shifts. The differences in degradation can be ascribed to different electric currents that drive ion migration. Moreover, solution-processed perovskite cuboids show heterogeneity in stability which is likely related to crystallinity and morphology. Our results reveal the essential role of ion migration in perovskite degradation and provide potential avenues to rationally enhance the stability of perovskite materials by reducing ion migration while improving morphology and crystallinity. It is worth noting that even moderate e-beam currents (86 pA) and acceleration voltages (10 kV) readily induce significant perovskite degradation and alter their optical properties. Therefore, attention has to be paid while characterizing such materials using scanning electron microscopy or transmission electron microscopy techniques. PMID:26804213

Breaking resolution limits in ultrafast electron diffraction and microscopy

PubMed Central

Baum, Peter; Zewail, Ahmed H.

2006-01-01

Ultrafast electron microscopy and diffraction are powerful techniques for the study of the time-resolved structures of molecules, materials, and biological systems. Central to these approaches is the use of ultrafast coherent electron packets. The electron pulses typically have an energy of 30 keV for diffraction and 100–200 keV for microscopy, corresponding to speeds of 33–70% of the speed of light. Although the spatial resolution can reach the atomic scale, the temporal resolution is limited by the pulse width and by the difference in group velocities of electrons and the light used to initiate the dynamical change. In this contribution, we introduce the concept of tilted optical pulses into diffraction and imaging techniques and demonstrate the methodology experimentally. These advances allow us to reach limits of time resolution down to regimes of a few femtoseconds and, possibly, attoseconds. With tilted pulses, every part of the sample is excited at precisely the same time as when the electrons arrive at the specimen. Here, this approach is demonstrated for the most unfavorable case of ultrafast crystallography. We also present a method for measuring the duration of electron packets by autocorrelating electron pulses in free space and without streaking, and we discuss the potential of tilting the electron pulses themselves for applications in domains involving nuclear and electron motions. PMID:17056711

Attosecond electron pulses for 4D diffraction and microscopy

PubMed Central

Baum, Peter; Zewail, Ahmed H.

2007-01-01

In this contribution, we consider the advancement of ultrafast electron diffraction and microscopy to cover the attosecond time domain. The concept is centered on the compression of femtosecond electron packets to trains of 15-attosecond pulses by the use of the ponderomotive force in synthesized gratings of optical fields. Such attosecond electron pulses are significantly shorter than those achievable with extreme UV light sources near 25 nm (≈50 eV) and have the potential for applications in the visualization of ultrafast electron dynamics, especially of atomic structures, clusters of atoms, and some materials. PMID:18000040

Ultrastructural pathogenesis of lesions produced by exposure to oxygen difluoride with correlative light microscopy

NASA Technical Reports Server (NTRS)

Harrison, G.; Mackenzie, W.

1973-01-01

The lungs of rats exposed to OF2 were examined by light and electron microscopy. The exposures were for 30 to 60 minutes to an average of 4.5 ppm OF2, the minimal lethal dose. Animals were sacrificed after 30 (group 1) and 60 minutes (group 2) exposure and 1 (group 3) and 2 (group 4) hours following 60 minutes exposure. Mild gross changes were observed in groups 3 and 4, but no light microscopic lesions were found. Alterations were noted in all four groups using electron microscopy. These were mostly indicative of fluid change and consisted of blebbing of the endothelial and epithelial layers of the alveolocapillary wall and rarification of the cytoplasm of these cells. The lamellar bodies of the Type II cells showed an increasing and consistent loss of matrix structure and density. These fine structural changes increased in quantity and severity as time of exposure or post-exposure period increased. (Modified author abstract)

Comparison of selective staining of fungi in paraffin sections by light microscopy, SEM and BEI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berman, E.L.; Laudate, A.; Carter, H.W.

Paraffin-embedded sections from human tissues with fungi or organisms classified with fungi were studied by light microscopy (LM), scanning electron microscopy (SEM), and the backscatter electron imaging (BEI) mode of the SEM. The fungal organisms selected for study were those familiar to the pathologist on the basis of their appearance in paraffin-embedded material stained with the Gomori-Grocott Chromic Acid Methenamine Silver Stain (GMS). The organisms were Actinomyces, Rhizopus, Cryptococcus, Histoplasma capsulatum, and Coccidia imitis. Sections were stained with the GMS Stain and/or the Becker modification of the GMS Stain (BGMS) and examined in the secondary electron imaging mode (SEI) andmore » BEI mode with an annular backscatter electron detector. This silver staining technique accentuated the wall of fungal organisms, in the backscatter mode. Depending on the fungal organism and type of silver stain employed, the GMS seemed the preferable stain. The advantages of SEM over LM were greater depth of focus and potential range of magnifications. BEI may also be used in conjunction with LM stain for microorganisms to establish their presence.« less

Cryogenic coherent X-ray diffraction imaging of biological samples at SACLA: a correlative approach with cryo-electron and light microscopy.

PubMed

Takayama, Yuki; Yonekura, Koji

2016-03-01

Coherent X-ray diffraction imaging at cryogenic temperature (cryo-CXDI) allows the analysis of internal structures of unstained, non-crystalline, whole biological samples in micrometre to sub-micrometre dimensions. Targets include cells and cell organelles. This approach involves preparing frozen-hydrated samples under controlled humidity, transferring the samples to a cryo-stage inside a vacuum chamber of a diffractometer, and then exposing the samples to coherent X-rays. Since 2012, cryo-coherent diffraction imaging (CDI) experiments have been carried out with the X-ray free-electron laser (XFEL) at the SPring-8 Ångstrom Compact free-electron LAser (SACLA) facility in Japan. Complementary use of cryo-electron microscopy and/or light microscopy is highly beneficial for both pre-checking samples and studying the integrity or nature of the sample. This article reports the authors' experience in cryo-XFEL-CDI of biological cells and organelles at SACLA, and describes an attempt towards reliable and higher-resolution reconstructions, including signal enhancement with strong scatterers and Patterson-search phasing.

Imaging the Atomic Position of Light Cations in a Porous Network and the Europium(III) Ion Exchange Capability by Aberration-Corrected Electron Microscopy.

PubMed

Mayoral, Alvaro; Hall, Reece M; Jackowska, Roksana; Readman, Jennifer E

2016-12-23

In the present work, ETS-10 microporous titanosilicate has been synthesized and its structure characterized by means of powder XRD and aberration corrected scanning transmission electron microscopy (C s -corrected STEM). For the first time, sodium ions have been imaged sitting inside the 7-membered rings. The ion-exchange capability has been tested by the inclusion of rare earth metals (Eu, Tb and Gd) to produce a luminescent material which has been studied by atomic-resolution C s -corrected STEM. The data produced has allowed unambiguous imaging of light atoms in a microporous framework as well as determining the cationic metal positions for the first time, providing evidence of the importance of advanced electron microscopy methods for the study of the local environment of metals within zeolitic supports providing unique information of both systems (guest and support) at the same time. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrastructural characters of a Physarum melleum on living leaves of Dendrobium candidum in China*

PubMed Central

Zhang, Jing-ze; Liu, Lu-ning; Fiore-Donno, Anna-Maria; Xu, Tong

2007-01-01

A known species, Physarum melleum, was found fruiting on living leaves of Dendrobium candidum, which was collected in China in 2004. Its morphological characters were revealed by light microscopy (LM), environmental scanning electron microscopy (ESEM) and scanning electron microscopy (SEM). Character variations were distinguished by its olive-yellow peridium and its always thinner capillitium containing globulose granular material between the large calcareous nodes. The calcium carbonate granules, deposited on stalks, peridium and hypothallus as well as within stalks, were globose and smooth. PMID:18257124

A new genus and species of Nematalycidae (Acari: Endeostigmata)

USDA-ARS?s Scientific Manuscript database

Osperalycus tenerphagus, a new genus and species of Nematalycidae (Acari: Endeostigmata), is described from Ohio, USA, using light microscopy and low temperature scanning electron microscopy. Specimens were extracted from two different loam soils. This genus can be readily distinguished from the oth...

Improved Serial Sectioning Techniques for Correlative Light-Electron Microscopy Mapping of Human Langerhans Islets

PubMed Central

Saitoh, Sei; Ohno, Nobuhiko; Saitoh, Yurika; Terada, Nobuo; Shimo, Satoshi; Aida, Kaoru; Fujii, Hideki; Kobayashi, Tetsuro; Ohno, Shinichi

2018-01-01

Combined analysis of immunostaining for various biological molecules coupled with investigations of ultrastructural features of individual cells is a powerful approach for studies of cellular functions in normal and pathological conditions. However, weak antigenicity of tissues fixed by conventional methods poses a problem for immunoassays. This study introduces a method of correlative light and electron microscopy imaging of the same endocrine cells of compact and diffuse islets from human pancreatic tissue specimens. The method utilizes serial sections obtained from Epon-embedded specimens fixed with glutaraldehyde and osmium tetroxide. Double-immunofluorescence staining of thick Epon sections for endocrine hormones (insulin and glucagon) and regenerating islet-derived gene 1 α (REG1α) was performed following the removal of Epoxy resin with sodium ethoxide, antigen retrieval by autoclaving, and de-osmification treatment with hydrogen peroxide. The immunofluorescence images of endocrine cells were superimposed with the electron microscopy images of the same cells obtained from serial ultrathin sections. Immunofluorescence images showed well-preserved secretory granules in endocrine cells, whereas electron microscopy observations demonstrated corresponding secretory granules and intracellular organelles in the same cells. In conclusion, the correlative imaging approach developed by us may be useful for examining ultrastructural features in combination with immunolocalisation of endocrine hormones in the same human pancreatic islets. PMID:29622846

Correlative fractography: combining scanning electron microscopy and light microscopes for qualitative and quantitative analysis of fracture surfaces.

PubMed

Hein, Luis Rogerio de Oliveira; de Oliveira, José Alberto; de Campos, Kamila Amato

2013-04-01

Correlative fractography is a new expression proposed here to describe a new method for the association between scanning electron microscopy (SEM) and light microscopy (LM) for the qualitative and quantitative analysis of fracture surfaces. This article presents a new method involving the fusion of one elevation map obtained by extended depth from focus reconstruction from LM with exactly the same area by SEM and associated techniques, as X-ray mapping. The true topographic information is perfectly associated to local fracture mechanisms with this new technique, presented here as an alternative to stereo-pair reconstruction for the investigation of fractured components. The great advantage of this technique resides in the possibility of combining any imaging methods associated with LM and SEM for the same observed field from fracture surface.

You can't measure what you can't see - detectors for microscopies

NASA Astrophysics Data System (ADS)

Denes, Peter

For centuries, the human eye has been the imaging detector of choice thanks to its high sensitivity, wide dynamic range, and direct connection to a built-in data recording and analysis system. The eye, however, is limited to visible light, which excludes microscopies with electrons and X-rays, and the built-in recording system stores archival information at very low rates. The former limitation has been overcome by ``indirect'' detectors, which convert probe particles to visible light, and the latter by a variety of recording techniques, from photographic film to semiconductor-based imagers. Semiconductor imagers have been used for decades as ``direct'' detectors in particle physics, and almost as long for hard X-rays. For soft X-ray microscopy, the challenge has been the small signal levels - plus getting the X-rays into the detector itself, given how quickly they are absorbed in inert layers. For electron microscopy, the challenge has been reconciling detector spatial resolution and pixel count with the large multiple scattering of electrons with energies used for microscopy. Further, a high recording rate (``movies'' rather than ``snapshots'') enables time-resolved studies, time-dependent corrections, shot-by-shot experiments and scanning techniques - at the expense of creating large data volumes. This talk will discuss solutions to these challenges, as well as an outlook towards future developments.

Electron microscopic identification of the intestinal protozoan flagellates of the xylophagous cockroach Parasphaeria boleiriana from Brazil.

PubMed

Brugerolle, G; Silva-Neto, I D; Pellens, R; Grandcolas, P

2003-06-01

Flagellate protozoa of the hindgut of the xylophagous blattid Parasphaeria boleiriana were examined by light and electron microscopy. This species harbours two oxymonad species of the genera Monocercomonoides and Polymastix, the latter bearing Fusiformis bacteria on its surface. A diplomonad was present and has features of the genus Hexamita rather than Spironucleus. In addition, two trichomonads of the genera Monocercomonas and Tetratrichomastix were identified. A precise comparison with species of blattids and other insects was difficult because most of these flagellates have been described only by light microscopy after cell staining and there are few electron microscope studies and no molecular studies. None of the flagellates contained wood fragments in their food vacuoles and so evidently do not participate in the digestion of wood or cellulose.

Glycogen in the Nervous System. I; Methods for Light and Electron Microscopy

NASA Technical Reports Server (NTRS)

Estable, Rosita F. De; Estable-Puig, J. F.; Miquel, J.

1964-01-01

'l'he relative value of different methods for combined light and electron microscopical studies of glycogen in the nervous tissue was investigated. Picroalcoholic fixatives preserve glycogen in a considerable amount but give an inadequate morphological image of glycogen distribution and are unsuitable for ultrastructural studies. Fixation by perfusion, with Dalton's chromeosmic fluid seems adequate for ultrastructural cytochemistry of glycogen. Furthermore it permits routine paraffin embedding of brain slices adjacent to those used for electron microscopy. Dimedone blocking is a necessary step for a selective staining of glycogen with PAS after osmic fixation. Enzymatic removal of glycogen in osmic fixed nervous tissue can be done In paraffin-embedded tissue. It can also be performed in glycolmethacrylate-embedded tissue without removal of the embedding medium. Paraphenylenediamine stains glycogen following periodic acid oxidation.

Asymmetric Flow-Field Flow Fractionation (AF4) of Aqueous C60 Aggregates with Dynamic Light Scattering Size and LC-MS

EPA Science Inventory

Current methods for the size determination of nanomaterials in aqueous suspension include dynamic or static light scattering and electron or atomic force microscopy techniques. Light scattering techniques are limited by poor resolution and the scattering intensity dependence on p...

Click-electron microscopy for imaging metabolically tagged non-protein biomolecules

PubMed Central

Ngo, John T.; Adams, Stephen R.; Deerinck, Thomas J.; Boassa, Daniela; Rodriguez-Rivera, Frances; Palida, Sakina F.; Bertozzi, Carolyn R.; Ellisman, Mark H.; Tsien, Roger Y.

2016-01-01

Electron microscopy (EM) has long been the main technique to image cell structures with nanometer resolution, but has lagged behind light microscopy in the crucial ability to make specific molecules stand out. Here we introduce “Click-EM,” a labeling technique for correlative light microscopy and EM imaging of non-protein biomolecules. In this approach, metabolic labeling substrates containing bioorthogonal functional groups are provided to cells for incorporation into biopolymers by endogenous biosynthetic machinery. The unique chemical functionality of these analogs is exploited for selective attachment of singlet oxygen-generating fluorescent dyes via bioorthogonal “click chemistry” ligations. Illumination of dye-labeled structures generates singlet oxygen to locally catalyze the polymerization of diaminobenzidine into an osmiophilic reaction product that is readily imaged by EM. We describe the application of Click-EM in imaging metabolically tagged DNA, RNA, and lipids in cultured cells and neurons, and highlight its use in tracking peptidoglycan synthesis in the Gram-positive bacterium Listeria monocytogenes. PMID:27110681

Nitrogen Doped Graphene Nickel Ferrite Magnetic Photocatalyst for the Visible Light Degradation of Methylene Blue.

PubMed

Singh, Rajinder; Ladol, Jigmet; Khajuria, Heena; Sheikh, Haq Nawaz

2017-01-01

A facile approach has been devised for the preparation of magnetic NiFe2O4 photocatalyst (NiFe2O4-NG) supported on nitrogen doped graphene (NG). The NiFe2O4-NG composite was synthesized by one step hydrothermal method. The nanocomposite catalyst was characterized by Powder X-ray diffraction (PXRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Ultraviolet-visible spectroscopy (UV-Vis) and Vibrating sample magnetometry (VSM). It is found that the combination of NiFe2O4 nanoparticles with nitrogen-doped graphene sheets converts NiFe2O4 into a good catalyst for methylene blue (MB) dye degradation by irradiation of visible light. The catalytic activity under visible light irradiation is assigned to extensive movement of photogenerated electron from NiFe2O4 to the conduction band of the reduced NG, effectively blocking direct recombination of electrons and holes. The NiFe2O4 nanoparticles alone have efficient magnetic property, so can be used for magnetic separation in the solution without additional magnetic support.

Simple route to (NH4)xWO3 nanorods for near infrared absorption

NASA Astrophysics Data System (ADS)

Guo, Chongshen; Yin, Shu; Dong, Qiang; Sato, Tsugio

2012-05-01

Described here is how to synthesize one-dimensional ammonium tungsten bronze ((NH4)xWO3) by a facile solvothermal approach in which ethylene glycol and acetic acid were employed as solvents and ammonium paratungstate was used as a starting material, as well as how to develop the near infrared absorption properties of (NH4)xWO3 nanorods for application as a solar light control filter. The as-obtained product was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), atomic force microscope (AFM) and UV-Vis-NIR spectra. The SEM and TEM images clearly revealed that the obtained sample possessed rod/fiber-like morphologies with diameters around 120 nm. As determined by UV-Vis-NIR optical measurement, the thin film consisted of (NH4)xWO3 nanoparticles, which can selectively transmit most visible lights, but strongly absorb the near-infrared (NIR) lights and ultraviolet rays. These interesting optical properties make the (NH4)xWO3 nanorods suitable for the solar control windows.Described here is how to synthesize one-dimensional ammonium tungsten bronze ((NH4)xWO3) by a facile solvothermal approach in which ethylene glycol and acetic acid were employed as solvents and ammonium paratungstate was used as a starting material, as well as how to develop the near infrared absorption properties of (NH4)xWO3 nanorods for application as a solar light control filter. The as-obtained product was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry (TG), atomic force microscope (AFM) and UV-Vis-NIR spectra. The SEM and TEM images clearly revealed that the obtained sample possessed rod/fiber-like morphologies with diameters around 120 nm. As determined by UV-Vis-NIR optical measurement, the thin film consisted of (NH4)xWO3 nanoparticles, which can selectively transmit most visible lights, but strongly absorb the near-infrared (NIR) lights and ultraviolet rays. These interesting optical properties make the (NH4)xWO3 nanorods suitable for the solar control windows. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30612c

Insights into the prominent effect of mahanimbine on Acanthamoeba castellanii: Cell profiling analysis based on microscopy techniques

NASA Astrophysics Data System (ADS)

Hashim, Fatimah; Amin, Nakisah Mat

2017-02-01

Mahanimbine (MH), has been shown to have antiamoeba properties. Therefore, the aim of this study was to assess the growth inhibitory mechanisms of MH on Acanthamoeba castellanii, a causative agents for Acanthamoeba keratitis. The IC50 value obtained for MH against A. castellanii was 1.18 µg/ml. Light and scanning electron microscopy observation showed that most cells were in cystic appearance. While transmission electron microscopy observation revealed changes at the ultrastructural level and fluorescence microscopy observation indicated the induction of apoptosis and autophagic activity in the amoeba cytoplasms. In conclusion, MH has very potent anti-amoebic properties on A. castellanii as is shown by cytotoxicity analyses based on microscopy techniques.

Synthesis of MoS2/rGO nanosheets hybrid materials for enhanced visible light assisted photocatalytic activity

NASA Astrophysics Data System (ADS)

Pal, Shreyasi; Dutta, Shibsankar; De, Sukanta

2018-04-01

A facile hydrothermal method has been adopted to synthesize pure MoS2 nanosheets and MoS2/rGO nanosheets hybrid. The samples were characterized using field emission scanning electron microscopy (FESEM), transmission electron microscopy (HRTEM), X-ray diffraction spectroscopy (XRD), Brunauer-Emmett-Teller (BET). The photocatalytic performance and reusability of MoS2 nanosheets and MoS2/rGO hybrids was evaluated by discoloring of RhB under visible light irradiation. Results indicated that MoS2/rGO photocatalysts with large surface area of 69.5 m2 g-1 could completely degrade 50 mL of 8 mg L-1 RhB aqueous solution in 90 min with excellent recycling and structural stability as compared with pure MoS2 nanosheets (53%). Such enhanced performance could be explained due to the high surface area, enhanced light absorption and the increased dye adsorptivity and reduced electron-hole pair recombination with the presence of rGO.

Polarized light and scanning electron microscopic investigation of enamel hypoplasia in primary teeth.

PubMed

Sabel, Nina; Klingberg, Gunilla; Dietz, Wolfram; Nietzsche, Sandor; Norén, Jörgen G

2010-01-01

Enamel hypoplasia is a developmental disturbance during enamel formation, defined as a macroscopic defect in the enamel, with a reduction of the enamel thickness with rounded, smooth borders. Information on the microstructural level is still limited, therefore further studies are of importance to better understand the mechanisms behind enamel hypoplasia. To study enamel hypoplasia in primary teeth by means of polarized light microscopy and scanning electron microscopy. Nineteen primary teeth with enamel hypoplasia were examined in a polarized light microscope and in a scanning electron microscope. The cervical and incisal borders of the enamel hypoplasia had a rounded appearance, as the prisms in the rounded cervical area of the hypoplasia were bent. The rounded borders had a normal surface structure whereas the base of the defects appeared rough and porous. Morphological findings in this study indicate that the aetiological factor has a short duration and affects only certain ameloblasts. The bottom of the enamel hypoplasia is porous and constitutes possible pathways for bacteria into the dentin.

Biomechanical and Histopathologic Effects of Pulsed-Light Accelerated Epithelium-On/-Off Corneal Collagen Cross-Linking.

PubMed

Zhang, Xiaoyu; Sun, Ling; Shen, Yang; Tian, Mi; Zhao, Jing; Zhao, Yu; Li, Meiyan; Zhou, Xingtao

2017-07-01

This study aimed to compare the biomechanical and histopathologic effects of transepithelial and accelerated epithelium-off pulsed-light accelerated corneal collagen cross-linking (CXL). A total of 24 New Zealand rabbits were analyzed after sham operation (control) or transepithelial or epithelium-off operation (45 mW/cm for both). The transepithelial group was treated with pulsed-light ultraviolet A for 5 minutes 20 seconds, and the epithelium-off group was treated for 90 seconds. Biomechanical testing, including ultimate stress, Young modulus, and the physiological modulus, was analyzed. Histological changes were evaluated by light microscopy and transmission electron microscopy. The stress-strain curve was nonlinear in both accelerated transepithelial and epithelium-off CXL groups. The stress and elastic moduli were all significantly higher in both experimental groups compared with the control group (P < 0.05), whereas there were no significant differences between the 2 treatment groups (P > 0.05). Six months after the operation, hematoxylin and eosin staining and transmission electron microscopy showed that the subcutaneous collagen fibers were arranged in a regular pattern, and the fiber density was higher in the experimental groups. Both transepithelial and accelerated epithelium-off CXL produced biomechanical and histopathologic improvements, which were not significantly different between the 2 pulsed-light accelerated CXL treatments.

Soft-template synthesis of single-crystalline CdS dendrites.

PubMed

Niu, Haixia; Yang, Qing; Tang, Kaibin; Xie, Yi; Zhu, Yongchun

2006-01-01

The single-crystalline CdS dendrites have been fabricated from the reaction of CdCl2 and thiourea at 180 degrees C, in which glycine was employed as a soft template. The obtained products were explored by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and selected area electronic diffraction. The optical properties of CdS dendrites have been investigated by ultraviolet and visible light (UV-vis) and photoluminescence techniques. The investigations indicated that the dendrites were grown due to the anisotropic properties enhanced by the use of Glycine in the route.

Follicular dysplasia in five Weimaraners.

PubMed

Laffort-Dassot, Catherine; Beco, Luc; Carlotti, Didier Noel

2002-10-01

This study evaluated the clinical and histopathological features and results of light and electron scanning microscopy assessments of follicular dysplasia in five Weimar Pointers. The data were compared with those obtained in three normal Weimaraners. In our study, this dermatosis affected young adults that showed progressive alopecia of the trunk (head and limbs were spared) associated with recurrent folliculitis/furunculosis. Exclusion of other dermatoses and the presence of histopathological lesions and hair shafts abnormalities seen in light and/or scanning electron microscopy similar to colour dilution alopecia led to the diagnosis of follicular dysplasia. The lesions we observed are the same as those described previously in colour dilution alopecia, but they were less pronounced in all our samples.

Curcumin Inhibits Tau Aggregation and Disintegrates Preformed Tau Filaments in vitro.

PubMed

Rane, Jitendra Subhash; Bhaumik, Prasenjit; Panda, Dulal

2017-01-01

The pathological aggregation of tau is a common feature of most of the neuronal disorders including frontotemporal dementia, Parkinson's disease, and Alzheimer's disease. The inhibition of tau aggregation is considered to be one of the important strategies for treating these neurodegenerative diseases. Curcumin, a natural polyphenolic molecule, has been reported to have neuroprotective ability. In this work, curcumin was found to bind to adult tau and fetal tau with a dissociation constant of 3.3±0.4 and 8±1 μM, respectively. Molecular docking studies indicated a putative binding site of curcumin in the microtubule-binding region of tau. Using several complementary techniques, including dynamic light scattering, thioflavin S fluorescence, 90° light scattering, electron microscopy, and atomic force microscopy, curcumin was found to inhibit the aggregation of tau. The dynamic light scattering analysis and atomic force microscopic images revealed that curcumin inhibits the oligomerization of tau. Curcumin also disintegrated preformed tau oligomers. Using Far-UV circular dichroism, curcumin was found to inhibit the β-sheets formation in tau indicating that curcumin inhibits an initial step of tau aggregation. In addition, curcumin inhibited tau fibril formation. Furthermore, the effect of curcumin on the preformed tau filaments was analyzed by atomic force microscopy, transmission electron microscopy, and 90° light scattering. Curcumin treatment disintegrated preformed tau filaments. The results indicated that curcumin inhibited the oligomerization of tau and could disaggregate tau filaments.

Ag(I)-bovine serum albumin hydrosol-mediated formation of Ag3PO4/reduced graphene oxide composites for visible-light degradation of Rhodamine B solution.

PubMed

Ma, Peiyan; Chen, Anliang; Wu, Yan; Fu, Zhengyi; Kong, Wei; Che, Liyuan; Ma, Ruifang

2014-03-01

A cost-effective Ag(I)-bovine serum albumin (BSA) supramolecular hydrosol strategy was utilized to assemble Ag3PO4 nanospheres onto reduced graphene oxide (rGO) sheets. The obtained composites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy and Fourier transform infrared spectroscopy. Compared with the pure Ag3PO4 crystals and Ag3PO4 particles prepared with Ag(I)-BSA hydrosol as precursor, the Ag3PO4/rGO composites obtained with different content of graphene oxide indicated improved visible-light-driven photocatalysis activity for the decomposition of Rhodamine B aqueous solution. The results pointed to the possibility of synthesizing graphene-based photocatalysts by metal ion-BSA hydrosol. Copyright © 2013 Elsevier Inc. All rights reserved.

Rose bengal-grafted biodegradable microcapsules: singlet-oxygen generation and cancer-cell incapacitation.

PubMed

Wang, Xiao-Lei; Zeng, Yu; Zheng, Yan-Zhen; Chen, Jian-Feng; Tao, Xia; Wang, Ling-Xuan; Teng, Yan

2011-09-26

Rose bengal-grafted chitosan (RB-CHI), synthesized through dehydration between amino and carboxyl functional groups under mild conditions, was coated onto the outer layer of preformed biodegradable microcapsules consisting of sodium alginate and chitosan. The fabricated photosensitive microcapsules were characterized by optical microscopy, scanning electron microscopy, and confocal laser scanning microscopy. The assembled materials maintained intact spherical morphology and thus showed good ability to form thin films. Electron spin resonance spectroscopy allowed direct observation of the generation of singlet oxygen ((1)O(2)) from photosensitive microcapsules under light excitation at about 545 nm. Furthermore, with increasing light radiation, the content of (1)O(2) increased, as detected by a chemical probe. In vitro cellular toxicity assays showed that RB-CHI-coated photosensitive microcapsules exhibit good biocompatibility in darkness and high cytotoxicity after irradiation, and could provide new photoresponsive drug-delivery vehicles. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simulation of bone resorption-repair coupling in vitro.

PubMed

Jones, S J; Gray, C; Boyde, A

1994-10-01

In the normal adult human skeleton, new bone formation by osteoblasts restores the contours of bone surfaces following osteoclastic bone resorption, but the evidence for resorption-repair coupling remains circumstantial. To investigate whether sites of prior resorption, more than the surrounding unresorbed surface, attract osteoblasts or stimulate them to proliferate or make new matrix, we developed a simple in vitro system in which resorption-repair coupling occurs. Resorption pits were produced in mammalian dentine or bone slabs by culturing chick bone-derived cells on them for 2-3 days. The chick cells were swept off and the substrata reseeded with rat calvarial osteoblastic cells, which make bone nodules in vitro, for periods of up to 8 weeks. Cell positions and new bone formation were investigated by ordinary light microscopy, fluorescence and reflection confocal laser microscopy, and SEM, in stained and unstained samples. There was no evidence that the osteoblasts were especially attracted to, or influenced by, the sites of resorption in dentine or bone before cell confluence was reached. Bone formation was identified by light microscopy by the accumulation of matrix, staining with alizarin and calcein and by von Kossa's method, and confirmed by scanning electron microscopy (SEM) by using backscattered electron (BSE) and transmitted electron imaging of unembedded samples and BSE imaging of micro-milled embedded material. These new bone patches were located initially in the resorption pits. The model in vitro system may throw new light on the factors that control resorption-repair coupling in the mineralised tissues in vivo.

Oscheius wisconsinensis n. sp. (Nematoda: Rhabditidae), a potential entomopathogenic nematode from the marshlands of Wisconsin

USDA-ARS?s Scientific Manuscript database

Oscheius wisconsinensis n. sp. (Rhabditidae) was recovered through the Galleria bait method from a wild cranberry marsh in Jackson County, Wisconsin, USA. Morphological studies with light microscopy and scanning electron microscopy, as well as molecular analyses of the near-full-length small subunit...

Application of SEM and EDX in studying biomineralization in plant tissues.

PubMed

He, Honghua; Kirilak, Yaowanuj

2014-01-01

This chapter describes protocols using formalin-acetic acid-alcohol (FAA) to fix plant tissues for studying biomineralization by means of scanning electron microscopy (SEM) and qualitative energy-dispersive X-ray microanalysis (EDX). Specimen preparation protocols for SEM and EDX mainly include fixation, dehydration, critical point drying (CPD), mounting, and coating. Gold-coated specimens are used for SEM imaging, while gold- and carbon-coated specimens are prepared for qualitative X-ray microanalyses separately to obtain complementary information on the elemental compositions of biominerals. During the specimen preparation procedure for SEM, some biominerals may be dislodged or scattered, making it difficult to determine their accurate locations, and light microscopy is used to complement SEM studies. Specimen preparation protocols for light microscopy generally include fixation, dehydration, infiltration and embedding with resin, microtome sectioning, and staining. In addition, microwave processing methods are adopted here to speed up the specimen preparation process for both SEM and light microscopy.

Impact of New Camera Technologies on Discoveries in Cell Biology.

PubMed

Stuurman, Nico; Vale, Ronald D

2016-08-01

New technologies can make previously invisible phenomena visible. Nowhere is this more obvious than in the field of light microscopy. Beginning with the observation of "animalcules" by Antonie van Leeuwenhoek, when he figured out how to achieve high magnification by shaping lenses, microscopy has advanced to this day by a continued march of discoveries driven by technical innovations. Recent advances in single-molecule-based technologies have achieved unprecedented resolution, and were the basis of the Nobel prize in Chemistry in 2014. In this article, we focus on developments in camera technologies and associated image processing that have been a major driver of technical innovations in light microscopy. We describe five types of developments in camera technology: video-based analog contrast enhancement, charge-coupled devices (CCDs), intensified sensors, electron multiplying gain, and scientific complementary metal-oxide-semiconductor cameras, which, together, have had major impacts in light microscopy. © 2016 Marine Biological Laboratory.

High Prevalence of Human Liver Infection by Amphimerus spp. Flukes, Ecuador

PubMed Central

Calvopiña, Manuel; Cevallos, William; Kumazawa, Hideo; Eisenberg, Joseph

2011-01-01

Amphimerus spp. flukes are known to infect mammals, but human infections have not been confirmed. Microscopy of fecal samples from 397 persons from Ecuador revealed Opisthorchiidae eggs in 71 (24%) persons. Light microscopy of adult worms and scanning electron microscopy of eggs were compatible with descriptions of Amphimerus spp. This pathogen was only observed in communities that consumed undercooked fish. PMID:22172165

Nano-Se: Cheap and easy-to-obtain novel material for all-dielectric nano-photonics

NASA Astrophysics Data System (ADS)

Ivanova, A. K.; Ionin, A. A.; Khmel'nitskii, R. A.; Klevkov, Yu. K.; Kudryashov, S. I.; Levchenko, A. O.; Mel'nik, N. N.; Nastulyavichus, A. A.; Rudenko, A. A.; Saraeva, I. N.; Smirnov, N. A.; Zayarny, D. A.; Gonchukov, S. A.; Tolordava, E. R.; Baranov, A. N.

2017-09-01

Milligram-per-second production of selenium nanoparticles in water sols was realized through few W, kHz-rate nanosecond laser ablation of a solid selenium pellet. High-yield particle formation mechanism and ultimate mass-removal yield were elucidated by optical profilometry and scanning electron microscopy characterization of crater depths and topographies. Deposited particles were inspected by scanning electron microscopy, while optical transmission Raman and dynamic light scattering spectroscopy characterized their hydrosols.

Endolithic algae and micrite envelope formation in Bahamian oolites as revealed by scanning electron microscopy.

NASA Technical Reports Server (NTRS)

Margolis, S.; Rex, R. W.

1971-01-01

Examination of Holocene Bahamian ooelites by scanning electron and light microscopy has revealed the morphology and orientation of aragonite crystals in the lamellar ooelitic envelope, and their modification by the boring activities of endolithic algae. The voids produced by these algae are found in progressive stages of being lined and filled with precipitated microcrystalline aragonite, which is similar to the process of micrite envelope formation in molluscan and other skeletal carbonate grains.

Shedding light on cell compartmentation in the candidate phylum Poribacteria by high resolution visualisation and transcriptional profiling

NASA Astrophysics Data System (ADS)

Jahn, Martin T.; Markert, Sebastian M.; Ryu, Taewoo; Ravasi, Timothy; Stigloher, Christian; Hentschel, Ute; Moitinho-Silva, Lucas

2016-10-01

Assigning functions to uncultivated environmental microorganisms continues to be a challenging endeavour. Here, we present a new microscopy protocol for fluorescence in situ hybridisation-correlative light and electron microscopy (FISH-CLEM) that enabled, to our knowledge for the first time, the identification of single cells within their complex microenvironment at electron microscopy resolution. Members of the candidate phylum Poribacteria, common and uncultivated symbionts of marine sponges, were used towards this goal. Cellular 3D reconstructions revealed bipolar, spherical granules of low electron density, which likely represent carbon reserves. Poribacterial activity profiles were retrieved from prokaryotic enriched sponge metatranscriptomes using simulation-based optimised mapping. We observed high transcriptional activity for proteins related to bacterial microcompartments (BMC) and we resolved their subcellular localisation by combining FISH-CLEM with immunohistochemistry (IHC) on ultra-thin sponge tissue sections. In terms of functional relevance, we propose that the BMC-A region may be involved in 1,2-propanediol degradation. The FISH-IHC-CLEM approach was proven an effective toolkit to combine -omics approaches with functional studies and it should be widely applicable in environmental microbiology.

Asymmetrical flow field-flow fractionation with multi-angle light scattering and quasi-elastic light scattering for characterization of polymersomes: comparison with classical techniques.

PubMed

Till, Ugo; Gaucher-Delmas, Mireille; Saint-Aguet, Pascale; Hamon, Glenn; Marty, Jean-Daniel; Chassenieux, Christophe; Payré, Bruno; Goudounèche, Dominique; Mingotaud, Anne-Françoise; Violleau, Frédéric

2014-12-01

Polymersomes formed from amphiphilic block copolymers, such as poly(ethyleneoxide-b-ε-caprolactone) (PEO-b-PCL) or poly(ethyleneoxide-b-methylmethacrylate), were characterized by asymmetrical flow field-flow fractionation coupled with quasi-elastic light scattering (QELS), multi-angle light scattering (MALS), and refractive index detection, leading to the determination of their size, shape, and molecular weight. The method was cross-examined with more classical ones, like batch dynamic and static light scattering, electron microscopy, and atomic force microscopy. The results show good complementarities between all the techniques; asymmetrical flow field-flow fractionation being the most pertinent one when the sample exhibits several different types of population.

Utility of fluorescence microscopy in embryonic/fetal topographical analysis.

PubMed

Zucker, R M; Elstein, K H; Shuey, D L; Ebron-McCoy, M; Rogers, J M

1995-06-01

For topographical analysis of developing embryos, investigators typically rely on scanning electron microscopy (SEM) to provide the surface detail not attainable with light microscopy. SEM is an expensive and time-consuming technique, however, and the preparation procedure may alter morphology and leave the specimen friable. We report that by using a high-resolution compound epifluorescence microscope with inexpensive low-power objectives and the fluorochrome acridine orange, we were able to obtain surface images of fixed or fresh whole rat embryos and fetal palates of considerably greater topographical detail than those obtained using routine light microscopy. Indeed the resulting high-resolution images afford not only superior qualitative documentation of morphological observations, but the capability for detailed morphometry via digitization and computer-assisted image analysis.

An historical account of the development and applications of the negative staining technique to the electron microscopy of viruses.

PubMed

Horne, R W; Wildy, P

1979-09-01

A brief historical account of the development and applications of the negative staining techniques to the study of the structure of viruses and their components as observed in the electron microscope is presented. Although the basic method of surrounding or embedding specimens in opaque dyes was used in light microscopy dating from about 1884, the equivalent preparative techniques applied to electron microscopy were comparatively recent. The combination of experiments on a sophisticated bacterial virus and the installation of a high resolution electron microscope in the Cavendish Laboratory, Cambridge, during 1954, subsequently led to the analysis of several important morphological features of animal, plant and bacterial viruses. The implications of the results from these early experiments on viruses and recent developments in negative staining methods for high resolution image analysis of electron micrographs are also discussed.

Modified microwave method for the synthesis of visible light-responsive TiO2/MWCNTs nanocatalysts

PubMed Central

2013-01-01

Recently, TiO2/multi-walled carbon nanotube (MWCNT) hybrid nanocatalysts have been a subject of high interest due to their excellent structures, large surface areas and peculiar optical properties, which enhance their photocatalytic performance. In this work, a modified microwave technique was used to rapidly synthesise a TiO2/MWCNT nanocatalyst with a large surface area. X-ray powder diffraction, field-emission scanning electron microscopy, transmission electron microscopy and Brunauer-Emmett-Teller measurements were used to characterise the structure, morphology and the surface area of the sample. The photocatalytic activity of the hybrid nanocatalysts was evaluated through a comparison of the degradation of methylene blue dye under irradiation with ultraviolet and visible light. The results showed that the TiO2/MWCNT hybrid nanocatalysts degraded 34.9% of the methylene blue (MB) under irradiation with ultraviolet light, whereas 96.3% of the MB was degraded under irradiation with visible light. PMID:23919496

Enhanced light element imaging in atomic resolution scanning transmission electron microscopy.

PubMed

Findlay, S D; Kohno, Y; Cardamone, L A; Ikuhara, Y; Shibata, N

2014-01-01

We show that an imaging mode based on taking the difference between signals recorded from the bright field (forward scattering region) in atomic resolution scanning transmission electron microscopy provides an enhancement of the detectability of light elements over existing techniques. In some instances this is an enhancement of the visibility of the light element columns relative to heavy element columns. In all cases explored it is an enhancement in the signal-to-noise ratio of the image at the light column site. The image formation mechanisms are explained and the technique is compared with earlier approaches. Experimental data, supported by simulation, are presented for imaging the oxygen columns in LaAlO₃. Case studies looking at imaging hydrogen columns in YH₂ and lithium columns in Al₃Li are also explored through simulation, particularly with respect to the dependence on defocus, probe-forming aperture angle and detector collection aperture angles. © 2013 Elsevier B.V. All rights reserved.

Synthesis and characterization of CdS-based ternary composite for enhanced visible light-driven photocatalysis

NASA Astrophysics Data System (ADS)

Singh, Arvind; Sinha, A. S. K.

2018-09-01

Active ternary graphite and alumina-supported cadmium sulphide (CdS) composite was synthesized by impregnation method followed by high-temperature solid-gas reaction and characterized by X-ray diffraction (XRD), photoluminescence spectroscopy (PL), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) techniques. The ternary CdS-graphite-alumina composite exhibited superior catalytic activity compared with the binary CdS-alumina composite due to its better visible-light absorption and higher charge separation. The ternary composite has a bed-type structure. It permits a greater interaction at the interface due to intimate contact between CdS and graphite in the ternary composite. This composite has a highly efficient visible light-driven photocatalytic activity for sustainable hydrogen production. It is also capable of degrading organic dyes in wastewater.

Preparation, characterization and photocatalytic behavior of WO3-fullerene/TiO2 catalysts under visible light

PubMed Central

2011-01-01

WO3-treated fullerene/TiO2 composites (WO3-fullerene/TiO2) were prepared using a sol-gel method. The composite obtained was characterized by BET surface area measurements, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy, and UV-vis analysis. A methyl orange (MO) solution under visible light irradiation was used to determine the photocatalytic activity. Excellent photocatalytic degradation of a MO solution was observed using the WO3-fullerene, fullerene-TiO2, and WO3-fullerene/TiO2 composites under visible light. An increase in photocatalytic activity was observed, and WO3-fullerene/TiO2 has the best photocatalytic activity; it may attribute to the increase of the photo-absorption effect by the fullerene and the cooperative effect of the WO3. PMID:21774800

Enhanced photocatalytic activity of ZnO/CuO nanocomposite for the degradation of textile dye on visible light illumination.

PubMed

Saravanan, R; Karthikeyan, S; Gupta, V K; Sekaran, G; Narayanan, V; Stephen, A

2013-01-01

The photocatalytic degradation of organic dyes such as methylene blue and methyl orange in the presence of various percentages of composite catalyst under visible light irradiation was carried out. The catalyst ZnO nanorods and ZnO/CuO nanocomposites of different weight ratios were prepared by new thermal decomposition method, which is simple and cost effective. The prepared catalysts were characterized by different techniques such as X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and UV-visible absorption spectroscopy. Further, the most photocatalytically active composite material was used for degradation of real textile waste water under visible light illumination. The irradiated samples were analysed by total organic carbon and chemical oxygen demand. The efficiency of the catalyst and their photocatalytic mechanism has been discussed in detail. Copyright © 2012 Elsevier B.V. All rights reserved.

Aharonov-Bohm Effect in the Photodetachment Microscopy of Hydrogen Negative Ions in an Electric Field

NASA Astrophysics Data System (ADS)

Wang, Dehua

2014-09-01

The Aharonov-Bohm (AB) effect in the photodetachment microscopy of the H- ions in an electric field has been studied on the basis of the semiclassical theory. After the H- ion is irradiated by a laser light, they provide a coherent electron source. When the detached electron is accelerated by a uniform electric field, two trajectories of a detached electron which run from the source to the same point on the detector, will interfere with each other and lead to an interference pattern in the photodetachment microscopy. After the solenoid is electrified beside the H- ion, even though no Lorentz force acts on the electron outside the solenoid, the photodetachment microscopy interference pattern on the detector is changed with the variation in the magnetic flux enclosed by the solenoid. This is caused by the AB effect. Under certain conditions, the interference pattern reaches the macroscopic dimensions and could be observed in a direct AB effect experiment. Our study can provide some predictions for the future experimental study of the AB effect in the photodetachment microscopy of negative ions.

Synthesis of β-AgVO3 nanowires decorated with Ag2CrO4, with improved visible light photocatalytic performance

NASA Astrophysics Data System (ADS)

Ouyang, Qi; Li, Zhonghua; Liu, Jiawen

2018-05-01

Silver chromate‑silver vanadate (Ag2CrO4/β-AgVO3) heterojunction composites are synthesized through a facile precipitation process. The Ag2CrO4/β-AgVO3 hybrids obtained exhibit better photocatalytic activity in degradation of RhB than both pure Ag2CrO4 and β-AgVO3 under visible light irradiation. The 20 wt% Ag2CrO4/β-AgVO3 heterojunction possesses the best photocatalytic ability for degrading RhB: 24.4 times that of pristine β-AgVO3 nanowires and 3.2 times that of individual Ag2CrO4 particles. The phase of the nanocomposites was analyzed using x-ray diffraction as well as x-ray photoelectron spectroscopy. Their morphology was observed via scanning electron microscopy and transmission electron microscopy. The improvement in photocatalytic performance is chiefly ascribed to the synergies between Ag2CrO4/β-AgVO3 heterostructure, which can enhance the light absorbance ability and also accelerate the separation and transfer of photoinduced electrons and holes under visible light irradiation; this is also confirmed by UV–vis diffuse reflection spectrometry and fluorescence emission spectra.

Targeted Cancer Therapy: Correlative Light-Electron Microscopy Shows RGD-Targeted ZnO Nanoparticles Dissolve in the Intracellular Environment of Triple Negative Breast Cancer Cells and Cause Apoptosis with Intratumor Heterogeneity (Adv. Healthcare Mater. 11/2016).

PubMed

Othman, Basmah A; Greenwood, Christina; Abuelela, Ayman F; Bharath, Anil A; Chen, Shu; Theodorou, Ioannis; Douglas, Trevor; Uchida, Maskai; Ryan, Mary; Merzaban, Jasmeen S; Porter, Alexandra E

2016-06-01

On page 1310 J. S. Merzaban, A. E. Porter, and co-workers present fluorescently labeled RGD-targeted ZnO nanoparticles (NPs; green) for the targeted delivery of cytotoxic ZnO to integrin αvβ3 receptors expressed on triple negative breast cancer cells. Correlative light-electron microscopy shows that NPs dissolve into ionic Zn(2+) (blue) upon uptake and cause apoptosis (red) with intra-tumor heterogeneity, thereby providing a possible strategy for targeted breast cancer therapy. Cover design by Ivan Gromicho. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Blue light emitting diesel soot for photonic applications

NASA Astrophysics Data System (ADS)

Swapna, M. S.; Sankararaman, S.

2018-01-01

The present work is the first report of producing blue light emission from phosphor free and low-cost material—the diesel soot from the internal combustion engines (ICEs). The structural morphology is analyzed by field emission scanning electron microscopy and high-resolution transmission electron microscopy. The optical characterization is done by recording UV-visible spectrum and photoluminescent Spectrum. The CIE plot and the power spectrum for the sample show blue emission. This is further verified by collecting diesel soot from the ICE of different year of make. A visual confirmation of blue emission is obtained by exciting the sample with UV laser. The presence of various allotropic forms of carbon in the sample is identified by x-ray diffraction, Fourier transform infrared and Raman spectroscopic analysis.

Precise and economic FIB/SEM for CLEM: with 2 nm voxels through mitosis.

PubMed

Luckner, Manja; Wanner, Gerhard

2018-05-23

A portfolio is presented documenting economic, high-resolution correlative focused ion beam scanning electron microscopy (FIB/SEM) in routine, comprising: (i) the use of custom-labeled slides and coverslips, (ii) embedding of cells in thin, or ultra-thin resin layers for correlative light and electron microscopy (CLEM) and (iii) the claim to reach the highest resolution possible with FIB/SEM in xyz. Regions of interest (ROIs) defined in light microscope (LM), can be relocated quickly and precisely in SEM. As proof of principle, HeLa cells were investigated in 3D context at all stages of the cell cycle, documenting ultrastructural changes during mitosis: nuclear envelope breakdown and reassembly, Golgi degradation and reconstitution and the formation of the midzone and midbody.

EELS from organic crystalline materials

NASA Astrophysics Data System (ADS)

Brydson, R.; Eddleston, M. D.; Jones, W.; Seabourne, C. R.; Hondow, N.

2014-06-01

We report the use of the electron energy loss spectroscopy (EELS) for providing light element chemical composition information from organic, crystalline pharmaceutical materials including theophylline and paracetamol and discuss how this type of data can complement transmission electron microscopy (TEM) imaging and electron diffraction when investigating polymorphism. We also discuss the potential for the extraction of bonding information using electron loss near-edge structure (ELNES).

Imaging bacterial spores by soft-x-ray microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stead, A.D.; Ford, T.W.; Judge, J.

1997-04-01

Bacterial spores are able to survive dehydration, but neither the physiological nor structural basis of this have been fully elucidated. Furthermore, once hydrated, spores often require activation before they will germinate. Several treatments can be used to activate spores, but in the case of Bacillus subtlis the most effective is heat treatment. The physiological mechanism associated with activation is also not understood, but some workers suggest that the loss of calcium from the spores may be critical. However, just prior to germination, the spores change from being phase bright to phase dark when viewed by light microscopy. Imaging spores bymore » soft x-ray microscopy is possible without fixation. Thus, in contrast to electron microscopy, it is possible to compare the structure of dehydrated and hydrated spores in a manner not possible previously. A further advantage is that it is possible to monitor individual spores by phase contrast light microscopy immediately prior to imaging with soft x-rays; whereas, with both electron microscopy and biochemical studies, it is a population of spores being studied without knowledge of the phase characteristics of individual spores. This study has therefore tried to compare dehydrated and hydrated spores and to determine if there is a mass loss from individual spores as they pass the transition from being phase bright to phase dark.« less

Photon gating in four-dimensional ultrafast electron microscopy.

PubMed

Hassan, Mohammed T; Liu, Haihua; Baskin, John Spencer; Zewail, Ahmed H

2015-10-20

Ultrafast electron microscopy (UEM) is a pivotal tool for imaging of nanoscale structural dynamics with subparticle resolution on the time scale of atomic motion. Photon-induced near-field electron microscopy (PINEM), a key UEM technique, involves the detection of electrons that have gained energy from a femtosecond optical pulse via photon-electron coupling on nanostructures. PINEM has been applied in various fields of study, from materials science to biological imaging, exploiting the unique spatial, energy, and temporal characteristics of the PINEM electrons gained by interaction with a "single" light pulse. The further potential of photon-gated PINEM electrons in probing ultrafast dynamics of matter and the optical gating of electrons by invoking a "second" optical pulse has previously been proposed and examined theoretically in our group. Here, we experimentally demonstrate this photon-gating technique, and, through diffraction, visualize the phase transition dynamics in vanadium dioxide nanoparticles. With optical gating of PINEM electrons, imaging temporal resolution was improved by a factor of 3 or better, being limited only by the optical pulse widths. This work enables the combination of the high spatial resolution of electron microscopy and the ultrafast temporal response of the optical pulses, which provides a promising approach to attain the resolution of few femtoseconds and attoseconds in UEM.

Photon gating in four-dimensional ultrafast electron microscopy

PubMed Central

Hassan, Mohammed T.; Liu, Haihua; Baskin, John Spencer; Zewail, Ahmed H.

2015-01-01

Ultrafast electron microscopy (UEM) is a pivotal tool for imaging of nanoscale structural dynamics with subparticle resolution on the time scale of atomic motion. Photon-induced near-field electron microscopy (PINEM), a key UEM technique, involves the detection of electrons that have gained energy from a femtosecond optical pulse via photon–electron coupling on nanostructures. PINEM has been applied in various fields of study, from materials science to biological imaging, exploiting the unique spatial, energy, and temporal characteristics of the PINEM electrons gained by interaction with a “single” light pulse. The further potential of photon-gated PINEM electrons in probing ultrafast dynamics of matter and the optical gating of electrons by invoking a “second” optical pulse has previously been proposed and examined theoretically in our group. Here, we experimentally demonstrate this photon-gating technique, and, through diffraction, visualize the phase transition dynamics in vanadium dioxide nanoparticles. With optical gating of PINEM electrons, imaging temporal resolution was improved by a factor of 3 or better, being limited only by the optical pulse widths. This work enables the combination of the high spatial resolution of electron microscopy and the ultrafast temporal response of the optical pulses, which provides a promising approach to attain the resolution of few femtoseconds and attoseconds in UEM. PMID:26438835

A national facility for biological cryo-electron microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saibil, Helen R., E-mail: h.saibil@mail.cryst.bbk.ac.uk; Grünewald, Kay; Stuart, David I.

2015-01-01

This review provides a brief update on the use of cryo-electron microscopy for integrated structural biology, along with an overview of the plans for the UK national facility for electron microscopy being built at the Diamond synchrotron. Three-dimensional electron microscopy is an enormously powerful tool for structural biologists. It is now able to provide an understanding of the molecular machinery of cells, disease processes and the actions of pathogenic organisms from atomic detail through to the cellular context. However, cutting-edge research in this field requires very substantial resources for equipment, infrastructure and expertise. Here, a brief overview is provided ofmore » the plans for a UK national three-dimensional electron-microscopy facility for integrated structural biology to enable internationally leading research on the machinery of life. State-of-the-art equipment operated with expert support will be provided, optimized for both atomic-level single-particle analysis of purified macromolecules and complexes and for tomography of cell sections. The access to and organization of the facility will be modelled on the highly successful macromolecular crystallography (MX) synchrotron beamlines, and will be embedded at the Diamond Light Source, facilitating the development of user-friendly workflows providing near-real-time experimental feedback.« less

High-quality ultrastructural preservation using cryofixation for 3D electron microscopy of genetically labeled tissues

PubMed Central

Boassa, Daniela; Hu, Junru; Romoli, Benedetto; Phan, Sebastien; Dulcis, Davide

2018-01-01

Electron microscopy (EM) offers unparalleled power to study cell substructures at the nanoscale. Cryofixation by high-pressure freezing offers optimal morphological preservation, as it captures cellular structures instantaneously in their near-native state. However, the applicability of cryofixation is limited by its incompatibility with diaminobenzidine labeling using genetic EM tags and the high-contrast en bloc staining required for serial block-face scanning electron microscopy (SBEM). In addition, it is challenging to perform correlated light and electron microscopy (CLEM) with cryofixed samples. Consequently, these powerful methods cannot be applied to address questions requiring optimal morphological preservation. Here, we developed an approach that overcomes these limitations; it enables genetically labeled, cryofixed samples to be characterized with SBEM and 3D CLEM. Our approach is broadly applicable, as demonstrated in cultured cells, Drosophila olfactory organ and mouse brain. This optimization exploits the potential of cryofixation, allowing for quality ultrastructural preservation for diverse EM applications. PMID:29749931

Novel Crystalline SiO2 Nanoparticles via Annelids Bioprocessing of Agro-Industrial Wastes

PubMed Central

2010-01-01

The synthesis of nanoparticles silica oxide from rice husk, sugar cane bagasse and coffee husk, by employing vermicompost with annelids (Eisenia foetida) is reported. The product (humus) is calcinated and extracted to recover the crystalline nanoparticles. X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and dynamic light scattering (DLS) show that the biotransformation allows creating specific crystalline phases, since equivalent particles synthesized without biotransformation are bigger and with different crystalline structure. PMID:20802789

Use of scanning electron microscopy in the speciation of Gliocephalotrichum spp. in rambutan (Nephelium lappaceum L.)

USDA-ARS?s Scientific Manuscript database

Rambutan is a tropical tree fruit crop native to Malaysia. Worldwide, fruit rot is a limiting factor for fruit quality. In 2011, fruit rot was observed on rambutan at the USDA-ARS Tropical Agricultural Station in Mayaguez, Puerto Rico, and was attributed to Gliocephalotrichum spp. Light microscopy (...

Characterisation of Oscheius onirici (Nematoda: Rhabditidae), a hermaphroditic nematode from the marshlands of Wisconsin

USDA-ARS?s Scientific Manuscript database

An Oscheius (Rhabditidae) was recovered through the Galleria bait method from a wild cranberry marsh in Jackson County, Wisconsin, USA. Morphological studies with light microscopy and scanning electron microscopy, as well as molecular analyses of the near-full-length small subunit rDNA gene (SSU), D...

Respiratory adenovirus-like infection in a rose-ringed parakeet (Psittacula krameri).

PubMed

Desmidt, M; Ducatelle, R; Uyttebroek, E; Charlier, G; Hoorens, J

1991-01-01

Intranuclear inclusions were observed under light microscopy in the bronchial epithelial cells of a recently purchased female rose-ringed parakeet that died of chlamydiosis. Transmission electron microscopy revealed the presence of numerous particles of adenovirus morphology. A latent adenovirus infection may have become more severe following chlamydiosis and the stress of handling.

Structured Illumination Microscopy for the Investigation of Synaptic Structure and Function.

PubMed

Hong, Soyon; Wilton, Daniel K; Stevens, Beth; Richardson, Douglas S

2017-01-01

The neuronal synapse is a primary building block of the nervous system to which alterations in structure or function can result in numerous pathologies. Studying its formation and elimination is the key to understanding how brains are wired during development, maintained throughout adulthood plasticity, and disrupted during disease. However, due to its diffraction-limited size, investigations of the synaptic junction at the structural level have primarily relied on labor-intensive electron microscopy or ultra-thin section array tomography. Recent advances in the field of super-resolution light microscopy now allow researchers to image synapses and associated molecules with high-spatial resolution, while taking advantage of the key characteristics of light microscopy, such as easy sample preparation and the ability to detect multiple targets with molecular specificity. One such super-resolution technique, Structured Illumination Microscopy (SIM), has emerged as an attractive method to examine synapse structure and function. SIM requires little change in standard light microscopy sample preparation steps, but results in a twofold improvement in both lateral and axial resolutions compared to widefield microscopy. The following protocol outlines a method for imaging synaptic structures at resolutions capable of resolving the intricacies of these neuronal connections.

Visible-light-assisted SLCs template synthesis of sea anemone-like Pd/PANI nanocomposites with high electrocatalytic activity for methane oxidation in acidic medium

NASA Astrophysics Data System (ADS)

Tan, De-Xin; Wang, Yan-Li

2018-03-01

Sea anemone-like palladium (Pd)/polyaniline (PANI) nanocomposites were synthesized via visible-light-assisted swollen liquid crystals (SLCs) template method. The resulting samples were characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive spectrometer (EDS), x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), ultraviolet-visible (UV–vis) absorption spectroscopy and Fourier transform infrared (FT-IR) spectroscopy, respectively. The electrocatalytic properties of Pd/PANI nanocomposites modified glass carbon electrode (GCE) for methane oxidation were investigated by cycle voltammetry (CV) and chronoamperometry. Those dispersed sea anemone-like Pd/PANI nanocomposites had an average diameter of 320 nm. The obtained Pd nanoparticles with an average diameter of about 45 nm were uniformly distributed in PANI matrix. Sea anemone-like Pd/PANI nanocomposites exhibited excellent electrocatalytic activity and stability for oxidation of methane (CH4).

