SEM Analysis of Surface Impact on Biofilm Antibiotic Treatment.

PubMed

Gomes, Luciana Calheiros; Mergulhão, Filipe José

2017-01-01

The aim of this work was to use scanning electron microscopy (SEM) to investigate the effect of ampicillin treatment on Escherichia coli biofilms formed on two surface materials with different properties, silicone (SIL) and glass (GLA). Epifluorescence microscopy (EM) was initially used to assess biofilm formation and killing efficiency on both surfaces. This technique showed that higher bacterial colonization was obtained in the hydrophobic SIL than in the hydrophilic GLA. It has also shown that higher biofilm inactivation was attained for GLA after the antibiotic treatment (7-log reduction versus 1-log reduction for SIL). Due to its high resolution and magnification, SEM enabled a more detailed analysis of the antibiotic effect on biofilm cells, complementing the killing efficiency information obtained by EM. SEM micrographs revealed that ampicillin-treated cells have an elongated form when compared to untreated cells. Additionally, it has shown that different materials induced different levels of elongation on cells exposed to antibiotic. Biofilms formed on GLA showed a 37% higher elongation than those formed on SIL. Importantly, cell elongation was related to viability since ampicillin had a higher bactericidal effect on GLA-formed biofilms. These findings raise the possibility of using SEM for understanding the efficacy of antimicrobial treatments by observation of biofilm morphology.

Generating 3D and 3D-like animations of strongly uneven surface microareas of bloodstains from small series of partially out-of-focus digital SEM micrographs.

PubMed

Hortolà, Policarp

2010-01-01

When dealing with microscopic still images of some kinds of samples, the out-of-focus problem represents a particularly serious limiting factor for the subsequent generation of fully sharp 3D animations. In order to produce fully-focused 3D animations of strongly uneven surface microareas, a vertical stack of six digital secondary-electron SEM micrographs of a human bloodstain microarea was acquired. Afterwards, single combined images were generated using a macrophotography and light microscope image post-processing software. Subsequently, 3D animations of texture and topography were obtained in different formats using a combination of software tools. Finally, a 3D-like animation of a texture-topography composite was obtained in different formats using another combination of software tools. By one hand, results indicate that the use of image post-processing software not concerned primarily with electron micrographs allows to obtain, in an easy way, fully-focused images of strongly uneven surface microareas of bloodstains from small series of partially out-of-focus digital SEM micrographs. On the other hand, results also indicate that such small series of electron micrographs can be utilized for generating 3D and 3D-like animations that can subsequently be converted into different formats, by using certain user-friendly software facilities not originally designed for use in SEM, that are easily available from Internet. Although the focus of this study was on bloodstains, the methods used in it well probably are also of relevance for studying the surface microstructures of other organic or inorganic materials whose sharp displaying is difficult of obtaining from a single SEM micrograph.

An Investigation of Concrete Deterioration at South Florida Water Management District Structure S65E

DTIC Science & Technology

2014-02-01

24 Figure 19. SEM micrographs of deterioration observed on fracture surface including borehole near exposed surface and transition between...photomicrographs of repaired concrete surface. ........................................ 36 Figure A6. Supplemental photomicrographs of fractured sample...38 Figure B1. Supplemental SEM micrographs of inner non-deteriorated concrete fracture surface

Conductive Polymer Blends

DTIC Science & Technology

1988-04-26

FIGURES Figure 1. Schematic of the suspension copolymerization approach ................ 8 Figure 2. SEM micrograph of fracture surface near molded...micrograph of fracture surface near molded edge of sample 1430-58b.............................................................. 18 Figure 12. SEM... caprolactam . The caprolactam (11.3 g) was placed in a large tube equipped with a nitrogen inlet, and heated under nitrogen to 80*C, whereupon

Silver nanoparticle production by Rhizopus stolonifer and its antibacterial activity against extended spectrum {beta}-lactamase producing (ESBL) strains of Enterobacteriaceae

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

Banu, Afreen; Rathod, Vandana, E-mail: drvandanarathod@rediffmail.com; Ranganath, E.

Highlights: {yields} Silver nanoparticle production by using Rhizopus stolonifer. {yields} Antibacterial activity of silver nanoparticles against extended spectrum {beta}-lactamase producing (ESBL) strains of Enterobacteriaceae. {yields} Synergistic effect of antibiotics with silver nanoparticles towards ESBL-strains. {yields} Characterization of silver nanoparticles made by UV-vis spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) spectroscopy, atomic force microscopy (AFM). -- Abstract: This report focuses on the synthesis of silver nanoparticles using the fungus, Rhizopus stolonifer and its antimicrobial activity. Research in nanotechnology highlights the possibility of green chemistry pathways to produce technologically important nanomaterials. Characterization of newly synthesized silvermore » nanoparticles was made by UV-visible absorption spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy and atomic force microscope (AFM). TEM micrograph revealed the formation of spherical nanoparticles with size ranging between 3 and 20 nm. The biosynthesized silver nanoparticles (AgNPs) showed excellent antibacterial activity against ESBL-strains which includes E. coli, Proteus. sp. and Klebsiella sp.« less

A study of the UV and VUV degradation of FEP

NASA Technical Reports Server (NTRS)

George, Graeme A.; Hill, David J. T.; Odonnell, James H.; Pomery, Peter J.; Rasoul, Firas A.

1993-01-01

UV and VUV degradation of fluorinated ethylene propylene (FEP) copolymer was studied using electron spin resonance (ESR) spectroscopy, x-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The ESR study revealed the formation of a terminal polymer radical. The stability of this radical was investigated under different environments. An XPS study of FEP film exposed to VUV and atomic oxygen showed that oxidation takes place on the polymer surface. The study revealed also that the percentage of CF2 in the polymer surface decreased with exposure time and the percentage of CF, CF3, and carbon attached to oxygen increased. SEM micrographs of FEP film exposed to VUV and atomic oxygen identified a rough surface with undulations similar to sand dunes.

Microbial structures in an Alpine Thermal Spring - Microscopic techniques for the examination of Biofilms in a Subsurface Environment

NASA Astrophysics Data System (ADS)

Dornmayr-Pfaffenhuemer, Marion; Pierson, Elisabeth; Janssen, Geert-Jan; Stan-Lotter, Helga

2010-05-01

The research into extreme environments hast important implications for biology and other sciences. Many of the organisms found there provide insights into the history of Earth. Life exists in all niches where water is present in liquid form. Isolated environments such as caves and other subsurface locations are of interest for geomicrobiological studies. And because of their "extra-terrestrial" conditions such as darkness and mostly extreme physicochemical state they are also of astrobiological interest. The slightly radioactive thermal spring at Bad Gastein (Austria) was therefore examined for the occurrence of subsurface microbial communities. The surfaces of the submerged rocks in this warm spring were overgrown by microbial mats. Scanning electron microscopy (SEM) performed by the late Dr. Wolfgang Heinen revealed an interesting morphological diversity in biofilms found in this environment (1, 2). Molecular analysis of the community structure of the radioactive subsurface thermal spring was performed by Weidler et al. (3). The growth of these mats was simulated using sterile glass slides which were exposed to the water stream of the spring. Those mats were analysed microscopically. Staining, using fluorescent dyes such as 4',6-Diamidino-2-phenylindol (DAPI), gave an overview of the microbial diversity of these biofilms. Additional SEM samples were prepared using different fixation protocols. Scanning confocal laser microscopy (SCLM) allowed a three dimensional view of the analysed biofilms. This work presents some electron micrographs of Dr. Heinen and additionally new microscopic studies of the biofilms formed on the glass slides. The appearances of the new SEM micrographs were compared to those of Dr. Heinen that were done several years ago. The morphology and small-scale distribution in the microbial mat was analyzed by fluorescence microscopy. The examination of natural biomats and biofilms grown on glass slides using several microscopical techniques suggest that the thermal springs in the Central Alps near Bad Gastein represent a novel and unique habitat for microbial life. Results obtained during these studies revealed reproducibility of Dr. Heinen's micrographs. Hollow reticulated filaments and flat ribbons with parallel hexagonal chambers (web-structures) were found repeatedly. Given the chance that subsurface environments represent a potent opportunity to detect life on planetary bodies it is of big interest to search for representative biosignatures found on earth today. References: 1. Lauwers A. M. & Heinen W. (1985) Mikroskopie (Wien) 42, 94-101. 2. Heinen W. & Lauwers A. M. (1985) Mikroskopie (Wien) 42, 124-134. 3. Weidler G. W., Dornmayr-Pfaffenhuemer M., Gerbl F. W., Heinen W., Stan-Lotter H. (2007) AEM 73, 259-270.

Synthesis of graphene oxide and reduced graphene oxide by needle platy natural vein graphite

NASA Astrophysics Data System (ADS)

Rathnayake, R. M. N. M.; Wijayasinghe, H. W. M. A. C.; Pitawala, H. M. T. G. A.; Yoshimura, Masamichi; Huang, Hsin-Hui

2017-01-01

Among natural graphite varieties, needle platy vein graphite (NPG) has very high purity. Therefore, it is readily used to prepare graphene oxide (GO) and reduced graphene oxide (rGO). In this study, GO and rGO were prepared using chemical oxidation and reduction process, respectively. The synthesized materials were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. XRD studies confirmed the increase of the interlayer spacing of GO and rGO in between 3.35 to 8.66 A°. AFM studies showed the layer height of rGO to be 1.05 nm after the reduction process. TEM micrographs clearly illustrated that the prepared GO has more than 25 layers, while the rGO has only less than 15 layers. Furthermore, the effect of chemical oxidation and reduction processes on surface morphology of graphite were clearly observed in FESEM micrographs. The calculated RO/C of GO and rGO using XPS analysis are 5.37% and 1.77%, respectively. The present study revealed the successful and cost effective nature of the chemical oxidation, and the reduction processes for the production of GO and rGO out of natural vein graphite.

Use of fluorescence and scanning electron microscopy as tools in teaching biology

NASA Astrophysics Data System (ADS)

Ghosh, Nabarun; Silva, Jessica; Vazquez, Aracely; Das, A. B.; Smith, Don W.

2011-06-01

Recent nationwide surveys reveal significant decline in students' interest in Math and Sciences. The objective of this project was to inspire young minds in using various techniques involved in Sciences including Scanning Electron Microscopy. We used Scanning Electron Microscope in demonstrating various types of Biological samples. An SEM Tabletop model in the past decade has revolutionized the use of Scanning Electron Microscopes. Using SEM Tabletop model TM 1000 we studied biological specimens of fungal spores, pollen grains, diatoms, plant fibers, dust mites, insect parts and leaf surfaces. We also used fluorescence microscopy to view, to record and analyze various specimens with an Olympus BX40 microscope equipped with FITC and TRITC fluorescent filters, a mercury lamp source, DP-70 digital camera with Image Pro 6.0 software. Micrographs were captured using bright field microscopy, the fluoresceinisothiocyanate (FITC) filter, and the tetramethylrhodamine (TRITC) filter settings at 40X. A high pressure mercury lamp or UV source was used to excite the storage molecules or proteins which exhibited autofluorescence. We used fluorescent microscopy to confirm the localization of sugar beet viruses in plant organs by viewing the vascular bundles in the thin sections of the leaves and other tissues. We worked with the REU summer students on sample preparation and observation on various samples utilizing the SEM. Critical Point Drying (CPD) and metal coating with the sputter coater was followed before observing some cultured specimen and the samples that were soft in textures with high water content. SEM Top allowed investigating the detailed morphological features that can be used for classroom teaching. Undergraduate and graduate researchers studied biological samples of Arthropods, pollen grains and teeth collected from four species of snakes using SEM. This project inspired the research students to pursue their career in higher studies in science and 45% of the undergraduates participated in this project entered Graduate school.

Development and characterization of Mn2+-doped MgO nanoparticles by solution combustion synthesis

NASA Astrophysics Data System (ADS)

Basha, Md. Hussain; Gopal, N. O.; Rao, J. L.; Nagabhushana, H.; Nagabhushana, B. M.; Chakradhar, R. P. S.

2015-06-01

Mn doped MgO Nanoparticles have been prepared by Solution Combustion Synthesis. The synthesized sample is characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Electron Paramagnetic Resonance (EPR). The prepared MgO:Mn (1 mol%) nano crystals appear to be of simple cubic crystalline phase with lattice parameters a = 4.218(2) Å and cell volume = 74.98 (7) Å3. SEM micrograph of powders show highly porous, many agglomerates with irregular morphology, large voids, cracks and pores. EPR spectrum of the sample at room temperature exhibit an isotropic sextet hyperfine pattern, centered at g=1.99, characteristic if Mn2+ ions with S=I=5/2.The observed g value and the hyperfine value reveal the ionic bonding between Mn2+ and its surroundings.

Structural, microstructural, dielectric and ferroelectric properties of lead free Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramic

NASA Astrophysics Data System (ADS)

Sharma, Sarita; Sharma, Hakikat; Negi, N. S.

2018-05-01

Lead free Ba0.85Ca0.15Zr0.1Ti0.9O3(BCTZ) ceramic has been synthesized by sol-gel method. Properties of material are studied at different sintering temperatures for 5 hours. Structural and microstructural properties are analyzed by using X-ray diffractrometer (XRD) and scanning electron microscopy (SEM) at annealing temperature of 850°C and 1050°C XRD pattern confirm the perovskite structure of the material without any unwanted phases crystalinity increased with increase of sintering temperature so as roughness and porosity is decreased as shown by SEM micrographs. There is large improvement in density with rise of sintering temperature which also leads to drastic change in ferroelectric and dielectric properties.

A combined optical, SEM and STM study of growth spirals on the polytypic cadmium iodide crystals

NASA Astrophysics Data System (ADS)

Singh, Rajendra; Samanta, S. B.; Narlikar, A. V.; Trigunayat, G. C.

2000-05-01

Some novel results of a combined sequential study of growth spirals on the basal surface of the richly polytypic CdI 2 crystals by optical microscopy, scanning electron microscopy (SEM) and scanning tunneling microscopy (STM) are presented and discussed. Under the high resolution and magnification achieved in the scanning electron microscope, the growth steps of large heights seen in the optical micrographs are found to have a large number of additional steps of smaller heights existing between any two adjacent large height growth steps. When further seen by a scanning tunneling microscope, which provides still higher resolution, sequences of unit substeps, each of height equal to the unit cell height of the underlying polytype, are revealed to exist on the surface. Several large steps also lie between the unit steps, with heights equal to an integral multiple of either the unit cell height of the underlying polytype or the thickness of a molecular sheet I-Cd-I. It is suggested that initially a giant screw dislocation may form by brittle fracture of the crystal platelet, which may gradually decompose into numerous unit dislocations during subsequent crystal growth.

Recent advances in 3D SEM surface reconstruction.

PubMed

Tafti, Ahmad P; Kirkpatrick, Andrew B; Alavi, Zahrasadat; Owen, Heather A; Yu, Zeyun

2015-11-01

The scanning electron microscope (SEM), as one of the most commonly used instruments in biology and material sciences, employs electrons instead of light to determine the surface properties of specimens. However, the SEM micrographs still remain 2D images. To effectively measure and visualize the surface attributes, we need to restore the 3D shape model from the SEM images. 3D surface reconstruction is a longstanding topic in microscopy vision as it offers quantitative and visual information for a variety of applications consisting medicine, pharmacology, chemistry, and mechanics. In this paper, we attempt to explain the expanding body of the work in this area, including a discussion of recent techniques and algorithms. With the present work, we also enhance the reliability, accuracy, and speed of 3D SEM surface reconstruction by designing and developing an optimized multi-view framework. We then consider several real-world experiments as well as synthetic data to examine the qualitative and quantitative attributes of our proposed framework. Furthermore, we present a taxonomy of 3D SEM surface reconstruction approaches and address several challenging issues as part of our future work. Copyright © 2015 Elsevier Ltd. All rights reserved.

Miscibility and Morphology of Poly(lactic ACID)/POLY(Β-HYDROXYBUTYRATE) Blends

NASA Astrophysics Data System (ADS)

Tri Phuong, Nguyen; Guinault, Alain; Sollogoub, Cyrille

2011-01-01

The miscibility and morphology of poly(lactic)acid (PLA)/polyβ-hydroxybutyrate (PHB) prepared by melt blending method were investigated by Fourier transform infrared (FTIR), Differential scanning calorimetry (DSC), melt rheology and scanning electron microscopy (SEM) observations. FTIR and DSC methods present some limits to examine the miscibility state of PLA/PHB blends. This drawback can be overcome with the Cole-Cole method by observing the η" = f(η') curves to confirm the miscibility of semicrystalline PLA/ semicrystalline PHB blends. MEB micrographs of fractured surface of blends were also used to investigate the miscibility of these blends.

Investigation of manifestation of optical properties of butterfly wings with nanoscale zinc oxide incorporation

NASA Astrophysics Data System (ADS)

Aideo, Swati N.; Mohanta, Dambarudhar

2016-10-01

In this work, microstructural and optical characteristics nanoparticles of wings of Tailed Jay (Graphium Agamemnon) butterfly were studied before and after treating it in a precursor solution of zinc acetate and ethanol. We speculate that the butterfly scales are infiltrated with ZnO nanoparticles owing to reduction of Zinc hydroxide under ambient condition. The ZnO butterfly scales so produced were characterised using optical microscopy, UV-Vis reflectance spectroscopy, and electron microscopy etc. From the reflectance spectra, we could see that after treating it in the solution, optical properties vary. We anticipate that this change may be due to the formation of ZnO nanoparticles as well as the loss in periodicity due to the chemical treatments, which could be assessed from the SEM micrographs.

Evaluation of enamel by scanning electron microscopy green LED associated to hydrogen peroxide 35% for dental bleaching

NASA Astrophysics Data System (ADS)

Monteiro, Juliana S. C.; de Oliveira, Susana C. P. S.; Zanin, Fátima A. A.; Santos, Gustavo M. P.; Sampaio, Fernando J. P.; Gomes Júnior, Rafael Araújo; Gesteira, Maria F. M.; Vannier-Santos, Marcos A.; Pinheiro, Antônio Luiz B.

2014-02-01

Dental bleaching is a frequently requested procedure in clinical dental practice. The literature is contradictory regarding the effects of bleaching agents on both morphology and demineralization of enamel after bleaching. The aim of this study was to analyze by SEM the effect of 35% neutral hydrogen peroxide cured by green LED. Buccal surfaces of 15 pre-molars were sectioned and marked with a central groove to allow experimental and control groups on the same specimen. For SEM, 75 electron micrographs were evaluated by tree observers at 43X, 220X and 1000X. Quantitative analysis for the determination of the surface elemental composition of the samples through X-ray microanalysis by SEM was also performed. The protocol tested neither showed significant changes in mineral composition of the samples nor to dental enamel structure when compared to controls. SEM analysis allowed inferring that there were marked morphological differences between the enamel samples highlighting the need for the use of the same tooth in comparative morphological studies. The tested protocol did not cause morphological damage the enamel surface when compared to their respective controls.

Evaluation of poly (vinyl alcohol) based cryogel-zinc oxide nanocomposites for possible applications as wound dressing materials.

PubMed

Chaturvedi, Archana; Bajpai, Anil K; Bajpai, Jaya; K Singh, Sunil

2016-08-01

In this investigation cryogels composed of poly (vinyl alcohol) (PVA) were prepared by repeated freeze thaw method followed by in situ precipitation of zinc oxide nanoparticles within the cryogel networks. Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX) were used to characterize the nanocomposites. The morphologies of native PVA cryogels and PVA cryogel-ZnO nanocomposites were observed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) techniques. The SEM analysis suggested that cryogels show a well-defined porous morphology whereas TEM micrographs revealed the presence of nearly spherical and well separated zinc oxide nanoparticles with diameter<100nm. XRD results showed all relevant Bragg's reflections for crystal structure of zinc oxide nanoparticles. Thermo gravimetric-differential thermal analysis (TG-DTA) was conducted to evaluate thermal stability of the nanocomposites. Mechanical properties of nanocomposites were determined in terms of tensile strength and percent elongation. Biocompatible nature was ascertained by anti-haemolytic activity, bovine serum albumin (blood protein) adsorption and in vitro cytotoxicity tests. The prepared nanocomposites were also investigated for swelling and deswelling behaviours. The results revealed that both the swelling and deswelling process depend on the chemical composition of the nanocomposites, number of freeze-thaw cycles, pH and temperature of the swelling medium. The developed biocompatible PVA cryogel-ZnO nanocomposites were also tested for antibacterial activities against both Gram-negative and Gram-positive bacteria. Copyright © 2016 Elsevier B.V. All rights reserved.

Microstructural, optical and electrical properties of LaFe0.5Cr0.5O3 perovskite nanostructures

NASA Astrophysics Data System (ADS)

Ali, S. Asad; Naseem, Swaleha; Khan, Wasi; Sharma, A.; Naqvi, A. H.

2016-05-01

Perovskite nanocrystalline powder of LaFe0.5Cr0.5O3 was synthesized by sol-gel combustion route and characterized by x-ray diffractometer (XRD), scanning electron microscopy (SEM) equipped with EDS, UV-visible and LCR meter at room temperature Rietveld refinement of the XRD data confirms that the sample is in single phase-rhombohedral structure with space group R-3C. SEM micrograph shows clear nanostructure of the sample and EDS ensures the presence of all elements in good stoichiometric. The optical absorption indicates the maximum absorption at 315 nm and optical band gap of 2.94 eV was estimated using Tauc's relation. Dielectric constant (ɛ') and loss were found to decrease with increase in frequencies. The dielectric behavior was explained on the basis of Maxwell-Wagner's two layer model.

Microbial examination of anaerobic sludge adaptation to animal slurry.

PubMed

Moset, V; Cerisuelo, A; Ferrer, P; Jimenez, A; Bertolini, E; Cambra-López, M

2014-01-01

The objective of this study was to evaluate changes in the microbial population of anaerobic sludge digesters during the adaptation to pig slurry (PS) using quantitative real-time polymerase chain reaction (qPCR) and qualitative scanning electron microscopy (SEM). Additionally, the relationship between microbial parameters and sludge physicochemical composition and methane yield was examined. Results showed that the addition of PS to an unadapted thermophilic anaerobic digester caused an increase in volatile fatty acids (VFA) concentration, a decrease in removal efficiency and CH4 yield. Additionally, increases in total bacteria and total archaea were observed using qPCR. Scanning electron micrographs provided a general overview of the sludge's cell morphology, morphological diversity and degree of organic matter degradation. A change in microbial morphotypes from homogeneous cell morphologies to a higher morphological diversity, similar to that observed in PS, was observed with the addition of PS by SEM. Therefore, the combination of qPCR and SEM allowed expanding the knowledge about the microbial adaptation to animal slurry in thermophilic anaerobic digesters.

Graphite to Graphene via Graphene Oxide: An Overview on Synthesis, Properties, and Applications

NASA Astrophysics Data System (ADS)

Hansora, D. P.; Shimpi, N. G.; Mishra, S.

2015-12-01

This work represents a state-of-the-art technique developed for the preparation of graphene from graphite-metal electrodes by the arc-discharge method carried out in a continuous flow of water. Because of continuous arcing of graphite-metal electrodes, the graphene sheets were observed in water with uniformity and little damage. These nanosheets were subjected to various purification steps such as acid treatment, oxidation, water washing, centrifugation, and drying. The pure graphene sheets were analyzed using Raman spectrophotometry, x-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), and tunneling electron microscopy (TEM). Peaks of Raman spectra were recorded at (1300-1400 cm-1) and (1500-1600 cm-1) for weak D-band and strong G-band, respectively. The XRD pattern showed 85.6% crystallinity of pure graphite, whereas pure graphene was 66.4% crystalline. TEM and FE-SEM micrographs revealed that graphene sheets were overlapped to each other and layer-by-layer formation was also observed. Beside this research work, we also reviewed recent developments of graphene and related nanomaterials along with their preparations, properties, functionalizations, and potential applications.

Microstructural Evolution of Secondary Phases in the Cast Duplex Stainless Steels CD3MN and CD3MWCuN

NASA Astrophysics Data System (ADS)

Kim, Yoon-Jun; Ugurlu, Ozan; Jiang, Chao; Gleeson, Brian; Chumbley, L. Scott

2007-02-01

The isothermal formation behavior of secondary phases in two types of duplex stainless steels (DSS), CD3MN and CD3MWCuN, was characterized. Samples were heat treated from 1 minute to 30 days at temperatures from 700°C to 900°C. Small carbide (M23C6) and nitride (Cr2N) precipitates, together with the intermetallic phases sigma and chi, were observed using scanning electron microscopy (SEM) and confirmed by transmission electron microscopy (TEM) analyses. Based on SEM analysis, time-temperature-transformation (TTT) curves for the sigma and chi phases were determined by measuring their volume fractions from backscattered electron micrographs of heat-treated and quenched sample cross sections. Resulting TTT curves showed that the maximum formation temperature for chi is lower than that for sigma, while the time to reach 1 vol pct formation is much less for sigma than it is for chi. The thermodynamic driving forces associated with the sigma and chi formation were assessed using Thermo-Calc.

Surfactant-free bio-synthesised Tio2 nanorods from Turbinaria conoides-a study on photocatalytic and anti-bacterial activity

NASA Astrophysics Data System (ADS)

Subhapriya, S.; Gomathipriya, P.

2018-06-01

In this study, Titania nanorods were synthesised from aqueous extract of Turbinaria conoides (brown seaweeds) (TiO2NRs-TC) under surfactant free medium. The photocatalytic activity of the synthesised nanorods was tested towards the photocatalytic decolourization using simulated dye wastewater containing Navy Blue HER (NBHER). The synthesised Titania nanorods were characterized by using x-ray diffraction (XRD), UV–visible spectroscopy (UV–vis), Scanning Electron Microscopy (SEM), Energy Dispersive Spectrophotometer (EDS) and Transmission Electron Microscopy (TEM). XRD pattern confirms the anatase phase formation and HR-SEM micrograph shows the presence of rod like structure with the size of about 50 nm. TEM analysis proves the rod like structure with a size of 45–50 nm which was in agreement with the XRD analysis and HR-SEM images. EDS and XDS confirmed the formation of Titania nanoparticles. The formation of TiO2NRs-TC has a beneficial influence on the dye Navy blue HER photodegradation. TiO2-TC nano rods also show superior photocatalytic ability in hydrogen generation (2.1 mmol/h‑1g‑1). The antibacterial activity of the synthesised nanoparticles was examined using disc diffusion method which showed diverse susceptibility of microorganisms to the Titania nanoparticles.

Serial Section Scanning Electron Microscopy (S3EM) on Silicon Wafers for Ultra-Structural Volume Imaging of Cells and Tissues

PubMed Central

Horstmann, Heinz; Körber, Christoph; Sätzler, Kurt; Aydin, Daniel; Kuner, Thomas

2012-01-01

High resolution, three-dimensional (3D) representations of cellular ultrastructure are essential for structure function studies in all areas of cell biology. While limited subcellular volumes have been routinely examined using serial section transmission electron microscopy (ssTEM), complete ultrastructural reconstructions of large volumes, entire cells or even tissue are difficult to achieve using ssTEM. Here, we introduce a novel approach combining serial sectioning of tissue with scanning electron microscopy (SEM) using a conductive silicon wafer as a support. Ribbons containing hundreds of 35 nm thick sections can be generated and imaged on the wafer at a lateral pixel resolution of 3.7 nm by recording the backscattered electrons with the in-lens detector of the SEM. The resulting electron micrographs are qualitatively comparable to those obtained by conventional TEM. S3EM images of the same region of interest in consecutive sections can be used for 3D reconstructions of large structures. We demonstrate the potential of this approach by reconstructing a 31.7 µm3 volume of a calyx of Held presynaptic terminal. The approach introduced here, Serial Section SEM (S3EM), for the first time provides the possibility to obtain 3D ultrastructure of large volumes with high resolution and to selectively and repetitively home in on structures of interest. S3EM accelerates process duration, is amenable to full automation and can be implemented with standard instrumentation. PMID:22523574

Serial section scanning electron microscopy (S3EM) on silicon wafers for ultra-structural volume imaging of cells and tissues.

PubMed

Horstmann, Heinz; Körber, Christoph; Sätzler, Kurt; Aydin, Daniel; Kuner, Thomas

2012-01-01

High resolution, three-dimensional (3D) representations of cellular ultrastructure are essential for structure function studies in all areas of cell biology. While limited subcellular volumes have been routinely examined using serial section transmission electron microscopy (ssTEM), complete ultrastructural reconstructions of large volumes, entire cells or even tissue are difficult to achieve using ssTEM. Here, we introduce a novel approach combining serial sectioning of tissue with scanning electron microscopy (SEM) using a conductive silicon wafer as a support. Ribbons containing hundreds of 35 nm thick sections can be generated and imaged on the wafer at a lateral pixel resolution of 3.7 nm by recording the backscattered electrons with the in-lens detector of the SEM. The resulting electron micrographs are qualitatively comparable to those obtained by conventional TEM. S(3)EM images of the same region of interest in consecutive sections can be used for 3D reconstructions of large structures. We demonstrate the potential of this approach by reconstructing a 31.7 µm(3) volume of a calyx of Held presynaptic terminal. The approach introduced here, Serial Section SEM (S(3)EM), for the first time provides the possibility to obtain 3D ultrastructure of large volumes with high resolution and to selectively and repetitively home in on structures of interest. S(3)EM accelerates process duration, is amenable to full automation and can be implemented with standard instrumentation.

Study on biofilm-forming properties of clinical isolates of Staphylococcus aureus.

PubMed

Taj, Yasmeen; Essa, Farhan; Aziz, Faisal; Kazmi, Shahana Urooj

2012-05-14

The purpose of this study was to observe the formation of biofilm, an important virulence factor, by isolates of Staphylococcus aureus (S. aureus) in Pakistan by different conventional methods and through electron microscopy. We screened 115 strains of S. aureus isolated from different clinical specimens by tube method (TM), air-liquid interface coverslip assay method, Congo red agar (CRA) method, and scanning electron microscopy (SEM). Out of 115 S. aureus isolates, 63 (54.78%) showed biofilm formation by tube method. Biofilm forming bacteria were further categorized as high producers (n = 23, 20%) and moderate producers (n = 40, 34.78%). TM coordinated well with the coverslip assay for strong biofilm-producing strains in 19 (16.5%) isolates. By coverslip method, weak producers were difficult to differentiate from biofilm negative isolates. Screening on CRA showed biofilm formation only in four (3.47%) strains. Scanning electron micrographs showed the biofilm-forming strains of S. aureus arranged in a matrix on the propylene surface and correlated well with the TM. Biofilm production is a marker of virulence for clinically relevant staphylococcal infections. It can be studied by various methods but screening on CRA is not recommended for investigation of biofilm formation in Staphylococcus aureus. Electron micrograph images correlate well with the biofilm production as observed by TM.

Leaching behavior and ESEM characterization of water-sensitive mudstone in southwestern Taiwan.

PubMed

Chen, Hung-Ta; Lin, Tzong-Tzeng; Chang, Juu-En

2003-05-01

This investigation attempts to understand the critical soluble salts in natural mudstone and the leaching, microstructural, and microchemical characteristics in soaked mudstone using scanning electron microscopy (SEM)/energy-dispersive X-ray analysis (EDAX), X-ray fluorescence spectrometry (XRF), X-ray diffractometry (XRD), conductivity measurement, ion chromatography (IC), and environmental scanning electron microscopy (ESEM)/EDAX techniques. Natural mudstone probably includes soluble salts such as Na2SO4, NaCl, NaCO3, and CaCO3. The dissolution of Na2SO4 controls water-sensitive mudstone very susceptible to slaking and dispersion. ESEM micrographs clearly show evidence of mudstone-slaking during soaking since the visible pores are filled with small aggregative masses. A calcium-bearing precipitate from the soaked mudstone is speculated to be attributable to the decomposition of the hydrated product of the fresh mudstone.