Solvothermal preparation of phthalocyanine nanorod/rGO composites and their application to visible-light-responsive photocatalysts

NASA Astrophysics Data System (ADS)

Zhang, Shuai; Lu, Yongting; Zhang, Fan; Qu, Jie; Lin, Bencai; Yuan, Ningyi; Fang, Bijun; Ding, Jian-Ning

2016-09-01

Phthalocyanine (Pc) nanorod/reduced graphene oxide (rGO) composites were prepared by a simple solvothermal method, in which Pc nanosheet and graphene oxide (GO) suspensions were mixed in methanol. As characterized by scanning electron microscopy, transmission electron microscopy, and selected area electron diffraction, Pc nanorods with an amorphous structure and an average diameter of 250nm are partially covered by rGO sheets. In the photodegradation experiments, all the composites with different rGO content show enhanced photocatalytic activity for Rhodamine B decomposition under visible-light compared to pure Pc nanorods or rGO sheets. The enhanced photocatalytic activity shall be ascribed to the large surface area offered by rGO and the charge-transfer from Pc to rGO as indicated by the photoluminescence measurement, in which fluorescence intensity of the composites is much weaker than that of Pc nanorods.

Scanning electron microscope cathodoluminescence imaging of subgrain boundaries, twins and planar deformation features in quartz

NASA Astrophysics Data System (ADS)

Hamers, M. F.; Pennock, G. M.; Drury, M. R.

2017-04-01

The study of deformation features has been of great importance to determine deformation mechanisms in quartz. Relevant microstructures in both growth and deformation processes include dislocations, subgrains, subgrain boundaries, Brazil and Dauphiné twins and planar deformation features (PDFs). Dislocations and twin boundaries are most commonly imaged using a transmission electron microscope (TEM), because these cannot directly be observed using light microscopy, in contrast to PDFs. Here, we show that red-filtered cathodoluminescence imaging in a scanning electron microscope (SEM) is a useful method to visualise subgrain boundaries, Brazil and Dauphiné twin boundaries. Because standard petrographic thin sections can be studied in the SEM, the observed structures can be directly and easily correlated to light microscopy studies. In contrast to TEM preparation methods, SEM techniques are non-destructive to the area of interest on a petrographic thin section.

Full-scale characterization of UVLED Al(x)Ga(1-x)N nanowires via advanced electron microscopy.

PubMed

Phillips, Patrick J; Carnevale, Santino D; Kumar, Rajan; Myers, Roberto C; Klie, Robert F

2013-06-25

III-Nitride semiconductor heterostructures continue to attract a great deal of attention due to the wide range of wavelengths at which they can emit light, and the subsequent desire to employ them in optoelectronic applications. Recently, a new type of pn-junction which relies on polarization-induced doping has shown promise for use as an ultraviolet light emitting diode (UVLED); nanowire growth of this device has been successfully demonstrated. However, as these devices are still in their infancy, in order to more fully understand their physical and electronic properties, they require a multitude of characterization techniques. Specifically, the present contribution will discuss the application of advanced scanning transmission electron microscopy (STEM) to AlxGa1-xN UVLED nanowires. In addition to structural data, chemical and electronic properties will also be probed through various spectroscopy techniques, with the focus remaining on practically applying the knowledge gained via STEM to the growth procedures in order to optimize device peformance.

Correlative and integrated light and electron microscopy of in-resin GFP fluorescence, used to localise diacylglycerol in mammalian cells

PubMed Central

Peddie, Christopher J.; Blight, Ken; Wilson, Emma; Melia, Charlotte; Marrison, Jo; Carzaniga, Raffaella; Domart, Marie-Charlotte; O׳Toole, Peter; Larijani, Banafshe; Collinson, Lucy M.

2014-01-01

Fluorescence microscopy of GFP-tagged proteins is a fundamental tool in cell biology, but without seeing the structure of the surrounding cellular space, functional information can be lost. Here we present a protocol that preserves GFP and mCherry fluorescence in mammalian cells embedded in resin with electron contrast to reveal cellular ultrastructure. Ultrathin in-resin fluorescence (IRF) sections were imaged simultaneously for fluorescence and electron signals in an integrated light and scanning electron microscope. We show, for the first time, that GFP is stable and active in resin sections in vacuo. We applied our protocol to study the subcellular localisation of diacylglycerol (DAG), a modulator of membrane morphology and membrane dynamics in nuclear envelope assembly. We show that DAG is localised to the nuclear envelope, nucleoplasmic reticulum and curved tips of the Golgi apparatus. With these developments, we demonstrate that integrated imaging is maturing into a powerful tool for accurate molecular localisation to structure. PMID:24637200

Long helical filaments are not seen encircling cells in electron cryotomograms of rod-shaped bacteria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swulius, Matthew T.; Chen, Songye; Jane Ding, H.

2011-04-22

Highlights: {yields} No long helical filaments are seen near or along rod-shaped bacterial inner membranes by electron cryo-tomography. {yields} Electron cryo-tomography has the resolution to detect single filaments in vivo. -- Abstract: How rod-shaped bacteria form and maintain their shape is an important question in bacterial cell biology. Results from fluorescent light microscopy have led many to believe that the actin homolog MreB and a number of other proteins form long helical filaments along the inner membrane of the cell. Here we show using electron cryotomography of six different rod-shaped bacterial species, at macromolecular resolution, that no long (>80 nm)more » helical filaments exist near or along either surface of the inner membrane. We also use correlated cryo-fluorescent light microscopy (cryo-fLM) and electron cryo-tomography (ECT) to identify cytoplasmic bundles of MreB, showing that MreB filaments are detectable by ECT. In light of these results, the structure and function of MreB must be reconsidered: instead of acting as a large, rigid scaffold that localizes cell-wall synthetic machinery, moving MreB complexes may apply tension to growing peptidoglycan strands to ensure their orderly, linear insertion.« less

The importance of transmission electron microscopy analysis of spermatozoa: Diagnostic applications and basic research.

PubMed

Moretti, Elena; Sutera, Gaetano; Collodel, Giulia

2016-06-01

This review is aimed at discussing the role of ultrastructural studies on human spermatozoa and evaluating transmission electron microscopy as a diagnostic tool that can complete andrology protocols. It is clear that morphological sperm defects may explain decreased fertilizing potential and acquire particular value in the field of male infertility. Electron microscopy is the best method to identify systematic or monomorphic and non-systematic or polymorphic sperm defects. The systematic defects are characterized by a particular anomaly that affects the vast majority of spermatozoa in a semen sample, whereas a heterogeneous combination of head and tail defects found in variable percentages are typically non-systematic or polymorphic sperm defects. A correct diagnosis of these specific sperm alterations is important for choosing the male infertility's therapy and for deciding to turn to assisted reproduction techniques. Transmission electron microscopy (TEM) also represents a valuable method to explore the in vitro effects of different compounds (for example drugs with potential spermicidal activity) on the morphology of human spermatozoa. Finally, TEM used in combination with immunohistochemical techniques, integrates structural and functional aspects that provide a wide horizon in the understanding of sperm physiology and pathology. transmission electron microscopy: TEM; World Health Organization: WHO; light microscopy: LM; motile sperm organelle morphology examination: MSOME; intracytoplasmic morphologically selected sperm injection: IMSI; intracytoplasmic sperm injection: ICSI; dysplasia of fibrous sheath: DFS; primary ciliary dyskinesia: PCD; outer dense fibers: ODF; assisted reproduction technologies: ART; scanning electron microscopy: SEM; polyvinylpirrolidone: PVP; tert-butylhydroperoxide: TBHP.

AgBr/MgBi2O6 heterostructured composites with highly efficient visible-light-driven photocatalytic activity

NASA Astrophysics Data System (ADS)

Zhong, Liansheng; Hu, Chaohao; Zhuang, Jing; Zhong, Yan; Wang, Dianhui; Zhou, Huaiying

2018-06-01

AgBr/MgBi2O6 heterostructured photocatalysts were synthesized by the deposition-precipitation method. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and UV-Visible diffuse reflectance spectroscopy (UV-Vis DRS) were employed to examine the phase structure, morphology and optical properties of the as-prepared samples. The photocatalytic activity was investigated by decomposing methylene blue (MB) solution under visible light irradiation (λ > 420 nm). AgBr/MgBi2O6 composites exhibited significantly enhanced visible-light-driven photocatalytic properties in comparison with pure MgBi2O6 and AgBr. When the molar ratio of AgBr to MgBi2O6 was 3:1, the composite catalyst showed the optimal photocatalytic activity and excellent stability. The enhanced photocatalytic activity of AgBr/MgBi2O6 composites was attributed to the formation of p-n heterojunction between AgBr and MgBi2O6, thereby resulting in the effective separation and transfer of photogenerated electrons-hole pairs.

Spatially Resolved Imaging on Photocarrier Generations and Band Alignments at Perovskite/PbI2 Heterointerfaces of Perovskite Solar Cells by Light-Modulated Scanning Tunneling Microscopy.

PubMed

Shih, Min-Chuan; Li, Shao-Sian; Hsieh, Cheng-Hua; Wang, Ying-Chiao; Yang, Hung-Duen; Chiu, Ya-Ping; Chang, Chia-Seng; Chen, Chun-Wei

2017-02-08

The presence of the PbI 2 passivation layers at perovskite crystal grains has been found to considerably affect the charge carrier transport behaviors and device performance of perovskite solar cells. This work demonstrates the application of a novel light-modulated scanning tunneling microscopy (LM-STM) technique to reveal the interfacial electronic structures at the heterointerfaces between CH 3 NH 3 PbI 3 perovskite crystals and PbI 2 passivation layers of individual perovskite grains under light illumination. Most importantly, this technique enabled the first observation of spatially resolved mapping images of photoinduced interfacial band bending of valence bands and conduction bands and the photogenerated electron and hole carriers at the heterointerfaces of perovskite crystal grains. By systematically exploring the interfacial electronic structures of individual perovskite grains, enhanced charge separation and reduced back recombination were observed when an optimal design of interfacial PbI 2 passivation layers consisting of a thickness less than 20 nm at perovskite crystal grains was applied.

Photoisomerisation and light-induced morphological switching of a polyoxometalate-azobenzene hybrid.

PubMed

Markiewicz, Grzegorz; Pakulski, Dawid; Galanti, Agostino; Patroniak, Violetta; Ciesielski, Artur; Stefankiewicz, Artur R; Samorì, Paolo

2017-06-29

The functionalization of a spherical Keplerate-type polyoxometalate {Mo 72 V 30 } with a cationic azobenzene surfactant has been achieved through ionic self-assembly. The photoisomerisation reaction of this complex, which emerges in a light-triggered aggregation-disaggregation process, has been followed by 1 H NMR spectroscopy, dynamic light scattering, absorption spectroscopy and scanning electron microscopy analyses.

Effects of spaceflight in the adductor longus muscle of rats flown in the Soviet Biosatellite COSMOS 2044. A study employing neural cell adhesion molecule (N-CAM) immunocytochemistry and conventional morphological techniques (light and electron microscopy)

NASA Technical Reports Server (NTRS)

D'Amelio, F.; Daunton, N. G.

1992-01-01

The effects of spaceflight upon the "slow" muscle adductor longus were examined in rats flown in the Soviet Biosatellite COSMOS 2044. The techniques employed included standard methods for light microscopy, neural cell adhesion molecule (N-CAM) immunocytochemistry and electron microscopy. Light microscopic observations revealed myofiber atrophy and segmental necrosis accompanied by cellular infiltrates composed of macrophages, leukocytes and mononuclear cells. Neural cell adhesion molecule immunoreactivity (N-CAM-IR) was seen on the myofiber surface and in regenerating myofibers. Ultrastructural alterations included Z band streaming, disorganization of myofibrillar architecture, sarcoplasmic degradation, extensive segmental necrosis with apparent preservation of the basement membrane, degenerative phenomena of the capillary endothelium and cellular invasion of necrotic areas. Regenerating myofibers were identified by the presence of increased amounts of ribosomal aggregates and chains of polyribosomes associated with myofilaments. The principal electron microscopic changes of the neuromuscular junctions showed axon terminals with a decrease or absence of synaptic vesicles replaced by microtubules and neurofilaments, degeneration of axon terminals, vacant axonal spaces and changes suggestive of axonal sprouting. The present observations suggest that alterations such as myofibrillar disruption and necrosis, muscle regeneration and denervation and synaptic remodeling at the level of the neuromuscular junction may take place during spaceflight.

Electronically tunable femtosecond all-fiber optical parametric oscillator for multi-photon microscopy

NASA Astrophysics Data System (ADS)

Hellwig, Tim; Brinkmann, Maximilian; Fallnich, Carsten

2018-02-01

We present a femtosecond fiber-based optical parametric oscillator (FOPO) for multiphoton microscopy with wavelength tuning by electronic repetition rate tuning in combination with a dispersive filter in the FOPO cavity. The all-spliced, all-fiber FOPO cavity is based on polarization-maintaining fibers and a broadband output coupler, allowing to get access to the resonant signal pulses as well as the idler pulses simultaneously. The system was pumped by a gain-switched fiber-coupled laser diode emitting pulses at a central wavelength of 1030 nm and an electronically tunable repetition frequency of about 2 MHz. The pump pulses were amplified in an Ytterbium fiber amplifier system with a pulse duration after amplification of 13 ps. Tuning of the idler (1140 nm - 1300 nm) and signal wavelengths (850 nm - 940 nm) was achieved by changing the repetition frequency of the pump laser by about 4 kHz. The generated signal pulses reached a pulse energy of up to 9.2 nJ at 920 nm and were spectrally broadened to about 6 nm in the FOPO by a combination of self-phase and cross-phase modulation. We showed external compression of the idler pulses at 920 nm to about 430 fs and appleid them to two-photon excitation microscopy with green fluorescent dyes. The presented system constitutes an important step towards a fully fiber-integrated all-electronically tunable and, thereby, programmable light source and already embodies a versatile and flexible light source for applications, e.g., for smart microscopy.

Detecting and locating light atoms from high-resolution STEM images: The quest for a single optimal design.

PubMed

Gonnissen, J; De Backer, A; den Dekker, A J; Sijbers, J; Van Aert, S

2016-11-01

In the present paper, the optimal detector design is investigated for both detecting and locating light atoms from high resolution scanning transmission electron microscopy (HR STEM) images. The principles of detection theory are used to quantify the probability of error for the detection of light atoms from HR STEM images. To determine the optimal experiment design for locating light atoms, use is made of the so-called Cramér-Rao Lower Bound (CRLB). It is investigated if a single optimal design can be found for both the detection and location problem of light atoms. Furthermore, the incoming electron dose is optimised for both research goals and it is shown that picometre range precision is feasible for the estimation of the atom positions when using an appropriate incoming electron dose under the optimal detector settings to detect light atoms. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication of bright and thin Zn₂SiO₄ luminescent film for electron beam excitation-assisted optical microscope.

PubMed

Furukawa, Taichi; Kanamori, Satoshi; Fukuta, Masahiro; Nawa, Yasunori; Kominami, Hiroko; Nakanishi, Yoichiro; Sugita, Atsushi; Inami, Wataru; Kawata, Yoshimasa

2015-07-13

We fabricated a bright and thin Zn₂SiO₄ luminescent film to serve as a nanometric light source for high-spatial-resolution optical microscopy based on electron beam excitation. The Zn₂SiO₄ luminescent thin film was fabricated by annealing a ZnO film on a Si₃N₄ substrate at 1000 °C in N₂. The annealed film emitted bright cathodoluminescence compared with the as-deposited film. The film is promising for nano-imaging with electron beam excitation-assisted optical microscopy. We evaluated the spatial resolution of a microscope developed using this Zn₂SiO₄ luminescent thin film. This is the first report of the investigation and application of ZnO/Si₃N₄ annealed at a high temperature (1000 °C). The fabricated Zn₂SiO₄ film is expected to enable high-frame-rate dynamic observation with ultra-high resolution using our electron beam excitation-assisted optical microscopy.

Tackling the Challenges of Dynamic Experiments Using Liquid-Cell Transmission Electron Microscopy.

PubMed

Parent, Lucas R; Bakalis, Evangelos; Proetto, Maria; Li, Yiwen; Park, Chiwoo; Zerbetto, Francesco; Gianneschi, Nathan C

2018-01-16

Revolutions in science and engineering frequently result from the development, and wide adoption, of a new, powerful characterization or imaging technique. Beginning with the first glass lenses and telescopes in astronomy, to the development of visual-light microscopy, staining techniques, confocal microscopy, and fluorescence super-resolution microscopy in biology, and most recently aberration-corrected, cryogenic, and ultrafast (4D) electron microscopy, X-ray microscopy, and scanning probe microscopy in nanoscience. Through these developments, our perception and understanding of the physical nature of matter at length-scales beyond ordinary perception have been fundamentally transformed. Despite this progression in microscopy, techniques for observing nanoscale chemical processes and solvated/hydrated systems are limited, as the necessary spatial and temporal resolution presents significant technical challenges. However, the standard reliance on indirect or bulk phase characterization of nanoscale samples in liquids is undergoing a shift in recent times with the realization ( Williamson et al. Nat. Mater . 2003 , 2 , 532 - 536 ) of liquid-cell (scanning) transmission electron microscopy, LC(S)TEM, where picoliters of solution are hermetically sealed between electron-transparent "windows," which can be directly imaged or videoed at the nanoscale using conventional transmission electron microscopes. This Account seeks to open a discussion on the topic of standardizing strategies for conducting imaging experiments with a view to characterizing dynamics and motion of nanoscale materials. This is a challenge that could be described by critics and proponents alike, as analogous to doing chemistry in a lightning storm; where the nature of the solution, the nanomaterial, and the dynamic behaviors are all potentially subject to artifactual influence by the very act of our observation.

New findings on tarsonemid mites (Prostigmata: Tarsonemidae) under the LT-SEM (Low Temperature Scanning Electron Microscopy) – The case of genera Daidalotarsonemus and Excelsotarsonemus

USDA-ARS?s Scientific Manuscript database

Daidalotarsonemus De Leon and Excelsotarsonemus Ochoa & Naskrecki are tarsonemids considered to be plant inhabiting genera. Both present complex structured bodies which are very difficult to be interpreted by traditional light microscopy techniques. Due to this most of the papers published have pres...

Mycorrhizal associations in Ailanthus altissima (Simaroubaceae) from forested and non-forested sites

Treesearch

Cynthia D. Huebner; Carolyn McQuattie; Joanne Rebbeck

2007-01-01

Ailanthus altissima tree seedlings were excavated from each of two habitats: (1) a forest adjacent to a trail and stream and (2) a non-forested steep, barren slope adjacent to a major highway. Each seedling root system was examined for colonization by mycorrhizal structures using light microscopy and transmission electron microscopy. The roots were...

An investigation of the vegetative anatomy of Piper sarmentosum, and a comparison with the anatomy of Piper betle (Piperaceae)

USDA-ARS?s Scientific Manuscript database

Piper sarmentosum Roxb. (synonym, P. lolot C.DC.) is a southeast Asian medicinal plant valued for its medicinal and culinary uses. Hand-sections of the vegetative parts of P. sarmentosum were prepared and the anatomical features were studied by light microscopy and scanning electron microscopy. Th...

Congenital myopathy associated with the triadin knockout syndrome

PubMed Central

Redhage, Keeley R.; Tester, David J.; Ackerman, Michael J.; Selcen, Duygu

2017-01-01

Objective: Triadin is a component of the calcium release complex of cardiac and skeletal muscle. Our objective was to analyze the skeletal muscle phenotype of the triadin knockout syndrome. Methods: We performed clinical evaluation, analyzed morphologic features by light and electron microscopy, and immunolocalized triadin in skeletal muscle. Results: A 6-year-old boy with lifelong muscle weakness had a triadin knockout syndrome caused by compound heterozygous null mutations in triadin. Light microscopy of a deltoid muscle specimen shows multiple small abnormal spaces in all muscle fibers. Triadin immunoreactivity is absent from type 1 fibers and barely detectable in type 2 fibers. Electron microscopy reveals focally distributed dilation and degeneration of the lateral cisterns of the sarcoplasmic reticulum and loss of the triadin anchors from the preserved lateral cisterns. Conclusions: Absence of triadin in humans can result in a congenital myopathy associated with profound pathologic alterations in components of the sarcoplasmic reticulum. Why only some triadin-deficient patients develop a skeletal muscle phenotype remains an unsolved question. PMID:28202702

Gonococcal attachment to eukaryotic cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

James, J.F.; Lammel, C.J.; Draper, D.L.

The attachment of Neisseria gonorrhoeae to eukaryotic cells grown in tissue culture was analyzed by use of light and electron microscopy and by labeling of the bacteria with (/sup 3/H)- and (/sup 14/C)adenine. Isogenic piliated and nonpiliated N. gonorrhoeae from opaque and transparent colonies were studied. The results of light microscopy studies showed that the gonococci attached to cells of human origin, including Flow 2000, HeLa 229, and HEp 2. Studies using radiolabeled gonococci gave comparable results. Piliated N. gonorrhoeae usually attached in larger numbers than nonpiliated organisms, and those from opaque colonies attached more often than isogenic variants frommore » transparent colonies. Day-to-day variation in rate of attachment was observed. Scanning electron microscopy studies showed the gonococcal attachment to be specific for microvilli of the host cells. It is concluded that more N. gonorrhoeae from opaque colonies, as compared with isogenic variants from transparent colonies, attach to eukaryotic cells grown in tissue culture.« less

Cristispira from oyster styles: complex morphology of large symbiotic spirochetes

NASA Technical Reports Server (NTRS)

Margulis, L.; Nault, L.; Sieburth, J. M.

1991-01-01

Crystalline styles (digestive organs) of bivalve mollusks provide the habitat for highly motile bacteria. Styles from freshly-collected oysters, Crassostrea virginica, were studied by electron microscopy; Cristispira spirochetes were abundant in these organs. Detailed study reveals these spirochetes to be among the most complex prokaryotic cells known. More than 600 periplasmic flagella and an adhering outer lipoprotein membrane (e.g., a 270 degrees sillon) form the ultrastructural basis for the "crista," first described by light microscopy. Unique rosette structures corresponding to the "chambers" or "ovoid inclusions" of light microscopy were detected at the periphery of all protoplasmic cylinders. Polar organelles and linearly aligned flagellar insertions are conspicuous. In size and complexity, Cristispira more resembles Pillotina, Diplocalyx, Clevelandina and Hollandina (large spirochetes symbiotic in termites) than it does Treponema. Cristispira pectinis (Gross, 1910), the type species; Spirillum ostrea (Noguchi, 1921); and another, less frequent bacterial symbiont are the predominant inhabitants of the dense style matrix. The ultrastructure of the spirillum and an electron micrograph of the third bacterium are shown.

Analysis of acute brain slices by electron microscopy: a correlative light-electron microscopy workflow based on Tokuyasu cryo-sectioning.

PubMed

Loussert Fonta, Celine; Leis, Andrew; Mathisen, Cliff; Bouvier, David S; Blanchard, Willy; Volterra, Andrea; Lich, Ben; Humbel, Bruno M

2015-01-01

Acute brain slices are slices of brain tissue that are kept vital in vitro for further recordings and analyses. This tool is of major importance in neurobiology and allows the study of brain cells such as microglia, astrocytes, neurons and their inter/intracellular communications via ion channels or transporters. In combination with light/fluorescence microscopies, acute brain slices enable the ex vivo analysis of specific cells or groups of cells inside the slice, e.g. astrocytes. To bridge ex vivo knowledge of a cell with its ultrastructure, we developed a correlative microscopy approach for acute brain slices. The workflow begins with sampling of the tissue and precise trimming of a region of interest, which contains GFP-tagged astrocytes that can be visualised by fluorescence microscopy of ultrathin sections. The astrocytes and their surroundings are then analysed by high resolution scanning transmission electron microscopy (STEM). An important aspect of this workflow is the modification of a commercial cryo-ultramicrotome to observe the fluorescent GFP signal during the trimming process. It ensured that sections contained at least one GFP astrocyte. After cryo-sectioning, a map of the GFP-expressing astrocytes is established and transferred to correlation software installed on a focused ion beam scanning electron microscope equipped with a STEM detector. Next, the areas displaying fluorescence are selected for high resolution STEM imaging. An overview area (e.g. a whole mesh of the grid) is imaged with an automated tiling and stitching process. In the final stitched image, the local organisation of the brain tissue can be surveyed or areas of interest can be magnified to observe fine details, e.g. vesicles or gold labels on specific proteins. The robustness of this workflow is contingent on the quality of sample preparation, based on Tokuyasu's protocol. This method results in a reasonable compromise between preservation of morphology and maintenance of antigenicity. Finally, an important feature of this approach is that the fluorescence of the GFP signal is preserved throughout the entire preparation process until the last step before electron microscopy. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Identification of a Multicomponent Traditional Herbal Medicine by HPLC-MS and Electron and Light Microscopy.

PubMed

Liu, Ju-Han; Cheng, Yung-Yi; Hsieh, Chen-Hsi; Tsai, Tung-Hu

2017-12-15

Commercial pharmaceutical herbal products have enabled people to take traditional Chinese medicine (TCM) in a convenient and accessible form. However, the quantity and quality should be additionally inspected. To address the issue, a combination of chemical and physical inspection methods were developed to evaluate the amount of an herbal formula, Xiang-Sha-Liu-Jun-Zi-Tang (XSLJZT), in clinical TCM practice. A high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS) method with electrospray ionization was developed to measure the herbal biomarkers of guanosine, atractylenolide III, glycyrrhizic acid, dehydrocostus lactone, hesperidin, and oleanolic acid from XSLJZT. Scanning electron microscopy (SEM) photographs and light microscopy photographs with Congo red and iodine-KI staining were used to identify the cellulose fibers and starch content. Furthermore, solubility analysis, swelling power test, and crude fiber analysis were contributed to measure the starch additive in pharmaceutical products. The results demonstrated large variations in the chemical components of different pharmaceutical brands. The SEM photographs revealed that the starch was oval, smooth, and granular, and that the raw herbal powder appears stripy, stretched, and filiform. The stained light microscopy photographs of all of the pharmaceutical products showed added starch and raw herbal powder as extenders. The developed chemical and physical methods provide a standard operating procedure for the quantity control of the herbal pharmaceutical products of XSLJZT.

Elastomeric photo-actuators and their investigation by confocal laser scanning microscopy

NASA Astrophysics Data System (ADS)

Czaniková, Klaudia; Ilčíková, Markéta; Krupa, Igor; Mičušík, Matej; Kasák, Peter; Pavlova, Ewa; Mosnáček, Jaroslav; Chorvát, Dušan, Jr.; Omastová, Mária

2013-10-01

The photo-actuation behavior of nanocomposites based on ethylene-vinylacetate copolymer (EVA) and styrene-isoprene-styrene (SIS) block copolymer filled with well-dispersed and modified multiwalled carbon nanotubes (MWCNTs) is discussed in this paper. The nanocomposites were prepared by casting from solution. To improve the dispersion of the MWCNTs in EVA, the MWCNT surface was modified with a non-covalent surfactant, cholesteryl 1-pyrenecarboxylate (PyChol). To prepare SIS nanocomposites, the MWCNT surface was covalently modified with polystyrene chains. The good dispersion of the filler was confirmed by transmission electron microscopy (TEM). Special, custom-made punch/die molds were used to create a Braille element (BE)-like shape, which under shear forces induces a uniaxial orientation of the MWCNTs within the matrix. The uniaxial orientation of MWCNTs is an essential precondition to ensure the photo-actuating behavior of MWCNTs in polymeric matrices. The orientation of the MWCNTs within the matrices was examined by scanning electron microscopy (SEM). Nanocomposite BEs were illuminated from the bottom by a red light-emitting diode (LED), and the photo-actuation was investigated by confocal laser scanning microscopy (CLSM). When the BEs were exposed to light, a temporary increase in the height of the element was detected. This process was observed to be reversible: after switching off the light, the BEs returned to their original shape and height.

Preparation of electrospun pyrochlore-structure KGdTa2O7:Eu3+ phosphor: the optical and structural properties for white light emitting diode applications.

PubMed

Yim, Chul Jin; Unithrattil, Sanjith; Chung, Woon Jin; Im, Won Bin

2013-12-01

Red emitting nanofibers, KGdTa2O7:Eu3+ were synthesized by electrospinning technique followed by heat treatment. As-prepared uniform fiber precursor with diameter ranging from about 700 nm to about 900 nm were calcined after removing organic species by calcination. The fiber surface become rough and diameter decreased to about 250-340 nm range due to decomposition of organic species and formation of inorganic phase. Morphology, structural and photoluminescent properties of fibers were analyzed using thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL). TG-DTA analysis indicates that KGdTa2O7:Eu3+ began to crystalize at 520 degrees C. Fibers annealed at 900 degrees C formed well crystallized uniform fibers. Under ultraviolet excitation KGdTa2O7:Eu3+ exhibits red emission due to transitions in 4f states of Eu3+. The excitation band is dominated by the Eu(3+)--O2-charge transfer band peaked at 289 nm. The emission peak is in the region that is ideal for red light emission.

Relative merits and limiting factors for x-ray and electron microscopy of thick, hydrated organic materials

DOE PAGES

Du, Ming; Jacobsen, Chris

2017-10-07

Electron and x-ray microscopes allow one to image the entire, unlabeled structure of hydrated materials at a resolution well beyond what visible light microscopes can achieve. However, both approaches involve ionizing radiation, so that radiation damage must be considered as one of the limits to imaging. Drawing upon earlier work, we describe here a unified approach to estimating the image contrast (and thus the required exposure and corresponding radiation dose) in both x-ray and electron microscopy. This approach accounts for factors such as plural and inelastic scattering, and (in electron microscopy) the use of energy filters to obtain so-called "zeromore » loss" images. As expected, it shows that electron microscopy offers lower dose for specimens thinner than about 1 mu m (such as for studies of macromolecules, viruses, bacteria and archaebacteria, and thin sectioned material), while x-ray microscopy offers superior characteristics for imaging thicker specimen such as whole eukaryotic cells, thick-sectioned tissues, and organs. The required radiation dose scales strongly as a function of the desired spatial resolution, allowing one to understand the limits of live and frozen hydrated specimen imaging. Lastly, we consider the factors limiting x-ray microscopy of thicker materials, suggesting that specimens as thick as a whole mouse brain can be imaged with x-ray microscopes without significant image degradation should appropriate image reconstruction methods be identified.« less

Relative merits and limiting factors for x-ray and electron microscopy of thick, hydrated organic materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Ming; Jacobsen, Chris

Electron and x-ray microscopes allow one to image the entire, unlabeled structure of hydrated materials at a resolution well beyond what visible light microscopes can achieve. However, both approaches involve ionizing radiation, so that radiation damage must be considered as one of the limits to imaging. Drawing upon earlier work, we describe here a unified approach to estimating the image contrast (and thus the required exposure and corresponding radiation dose) in both x-ray and electron microscopy. This approach accounts for factors such as plural and inelastic scattering, and (in electron microscopy) the use of energy filters to obtain so-called "zeromore » loss" images. As expected, it shows that electron microscopy offers lower dose for specimens thinner than about 1 mu m (such as for studies of macromolecules, viruses, bacteria and archaebacteria, and thin sectioned material), while x-ray microscopy offers superior characteristics for imaging thicker specimen such as whole eukaryotic cells, thick-sectioned tissues, and organs. The required radiation dose scales strongly as a function of the desired spatial resolution, allowing one to understand the limits of live and frozen hydrated specimen imaging. Lastly, we consider the factors limiting x-ray microscopy of thicker materials, suggesting that specimens as thick as a whole mouse brain can be imaged with x-ray microscopes without significant image degradation should appropriate image reconstruction methods be identified.« less

In situ polymerization synthesis of Z-scheme tungsten trioxide/polyimide photocatalyst with enhanced visible-light photocatalytic activity

NASA Astrophysics Data System (ADS)

Meng, Pengcheng; Heng, Huimin; Sun, Yanhong; Liu, Xia

2018-01-01

A novel direct Z-scheme P-containing tungsten trioxide/polyimide (PWO/PI) photocatalyst was synthesized by an in-situ solid-state polymerization strategy to enhance the visible-light photocatalytic oxidation capacity of PI. The effects of polymerization temperature and PWO content on the physicochemical properties of PWO/PI composites and photocatalytic degradation efficiency of imidacloprid were investigated. The photocatalysts were characterized by X-ray powder diffraction, Fourier transformed infrared spectra, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, UV-vis diffused reflection spectra and N2 adsorption-desorption isothermals. The results showed that the photocatalysts with visible-light photocatalytic activity can already be prepared at 300 °C. The PWO/PI composites exhibited a lamellar structure and PWO was wrapped by PI. After PWO was introduced, there was a significant interaction between PWO and PI, and the visible light response of photocatalysts was also improved. The visible-light photocatalytic degradation efficiency of imidacloprid on 3% PWO/PI-300 composite was about 3.2 times of commercial P25, and the corresponding pseudo-first-order rate constant was about 2.9 times of pristine PI. The Z-scheme photocatalytic system of PWO/PI composites was confirmed by the electron spin resonance technology, terephthalic acid photoluminescence probing technique, reactive species trapping experiments, X-ray photoelectron spectroscopy and photoluminescence of PWO/PI composites and pristine photocatalysts.

Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

DOE PAGES

Ophus, Colin; Ciston, Jim; Pierce, Jordan; ...

2016-02-29

The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, makingmore » it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Ultimately, simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.« less

Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry.

PubMed

Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R; Chess, Jordan; McMorran, Benjamin J; Czarnik, Cory; Rose, Harald H; Ercius, Peter

2016-02-29

The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.

Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

PubMed Central

Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

2016-01-01

The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals. PMID:26923483

4D multiple-cathode ultrafast electron microscopy

PubMed Central

Baskin, John Spencer; Liu, Haihua; Zewail, Ahmed H.

2014-01-01

Four-dimensional multiple-cathode ultrafast electron microscopy is developed to enable the capture of multiple images at ultrashort time intervals for a single microscopic dynamic process. The dynamic process is initiated in the specimen by one femtosecond light pulse and probed by multiple packets of electrons generated by one UV laser pulse impinging on multiple, spatially distinct, cathode surfaces. Each packet is distinctly recorded, with timing and detector location controlled by the cathode configuration. In the first demonstration, two packets of electrons on each image frame (of the CCD) probe different times, separated by 19 picoseconds, in the evolution of the diffraction of a gold film following femtosecond heating. Future elaborations of this concept to extend its capabilities and expand the range of applications of 4D ultrafast electron microscopy are discussed. The proof-of-principle demonstration reported here provides a path toward the imaging of irreversible ultrafast phenomena of materials, and opens the door to studies involving the single-frame capture of ultrafast dynamics using single-pump/multiple-probe, embedded stroboscopic imaging. PMID:25006261

4D multiple-cathode ultrafast electron microscopy.

PubMed

Baskin, John Spencer; Liu, Haihua; Zewail, Ahmed H

2014-07-22

Four-dimensional multiple-cathode ultrafast electron microscopy is developed to enable the capture of multiple images at ultrashort time intervals for a single microscopic dynamic process. The dynamic process is initiated in the specimen by one femtosecond light pulse and probed by multiple packets of electrons generated by one UV laser pulse impinging on multiple, spatially distinct, cathode surfaces. Each packet is distinctly recorded, with timing and detector location controlled by the cathode configuration. In the first demonstration, two packets of electrons on each image frame (of the CCD) probe different times, separated by 19 picoseconds, in the evolution of the diffraction of a gold film following femtosecond heating. Future elaborations of this concept to extend its capabilities and expand the range of applications of 4D ultrafast electron microscopy are discussed. The proof-of-principle demonstration reported here provides a path toward the imaging of irreversible ultrafast phenomena of materials, and opens the door to studies involving the single-frame capture of ultrafast dynamics using single-pump/multiple-probe, embedded stroboscopic imaging.

Nanodiamonds as multi-purpose labels for microscopy.

PubMed

Hemelaar, S R; de Boer, P; Chipaux, M; Zuidema, W; Hamoh, T; Martinez, F Perona; Nagl, A; Hoogenboom, J P; Giepmans, B N G; Schirhagl, R

2017-04-07

Nanodiamonds containing fluorescent nitrogen-vacancy centers are increasingly attracting interest for use as a probe in biological microscopy. This interest stems from (i) strong resistance to photobleaching allowing prolonged fluorescence observation times; (ii) the possibility to excite fluorescence using a focused electron beam (cathodoluminescence; CL) for high-resolution localization; and (iii) the potential use for nanoscale sensing. For all these schemes, the development of versatile molecular labeling using relatively small diamonds is essential. Here, we show the direct targeting of a biological molecule with nanodiamonds as small as 70 nm using a streptavidin conjugation and standard antibody labelling approach. We also show internalization of 40 nm sized nanodiamonds. The fluorescence from the nanodiamonds survives osmium-fixation and plastic embedding making them suited for correlative light and electron microscopy. We show that CL can be observed from epon-embedded nanodiamonds, while surface-exposed nanoparticles also stand out in secondary electron (SE) signal due to the exceptionally high diamond SE yield. Finally, we demonstrate the magnetic read-out using fluorescence from diamonds prior to embedding. Thus, our results firmly establish nanodiamonds containing nitrogen-vacancy centers as unique, versatile probes for combining and correlating different types of microscopy, from fluorescence imaging and magnetometry to ultrastructural investigation using electron microscopy.

Wing scale microstructures and nanostructures in butterflies--natural photonic crystals.

PubMed

Vértesy, Z; Bálint, Zs; Kertész, K; Vigneron, J P; Lousse, V; Biró, L P

2006-10-01

The aim of our study was to investigate the correlation between structural colour and scale morphology in butterflies. Detailed correlations between blue colour and structure were investigated in three lycaenid subfamilies, which represent a monophylum in the butterfly family Lycaenidae (Lepidoptera): the Coppers (Lycaeninae), the Hairstreaks (Theclinae) and the Blues (Polyommatinae). Complex investigations such as spectral measurements and characterization by means of light microscopy, scanning electron microscopy and transmission electron microscopy enabled us to demonstrate that: (i) a wide array of nanostructures generate blue colours; (ii) monophyletic groups use qualitatively similar structures; and (iii) the hue of the blue colour is characteristic for the microstructure and nanostructure of the body of the scales.

Quantitative light and scanning electron microscopy of ferret sperm.

PubMed

Van der Horst, G; Curry, P T; Kitchin, R M; Burgess, W; Thorne, E T; Kwiatkowski, D; Parker, M; Atherton, R W

1991-11-01

Sperm were obtained via electroejaculation from Domestic ferret, (Mustela putorius furo), Siberian ferret (M. eversmanni), Black-footed ferret (M. nigripes), and a hybrid between Siberian and Domestic, called the Fitch ferret (M. sp.). Comparisons of sperm were made by four different microscopy techniques to determine whether differences exist among species. First, Nomarski differential interference microscopy could be used to distinguish domestic ferret sperm from the others on the basis of the structure of the posterior part of the acrosome. Second, both silver staining, which demonstrates argentophilic protein distribution, and scanning electron microscopy (SEM), revealed differences among the morphology of sperm for each species; variation in the unique appearance of the acrosome in ferret sperm was detected especially well by SEM. To quantify differences in morphology, five sperm head parameters were measured using image analysis; light microscopy produced significantly larger values than did SEM (all parameters and all species but Fitch), and there were significant differences owing to species for all parameters but one. Generally, our data demonstrate the value of complementary techniques to distinguish among sperm of closely related species and more specifically may help establish evolutionary relationships among the ferret species studied. In addition, they provide baseline data important for the captive breeding of the endangered Black-footed ferret.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Timmermans, F. J.; Otto, C.

New developments in the field of microscopy enable to acquire increasing amounts of information from large sample areas and at an increased resolution. Depending on the nature of the technique, the information may reveal morphological, structural, chemical, and still other sample characteristics. In research fields, such as cell biology and materials science, there is an increasing demand to correlate these individual levels of information and in this way to obtain a better understanding of sample preparation and specific sample properties. To address this need, integrated systems were developed that combine nanometer resolution electron microscopes with optical microscopes, which produce chemicallymore » or label specific information through spectroscopy. The complementary information from electron microscopy and light microscopy presents an opportunity to investigate a broad range of sample properties in a correlated fashion. An important part of correlating the differences in information lies in bridging the different resolution and image contrast features. The trend to analyse samples using multiple correlated microscopes has resulted in a new research field. Current research is focused, for instance, on (a) the investigation of samples with nanometer scale distribution of inorganic and organic materials, (b) live cell analysis combined with electron microscopy, and (c) in situ spectroscopic and electron microscopy analysis of catalytic materials, but more areas will benefit from integrated correlative microscopy.« less

Physicochemcial characteristic of CdS-anchored porous WS2 hybrid in the photocatalytic degradation of crystal violet under UV and visible light irradiation

NASA Astrophysics Data System (ADS)

Vattikuti, S. V. Prabhakar; Ngo, Ich-Long; Byon, Chan

2016-11-01

In this work, we report the synthesis of CdS-incorporated porous WS2 by a simple hydrothermal method. The structural, morphological, and optical properties of the samples were examined by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), high resolution X-ray photoelectron spectroscopy (XPS) and UV-visible spectrometry. The photocatalytic activities were established for degradation of crystal violet (CV) under UV and visible light irradiation. The CdS-incorporated porous WS2 hybrid demonstrated high photocatalytic activity for degradation of CV pollutant compared to pure CdS nanoparticles and porous WS2 sheets. This result implies that the CdS-incorporated porous WS2 promoted more electron-hole pair transformation under UV and visible light irradiation. This significant enhancement of photocatalytic efficiency of CdS-incorporated porous WS2 photocatalyst under visible light can be ascribed to the presence of CdS nanospheres on the meshed-like WS2 sheets which potentially improves absorption in the visible range enabled by surface plasmon resonance effect of CdS nanospheres. The photostability and reusability of the CdS-porous WS2 were examined through recycling experiments.

Facile fabrication of CuO-Pb2O3 nanophotocatalyst for efficient degradation of Rose Bengal dye under visible light irradiation

NASA Astrophysics Data System (ADS)

Kamaraj, Eswaran; Somasundaram, Sivaraman; Balasubramani, Kavitha; Eswaran, Muthu Prema; Muthuramalingam, Rajarajan; Park, Sanghyuk

2018-03-01

A p-type CuO/n-type Pb2O3 heterojunction photocatalyst was prepared by a simple wet chemical process and the photocatalytic ability was evaluated for the degradation of Rose Bengal (RB) under visible light irradiation. Synthesized nanocatalysts were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET) surface area analysis, and X-ray photoelectron spectroscopy (XPS). The p-n heterojunction of CuO-Pb2O3 nanostructures can promote the light absorption capability of photocatalyst and charge separation of electron-hole pairs. Photodegradation assays showed that the addition of CuO effectively enhanced the photocatalytic activity of CuO-Pb2O3 under visible light irradiation (λmax > 420 nm). Compared with pure Pb2O3 and CuO, the CuO-Pb2O3 exhibited significantly enhanced photocatalytic degradation activity. The reaction rate constant of CuO-Pb2O3 is 0.092 min-1, which is much higher than those of CuO (0.073 min-1) and Pb2O3 (0.045 min-1).

ZnO/Ag/CdO nanocomposite for visible light-induced photocatalytic degradation of industrial textile effluents.

PubMed

Saravanan, R; Mansoob Khan, M; Gupta, Vinod Kumar; Mosquera, E; Gracia, F; Narayanan, V; Stephen, A

2015-08-15

A ternary ZnO/Ag/CdO nanocomposite was synthesized using thermal decomposition method. The resulting nanocomposite was characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, UV-Vis spectroscopy, and X-ray photoelectron spectroscopy. The ZnO/Ag/CdO nanocomposite exhibited enhanced photocatalytic activity under visible light irradiation for the degradation of methyl orange and methylene blue compared with binary ZnO/Ag and ZnO/CdO nanocomposites. The ZnO/Ag/CdO nanocomposite was also used for the degradation of the industrial textile effluent (real sample analysis) and degraded more than 90% in 210 min under visible light irradiation. The small size, high surface area and synergistic effect in the ZnO/Ag/CdO nanocomposite is responsible for high photocatalytic activity. These results also showed that the Ag nanoparticles induced visible light activity and facilitated efficient charge separation in the ZnO/Ag/CdO nanocomposite, thereby improving the photocatalytic performance. Copyright © 2015 Elsevier Inc. All rights reserved.

Learning from connectomics on the fly.

PubMed

Schlegel, Philipp; Costa, Marta; Jefferis, Gregory Sxe

2017-12-01

Parallels between invertebrates and vertebrates in nervous system development, organisation and circuits are powerful reasons to use insects to study the mechanistic basis of behaviour. The last few years have seen the generation in Drosophila melanogaster of very large light microscopy data sets, genetic driver lines and tools to report or manipulate neural activity. These resources in conjunction with computational tools are enabling large scale characterisation of neuronal types and their functional properties. These are complemented by 3D electron microscopy, providing synaptic resolution data. A whole brain connectome of the fly larva is approaching completion based on manual reconstruction of electron-microscopy data. An adult whole brain dataset is already publicly available and focussed reconstruction is under way, but its 40× greater volume would require ∼500-5000 person-years of manual labour. Nevertheless rapid technical improvements in imaging and especially automated segmentation will likely deliver a complete adult connectome in the next 5 years. To enhance our understanding of the circuit basis of behaviour, light and electron microscopy outputs must be integrated with functional and physiological information into comprehensive databases. We review presently available data, tools and opportunities in Drosophila. We then consider the limits and potential of future progress and how this may impact neuroscience in rich model systems provided by larger insects and vertebrates. Copyright © 2017 Elsevier Inc. All rights reserved.

Light propagation and interaction observed with electrons.

PubMed

Word, Robert C; Fitzgerald, J P S; Könenkamp, R

2016-01-01

We discuss possibilities for a microscopic optical characterization of thin films and surfaces based on photoemission electron microscopy. We show that propagating light with wavelengths across the visible range can readily be visualized, and linear and non-linear materials properties can be evaluated non-invasively with nanometer spatial resolution. While femtosecond temporal resolution can be achieved in pump-probe-type experiments, the interferometric approach presented here has typical image frame times of ~200 fs. Copyright © 2015 Elsevier B.V. All rights reserved.

Advantages of intermediate X-ray energies in Zernike phase contrast X-ray microscopy.

PubMed

Wang, Zhili; Gao, Kun; Chen, Jian; Hong, Youli; Ge, Xin; Wang, Dajiang; Pan, Zhiyun; Zhu, Peiping; Yun, Wenbing; Jacobsen, Chris; Wu, Ziyu

2013-01-01

Understanding the hierarchical organizations of molecules and organelles within the interior of large eukaryotic cells is a challenge of fundamental interest in cell biology. Light microscopy is a powerful tool for observations of the dynamics of live cells, its resolution attainable is limited and insufficient. While electron microscopy can produce images with astonishing resolution and clarity of ultra-thin (<1 μm thick) sections of biological specimens, many questions involve the three-dimensional organization of a cell or the interconnectivity of cells. X-ray microscopy offers superior imaging resolution compared to light microscopy, and unique capability of nondestructive three-dimensional imaging of hydrated unstained biological cells, complementary to existing light and electron microscopy. Until now, X-ray microscopes operating in the "water window" energy range between carbon and oxygen k-shell absorption edges have produced outstanding 3D images of cryo-preserved cells. The relatively low X-ray energy (<540 eV) of the water window imposes two important limitations: limited penetration (<10 μm) not suitable for imaging larger cells or tissues, and small depth of focus (DoF) for high resolution 3D imaging (e.g., ~1 μm DoF for 20 nm resolution). An X-ray microscope operating at intermediate energy around 2.5 keV using Zernike phase contrast can overcome the above limitations and reduces radiation dose to the specimen. Using a hydrated model cell with an average chemical composition reported in literature, we calculated the image contrast and the radiation dose for absorption and Zernike phase contrast, respectively. The results show that an X-ray microscope operating at ~2.5 keV using Zernike phase contrast offers substantial advantages in terms of specimen size, radiation dose and depth-of-focus. Copyright © 2012 Elsevier Inc. All rights reserved.

Electron tomography of whole cultured cells using novel transmission electron imaging technique.

PubMed

Okumura, Taiga; Shoji, Minami; Hisada, Akiko; Ominami, Yusuke; Ito, Sukehiro; Ushiki, Tatsuo; Nakajima, Masato; Ohshima, Takashi

2018-01-01

Since a three-dimensional (3D) cellular ultrastructure is significant for biological functions, it has been investigated using various electron microscopic techniques. Although transmission electron microscopy (TEM)-based techniques are traditionally used, cells must be embedded in resin and sliced into ultrathin sections in sample preparation processes. Block-face observation using a scanning electron microscope (SEM) has also been recently applied to 3D observation of cellular components, but this is a destructive inspection and does not allow re-examination. Therefore, we developed electron tomography using a transmission electron imaging technique called Plate-TEM. With Plate-TEM, the cells cultured directly on a scintillator plate are inserted into a conventional SEM equipped with a Plate-TEM observation system, and their internal structures are observed by detecting scintillation light produced by electrons passing through the cells. This technology has the following four advantages. First, the cells cultured on the plate can be observed at electron-microscopic resolution since they remain on the plate. Second, both surface and internal information can be obtained simultaneously by using electron- and photo-detectors, respectively, because a Plate-TEM detector is installed in an SEM. Third, the cells on the scintillator plate can also be inspected using light microscopy because the plate has transparent features. Finally, correlative observation with other techniques, such as conventional TEM, is possible after Plate-TEM observation because Plate-TEM is a non-destructive analysis technique. We also designed a sample stage to tilt the samples for tomography with Plate-TEM, by which 3D organization of cellular structures can be visualized as a whole cell. In the present study, Mm2T cells were investigated using our tomography system, resulting in 3D visualization of cell organelles such as mitochondria, lipid droplets, and microvilli. Correlative observations with various imaging techniques were also conducted by successive observations with light microscopy, SEM, Plate-TEM, and conventional TEM. Consequently, the Plate-TEM tomography technique encourages understanding of cellular structures at high resolution, which can contribute to cellular biological research. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Interior Analysis and 3-D Reconstruction of Internally-Mixed Light-Absorbing Atmospheric Particles

NASA Astrophysics Data System (ADS)

Conny, J. M.; Collins, S. M.; Anderson, I.; Herzing, A.

2010-12-01

Carbon-containing atmospheric particles may either absorb solar or outgoing long-wave radiation or scatter solar radiation, and thus, affect Earth’s radiative balance in multiple ways. Light-absorbing carbon that is common in urban air particles such as industrial coke dust, road dust, and diesel soot, often exists in the same particle with other phases that contain, for example, aluminum, calcium, iron, and sulfur. While the optical properties of atmospheric particles in general depend on overall particle size and shape, the inhomogeneity of chemical phases within internally-mixed particles may also greatly affect particle optical properties. In this study, a series of microscopic approaches were used to identify individual light-absorbing coarse-mode particles and to assess their interior structure and composition. Particle samples were collected in 2004 from one of the U.S. EPA’s Los Angeles Particulate Matter Supersites, and were likely affected substantially by road dust and construction dust. First, bright-field and dark-field light microscopy and computer-controlled scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDX) were used to distinguish predominantly light-absorbing carbonaceous particles from other particle types such as mineral dust, sea salt, and brake wear. Second, high-resolution SEM-EDX elemental mapping of individual carbonaceous particles was used to select particles with additional elemental phases that exhibited spatial inhomogeneity. Third, focused ion-beam SEM (FIB-SEM) with EDX was used to slice through selected particles to expose interior surfaces and to determine the spatial distribution of element phases throughout the particles. Fourth, study of the interior phases of a particle was augmented by the transmission electron microscopy (TEM) of a thin section of the particle prepared by FIB-SEM. Here, electron energy loss spectroscopy with TEM was used to study chemical bonding in the carbonaceous phase. Finally, automated serial slicing and imaging in the FIB-SEM generated a stack of secondary electron images of the particles’ interior surfaces that allowed for the 3-D reconstruction of the particles, a process known as FIB tomography. Interior surface of light-absorbing carbonaceous particle from FIB-SEM analysis.

Microwave-accelerated cytochemical stains for the image analysis and the electron microscopic examination of light microscopy diagnostic slides.

PubMed

Hanker, J; Giammara, B

1993-01-01

Recent studies in our laboratories have shown how microwave (MW) irradiation can accelerate a number of tissue-processing techniques, especially staining, to aid in the preparation of single specimens on glass microscope slides or coverslips for examination by light microscopy (and electron microscopy, if required) for diagnostic purposes. Techniques have been developed, which give permanently stained preparations, that can be studied initially by light microscopy, their areas of interest mapped, and computer-automated image analysis performed to obtain quantitative information. This is readily performed after MW-accelerated staining with silver methenamine by the Giammara-Hanker PATS or PATS-TS reaction. This variation of the PAS reaction gives excellent markers for specific infectious agents such as lipopolysaccharides for gram-negative bacteria or mannans for fungi. It is also an excellent stain for glycogen and basement membranes and an excellent marker for type III collagen or reticulin in the endoneurium or perineurium of peripheral nerve or in the capillary walls. Our improved MW-accelerated Feulgen reaction with silver methenamine for nuclear DNA is useful to show the nuclei of bacteria and fungi as well as of cells they are infecting. Improved coating and penetration of tissue surfaces by thiocarbohydrazide bridging of ruthenium red, applied under MW-acceleration, render biologic specimens sufficiently conductive for SEM so that sputter coating with gold is unnecessary. The specimens treated with these highly visible electron-opaque stains can be screened with the light microscope after mounting in polyethylene glycol (PEG) and the structures or areas selected for EM study are mapped with a Micro-Locator slide. After removal of the water soluble PEG the specimens are remounted in the usual EM media for scanning electron microscopy (SEM) or transmission electron microscopy (TEM) study of the mapped areas. By comparing duplicate smears from areas of infection, such as two coverslips of buffy coat smears of blood from a patient with septicemia, the microorganisms responsible can occasionally be classified for antimicrobial therapy long before culture results are available; gram-negative bacteria are positive with the Giammara-Hanker PATS-TS stain, and gram-positive bacteria are positive with the SIGMA HT40 Gram stain. The gram-positive as well as gram-negative bacteria are both initially stained by the crystal violet component of the Gram stain. The crystal violet stain is readily removed from the gram-negative (but not the gram-positive) bacteria when the specimens are rinsed with alcohol/acetone. If this rinse step is omitted, the crystal violet remains attached to both gram-negative and gram-positive bacteria. It can then be rendered insoluble, electron-opaque, and conductive by treatment with silver methenamine solution under MW-irradiation. This metallized crystal violet is a more effective silver stain than the PATS-TS stain for a number of gram-negative spirochetes such as Treponema pallidum, the microbe that causes syphilis.

Identification of Foreign Particles in Human Tissues using Raman Microscopy.

PubMed

Campion, Alan; Smith, Kenneth J; Fedulov, Alexey V; Gregory, David; Fan, Yuwei; Godleski, John J

2018-06-12

The precise identification of foreign particles in tissue for patient care and research has been studied using polarized light microscopy, electron microscopy with X-ray analysis, and electron diffraction. The goal of this study was to unambiguously identify particles in tissues using a combina-tion of polarized light microscopy and Raman microscopy, which provides chemical composition and microstructural characterization of complex materials with submicron spatial resolution. We designed a model system of stained and unstained cells that contained birefringent talc particles, and systematically investigated the influence of slide and coverslip materials, laser wavelengths, and mounting media on the Raman spectra ob-tained. Hematoxylin and eosin stained slides did not produce useful results because of fluorescence interference from the stains. Unstained cell samples prepared with standard slides and coverslips produce high quality Raman spectra when excited at 532 nm; the spectra are uniquely as-signed to talc. We also obtain high quality Raman spectra specific for talc in unstained tissue samples (pleural tissue following talc pleurodesis and ovarian tissue following long-term perineal talc exposure). Raman microscopy is sufficiently sensitive and compositionally selective to identify particles as small as one micron in diameter. Among commonly used coverslip mounting media, Cytoseal 60 is recommended; Permount was unacceptable due to intense background interference. Raman spectra have been catalogued for thousands of substances, which suggests that this approach is likely to be successful in identifying other particles of interest in tissues, potentially making Raman microscopy a powerful new tool in pathology.

Bandgap Inhomogeneity of a PbSe Quantum Dot Ensemble from Two-Dimensional Spectroscopy and Comparison to Size Inhomogeneity from Electron Microscopy

DOE PAGES

Park, Samuel D.; Baranov, Dmitry; Ryu, Jisu; ...

2017-01-03

Femtosecond two-dimensional Fourier transform spectroscopy is used to determine the static bandgap inhomogeneity of a colloidal quantum dot ensemble. The excited states of quantum dots absorb light, so their absorptive two-dimensional (2D) spectra will typically have positive and negative peaks. We show that the absorption bandgap inhomogeneity is robustly determined by the slope of the nodal line separating positive and negative peaks in the 2D spectrum around the bandgap transition; this nodal line slope is independent of excited state parameters not known from the absorption and emission spectra. The absorption bandgap inhomogeneity is compared to a size and shape distributionmore » determined by electron microscopy. The electron microscopy images are analyzed using new 2D histograms that correlate major and minor image projections to reveal elongated nanocrystals, a conclusion supported by grazing incidence small-angle X-ray scattering and high-resolution transmission electron microscopy. Lastly, the absorption bandgap inhomogeneity quantitatively agrees with the bandgap variations calculated from the size and shape distribution, placing upper bounds on any surface contributions.« less

Brain Tissue Compartment Density Estimated Using Diffusion-Weighted MRI Yields Tissue Parameters Consistent With Histology

PubMed Central

Sepehrband, Farshid; Clark, Kristi A.; Ullmann, Jeremy F.P.; Kurniawan, Nyoman D.; Leanage, Gayeshika; Reutens, David C.; Yang, Zhengyi

2015-01-01

We examined whether quantitative density measures of cerebral tissue consistent with histology can be obtained from diffusion magnetic resonance imaging (MRI). By incorporating prior knowledge of myelin and cell membrane densities, absolute tissue density values were estimated from relative intra-cellular and intra-neurite density values obtained from diffusion MRI. The NODDI (neurite orientation distribution and density imaging) technique, which can be applied clinically, was used. Myelin density estimates were compared with the results of electron and light microscopy in ex vivo mouse brain and with published density estimates in a healthy human brain. In ex vivo mouse brain, estimated myelin densities in different sub-regions of the mouse corpus callosum were almost identical to values obtained from electron microscopy (Diffusion MRI: 42±6%, 36±4% and 43±5%; electron microscopy: 41±10%, 36±8% and 44±12% in genu, body and splenium, respectively). In the human brain, good agreement was observed between estimated fiber density measurements and previously reported values based on electron microscopy. Estimated density values were unaffected by crossing fibers. PMID:26096639

Integrated light and scanning electron microscopy of GFP-expressing cells.