Production of bacterial cellulose using different carbon sources and culture media.

PubMed

Mohammadkazemi, Faranak; Azin, Mehrdad; Ashori, Alireza

2015-03-06

In this work, the effects of carbon sources and culture media on the production and structural properties of bacterial cellulose (BC) have been studied. BC nanofibers were synthesized using Gluconacetobacter xylinus strain PTCC 1734. Media used were Hestrin-Schramm (H), Yamanaka (Y), and Zhou (Z). Five different carbon sources, namely date syrup, glucose, mannitol, sucrose, and food-grade sucrose were used in these media. All the produced BC pellicles were characterized in terms of dry weight production, biomass yield, thermal stability, crystallinity and morphology by thermogravimetric analysis (TGA), x-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The obtained results showed that mannitol lead to the highest yield, followed by sucrose. The highest production efficiency of mannitol might be due to the nitrogen source, which plays an important role. The maximum improvement on the thermal stability of the composites was achieved when mannitol was used in H medium. In addition, the crystallinity was higher in BC formed in H medium compared to other media. FE-SEM micrographs illustrated that the BC pellicles, synthesized in the culture media H and Z, were stable, unlike those in medium Y that were unstable. The micrographs of BC produced in media containing mannitol and sucrose provided evidence of the strong interfacial adhesion between the BC fibers without noticeable aggregates. Copyright © 2014 Elsevier Ltd. All rights reserved.

Evaluation of Microstructure and Mechanical Properties of Al-TiC Metal Matrix Composite Prepared by Conventional, Microwave and Spark Plasma Sintering Methods

PubMed Central

Ghasali, Ehsan; Fazili, Ali; Alizadeh, Masoud; Shirvanimoghaddam, Kamyar; Ebadzadeh, Touradj

2017-01-01

In this research, the mechanical properties and microstructure of Al-15 wt % TiC composite samples prepared by spark plasma, microwave, and conventional sintering were investigated. The sintering process was performed by the speak plasma sintering (SPS) technique, microwave and conventional furnaces at 400 °C, 600 °C, and 700 °C, respectively. The results showed that sintered samples by SPS have the highest relative density (99% of theoretical density), bending strength (291 ± 12 MPa), and hardness (253 ± 23 HV). The X-ray diffraction (XRD) investigations showed the formation of TiO2 from the surface layer decomposition of TiC particles. Scanning electron microscopy (SEM) micrographs demonstrated uniform distribution of reinforcement particles in all sintered samples. The SEM/EDS analysis revealed the formation of TiO2 around the porous TiC particles. PMID:29088114

Development and characterization of Mn{sup 2+}-doped MgO nanoparticles by solution combustion synthesis

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

Basha, Md. Hussain; Gopal, N. O., E-mail: nogopal@yahoo.com; Rao, J. L.

2015-06-24

Mn doped MgO Nanoparticles have been prepared by Solution Combustion Synthesis. The synthesized sample is characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Electron Paramagnetic Resonance (EPR). The prepared MgO:Mn (1 mol%) nano crystals appear to be of simple cubic crystalline phase with lattice parameters a = 4.218(2) Å and cell volume = 74.98 (7) Å{sup 3}. SEM micrograph of powders show highly porous, many agglomerates with irregular morphology, large voids, cracks and pores. EPR spectrum of the sample at room temperature exhibit an isotropic sextet hyperfine pattern, centered at g=1.99, characteristic if Mn{sup 2+} ions with S=I=5/2.The observedmore » g value and the hyperfine value reveal the ionic bonding between Mn{sup 2+} and its surroundings.« less

Effect of some biotic factors on microbially-induced calcite precipitation in cement mortar.

PubMed

Al-Salloum, Yousef; Abbas, H; Sheikh, Q I; Hadi, S; Alsayed, Saleh; Almusallam, Tarek

2017-02-01

Sporosarcina pasteurii , a common soil bacterium has been tested for microbial treatment of cement mortar. The present study also seeks to investigate the effects of growth medium, bacterial concentration and different buffers concerning the preparation of bacterial suspensions on the compressive strength of cement mortar. Two growth media, six different suspensions and two bacterial concentrations were used in the study. The influence of growth medium on calcification efficiency of S. pasteurii was insignificant. Significant improvement in the compressive as well as the tensile strength of cement mortar was observed. Microbial mineral precipitation visualized by Scanning Electron Microscopy (SEM) shows fibrous material that increased the strength of cement mortar. Formation of thin strands of fillers observed through SEM micrographs improves the pore structure, impermeability and thus the compressive as well as the tensile strengths of the cement mortar. The type of substrate and its molarity have a significant influence on the strength of cement mortar.

Composition and Structure of Microalgae Indicated in Raman and Hyperspectral Spectra and Scanning Electron Microscopy: from Cyanobacteria to Isolates from Coal-bed Methane Water Ponds

NASA Astrophysics Data System (ADS)

Zhou, X.; Zhou, Z.; Apple, M. E.; Spangler, L.

2017-12-01

Microalgae can be used for many potential applications for human's benefits. These potential applications included biofuel production from microalgae, biofiltering to cleaning water, chemical extraction as nutrients, etc. However, exploration for such applications is still in the early stages. For instance, many species and strains of microalgae have been investigated for their lipid content and growing conditions for efficient productions of lipids, but no specific species have yet been chosen as a fuel source for commercial production because of the huge biodiversity and subsequently a wide range of species that can potentially be exploited for biodiesel production, the great variability between species in their fuel precursor producing capabilities. Numerous coal-bed methane water ponds were established in the world as a consequence of coal-bed methane production from deep coal seams. Microalgae were isolated from such ponds and potentially these ponds can be used as venues for algal production. In this study, we characterized chemical composition and structure of the Cyanobacteria Anabaena cylindrica (UTEX # 1611) and isolates from coal-bed methane ponds Nannochloropsis gaditana and PW95 using Laser Raman Spectroscopy (LRS), hyperspectral spectra, and Scanning Electron Microscope (SEM). The objective is to seek bio-indicators for potential applications of these microalgae species. For instance, indicator of rich content lips shows the great potential for biofuel production. Fig.1 shows an example of the Raman spectra of the three species in desiccated form. The spectral peaks were isolated and the corresponding composition was identified. The insert at the right hand of the Raman spectrum of each species is the micrograph of the cell morphology under a microscope. The Raman spectra of cells in aquatic solutions were also obtained and compared with the desiccated form. The hyperspectral reflectances of the three species show quite different characteristics and the main absorption bands and scattering bands were located and their association with composition and structure were analyzed and discussed. SEM micrographs will be collected and the composition and structure derived from the SEM micrographs will be discussed and compared with those derived from the Raman spectra and hyperspectral spectra.

In vitro deposition of hydroxyapatite on cortical bone collagen stimulated by deformation-induced piezoelectricity.

PubMed

Noris-Suárez, Karem; Lira-Olivares, Joaquin; Ferreira, Ana Marina; Feijoo, José Luis; Suárez, Nery; Hernández, Maria C; Barrios, Esteban

2007-03-01

In the present work, we have studied the effect of the piezoelectricity of elastically deformed cortical bone collagen on surface using a biomimetic approach. The mineralization process induced as a consequence of the piezoelectricity effect was evaluated using scanning electron microscopy (SEM), thermally stimulated depolarization current (TSDC), and differential scanning calorimetry (DSC). SEM micrographs showed that mineralization occurred predominantly over the compressed side of bone collagen, due to the effect of piezoelectricity, when the sample was immersed in the simulated body fluid (SBF) in a cell-free system. The TSDC method was used to examine the complex collagen dielectric response. The dielectric spectra of deformed and undeformed collagen samples with different hydration levels were compared and correlated with the mineralization process followed by SEM. The dielectric measurements showed that the mineralization induced significant changes in the dielectric spectra of the deformed sample. DSC and TSDC results demonstrated a reduction of the collagen glass transition as the mineralization process advanced. The combined use of SEM, TSDC, and DSC showed that, even without osteoblasts present, the piezoelectric dipoles produced by deformed collagen can produce the precipitation of hydroxyapatite by electrochemical means, without a catalytic converter as occurs in classical biomimetic deposition.

Porous Si nanowires for highly selective room-temperature NO2 gas sensing

NASA Astrophysics Data System (ADS)

Kwon, Yong Jung; Mirzaei, Ali; Gil Na, Han; Kang, Sung Yong; Choi, Myung Sik; Bang, Jae Hoon; Oum, Wansik; Kim, Sang Sub; Kim, Hyoun Woo

2018-07-01

We report the room-temperature sensing characteristics of Si nanowires (NWs) fabricated from p-Si wafers by a metal-assisted chemical etching method, which is a facile and low-cost method. X-ray diffraction was used to the the study crystallinity and phase formation of Si NWs, and product morphology was examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). After confirmation of Si NW formation via the SEM and TEM micrographs, sensing tests were carried out at room temperature, and it was found that the Si NW sensor prepared from Si wafers with a resistivity of 0.001–0.003 Ω.cm had the highest response to NO2 gas (Rg/Ra = 1.86 for 50 ppm NO2), with a fast response (15 s) and recovery (30 s) time. Furthermore, the sensor responses to SO2, toluene, benzene, H2, and ethanol were nearly negligible, demonstrating the excellent selectivity to NO2 gas. The gas-sensing mechanism is discussed in detail. The present sensor can operate at room temperature, and is compatible with the microelectronic fabrication process, demonstrating its promise for next-generation Si-based electronics fused with functional chemical sensors.

Hematite/silica nanoparticle bilayers on mica: AFM and electrokinetic characterization.

PubMed

Morga, Maria; Adamczyk, Zbigniew; Kosior, Dominik; Oćwieja, Magdalena

2018-06-06

Quantitative studies on self-assembled hematite/silica nanoparticle (NP) bilayers on mica were performed by applying scanning electron microscopy (SEM), atomic force microscopy (AFM), and streaming potential measurements. The coverage of the supporting hematite layers was adjusted by changing the bulk concentration of the suspension and the deposition time. The coverage was determined by direct enumeration of deposited particles from AFM images and SEM micrographs. Afterward, silica nanoparticle monolayers were assembled under diffusion-controlled transport. A unique functional relationship was derived connecting the silica coverage with the hematite precursor layer coverage. The formation of the hematite monolayer and the hematite/silica bilayer was also monitored in situ by streaming potential measurements. It was confirmed that the zeta potential of the bilayers was independent of the supporting layer coverage, exceeding 0.15. These measurements were theoretically interpreted in terms of the general electrokinetic model that allowed for deriving a formula for calculating nanoparticle coverage in the bilayers. Additionally, from desorption experiments, the interactions among hematite/silica particles in the bilayers were determined using DLVO theory. These results facilitate the development of a robust method of preparing nanoparticle bilayers with controlled properties, with potential applications in catalytic processes.

Porous Si nanowires for highly selective room-temperature NO2 gas sensing.

PubMed

Kwon, Yong Jung; Mirzaei, Ali; Na, Han Gil; Kang, Sung Yong; Choi, Myung Sik; Bang, Jae Hoon; Oum, Wansik; Kim, Sang Sub; Kim, Hyoun Woo

2018-07-20

We report the room-temperature sensing characteristics of Si nanowires (NWs) fabricated from p-Si wafers by a metal-assisted chemical etching method, which is a facile and low-cost method. X-ray diffraction was used to the the study crystallinity and phase formation of Si NWs, and product morphology was examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). After confirmation of Si NW formation via the SEM and TEM micrographs, sensing tests were carried out at room temperature, and it was found that the Si NW sensor prepared from Si wafers with a resistivity of 0.001-0.003 Ω.cm had the highest response to NO 2 gas (R g /R a  = 1.86 for 50 ppm NO 2 ), with a fast response (15 s) and recovery (30 s) time. Furthermore, the sensor responses to SO 2 , toluene, benzene, H 2 , and ethanol were nearly negligible, demonstrating the excellent selectivity to NO 2 gas. The gas-sensing mechanism is discussed in detail. The present sensor can operate at room temperature, and is compatible with the microelectronic fabrication process, demonstrating its promise for next-generation Si-based electronics fused with functional chemical sensors.

Synthesis and characterization of novel 4-Tetra-4-Tolylsulfonyl ZnPc thin films for optoelectronic applications

NASA Astrophysics Data System (ADS)

Khalil, Salah; Tazarki, Helmi; Souli, Mehdi; Guasch, Cathy; Jamoussi, Bassem; Kamoun, Najoua

2017-11-01

Novel 4-Tetra-4-Tolylsulfonyl:zinc phthalocyanine and simple zinc phthalocyanine were synthesized. Our materials were grown on glass substrates by spin coating technique. Thin films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electronic micrograph (SEM), atomic force microscopy (AFM), spectrophotometer and Hall effect measurement. X-ray spectra reveal that 4-Tetra-4-Tolylsulfonyl:zinc phthalocyanine (4T4TS:ZnPc) and zinc phthalocyanine (ZnPc) thin films have a monoclinic crystalline structure in β phase. The surface properties and chemical composition were detailed using XPS measurement. SEM were used to investigate the surface morphology for 4T4TS:ZnPc and ZnPc thin films. Atomic force microscopy images have shown a decrease in surface roughness after substitution. Optical properties were investigated by measuring transmission and reflection spectra. Electrical properties were studied and the different electrical parameters was measured and compared on glass, silicon and tin dioxide substrates by Hall Effect technique. All obtained results indicate an improvement in physical properties of 4T4TS:ZnPc which allows used it in optoelectronic applications.

Additive assisted hydrothermal synthesis, characterization and optical properties of one dimensional DyPO4:Ce3+ nanostructures

NASA Astrophysics Data System (ADS)

Khajuria, H.; Kumar, M.; Singh, R.; Ladol, J.; Nawaz Sheikh, H.

2018-05-01

One dimensional nanostructures of cerium doped dysprosium phosphate (DyPO4:Ce3+) were synthesized via hydrothermal route in the presence of different surfactants [sodium dodecyl sulfate (SDS), dodecyl sulfosuccinate (DSS), polyvinyl pyrollidone (PVP)] and solvent [ethylene glycol and water]. The prepared nanostructures were characterized by Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), UV-VIS-NIR absorption spectrophotometer and photoluminescence (PL) studies. The PXRD and FTIR results indicate purity, good crystallinity and effective doping of Ce3+ in nanostructures. SEM and TEM micrographs display nanorods, nanowires and nanobundles like morphology of DyPO4:Ce3+. Energy-dispersive X-ray spectra (EDS) of DyPO4:Ce3+nanostructures confirm the presence of dopant. UV-VIS-NIR absorption spectra of prepared compounds are used to calculate band gap and explore their optical properties. Luminescent properties of DyPO4:Ce3+ was studied by using PL emission spectra. The effect of additives and solvents on the uniformity, morphology and optical properties of the nanostructures were studied in detail.

Porous carbon materials synthesized using IRMOF-3 and furfuryl alcohol as precursor

NASA Astrophysics Data System (ADS)

Deka, Pemta Tia; Ediati, Ratna

2016-03-01

IRMOF-3 crystals have been synthesized using solvothermal method by adding zinc nitrate hexahydrate with 2-amino-1,4-benzenedicarboxylic acid in N'N-dimethylformamide (DMF) at 100°C for 24 (note as IR-24) and 72 h (note as IR-72). The obtained crystals were characterized using X-ray Diffraction (XRD), SEM (Scanning Electron Microscopy) and Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX), FTIR and Isothermal adsorption-desorption N2. The diffractogram solids synthesized show characteristic peak at 2θ 6.8, 9.6 and 13.7°. SEM micrograph show cubic shape of IRMOF-3 crystal. Based on FTIR characterization, IRMOF-3 appear at wavelength (1691,46; 1425,3; 1238,21; 1319,22 dan 3504,42)cm-1. The Isotherm of crystal IRMOF-3 at heating time 24 h and 72 h are type IV. The surface area of IR-24 and IR-72 are respectively 24,758 m2/g and 29,139 m2/g with its dominant mesopores. Carbonaceous materials has been successfully synthesized using IR-24, IR-72 and furfuryl alcohol (FA) as second carbon precursor with variation of carbonation temperature 550, 700 and 850°C. The XRD result from both carbonaceous materials show formation of amorphous carbon and caharacteristic peak of ZnO oxide. Micrograph SEM show that carbonaceous materials have cubic shape as IRMOF-3 and SEM-EDX result indicate Zn and nitrogen content of these materials has decrease until temperature 850°C. Porous carbon using IR-24 and FA (notes as C-24) has increased surface area with higher carbonation temperature. The highest surface area is 1495,023 m2/g. Total pore volume and pore size of C-24 from low to high temperature respectively as (0,338; 0,539 and 1,598) cc/g; (0,107; 0,152 and 0,610) cc/g. Porous carbon using IR-72 and FA (notes as C-72) has smaller surface area than C-24 but its also increased during higher carbonation heating. The highest surface area is 1029,668 m2/g.The total pore volume and pore size of these carbon materials from low to high temperature respectively as (0,390; 0,727 and 1,345) cc/g and (0,065; 0,157 and 0,381) cc/g. Carbonaceous materials with high porosity and nitrogen content will be expected increase mechanical properties and hydrogen storage from these materials.

Tetraethylorthosilicate (TEOS) applied in the surface modification of hydroxyapatite to develop polydimethylsiloxane/hydroxyapatite composites.

PubMed

Bareiro, O; Santos, L A

2014-03-01

Nanometric hydroxyapatite (HAp) particles were modified with 5 or 10 wt.% tetraethylorthosilicate (TEOS) solutions in order to prepare polydimethylsiloxane/hydroxyapatite (PDMS/HAp) composites. The surface modification of the HAp particles was studied by transmission electron spectroscopy (TEM) and by scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) equipment. The dispersion state of the modified particles in the PDMS matrix was also assessed by SEM. The composite phase composition was characterized by X-ray diffraction (XRD). The composite thermodynamic parameters of cross-linking were analyzed by differential scanning calorimetry (DSC). TEM micrographs and EDS spectra indicated evidence of silica-coating formation on the surface of modified HAp particles. SEM results showed that the HAp particles formed agglomerates in the PDMS matrix. It was found that the introduction of HAp particles into the PDMS changed the enthalpy of cross-linking and the temperature of the beginning of the cross-linking reaction. EDS results indicated that the surface modification of HAp produced composites showing thermodynamic parameters that were more similar to those of unfilled PDMS. Copyright © 2013 Elsevier B.V. All rights reserved.

Fabrication and physical-chemical characterisation of polyelectrolyte microparticles: platform for controlled release of bioactives.

PubMed

Sun, Yuhui; Travas-Sejdic, Jadranka; Wen, Jingyuan; Alany, Raid G

2009-08-01

Porous CaCO(3) microparticles were fabricated by colloidal crystallization. Two oppositely charged polyelectrolytes, poly (styrene sulfonate, PSS) and poly (allylamine hydrochloride, PAH) were adsorbed layer-by-layer on the CaCO(3) templates. Polyelectrolyte microcapsules were then obtained by removing the CaCO(3) core. Scanning electron microscopy (SEM), energy-dispersion X-ray analysis (EDX), laser diffraction particle sizing and Raman spectroscopy were employed to characterize the physico-chemical properties of the constructed microcapsules. In vitro drug release studies were conducted using the model water-soluble drug Rhodamine B. Factors such as the number of polyelectrolyte layers and pH were investigated. SEM micrographs revealed uniform CaCO(3) microparticles, nearly spherical in shape with pronounced surface roughness, and highly developed interior porous structure. The surface of polyelectrolyte coated particles became rougher than the initial CaCO(3) microparticles. The acquired SEM micrographs of the (PSS/PAH)(n) microcapsules indicated that the number of layers affected the morphology of the microcapsules. The (PSS/PAH)(3) microcapsules revealed a very porous network with many holes resembling the initial morphology of CaCO(3) microparticles. Raman spectra showed peaks at 1125 cm(-1) (S=O bond) and 1600 cm(-1) (aromatic ring stretching) which represented the PSS molecule. The thickness of each layer was about 10 to 20 nm and it can be tailored to such nanometer level by controlling the number of adsorbed layers. The in vitro release of Rhodamine B was dependent on both the number of wall bilayers as well as the pH of the release media. These systems provide an opportunity for the development of controlled release dosage forms with greater effectiveness in the treatment of chronic conditions.

Fabrication and characterization of functionalized surfaces with 3-amino propyltrimethoxysilane films for anti-infective therapy applications

NASA Astrophysics Data System (ADS)

Grumezescu, Valentina; Andronescu, Ecaterina; Holban, Alina Maria; Socol, Gabriel; Grumezescu, Alexandru Mihai; Ficai, Anton; Lazar, Veronica; Chifiriuc, Mariana Carmen; Trusca, Roxana; Iordache, Florin

2015-05-01

The purpose of this study was the fabrication of functionalized anti-adherent surfaces based on the polyvinyl chloride (PVC) coated with 3-amino propyltrimethoxysilane (APTMS) by matrix assisted pulsed laser evaporation (MAPLE) in order to improve the resistance of PVC based prosthetic devices to microbial colonization. Infrared microscopy (IRM) investigations of APTMS thin films proved the compositional homogeneity of the prepared thin film. Scanning electron microscopy (SEM) micrographs revealed a granular morphology with microspheres harboring a diameter between 15 and 60 nm. The microbiological assays proved that MAPLE deposited APTMS films inhibited the adherence capacity and biofilm development of Pseudomonas aeruginosa and Staphylococcus aureus strains. Furthermore, this material proved to be highly biocompatible, allowing the normal growth and development of human endothelial cells. These traits highlight the fact that the fabricated APTMS thin films may be efficiently used for improving different surfaces of medical use, including prostheses and implantable devices.

Synthesis of nano-crystalline hydroxyapatite and ammonium sulfate from phosphogypsum waste

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

Mousa, Sahar, E-mail: dollyriri@yahoo.com; King Abdulaziz University, Science and Art College, Chemistry Department, Rabigh Campus, P.O. Box:344, Postal code: 21911 Rabigh; Hanna, Adly

2013-02-15

Graphical abstract: TEM micrograph of dried HAP at 800 °C. -- Abstract: Phosphogypsum (PG) waste which is derived from phosphoric acid manufacture by using wet method was converted into hydroxyapatite (HAP) and ammonium sulfate. Very simple method was applied by reacting PG with phosphoric acid in alkaline medium with adjusting pH using ammonia solution. The obtained nano-HAP was dried at 80 °C and calcined at 600 °C and 900 °C for 2 h. Both of HAP and ammonium sulfate were characterized by X-ray diffraction (XRD) and infrared spectroscopy (IR) to study the structural evolution. The thermal behavior of nano-HAP wasmore » studied; the particle size and morphology were estimated by using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). All the results showed that HAP nano-crystalline and ammonium sulfate can successfully be produced from phosphogypsum waste.« less

Optical Waveguide Scattering Reduction. II.

DTIC Science & Technology

1980-12-01

Direct Methods..........................13 Topographical Approaches ................... 13 Nomarski Microscopy ................... 13 TIR Microscopy...6 3 Nomarski micrograph showing artifacts near the edge of a Ti- diffused LiNbO3 waveguide (50OX) ....... ................ 9...4 Nomarski micrograph showing the results of a 10 min heat treat- ment of LiNbO 3 at 850’C in flowing 02 ... ............. ... 12 5 Nomarski

Nanorods, nanospheres, nanocubes: Synthesis, characterization and catalytic activity of nanoferrites of Mn, Co, Ni, Part-89

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

Singh, Supriya; Srivastava, Pratibha; Singh, Gurdip, E-mail: gsingh4us@yahoo.com

2013-02-15

Graphical abstract: Prepared nanoferrites were characterized by FE-SEM and bright field TEM micrographs. The catalytic effect of these nanoferrites was evaluated on the thermal decomposition of ammonium perchlorate using TG and TG–DSC techniques. The kinetics of thermal decomposition of AP was evaluated using isothermal TG data by model fitting as well as isoconversional method. Display Omitted Highlights: ► Synthesis of ferrite nanostructures (∼20.0 nm) by wet-chemical method under different synthetic conditions. ► Characterization using XRD, FE-SEM, EDS, TEM, HRTEM and SAED pattern. ► Catalytic activity of ferrite nanostructures on AP thermal decomposition by thermal techniques. ► Burning rate measurements ofmore » CSPs with ferrite nanostructures. ► Kinetics of thermal decomposition of AP + nanoferrites. -- Abstract: In this paper, the nanoferrites of Mn, Co and Ni were synthesized by wet chemical method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive, X-ray spectra (EDS), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HR-TEM). It is catalytic activity were investigated on the thermal decomposition of ammonium perchlorate (AP) and composite solid propellants (CSPs) using thermogravimetry (TG), TG coupled with differential scanning calorimetry (TG–DSC) and ignition delay measurements. Kinetics of thermal decomposition of AP + nanoferrites have also been investigated using isoconversional and model fitting approaches which have been applied to data for isothermal TG decomposition. The burning rate of CSPs was considerably enhanced by these nanoferrites. Addition of nanoferrites to AP led to shifting of the high temperature decomposition peak toward lower temperature. All these studies reveal that ferrite nanorods show the best catalytic activity superior to that of nanospheres and nanocubes.« less

Synthesis and characterization of NiO nanopowder by sol-gel process

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

Ningsih, Sherly Kasuma Warda

2015-09-30

Preparation of nickel oxide (NiO) nanopowder by sol-gel process has been studied. NiO nanopowders were obtained by sol-gel method by using nickel nitrate hexahydrate and sodium hydroxide and aquadest were used as precursor, agent precipitator and solvent, respectively. The powders were formed by drying at 110°C and followed by heating in the furnace at 400°C for 1.5 hours. The product was obtained black powder. The product was characterized by Energy Dispesive X-ray Fluorescence (ED-XRF), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The ED-XRF pattern shows the composition of NiO produced was 97.1%. The XRD pattern showed NiO forms weremore » produced generally in monoclinic stucture. The crystalline size of NiO was obtained in the range 40-85 nm. SEM micrograph clearly showed that powder had a spherical with uniform distribution size is 0.1-1.0 µm approximately.« less

Structural and magnetic characterization of Ti doped cobalt ferrite (CoFe2O4)

NASA Astrophysics Data System (ADS)

Pal, Jaswinder; Kumar, Sunil; Kaur, Randeep; Agrawal, P.; Singh, Mandeep; Singh, Anupinder

2018-05-01

Synthesis of Co1-xTixFe2O4 solid solutions for 0.1≤x≤0.4 using the solid-state-reaction rate has been done. The prepared samples were characterized by using XRD (X-ray diffraction) and SEM (Scanning Electron Microscopy). Magnetic studies have been done using Vibrating Sample Magnetometer (VSM). XRD confirmed that Cobalt Ferrite spinel cubic structure in all prepared samples. The lattice parameter `a' increases with increase in the concentration of Ti. SEM micrograph shows good grain growth in all samples. Magnetic Study reveals that the M-H curves of all the prepared samples taken at room temperature are very well saturated. The maximum value of remnant magnetization (Mr ˜13.9 emu/g) and saturation magnetization (Ms ˜74.4 emu/g) has been observed for x =0.2 sample. Coercivity does not show any regular variation with increase in the molar concentration of Ti in CoFe2O4 at A-site.

Navicula sp. Sulfated Polysaccharide Gels Induced by Fe(III): Rheology and Microstructure

PubMed Central

Fimbres-Olivarría, Diana; López-Elías, José Antonio; Carvajal-Millán, Elizabeth; Márquez-Escalante, Jorge Alberto; Martínez-Córdova, Luis Rafael; Miranda-Baeza, Anselmo; Enríquez-Ocaña, Fernando; Valdéz-Holguín, José Eduardo; Brown-Bojórquez, Francisco

2016-01-01

A sulfated polysaccharide extracted from Navicula sp. presented a yield of 4.4 (% w/w dry biomass basis). Analysis of the polysaccharide using gas chromatography showed that this polysaccharide contained glucose (29%), galactose (21%), rhamnose (10%), xylose (5%) and mannose (4%). This polysaccharide presented an average molecular weight of 107 kDa. Scanning electron microscopy (SEM) micrographs showed that the lyophilized Navicula sp. polysaccharide is an amorphous solid with particles of irregular shapes and sharp angles. The polysaccharide at 1% (w/v) solution in water formed gels in the presence of 0.4% (w/v) FeCl3, showing elastic and viscous moduli of 1 and 0.7 Pa, respectively. SEM analysis performed on the lyophilized gel showed a compact pore structure, with a pore size of approximately 150 nm. Very few studies on the gelation of sulfated polysaccharides using trivalent ions exist in the literature, and, to the best of our knowledge, this study is the first to describe the gelation of sulfated polysaccharides extracted from Navicula sp. PMID:27483255

Navicula sp. Sulfated Polysaccharide Gels Induced by Fe(III): Rheology and Microstructure.

PubMed

Fimbres-Olivarría, Diana; López-Elías, José Antonio; Carvajal-Millán, Elizabeth; Márquez-Escalante, Jorge Alberto; Martínez-Córdova, Luis Rafael; Miranda-Baeza, Anselmo; Enríquez-Ocaña, Fernando; Valdéz-Holguín, José Eduardo; Brown-Bojórquez, Francisco

2016-07-30

A sulfated polysaccharide extracted from Navicula sp. presented a yield of 4.4 (% w/w dry biomass basis). Analysis of the polysaccharide using gas chromatography showed that this polysaccharide contained glucose (29%), galactose (21%), rhamnose (10%), xylose (5%) and mannose (4%). This polysaccharide presented an average molecular weight of 107 kDa. Scanning electron microscopy (SEM) micrographs showed that the lyophilized Navicula sp. polysaccharide is an amorphous solid with particles of irregular shapes and sharp angles. The polysaccharide at 1% (w/v) solution in water formed gels in the presence of 0.4% (w/v) FeCl₃, showing elastic and viscous moduli of 1 and 0.7 Pa, respectively. SEM analysis performed on the lyophilized gel showed a compact pore structure, with a pore size of approximately 150 nm. Very few studies on the gelation of sulfated polysaccharides using trivalent ions exist in the literature, and, to the best of our knowledge, this study is the first to describe the gelation of sulfated polysaccharides extracted from Navicula sp.

Effects of gliadin addition on the rheological, microscopic and thermal characteristics of wheat gluten.

PubMed

Khatkar, B S; Barak, Sheweta; Mudgil, Deepak

2013-02-01

In the present study, micro-structural, thermal and rheological changes in the gluten network upon addition of gliadins at 5% and 10% levels were investigated using scanning electron microscopy (SEM), thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC) and dynamic rheometry. The addition of gliadins decreased the peak dough height inferring decrease in dough strength. The dough stability also decreased from 3.20 to 1.40 min upon addition of 10% gliadin to the base flour. The TGA profile and the glass transition behavior of the control gluten and gluten obtained from dough with gliadin added at 5% and 10% levels showed decrease in thermal stability. The SEM micrograph of the control gluten showed foam like protein matrix. As the gliadin percentage in the gluten was increased, the compactness of the gluten structure reduced considerably leading to the formation of a more open weak gluten network. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis and optimization of chitosan nanoparticles: Potential applications in nanomedicine and biomedical engineering.

PubMed

Ghadi, Arezou; Mahjoub, Soleiman; Tabandeh, Fatemeh; Talebnia, Farid

2014-01-01

Chitosan nanoparticles have become of great interest for nanomedicine, biomedical engineering and development of new therapeutic drug release systems with improved bioavailability, increased specificity and sensitivity, and reduced pharmacological toxicity. The aim of the present study was to synthesis and optimize of the chitosan nanoparticles for industrial and biomedical applications. Fe3O4 was synthesized and optimized as magnetic core nanoparticles and then chitosan covered this magnetic core. The size and morphology of the nano-magnetic chitosan was analyzed by scanning electron microscope (SEM). Topography and size distribution of the nanoparticles were shown with two-dimensional and three-dimensional images of atomic force microscopy (AFM). The nanoparticles were analyzed using transmission electron microscopy (TEM). The chitosan nanoparticles prepared in the experiment exhibited white powder shape. The SEM micrographs of the nano-magnetic chitosan showed that they were approximately uniform spheres. The unmodified chitosan nanoparticles composed of clusters of nanoparticles with sizes ranging from 10 nm to 80 nm. AFM provides a three-dimensional surface profile. The TEM image showed physical aggregation of the chitosan nanoparticles. The results show that a novel chitosan nanoparticle was successfully synthesized and characterized. It seems that this nanoparticle like the other chitosan nano particles has potential applications for nanomedicine, biomedical engineering, industrial and pharmaceutical fields.