PubMed

Peddie, Christopher J; Liv, Nalan; Hoogenboom, Jacob P; Collinson, Lucy M

2014-01-01

Integration of light and electron microscopes provides imaging tools in which fluorescent proteins can be localized to cellular structures with a high level of precision. However, until recently, there were few methods that could deliver specimens with sufficient fluorescent signal and electron contrast for dual imaging without intermediate staining steps. Here, we report protocols that preserve green fluorescent protein (GFP) in whole cells and in ultrathin sections of resin-embedded cells, with membrane contrast for integrated imaging. Critically, GFP is maintained in a stable and active state within the vacuum of an integrated light and scanning electron microscope. For light microscopists, additional structural information gives context to fluorescent protein expression in whole cells, illustrated here by analysis of filopodia and focal adhesions in Madin Darby canine kidney cells expressing GFP-Paxillin. For electron microscopists, GFP highlights the proteins of interest within the architectural space of the cell, illustrated here by localization of the conical lipid diacylglycerol to cellular membranes. © 2014 Elsevier Inc. All rights reserved.

Subcellular pigment distribution is altered under far-red light acclimation in cyanobacteria that contain chlorophyll f.

PubMed

Majumder, Erica L-W; Wolf, Benjamin M; Liu, Haijun; Berg, R Howard; Timlin, Jerilyn A; Chen, Min; Blankenship, Robert E

2017-11-01

Far-Red Light (FRL) acclimation is a process that has been observed in cyanobacteria and algae that can grow solely on light above 700 nm. The acclimation to FRL results in rearrangement and synthesis of new pigments and pigment-protein complexes. In this study, cyanobacteria containing chlorophyll f, Synechococcus sp. PCC 7335 and Halomicronema hongdechloris, were imaged as live cells with confocal microscopy. H. hongdechloris was further studied with hyperspectral confocal fluorescence microscopy (HCFM) and freeze-substituted thin-section transmission electron microscopy (TEM). Under FRL, phycocyanin-containing complexes and chlorophyll-containing complexes were determined to be physically separated and the synthesis of red-form phycobilisome and Chl f was increased. The timing of these responses was observed. The heterogeneity and eco-physiological response of the cells was noted. Additionally, a gliding motility for H. hongdechloris is reported.

In situ electron microscopy of Braille microsystems: photo-actuation of ethylene vinyl acetate/carbon nanotube composites

NASA Astrophysics Data System (ADS)

Czaniková, Klaudia; Krupa, Igor; Račko, Dušan; Šmatko, Vasilij; Campo, Eva M.; Pavlova, Ewa; Omastová, Mária

2015-02-01

The development of new types of tactile displays based on the actuation of composite materials can aid the visually impaired. Micro/nano systems based on ethylene vinyl acetate (EVA) polymeric matrices enriched with multiwalled carbon nanotubes (MWCNT) can produce ensembles capable of light-induced actuation. In this report, we investigate two types of commercial EVA copolymers matrices containing 28 and 50 wt% vinyl-acetate (VA). Non-covalent modification of carbon nanotubes was achieved through a compatibilization technique that appends the pyrenenyl and cholesteryl groups on the carbon nanotubes (CNTs) surface. EVA/MWCNT nanocomposites were prepared by casting from a solution. These composites were shaped into Braille elements using molds. The deformation of the Braille element (BE) under light-emitting diode (LED) illumination was observed for the first time by in situ scanning electron microscopy (SEM). The superior actuation performance promoted by the EVA/MWCNT nanocomposites indicates that these materials will be useful in the future as light-driven micro/nano system actuators.

Isotope effect in heavy/light water suspensions of optically active gold nanoparticles

NASA Astrophysics Data System (ADS)

Kutsenko, V. Y.; Artykulnyi, O. P.; Petrenko, V. I.; Avdeev, M. V.; Marchenko, O. A.; Bulavin, L. A.; Snegir, S. V.

2018-04-01

Aqueous suspensions of optically active gold nanoparticles coated with trisodium citrate were synthesized in light (H2O) water and mixture of light and heavy (H2O/D2O) water using the modified Turkevich protocol. The objective of the paper was to verify sensitivity of neutron scattering methods (in particular, neutron reflectometry) to the potential isotope H/D substitution in the stabilizing organic shell around particles in colloidal solutions. First, the isotope effect was studied with respect to the changes in the structural properties of metal particles (size, shape, crystalline morphology) in solutions by electron microscopy including high-resolution transmission electron microscopy from dried systems. The structural factors determining the variation in the adsorption spectra in addition to the change in the optical properties of surrounding medium were discussed. Then, neutron reflectometry was applied to the layered nanoparticles anchored on a silicon wafer via 3-aminopropyltriethoxysilane molecules to reveal the presence of deuterated water molecules in the shell presumably formed by citrate molecules around the metallic core.

Effects of microgravity on muscle and cerebral cortex: a suggested interaction

NASA Astrophysics Data System (ADS)

D'Amelio, F.; Fox, R. A.; Wu, L. C.; Daunton, N. G.; Corcoran, M. L.

The ``slow'' antigravity muscle adductor longus was studied in rats after 14 days of spaceflight (SF). The techniques employed included standard methods for light microscopy, neural cell adhesion molecule (N-CAM) immunocytochemistry and electron microscopy. Light and electron microscopy revealed myofiber atrophy, segmental necrosis and regenerative myofibers. Regenerative myofibers were N-CAM immunoreactive (N-CAM-IR). The neuromuscular junctions showed axon terminals with a decrease or absence of synaptic vesicles, degenerative changes, vacant axonal spaces and changes suggestive of axonal sprouting. No alterations of muscle spindles was seen either by light or electron microscopy. These observations suggest that muscle regeneration and denervation and synaptic remodeling at the level of the neuromuscular junction may take place during spaceflight. In a separate study, GABA immunoreactivity (GABA-IR) was evaluated at the level of the hindlimb representation of the rat somatosensory cortex after 14 days of hindlimb unloading by tail suspension (``simulated'' microgravity). A reduction in number of GABA-immunoreactive cells with respect to the control animals was observed in layer Va and Vb. GABA-IR terminals were also reduced in the same layers, particularly those terminals surrounding the soma and apical dendrites of pyramidal cells in layer Vb. On the basis of previous morphological and behavioral studies of the neuromuscular system after spaceflight and hindlimb suspension it is suggested that after limb unloading there are alterations of afferent signaling and feedback information from intramuscular receptors to the cerebral cortex due to modifications in the reflex organization of hindlimb muscle groups. We propose that the changes observed in GABA immunoreactivity of cells and terminals is an expression of changes in their modulatory activity to compensate for the alterations in the afferent information.

Live CLEM imaging to analyze nuclear structures at high resolution.

PubMed

Haraguchi, Tokuko; Osakada, Hiroko; Koujin, Takako

2015-01-01

Fluorescence microscopy (FM) and electron microscopy (EM) are powerful tools for observing molecular components in cells. FM can provide temporal information about cellular proteins and structures in living cells. EM provides nanometer resolution images of cellular structures in fixed cells. We have combined FM and EM to develop a new method of correlative light and electron microscopy (CLEM), called "Live CLEM." In this method, the dynamic behavior of specific molecules of interest is first observed in living cells using fluorescence microscopy (FM) and then cellular structures in the same cell are observed using electron microscopy (EM). Following image acquisition, FM and EM images are compared to enable the fluorescent images to be correlated with the high-resolution images of cellular structures obtained using EM. As this method enables analysis of dynamic events involving specific molecules of interest in the context of specific cellular structures at high resolution, it is useful for the study of nuclear structures including nuclear bodies. Here we describe Live CLEM that can be applied to the study of nuclear structures in mammalian cells.

Remineralization Potential of Three Tooth Pastes on Enamel Caries.

PubMed

Singhal, Rajnish K; Rai, Balwant

2017-08-15

Different formulations of dentifrices exist in the market. Usually, single toothpaste is used by all family members including children. There is a big concern of fluoride ingestion with the toothpaste containing high fluoride content in children. Recently, new toothpaste (including toothpaste) with remineralization potential without fluoride content has been formulated. There is an urgent need to compare remineralization potential of this new formulation with the exiting dentifrices. Therefore, the present study has been undertaken to assess and compare the remineralization potential of three dentifrices with different compositions on artificially induced carious lesions in vitro by using scanning electron microscopy and polarised light microscopy. The present in vitro study was conducted on 21 healthy extracted primary central incisor teeth surfaces, which were divided into three groups and were treated by three different dentifrices. Artificial demineralization was followed by remineralization using dentifrice slurry as per the group distribution. All the samples were studied for remineralization by using scanning electron microscopy and polarised light microscopy. Data were analysed using SPSS version 11 software. A significant difference was found between the remineralization potential of incudent toothpaste and other toothpaste groups based on the analysis of polarised light microscopy and stereomicroscope. The remineralizing ability of incudent toothpaste for artificial enamel lesions was found to be significantly higher than that of Colgate® and Crest toothpaste. The limitations of this study include, being a short term study, low sample size and in vitro experiment. incudent toothpaste has exhibited a higher remineralizing potential as compared to fluoride based toothpaste in our study.

A simple energy filter for low energy electron microscopy/photoelectron emission microscopy instruments.

PubMed

Tromp, R M; Fujikawa, Y; Hannon, J B; Ellis, A W; Berghaus, A; Schaff, O

2009-08-05

Addition of an electron energy filter to low energy electron microscopy (LEEM) and photoelectron emission microscopy (PEEM) instruments greatly improves their analytical capabilities. However, such filters tend to be quite complex, both electron optically and mechanically. Here we describe a simple energy filter for the existing IBM LEEM/PEEM instrument, which is realized by adding a single scanning aperture slit to the objective transfer optics, without any further modifications to the microscope. This energy filter displays a very high energy resolution ΔE/E = 2 × 10(-5), and a non-isochromaticity of ∼0.5 eV/10 µm. The setup is capable of recording selected area electron energy spectra and angular distributions at 0.15 eV energy resolution, as well as energy filtered images with a 1.5 eV energy pass band at an estimated spatial resolution of ∼10 nm. We demonstrate the use of this energy filter in imaging and spectroscopy of surfaces using a laboratory-based He I (21.2 eV) light source, as well as imaging of Ag nanowires on Si(001) using the 4 eV energy loss Ag plasmon.

Angular reconstitution-based 3D reconstructions of nanomolecular structures from superresolution light-microscopy images

PubMed Central

Salas, Desirée; Le Gall, Antoine; Fiche, Jean-Bernard; Valeri, Alessandro; Ke, Yonggang; Bron, Patrick; Bellot, Gaetan

2017-01-01

Superresolution light microscopy allows the imaging of labeled supramolecular assemblies at a resolution surpassing the classical diffraction limit. A serious limitation of the superresolution approach is sample heterogeneity and the stochastic character of the labeling procedure. To increase the reproducibility and the resolution of the superresolution results, we apply multivariate statistical analysis methods and 3D reconstruction approaches originally developed for cryogenic electron microscopy of single particles. These methods allow for the reference-free 3D reconstruction of nanomolecular structures from two-dimensional superresolution projection images. Since these 2D projection images all show the structure in high-resolution directions of the optical microscope, the resulting 3D reconstructions have the best possible isotropic resolution in all directions. PMID:28811371

An introduction to optical super-resolution microscopy for the adventurous biologist

NASA Astrophysics Data System (ADS)

Vangindertael, J.; Camacho, R.; Sempels, W.; Mizuno, H.; Dedecker, P.; Janssen, K. P. F.

2018-04-01

Ever since the inception of light microscopy, the laws of physics have seemingly thwarted every attempt to visualize the processes of life at its most fundamental, sub-cellular, level. The diffraction limit has restricted our view to length scales well above 250 nm and in doing so, severely compromised our ability to gain true insights into many biological systems. Fortunately, continuous advancements in optics, electronics and mathematics have since provided the means to once again make physics work to our advantage. Even though some of the fundamental concepts enabling super-resolution light microscopy have been known for quite some time, practically feasible implementations have long remained elusive. It should therefore not come as a surprise that the 2014 Nobel Prize in Chemistry was awarded to the scientists who, each in their own way, contributed to transforming super-resolution microscopy from a technological tour de force to a staple of the biologist’s toolkit. By overcoming the diffraction barrier, light microscopy could once again be established as an indispensable tool in an age where the importance of understanding life at the molecular level cannot be overstated. This review strives to provide the aspiring life science researcher with an introduction to optical microscopy, starting from the fundamental concepts governing compound and fluorescent confocal microscopy to the current state-of-the-art of super-resolution microscopy techniques and their applications.

Interaction of electrons with light metal hydrides in the transmission electron microscope.

PubMed

Wang, Yongming; Wakasugi, Takenobu; Isobe, Shigehito; Hashimoto, Naoyuki; Ohnuki, Somei

2014-12-01

Transmission electron microscope (TEM) observation of light metal hydrides is complicated by the instability of these materials under electron irradiation. In this study, the electron kinetic energy dependences of the interactions of incident electrons with lithium, sodium and magnesium hydrides, as well as the constituting element effect on the interactions, were theoretically discussed, and electron irradiation damage to these hydrides was examined using in situ TEM. The results indicate that high incident electron kinetic energy helps alleviate the irradiation damage resulting from inelastic or elastic scattering of the incident electrons in the TEM. Therefore, observations and characterizations of these materials would benefit from increased, instead decreased, TEM operating voltage. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Optical properties of metamorphic GaAs/InAlGaAs/InGaAs heterostructures with InAs/InGaAs quantum wells, emitting light in the 1250–1400-nm spectral range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Egorov, A. Yu., E-mail: anton@beam.ioffe.ru; Karachinsky, L. Ya.; Novikov, I. I.

It is demonstrated that metamorphic GaAs/InAlGaAs/InGaAs heterostructures with InAs/InGaAs quantum wells, which emit light in the 1250–1400 nm spectral range, can be fabricated by molecular-beam epitaxy. The structural and optical properties of the heterostructures are studied by X-ray diffraction analysis, transmission electron microscopy, and the photoluminescence method. Comparative analysis of the integrated photoluminescence intensity of the heterostructures and a reference sample confirm the high efficiency of radiative recombination in the heterostructures. It is confirmed by transmission electron microscopy that dislocations do not penetrate into the active region of the metamorphic heterostructures, where the radiative recombination of carriers occurs.

Cytochemical Detection of Peroxisomes in Light and Electron Microscopy with 3,3'-diaminobenzidine.

PubMed

Fahimi, H Dariush

2017-01-01

Peroxisomes are ubiquitous dynamic and multifunctional organelles that contribute to numerous anabolic and catabolic pathways, being essential for human health and development. Their best known functions include the oxidation of fatty acids and metabolism of hydrogen peroxide with catalase as a marker enzyme. Indeed, historically, it was the cytochemical staining of catalase in many different cells and tissues that revealed the ubiquitous presence of peroxisomes in almost all animal and plant cells. In this chapter, the method for cytochemical staining of catalase with the alkaline 3, 3'-diaminobenzidine (DAB) is described. Since aldehyde fixation is a prerequisite for staining of catalase with DAB, a method for perfusion fixation of rat liver with glutaraldehyde is presented prior to the cytochemical staining method and the subsequent tissue processing for light and electron microscopy.

Experiment K-7-18: Effects of Spaceflight in the Muscle Adductor Longus of Rats Flown in the Soviet Biosatellite Cosmos 2044. Part 1; A Study Employing Neural Cell Adhesion Molecules (N-CAM) Immunocytochemistry and Conventional Morphological Techniques (Light and Electron Microscopy)

NASA Technical Reports Server (NTRS)

Daunton, N. G.; DAmelio, F.; Wu, L.; Ilyina-Kakueva, E. I.; Krasnov, I. B.; Hyde, T. M.; Sigworth, S. K.

1994-01-01

The effects of spaceflight upon the 'slow' muscle adductor longus was examined in rats flown in the Soviet Biosatellite COSMOS 2044. Three groups - synchronous, vivarium and basal served as controls. The techniques employed included standard methods for light microscopy, N-CAM immunocytochemistry and electron microscopy. Light microscopic observations revealed myofiber atrophy, contraction bands and segmental necrosis accompanied by cellular infiltrates composed of macrophages, leucocytes and mononuclear cells. N-CAM immunoreactivity was seen (N-CAM-IR) on the myofiber surface, satellite cells and in regenerating myofibers reminiscent of myotubes. Ultrastructural alterations included Z band streaming, disorganization of myofibrillar architecture, sarcoplasmic degradation, extensive segmental necrosis with preservation of the basement membrane, degenerative phenomena of the capillary endothelium and cellular invasion of necrotic areas. Regenerating myofibers were identified by the presence of increased amounts of ribosomal aggregates and chains of polyribosomes associated with myofilaments that displayed varied distributive patterns. The principal electron microscopic changes of the neuromuscular junctions consisted of a decrease or absence of synaptic vesicles, degeneration of axon terminals, increased number of microtubules, vacant axonal spaces and axonal sprouting. The present observations indicate that major alterations such as myofibrillar disruption and necrosis, muscle regeneration and denervation and synaptic remodeling at the level of the neuromuscular junction may take place during spaceflight.

Polarized Light Microscopy

NASA Technical Reports Server (NTRS)

Frandsen, Athela F.

2016-01-01

Polarized light microscopy (PLM) is a technique which employs the use of polarizing filters to obtain substantial optical property information about the material which is being observed. This information can be combined with other microscopy techniques to confirm or elucidate the identity of an unknown material, determine whether a particular contaminant is present (as with asbestos analysis), or to provide important information that can be used to refine a manufacturing or chemical process. PLM was the major microscopy technique in use for identification of materials for nearly a century since its introduction in 1834 by William Fox Talbot, as other techniques such as SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared spectroscopy), XPD (X-ray Powder Diffraction), and TEM (Transmission Electron Microscopy) had not yet been developed. Today, it is still the only technique approved by the Environmental Protection Agency (EPA) for asbestos analysis, and is often the technique first applied for identification of unknown materials. PLM uses different configurations in order to determine different material properties. With each configuration additional clues can be gathered, leading to a conclusion of material identity. With no polarizing filter, the microscope can be used just as a stereo optical microscope, and view qualities such as morphology, size, and number of phases. With a single polarizing filter (single polars), additional properties can be established, such as pleochroism, individual refractive indices, and dispersion staining. With two polarizing filters (crossed polars), even more can be deduced: isotropy vs. anisotropy, extinction angle, birefringence/degree of birefringence, sign of elongation, and anomalous polarization colors, among others. With the use of PLM many of these properties can be determined in a matter of seconds, even for those who are not highly trained. McCrone, a leader in the field of polarized light microscopy, often advised, If you cant determine a specific optical property of a particle after two minutes, move onto another configuration. Since optical properties can be seen so very quickly and easily under polarized light, it is only necessary to spend a maximum of two minutes on a technique to determine a particular property, though often only a few seconds are required.

Microscopic and ultrastructural changes of Müller's muscle in patients with simple congenital ptosis.

PubMed

Alshehri, Mohammed D; Al-Fakey, Yasser H; Alkhalidi, Hisham M; Mubark, Mohamed A; Alsuhaibani, Adel H

2014-01-01

To study microscopic and ultrastructural changes of Müller's muscle in patients with isolated congenital ptosis. In this prospective, observational case-control study, Müller's muscle specimens were collected during ptosis surgical correction for 18 consecutive patients. Each specimen was divided into 2 parts. One part was embedded in formalin for light microscopy, and the other one was fixed in 3% glutaraldehyde for electron microscopy. A neuropathologist, serving as a masked evaluator, blindly reviewed all the different features for every case and counted the number of myocytes showing distinct myofilaments in the whole grid for every case. Statistical analysis using compare means and correlation tests was conducted to investigate potential associations and/or differences within and across groups. Twelve Müller's muscle specimens from patients with simple congenital ptosis of various severities and 6 specimens from patients with aponeurotic ptosis (controls) were collected and studied. Under light microscopy, congenital ptosis slides showed a small number of dispersed myocytes in a fibrotic background, whereas acquired ptosis slides showed a greater number of well-defined myocytes. Under electron microscopy, all congenital ptosis specimens had only a very small number of myocytes with clear, distinct myofilaments. Most myocytes in the aponeurotic ptosis group showed clear, distinct myofilaments, indicating a well-preserved muscle. No relationship existed between the number of clear, distinct myofilaments observed in the congenital ptosis group by transmission electron microscopy and patient age or ptosis severity. Substantial Müller's muscle atrophy was observed in patients with different severities of isolated congenital ptosis.

Development of an environmental high-voltage electron microscope for reaction science.

PubMed

Tanaka, Nobuo; Usukura, Jiro; Kusunoki, Michiko; Saito, Yahachi; Sasaki, Katuhiro; Tanji, Takayoshi; Muto, Shunsuke; Arai, Shigeo

2013-02-01

Environmental transmission electron microscopy and ultra-high resolution electron microscopic observation using aberration correctors have recently emerged as topics of great interest. The former method is an extension of the so-called in situ electron microscopy that has been performed since the 1970s. Current research in this area has been focusing on dynamic observation with atomic resolution under gaseous atmospheres and in liquids. Since 2007, Nagoya University has been developing a new 1-MV high voltage (scanning) transmission electron microscope that can be used to observe nanomaterials under conditions that include the presence of gases, liquids and illuminating lights, and it can be also used to perform mechanical operations to nanometre-sized areas as well as electron tomography and elemental analysis by electron energy loss spectroscopy. The new instrument has been used to image and analyse various types of samples including biological ones.

Correlating Intravital Multi-Photon Microscopy to 3D Electron Microscopy of Invading Tumor Cells Using Anatomical Reference Points

PubMed Central

Karreman, Matthia A.; Mercier, Luc; Schieber, Nicole L.; Shibue, Tsukasa; Schwab, Yannick; Goetz, Jacky G.

2014-01-01

Correlative microscopy combines the advantages of both light and electron microscopy to enable imaging of rare and transient events at high resolution. Performing correlative microscopy in complex and bulky samples such as an entire living organism is a time-consuming and error-prone task. Here, we investigate correlative methods that rely on the use of artificial and endogenous structural features of the sample as reference points for correlating intravital fluorescence microscopy and electron microscopy. To investigate tumor cell behavior in vivo with ultrastructural accuracy, a reliable approach is needed to retrieve single tumor cells imaged deep within the tissue. For this purpose, fluorescently labeled tumor cells were subcutaneously injected into a mouse ear and imaged using two-photon-excitation microscopy. Using near-infrared branding, the position of the imaged area within the sample was labeled at the skin level, allowing for its precise recollection. Following sample preparation for electron microscopy, concerted usage of the artificial branding and anatomical landmarks enables targeting and approaching the cells of interest while serial sectioning through the specimen. We describe here three procedures showing how three-dimensional (3D) mapping of structural features in the tissue can be exploited to accurately correlate between the two imaging modalities, without having to rely on the use of artificially introduced markers of the region of interest. The methods employed here facilitate the link between intravital and nanoscale imaging of invasive tumor cells, enabling correlating function to structure in the study of tumor invasion and metastasis. PMID:25479106

Controlled Synthesis of Atomically Layered Hexagonal Boron Nitride via Chemical Vapor Deposition.

PubMed

Liu, Juanjuan; Kutty, R Govindan; Liu, Zheng

2016-11-29

Hexagonal boron nitrite (h-BN) is an attractive material for many applications including electronics as a complement to graphene, anti-oxidation coatings, light emitters, etc. However, the synthesis of high-quality h-BN is still a great challenge. In this work, via controlled chemical vapor deposition, we demonstrate the synthesis of h-BN films with a controlled thickness down to atomic layers. The quality of as-grown h-BN is confirmed by complementary characterizations including high-resolution transition electron microscopy, atomic force microscopy, Raman spectroscopy and X-ray photo-electron spectroscopy. This work will pave the way for production of large-scale and high-quality h-BN and its applications as well.

Relative merits and limiting factors for x-ray and electron microscopy of thick, hydrated organic materials.

PubMed

Du, Ming; Jacobsen, Chris

2018-01-01

Electron and x-ray microscopes allow one to image the entire, unlabeled structure of hydrated materials at a resolution well beyond what visible light microscopes can achieve. However, both approaches involve ionizing radiation, so that radiation damage must be considered as one of the limits to imaging. Drawing upon earlier work, we describe here a unified approach to estimating the image contrast (and thus the required exposure and corresponding radiation dose) in both x-ray and electron microscopy. This approach accounts for factors such as plural and inelastic scattering, and (in electron microscopy) the use of energy filters to obtain so-called "zero loss" images. As expected, it shows that electron microscopy offers lower dose for specimens thinner than about 1 µm (such as for studies of macromolecules, viruses, bacteria and archaebacteria, and thin sectioned material), while x-ray microscopy offers superior characteristics for imaging thicker specimen such as whole eukaryotic cells, thick-sectioned tissues, and organs. The required radiation dose scales strongly as a function of the desired spatial resolution, allowing one to understand the limits of live and frozen hydrated specimen imaging. Finally, we consider the factors limiting x-ray microscopy of thicker materials, suggesting that specimens as thick as a whole mouse brain can be imaged with x-ray microscopes without significant image degradation should appropriate image reconstruction methods be identified. Copyright © 2017 Elsevier B.V. All rights reserved.

On the chemical homogeneity of In xGa 1–xN alloys – Electron microscopy at the edge of technical limits

DOE PAGES

Specht, Petra; Kisielowski, Christian

2016-08-30

Ternary In xGa 1–xN alloys became technologically attractive when p-doping was achieved to produce blue and green light emitting diodes (LED)s. Starting in the mid 1990th, investigations of their chemical homogeneity were driven by the need to understand carrier recombination mechanisms in optical device structures to optimize their performance. Transmission electron microscopy (TEM) is the technique of choice to complement optical data evaluations, which suggests the coexistence of local carrier recombination mechanisms based on piezoelectric field effects and on indium clustering in the quantum wells of LEDs. We summarize the historic context of homogeneity investigations using electron microscopy techniques thatmore » can principally resolve the question of indium segregation and clustering in In xGa 1–xN alloys if optimal sample preparation and electron dose-controlled imaging techniques are employed together with advanced data evaluation.« less

Frontiers of in situ electron microscopy

DOE PAGES

Zheng, Haimei; Zhu, Yimei; Meng, Shirley Ying

2015-01-01

In situ transmission electron microscopy (TEM) has become an increasingly important tool for materials characterization. It provides key information on the structural dynamics of a material during transformations and the correlation between structure and properties of materials. With the recent advances in instrumentation, including aberration corrected optics, sample environment control, the sample stage, and fast and sensitive data acquisition, in situ TEM characterization has become more and more powerful. In this article, a brief review of the current status and future opportunities of in situ TEM is included. It also provides an introduction to the six articles covered by inmore » this issue of MRS Bulletin explore the frontiers of in situ electron microscopy, including liquid and gas environmental TEM, dynamic four-dimensional TEM, nanomechanics, ferroelectric domain switching studied by in situ TEM, and state-of-the-art atomic imaging of light elements (i.e., carbon atoms) and individual defects.« less

Milligram-per-second femtosecond laser production of Se nanoparticle inks and ink-jet printing of nanophotonic 2D-patterns

NASA Astrophysics Data System (ADS)

Ionin, Andrey; Ivanova, Anastasia; Khmel'nitskii, Roman; Klevkov, Yury; Kudryashov, Sergey; Mel'nik, Nikolay; Nastulyavichus, Alena; Rudenko, Andrey; Saraeva, Irina; Smirnov, Nikita; Zayarny, Dmitry; Baranov, Anatoly; Kirilenko, Demid; Brunkov, Pavel; Shakhmin, Alexander

2018-04-01

Milligram-per-second production of selenium nanoparticles in water sols was realized through 7-W, 2 MHz-rate femtosecond laser ablation of a crystalline trigonal selenium pellet. High-yield particle formation mechanism and ultimate mass-removal yield were elucidated by optical profilometry and scanning electron microscopy characterization of the corresponding crater depths and topographies. Deposited selenium particles were inspected by scanning and transmission electron microscopy, while their hydrosols (nanoinks) were characterized by optical transmission, Raman and dynamic light scattering spectroscopy. 2D patterns and coatings were ink-jet printed on thin supported silver films and their bare silica glass substrates, as well as on IR-transparent CaF2 substrates, and characterized by electron microscopy, energy-dispersive x-ray spectroscopy, and broadband (vis-mid IR) transmission spectroscopy, exhibiting crystalline selenium nanoparticles with high refractive index as promising all-dielectric sensing building nanoblocks in nanophotonics.

Light Microscopy at Maximal Precision

NASA Astrophysics Data System (ADS)

Bierbaum, Matthew; Leahy, Brian D.; Alemi, Alexander A.; Cohen, Itai; Sethna, James P.

2017-10-01

Microscopy is the workhorse of the physical and life sciences, producing crisp images of everything from atoms to cells well beyond the capabilities of the human eye. However, the analysis of these images is frequently little more accurate than manual marking. Here, we revolutionize the analysis of microscopy images, extracting all the useful information theoretically contained in a complex microscope image. Using a generic, methodological approach, we extract the information by fitting experimental images with a detailed optical model of the microscope, a method we call parameter extraction from reconstructing images (PERI). As a proof of principle, we demonstrate this approach with a confocal image of colloidal spheres, improving measurements of particle positions and radii by 10-100 times over current methods and attaining the maximum possible accuracy. With this unprecedented accuracy, we measure nanometer-scale colloidal interactions in dense suspensions solely with light microscopy, a previously impossible feat. Our approach is generic and applicable to imaging methods from brightfield to electron microscopy, where we expect accuracies of 1 nm and 0.1 pm, respectively.

Cathodoluminescence of stacking fault bound excitons for local probing of the exciton diffusion length in single GaN nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nogues, Gilles, E-mail: gilles.nogues@neel.cnrs.fr; Den Hertog, Martien; Inst. NEEL, CNRS, F-38042 Grenoble

We perform correlated studies of individual GaN nanowires in scanning electron microscopy combined to low temperature cathodoluminescence, microphotoluminescence, and scanning transmission electron microscopy. We show that some nanowires exhibit well localized regions emitting light at the energy of a stacking fault bound exciton (3.42 eV) and are able to observe the presence of a single stacking fault in these regions. Precise measurements of the cathodoluminescence signal in the vicinity of the stacking fault give access to the exciton diffusion length near this location.

Characterisation of 3D-GaN/InGaN nanostructured Light Emitting Diodes by Transmission Electron Microscopy

NASA Astrophysics Data System (ADS)

Griffiths, I. J.; Cherns, D.; Wang, X.; Waag, A.; Wehmann, H.-H.

2013-11-01

Transmission and scanning electron microscopy have been used to characterise GaN/InGaN 3D nanostructures grown on patterned GaN/sapphire substrates by MOVPE. It has been found that the growth of well ordered arrays of such nanostructures, containing multiple quantum wells on non-polar side-facets, can be achieved with a low density of defects. Growth changes and surface morphology play a major role in the nucleation of any defects present. The nanostructure morphology has been investigated and non-uniform growth on adjacent facets studied.

Ag-doped TiO2 hollow microspheres with visible light response by template-free route for removal of tetracycline hydrochloride from aqueous solution

NASA Astrophysics Data System (ADS)

Zhang, Jian; Li, Xuanhua; Peng, Meiling; Tang, Yuanyuan; Ke, Anqi; Gan, Wei; Fu, Xucheng; Hao, Hequn

2018-06-01

In this study, Ag-doped TiO2 hollow microspheres were synthesized by a template-free route, and their photocatalytic performance and catalytic mechanism were investigated. The hollow microspheres were characterized by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy and UV–vis spectroscopy. Ag-doped hollow TiO2 microspheres exhibited excellent photocatalytic performance for tetracycline hydrochloride (TC) in water. TC degradation follows pseudo first-order kinetics, and hydroxyl radical (OH·) and holes (h+) were active substances in the photocatalytic reaction.

New approaches in renal microscopy: volumetric imaging and superresolution microscopy.

PubMed

Kim, Alfred H J; Suleiman, Hani; Shaw, Andrey S

2016-05-01

Histologic and electron microscopic analysis of the kidney has provided tremendous insight into structures such as the glomerulus and nephron. Recent advances in imaging, such as deep volumetric approaches and superresolution microscopy, have the capacity to dramatically enhance our current understanding of the structure and function of the kidney. Volumetric imaging can generate images millimeters below the surface of the intact kidney. Superresolution microscopy breaks the diffraction barrier inherent in traditional light microscopy, enabling the visualization of fine structures. Here, we describe new approaches to deep volumetric and superresolution microscopy of the kidney. Rapid advances in lasers, microscopic objectives, and tissue preparation have transformed our ability to deep volumetric image the kidney. Innovations in sample preparation have allowed for superresolution imaging with electron microscopy correlation, providing unprecedented insight into the structures within the glomerulus. Technological advances in imaging have revolutionized our capacity to image both large volumes of tissue and the finest structural details of a cell. These new advances have the potential to provide additional profound observations into the normal and pathologic functions of the kidney.

Primary Glomerulonephritis with Unique C4d Deposition and Concurrent Non-infectious Intermediate Uveitis: a Case Report and Literature Review

PubMed Central

2018-01-01

C4 glomerulopathy is a recently introduced entity that presents with bright C4d staining and minimal or absent immunoglobulin and C3 staining. We report a case of a 62-year-old man with C4 glomerulonephritis (GN) and uveitis. He presented to the nephrology department with proteinuria and hematuria. The patient also had intermediate uveitis along with proteinuria and hematuria. A kidney biopsy that was performed in light of continuing proteinuria and hematuria showed a focal proliferative, focal sclerotic glomerulopathy pattern on light microscopy, absent staining for immunoglobulin or C3 by immunofluorescence microscopy, with bright staining for C4d on immunohistochemistry, and electron-dense deposits on electron microscopy. Consequently, C4 GN was suggested as the pathologic diagnosis. Although laser microdissection and mass spectrometry for glomerular deposit and pathologic evaluation of the retinal tissue were not performed, this is the first report of C4 GN in Korea and the first case of coexisting C4 GN and uveitis in the English literature. PMID:29713256

Microwave-Hydrothermal Synthesis of SnO2-CNTs Hybrid Nanocomposites with Visible Light Photocatalytic Activity.

PubMed

Wu, Shuisheng; Dai, Weili

2017-03-03

SnO2 nanoparticles coated on carbon nanotubes (CNTs) were prepared via a simple microwave-hydrothermal route. The as-obtained SnO2-CNTs composites were characterized using X-ray powder diffraction, Raman spectroscopy, and transmission electron microscopy. The photocatalytic activity of as-prepared SnO2-CNTs for degradation of Rhodamine B under visible light irradiation was investigated. The results show that SnO2-CNTs nanocomposites have a higher photocatalytic activity than pure SnO2 due to the rapid transferring of electrons and the effective separation of holes and electrons on SnO2-CNTs.

Microwave-Hydrothermal Synthesis of SnO2-CNTs Hybrid Nanocomposites with Visible Light Photocatalytic Activity

PubMed Central

Wu, Shuisheng; Dai, Weili

2017-01-01

SnO2 nanoparticles coated on carbon nanotubes (CNTs) were prepared via a simple microwave-hydrothermal route. The as-obtained SnO2-CNTs composites were characterized using X-ray powder diffraction, Raman spectroscopy, and transmission electron microscopy. The photocatalytic activity of as-prepared SnO2-CNTs for degradation of Rhodamine B under visible light irradiation was investigated. The results show that SnO2-CNTs nanocomposites have a higher photocatalytic activity than pure SnO2 due to the rapid transferring of electrons and the effective separation of holes and electrons on SnO2-CNTs. PMID:28336888

Gold nanoparticle uptake in whole cells in liquid examined by environmental scanning electron microscopy.

PubMed

Peckys, Diana B; de Jonge, Niels

2014-02-01

The size of gold nanoparticles (AuNPs) can influence various aspects of their cellular uptake. Light microscopy is not capable of resolving most AuNPs, while electron microscopy (EM) is not practically capable of acquiring the necessary statistical data from many cells and the results may suffer from various artifacts. Here, we demonstrate the use of a fast EM method for obtaining high-resolution data from a much larger population of cells than is usually feasible with conventional EM. A549 (human lung carcinoma) cells were subjected to uptake protocols with 10, 15, or 30 nm diameter AuNPs with adsorbed serum proteins. After 20 min, 24 h, or 45 h, the cells were fixed and imaged in whole in a thin layer of liquid water with environmental scanning electron microscopy equipped with a scanning transmission electron microscopy detector. The fast preparation and imaging of 145 whole cells in liquid allowed collection of nanoscale data within an exceptionally small amount of time of ~80 h. Analysis of 1,041 AuNP-filled vesicles showed that the long-term AuNP storing lysosomes increased their average size by 80 nm when AuNPs with 30 nm diameter were uptaken, compared to lysosomes of cells incubated with AuNPs of 10 and 15 nm diameter.

Wavelength-Controlled Photodetector Based on Single CdSSe Nanobelt

NASA Astrophysics Data System (ADS)

Li, Xinmin; Tan, Qiuhong; Feng, Xiaobo; Wang, Qianjin; Liu, Yingkai

2018-06-01

CdSSe nanobelts (NBs) are synthesized by thermal evaporation and then characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and cathodoluminescence (CL). It is found that the CdSSe NBs have a good morphology and microstructure without defects. CL is sensitive to the defects of CdSSe NBs; thus, we can select single nanobelt with homogeneous CL emission to prepare a detector. Based on it, the photodetector of single CdSSe NB was developed and its photoelectric properties were investigated in detail. It is found that under illumination of white light and at the bias voltage of 1 V, the photocurrent of a single CdSSe nanobelt device is 1.60 × 10-7 A, the dark current is 1.96 × 10-10 A, and the ratio of light current to dark one is 816. In addition, the CdSSe nanobelt detector has high photoelectric performance with spectral responsivity of 10.4 AW-1 and external quantum efficiency (EQE) of 19.1%. Its rise/decay time is about 1.62/4.70 ms. This work offers a novel strategy for design wavelength-controlled photodetectors by adjusting their compositions.

Wavelength-Controlled Photodetector Based on Single CdSSe Nanobelt.

PubMed

Li, Xinmin; Tan, Qiuhong; Feng, Xiaobo; Wang, Qianjin; Liu, Yingkai

2018-06-07

CdSSe nanobelts (NBs) are synthesized by thermal evaporation and then characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and cathodoluminescence (CL). It is found that the CdSSe NBs have a good morphology and microstructure without defects. CL is sensitive to the defects of CdSSe NBs; thus, we can select single nanobelt with homogeneous CL emission to prepare a detector. Based on it, the photodetector of single CdSSe NB was developed and its photoelectric properties were investigated in detail. It is found that under illumination of white light and at the bias voltage of 1 V, the photocurrent of a single CdSSe nanobelt device is 1.60 × 10 -7  A, the dark current is 1.96 × 10 -10  A, and the ratio of light current to dark one is 816. In addition, the CdSSe nanobelt detector has high photoelectric performance with spectral responsivity of 10.4 AW -1 and external quantum efficiency (EQE) of 19.1%. Its rise/decay time is about 1.62/4.70 ms. This work offers a novel strategy for design wavelength-controlled photodetectors by adjusting their compositions.

The erosive potential of soft drinks on enamel surface substrate: an in vitro scanning electron microscopy investigation.

PubMed

Owens, Barry M; Kitchens, Michael

2007-11-01

Using scanning electron and light microscopy, this study qualitatively evaluated the erosive potential of carbonated cola beverages as well as sports and high-energy drinks on enamel surface substrate. Beverages used in this study included: Coca Cola Classic, Diet Coke, Gatorade sports drink, Red Bull high-energy drink, and tap water (control). Extracted human permanent molars free of hypocalcification and/or caries were used in this study. The coronal portion of each tooth was removed and sectioned longitudinally from the buccal to the lingual surface. The crown sections were embedded in acrylic resin, leaving the enamel surfaces exposed. Following finishing and polishing of all surfaces, one side was covered with red nail varnish while the remaining side was exposed to individual beverage immersion for 14 days, 24 hours per day, at 37 degrees C. The specimens were evaluated for enamel surface changes using scanning electron and light microscopy. Enamel specimens exhibited visual surface changes following immersion in the test beverages with Red Bull and Gatorade revealing the most striking surface morphological changes. Specimens subjected to Coca Cola Classic and Diet Coke immersion also displayed irregular post-treatment surface morphology. As verified by microscopic evaluation, all test beverages displayed enamel dissolution in the following order: Red Bull>Gatorade>Coca-Cola Classic>Diet Coke.

Neural plasticity explored by correlative two-photon and electron/SPIM microscopy

NASA Astrophysics Data System (ADS)

Allegra Mascaro, A. L.; Silvestri, L.; Costantini, I.; Sacconi, L.; Maco, B.; Knott, G. W.; Pavone, F. S.

2013-06-01

Plasticity of the central nervous system is a complex process which involves the remodeling of neuronal processes and synaptic contacts. However, a single imaging technique can reveal only a small part of this complex machinery. To obtain a more complete view, complementary approaches should be combined. Two-photon fluorescence microscopy, combined with multi-photon laser nanosurgery, allow following the real-time dynamics of single neuronal processes in the cerebral cortex of living mice. The structural rearrangement elicited by this highly confined paradigm of injury can be imaged in vivo first, and then the same neuron could be retrieved ex-vivo and characterized in terms of ultrastructural features of the damaged neuronal branch by means of electron microscopy. Afterwards, we describe a method to integrate data from in vivo two-photon fluorescence imaging and ex vivo light sheet microscopy, based on the use of major blood vessels as reference chart. We show how the apical dendritic arbor of a single cortical pyramidal neuron imaged in living mice can be found in the large-scale brain reconstruction obtained with light sheet microscopy. Starting from its apical portion, the whole pyramidal neuron can then be segmented and located in the correct cortical layer. With the correlative approach presented here, researchers will be able to place in a three-dimensional anatomic context the neurons whose dynamics have been observed with high detail in vivo.

Electron and Light Microscopy Techniques Suitable for Studying Fatigue Damage in a Crystallized Glass Ceramic

NASA Technical Reports Server (NTRS)

Harrell, Shelley; Zaretsky, Erwin V.

1961-01-01

The crystals of Pyroceram are randomly oriented and highly reflective so that standard microscopy techniques are not satisfactory for studying this material. Standard replicating procedures proved difficult to use. New microscopy techniques and procedures have therefore been developed. A method for locating, orienting, and identifying specific areas to be viewed with an electron microscope is described. This method not require any special equipment. Plastic replicas were found to be unsatisfactory because of their tendency to adhere to Pryoceram. This caused them to tear when released or resulted in artifacts. Preshadowed silicon monoxide replicas were satisfactory but required a releasing agent. A method of depositing the releasing agent is described. To polish specimens without evidence of fire-polishing, it was found necessary to use a vibratory polishing technique. Chrome oxide was used as the abrasive and either water or kerosene as the lubricant. Vibratory polishing is extremely slow, but surfaces so polished show no evidence of fire polishing, even when examined by electron microscopy. The most satisfactory etching process used for Pyroceram 9608 consisted of a primary etch of 5 milliliters of hydrochloric acid (concentrated), 5 milliliters of hydrogen fluoride (45 percent), and 45 milliliters of water, and a secondary etch with methyl alcohol replacing the water. Best results were obtained with total etching times from 25 to 30 seconds. Staining of the Pyroceram surface with a Sanford's marker was found to be an expedient way to reduce the glare of reflected light.

Mechanisms of fine extinction band development in vein quartz: new insights from correlative light and electron microscopy

NASA Astrophysics Data System (ADS)

Derez, Tine; Van Der Donck, Tom; Plümper, Oliver; Muchez, Philippe; Pennock, Gill; Drury, Martyn R.; Sintubin, Manuel

2017-07-01

Fine extinction bands (FEBs) (also known as deformation lamellae) visible with polarized light microscopy in quartz consist of a range of nanostructures, inferring different formation processes. Previous transmission electron microscopy studies have shown that most FEB nanostructures in naturally deformed quartz are elongated subgrains formed by recovery of dislocation slip bands. Here we show that three types of FEB nanostructure occur in naturally deformed vein quartz from the low-grade metamorphic High-Ardenne slate belt (Belgium). Prismatic oriented FEBs are defined by bands of dislocation walls. Dauphiné twin boundaries present along the FEB boundaries probably formed after FEB formation. In an example of two sub-rhombohedral oriented FEBs, developed as two sets in one grain, the finer FEB set consists of elongated subgrains, similar to FEBs described in previous transmission electron microscopy studies. The second wider FEB set consists of bands with different dislocation density and fluid-inclusion content. The wider FEB set is interpreted as bands with different plastic strain associated with the primary growth banding of the vein quartz grain. The nanometre-scale fluid inclusions are interpreted to have formed from structurally bounded hydroxyl groups that moreover facilitated formation of the elongate subgrains. Larger fluid inclusions aligned along FEBs are explained by fluid-inclusion redistribution along dislocation cores. The prismatic FEB nanostructure and the relation between FEBs and growth bands have not been recognized before, although related structures have been reported in experimentally deformed quartz.

Identification of Metal Oxide Nanoparticles in Histological Samples by Enhanced Darkfield Microscopy and Hyperspectral Mapping.

PubMed

Roth, Gary A; Sosa Peña, Maria del Pilar; Neu-Baker, Nicole M; Tahiliani, Sahil; Brenner, Sara A

2015-12-08

Nanomaterials are increasingly prevalent throughout industry, manufacturing, and biomedical research. The need for tools and techniques that aid in the identification, localization, and characterization of nanoscale materials in biological samples is on the rise. Currently available methods, such as electron microscopy, tend to be resource-intensive, making their use prohibitive for much of the research community. Enhanced darkfield microscopy complemented with a hyperspectral imaging system may provide a solution to this bottleneck by enabling rapid and less expensive characterization of nanoparticles in histological samples. This method allows for high-contrast nanoscale imaging as well as nanomaterial identification. For this technique, histological tissue samples are prepared as they would be for light-based microscopy. First, positive control samples are analyzed to generate the reference spectra that will enable the detection of a material of interest in the sample. Negative controls without the material of interest are also analyzed in order to improve specificity (reduce false positives). Samples can then be imaged and analyzed using methods and software for hyperspectral microscopy or matched against these reference spectra in order to provide maps of the location of materials of interest in a sample. The technique is particularly well-suited for materials with highly unique reflectance spectra, such as noble metals, but is also applicable to other materials, such as semi-metallic oxides. This technique provides information that is difficult to acquire from histological samples without the use of electron microscopy techniques, which may provide higher sensitivity and resolution, but are vastly more resource-intensive and time-consuming than light microscopy.

Nano-fEM: protein localization using photo-activated localization microscopy and electron microscopy.

PubMed

Watanabe, Shigeki; Richards, Jackson; Hollopeter, Gunther; Hobson, Robert J; Davis, Wayne M; Jorgensen, Erik M

2012-12-03

Mapping the distribution of proteins is essential for understanding the function of proteins in a cell. Fluorescence microscopy is extensively used for protein localization, but subcellular context is often absent in fluorescence images. Immuno-electron microscopy, on the other hand, can localize proteins, but the technique is limited by a lack of compatible antibodies, poor preservation of morphology and because most antigens are not exposed to the specimen surface. Correlative approaches can acquire the fluorescence image from a whole cell first, either from immuno-fluorescence or genetically tagged proteins. The sample is then fixed and embedded for electron microscopy, and the images are correlated (1-3). However, the low-resolution fluorescence image and the lack of fiducial markers preclude the precise localization of proteins. Alternatively, fluorescence imaging can be done after preserving the specimen in plastic. In this approach, the block is sectioned, and fluorescence images and electron micrographs of the same section are correlated (4-7). However, the diffraction limit of light in the correlated image obscures the locations of individual molecules, and the fluorescence often extends beyond the boundary of the cell. Nano-resolution fluorescence electron microscopy (nano-fEM) is designed to localize proteins at nano-scale by imaging the same sections using photo-activated localization microscopy (PALM) and electron microscopy. PALM overcomes the diffraction limit by imaging individual fluorescent proteins and subsequently mapping the centroid of each fluorescent spot (8-10). We outline the nano-fEM technique in five steps. First, the sample is fixed and embedded using conditions that preserve the fluorescence of tagged proteins. Second, the resin blocks are sectioned into ultrathin segments (70-80 nm) that are mounted on a cover glass. Third, fluorescence is imaged in these sections using the Zeiss PALM microscope. Fourth, electron dense structures are imaged in these same sections using a scanning electron microscope. Fifth, the fluorescence and electron micrographs are aligned using gold particles as fiducial markers. In summary, the subcellular localization of fluorescently tagged proteins can be determined at nanometer resolution in approximately one week.

In-situ spectro-microscopy on organic films: Mn-Phthalocyanine on Ag(100)

NASA Astrophysics Data System (ADS)

Al-Mahboob, Abdullah; Sadowski, Jerzy T.; Vescovo, Elio

2013-03-01

Metal phthalocyanines are attracting significant attention, owing to their potential for applications in chemical sensors, solar cells and organic magnets. As the electronic properties of molecular films are determined by their crystallinity and molecular packing, the optimization of film quality is important for improving the performance of organic devices. Here, we present the results of in situ low-energy electron microscopy / photoemission electron microscopy (LEEM/PEEM) studies of incorporation-limited growth of manganese-phthalocyanine (MnPc) on Ag(100) surfaces. MnPc thin films were grown on both, bulk Ag(100) surface and thin Ag(100)/Fe(100) films, where substrate spin-polarized electronic states can be modified through tuning the thickness of the Ag film. We also discuss the electronic structure and magnetic ordering in MnPc thin films, investigated by angle- and spin-resolved photoemission spectroscopy. Research carried out at the Center for Functional Nanomaterials and National Synchrotron Light Source, Brookhaven National Laboratory, which are supported by the U.S. Dept. of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886.

A large-sized bubbling appearance of the glomerular basement membrane in a patient with pulmonary limited AL amyloidosis and a past history of lupus nephritis.

PubMed

Suga, Norihiro; Miura, Naoto; Uemura, Yuko; Nakamura, Toshinobu; Morita, Hiroyuki; Banno, Shogo; Imai, Hirokazu

2011-12-01

We report an unusual pathological finding, a large-sized bubbling appearance of the glomerular basement membrane (GBM), in a patient with pulmonary limited AL amyloidosis and a past history of lupus nephritis. The first renal biopsy specimen from 10 years ago, when systemic lupus erythematosus was diagnosed, demonstrated mild mesangial proliferation and subepithelial deposits (WHO classification: III + V). Light microscopy of the current biopsy using periodic acid methenamine silver (PAMS) stain demonstrated a large-sized bubbling appearance of the GBM; however, very weak immunoglobulin and complement deposition was observed in immunofluorescence studies. Routine electron microscopy demonstrated partial subendothelial expansion with electron-lucent materials, but no electron-dense deposits or amyloid fibrils. Electron microscopy with PAMS stain revealed electron-lucent endothelial scalloping, including some cellular components and microspheres in the GBM; however, it is not clear if these materials are derived from endothelial cells. One possibility is that these unique findings represent a recovery phase of lupus membranous nephritis; another is that these findings correspond to a new disease entity.

Complementary Imaging of Silver Nanoparticle Interactions with Green Algae: Dark-Field Microscopy, Electron Microscopy, and Nanoscale Secondary Ion Mass Spectrometry.

PubMed

Sekine, Ryo; Moore, Katie L; Matzke, Marianne; Vallotton, Pascal; Jiang, Haibo; Hughes, Gareth M; Kirby, Jason K; Donner, Erica; Grovenor, Chris R M; Svendsen, Claus; Lombi, Enzo

2017-11-28

Increasing consumer use of engineered nanomaterials has led to significantly increased efforts to understand their potential impact on the environment and living organisms. Currently, no individual technique can provide all the necessary information such as their size, distribution, and chemistry in complex biological systems. Consequently, there is a need to develop complementary instrumental imaging approaches that provide enhanced understanding of these "bio-nano" interactions to overcome the limitations of individual techniques. Here we used a multimodal imaging approach incorporating dark-field light microscopy, high-resolution electron microscopy, and nanoscale secondary ion mass spectrometry (NanoSIMS). The aim was to gain insight into the bio-nano interactions of surface-functionalized silver nanoparticles (Ag-NPs) with the green algae Raphidocelis subcapitata, by combining the fidelity, spatial resolution, and elemental identification offered by the three techniques, respectively. Each technique revealed that Ag-NPs interact with the green algae with a dependence on the size (10 nm vs 60 nm) and surface functionality (tannic acid vs branched polyethylenimine, bPEI) of the NPs. Dark-field light microscopy revealed the presence of strong light scatterers on the algal cell surface, and SEM imaging confirmed their nanoparticulate nature and localization at nanoscale resolution. NanoSIMS imaging confirmed their chemical identity as Ag, with the majority of signal concentrated at the cell surface. Furthermore, SEM and NanoSIMS provided evidence of 10 nm bPEI Ag-NP internalization at higher concentrations (40 μg/L), correlating with the highest toxicity observed from these NPs. This multimodal approach thus demonstrated an effective approach to complement dose-response studies in nano-(eco)-toxicological investigations.

Visible-light-driven Bi 2 O 3 /WO 3 composites with enhanced photocatalytic activity

DOE PAGES

Adhikari, Shiba P.; Dean, Hunter; Hood, Zachary D.; ...

2015-10-19

Semiconductor heterojunctions (composites) have been shown to be effective photocatalytic materials to overcome the drawbacks of low photocatalytic efficiency that results from electron–hole recombination and narrow photo-response range. We prepared a novel visible-light-driven Bi 2O 3/WO 3 composite photocatalyst by hydrothermal synthesis. The composite was characterized by scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area, Raman spectroscopy, photoluminescence spectroscopy (PL) and electrochemical impedance spectroscopy (EIS) to better understand the structures, compositions, morphologies and optical properties. Bi 2O 3/WO 3 heterojunction was found to exhibit significantly higher photocatalyticmore » activity towards the decomposition of Rhodamine B (RhB) and 4-nitroaniline (4-NA) under visible light irradiation compared to that of Bi 2O 3 and WO 3. A tentative mechanism for the enhanced photocatalytic activity of the heterostructured composite is discussed based on observed activity, band position calculations, photoluminescence, and electrochemical impedance data. Our study provides a new strategy for the design of composite materials with enhanced visible light photocatalytic performance.« less

In Vitro Self-Assembly of the Light Harvesting Pigment-Protein LH2 Revealed by Ultrafast Spectroscopy and Electron Microscopy

PubMed Central

Schubert, Axel; Stenstam, Anna; Beenken, Wichard J. D.; Herek, Jennifer L.; Cogdell, Richard; Pullerits, Tõnu; Sundström, Villy

2004-01-01

Controlled ensemble formation of protein-surfactant systems provides a fundamental concept for the realization of nanoscale devices with self-organizing capability. In this context, spectroscopic monitoring of pigment-containing proteins yields detailed structural information. Here we have studied the association behavior of the bacterial light-harvesting protein LH2 from Rhodobacter spheroides in an n,n-dimethyldodecylamine-n-oxide/water environment. Time-resolved studies of the excitation annihilation yielded information about aggregate sizes and packing of the protein complexes therein. The results are compared to transmission electron microscopy images of instantaneously frozen samples. Our data indicate the manifestation of different phases, which are discussed with respect to the thermodynamic equilibrium in ternary protein-surfactant-water systems. Accordingly, by varying the concentration the formation of different types of aggregates can be controlled. Conditions for the appearance of isolated LH2 complexes are defined. PMID:15041674

Morphology of glochidia of Lampsilis higginsi (Bivalvia: Unionidae) compared with three related species

USGS Publications Warehouse

Waller, D.L.; Holland Bartels, L. E.; Mitchell, L.G.

1988-01-01

Glochidia of the endangered unionid mussel Lampsilis higginsi (Lea) are morphologically similar to those of several other species in the upper Mississippi River. Life history details, such as the timing of reproduction and identity of host fish, can be readily studied if the glochidia of L. higginsi can be distinguished from those of related species. Authors used light and scanning electron microscopy and statistical analyses of three shell measurements, shell length, shell height, and hinge length, to compare the glochidia of L. higginsi with those of L. radiata siliquoidea (Barnes), L. ventricosa (Barnes), and Ligumia recta (Lamarck). Glochidia of L. higginsi were differentiated by scanning electron microscopy on the basis of a combined examination of the position of the hinge ligament and the width of dorsal ridges, but were indistinguishable by light microscope examination or by statistical analyses of measurements.

Light and electron microscopic observation of regenerated fungiform taste buds in patients with recovered taste function after severing chorda tympani nerve.

PubMed

Saito, Takehisa; Ito, Tetsufumi; Narita, Norihiko; Yamada, Takechiyo; Manabe, Yasuhiro

2011-11-01

The aim of this study was to evaluate the mean number of regenerated fungiform taste buds per papilla and perform light and electron microscopic observation of taste buds in patients with recovered taste function after severing the chorda tympani nerve during middle ear surgery. We performed a biopsy on the fungiform papillae (FP) in the midlateral region of the dorsal surface of the tongue from 5 control volunteers (33 total FP) and from 7 and 5 patients with and without taste recovery (34 and 29 FP, respectively) 3 years 6 months to 18 years after surgery. The specimens were observed by light and transmission electron microscopy. The taste function was evaluated by electrogustometry. The mean number of taste buds in the FP of patients with completely recovered taste function was significantly smaller (1.9 +/- 1.4 per papilla; p < 0.01) than that of the control subjects (3.8 +/- 2.2 per papilla). By transmission electron microscopy, 4 distinct types of cell (type I, II, III, and basal cells) were identified in the regenerated taste buds. Nerve fibers and nerve terminals were also found in the taste buds. It was clarified that taste buds containing taste cells and nerve endings do regenerate in the FP of patients with recovered taste function.

Optical spectroscopy and microscopy of radiation-induced light-emitting point defects in lithium fluoride crystals and films

NASA Astrophysics Data System (ADS)

Montereali, R. M.; Bonfigli, F.; Menchini, F.; Vincenti, M. A.

2012-08-01

Broad-band light-emitting radiation-induced F2 and F3+ electronic point defects, which are stable and laser-active at room temperature in lithium fluoride crystals and films, are used in dosimeters, tuneable color-center lasers, broad-band miniaturized light sources and novel radiation imaging detectors. A brief review of their photoemission properties is presented, and their behavior at liquid nitrogen temperatures is discussed. Some experimental data from optical spectroscopy and fluorescence microscopy of these radiation-induced point defects in LiF crystals and thin films are used to obtain information about the coloration curves, the efficiency of point defect formation, the effects of photo-bleaching processes, etc. Control of the local formation, stabilization, and transformation of radiation-induced light-emitting defect centers is crucial for the development of optically active micro-components and nanostructures. Some of the advantages of low temperature measurements for novel confocal laser scanning fluorescence microscopy techniques, widely used for spatial mapping of these point defects through the optical reading of their visible photoluminescence, are highlighted.

Single organelle dynamics linked to 3D structure by correlative live-cell imaging and 3D electron microscopy.

PubMed

Fermie, Job; Liv, Nalan; Ten Brink, Corlinda; van Donselaar, Elly G; Müller, Wally H; Schieber, Nicole L; Schwab, Yannick; Gerritsen, Hans C; Klumperman, Judith

2018-05-01

Live-cell correlative light-electron microscopy (live-cell-CLEM) integrates live movies with the corresponding electron microscopy (EM) image, but a major challenge is to relate the dynamic characteristics of single organelles to their 3-dimensional (3D) ultrastructure. Here, we introduce focused ion beam scanning electron microscopy (FIB-SEM) in a modular live-cell-CLEM pipeline for a single organelle CLEM. We transfected cells with lysosomal-associated membrane protein 1-green fluorescent protein (LAMP-1-GFP), analyzed the dynamics of individual GFP-positive spots, and correlated these to their corresponding fine-architecture and immediate cellular environment. By FIB-SEM we quantitatively assessed morphological characteristics, like number of intraluminal vesicles and contact sites with endoplasmic reticulum and mitochondria. Hence, we present a novel way to integrate multiple parameters of subcellular dynamics and architecture onto a single organelle, which is relevant to address biological questions related to membrane trafficking, organelle biogenesis and positioning. Furthermore, by using CLEM to select regions of interest, our method allows for targeted FIB-SEM, which significantly reduces time required for image acquisition and data processing. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Attosecond control of electron beams at dielectric and absorbing membranes

NASA Astrophysics Data System (ADS)

Morimoto, Yuya; Baum, Peter

2018-03-01

Ultrashort electron pulses are crucial for time-resolved electron diffraction and microscopy of the fundamental light-matter interaction. In this work, we study experimentally and theoretically the generation and characterization of attosecond electron pulses by optical-field-driven compression and streaking at dielectric or absorbing interaction elements. The achievable acceleration and deflection gradient depends on the laser-electron angle, the laser's electric and magnetic field directions, and the foil orientation. Electric and magnetic fields have similar contributions to the final effect and both need to be considered. Experiments and theory agree well and reveal the optimum conditions for highly efficient, velocity-matched electron-field interactions in the longitudinal or transverse direction. We find that metallic membranes are optimum for light-electron control at mid-infrared or terahertz wavelengths, but dielectric membranes are excellent in the visible and near-infrared regimes and are therefore ideal for the formation of attosecond electron pulses.

A Magnetorheological Polishing-Based Approach for Studying Precision Microground Surfaces of Tungsten Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shafrir, S.N.; Lambropoulos, J.C.; Jacobs, S.D.

2007-03-23

Surface features of tungsten carbide composites processed by bound abrasive deterministic microgrinding and magnetorheological finishing (MRF) were studied for five WC-Ni composites, including one binderless material. All the materials studied were nonmagnetic with different microstructures and mechanical properties. White-light interferometry, scanning electron microscopy, and atomic force microscopy were used to characterize the surfaces after various grinding steps, surface etching, and MRF spot-taking.

Sinusoidal obstruction syndrome (SOS): A light and electron microscopy study in human liver.

PubMed

Vreuls, C P H; Driessen, A; Olde Damink, S W M; Koek, G H; Duimel, H; van den Broek, M A J; Dejong, C H C; Braet, F; Wisse, E

2016-05-01

Oxaliplatin is an important chemotherapeutic agent, used in the treatment of hepatic colorectal metastases, and known to induce the sinusoidal obstruction syndrome (SOS). Pathophysiological knowledge concerning SOS is based on a rat model. Therefore, the aim was to perform a comprehensive study of the features of human SOS, using both light microscopy (LM) and electron microscopy (EM). Included were all patients of whom wedge liver biopsies were collected during a partial hepatectomy for colorectal liver metastases, in a 4-year period. The wedge biopsy were perfusion fixated and processed for LM and EM. The SOS lesions were selected by LM and details were studied using EM. Material was available of 30 patients, of whom 28 patients received neo-adjuvant oxaliplatin. Eighteen (64%) of the 28 patients showed SOS lesions, based on microscopy. The lesions consisted of sinusoidal endothelial cell detachment from the space of Disse on EM. In the enlarged space of Disse a variable amount of erythrocytes were located. Sinusoidal endothelial cell detachment was present in human SOS, accompanied by enlargement of the space of Disse and erythrocytes in this area. These findings, originally described in a rat model, were now for the first time confirmed in human livers under clinically relevant settings. Copyright © 2016 Elsevier Ltd. All rights reserved.

Immunohistochemical localization of beta-amyloid precursor protein sequences in Alzheimer and normal brain tissue by light and electron microscopy.

PubMed

McGeer, P L; Akiyama, H; Kawamata, T; Yamada, T; Walker, D G; Ishii, T

1992-03-01

Immunohistochemical staining with antibodies directed against four segments of the amyloid precursor protein (APP) was studied by light and electron microscopy in normal and Alzheimer (AD) brain tissue. The segments according to the Kang et al. sequence were: 18-38 (T97); 527-540 (R36); 597-620 (1-24 of beta-amyloid protein [BAP], R17); and 681-695 (R37) (Kang et al. [1987]: Nature 325:733-736). The antibodies recognized full length APP in Western blots of extracts of APP transfected cells. They stained cytoplasmic granules in some pyramidal neurons in normal appearing tissue from control and AD cases. In AD affected tissue, the antibodies to amino terminal sections of APP stained tangled neurons and neuropil threads, and intensely stained dystrophic neurites in senile plaques. By electron microscopy, this staining was localized to abnormal filaments. The antibody to the carboxy terminal segment failed to stain neurofibrillary tangles or neuropil threads; it did stain some neurites with globular swellings. It also stained globular and elongated deposits in senile plaque areas. The antibody against the BAP intensely stained extracellular material in senile plaques and diffuse deposits. By electron microscopy, the antibodies all stained intramicroglial deposits. Some of the extracellular and intracellular BAP-positive deposits were fibrillary. Communication between intramicroglial and extracellular fibrils was detected in plaque areas. These data suggest the following sequence of events. APP is normally concentrated in intraneuronal granules. In AD, it accumulates in damaged neuronal fibers. The amino terminal portion binds to abnormal neurofilaments. Major fragments of APP are phagocytosed and processed by microglia with the BAP portion being preserved. The preserved BAP is then extruded and accumulates in extracellular tissue.

Multi-scale Observation of Biological Interactions of Nanocarriers: from Nano to Macro

PubMed Central

Jin, Su-Eon; Bae, Jin Woo; Hong, Seungpyo

2010-01-01

Microscopic observations have played a key role in recent advancements in nanotechnology-based biomedical sciences. In particular, multi-scale observation is necessary to fully understand the nano-bio interfaces where a large amount of unprecedented phenomena have been reported. This review describes how to address the physicochemical and biological interactions of nanocarriers within the biological environments using microscopic tools. The imaging techniques are categorized based on the size scale of detection. For observation of the nano-scale biological interactions of nanocarriers, we discuss atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). For the micro to macro-scale (in vitro and in vivo) observation, we focus on confocal laser scanning microscopy (CLSM) as well as in vivo imaging systems such as magnetic resonance imaging (MRI), superconducting quantum interference devices (SQUIDs), and IVIS®. Additionally, recently developed combined techniques such as AFM-CLSM, correlative Light and Electron Microscopy (CLEM), and SEM-spectroscopy are also discussed. In this review, we describe how each technique helps elucidate certain physicochemical and biological activities of nanocarriers such as dendrimers, polymers, liposomes, and polymeric/inorganic nanoparticles, thus providing a toolbox for bioengineers, pharmaceutical scientists, biologists, and research clinicians. PMID:20232368

The quest for four-dimensional imaging in plant cell biology: it's just a matter of time

PubMed Central

Domozych, David S.

2012-01-01

Background Analysis of plant cell dynamics over time, or four-dimensional imaging (4-DI), represents a major goal of plant science. The ability to resolve structures in the third dimension within the cell or tissue during developmental events or in response to environmental or experimental stresses (i.e. 4-DI) is critical to our understanding of gene expression, post-expression modulations of macromolecules and sub-cellular system interactions. Scope Microscopy-based technologies have been profoundly integral to this type of investigation, and new and refined microscopy technologies now allow for the visualization of cell dynamics with unprecedented resolution, contrast and experimental versatility. However, certain realities of light and electron microscopy, choice of specimen and specimen preparation techniques limit the scope of readily attaining 4-DI. Today, the plant microscopist must use a combinatorial strategy whereby multiple microscopy-based investigations are used. Modern fluorescence, confocal laser scanning, transmission electron and scanning electron microscopy provide effective conduits for synthesizing data detailing live cell dynamics and highly resolved snapshots of specific cell structures that will ultimately lead to 4-DI. This review provides a synopsis of such technologies available. PMID:22628381

The role of vitamin E in the prevention of zoledronic acid-induced nephrotoxicity in rats: a light and electron microscopy study.

PubMed

Sert, İbrahim Unal; Kilic, Ozcan; Akand, Murat; Saglik, Lutfi; Avunduk, Mustafa Cihat; Erdemli, Esra

2018-03-01

Bisphosphonates are widely used in metastatic cancer such as prostate and breast cancer, and their nephrotoxic effects have been established previously. In this study we aimed to evaluate both the nephrotoxic effects of zoledronic acid (ZA) and the protective effects of vitamin E (Vit-E) on this process under light and electron microscopy. A total of 30 male Sprague-Dawley rats were divided into 3 groups. The first group constituted the control group. The second group was given i.v. ZA of 3 mg/kg once every 3 weeks for 12 weeks from the tail vein. The third group received the same dosage of ZA with an additional i.m . injection of 15 mg Vit-E every week for 12 weeks. Tissues were taken 4 days after the last dose of ZA for histopathological and ultrastructural evaluation. Paller score, tubular epithelial thickness and basal membrane thickness were calculated for each group. For group 2, the p -values are all < 0.001 for Paller score, epitelial thickness, and basal membrane thickness. For group 3 (ZA + Vit. E), the p -values are < 0.001 for Paller score, 0.996 for epitelial thickness, and < 0.001 basal membrane thickness. Significant differences were also observed in ultrastructural changes for group 2. However, adding Vit-E to ZA administration reversed all the histopathological changes to some degree, with statistical significance. Administration of ZA had nephrotoxic effects on rat kidney observed under both light and electron microscopy. Concomitant administration of Vit-E significantly reduces toxic histopathological effects of ZA.

THE CELL CENTERED DATABASE PROJECT: AN UPDATE ON BUILDING COMMUNITY RESOURCES FOR MANAGING AND SHARING 3D IMAGING DATA

PubMed Central

Martone, Maryann E.; Tran, Joshua; Wong, Willy W.; Sargis, Joy; Fong, Lisa; Larson, Stephen; Lamont, Stephan P.; Gupta, Amarnath; Ellisman, Mark H.

2008-01-01

Databases have become integral parts of data management, dissemination and mining in biology. At the Second Annual Conference on Electron Tomography, held in Amsterdam in 2001, we proposed that electron tomography data should be shared in a manner analogous to structural data at the protein and sequence scales. At that time, we outlined our progress in creating a database to bring together cell level imaging data across scales, The Cell Centered Database (CCDB). The CCDB was formally launched in 2002 as an on-line repository of high-resolution 3D light and electron microscopic reconstructions of cells and subcellular structures. It contains 2D, 3D and 4D structural and protein distribution information from confocal, multiphoton and electron microscopy, including correlated light and electron microscopy. Many of the data sets are derived from electron tomography of cells and tissues. In the five years since its debut, we have moved the CCDB from a prototype to a stable resource and expanded the scope of the project to include data management and knowledge engineering. Here we provide an update on the CCDB and how it is used by the scientific community. We also describe our work in developing additional knowledge tools, e.g., ontologies, for annotation and query of electron microscopic data. PMID:18054501

Directional budding of human immunodeficiency virus from monocytes.

PubMed Central

Perotti, M E; Tan, X; Phillips, D M

1996-01-01

Time-lapse cinematography revealed that activated human immunodeficiency virus (HIV)-infected monocytes crawl along surfaces, putting forward a leading pseudopod. Scanning electron micrographs showed monocyte pseudopods associated with spherical structures the size of HIV virions, and transmission electron micrographs revealed HIV virions budding from pseudopods. Filamentous actin (F-actin) was localized by electron microscopy in the pseudopod by heavy meromyosin decoration. Colocalization of F-actin and p24 viral antigen by light microscopy immunofluorescence indicated that F-actin and virus were present on the same pseudopod. These observations indicate that monocytes produce virus from a leading pseudopod. We suggest that HIV secretion at the leading edges of donor monocytes/macrophages may be an efficient way for HIV to infect target cells. PMID:8709212

Damage mechanisms of MoN/SiN multilayer optics for next-generation pulsed XUV light sources.

PubMed

Sobierajski, R; Bruijn, S; Khorsand, A R; Louis, E; van de Kruijs, R W E; Burian, T; Chalupsky, J; Cihelka, J; Gleeson, A; Grzonka, J; Gullikson, E M; Hajkova, V; Hau-Riege, S; Juha, L; Jurek, M; Klinger, D; Krzywinski, J; London, R; Pelka, J B; Płociński, T; Rasiński, M; Tiedtke, K; Toleikis, S; Vysin, L; Wabnitz, H; Bijkerk, F

2011-01-03

We investigated the damage mechanism of MoN/SiN multilayer XUV optics under two extreme conditions: thermal annealing and irradiation with single shot intense XUV pulses from the free-electron laser facility in Hamburg - FLASH. The damage was studied "post-mortem" by means of X-ray diffraction, interference-polarizing optical microscopy, atomic force microscopy, and scanning transmission electron microscopy. Although the timescale of the damage processes and the damage threshold temperatures were different (in the case of annealing it was the dissociation temperature of Mo2N and in the case of XUV irradiation it was the melting temperature of MoN) the main damage mechanism is very similar: molecular dissociation and the formation of N2, leading to bubbles inside the multilayer structure.

Engineered ascorbate peroxidase as a genetically encoded reporter for electron microscopy.

PubMed

Martell, Jeffrey D; Deerinck, Thomas J; Sancak, Yasemin; Poulos, Thomas L; Mootha, Vamsi K; Sosinsky, Gina E; Ellisman, Mark H; Ting, Alice Y

2012-11-01

Electron microscopy (EM) is the standard method for imaging cellular structures with nanometer resolution, but existing genetic tags are inactive in most cellular compartments or require light and can be difficult to use. Here we report the development of 'APEX', a genetically encodable EM tag that is active in all cellular compartments and does not require light. APEX is a monomeric 28-kDa peroxidase that withstands strong EM fixation to give excellent ultrastructural preservation. We demonstrate the utility of APEX for high-resolution EM imaging of a variety of mammalian organelles and specific proteins using a simple and robust labeling procedure. We also fused APEX to the N or C terminus of the mitochondrial calcium uniporter (MCU), a recently identified channel whose topology is disputed. These fusions give EM contrast exclusively in the mitochondrial matrix, suggesting that both the N and C termini of MCU face the matrix. Because APEX staining is not dependent on light activation, APEX should make EM imaging of any cellular protein straightforward, regardless of the size or thickness of the specimen.

Label-free volumetric optical imaging of intact murine brains

NASA Astrophysics Data System (ADS)

Ren, Jian; Choi, Heejin; Chung, Kwanghun; Bouma, Brett E.

2017-04-01

A central effort of today’s neuroscience is to study the brain’s ’wiring diagram’. The nervous system is believed to be a network of neurons interacting with each other through synaptic connection between axons and dendrites, therefore the neuronal connectivity map not only depicts the underlying anatomy, but also has important behavioral implications. Different approaches have been utilized to decipher neuronal circuits, including electron microscopy (EM) and light microscopy (LM). However, these approaches typically demand extensive sectioning and reconstruction for a brain sample. Recently, tissue clearing methods have enabled the investigation of a fully assembled biological system with greatly improved light penetration. Yet, most of these implementations, still require either genetic or exogenous contrast labeling for light microscopy. Here we demonstrate a high-speed approach, termed as Clearing Assisted Scattering Tomography (CAST), where intact brains can be imaged at optical resolution without labeling by leveraging tissue clearing and the scattering contrast of optical frequency domain imaging (OFDI).

Correlative 3D imaging of Whole Mammalian Cells with Light and Electron Microscopy

PubMed Central

Murphy, Gavin E.; Narayan, Kedar; Lowekamp, Bradley C.; Hartnell, Lisa M.; Heymann, Jurgen A. W.; Fu, Jing; Subramaniam, Sriram

2011-01-01

We report methodological advances that extend the current capabilities of ion-abrasion scanning electron microscopy (IA–SEM), also known as focused ion beam scanning electron microscopy, a newly emerging technology for high resolution imaging of large biological specimens in 3D. We establish protocols that enable the routine generation of 3D image stacks of entire plastic-embedded mammalian cells by IA-SEM at resolutions of ~10 to 20 nm at high contrast and with minimal artifacts from the focused ion beam. We build on these advances by describing a detailed approach for carrying out correlative live confocal microscopy and IA–SEM on the same cells. Finally, we demonstrate that by combining correlative imaging with newly developed tools for automated image processing, small 100 nm-sized entities such as HIV-1 or gold beads can be localized in SEM image stacks of whole mammalian cells. We anticipate that these methods will add to the arsenal of tools available for investigating mechanisms underlying host-pathogen interactions, and more generally, the 3D subcellular architecture of mammalian cells and tissues. PMID:21907806

Reversal of histopathologic pulmonary changes with indomethacin.

PubMed

Kerstein, M D; Crivello, M

1980-12-01

There are pulmonary changes documented by light and electron microscopy in a canine model of nonhypotensive shock induced by a lower limb tourniquet. These histopathologic changes are mediated, at least in part, when the dog is treated with indomethacin.

Synthesis and photocatalytic activity of N-doped TiO2 produced in a solid phase reaction

NASA Astrophysics Data System (ADS)

Xin, Gang; Pan, Hongfei; Chen, Dan; Zhang, Zhihua; Wen, Bin

2013-02-01

N-doped TiO2 was synthesized by calcining a mixture of titanic acid and graphitic carbon nitride (g-C3N4) at temperatures above 500 °C. The final samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and UV-vis diffuse reflectance spectra. The photocatalytic activity of N-doped TiO2 was studied by assessing the degradation of methylene blue in an aqueous solution, under visible light and UV light irradiation. It was found that the N-doped TiO2 displayed higher photocatalytic activity than pure TiO2, under both visible and UV light.

Functionalization of a nanostructured hydroxyapatite with Cu(II) compounds as a pesticide: in situ transmission electron microscopy and environmental scanning electron microscopy observations of treated Vitis vinifera L. leaves.

PubMed

Battiston, Enrico; Salvatici, Maria C; Lavacchi, Alessandro; Gatti, Antonietta; Di Marco, Stefano; Mugnai, Laura

2018-02-19

The present study evaluated a biocompatible material for plant protection with the aim of reducing the amount of active substance applied. We used a synthetic hydroxyapatite (HA) that has been studied extensively as a consequence of its bioactivity and biocompatibility. An aggregation between HA nanoparticles and four Cu(II) compounds applied to Vitis vinifera L. leaves as a pesticide was studied. Formulations were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS) and electron microscopy and applied in planta to verify particle aggregation and efficiency in controlling the pathogen Plasmopara viticola. The XRD patterns showed different crystalline phases dependig on the Cu(II) compound formulated with HA particles, DLS showed that nanostructured particles are stable as aggregates out of the nanometer range and, in all formulations, transmission electron microscopy (TEM) and environmental scanning electron microscopy (ESEM) microscopy showed large aggregates which were partially nanostructured and were recognized as stable in their micrometric dimensions. Such particles did not show phytotoxic effects after their application in planta. A formulation based on HA and a soluble Cu(II) compound showed promising results in the control of the fungal pathogen, confirming the potential role of HA as an innovative delivery system of Cu(II) ions. The present work indicates the possibility of improving the biological activity of a bioactive substance by modifying its structure through an achievable formulation with a biocompatible material. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Enhanced visible light photocatalytic activity of copper-doped titanium oxide-zinc oxide heterojunction for methyl orange degradation

NASA Astrophysics Data System (ADS)

Dorraj, Masoumeh; Alizadeh, Mahdi; Sairi, Nor Asrina; Basirun, Wan Jefrey; Goh, Boon Tong; Woi, Pei Meng; Alias, Yatimah

2017-08-01

A novel Cu-doped TiO2 coupled with ZnO nanoparticles (Cu-TiO2/ZnO) was prepared by sol-gel method and subsequent precipitation for methyl orange (MO) photodegradation under visible light irradiation. The compositions and shapes of the as-prepared Cu-TiO2/ZnO nanocomposites were characterized by photoluminescence spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, UV-vis diffuse reflectance spectra and Brunauer-Emmett-Teller adsorption isotherm techniques. The Cu-TiO2/ZnO nanocomposites showed considerably higher photocatalytic activity for MO removal from water under visible light irradiation than that of single-doped semiconductors. The effects of Cu-TiO2 and ZnO mass ratios on the photocatalytic reaction were also studied. A coupling percentage of 30% ZnO exhibited the highest photocatalytic activity. The enhanced photocatalytic activity of the Cu-TiO2/ZnO nanocomposites was mainly attributed to heterojunction formation, which allowed the efficient separation of photoinduced electron-hole pairs at the interface. Moreover, these novel nanocomposites could be recycled during MO degradation in a three-cycle experiment without evident deactivation, which is particularly important in environmental applications.

Synthesis and photocatalytic performance of reduced graphene oxide-TiO2 nanocomposites for orange II degradation under UV light irradiation.

PubMed

Li, Tengfei; Wang, Tiecheng; Qu, Guangzhou; Liang, Dongli; Hu, Shibin

2017-05-01

To enhance the photocatalytic activity of TiO 2 , reduced graphene oxide-TiO 2 (RGO-TiO 2 ) composites with sandwich-like structure were synthesized using a simple solvothermal method. The morphology, crystalline information, and structural property of the photocatalyst were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier transmission infrared spectroscopy. The photocatalytic performances of the RGO-TiO 2 composites were evaluated by the degradation of orange II (AO7) in water under UV light irradiation. The results showed that the RGO-TiO 2 composites exhibited much higher photocatalytic activity than TiO 2 and that the removal efficiency of AO7 could reach above 95% only after 20 min of UV light irradiation under the optimum condition. The improved photocatalytic activity might be attributed to the improved charge transfer and significant separation of the photoinduced electrons and holes in the presence of a two-dimensional graphene network. The results of recycling experiments show that RGO-TiO 2 composites have a high photostability, which is expected in the practical application. Radical trapping experiments indicated that ·OH plays a crucial role in the process of AO7 degradation.

Automated sub-5 nm image registration in integrated correlative fluorescence and electron microscopy using cathodoluminescence pointers

NASA Astrophysics Data System (ADS)

Haring, Martijn T.; Liv, Nalan; Zonnevylle, A. Christiaan; Narvaez, Angela C.; Voortman, Lenard M.; Kruit, Pieter; Hoogenboom, Jacob P.

2017-03-01

In the biological sciences, data from fluorescence and electron microscopy is correlated to allow fluorescence biomolecule identification within the cellular ultrastructure and/or ultrastructural analysis following live-cell imaging. High-accuracy (sub-100 nm) image overlay requires the addition of fiducial markers, which makes overlay accuracy dependent on the number of fiducials present in the region of interest. Here, we report an automated method for light-electron image overlay at high accuracy, i.e. below 5 nm. Our method relies on direct visualization of the electron beam position in the fluorescence detection channel using cathodoluminescence pointers. We show that image overlay using cathodoluminescence pointers corrects for image distortions, is independent of user interpretation, and does not require fiducials, allowing image correlation with molecular precision anywhere on a sample.

Automated sub-5 nm image registration in integrated correlative fluorescence and electron microscopy using cathodoluminescence pointers.

PubMed

Haring, Martijn T; Liv, Nalan; Zonnevylle, A Christiaan; Narvaez, Angela C; Voortman, Lenard M; Kruit, Pieter; Hoogenboom, Jacob P

2017-03-02

In the biological sciences, data from fluorescence and electron microscopy is correlated to allow fluorescence biomolecule identification within the cellular ultrastructure and/or ultrastructural analysis following live-cell imaging. High-accuracy (sub-100 nm) image overlay requires the addition of fiducial markers, which makes overlay accuracy dependent on the number of fiducials present in the region of interest. Here, we report an automated method for light-electron image overlay at high accuracy, i.e. below 5 nm. Our method relies on direct visualization of the electron beam position in the fluorescence detection channel using cathodoluminescence pointers. We show that image overlay using cathodoluminescence pointers corrects for image distortions, is independent of user interpretation, and does not require fiducials, allowing image correlation with molecular precision anywhere on a sample.

Automated sub-5 nm image registration in integrated correlative fluorescence and electron microscopy using cathodoluminescence pointers

PubMed Central

Haring, Martijn T.; Liv, Nalan; Zonnevylle, A. Christiaan; Narvaez, Angela C.; Voortman, Lenard M.; Kruit, Pieter; Hoogenboom, Jacob P.

2017-01-01

In the biological sciences, data from fluorescence and electron microscopy is correlated to allow fluorescence biomolecule identification within the cellular ultrastructure and/or ultrastructural analysis following live-cell imaging. High-accuracy (sub-100 nm) image overlay requires the addition of fiducial markers, which makes overlay accuracy dependent on the number of fiducials present in the region of interest. Here, we report an automated method for light-electron image overlay at high accuracy, i.e. below 5 nm. Our method relies on direct visualization of the electron beam position in the fluorescence detection channel using cathodoluminescence pointers. We show that image overlay using cathodoluminescence pointers corrects for image distortions, is independent of user interpretation, and does not require fiducials, allowing image correlation with molecular precision anywhere on a sample. PMID:28252673

ELECTRON MICROSCOPIC STUDY OF THE ATPASE ACTIVITY OF THE BAI STRAIN A (MYELOBLASTOSIS) AVIAN TUMOR VIRUS

PubMed Central

Novikoff, Alex B.; de Thé, Guy; Beard, D.; Beard, J. W.

1962-01-01

Thymus glands of chicks with leukemia induced by BAI strain A (myeloblastosis) virus were fixed in cold 4 per cent formaldehyde-sucrose. Frozen sections were incubated in the ATPase medium of Wachstein and Meisel and studied by light microscopy and electron microscopy. The ATPase activity of the virus is localized to the outermost membrane of the virus. The membrane of the blast-like cells of the thymus cortex from which the virus emerges, by budding, also possesses such activity. It appears likely that the outermost membrane of the virus is derived from the plasma membrane of these cells. PMID:13939125

Visualizing light with electrons

NASA Astrophysics Data System (ADS)

Fitzgerald, J. P. S.; Word, R. C.; Koenenkamp, R.

2014-03-01

In multiphoton photoemission electron microscopy (nP-PEEM) electrons are emitted from surfaces at a rate proportional to the surface electromagnetic field amplitude. We use 2P-PEEM to give nanometer scale visualizations of light of diffracted and waveguide fields around various microstructures. We use Fourier analysis to determine the phase and amplitude of surface fields in relation to incident light from the interference patterns. To provide quick and intuitive simulations of surface fields, we employ two dimensional Fresnel-Kirchhoff integration, a technique based on freely propagating waves and Huygens' principle. We find generally good agreement between simulations and experiment. Additionally diffracted wave simulations exhibit greater phase accuracy, indicating that these waves are well represented by a two dimensional approximation. The authors gratefully acknowledge funding of this research by the US-DOE Basic Science Office under Contract DE-FG02-10ER46406.

Correlative two-photon and serial block face scanning electron microscopy in neuronal tissue using 3D near-infrared branding maps.

PubMed

Lees, Robert M; Peddie, Christopher J; Collinson, Lucy M; Ashby, Michael C; Verkade, Paul

2017-01-01

Linking cellular structure and function has always been a key goal of microscopy, but obtaining high resolution spatial and temporal information from the same specimen is a fundamental challenge. Two-photon (2P) microscopy allows imaging deep inside intact tissue, bringing great insight into the structural and functional dynamics of cells in their physiological environment. At the nanoscale, the complex ultrastructure of a cell's environment in tissue can be reconstructed in three dimensions (3D) using serial block face scanning electron microscopy (SBF-SEM). This provides a snapshot of high resolution structural information pertaining to the shape, organization, and localization of multiple subcellular structures at the same time. The pairing of these two imaging modalities in the same specimen provides key information to relate cellular dynamics to the ultrastructural environment. Until recently, approaches to relocate a region of interest (ROI) in tissue from 2P microscopy for SBF-SEM have been inefficient or unreliable. However, near-infrared branding (NIRB) overcomes this by using the laser from a multiphoton microscope to create fiducial markers for accurate correlation of 2P and electron microscopy (EM) imaging volumes. The process is quick and can be user defined for each sample. Here, to increase the efficiency of ROI relocation, multiple NIRB marks are used in 3D to target ultramicrotomy. A workflow is described and discussed to obtain a data set for 3D correlated light and electron microscopy, using three different preparations of brain tissue as examples. Copyright © 2017 Elsevier Inc. All rights reserved.

Optical sectioning in wide-field microscopy obtained by dynamic structured light illumination and detection based on a smart pixel detector array.

PubMed

Mitić, Jelena; Anhut, Tiemo; Meier, Matthias; Ducros, Mathieu; Serov, Alexander; Lasser, Theo

2003-05-01

Optical sectioning in wide-field microscopy is achieved by illumination of the object with a continuously moving single-spatial-frequency pattern and detecting the image with a smart pixel detector array. This detector performs an on-chip electronic signal processing that extracts the optically sectioned image. The optically sectioned image is directly observed in real time without any additional postprocessing.

Three-Dimensional BiOI/BiOX (X = Cl or Br) Nanohybrids for Enhanced Visible-Light Photocatalytic Activity

PubMed Central

Liu, Yazi; Xu, Jian; Wang, Liqiong; Zhang, Huayang; Xu, Ping; Duan, Xiaoguang; Sun, Hongqi; Wang, Shaobin

2017-01-01

Three-dimensional flower-like BiOI/BiOX (X = Br or Cl) hybrids were synthesized via a facile one-pot solvothermal approach. With systematic characterizations by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), the Brunauer-Emmett-Teller (BET)specific surface area, X-ray photoelectron spectroscopy (XPS), and the UV-Vis diffuse reflectance spectra (DRS), the BiOI/BiOCl composites showed a fluffy and porous 3-D architecture with a large specific surface area (SSA) and high capability for light absorption. Among all the BiOX (X = Cl, Br, I) and BiOI/BiOX (X = Cl or Br) composites, BiOI/BiOCl stands out as the most efficient photocatalyst under both visible and UV light irradiations for methyl orange (MO) oxidation. The reaction rate of MO degradation on BiOI/BiOCl was 2.1 times higher than that on pure BiOI under visible light. Moreover, BiOI/BiOCl exhibited enhanced water oxidation efficiency for O2 evolution which was 1.5 times higher than BiOI. The enhancement of photocatalytic activity could be attributed to the formation of a heterojunction between BiOI and BiOCl, with a nanoporous structure, a larger SSA, and a stronger light absorbance capacity especially in the visible-light region. The in situ electron paramagnetic resonance (EPR) revealed that BiOI/BiOCl composites could effectively evolve superoxide radicals and hydroxyl radicals for photodegradation, and the superoxide radicals are the dominant reactive species. The superb photocatalytic activity of BiOI/BiOCl could be utilized for the degradation of various industrial dyes under natural sunlight irradiation which is of high significance for the remediation of industrial wastewater in the future. PMID:28336897

Notes on Citrullius spp. and Acanthosicyos naudinianus

USDA-ARS?s Scientific Manuscript database

Scanning electron and light microscopy were utilized to examine pollen of the currently recognized species (and forms) within the genus Citrullus (Cucurbitaceae). Materials examined included: C. lanatus (Thunb.) Matsum. & Nakai including the citron (C. amarus Schrad.) and egusi (C. lanatus subsp. mu...

Effects of radiation upon the light-sensing elements of the retina as characterized by scanning electron microscopy

NASA Technical Reports Server (NTRS)

Malachowski, M. J.; Tobias, C. A.; Leith, J. T.

1977-01-01

A model system using Necturus maculosus, the common mudpuppy, was established for evaluating effects of radiation upon the light-sensing elements of the retina. Accelerated heavy ions of helium and neon from the Berkeley Bevalac were used. A number of criteria were chosen to characterize radiation damage by observing morphological changes with the scanning electron microscope. The studies indicated retina sensitivity to high-LET (neon) particles at radiation levels below 10 rads (7 particles per visual element) whereas no significant effects were seen from fast helium ions below 50 rads.

Light and electron microscope study of the neurotropism of Powassan virus strain P-40.

PubMed

Isachkova, L M; Shestopalova, N M; Frolova, M P; Reingold, V N

1979-01-01

Brains of adult white mice inoculated with the P-40 strain of Powassan virus isolated in Primorsky Krai (U.S.S.R) from ticks were studied by light and electron microscopy. Accumulations of virus particles were found in neurons and their dendrites and axons, in glial cells, and in intercellular spaces. In the nerve cells, most prevalent were changes of the type of chromatolysis and formation of small vacuoles, associated with the alteration of the endoplasmic reticulum induced by virus morphogenesis. In virus-affected cells, multilayer dense membranes were found.

Efficient visible light induced synthesis of silver nanoparticles by Penicillium polonicum ARA 10 isolated from Chetomorpha antennina and its antibacterial efficacy against Salmonella enterica serovar Typhimurium.

PubMed

Neethu, Sahadevan; Midhun, Sebastian Jose; Sunil, M A; Soumya, Soman; Radhakrishnan, E K; Jyothis, Mathew

2018-03-01

The green synthesis of silver nanoparticles (AgNPs) using biological systems such as fungi has evolved to become an important area of nanobiotechnology. Herein, we report for the first time the light-induced extracellular synthesis of silver nanoparticles using algicolous endophytic fungus Penicillium polonicum ARA 10, isolated from the marine green alga Chetomorpha antennina. Parametric optimization, including the concentration of AgNO 3 , fungal biomass, ratio of cell filtrate and AgNO 3 , pH, reaction time and presence of light, was done for rapid AgNPs production. The obtained silver nanoparticles (AgNPs) were characterized by UV-Visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and Transmission electron microscopy (HRTEM-EDAX). The AgNPs showed a characteristic UV-visible peak at 430 nm with an average size of 10-15 nm. The NH stretches in FTIR indicate the presence of protein molecules. The Raman vibrational bands suggest that the molecules responsible for the reduction and stability of AgNPs were extracellular proteins produced by P.polonicum. Antibacterial evaluation of AgNPs against the major foodborne bacterial pathogen Salmonella enterica serovar Typhimurium MTCC 1251, was assessed by well diffusion, Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assay. Killing kinetic studies revealed complete killing of the bacterial cells within 4 h and the bactericidal nature of synthesized nanoparticles was confirmed by fluorescent microscopy and scanning electron microscopy. Furthermore, the bactericidal studies with Transmission electron microscopy (TEM) at different time intervals explored the presence of AgNPs in the cell wall of S.Typhimurium at about 30 min and the complete bacterial lysis was found at 24 h. The current research opens an insight into the green synthesis of AgNPs and the mechanism of bacterial lysis by direct damage to the cell wall. Copyright © 2018 Elsevier B.V. All rights reserved.

ELECTRON MICROSCOPY OF HELA CELLS INFECTED WITH ADENOVIRUSES

PubMed Central

Harford, Carl G.; Hamlin, Alice; Parker, Esther; van Ravenswaay, Theodore

1956-01-01

HeLa cells were infected with adenoviruses (types 1–4) and sectioned for electron microscopy after intervals of 20 to 48 hours. Clusters of virus-like particles were found within the nuclei of infected cultures but not in those of uninfected controls. The particles were often arranged in rows as if in crystalline formation. Maximal diameter of particles was approximately 65 mµ, and internal bodies were demonstrated. Lesions of infected cells included target-like structures of the nuclear membrane, large nuclear vacuoles (type 2), and increased numbers of large irregular electron-dense granules in the cytoplasm 48 hours after infection. Examination of infected cultures by light microscopy, using the Feulgen reaction, showed intranuclear inclusion bodies and a cytopathogenic effect consisting of clumping of cells without pyknosis of nuclei. A lipide stain showed numerous cytoplasmic granules that were not identical with the large, irregular, electron-dense granules of the cytoplasm. Practically all the cells showed the viral cytopathogenic effect, but only a minority of cells were found to contain virus-like particles or intranuclear inclusion bodies. PMID:13357696

Enhanced photocatalytic performance of RGO/Ag nanocomposites produced via a facile microwave irradiation for the degradation of Rhodamine B in aqueous solution

NASA Astrophysics Data System (ADS)

Divya, K. S.; Chandran, Akash; Reethu, V. N.; Mathew, Suresh

2018-06-01

A series of RGO/Ag nanocomposites with different weight addition ratios of graphene oxide (GO) have been successfully prepared in situ through the simultaneous reduction of GO and AgNO3 via a facile microwave irradiation. X-ray diffraction analysis, Fourier Transform Infrared Spectroscopy, UV-vis diffuse reflectance spectra, Scanning electron microscopy, Photoluminescence spectra, Raman spectra, Atomic Force Microscopy, X-ray photoelectron spectroscopy (XPS) and Transmission electron microscopy are employed to determine the properties of the samples. It is found that RGO/Ag nanocomposites with a proper weight addition ratios of GO exhibit higher photocatalytic activity toward liquid phase photodegradation of Rhodamine B under visible light irradiation. The improved photoactivity of RGO/Ag nanocomposites can be ascribed to the integrative synergestic effect of enhanced adsorption capacity, the prolonged lifetime of photogenerated electron-hole pairs and effective interfacial hybridization between RGO and Ag nanoparticles. This study also shows that graphene sheets act as electronic conductive channels to efficiently separate charge carriers from Ag nanoparticles.

Rare-earth-doped nanophosphors for multicolor cathodoluminescence nanobioimaging using scanning transmission electron microscopy.

PubMed

Furukawa, Taichi; Fukushima, Shoichiro; Niioka, Hirohiko; Yamamoto, Naoki; Miyake, Jun; Araki, Tsutomu; Hashimoto, Mamoru

2015-05-01

We describe rare-earth-doped nanophosphors (RE-NPs) for biological imaging using cathodoluminescence(CL) microscopy based on scanning transmission electron microscopy (STEM). We report the first demonstration of multicolor CL nanobioimaging using STEM with nanophosphors. The CL spectra of the synthesized nanophosphors (Y2O3∶Eu, Y2O3∶Tb) were sufficiently narrow to be distinguished. From CL images of RE-NPs on an elastic carbon-coated copper grid, the spatial resolution was beyond the diffraction limit of light.Y2O3∶Tb and Y2O3∶Eu RE-NPs showed a remarkable resistance against electron beam exposure even at high acceleration voltage (80 kV) and retained a CL intensity of more than 97% compared with the initial intensity for 1 min. In biological CL imaging with STEM, heavy-metal-stained cell sections containing the RE-NPs were prepared,and both the CL images of RE-NPs and cellular structures, such as mitochondria, were clearly observed from STEM images with high contrast. The cellular CL imaging using RE-NPs also had high spatial resolution even though heavy-metal-stained cells are normally regarded as highly scattering media. Moreover, since theRE-NPs exhibit photoluminescence (PL) excited by UV light, they are useful for multimodal correlative imaging using CL and PL.

Differential localization of SAP102 and PSD-95 is revealed in hippocampal spines using super-resolution light microscopy.

PubMed

Zheng, Chan-Ying; Wang, Ya-Xia; Kachar, Bechara; Petralia, Ronald S

2011-01-01

Synapse-associated protein 102 (SAP102) and postsynaptic density 95 (PSD-95) are two major cytoskeleton proteins in the postsynaptic density (PSD). Both of them belong to the membrane-associated guanylate kinase (MAGUK) family, which clusters and anchors glutamate receptors and other proteins at synapses. In our previous study, we found that SAP102 and PSD-95 have different distributions, using combined light/electron microscopy (LM/EM) methods.1 Here, we double labeled endogenous SAP102 and PSD-95 in mature hippocampal neurons, and then took images by two different kinds of super resolution microscopy-Stimulated Emission Depletion microscopy (STED) and DeltaVision OMX 3D super resolution microscopy. We found that our 2D and 3D super resolution data were consistent with our previous LM/EM data, showing significant differences in the localization of SAP102 and PSD-95 in spines: SAP102 is distributed in both the PSD and cytoplasm of spines, while PSD-95 is concentrated only in the PSD area. These results indicate functional differences between SAP102 and PSD-95 in synaptic organization and plasticity.

Learning a cost function for microscope image segmentation.

PubMed

Nilufar, Sharmin; Perkins, Theodore J

2014-01-01

Quantitative analysis of microscopy images is increasingly important in clinical researchers' efforts to unravel the cellular and molecular determinants of disease, and for pathological analysis of tissue samples. Yet, manual segmentation and measurement of cells or other features in images remains the norm in many fields. We report on a new system that aims for robust and accurate semi-automated analysis of microscope images. A user interactively outlines one or more examples of a target object in a training image. We then learn a cost function for detecting more objects of the same type, either in the same or different images. The cost function is incorporated into an active contour model, which can efficiently determine optimal boundaries by dynamic programming. We validate our approach and compare it to some standard alternatives on three different types of microscopic images: light microscopy of blood cells, light microscopy of muscle tissue sections, and electron microscopy cross-sections of axons and their myelin sheaths.

Measurement of replication structures at the nanometer scale using super-resolution light microscopy

PubMed Central

Baddeley, D.; Chagin, V. O.; Schermelleh, L.; Martin, S.; Pombo, A.; Carlton, P. M.; Gahl, A.; Domaing, P.; Birk, U.; Leonhardt, H.; Cremer, C.; Cardoso, M. C.

2010-01-01

DNA replication, similar to other cellular processes, occurs within dynamic macromolecular structures. Any comprehensive understanding ultimately requires quantitative data to establish and test models of genome duplication. We used two different super-resolution light microscopy techniques to directly measure and compare the size and numbers of replication foci in mammalian cells. This analysis showed that replication foci vary in size from 210 nm down to 40 nm. Remarkably, spatially modulated illumination (SMI) and 3D-structured illumination microscopy (3D-SIM) both showed an average size of 125 nm that was conserved throughout S-phase and independent of the labeling method, suggesting a basic unit of genome duplication. Interestingly, the improved optical 3D resolution identified 3- to 5-fold more distinct replication foci than previously reported. These results show that optical nanoscopy techniques enable accurate measurements of cellular structures at a level previously achieved only by electron microscopy and highlight the possibility of high-throughput, multispectral 3D analyses. PMID:19864256

Adhesion and the Lamination/Failure of Stretchable Organic and Composite Organic/Inorganic Electronic Structures

NASA Astrophysics Data System (ADS)

Yu, Deying

Stretchable organic electronics have emerged as interesting technologies for several applications where stretchability is considered important. The easy and low-cost deposition procedures for the fabrication of stretchable organic solar cells and organic light emitting devices reduce the overall cost for the fabrication of these devices. However, the interfacial cracks and defects at the interfaces of the devices, during fabrication, are detrimental to the performance of stretchable organic electronic devices. Also, as the devices are deformed under service conditions, it is possible for cracks to grow. Furthermore, the multilayered structures of the devices can fail due to the delamination and buckling of the layered structures. There is, therefore, a need to study the failure mechanism in the layered structures that are relevant to stretchable organic electronic devices. Hence, in this study, a combined experimental, analytical and computational approach is used to study the effects of adhesion and deformation on the failure mechanisms in structures that are relevant to stretchable electronic devices. First, the failure mechanisms are studied in stretchable inorganic electronic structures. The wrinkles and buckles are formed by the unloading of pre-stretched PDMS/Au structure, after the evaporation of nano-scale Au layers. They are then characterized using atomic force microscopy and scanning electron microscopy. Analytical models are used to determine the critical stresses for wrinkling and buckling. The interfacial cracking and film buckling that can occur are also studied using finite element simulations. The implications of the results are then discussed for the potential applications of micro-wrinkles and micro-buckles in the stretchable electronic structures and biomedical devices. Subsequently, the adhesion between bi-material pairs that are relevant to organic light emitting devices, composite organic/inorganic light emitting devices, organic bulk heterojunction solar cells, and composite organic/inorganic solar cells on flexible substrates, is measured using force microscopy (AFM) techniques. The AFM measurements are incorporated into the Derjaguin-Muller-Toporov model to calculate the adhesion energies. The implications of the results are then discussed for the design of robust organic and composite organic/inorganic electronic devices. Finally, the lamination of organic solar cells and organic light emitting devices is studied using a combination of experimental, computational, and analytical approaches. First, the effects of applied lamination force (on contact between the laminated layers) are studied using experiments and models. The crack driving forces associated with the interfacial cracks that form at the interfaces between layers (at the bi-material interfaces) are estimated along with the critical interfacial crack driving forces associated with the separation of thin films, after layer transfer. The conditions for successful lamination are predicted using a combination of experiments and models. Guidelines are developed for the lamination of low-cost organic electronic structures.

A Global Approach for Quantitative Super Resolution and Electron Microscopy on Cryo and Epoxy Sections Using Self-labeling Protein Tags.

PubMed

Müller, Andreas; Neukam, Martin; Ivanova, Anna; Sönmez, Anke; Münster, Carla; Kretschmar, Susanne; Kalaidzidis, Yannis; Kurth, Thomas; Verbavatz, Jean-Marc; Solimena, Michele

2017-02-02

Correlative light and electron microscopy (CLEM) is a powerful approach to investigate the molecular ultrastructure of labeled cell compartments. However, quantitative CLEM studies are rare, mainly due to small sample sizes and the sensitivity of fluorescent proteins to strong fixatives and contrasting reagents for EM. Here, we show that fusion of a self-labeling protein to insulin allows for the quantification of age-distinct insulin granule pools in pancreatic beta cells by a combination of super resolution and transmission electron microscopy on Tokuyasu cryosections. In contrast to fluorescent proteins like GFP organic dyes covalently bound to self-labeling proteins retain their fluorescence also in epoxy resin following high pressure freezing and freeze substitution, or remarkably even after strong chemical fixation. This enables for the assessment of age-defined granule morphology and degradation. Finally, we demonstrate that this CLEM protocol is highly versatile, being suitable for single and dual fluorescent labeling and detection of different proteins with optimal ultrastructure preservation and contrast.

A national facility for biological cryo-electron microscopy

PubMed Central

Saibil, Helen R.; Grünewald, Kay; Stuart, David I.

2015-01-01

Three-dimensional electron microscopy is an enormously powerful tool for structural biologists. It is now able to provide an understanding of the molecular machinery of cells, disease processes and the actions of pathogenic organisms from atomic detail through to the cellular context. However, cutting-edge research in this field requires very substantial resources for equipment, infrastructure and expertise. Here, a brief overview is provided of the plans for a UK national three-dimensional electron-microscopy facility for integrated structural biology to enable internationally leading research on the machinery of life. State-of-the-art equipment operated with expert support will be provided, optimized for both atomic-level single-particle analysis of purified macromolecules and complexes and for tomography of cell sections. The access to and organization of the facility will be modelled on the highly successful macromolecular crystallography (MX) synchrotron beamlines, and will be embedded at the Diamond Light Source, facilitating the development of user-friendly workflows providing near-real-time experimental feedback. PMID:25615867

Characterization of contaminant removal by an optical strip material

NASA Astrophysics Data System (ADS)

Hamilton, James P.; Frigo, S. P.; Caroll, Brenden J.; Assoufidyen, L.; Lewis, Matthew S.; Cook, Russell E.; de Carlo, F.

2001-03-01

Department of Chemistry and Engineering Physics, University of Wisconsin-Platteville, Platteville, WI 53818 Advanced Photon Source, X-Ray Facilities Division, Argonne National Laboratory, Advanced Photon Source, User Program Division, Argonne National Laboratory, *Electron Microscopy Center, Materials Science Division, Argonne National Laboratory, Argonne National Laboratory, 9700 S. Cass Ave., Argonne IL 60439-4856 USA A novel optical strip coating material, Opticlean, has been shown to safely remove fingerprints, particles and contamination from a variety of optical surfaces including coated glass, Si and first surface mirrors. Contaminant removal was monitored by Nomarski, Atomic Force and Scanning Electron Microscopy. Sub-micron features on diffraction gratings and silicon wafers were also cleaned without leaving light scattering particles on the surface. **This work was supported in part by the U.S. Department of Energy, Basic Energy Sciences-Materials Sciences, under contract no. W-31-109-ENG-38. The authors acknowledge the support and facilities provided by the Advanced Photon Source and the Electron Microscopy Center at Argonne National Laboratory.

Momentum microscopy of ? single crystals with detailed surface characterisation

NASA Astrophysics Data System (ADS)

Ellguth, M.; Tusche, C.; Iga, F.; Suga, S.

2016-11-01

We report the in situ preparation of surfaces of the proposed topological Kondo insulator SmB? by controlled cycles of Ar ion sputtering and annealing. The procedure provides a reproducible way for the preparation of Sm- or B-rich surface terminations by low (?1080 ?C) or high (?1200 ?C) temperature annealing. The surface quality and termination were checked by low energy electron diffraction and Auger electron spectroscopy. Photoemission studies were carried out using momentum microscopy and two laboratory light sources providing polarised radiation with an energy of 6 eV (fourth harmonic of a pulsed Ti:Sapphire laser) and unpolarised radiation with an energy of 21.2 eV (He-I line of a gas discharge lamp). Full dispersions of electronic states in a wide two-dimensional momentum space were obtained by momentum microscopy from the in situ prepared Sm-terminated surface. The shape of the Fermi surface is discussed based on the sections through the bulk Brillouin zone sampled by the different photon energies.

Characterization of magnetic nanoparticle by dynamic light scattering

PubMed Central

2013-01-01

Here we provide a complete review on the use of dynamic light scattering (DLS) to study the size distribution and colloidal stability of magnetic nanoparticles (MNPs). The mathematical analysis involved in obtaining size information from the correlation function and the calculation of Z-average are introduced. Contributions from various variables, such as surface coating, size differences, and concentration of particles, are elaborated within the context of measurement data. Comparison with other sizing techniques, such as transmission electron microscopy and dark-field microscopy, revealed both the advantages and disadvantages of DLS in measuring the size of magnetic nanoparticles. The self-assembly process of MNP with anisotropic structure can also be monitored effectively by DLS. PMID:24011350

Identification of oleoresin in epoxy-embedded slash pine tissue

DOE Office of Scientific and Technical Information (OSTI.GOV)

Birchem, R.; Brown, C.L.

1978-01-01

Sudan black B stains oleoresin blue-black in epoxy-embedded material as well as in living tissue. The Sudan black B staining properties of oleoresin are similar to those of lipid, but it can be distinguished from tannin, which stains brown. Practically all oleoresin present in resin ducts and intercellular spaces, and much of that contained in epithelial and ray cells, is extracted in preparatory procedures for electron microscopy. A fixation procedure is proposed which preserves significantly more oleoresin in situ. The use of Sudan black B enables one to localize oleoresin by light microscopy, and permits direct comparison of adjacent sectionsmore » of epoxy-embedded material at the ultrastructure level. Ultrastructurally oleoresin and lipid possess similar electron densities and can be distinguished from the highly electron-opaque tannin deposits.« less

The microcomputer in cell and neurobiology research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mize, R.R.

1985-01-01

This book contains 21 chapters. They are divided into the following sections: The Microcomputer as a Research Tool, Microcomputer Uses in Light and Electron Microscopy, Microcomputer Uses in Morphometry, Serial Section Reconstruction, Microcomputer Uses in Imaging and Densitometry, and Microcomputer Uses in Electrophysiology.

Structure and location of macronutrients in ancient and alternative crops (abstract)

USDA-ARS?s Scientific Manuscript database

Structure, histochemistry and composition of mature seeds of several ancient or alternative crops were studied by light and electron microscopies to localize specific macronutrients including protein, starch, non-starch carbohydrates and lipid. Botanically, these seeds fall into different classifica...

Clavicipitaceous anamorphic endophytes in Hordeum germplasm

Treesearch

A. Dan Wilson

2007-01-01

The incidence of clavicipitaceous anamorphic endophytes, non-choke inducing endosymbiotic fungi of the genus Neotyphodium that systemically infect grasses, in eighteen Hordeum species from the U.S. National Plant Germplasm System was examined using light and Scanning Electron Microscopy (SEM). Seventeen plant inventory accessions...

The collection of MicroED data for macromolecular crystallography.

PubMed

Shi, Dan; Nannenga, Brent L; de la Cruz, M Jason; Liu, Jinyang; Sawtelle, Steven; Calero, Guillermo; Reyes, Francis E; Hattne, Johan; Gonen, Tamir

2016-05-01

The formation of large, well-ordered crystals for crystallographic experiments remains a crucial bottleneck to the structural understanding of many important biological systems. To help alleviate this problem in crystallography, we have developed the MicroED method for the collection of electron diffraction data from 3D microcrystals and nanocrystals of radiation-sensitive biological material. In this approach, liquid solutions containing protein microcrystals are deposited on carbon-coated electron microscopy grids and are vitrified by plunging them into liquid ethane. MicroED data are collected for each selected crystal using cryo-electron microscopy, in which the crystal is diffracted using very few electrons as the stage is continuously rotated. This protocol gives advice on how to identify microcrystals by light microscopy or by negative-stain electron microscopy in samples obtained from standard protein crystallization experiments. The protocol also includes information about custom-designed equipment for controlling crystal rotation and software for recording experimental parameters in diffraction image metadata. Identifying microcrystals, preparing samples and setting up the microscope for diffraction data collection take approximately half an hour for each step. Screening microcrystals for quality diffraction takes roughly an hour, and the collection of a single data set is ∼10 min in duration. Complete data sets and resulting high-resolution structures can be obtained from a single crystal or by merging data from multiple crystals.

Heroin crystal nephropathy

PubMed Central

Bautista, Josef Edrik Keith; Merhi, Basma; Gregory, Oliver; Hu, Susie; Henriksen, Kammi; Gohh, Reginald

2015-01-01

In this paper we present an interesting case of acute kidney injury and severe metabolic alkalosis in a patient with a history of heavy heroin abuse. Urine microscopy showed numerous broomstick-like crystals. These crystals are also identified in light and electron microscopy. We hypothesize that heroin crystalizes in an alkaline pH, resulting in tubular obstruction and acute kidney injury. Management is mainly supportive as there is no known specific therapy for this condition. This paper highlights the utility of urine microscopy in diagnosing the etiology of acute kidney injury and proposes a novel disease called heroin crystal nephropathy. PMID:26034599

Techniques for the Cellular and Subcellular Localization of Endocannabinoid Receptors and Enzymes in the Mammalian Brain.

PubMed

Cristino, Luigia; Imperatore, Roberta; Di Marzo, Vincenzo

2017-01-01

This chapter attempts to piece together knowledge about new advanced microscopy techniques to study the neuroanatomical distribution of endocannabinoid receptors and enzymes at the level of cellular and subcellular structures and organelles in the brain. Techniques ranging from light to electron microscopy up to the new advanced LBM, PALM, and STORM super-resolution microscopy will be discussed in the context of their contribution to define the spatial distribution and organization of receptors and enzymes of the endocannabinoid system (ECS), and to better understand ECS brain functions. © 2017 Elsevier Inc. All rights reserved.

Utilization of visible to NIR light energy by Yb+3, Er+3 and Tm+3 doped BiVO4 for the photocatalytic degradation of methylene blue

NASA Astrophysics Data System (ADS)

Regmi, Chhabilal; Kshetri, Yuwaraj K.; Ray, Schindra Kumar; Pandey, Ramesh Prasad; Lee, Soo Wohn

2017-01-01

Lanthanide-doped BiVO4 semiconductors with efficient photocatalytic activities over a broad range of the solar light spectrum have been synthesized by the microwave hydrothermal method using ethylenediaminetetraacetic acid (EDTA). The structural, morphological, and optical properties of the as-synthesized samples were evaluated by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray powder diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, UV-vis diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy (PL). The chemical compositions were analyzed by X-ray photoelectron spectroscopy (XPS). The toxicity of the samples was measured using Mus musculus skin melanoma cells (B16-F10 (ATCC® CRL-6475™)) and were found to be nontoxic for human cells. The photocatalytic efficiency of the prepared samples was evaluated by methylene blue (MB) degradation. The best photocatalytic activity was shown by BiVO4 with 6:3:3 mol percentage of Yb+3:Er+3:Tm+3 in all solar light spectrum. The synthesized samples possess low band gap energy and a hollow structure suitable for the better photocatalytic activity. The observed NIR photoactivity supports that the upconversion mechanism is involved in the overall photocatalytic process. Therefore, this approach provides a better alternative upconversion material for integral solar light absorption.

Transparent sunlight conversion film based on carboxymethyl cellulose and carbon dots.

PubMed

You, Yaqin; Zhang, Haoran; Liu, Yingliang; Lei, Bingfu

2016-10-20

Transparent sunlight conversion film based on carboxymethyl cellulose (CMC) and carbon dots (CDs) has been developed for the first time through dispersion of CDs in CMC aqueous solution. Due to the hydrogen bonds interaction, CMC can effectively absorb the CDs, whose surfaces are functionalized by lots of polar groups. The results from atomic force microscopy (AFM), scanning electron microscopy (SEM) confirm that the composite film possesses a homogeneous and compact structure. Besides, the CMC matrix neither competes for absorbing excitation light nor absorbs the emissions of CDs, which reserves the inherent optical properties of the individual CDs. The composite films can efficiently convert ultraviolet light to blue light. What's more, the film is transparent and possesses excellent mechanical properties, expected to apply in the field of agricultural planting for sunlight conversion. Copyright © 2016 Elsevier Ltd. All rights reserved.