Passive optical limiting studies of nanostructured Cu doped ZnO-PVA composite thin films

NASA Astrophysics Data System (ADS)

Tamgadge, Y. S.; Sunatkari, A. L.; Talwatkar, S. S.; Pahurkar, V. G.; Muley, G. G.

2016-01-01

We prepared undoped and Cu doped ZnO semiconducting nanoparticles (NPs) by chemical co-precipitation method and obtained Cu doped ZnO-polyvinyl alcohol (PVA) nanocomposite thin films by spin coating to investigate third order nonlinear optical and optical limiting properties under cw laser excitation. Powder samples of NPs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy, transmission electron microscopy, ultraviolet-visible (UV-vis) and Fourier transform infrared spectroscopy. XRD pattern and FE-SEM micrograph revealed the presence of hexagonal wurtzite phase ZnO NPs having uniform morphology with average particle size of 20 nm. The presence of excitons and absorption peaks in the range 343-360 nm, revealed by UV-vis study, were attributed to excitons in n = 1 quantum state. Third order NLO properties of all composite thin films were investigated by He-Ne continuous wave (cw) laser of wavelength 632.8 nm using Z-scan technique. Thermally stimulated enhanced values of nonlinear refraction and absorption coefficients were obtained which may be attributed to self-defocusing effect, reverse saturable absorption, weak free carrier absorption and surface states properties originated from thermo optic effect. Optical limiting properties have been studied using cw diode laser of wavelength 808 nm and results are presented.

Effects of Polishing Bur Application Force and Reuse on Sintered Zirconia Surface Topography.

PubMed

Fischer, N G; Tsujimoto, A; Baruth, A G

2018-03-16

Limited information is available on how to polish and finish zirconia surfaces following computer-aided design/computer-aided manufacturing (CAD/CAM), specifically, how differing application forces and reuse of zirconia polishing systems affect zirconia topography. To determine the effect of differing, clinically relevant, polishing application forces and multiple usages of polishing burs on the surface topography of CAD/CAM zirconia. One hundred twenty 220-grit carbide finished zirconia disks were sintered according to manufacturer's directions and divided into two groups for the study of two coarse polishing bur types. Each group was divided into subgroups for polishing (15,000 rpm) at 15 seconds for 1.0 N, 4.5 N, or 11 N of force using a purpose-built fixture. Subgroups were further divided to study the effects of polishing for the first, fifth, 15th, and 30th bur use, simulating clinical procedures. Unpolished surfaces served as a control group. Surfaces were imaged with noncontact optical profilometry (OP) and atomic force microscopy (AFM) to measure average roughness values (Ra). Polishing burs were optically examined for wear. Scanning electron microscopy (SEM) was performed on burs and zirconia surfaces. One-way ANOVA with post hoc Tukey HSD (honest significant difference) tests (α=0.05) were used for statistical analyses. AFM and OP Ra values of all polished surfaces were significantly lower than those of the unpolished control. Different polishing forces and bur reuse showed no significant differences in AFM Ra. However, significant differences in OP Ra were found due to differing application forces and bur reuse between the first and subsequent uses. SEM and optical micrographs revealed notable bur wear, increasing with increasing reuse. SEM and AFM micrographs clearly showed polished, periodic zirconia surfaces. Nanoscale topography, as analyzed with kurtosis and average groove depth, was found dependent on the specific polishing bur type. These in vitro results suggest changes in OP Ra due to bur reuse and polishing application force. Within the parameters of this study, the resultant topography of zirconia polishing is force-dependent and the reuse of coarse polishing burs is possible without statistically significant differences in Ra values after initial use. Nanoscale and microscale topography were shown to depend on specific polishing bur type.

Effect of Annealing Temperature on Microstructure and Mechanical Properties of Hot-Dip Galvanizing DP600 Steel

NASA Astrophysics Data System (ADS)

Hai-yan, Sun; Zhi-li, Liu; Yang, Xu; Jian-qiang, Shi; Lian-xuan, Wang

Hot-dip galvanizing dual phase steel DP600 steel grade with low Si was produced by steel plant and experiments by simulating galvanizing thermal history. The microstructure was observed and analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of different annealing temperatures on the microstructure and mechanical properties of dual-phase steel was also discussed. The experimental results show that the dual-phase steel possesses excellent strength and elongation that match EN10346 600MPa standards. The microstructure is ferrite and martensite. TEM micrograph shows that white ferrite with black martensite islands inlay with a diameter of around 1um and the content of 14 18%. The volume will expand and phase changing take the form of shear transformation when ferrite converted to martensite. So there are high density dislocations in ferrite crystalline grain near martensite. The martensite content growing will be obvious along with annealing temperature going up. But the tendency will be weak when temperature high.

Laser Cutting of Multilayered Kevlar Plates

NASA Astrophysics Data System (ADS)

Yilbas, B. S.; Al-Sulaiman, F.; Karakas, C.; Ahsan, M.

2007-12-01

Laser cutting of Kevlar plates, consisting of multilayered laminates, with different thicknesses are carried out. A mathematical model is developed to predict the kerf width, thermal efficiency, and specific energy requirements during cutting. Optical microscopy and Scanning Electron Microscopy (SEM) are employed to obtain the micrographs of the cutting sections. The kerf width size is measured and compared with the predictions. A factorial analysis is carried out to assess the affecting parameters on the mean kerf width and dimensionless damage sizes. It is found that the kerf width and damage sizes changes sharply when increasing cutting speed from 0.03 to 0.08 m/s. Thermal efficiency of the cutting process increases with increasing thickness and cutting speed while specific energy reduces with increasing thickness. The main effects of cutting parameters are found to be significant on the mean kerf width and dimensionless damage sizes, which is more pronounced for the workpiece bottom surface, where locally distributed char formation and sideways burning are observed.

The use of castor oil and ricinoleic acid in lead chalcogenide nanocrystal synthesis

NASA Astrophysics Data System (ADS)

Kyobe, Joseph W. M.; Mubofu, Egid B.; Makame, Yahya M. M.; Mlowe, Sixberth; Revaprasadu, Neerish

2016-08-01

A green solution-based thermolysis method for the synthesis of lead chalcogenide (PbE, E = S, Se, Te) nanocrystals in castor oil (CSTO) and its isolate ricinoleic acid (RA) is described. The blue shift observed from the optical spectra of CSTO and RA-capped PbE nanocrystals (NCs) confirmed the evidence of quantum confinement. The dimensions of PbE NCs obtained from NIR absorption spectra, transmission electron microscopy (TEM), and X-ray diffraction (XRD) studies were in good agreement. The particle sizes estimated were in the range of 20, 25, and 130 nm for castor oil-capped PbS, PbSe, and PbTe, respectively. Well-defined close to cubic-shaped particles were observed in the scanning electron microscopy (SEM) images of PbSe and PbTe nanocrystals. The high-resolution TEM and selective area electron diffraction (SAED) micrographs of the as-synthesized crystalline PbE NCs showed distinct lattice fringes with d-spacing distances corroborating with the standard values reported in literature.

3D reconstruction of SEM images by use of optical photogrammetry software.

PubMed

Eulitz, Mona; Reiss, Gebhard

2015-08-01

Reconstruction of the three-dimensional (3D) surface of an object to be examined is widely used for structure analysis in science and many biological questions require information about their true 3D structure. For Scanning Electron Microscopy (SEM) there has been no efficient non-destructive solution for reconstruction of the surface morphology to date. The well-known method of recording stereo pair images generates a 3D stereoscope reconstruction of a section, but not of the complete sample surface. We present a simple and non-destructive method of 3D surface reconstruction from SEM samples based on the principles of optical close range photogrammetry. In optical close range photogrammetry a series of overlapping photos is used to generate a 3D model of the surface of an object. We adapted this method to the special SEM requirements. Instead of moving a detector around the object, the object itself was rotated. A series of overlapping photos was stitched and converted into a 3D model using the software commonly used for optical photogrammetry. A rabbit kidney glomerulus was used to demonstrate the workflow of this adaption. The reconstruction produced a realistic and high-resolution 3D mesh model of the glomerular surface. The study showed that SEM micrographs are suitable for 3D reconstruction by optical photogrammetry. This new approach is a simple and useful method of 3D surface reconstruction and suitable for various applications in research and teaching. Copyright © 2015 Elsevier Inc. All rights reserved.

Preparation and Characterization of Carbon Filaments

DTIC Science & Technology

1991-04-01

Kawasumi, "Whiskerization of Carbon Beads by Vapor Phase Growth of Carbon Fibers to Obtain Sea Urchin -Type Particles", Carbon 21, 89 (1983). 5) R.T.K...multiple fiber microstructure are possible on what appears to be a single fiber along the length of the fiber. However, without SEM micrographs, it is...180 minutes. Scanning Electron Microscopic ( SEM ) observations were cared out using P Philips series 505 SEM system, typically operating at an

Co-Precipitation Synthesis and Characterization of SrBi2Ta2O9 Ceramic

NASA Astrophysics Data System (ADS)

Afqir, Mohamed; Tachafine, Amina; Fasquelle, Didier; Elaatmani, Mohamed; Carru, Jean-Claude; Zegzouti, Abdelouahad; Daoud, Mohamed

2018-04-01

Strontium bismuth tantalate (SrBi2Ta2O9) was synthesized by a co-precipitation method. The sample was characterized by x-ray powder diffraction patterns (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results of the dielectric properties are reported at room temperature. No secondary phases were found while heating the powder at 850°C and the pure SrBi2Ta2O9 phase was formed, as revealed by XRD. The characteristic bands for SrBi2Ta2O9 were observed by FTIR at approximately 619 cm-1 and 810 cm-1. SEM micrographs for the sample displayed thin plate-like grains. The grain size was less than 1 μm and the crystallite size of about 24 nm. Dielectric response at room temperature shows that the SrBi2Ta2O9 ceramic has low loss values, and the flattening of the dielectric constant at higher frequencies. The observed Curie temperature is comparable with those reported in the literature.

Combined Extraction Processes of Lipid from Chlorella vulgaris Microalgae: Microwave Prior to Supercritical Carbon Dioxide Extraction

PubMed Central

Dejoye, Céline; Vian, Maryline Abert; Lumia, Guy; Bouscarle, Christian; Charton, Frederic; Chemat, Farid

2011-01-01

Extraction yields and fatty acid profiles from freeze-dried Chlorella vulgaris by microwave pretreatment followed by supercritical carbon dioxide (MW-SCCO2) extraction were compared with those obtained by supercritical carbon dioxide extraction alone (SCCO2). Work performed with pressure range of 20–28 Mpa and temperature interval of 40–70 °C, gave the highest extraction yield (w/w dry weight) at 28 MPa/40 °C. MW-SCCO2 allowed to obtain the highest extraction yield (4.73%) compared to SCCO2 extraction alone (1.81%). Qualitative and quantitative analyses of microalgae oil showed that palmitic, oleic, linoleic and α-linolenic acid were the most abundant identified fatty acids. Oils obtained by MW-SCCO2 extraction had the highest concentrations of fatty acids compared to SCCO2 extraction without pretreatment. Native form, and microwave pretreated and untreated microalgae were observed by scanning electronic microscopy (SEM). SEM micrographs of pretreated microalgae present tearing wall agglomerates. After SCCO2, microwave pretreated microalgae presented several micro cracks; while native form microalgae wall was slightly damaged. PMID:22272135

Pretreatment of Wheat Bran for Suitable Reinforcement in Biocomposites

PubMed Central

Rahman, Atikur; Ulven, Chad A.; Johnson, Maren A.; Durant, Cheyenne; Hossain, Khwaja G.

2018-01-01

Wheat bran, abundant but underutilized, was investigated for its potential as a reinforcement in biocomposites through different pretreatment methods. Pretreatment methods included were dilute sodium hydroxide (NaOH), dilute sulfuric acid (H2SO4), liquid hot water (LHW), calcium hydroxide (CaOH), organosolv such as aqueous ethanol (EtOH), and methyl isobutyl ketone (MIBK). Changes in chemical composition and fiber characteristics of the treated bran were studied using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Cellulose content increased to 35.1% and 29.6% in brans treated with H2SO4 and NaOH, respectively. The SEM micrographs showed surface cleaning of treated bran while maintaining sufficient surface roughness for the H2SO4, NaOH, and MIBK treated brans. Crystallinity index increased slightly for all treatments except H2SO4. NaOH and H2SO4 pretreated brans achieved important fiber characteristics, which could be useful for making thermoplastic biocomposites. Innovative use of bran in thermoplastic will create more opportunities for growers while enhancing biodegradability. PMID:29417961

Combining autohydrolysis and ionic liquid microwave treatment to enhance enzymatic hydrolysis of Eucalyptus globulus wood.

PubMed

Rigual, Victoria; Santos, Tamara M; Domínguez, Juan Carlos; Alonso, M Virginia; Oliet, Mercedes; Rodriguez, Francisco

2018-03-01

The combination of autohydrolysis and ionic liquid microwave treatments of eucalyptus wood have been studied to facilitate sugar production in a subsequent enzymatic hydrolysis step. Three autohydrolysis conditions (150 °C, 175 °C and 200 °C) in combination with two ionic liquid temperatures (80 °C and 120 °C) were compared in terms of chemical composition, enzymatic digestibility and sugar production. Morphology was measured (using SEM) and the biomass surface was visualized with confocal fluorescence microscopy. The synergistic cooperation of both treatments was demonstrated, enhancing cellulose accessibility. At intermediate autohydrolysis conditions (175 °C) and low ionic liquid temperature (80 °C), a glucan digestibility of 84.4% was obtained. Using SEM micrographs, fractal dimension (as a measure of biomass complexity) and lacunarity (as a measure of homogeneity) were calculated before and after pretreatment. High fractals dimensions and low lacunarities correspond to morphologically complex and homogeneous samples, that are better digested by enzyme cocktails. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of Antibiotic-Loaded Alginate-Osa Starch Microbeads Produced by Ionotropic Pregelation

PubMed Central

Fontes, Gizele Cardoso; Calado, Verônica Maria Araújo; Rossi, Alexandre Malta; da Rocha-Leão, Maria Helena Miguez

2013-01-01

The aim of this study was to characterize the penicillin-loaded microbeads composed of alginate and octenyl succinic anhydride (OSA) starch prepared by ionotropic pregelation with calcium chloride and to evaluate their in vitro drug delivery profile. The beads were characterized by size, scanning electron microscopy (SEM), zeta potential, swelling behavior, and degree of erosion. Also, the possible interaction between penicillin and biopolymers was investigated by differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), and Fourier transform infrared (FTIR) analysis. The SEM micrograph results indicated a homogeneous drug distribution in the matrix. Also, based on thermal analyses (TGA/DSC), interactions were detected between microbead components. Although FTIR spectra of penicillin-loaded microbeads did not reveal the formation of new chemical entities, they confirmed the chemical drug stability. XRD patterns showed that the incorporated crystalline structure of penicillin did not significantly alter the primarily amorphous polymeric network. In addition, the results confirmed a prolonged penicillin delivery system profile. These results imply that alginate and OSA starch beads can be used as a suitable controlled-release carrier for penicillin. PMID:23862146

Understanding the shrinkage of optical absorption edges of nanostructured Cd-Zn sulphide films for photothermal applications

NASA Astrophysics Data System (ADS)

Hossain, Md. Sohrab; Kabir, Humayun; Rahman, M. Mahbubur; Hasan, Kamrul; Bashar, Muhammad Shahriar; Rahman, Mashudur; Gafur, Md. Abdul; Islam, Shariful; Amri, Amun; Jiang, Zhong-Tao; Altarawneh, Mohammednoor; Dlugogorski, Bogdan Z.

2017-01-01

In this article Cd-Zn sulphide thin films deposited onto soda lime glass substrates via chemical bath deposition (CBD) technique were investigated for photovoltaic applications. The synthesized films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet visible (UV-vis) spectroscopic methodologies. A higher degree of crystallinity of the films was attained with the increase of film thicknesses. SEM micrographs exhibited a partial crystalline structure with a particulate appearance surrounded by the amorphous grain boundaries. The optical absorbance and absorption coefficient of the films were also enhanced significantly with the increase in film thicknesses. Optical band-gap analysis indicated a monotonic decrease in direct and indirect band-gaps with the increase of thicknesses of the films. The presence of direct and indirect transitional energies due to the exponential falling edges of the absorption curves may either be due to the lack of long-range order or to the existence of defects in the films. The declination of the optical absorption edges was also confirmed via Urbach energy and steepness parameters studies.

Structure of first- and second-stage mineralized elements in teeth of the sea urchin Lytechinus variegatus.

PubMed

Robach, J S; Stock, S R; Veis, A

2009-12-01

Microstructure of the teeth of the sea urchin Lytechinus variegatus was investigated using optical microscopy, SEM (scanning electron microscopy) and SIMS (secondary ion mass spectroscopy). The study focused on the internal structure of the first-stage mineral structures of high Mg calcite (primary, secondary and carinar process plates, prisms) and on morphology of the columns of second-stage mineral (very high Mg calcite) that cement the first-stage material together. Optical micrographs under polarized light revealed contrast in the centers (midlines) of carinar process plates and in prisms in polished sections; staining of primary and carinar process plates revealed significant dye uptake at the plate centers. Demineralization with and without fixation revealed that the midlines of primary and carinar process plates (but not secondary plates) and the centers of prisms differed from the rest of the plate or prism, and SIMS showed proteins concentrated in these plate centers. SEM was used to study the morphology of columns, the fracture surfaces of mature teeth and the 3D morphology of prisms. These observations of internal structures in plates and prisms offer new insight into the mineralization process and suggest an important role for protein inclusions within the first-stage mineral. Some of the 3D structures not reported previously, such as twisted prisms and stacks of carinar process plates with nested wrinkles, may represent structural strengthening strategies.

Substrate bias induced synthesis of flowered-like bunched carbon nanotube directly on bulk nickel

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

Bisht, Atul; Academy of Scientific and Innovative Research; Chockalingam, S.

2016-02-15

Highlights: • Flowered-like bunched MWCNTs have been synthesized by MW PECVD technique. • Effect of substrate bias on the properties of MWCNT has been studied. • Minimum E{sub T} = 1.9 V/μm with β = 4770 has been obtained in the film deposited at −350 V. - Abstract: This paper reports the effect of substrate bias on the multiwalled carbon nanotube (MWCNT) deposited on nickel foil by microwave plasma enhanced chemical vapor deposition technique. The MWCNTs have been characterized by the scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy, field emission and current–voltage characteristic of themore » heterojunction diode. The SEM images exhibit unique hierarchical flowered-like bunched and conformally coated MWCNTs. Substrate bias induced ion bombardment helps in the enhancement of hydrocarbon dissociation and is responsible for flowered-like MWCNTs growth. The HRTEM micrographs show the base growth mechanism for MWCNTs. The value of turn on field for emission decreases from 5.5 to 1.9 V/μm and field enhancement factor increases from 927 to 4770, respectively, with the increase of substrate bias. The diode ideality factor of CNT/ n-Si heterojunction is evaluated as 2.4 and the on/off current ratio is found to be 7 at ±2 V, respectively.« less

Synthesis and Characterization of Chromate Conversion Coatings on GALVALUME and Galvanized Steel Substrates

NASA Astrophysics Data System (ADS)

Domínguez-Crespo, M. A.; Onofre-Bustamante, E.; Torres-Huerta, A. M.; Rodríguez-Gómez, F. J.; Rodil, S. E.; Flores-Vela, A.

2009-07-01

The morphology, composition, and corrosion performance of chromate conversion coatings (CCCs) formed on GALVALUME (Fe-Al-Zn) and galvanized steel (Fe-Zn) samples have been studied, and different immersion times (0, 10, 30, and 60 seconds) have been compared. The coated surfaces were analyzed using light microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical measurements in a NaCl solution (3 wt pct). The electrochemical measurements were carried out using the polarization resistance, Tafel, and ac impedance methods. A nonuniform growth of the CCCs having a porous morphology and cracks that appear extended to the base metal was observed. The XRD patterns show that the coatings mainly consist of CrO3, Cr2O3, and traces of Cr2O{7/-2}. The electrochemical results show that GALVALUME presents a better behavior than that of the galvanized steel alloys at each dipping time. The SEM micrographs show that the galvanized steel treatments resulted in the formation of a more uniform film, but their protection barrier broke down faster than that of the GALVALUME samples in contact with the aggressive media. The samples that underwent the lowest degree of dissolution were those with a dipping time of 30 seconds. The difference in the corrosion protection given by the two substrate types could be attributed to the structural properties, grain size, composition, and roughness, which affect oxygen diffusion.

Growth and characterization of PbSe and Pb{sub 1{minus}x}Sn{sub x}Se layers on Si (100)

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

Sachar, H.K.; Chao, I.; Fang, X.M.

1998-12-31

Crack-free layers of PbSe were grown on Si (100) by a combination of liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE) techniques. The PbSe layer was grown by LPE on Si(100) using a MBE-grown PbSe/BaF{sub 2}/CaF{sub 2} buffer layer structure. Pb{sub 1{minus}x}Sn{sub x}Se layers with tin contents in the liquid growth solution equal to 3%, 5%, 6%, 7%, and 10%, respectively, were also grown by LPE on Si(100) substrates using similar buffer layer structures. The LPE-grown PbSe and Pb{sub 1{minus}x}Sn{sub x}Se layers were characterized by optical Nomarski microscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electronmore » microscopy (SEM). Optical Nomarski characterization of the layers revealed their excellent surface morphologies and good growth solution wipe-offs. FTIR transmission experiments showed that the absorption edge of the Pb{sub 1{minus}x}Sn{sub x}Se layers shifted to lower energies with increasing tin contents. The PbSe epilayers were also lifted-off from the Si substrate by dissolving the MBE-grown BaF{sub 2} buffer layer. SEM micrographs of the cleaved edges revealed that the lifted-off layers formed structures suitable for laser fabrication.« less

Structure of first- and second-stage mineralized elements in teeth of the sea urchin Lytechinus variegatus

PubMed Central

Robach, J. S.; Stock, S. R.; Veis, A.

2009-01-01

Microstructure of the teeth of the sea urchin Lytechinus variegatus was investigated using optical microscopy, SEM (scanning electron microscopy) and SIMS (secondary ion mass spectroscopy). The study focused on the internal structure of the first-stage mineral structures of high Mg calcite (primary, secondary and carinar process plates; prisms) and on morphology of the columns of second-stage mineral (very high Mg calcite) that cement the first-stage material together. Optical micrographs under polarized light revealed contrast in the centers (midlines) of carinar process plates and in prisms in polished sections; staining of primary and carinar process plates revealed significant dye uptake at the plate centers. Demineralization with and without fixation revealed that the midlines of primary and carinar process plates (but not secondary plates) and the centers of prisms differed from the rest of the plate or prism, and SIMS showed proteins concentrated in these plate centers. SEM was used to study the morphology of columns, the fracture surfaces of mature teeth and the 3D morphology of prisms. These observations of internal structures in plates and prisms offer new insight into the mineralization process and suggest an important role for protein inclusions within the first-stage mineral. Some of the 3D structures not reported previously, such as twisted prisms and stacks of carinar process plates with nested wrinkles, may represent structural strengthening strategies. PMID:19616101

Flexible magnetic membranes based on bacterial cellulose and its evaluation as electromagnetic interference shielding material.

PubMed

Marins, Jéssica A; Soares, Bluma G; Barud, Hernane S; Ribeiro, Sidney J L

2013-10-01

Flexible magnetic membranes with high proportion of magnetite were successfully prepared by previous impregnation of the never dried bacterial cellulose pellicles with ferric chloride followed by reduction with sodium bisulfite and alkaline treatment for magnetite precipitation. Membranes were characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating magnetometer, field emission scanning electron microscopy (FEG-SEM) and impedance spectroscopy. Microwave properties of these membranes were investigated in the X-band (8.2 to 12.4 GHz). FEG-SEM micrographs show an effective coverage of the BC nanofibers by Fe3O4 nanoparticles. Membranes with up to 75% in weight of particles have been prepared after 60 min of reaction. Magnetite nanoparticles in the form of aggregates well adhered to the BC fibers were observed by SEM. The average crystal sizes of the magnetic particles were in the range of 10±1 to 13±1 nm (estimated by XRD). The magnetic particles in the BC pellicles presented superparamagnetic behavior with a saturation magnetization in the range of 60 emu g(-1) and coercive force around 15 Oe. These magnetic pellicles also displayed high electrical permittivity and a potential application as microwave absorber materials. Copyright © 2013 Elsevier B.V. All rights reserved.

A comparative scanning electron microscopy evaluation of smear layer removal with apple vinegar and sodium hypochlorite associated with EDTA

PubMed Central

CANDEIRO, George Táccio de Miranda; de MATOS, Isabela Barbosa; da COSTA, Clarice Fernandes Eloy; FONTELES, Cristiane Sá Roriz; do VALE, Mônica Sampaio

2011-01-01

Objective The purpose of this study was to evaluate by scanning electron microscopy (SEM) the removal of smear layer from the middle and apical root thirds after use of different irrigating solutions. Material and Methods Forty roots of permanent human teeth had their canals instrumented and were randomly assigned to 4 groups (n=10), according to the irrigating solution: apple vinegar (group A), apple vinegar finished with 17% ethylenediaminetetraacetic acid (EDTA) (group B), 1% sodium hypochlorite (NaOCl) finished with 17% EDTA (group C) and saline (group D - control). After chemomechanical preparation, the roots were cleaved longitudinally and their middle and apical thirds were examined by SEM at ×1,000 magnification. Two calibrated examiners (kappa=0.92) analyzed the SEM micrographs qualitatively attributing scores that indicated the efficacy of the solutions in removing the smear layer from the surface of the dentin tubules (1 - poor, 2 - good and 3 - excellent). Data from the control and experimental groups were analyzed by the Kruskal-Wallis and Dunn's test, while the Wilcoxon test was used to compare the middle and apical thirds of the canals within the same group (α=0.05). Results The middle third presented less amount of smear layer than the apical third, regardless of the irrigant. There was statistically significant difference (p=0.0402) among the groups in the middle third. In the apical third, the apple vinegar/EDTA group showed the greatest removal of smear layer (p=0.0373). Conclusion Apple vinegar associated or not with EDTA was effective in removing smear layer when used as an endodontic irrigant. PMID:22231000

FIB/SEM and SEM/EDS microstructural analysis of metal-ceramic and zirconia-ceramic interfaces.

PubMed

Massimi, F; Merlati, G; Sebastiani, M; Battaini, P; Menghini, P; Bemporad, E

2012-01-10

Recently introduced FIB/SEM analysis in microscopy seems to provide a high-resolution characterization of the samples by 3D (FIB) cross-sectioning and (SEM) high resolution imaging. The aim of this study was to apply the FIB/SEM and SEM/EDS analysis to the interfaces of a metal-ceramic vs. two zirconia-ceramic systems. Plate samples of three different prosthetic systems were prepared in the dental lab following the manufacturers' instructions, where metal-ceramic was the result of a ceramic veneering (porcelain-fused-to-metal) and the two zirconia-ceramic systems were produced by the dedicated CAD-CAM procedures of the zirconia cores (both with final sintering) and then veneered by layered or heat pressed ceramics. In a FIB/SEM equipment (also called DualBeam), a thin layer of platinum (1 μm) was deposited on samples surface crossing the interfaces, in order to protect them during milling. Then, increasingly deeper trenches were milled by a focused ion beam, first using a relatively higher and later using a lower ion current (from 9 nA to 0.28 nA, 30KV). Finally, FEG-SEM (5KV) micrographs (1000-50,000X) were acquired. In a SEM the analysis of the morphology and internal microstructure was performed by 13KV secondary and backscattered electrons signals (in all the samples). The compositional maps were then performed by EDS probe only in the metal-ceramic system (20kV). Despite the presence of many voids in all the ceramic layers, it was possible to identify: (1) the grain structures of the metallic and zirconia substrates, (2) the thin oxide layer at the metal-ceramic interface and its interactions with the first ceramic layer (wash technique), (3) the roughness of the two different zirconia cores and their interactions with the ceramic interface, where the presence of zirconia grains in the ceramic layer was reported in two system possibly due to sandblasting before ceramic firing.

Fabrication and Characterization of novel W80Ni10Nb10 alloy produced by mechanical alloying

NASA Astrophysics Data System (ADS)

Saxena, R.; Patra, A.; Karak, S. K.; Pattanaik, A.; Mishra, S. C.

2016-02-01

Nanostructured tungsten (W) based alloy with nominal composition of W80Ni10Nb10 (in wt. %) was synthesized by mechanical alloying of elemental powders of tungsten (W), nickel (Ni), niobium (Nb) in a high energy planetary ball-mill for 20 h using chrome steel as grinding media and toluene as process control agent followed by compaction at 500 MPa pressure for 5 mins and sintering at 1500°C for 2 h in Ar atmosphere. The phase evolution and the microstructure of the milled powder and consolidated product were investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The crystallite size of W in W80Ni10Nb10 powder was reduced from 100 μm at 0 h to 45.6 nm at 10 h and 34.1 nm at 20 h of milling whereas lattice strain increases to 35% at 20 h of milling. The dislocation density shows sharp increase up to 5 h of milling and the rate of increase drops beyond 5 to 20 h of milling. The lattice parameter of tungsten in W80Ni10Nb10 expanded upto 0.04% at 10 h of milling and contracted upto 0.02% at 20 h of milling. The SEM micrograph revealed the presence of spherical and elongated particles in W80Ni10Nb10 powders at 20 h of milling. The particle size decreases from 100 μm to 2 μm with an increase in the milling time from 0 to 20 hours. The crystallite size of W in milled W80Ni10Nb10 alloy as evident from bright field TEM image was in well agreement with the measured crystallite size from XRD. Structure of W in 20 h milled W80Ni10Nb10 alloy was identified by indexing of selected area diffraction (SAD) pattern. Formation of NbNi intermetallic was evident from XRD pattern and SEM micrograph of sintered alloy. Maximum sinterability of 90.8% was achieved in 20 h milled sintered alloy. Hardness and wear study was also conducted to investigate the mechanical behaviour of the sintered product. Hardness of W80Ni10Nb10 alloy reduces with increasing load whereas wear rate increases with increasing load. The evaluated hardness value in the present study for all loads is lower than the literature reported hardness of nanostructured W.

Microstructural, mechanical and electrochemical behaviour of a 7017 Al–Zn–Mg alloy of different tempers

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

Rout, Prasanta Kumar, E-mail: prasantonnet55@yahoo.com; Ghosh, M.M.; Ghosh, K.S., E-mail: ksghosh2001@yahoo.co.uk

2015-06-15

The aim of the investigation is to assess the microstructural features and associated physical, mechanical and electrochemical properties of a 7017 Al–Zn–Mg alloy of various tempers. A 7017 Al–Zn–Mg alloy was subjected to different ageing schedules to produce under-(T4), peak-(T6), over-(T7) and highly over-aged tempers. Optical microscopy, hardness measurement, electrical conductivity measurement, tensile testing and SEM fractographs, differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and electrochemical polarization studies have been used to characterize the alloy tempers. Hardness measurement and tensile testing showed the characteristic age hardening phenomenon of aluminium alloys. Optical and TEM micrographs have revealed the variation inmore » size of matrix strengthening η′ (MgZn{sub 2}) and also the size and distribution of grain boundary η (MgZn{sub 2}) precipitate with ageing time. DSC thermograms exhibiting exothermic and endothermic peaks indicated the characteristic solid state reaction sequence of the 7017 alloy. Potentiodynamic polarization study of the 7017 alloy of various tempers in 3.5 wt.% NaCl solution at near neutral pH showed typical active metal dissolution behaviour, but at pH 12 an active–passive–transpassive transition behaviour has been observed. - Graphical abstract: TEM micrograph of the 7017 aluminium alloy of various tempers (a, b) under aged (T4), (c, d) peak aged (T6), (e, f) over aged (T7) and (g, h) highly over-aged. Display Omitted - Highlights: • 7017 Al-Zn-Mg alloy was subjected to different artificial ageing treatments. • Characterization of 7017 alloy tempers by hardness, tensile, DSC, TEM and electrochemical behaviour. • Structure-properties relationship of the 7017 Al-Zn-Mg alloy of various tempers.« less

Structural and morphological study of Zn0.9Mn0.05Fe0.05O synthesized by sol-gel wet chemical precipitation route

NASA Astrophysics Data System (ADS)

Jain, S. K.; Dolia, S. N.; Choudhary, B. L.; Prashant, B. L.

2018-04-01

Transition metal substituted Zinc oxide (ZnO) has drawn a great deal of attention due to its excellent properties. Zn0.9Mn0.05Fe0.05O sample synthesized was by Sol-gel wet chemical precipitation route at temperature 350°C. The crystallinity and the structure of Zn0.9Mn0.05Fe0.05O was determined by X-ray diffraction by Cu-Kα radiations operated at 40kV and 35mA in the range of 20° to 80°. The pattern gets indexed in wurtzite (hexagonal) structure with lattice constants a=b=3.2525Å and c=5.2071Å and approves the single phase material with no impurity. The values of particle size assessed by Debye Scherer’s (DS) formula lie in the range of 13nm to 33nm indicating the nano-crystalline nature of the sample. The morphological analysis of the sample was performed by Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) measurements. The observed size of Zn0.9Mn0.05Fe0.05O nanoparticles by TEM micrograph exhibits the similar trend with the size calculated by Debye-Scherer formula. TEM image show the irregular shape of the nanoparticles and particle size lies in the range of 10-35nm. Similar to SEM image, the slight agglomeration of the nanoparticles have been observed from TEM.

Understanding the formation and growth of Ag nanoparticles on silver chromate induced by electron irradiation in electron microscope: A combined experimental and theoretical study

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

Fabbro, Maria T.; Department of Inorganic and Organic Chemistry, Universitat Jaume I, Campus del Riu Sec, E-12071 Castellón; Gracia, Lourdes

Ag{sub 2}CrO{sub 4} microcrystals were synthesized using the co-precipitation method. These microcrystals were characterized through X-ray diffraction (XRD) with Rietveld analysis, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) with energy-dispersive spectroscopy (EDS), micro-Raman (MR). XRD patterns and Rietveld refinement data showed that the material exhibits an orthorhombic structure without any deleterious phases. FE-SEM and TEM micrographs revealed the morphology and the growth of Ag nanoparticles on Ag{sub 2}CrO{sub 4} microcrystals during electron beam irradiation. These events were directly monitored in real-time. Their optical properties were investigated using ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy that allowed the calculation of themore » optical band gap energy. Theoretical analyses based on the density functional theory level indicate that the incorporation of electrons is responsible for structural modifications and formation of defects on the [AgO{sub 6}] and [AgO{sub 4}] clusters, generating ideal conditions for the growth of Ag nanoparticles. - Graphical abstract: Theoretical representation of the Ag{sub 2}CrO{sub 4} orthorhombic structure. Display Omitted - Highlights: • The Ag{sub 2}CrO{sub 4} microcrystals indicate an orthorhombic structure. • The formation of Ag{sup 0} promotes Ag-nanoparticle growth on the surface of the Ag{sub 2}CrO{sub 4}. • Electron irradiation of the material induces the formation of Ag vacancies.« less

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

Laguna, O.; Collar, E.P.; Taranco, J.

Observations are made about microstructural aspects from HDPE and LDPE homopolymers and their blends as virgin materials and also from urban plastic wastes. Micrographs were taken by SEM. Micrographs corresponding to the fracture surface from specimens tested in an impact test clearly show different microstructural features due to polymer which is more than 50%. Parts were injection molded. A discussion is given about crystallization behavior of those materials obtained by DSC. For all blends the same results have been found, i.e., two peaks owing to each of the two polymers which are present in the blends.

Phonon Avoided and Scalable Cascade Lasers (PASCAL)

DTIC Science & Technology

2008-11-01

up We fully developed the mask-less nanolithography technique. The SEM micrographs show that highly uniform nanoholes and nanopillars array can be...by the technique and we produced a large area of high uniform nanoholes perforated in Al films, which is a big step towards making quantum dot...spheres on photoresist ’ • A. W A - " > EN • • • ^Ti—i Figure 14 - SEM images series showing nanoholes generated with

Characterization of airborne particles in an open pit mining region.

PubMed

Huertas, José I; Huertas, María E; Solís, Dora A

2012-04-15

We characterized airborne particle samples collected from 15 stations in operation since 2007 in one of the world's largest opencast coal mining regions. Using gravimetric, scanning electron microscopy (SEM-EDS), and X-ray photoelectron spectroscopy (XPS) analysis the samples were characterized in terms of concentration, morphology, particle size distribution (PSD), and elemental composition. All of the total suspended particulate (TSP) samples exhibited a log-normal PSD with a mean of d=5.46 ± 0.32 μm and σ(ln d)=0.61 ± 0.03. Similarly, all particles with an equivalent aerodynamic diameter less than 10 μm (PM(10)) exhibited a log-normal type distribution with a mean of d=3.6 ± 0.38 μm and σ(ln d)=0.55 ± 0.03. XPS analysis indicated that the main elements present in the particles were carbon, oxygen, potassium, and silicon with average mass concentrations of 41.5%, 34.7%, 11.6%, and 5.7% respectively. In SEM micrographs the particles appeared smooth-surfaced and irregular in shape, and tended to agglomerate. The particles were typically clay minerals, including limestone, calcite, quartz, and potassium feldspar. Copyright © 2012 Elsevier B.V. All rights reserved.

Studies on Structural, Optical, Thermal and Electrical Properties of Perylene-Doped p-terphenyl Luminophors.

PubMed

Desai, Netaji K; Mahajan, Prasad G; Bhopate, Dhanaji P; Dalavi, Dattatray K; Kamble, Avinash A; Gore, Anil H; Dongale, Tukaram D; Kolekar, Govind B; Patil, Shivajirao R

2018-01-01

A simple solid state reaction technique was employed for the preparation of polycrystalline luminophors of p-terphenyl containing different amounts of perylene followed by spectral characterization techniques viz. XRD, SEM, TGA-DSC, UV-Visible spectroscopy, thermo-electrical conductivity, fluorescence spectroscopy, fluorescence life time spectroscopy and temperature dependent fluorescence. X-ray diffraction profiles of the doped p-terphenyl reveal well-defined and sharp peaks indicate homogeneity and crystallinity. The SEM micrograph of pure p-terphenyl exhibit flakes like grains and then compact and finally gets separately with perylene amounts. The observed results indicate that closed packed crystal structures of doped p-terphenyl during crystal formation. The band gaps estimated from UV-visible spectroscopy decreased from 5.20 to 4.10 eV, while thermo-electrical conductivity increases with perylene content. The fluorescence spectra showed partial quenching of p-terphenyl fluorescence and simultaneously sensitization of perylene fluorescence at the excitation wavelength of p-terphenyl (290 nm) due to excitation energy transfer from p-terphenyl to perylene. The observed sensitization results are in harmony with intense blue color seen in fluorescence microscopy images and has high demand in scintillation process.

Crystal growth in zinc borosilicate glasses

NASA Astrophysics Data System (ADS)

Kullberg, Ana T. G.; Lopes, Andreia A. S.; Veiga, João P. B.; Monteiro, Regina C. C.

2017-01-01

Glass samples with a molar composition (64+x)ZnO-(16-x)B2O3-20SiO2, where x=0 or 1, were successfully synthesized using a melt-quenching technique. Based on differential thermal analysis data, the produced glass samples were submitted to controlled heat-treatments at selected temperatures (610, 615 and 620 °C) during various times ranging from 8 to 30 h. The crystallization of willemite (Zn2SiO4) within the glass matrix was confirmed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Under specific heat-treatment conditions, transparent nanocomposite glass-ceramics were obtained, as confirmed by UV-vis spectroscopy. The influence of temperature, holding time and glass composition on crystal growth was investigated. The mean crystallite size was determined by image analysis on SEM micrographs. The results indicated an increase on the crystallite size and density with time and temperature. The change of crystallite size with time for the heat-treatments at 615 and 620 °C depended on the glass composition. Under fixed heat-treatment conditions, the crystallite density was comparatively higher for the glass composition with higher ZnO content.

Structural properties and optical characterization of flower-like Mg doped NiO

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

Allaedini, Ghazaleh, E-mail: jiny-ghazaleh@yahoo.com; Tasirin, Siti Masrinda; Aminayi, Payam

In this study, un-doped and Mg doped NiO nanoparticles have been synthesized through a simple sol-gel method. To investigate the effect of Mg-doping on the structure of NiO, the obtained nanoparticles were characterized using scanning electron microscopy (SEM). Flower/star like morphology was clearly observed in the SEM micrographs. The BET (Brunauer-Emmett-Teller) nitrogen absorption isotherm exhibits high specific surface area (∼37 m{sup 2} /g) for the Mg doped NiO nanoparticles. X-Ray diffraction (XRD) of the prepared Mg-NiO nanoparticles showed a face-centered cubic (f.c.c) structure, and the average particle size was estimated to be 32 nm using Scherrer’s formula. Energy Dispersive X-Ray (EDX)more » confirms that the NiO particles are successfully doped with Mg. Photoluminescence (PL) and UV-Vis optical absorption characteristics of the prepared nanoparticles have also been investigated in this study. The PL emission response showed a blue shift when NiO was doped with Mg, which is indicative of interstitial oxygen. The UV-Vis results demonstrate a band gap increase as NiO nanoparticles are doped with Mg.« less

Glycolysis of carbon fiber-epoxy unidirectional mat catalysed by sodium hydroxide

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

Zaini, Mariana Binti Mohd; Badri, Khairiah Haji

2014-09-03

This study was conducted to recycle carbon fibre-epoxy (CFRP) composite in woven sheet/ mat form. The CFRP was recycled through glycolysis with polyethlyene glycol (PEG 200) as the solvent. The CFRP was loaded into the solvent at a ratio of 4:1 (w/w). PEG200 was diluted with water to a ratio of 80:20 (v/v). This reaction was catalysed by sodium hydroxide (NaOH) solution with varying concentrations at 1.5, 1.7 and 1.9% (w/v). The glycolysis was conducted at 180-190 °C. The recovered CF (rCF) was analysed using Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) while themore » degraded solution was analysed using FTIR and the epoxy content was determined. The FTIR spectrum of the rCF exhibited the disappearance of the COC peak belonged to epoxy and supported by the SEM micrographs that showed clear rCF. On the other hand, the analysed filtrate detected the disappearance of oxygen peak element in the EDX spectrum for all rCF samples. This gave an indication that the epoxy resin has been removed from the surface of the carbon fiber.« less

Glycolysis of carbon fiber-epoxy unidirectional mat catalysed by sodium hydroxide

NASA Astrophysics Data System (ADS)

Zaini, Mariana Binti Mohd; Badri, Khairiah Haji

2014-09-01

This study was conducted to recycle carbon fibre-epoxy (CFRP) composite in woven sheet/ mat form. The CFRP was recycled through glycolysis with polyethlyene glycol (PEG 200) as the solvent. The CFRP was loaded into the solvent at a ratio of 4:1 (w/w). PEG200 was diluted with water to a ratio of 80:20 (v/v). This reaction was catalysed by sodium hydroxide (NaOH) solution with varying concentrations at 1.5, 1.7 and 1.9% (w/v). The glycolysis was conducted at 180-190 °C. The recovered CF (rCF) was analysed using Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) while the degraded solution was analysed using FTIR and the epoxy content was determined. The FTIR spectrum of the rCF exhibited the disappearance of the COC peak belonged to epoxy and supported by the SEM micrographs that showed clear rCF. On the other hand, the analysed filtrate detected the disappearance of oxygen peak element in the EDX spectrum for all rCF samples. This gave an indication that the epoxy resin has been removed from the surface of the carbon fiber.

Inorganic particle analysis of dental impression elastomers.

PubMed

Carlo, Hugo Lemes; Fonseca, Rodrigo Borges; Soares, Carlos José; Correr, Américo Bortolazzo; Correr-Sobrinho, Lourenço; Sinhoreti, Mário Alexandre Coelho

2010-01-01

The aim of this study was to determine quantitatively and qualitatively the inorganic particle fraction of commercially available dental elastomers. The inorganic volumetric fraction of two addition silicones (Reprosil Putty/Fluid and Flexitime Easy Putty/Fluid), three condensation silicones (Clonage Putty/Fluid, Optosil Confort/Xantopren VL and Silon APS Putty/Fluid), one polyether (Impregum Soft Light Body) and one polysulfide (Permlastic Light Body) was accessed by weighing a previously determined mass of each material in water before and after burning samples at 600 ºC, during 3 h. Unsettled material samples were soaked in acetone and chloroform for removal of the organic portion. The remaining filler particles were sputter-coated with gold evaluation of their morphology and size, under scanning electron microscopy (SEM). Flexitime Easy Putty was the material with the highest results for volumetric particle fraction, while Impregum Soft had the lowest values. Silon 2 APS Fluid presented the lowest mean filler size values, while Clonage Putty had the highest values. SEM micrographs of the inorganic particles showed several morphologies - lathe-cut, spherical, spherical-like, sticks, and sticks mixed to lathe-cut powder. The results of this study revealed differences in particle characteristics among the elastometic materials that could lead to different results when testing mechanical properties.

Transformation of toxic and allelopathic lantana into a benign organic fertilizer through vermicomposting

NASA Astrophysics Data System (ADS)

Hussain, Naseer; Abbasi, Tasneem; Abbasi, S. A.

2016-06-01

In a first study of its kind, the composition of vermicompost derived solely from the toxic and allelopathic weed lantana has been investigated using UV-visible and Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric (TG) and differential scanning calorimetry (DSC), gas chromatography-mass spectometry (GC-MS), and scanning electron microscopy (SEM). The studies reveal that a sharp reduction in humification index, substantial mineralization of organic matter and degradation of complex aromatics such as lignin and polyphenols into simpler carbohydrates and lipids occur in the course of vermicomposting. GC-MS analysis shows significant fragmentation, bio-oxidation and molecular rearrangements of chemical compounds in vermicompost in comparison to those in lantana. SEM micrographs of vermicompost reflect strong disaggregation of material compared to the much better formed lantana matrices. The phenols and sesquiterpene lactones which are specifically responsible for the toxicity and allelopathy of lantana are seen to get significantly degraded in the course of vermicomposting - turning it into a plant-friendly organic fertilizer. The study leads to the possibility that the millions of tons of phytomass that is generated annually by lantana can be gainfully utilized in producing organic fertilizer via vermicomposting.

Synthesis and characterization of magnesium aluminate (MgAl2O4) spinel (MAS) thin films

NASA Astrophysics Data System (ADS)

Ahmad, Syed Muhammad; Hussain, Tousif; Ahmad, Riaz; Siddiqui, Jamil; Ali, Dilawar

2018-01-01

In a quest to identify more economic routes for synthesis of magnesium aluminate (MgAl2O4) spinel (MAS) thin films, dense plasma focus device was used with multiple plasma focus shots. Structural, bonding between composite films, surface morphological, compositional and hardness properties of MAS thin films were investigated by using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive x-rays (EDX) analysis and Vickers micro hardness test respectively. In XRD graph, the presence of MgAl2O4 diffraction peaks in crystallographic orientations (222), (400) and (622) pointed out the successful formation of polycrystalline thin films of MgAl2O4 with face centered cubic structure. The FTIR spectrums showed a major common transmittance band at 697.95 cm-1 which belongs to MgAl2O4. SEM micrographs illustrated a mesh type, granular and multi layers microstructures with significant melting effects. EDX spectrum confirmed the existence of magnesium, oxygen and aluminum in MAS films. A common increasing behavior in micro-hardness of composite MgAl2O4 films by increasing number of plasma focus shots was found.

FibrilJ: ImageJ plugin for fibrils' diameter and persistence length determination

NASA Astrophysics Data System (ADS)

Sokolov, P. A.; Belousov, M. V.; Bondarev, S. A.; Zhouravleva, G. A.; Kasyanenko, N. A.

2017-05-01

Application of microscopy to evaluate the morphology and size of filamentous proteins and amyloids requires new and creative approaches to simplify and automate the image processing. The estimation of mean values of fibrils diameter, length and bending stiffness on micrographs is a major challenge. For this purpose we developed an open-source FibrilJ plugin for the ImageJ/FiJi program. It automatically recognizes the fibrils on the surface of a mica, silicon, gold or formvar film and further analyzes them to calculate the distribution of fibrils by diameters, lengths and persistence lengths. The plugin has been validated by the processing of TEM images of fibrils formed by Sup35NM yeast protein and artificially created images of rod-shape objects with predefined parameters. Novel data obtained by SEM for Sup35NM protein fibrils immobilized on silicon and gold substrates are also presented and analyzed.

Study of structural, spectroscopic and dielectric properties of multiferroic cadmium doped Samarium manganite synthesized by solid state reaction method

NASA Astrophysics Data System (ADS)

Gupta, Vandana; Raina, Bindu; Verma, Seema; Bamzai, K. K.

2018-05-01

Samarium manganite doped with cadmium having general formula Sm1-xCdxMnO3 for x = 0.05, 0.15 were synthesized by solid state reaction technique. These compositions were characterized by various techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and dielectric. XRD analysis confirms the single phase formation with pervoskites structure having orthorhombic phase. Densities were determined and compared with the results obtained by Archimedes principle. The scanning electron micrograph shows that the particle size distribution is almost homogeneous and spherical in shape. FTIR analysis confirms the presence of various atomic bonds within a molecule. A very large value of dielectric constant was observed at low frequencies due to the presence of grains and interfaces. The dielectric constant value decreases with increase in cadmium doping at samarium site.

Evaluation of intracameral injection of ranibizumab and bevacizumab on the corneal endothelium by scanning electron microscopy.

PubMed

Ari, Seyhmus; Nergiz, Yusuf; Aksit, Ihsan; Sahin, Alparslan; Cingu, Kursat; Caca, Ihsan

2015-03-01

To evaluate the effects of intracameral injection of ranibizumab and bevacizumab on the corneal endothelium by scanning electron microscopy (SEM). Twenty-eight female rabbits were randomly divided into four equal groups. Rabbits in groups 1 and 2 underwent intracameral injection of 1 mg/0.1 mL and 0.5 mg/0.05 mL ranibizumab, respectively; group 3 was injected with 1.25 mg/0.05 mL bevacizumab. All three groups were injected with a balanced salt solution (BSS) into the anterior chamber of the left (fellow) eye. None of the rabbits in group 4 underwent an injection. Corneal thickness and intraocular pressure were measured before the injections, on the first day, and in the first month after injection. The rabbits were sacrificed and corneal tissues were excised in the first month after injection. Specular microscopy was used for the corneal endothelial cell count. Endothelial cell density was assessed and comparisons drawn between the groups and the control. Micrographs were recorded for SEM examination. The structure of the corneal endothelial cells, the junctional area of the cell membrane, the distribution of microvillus, and the cell morphology of the eyes that underwent intracameral injection of vascular endothelial growth factor (VEGF), BSS, and the control group were compared. Corneal thickness and intraocular pressure were not significantly different between the groups that underwent anti-VEGF or BSS injection and the control group on the first day and in the first month of injection. The corneal endothelial cell count was significantly diminished in all three groups; predominantly in group 1 and 2 (P<0.05). The SEM examination revealed normal corneal endothelial histology in group 3 and the control group. Eyes in group 1 exhibited indistinctness of corneal endothelial cell borders, microvillus loss in the luminal surface, excessive blebbing, and disintegration of intercellular junctions. In group 2, the cell structure of the corneal endothelium and intercellular junctions were normal. However, a relative reduction was observed in the microvillus density of endothelial cells. Although eyes in group 3 were morphologically similar to fellow eyes and the control group, disarrangement in endothelial cell borders was evident. The SEM examination pointed out deterioration in endothelial cell morphology after intracameral injection of 1 and 0.5 mg ranizumab. However, the effects of intracameral bevacizumab injection on corneal endothelial cells were similar to those found in fellow eyes and the control group. Further large-scale studies that examine the cellular changes by transmission electron microscopy are required to support the results of the present study that evaluates the structural changes in endothelial cells by SEM.

Synthesis of nanocrystalline diamonds by microwave plasma

NASA Astrophysics Data System (ADS)

Purohit, V. S.; Jain, Deepti; Sathe, V. G.; Ganesan, V.; Bhoraskar, S. V.

2007-03-01

Nanocrystalline diamonds, varying in size from 40 to 400 nm, with random faceting were grown without the help of initial nucleation sites on nickel substrates as seen by scanning electron micrographs. These carbonaceous films were deposited in a microwave plasma reactor using hexane/nitrogen based chemical vapour deposition. The substrate temperatures during deposition were varied from 400 to 600 °C. The morphological investigations obtained by scanning electron micrographs and atomic force microscopy revealed the presence of nanocrystallites with multifaceted structures. Micro Raman investigations were carried out on the deposited films, which conclusively inferred that the growth of nanodiamond crystallites seen in the scanning electron micrographs correlate with clear Raman peaks appearing at 1120 and 1140 cm-1. Nanoindentation analysis with atomic force microscopy has revealed that the carbonaceous deposition identified by the Raman line at ~1140 cm-1, in fact, is related to nanodiamond on account of its hardness which was ~30 GPa. X-ray diffraction data supported this fact.

Fabrication of high-performance supercapacitors based on transversely oriented carbon nanotubes

NASA Astrophysics Data System (ADS)

Markoulidis, F.; Lei, C.; Lekakou, C.

2013-04-01

High-performance supercapacitors with organic electrolyte 1 M TEABF4 (tetraethyl ammonium tetrafluoroborate) in PC (propylene carbonate) were fabricated and tested, based on multiwall carbon nanotubes (MWNTs) deposited by electrophoresis on three types of alternative substrates: aluminium foil, ITO (indium tin oxide) coated PET (polyethylene terephthalate) film and PET film. In all cases, SEM (scanning electron microscopy) and STEM (scanning transmission electron microscopy) micrographs demonstrated that protruding, transversely oriented MWNT structures were formed, which should increase the transverse conductivity of these MWNT electrodes. The best supercapacitor cell of MWNT electrodes deposited on aluminium foil displayed good transverse orientation of the MWNT structures as well as an in-plane MWNT network at the feet of the protruding structures, which ensured good in-plane conductivity. Capacitor cells with MWNT electrodes deposited either on ITO-coated PET film or on PET film demonstrated lower but still very good performance due to the high density of transversely oriented MWNT structures (good transverse conductivity) but some in-plane inhomogeneities. Capacitor cells with drop-printed MWNTs on aluminium foil, without any transverse orientation, had 16-30 times lower specific capacitance and 5-40 times lower power density than the capacitor cells with the electrophoretically deposited MWNT electrodes.

A novel route for synthesis of nanocrystalline hydroxyapatite from eggshell waste.

PubMed

Siva Rama Krishna, D; Siddharthan, A; Seshadri, S K; Sampath Kumar, T S

2007-09-01

The eggshell waste has been value engineered to a nanocrystalline hydroxyapatite (HA) by microwave processing. To highlight the advantages of eggshell as calcium precursor in the synthesis of HA (OHA), synthetic calcium hydroxide was also used to form HA (SHA) following similar procedure and were compared with a commercially available pure HA (CHA). All the HAs were characterized by X-ray powder diffraction (XRD) method, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and specific surface area measurements. Nanocrystalline nature of OHA is revealed through characteristic broad peaks in XRD patterns, platelets of length 33-50 nm and width 8-14 nm in TEM micrograph and size calculations from specific surface area measurements. FT-IR spectra showed characteristic bands of HA and additionally peaks of carbonate ions. The cell parameter calculations suggest the formation of carbonated HA of B-type. The OHA exhibits superior sinterability in terms of hardness and density than both SHA and CHA may be due to larger surface area of its spherulite structure. The in vitro dissolution study shows longer stability in phosphate buffer and cell culture test using osteoblast cells establishes biocompatibility of OHA.

Stability and Synergistic Effect of Polyaniline/TiO₂ Photocatalysts in Degradation of Azo Dye in Wastewater.

PubMed

Gilja, Vanja; Novaković, Katarina; Travas-Sejdic, Jadranka; Hrnjak-Murgić, Zlata; Roković, Marijana Kraljić; Žic, Mark

2017-11-23

The polyaniline/TiO₂ (PANI/TiO₂) composite photocatalysts were prepared by the in situ chemical oxidation of aniline (An) in the presence of TiO₂ particles. For this purpose, photocatalysts with different amounts of PANI polymer were prepared and analysed. Fourier-transform infrared (FT-IR) spectroscopy and thermogravimetric (TG) analysis indicated successful synthesis of the PANI polymer and its conductivity was also determined. The micrographs of field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were used to explain the impact of the aniline amount on the aggregation process during the synthesis of the composites. The smallest size of aggregates was obtained for the photocatalysts with 15% of PANI (15PANI/TiO₂) due to the formation of homogenous PANI. The photocatalytic activity of studied PANI/TiO₂ photocatalysts was validated by monitoring the discoloration and mineralization of Reactive Red azo dye (RR45) in wastewater. The 15PANI/TiO₂ sample presented the highest photocatalytic efficiency under ultraviolet A (UVA) irradiation, in comparison to pure TiO₂. This was explained by the formation of uniformly dispersed PANI on the TiO₂ particles, which was responsible for the synergistic PANI-TiO₂ effect.

CoO doping effects on the ZnO films through EBPDV technique

NASA Astrophysics Data System (ADS)

Inês Basso Bernardi, Maria; Queiroz Maia, Lauro June; Antonelli, Eduardo; Mesquita, Alexandre; Li, Maximo Siu; Gama, Lucianna

2014-03-01

Nanometric Zn1-xCo xO (x = 0.020, 0.025 and 0.030 in mol.%) nanopowders were obtained from low temperature calcination of a resin prepared using the Pechini's method. Firing the Zn1-xCoxO resin at 400 °C/2 h a powder with hexagonal structure was obtained as measured by X-ray diffraction (XRD). The powder presented average particle size of 40 nm observed by field emission scanning electronic microscopy (FE-SEM) micrographs and average crystallite size of 10 nm calculated from the XRD using Scherrer's equation. Nanocrystalline Zn1-xCo xO films with good homogeneity and optical quality were obtained with 280-980 nm thicknesses by electron beam physical vapour deposition (EBPVD) under vacuum onto silica substrate at 25 °C. Scanning electron microscopy with field emission gun showed that the film microstructure is composed by spherical grains and some needles. In these conditions of deposition the films presented only hexagonal phase observed by XRD. The UV-visible-NIR and diffuse reflectance properties of the films were measured and the electric properties were calculated using the reflectance and transmittance spectra.

Structural, magnetic and electronic structure properties of Co doped ZnO nanoparticles

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

Kumar, Shalendra, E-mail: shailuphy@gmail.com; School of Materials Science and Engineering, Changwon National University, Changwon, Gyeongnam 641-773; Song, T.K., E-mail: tksong@changwon.ac.kr

Highlights: • XRD and HR-TEM results show the single phase nature of Co doped ZnO nanoparticles. • XMCD and dc magnetization results indicate the RT-FM in Co doped ZnO nanoparticles. • Co L{sub 3,2} NEXAFS spectra infer that Co ions are in 2+ valence state. • O K edge NEXAFS spectra show that O vacancy increases with Co doping in ZnO. - Abstract: We reported structural, magnetic and electronic structure studies of Co doped ZnO nanoparticles. Doping of Co ions in ZnO host matrix has been studied and confirmed using various methods; such as X-ray diffraction (XRD), field emission scanningmore » electron microscopy (FE-SEM), energy dispersed X-ray (EDX), high resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, magnetic hysteresis loop measurements and X-ray magnetic circular dichroism (XMCD). From the XRD and HR-TEM results, it is observed that Co doped ZnO nanoparticles have single phase nature with wurtzite structure and exclude the possibility of secondary phase formation. FE-SEM and TEM micrographs show that pure and Co doped nanoparticles are nearly spherical in shape. O K edge NEXAFS spectra indicate that O vacancies increase with Co doping. The Co L{sub 3,2} edge NEXAFS spectra revealed that Co ions are in 2+ valence state. DC magnetization hysteresis loops and XMCD results clearly showed the intrinsic origin of temperature ferromagnetism in Co doped ZnO nanoparticles.« less

Surfactant mediated hydrothermal synthesis, characterization and luminescent properties of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} core shell nanorods

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

Khajuria, Heena; Ladol, Jigmet; Khajuria, Sonika

Highlights: • Core shell nanorods were synthesised by surfactant assisted hydrothermal method. • Morphology of core shell nanorods resembles those of core nanorods indicating coating of shell on cores. • More uniform and non-aggregated core shell nanorods were prepared in presence of surfactants. • Surfactant assisted prepared core shell nanorods show intense emission as compared to uncoated core nanorods. - Abstract: Core shell GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} nanorods were synthesized via hydrothermal route in the presence of different surfactants [cetyltrimethyl ammonium bromide (CTAB) and Sodium dodecyl sulphate (SDS)]. The nanorods were characterized by powder X-ray diffractionmore » (PXRD), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and photoluminescence (PL) studies. The X-ray diffraction results indicate good crystallinity and effective doping in core and core shell nanorods. SEM and TEM micrographs show that all of the as prepared gadolinium phosphate products have rod like shape. The compositional analysis of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} core was done by EDS. The emission intensity of the GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} @ GdPO{sub 4} core shell increased significantly with respect to those of GdPO{sub 4}: Ce{sup 3+}/Tb{sup 3+} core nanorods. The effect of surfactant on the uniformity, thickness and luminescence of the core shell nanorods was investigated.« less

Inserting ex vivo fluorescence confocal microscopy perioperatively in Mohs micrographic surgery expedites bedside assessment of excision margins in recurrent basal cell carcinoma.

PubMed

Longo, Caterina; Ragazzi, Moira; Castagnetti, Fabio; Gardini, Stefano; Palmieri, Tamara; Lallas, Aimilios; Moscarella, Elvira; Piana, Simonetta; Pellacani, Giovanni; Zalaudek, Iris; Argenziano, Giuseppe

2013-01-01

Mohs micrographic surgery can be employed in recurrent basal cell carcinoma, although it is a time-consuming technique. Recently, ex vivo fluorescence confocal microscopy (FCM) has been employed to obtain a fast assessment of tumor margins at the bedside. In our case we successfully employed ex vivo FCM to assess the tumor margins and we treated the persistent tumor with intensity-modulated radiation therapy. Our case demonstrates that a multidisciplinary approach is very efficient in managing complex and recurrent tumors and highlights the benefits of FCM as a new technique that can be used in the surgical theater to speed up the entire procedure.

Damage of Escherichia coli membrane by bactericidal agent polyhexamethylene guanidine hydrochloride: micrographic evidences.