Neural differentiation of transplanted neural stem cells in a rat model of striatal lacunar infarction: light and electron microscopic observations

PubMed Central

Muñetón-Gómez, Vilma C.; Doncel-Pérez, Ernesto; Fernandez, Ana P.; Serrano, Julia; Pozo-Rodrigálvarez, Andrea; Vellosillo-Huerta, Lara; Taylor, Julian S.; Cardona-Gómez, Gloria P.; Nieto-Sampedro, Manuel; Martínez-Murillo, Ricardo

2012-01-01

The increased risk and prevalence of lacunar stroke and Parkinson's disease (PD) makes the search for better experimental models an important requirement for translational research. In this study we assess ischemic damage of the nigrostriatal pathway in a model of lacunar stroke evoked by damaging the perforating arteries in the territory of the substantia nigra (SN) of the rat after stereotaxic administration of endothelin-1 (ET-1), a potent vasoconstrictor peptide. We hypothesized that transplantation of neural stem cells (NSCs) with the capacity of differentiating into diverse cell types such as neurons and glia, but with limited proliferation potential, would constitute an alternative and/or adjuvant therapy for lacunar stroke. These cells showed neuritogenic activity in vitro and a high potential for neural differentiation. Light and electron microscopy immunocytochemistry was used to characterize GFP-positive neurons derived from the transplants. 48 h after ET-1 injection, we characterized an area of selective degeneration of dopaminergic neurons within the nigrostriatal pathway characterized with tissue necrosis and glial scar formation, with subsequent behavioral signs of Parkinsonism. Light microscopy showed that grafted cells within the striatal infarction zone differentiated with a high yield into mature glial cells (GFAP-positive) and neuron types present in the normal striatum. Electron microscopy revealed that NSCs-derived neurons integrated into the host circuitry establishing synaptic contacts, mostly of the asymmetric type. Astrocytes were closely associated with normal small-sized blood vessels in the area of infarct, suggesting a possible role in the regulation of the blood brain barrier and angiogenesis. Our results encourage the use of NSCs as a cell-replacement therapy for the treatment of human vascular Parkinsonism. PMID:22876219

Ag3PO4 nanocrystals deposited on monoclinic olive-like BiVO4 with efficient photodegradation of organic dyes under visible light irradiation

NASA Astrophysics Data System (ADS)

Chen, Jingshuai; Jiang, Liang-Liang; Liu, Xing-Pei; Mao, Chang-Jie; Song, Ji-Ming; Niu, Helin; Zhang, Shengyi

2017-05-01

Olive-like BiVO4 microstructures with lengths of 600-1000 nm and widths of 300-600 nm have been synthesized via a facile and additive-free solvothermal method. Studies find that the type of solvent plays an important role in the morphology of the final products. Furthermore, Ag3PO4 nanocrystals are successfully deposited on monoclinic olive-like BiVO4 via in situ precipitation method. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), photoluminescence (PL) spectra, and UV-vis diffuse reflectance spectra (DRS). The photocatalytic activities of the catalysts are evaluated by degradation of rhodamine B (RhB) and methylene blue (MB) under visible light (≥420 nm) irradiation. The experimental results suggest that catalytic activity of the composite photocatalysts is greatly influenced by the loading level of Ag3PO4. The molar ratio of 0.8:1.0 Ag3PO4-loaded BiVO4 exhibits higher photocatalytic activity in both the decolorization of RhB and MB than that of individual BiVO4 and P25. The observed improvement in photocatalytic activity is associated with the extended absorption in the visible light region resulting from the Ag3PO4 nanoparticles, and the effective separation of photogenerated carriers at the Ag3PO4/BiVO4 interfaces through the formation of heterojunction structure. The study provides a general and effective method in the fabrication of composite with sound heterojunctions that may show a variety of applications.

Tracking the ultrafast motion of a single molecule by femtosecond orbital imaging

NASA Astrophysics Data System (ADS)

Cocker, Tyler L.; Peller, Dominik; Yu, Ping; Repp, Jascha; Huber, Rupert

2016-11-01

Watching a single molecule move on its intrinsic timescale has been one of the central goals of modern nanoscience, and calls for measurements that combine ultrafast temporal resolution with atomic spatial resolution. Steady-state experiments access the requisite spatial scales, as illustrated by direct imaging of individual molecular orbitals using scanning tunnelling microscopy or the acquisition of tip-enhanced Raman and luminescence spectra with sub-molecular resolution. But tracking the intrinsic dynamics of a single molecule directly in the time domain faces the challenge that interactions with the molecule must be confined to a femtosecond time window. For individual nanoparticles, such ultrafast temporal confinement has been demonstrated by combining scanning tunnelling microscopy with so-called lightwave electronics, which uses the oscillating carrier wave of tailored light pulses to directly manipulate electronic motion on timescales faster even than a single cycle of light. Here we build on ultrafast terahertz scanning tunnelling microscopy to access a state-selective tunnelling regime, where the peak of a terahertz electric-field waveform transiently opens an otherwise forbidden tunnelling channel through a single molecular state. It thereby removes a single electron from an individual pentacene molecule’s highest occupied molecular orbital within a time window shorter than one oscillation cycle of the terahertz wave. We exploit this effect to record approximately 100-femtosecond snapshot images of the orbital structure with sub-ångström spatial resolution, and to reveal, through pump/probe measurements, coherent molecular vibrations at terahertz frequencies directly in the time domain. We anticipate that the combination of lightwave electronics and the atomic resolution of our approach will open the door to visualizing ultrafast photochemistry and the operation of molecular electronics on the single-orbital scale.

Methods for characterizing plant fibers.

PubMed

Cruthers, Natasha; Carr, Debra; Niven, Brian; Girvan, Elizabeth; Laing, Raechel

2005-08-01

The effectiveness of different microscopy techniques for measuring the dimensions of ultimate fibers from harakeke (Phormium tenax, New Zealand flax) was investigated using a factorial experimental design. Constant variables were geographical location, location of specimens along the leaf, season (winter), individual plant, a fourth leaf from a north-facing fan, age of plant, and cultivars (two). Experimental variables were microscopy techniques and measurement axis. Measurements of width and length of harakeke ultimate fibers depended on the microscopic preparation/technique used as well as the cultivar examined. The best methods were (i) transverse sections of leaf specimens 4 microm thick, embedded in Paraplast and observed using light microscopy, and (ii) nonfixed ultimate fibers observed using scanning electron microscopy. (c) 2005 Wiley-Liss, Inc.

Correlation of two-photon in vivo imaging and FIB/SEM microscopy

PubMed Central

Blazquez-Llorca, L; Hummel, E; Zimmerman, H; Zou, C; Burgold, S; Rietdorf, J; Herms, J

2015-01-01

Advances in the understanding of brain functions are closely linked to the technical developments in microscopy. In this study, we describe a correlative microscopy technique that offers a possibility of combining two-photon in vivo imaging with focus ion beam/scanning electron microscope (FIB/SEM) techniques. Long-term two-photon in vivo imaging allows the visualization of functional interactions within the brain of a living organism over the time, and therefore, is emerging as a new tool for studying the dynamics of neurodegenerative diseases, such as Alzheimer’s disease. However, light microscopy has important limitations in revealing alterations occurring at the synaptic level and when this is required, electron microscopy is mandatory. FIB/SEM microscopy is a novel tool for three-dimensional high-resolution reconstructions, since it acquires automated serial images at ultrastructural level. Using FIB/SEM imaging, we observed, at 10 nm isotropic resolution, the same dendrites that were imaged in vivo over 9 days. Thus, we analyzed their ultrastructure and monitored the dynamics of the neuropil around them. We found that stable spines (present during the 9 days of imaging) formed typical asymmetric contacts with axons, whereas transient spines (present only during one day of imaging) did not form a synaptic contact. Our data suggest that the morphological classification that was assigned to a dendritic spine according to the in vivo images did not fit with its ultrastructural morphology. The correlative technique described herein is likely to open opportunities for unravelling the earlier unrecognized complexity of the nervous system. Lay Description Neuroscience and the understanding of brain functions are closely linked to the technical advances in microscopy. In this study we performed a correlative microscopy technique that offers the possibility to combine 2 photon in vivo imaging and FIB/SEM microscopy. Long term 2 photon in vivo imaging allows the visualization of functional interactions within the brain of a living organism over the time, and therefore, is emerging as a new tool to study the dynamics of neurodegenerative diseases, such as Alzheimer’s disease. However, light microscopy has important limitations in revealing synapses that are the connections between neurons, and for this purpose, the electron microscopy is necessary. FIB/SEM microscopy is a novel tool for three-dimensional (3D) high resolution reconstructions since it acquires automated serial images at ultrastructural level. This correlative technique will open up new horizons and opportunities for unravelling the complexity of the nervous system. PMID:25786682

Solar light-driven photocatalysis using mixed-phase bismuth ferrite (BiFeO3/Bi25FeO40) nanoparticles for remediation of dye-contaminated water: kinetics and comparison with artificial UV and visible light-mediated photocatalysis.

PubMed

Kalikeri, Shankramma; Shetty Kodialbail, Vidya

2018-05-01

Mixed-phase bismuth ferrite (BFO) nanoparticles were prepared by co-precipitation method using potassium hydroxide as the precipitant. X-ray diffractogram (XRD) of the particles showed the formation of mixed-phase BFO nanoparticles containing BiFeO 3 /Bi 25 FeO 40 phases with the crystallite size of 70 nm. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the formation of quasi-spherical particles. The BFO nanoparticles were uniform sized with narrow size range and with the average hydrodynamic diameter of 76 nm. The band gap energy of 2.2 eV showed its ability to absorb light even in the visible range. Water contaminated with Acid Yellow (AY-17) and Reactive Blue (RB-19) dye was treated by photocatalysis under UV, visible, and solar light irradiation using the BFO nanoparticles. The BFO nanoparticles showed maximum photocatalytical activity under solar light as compared to UV and visible irradiations, and photocatalysis was favored under acidic pH. Complete degradation of AY-17 dyes and around 95% degradation of RB-19 could be achieved under solar light at pH 5. The kinetics of degradation followed the Langmuir-Hinshelhood kinetic model showing that the heterogeneous photocatalysis is adsorption controlled. The findings of this work prove the synthesized BFO nanoparticles as promising photocatalysts for the treatment of dye-contaminated industrial wastewater.

Molecular Architecture of Plant Thylakoids under Physiological and Light Stress Conditions: A Study of Lipid–Light-Harvesting Complex II Model Membranes[C][W

PubMed Central

Janik, Ewa; Bednarska, Joanna; Zubik, Monika; Puzio, Michal; Luchowski, Rafal; Grudzinski, Wojciech; Mazur, Radoslaw; Garstka, Maciej; Maksymiec, Waldemar; Kulik, Andrzej; Dietler, Giovanni; Gruszecki, Wieslaw I.

2013-01-01

In this study, we analyzed multibilayer lipid-protein membranes composed of the photosynthetic light-harvesting complex II (LHCII; isolated from spinach [Spinacia oleracea]) and the plant lipids monogalcatosyldiacylglycerol and digalactosyldiacylglycerol. Two types of pigment-protein complexes were analyzed: those isolated from dark-adapted leaves (LHCII) and those from leaves preilluminated with high-intensity light (LHCII-HL). The LHCII-HL complexes were found to be partially phosphorylated and contained zeaxanthin. The results of the x-ray diffraction, infrared imaging microscopy, confocal laser scanning microscopy, and transmission electron microscopy revealed that lipid-LHCII membranes assemble into planar multibilayers, in contrast with the lipid-LHCII-HL membranes, which form less ordered structures. In both systems, the protein formed supramolecular structures. In the case of LHCII-HL, these structures spanned the multibilayer membranes and were perpendicular to the membrane plane, whereas in LHCII, the structures were lamellar and within the plane of the membranes. Lamellar aggregates of LHCII-HL have been shown, by fluorescence lifetime imaging microscopy, to be particularly active in excitation energy quenching. Both types of structures were stabilized by intermolecular hydrogen bonds. We conclude that the formation of trans-layer, rivet-like structures of LHCII is an important determinant underlying the spontaneous formation and stabilization of the thylakoid grana structures, since the lamellar aggregates are well suited to dissipate excess energy upon overexcitation. PMID:23898030

Molecular architecture of plant thylakoids under physiological and light stress conditions: a study of lipid-light-harvesting complex II model membranes.

PubMed

Janik, Ewa; Bednarska, Joanna; Zubik, Monika; Puzio, Michal; Luchowski, Rafal; Grudzinski, Wojciech; Mazur, Radoslaw; Garstka, Maciej; Maksymiec, Waldemar; Kulik, Andrzej; Dietler, Giovanni; Gruszecki, Wieslaw I

2013-06-01

In this study, we analyzed multibilayer lipid-protein membranes composed of the photosynthetic light-harvesting complex II (LHCII; isolated from spinach [Spinacia oleracea]) and the plant lipids monogalcatosyldiacylglycerol and digalactosyldiacylglycerol. Two types of pigment-protein complexes were analyzed: those isolated from dark-adapted leaves (LHCII) and those from leaves preilluminated with high-intensity light (LHCII-HL). The LHCII-HL complexes were found to be partially phosphorylated and contained zeaxanthin. The results of the x-ray diffraction, infrared imaging microscopy, confocal laser scanning microscopy, and transmission electron microscopy revealed that lipid-LHCII membranes assemble into planar multibilayers, in contrast with the lipid-LHCII-HL membranes, which form less ordered structures. In both systems, the protein formed supramolecular structures. In the case of LHCII-HL, these structures spanned the multibilayer membranes and were perpendicular to the membrane plane, whereas in LHCII, the structures were lamellar and within the plane of the membranes. Lamellar aggregates of LHCII-HL have been shown, by fluorescence lifetime imaging microscopy, to be particularly active in excitation energy quenching. Both types of structures were stabilized by intermolecular hydrogen bonds. We conclude that the formation of trans-layer, rivet-like structures of LHCII is an important determinant underlying the spontaneous formation and stabilization of the thylakoid grana structures, since the lamellar aggregates are well suited to dissipate excess energy upon overexcitation.

Super-resolution photoacoustic microscopy using a localized near-field of a plasmonic nanoaperture: a three-dimensional simulation study

NASA Astrophysics Data System (ADS)

Park, Byullee; Lee, Hongki; Upputuri, Paul Kumar; Pramanik, Manojit; Kim, Donghyun; Kim, Chulhong

2018-02-01

Super-resolution microscopy has been increasingly important to delineate nanoscale biological structures or nanoparticles. With these increasing demands, several imaging modalities, including super-resolution fluorescence microscope (SRFM) and electron microscope (EM), have been developed and commercialized. These modalities achieve nanoscale resolution, however, SRFM cannot image without fluorescence, and sample preparation of EM is not suitable for biological specimens. To overcome those disadvantages, we have numerically studied the possibility of superresolution photoacoustic microscopy (SR-PAM) based on near-field localization of light. Photoacoustic (PA) signal is generally acquired based on optical absorption contrast; thus it requires no agents or pre-processing for the samples. The lateral resolution of the conventional photoacoustic microscopy is limited to 200 nm by diffraction limit, therefore reducing the lateral resolution is a major research impetus. Our approach to breaking resolution limit is to use laser pulses of extremely small spot size as a light source. In this research, we simulated the PA signal by constructing the three dimensional SR-PAM system environment using the k-Wave toolbox. As the light source, we simulated ultrashort light pulses using geometrical nanoaperture with near-field localization of surface plasmons. Through the PA simulation, we have successfully distinguish cuboids spaced 3 nm apart. In the near future, we will develop the SR-PAM and it will contribute to biomedical and material sciences.

Filling the gap: adding super-resolution to array tomography for correlated ultrastructural and molecular identification of electrical synapses at the C. elegans connectome.

PubMed

Markert, Sebastian Matthias; Britz, Sebastian; Proppert, Sven; Lang, Marietta; Witvliet, Daniel; Mulcahy, Ben; Sauer, Markus; Zhen, Mei; Bessereau, Jean-Louis; Stigloher, Christian

2016-10-01

Correlating molecular labeling at the ultrastructural level with high confidence remains challenging. Array tomography (AT) allows for a combination of fluorescence and electron microscopy (EM) to visualize subcellular protein localization on serial EM sections. Here, we describe an application for AT that combines near-native tissue preservation via high-pressure freezing and freeze substitution with super-resolution light microscopy and high-resolution scanning electron microscopy (SEM) analysis on the same section. We established protocols that combine SEM with structured illumination microscopy (SIM) and direct stochastic optical reconstruction microscopy (dSTORM). We devised a method for easy, precise, and unbiased correlation of EM images and super-resolution imaging data using endogenous cellular landmarks and freely available image processing software. We demonstrate that these methods allow us to identify and label gap junctions in Caenorhabditis elegans with precision and confidence, and imaging of even smaller structures is feasible. With the emergence of connectomics, these methods will allow us to fill in the gap-acquiring the correlated ultrastructural and molecular identity of electrical synapses.

Simple technique for high-throughput marking of distinguishable micro-areas for microscopy.

PubMed

Henrichs, Leonard F; Chen, L I; Bell, Andrew J

2016-04-01

Today's (nano)-functional materials, usually exhibiting complex physical properties require local investigation with different microscopy techniques covering different physical aspects such as dipolar and magnetic structure. However, often these must be employed on the very same sample position to be able to truly correlate those different information and corresponding properties. This can be very challenging if not impossible especially when samples lack prominent features for orientation. Here, we present a simple but effective method to mark hundreds of approximately 15×15 μm sample areas at one time by using a commercial transmission electron microscopy grid as shadow mask in combination with thin-film deposition. Areas can be easily distinguished when using a reference or finder grid structure as shadow mask. We show that the method is suitable to combine many techniques such as light microscopy, scanning probe microscopy and scanning electron microscopy. Furthermore, we find that best results are achieved when depositing aluminium on a flat sample surface using electron-beam evaporation which ensures good line-of-sight deposition. This inexpensive high-throughput method has several advantageous over other marking techniques such as focused ion-beam processing especially when batch processing or marking of many areas is required. Nevertheless, the technique could be particularly valuable, when used in junction with, for example focused ion-beam sectioning to obtain a thin lamellar of a particular pre-selected area. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Chemical analyses of fossil bone.

PubMed

Zheng, Wenxia; Schweitzer, Mary Higby

2012-01-01

The preservation of microstructures consistent with soft tissues, cells, and other biological components in demineralized fragments of dinosaur bone tens of millions of years old was unexpected, and counter to current hypotheses of tissue, cellular, and molecular degradation. Although the morphological similarity of these tissues to extant counterparts was unmistakable, after at least 80 million years exposed to geochemical influences, morphological similarity is insufficient to support an endogenous source. To test this hypothesis, and to characterize these materials at a molecular level, we applied multiple independent chemical, molecular, and microscopic analyses to identify the presence of original components produced by the extinct organisms. Microscopic techniques included field emission scanning electron microscopy, analytical transmission electron microscopy, transmitted light microscopy (LM), and fluorescence microscopy (FM). The chemical and molecular techniques include enzyme-linked immunosorbant assay, sodium dodecyl sulfate polyacrylamide gel electrophoresis, western blot (immunoblot), and attenuated total reflectance infrared spectroscopy. In situ analyses performed directly on tissues included immunohistochemistry and time-of-flight secondary ion mass spectrometry. The details of sample preparation and methodology are described in detail herein.

Confocal laser scanning microscopic photoconversion: a new method to stabilize fluorescently labeled cellular elements for electron microscopic analysis.

PubMed

Colello, Raymond J; Tozer, Jordan; Henderson, Scott C

2012-01-01

Photoconversion, the method by which a fluorescent dye is transformed into a stable, osmiophilic product that can be visualized by electron microscopy, is the most widely used method to enable the ultrastructural analysis of fluorescently labeled cellular structures. Nevertheless, the conventional method of photoconversion using widefield fluorescence microscopy requires long reaction times and results in low-resolution cell targeting. Accordingly, we have developed a photoconversion method that ameliorates these limitations by adapting confocal laser scanning microscopy to the procedure. We have found that this method greatly reduces photoconversion times, as compared to conventional wide field microscopy. Moreover, region-of-interest scanning capabilities of a confocal microscope facilitate the targeting of the photoconversion process to individual cellular or subcellular elements within a fluorescent field. This reduces the area of the cell exposed to light energy, thereby reducing the ultrastructural damage common to this process when widefield microscopes are employed. © 2012 by John Wiley & Sons, Inc.

Direct measurement of the electric-field distribution in a light-emitting electrochemical cell

NASA Astrophysics Data System (ADS)

Slinker, Jason D.; Defranco, John A.; Jaquith, Michael J.; Silveira, William R.; Zhong, Yu-Wu; Moran-Mirabal, Jose M.; Craighead, Harold G.; Abruña, Héctor D.; Marohn, John A.; Malliaras, George G.

2007-11-01

The interplay between ionic and electronic charge carriers in mixed conductors offers rich physics and unique device potential. In light-emitting electrochemical cells (LEECs), for example, the redistribution of ions assists the injection of electronic carriers and leads to efficient light emission. The mechanism of operation of LEECs has been controversial, as there is no consensus regarding the distribution of electric field in these devices. Here, we probe the operation of LEECs using electric force microscopy on planar devices. We show that obtaining the appropriate boundary conditions is essential for capturing the underlying device physics. A patterning scheme that avoids overlap between the mixed-conductor layer and the metal electrodes enabled the accurate in situ measurement of the electric-field distribution. The results show that accumulation and depletion of mobile ions near the electrodes create high interfacial electric fields that enhance the injection of electronic carriers.

Monitoring adsorption of gold nanoparticles on gold nanodisk array using dark-field hyperspectral microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zhao, Fusheng; Zenasni, Oussama; Li, Jingting; Shih, Wei-Chuan

2017-02-01

Localized surface plasmon resonance (LSPR) arises from the interaction of light with noble metal nanoparticles, which induces a collective oscillation in the free electrons. The size and shape of the metallic nanostructure significantly impact LSPR frequency and strength. Nanoplasmonic sensor has become a recent research focus due to its significant signal enhancement and robust signal transduction measured by extinction spectroscopy, fluorescence, Raman scattering, and absorption spectroscopy. Dark-field microscopy, in contrast, reports the scattered photons after light-matter interactions. In this case, the nanoparticles can be understood as dipole radiators whose free electrons oscillate in concert. Coupled with spectroscopy, this platform allows the collection of plasmonically scattered spectra from gold nanoparticles. Plasmonic coupling between electron-beam lithography patterned gold nanodisks (AuND) and colloidal gold nanoparticles (AuNP) can change the plasmonic resonance of the original entities, and can be effectively studied by dark-field hyperspectral microscopy. Typically, a pronounced redshift can be observed when plasmonic coupling occurs. When these nano-entities are functionalized with interactive surface moieties, biochemistry and molecular processes can be studied. In this paper, we will present the capability of assessing the process of immobilizing streptavidin-functionalized AuNPs on an array of biotin-terminated AuNDs. By monitoring changes in the LSPR band of AuNDs, we are able to evaluate similar processes in other molecular systems. In addition, plasmon coupling induced scattering intensity variations can be measured by an electron-multiplied charge-coupled device camera for rapid in situ monitoring. This method can potentially be useful in studying dynamic biophysical and biochemical processes in situ.

New histopathologic and ultrastructural findings in Reis-Bücklers corneal dystrophy caused by the Arg124Leu mutation of TGFBI gene.

PubMed

Qiu, Wen-Ya; Zheng, Li-Bin; Pan, Fei; Wang, Bei-Bei; Yao, Yu-Feng

2016-09-02

Reis-Bücklers corneal dystrophy (RBCD) was consistently reported as a corneal dystrophy only affected Bowman's layer and superficial corneal stroma, and superficial keratectomy was a recommendation surgery for treatment in literatures. The study reported new histopathological and ultrastructural findings in RBCD caused by the Arg124Leu mutation of transforming growth factor induced (TGFBI) gene in a four-generation Chinese pedigree. Subjects including eight patients and seven unaffected family members received slit-lamp biomicroscopy and photography. DNA was obtained from all subjects, and exons 4 and 11 to 14 of TGFBI gene were analyzed by polymerase chain reaction and the products were sequenced. Anterior segment optical coherence tomography (AS OCT) and in vivo confocal microscopy were conducted for ten eyes of five patients. Based on the results of AS OCT and in vivo confocal microscopy, deep anterior lamellar keratoplasty (DLKP) using cryopreserved donor cornea was applied for four eyes of four patients. Four lamellar dystrophic corneal buttons were studied by light and transmission electron microscopy, and TGFBI immunohistochemistry. Eight patients had typical clinical manifestations of RBCD presenting recurrent painful corneal erosion starting in their early first decades, along with age-dependent progressive geographic corneal opacities. TGFBI sequencing revealed a heterozygous mutation, Arg124Leu in all eight patients. Anterior segment optical coherence tomography and in vivo confocal microscopy showed the dystrophic deposits involved not only in subepithelial and superficial stroma, but also in mid- or posterior stroma in four examined advanced eyes. Light microscopy showed Bowman's layer was absent, replaced by abnormal deposits stain bright red with Masson's trichrome. In superficial cornea, the deposits stacked and produced three to five continuous bands parallel to the corneal collagen lamellae. In mid- to posterior stroma, numerous granular or dot- like aggregates were heavily scattered, and most of them presented around the nuclei of stromal keratocytes. Transmission electron microscopy revealed the multiple electron-dense rod-shaped deposits aggregated and formed a characteristic pattern of three to five continuous bands in superficial cornea, which were similar to those seen under light microscopy. In mid- to posterior stroma, clusters of rod-shaped bodies were scattered extracellular or intracellular of the stromal keratocytes between the stromal lamellae suggesting the close relationship between mutated proteins and keratocyte. The study offer evidences indicating DLKP is a viable treatment option for advanced RBCD to avoid recurrence, and the mutated TGFBIp in dystrophic corneas are of keratocytes origin.

Electroluminescence and other diagnostic techniques for the study of hot-electron effects in compound semiconductor devices

NASA Astrophysics Data System (ADS)

Zanoni, Enrico; Meneghesso, Gaudenzio; Menozzi, Roberto

2000-03-01

Hot electron in III-V FETs can be indirectly monitored by measuring the current coming out from the gate when the device is biased at high electric fields. This negative current is due to the collection of holes generated by impact ionization in the gate-to drain region. Electroluminescence represents a powerful tool in order to characterize not only hot electrons but also material properties. By using spatially resolved emission microscopy it is possible to show that the light due to cold electron/hole recombination is emitted between the gate and the source (low electric field region), while the contribution due to hot electrons is emitted between the gate and the drain (high electric field region). Deep-traps created in the device by hot carriers can be analysed by means of drain current deep level transient spectroscopy and by transconductance frequency dispersion. Cathodoluminescence, optical beam induced current, X-ray spectroscopy, electron energy loss spectroscopy in combination with a transmission electron microscopy are powerful tools in order to identify and localize surface modification following hot-electron stress tests.

Ultrastructural changes in sweet orange with symptoms of huanglongbing

USDA-ARS?s Scientific Manuscript database

Citrus greening (Huanglongbing [HLB]) is one of the most destructive citrus diseases worldwide. To better understand the ultrastructural changes of sweet orange seedlings in response to infection, anatomical analyses of HLB-infected sweet orange were carried out by light and electron microscopy. A...

Notes on Citrullus spp.: Pollen morphology, C values, and interspecific hybridization

USDA-ARS?s Scientific Manuscript database

Scanning electron and light microscopy were utilized to examine pollen of the currently recognized species (and forms) within the genus Citrullus (Cucurbitaceae). Materials examined included: C. lanatus (Thunb.) Matsum. & Nakai including the citron (C. amarus Schrad.) and egusi (C. mucosospermus (Fu...

Protein-accumulating cells and dilated cisternae of the endoplasmic reticulum in three glucosinolate-containing genera: Armoracia, Capparis, Drypetes.

PubMed

Jørgensen, L B; Behnke, H D; Mabry, T J

1977-01-01

Three glucosinolate-containing species, Armoracia rusticana Gaertner, Meyer et Scherbius (Brassicaceae), Capparis cynophallophora L. (Capparaceae) and Drypetes roxburghii (Wall.) Hurusawa (Euphorbiaceae), are shown by both light and electron microscopy to contain protein-accumulating cells (PAC). The PAC of Armoracia and Copparis (former "myrosin cells") occur as idioblasts. The PAC of Drypetes are usual members among axial phloem parenchyma cells rather than idioblasts. In Drypetes the vacuoles of the PAC are shown ultrastructurally to contain finely fibrillar material and to originate from local dilatations of the endoplasmic reticulum. The vacuoles in PAC of Armoracia and Capparis seem to originate in the same way; but ultrastructurally, their content is finely granular. In addition, Armoracia and Capparis are shown by both light and electron microscopy to contain dilated cisternae (DC) of the endoplasmic reticulum in normal parenchyma cells, in accord with previous findings for several species within Brassicaceae. The relationship of PAC and DC to glucosinolates and the enzyme myrosinase is discussed.

The preparation and photocatalytic activity of CdS/(Cal-Ta2O5-SiO2) composite photocatalyst under visible light

NASA Astrophysics Data System (ADS)

Li, Juxia

2018-02-01

CdS/(Cal-Ta2O5-SiO2) composite photocatalyst has been successfully fabricated via wet chemistry method. Ta2O5-SiO2 with multi-step Ta2O5 deposition on SiO2 has more Ta2O5 on SiO2 to ensure the active sites. Trough multi-step calcination, Ta2O5 can load on SiO2 with uniform and stable, which make it have high photocatalytic activity. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance ultraviolet-visible spectroscopy (UV-vis) and photoluminescence spectroscopy (PL). Without any co-catalysts, the as-prepared CdS/(Cal-Ta2O5-SiO2) exhibited remarkable photocatalytic activity and recyclability both in the degradation of rhodamine B and in the hydrogen production from water splitting under visible light.

Studies on hydrothermal synthesis of photolumniscent rare earth (Eu3+ & Tb3+) doped NG@FeMoO4 for enhanced visible light photodegradation of methylene blue dye

NASA Astrophysics Data System (ADS)

Singh, R.; Kumar, M.; Khajuria, H.; Sharma, S.; Sheikh, H. Nawaz

2018-02-01

FeMoO4 nanorods and their rare earth (Eu3+ and Tb3+) doped composites with nitrogen doped graphene (NG) were synthesized by facile hydrothermal method in aqueous medium. X-ray diffraction (XRD) analysis of the as-synthesized samples was done to study the phase purity and crystalline nature. FTIR and Raman Spectroscopy have been studied for investigating the bonding in nanostructures. The surface morphology of the samples was investigated with field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The photolumniscent nature of the samples was investigated by the using the fluorescence spectrophotometer. The photocatalytic degradation efficiency of the prepared pure FeMoO4 and its rare earth doped composites with nitrogen doped graphene was evaluated as function of visible light irradiation versus concentration of methylene blue (MB dye). The prepared nanocomposites show enhanced photocatalytic efficiency as compared to the bare FeMoO4 nanorods.

Extrusion of amyloid fibrils to the extracellular space in experimental mesangial AL-amyloidosis: transmission and scanning electron microscopy studies and correlation with renal biopsy observations.

PubMed

Teng, Jiamin; Turbat-Herrera, Elba A; Herrera, Guillermo A

2014-04-01

In vitro studies have provided much information regarding the process of glomerular AL-amyloidogenesis. Research efforts have been successful in deciphering how glomerulopathic light chains interact with mesangial cells. The sequential steps involved in the genesis of amyloid fibrils include interactions with surface caveolae in mesangial cells and internalization of the monoclonal light chains through a clathrin-mediated process followed by trafficking in the mesangial cells to the mature lysosomal compartment where fibrils are formed. This manuscript focuses on how mesangial cells, once amyloid has been formed, deliver the fibrils to the extracellular matrix. The delivery of amyloid fibrils to the outside of the cells is carried out by lysosomes, which abut the mesangial cell membranes and extrude their contents into the extracellular space. This final step responsible for the fibrils to be present predominantly in the extracellular space is well demonstrated with scanning electron microscopy.

Green chemistry approach for the synthesis of ZnO-carbon dots nanocomposites with good photocatalytic properties under visible light.

PubMed

Bozetine, Hakima; Wang, Qi; Barras, Alexandre; Li, Musen; Hadjersi, Toufik; Szunerits, Sabine; Boukherroub, Rabah

2016-03-01

We report on a simple and one-pot synthetic method to produce ZnO/carbon quantum dots (ZnO/CQDs) nanocomposites. The morphological features and chemical composition of the nanocomposites were characterized using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analyses (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optical properties of the nanocomposites were examined using UV-visible (UV-vis) spectrophotometry. The photocatalytic activity of the ZnO/CQDs was evaluated for the degradation of a model organic pollutant, rhodamine B, under visible light irradiation at room temperature. The highly efficient photodegradation capability of the nanocomposite was demonstrated by comparison with ZnO particles, prepared using identical experimental conditions. Overall, the present approach adheres to green chemistry principles and the nanocomposite holds promise for the development of remarkably efficient catalytic systems. Copyright © 2015 Elsevier Inc. All rights reserved.

Light and scanning electron microscopy of the ecdysis of Haemonchus contortus infective larvae.

PubMed

Gamble, H R; Lichtenfels, J R; Purcell, J P

1989-04-01

During the second ecdysis of ruminant trichostrongyles, a region of the second molt cuticle is digested by a 44-kDa Zn-metalloprotease. We have examined this digestion process by light and scanning electron microscopy (SEM). The substrate region of the cuticle appeared, during the ecdysis process, as an indented ring at the 20th cuticular annulus coincident with the anterior terminus of the lateral alae. Continued digestion of the cuticle resulted in holes in the ring region that expanded until they became continuous and separation occurred between the anterior and posterior portions of the cuticle. Mechanical movements of the L3 forced aside the cuticle cap that generally remained attached on one side to the posterior portion as the larva escaped from the sheath. The site of secretion of the 44-kDa ecdysing enzyme causing cuticle digestion was not clear from morphological observations; however, existing evidence strongly points to the release of enzyme from the esophageal (pharyngeal) glands through the mouth.

Green Synthesis and Characterization of SmVO4 Nanoparticles in the Presence of Carbohydrates As Capping Agents with Investigation of Visible-Light Photocatalytic Properties

NASA Astrophysics Data System (ADS)

Eghbali-Arani, Mohammad; Sobhani-Nasab, Ali; Rahimi-Nasrabadi, Mehdi; Pourmasoud, Saeid

2018-03-01

SmVO4 nanoparticles were synthesized through a fast and simple procedure (green method). The effects of three parameters including temperature, type of capping agent, and concentration on the size and morphology behavior of SmVO4 nanoparticles were explored. The analysis of SmVO4 nanoparticles was performed through some techniques including, Fourier transform infrared spectroscopy, x-ray diffraction, energy dispersive x-ray microanalysis, scanning electron microscopy, transmission electron microscopy, thermogravimetry, differential thermal analysis, ultraviolet-visible spectroscopy, and vibrating sample magnetometers. The study of photocatalytic behaviour of the SmVO4 nanoparticles in various conditions has been carried out. The impacts of different factors such as dosage, grain size, and kind of pollutant (methylene blue = MB and methyl orange = MO) on the photocatalytic property of SmVO4 nanoparticles were assessed. The photocatalytic activities of SmVO4 catalysts were studied for the degradation of dye under visible light (λ > 400 nm).

Further description of Aspidodera raillieti (Nematoda: Aspidoderidae) from Didelphis marsupialis (Mammalia: Didelphidae) by light and scanning electron microscopy.

PubMed

Chagas-Moutinho, V A; Oliveira-Menezes, A; Cárdenas, M Q; Lanfredi, R M

2007-10-01

Nematodes of the family Aspidoderidae (Nematoda: Heterakoidea) Freitas 1956 are widely distributed from Americas. The species of the genus Aspidodera Railliet and Henry 1912 are parasites of mammals of the orders Edentata, Marsupialia, and Rodentia. In the present work, Aspidodera raillieti (L. Travassos, Mem Inst Oswaldo Cruz 5(3):271-318, 1913), collected from the large intestine of Didelphis marsupialis (Mammalia: Didelphidae) from Valle del Cauca, Colombia, is redescribed. The association of light and scanning electron microscopy (SEM) allowed a detailed analysis of the morphology and ultrastructure of this nematode. Some taxonomic features, such as cephalic region, topography of the cuticle, sucker, spicules, posterior end of males, localization of vulva, the anus, and posterior end of females were observed. Important structures such as amphid, details of cephalic region, phasmid, and number and localization of caudal papillae are documented by SEM, for the first time adding characters to identify this species. Colombia is a new geographical record for A. raillieti.

EFFECTS OF CHEMICAL PROCESSING AND OXIDE ETHYLENE STERILIZATION ON CORTICAL AND CANCELLOUS RAT BONE: A LIGHT AND ELECTRON SCANNING MICROSCOPY STUDY

PubMed Central

Castiglia, Marcello Teixeira; da Silva, Juliano Voltarelli F.; Frezarim Thomazini, José Armendir; Volpon, José Batista

2015-01-01

To evaluate, under microscopic examination, the structural changes displayed by the trabecular and cortical bones after being processed chemically and sterilized by ethylene oxide. Methods: Samples of cancellous and cortical bones obtained from young female albinus rats (Wistar) were assigned to four groups according to the type of treatment: Group I- drying; Group II- drying and ethylene oxide sterilization; III- chemical treatment; IV- chemical treatment and ethylene oxide sterilization. Half of this material was analyzed under ordinary light microscope and the other half using scanning electron microscopy. Results: In all the samples, regardless the group, there was good preservation of the general morphology. For samples submitted to the chemical processing there was better preservation of the cellular content, whereas there was amalgamation of the fibres when ethylene oxide was used. Conclusion: Treatment with ethylene oxide caused amalgamation of the fibers, possibly because of heating and the chemical treatment contributed to a better cellular preservation of the osseous structure. PMID:26998450

Reevaluation of Physaloptera bispiculata (Nematoda: Spiruroidaea) by light and scanning electron microscopy.

PubMed

Mafra, A C; Lanfredi, R M

1998-06-01

This study was undertaken to clarify several aspects of morphological and taxonomic characters of Physaloptera bispiculata Vaz and Pereira, 1935, a parasite of the water rat, Nectomys squamipes. The cephalic structures (including lips, papillae, teeth, amphids, and porous areas) and details of the posterior end of male and female adult worms were examined by scanning electron microscopy, leading to the addition of new taxonomic characters for this species. We consider P. bispiculata a valid species, based on a comparative analysis of the specific characters for P. bispiculata and P. getula Seurat, 1917, including the morphology and morphometry of body structures as well as number and disposition of caudal papillae of the males.

Serial block face-scanning electron microscopy: a tool for studying embryonic development at the cell-matrix interface.

PubMed

Starborg, Tobias; Kadler, Karl E

2015-03-01

Studies of gene regulation, signaling pathways, and stem cell biology are contributing greatly to our understanding of early embryonic vertebrate development. However, much less is known about the events during the latter half of embryonic development, when tissues comprising mostly extracellular matrix (ECM) are formed. The matrix extends far beyond the boundaries of individual cells and is refractory to study by conventional biochemical and molecular techniques; thus major gaps exist in our knowledge of the formation and three-dimensional (3D) organization of the dense tissues that form the bulk of adult vertebrates. Serial block face-scanning electron microscopy (SBF-SEM) has the ability to image volumes of tissue containing numerous cells at a resolution sufficient to study the organization of the ECM. Furthermore, whereas light microscopy was once relatively straightforward and electron microscopy was performed in specialist laboratories, the tables are turned; SBF-SEM is relatively straightforward and is becoming routine in high-end resolution studies of embryonic structures in vivo. In this review, we discuss the emergence of SBF-SEM as a tool for studying embryonic vertebrate development. © 2015 Wiley Periodicals, Inc.

Exopolysaccharide microchannels direct bacterial motility and organize multicellular behavior

DOE PAGES

Berleman, James E.; Zemla, Marcin; Remis, Jonathan P.; ...

2016-05-06

The myxobacteria are a family of soil bacteria that form biofilms of complex architecture, aligned multilayered swarms or fruiting body structures that are simple or branched aggregates containing myxospores. Here, we examined the structural role of matrix exopolysaccharide (EPS) in the organization of these surface-dwelling bacterial cells. Using time-lapse light and fluorescence microscopy, as well as transmission electron microscopy and focused ion beam/scanning electron microscopy (FIB/SEM) electron microscopy, we found that Myxococcus xanthus cell organization in biofilms is dependent on the formation of EPS microchannels. Cells are highly organized within the three-dimensional structure of EPS microchannels that are required formore » cell alignment and advancement on surfaces. Mutants lacking EPS showed a lack of cell orientation and poor colony migration. Purified, cell-free EPS retains a channel-like structure, and can complement EPS - mutant motility defects. In addition, EPS provides the cooperative structure for fruiting body formation in both the simple mounds of M. xanthus and the complex, tree-like structures of Chondromyces crocatus. We furthermore investigated the possibility that EPS impacts community structure as a shared resource facilitating cooperative migration among closely related isolates of M. xanthus.« less

Age-related adaptive responses of mitochondria of the retinal pigment epithelium to the everyday blue LED lighting.

PubMed

Serezhnikova, N B; Pogodina, L S; Lipina, T V; Trofimova, N N; Gurieva, T S; Zak, P P

2017-07-01

The effect of everyday blue light (λ = 440-460 nm) on mitochondria of the retinal pigment epithelium of different age groups of Japanese quail was studied using electron microscopy, morphometric methods, and biochemical analysis. We have found a significant increase in the number of mitochondria, including those modified, mainly in young birds. In addition, cell metabolic activity increased in response to blue lighting. These changes are assumed to reflect an adaptive response of mitochondria aimed at neutralizing the phototoxic effect of blue light caused by accumulation of lipofuscin granules.

Light production in the luminous fishes Photoblepharon and Anomalops from the Banda Islands.

PubMed

Haneda, Y; Tsuji, F I

1971-07-09

The unresolved mechanism of light production in Photoblepharon and Anomalops has been reinvestigated in fresh and preserved material. Based on biochemical evidence obtained with emulsions and cell-free extracts of the organs, especially the stimulation of light with reduced flavin mononucleotide, and on electron microscopy of organ sections showing the presence of numerous bacteria, we conclude that the light is produced by symbiotic luminous bacteria. Because of the continuing failure to cultivate the luminous bacteria and because of their morphology, we suggest that the bacteria are of a primitive type called bacteroids.

Imaging mammalian cells with soft x rays: The importance of specimen preparation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, J.T.; Meyer-Ilse, W.

1997-04-01

Studies of mammalian cell structure and spatial organization are a very prominent part of modern cell biology. The interest in them as well as their size make them very accommodating subject specimens for imaging with soft x-rays using the XM-1 transmission microscope built and operated by The Center for X-ray Optics on Beam Line 6.1 at the Advanced Light Source. The purpose of these experiments was to determine if the fixative protocols normally used in electron or visible light microscopy were adequate to allow imaging cells, either fibroblasts or neurons, with minimal visible radiation damage due to imaging with softmore » x-rays at 2.4 nm. Two cell types were selected. Fibroblasts are easily cultured but fragile cells which are commonly used as models for the detailed study of cell physiology. Neurons are complex and sensitive cells which are difficult to prepare and to culture for study in isolation from their connections with surrounding cells. These cell types pose problems in their preparation for any microscopy. To improve the contrast and to prevent postmortem alteration of the chemistry and hence the structure of cells extracted from culture or from living organisms, fixation and staining techniques are employed in electron and visible light microscopy. It has been accepted by biologists for years that these treatments create artifacts and false structure. The authors have begun to develop protocols for specimens of each of these two cell types for soft x-ray microscopy which will preserve them in as near normal state as possible using minimal fixation, and make it possible to image them in either a hydrated or dried state free of secondary addition of stains or other labels.« less

Morphology of the Vestibular Utricule in Toadfish, Opsanus Tau

NASA Technical Reports Server (NTRS)

Bass, L.; Smith, J.; Twombly, A.; Boyle, Richard; Varelas, Ehsanian J.; Johanson, C.

2003-01-01

The uticle is an otolith organ in the vertebrate inner ear that provides gravitoinertial acceleration information into the vestibular reflex pathways. The aim of the present study was to provide an anatomical description of this structure in the adult oyster toadfish, and establish a morphological basis for interpretation of subsequent functional studies. Light, scanning electron and transmission electron microscopy were applied to visualize the sensory epithelium and its neural innervation. Electrophysiological techniques were used to identify utricular afferents by their response to translation stimuli. Similar to nerve afferents supplying the semicircular canals and lagena, utricular afferents commonly exhibit a short-latency increase of firing rate in response to electrical activation of the central efferent pathway. Afferents were labeled with biocytin either intraaxonally or with extracellular bulk deposits. Light microscope images of serial thick sections were used to make three-dimensional reconstructions of individual labeled afferents to identify the dendritic morphology with respect to epithelial location. Scanning electron microscopy was used to visualize the surface of the otolith mass facing the otolith membrane, and the hair cell polarization patterns of strioler and extrastriolar regions. Transmission electron micrographs of serial thin sections were compiled to create a three-dimensional reconstruction of the labeled afferent over a segment of its dendritic field and to examine the hair cell-afferent synaptic contacts.

Deep data mining in a real space: Separation of intertwined electronic responses in a lightly doped BaFe 2As 2

DOE PAGES

Ziatdinov, Maxim; Maksov, Artem; Li, Li; ...

2016-10-25

Electronic interactions present in material compositions close to the superconducting dome play a key role in the manifestation of high-T c superconductivity. In many correlated electron systems, however, the parent or underdoped states exhibit strongly inhomogeneous electronic landscape at the nanoscale that may be associated with competing, coexisting, or intertwined chemical disorder, strain, magnetic, and structural order parameters. Here we demonstrate an approach based on a combination of scanning tunneling microscopy/spectroscopy and advanced statistical learning for an automatic separation and extraction of statistically significant electronic behaviors in the spin density wave regime of a lightly (~1%) gold-doped BaFe 2As 2.more » Lastly, we show that the decomposed STS spectral features have a direct relevance to fundamental physical properties of the system, such as SDW-induced gap, pseudogap-like state, and impurity resonance states.« less

Deep data mining in a real space: Separation of intertwined electronic responses in a lightly doped BaFe 2As 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ziatdinov, Maxim; Maksov, Artem; Li, Li

Electronic interactions present in material compositions close to the superconducting dome play a key role in the manifestation of high-T c superconductivity. In many correlated electron systems, however, the parent or underdoped states exhibit strongly inhomogeneous electronic landscape at the nanoscale that may be associated with competing, coexisting, or intertwined chemical disorder, strain, magnetic, and structural order parameters. Here we demonstrate an approach based on a combination of scanning tunneling microscopy/spectroscopy and advanced statistical learning for an automatic separation and extraction of statistically significant electronic behaviors in the spin density wave regime of a lightly (~1%) gold-doped BaFe 2As 2.more » Lastly, we show that the decomposed STS spectral features have a direct relevance to fundamental physical properties of the system, such as SDW-induced gap, pseudogap-like state, and impurity resonance states.« less

One-step growth of nanosheet-assembled BiOCl/BiOBr microspheres for highly efficient visible photocatalytic performance

NASA Astrophysics Data System (ADS)

Zhang, Jinfeng; Lv, Jiali; Dai, Kai; Liang, Changhao; Liu, Qi

2018-02-01

In this work, we have developed a simple synthetic approach of nanosheet-assembled BiOCl/BiOBr microspheres by an ethylene glycol (EG)-assisted hydrothermal method. The crystalline form, morphology, chemical composition, optical performance and surface area of BiOCl/BiOBr microspheres were identified using X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution TEM (HRTEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy spectra (EDX), UV-vis diffuse reflectance spectroscopy (DRS) analysis, high resolution X-ray photoelectron spectra (XPS) and N2 adsorption-desorption isotherms. BiOCl/BiOBr microspheres were nanosheet-assembled particles, which possessed visible light absorption under LED light irridation. Additionally, the methylene blue (MB) photodegradation performance of different BiOCl/BiOBr microspheres irradiated under 410 nm LED light arrays were investigated, the results exhibited that as-prepared BiOCl/BiOBr products showed higher catalytic effiency than pure BiOCl or BiOBr. By optimizing the composition ration of the BiOCl and BiOBr, up to 93% degradation rate can be obtained in the 40%BiOCl/BiOBr microspheres. Finally, the photocatalytic mechanism of BiOCl/BiOBr microspheres had been proposed.

Effect of Annealing Time of YAG:Ce3+ Phosphor on White Light Chromaticity Values

NASA Astrophysics Data System (ADS)

Abd, Husnen R.; Hassan, Z.; Ahmed, Naser M.; Almessiere, Munirah Abdullah; Omar, A. F.; Alsultany, Forat H.; Sabah, Fayroz A.; Osman, Ummu Shuhada

2018-02-01

Yttrium and aluminium nitrate phosphors doped with cerium nitrate and mixed with urea (fuel) are prepared by using microwave-induced combustion synthesis according to the formula Y(3-0.06)Al5O12:0.06Ce3+ (YAG:Ce3+) to produce white light emitting diodes by conversion from blue indium gallium nitride-light emitting diode chips. The sintering time with fixed temperature (1050°C) for phosphor powder was optimized and found to be 5 h. The crystallinity, structure, chemical composition, luminescent properties with varying currents densities and chromaticity were characterized by x-ray diffraction, field emission-scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, photoluminescence emission, electroluminescence and standard CIE 1931 chromaticity diagram, respectively. The energy levels of Ce3+ in YAG were discussed based on its absorption and excitation spectra. The results show that the obtained YAG:Ce3+ phosphor sintered for 5 h has good crystallinity with pure phase, low agglomerate with spherical shaped particles and strong yellow emission, offering cool-white LED with tuneable correlated color temperature and a good color rendering index compared to those prepared by sintering for 2 h and as-prepared phosphor powders.

Facile Synthesis of g-C3N4 Nanosheets/ZnO Nanocomposites with Enhanced Photocatalytic Activity in Reduction of Aqueous Chromium(VI) under Visible Light

PubMed Central

Yuan, Xiaoya; Zhou, Chao; Jing, Qiuye; Tang, Qi; Mu, Yuanhua; Du, An-ke

2016-01-01

Graphitic-C3N4 nanosheets (CN)/ZnO photocatalysts (CN/ZnO) with different CN loadings were successfully prepared via a simple precipitation-calcination in the presence of exfoliated C3N4 nanosheets. Their morphology and structure were thoroughly characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS) and photoluminescence spectra (PL). The results showed that hexagonal wurzite-phase ZnO nanoparticles were randomly distributed onto the CN nanosheets with a well-bonded interface between the two components in the CN/ZnO composites. The performance of the photocatalytic Cr(VI) reduction indicated that CN/ZnO exhibited better photocatalytic activity than pure ZnO under visible-light irradiation and the photocatalyst composite with a lower loading of CN sheets eventually displayed higher activity. The enhanced performance of CN/ZnO photocatalysts could be ascribed to the increased absorption of the visible light and the effective transfer and separation of the photogenerated charge carriers. PMID:28335301

Facile fabrication of transparent TiO2-C@TiO2-C free-standing film for visible-light photocatalytic application

NASA Astrophysics Data System (ADS)

Hu, Luyang; Zhang, Yumin; Zhang, Shanmei; Li, Benxia

2017-02-01

A transparent TiO2-C@TiO2-C free-standing film has been synthesized by two-step hydrothermal method and subsequent thermal annealing. The chemical composition and morphological features of the TiO2-C@TiO2-C film are characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and N2 adsorption-desorption measurement. The results indicate that the flower-like micro/nanostructure TiO2-C particle layers are intimately inhered to porous TiO2-C fibers. The fibers in film are interconnected each other to form a three-dimensional reticulate microstructure, and exhibit intense visible light absorption and high adsorptivity of dye molecules. The interaction between TiO2 and its surface carbon layer in TiO2-C particle promotes the generation of Ti-O-C bonds, which leads to effective charge transfer. Under visible-light irradiation, TiO2-C@TiO2-C film presents enhanced photocatalytic activity for degradation of methylene blue. This work may provide a new viewpoint for designing transparent photocatalytic film for promising applications in heterogeneous photocatalysis.

Femtosecond Snapshots of quantum mechanics at work in plasmonic nano-structures

NASA Astrophysics Data System (ADS)

Carbone, Fabrizio

Ultrafast Transmission Electron Microscopy enabled a new technique (Photon-Induced Near Field Electron Microscopy, PINEM), capable of controlling electromagnetic fields confined on the surface of nanostructures and image their properties with nm-resolution in direct space and fs resolution in time. In this presentation, we will show some recent results where the standing wave formed by the plasmonic field confined on the surface of one silver nano-wire was imaged together with its energy exchange with the imaging electrons. In these results, both the interference and the quantization of the plasmonic near field could be imaged simultaneously, revealing both a quantum and a classical aspect of the electromagnetic field in one snapshot. The implications of these results will be discussed, and we will also present new ideas and methodologies to go beyond such an experiment and image the interaction between single electrons and single plasmons. We will also show that shaping the electron density in a thin film via light pulses is possible by taking advantage of the plasmon-plasmon interference and the ability of light polarization to control the excitation of different plasmonic field geometries in ad hoc designed nanostructures. Movies of the propagation of plasmons will also be presented, providing insights into their speed, propagation losses and the effect of confinment. This work was supported by an ERC Grant USED.

Facile solvothermal synthesis of cube-like Ag@AgCl: a highly efficient visible light photocatalyst

NASA Astrophysics Data System (ADS)

Han, Lei; Wang, Ping; Zhu, Chengzhou; Zhai, Yueming; Dong, Shaojun

2011-07-01

In this paper, a stable and highly efficient plasmonic photocatalyst, Ag@AgCl, with cube-like morphology, has been successfully prepared via a simple hydrothermal method. Using methylene dichloride as chlorine source in the synthesis can efficiently control the morphology of Ag@AgCl, due to the low release rate of chloride ions. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectra were used to characterize the obtained product. The photocatalytic activity of the obtained product was evaluated by the photodegradation of methyl orange (MO) under visible light irradiation, and it was found, interestingly, that Ag@AgCl exhibits high visible light photocatalytic activity and good stability.In this paper, a stable and highly efficient plasmonic photocatalyst, Ag@AgCl, with cube-like morphology, has been successfully prepared via a simple hydrothermal method. Using methylene dichloride as chlorine source in the synthesis can efficiently control the morphology of Ag@AgCl, due to the low release rate of chloride ions. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectra were used to characterize the obtained product. The photocatalytic activity of the obtained product was evaluated by the photodegradation of methyl orange (MO) under visible light irradiation, and it was found, interestingly, that Ag@AgCl exhibits high visible light photocatalytic activity and good stability. Electronic supplementary information (ESI) available: SEM images of the AgCl samples synthesized by changing the addition amount of PVP and AgNO3. See DOI: 10.1039/c1nr10247h

In-situ fabrication of diketopyrrolopyrrole-carbazole-based conjugated polymer/TiO2 heterojunction for enhanced visible light photocatalysis

NASA Astrophysics Data System (ADS)

Yang, Long; Yu, Yuyan; Zhang, Jianling; Chen, Fu; Meng, Xiao; Qiu, Yong; Dan, Yi; Jiang, Long

2018-03-01

Aiming at developing highly efficient photocatalysts by broadening the light-harvesting region and suppressing photo-generated electron-hole recombination simultaneously, this work reports rational design and fabrication of donor-acceptor (D-A) conjugated polymer/TiO2 heterojunction catalyst with strong interfacial interactions by a facile in-situ thermal treatment. To expand the light-harvesting window, soluable conjugated copolymers with D-A architecture are prepared by Pd-mediated polycondensation of diketopyrrolopyrrole (DPP) and t-butoxycarbonyl (t-Boc) modified carbazole (Car), and used as visible-light-harvesting antenna to couple with TiO2 nanocrystals. The DPP-Car/TiO2 composites show wide range absorption in 300-1000 nm. To improve the interfacial binding at the interface, a facile in-situ thermal treatment is carried out to cleave the pendant t-Boc groups in carbazole units and liberate the polar amino groups (-NH-) which strongly bind to the surface of TiO2 through dipole-dipole interactions, forming a heterojunction interface. This in-situ thermal treatment changes the surface elemental distribution of TiO2, reinforces the interface bonding at the boundary of conjugated polymers/TiO2 and finally improves the photocatalytic efficiency of DPP-Car/TiO2 under visible-light irradiation. The interface changes are characterized and verified through Fourier-transform infrared spectroscopy (FT-IR), photo images, UV/Vis (solution state and powder diffuse reflection spectroscopy), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fluorescence, scanning electron microscopy(SEM) and transmission electron microscopy (TEM) techniques. This study provides a new strategy to avoid the low solubility of D-A conjugated polymers and construct highly-efficient conjugated polymer/TiO2 heterojunction by enforcing the interface contact and facilitating charge or energy transfer for the applications in photocatalysis.

SRRF: Universal live-cell super-resolution microscopy.

PubMed

Culley, Siân; Tosheva, Kalina L; Matos Pereira, Pedro; Henriques, Ricardo

2018-08-01

Super-resolution microscopy techniques break the diffraction limit of conventional optical microscopy to achieve resolutions approaching tens of nanometres. The major advantage of such techniques is that they provide resolutions close to those obtainable with electron microscopy while maintaining the benefits of light microscopy such as a wide palette of high specificity molecular labels, straightforward sample preparation and live-cell compatibility. Despite this, the application of super-resolution microscopy to dynamic, living samples has thus far been limited and often requires specialised, complex hardware. Here we demonstrate how a novel analytical approach, Super-Resolution Radial Fluctuations (SRRF), is able to make live-cell super-resolution microscopy accessible to a wider range of researchers. We show its applicability to live samples expressing GFP using commercial confocal as well as laser- and LED-based widefield microscopes, with the latter achieving long-term timelapse imaging with minimal photobleaching. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Correlative near-infrared light and cathodoluminescence microscopy using Y2O3:Ln, Yb (Ln = Tm, Er) nanophosphors for multiscale, multicolour bioimaging

PubMed Central

Fukushima, S.; Furukawa, T.; Niioka, H.; Ichimiya, M.; Sannomiya, T.; Tanaka, N.; Onoshima, D.; Yukawa, H.; Baba, Y.; Ashida, M.; Miyake, J.; Araki, T.; Hashimoto, M.

2016-01-01

This paper presents a new correlative bioimaging technique using Y2O3:Tm, Yb and Y2O3:Er, Yb nanophosphors (NPs) as imaging probes that emit luminescence excited by both near-infrared (NIR) light and an electron beam. Under 980 nm NIR light irradiation, the Y2O3:Tm, Yb and Y2O3:Er, Yb NPs emitted NIR luminescence (NIRL) around 810 nm and 1530 nm, respectively, and cathodoluminescence at 455 nm and 660 nm under excitation of accelerated electrons, respectively. Multimodalities of the NPs were confirmed in correlative NIRL/CL imaging and their locations were visualized at the same observation area in both NIRL and CL images. Using CL microscopy, the NPs were visualized at the single-particle level and with multicolour. Multiscale NIRL/CL bioimaging was demonstrated through in vivo and in vitro NIRL deep-tissue observations, cellular NIRL imaging, and high-spatial resolution CL imaging of the NPs inside cells. The location of a cell sheet transplanted onto the back muscle fascia of a hairy rat was visualized through NIRL imaging of the Y2O3:Er, Yb NPs. Accurate positions of cells through the thickness (1.5 mm) of a tissue phantom were detected by NIRL from the Y2O3:Tm, Yb NPs. Further, locations of the two types of NPs inside cells were observed using CL microscopy. PMID:27185264

A new species of Dianthus (Caryophyllaceae) from Antalya, South Anatolia, Turkey.

PubMed

Deniz, İsmail Gökhan; Aykurt, Candan; Genç, İlker; Aksoy, Ahmet

2016-01-01

Dianthus multiflorus from Gazipaşa (Antalya), south Anatolia (Turkey), is described as a new annual species with verrucose calyx. The morphological differences from the species within the same group with Dianthus multiflorus, which are Dianthus aydogdui, Dianthus cyri and Dianthus tripunctatus, are discussed. The International Union for Conservation of Nature (IUCN) threat category and observations on the ecology of the populations are noted. The karyology and seed micromorphology of Dianthus multiflorus and Dianthus tripunctatus were examined by light microscopy and scanning electron microscopy.