PubMed

Zhou, Z X; Wei, D F; Guan, Y; Zheng, A N; Zhong, J J

2010-03-01

The purpose of this study was to provide micrographic evidences for the damaged membrane structure and intracellular structure change of Escherichia coli strain 8099, induced by polyhexamethylene guanidine hydrochloride (PHMG). The bactericidal effect of PHMG on E. coli was investigated based on beta-galactosidase activity assay, fluorescein-5-isothiocyanate confocal laser scanning microscopy, field emission scanning electron microscopy and transmission electron microscopy. The results revealed that a low dose (13 microg ml(-1)) of PHMG slightly damaged the outer membrane structure of the treated bacteria and increased the permeability of the cytoplasmic membrane, while no significant damage was observed to the morphological structure of the cells. A high dose (23 microg ml(-1)) of PHMG collapsed the outer membrane structure, led to the formation of a local membrane pore across the membrane and badly damaged the internal structure of the cells. Subsequently, intracellular components were leaked followed by cell inactivation. Dose-dependent membrane disruption was the main bactericidal mechanism of PHMG. The formation of the local membrane pores was probable after exposure to a high dose (23 microg ml(-1)) of PHMG. Micrographic evidences were provided about the damaged membrane structure and intracellular structure change of E. coli. The presented information helps understand the bactericidal mechanism of PHMG by membrane damage.

Surface modification of cellulose acetate membrane using thermal annealing to enhance produced water treatment

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

Kusworo, T. D., E-mail: tdkusworo@che.undip.ac.id; Aryanti, N., E-mail: nita.aryanti@gmail.com; Firdaus, M. M. H.

2015-12-29

This study is performed primarily to investigate the effect of surface modification of cellulose acetate using thermal annealing on the enhancement of membrane performance for produced water treatment. In this study, Cellulose Acetate membranes were casted using dry/wet phase inversion technique. The effect of additive and post-treatment using thermal annealing on the membrane surface were examined for produced water treatment. Therma annealing was subjected to membrane surface at 60 and 70 °C for 5, 10 and 15 second, respectively. Membrane characterizations were done using membrane flux and rejection with produced water as a feed, Scanning Electron Microscopy (SEM) and Fouriermore » Transform Infra Red (FTIR) analysis. Experimental results showed that asymmetric cellulose acetate membrane can be made by dry/wet phase inversion technique. The results from the Scanning Electron Microscopy (FESEM) analysis was also confirmed that polyethylene glycol as additivie in dope solution and thermal annealing was affected the morphology and membrane performance for produced water treatment, respectively. Scanning electron microscopy micrographs showed that the selective layer and the substructure of membrane became denser and more compact after the thermal annealing processes. Therefore, membrane rejection was significantly increased while the flux was slighty decreased, respectively. The best membrane performance is obtained on the composition of 18 wt % cellulose acetate, poly ethylene glycol 5 wt% with thermal annealing at 70° C for 15 second.« less

Impact Strength and Flexural Properties Enhancement of Methacrylate Silane Treated Oil Palm Mesocarp Fiber Reinforced Biodegradable Hybrid Composites

PubMed Central

Ibrahim, Nor Azowa; Ariffin, Hidayah; Yunus, Wan Md. Zin Wan

2014-01-01

Natural fiber as reinforcement filler in polymer composites is an attractive approach due to being fully biodegradable and cheap. However, incompatibility between hydrophilic natural fiber and hydrophobic polymer matrix restricts the application. The current studies focus on the effects of incorporation of silane treated OPMF into polylactic acid (PLA)/polycaprolactone (PCL)/nanoclay/OPMF hybrid composites. The composites were prepared by melt blending technique and characterize the composites with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR spectra indicated that peak shifting occurs when silane treated OPMF was incorporated into hybrid composites. Based on mechanical properties results, incorporation of silane treated OPMF enhances the mechanical properties of unmodified OPMF hybrid composites with the enhancement of flexural and impact strength being 17.60% and 48.43%, respectively, at 10% fiber loading. TGA thermogram shows that incorporation of silane treated OPMF did not show increment in thermal properties of hybrid composites. SEM micrographs revealed that silane treated OPMF hybrid composites show good fiber/matrix adhesion as fiber is still embedded in the matrix and no cavity is present on the surface. Water absorption test shows that addition of less hydrophilic silane treated OPMF successfully reduces the water uptake of hybrid composites. PMID:25254230

Laser micro-processing of amorphous and partially crystalline Cu45Zr48Al7 alloy

NASA Astrophysics Data System (ADS)

Aqida, S. N.; Brabazon, D.; Naher, S.; Kovacs, Z.; Browne, D. J.

2010-11-01

This paper presents a microstructural study of laser micro-processed high-purity Cu45Zr48Al7 alloys prepared by arc melting and Cu-mould casting. Microprocessing of the Cu45Zr48Al7 alloy was performed using a Rofin DC-015 diffusion-cooled CO2 slab laser system with 10.6-μm wavelength. The laser was defocused to a spot size of 0.2 mm on the sample surface. The laser parameters were set to give 300- and 350-W peak power, 30% duty cycle and a 3000-Hz laser pulse repetition frequency (PRF). About 100-micrometer-wide channels were scribed on the surfaces of disk-shaped amorphous and partially crystalline samples at traverse speeds of 500 and 5000 mm/min. These channels were analysed using scanning electron microscopy (SEM) and 2D stylus profilometry. The metallographic study and profile of these processed regions are discussed in terms of the applied laser processing parameters. The SEM micrographs showed that striation marks developed at the edge and inside these regions as a result of the laser processing. The results from this work showed that microscale features can be produced on the surface of amorphous Cu-Zr-Al alloys by CO2 laser processing.

The effects of fuel type in synthesis of NiFe2O4 nanoparticles by microwave assisted combustion method

NASA Astrophysics Data System (ADS)

Karcıoğlu Karakaş, Zeynep; Boncukçuoğlu, Recep; Karakaş, İbrahim H.

2016-04-01

In this study, it was investigated the effects of the used fuels on structural, morphological and magnetic properties of nanoparticles in nanoparticle synthesis with microwave assisted combustion method with an important method in quick, simple and low cost at synthesis of the nanoparticles. In this aim, glycine, urea and citric acid were used as fuel, respectively. The synthesised nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmet-Teller surface area (BET), and vibrating sample magnetometry (VSM) techniques. We observed that fuel type is quite effective on magnetic properties and surface properties of the nanoparticles. X-ray difractograms of the obtained nanoparticles were compared with standard powder diffraction cards of NiFe2O4 (JCPDS Card Number 54-0964). The results demonstrated that difractograms are fully compatible with standard reflection peaks. According to the results of the XRD analysis, the highest crystallinity was observed at nanoparticles synthesized with glycine. The results demonstrated that the nanoparticles prepared with urea has the highest surface area. The micrographs of SEM showed that all of the nanoparticles have nano-crystalline behaviour and particles indication cubic shape. VSM analysis demonstrated that the type of fuel used for synthesis is highly effective a parameter on magnetic properties of nanoparticles.

Using SEM-EDX and ICP-OES to investigate the elemental composition of green macroalga Vaucheria sessilis.

PubMed

Michalak, Izabela; Marycz, Krzysztof; Basińska, Katarzyna; Chojnacka, Katarzyna

2014-01-01

The biomass of Vaucheria sessilis forms algal mats in many freshwaters. There is a need to find the method of algal biomass utilization. Vaucheria sessilis is a rich source of micro- and macronutrients and can be used as a soil amendment. In the paper, the elemental composition of enriched, via bioaccumulation process, macroalga was investigated. For this purpose, two independent techniques were used: scanning electron microscopy with an energy dispersive X-ray analytical system (SEMEDX) and inductively coupled plasma optical emission spectroscopy (ICP-OES). The biomass was exposed to two microelemental solutions, with Cu(II) and Zn(II) ions. After two weeks of the experiment, macroalga accumulated 98.5 mg of Zn(II) ions in 1 g of dry biomass and 68.9 mg g(-1) of Cu(II) ions. Micrographs performed by SEM proved that bioaccumulation occurred. Metal ions were bound on the surface and in the interior of cells. Mappings of all cations showed that in the case of the surface of biomass (biosorption), the elements constituted aggregations and in the case of the cross section (bioaccumulation) they were evenly distributed. The algal biomass with permanently bound microelements can find an application in many branches of the industry (feed, natural fertilizers, etc.).

Preparation and characterization of bagasse/HDPE composites using multi-walled carbon nanotubes.

PubMed

Ashori, Alireza; Sheshmani, Shabnam; Farhani, Foad

2013-01-30

This article presents the preparation and characterization of bagasse/high density polyethylene (HDPE) composites. The effects of multi-walled carbon nanotubes (MWCNTs), as reinforcing agent, on the mechanical and physical properties were also investigated. In order to increase the interphase adhesion, maleic anhydride grafted polyethylene (MAPE) was added as a coupling agent to all the composites studied. In the sample preparation, MWCNTs and MAPE contents were used as variable factors. The morphology of the specimens was characterized using scanning electron microscopy (SEM) technique. The results of strength measurement indicated that when 1.5 wt% MWCNTs were added, tensile and flexural properties reached their maximum values. At high level of MWCNTs loading (3 or 4 wt%), increased population of MWCNTs lead to agglomeration and stress transfer gets blocked. The addition of MWCNTs filler slightly decreased the impact strength of composites. Both mechanical and physical properties were improved when 4 wt% MAPE was applied. SEM micrographs also showed that the surface roughness improved with increasing MAPE loading from 0 to 4 wt%. The improvement of physicomechanical properties of composites confirmed that MWCNTs have good reinforcement and the optimum synergistic effect of MWCNTs and MAPE was achieved at the combination of 1.5 and 4 wt%, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

Porous Silicon Covered with Silver Nanoparticles as Surface-Enhanced Raman Scattering (SERS) Substrate for Ultra-Low Concentration Detection.

PubMed

Kosović, Marin; Balarin, Maja; Ivanda, Mile; Đerek, Vedran; Marciuš, Marijan; Ristić, Mira; Gamulin, Ozren

2015-12-01

Microporous and macro-mesoporous silicon templates for surface-enhanced Raman scattering (SERS) substrates were produced by anodization of low doped p-type silicon wafers. By immersion plating in AgNO3, the templates were covered with silver metallic film consisting of different silver nanostructures. Scanning electron microscopy (SEM) micrographs of these SERS substrates showed diverse morphology with significant difference in an average size and size distribution of silver nanoparticles. Ultraviolet-visible-near-infrared (UV-Vis-NIR) reflection spectroscopy showed plasmonic absorption at 398 and 469 nm, which is in accordance with the SEM findings. The activity of the SERS substrates was tested using rhodamine 6G (R6G) dye molecules and 514.5 nm laser excitation. Contrary to the microporous silicon template, the SERS substrate prepared from macro-mesoporous silicon template showed significantly broader size distribution of irregular silver nanoparticles as well as localized surface plasmon resonance closer to excitation laser wavelength. Such silver morphology has high SERS sensitivity that enables ultralow concentration detection of R6G dye molecules up to 10(-15) M. To our knowledge, this is the lowest concentration detected of R6G dye molecules on porous silicon-based SERS substrates, which might even indicate possible single molecule detection.

Impact strength and flexural properties enhancement of methacrylate silane treated oil palm mesocarp fiber reinforced biodegradable hybrid composites.

PubMed

Eng, Chern Chiet; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Ariffin, Hidayah; Yunus, Wan Md Zin Wan

2014-01-01

Natural fiber as reinforcement filler in polymer composites is an attractive approach due to being fully biodegradable and cheap. However, incompatibility between hydrophilic natural fiber and hydrophobic polymer matrix restricts the application. The current studies focus on the effects of incorporation of silane treated OPMF into polylactic acid (PLA)/polycaprolactone (PCL)/nanoclay/OPMF hybrid composites. The composites were prepared by melt blending technique and characterize the composites with Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR spectra indicated that peak shifting occurs when silane treated OPMF was incorporated into hybrid composites. Based on mechanical properties results, incorporation of silane treated OPMF enhances the mechanical properties of unmodified OPMF hybrid composites with the enhancement of flexural and impact strength being 17.60% and 48.43%, respectively, at 10% fiber loading. TGA thermogram shows that incorporation of silane treated OPMF did not show increment in thermal properties of hybrid composites. SEM micrographs revealed that silane treated OPMF hybrid composites show good fiber/matrix adhesion as fiber is still embedded in the matrix and no cavity is present on the surface. Water absorption test shows that addition of less hydrophilic silane treated OPMF successfully reduces the water uptake of hybrid composites.

Epicuticular Wax Crystals of Wollemia nobilis: Morphology and Chemical Composition

PubMed Central

Dragota, Simona; Riederer, Markus

2007-01-01

Background and Aims The morphology of the epicuticular leaf waxes of Wollemia nobilis (Araucariaceae) was studied with special emphasis on the relationship between the microstructure of epicuticular wax crystals and their chemical composition. Wollemia nobilis is a unique coniferous tree of the family Araucariaceae and is of very high scientific value as it is the sole living representative of an ancient genus, which until 1994 was known only from fossils. Methods Scanning electron microscopy (SEM), gas chromatography (GC) combined with mass spectrometry (GC–MS) and nuclear magnetic resonance spectroscopy (NMR) were used for characterizing the morphology and the chemical structure of the epicuticular wax layer of W. nobilis needles. Key Results The main component of the leaf epicuticular wax of W. nobilis is nonacosan-10-ol. This secondary alcohol together with nonacosane diols is responsible for the tubular habit of the epicuticular wax crystals. Scanning electron micrographs revealed differences in the fine structure of adaxial and abaxial leaf surfaces that could be explained by gas chromatographic studies after selective mechanical removal of the waxes. Conclusions SEM investigations established the tubular crystalline microstructure of the epicuticular wax of W. nobilis leaves. GC–MS and NMR experiments showed that nonacosan-10-ol is the major constituent of the epicuticular wax of W. nobilis leaves. PMID:17611192

Preparation and study of (1 - x)CuFe2O4-xBaTiO3 (x = 0, 0.1 and 1) composite multiferroics

NASA Astrophysics Data System (ADS)

Murtaza, Tahir; Ali, Javid; Khan, M. S.

2018-07-01

The parent and mixed spinel-perovskite composite of (1 - x)CuFe2O4-xBaTiO3 (x = 0, 0.1 and 1) has been prepared by solid-state reaction method and studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy, magnetometry and P-E lope tracer. The XRD results showed the formation of single phase tetragonal spinel CuFe2O4 and tetragonal perovskite BaTiO3 at room temperature, further XRD of composite 0.1CuFe2O4-0.9BaTiO3 reflects the two crystallographic phases with 1:9 ratio. The SEM micrographs show the homogeneous and uniform formation of the samples. Through EDAX analysis, the chemical composition of the sample is found to be same as the nominal composition. The high field Mossbauer data of CuFe2O4 sample shows the ferrimagnetic ordering in the sample. The observed M-H and P-E loops of the composite 0.1CuFe2O4-0.9BaTiO3 sample show the presence of spontaneous magnetization and spontaneous electric polarization indicating the multiferroic nature of the sample.

Kinetic modeling of simultaneous saccharification and fermentation of corn starch for ethanol production.

PubMed

Białas, Wojciech; Czerniak, Adrian; Szymanowska-Powałowska, Daria

2014-01-01

Fuel ethanol production, using a simultaneous saccharification and fermentation process (SSF) of native starch from corn flour, has been performed using Saccharomyces cerevisiae and a granular starch hydrolyzing enzyme. The quantitative effects of mash concentration, enzyme dose and pH were investigated with the use of a Box-Wilson central composite design protocol. Proceeding from results obtained in optimal fermentation conditions, a kinetics model relating the utilization rates of starch and glucose as well as the production rates of ethanol and biomass was tested. Moreover, scanning electron microscopy (SEM) was applied to investigate corn starch granule surface after the SFF process. A maximum ethanol concentration of 110.36 g/l was obtained for native corn starch using a mash concentration of 25%, which resulted in ethanol yield of 85.71%. The optimal conditions for the above yield were found with an enzyme dose of 2.05 ml/kg and pH of 5.0. These results indicate that by using a central composite design, it is possible to determine optimal values of the fermentation parameters for maximum ethanol production. The investigated kinetics model can be used to describe SSF process conducted with granular starch hydrolyzing enzymes. The SEM micrographs reveal randomly distributed holes on the surface of granules.

In Vitro-In Vivo Relationship of Amorphous Insoluble API (Progesterone) in PLGA Microspheres.

PubMed

Pu, Chenguang; Wang, Qiao; Zhang, Hongjuan; Gou, Jingxin; Guo, Yuting; Tan, Xinyi; Xie, Bin; Yin, Na; He, Haibing; Zhang, Yu; Wang, Yanjiao; Yin, Tian; Tang, Xing

2017-12-01

The mechanism of PRG release from PLGA microspheres was studied and the correlation of in vitro and in vivo analyses was assessed. PRG-loaded microspheres were prepared by the emulsion-evaporate method. The physical state of PRG and microstructure changings during the drug release period were evaluated by powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) respectively. Pharmacokinetic studies were performed in male Sprague-Dawley rats, and the in vivo-in vitro correlation (IVIVC) was established by linear fitting of the cumulative release (%) in vitro and fraction of absorption (%) in vivo. PXRD results indicated recrystallization of PRG during release. The changes of microstructure of PRG-loaded microspheres during the release period could be observed in SEM micrographs. Pharmacokinetics results performed low burst-release followed a steady-released manner. The IVIVC assessment exhibited a good correlation between vitro and in vivo. The burst release phase was caused by diffusion of amorphous PRG near the surface, while the second release stage was impacted by PRG-dissolution from crystal depots formed in microspheres. The IVIVC assessment suggests that the in vitro test method used in this study could predict the real situation in vivo and is helpful to study the release mechanism in vivo.

Effect of stacking angles on mechanical properties and damage propagation of plain woven carbon fiber laminates

NASA Astrophysics Data System (ADS)

Zhuang, Weimin; Ao, Wenhong

2018-03-01

Damage propagation induced failure is a predominant damage mechanism. This study is aimed at assessing the damage state and damage propagation induced failure with different stacking angles, of woven carbon fiber/epoxy laminates subjected to quasi-static tensile and bending load. Different stages of damage processing and damage behavior under the bending load are investigated by Scanning Electron Microscopy (SEM). The woven carbon fiber/epoxy laminates which are stacked at six different angles (0°, 15°, 30°, 45°, 60°, 75°) with eight plies have been analyzed: [0]8, [15]8, [30]8, [45]8, [60]8, [75]8. Three-point bending test and quasi-static tensile test are used in validating the woven carbon fiber/epoxy laminates’ mechanical properties. Furthermore, the damage propagation and failure modes observed under flexural loading is correlated with flexural force and load-displacement behaviour respectively for the laminates. The experimental results have indicated that [45]8 laminate exhibits the best flexural performance in terms of energy absorption duo to its pseudo-ductile behaviour but the tensile strength and flexural strength drastically decreased compared to [0]8 laminate. Finally, SEM micrographs of specimens and fracture surfaces are used to reveal the different types of damage of the laminates with different stacking angles.

Using SEM-EDX and ICP-OES to Investigate the Elemental Composition of Green Macroalga Vaucheria sessilis

PubMed Central

Michalak, Izabela; Marycz, Krzysztof; Basińska, Katarzyna; Chojnacka, Katarzyna

2014-01-01

The biomass of Vaucheria sessilis forms algal mats in many freshwaters. There is a need to find the method of algal biomass utilization. Vaucheria sessilis is a rich source of micro- and macronutrients and can be used as a soil amendment. In the paper, the elemental composition of enriched, via bioaccumulation process, macroalga was investigated. For this purpose, two independent techniques were used: scanning electron microscopy with an energy dispersive X-ray analytical system (SEMEDX) and inductively coupled plasma optical emission spectroscopy (ICP-OES). The biomass was exposed to two microelemental solutions, with Cu(II) and Zn(II) ions. After two weeks of the experiment, macroalga accumulated 98.5 mg of Zn(II) ions in 1 g of dry biomass and 68.9 mg g−1 of Cu(II) ions. Micrographs performed by SEM proved that bioaccumulation occurred. Metal ions were bound on the surface and in the interior of cells. Mappings of all cations showed that in the case of the surface of biomass (biosorption), the elements constituted aggregations and in the case of the cross section (bioaccumulation) they were evenly distributed. The algal biomass with permanently bound microelements can find an application in many branches of the industry (feed, natural fertilizers, etc.). PMID:25180212

Functionalization of surfactant wrapped graphenenanosheets with alkylazides for enhanced dispersibility

NASA Astrophysics Data System (ADS)

Vadukumpully, Sajini; Gupta, Jhinuk; Zhang, Yongping; Xu, Guo Qin; Valiyaveettil, Suresh

2011-01-01

A facile and simple approach for the covalent functionalization of surfactant wrapped graphene sheets is described. The approach involves functionalization of dispersible graphene sheets with various alkylazides and 11-azidoundecanoic acid proved the best azide for enhanced dispersibility. The functionalization was confirmed by infrared spectroscopy and scanning tunneling microscopy. The free carboxylic acidgroups can bind to gold nanoparticles, which were introduced as markers for the reactive sites. The interaction between gold nanoparticles and the graphene sheets was followed by UV-vis spectroscopy. The gold nanoparticle-graphene composite was characterized by transmission electron microscopy and atomic force microscopy, demonstrating the uniform distribution of gold nanoparticles all over the surface. Our results open the possibility to control the functionalization on graphene in the construction of composite nanomaterials.A facile and simple approach for the covalent functionalization of surfactant wrapped graphene sheets is described. The approach involves functionalization of dispersible graphene sheets with various alkylazides and 11-azidoundecanoic acid proved the best azide for enhanced dispersibility. The functionalization was confirmed by infrared spectroscopy and scanning tunneling microscopy. The free carboxylic acidgroups can bind to gold nanoparticles, which were introduced as markers for the reactive sites. The interaction between gold nanoparticles and the graphene sheets was followed by UV-vis spectroscopy. The gold nanoparticle-graphene composite was characterized by transmission electron microscopy and atomic force microscopy, demonstrating the uniform distribution of gold nanoparticles all over the surface. Our results open the possibility to control the functionalization on graphene in the construction of composite nanomaterials. Electronic Supplementary Information (ESI) available: Synthesis and characterization details of dodecylazide, hexylazide, 11-azidoundecanol (AUO), micrographs (SEM and TEM images) of the various azide functionalized samples and the statistical analysis of the graphene thickness. See 10.1039/c0nr00547a.

Electrical properties of palladium-doped CaCu3Ti4O12 ceramics

NASA Astrophysics Data System (ADS)

Singh, Arashdeep; Md Mursalin, Sk.; Rana, P.; Sen, Shrabanee

2015-09-01

The effect of doping palladium (Pd) at the Cu site of CaCu3Ti4O12 powders (CCPTO) synthesized by sol-gel technique on electrical properties was studied. XRD analysis revealed the formation of CCTO and CCPTO ceramics with some minor quantities of impurities. SEM micrographs revealed that the grain size decreased with Pd doping. TEM micrographs of CCPTO powder showed the formation of irregular-shaped particles of ~40 nm. The dielectric constant and dielectric loss showed a significant enhancement with Pd doping. A significant decrease in grain-boundary resistance with Pd doping was ascertained by impedance spectroscopy study.

Enamel alteration following tooth bleaching and remineralization.

PubMed

Coceska, Emilija; Gjorgievska, Elizabeta; Coleman, Nichola J; Gabric, Dragana; Slipper, Ian J; Stevanovic, Marija; Nicholson, John W

2016-06-01

The purpose of this study was to compare the effects of professional tooth whitening agents containing highly concentrated hydrogen peroxide (with and without laser activation), on the enamel surface; and the potential of four different toothpastes to remineralize any alterations. The study was performed on 50 human molars, divided in two groups: treated with Opalescence(®) Boost and Mirawhite(®) Laser Bleaching. Furthermore, each group was divided into five subgroups, a control one and 4 subgroups remineralized with: Mirasensitive(®) hap+, Mirawhite(®) Gelleѐ, GC Tooth Mousse™ and Mirafluor(®) C. The samples were analysed by SEM/3D-SEM-micrographs, SEM/EDX-qualitative analysis and SEM/EDX-semiquantitative analysis. The microphotographs show that both types of bleaching cause alterations: emphasized perikymata, erosions, loss of interprizmatic substance; the laser treatment is more aggressive and loss of integrity of the enamel is determined by shearing off the enamel rods. In all samples undergoing remineralization deposits were observed, those of toothpastes based on calcium phosphate technologies seem to merge with each other and cover almost the entire surface of the enamel. Loss of integrity and minerals were detected only in the line-scans of the sample remineralized with GC Tooth Mousse™. The semiquantitative EDX analysis of individual elements in the surface layer of the enamel indicates that during tooth-bleaching with HP statistically significant loss of Na and Mg occurs, whereas the bleaching in combination with a laser leads to statistically significant loss of Ca and P. The results undoubtedly confirm that teeth whitening procedures lead to enamel alterations. In this context, it must be noted that laser bleaching is more aggressive for dental substances. However, these changes are reversible and can be repaired by application of remineralization toothpastes. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Energy Harvesting and Storage Systems for Future AF Vehicles

DTIC Science & Technology

2012-05-18

mechanical testing setup/procedures to determine the Young’s modulus and fracture strength of solar energy harvesting modules. Figure D1 SEM micrograph of...failure modes. (4 configurations; 2 repetitions) Table D3. Summary of mechanical testing activity The goal of the test is to determine the fracture ...

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

LPG ammonia and nitrogen dioxide gas sensing properties of nanostructured polypyrrole thin film

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

Bagul, Sagar B., E-mail: nano.sbbagul@gmail.com; Upadhye, Deepak S.; Sharma, Ramphal, E-mail: rps.phy@gmail.com

Nanostructured Polypyrrole thin film was synthesized by easy and economic chemical oxidative polymerization technique on glass at room temperature. The prepared thin film of Polypyrrole was characterized by optical absorbance study by UV-visible spectroscopy and electrical study by I-V measurement system. The optical absorbance spectrum of Polypyrrole shows two fundamental peaks in region of 420 and 890 nm, which confirms the formation of Polypyrrole on glass substrate. The I-V graph of nanostructured Polypyrrole represents the Ohmic nature. Furthermore, the thin film of Polypyrrole was investigated by Scanning electron microscopy for surface morphology study. The SEM micrograph represents spherical nanostructured morphology ofmore » Polypyrrole on glass substrate. In order to investigate gas sensing properties, 100 ppm of LPG, Ammonia and Nitrogen Dioxide were injected in the gas chamber and magnitude of resistance has been recorded as a function of time in second. It was observed that nanostructured Polypyrrole thin film shows good sensing behavior at room temperature.« less

Effects of formulation variables and characterization of guaifenesin wax microspheres for controlled release.

PubMed

Mani, Narasimhan; Park, M O; Jun, H W

2005-01-01

Sustained-release wax microspheres of guaifenesin, a highly water-soluble drug, were prepared by the hydrophobic congealable disperse method using a salting-out procedure. The effects of formulation variables on the loading efficiency, particle properties, and in-vitro drug release from the microspheres were determined. The type of dispersant, the amount of wetting agent, and initial stirring time used affected the loading efficiency, while the volume of external phase and emulsification speed affected the particle size of the microspheres to a greater extent. The crystal properties of the drug in the wax matrix and the morphology of the microspheres were studied by differential scanning calorimetry (DSC), powder x-ray diffraction (XRD), and scanning electron microscopy (SEM). The DSC thermograms of the microspheres showed that the drug lost its crystallinity during the microencapsulation process, which was further confirmed by the XRD data. The electron micrographs of the drug-loaded microspheres showed well-formed spherical particles with a rough exterior.

Antimicrobial and Physicochemical Characterization of Biodegradable, Nitric Oxide-Releasing Nanocellulose-Chitosan Packaging Membranes.

PubMed

Sundaram, Jaya; Pant, Jitendra; Goudie, Marcus J; Mani, Sudhagar; Handa, Hitesh

2016-06-29

Biodegradable composite membranes with antimicrobial properties consisting of nanocellulose fibrils (CNFs), chitosan, and S-nitroso-N-acetyl-d-penicillamine (SNAP) were developed and tested for food packaging applications. As a nitric oxide donor, SNAP was encapsulated into completely dispersed chitosan in 100 mL of 0.1 N acetic acid and was thoroughly mixed with CNFs to produce a composite membrane. The fabricated membranes had a uniform dispersion of chitosan and SNAP within the CNFs, which was confirmed through scanning electron microscopy (SEM) micrographs and a chemiluminescence nitric oxide analyzer. The membranes prepared without SNAP showed lower water vapor permeability than that of the membranes with SNAP. The addition of SNAP resulted in a decrease in Young's modulus for both two- and three-layer membrane configurations. Antimicrobial property evaluation of SNAP-incorporated membranes showed an effective zone of inhibition against bacterial strains of Enterococcus faecalis, Staphylococcus aureus, and Listeria monocytogenes and demonstrated its potential applications for food packaging.

Synthesis and electrochemical properties of olivine LiFePO 4 prepared by a carbothermal reduction method

NASA Astrophysics Data System (ADS)

Liu, Hui-ping; Wang, Zhi-xing; Li, Xin-hai; Guo, Hua-jun; Peng, Wen-jie; Zhang, Yun-he; Hu, Qi-yang

LiFePO 4/C composite cathode material was prepared by carbothermal reduction method, which uses NH 4H 2PO 4, Li 2CO 3 and cheap Fe 2O 3 as starting materials, acetylene black and glucose as carbon sources. The precursor of LiFePO 4/C was characterized by differential thermal analysis and thermogravimetry. X-ray diffraction (XRD), scanning electron microscopy (SEM) micrographs showed that the LiFePO 4/C is olivine-type phase, and the addition of the carbon reduced the LiFePO 4 grain size. The carbon is dispersed between the grains, ensuring a good electronic contact. The products sintered at 700 °C for 8 h with glucose as carbon source possessed excellent electrochemical performance. The synthesized LiFePO 4 composites showed a high electrochemical capacity of 159.3 mAh g -1 at 0.1 C rate, and the capacity fading is only 2.2% after 30 cycles.

A new species of Perichaena (Myxomycetes) with reticulate spores from southern Vietnam.

PubMed

Novozhilov, Yuri K; Stephenson, Steven L

2015-01-01

A new species of Perichaena, described herein as P. echinolophospora, was isolated in moist chamber cultures from substrate samples collected in the monsoon deciduous lowland tropical forests (Cat Tien National Park, Vinh Cuu Nature Reserve) and mixed montane tropical forests (Bi Dup-Nui Ba Nature Reserve) of southern Vietnam. Perichaena echinolophospora was recovered from ground litter, aerial litter and the bark of living trees. The morphology of representative specimens was examined by light and scanning electron microscopy, and micrographs of relevant details are provided. Spore ornamentation consists of a regular reticulum with large meshes, 3-4 μm in wide and limited by denticulate ridges, 1.7-2.2 μm tall, and clusters of small warts and rods densely distributed over the spore surface within the meshes of the reticulum and visible only by SEM. The stability of the taxonomic characters of the species was confirmed by several collections obtained during three field seasons. © 2015 by The Mycological Society of America.

LPG ammonia and nitrogen dioxide gas sensing properties of nanostructured polypyrrole thin film

NASA Astrophysics Data System (ADS)

Bagul, Sagar B.; Upadhye, Deepak S.; Sharma, Ramphal

2016-05-01

Nanostructured Polypyrrole thin film was synthesized by easy and economic chemical oxidative polymerization technique on glass at room temperature. The prepared thin film of Polypyrrole was characterized by optical absorbance study by UV-visible spectroscopy and electrical study by I-V measurement system. The optical absorbance spectrum of Polypyrrole shows two fundamental peaks in region of 420 and 890 nm, which confirms the formation of Polypyrrole on glass substrate. The I-V graph of nanostructured Polypyrrole represents the Ohmic nature. Furthermore, the thin film of Polypyrrole was investigated by Scanning electron microscopy for surface morphology study. The SEM micrograph represents spherical nanostructured morphology of Polypyrrole on glass substrate. In order to investigate gas sensing properties, 100 ppm of LPG, Ammonia and Nitrogen Dioxide were injected in the gas chamber and magnitude of resistance has been recorded as a function of time in second. It was observed that nanostructured Polypyrrole thin film shows good sensing behavior at room temperature.

Acids with an equivalent taste lead to different erosion of human dental enamel.

PubMed

Beyer, Markus; Reichert, Jörg; Bossert, Jörg; Sigusch, Bernd W; Watts, David C; Jandt, Klaus D

2011-10-01

The consumption of acidic soft drinks may lead to demineralization and softening of human dental enamel, known as dental erosion. The aims of this in vitro study were to determine: (i) if different acids with a similar sensorial acidic taste lead to different hardness loss of enamel and (ii) if the fruit acids tartaric, malic, lactic or ascorbic acid lead to less hardness loss of enamel than citric or phosphoric acid when their concentration in solution is based on an equivalent sensorial acidic taste. Enamel samples of non-erupted human third molars were treated with acidic solutions of tartaric (TA), malic (MA), lactic (LA), ascorbic (AA), phosphoric (PA) and citric (CA) acids with a concentration that gave an equivalent sensorial acidic taste. The acidic solutions were characterized by pH value and titratable acidity. Atomic force microscopy (AFM) based nanoindentation was used to study the nano mechanical properties and scanning electron microscopy (SEM) was used to study the morphology of the treated enamel samples and the untreated control areas, respectively. The investigated acids fell into two groups. The nano hardnesses of MA, TA and CA treated enamel samples (group I) were statistically significantly greater (p<0.05) than the nano hardnesses of PA, AA and LA treated enamel samples (group II). Within each group the nano hardness was not statistically significantly different (p>0.05). The SEM micrographs showed different etch prism morphologies depending on the acid used. In vitro, the acids investigated led to different erosion effects on human dental enamel, despite their equivalent sensorial acidic taste. This has not been reported previously. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effects of a Ta interlayer on the phase transition of TiSi2 on Si(111)

NASA Astrophysics Data System (ADS)

Jeon, Hyeongtag; Jung, Bokhee; Kim, Young Do; Yang, Woochul; Nemanich, R. J.

2000-09-01

This study examines the effects of a thin Ta interlayer on the formation of TiSi2 on Si(111) substrate. The Ta interlayer was introduced by depositing Ta and Ti films sequentially on an atomically clean Si(111) substrate in an ultrahigh vacuum (UHV) system. Samples of 100 Å Ti with 5 and 10 Å Ta interlayers were compared to similar structures without an interlayer. After deposition, the substrates were annealed for 10 min, in situ, at temperatures between 500 and 750 °C in 50 °C increments. The TiSi2 formation with and without the Ta interlayer was analyzed with an X-ray diffractometer, Auger electron spectroscopy (AES), Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and a four-point probe. The AES analysis data showed a 1:2 ratio of Ti:Si in the Ti-silicide layer and indicated that the Ta layer remained at the interface between TiSi2 and the Si(111) substrate. The C 49-C 54 TiSi2 phase transition temperature was lowered by ˜200 °C. The C 49-C 54 TiSi2 phase transition temperature was 550 °C for the samples with a Ta interlayer and was 750 °C for the samples with no Ta interlayer. The sheet resistance of the Ta interlayered Ti silicide showed lower values of resistivity at low temperatures which indicated the change in phase transition temperature. The C 54 TiSi2 displayed different crystal orientation when the Ta interlayer was employed. The SEM and TEM micrographs showed that the TiSi2 with a Ta interlayer significantly suppressed the tendency to islanding and surface agglomeration.

Fuzzy Reasoning to More Accurately Determine Void Areas on Optical Micrographs of Composite Structures

NASA Technical Reports Server (NTRS)

Dominquez, Jesus A.; Tate, Lanetra C.; Wright, M. Clara; Caraccio, Anne

2013-01-01

Accomplishing the best-performing composite matrix (resin) requires that not only the processing method but also the cure cycle generate low-void-content structures. If voids are present, the performance of the composite matrix will be significantly reduced. This is usually noticed by significant reductions in matrix-dominated properties, such as compression and shear strength. Voids in composite materials are areas that are absent of the composite components: matrix and fibers. The characteristics of the voids and their accurate estimation are critical to determine for high performance composite structures. One widely used method of performing void analysis on a composite structure sample is acquiring optical micrographs or Scanning Electron Microscope (SEM) images of lateral sides of the sample and retrieving the void areas within the micrographs/images using an image analysis technique. Segmentation for the retrieval and subsequent computation of void areas within the micrographs/images is challenging as the gray-scaled values of the void areas are close to the gray-scaled values of the matrix leading to the need of manually performing the segmentation based on the histogram of the micrographs/images to retrieve the void areas. The use of an algorithm developed by NASA and based on Fuzzy Reasoning (FR) proved to overcome the difficulty of suitably differentiate void and matrix image areas with similar gray-scaled values leading not only to a more accurate estimation of void areas on composite matrix micrographs but also to a faster void analysis process as the algorithm is fully autonomous.

Stability and Synergistic Effect of Polyaniline/TiO2 Photocatalysts in Degradation of Azo Dye in Wastewater

PubMed Central

Gilja, Vanja; Novaković, Katarina; Travas-Sejdic, Jadranka; Kraljić Roković, Marijana; Žic, Mark

2017-01-01

The polyaniline/TiO2 (PANI/TiO2) composite photocatalysts were prepared by the in situ chemical oxidation of aniline (An) in the presence of TiO2 particles. For this purpose, photocatalysts with different amounts of PANI polymer were prepared and analysed. Fourier-transform infrared (FT-IR) spectroscopy and thermogravimetric (TG) analysis indicated successful synthesis of the PANI polymer and its conductivity was also determined. The micrographs of field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were used to explain the impact of the aniline amount on the aggregation process during the synthesis of the composites. The smallest size of aggregates was obtained for the photocatalysts with 15% of PANI (15PANI/TiO2) due to the formation of homogenous PANI. The photocatalytic activity of studied PANI/TiO2 photocatalysts was validated by monitoring the discoloration and mineralization of Reactive Red azo dye (RR45) in wastewater. The 15PANI/TiO2 sample presented the highest photocatalytic efficiency under ultraviolet A (UVA) irradiation, in comparison to pure TiO2. This was explained by the formation of uniformly dispersed PANI on the TiO2 particles, which was responsible for the synergistic PANI-TiO2 effect. PMID:29168744

Study on immobilization of yeast alcohol dehydrogenase on nanocrystalline Ni-Co ferrites as magnetic support.

PubMed

Shakir, Mohammad; Nasir, Zeba; Khan, Mohd Shoeb; Lutfullah; Alam, Md Fazle; Younus, Hina; Al-Resayes, Saud Ibrahim

2015-01-01

The covalent binding of yeast alcohol dehydrogenase (YADH) enzyme complex in a series of magnetic crystalline Ni-Co nanoferrites, synthesized via sol-gel auto combustion technique was investigated. The structural analysis, morphology and magnetic properties of Ni-Co nanoferrites were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), vibrating-sample magnetometer (VSM), high resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR). The comparative analysis of the HRTEM micrographs of bare magnetic nanoferrite particles and particles immobilized with enzyme revealed an uniform distribution of the particles in both the cases without undergoing change in the size which was found to be in the range 20-30 nm. The binding of YADH to Ni-Co nanoferrites and the possible binding mechanism have been suggested by comparing the FTIR results. The binding properties of the immobilized YADH enzyme were also studied by kinetic parameters, optimum operational pH, temperature, thermal stability and reusability. The immobilized YADH exhibits enhanced thermal stability as compared to the free enzyme over a wide range of temperature and pH, and showed good durability after recovery by magnetic separation for repeated use. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of polysulfone and polysulfone/vanillin microcapsules by 1H NMR spectroscopy, solid-state 13C CP/MAS-NMR spectroscopy, and N2 adsorption-desorption analyses.

PubMed

Peña, Brisa; de Ménorval, Louis-Charles; Garcia-Valls, Ricard; Gumí, Tània

2011-11-01

Textile detergent and softener industries have incorporated perfume microencapsulation technology to improve their products. Perfume encapsulation allows perfume protection until use and provides a long-lasting fragrance release. But, certain industrial microcapsules show low encapsulation capacity and low material stability. Polysulfone capsules have been already proposed to solve these drawbacks. Among them, PSf/Vanillin capsules were considered as a desirable system. They present both good material stability and high encapsulation capacity. However, several factors such as the final location of the perfume in the polymeric matrix, the aggregation state that it has in the capsule and its interaction with the capsule components have not been studied yet. These factors can provide vast information about the capsule performance and its improvement. With the aim to characterize these parameters, the physical and chemical properties of PSf/Vanillin capsules have been investigated by nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and N(2) adsorption-desorption measurements. AFM micrograph and N(2) isotherms confirm that the presence of vanillin modify the physical structure of PSf/Vanillin microcapsules as it is trapped in the capsule porosity. NMR results show that vanillin is present in solid state in PSf/Vanillin microcapsules.

Polymeric vs hydroxyapatite-based scaffolds on dental pulp stem cell proliferation and differentiation

PubMed Central

Khojasteh, Arash; Motamedian, Saeed Reza; Rad, Maryam Rezai; Shahriari, Mehrnoosh Hasan; Nadjmi, Nasser

2015-01-01

AIM: To evaluate adhesion, proliferation and differentiation of human dental pulp stem cells (hDPSCs) on four commercially available scaffold biomaterials. METHODS: hDPSCs were isolated from human dental pulp tissues of extracted wisdom teeth and established in stem cell growth medium. hDPSCs at passage 3-5 were seeded on four commercially available scaffold biomaterials, SureOss (Allograft), Cerabone (Xenograft), PLLA (Synthetic), and OSTEON II Collagen (Composite), for 7 and 14 d in osteogenic medium. Cell adhesion and morphology to the scaffolds were evaluated by scanning electron microscopy (SEM). Cell proliferation and differentiation into osteogenic lineage were evaluated using DNA counting and alkaline phosphatase (ALP) activity assay, respectively. RESULTS: All scaffold biomaterials except SureOss (Allograft) supported hDPSC adhesion, proliferation and differentiation. hDPSCs seeded on PLLA (Synthetic) scaffold showed the highest cell proliferation and attachment as indicated with both SEM and DNA counting assay. Evaluating the osteogenic differentiation capability of hDPSCs on different scaffold biomaterials with ALP activity assay showed high level of ALP activity on cells cultured on PLLA (Synthetic) and OSTEON II Collagen (Composite) scaffolds. SEM micrographs also showed that in the presence of Cerabone (Xenograft) and OSTEON II Collagen (Composite) scaffolds, the hDPSCs demonstrated the fibroblastic phenotype with several cytoplasmic extension, while the cells on PLLA scaffold showed the osteoblastic-like morphology, round-like shape. CONCLUSION: PLLA scaffold supports adhesion, proliferation and osteogenic differentiation of hDPSCs. Hence, it may be useful in combination with hDPSCs for cell-based reconstructive therapy. PMID:26640621

Exploring transmission Kikuchi diffraction using a Timepix detector

NASA Astrophysics Data System (ADS)

Vespucci, S.; Winkelmann, A.; Mingard, K.; Maneuski, D.; O'Shea, V.; Trager-Cowan, C.

2017-02-01

Electron backscatter diffraction (EBSD) is a well-established scanning electron microscope (SEM)-based technique [1]. It allows the non-destructive mapping of the crystal structure, texture, crystal phase and strain with a spatial resolution of tens of nanometers. Conventionally this is performed by placing an electron sensitive screen, typically consisting of a phosphor screen combined with a charge coupled device (CCD) camera, in front of a specimen, usually tilted 70° to the normal of the exciting electron beam. Recently, a number of authors have shown that a significant increase in spatial resolution is achievable when Kikuchi diffraction patterns are acquired in transmission geometry; that is when diffraction patterns are generated by electrons transmitted through an electron-transparent, usually thinned, specimen. The resolution of this technique, called transmission Kikuchi diffraction (TKD), has been demonstrated to be better than 10 nm [2,3]. We have recently demonstrated the advantages of a direct electron detector, Timepix [4,5], for the acquisition of standard EBSD patterns [5]. In this article we will discuss the advantages of Timepix to perform TKD and for acquiring spot diffraction patterns and more generally for acquiring scanning transmission electron microscopy micrographs in the SEM. Particularly relevant for TKD, is its very compact size, which allows much more flexibility in the positioning of the detector in the SEM chamber. We will furthermore show recent results using Timepix as a virtual forward scatter detector, and will illustrate the information derivable on producing images through processing of data acquired from different areas of the detector. We will show results from samples ranging from gold nanoparticles to nitride semiconductor nanorods.

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.

Investigation of magnetic and structural properties of Ni-Zr co-doped M-type Sr-La hexaferrites

NASA Astrophysics Data System (ADS)

Yang, Yujie; Wang, Fanhou; Shao, Juxiang; Huang, Duohui; Tang, Jin; Rehman, Khalid Mehmood Ur

2018-02-01

In this research, Ni2+ and Zr4+ co-doped Sr-La hexaferrites Sr0.7La0.3Fe12.0-2 x (NiZr) x O19 (0.0 ≤ x ≤ 0.5) were synthesized by the standard ceramic method. The phase identification of the hexaferrites was confirmed by X-ray diffraction analysis. X-ray diffraction analysis showed that all the samples were in single phase M-type hexagonal structure and no impurity phase was observed. Lattice parameters ( c and a) increased with increasing NiZr content ( x) from 0.0 to 0.5. The morphology of the hexaferrites was analyzed by a field emission scanning electron microscopy (FE-SEM). FE-SEM micrographs showed that the grains exhibited hexagonal shape in a plate-like structure with clear grain boundaries. Magnetization properties of the hexaferrites were carried out at room temperature using a physical property measurement system-vibrating sample magnetometer. The values of saturation magnetization ( M s), remanent magnetization ( M r) and coercivity ( H c) were calculated from magnetic hysteresis ( M- H) loops. M s and H c decreased with increasing NiZr content ( x) from 0.0 to 0.5. M r and M r/ M s ratio first increased with increasing NiZr content ( x) from 0.0 to 0.1, and then decreased when NiZr content ( x) ≥ 0.1.

Effective remediation of phenol,2,4-bis(1,1-dimethylethyl) and bis(2-ethylhexyl) phthalate in farm effluent using Guar gum--A plant based biopolymer.

PubMed

Kee, Yang Ling; Mukherjee, Sumona; Pariatamby, Agamuthu

2015-10-01

This study was carried out to evaluate the efficiency of Guar gum in removing Persistent Organic Pollutants (POPs), viz. phenol,2,4-bis(1,1-dimethylethyl) and bis(2-ethylhexyl) phthalate (DEHP), from farm effluent. The removal efficiency was compared with alum. The results indicated that 4.0 mg L(-1) of Guar gum at pH 7 could remove 99.70% and 99.99% of phenol,2,4-bis(1,1-dimethylethyl) and DEHP, respectively. Box Behnken design was used for optimization of the operating parameters for optimal POPs removal. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy studies were conducted on the flocs. SEM micrographs showed numerous void spaces in the flocs produced by Guar gum as opposed to those produced by alum. This indicated why Guar gum was more effective in capturing and removal of suspended particles and POPs as compared to alum. FTIR spectra indicated a shift in the bonding of functional groups in the flocs produced by Guar gum as compared to raw Guar gum powder signifying chemical attachment of the organics present in the effluent to the coagulant resulting in their removal. Guar gum is highly recommended as a substitute to chemical coagulant in treating POPs due to its non-toxic and biodegradable characteristics. Copyright © 2015 Elsevier Ltd. All rights reserved.

Degradation of blue and red inks by Ag/AgCl photocatalyst under UV light irradiation

NASA Astrophysics Data System (ADS)

Daupor, Hasan; Chenea, Asmat

2017-08-01

Objective of this research, cubic Ag/AgCl photocatalysts with an average particle size of 500 nm has been successfully synthesized via a modified precipitation reaction between ZrCl4 and AgNO3. Method for analysis, the crystal structure of the product was characterized by X-ray powder diffraction (XRD). The morphology and composition were studied by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV-vis diffuse-reflection spectra (DRS) and so on. The result showed that the optical absorption spectrum exhibited strong absorption in the visible region around 500-600 nm due to surface plasmon resonance (SPR) of metallic silver nanoparticles. SEM micrographs showed that the obtained Ag/AgCl had cubic morphology and appeared on the porous surface as the cubic cage morphology. As a result, this porous surface also positively affected the photocatalytic reaction. The photocatalytic activity of the obtained product was evaluated by the photodegradation of blue and red ink solutions under UV light irradiation, and it was interestingly, discovered that AgCl could degrade 0.25% and 0.10% in 7 hours for blue and red inks solution respectively, Which were higher than of commercial AgCl. The result suggested that the morphology of Ag/AgCl strongly affected their photocatalytic activities. O2-, OH- reaction. radicals and Cl° atom are main species during photocatalytic reaction.

Temperature dependent dielectric relaxation and ac-conductivity of alkali niobate ceramics studied by impedance spectroscopy

NASA Astrophysics Data System (ADS)

Yadav, Abhinav; Mantry, Snigdha Paramita; Fahad, Mohd.; Sarun, P. M.

2018-05-01

Sodium niobate (NaNbO3) ceramics is prepared by conventional solid state reaction method at sintering temperature 1150 °C for 4 h. The structural information of the material has been investigated by X-ray diffraction (XRD) and Field emission scanning electron microscopy (FE-SEM). The XRD analysis of NaNbO3 ceramics shows an orthorhombic structure. The FE-SEM micrograph of NaNbO3 ceramics exhibit grains with grain sizes ranging between 1 μm to 5 μm. The surface coverage and average grain size of NaNbO3 ceramics are found to be 97.6 % and 2.5 μm, respectively. Frequency dependent electrical properties of NaNbO3 is investigated from room temperature to 500 °C in wide frequency range (100 Hz-5 MHz). Dielectric constant, ac-conductivity, impedance, modulus and Nyquist analysis are performed. The observed dielectric constant (1 kHz) at transition temperature (400 °C) are 975. From conductivity analysis, the estimated activation energy of NaNbO3 ceramics is 0.58 eV at 10 kHz. The result of Nyquist plot shows that the electrical behavior of NaNbO3 ceramics is contributed by grain and grain boundary responses. The impedance and modulus spectrum asserts that the negative temperature coefficient of resistance (NTCR) behavior and non-Debye type relaxation in NaNbO3.

Oxygen ion irradiation effect on corrosion behavior of titanium in nitric acid medium

NASA Astrophysics Data System (ADS)

Ningshen, S.; Kamachi Mudali, U.; Mukherjee, P.; Barat, P.; Raj, Baldev

2011-01-01

The corrosion assessment and surface layer properties after O 5+ ion irradiation of commercially pure titanium (CP-Ti) has been studied in 11.5 N HNO 3. CP-Ti specimen was irradiated at different fluences of 1 × 10 13, 1 × 10 14 and 1 × 10 15 ions/cm 2 below 313 K, using 116 MeV O 5+ ions source. The corrosion resistance and surface layer were evaluated by using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and glancing-angle X-ray diffraction (GXRD) methods. The potentiodynamic anodic polarization results of CP-Ti revealed that increased in ion fluence (1 × 10 13-1 × 10 15 ions/cm 2) resulted in increased passive current density due to higher anodic dissolution. SEM micrographs and GXRD analysis corroborated these results showing irradiation damage after corrosion test and modified oxide layer by O 5+ ion irradiation was observed. The EIS studies revealed that the stability and passive film resistance varied depending on the fluence of ion irradiation. The GXRD patterns of O 5+ ion irradiated CP-Ti revealed the oxides formed are mostly TiO 2, Ti 2O 3 and TiO. In this paper, the effects of O 5+ ion irradiation on material integrity and corrosion behavior of CP-Ti in nitric acid are described.

An investigation on morphology and mechanical properties of HDPE/nanoclay/nanoCaCO{sub 3} ternary nanocomposites

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

Garmabi, Hamid, E-mail: garmabi@aut.ac.ir; Tabari, Seyed Emad Alavi; Javadi, Azizeh

Ternary Nanocomposites of high-density polyethylene (HDPE) containing two types of nano particles, a layered organoclay (Closite 15A) and a spherical nano Calcium Carbonate (CaCO{sub 3}), with various compositions were prepared using melt mixing. Maleic anhydride grafted polyethylene (MA-g-PE) was used to enhance the dispersion of nanofillers and better interface adhesion. Three different levels of nanoclay (1, 3, 5 wt. %), CaCO{sub 3} (6, 8, 10 wt. %) and MA-g-PE (3, 6, 9 wt. %) were used. The mixing was done in two steps: First a concentrated masterbatch of nanoparticles in HPDE and MA-g-PE was prepared using an internal mixer andmore » then melt-mixing of nanocomposites was done in a lab scale co-rotating twin screw extruder. The morphology of samples was studied using Scanning Electron Microscopy (SEM) and mechanical properties were evaluated using tensile and impact tests. According to the SEM micrographs, nanofillers were well dispersed in the HDPE matrix and XRD patterns showed the intercalation of nanoclay layers too. Generally using the layered nanoclay can enhance the tensile modulus while the use of spherical nano CaCO{sub 3} results into improved toughness. It was found that co-incorporation of these two types of nanofillers, leads to improve the stiffness and minimize the reduction of impact strength, simultaneously.« less

Potentiodynamic Polarization Studies and Surface Chemical Composition of Bismuth Titanate (BixTiyOz) Films Produced through Radiofrequency Magnetron Sputtering

PubMed Central

Alfonso, José E.; Olaya, Jhon J.; Pinzón, Manuel J.; Marco, José F.

2013-01-01

The applications of Bismuth Titanate (BixTiyOz) materials have been focused on their electronic and optical properties, but with respect to the use of these compounds in applications like corrosion resistance, have been very few or nonexistent. For this reason, in the present investigation BixTiyOz thin films were deposited using RF magnetron sputtering onto silicon wafers, stainless steel 316L, and titanium alloy (Ti6Al4V) substrates, in order to carry out a study of the corrosion behavior of this compound. The structural properties of the coatings were studied through X-ray diffraction (XRD), the morphology was determined using Scanning Electron Microscopy (SEM), the corrosion resistance behavior of the coated and uncoated substrates was evaluated via the Potentiodynamic Polarization technique, and surface chemical composition was evaluated through X-ray photoelectron spectroscopy (XPS). The XRD results indicated that the films were amorphous. The SEM micrographs showed that the deposited films were homogeneous, but in some cases there were cracks. The potentiodynamic polarization technique showed that the corrosion current in the coated substrates decreased by an order of two magnitudes with respect to the uncoated substrates, but in both cases the corrosion mechanism was pitting due to the pores in the film. The XPS analysis shows that the deposited films contain both Bi3+ and Ti4+. PMID:28788338

Potentiodynamic Polarization Studies and Surface Chemical Composition of Bismuth Titanate (Bi x Ti y O z ) Films Produced through Radiofrequency Magnetron Sputtering.

PubMed

Alfonso, José E; Olaya, Jhon J; Pinzón, Manuel J; Marco, José F

2013-10-08

The applications of Bismuth Titanate (Bi x Ti y O z ) materials have been focused on their electronic and optical properties, but with respect to the use of these compounds in applications like corrosion resistance, have been very few or nonexistent. For this reason, in the present investigation Bi x Ti y O z thin films were deposited using RF magnetron sputtering onto silicon wafers, stainless steel 316L, and titanium alloy (Ti₆Al₄V) substrates, in order to carry out a study of the corrosion behavior of this compound. The structural properties of the coatings were studied through X-ray diffraction (XRD), the morphology was determined using Scanning Electron Microscopy (SEM), the corrosion resistance behavior of the coated and uncoated substrates was evaluated via the Potentiodynamic Polarization technique, and surface chemical composition was evaluated through X-ray photoelectron spectroscopy (XPS). The XRD results indicated that the films were amorphous. The SEM micrographs showed that the deposited films were homogeneous, but in some cases there were cracks. The potentiodynamic polarization technique showed that the corrosion current in the coated substrates decreased by an order of two magnitudes with respect to the uncoated substrates, but in both cases the corrosion mechanism was pitting due to the pores in the film. The XPS analysis shows that the deposited films contain both Bi 3+ and Ti 4+ .

Studying the morphological features of plasma treated silver and PEGylated silver nanoparticles: antibacterial activity

NASA Astrophysics Data System (ADS)

Waseem, M.; Awan, T.; Yasin, H. M.; Rehman, N. U.

2018-03-01

A strategy to treat the silver and PEGylated silver nanoparticles with plasma was being purposed. Oil in water (o/w) microemulsion method was used for the synthesis of Ag nanoparticles (AgNPs). Polyethylene glycol (PEG) having molecular weight 600 was used to coat the surface of AgNPs. Optical emission spectroscopy (OES) was used to characterize the plasma and it is noted that plasma treatment is useful to modify the structural characteristic of silver nanoparticles. The nanoparticles were treated with helium-oxygen mixture plasma, generated in plasma needle at atmospheric pressure. Both AgNPs and PEGylated AgNPs before and after plasma treatment were characterized by x-rays diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The crystallite size of silver nanoparticles after the treatment of plasma decreases from 71 nm to 27 nm. The SEM micrographs show that the size of Ag nanoparticles was nearly 118 nm whereas the thickness of the silver needle was around 135 nm. All the characteristics IR bands associated to the silver nanoparticles were detected. The FTIR spectrum also support the accumulation of OH radicals in the plasma treated samples. The samples before and after plasma treatment were screened against Gram positive (Bacillus Subtilis and Staphylococcus Aureus) and Gram negative (Escherichia Coli and Pseudomonas Aeruginosa) bacteria. The promising response was detected when plasma treated PEGylated AgNPs was tested against bacterial strains.

Supercritical fluid crystallization of griseofulvin: crystal habit modification with a selective growth inhibitor.

PubMed

Jarmer, Daniel J; Lengsfeld, Corinne S; Anseth, Kristi S; Randolph, Theodore W

2005-12-01

Poly (sebacic anhydride) (PSA) was used as a growth inhibitor to selectively modify habit of griseofulvin crystals formed via the Precipitation with a compressed-fluid antisolvent (PCA) process. PSA and griseofulvin were coprecipitated within a PCA injector, which provided efficient mixing between the solution and compressed antisolvent process streams. Griseofulvin crystal habit was modified from acicular to bipyramidal when the mass ratio of PSA/griseofulvin in the solution feed stream was

Synthesis and characterization of agricultural controllable humic acid superabsorbent.

PubMed

Gao, Lijuan; Wang, Shiqiang; Zhao, Xuefei

2013-12-01

Humic acid superabsorbent polymer (P(AA/AM-HA)) and superabsorbent polymer (P(AA/AM)) were synthesized by aqueous solution polymerization method using acrylic acid (AA), acrylamide (AM) and humic acid (HA) as raw material. The effects of N,N'-methylenebisacrylamide (MBA) crosslinking agent, potassium peroxydisulfate (KPS) initiator, reaction temperature, HA content, ratio of AA to AM, concentration of monomer and neutralization of AA on water absorption were investigated. Absorption and desorption ratios of nitrogen fertilizer and phosphate fertilizer were also investigated by determination of absorption and desorption ratio of NH4(+), PO4(3-) on P(AA/AM-HA) and P(AA/AM). The P(AA/AM-HA) and P(AA/AM) were characterized by Fourier translation infrared spectroscopy, biological photomicroscope and scanning electron microscopy (SEM). The optimal conditions obtained were as follows: the weight ratio of MBA to AA and AM was 0.003; the weight ratio of KPS to AA and AM was 0.008; the weight ratio of HA to AA was 0.1; the mole ratio of AM to AA is 0.1; the mole ratio of NaOH to AA is 0.9; the reaction temperature was 60°C. P(AA/AM-HA) synthesized under optimal conditions, has a good saline tolerance, its water absorbency in distilled water and 0.9 wt.% saline solution is 1180 g/g and 110 g/g, respectively. P(AA/AM-HA) achieves half saturation in 6.5 min. P(AA/AM-HA) is superior to P(AA/AM) on absorption of NH4(+), PO4(3-). The SEM micrograph of P(AA/AM-HA) shows a fine alveolate structure. The biological optical microscope micrograph of P(AA/AM-HA) shows a network structure. Graft polymerization between P(AA/AM) and HA was demonstrated by infrared spectrum. The P(AA/AM-HA) superabsorbent has better absorbing ability of water and fertilizer, electrolytic tolerance and fewer cost than P(AA/AM) superabsorbent. Copyright © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Notch Sensitivity of Fatigue Behavior of a Hi-Nicalon/SiC Ceramic Composite with an Oxidation Inhibited Matrix at 1200 degree C in Air and in Steam

DTIC Science & Technology

2011-03-24

Stress Ratio and Frequency. AGARD - CP -569, NATO, AGARD , SMP, 7 Rue Ancelle, 92200 Neuilly sur Seine, France, March 1996. 5. Chawla, K.K. Ceramic Matrix...fatigue at 1.0 Hz in air at 1200°C. σmax = 120 MPa, Nf = 77,575, tf = 21.5 h ........................................................ 73 Figure 55: SEM...areas of oxidation. ............ 73 Figure 56: SEM micrographs of the fiber fracture surfaces of specimen 13 tested in fatigue at 1.0 Hz in steam at

A deep convolutional neural network approach to single-particle recognition in cryo-electron microscopy.

PubMed

Zhu, Yanan; Ouyang, Qi; Mao, Youdong

2017-07-21

Single-particle cryo-electron microscopy (cryo-EM) has become a mainstream tool for the structural determination of biological macromolecular complexes. However, high-resolution cryo-EM reconstruction often requires hundreds of thousands of single-particle images. Particle extraction from experimental micrographs thus can be laborious and presents a major practical bottleneck in cryo-EM structural determination. Existing computational methods for particle picking often use low-resolution templates for particle matching, making them susceptible to reference-dependent bias. It is critical to develop a highly efficient template-free method for the automatic recognition of particle images from cryo-EM micrographs. We developed a deep learning-based algorithmic framework, DeepEM, for single-particle recognition from noisy cryo-EM micrographs, enabling automated particle picking, selection and verification in an integrated fashion. The kernel of DeepEM is built upon a convolutional neural network (CNN) composed of eight layers, which can be recursively trained to be highly "knowledgeable". Our approach exhibits an improved performance and accuracy when tested on the standard KLH dataset. Application of DeepEM to several challenging experimental cryo-EM datasets demonstrated its ability to avoid the selection of un-wanted particles and non-particles even when true particles contain fewer features. The DeepEM methodology, derived from a deep CNN, allows automated particle extraction from raw cryo-EM micrographs in the absence of a template. It demonstrates an improved performance, objectivity and accuracy. Application of this novel method is expected to free the labor involved in single-particle verification, significantly improving the efficiency of cryo-EM data processing.

A Stochastic Kinematic Model of Class Averaging in Single-Particle Electron Microscopy

PubMed Central

Park, Wooram; Midgett, Charles R.; Madden, Dean R.; Chirikjian, Gregory S.