A Cyanobacterium Capable of Swimming Motility

NASA Astrophysics Data System (ADS)

Waterbury, John B.; Willey, Joanne M.; Franks, Diana G.; Valois, Frederica W.; Watson, Stanley W.

1985-10-01

A novel cyanobacterium capable of swimming motility wass isolated in pure culture from several locations in the Atlantic Ocean. It is a small unicellular form, assignable to the genus Synechococcus, that is capable of swimming through liquids at speeds of 25 micrometers per second. Light microscopy revealed that the motile cells display many features characteristic of bacterial flagellar motility. However, electron microscopy failed to reveal flagella and shearing did not arrest motility, indicating that the cyanobacterium may be propelled by a novel mechanism.

Synthesis of BiOCl nanosheets with oxygen vacancies for the improved photocatalytic properties

NASA Astrophysics Data System (ADS)

Cai, Yujie; Li, Dongya; Sun, Jingyu; Chen, Mengdie; Li, Yirui; Zou, Zhongwei; Zhang, Hua; Xu, Haiming; Xia, Dongsheng

2018-05-01

The square-sharped BiOCl nanosheets with oxygen vacancies were successfully synthesized via a facile hydrothermal route using xylitol as surfactant. The as-prepared BiOCl samples were characterized by Powder X-ray Diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), UV-Vis diffuse reflectance spectra (DRS), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) and Electron spin resonance (ESR). The as-prepared samples were phase-pure with the width and the thickness were about 50-400 nm and 20-50 nm respectively. Besides, the photodegradation performances showed the BiOCl nanosheets with 0.1 g concentration of xylitol (BOC-1) had the best photocatalytic activity under visible light due to its special polycrystalline structure, grain boundary and an optimum concentration of oxygen vacancies. The h+ and radO2- were the two main active species during the photocatalytic process and the possible photocatalytic mechanism was proposed.

Identification of morphological markers of sarcopenia at early stage of aging in skeletal muscle of mice.

PubMed

Sayed, Ramy K A; de Leonardis, Erika Chacin; Guerrero-Martínez, José A; Rahim, Ibtissem; Mokhtar, Doaa M; Saleh, Abdelmohaimen M; Abdalla, Kamal E H; Pozo, María J; Escames, Germaine; López, Luis C; Acuña-Castroviejo, Darío

2016-10-01

The gastrocnemius muscle (GM) of young (3months) and aged (12months) female wild-type C57/BL6 mice was examined by light and electron microscopy, looking for the presence of structural changes at early stage of the aging process. Morphometrical parameters including body and gastrocnemius weights, number and type of muscle fibers, cross section area (CSA), perimeter, and Feret's diameter of single muscle fiber, were measured. Moreover, lengths of the sarcomere, A-band, I-band, H-zone, and number and CSA of intermyofibrillar mitochondria (IFM), were also determined. The results provide evidence that 12month-old mice had significant changes on skeletal muscle structure, beginning with the reduction of gastrocnemius weight to body weight ratio, compatible with an early loss of skeletal muscle function and strength. Moreover, light microscopy revealed increased muscle fibers size, with a significant increase on their CSA, perimeter, and diameter of both type I and type II muscle fibers, and a reduction in the percentage of muscle area occupied by type II fibers. Enhanced connective tissue infiltrations, and the presence of centrally nucleated muscle fibers, were also found in aged mice. These changes may underlie an attempt to compensate the loss of muscle mass and muscle fibers number. Furthermore, electron microscopy discovered a significant age-dependent increase in the length of sarcomeres, I and H bands, and reduction on the overlapped actin/myosin length, supporting contractile force loss with age. Electron microscopy also showed an increased number and CSA of IFM with age, which may reveal more endurance at 12months of age. Together, mice at early stage of aging already show significant changes in gastrocnemius muscle morphology and ultrastructure that are suggestive of the onset of sarcopenia. Copyright © 2016 Elsevier Inc. All rights reserved.

Studying aerosol light scattering based on aspect ratio distribution observed by fluorescence microscope.

PubMed

Li, Li; Zheng, Xu; Li, Zhengqiang; Li, Zhanhua; Dubovik, Oleg; Chen, Xingfeng; Wendisch, Manfred

2017-08-07

Particle shape is crucial to the properties of light scattered by atmospheric aerosol particles. A method of fluorescence microscopy direct observation was introduced to determine the aspect ratio distribution of aerosol particles. The result is comparable with that of the electron microscopic analysis. The measured aspect ratio distribution has been successfully applied in modeling light scattering and further in simulation of polarization measurements of the sun/sky radiometer. These efforts are expected to improve shape retrieval from skylight polarization by using directly measured aspect ratio distribution.

Ultrastructure of Sarcocystis bertrami sarcocysts from naturally infected donkey (Equus asinus) from Egypt

USDA-ARS?s Scientific Manuscript database

There is considerable confusion concerning Sarcocystis species in equids. Little is known of Sarcocystis infections in donkeys (Equus asinus). Here we describe the structure of Sarcocystis bertrami-like from the donkey by light and transmission electron microscopy (LM, TEM). Nineteen sarcocysts fro...

Photo-actuating materials based on elastomers and modified carbon nanotubes

NASA Astrophysics Data System (ADS)

Czaniková, Klaudia; Krupa, Igor; Ilčíková, Markéta; Kasák, Peter; Chorvát, , Dušan; Valentin, Marian; Šlouf, Miroslav; Mosnáček, Jaroslav; Mičušík, Matej; Omastová, Mária

2012-01-01

The photo-actuating behavior of new polymeric nanocomposite materials based on a commercial elastomer, an ethylene-vinylacetate copolymer (EVA), filled with multiwalled carbon nanotubes (MWCNT) was investigated. A good dispersion of the MWCNT within the elastomeric matrix was ensured by using a novel, specific compatibilizer consisting of pyrenyl and cholesteryl groups. A uniaxial orientation of the MWCNT within the matrix was induced with shear forces by employing a special custom-made punch/die system. Good dispergation and alignment of the MWCNT within the matrix were demonstrated by scanning electron microscopy. Transmission electron microscopy showed a good dispersion of the MWCNT within the composite. Photo-actuation was qualitatively characterized by atomic force microscopy and quantitatively characterized by nanoindentation. The samples prepared in the form of Braille element showed expansion upon illumination by light diodes. The maximal height deformation changes about 15% was detected when a blue diode was used.

The role of an organic matrix during the formation of siliceous scales in the heliozoon Actinophrys sol (actinophryida, protista).

PubMed

Newman, P J; Patterson, D J

1993-07-25

Actinophrys sol is a freshwater heliozoon which has trophic and encysted body forms. During encystment, siliceous scales are laid down in silica deposition vesicles. The scales form one layer of a multi-layered cyst wall. Scale production is described using light microscopy, transmission electron microscopy, scanning electron microscopy, and X-ray microanalysis. Silica is laid down on an organic matrix which is visible prior to silicification and after removal of silica with hydrofluoric acid. Actinophrys sol can be cultured under silica impoverished conditions, with the result that the siliceous plates are absent. The cysts continue to form but are fragile. Silica is not a prerequisite for the processes of encystment and cyst formation. Copyright © 1993 Gustav Fischer Verlag · Stuttgart · Jena · New York. Published by Elsevier GmbH.. All rights reserved.

Fabrication of meso-porous BiOI sensitized zirconia nanoparticles with enhanced photocatalytic activity under simulated solar light irradiation

NASA Astrophysics Data System (ADS)

Vignesh, K.; Suganthi, A.; Min, Bong-Ki; Kang, Misook

2015-01-01

In this present work, BiOI sensitized zirconia (BiOI-ZrO2) nanoparticles were fabricated using a precipitation-deposition method. The physicochemical characteristics of BiOI/ZrO2 were studied through X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), BET-surface area, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis-DRS) and photoluminescence (PL) spectroscopy techniques. The absorption maximum of ZrO2 was shifted to the visible region after sensitization with BiOI. BET-surface area results inferred that the prepared hetero-junctions were meso-porous in nature. The photocatalytic activity of BiOI-ZrO2 for the degradation of methyl violet (MV) dye under simulated solar light irradiation was investigated in detail. 3% BiOI-ZrO2 exhibited the highest photocatalytic performance (98% of MV degradation) when compared with ZrO2 and BiOI. The enhancement in the photocatalytic activity of BiOI-ZrO2 is ascribed to the sensitization effect of BiOI, suppression of electron-hole recombination and the formation of p-n hetero-junction.

Synthesis of BiVO4-GO-PVDF nanocomposite: An excellent, newly designed material for high photocatalytic activity towards organic dye degradation by tuning band gap energies

NASA Astrophysics Data System (ADS)

Biswas, Md Rokon Ud Dowla; Oh, Won-Chun

2018-06-01

BiVO4-GO-PVDF (PVDF = Polyvinylidene Difluoride) photocatalyst is successfully synthesized by ultrasonication method and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy techniques. Morphology of BiVO4-GO-PVDF looks like a human embryo embedded inside an amniotic sac. Photocatalytic performance of BiVO4-GO-PVDF for decolorization of methylene blue is investigated. BiVO4-GO-PVDF system reveals enhanced photocatalytic activity degradation of methylene blue (MB), Rhodamine B (RhB) & Safranin-O (SO) in water under visible light irradiation as compared to the pure BiVO4 catalyst, BiVO4 & PTFE decorated on the graphene sheet. The experimental result reveals that the covering of graphene sheets in this composite catalyst enhances photocatalytic performance under visible light. This enhanced activity is mainly attributed to effective quenching of the photogenerated electron-hole pairs confirmed by photoluminescence spectra. Trapping experiments of radicals and holes were conducted to detect reactive species generated in the photocatalytic system, experimental results revealed that direct hole oxidation reaction is obviously dominant during photocatalytic reactions on the BiVO4-GO-PVDF system.

Magnetically recoverable TiO2-WO3 photocatalyst to oxidize bisphenol A from model wastewater under simulated solar light.

PubMed

Dominguez, S; Huebra, M; Han, C; Campo, P; Nadagouda, M N; Rivero, M J; Ortiz, I; Dionysiou, D D

2017-05-01

A novel magnetically recoverable, visible light active TiO 2 -WO 3 composite (Fe 3 O 4 @SiO 2 @TiO 2 -WO 3 ) was prepared to enable the photocatalyst recovery after the degradation of bisphenol A (BPA) under simulated solar light. For comparison, the photocatalytic activity of other materials such as non-magnetic TiO 2 -WO 3 , Fe 3 O 4 @SiO 2 @TiO 2 , TiO 2 , and the commercial TiO 2 P25 was also evaluated under the studied experimental conditions. The structure and morphology of the synthesized materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and electron dispersion spectroscopy (EDS). Moreover, Brunauer-Emmett-Teller (BET) surface area and magnetic properties of the samples were determined. The Fe 3 O 4 @SiO 2 @TiO 2 -WO 3 and TiO 2 -WO 3 led to a BPA degradation of 17.50 and 27.92 %, respectively, after 2 h of the simulated solar light irradiation. Even though their activity was lower than that of P25, which degraded completely BPA after 1 h, our catalysts were magnetically separable for their further reuse in the treatment. Furthermore, the influence of the water matrix in the photocatalytic activity of the samples was studied in municipal wastewater. Finally, the identification of reaction intermediates was performed and a possible BPA degradation pathway was proposed to provide a better understanding of the degradation process. Graphical abstract ᅟ.

Black TiO2 nanobelts/g-C3N4 nanosheets Laminated Heterojunctions with Efficient Visible-Light-Driven Photocatalytic Performance

PubMed Central

Shen, Liyan; Xing, Zipeng; Zou, Jinlong; Li, Zhenzi; Wu, Xiaoyan; Zhang, Yuchi; Zhu, Qi; Yang, Shilin; Zhou, Wei

2017-01-01

Black TiO2 nanobelts/g-C3N4 nanosheets laminated heterojunctions (b-TiO2/g-C3N4) as visible-light-driven photocatalysts are fabricated through a simple hydrothermal-calcination process and an in-situ solid-state chemical reduction approach, followed by the mild thermal treatment (350 °C) in argon atmosphere. The prepared samples are evidently investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, N2 adsorption, and UV-visible diffuse reflectance spectroscopy, respectively. The results show that special laminated heterojunctions are formed between black TiO2 nanobelts and g-C3N4 nanosheets, which favor the separation of photogenerated electron-hole pairs. Furthermore, the presence of Ti3+ and g-C3N4 greatly enhance the absorption of visible light. The resultant b-TiO2/g-C3N4 materials exhibit higher photocatalytic activity than that of g-C3N4, TiO2, b-TiO2 and TiO2/g-C3N4 for degradation of methyl orange (95%) and hydrogen evolution (555.8 μmol h−1 g−1) under visible light irradiation. The apparent reaction rate constant (k) of b-TiO2/g-C3N4 is ~9 times higher than that of pristine TiO2. Therefore, the high-efficient laminated heterojunction composites will have potential applications in fields of environment and energy. PMID:28165021

355, 532, and 1064 nm picosecond laser interaction with grass tissues

NASA Astrophysics Data System (ADS)

Kim, Jaehun; Ki, Hyungson

2012-12-01

In this article, we investigate how 355, 532, and 1064 nm picosecond lasers interact with grass tissues. We have identified five interaction regimes, and based on this classification, interaction maps have been constructed from a systematic experiment. The optical properties of light absorbing grass constituents are studied theoretically in order to understand how and how much light is absorbed by grass tissues. Scanning electron microscopy and optical microscopy are employed for observing morphological and structural changes of grass tissues. To the best of the authors' knowledge, this is the first investigation into laser interaction with plant leaves and reveals some fundamental findings regarding how a laser interacts with grass tissues and how plant leaves can be processed using lasers.

Micro-CT scouting for transmission electron microscopy of human tissue specimens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morales, A. G.; Stempinski, E. S.; XIAO, X.

Transmission electron microscopy (TEM) provides sub-nanometre-scale details in volumetric samples. Samples such as pathology tissue specimens are often stained with a metal element to enhance contrast, which makes them opaque to optical microscopes. As a result, it can be a lengthy procedure to find the region of interest inside a sample through sectioning. Here, we describe micro-CT scouting for TEM that allows noninvasive identification of regions of interest within a block sample to guide the sectioning step. In a tissue pathology study, a bench-top micro-CT scanner with 10 m resolution was used to determine the location of patches of themore » mucous membrane in osmium-stained human nasal scraping samples. Furthermore, once the regions of interest were located, the sample block was sectioned to expose that location, followed by ultra-thin sectioning and TEM to inspect the internal structure of the cilia of the membrane epithelial cells with nanometre resolution. This method substantially reduced the time and labour of the search process from typically 20 sections for light microscopy to three sections with no added sample preparation. Lay description Electron microscopy provides very high levels of detail in a small area, and thus the question of where to look in an opaque sample, such as a stained tissue specimen, needs to be answered by sectioning the sample in small steps and examining the sections under a light microscope, until the region of interest is found. The search process can be lengthy and labor intensive, especially for a study involving a large number of samples. Small areas of interest can be missed in the process if not enough regions are examined. We also describe a method to directly locate the region of interest within a whole sample using micro-CT imaging, bypassing the need of blindly sectioning. Micro-CT enables locating the region within 3D space; this information provides a guide for sectioning the sample to expose that precise location for high resolution electron microscopy imaging. In a human tissue specimen study, this method considerably reduced the time and labor of the search process.« less

Immune Defenses of the Invasive Apple Snail Pomacea canaliculata (Caenogastropoda, Ampullariidae): Phagocytic Hemocytes in the Circulation and the Kidney

PubMed Central

Vega, Israel A.; Castro-Vazquez, Alfredo

2015-01-01

Hemocytes in the circulation and kidney islets, as well as their phagocytic responses to microorganisms and fluorescent beads, have been studied in Pomacea canaliculata, using flow cytometry, light microscopy (including confocal laser scanning microscopy) and transmission electron microscopy (TEM). Three circulating hemocyte types (hyalinocytes, agranulocytes and granulocytes) were distinguished by phase contrast microscopy of living cells and after light and electron microscopy of fixed material. Also, three different populations of circulating hemocytes were separated by flow cytometry, which corresponded to the three hemocyte types. Hyalinocytes showed a low nucleus/cytoplasm ratio, and no apparent granules in stained material, but showed granules of moderate electron density under TEM (L granules) and at least some L granules appear acidic when labeled with LysoTracker Red. Both phagocytic and non-phagocytic hyalinocytes lose most (if not all) L granules when exposed to microorganisms in vitro. The phagosomes formed differed whether hyalinocytes were exposed to yeasts or to Gram positive or Gram negative bacteria. Agranulocytes showed a large nucleus/cytoplasm ratio and few or no granules. Granulocytes showed a low nucleus/cytoplasm ratio and numerous eosinophilic granules after staining. These granules are electron dense and rod-shaped under TEM (R granules). Granulocytes may show merging of R granules into gigantic ones, particularly when exposed to microorganisms. Fluorescent bead exposure of sorted hemocytes showed phagocytic activity in hyalinocytes, agranulocytes and granulocytes, but the phagocytic index was significantly higher in hyalinocytes. Extensive hemocyte aggregates ('islets') occupy most renal hemocoelic spaces and hyalinocyte-like cells are the most frequent component in them. Presumptive glycogen deposits were observed in most hyalinocytes in renal islets (they also occur in the circulation but less frequently) and may mean that hyalinocytes participate in the storage and circulation of this compound. Injection of microorganisms in the foot results in phagocytosis by hemocytes in the islets, and the different phagosomes formed are similar to those in circulating hyalinocytes. Dispersed hemocytes were obtained after kidney collagenase digestion and cell sorting, and they were able to phagocytize fluorescent beads. A role for the kidney as an immune barrier is proposed for this snail. PMID:25893243

Immune Defenses of the Invasive Apple Snail Pomacea canaliculata (Caenogastropoda, Ampullariidae): Phagocytic Hemocytes in the Circulation and the Kidney.

PubMed

Cueto, Juan A; Rodriguez, Cristian; Vega, Israel A; Castro-Vazquez, Alfredo

2015-01-01

Hemocytes in the circulation and kidney islets, as well as their phagocytic responses to microorganisms and fluorescent beads, have been studied in Pomacea canaliculata, using flow cytometry, light microscopy (including confocal laser scanning microscopy) and transmission electron microscopy (TEM). Three circulating hemocyte types (hyalinocytes, agranulocytes and granulocytes) were distinguished by phase contrast microscopy of living cells and after light and electron microscopy of fixed material. Also, three different populations of circulating hemocytes were separated by flow cytometry, which corresponded to the three hemocyte types. Hyalinocytes showed a low nucleus/cytoplasm ratio, and no apparent granules in stained material, but showed granules of moderate electron density under TEM (L granules) and at least some L granules appear acidic when labeled with LysoTracker Red. Both phagocytic and non-phagocytic hyalinocytes lose most (if not all) L granules when exposed to microorganisms in vitro. The phagosomes formed differed whether hyalinocytes were exposed to yeasts or to Gram positive or Gram negative bacteria. Agranulocytes showed a large nucleus/cytoplasm ratio and few or no granules. Granulocytes showed a low nucleus/cytoplasm ratio and numerous eosinophilic granules after staining. These granules are electron dense and rod-shaped under TEM (R granules). Granulocytes may show merging of R granules into gigantic ones, particularly when exposed to microorganisms. Fluorescent bead exposure of sorted hemocytes showed phagocytic activity in hyalinocytes, agranulocytes and granulocytes, but the phagocytic index was significantly higher in hyalinocytes. Extensive hemocyte aggregates ('islets') occupy most renal hemocoelic spaces and hyalinocyte-like cells are the most frequent component in them. Presumptive glycogen deposits were observed in most hyalinocytes in renal islets (they also occur in the circulation but less frequently) and may mean that hyalinocytes participate in the storage and circulation of this compound. Injection of microorganisms in the foot results in phagocytosis by hemocytes in the islets, and the different phagosomes formed are similar to those in circulating hyalinocytes. Dispersed hemocytes were obtained after kidney collagenase digestion and cell sorting, and they were able to phagocytize fluorescent beads. A role for the kidney as an immune barrier is proposed for this snail.

Micro-CT scouting for transmission electron microscopy of human tissue specimens

DOE PAGES

Morales, A. G.; Stempinski, E. S.; XIAO, X.; ...

2016-02-08

Transmission electron microscopy (TEM) provides sub-nanometre-scale details in volumetric samples. Samples such as pathology tissue specimens are often stained with a metal element to enhance contrast, which makes them opaque to optical microscopes. As a result, it can be a lengthy procedure to find the region of interest inside a sample through sectioning. Here, we describe micro-CT scouting for TEM that allows noninvasive identification of regions of interest within a block sample to guide the sectioning step. In a tissue pathology study, a bench-top micro-CT scanner with 10 m resolution was used to determine the location of patches of themore » mucous membrane in osmium-stained human nasal scraping samples. Furthermore, once the regions of interest were located, the sample block was sectioned to expose that location, followed by ultra-thin sectioning and TEM to inspect the internal structure of the cilia of the membrane epithelial cells with nanometre resolution. This method substantially reduced the time and labour of the search process from typically 20 sections for light microscopy to three sections with no added sample preparation. Lay description Electron microscopy provides very high levels of detail in a small area, and thus the question of where to look in an opaque sample, such as a stained tissue specimen, needs to be answered by sectioning the sample in small steps and examining the sections under a light microscope, until the region of interest is found. The search process can be lengthy and labor intensive, especially for a study involving a large number of samples. Small areas of interest can be missed in the process if not enough regions are examined. We also describe a method to directly locate the region of interest within a whole sample using micro-CT imaging, bypassing the need of blindly sectioning. Micro-CT enables locating the region within 3D space; this information provides a guide for sectioning the sample to expose that precise location for high resolution electron microscopy imaging. In a human tissue specimen study, this method considerably reduced the time and labor of the search process.« less

Distinct lobes of Limulus ventral photoreceptors. I. Functional and anatomical properties of lobes revealed by removal of glial cells

PubMed Central

1982-01-01

Removing the glial cells that encase Limulus ventral photoreceptors allows direct observation of the cell surface. Light microscopy of denuded photoreceptors reveals a subdivision of the cell body into lobes. Often one lobe, but sometimes several, is relatively clear and translucent (the R lobes). The lobe adjacent to the axon (the A lobe) has a textured appearance. Scanning electron microscopy shows that microvilli cover the surface of R lobes and are absent from the surface of A lobes. When a dim spot of light is incident on the R lobe, the probability of evoking a single photon response is two to three orders of magnitude higher than when the same spot is incident on the A lobe. We conclude that the sensitivity of the cell to light is principally a function of the R lobe. PMID:7175490

Light microscopy morphological characteristics of the sperm flagellum may be related to axonemal abnormalities.

PubMed

Mitchell, V; Sigala, J; Ballot, C; Jumeau, F; Barbotin, A L; Duhamel, A; Rives, N; Rigot, J M; Escalier, D; Peers, M C

2015-03-01

Although electron microscopy provides a detailed analysis of ultrastructural abnormalities, this technique is not available in all laboratories. We sought to determine whether certain characteristics of the flagellum as assessed by light microscopy were related to axonemal abnormalities. Forty-one patients with an absence of outer dynein arms (type I), a lack of a central complex (type III) and an absence of peripheral doublets (type IV) were studied. Sperm morphology was scored according to David's modified classification. Flagella with an irregular thickness were classified as being of normal length, short or broken. There were correlations between missing outer dynein arms and abnormal, short or coiled flagellum. Type III patients showed the highest flagellar defects (a short (P = 0.0027) or an absent flagellum (P = 0.011)). Just over 68% of the irregular flagella were short in Type III patients, whereas this value was only 34.5% in type I and 26.4% in type IV (P = 0.002). There was a negative correlation between misassembly and spermatozoa of irregular flagella (r = -0.79; P = 0.019). It is concluded that light microscopy analysis of flagellum abnormalities may help provide a correct diagnosis, identify sperm abnormalities with fertility potentials and outcomes in assisted reproduction technologies and assess the genetic risk. © 2014 Blackwell Verlag GmbH.

Histology and ultrastructure of picosecond laser intrastromal photorefractive keratectomy (ISPRK)

NASA Astrophysics Data System (ADS)

Krueger, Ronald R.; Quantock, Andrew J.; Ito, Mitsutoshi; Assil, Kerry K.; Schanzlin, David J.

1995-05-01

Picosecond intrastromal ablation is currently under investigation as a new minimally invasive way of correcting refractive error. When the laser pulses are placed in an expanding spiral pattern along a lamellar plane, the technique is called intrastromal photorefractive keratectomy (ISPRK). We performed ISPRK on six human eye bank eyes. Thirty picosecond pulses at 1000 Hz and 20 - 25 (mu) J per pulse were separated by 15 microns. A total of 3 layers were placed in the anterior stroma separated by 15 microns. The eyes were then preserved and sectioned for light, scanning and transmission electron microscopy. Light and scanning electron microscopy reveals that picosecond intrastromal ablation using an ISPRK pattern demonstrates multiple, coalescing intrastromal cavities oriented parallel to the corneal surface. These cavities possess a smooth appearing inner wall. Using transmission electron microscopy, we noticed tissue loss surrounding some cavities with collagen fibril termination and thinning of collagen lamella. Other cavities we formed by separation of lamella with little evidence of tissue loss. A pseudomembrane lines the edge of some cavities. Although underlying tissue disruption was occasionally seen along the border of a cavity in no case was there any evidence of thermal damage or tissue necrosis. Ablation and loss of tissue in ISPRK results in nonthermal microscopic corneal thinning around some cavities whereas others demonstrate only lamellar separation. Alternative patterns and energy parameters should be investigated to bring this technology to its full potential in refractive surgery.

Modified solvothermal synthesis of cobalt ferrite (CoFe2O4) magnetic nanoparticles photocatalysts for degradation of methylene blue with H2O2/visible light

NASA Astrophysics Data System (ADS)

Kalam, Abul; Al-Sehemi, Abdullah G.; Assiri, Mohammed; Du, Gaohui; Ahmad, Tokeer; Ahmad, Irfan; Pannipara, M.

2018-03-01

Different grads of magnetic nano-scaled cobalt ferrites (CoFe2O4) photocatalysts were synthesized by modified Solvothermal (MST) process with and without polysaccharide. The indigenously synthesized photocatalysts were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermo gravimetric analysis (TGA), Fourier transform infrared (FT-IR), UV-visible (UV-vis) spectroscopy and N2 adsorption-desorption isotherm method. The Fourier transform infrared spectroscopy study showed the Fe-O stretching vibration 590-619 cm-1, confirming the formation of metal oxide. The crystallite size of the synthesized photocatalysts was found in the range between 20.0 and 30.0 nm. The surface area of obtained magnetic nanoparticles is found to be reasonably high in the range of 63.0-76.0 m2/g. The results shown that only MST-2 is the most active catalyst for photo-Fenton like scheme for fast photodegradation action of methylene blue dye, this is possible due to optical band gap estimated of 2.65 eV. Captivatingly the percentage of degradation efficiency increases up to 80% after 140 min by using MST-2 photocatalyst. Photocatalytic degradation of methylene blue (MB) dye under visible light irradiation with cobalt ferrite magnetic nanoparticles followed first order kinetic constant and rate constant of MST-2 is almost 2.0 times greater than MST-1 photocatalyst.

Three-Dimensional Human Bronchial-Tracheal Epithelial Tissue-Like Assemblies (TLAs) as Hosts for Severe Acute Respiratory Syndrome (SARS)-CoV Infection

NASA Technical Reports Server (NTRS)

Suderman, M. T.; McCarthy, M.; Mossell, E.; Watts, D. M.; Peters, C. J.; Shope, R.; Goodwin, T. J.

2006-01-01

A three-dimensional (3-D) tissue-like assembly (TLA) of human bronchial-tracheal mesenchymal (HBTC) cells with an overlay of human bronchial epithelial (BEAS-2B) cells was constructed using a NASA Bioreactor to survey the infectivity of SARS-CoV. This TLA was inoculated with a low passage number Urbani strain of SARS-CoV. At selected intervals over a 10-day period, media and cell aliquots of the 3-D TLA were harvested for viral titer assay and for light and electron microscopy examination. All viral titer assays were negative in both BEAS-2B two-dimensional monolayer and TLA. Light microscopy immunohistochemistry demonstrated antigen-antibody reactivity with anti-SARS-CoV polyclonal antibody to spike and nuclear proteins on cell membranes and cytoplasm. Coronavirus Group 2 cross-reactivity was demonstrated by positive reaction to anti-FIPV 1 and anti-FIPV 1 and 2 antibodies. TLA examination by transmission electron microscopy indicated increasing cytoplasmic vacuolation with numerous electron-dense bodies measuring 45 to 270 nm from days 4 through 10. There was no evidence of membrane blebbing, membrane duplication, or fragmentation of organelles in the TLAs. However, progressive disruption of endoplasmic reticulum was observed throughout the cells. Antibody response to SARS-CoV specific spike and nucleocapsid glycoproteins, cross-reactivity with FIPV antibodies, and the cytoplasmic pathology suggests this HBTE TLA model is permissive to SARS-CoV infection.

Ultrastructure and Glycoconjugate Pattern of the Foot Epithelium of the Abalone Haliotis tuberculata (Linnaeus, 1758) (Gastropoda, Haliotidae)

PubMed Central

Bravo Portela, I.; Martinez-Zorzano, V. S.; Molist- Perez, I.; Molist García, P.

2012-01-01

The foot epithelium of the gastropod Haliotis tuberculata is studied by light and electron microscopy in order to contribute to the understanding of the anatomy and functional morphology of the mollusks integument. Study of the external surface by scanning electron microscopy reveals that the side foot epithelium is characterized by a microvillus border with a very scant presence of small ciliary tufts, but the sole foot epithelium bears a dense field of long cilia. Ultrastructural examination by transmission electron microscopy of the side epithelial cells shows deeply pigmented cells with high electron-dense granular content which are not observed in the epithelial sole cells. Along the pedal epithelium, seven types of secretory cells are present; furthermore, two types of subepithelial glands are located just in the sole foot. The presence and composition of glycoconjugates in the secretory cells and subepithelial glands are analyzed by conventional and lectin histochemistry. Subepithelial glands contain mainly N-glycoproteins rich in fucose and mannose whereas secretory cells present mostly acidic sulphated glycoconjugates such as glycosaminoglycans and mucins, which are rich in galactose, N-acetyl-galactosamine, and N-acetyl-glucosamine. No sialic acid is present in the foot epithelium. PMID:22645482

The future of electron microscopy

DOE PAGES

Zhu, Yimei; Durr, Hermann

2015-04-01

Seeing is believing. So goes the old adage and seen evidence is undoubtedly satisfying because it can be interpreted easily, though not always correctly. For centuries, humans have developed such instruments as telescopes that observe the heavens and microscopes that reveal bacteria and viruses. The 2014 Nobel Prize in Chemistry was awarded to Eric Betzig, Stefan Hell, and William Moerner for their foundational work on superresolution fluorescence microscopy in which they overcame the Abbe diffraction limit for the resolving power of conventional light microscopes. (See Physics Today, December 2014, page 18.) That breakthrough enabled discoveries in biological research and testifiesmore » to the importance of modern microscopy.« less

Electronic cameras for low-light microscopy.

PubMed

Rasnik, Ivan; French, Todd; Jacobson, Ken; Berland, Keith

2013-01-01

This chapter introduces to electronic cameras, discusses the various parameters considered for evaluating their performance, and describes some of the key features of different camera formats. The chapter also presents the basic understanding of functioning of the electronic cameras and how these properties can be exploited to optimize image quality under low-light conditions. Although there are many types of cameras available for microscopy, the most reliable type is the charge-coupled device (CCD) camera, which remains preferred for high-performance systems. If time resolution and frame rate are of no concern, slow-scan CCDs certainly offer the best available performance, both in terms of the signal-to-noise ratio and their spatial resolution. Slow-scan cameras are thus the first choice for experiments using fixed specimens such as measurements using immune fluorescence and fluorescence in situ hybridization. However, if video rate imaging is required, one need not evaluate slow-scan CCD cameras. A very basic video CCD may suffice if samples are heavily labeled or are not perturbed by high intensity illumination. When video rate imaging is required for very dim specimens, the electron multiplying CCD camera is probably the most appropriate at this technological stage. Intensified CCDs provide a unique tool for applications in which high-speed gating is required. The variable integration time video cameras are very attractive options if one needs to acquire images at video rate acquisition, as well as with longer integration times for less bright samples. This flexibility can facilitate many diverse applications with highly varied light levels. Copyright © 2007 Elsevier Inc. All rights reserved.

Effect of ferroelastic domain pattern changes on the EPR spectra in TDM

NASA Astrophysics Data System (ADS)

Zapart, W.; Zapart, M. B.

2011-09-01

This article presents polarized light microscopy studies of the ferroelastic domain structure and the analysis of electron paramagnetic resonance spectra of Cr3+ admixture ions in trigonal double molybdates. The correlation has been found between abnormal EPR lineshape and domain structure in ferroelastic phases of these crystals.

Morphological characterization of the antennal sensilla of the dogwood borer (Lepidoptera: Sesiidae)

USDA-ARS?s Scientific Manuscript database

The external morphology of the dogwood borer antennae and their sensilla was investigated using light and scanning electron microscopy. Male and female antennaes were clavate before tapering to an apical point and consisted of three main segments; the scape, pedicel, and flagellum. Although, there...

Using Asymmetric Flow Field-Flow Fractionation (AF4) to Determine C60 Colloidal Size Distributions

EPA Science Inventory

The formation of aqueous fullerene suspensions by solvent exchange, sonication, or extended mixing in water is widely reported. Commonly used methods for determining the size of these aggregates rely on static and dynamic light scattering, electron microscopy (EM), or atomic forc...

The first description of eggs in the male reproductive system of Physaloptera bispiculata (Nematoda: Spiruroidaea).

PubMed

Oliveira-Menezes, A; Lanfredi-Rangel, A; Lanfredi, R M

2011-06-01

Physaloptera bispiculata (Nematoda: Spiruroidaea) is a parasite of Nectomys squamipes (Rodentia: Cricetidae), a water rat that only occurs in Brazil. Naturally infected rodents were captured in the municipality of Rio Bonito, Rio de Janeiro, Brazil. Adult P. bispiculata worms were collected, prepared and analysed by light and scanning electron microscopy. Under scanning electron microscopy, several eggs were seen glued by cement to the cloacal aperture. Light microscopy revealed that some male worms had an uncountable number of embryonated eggs in the ejaculatory duct, cloaca and also in the posterior portion of the intestine. The probable explanation is that the eggs developing in the female uterus are pumped by the female or sucked by the male to the cloacal opening and from this point to the intestine and ejaculatory duct. The male probably does not have the ability to expel the eggs and for this reason a large number were found in these organs. On the other hand, this could be an important adaptation for the parasite, i.e. male worms expelled by the host can carry a large number of eggs and spread them to intermediate hosts when ingested by these hosts. As far as we know this is the first record of a physalopterid nematode harbouring eggs in the cloacal region, ejaculatory duct or intestine.

Paravascular channels, cisterns, and the subarachnoid space in the rat brain: A single compartment with preferential pathways

PubMed Central

Bedussi, Beatrice; van der Wel, Nicole N; de Vos, Judith; van Veen, Henk; Siebes, Maria; VanBavel, Ed

2016-01-01

Recent evidence suggests an extensive exchange of fluid and solutes between the subarachnoid space and the brain interstitium, involving preferential pathways along blood vessels. We studied the anatomical relations between brain vasculature, cerebrospinal fluid compartments, and paravascular spaces in male Wistar rats. A fluorescent tracer was infused into the cisterna magna, without affecting intracranial pressure. Tracer distribution was analyzed using a 3D imaging cryomicrotome, confocal microscopy, and correlative light and electron microscopy. We found a strong 3D colocalization of tracer with major arteries and veins in the subarachnoid space and large cisterns, attributed to relatively large subarachnoid space volumes around the vessels. Confocal imaging confirmed this colocalization and also revealed novel cisternal connections between the subarachnoid space and ventricles. Unlike the vessels in the subarachnoid space, penetrating arteries but not veins were surrounded by tracer. Correlative light and electron microscopy images indicated that this paravascular space was located outside of the endothelial layer in capillaries and just outside of the smooth muscle cells in arteries. In conclusion, the cerebrospinal fluid compartment, consisting of the subarachnoid space, cisterns, ventricles, and para-arteriolar spaces, forms a continuous and extensive network that surrounds and penetrates the rat brain, in which mixing may facilitate exchange between interstitial fluid and cerebrospinal fluid. PMID:27306753

Paravascular channels, cisterns, and the subarachnoid space in the rat brain: A single compartment with preferential pathways.

PubMed

Bedussi, Beatrice; van der Wel, Nicole N; de Vos, Judith; van Veen, Henk; Siebes, Maria; VanBavel, Ed; Bakker, Erik Ntp

2017-04-01

Recent evidence suggests an extensive exchange of fluid and solutes between the subarachnoid space and the brain interstitium, involving preferential pathways along blood vessels. We studied the anatomical relations between brain vasculature, cerebrospinal fluid compartments, and paravascular spaces in male Wistar rats. A fluorescent tracer was infused into the cisterna magna, without affecting intracranial pressure. Tracer distribution was analyzed using a 3D imaging cryomicrotome, confocal microscopy, and correlative light and electron microscopy. We found a strong 3D colocalization of tracer with major arteries and veins in the subarachnoid space and large cisterns, attributed to relatively large subarachnoid space volumes around the vessels. Confocal imaging confirmed this colocalization and also revealed novel cisternal connections between the subarachnoid space and ventricles. Unlike the vessels in the subarachnoid space, penetrating arteries but not veins were surrounded by tracer. Correlative light and electron microscopy images indicated that this paravascular space was located outside of the endothelial layer in capillaries and just outside of the smooth muscle cells in arteries. In conclusion, the cerebrospinal fluid compartment, consisting of the subarachnoid space, cisterns, ventricles, and para-arteriolar spaces, forms a continuous and extensive network that surrounds and penetrates the rat brain, in which mixing may facilitate exchange between interstitial fluid and cerebrospinal fluid.

Microscopic analysis of Spodoptera frugiperda (Lepidoptera: Noctuidae) embryonic development before and after treatment with azadirachtin, lufenuron, and deltamethrin.

PubMed

Correia, Alicely A; Wanderley-Teixeira, Valéria; Teixeira, Alvaro A C; Oliveira, José V; Gonçalves, Gabriel G A; Cavalcanti, MaríIia G S; Brayner, Fábio A; Alves, Luiz C

2013-04-01

The botanical insecticides, growth regulators, and pyrethroids have an effect on the biology of Spodoptera frugiperda (Smith). However, no emphasis has been given to the effect of these insecticides on embryonic development of insects, in histological level. Thus, this research aimed to examine by light and scanning electron microscopy S. frugiperda eggs and to describe the embryonic development, before and after immersion treatment, using commercial concentrations and lower concentrations than commercial ones, of the compounds lufenuron (Match), azadirachtin (AzaMax), and deltamethrin (Decis-positive control). For light microscopy semithin sections of eggs were used, and for scanning electron microscopy, images of the surface of eggs, treated and untreated with insecticides. The morphological characteristics of S. frugiperda eggs, in general, were similar to those described in the literature for most of the insects in the order Lepidoptera. Spherical eggs slightly flattened at the poles, with chorion, yolk, vitelline membrane, and embryo formation. In both microscopic analysis, we observed that insecticides acted immediately and independent of concentration, resulting absence, or incomplete embryo, presented yolk granules widely dispersed, without vitellophage formation, chorion disintegration, disorganized blastoderm, presenting vacuoles, yolk region with amorphous cells, and formation of completely uncharacterized appendages. Thus, we conclude that the compounds lufenuron and azadirachtin interfere on S. frugiperda embryonic development.

Preparation, characterization and photocatalytic activity of visible-light-driven plasmonic Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xiaojuan, E-mail: lixiaojuan@fzu.edu.cn; Tang, Duanlian; Tang, Fan

2014-08-15

Highlights: • A plasmonic Ag/AgBr/ZnFe{sub 2}O{sub 4} photocatalyst has been successfully synthesized. • Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposites exhibit high visible light photocatalytic activity. • Ag/AgBr/ZnFe{sub 2}O{sub 4} photocatalyst is stable and magnetically separable. - Abstract: A visible-light-driven plasmonic Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposite has been successfully synthesized via a deposition–precipitation and photoreduction through a novel one-pot process. X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy were employed to investigate the crystal structure, chemical composition, morphology, and optical properties of the as-prepared nanocomposites. The photocatalytic activities of the nanocomposites were evaluated by photodegradationmore » of Rhodamine B (RhB) and phenol under visible light. The results demonstrated that the obtained Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposites exhibited higher photocatalytic activity as compared to pure ZnFe{sub 2}O{sub 4}. In addition, the sample photoreduced for 20 min and calcined at 500 °C achieved the highest photocatalytic activity. Furthermore, the Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposite has high stability under visible light irradiation and could be conveniently separated by using an external magnetic field.« less

Not all that glitters is gold-Electron microscopy study on uptake of gold nanoparticles in Daphnia magna and related artifacts.

PubMed

Jensen, Louise Helene Søgaard; Skjolding, Lars Michael; Thit, Amalie; Sørensen, Sara Nørgaard; Købler, Carsten; Mølhave, Kristian; Baun, Anders

2017-06-01

Increasing use of engineered nanoparticles has led to extensive research into their potential hazards to the environment and human health. Cellular uptake from the gut is sparsely investigated, and microscopy techniques applied for uptake studies can result in misinterpretations. Various microscopy techniques were used to investigate internalization of 10-nm gold nanoparticles in Daphnia magna gut lumen and gut epithelial cells following 24-h exposure and outline potential artifacts (i.e., high-contrast precipitates from sample preparation related to these techniques). Light sheet microscopy confirmed accumulation of gold nanoparticles in the gut lumen. Scanning transmission electron microscopy and elemental analysis revealed gold nanoparticles attached to the microvilli of gut cells. Interestingly, the peritrophic membrane appeared to act as a semipermeable barrier between the lumen and the gut epithelium, permitting only single particles through. Structures resembling nanoparticles were also observed inside gut cells. Elemental analysis could not verify these to be gold, and they were likely artifacts from the preparation, such as osmium and iron. Importantly, gold nanoparticles were found inside holocrine cells with disrupted membranes. Thus, false-positive observations of nanoparticle internalization may result from either preparation artifacts or mistaking disrupted cells for intact cells. These findings emphasize the importance of cell integrity and combining elemental analysis with the localization of internalized nanoparticles using transmission electron microscopy. Environ Toxicol Chem 2017;36:1503-1509. © 2016 SETAC. © 2016 SETAC.

Contribution of high-resolution correlative imaging techniques in the study of the liver sieve in three-dimensions.

PubMed

Braet, Filip; Wisse, Eddie; Bomans, Paul; Frederik, Peter; Geerts, Willie; Koster, Abraham; Soon, Lilian; Ringer, Simon

2007-03-01

Correlative microscopy has become increasingly important for the analysis of the structure, function, and dynamics of cells. This is largely due to the result of recent advances in light-, probe-, laser- and various electron microscopy techniques that facilitate three-dimensional studies. Furthermore, the improved understanding in the past decade of imaging cell compartments in the third dimension has resulted largely from the availability of powerful computers, fast high-resolution CCD cameras, specifically developed imaging analysis software, and various probes designed for labeling living and or fixed cells. In this paper, we review different correlative high-resolution imaging methodologies and how these microscopy techniques facilitated the accumulation of new insights in the morpho-functional and structural organization of the hepatic sieve. Various aspects of hepatic endothelial fenestrae regarding their structure, origin, dynamics, and formation will be explored throughout this paper by comparing the results of confocal laser scanning-, correlative fluorescence and scanning electron-, atomic force-, and whole-mount electron microscopy. Furthermore, the recent advances of vitrifying cells with the vitrobot in combination with the glove box for the preparation of cells for cryo-electron microscopic investigation will be discussed. Finally, the first transmission electron tomography data of the liver sieve in three-dimensions are presented. The obtained data unambiguously show the involvement of special domains in the de novo formation and disappearance of hepatic fenestrae, and focuses future research into the (supra)molecular structure of the fenestrae-forming center, defenestration center and fenestrae-, and sieve plate cytoskeleton ring by using advanced cryo-electron tomography. (c) 2007 Wiley-Liss, Inc.

The Role of Electron Microscopy in Studying the Continuum of Changes in Membranous Structures during Poliovirus Infection

PubMed Central

Rossignol, Evan D.; Yang, Jie E.; Bullitt, Esther

2015-01-01

Replication of the poliovirus genome is localized to cytoplasmic replication factories that are fashioned out of a mixture of viral proteins, scavenged cellular components, and new components that are synthesized within the cell due to viral manipulation/up-regulation of protein and phospholipid synthesis. These membranous replication factories are quite complex, and include markers from multiple cytoplasmic cellular organelles. This review focuses on the role of electron microscopy in advancing our understanding of poliovirus RNA replication factories. Structural data from the literature provide the basis for interpreting a wide range of biochemical studies that have been published on virus-induced lipid biosynthesis. In combination, structural and biochemical experiments elucidate the dramatic membrane remodeling that is a hallmark of poliovirus infection. Temporal and spatial membrane modifications throughout the infection cycle are discussed. Early electron microscopy studies of morphological changes following viral infection are re-considered in light of more recent data on viral manipulation of lipid and protein biosynthesis. These data suggest the existence of distinct subcellular vesicle populations, each of which serves specialized roles in poliovirus replication processes. PMID:26473912

Corneal Biofilms: From Planktonic to Microcolony Formation in an Experimental Keratitis Infection with Pseudomonas Aeruginosa.

PubMed

Saraswathi, Padmanabhan; Beuerman, Roger W

2015-10-01

Microbial biofilms commonly comprise part of the infectious scenario, complicating the therapeutic approach. The purpose of this study was to determine in a mouse model of corneal infection if mature biofilms formed and to visualize the stages of biofilm formation. A bacterial keratitis model was established using Pseudomonas aeruginosa ATCC 9027 (1 × 10(8) CFU/ml) to infect the cornea of C57BL/6 black mouse. Eyes were examined post-infection (PI) on days 1, 2, 3, 5, and 7, and imaged by slit lamp microscopy, and light, confocal, and electron microscopy to identify the stages of biofilm formation and the time of appearance. On PI day 1, Gram staining showed rod-shaped bacteria adherent on the corneal surface. On PI days 2 and 3, bacteria were seen within webs of extracellular polymeric substance (EPS) and glycocalyx secretion, imaged by confocal microscopy. Scanning electron microscopy demonstrated microcolonies of active infectious cells bound with thick fibrous material. Transmission electron microscopy substantiated the formation of classical biofilm architecture with P. aeruginosa densely packed within the extracellular polymeric substances on PI days 5 and 7. Direct visual evidence showed that biofilms routinely developed on the biotic surface of the mouse cornea. The mouse model can be used to develop new approaches to deal therapeutically with biofilms in corneal infections. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Handling Golgi-impregnated tissue for light microscopy.

PubMed

Berbel, P J; Fairén, A

1983-08-08

The use of cyanocrylic glue to fix pieces of Golgi-stained nervous tissue on a paraffin blank is proposed for obtaining thick sections of unembedded tissue with a sliding microtome. This procedure makes correct orientation of the tissue easy during sectioning and makes it possible to obtain tissue sections quickly. The sections are flat-mounted using epoxy resin, resulting in permanent preparations with excellent optical properties and enabling further thin-sectioning for light and electron microscopic studies.

Dissociation of β-Sheet Stacking of Amyloid β Fibrils by Irradiation of Intense, Short-Pulsed Mid-infrared Laser.

PubMed

Kawasaki, Takayasu; Yaji, Toyonari; Ohta, Toshiaki; Tsukiyama, Koichi; Nakamura, Kazuhiro

2018-02-05

Structure of amyloid β (Aβ) fibrils is rigidly stacked by β-sheet conformation, and the fibril state of Aβ is profoundly related to pathogenesis of Alzheimer's disease (AD). Although mid-infrared light has been used for various biological researches, it has not yet been known whether the infrared light changes the fibril structure of Aβ. In this study, we tested the effect of irradiation of intense mid-infrared light from a free-electron laser (FEL) targeting the amide bond on the reduction of β-sheet content in Aβ fibrils. The FEL reduced entire contents of proteins exhibiting β-sheet structure in brain sections from AD model mice, as shown by synchrotron-radiation infrared microscopy analysis. Since Aβ 1-42 fibril absorbed a considerable FEL energy at amide I band (6.17 μm), we irradiated the FEL at 6.17 μm and found that β-sheet content of naked Aβ 1-42 fibril was decreased using infrared microscopic analysis. Consistent with the decrease in the β-sheet content, Congo-red signal is decreased after the irradiation to Aβ 1-42 fibril. Furthermore, electron microscopy analysis revealed that morphologies of the fibril and proto-fibril were largely changed after the irradiation. Thus, mid-infrared light dissociates β-sheet structure of Aβ fibrils, which justifies exploration of possible laser-based therapy for AD.

Rat animal model for preclinical testing of microparticle urethral bulking agents.

PubMed

Mann-Gow, Travis K; Blaivas, Jerry G; King, Benjamin J; El-Ghannam, Ahmed; Knabe, Christine; Lam, Michael K; Kida, Masatoshi; Sikavi, Cameron S; Plante, Mark K; Krhut, Jan; Zvara, Peter

2015-04-01

To develop an economic, practical and readily available animal model for preclinical testing of urethral bulking therapies, as well as to establish feasible experimental methods that allow for complete analysis of hard microparticle bulking agents. Alumina ceramic beads suspended in hyaluronic acid were injected into the proximal urethra of 15 female rats under an operating microscope. We assessed overall lower urinary tract function, bulking material intraurethral integrity and local host tissue response over time. Microphotographs were taken during injection and again 6 months postoperatively, before urethral harvest. Urinary flow rate and voiding frequency were assessed before and after injection. At 6 months, the urethra was removed and embedded in resin. Hard tissue sections were cut using a sawing microtome, and processed for histological analysis using scanning electron microscopy, light microscopy and immunohistochemistry. Microphotographs of the urethra showed complete volume retention of the bulking agent at 6 months. There was no significant difference between average urinary frequency and mean urinary flow rate at 1 and 3 months postinjection as compared with baseline. Scanning electron microscopy proved suitable for evaluation of microparticle size and integrity, as well as local tissue remodeling. Light microscopy and immunohistochemistry allowed for evaluation of an inflammatory host tissue reaction to the bulking agent. The microsurgical injection technique, in vivo physiology and novel hard tissue processing for histology, described in the present study, will allow for future comprehensive preclinical testing of urethral bulking therapy agents containing microparticles made of a hard material. © 2015 The Japanese Urological Association.

Posterior vitreous detachment induced by nattokinase (subtilisin NAT): a novel enzyme for pharmacologic vitreolysis.

PubMed

Takano, Akiomi; Hirata, Akira; Ogasawara, Kazuya; Sagara, Nina; Inomata, Yasuya; Kawaji, Takahiro; Tanihara, Hidenobu

2006-05-01

To investigate the effects of intravitreal injection of nattokinase (subtilisin NAT), a serine protease that is produced by Bacillus subtilis (natto), for induction of posterior vitreous detachment (PVD). Different doses of nattokinase (1, 0.1, or 0.01 fibrin-degradation units [FU]) or physiologic saline as a control were injected into the vitreous cavity of rabbit eyes. Scanning electron microscopy was used to observe the retinal surfaces of four rabbit eyes per concentration. Histologic alterations were assessed by light microscopy, using four eyes from each group. Electroretinography (ERG) was performed to observe retinal function, ranging from 1 hour to 1 week after the nattokinase (1 or 0.1 FU) or saline solution administration, using four eyes from each group at each time point. Also, findings in all rabbits were monitored by slit lamp examination and by indirect ophthalmoscopy with a 20-D lens. Scanning electron microscopy showed smooth retinal surfaces, indicating the occurrence of PVD at 30 minutes after intervention in all the experimental eyes injected with 0.1 or 1.0 FU nattokinase, but none of the control eyes. Light microscopy and ERG analysis showed no critical change even after the use of 0.1 FU nattokinase, an amount sufficient to induce PVD. However, toxicity in the forms of preretinal hemorrhage and ERG changes was noted with the higher dose (1 FU) of nattokinase. The results suggested that nattokinase is a useful enzyme for pharmacologic vitreolysis because of its efficacy in inducing PVD.

Morphological observation of the stria vascularis in midkine and pleiotrophin knockout mice.

PubMed

Sone, Michihiko; Muramatsu, Hisako; Muramatsu, Takashi; Nakashima, Tsutomu

2011-02-01

Midkine and Pleiotrophin are low molecular weight basic proteins with closely related structures and serve as growth/differentiation factors. They have been reported to be expressed in the cochlea during the embryonic and perinatal periods. In the present study, we focused on the roles of midkine and pleiotrophin in the stria vascularis and investigated morphological changes using mice deficient in these genes. Midkine knockout, pleiotrophin knockout, and double knockout mice were used and compared to wild-type mice. Auditory brain stem responses (ABRs) and cochlear blood flows were measured in each type of mice. Pathological changes in the stria vascularis were examined by light microscopy, including immunohistochemical staining with anti-Kir4.1 antibody, and electron microscopy. Hearing thresholds examined by ABRs were significantly higher in midkine knockout and pleiotrophin knockout mice than in wild-type mice. Double knockout mice showed higher thresholds compared to midkine knockout and pleiotrophin knockout mice. Blood flow in the lateral walls did not significantly differ and light microscopy examination showed an almost normal appearance of the stria vascularis in these knockout mice. However, the expression of Kir4.1 was weak in the knockout mice and severe vacuolar degeneration was observed by electron microscopy in the intermediate cells of the double knockout mice. The present study demonstrates that midkine and pleiotrophin play some roles for the morphological maintenance of intermediate cell in the stria vascularis. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Sequential Immunofluorescent Light Microscopy and Electron Microscopy of Recombination Nodules During Meiotic Prophase I.

PubMed

Anderson, Lorinda K

2017-01-01

Immunolocalization using either fluorescence for light microscopy (LM) or gold particles for electron microscopy (EM) has become a common tool to pinpoint proteins involved in recombination during meiotic prophase. Each method has its advantages and disadvantages. For example, LM immunofluorescence is comparatively easier and higher throughput compared to immunogold EM localization. In addition, immunofluorescence has the advantages that a faint signal can often be enhanced by longer exposure times and colocalization using two (or more) probes with different absorbance and emission spectra is straightforward. However, immunofluorescence is not useful if the object of interest does not label with an antibody probe and is below the resolution of the LM. In comparison, immunogold EM localization is higher resolution than immunofluorescent LM localization, and individual nuclear structures, such as recombination nodules, can be identified by EM regardless of whether they are labeled or not. However, immunogold localization has other disadvantages including comparatively low signal-to-noise ratios, more difficult colocalization using gold particles of different sizes, and the inability to evaluate labeling efficiency before examining the sample using EM (a more expensive and time-consuming technique than LM). Here we describe a method that takes advantage of the good points of both immunofluorescent LM and EM to analyze two classes of late recombination nodules (RNs), only one of which labels with antibodies to MLH1 protein, a marker of crossovers. The method can be used readily with other antibodies to analyze early recombination nodules or other prophase I structures.

Property Characterization and Photocatalytic Activity Evaluation of BiGdO₃ Nanoparticles under Visible Light Irradiation.

PubMed

Luan, Jingfei; Shen, Yue; Zhang, Lingyan; Guo, Ningbin

2016-09-08

BiGdO₃ nanoparticles were prepared by a solid-state reaction method and applied in photocatalytic degradation of dyes in this study. BiGdO₃ was characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller, UV-Vis diffuse reflectance spectroscopy and transmission electron microscopy. The results showed that BiGdO₃ crystallized well with the fluorite-type structure, a face-centered cubic crystal system and a space group Fm3m 225. The lattice parameter of BiGdO₃ was 5.465 angstrom. The band gap of BiGdO₃ was estimated to be 2.25 eV. BiGdO₃ showed a strong optical absorption during the visible light region. Moreover, the photocatalytic activity of BiGdO₃ was evaluated by photocatalytic degradation of direct dyes in aqueous solution under visible light irradiation. BiGdO₃ demonstrated excellent photocatalytic activity in degrading Direct Orange 26 (DO-26) or Direct Red 23 (DR-23) under visible light irradiation. The photocatalytic degradation of DO-26 or DR-23 followed the first-order reaction kinetics, and the first-order rate constant was 0.0046 or 0.0023 min(-1) with BiGdO₃ as catalyst. The degradation intermediates of DO-26 were observed and the possible photocatalytic degradation pathway of DO-26 under visible light irradiation was provided. The effect of various operational parameters on the photocatalytic activity and the stability of BiGdO₃ particles were also discussed in detail. BiGdO₃/(visible light) photocatalysis system was confirmed to be suitable for textile industry wastewater treatment.

Efficiency enhancement in dye sensitized solar cells using dual function mesoporous silica as scatterer and back recombination inhibitor

NASA Astrophysics Data System (ADS)

Tanvi; Mahajan, Aman; Bedi, R. K.; Kumar, Subodh; Saxena, Vibha; Aswal, D. K.

2016-08-01

In the present work, we report the usage of mesoporous silica for improving light harvesting as well as for suppression of back recombination without affecting the extent of dye loading on TiO2 films. Synthesized mesoporous SiO2 was characterized by X-ray photoelectron spectroscopy, X-ray diffraction, Brunauer Emmett and Teller measurement, Scanning electron microscopy and Transmission electron microscopy. DSSCs were fabricated by incorporating different wt% of mesoporous SiO2 in TiO2 paste. An improvement of 50% was observed for devices fabricated using 0.75 wt% of mesoporous SiO2. The mechanism behind the improvement was investigated using electrochemical impedance spectroscopy and UV-Vis spectroscopy.

A facile synthesis of metal nanoparticle - graphene composites for better absorption of solar radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Bindu; Mulla, Rafiq; Rabinal, M. K., E-mail: mkrabinal@yahoo.com

2015-06-24

Herein, a facile chemical approach has been adopted to prepare silver nanoparticles (AgNPs)- graphene (G) composite to study photothermal effect. Sodium borohydride (SBH), a strong reducing agent has been selected for this work. Effect of SBH concentrations on optical behavior of AgNPs-G composite was also investigated. Resultant materials were characterized by various techniques including X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), optical absorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM micrographs confirm wrapping of AgNPs into graphene whereas XRD analysis reveals their particle size variation between 47 nm to 69 nm. Optical studies throw a light on theirmore » strong absorption behavior towards solar radiation.« less

Preparation of silver nanoparticles loaded graphene oxide nanosheets for antibacterial activity

NASA Astrophysics Data System (ADS)

T, T. T., Vi; Lue, S. J.