2011-01-01

Single-particle electron microscopy is an experimental technique that is used to determine the 3D structure of biological macromolecules and the complexes that they form. In general, image processing techniques and reconstruction algorithms are applied to micrographs, which are two-dimensional (2D) images taken by electron microscopes. Each of these planar images can be thought of as a projection of the macromolecular structure of interest from an a priori unknown direction. A class is defined as a collection of projection images with a high degree of similarity, presumably resulting from taking projections along similar directions. In practice, micrographs are very noisy and those in each class are aligned and averaged in order to reduce the background noise. Errors in the alignment process are inevitable due to noise in the electron micrographs. This error results in blurry averaged images. In this paper, we investigate how blurring parameters are related to the properties of the background noise in the case when the alignment is achieved by matching the mass centers and the principal axes of the experimental images. We observe that the background noise in micrographs can be treated as Gaussian. Using the mean and variance of the background Gaussian noise, we derive equations for the mean and variance of translational and rotational misalignments in the class averaging process. This defines a Gaussian probability density on the Euclidean motion group of the plane. Our formulation is validated by convolving the derived blurring function representing the stochasticity of the image alignments with the underlying noiseless projection and comparing with the original blurry image. PMID:21660125

Novel Processing of Boron Carbide (B4C): Plasma Synthesized Nano Powders and Pressureless Sintering Forming of Complex Shapes

DTIC Science & Technology

2008-12-01

Figure 4. B4C plates formed via hot pressing with a curved shape. Commercial B4C shows a large number of lenticular graphitic inclusions, Figure 5...materials and they act as crack initiation points in flexure testing. Figure 5. SEM micrograph showing large lenticular graphitic inclusions in commercial

Lunar sample analysis

NASA Technical Reports Server (NTRS)

Housley, R. M.

1983-01-01

The evolution of the lunar regolith under solar wind and micrometeorite bombardment is discussed as well as the size distribution of ultrafine iron in lunar soil. The most important characteristics of complex graphite, sulfide, arsenide, palladium, and platinum mineralization in a pegmatoid pyroxenite of the Stillwater Complex in Montana are examined. Oblique reflected light micrographs and backscattered electron SEM images of the graphite associations are included.

Removal of industrial dyes and heavy metals by Beauveria bassiana: FTIR, SEM, TEM and AFM investigations with Pb(II).

PubMed

Gola, Deepak; Malik, Anushree; Namburath, Maneesh; Ahammad, Shaikh Ziauddin

2017-10-01

Presence of industrial dyes and heavy metal as a contaminant in environment poses a great risk to human health. In order to develop a potential technology for remediation of dyes (Reactive remazol red, Yellow 3RS, Indanthrene blue and Vat novatic grey) and heavy metal [Cu(II), Ni(II), Cd(II), Zn(II), Cr(VI) and Pb(II)] contamination, present study was performed with entomopathogenic fungi, Beauveria bassiana (MTCC no. 4580). High dye removal (88-97%) was observed during the growth of B. bassiana while removal percentage for heavy metals ranged from 58 to 75%. Further, detailed investigations were performed with Pb(II) in terms of growth kinetics, effect of process parameters and mechanism of removal. Growth rate decreased from 0.118 h -1 (control) to 0.031 h -1 , showing 28% reduction in biomass at 30 mg L -1 Pb(II) with 58.4% metal removal. Maximum Pb(II) removal was observed at 30 °C, neutral pH and 30 mg L -1 initial metal concentration. FTIR analysis indicated the changes induced by Pb(II) in functional groups on biomass surface. Further, microscopic analysis (SEM and atomic force microscopy (AFM)) was performed to understand the changes in cell surface morphology of the fungal cell. SEM micrograph showed a clear deformation of fungal hyphae, whereas AFM studies proved the increase in surface roughness (RSM) in comparison to control cell. Homogenous bioaccumulation of Pb(II) inside the fungal cell was clearly depicted by TEM-high-angle annular dark field coupled with EDX. Present study provides an insight into the mechanism of Pb(II) bioremediation and strengthens the significance of using entomopathogenic fungus such as B. bassiana for metal and dye removal.

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.

Multimodal hyperspectral optical microscopy

DOE PAGES

Novikova, Irina V.; Smallwood, Chuck R.; Gong, Yu; ...

2017-09-02

We describe a unique and convenient approach to multimodal hyperspectral optical microscopy, herein achieved by coupling a portable and transferable hyperspectral imager to various optical microscopes. The experimental and data analysis schemes involved in recording spectrally and spatially resolved fluorescence, dark field, and optical absorption micrographs are illustrated through prototypical measurements targeting selected model systems. Namely, hyperspectral fluorescence micrographs of isolated fluorescent beads are employed to ensure spectral calibration of our detector and to gauge the attainable spatial resolution of our measurements; the recorded images are diffraction-limited. Moreover, spatially over-sampled absorption spectroscopy of a single lipid (18:1 Liss Rhod PE)more » layer reveals that optical densities on the order of 10-3 may be resolved by spatially averaging the recorded optical signatures. We also briefly illustrate two applications of our setup in the general areas of plasmonics and cell biology. Most notably, we deploy hyperspectral optical absorption microscopy to identify and image algal pigments within a single live Tisochrysis lutea cell. Overall, this work paves the way for multimodal multidimensional spectral imaging measurements spanning the realms of several scientific disciples.« less

Multimodal hyperspectral optical microscopy

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

Novikova, Irina V.; Smallwood, Chuck R.; Gong, Yu

We describe a unique and convenient approach to multimodal hyperspectral optical microscopy, herein achieved by coupling a portable and transferable hyperspectral imager to various optical microscopes. The experimental and data analysis schemes involved in recording spectrally and spatially resolved fluorescence, dark field, and optical absorption micrographs are illustrated through prototypical measurements targeting selected model systems. Namely, hyperspectral fluorescence micrographs of isolated fluorescent beads are employed to ensure spectral calibration of our detector and to gauge the attainable spatial resolution of our measurements; the recorded images are diffraction-limited. Moreover, spatially over-sampled absorption spectroscopy of a single lipid (18:1 Liss Rhod PE)more » layer reveals that optical densities on the order of 10-3 may be resolved by spatially averaging the recorded optical signatures. We also briefly illustrate two applications of our setup in the general areas of plasmonics and cell biology. Most notably, we deploy hyperspectral optical absorption microscopy to identify and image algal pigments within a single live Tisochrysis lutea cell. Overall, this work paves the way for multimodal multidimensional spectral imaging measurements spanning the realms of several scientific disciples.« less

Two-dimensional simulation and modeling in scanning electron microscope imaging and metrology research.

PubMed

Postek, Michael T; Vladár, András E; Lowney, Jeremiah R; Keery, William J

2002-01-01

Traditional Monte Carlo modeling of the electron beam-specimen interactions in a scanning electron microscope (SEM) produces information about electron beam penetration and output signal generation at either a single beam-landing location, or multiple landing positions. If the multiple landings lie on a line, the results can be graphed in a line scan-like format. Monte Carlo results formatted as line scans have proven useful in providing one-dimensional information about the sample (e.g., linewidth). When used this way, this process is called forward line scan modeling. In the present work, the concept of image simulation (or the first step in the inverse modeling of images) is introduced where the forward-modeled line scan data are carried one step further to construct theoretical two-dimensional (2-D) micrographs (i.e., theoretical SEM images) for comparison with similar experimentally obtained micrographs. This provides an ability to mimic and closely match theory and experiment using SEM images. Calculated and/or measured libraries of simulated images can be developed with this technique. The library concept will prove to be very useful in the determination of dimensional and other properties of simple structures, such as integrated circuit parts, where the shape of the features is preferably measured from a single top-down image or a line scan. This paper presents one approach to the generation of 2-D simulated images and presents some suggestions as to their application to critical dimension metrology.

TiO2-PANI/Cork composite: A new floating photocatalyst for the treatment of organic pollutants under sunlight irradiation.

PubMed

Sboui, Mouheb; Nsib, Mohamed Faouzi; Rayes, Ali; Swaminathan, Meenakshisundaram; Houas, Ammar

2017-10-01

A novel photocatalyst based on TiO 2 -PANI composite supported on small pieces of cork has been reported. It was prepared by simple impregnation method of the polyaniline (PANI)-modified TiO 2 on cork. The TiO 2 -PANI/Cork catalyst shows the unique feature of floating on the water surface. The as-synthesized catalyst was characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectra (UV-vis DRS) and the Brunauer-Emmett-Teller (BET) surface area analysis. Characterization suggested the formation of anatase highly dispersed on the cork surface. The prepared floating photocatalyst showed high efficiency for the degradation of methyl orange dye and other organic pollutants under solar irradiation and constrained conditions, i.e., no-stirring and no-oxygenation. The TiO 2 -PANI/Cork floating photocatalyst can be reused for at least four consecutive times without significant decrease of the degradation efficiency. Copyright © 2017. Published by Elsevier B.V.

Development and characterization of the kefiran-whey protein isolate-TiO2 nanocomposite films.

PubMed

Zolfi, Mohsen; Khodaiyan, Faramarz; Mousavi, Mohammad; Hashemi, Maryam

2014-04-01

Biodegradable kefiran-whey protein isolate (WPI)-titanium dioxide (TiO2) blend films were developed and characterized as a function of incorporating amount of TiO2 nanoparticles (1, 3 and 5% wt.). Results showed that the water vapor permeability, moisture content, moisture absorption and water solubility decreased by increasing the nano-TiO2 content. Mechanical tests revealed the plasticizing effect of TiO2 nanoparticles on the kefiran-WPI-TiO2 film. Addition of TiO2 nanoparticles to kefiran-WPI films significantly decreased tensile strength and Young's modulus, while increased its elongation at break. Differential scanning calorimetry data indicated that the glass transition temperature significantly changed by adding nano-TiO2. X-ray diffraction analysis also demonstrated that crystal type in kefiran-WPI was not affected by incorporation of TiO2 nanoparticles. A uniform distribution at 1 and 3% wt. loading levels of TiO2 nanoparticles was observed using scanning electron microscopy (SEM) micrographs. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis, characterization and anti-bacterial activities of pure and Co-doped BaSO4 nanoparticles via chemical precipitation route

NASA Astrophysics Data System (ADS)

Sivakumar, S.; Soundhirarajan, P.; Venkatesan, A.; Khatiwada, Chandra Prasad

2015-02-01

In the present study, we reported that the synthesis and characterization of pure and diverse mole Co-doped BaSO4 nanoparticles have been synthesized by chemical precipitation technique. X-ray diffraction analysis (XRD) brought out the information about the synthesized products is orthorhombic structure and highly crystalline in nature. The average grain size of the samples was determined by using the Debye-Scherer's equation. The existence of functional groups and band area of the samples were confirmed by Fourier transform infrared (FTIR) spectroscopy. The direct and indirect band gap energy of pure and doped samples was carried out using UV-VIS-DRS. The surface micrograph, morphological distribution and elemental compositions of the synthesized products were assessed by scanning electron microscopy (SEM) and Energy dispersive X-ray (EDS). Thermo gravimetric and differential thermal analysis (TG-DTA) techniques were analyzed thermal behaviour of pure and Co-doped samples. Finally, antibacterial activities found the Gram-positive and Gram-negative bacteria are more active in transporter, dehydrogenize and periplasmic enzymatic activities of pure and doped samples.

Studies on structural, electrical, thermal and magnetic properties of YFeO3 ceramic

NASA Astrophysics Data System (ADS)

Suthar, Lokesh; Jha, V. K.; Bhadala, Falguni; Roy, M.; Sahu, S.; Barbar, S. K.

2017-10-01

The polycrystalline ceramic sample of YFeO3 has been synthesized by high-temperature solid-state reaction method using high-purity oxides. The formation of the compound has been confirmed by the room temperature (RT) X-ray diffraction analysis. The refined lattice parameters obtained by Rietveld analysis are: a = 5.5907 Å, b = 7.6082 Å and c = 5.2849 Å with orthorhombic symmetry in space group Pnma. The average grain size obtained from the SEM micrograph is around 2 µm. The three-dimensional surface morphology has been investigated using atomic force microscopy (AFM), and the average roughness measured in the sampling area of 100.07 µm2 is around 142 nm. The frequency- and temperature-dependent dielectric constant has been measured. The material shows high dielectric constant value (750) at RT. The activation energy obtained from dc conductivity using Arrhenius relation σ = σ oexp(-Ea/kT) is 2.12 eV. Thermal analysis shows phase change around 625 K with minimum weight loss (i.e. 1.27% of initial weight) from RT to 1273 K. The magnetization measurement indicates soft magnetic behaviour.

Three-dimensional reconstruction of highly complex microscopic samples using scanning electron microscopy and optical flow estimation.

PubMed

Baghaie, Ahmadreza; Pahlavan Tafti, Ahmad; Owen, Heather A; D'Souza, Roshan M; Yu, Zeyun

2017-01-01

Scanning Electron Microscope (SEM) as one of the major research and industrial equipment for imaging of micro-scale samples and surfaces has gained extensive attention from its emerge. However, the acquired micrographs still remain two-dimensional (2D). In the current work a novel and highly accurate approach is proposed to recover the hidden third-dimension by use of multi-view image acquisition of the microscopic samples combined with pre/post-processing steps including sparse feature-based stereo rectification, nonlocal-based optical flow estimation for dense matching and finally depth estimation. Employing the proposed approach, three-dimensional (3D) reconstructions of highly complex microscopic samples were achieved to facilitate the interpretation of topology and geometry of surface/shape attributes of the samples. As a byproduct of the proposed approach, high-definition 3D printed models of the samples can be generated as a tangible means of physical understanding. Extensive comparisons with the state-of-the-art reveal the strength and superiority of the proposed method in uncovering the details of the highly complex microscopic samples.

Optimization of conditions of solvent-free microwave extraction and study on antioxidant capacity of essential oil from Schisandra chinensis (Turcz.) Baill.

PubMed

Ma, Chun-hui; Yang, Lei; Zu, Yuan-gang; Liu, Ting-ting

2012-10-15

In this article, solvent-free microwave extraction (SFME) of essential oil from Schisandra chinensis (Turcz.) Baill was studied. A multivariate study based on central composite design (CCD) was used to evaluate the influence of three major variables affecting the performance of SFME. The optimum parameters were extraction time 30 min, irradiation power 385 W and moisture content of the fruits was 68%. The extraction yield of essential oil was 11 ml/kg under the optimum conditions. The antioxidant capacity of essential oils extracted by different methods were determined, and compared with traditional antioxidants. GC-MS showed the different composition of essential oil extracted by hydro-distillation (HD), steam-distillation (SD) and SFME. S. chinensis materials treated by different methods were observed by scanning electronic microscopy (SEM) and thermo-gravimetric analysis (TGA). Micrographs and thermo gravimetric loss provided more evidences to prove SFME of essential oil is more completed than HD and SD. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Optimization of a sponge cake formulation with inulin as fat replacer: structure, physicochemical, and sensory properties.

PubMed

Rodríguez-García, Julia; Puig, Ana; Salvador, Ana; Hernando, Isabel

2012-02-01

The effects of several fat replacement levels (0%, 35%, 50%, 70%, and 100%) by inulin in sponge cake microstructure and physicochemical properties were studied. Oil substitution for inulin decreased significantly (P < 0.05) batter viscosity, giving heterogeneous bubbles size distributions as it was observed by light microscopy. Using confocal laser scanning microscopy the fat was observed to be located at the bubbles' interface, enabling an optimum crumb cake structure development during baking. Cryo-SEM micrographs of cake crumbs showed a continuous matrix with embedded starch granules and coated with oil; when fat replacement levels increased, starch granules appeared as detached structures. Cakes with fat replacement up to 70% had a high crumb air cell values; they were softer and rated as acceptable by an untrained sensory panel (n = 51). So, the reformulation of a standard sponge cake recipe to obtain a new product with additional health benefits and accepted by consumers is achieved. Practical Application:  In this study, fat is replaced by inulin in cakes, which is a fiber mainly obtained from chicory roots. Sponge cake formulations with reductions in fat content up to 70% are achieved. These high-quality products can be labeled as "reduced in fat" according to U.S. FDA (2009) and EU regulations (European-Union 2006). © 2012 Institute of Food Technologists®

Additive Manufacturing of Single-Crystal Superalloy CMSX-4 Through Scanning Laser Epitaxy: Computational Modeling, Experimental Process Development, and Process Parameter Optimization

NASA Astrophysics Data System (ADS)

Basak, Amrita; Acharya, Ranadip; Das, Suman

2016-08-01

This paper focuses on additive manufacturing (AM) of single-crystal (SX) nickel-based superalloy CMSX-4 through scanning laser epitaxy (SLE). SLE, a powder bed fusion-based AM process was explored for the purpose of producing crack-free, dense deposits of CMSX-4 on top of similar chemistry investment-cast substrates. Optical microscopy and scanning electron microscopy (SEM) investigations revealed the presence of dendritic microstructures that consisted of fine γ' precipitates within the γ matrix in the deposit region. Computational fluid dynamics (CFD)-based process modeling, statistical design of experiments (DoE), and microstructural characterization techniques were combined to produce metallurgically bonded single-crystal deposits of more than 500 μm height in a single pass along the entire length of the substrate. A customized quantitative metallography based image analysis technique was employed for automatic extraction of various deposit quality metrics from the digital cross-sectional micrographs. The processing parameters were varied, and optimal processing windows were identified to obtain good quality deposits. The results reported here represent one of the few successes obtained in producing single-crystal epitaxial deposits through a powder bed fusion-based metal AM process and thus demonstrate the potential of SLE to repair and manufacture single-crystal hot section components of gas turbine systems from nickel-based superalloy powders.

The natural compound magnolol affects growth, biofilm formation, and ultrastructure of oral Candida isolates.

PubMed

Behbehani, Jawad; Shreaz, Sheikh; Irshad, Mohammad; Karched, Maribassapa

2017-12-01

The incidence of oral candidosis has increased in recent years due to the escalation in HIV-infection, cancer treatments, organ transplantation, and diabetes. In addition, corticosteroid use, dentures, and broad-spectrum antibiotic use have also contributed to the problem. Treatment of oral candidosis has continued to be problematic because of the potential toxicity of antifungals in clinical use, and, above all, development of drug resistance among patients. In this study, the antifungal effect of magnolol was investigated against 64 strains of Candida spp. (four standard and 60 oral isolates) through minimum inhibitory concentration (MIC) and growth curve assays. Insight into the mechanisms of the antifungal action has been gained through ultrastructural studies using confocal scanning laser microscopy (CSLM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Molecular docking was done for predicting the interactions of magnolol with ergosterol at supramolecular level. The toxicity of magnolol on human erythrocytes was measured by in vitro hemolytic assay. MIC values of magnolol ranged from 16-64 μg/ml, respectively. All tested isolates showed a marked sensitivity towards magnolol in growth curve assays. Biofilm results suggested that magnolol showed strong anti-biofilm activity. The results obtained for four different Candida spp. demonstrated that MBIC values of magnolol showed the average biofilm inhibition by 69.5%, respectively. CLSM experiments showed that cells exposed to magnolol (MIC) exhibited cell membrane disruption. SEM analysis of magnolol treated cells resulted in deformed cells. TEM micrographs showed rupturing of the cell wall and plasma membrane, releasing the intracellular content, and swelling of the cell wall. Hemolytic activity of magnolol is 11.9% at its highest MIC compared to an activity level of 25.4% shown by amphotericin B (Amp B) at 1 μg/ml. Lipinski's parameters calculated for magnolol suggested its good oral bioavailability. Docking studies indicated that magnolol might be interacting with ergosterol in the fungal cell membranes. Together, the present study provides enough evidence for further work on magnolol so that better strategies could be employed to treat oral candidosis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Removal of Micrometer Size Morphological Defects and Enhancement of Ultraviolet Emission by Thermal Treatment of Ga-Doped ZnO Nanostructures

PubMed Central

Manzoor, Umair; Kim, Do K.; Islam, Mohammad; Bhatti, Arshad S.

2014-01-01

Mixed morphologies of Ga-doped Zinc Oxide (ZnO) nanostructures are synthesized by vapor transport method. Systematic scanning electron microscope (SEM) studies of different morphologies, after periodic heat treatments, gives direct evidence of sublimation. SEM micrographs give direct evidence that morphological defects of nanostructures can be removed by annealing. Ultra Violet (UV) and visible emission depends strongly on the annealing temperatures and luminescent efficiency of UV emission is enhanced significantly with each subsequent heat treatment. X-Ray diffraction (XRD) results suggest that crystal quality improved by annealing and phase separation may occur at high temperatures. PMID:24489725

Removal of micrometer size morphological defects and enhancement of ultraviolet emission by thermal treatment of Ga-doped ZnO nanostructures.

PubMed

Manzoor, Umair; Kim, Do K; Islam, Mohammad; Bhatti, Arshad S

2014-01-01

Mixed morphologies of Ga-doped Zinc Oxide (ZnO) nanostructures are synthesized by vapor transport method. Systematic scanning electron microscope (SEM) studies of different morphologies, after periodic heat treatments, gives direct evidence of sublimation. SEM micrographs give direct evidence that morphological defects of nanostructures can be removed by annealing. Ultra Violet (UV) and visible emission depends strongly on the annealing temperatures and luminescent efficiency of UV emission is enhanced significantly with each subsequent heat treatment. X-Ray diffraction (XRD) results suggest that crystal quality improved by annealing and phase separation may occur at high temperatures.

Analysis and comparison of focused ion beam milling and vibratory polishing sample surface preparation methods for porosity study of U-Mo plate fuel for research and test reactors.

PubMed

Westman, Bjorn; Miller, Brandon; Jue, Jan-Fong; Aitkaliyeva, Assel; Keiser, Dennis; Madden, James; Tucker, Julie D

2018-07-01

Uranium-Molybdenum (U-Mo) low enriched uranium (LEU) fuels are a promising candidate for the replacement of high enriched uranium (HEU) fuels currently in use in a high power research and test reactors around the world. Contemporary U-Mo fuel sample preparation uses focused ion beam (FIB) methods for analysis of fission gas porosity. However, FIB possess several drawbacks, including reduced area of analysis, curtaining effects, and increased FIB operation time and cost. Vibratory polishing is a well understood method for preparing large sample surfaces with very high surface quality. In this research, fission gas porosity image analysis results are compared between samples prepared using vibratory polishing and FIB milling to assess the effectiveness of vibratory polishing for irradiated fuel sample preparation. Scanning electron microscopy (SEM) imaging was performed on sections of irradiated U-Mo fuel plates and the micrographs were analyzed using a fission gas pore identification and measurement script written in MatLab. Results showed that the vibratory polishing method is preferentially removing material around the edges of the pores, causing the pores to become larger and more rounded, leading to overestimation of the fission gas porosity size. Whereas, FIB preparation tends to underestimate due to poor micrograph quality and surface damage leading to inaccurate segmentations. Despite the aforementioned drawbacks, vibratory polishing remains a valid method for porosity analysis sample preparation, however, improvements should be made to reduce the preferential removal of material surrounding pores in order to minimize the error in the porosity measurements. Copyright © 2018 Elsevier Ltd. All rights reserved.

Transmission Electron Microscopy of Bombyx Mori Silk Fibers

NASA Astrophysics Data System (ADS)

Shen, Y.; Martin, D. C.

1997-03-01

The microstructure of B. Mori silk fibers before and after degumming was examined by TEM, selected area electron diffraction (SAED), WAXS and low voltage SEM. SEM micrographs of the neat cocoon revealed a network of pairs of twisting filaments. After degumming, there were only individual filaments showing a surface texture consistent with an oriented fibrillar structure in the fiber interior. WAXS patterns confirmed the oriented beta-sheet crystal structure common to silkworm and spider silks. Low dose SAED results were fully consistent with the WAXS data, and revealed that the crystallographic texture did not vary significantly across the fiber diameter. TEM observations of microtomed fiber cross sections indicated a somewhat irregular shape, and also revealed a 0.5-2 micron sericin coating which was removed by the degumming process. TEM observations of the degummed silk fiber showed banded features with a characteristic spacing of nominally 600 nm along the fiber axis. These bands were oriented in a roughly parabolic or V-shape pointing along one axis within a given fiber. We hypothesize that this orientation is induced by the extrusion during the spinning process. Equatorial DF images revealed that axial and lateral sizes of the β-sheet crystallites in silk fibroin ranged from 20 to 170 nm and from 1 to 24 nm, respectively. Crazes developed in the degummed silk fiber parallel to the fiber direction. The formation of these crazes suggests that there are significant lateral interactions between fibrils in silk fibers.

Chemical crosslinking of acrylic acid to form biocompatible pH sensitive hydrogel reinforced with cellulose nanocrystals (CNC)

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

Lim, Lim Sze; Ahmad, Ishak; Lazim, Mohd Azwani Shah Mat

2014-09-03

The purpose of this study is to produce a novel pH and temperature sensitive hydrogel, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. The PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) with CNC entrapped in PAA matrix. The mixture was casted onto petri dish to obtain disc shape hydrogel. The effects of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH and temperature were studied.more » The obtained hydrogel was further subjected to different tests such swelling test for swelling behaviour at different pH and temperature along with scanning electron microscopy (SEM) for morphology analysis. The hydrogel obtained showed excellent pH sensitivity and obtained maximum swelling at pH 7. Besides that, hydrogel obtained showed significant increase in swelling ratio when temperature of swelling medium was increased from 25°C to 37°C. SEM micrograph showed that the pore size of the hydrogel decreases with increase of CNC content proving that the hydrogel structure became more rigid with addition of CNC. The PAA/CNC hydrogel with such excellent sensitivity towards pH and temperature can be developed further as drug carrier.« less

Preparation of a new composite combining strengthened β-tricalcium phosphate with platelet-rich plasma as a potential scaffold for the repair of bone defects

PubMed Central

WANG, CHENGGONG; ZHONG, DA; ZHOU, XING; YIN, KE; LIAO, QIANDE; KONG, LINGYU; LIU, ANSONG

2014-01-01

β-tricalcium phosphate (β-TCP) and platelet-rich plasma (PRP) are commonly used in bone tissue engineering. In the present study, a new composite combining strengthened β-TCP and PRP was prepared and its morphological and mechanical properties were investigated by scanning electron microscopy (SEM) and material testing. The biocompatibility was evaluated by measuring the adhesion rate and cytotoxicity of bone marrow stromal cells (BMSCs). The strengthened β-TCP/PRP composite had an appearance like the fungus Boletus kermesinus with the PRP gel distributed on the surface of the micropores. The maximum load and load intensity were 945.6±86.4 N and 13.1±0.5 MPa, which were significantly higher than those of β-TCP (110.1±14.3 N and 1.6±0.2 MPa; P<0.05). The BMSC adhesion rate on the strengthened β-TCP/PRP composite was >96% after 24 h, with a cell cytotoxicity value of zero. SEM micrographs revealed that following seeding of BMSCs onto the composite in high-glucose Dulbecco’s modified Eagle’s medium culture for two weeks, the cells grew well and exhibited fusiform, spherical and polygonal morphologies, as well as pseudopodial connections. The strengthened β-TCP/PRP composite has the potential to be used as a scaffold in bone tissue engineering due to its effective biocompatibility and mechanical properties. PMID:25187800

Influence of Ultrafine 2CaO·SiO₂ Powder on Hydration Properties of Reactive Powder Concrete.

PubMed

Sun, Hongfang; Li, Zishanshan; Memon, Shazim Ali; Zhang, Qiwu; Wang, Yaocheng; Liu, Bing; Xu, Weiting; Xing, Feng

2015-09-17

In this research, we assessed the influence of an ultrafine 2CaO·SiO₂ powder on the hydration properties of a reactive powder concrete system. The ultrafine powder was manufactured through chemical combustion method. The morphology of ultrafine powder and the development of hydration products in the cement paste prepared with ultrafine powder were investigated by scanning electron microscopy (SEM), mineralogical composition were determined by X-ray diffraction, while the heat release characteristics up to the age of 3 days were investigated by calorimetry. Moreover, the properties of cementitious system in fresh and hardened state (setting time, drying shrinkage, and compressive strength) with 5% ordinary Portland cement replaced by ultrafine powder were evaluated. From SEM micrographs, the particle size of ultrafine powder was found to be up to several hundred nanometers. The hydration product started formulating at the age of 3 days due to slow reacting nature of belitic 2CaO·SiO₂. The initial and final setting times were prolonged and no significant difference in drying shrinkage was observed when 5% ordinary Portland cement was replaced by ultrafine powder. Moreover, in comparison to control reactive powder concrete, the reactive powder concrete containing ultrafine powder showed improvement in compressive strength at and above 7 days of testing. Based on above, it can be concluded that the manufactured ultrafine 2CaO·SiO₂ powder has the potential to improve the performance of a reactive powder cementitious system.

Formation of silicon nanowire packed films from metallurgical-grade silicon powder using a two-step metal-assisted chemical etching method.

PubMed

Ouertani, Rachid; Hamdi, Abderrahmen; Amri, Chohdi; Khalifa, Marouan; Ezzaouia, Hatem

2014-01-01

In this work, we use a two-step metal-assisted chemical etching method to produce films of silicon nanowires shaped in micrograins from metallurgical-grade polycrystalline silicon powder. The first step is an electroless plating process where the powder was dipped for few minutes in an aqueous solution of silver nitrite and hydrofluoric acid to permit Ag plating of the Si micrograins. During the second step, corresponding to silicon dissolution, we add a small quantity of hydrogen peroxide to the plating solution and we leave the samples to be etched for three various duration (30, 60, and 90 min). We try elucidating the mechanisms leading to the formation of silver clusters and silicon nanowires obtained at the end of the silver plating step and the silver-assisted silicon dissolution step, respectively. Scanning electron microscopy (SEM) micrographs revealed that the processed Si micrograins were covered with densely packed films of self-organized silicon nanowires. Some of these nanowires stand vertically, and some others tilt to the silicon micrograin facets. The thickness of the nanowire films increases from 0.2 to 10 μm with increasing etching time. Based on SEM characterizations, laser scattering estimations, X-ray diffraction (XRD) patterns, and Raman spectroscopy, we present a correlative study dealing with the effect of the silver-assisted etching process on the morphological and structural properties of the processed silicon nanowire films.

Formation of silicon nanowire packed films from metallurgical-grade silicon powder using a two-step metal-assisted chemical etching method

PubMed Central

2014-01-01

In this work, we use a two-step metal-assisted chemical etching method to produce films of silicon nanowires shaped in micrograins from metallurgical-grade polycrystalline silicon powder. The first step is an electroless plating process where the powder was dipped for few minutes in an aqueous solution of silver nitrite and hydrofluoric acid to permit Ag plating of the Si micrograins. During the second step, corresponding to silicon dissolution, we add a small quantity of hydrogen peroxide to the plating solution and we leave the samples to be etched for three various duration (30, 60, and 90 min). We try elucidating the mechanisms leading to the formation of silver clusters and silicon nanowires obtained at the end of the silver plating step and the silver-assisted silicon dissolution step, respectively. Scanning electron microscopy (SEM) micrographs revealed that the processed Si micrograins were covered with densely packed films of self-organized silicon nanowires. Some of these nanowires stand vertically, and some others tilt to the silicon micrograin facets. The thickness of the nanowire films increases from 0.2 to 10 μm with increasing etching time. Based on SEM characterizations, laser scattering estimations, X-ray diffraction (XRD) patterns, and Raman spectroscopy, we present a correlative study dealing with the effect of the silver-assisted etching process on the morphological and structural properties of the processed silicon nanowire films. PMID:25349554

Influence of Ultrafine 2CaO·SiO2 Powder on Hydration Properties of Reactive Powder Concrete

PubMed Central

Sun, Hongfang; Li, Zishanshan; Memon, Shazim Ali; Zhang, Qiwu; Wang, Yaocheng; Liu, Bing; Xu, Weiting; Xing, Feng

2015-01-01

In this research, we assessed the influence of an ultrafine 2CaO·SiO2 powder on the hydration properties of a reactive powder concrete system. The ultrafine powder was manufactured through chemical combustion method. The morphology of ultrafine powder and the development of hydration products in the cement paste prepared with ultrafine powder were investigated by scanning electron microscopy (SEM), mineralogical composition were determined by X-ray diffraction, while the heat release characteristics up to the age of 3 days were investigated by calorimetry. Moreover, the properties of cementitious system in fresh and hardened state (setting time, drying shrinkage, and compressive strength) with 5% ordinary Portland cement replaced by ultrafine powder were evaluated. From SEM micrographs, the particle size of ultrafine powder was found to be up to several hundred nanometers. The hydration product started formulating at the age of 3 days due to slow reacting nature of belitic 2CaO·SiO2. The initial and final setting times were prolonged and no significant difference in drying shrinkage was observed when 5% ordinary Portland cement was replaced by ultrafine powder. Moreover, in comparison to control reactive powder concrete, the reactive powder concrete containing ultrafine powder showed improvement in compressive strength at and above 7 days of testing. Based on above, it can be concluded that the manufactured ultrafine 2CaO·SiO2 powder has the potential to improve the performance of a reactive powder cementitious system. PMID:28793560

Development of Thin Films as Potential Structural Cathodes to Enable Multifunctional Energy-Storage Structural Composite Batteries for the U.S. Army’s Future Force

DTIC Science & Technology

2011-09-01

glancing angle X - ray diffraction (GAXRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and electrochemical...Emission SEM FWHM full width at half maximum GAXRD glancing angle X - ray diffraction H3COCH2CH2OH 2-methoxyethanol LiMn2O4 lithium manganese oxide...were characterized by scanning electron microscopy (SEM), X - ray diffraction (XRD), and atomic force microscopy (AFM). In addition,

The effect of the distance between acidic site and basic site immobilized on mesoporous solid on the activity in catalyzing aldol condensation

NASA Astrophysics Data System (ADS)

Yu, Xiaofang; Yu, Xiaobo; Wu, Shujie; Liu, Bo; Liu, Heng; Guan, Jingqi; Kan, Qiubin

2011-02-01

Acid-base bifunctional heterogeneous catalysts containing carboxylic and amine groups, which were immobilized at defined distance from one another on the mesoporous solid were synthesized by immobilizing lysine onto carboxyl-SBA-15. The obtained materials were characterized by X-ray diffraction (XRD), N 2 adsorption, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron micrographs (SEM), transmission electron micrographs (TEM), elemental analysis, and back titration. Proximal-C-A-SBA-15 with a proximal acid-base distance was more active than maximum-C-A-SBA-15 with a maximum acid-base distance in aldol condensation reaction between acetone and various aldehydes. It appears that the distance between acidic site and basic site immobilized on mesoporous solid should be an essential factor for catalysis optimization.