2016-11-01

A simple, facile method to fabricate successfully silver nanoparticle (AgNPs) decorated on graphene oxide (GO) layers via grafted thiol groups. Samples were prepared with different concentrations of AgNO3. Resulting AgNPs were quasi-spherical in shape and attached on the layers of GO. Physical properties were confirmed by X-ray diffraction (XRD), zeta potential, dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectra, thermogravimetric analyzer (TGA), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM). Antimicrobial test was effectively showed using MRSA (Staphylococcus areus). The GO-Ag NPs with appropriate Ag NPs content of 0.2 M AgNO3 exhibited the strongest antibacterial activity at 48.77% inhibition after 4 hours incubation.

Cyclic Degradation Behavior of < 001 > -Oriented Fe-Mn-Al-Ni Single Crystals in Tension

NASA Astrophysics Data System (ADS)

Vollmer, M.; Kriegel, M. J.; Krooß, P.; Martin, S.; Klemm, V.; Weidner, A.; Chumlyakov, Y.; Biermann, H.; Rafaja, D.; Niendorf, T.

2017-12-01

In the present study, functional fatigue behavior of a near 〈001〉-oriented Fe-Mn-Al-Ni single crystal was investigated under tensile load. An incremental strain test up to 3.5% strain and cyclic tests up to 25 cycles revealed rapid pseudoelastic degradation. Progressive microstructural degradation was studied by in situ scanning electron microscopy. The results show a partially inhibited reactivation of previously formed martensite and proceeding activation of untransformed areas in subsequent cycles. The preferentially formed martensite variants were identified by means of Schmid factor calculation and the Kurdjumov-Sachs relationship. Post mortem transmission electron microscopy investigations shed light on the prevailing degradation mechanisms. Different types of dislocations were found promoting the progressive degradation during cyclic loading.

An electron microscopy examination of primary recrystallization in TD-nickel.

NASA Technical Reports Server (NTRS)

Petrovic, J. J.; Ebert, L. J.

1972-01-01

Primary recrystallization in TD-nickel 1 in. bar has previously been regarded as the process by which the initial fine grain structure is converted to a coarse grain size (increases in grain size by 500 times) under suitable deformation and annealing conditions. This process is dependent on deformation mode. While it occurs readily after rolling transverse to the bar axis and annealing (800 C), it is completely inhibited by longitudinal rolling and swaging deformations, even for very high (1320 C) annealing temperatures. A transmission electron microscopy examination of deformation and annealing substructures indicates that primary recrystallization in TD-nickel 1 in. bar actually occurs on the sub-light optical level, to produce a grain structure similar in size to the initial fine grained state.

Tracking the ultrafast motion of a single molecule by femtosecond orbital imaging

PubMed Central

Yu, Ping; Repp, Jascha; Huber, Rupert

2017-01-01

Watching a single molecule move on its intrinsic time scale—one of the central goals of modern nanoscience—calls for measurements that combine ultrafast temporal resolution1–8 with atomic spatial resolution9–30. Steady-state experiments achieve the requisite spatial resolution, as illustrated by direct imaging of individual molecular orbitals using scanning tunnelling microscopy9–11 or the acquisition of tip-enhanced Raman and luminescence spectra with sub-molecular resolution27–29. But tracking the dynamics of a single molecule directly in the time domain faces the challenge that single-molecule excitations need to be confined to an ultrashort time window. A first step towards overcoming this challenge has combined scanning tunnelling microscopy with so-called ‘lightwave electronics”1–8, which uses the oscillating carrier wave of tailored light pulses to directly manipulate electronic motion on time scales faster even than that of a single cycle of light. Here we use such ultrafast terahertz scanning tunnelling microscopy to access a state-selective tunnelling regime, where the peak of a terahertz electric-field waveform transiently opens an otherwise forbidden tunnelling channel through a single molecular state and thereby removes a single electron from an individual pentacene molecule’s highest occupied molecular orbital within a time window shorter than one oscillation cycle of the terahertz wave. We exploit this effect to record ~100 fs snapshot images of the structure of the orbital involved, and to reveal through pump-probe measurements coherent molecular vibrations at terahertz frequencies directly in the time domain and with sub-angstrom spatial resolution. We anticipate that the combination of lightwave electronics1–8 and atomic resolution of our approach will open the door to controlling electronic motion inside individual molecules at optical clock rates. PMID:27830788

Ultrafast structural and electronic dynamics of the metallic phase in a layered manganite

PubMed Central

Piazza, L.; Ma, C.; Yang, H. X.; Mann, A.; Zhu, Y.; Li, J. Q.; Carbone, F.

2013-01-01

The transition between different states in manganites can be driven by various external stimuli. Controlling these transitions with light opens the possibility to investigate the microscopic path through which they evolve. We performed femtosecond (fs) transmission electron microscopy on a bi-layered manganite to study its response to ultrafast photoexcitation. We show that a photoinduced temperature jump launches a pressure wave that provokes coherent oscillations of the lattice parameters, detected via ultrafast electron diffraction. Their impact on the electronic structure are monitored via ultrafast electron energy loss spectroscopy, revealing the dynamics of the different orbitals in response to specific structural distortions. PMID:26913564

Patterns of light interference produced by damaged cuticle cells in human hair.

PubMed

Gamez-Garcia, Manuel; Lu, Yuan

2007-01-01

Colorful patterns of light interference have been observed to occur in human hair cuticle cells. The light interference phenomenon has been analyzed by optical microscopy. The strong patterns of light interference appeared only in cuticle cells that had been damaged either mechanically or by thermal stresses. Cuticle cells that were not damaged did not produce this phenomenon. The zones of light interference on the hair surface were seen to extend to cuticle sheath areas whose damage was not apparent when analyzed under the Scanning Electron Microscope. The presence of oils and other hydrophobic materials in the hair had a strong effect in the appearance or disappearance of the interference patterns.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung, Woo-Young; Seol, Jae-Bok, E-mail: jb-seol@postech.ac.kr; Kwak, Chan-Min

The compositional distribution of In atoms in InGaN/GaN multiple quantum wells is considered as one of the candidates for carrier localization center, which enhances the efficiency of the light-emitting diodes. However, two challenging issues exist in this research area. First, an inhomogeneous In distribution is initially formed by spinodal decomposition during device fabrication as revealed by transmission electron microscopy. Second, electron-beam irradiation during microscopy causes the compositional inhomogeneity of In to appear as a damage contrast. Here, a systematic approach was proposed in this study: Electron-beam with current density ranging from 0 to 20.9 A/cm{sup 2} was initially exposed to themore » surface regions during microscopy. Then, the electron-beam irradiated regions at the tip surface were further removed, and finally, atom probe tomography was performed to run the samples without beam-induced damage and to evaluate the existence of local inhomegenity of In atoms. We proved that after eliminating the electron-beam induced damage regions, no evidence of In clustering was observed in the blue-emitting InGaN/GaN devices. In addition, it is concluded that the electron-beam induced localization of In atoms is a surface-related phenomenon, and hence spinodal decomposition, which is typically responsible for such In clustering, is negligible for biaxially strained blue-emitting InGaN/GaN devices.« less

UV-visible light-activated Ag-decorated, monodisperse TiO2 aggregates for treatment of the pharmaceutical oxytetracycline.

PubMed

Han, Changseok; Likodimos, Vlassis; Khan, Javed Ali; Nadagouda, Mallikarjuna N; Andersen, Joel; Falaras, Polycarpos; Rosales-Lombardi, Pablo; Dionysiou, Dionysios D

2014-10-01

Noble metal Ag-decorated, monodisperse TiO2 aggregates were successfully synthesized by an ionic strength-assisted, simple sol-gel method and were used for the photocatalytic degradation of the antibiotic oxytetracycline (OTC) under both UV and visible light (UV-visible light) irradiation. The synthesized samples were characterized by X-ray diffraction analysis (XRD); UV-vis diffuse reflectance spectroscopy; environmental scanning electron microscopy (ESEM); transmission electron microscopy (TEM); high-resolution TEM (HR-TEM); micro-Raman, energy-dispersive X-ray spectroscopy (EDS); and inductively coupled plasma optical emission spectrometry (ICP-OES). The results showed that the uniformity of TiO2 aggregates was finely tuned by the sol-gel method, and Ag was well decorated on the monodisperse TiO2 aggregates. The absorption of the samples in the visible light region increased with increasing Ag loading that was proportional to the amount of Ag precursor added in the solution over the tested concentration range. The Brunauer, Emmett, and Teller (The BET) surface area slightly decreased with increasing Ag loading on the TiO2 aggregates. Ag-decorated TiO2 samples demonstrated enhanced photocatalytic activity for the degradation of OTC under UV-visible light illumination compared to that of pure TiO2. The sample containing 1.9 wt% Ag showed the highest photocatalytic activity for the degradation of OTC under both UV-visible light and visible light illumination. During the experiments, the detected Ag leaching for the best TiO2-Ag photocatalyst was much lower than the National Secondary Drinking Water Regulation for Ag limit (0.1 mg L(-1)) issued by the US Environmental Protection Agency.

Determination of the Goos-Hanchen shift in dielectric waveguides via photo emission electron microscopy in the visible spectrum

DOE PAGES

Stenmark, Theodore; Word, R. C.; Konenkamp, R.

2016-02-16

Photoemission Electron Microscopy (PEEM) is a versatile tool that relies on the photoelectric effect to produce high-resolution images. Pulse lasers allow for multi-photon PEEM where multiple photons are required excite a single electron. This non-linear process can directly image the near field region of electromagnetic fields in materials. We use this ability here to analyze wave propagation in a linear dielectric waveguide with wavelengths of 410nm and 780nm. The propagation constant of the waveguide can be extracted from the interference pattern created by the coupled and incident light and shows distinct polarization dependence. Furthermore, the electromagnetic field interaction at themore » boundaries can then be deduced which is essential to understand power flow in wave guiding structures. These results match well with simulations using finite element techniques.« less

Electron microscopic demonstration of hormone-producing metastatic carcinoma of the choroid from the bronchus.

PubMed

Amemiya, T; Nomura, S

1975-01-01

Clinical, laboratory and pathological findings of a patient in bronchial carcinoma with choroidal metastasis were presented. X-ray examination of the chest suggested the tumor shadow in the posterior segmental bronchus of the right upper lobe of the lung (r-B2b), while funduscopy and fluorescein angiography revealed the presence of choroidal tumor. ACTH levels in tumor tissues at autopsy and in serum were measured and definitely demonstrated and elevated. Histopathologically, the primary lesion was r-B2b and diagnosed as a mucocellular type of adenocarcinoma. The choroidal lesion was metastatic carcinoma. Electron microscopic examination of the choroidal lesion reembedded for electron microscopy from celloidin-embedded materials for light microscopy could reveal the presence of characteristic cytoplasmic granules referred to as neurosecretory-type granules. It is extremely rare that a hormone-producing metastatic carcinoma of the choroid from the bronchus has been proved.

Atomic bonding effects in annular dark field scanning transmission electron microscopy. I. Computational predictions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Odlyzko, Michael L.; Mkhoyan, K. Andre, E-mail: mkhoyan@umn.edu; Himmetoglu, Burak

2016-07-15

Annular dark field scanning transmission electron microscopy (ADF-STEM) image simulations were performed for zone-axis-oriented light-element single crystals, using a multislice method adapted to include charge redistribution due to chemical bonding. Examination of these image simulations alongside calculations of the propagation of the focused electron probe reveal that the evolution of the probe intensity with thickness exhibits significant sensitivity to interatomic charge transfer, accounting for observed thickness-dependent bonding sensitivity of contrast in all ADF-STEM imaging conditions. Because changes in image contrast relative to conventional neutral atom simulations scale directly with the net interatomic charge transfer, the strongest effects are seen inmore » crystals with highly polar bonding, while no effects are seen for nonpolar bonding. Although the bonding dependence of ADF-STEM image contrast varies with detector geometry, imaging parameters, and material temperature, these simulations predict the bonding effects to be experimentally measureable.« less

Spall Response of Additive Manufactured Ti-6Al-4V

NASA Astrophysics Data System (ADS)

Brown, Andrew; Gregg, Adam; Escobedo, Jp; Hazell, Paul; East, Daniel; Quadir, Zakaria

2017-06-01

Additive manufactured (AM) Ti-6Al-4V was produced via electron beam melting (EBM) and laser melting deposition (LMD) techniques. The dynamic response of AM varieties of common aerospace and infrastructure metals are yet to be fully characterized and compared to their traditionally processed counterparts. Spall damage is one of the primary failure modes in metals subjected to shock loading from high velocity impact. Both EBM and LMD Ti-6Al-4V were shock loaded via flyer-target plate impact using a single-stage light gas gun. Target plates were subjected to pressures just above the spall strength of the material (3-5 GPa) to investigate the early onset of damage nucleation as a function of processing technique and shock orientation with respect to the AM-build direction. Post-mortem characterization of the spall damage and surrounding microstructure was performed using a combination of optical microscopy, scanning electron microscopy, and electron backscatter diffraction.

Hemizygous Fabry disease associated with membranous nephropathy: A rare case report
.

PubMed

Zhou, Wenyan; Ni, Zhaohui; Zhang, Minfang

2018-05-24

Fabry disease may coexist with various glomerular diseases, including IgA nephropathy, focal segmental glomerulosclerosis, etc. In this study, we report a rare case of Fabry disease associated with membranous nephropathy (MN). A 30-year-old man with nephrotic proteinuria, normal renal function, and no other extrarenal manifestations underwent a renal biopsy in February 2017. Light microscopy and immunofluorescence indicated MN (stage 1). Under an electron microscope, there were subepithelial electron-dense deposits and abundant zebra bodies in podocytes. Both the findings of low-activity α-galactosidase A (α-Gal A, GLA) and base deletion in exon 7 of the GLA gene (GLA-E07.1286_*7 del, a newly reported mutation) confirmed that this patient was simultaneously afflicted with Fabry disease. This case report is an important reminder of the role of kidney biopsy, especially electron microscopy, as an indicator of Fabry disease and its rare coexistence with MN.
.

Curcumin-sensitized TiO2 for enhanced photodegradation of dyes under visible light

NASA Astrophysics Data System (ADS)

Buddee, Supat; Wongnawa, Sumpun; Sriprang, Pimpaporn; Sriwong, Chaval

2014-04-01

Curcumin was coated on P25 TiO2 by using impregnation method from freshly prepared curcumin solution. The resulting products (Cur-TiO2-P25) was studied by several techniques such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier-transformed infrared spectroscopy, specific surface area by the Brunauer-Emmett-Teller method, and UV-Vis diffused reflectance spectroscopy. Experimental results revealed that impregnation of curcumin at 0.5, 3, 5, and 7 wt% did not affect the native phase of anatase and rutile in P25 significantly, however, it caused red shift of absorption onset in all curcumin-coated samples. The Cur-TiO2-P25 showed enhanced adsorption efficiency and increased photocatalytic activity under visible light with optimal result at 5 wt% curcumin content. Commercial anatase and rutile coated with curcumin (Cur-TiO2-an and Cur-TiO2-ru) were also prepared by the same method for the use in comparative studies of photodegradation of dyes. Cur-TiO2-an and Cur-TiO2-ru were also characterized with some selected equipment above but not as extensively as the Cur-TiO2-P25. Curcumin coating helped improve photocatalytic efficiencies of P25 and anatase but not for rutile. The mechanism of photocatalytic reaction was proposed that under visible light irradiation, curcumin molecule could act as dye sensitizing agent that injected electron into the conduction band of TiO2 leading to photodegradation of dyes.

Fluorescent light mediated a green synthesis of silver nanoparticles using the protein extract of weaver ant larvae.

PubMed

Khamhaengpol, Arunrat; Siri, Sineenat

2016-10-01

Alternative to crude plant extracts, a crude protein extract derived from animal cells is one of the potential sources of biomolecules for mediating a reduction of silver ions and a formation of silver nanoparticles (AgNPs) under a mild condition, which very few works have been reported. This work demonstrated a use of the protein extract of weaver ant larvae as a bio-facilitator for a simple, green synthesis of AgNPs under fluorescent light at room temperature. The protein extract of weaver ant larvae exhibited the reducing and antioxidant activities, which assisted a formation of AgNPs in the reaction containing only silver nitrate under light exposure. Transmission electron microscopy images revealed the dispersed, spherical AgNPs with an average size of 7.87±2.54nm. The maximum surface plasmon resonance (SPR) band of the synthesized AgNPs was at 435nm. The energy-dispersive X-ray analysis revealed that silver was a major element of the particles. The identity of AgNPs was confirmed by X-ray diffraction pattern, selected area electron diffraction and high resolution transmission electron microscopy analyses, which demonstrated the planes of face centered cubic silver. The synthesized AgNPs showed antibacterial activity against both Escherichia coli and Staphylococcus aureus with the minimum bactericidal concentration (MBC) values equally at 250μg/ml, suggesting their potential application as an effective antibacterial agent. Copyright © 2016 Elsevier B.V. All rights reserved.

A scanning transmission electron microscopy approach to analyzing large volumes of tissue to detect nanoparticles.

PubMed

Kempen, Paul J; Thakor, Avnesh S; Zavaleta, Cristina; Gambhir, Sanjiv S; Sinclair, Robert

2013-10-01

The use of nanoparticles for the diagnosis and treatment of cancer requires the complete characterization of their toxicity, including accurately locating them within biological tissues. Owing to their size, traditional light microscopy techniques are unable to resolve them. Transmission electron microscopy provides the necessary spatial resolution to image individual nanoparticles in tissue, but is severely limited by the very small analysis volume, usually on the order of tens of cubic microns. In this work, we developed a scanning transmission electron microscopy (STEM) approach to analyze large volumes of tissue for the presence of polyethylene glycol-coated Raman-active-silica-gold-nanoparticles (PEG-R-Si-Au-NPs). This approach utilizes the simultaneous bright and dark field imaging capabilities of STEM along with careful control of the image contrast settings to readily identify PEG-R-Si-Au-NPs in mouse liver tissue without the need for additional time-consuming analytical characterization. We utilized this technique to analyze 243,000 mm³ of mouse liver tissue for the presence of PEG-R-Si-Au-NPs. Nanoparticles injected into the mice intravenously via the tail vein accumulated in the liver, whereas those injected intrarectally did not, indicating that they remain in the colon and do not pass through the colon wall into the systemic circulation.

A Scanning Transmission Electron Microscopy (STEM) Approach to Analyzing Large Volumes of Tissue to Detect Nanoparticles

PubMed Central

Kempen, Paul J.; Thakor, Avnesh S.; Zavaleta, Cristina; Gambhir, Sanjiv S.; Sinclair, Robert

2013-01-01

The use of nanoparticles for the diagnosis and treatment of cancer requires the complete characterization of their toxicity, including accurately locating them within biological tissues. Owing to their size, traditional light microscopy techniques are unable to resolve them. Transmission electron microscopy provides the necessary spatial resolution to image individual nanoparticles in tissue but is severely limited by the very small analysis volume, usually on the order of tens of cubic microns. In this work we developed a scanning transmission electron microscopy (STEM) approach to analyze large volumes of tissue for the presence of polyethylene glycol coated Raman-active-silica-gold-nanoparticles (PEG-R-Si-Au-NPs). This approach utilizes the simultaneous bright and dark field imaging capabilities of STEM along with careful control of the image contrast settings to readily identify PEG-R-Si-Au-NPs in mouse liver tissue without the need for additional time consuming analytical characterization. We utilized this technique to analyze 243,000 µm3 of mouse liver tissue for the presence of PEG-R-Si-Au-NPs. Nanoparticles injected into the mice intravenously via the tail-vein accumulated in the liver while those injected intrarectally did not, indicating that they remain in the colon and do not pass through the colon wall into the systemic circulation. PMID:23803218

Characterization and Imaging of Antibody-Coated Gold Nanoparticles for Targeted Treatment of Microbial Keratitis

NASA Astrophysics Data System (ADS)

Mahan, Matthew

Microbial keratitis (MK) is an infection of the cornea by pathogenic organisms that causes inflammation and irritation. It can lead to full or partial blindness if left untreated. Current clinical treatment methods rely on high frequency application of topical drugs which are subject to the issues of patient compliance and microbial resistance. In this work, gold nanoparticles (AuNP) were proposed as an alternative treatment method in light-based therapies. Particle formulation methods were investigated and assessed using transmission electron microscopy (TEM) and ultraviolet/visible spectroscopy (UV-Vis). AuNP of 20 nm diameter were used as platforms to attach monoclonal antibodies anti-FLAG or anti-F1 to enhance their cell-targeting ability as well as polyethylene glycol to reduce non-specific binding and protein adsorption. These functionalized particles were qualitatively assessed using UV-Vis. The antibody-functionalized AuNP were then assessed for their ability to attach directly to Pseudomonas aeruginosa, expressing FLAG peptide, or Aspergillus fumigatus, expressing the F1 receptor. Attachment was imaged using dark field microscopy, transmission electron microscopy, and fluorescence microscopy.

Atomic electric fields revealed by a quantum mechanical approach to electron picodiffraction.

PubMed

Müller, Knut; Krause, Florian F; Béché, Armand; Schowalter, Marco; Galioit, Vincent; Löffler, Stefan; Verbeeck, Johan; Zweck, Josef; Schattschneider, Peter; Rosenauer, Andreas

2014-12-15

By focusing electrons on probes with a diameter of 50 pm, aberration-corrected scanning transmission electron microscopy (STEM) is currently crossing the border to probing subatomic details. A major challenge is the measurement of atomic electric fields using differential phase contrast (DPC) microscopy, traditionally exploiting the concept of a field-induced shift of diffraction patterns. Here we present a simplified quantum theoretical interpretation of DPC. This enables us to calculate the momentum transferred to the STEM probe from diffracted intensities recorded on a pixel array instead of conventional segmented bright-field detectors. The methodical development yielding atomic electric field, charge and electron density is performed using simulations for binary GaN as an ideal model system. We then present a detailed experimental study of SrTiO3 yielding atomic electric fields, validated by comprehensive simulations. With this interpretation and upgraded instrumentation, STEM is capable of quantifying atomic electric fields and high-contrast imaging of light atoms.

Atomic electric fields revealed by a quantum mechanical approach to electron picodiffraction

NASA Astrophysics Data System (ADS)

Müller, Knut; Krause, Florian F.; Béché, Armand; Schowalter, Marco; Galioit, Vincent; Löffler, Stefan; Verbeeck, Johan; Zweck, Josef; Schattschneider, Peter; Rosenauer, Andreas

2014-12-01

By focusing electrons on probes with a diameter of 50 pm, aberration-corrected scanning transmission electron microscopy (STEM) is currently crossing the border to probing subatomic details. A major challenge is the measurement of atomic electric fields using differential phase contrast (DPC) microscopy, traditionally exploiting the concept of a field-induced shift of diffraction patterns. Here we present a simplified quantum theoretical interpretation of DPC. This enables us to calculate the momentum transferred to the STEM probe from diffracted intensities recorded on a pixel array instead of conventional segmented bright-field detectors. The methodical development yielding atomic electric field, charge and electron density is performed using simulations for binary GaN as an ideal model system. We then present a detailed experimental study of SrTiO3 yielding atomic electric fields, validated by comprehensive simulations. With this interpretation and upgraded instrumentation, STEM is capable of quantifying atomic electric fields and high-contrast imaging of light atoms.

Atomic electric fields revealed by a quantum mechanical approach to electron picodiffraction

PubMed Central

Müller, Knut; Krause, Florian F.; Béché, Armand; Schowalter, Marco; Galioit, Vincent; Löffler, Stefan; Verbeeck, Johan; Zweck, Josef; Schattschneider, Peter; Rosenauer, Andreas

2014-01-01

By focusing electrons on probes with a diameter of 50 pm, aberration-corrected scanning transmission electron microscopy (STEM) is currently crossing the border to probing subatomic details. A major challenge is the measurement of atomic electric fields using differential phase contrast (DPC) microscopy, traditionally exploiting the concept of a field-induced shift of diffraction patterns. Here we present a simplified quantum theoretical interpretation of DPC. This enables us to calculate the momentum transferred to the STEM probe from diffracted intensities recorded on a pixel array instead of conventional segmented bright-field detectors. The methodical development yielding atomic electric field, charge and electron density is performed using simulations for binary GaN as an ideal model system. We then present a detailed experimental study of SrTiO3 yielding atomic electric fields, validated by comprehensive simulations. With this interpretation and upgraded instrumentation, STEM is capable of quantifying atomic electric fields and high-contrast imaging of light atoms. PMID:25501385

Characterization of swift heavy ion irradiation damage in ceria

DOE PAGES

Yablinsky, Clarissa A.; Devanathan, Ram; Pakarinen, Janne; ...

2015-03-04

Swift heavy ion induced radiation damage is investigated for ceria (CeO 2), which serves as a UO 2 fuel surrogate. Microstructural changes resulting from an irradiation with 940 MeV gold ions of 42 keV/nm electronic energy loss are investigated by means of electron microscopy accompanied by electron energy loss spectroscopy showing that there exists a small density reduction in the ion track core. While chemical changes in the ion track are not precluded, evidence of them was not observed. Classical molecular dynamics simulations of thermal spikes in CeO 2 with an energy deposition of 12 and 36 keV/nm show damagemore » consisting of isolated point defects at 12 keV/nm, and defect clusters at 36 keV/nm, with no amorphization at either energy. Furthermore, inferences are drawn from modeling about density changes in the ion track and the formation of interstitial loops that shed light on features observed by electron microscopy of swift heavy ion irradiated ceria.« less

Gastroesophageal junction of Anatolian shepherd dog; a study by topographic anatomy, scanning electron and light microscopy.

PubMed

Alsafy, M A M; El-Gendy, S A A

2012-03-01

The aim of this study was to cast a spotlight on the topography and to point out the clinical importance of the gastroesophageal junction (GEJ) in Anatolian Shepherd dogs. Nine Anatolian Shepherd dogs were used to study the morphology of the GEJ. The esophagus was appeared has a portion within the thoracic cavity while no portion of the esophagus presented within the abdominal cavity that documented the absence of the intra-abdominal portion in all studied dogs. The topographic anatomy, scanning electron and light microscopic examinations revealed that the gastroesophageal junction was located at the level of the phrenico-esophageal ligament (PEL) inside the esophageal hiatus. Our results were distinguished the morphology of the esophageal and gastric cardiac mucosa at the level of the gastroesophageal junction by the scanning electron micrographs. The light microscopical examination was explained the PEL attached to the esophageal side in one dog and to the gastric cardiac side in three dogs.

Light and electron microscopic analyses of Vasa expression in adult germ cells of the fish medaka.

PubMed

Yuan, Yongming; Li, Mingyou; Hong, Yunhan

2014-07-15

Germ cells of diverse animal species have a unique membrane-less organelle called germ plasm (GP). GP is usually associated with mitochondria and contains RNA binding proteins and mRNAs of germ genes such as vasa. GP has been described as the mitochondrial cloud (MC), intermitochondrial cement (IC) and chromatoid body (CB). The mechanism underlying varying GP structures has remained incompletely understood. Here we report the analysis of GP through light and electron microscopy by using Vasa as a marker in adult male germ cells of the fish medaka (Oryzias latipes). Immunofluorescence light microscopy revealed germ cell-specific Vasa expression. Vasa is the most abundant in mitotic germ cells (oogonia and spermatogonia) and reduced in meiotic germ cells. Vasa in round spermatids exist as a spherical structure reminiscent of CB. Nanogold immunoelectron microscopy revealed subcellular Vasa redistribution in male germ cells. Vasa in spermatogonia concentrates in small areas of the cytoplasm and is surrounded by mitochondria, which is reminiscent of MC. Vasa is intermixed with mitochondria to form IC in primary spermatocytes, appears as the free cement (FC) via separation from mitochondria in secondary spermatocyte and becomes condensed in CB at the caudal pole of round spermatids. During spermatid morphogenesis, Vasa redistributes and forms a second CB that is a ring-like structure surrounding the dense fiber of the flagellum in the midpiece. These structures resemble those described for GP in various species. Thus, Vasa identifies GP and adopts varying structures via dynamic reorganization at different stages of germ cell development. Copyright © 2014 Elsevier B.V. All rights reserved.

Nanoscale chromatin structure characterization for optical applications: a transmission electron microscopy study (Conference Presentation)

NASA Astrophysics Data System (ADS)

Li, Yue; Cherkezyan, Lusik; Zhang, Di; Almassalha, Luay; Roth, Eric; Chandler, John; Bleher, Reiner; Subramanian, Hariharan; Dravid, Vinayak P.; Backman, Vadim

2017-02-01

Structural and biological origins of light scattering in cells and tissue are still poorly understood. We demonstrate how this problem might be addressed through the use of transmission electron microscopy (TEM). For biological samples, TEM image intensity is proportional to mass-density, and thus proportional to refractive index (RI). By calculating the autocorrelation function (ACF) of TEM image intensity of a thin-section of cells, we essentially maintain the nanoscale ACF of the 3D cellular RI distribution, given that the RI distribution is statistically isotropic. Using this nanoscale 3D RI ACF, we can simulate light scattering through biological samples, and thus guiding many optical techniques to quantify specific structures. In this work, we chose to use Partial Wave Spectroscopy (PWS) microscopy as a one of the nanoscale-sensitive optical techniques. Hela cells were prepared using standard protocol to preserve nanoscale ultrastructure, and a 50-nm slice was sectioned for TEM imaging at 6 nm resolution. The ACF was calculated for chromatin, and the PWS mean sigma was calculated by summing over the power spectral density in the visible light frequency of a random medium generated to match the ACF. A 1-µm slice adjacent to the 50-nm slice was sectioned for PWS measurement to guarantee identical chromatin structure. For 33 cells, we compared the calculated PWS mean sigma from TEM and the value measured directly, and obtained a strong correlation of 0.69. This example indicates the great potential of using TEM measured RI distribution to better understand the quantification of cellular nanostructure by optical methods.

Cassette Series Designed for Live-Cell Imaging of Proteins and High Resolution Techniques in Yeast

PubMed Central

Young, Carissa L.; Raden, David L.; Caplan, Jeffrey; Czymmek, Kirk; Robinson, Anne S.

2012-01-01

During the past decade, it has become clear that protein function and regulation are highly dependent upon intracellular localization. Although fluorescent protein variants are ubiquitously used to monitor protein dynamics, localization, and abundance; fluorescent light microscopy techniques often lack the resolution to explore protein heterogeneity and cellular ultrastructure. Several approaches have been developed to identify, characterize, and monitor the spatial localization of proteins and complexes at the sub-organelle level; yet, many of these techniques have not been applied to yeast. Thus, we have constructed a series of cassettes containing codon-optimized epitope tags, fluorescent protein variants that cover the full spectrum of visible light, a TetCys motif used for FlAsH-based localization, and the first evaluation in yeast of a photoswitchable variant – mEos2 – to monitor discrete subpopulations of proteins via confocal microscopy. This series of modules, complete with six different selection markers, provides the optimal flexibility during live-cell imaging and multicolor labeling in vivo. Furthermore, high-resolution imaging techniques include the yeast-enhanced TetCys motif that is compatible with diaminobenzidine photooxidation used for protein localization by electron microscopy and mEos2 that is ideal for super-resolution microscopy. We have examined the utility of our cassettes by analyzing all probes fused to the C-terminus of Sec61, a polytopic membrane protein of the endoplasmic reticulum of moderate protein concentration, in order to directly compare fluorescent probes, their utility and technical applications. Our series of cassettes expand the repertoire of molecular tools available to advance targeted spatiotemporal investigations using multiple live-cell, super-resolution or electron microscopy imaging techniques. PMID:22473760

Atomic oxygen effects on thin film space coatings studied by spectroscopic ellipsometry, atomic force microscopy, and laser light scattering

NASA Technical Reports Server (NTRS)

Synowicki, R. A.; Hale, Jeffrey S.; Woollam, John A.

1992-01-01

The University of Nebraska is currently evaluating Low Earth Orbit (LEO) simulation techniques as well as a variety of thin film protective coatings to withstand atomic oxygen (AO) degradation. Both oxygen plasma ashers and an electron cyclotron resonance (ECR) source are being used for LEO simulation. Thin film coatings are characterized by optical techniques including Variable Angle Spectroscopic Ellipsometry, Optical spectrophotometry, and laser light scatterometry. Atomic Force Microscopy (AFM) is also used to characterize surface morphology. Results on diamondlike carbon (DLC) films show that DLC degrades with simulated AO exposure at a rate comparable to Kapton polyimide. Since DLC is not as susceptible to environmental factors such as moisture absorption, it could potentially provide more accurate measurements of AO fluence on short space flights.

Mast cell dynamics in the house rat (Rattus rattus) ovary during estrus cycle, pregnancy and lactation.

PubMed

Batth, B K; Parshad, R K

2000-02-01

The distribution of mast cells in various ovarian compartments was studied during different stages of the reproductive cycles in Rattus rattus. Two types of mast cell populations were recognized with light microscopy i.e., light purple and deep purple, the latter also includes deeply stained cells with extruded granules. Mast cells identified by electron microscopy showed the ultrastructural features during granule formation and release of their content. Significantly higher numbers of mast cells per unit area of ovary were seen at estrus and diestrus. Numbers of mast cells also remained high during pregnancy with possible involvement of mast cell products in vascularization of corpora lutea. A positive correlation existed between mast cell counts and embryo number during pregnancy. However, numbers of mast cells declined significantly after parturition.

Open LED Illuminator: A Simple and Inexpensive LED Illuminator for Fast Multicolor Particle Tracking in Neurons

PubMed Central

Bosse, Jens B.; Tanneti, Nikhila S.; Hogue, Ian B.; Enquist, Lynn W.

2015-01-01

Dual-color live cell fluorescence microscopy of fast intracellular trafficking processes, such as axonal transport, requires rapid switching of illumination channels. Typical broad-spectrum sources necessitate the use of mechanical filter switching, which introduces delays between acquisition of different fluorescence channels, impeding the interpretation and quantification of highly dynamic processes. Light Emitting Diodes (LEDs), however, allow modulation of excitation light in microseconds. Here we provide a step-by-step protocol to enable any scientist to build a research-grade LED illuminator for live cell microscopy, even without prior experience with electronics or optics. We quantify and compare components, discuss our design considerations, and demonstrate the performance of our LED illuminator by imaging axonal transport of herpes virus particles with high temporal resolution. PMID:26600461

Contrast in the Photoelectric Effect of Organic and Biochemical Surfaces

PubMed Central

Birrell, G. B.; Burke, C.; Dehlinger, P.; Griffith, O. H.

1973-01-01

The photoelectric effect can provide the physical basis for a new method of mapping organic and biological surfaces. The technique, photoelectron microscopy, is similar to fluorescence microscopy using incident ultraviolet light except that photoejected electrons form the image of the specimen surface. In this work the minimum wavelengths of incident light required to produce an image were determined for the molecules 3,6-bis(dimethylamino)acridine (acridine orange) (I), benzo[a]pyrene (II), N,N,N′,N′-tetraphenylbenzidine (III), and copper phthalocyanine (IV). The photoelectron image thresholds for these compounds are 220 (I), 215 (II), 220 (III), and 240 nm (IV), all ±5 nm. Contrast of I-IV with respect to typical protein, lipid, nucleic acid, and polysaccharide surfaces was examined over the wavelength range 240-180 nm. The low magnification micrographs exhibited bright areas corresponding to I-IV but dark regions for the biochemical surfaces. The high contrast suggests the feasibility of performing extrinsic photoelectron microscopy experiments through selective labeling of sites on biological surfaces. ImagesFIGURE 3 PMID:4704486

Impact of gluten-friendly™ technology on wheat kernel endosperm and gluten protein structure in seeds by light and electron microscopy.

PubMed

Landriscina, L; D'Agnello, P; Bevilacqua, A; Corbo, M R; Sinigaglia, M; Lamacchia, C

2017-04-15

The main aim of this paper was to assess the impact of Gluten-Friendly™ (GF) technology (Italian priority patent n° 102015000084813 filed on 17th December 2015) on wheat kernel endosperm morphology and gluten protein structure, using SEM, light and immunofluorescent microscopy. Microscopy was combined with immunodetection with specific antibodies for gliadins, γ-gliadins, LMW subunits and antigenic epitopes to gain a better understanding of the technology at a molecular level. The results showed significant changes to gluten proteins after GF treatment; cross-reactivity towards the antibodies recognizing almost the entire range of gluten proteins as well as the antigenic epitopes through the sequences QQSF, QQSY, PEQPFPQGC and QQPFP was significantly reduced. The present study confirms the results from our previous work and shows, for the first time, the mechanism by which a chemical-physical treatment abolishes the antigenic capacity of gluten. Copyright © 2016 Elsevier Ltd. All rights reserved.

Trichomes and chemical composition of the volatile oil of Trichogonia cinerea (Gardner) R. M. King & H. Rob. (Eupatorieae, Asteraceae).

PubMed

Fernandes, Yanne S; Trindade, Luma M P; Rezende, Maria Helena; Paula, José R; Gonçalves, Letícia A

2016-03-01

Trichogonia cinerea is endemic to Brazil and occurs in areas of cerrado and campo rupestre. In this study, we characterized the glandular and non-glandular trichomes on the aerial parts of this species, determined the principal events in the development of the former, and identified the main constituents of the volatile oil produced in its aerial organs. Fully expanded leaves, internodes, florets, involucral bracts, and stem apices were used for the characterization of trichomes. Leaves, internodes, florets, and involucral bracts were examined by light microscopy and scanning electron microscopy, whereas stem apices were examined only by light microscopy. Branches in the reproductive phase were used for the extraction and determination of the composition of the volatile oil. The species has three types of glandular trichomes, biseriate vesicular, biseriate pedunculate, and multicellular uniseriate, which secrete volatile oils and phenolic compounds. The major components identified in the volatile oil were 3,5-muuroladiene (39.56%) and butylated hydroxytoluene (13.07%).

Redescription of Oswaldocruzia chambrieri (Strongylida: Molineidae) from Rhinella margaritifera (Anura: Bufonidae) in Caxiuanã National Forest, Brazil.

PubMed

Willkens, Yuri; Maldonado, Arnaldo; Dos Santos, Jeannie Nascimento; Maschio, Gleomar Fabiano; de Vasconcelos Melo, Francisco Tiago

2016-09-01

Oswaldocruzia chambrieri Ben Slimane et Durette-Desset, 1993 is redescribed from specimens collected from the small intestine of the South American common toad, Rhinella margaritifera, from Caxiuanã National Forest in Pará, Brazil, using light and scanning microscopy and molecular analysis of Cytochrome Oxidase I (COI) - coding regions of DNA. The discovered nematodes are characterized by a type III caudal bursa with two papillae, rays 4 with a median groove, and spicules divided into a blade, a shoe and a fork. Cervical alae are absent, the cephalic vesicle is divided into two portions, and the synlophe has low ridges without chitinous supports. The present study establishes the Caxiuanã National Forest as a new location for O. chambrieri, which had previously been reported as a parasite of R. margaritifera in Ecuador, uses light microscopy and scanning electron microscopy (SEM) to identify new morphological characters of the species and represents the second molecular sequence deposited for the Oswaldocruzia genus.

Restenosis after hot-tip laser-balloon angioplasty: histologic evaluation of the samples removed by Simpson atherectomy

NASA Astrophysics Data System (ADS)

Barbieri, Enrico; Tanganelli, Pietro; Taddei, Giuseppe; Perbellini, Antonio; Attino, Vito; Destro, Gianni; Zardini, Piero

1991-05-01

Laser balloon angioplasty has been used in recent years to treat peripheral artery disease. Despite a primary success the technique is plagued by a high restenosis rate. Directional atherectomy was performed in a small group of patients affected by primitive stenosis or restenosis after an invasive procedure. Light microscopy, immunohistochemistry, and transmission electron microscopy have identified the cellular component of intimal hyperplasia as smooth muscle cells in an active synthetic phenotype. The arterial healing process after invasive procedures seems to develop similarly independently of the device employed.

In situ localization of nucleolin in the plant nucleolar matrix.

PubMed

Minguez, A; Moreno Diaz de la Espina, S

1996-01-10

The analysis of isolated nucleolar matrices from onion cells by light and electron microscopy, 2-D separation of proteins, and confocal microscopy has confirmed the existence of an organized nucleolar matrix with a complex protein composition to which are attached the insoluble processing complexes. In the present work, we present evidence from immunoblotting, immunofluorescence, immunogold labeling, and preferential cytochemical staining with bismuth salts that an insoluble fraction of the multifunctional protein nucleolin, is a component of the onion nucleolar matrix, and analyse its ultrastructural distribution in the described domains of the matrix.

Typification and taxonomic status re-evaluation of 15 taxon names within the species complex Cymbella affinis/tumidula/turgidula (Cymbellaceae, Bacillariophyta)

PubMed Central

da Silva, Weliton José; Jahn, Regine; Ludwig, Thelma Alvim Veiga; Hinz, Friedel; Menezes, Mariângela

2015-01-01

Abstract Specimens belonging to the Cymbella affinis / Cymbella tumidula / Cymbella turgidula species complex have many taxonomic problems, due to their high morphological variability and lack of type designations. Fifteen taxon names of this complex, distributed in five species, were re-evaluated concerning their taxonomic status, and lectotypified based on original material. In addition to light microscopy, some material was analyzed by electron microscopy. Four new combinations are proposed in order to reposition infraspecific taxa. PMID:26312038

A new species of Dianthus (Caryophyllaceae) from Antalya, South Anatolia, Turkey

PubMed Central

Deniz, İsmail Gökhan; Aykurt, Candan; Genç, İlker; Aksoy, Ahmet

2016-01-01

Abstract Dianthus multiflorus from Gazipaşa (Antalya), south Anatolia (Turkey), is described as a new annual species with verrucose calyx. The morphological differences from the species within the same group with Dianthus multiflorus, which are Dianthus aydogdui, Dianthus cyri and Dianthus tripunctatus, are discussed. The International Union for Conservation of Nature (IUCN) threat category and observations on the ecology of the populations are noted. The karyology and seed micromorphology of Dianthus multiflorus and Dianthus tripunctatus were examined by light microscopy and scanning electron microscopy. PMID:27489473

Scaffolded DNA origami of a DNA tetrahedron molecular container.

PubMed

Ke, Yonggang; Sharma, Jaswinder; Liu, Minghui; Jahn, Kasper; Liu, Yan; Yan, Hao

2009-06-01

We describe a strategy of scaffolded DNA origami to design and construct 3D molecular cages of tetrahedron geometry with inside volume closed by triangular faces. Each edge of the triangular face is approximately 54 nm in dimension. The estimated total external volume and the internal cavity of the triangular pyramid are about 1.8 x 10(-23) and 1.5 x 10(-23) m(3), respectively. Correct formation of the tetrahedron DNA cage was verified by gel electrophoresis, atomic force microscopy, transmission electron microscopy, and dynamic light scattering techniques.

[Could isolated mesangial deposits of C3 be responsible of glomerular hematuric nephropathies (author's transl)].

PubMed

Saint-Andre, J P; Touzard, D; Houssin, A; Simard, C

1982-01-01

This communication presents three cases of prolonged macroscopic hematuria in young subjects. Complementary explorations eliminated urologic or vascular causes. Renal biopsies showed minimal glomerular lesions with light microscopy, normal basement membranes in electron microscopy and mesangial deposits of C3 and properdine in immunofluorescence. Although the mesangial deposits of C3 lack specificity and the number of observations is small, it appears useful to report such cases so as to indicate their frequency and perhaps their autonomy, in glomerular hematuric nephropathies.

Palladium-doped-ZrO2-multiwalled carbon nanotubes nanocomposite: an advanced photocatalyst for water treatment

NASA Astrophysics Data System (ADS)

Anku, William Wilson; Oppong, Samuel Osei-Bonsu; Shukla, Sudheesh Kumar; Agorku, Eric Selorm; Govender, Poomani Penny

2016-06-01

The photocatalytic degradation of organic pollutants from water using palladium-doped-zirconium oxide-multiwalled carbon nanotubes (Pd-ZrO2-MWCNTs) nanocomposites is presented. A series of Pd doped-ZrO2-MWCNTs nanocomposites with varying percentage compositions of Pd were prepared by the homogenous co-precipitation method. The photocatalytic applicability of the materials was investigated by the degradation of acid blue 40 dye in water under simulated solar light. The optical, morphological and structural properties of the nanocomposites were evaluated using X-ray powder diffraction, Fourier transformer infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, BET surface area analysis and (UV-Vis) spectroscopy. The Pd-ZrO2-MWCNTs nanocomposites showed enhanced photocatalytic activity toward the degradation of the acid blue 40 dye under visible light compared with bare ZrO2 and ZrO2-MWCNTs alone. The remarkable photocatalytic activity of Pd-ZrO2-MWCNTs nanocomposites in the visible light makes it an ideal photocatalyst for the removal of organic pollutants in water. The 0.5 % Pd-ZrO2-MWCNT was the most efficient photocatalyst with 98 % degradation after 3 h with corresponding K a and band gap values of 16.8 × 10-3 m-1 and 2.79 eV, respectively.

Quantum coherent optical phase modulation in an ultrafast transmission electron microscope.

PubMed

Feist, Armin; Echternkamp, Katharina E; Schauss, Jakob; Yalunin, Sergey V; Schäfer, Sascha; Ropers, Claus

2015-05-14

Coherent manipulation of quantum systems with light is expected to be a cornerstone of future information and communication technology, including quantum computation and cryptography. The transfer of an optical phase onto a quantum wavefunction is a defining aspect of coherent interactions and forms the basis of quantum state preparation, synchronization and metrology. Light-phase-modulated electron states near atoms and molecules are essential for the techniques of attosecond science, including the generation of extreme-ultraviolet pulses and orbital tomography. In contrast, the quantum-coherent phase-modulation of energetic free-electron beams has not been demonstrated, although it promises direct access to ultrafast imaging and spectroscopy with tailored electron pulses on the attosecond scale. Here we demonstrate the coherent quantum state manipulation of free-electron populations in an electron microscope beam. We employ the interaction of ultrashort electron pulses with optical near-fields to induce Rabi oscillations in the populations of electron momentum states, observed as a function of the optical driving field. Excellent agreement with the scaling of an equal-Rabi multilevel quantum ladder is obtained, representing the observation of a light-driven 'quantum walk' coherently reshaping electron density in momentum space. We note that, after the interaction, the optically generated superposition of momentum states evolves into a train of attosecond electron pulses. Our results reveal the potential of quantum control for the precision structuring of electron densities, with possible applications ranging from ultrafast electron spectroscopy and microscopy to accelerator science and free-electron lasers.

Quantum coherent optical phase modulation in an ultrafast transmission electron microscope

NASA Astrophysics Data System (ADS)

Feist, Armin; Echternkamp, Katharina E.; Schauss, Jakob; Yalunin, Sergey V.; Schäfer, Sascha; Ropers, Claus

2015-05-01

Coherent manipulation of quantum systems with light is expected to be a cornerstone of future information and communication technology, including quantum computation and cryptography. The transfer of an optical phase onto a quantum wavefunction is a defining aspect of coherent interactions and forms the basis of quantum state preparation, synchronization and metrology. Light-phase-modulated electron states near atoms and molecules are essential for the techniques of attosecond science, including the generation of extreme-ultraviolet pulses and orbital tomography. In contrast, the quantum-coherent phase-modulation of energetic free-electron beams has not been demonstrated, although it promises direct access to ultrafast imaging and spectroscopy with tailored electron pulses on the attosecond scale. Here we demonstrate the coherent quantum state manipulation of free-electron populations in an electron microscope beam. We employ the interaction of ultrashort electron pulses with optical near-fields to induce Rabi oscillations in the populations of electron momentum states, observed as a function of the optical driving field. Excellent agreement with the scaling of an equal-Rabi multilevel quantum ladder is obtained, representing the observation of a light-driven `quantum walk' coherently reshaping electron density in momentum space. We note that, after the interaction, the optically generated superposition of momentum states evolves into a train of attosecond electron pulses. Our results reveal the potential of quantum control for the precision structuring of electron densities, with possible applications ranging from ultrafast electron spectroscopy and microscopy to accelerator science and free-electron lasers.

Dynamic light scattering study on vesicles of Netaine-Cholesterol system

NASA Astrophysics Data System (ADS)

Alenaizi, R.; Radiman, S.; Mohamed, F.; Rahman, I. Abdul

2014-09-01

The morphology of vesicles system with defined particle size and shape is one of interest in our technical applications. Here we have used dynamic light scattering technique and transmission electron microscopy for structural characterization of N-dimethylglycine Betaine with 5-cholesten-3β-ol vesicles in aqueous solutions. An isotropic one phase region is found in the very diluted regions depending on Betaine/Cholesterol ratio. The isotropic region was stable for more than 3 months at room temperature, with monodispersed unilamellar vesicles ˜ 300nm.

Facile preparation of optically transparent and hydrophobic cellulose nanofibril composite films

Treesearch

Yan Qing; Zhiyong Cai; Yiqiang Wu; Chunhua Yao; Qinglin Wu; Xianjun Li

2015-01-01

Cellulose nanofibril (CNF) and epoxy nanocomposites with high visible light transmittance and low watersensitivity were manufactured by laminating thin layers of epoxy resin onto CNF films prepared through,pressurized filtration in combination with oven drying. Scanning Electron Microscopy (SEM) studiessuggest that the resin component bonded to the CNF substrate well....

Trachymolgus purpureus sp. nov., an armored snout mite (Acari: Bdellidae) from the Ozark highlands: morphology, development, and key to Trachymolgus Berlese

USDA-ARS?s Scientific Manuscript database

Trachymolgus purpureus Fisher & Dowling sp. nov. is described from the Ozark highlands of North America. A diversity of imaging techniques are used to illustrate the species including field emission low-temperature scanning electron microscopy (FE-LTSEM), stereomicrography, compound light micrograph...

Characterization of Peronospora belbahrii on basil under light and scanning electron microscopy

USDA-ARS?s Scientific Manuscript database

Basil (Ocimum spp.) downy mildew caused by Peronsoora belbahrii is a major yield-limiting disease of sweet basil (O. basilicum) production worldwide. In this study, sweet basil was grown in a soilless potting mix in plant growth chambers and inoculated with sporangia of P. belbahrii harvested from p...

Microwave-assisted hydrothermal synthesis of marigold-like ZnIn2S4 microspheres and their visible light photocatalytic activity

NASA Astrophysics Data System (ADS)

Chen, Zhixin; Li, Danzhen; Xiao, Guangcan; He, Yunhui; Xu, Yi-Jun

2012-02-01

Marigold-like ZnIn2S4 microspheres were synthesized by a microwave-assisted hydrothermal method with the temperature ranging from 80 to 195 °C. X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen sorption analysis, UV-visible spectroscopy, scanning electron microscopy and transmission electron microscopy were used to characterize the products. It was found that the crystallographic structure and optical property of the products synthesized at different temperatures were almost the same. The degradation of methyl orange (MO) under the visible light irradiation has been used as a probe reaction to investigate the photocatalytic activity of as-prepared ZnIn2S4, which shows that the ZnIn2S4 sample synthesized at 195 °C shows the best photocatalytic activity for MO degradation. In addition, the photocatalytic activities of all the samples prepared by the microwave-assisted hydrothermal method are better than those prepared by a normal hydrothermal method, which could be attributed to the formation of more defect sites during the microwave-assisted hydrothermal treatment.

THE FINE STRUCTURE OF THE NUCLEOLUS DURING MITOSIS IN THE GRASSHOPPER NEUROBLAST CELL

PubMed Central

Stevens, Barbara J.

1965-01-01

The behavior of the nucleolus during mitosis was studied by electron microscopy in neuroblast cells of the grasshopper embryo, Chortophaga viridifasciata. Living neuroblast cells were observed in the light microscope, and their mitotic stages were identified and recorded. The cells were fixed and embedded; alternate thick and thin sections were made for light and electron microscopy. The interphase nucleolus consists of two fine structural components arranged in separate zones. Concentrations of 150 A granules form a dense peripheral zone, while the central regions are composed of a homogeneous background substance. Observations show that nucleolar dissolution in prophase occurs in two steps with a preliminary loss of the background substance followed by a dispersal of the granules. Nucleolar material reappears at anaphase as small clumps or layers at the chromosome surfaces. These later form into definite bodies, which disappear as the nucleolus grows in telophase. Evidence suggests both a collecting and a synthesizing role for the nucleolus-associated chromatin. The final, mature nucleolar form is produced by a rearrangement of the fine structural components and an increase in their mass. PMID:14326121

Preparation high photocatalytic activity of CdS/halloysite nanotubes (HNTs) nanocomposites with hydrothermal method

NASA Astrophysics Data System (ADS)

Xing, Weinan; Ni, Liang; Huo, Pengwei; Lu, Ziyang; Liu, Xinlin; Luo, Yingying; Yan, Yongsheng

2012-10-01

A novel nanocatalyst CdS/halloysite nanotubes (HNTs) was synthesized by hydrothermal method with direct growth of CdS nanoparticles on the surface of HNTs. The as-prepared photocatalysts had been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis DRS), Fourier transform infrared (FT-IR) and the thermo gravimetric analysis (TGA). The photocatalytic activity of the sample was evaluated by the degradation of tetracycline (TC) under visible light irradiation. Benefit from the excellent properties of CdS and HNTs, the photocatalyst exhibited good photocatalytic activity and stability. In order to find out the optimum synthesis condition to obtain the best photocatalytic activity, a series of experiments were performed with different CdS loading capacity, different sources of sulfide and different hydrothermal temperatures, etc. The best photodegradation rate could reach 93% in 60 min under visible light irradiation. Therefore, the combination of CdS nanoparticles with HNTs endowed this material with a potential use in environmental treatments in industries.

Anabolic androgenic steroids reverse the beneficial effect of exercise on tendon biomechanics: an experimental study.

PubMed

Tsitsilonis, Serafim; Chatzistergos, Panayiotis E; Panayiotis, Chatzistergos E; Mitousoudis, Athanasios S; Athanasios, Mitousoudis S; Kourkoulis, Stavros K; Stavros, Kourkoulis K; Vlachos, Ioannis S; Ioannis, Vlachos S; Agrogiannis, George; George, Agrogiannis; Fasseas, Konstantinos; Konstantinos, Fasseas; Perrea, Despina N; Despina, Perrea N; Zoubos, Aristides B; Aristides, Zoubos B

2014-06-01

The effect of anabolic androgenic steroids on tendons has not yet been fully elucidated. Aim of the present study was the evaluation of the impact of anabolic androgenic steroids on the biomechanical and histological characteristics of Achilles tendons. Twenty-four male Wistar rats were randomized into four groups with exercise and anabolic steroids (nandrolone decanoate) serving as variables. Protocol duration was 12 weeks. Following euthanasia, tendons' biomechanical properties were tested with the use of a modified clamping configuration. Histological examination with light and electron microscopy were also performed. In the group of anabolic steroids and exercise the lowest fracture stress values were observed, while in the exercise group the highest ones. Histological examination by light and electron microscopy revealed areas of collagen dysplasia and an increased epitendon in the groups receiving anabolic steroids and exercise. These findings suggest that anabolic androgenic steroids reverse the beneficial effect of exercise, thus resulting in inferior maximal stress values. Copyright © 2013 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.

Facile one-pot synthesis of hexagons of NaSrB5O9:Tb3+ phosphor for solid-state lighting

NASA Astrophysics Data System (ADS)

Ramesh, B.; Dillip, G. R.; Deva Prasad Raju, B.; Somasundaram, K.; Prasad Peddi, Siva; de Carvalho dos Anjos, Virgilio; Joo, S. W.

2017-04-01

NaSrB5O9:Tb3+ hexagons were synthesized by a facile solid-state reaction method. The synthesized powders were structurally examined by x-ray diffraction analysis (XRD), and Rietveld refinement was performed using the XRD data and Fullprof software. Hexagon-like morphology was observed using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The elemental composition of the phosphors was investigated qualitatively by energy dispersive x-ray analysis (EDS) and quantitatively by x-ray photoelectron spectroscopy (XPS). The phosphor has a strong green emission at 545 nm under excitation of 379 nm, which is due to the 5{{\\text{D}}4}{{\\to}7}{{\\text{F}}5} transition of the Tb3+ ion. A lifetime of 3.48 ms was obtained for the phosphor. The important parameters of the light source were determined, such as the thermal quenching, critical distance, the nature of the dopant ion interaction, color coordinates, and quantum yield values. Other reported properties include the site occupancy of the dopant, surface properties, morphological properties, and optical properties.

Phenytoin accelerates tendon healing in a rat model of Achilles tendon rupture.

PubMed

Hajipour, B; Navali, A M; Mohammad, S Ali; Mousavi, G; Akbari, M Gahvechi; Miyandoab, T Maleki; Roshangar, L; Saleh, B Mohammadi; Kermani, T Asvadi; Laleh, F Moutab; Ghabili, M

2016-01-01

Tendons are vulnerable to various types of acute or chronic injures. Different methods have been investigated to achieve better healing. Phenytoin is a drug which could stimulate fibroblasts to produce collagen. This experimental study was performed to assess the effect of phenytoin on tendon healing in a rat model of tendon rupture. Thirty healthy rats were divided into 3 groups, 1) Sham group; 2) Tendon rupture; 3) Tendon rupture+phenytoin (100 mg/kg intraperitoneally) for 21 days. On 21st day after tendon injury, the rats were anesthetized and tendon tissue was sampled for studying by light and electron microscopy. Qualitative and quantitative microscopic comparisons of the repair tissues of both groups were made on the 21st day. The results obtained from light and electron microscopy studies showed that tendon tissue healing was significantly better in phenytoin group compared to the control group (p < 0.05). Systemic administration of phenytoin may have a positive effect on tendon healing by increasing fibroblast quantity, fibrillar collagen synthesis, vascularity, and suppressing inflammation (Tab. 2, Ref. 25).

Non-Metal Doped Titania Photocatalysts for the Degradation of Neonicotinoid Insecticides Under Visible Light Irradiation.

PubMed

Joseph, Amala Infant Joice; Thiripuranthagan, Sivakumar

2018-05-01

Recombination of e-/h+ pair, the major issue of any titania based photocatalytic material, is addressed here by doping non-metals such as C, N, B, F into the lattice of nano TiO2. The as-synthesised catalysts were characterized by using various instrumental techniques such as X-ray diffraction (XRD), UV-Diffuse reflectance spectroscopy (UV-DRS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Nanosize of titania was confirmed by both XRD and TEM studies. Visible light inactivity of TiO2 is overcome by C, N, B, F doped titania catalysts in the degradation of neonicotinoid type insecticides namely imidacloprid (IMI) and thiamethoxam (TMX). The degradation efficiencies of the catalysts under different irradiations namely UV, visible and solar were compared. Among the catalysts, CNBF/TiO2 degraded IMI completely at 150, 240 and 330 min whereas TMX has been degraded completely at 210, 270 and 420 min under UV, solar and visible irradiations respectively. The recyclability test of CNBF/TiO2 confirmed its stability towards photocatalytic reaction.

Pure and Mg-doped self-assembled ZnO nano-particles for the enhanced photocatalytic degradation of 4-chlorophenol.

PubMed

Selvam, N Clament Sagaya; Narayanan, S; Kennedy, L John; Vijaya, J Judith

2013-10-01

A novel self-assembled pure and Mg doped ZnO nano-particles (NPs) were successfully synthesized by a simple low temperature co-precipitation method. The prepared photocatalysts were characterized by X-ray diffraction, high resolution scanning electron microscopy, high resolution transmission electron microscopy, diffuse reflectance spectroscopy and photoluminescence (PL) spectroscopy. The results indicated that the prepared photocatalysts showed high crystallinity with a uniform size distribution of the NPs. The degradation of cholorphenols is highly mandatory in today's scenario as they are affecting the environment adversely. Thus, the photocatalytic degradation of 4-chlorophenol (4-CP), a potent endocrine disrupting chemical in aqueous medium was investigated by both pure and Mg-doped ZnO NPs under UV-light irradiation in the present study. The influence of the Mg content on the structure, morphology, PL character and photocatalytic activity of ZnO NPs were investigated systematically. Furthermore,the effect of different parameters such as 4-CP concentration, photocatalyst amount, pH and UV-light wavelength on the resulting photocatalytic activity was investigated.

Preparation of Ag/AgCl/BiMg{sub 2}VO{sub 6} composite and its visible-light photocatalytic activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Rui; Zhang, Gaoke, E-mail: gkzhang@whut.edu.cn; Liu, Jiu

2013-05-15

Graphical abstract: - Abstract: A novel composite photocatalyst Ag/AgCl/BiMg{sub 2}VO{sub 6} was synthesized by depositing Ag/AgCl nanoparticles on BiMg{sub 2}VO{sub 6} substrate via a precipitation–photoreduction method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDXA), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectrophotometer (UV–vis DRS). The photocatalyst showed high and stable photocatalytic activity for photocatalytic degradation of acid red G under visible-light irradiation (λ > 420 nm). In addition, the active ·O{sub 2}{sup −} and h{sup +}, as main reactive species, played the major roles during the reaction process.more » The high photocatalytic activity of the composite may be related to the efficient electron–hole pairs separation at the photocatalyst interfaces, as well as the surface plasmon resonance of Ag nanoparticles formed on AgCl particles in the degradation reaction.« less

A new look at lunar soil collected from the sea of tranquility during the Apollo 11 mission.

PubMed

Kiely, Carol; Greenberg, Gary; Kiely, Christopher J

2011-02-01

Complementary state-of-the-art optical, scanning electron, and X-ray microscopy techniques have been used to study the morphology of Apollo 11 lunar soil particles (10084-47). The combination of innovative lighting geometries with image processing of a through focal series of images has allowed us to obtain a unique collection of high-resolution light micrographs of these fascinating particles. Scanning electron microscopy (SEM) stereo-pair imaging has been exploited to illustrate some of the unique morphological properties of lunar regolith. In addition, for the first time, X-ray micrographs with submicron resolution have been taken of individual particles using X-ray ultramicroscopy (XuM). This SEM-based technique lends itself readily to the imaging of pores, cracks, and inclusions and allows the internal structure of an entire particle to be viewed. Rotational SEM and XuM movies have also been constructed from a series of images collected at sequential angles through 360°. These offer a new and insightful view of these complex particles providing size, shape, and spatial information on many of their internal features.

Fe2O3/ZnO/ZnFe2O4 composites for the efficient photocatalytic degradation of organic dyes under visible light

NASA Astrophysics Data System (ADS)

Li, Xiaojuan; Jin, Bo; Huang, Jingwen; Zhang, Qingchun; Peng, Rufang; Chu, Shijin

2018-06-01

In this study, novel ternary Fe2O3/ZnO/ZnFe2O4 (ZFO) composites were successfully prepared through a simple hydrothermal reaction with subsequent thermal treatment. The as-prepared products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis, Barrett-Joyner-Halenda (BJH) measurement, and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The photocatalytic degradation of rhodamine B (Rh B) under visible light irradiation indicated that the ZFO composites calcined at 500 °C has the best photocatalytic activity (the photocatalytic degradation efficiency can reach up to 95.7% within 60 min) and can maintain a stable photocatalytic degradation efficiency for at least three cycles. In addition, the photocatalytic activity of ZFO composites toward dye decomposition follows the order cationic Rh B > anionic methyl orange. Finally, using different scavengers, superoxide and hydroxyl radicals were identified as the primary active species during the degradation reaction of Rh B.

A low-cost visible light activeBiFeWO6/TiO2nanocompositewith an efficient photocatalytic and photoelectrochemical performance

NASA Astrophysics Data System (ADS)

Priya, A.; Arunachalam, Prabhakarn; Selvi, A.; Madhavan, J.; Al-Mayouf, Abdullah M.; Ghanem, Mohamed A.

2018-07-01

Herein, visible-light driven BiFeWO6/TiO2 nanocomposites photocatalysts were successfully synthesized by an incipient wet-impregnation method. The as-synthesized BiFeWO6/TiO2 nanocomposites were explored by using various techniques of X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, UV-vis diffuse reflection spectroscopy (DRS), photoluminescence (PL), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoelectrochemical (PEC) studies to investigate the material formation, surface morphology, electrochemical and optical behaviors. Furthermore, the photocatalytic efficiency of fabricated BiFeWO6/TiO2 nanocomposites was also evaluated towards the degradation of acid orange 7 (AO7). From the degradation results, it revealed that 1% BiFeWO6/TiO2 nanocomposite demonstrated superior photocatalytic performance than its comparison with pure components. This optimized 1% BiFeWO6/TiO2 nanocomposite was found to achieve complete degradation of AO7 within 60 min and also it showing a rate constant value of0.054 min-1 which is much superior to the pure TiO2. This improvement might be credited to its strong light absorption ability in a visible-light region and the low recombination rate of hole-electron pairs. Also, the BiFeWO6/TiO2 nanocomposite has an exceptional photostability and reusability character along with an excellent photo-electrochemical activity. Therefore, it can be well useful material for removing organic pollutants in the aqueous environment. Finally, a probable mechanism is suggested for the photodegradation of AO7 over as-synthesized BiFeWO6/TiO2nanocomposite material.

SPM characterization of next generation solar cells under light irradiation: Optoelectronic study from nano to macroscopic scale.

PubMed

Ishida, Nobuyuki; Fujita, Daisuke

2014-11-01

Solar cells (SCs) that contain elaborate nanostructures, such as quantum dots and quantum wells, have been rigorously investigated as a way to harvest a wide range of the solar spectrum [1]. However, the energy conversion efficiency of those SCs still remains low. For the further improvement of the device performance, a much deeper understanding of the role of nanostructures in the photovoltaic conversion process is essential to gain the effective design criteria. To achieve this, local electronic properties including electrical potential, energy states, and charge distribution around the excitation centers have to be characterized under light irradiation since they govern the behavior of excited carriers. These properties have so far been indirectly deduced from macroscopic characterization such as current-voltage (I-V) measurement; however, it is not sufficient to clarify rather complicated roles of the nanostructures [2]. Thus, a direct measurement of those properties with high spatial resolution is required to understand the detailed mechanisms of the photovoltaic conversion process. To this end, we have been developing a platform for performing scanning tunneling microscopy/spectroscopy (STM/STS), atomic force microscopy (AFM), and Kelvin probe force microscopy (KPFM) working under light irradiation conditions.Here, we outline the characterization of a multiple quantum well (QW) SC based on III-V compounds that is expected to be a potential candidate of intermediate band type SC. First, we show the electrical potential measurements along the p-i-n junction of the SC using KPFM in air. Measurements were performed in open and short circuit configurations under light irradiation conditions [Fig.1]. We demonstrate that the dependence of the open circuit voltage on the intensity of light can be successfully measured by careful interpretation of the KPFM data. Second, we introduce some examples of the atomic scale characterization of the multiple QW using ultrahigh vacuum STM including the atomic arrangement, electronic states, and band profile. Also, charge accumulation at the QW is discussed based on the topographic measurement under light irradiation.jmicro;63/suppl_1/i12/DFU042F1F1DFU042F1Fig. 1.(a) Schematic illustration of measurement system of KPFM in air. (b) Effect of light irradiation on potential profile in open circuit configuration. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Globular bodies: a primary cause of the opacity in senile and diabetic posterior cortical subcapsular cataracts?

PubMed

Creighton, M O; Trevithick, J R; Mousa, G Y; Percy, D H; McKinna, A J; Dyson, C; Maisel, H; Bradley, R

1978-07-01

We examined 9 cataracts from maturity onset diabetics and 4 senile posterior subcapsular cataracts by scanning electron microscopy, transmission electron microscopy, immunofluorescence for crystallin proteins and actin, histochemical methods and x-ray diffraction. The cataractous regions contained spherical globules up to 20 mu in diameter, often in a fibrous matrix. Some were extracellular Morgagnian globules, apparently formed by blebbing from the cell surface; others appeared to have been formed intracellularly. The area of globular degeneration was usually 300 mu deep, but had deeper fusiform extensions. Morphological changes in the cell cytoplasm varied according to their depth in the cataract. Electron microscopy showed intracellular and extracellular globules, many of them were bounded by lipid bilayer membranes. Immunofluorescent staining showed that all the globules contained gamma-crystallin; some contained alpha- and beta-crystallins and actin. All the globules contained higher concentrations of cysteine or cystine than the surrounding lens tissue but they did not react to stains for carbohydrate or calcium. X-ray diffraction studies showed that crystalline calcium salts were absent. Globules and cavities averaged 45% of the total area in cross section. Assuming an area of cataract to be 300 micron thick and that globules 1 mu in diameter scattered, while 2--20 mu in diameter reflected light, we calculated that light passing through such a thickness would be reduced by 65%. Thus the globules could account for most of the opacity of the cataractous area. Presumably the fibrous degeneration of the cells causes enough light scattering to account for the remainder of the reduction. Cataract patients complain of decreased visual acuity, a golden halo around objects, and difficulties when driving while facing oncoming traffic at night. These probably result from light scattering. In our previous experiments, globular bodies containing gamma-crystallin were found in cells grown in tissue culture, and blebs with increased acitn content similar to Morgagnian globules were formed in tissue culture by treating differentiated rat lens cells of stage 2 by cytochalasin D (which impaired microfilament function). These results suggest the possibility of simulating in tissue culture the morphological alterations seen in the cataractous cell.

Structure and function of embryonic rat retinal sheet transplants.

PubMed

Peng, Qing; Thomas, Biju B; Aramant, Robert B; Chen, Zhenhai; Sadda, Srinivas R; Seiler, Magdalene J

2007-09-01

To evaluate retinal sheet transplants in S334ter-line-3 retinal degenerate rats by comparing visual responses recorded electrophysiologically with morphology based on light and electron microscopy. S334ter-line-3 retinal degenerate rats (n = 7) received retinal sheet transplants between postnatal days 28 and 31. The donor tissue was derived from transgenic embryonic day 19 (E19) rat retinae expressing human placental alkaline phosphatase (hPAP). Fresh retinal sheets were gently transplanted into the subretinal space of the left eye with the help of a custom-made implantation tool. Selected rats (n = 5) were subjected to electrophysiologic evaluation of visual responses from the superior colliculus about 84-121 days after surgery. Transplanted eyes were processed for light microscopy (LM) and electron microscopy (EM) evaluations. All the transplanted rats that were evaluated for visual responses in the brain showed responses to very low light stimulation (-3.42 to -2.8 log cd/m(2)) of the eye in a small area of the superior colliculus corresponding with the placement of the transplant in the host retina. Histologic evaluation showed that most of the transplants contained well-laminated areas with correct polarity in the subretinal space. Inside the transplant areas, rosettes of photoreceptors with inner and outer segments were found. In the laminated areas, the outer segments of photoreceptors were facing the host retinal pigment epithelium (RPE). Immunohistochemical evaluation of hPAP donor cells revealed areas with specific staining of the transplants in the subretinal space. Electron microscopic evaluation showed a glial demarcation membrane between the host and the transplant, however, processes originating from the transplant were observed inside the host retina. Sheets of E19 rat retina transplanted into the subretinal space of S334ter-line-3 rats survived without immune rejection and continued to show visual function when tested after 3 months. Well-developed photoreceptors and many synapse types were seen within the transplants. hPAP staining showed a certain degree of integration between the host retina and the transplant suggesting that transplanted photoreceptors contributed to the restored light sensitivity.

Novel nano-OLED based probes for very high resolution optical microscopy

NASA Astrophysics Data System (ADS)

Zhao, Yiying

Near-field scanning optical microscopy (NSOM) has been applied in the study of nanomaterials, microelectronics, photonics, plasmonics, cells, and molecules. However, conventional NSOM relies on optically pumped probes, suffering low optical transmission, heating of the tip, and poor reproducibility of probe fabrication, increasing the cost, impeding usability, reducing practical imaging resolution, and limiting NSOM's utility. In this thesis, I demonstrate a novel probe based on a nanoscale, electrically pumped organic light-emitting device (OLED) formed on the tip of a low-cost, commercially available atomic force microscopy (AFM) probe. I describe the structure, fabrication, and principles of this novel probe's operation, and discuss its potential to overcome the limitations of conventional NSOM probes. The broader significance of this work in the field of organic optoelectronics is also discussed. Briefly, OLEDs consist of organic thin films sandwiched between two electrodes. Under bias, electrons and holes are injected into the organic layers, leading to radiative recombination. Depositing a small molecular OLED in vacuum onto a pyramid-tipped AFM probe results in a laminar structure that is highly curved at the tip. Simple electrical modeling predicts concentration of electric field and localized electron injection into the organic layers at the tip, improving the local charge balance in an otherwise electron-starved OLED. Utilizing an "inverted" OLED structure (i.e. cathode on the "bottom"), light emission is localized to sub-200 nm sized, green light emitting regions on probe vertices; light output power in the range of 0.1-0.5 nanowatts was observed, comparable to that of typical fiber based NSOM probes but with greater power efficiency. Massive arrays of similar sub-micron OLEDs were also fabricated by depositing onto textured silicon substrates, demonstrating the superior scalability of the probe fabrication process (e.g. relative to pulled glass fibers). The investigation of the effect of non-planar substrate geometry on charge injection, transport and recombination provides broader insights into OLEDs made on rough substrates, general understanding of OLED operation (e.g. filamentary charge conduction) and degradation, and potentially helps to improve technologically important "inverted" OLED structures.

Low vacuum scanning electron microscopy for paraffin sections utilizing the differential stainability of cells and tissues with platinum blue.

PubMed

Inaga, Sumire; Hirashima, Sayuri; Tanaka, Keiichi; Katsumoto, Tetsuo; Kameie, Toshio; Nakane, Hironobu; Naguro, Tomonori

2009-07-01

The present study introduces a novel method for the direct observation of histological paraffin sections by low vacuum scanning electron microscopy (LVSEM) with platinum blue (Pt-blue) treatment. Pt-blue was applied not only as a backscattered electron (BSE) signal enhancer but also as a histologically specific stain. In this method, paraffin sections of the rat tongue prepared for conventional light microscopy (LM) were stained on glass slides with a Pt-blue staining solution (pH 9) and observed in a LVSEM using BSE detector. Under LVSEM, overviews of whole sections as well as three-dimensional detailed observations of individual cells and tissues could be easily made at magnifications from x40 to x10,000. Each kind of cell and tissue observed in the section could be clearly distinguished due to the different yields of BSE signals, which depended on the surface structures and different affinities to Pt-blue. Thus, we roughly classified cellular and tissue components into three groups according to the staining intensity of Pt-blue observed by LM and LVSEM: 1) a strongly stained (deep blue by LM and brightest by LVSEM) group which included epithelial tissue, endothelium and mast cells; 2) a moderately stained (light blue and bright) group which included muscular tissue and nervous tissue; 3) an unstained or weakly stained (colorless and dark) group which included elastic fibers and collagen fibers. We expect that this method will prove useful for the three-dimensional direct observation of histological paraffin sections of various tissues by LVSEM with higher resolutions than LM.

Ultrastructure and Pathology of Microsporidium phytoseiuli n. sp. Infecting the Predatory Mite, Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae)

PubMed

Bjørnson; Steiner; Keddie

1996-11-01

Ultrastructure and pathology of Microsporidium phytoseiuli n. sp. infecting the predatory mite Phytoseiulus persimilis Athias-Henriot is described using light and transmission electron microscopy. Infected mites showed no gross, external symptoms. All observed stages of the parasite had unpaired nuclei. Schizonts were commonly observed within nuclei of digestive cells of the ventriculus and within the cytoplasm of cells lining the cecal wall and in muscle tissue underlying it. Sporoblasts and spores occurred in the nuclei and cytoplasm of digestive cells within the ventriculus, in cortical regions of the sub- and supraesophageal ganglia, within the cecal wall and muscle tissue, and in parenchyma cells underlying the cuticle. Mature spores were also observed in developing eggs within gravid females. These were broad- to elongate-ovoid, measured 4.33 ± 0.35 x 1.27 ± 0.15 &mgr;m (electron micrographs), 5.37 ± 0.46 x 2.22 ± 0.17 &mgr;m (fixed and stained), and 5.88 ± 0.34 x 2.22 ± 0.19 &mgr;m (fresh) and had an isolfilar polar filament coiled 12 to 15 times within the posterior two-thirds. Within cells, individual spores appeared to be in direct contact with host cytoplasm, while groups of spores were infrequently observed within interfacial envelopes. Groups of 4, 8, to more than 16 spores were observed by light microscopy, while 8 was the maximum observed by electron microscopy. No spores were observed in Tetranychus urticae, a mite used as food during this study.

Correlated light and electron microscopy observations of the uterine epithelial cell actin cytoskeleton using fluorescently labeled resin-embedded sections.

PubMed

Moore, Chad L; Cheng, Delfine; Shami, Gerald J; Murphy, Christopher R

2016-05-01

In order to perform correlative light and electron microscopy (CLEM) more precisely, we have modified existing specimen preparation protocols allowing fluorescence retention within embedded and sectioned tissue, facilitating direct observation across length scales. We detail a protocol which provides a precise correlation accuracy using accessible techniques in biological specimen preparation. By combining a pre-embedding uranyl acetate staining step with the progressive lowering of temperature (PLT) technique, a methacrylate embedded tissue specimen is ultrathin sectioned and mounted onto a TEM finder grid for immediate viewing in the confocal and electron microscope. In this study, the protocol is applied to rat uterine epithelial cells in vivo during early pregnancy. Correlative overlay data was used to track changes in filamentous actin that occurs in these cells from fertilization (Day 1) to implantation on Day 6 as part of the plasma membrane transformation, a process essential in the development of uterine receptivity in the rat. CLEM confirmed that the actin cytoskeleton is disrupted as apical microvilli are progressively lost toward implantation, and revealed the thick and continuous terminal web is replaced by a thinner and irregular actin band, with individually distinguishable filaments connecting actin meshworks which correspond with remaining plasma membrane protrusions. Copyright © 2016 Elsevier Ltd. All rights reserved.

The feasibility of using solution-processed aqueous La2O3 as effective hole injection layer in organic light-emitting diode

NASA Astrophysics Data System (ADS)

Zhang, Yan; Li, Wanshu; Zhang, Ting; Yang, Bo; Zheng, Qinghong; Xu, Jiwen; Wang, Hua; Wang, Lihui; Zhang, Xiaowen; Wei, Bin

2018-01-01

Low-cost and scalable manufacturing boosts organic electronic devices with all solution process. La2O3 powders and corresponding aqueous solutions are facilely synthesized. Atomic force microscopy and scanning electron microscopy measurements show that solution-processed La2O3 behaves superior film morphology. X-ray diffraction and X-ray photoelectron spectroscopy measurements verify crystal phase and typical La signals. In comparison with the most widely-used hole injection layers (HILs) of MoOx and poly(ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), enhanced luminous efficiency is observed in organic light-emitting diode (OLED) using solution-processed La2O3 HIL. Current-voltage, impedance-voltage and phase angle-voltage transition curves clarify that solution-processed La2O3 behaves nearly comparable hole injection capacity to MoOx and PEDOT:PSS, and favorably tailors carrier balance. Moreover, the hole injection mechanism of solution-processed La2O3 is proven to be predominantly controlled by Fowler-Nordheim tunneling process and the hole injection barrier height between ITO and NPB via La2O3 interlayer is estimated to be 0.098 eV. Our experiments provide a feasible application of La2O3 in organic electronic devices with solution process.

[Morphological structure of rat epiphysis exposed to electromagnetic radiation from communication devices].

PubMed

Yashchenko, S G; Rybalko, S Yu

Pineal gland is one of the most important components of homeostasis - the supporting system of the body. It participates in the launch of stress responses, restriction of their development, prevention of adverse effects on the body. There was proved an impact of electromagnetic radiation on the epiphysis. However, morphological changes in the epiphysis under exposure to electromagnetic radiation of modern communication devices are studied not sufficiently. For the time present the population is daily exposed to electromagnetic radiation, including local irradiation on the brain. These date determined the task of this research - the study of the structure of rat pineal gland under the exposure to electromagnetic radiation from personal computers and mobile phones. These date determined the task of this research - the study of the structure of rat pineal gland under the exposure to electromagnetic radiation from personal computers and mobile phones. Performed transmission electron microscopy revealed signs of degeneration of dark and light pinealocytes. These signs were manifested in the development of a complex of general and specific morphological changes. There was revealed the appearance of signs of aging and depletion transmission electron microscopy both in light and dark pinealocytes. These signs were manifested in the accumulation of lipofuscin granules and electron-dense "brain sand", the disappearance of nucleoli, cytoplasm vacuolization and mitochondrial cristae enlightenment.

Preparation of NiS/ZnIn2S4 as a superior photocatalyst for hydrogen evolution under visible light irradiation

PubMed Central

Wei, Liang; Chen, Yongjuan; Zhao, Jialin

2013-01-01

Summary In this study, NiS/ZnIn2S4 nanocomposites were successfully prepared via a facile two-step hydrothermal process. The as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). Their photocatalytic performance for hydrogen evolution under visible light irradiation was also investigated. It was found that the photocatalytic hydrogen evolution activity over hexagonal ZnIn2S4 can be significantly increased by loading NiS as a co-catalyst. The formation of a good junction between ZnIn2S4 and NiS via the two step hydrothermal processes is beneficial for the directional migration of the photo-excited electrons from ZnIn2S4 to NiS. The highest photocatalytic hydrogen evolution rate (104.7 μmol/h), which is even higher than that over Pt/ZnIn2S4 nanocomposite (77.8 μmol/h), was observed over an optimum NiS loading amount of 0.5 wt %. This work demonstrates a high potential of the developing of environmental friendly, cheap noble-metal-free co-catalyst for semiconductor-based photocatalytic hydrogen evolution. PMID:24455453

3D nanospherical CdxZn1-xS/reduced graphene oxide composites with superior photocatalytic activity and photocorrosion resistance

NASA Astrophysics Data System (ADS)

Huang, Meina; Yu, Jianhua; Deng, Changshun; Huang, Yingheng; Fan, Minguang; Li, Bin; Tong, Zhangfa; Zhang, Feiyue; Dong, Lihui

2016-03-01

Herein, a series of CdxZn1-xS and sulfide/graphene photocatalysts with 3D nanospherical framework have been successfully fabricated by one-pot solvothermal method for the first time. The morphology and structure of samples were confirmed by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray (EDX) spectrometry, N2 adsorption, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). The as-prepared samples exhibit excellent photocatalytic activities and photocorrosion resistance in the degradation of dyes under visible light. The Cd0.5Zn0.5S/rGO sample shows the most efficient in the photodegradation of methyl orange (MO). It takes about 30 min for degradation completely. The enhanced photocatalytic activity is mainly attributed to the slow photon enhancement of the 3D structure, and the heterojunction between the 3D nanospherical Cd0.5Zn0.5S solid solutions and a high quality 2D rGO support, which can greatly promote the separation of light-induced electrons and holes. Moreover, the large SBET and extended light absorption range also play an important role for improving the photocatalytic activity. The high photocatalytic stability is due to the successful inhibition of the photocorrosion of Cd0.5Zn0.5S/rGO by forming heterojunction between CdS and ZnS, and transferring the photogenerated electrons of Cd0.5Zn0.5S to rGO. The present work can provide rational design of graphene-based photocatalysts with large contact interface and strong interaction between the composites for other application.

ELECTRON MICROSCOPE AND X-RAY DIFFRACTION STUDIES ON A HOMOLOGOUS SERIES OF SATURATED PHOSPHATIDYLCHOLINES.

PubMed

ELBERS, P F; VERVERGAERT, P H

1965-05-01

Three homologous saturated phosphatidylcholines were studied by electron microscopy after tricomplex fixation. The results are compared with those obtained by x-ray diffraction analysis of the same and some other homologous compounds, in the dry crystalline state and after tricomplex fixation. By electron microscopy alternating dark and light bands are observed which are likely to correspond to phosphatide double layers. X-Ray diffraction reveals the presence of lamellar structures of regular spacing. The layer spacings obtained by both methods are in good agreement. From the electron micrographs the width of the polar parts of the double layers can be derived directly. The width of the carboxylglycerylphosphorylcholine moiety of the layers is found by extrapolating the x-ray diffraction data to zero chain length of the fatty acids. When from this width the contribution of the carboxylglyceryl part of the molecules is subtracted, again we find good agreement with the electron microscope measurements. An attempt has been made to account for the different layer spacings measured in terms of orientation of the molecules within the double layers.

Iodine Vapor Staining for Atomic Number Contrast in Backscattered Electron and X-ray Imaging

PubMed Central

Boyde, Alan; Mccorkell, Fergus A; Taylor, Graham K; Bomphrey, Richard J; Doube, Michael

2014-01-01

Iodine imparts strong contrast to objects imaged with electrons and X-rays due to its high atomic number (53), and is widely used in liquid form as a microscopic stain and clinical contrast agent. We have developed a simple technique which exploits elemental iodine's sublimation-deposition state-change equilibrium to vapor stain specimens with iodine gas. Specimens are enclosed in a gas-tight container along with a small mass of solid I2. The bottle is left at ambient laboratory conditions while staining proceeds until empirically determined completion (typically days to weeks). We demonstrate the utility of iodine vapor staining by applying it to resin-embedded tissue blocks and whole locusts and imaging them with backscattered electron scanning electron microscopy (BSE SEM) or X-ray microtomography (XMT). Contrast is comparable to that achieved with liquid staining but without the consequent tissue shrinkage, stain pooling, or uneven coverage artefacts associated with immersing the specimen in iodine solutions. Unmineralized tissue histology can be read in BSE SEM images with good discrimination between tissue components. Organs within the locust head are readily distinguished in XMT images with particularly useful contrast in the chitin exoskeleton, muscle and nerves. Here, we have used iodine vapor staining for two imaging modalities in frequent use in our laboratories and on the specimen types with which we work. It is likely to be equally convenient for a wide range of specimens, and for other modalities which generate contrast from electron- and photon-sample interactions, such as transmission electron microscopy and light microscopy. Microsc. Res. Tech. 77:1044–1051, 2014. © 2014 The Authors. Microscopy Research Technique published by Wiley Periodocals, Inc. PMID:25219801

Quantitative Near-field Microscopy of Heterogeneous and Correlated Electron Oxides

NASA Astrophysics Data System (ADS)

McLeod, Alexander Swinton

Scanning near-field optical microscopy (SNOM) is a novel scanning probe microscopy technique capable of circumventing the conventional diffraction limit of light, affording unparalleled optical resolution (down to 10 nanometers) even for radiation in the infrared and terahertz energy regimes, with light wavelengths exceeding 10 micrometers. However, although this technique has been developed and employed for more than a decade to a qualitatively impressive effect, researchers have lacked a practically quantitative grasp of its capabilities, and its application scope has so far remained restricted by implementations limited to ambient atmospheric conditions. The two-fold objective of this dissertation work has been to address both these shortcomings. The first half of the dissertation presents a realistic, semi-analytic, and benchmarked theoretical description of probe-sample near-field interactions that form the basis of SNOM. Owing its name to the efficient nano-focusing of light at a sharp metallic apex, the "lightning rod model" of probe-sample near-field interactions is mathematically developed from a flexible and realistic scattering formalism. Powerful and practical applications are demonstrated through the accurate prediction of spectroscopic near-field optical contrasts, as well as the "inversion" of these spectroscopic contrasts into a quantitative description of material optical properties. Thus enabled, this thesis work proceeds to present quantitative applications of infrared near-field spectroscopy to investigate nano-resolved chemical compositions in a diverse host of samples, including technologically relevant lithium ion battery materials, astrophysical planetary materials, and invaluable returned extraterrestrial samples. The second half of the dissertation presents the design, construction, and demonstration of a sophisticated low-temperature scanning near-field infrared microscope. This instrument operates in an ultra-high vacuum environment suitable for the investigation of nano-scale physics in correlated electron matter at cryogenic temperatures, thus vastly expanding the scope of applications for infrared SNOM. Performance of the microscope is demonstrated through quanttiative exploration of the canonical insulator-metal transition occuring in the correlated electron insulator V2O3. The methodology established for this investigation provides a model for ongoing and future nano-optical studies of phase transitions and phase coexistence in correlated electron oxides.

Nanoscale surface characterization using laser interference microscopy

NASA Astrophysics Data System (ADS)

Ignatyev, Pavel S.; Skrynnik, Andrey A.; Melnik, Yury A.

2018-03-01

Nanoscale surface characterization is one of the most significant parts of modern materials development and application. The modern microscopes are expensive and complicated tools, and its use for industrial tasks is limited due to laborious sample preparation, measurement procedures, and low operation speed. The laser modulation interference microscopy method (MIM) for real-time quantitative and qualitative analysis of glass, metals, ceramics, and various coatings has a spatial resolution of 0.1 nm for vertical and up to 100 nm for lateral. It is proposed as an alternative to traditional scanning electron microscopy (SEM) and atomic force microscopy (AFM) methods. It is demonstrated that in the cases of roughness metrology for super smooth (Ra >1 nm) surfaces the application of a laser interference microscopy techniques is more optimal than conventional SEM and AFM. The comparison of semiconductor test structure for lateral dimensions measurements obtained with SEM and AFM and white light interferometer also demonstrates the advantages of MIM technique.

Synthesis and photocatalytic properties of TiO{sub 2} nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xia, X.H.; Liang, Y.; Wang, Z.

2008-08-04

TiO{sub 2} particles, rods, flowers and sheets were prepared by hydrothermal method via adjusting the temperature, the pressure and the concentration of TiCl{sub 4}. The as-prepared TiO{sub 2} powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra and N{sub 2} adsorption-desorption measurements. It was found that pressure is the most important factor influencing the morphology of TiO{sub 2}. The photocatalytic activity of the products was evaluated by the photodegradation of aqueous brilliant red X-3B solution under UV light. Among the as-prepared nanostructures, the flower-like TiO{sub 2}more » exhibited the highest photocatalytic activity.« less

Synthesis and luminescent properties of Sr3Al2O5Cl2: Eu2+, Dy3+ rod-like nanocrystals

NASA Astrophysics Data System (ADS)

Wang, Zhengliang; Zhang, Qiuhan; Rong, Meizhu; Tan, Huiying; Wang, Qin; Zhou, Qiang; Chen, Guo

2016-08-01

White long afterglow phosphor with nano-rods, Sr3Al2O5Cl2: Eu2+, Dy3+, has been successfully synthesized by the solid state reaction. Their structure, morphology, scanning electron microscopy, luminescent properties and long afterglow properties were investigated by X-ray diffraction, transmission electron microscopy luminescence spectra and the luminescence decay curve. The obtained phosphor Sr3Al2O5Cl2: Eu2+, Dy3+ exhibits two broad emission bands, which are located at ∼445 nm and ∼590 nm, respectively. White light can be observed from this phosphor with appropriate CIE values (x = 0.357, y = 0.332). The white afterglow duration of this phosphor is about 0.5 h (>0.35 mcd/m2).

Extremely strong self-assembly of a bimetallic salen complex visualized at the single-molecule level.

PubMed

Salassa, Giovanni; Coenen, Michiel J J; Wezenberg, Sander J; Hendriksen, Bas L M; Speller, Sylvia; Elemans, Johannes A A W; Kleij, Arjan W

2012-04-25

A bis-Zn(salphen) structure shows extremely strong self-assembly both in solution as well as at the solid-liquid interface as evidenced by scanning tunneling microscopy, competitive UV-vis and fluorescence titrations, dynamic light scattering, and transmission electron microscopy. Density functional theory analysis on the Zn(2) complex rationalizes the very high stability of the self-assembled structures provoked by unusual oligomeric (Zn-O)(n) coordination motifs within the assembly. This coordination mode is strikingly different when compared with mononuclear Zn(salphen) analogues that form dimeric structures having a typical Zn(2)O(2) central unit. The high stability of the multinuclear structure therefore holds great promise for the development of stable self-assembled monolayers with potential for new opto-electronic materials.

Light-responsive micelles of spiropyran initiated hyperbranched polyglycerol for smart drug delivery.

PubMed

Son, Suhyun; Shin, Eeseul; Kim, Byeong-Su

2014-02-10

Light-responsive polymeric micelles have emerged as site-specific and time-controlled systems for advanced drug delivery. Spiropyran (SP), a well-known photochromic molecule, was used to initiate the ring-opening multibranching polymerization of glycidol to afford a series of hyperbranched polyglycerols (SP-hb-PG). The micelle assembly and disassembly were induced by an external light source owing to the reversible photoisomerization of hydrophobic SP to hydrophilic merocyanine (MC). Transmission electron microscopy, atomic force microscopy, UV/vis spectroscopy, and dynamic light scattering demonstrated the successful assembly and disassembly of SP-hb-PG micelles. In addition, the critical micelle concentration (CMC) was determined through the fluorescence analysis of pyrene to confirm the amphiphilicity of respective SP-hb-PGn (n = 15, 29, and 36) micelles, with CMC values ranging from 13 to 20 mg/L, which is correlated to the length of the polar polyglycerol backbone. Moreover, the superior biocompatibility of the prepared SP-hb-PG was evaluated using WI-38 cells and HeLa cells, suggesting the prospective applicability of the micelles in smart drug delivery systems.

Fungi and bacteria involved in desert varnish formation

NASA Technical Reports Server (NTRS)

Taylor-George, S.; Palmer, F.; Staley, J. T.; Curtiss, B.; Adams, J. B.; Borns, D. J.

1983-01-01

Desert varnish is a coating of ferromanganese oxides and clays that develops on rock surfaces in arid to semi-arid regions. Active respiration but not photosynthesis was detected on varnished rock surfaces from the Sonoran Desert. Light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations, and cultivation experiments indicate that both fungi, primarily dematiaceous hyphomycetes, and bacteria are found on and within desert varnish coatings from the arid regions studied. Some fungi grow as microcolonial fungi (MCF) on rocks, and microscopic observations suggest MCF become incorporated in the varnish coating. SEM-EDAX (energy dispersive X-ray systems) analyses indicate the MCF contain 3 of the characteristic elements of varnish: iron, aluminum, and silicon. In some locations, MCF are also enriched in manganese relative to the rock substratum. Furthermore, some of the dematiaceous hyphomycetes that have been cultivated are able to oxidize manganese under laboratory conditions. It is possible that manganese-oxidizing bacteria, which are found in varnish, also play an important role in varnish formation.

Green synthesis and characterization of alginate nanoparticles and its role as a biosorbent for Cr(VI) ions

NASA Astrophysics Data System (ADS)

Geetha, P.; Latha, M. S.; Pillai, Saumya S.; Deepa, B.; Santhosh Kumar, K.; Koshy, Mathew

2016-02-01

Green synthesis of nanoparticles has attained considerable attention in recent years because of its myriad of applications including drug delivery, tissue engineering and water purification. In the present study, alginate nanoparticles stabilized by honey were prepared by cross-linking aqueous solution of alginate with calcium ions. Honey mediated synthesis has been reported earlier for the production of metal nanoparticles. However no literature is available on the use of this technique for polymeric nanoparticles. Highly stable nanoparticles of 10-100 nm size were generated by this technique. The synthesised nanoparticles were characterized by transmission electron microscopy, scanning electron microscopy, atomic force microscopy, dynamic light scattering and Fourier transform infrared spectroscopic techniques. Potential of using these nanoparticles for heavy metal removal was studied by using Cr(VI) from aqueous solution, where a maximum removal efficiency of 93.5% was obtained. This method was also successfully employed for the production of other polymeric nanoparticles like casein, chitosan and albumin.

Correlation between molten vanadium salts and the structural degradation of HK-type steel superheater tubes

NASA Astrophysics Data System (ADS)

de Carvalho Nunes, Frederico; de Almeida, Luiz Henrique; Ribeiro, André Freitas

2006-12-01

HK steels are among the most used heat-resistant cast stainless steels, being corrosion-resistant and showing good mechanical properties at high service temperatures. These steels are widely used in reformer furnaces and as superheater tubes. During service, combustion gases leaving the burners come in contact with these tubes, resulting in corrosive attack and a large weight loss occurs due to the presence of vanadium, which forms low melting point salts, removing the protective oxide layer. In this work the external surface of a tube with dramatic wall thickness reduction was analyzed using light microscopy, scanning electron microscopy, and transmission electron microscopy. The identification of the phases was achieved by energy dispersive spectroscopy (EDS) analyses. The results showed oxides arising from the external surface. In this oxidized region vanadium compounds inside chromium carbide particles were also observed, due to inward vanadium diffusion during corrosion attack. A chemical reaction was proposed to explain the presence of vanadium in the metal microstructure.

The role of immunohistochemistry, electron microscopy, and ultrastructural cytochemistry in the diagnosis of mixed carcinoma-neuroendocrine neoplasms.

PubMed

Graham, A R; Payne, C M; Nagle, R B; Angel, E

1987-02-01

We studied four mixed carcinoma-neuroendocrine neoplasms from gastrointestinal tract and pancreas by routine light microscopy (LM), immunohistochemistry (IH), electron microscopy (EM), and ultrastructural cytochemistry (UC). By LM, the individual tumors showed fairly pure neuroendocrine (carcinoid) or epithelial (papillary) patterns, mixed neuroendocrine-carcinoma features and poorly-differentiated tumor in sheets and nests which did not lend itself to morphologic characterization. IH demonstrated mixed expression, within different areas of the same neoplasm, of epithelial antigens (keratins and carcinoembryonic antigen [CEA]) and neuroendocrine markers (neuron-specific enolase [NSE], bombesin and neurohormonal peptides). By EM, each tumor showed ultrastructural features of epithelial and neuroendocrine differentiation which varied substantially in terms of number of cells involved and their distribution; two of the neoplasms showed biphasic differentiation within single cells. The nature of the neurosecretory granules was verified with the uranaffin reaction (UR). This study illustrates the value of combining LM, IH, EM and UC for the identification of mixed carcinoma-neuroendocrine lesions.

Introduction to electron crystallography.

PubMed

Kühlbrandt, Werner

2013-01-01

From the earliest work on regular arrays in negative stain, electron crystallography has contributed greatly to our understanding of the structure and function of biological macromolecules. The development of electron cryo-microscopy (cryo-EM) then lead to the first groundbreaking atomic models of the membrane proteins bacteriorhodopsin and light harvesting complex II within lipid bilayers. Key contributions towards cryo-EM and electron crystallography methods included specimen preparation and vitrification, liquid-helium cooling, data collection, and image processing. These methods are now applied almost routinely to both membrane and soluble proteins. Here we outline the advances and the breakthroughs that paved the way towards high-resolution structures by electron crystallography, both in terms of methods development and biological milestones.

Property Characterization and Photocatalytic Activity Evaluation of BiGdO3 Nanoparticles under Visible Light Irradiation

PubMed Central

Luan, Jingfei; Shen, Yue; Zhang, Lingyan; Guo, Ningbin

2016-01-01

BiGdO3 nanoparticles were prepared by a solid-state reaction method and applied in photocatalytic degradation of dyes in this study. BiGdO3 was characterized by X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller, UV-Vis diffuse reflectance spectroscopy and transmission electron microscopy. The results showed that BiGdO3 crystallized well with the fluorite-type structure, a face-centered cubic crystal system and a space group Fm3m 225. The lattice parameter of BiGdO3 was 5.465 angstrom. The band gap of BiGdO3 was estimated to be 2.25 eV. BiGdO3 showed a strong optical absorption during the visible light region. Moreover, the photocatalytic activity of BiGdO3 was evaluated by photocatalytic degradation of direct dyes in aqueous solution under visible light irradiation. BiGdO3 demonstrated excellent photocatalytic activity in degrading Direct Orange 26 (DO-26) or Direct Red 23 (DR-23) under visible light irradiation. The photocatalytic degradation of DO-26 or DR-23 followed the first-order reaction kinetics, and the first-order rate constant was 0.0046 or 0.0023 min−1 with BiGdO3 as catalyst. The degradation intermediates of DO-26 were observed and the possible photocatalytic degradation pathway of DO-26 under visible light irradiation was provided. The effect of various operational parameters on the photocatalytic activity and the stability of BiGdO3 particles were also discussed in detail. BiGdO3/(visible light) photocatalysis system was confirmed to be suitable for textile industry wastewater treatment. PMID:27618018

Visible Light Assisted Photocatalytic Hydrogen Generation by Ta 2O 5/Bi 2O 3, TaON/Bi 2O 3, and Ta 3N 5/Bi 2O 3 Composites

DOE PAGES

Adhikari, Shiba; Hood, Zachary D.; More, Karren Leslie; ...

2015-06-15

Composites comprised of two semiconducting materials with suitable band gaps and band positions have been reported to be effective at enhancing photocatalytic activity in the visible light region of the electromagnetic spectrum. Here, we report the synthesis, complete structural and physical characterizations, and photocatalytic performance of a series of semiconducting oxide composites. UV light active tantalum oxide (Ta2O5) and visible light active tantalum oxynitride (TaON) and tantalum nitride (Ta 3N 5) were synthesized, and their composites with Bi 2O 3 were prepared in situ using benzyl alcohol as solvent. The composite prepared using equimolar amounts of Bi 2O 3 andmore » Ta 2O 5 leads to the formation of the ternary oxide, bismuth tantalate (BiTaO 4) upon calcination at 1000 °C. The composites and single phase bismuth tantalate formed were characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) surface area measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis diffuse reflectance spectroscopy, and photoluminescence. The photocatalytic activities of the catalysts were evaluated for generation of hydrogen using aqueous methanol solution under visible light irradiation (λ ≥ 420 nm). The results show that as-prepared composite photocatalysts extend the light absorption range and restrict photogenerated charge-carrier recombination, resulting in enhanced photocatalytic activity compared to individual phases. The mechanism for the enhanced photocatalytic activity for the heterostructured composites is elucidated based on observed activity, band positions calculations, and photoluminescence data.« less

Structural Analysis of Enamel in Teeth from Head-and-Neck Cancer Patients Who Underwent Radiotherapy.

PubMed

Madrid, Cristhian C; de Pauli Paglioni, Mariana; Line, Sergio R; Vasconcelos, Karina G; Brandão, Thaís Bianca; Lopes, Marcio A; Santos-Silva, Alan Roger; De Goes, Mario Fernando

2017-01-01

To analyze macroscopic, microscopic, and ultrastructural aspects of enamel from head-and-neck cancer patients submitted to radiotherapy. Twenty sound extracted permanent molars were used and divided into 2 groups. The experimental group consisted of 10 molars from head-and-neck cancer patients submitted to radiotherapy with total doses that ranged from 50 to 70 Gy. Ten molars from patients who did not receive radiotherapy were matched with experimental-group samples by anatomic tooth group and comprised the control group. To perform a macroscopic analysis, standardized photos of different enamel faces were taken with a camera. Teeth were subjected to longitudinal cuts and hand polished to a final thickness of 0.1 mm. Enamel was analyzed under polarized light microscopy, and optical retardation values of birefringence were calculated in cervical, cusp, and occlusal pit areas. Subsequently, the same enamel areas were analyzed by scanning electron microscopy. Data from optical retardation values were statistically analyzed by 2-way ANOVA and Fisher's test (α < 0.05). No macroscopic differences were observed between the irradiated and control groups. Polarized light microscopy analysis revealed that cervical enamel exhibited darker areas characterized by discrete birefringence patterns compared to the control enamel. Optical retardation values were only significantly different in the cervical enamel of the irradiated and control groups (p < 0.0001). Scanning electron microscopy analysis revealed more evident interprismatic spaces in the cervical and outer cusp enamel of irradiated samples. Head-and-neck radiotherapy reduced optical retardation values of birefringence in cervical enamel, and the interprismatic spaces became more evident. © 2017 S. Karger AG, Basel.

Correlative Instrumental Neutron Activation Analysis, Light Microscopy, Transmission Electron Microscopy, and X-ray Microanalysis for Qualitative and Quantitative Detection of Colloidal Gold Spheres in Biological Specimens

NASA Astrophysics Data System (ADS)

Hillyer, Julián F.; Albrecht, Ralph M.

1998-10-01

: Colloidal gold, conjugated to ligands or antibodies, is routinely used as a label for the detection of cell structures by light (LM) and electron microscopy (EM). To date, several methods to count the number of colloidal gold labels have been employed with limited success. Instrumental neutron activation analysis (INAA), a physical method for the analysis of the elemental composition of materials, can be used to provide a quantitative index of gold accumulation in bulk specimens. Given that gold is not naturally found in biological specimens in any substantial amount and that colloidal gold and ligand conjugates can be prepared to yield uniform bead sizes, the amount of label can be calculated in bulk biological samples by INAA. Here we describe the use of INAA, LM, transmission EM, and X-ray microanalysis (EDX) in a model to determine both distribution (localization) and amount of colloidal gold at the organ, tissue, cellular, and ultrastructural levels in whole animal systems following administration. In addition, the sensitivity for gold in biological specimens by INAA is compared with that of inductively coupled plasma mass spectrometry (ICP-MS). The correlative use of INAA, LM, TEM, and EDX can be useful, for example, in the quantitative and qualitative tracking of various labeled molecular species following administration in vivo.

Attachment reaction of rat uterine luminal epithelium. II. The effect of progesterone on the morphology of the uterine glands and the luminal epithelium of the spayed, virgin rat.

PubMed

Ljungkvist, I

1971-01-01

Ovariosalpingectomized rat uterine glands and luminal epithelium were examined by electron microscopy and in serial cross sections under light microscopy after up to 8 days of treatment with 5 mg progesterone daily. Under light microscopy, the gland lumen was narrow or absent in many epon sections, but wide in many paraffin sections, filled with toluidine blue stained secretion, and serial sections showed that the openings were closed, allowing no connection between the gland lumen and the uterus. In electron micrographs, only those glands without an opening appeared altered by progesterone. The most notable differences in the glandular epithelium were microvilli, condensed ribosome-free cytoplasm next to the lumen, numerous vesicles, sacs and dilated Golgi cisternae in the apical cytoplasm, and more giant mitrochondria in the basal cytoplasm than usually seen in controls. In the luminal epithelium, there were 3 distinct regions: the apical region had condensed cytoplasm often extruded into the lumen, with close-packed, smooth, empty vesicles; the middle region had granular endoplasmic reticulum, mitrochondria, dense bodies, multivesicular bodies, and lipid granules; the basal region contained the nucleus, granular endoplasmic reticulum, mitrochondria and dense abodies. These observations were interpreted as indicative of a transitional state from secretion to absorption, especially since without an opening, secretion would be of little significance.

Preliminary studies on LED-activated pyropheophorbide-α methyl ester killing cisplatin-resistant ovarian carcinoma cells

NASA Astrophysics Data System (ADS)

Tan, Yong; Xu, Chuan Shan; Xia, Xin Shu; Yu, He Ping; Bai, Ding Qun; He, Yong; Xu, Jing; Wang, Ping; Wang, Xin Na; Leung, Albert Wing Nang

2009-05-01

In the present study, a novel LED source was applied for activating pyropheophorbids-a methyl ester (MPPa) in cisplatin-resistant ovarian cell line COC1/DDP cells. MPPa concentration was 2 μM and light energy from 0.125-8 J/cm2. Cytotoxicity was investigated 24 h using MTT reduction assay and light microscopy after treatment. Cellular ultrastructure was observed using transmission electron microscopy (TEM) and nuclear chromatin by fluorescent microscope with Hoechst33258 staining. MTT reduction assay showed that the cytotoxicity of LED-activated MPPa in the COC1/DDP cells increased along with the light dose of LED source and LED-activated MPPa resulted in light-dependent cytotoxicity. The observations from light microscopy reinforced the above results. TEM showed that necrotic cells with the disruption of karyotheca, karyorrhexis, and karyolysis of nucleus and apoptotic cells, especially the apoptotic body, can be seen post LED-activated MPPa. Hoechst33258 staining showed that condensation of chromatin and nuclear fragmentations could be found in many treated cells and some of them formed the structure of apoptotic bodies when COC1/DDP cells were exposed to 2 μM MPPa for 20 h and then 1 J/cm2 irradiation of LED source. The findings demonstrated that the novel LED source could efficiently activated MPPa and LED-activated MPPa could significantly kill cisplatin-resistant ovarian cell line COC1/DDP cells through two major pathways including necrosis and apoptosis, suggesting that LED is a novel and efficient light source and LED-activated MPPa might be potential therapeutic modality for treating cisplatin-resistant ovarian carcinoma.

Trypanosoma janseni n. sp. (Trypanosomatida: Trypanosomatidae) isolated from Didelphis aurita (Mammalia: Didelphidae) in the Atlantic Rainforest of Rio de Janeiro, Brazil: integrative taxonomy and phylogeography within the Trypanosoma cruzi clade.

PubMed

Lopes, Camila Madeira Tavares; Menna-Barreto, Rubem Figueiredo Sadok; Pavan, Márcio Galvão; Pereira, Mirian Cláudia De Souza; Roque, André Luiz R

2018-01-01

Didelphis spp. are a South American marsupial species that are among the most ancient hosts for the Trypanosoma spp. We characterise a new species (Trypanosoma janseni n. sp.) isolated from the spleen and liver tissues of Didelphis aurita in the Atlantic Rainforest of Rio de Janeiro, Brazil. The parasites were isolated and a growth curve was performed in NNN and Schneider's media containing 10% foetal bovine serum. Parasite morphology was evaluated via light microscopy on Giemsa-stained culture smears, as well as scanning and transmission electron microscopy. Molecular taxonomy was based on a partial region (737-bp) of the small subunit (18S) ribosomal RNA gene and 708 bp of the nuclear marker, glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) genes. Maximum likelihood and Bayesian inference methods were used to perform a species coalescent analysis and to generate individual and concatenated gene trees. Divergence times among species that belong to the T. cruzi clade were also inferred. In vitro growth curves demonstrated a very short log phase, achieving a maximum growth rate at day 3 followed by a sharp decline. Only epimastigote forms were observed under light and scanning microscopy. Transmission electron microscopy analysis showed structures typical to Trypanosoma spp., except one structure that presented as single-membraned, usually grouped in stacks of three or four. Phylogeography analyses confirmed the distinct species status of T. janseni n. sp. within the T. cruzi clade. Trypanosoma janseni n. sp. clusters with T. wauwau in a well-supported clade, which is exclusive and monophyletic. The separation of the South American T. wauwau + T. janseni coincides with the separation of the Southern Super Continent. This clade is a sister group of the trypanosomes found in Australian marsupials and its discovery sheds light on the initial diversification process based on what we currently know about the T. cruzi clade.

Scanning Transmission Electron Microscopy at High Resolution

PubMed Central

Wall, J.; Langmore, J.; Isaacson, M.; Crewe, A. V.

1974-01-01

We have shown that a scanning transmission electron microscope with a high brightness field emission source is capable of obtaining better than 3 Å resolution using 30 to 40 keV electrons. Elastic dark field images of single atoms of uranium and mercury are shown which demonstrate this fact as determined by a modified Rayleigh criterion. Point-to-point micrograph resolution between 2.5 and 3.0 Å is found in dark field images of micro-crystallites of uranium and thorium compounds. Furthermore, adequate contrast is available to observe single atoms as light as silver. Images PMID:4521050

Chloride ion-driven transformation from Ag3PO4 to AgCl on the hydroxyapatite support and its dual antibacterial effect against Escherichia coli under visible light irradiation.

PubMed

Hong, Xiaoting; Li, Min; Shan, Shengdao; Hui, K S; Mo, Mingyue; Yuan, Xiaoli

2016-07-01

Visible light-driven photocatalytic inactivation of Escherichia coli was performed using hydroxyapatite-supported Ag3PO4 nanocomposites (Ag3PO4/HA). The antibacterial performance was evaluated by the methods of zone of inhibition plates and minimum inhibitory concentration test. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed to investigate the instability and transformation of the nanocomposite by comparing the crystalline, phase, and the morphology before and after exposure to Luria-Bertani culture medium under visible light irradiation. Ag3PO4 nanoparticles on the support were found to be shortly transformed into AgCl due to high chloride concentration of Luria-Bertani culture medium. The AgCl/HA nanocomposite showed both excellent intrinsic antibacterial performance contributed by the released silver ions and visible light-induced photocatalytic disinfection toward E. coli cells. This dual antibacterial function mechanism was validated by trapping the hydroxyl free radical and detecting the silver ions during the photocatalytic antibacterial process. The morphological change of E. coli cells in different reaction intervals was obtained by scanning electron microscopy (SEM) to complementally verify photocatalytic inactivation of E. coli. This work suggests that an essential comparison study is required for the antibacterial materials before and after the photocatalytic inactivation of bacterial cells using Ag3PO4 nanoparticles or Ag3PO4-related nanocomposites in mediums containing high-concentration chloride ions.

Adapalene microemulsion for transfollicular drug delivery.

PubMed

Bhatia, Gaurav; Zhou, Yingcong; Banga, Ajay K

2013-08-01

The aim of this study was to develop a microemulsion formulation of adapalene for transfollicular delivery. A pseudoternary phase diagram was developed for microemulsion consisting of oleic acid as oil phase, tween 20 as surfactant, Transcutol® as cosurfactant, and deionized water. Differential tape stripping and confocal laser scanning microscopy were performed to determine the penetration of microemulsion through hair follicles. Transmission electron microscopy, dynamic light scattering, polarizing light microscopy, and differential scanning calorimetry were performed to characterize the microstructures of microemulsion. The pH and viscosity of the microemulsions were also determined. Permeation studies were carried out in vitro on porcine ear skin over a period of 24 h using Franz diffusion cells. The drug penetration in the hair follicles increased from 0.109 ± 0.03 to 0.292 ± 0.094 μg, as the microstructure of microemulsion shifted from oil-in-water to bi-continuous, with increase in water content of microemulsion. Confocal laser scanning microscopy images suggested that hair follicles provided the path for transfollicular permeation of adapalene microemulsion. These results suggest that microemulsion penetrated through hair follicles and are promising for transfollicular drug delivery. Copyright © 2013 Wiley Periodicals, Inc.

Role of Eu{sup 2+} on the blue‐green photoluminescence of In{sub 2}O{sub 3}:Eu{sup 2+} nanocrystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Devi, Konsam Reenabati, E-mail: reena.kay14@manipuruniv.ac.in; Meetei, Sanoujam Dhiren, E-mail: sdmdhiren@gmail.com; Department of Physics, North Eastern Regional Institute of Science & Technology, Nirjuli, Itanagar 791109, Arunachal Pradesh

Blue‐green light emitting undoped and europium doped indium oxide nanocrystal were synthesized by simple precipitation method. X-ray diffraction (XRD) pattern confirmed the cubic phase of undoped and europium doped samples. Further, transmission electron microscopy (TEM), scanning electron microscopy (SEM) , energy dispersive analysis of X-rays (EDAX), Fourier transform infra-red (FT-IR), photoluminescence (PL), electron paramagnetic resonance (EPR) studies were performed to characterise the samples. PL analysis of the samples is the core of the present research. It includes excitation, emission and CIE (Commission Internationale de l’e´ clairage) studies of the samples. On doping europium to In{sub 2}O{sub 3} lattice, ln{sup 3+}more » site is substituted by Eu{sup 2+} thereby increasing the concentration of singly ionized oxygen vacancy and hence blue–green emission from the host is found to increase. Further, this increase in blue–green emission after doping may also be attributed to 4f → 5d transitions of Eu{sup 2+}. However, the blue–green PL emission is found to decrease after an optimum dopant concentration (Eu{sup 2+} = 4%) due to luminescence and size quenching. CIE co-ordinates of the samples are calculated to know colour of light emitted from the samples. It suggests that this blue–green light emitting In{sub 2}O{sub 3}: Eu{sup 2+} nanocrystals may find application in lighting such as in generation of white light. - Highlight: • XRD and TEM study confirms the synthesis of cubic doped and europium doped nanocrystals. • EPR study reveals the doped europium is in + 2 oxidation state. • Enhance PL emission intensity of host material due to increase in singly ionized oxygen vacancy and 4f–5d transitions of Eu{sup 2+} • CIE co-ordinates suggest the blue–green colour of the samples.« less

Three-dimensional bright-field scanning transmission electron microscopy elucidate novel nanostructure in microbial biofilms.

PubMed

Hickey, William J; Shetty, Ameesha R; Massey, Randall J; Toso, Daniel B; Austin, Jotham

2017-01-01

Bacterial biofilms play key roles in environmental and biomedical processes, and understanding their activities requires comprehension of their nanoarchitectural characteristics. Electron microscopy (EM) is an essential tool for nanostructural analysis, but conventional EM methods are limited in that they either provide topographical information alone, or are suitable for imaging only relatively thin (<300 nm) sample volumes. For biofilm investigations, these are significant restrictions. Understanding structural relations between cells requires imaging of a sample volume sufficiently large to encompass multiple cells and the capture of both external and internal details of cell structure. An emerging EM technique with such capabilities is bright-field scanning transmission electron microscopy (BF-STEM) and in the present report BF-STEM was coupled with tomography to elucidate nanostructure in biofilms formed by the polycyclic aromatic hydrocarbon-degrading soil bacterium, Delftia acidovorans Cs1-4. Dual-axis BF-STEM enabled high-resolution 3-D tomographic recontructions (6-10 nm) visualization of thick (1250 and 1500 nm) sections. The 3-D data revealed that novel extracellular structures, termed nanopods, were polymorphic and formed complex networks within cell clusters. BF-STEM tomography enabled visualization of conduits formed by nanopods that could enable intercellular movement of outer membrane vesicles, and thereby enable direct communication between cells. This report is the first to document application of dual-axis BF-STEM tomography to obtain high-resolution 3-D images of novel nanostructures in bacterial biofilms. Future work with dual-axis BF-STEM tomography combined with correlative light electron microscopy may provide deeper insights into physiological functions associated with nanopods as well as other nanostructures. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.