Scanning electron microscopy of dentition: methodology and ultrastructural morphology of tooth wear.

PubMed

Shkurkin, G V; Almquist, A J; Pfeihofer, A A; Stoddard, E L

1975-01-01

Scanning electron micrographs were taken of sets of human molars-those of paleo-Indians used in mastication of, ostensibly, a highly abrasive diet, and those of contemporary Americans. Different ultrastructural patterns of enamel wear were observed between the groups.

Transmission electron microscopy of amyloid fibrils.

PubMed

Gras, Sally L; Waddington, Lynne J; Goldie, Kenneth N

2011-01-01

Transmission Electron Microscopy of negatively stained and cryo-prepared specimens allows amyloid fibrils to be visualised at high resolution in a dried or a hydrated state, and is an essential method for characterising the morphology of fibrils and pre-fibrillar species. We outline the key steps involved in the preparation and observation of samples using negative staining and cryo-electron preservation. We also discuss methods to measure fibril characteristics, such as fibril width, from electron micrographs.

CdS thin films prepared by continuous wave Nd:YAG laser

NASA Astrophysics Data System (ADS)

Wang, H.; Tenpas, Eric W.; Vuong, Khanh D.; Williams, James A.; Schuesselbauer, E.; Bernstein, R.; Fagan, J. G.; Wang, Xing W.

1995-08-01

We report new results on continuous wave Nd:YAG laser deposition of cadmium sulfide thin films. Substrates were soda-lime silicate glass, silica glass, silicon, and copper coated formvar sheets. As deposited films were mixtures of cubic and hexagonal phases, with two different grain sizes. As revealed by SEM micrographs, films had smooth surface morphology. As revealed by TEM analysis, grain sizes were extremely small.

Fabrication of high-k dielectric Calcium Copper Titanate (CCTO) target by solid state route

NASA Astrophysics Data System (ADS)

Tripathy, N.; Das, K. C.; Ghosh, S. P.; Bose, G.; Kar, J. P.

2016-02-01

CaCu3Ti4O12 (CCTO) ceramic pellet of 10mm diameter has been synthesized by adopting solid state route. The structural and morphological characterization of the ceramics sample was carried out by X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. XRD pattern revealed the CCTO phase formation, where as SEM micrograph shows the sample consisting of well defined grain and grain boundaries. The room temperature dielectric constant of the sample was found to be ∼ 5000 at 1kHz. After successful preparation of CCTO pellet, a 2 inch diameter CCTO sputtering target is also fabricated in order to deposit CCTO thin films for microelectronic applications.

3DSEM++: Adaptive and intelligent 3D SEM surface reconstruction.

PubMed

Tafti, Ahmad P; Holz, Jessica D; Baghaie, Ahmadreza; Owen, Heather A; He, Max M; Yu, Zeyun

2016-08-01

Structural analysis of microscopic objects is a longstanding topic in several scientific disciplines, such as biological, mechanical, and materials sciences. The scanning electron microscope (SEM), as a promising imaging equipment has been around for decades to determine the surface properties (e.g., compositions or geometries) of specimens by achieving increased magnification, contrast, and resolution greater than one nanometer. Whereas SEM micrographs still remain two-dimensional (2D), many research and educational questions truly require knowledge and facts about their three-dimensional (3D) structures. 3D surface reconstruction from SEM images leads to remarkable understanding of microscopic surfaces, allowing informative and qualitative visualization of the samples being investigated. In this contribution, we integrate several computational technologies including machine learning, contrario methodology, and epipolar geometry to design and develop a novel and efficient method called 3DSEM++ for multi-view 3D SEM surface reconstruction in an adaptive and intelligent fashion. The experiments which have been performed on real and synthetic data assert the approach is able to reach a significant precision to both SEM extrinsic calibration and its 3D surface modeling. Copyright © 2016 Elsevier Ltd. All rights reserved.

On the Progress of Scanning Transmission Electron Microscopy (STEM) Imaging in a Scanning Electron Microscope.

PubMed

Sun, Cheng; Müller, Erich; Meffert, Matthias; Gerthsen, Dagmar

2018-04-01

Transmission electron microscopy (TEM) with low-energy electrons has been recognized as an important addition to the family of electron microscopies as it may avoid knock-on damage and increase the contrast of weakly scattering objects. Scanning electron microscopes (SEMs) are well suited for low-energy electron microscopy with maximum electron energies of 30 keV, but they are mainly used for topography imaging of bulk samples. Implementation of a scanning transmission electron microscopy (STEM) detector and a charge-coupled-device camera for the acquisition of on-axis transmission electron diffraction (TED) patterns, in combination with recent resolution improvements, make SEMs highly interesting for structure analysis of some electron-transparent specimens which are traditionally investigated by TEM. A new aspect is correlative SEM, STEM, and TED imaging from the same specimen region in a SEM which leads to a wealth of information. Simultaneous image acquisition gives information on surface topography, inner structure including crystal defects and qualitative material contrast. Lattice-fringe resolution is obtained in bright-field STEM imaging. The benefits of correlative SEM/STEM/TED imaging in a SEM are exemplified by structure analyses from representative sample classes such as nanoparticulates and bulk materials.

New developments in electron microscopy for serial image acquisition of neuronal profiles.

PubMed

Kubota, Yoshiyuki

2015-02-01

Recent developments in electron microscopy largely automate the continuous acquisition of serial electron micrographs (EMGs), previously achieved by laborious manual serial ultrathin sectioning using an ultramicrotome and ultrastructural image capture process with transmission electron microscopy. The new systems cut thin sections and capture serial EMGs automatically, allowing for acquisition of large data sets in a reasonably short time. The new methods are focused ion beam/scanning electron microscopy, ultramicrotome/serial block-face scanning electron microscopy, automated tape-collection ultramicrotome/scanning electron microscopy and transmission electron microscope camera array. In this review, their positive and negative aspects are discussed. © 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.

Cryo-Scanning Electron Microscopy (SEM) and Scanning Transmission Electron Microscopy (STEM)-in-SEM for Bio- and Organo-Mineral Interface Characterization in the Environment.

PubMed

Wille, Guillaume; Hellal, Jennifer; Ollivier, Patrick; Richard, Annie; Burel, Agnes; Jolly, Louis; Crampon, Marc; Michel, Caroline

2017-12-01

Understanding biofilm interactions with surrounding substratum and pollutants/particles can benefit from the application of existing microscopy tools. Using the example of biofilm interactions with zero-valent iron nanoparticles (nZVI), this study aims to apply various approaches in biofilm preparation and labeling for fluorescent or electron microscopy and energy dispersive X-ray spectrometry (EDS) microanalysis for accurate observations. According to the targeted microscopy method, biofilms were sampled as flocs or attached biofilm, submitted to labeling using 4',6-diamidino-2-phenylindol, lectins PNA and ConA coupled to fluorescent dye or gold nanoparticles, and prepared for observation (fixation, cross-section, freezing, ultramicrotomy). Fluorescent microscopy revealed that nZVI were embedded in the biofilm structure as aggregates but the resolution was insufficient to observe individual nZVI. Cryo-scanning electron microscopy (SEM) observations showed nZVI aggregates close to bacteria, but it was not possible to confirm direct interactions between nZVI and cell membranes. Scanning transmission electron microscopy in the SEM (STEM-in-SEM) showed that nZVI aggregates could enter the biofilm to a depth of 7-11 µm. Bacteria were surrounded by a ring of extracellular polymeric substances (EPS) preventing direct nZVI/membrane interactions. STEM/EDS mapping revealed a co-localization of nZVI aggregates with lectins suggesting a potential role of EPS in nZVI embedding. Thus, the combination of divergent microscopy approaches is a good approach to better understand and characterize biofilm/metal interactions.

Novel Magnetic Zinc Oxide Nanotubes for Phenol Adsorption: Mechanism Modeling

PubMed Central

Elkady, Marwa F.; Hassan, Hassan Shokry; Amer, Wael A.; Salama, Eslam; Algarni, Hamed; Shaaban, Essam Ramadan

2017-01-01

Considering the great impact of a material’s surface area on adsorption processes, hollow nanotube magnetic zinc oxide with a favorable surface area of 78.39 m2/g was fabricated with the assistance of microwave technology in the presence of poly vinyl alcohol (PVA) as a stabilizing agent followed by sonic precipitation of magnetite nano-particles. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs identified the nanotubes’ morphology in the synthesized material with an average aspect ratio of 3. X-ray diffraction (XRD) analysis verified the combination of magnetite material with the hexagonal wurtzite structure of ZnO in the prepared material. The immobilization of magnetite nanoparticles on to ZnO was confirmed using vibrating sample magnetometry (VSM). The sorption affinity of the synthesized magnetic ZnO nanotube for phenolic compounds from aqueous solutions was examined as a function of various processing factors. The degree of acidity of the phenolic solution has great influence on the phenol sorption process on to magnetic ZnO. The calculated value of ΔH0 designated the endothermic nature of the phenol uptake process on to the magnetic ZnO nanotubes. Mathematical modeling indicated a combination of physical and chemical adsorption mechanisms of phenolic compounds on to the fabricated magnetic ZnO nanotubes. The kinetic process correlated better with the second-order rate model compared to the first-order rate model. This result indicates the predominance of the chemical adsorption process of phenol on to magnetic ZnO nanotubes. PMID:29186853

Optimizing the 3D-reconstruction technique for serial block-face scanning electron microscopy.

PubMed

Wernitznig, Stefan; Sele, Mariella; Urschler, Martin; Zankel, Armin; Pölt, Peter; Rind, F Claire; Leitinger, Gerd

2016-05-01

Elucidating the anatomy of neuronal circuits and localizing the synaptic connections between neurons, can give us important insights in how the neuronal circuits work. We are using serial block-face scanning electron microscopy (SBEM) to investigate the anatomy of a collision detection circuit including the Lobula Giant Movement Detector (LGMD) neuron in the locust, Locusta migratoria. For this, thousands of serial electron micrographs are produced that allow us to trace the neuronal branching pattern. The reconstruction of neurons was previously done manually by drawing cell outlines of each cell in each image separately. This approach was very time consuming and troublesome. To make the process more efficient a new interactive software was developed. It uses the contrast between the neuron under investigation and its surrounding for semi-automatic segmentation. For segmentation the user sets starting regions manually and the algorithm automatically selects a volume within the neuron until the edges corresponding to the neuronal outline are reached. Internally the algorithm optimizes a 3D active contour segmentation model formulated as a cost function taking the SEM image edges into account. This reduced the reconstruction time, while staying close to the manual reference segmentation result. Our algorithm is easy to use for a fast segmentation process, unlike previous methods it does not require image training nor an extended computing capacity. Our semi-automatic segmentation algorithm led to a dramatic reduction in processing time for the 3D-reconstruction of identified neurons. Copyright © 2016 Elsevier B.V. All rights reserved.

Microstructure and wear characterization of aluminum matrix composites reinforced with industrial waste fly ash particulates synthesized by friction stir processing

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

Dinaharan, I., E-mail: dinaweld2009@gmail.com

Fly ash (FA) is a waste product of coal combustion in thermal power plants which is available in massive quantities all over the world causing land pollution. This paper reports the characterization of AA6061 aluminum matrix composites (AMCs) reinforced with FA particles synthesized using friction stir processing (FSP). The volume fraction of FA particles was varied from 0 to 18 in steps of 6. The prepared AMCs were characterized using optical microscopy (OM), scanning electron microscopy (SEM) and electron backscattered diagram (EBSD). The wear rate was estimated using a pin-on-disc wear apparatus. FA particles were observed to be distributed homogeneouslymore » in the AMC irrespective of the location within the stir zone. The EBSD micrographs revealed remarkable grain refinement in the AMC. The incorporation of FA particles enhanced the microhardness and wear resistance of the AMC. The strengthening mechanisms of the AMC were discussed and correlated to the observed microstructures. The wear mechanisms were identified by characterizing the wear debris and worn surfaces. - Highlights: •Industrial waste fly ash was used to produce aluminum matrix composites. •Friction stir processing was used to produce AA6061/Fly Ash composite. •Fly ash particles refined the grains of aluminum matrix. •Fly ash particles enhanced the hardness and wear resistance. •Successful utilization of fly ash to make aluminum composites reduces land pollution.« less

Study of Aging-Induced Degradation of Fracture Resistance of Alloy 617 Toward High-Temperature Applications

NASA Astrophysics Data System (ADS)

Singh, Aditya Narayan; Moitra, A.; Bhaskar, Pragna; Sasikala, G.; Dasgupta, Arup; Bhaduri, A. K.

2017-07-01

For the Alloy 617, the effect of aging on the fracture energy degradation has been investigated after aging for different time periods at 1023 K (750 °C). A sharp reduction in impact energy (by 55 pct vis-à-vis the as-received material) after 1000 hours of aging, as evaluated from room-temperature Charpy impact tests, has been observed. Further aging up to 10,000 hours has led to a degradation of fracture energy up to 78 pct. Fractographic examinations using scanning electron microscopy (SEM) have revealed a change in fracture mode from fibrous-ductile for the un-aged material to intergranular mode for the aged one. The extent of intergranular fracture increases with the increasing aging time, indicating a tendency of the material to undergo grain boundary embrittlement over long-term aging. Analysis of the transmission electron microscopy (TEM) micrographs along with selected area diffraction (SAD) patterns for the samples aged at 10,000 hours revealed finely dispersed γ' precipitates of size 30 to 40 nm, rich in Al and Ti, along with extensive precipitation of M23C6 at the grain boundaries. In addition, the presence of Ni3Si of size in the range of 110 to 120 nm also has been noticed. The extensive precipitation of M23C6 at the grain boundaries have been considered as a major reason for aging-induced embrittlement of this material.

Enhancement of aptamer immobilization using egg shell-derived nano-sized spherical hydroxyapatite for thrombin detection in neuroclinic.

PubMed

Derkus, Burak; Arslan, Yavuz Emre; Emregul, Kaan C; Emregul, Emel

2016-09-01

In the present study, we describe the sonochemical isolation of nano-sized spherical hydroxyapatite (nHA) from egg shell and application towards thrombin aptasensing. In addition to the sonochemical method, two conventional methods present in literature were carried out to perform a comparative study. Various analysis methods including Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Energy-Dispersive Analysis of X-Rays (EDAX), and Thermal Gravimetric Analysis (TGA) have been applied for the characterization of nHA and its nanocomposite with marine-derived collagen isolated from Rhizostoma pulmo jellyfish. TEM micrographs revealed the sonochemically synthesized nHA nanoparticles to have a unique porous spherical shape with a diameter of approximately 60-80nm when compared to hydroxyapatite nanoparticles synthesized using the other two methods which had a typical needle shaped morphology. EDAX, XRD and FTIR results demonstrated that the obtained patterns belonged to hydroxyapatite. Electrochemical impedance spectroscopy (EIS) is the main analyzing technique of the developed thrombin aptasensor. The proposed aptasensor has a detection limit of 0.25nM thrombin. For clinical application of the developed aptasensor, thrombin levels in blood and cerebrospinal fluid (CSF) samples obtained from patients with Multiple Sclerosis, Myastenia Gravis, Epilepsy, Parkinson, polyneuropathy and healthy donors were analyzed using both the aptasensor and commercial ELISA kit. The results showed that the proposed system is a promising candidate for clinical analysis of thrombin. Copyright © 2016 Elsevier B.V. All rights reserved.

Wood decay: a submicroscopic view

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

Blanchette, R.A.

1980-01-01

Typical patterns of decay in softwoods are shown by ultrastructural differences revealed by SEM. Illustrative micrographs are reproduced showing fungi and their effects. Brown rot fungi (e.g. Fomitopsis pinicolor) degrade cellulose leaving a lignin skeleton. White rot fungi (e.g. Coriolus versicolor and Hirschioporus abietinus) degrade both lignin and cellulose. White pocket rots (e.g. Phellinus pini) primarily degrade lignin; they have potential for use in paper making, or the production of animal feed.

Mechanical Property Comparison of the Soviet BS-41 and the US M993 Armor-Penetrating Cores

DTIC Science & Technology

2016-11-23

influences the formation of cracks at the tips of hardness indentations. The observations from the optical and SEM micrographs allow one to better...core is a fine-grained WC cemented in cobalt. The M993 core was determined to have superior hardness and indentation toughness. The superior... hardness , toughness, microstructure, composition 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 20 19a

Contributions of Stress and Oxidation on the Formation of Whiskers in Pb-free Solders

DTIC Science & Technology

2016-01-29

environmental factors influencing formation of tin whiskers on electrodeposited lead free, tin coatings over copper (or copper containing) substrates is the...Oxidation on the Formation of Whiskers in Pb‐free Solders,” WP-1754 15. SUBJECT TERMS Tin Whiskers, Residual Stress, Environmental Degradation 16...showing the surface of a tin film with whisker .................... 2 Figure 2: SEM Micrograph of Tin film on Copper Substrate cross-sectioned by FIB

Synthesis of boron nitride coatings on quartz fibers: Thickness control and mechanism research

NASA Astrophysics Data System (ADS)

Zheng, Yu; Wang, Shubin

2011-10-01

Boron nitride (BN) coatings were successfully synthesized on quartz fibers by dip-coating in boric acid and urea solutions at 700 °C. The SEM micrographs indicated that the quartz fibers were fully covered by coatings with smooth surface. The XRD, FT-IR, XPS spectra and HR-TEM results showed that the composition of the coatings which combined closely with the quartz fibers was polycrystalline h-BN. By changing the dip circles, the coating thickness was well controlled. The thicknesses of samples dipped less than six circles increased linearly with dipping-circles; and the increment of coating thickness would slow down when the fibers were dipped 10 circles. After being dipped for 10 circles, the thickness was about 300 nm. The coating thickness was also established by calculation and the calculated results were consistent with the results measured by micrograph.

Characterization of Limestone as Raw Material to Hydrated Lime

NASA Astrophysics Data System (ADS)

Salem Hwidi, Rajeb; Nuraiti Tengku Izhar, Tengku; Saad, Farah Naemah Mohd

2018-03-01

In Malaysia, limestone is essentially important for the economic growth as raw materials in the industry sector. Nevertheless, a little attention was paid to the physical, chemical, mineralogical, and morphological properties of the limestone using X-ray fluorescence (X-RF), X-ray diffraction (X-RD), Fourier transform infrared spectroscopy (FTIR), and Scanning electron microscopy / energy dispersive x-ray spectroscopy (SEM-EDS) respectively. Raw materials (limestone rocks) were collected from Bukit Keteri area, Chuping, Kangar, Perlis, Malaysia. Lab crusher and lab sieved were utilized to prepare five different size of ground limestone at (75 µm, 150 µm, 225 µm, 300, and 425 µm) respectively. It is found that the main chemical composition of bulk limestone was Calcium oxide (CaO) at 97.58 wt.% and trace amount of MnO, Al2O3, and Fe2O3 at 0.02%, 0.35%, and 0.396% respectively. XRD diffractograms showed characteristic peaks of calcite and quartz. Furthermore, main FTIR absorption bands at 1,419, 874.08 and 712.20 cm-1 indicated the presence of calcite. The micrographs showed clearly the difference of samples particle size. Furthermore, EDS peaks of Ca, O, and C elements confirmed the presence of CaCO3 in the samples.

Effects of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) microparticles on morphological, mechanical, thermal, and barrier properties in thermoplastic potato starch films.

PubMed

Malmir, Sara; Montero, Belén; Rico, Maite; Barral, Luis; Bouza, Rebeca; Farrag, Yousof

2018-08-15

Biocomposites of potato starch/poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) microparticles were prepared through the solvent casting method. Glycerol was used as a plasticizer. The effects of concentrations of PHBV microparticles as filler and glycerol on crystallinity behavior, surface morphology, dynamic mechanical properties, and thermal stability were studied. Humidity absorption and the water vapor transmission rate (WVTR) were investigated as well. Wide angle X-ray scattering (WAXS) patterns revealed that the plasticizing process occurred successfully. Scanning electron microscopy (SEM) micrographs exhibited good homogeneity of the surfaces for the biocomposites with a lower glycerol concentration. Dynamic mechanical analysis (DMA) results confirmed the reinforcing effect of PHBV microparticles inside the matrix. Thermogravimetric analysis (TGA) indicated that the presence of PHBV microparticles increased the thermal stability of the starch. Results of humidity absorption tests showed that the high hydrophilicity of the starch was reduced once the PHBV microparticles had been incorporated. Also, increasing PHBV microparticles reduced the water vapor transmission rate. However, samples with reduced glycerol content absorbed less humidity and showed a lower water vapor transmission rate. Copyright © 2018 Elsevier Ltd. All rights reserved.

Production of a cellulase-free alkaline xylanase from Bacillus pumilus MTCC 5015 by submerged fermentation and its application in biobleaching.

PubMed

Thomas, Leya; Sindhu, Raveendran; Binod, Parameswaran; Pandey, Ashok

2015-06-01

Here, we described the production of a cellulase-free alkaline xylanase from Bacillus pumilus MTCC 5015 by submerged fermentation and its application in biobleaching. Various process parameters affecting xylanase production by B. pumilus were optimized by adopting a Plackett-Burman design (PBD) as well as Response surface methodology (RSM). These statistical methods aid in improving the enzyme yield by analysing the individual crucial components of the medium. Maximum production was obtained with 4% yeast extract, 0.08% magnesium sulphate, 30 h of inoculum age, incubation temperature of 33.5 degrees C and pH 9.0. Under optimized conditions, the xylanase activity was 372 IU/ml. Media engineering improved a 5-fold increase in the enzyme production. Scanning electron microscopy (SEM) showed significant changes on the surface of xylanase treated pulps as a result of xylan hydrolysis. Increased roughness of paper carton fibres was apparent in scanning electron micrograph due to opening of the micro fibrils present on the surface by xylanase action. The untreated pulp did not show any such change. These results demonstrated that the B. pumilus MTCC 5015 xylanase was effective in bio-bleaching of paper carton.

Tuning the optical properties of ZnO nanorods by variation of precursor concentration through hydrothermal method

NASA Astrophysics Data System (ADS)

Kumari, Lakshmi; Kar, Asit Kumar

2018-05-01

ZnO nanorods with varying precursor concentration have been successfully synthesized by the hydrothermal method. The effect of the precursor concentration on the structural, morphological and optical properties of the resulting nanorods was investigated by means of X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), UV-Vis spectroscopy and photoluminescence (PL) spectroscopy. The crystalline structural characterization demonstrated that the synthesized materials crystallize in pure ZnO wurtzite structure without any other secondary phase. SEM micrographs demonstrate nanorod type features in all the samples. In addition, they show that increase of precursor concentration changes the length and diameter of nanorods. The UV-Vis studies show a strong absorption band in UV region at 373 nm attributed to the band-edge absorption of wurtzite hexagonal ZnO, blue shifted relative to its bulk form (380 nm). The PL spectra of obtained nanorods excited at 360 nm present broad visible emission. Moreover, as the visible region (from 510 to 550 nm) is concerned, it is speculated that the increase of the precursor concentration affects strongly the kind of interstitial defects (Oi, Zni and Vo) formed in ZnO nanorods. The luminescence intensity decreases with the increase of precursor concentration.

Physicochemical and mechanical properties of freeze cast hydroxyapatite-gelatin scaffolds with dexamethasone loaded PLGA microspheres for hard tissue engineering applications.

PubMed

Ghorbani, Farnaz; Nojehdehian, Hanieh; Zamanian, Ali

2016-12-01

Hydroxyapatite (HA)-gelatin scaffolds incorporated with dexamethasone-loaded polylactic-co-glycolic acid (PLGA) microspheres were synthesized by freeze casting technique. Scanning electron microscopy (SEM) micrographs demonstrated a unidirectional microstructure and a decrease in the pore size as a function of temperature gradient. Higher amounts of HA resulted in a decrease in the pore size. According to the results, at lower cooling rates, the formation of a lamellar structure decreased the mechanical strength, but at the same time, enhanced the swelling ratio, biodegradation rate and drug release level. On the other hand, higher weight ratios of HA increased the compressive strength, and reduced the swelling ratio, biodegradation rate and drug release level. The results obtained by furrier transform infrared spectroscopy (FTIR) and bioactivity analysis illustrated that the interactions of the materials support the apatite formation in the simulated body fluid (SBF) solution. Based on the obtained results, the synthesized composite scaffolds have the necessary mechanical and physicochemical features to support the regeneration of defects and to maintain their stability during the neo-tissue formation. Copyright © 2016 Elsevier B.V. All rights reserved.

Microwave sintering of nanopowder ZnNb2O6: Densification, microstructure and microwave dielectric properties

NASA Astrophysics Data System (ADS)

Bafrooei, H. Barzegar; Nassaj, E. Taheri; Hu, C. F.; Huang, Q.; Ebadzadeh, T.

2014-12-01

High density ZnNb2O6 ceramics were successfully fabricated by microwave sintering of ZnO-Nb2O5 and ZnNb2O6 nanopowders. Phase formation, microstructure and microwave electrical properties of the microwave sintered (MS) and microwave reaction sintered (MRS) specimens were examined using X-ray diffraction, field emission scanning electron microscopy and microwave dielectric properties measurement. Specimens were sintered in a temperature range from 950 to 1075 °C for 30 min at an interval of 25 °C using a microwave furnace operated at 2.45 GHz frequency, 3 kW power. XRD pattern revealed the formation of pure columbite phase of ZnNb2O6. The SEM micrographs show grain growth and reduction in porosity of specimens with the increase in sintering temperature. Good combination of microwave dielectric properties (εr~23.6, Qf~64,300 GHz and τf~-66 ppm/°C and εr~24, Qf~75,800 GHz and τf~-64 ppm/°C) was obtained for MS- and MRS-prepared samples at 1000 °C and 1050 °C for 30 min, respectively.

Development and evaluation of novel flavour microcapsules containing vanilla oil using complex coacervation approach.

PubMed

Yang, Ziming; Peng, Zheng; Li, Jihua; Li, Sidong; Kong, Lingxue; Li, Puwang; Wang, Qinghuang

2014-02-15

A novel flavour microcapsule containing vanilla oil (VO) was developed using complex coacervation approach, aimed to control release of VO and enhance its thermostability for spice application in food industry. Viscosity of chitosan (CS) and VO/CS ratio were optimised for fabrication of microcapsules. The flavour microcapsules were evaluated by scanning electron micrograph (SEM), laser confocal microscopy (LSCM), particle size analyser, infrared spectrometer (FT-IR), thermal analysis and controlled-release analysis. The microcapsules were in spherical with good dispersibility when moderate viscosity CS was used. 94.2% of encapsulation efficiency was achieved in VO/CS ratio of 2:1. The FT-IR study proved chemical cross-linking reaction occurred between genipin and chitosan, but a physical interaction between CS and VO. A core-shell structure of microcapsule was confirmed by LSCM, which was beneficial to improve the thermostability of VO in microcapsule. Moreover, VO could be remained about 60% in the microcapsules after release for 30 days, which demonstrated the flavour microcapsules had good potential to serve as a high quality food spice with long residual action and high thermostability. Copyright © 2013 Elsevier Ltd. All rights reserved.

Fabrication and Piezoelectric Properties of Textured (Bi1/2K1/2)TiO3 Ferroelectric Ceramics

NASA Astrophysics Data System (ADS)

Nagata, Hajime; Saitoh, Masahiro; Hiruma, Yuji; Takenaka, Tadashi

2010-09-01

Textured (Bi1/2K1/2)TiO3 (BKT) ceramics were prepared by a reactive templated grain growth (RTGG) method to improve their piezoelectric properties. Also, a hot-pressing (HP) method was modified on the basis of RTGG method to obtain dense ceramics and promote the grain orientation. The textured BKT ceramics prepared by the RTGG and HP methods exhibited a relatively high orientation factor F of 0.82 and a high density ratio of 95-99%. Scanning electron microscopy (SEM) micrographs of the textured HP-BKT indicated a textured and poreless microstructure. In addition, the resistivity of the textured HP-BKT was 1.73×1013 Ω·cm. The piezoelectric strain constant d33 determined by means of resonance and antiresonance method was 125 pC/N for the direction parallel to the sheet-stacking direction of the RTGG process. From the measurement of field-induced stain, the normalized d33* (=Smax/Emax) at 80 kV/cm were 127 and 238 pm/V on the randomly oriented and textured samples (F=0.82) for the (∥) direction, respectively.

Enhancing micrographs obtained with a scanning acoustic microscope using false-color encoding

NASA Astrophysics Data System (ADS)

Hammer, R.; Hollis, R. L.

1982-04-01

The periodic signal variations observed in reflection acoustic microscopy when lens-to-sample spacing is changed lead to reversals in image contrast. This contrast mechanism can be described by a V(Z) function, where V is the transducer voltage and Z the lens-to-sample spacing. In this work we show how by obtaining V(Z) curves from each plane of a complex sample, judicious choices of focal positions can be made to optimize signals from planes of interest, which allows color encoding of the image from each plane in an overlay image. We present false-color micrographs obtained in this way, along with A scans and V(Z) curves to demonstrate the technique.

Evaluation of different sterilization and disinfection methods on commercially made preformed crowns.

PubMed

Yilmaz, Y; Guler, C

2008-12-01

The aim of this study was to evaluate the changes caused by different sterilization or disinfection methods on the vestibular surface of four commercially made preformed crowns using stereomicroscopy and scanning electron microscopy (SEM). Preformed crowns (NuSmile Primary Anterior Crown (NSC), Kinder Krowns (KK), Pedo Pearls (PP) and polycarbonate crowns (PC)) were sterilized and/or disinfected by one of the following techniques: no sterilization or disinfection (G1 control group); steam autoclaving at 134 degrees C (30 psi) for 4 min (G2); steam autoclaving at 134 degrees C (30 psi) for 12 min (G3); steam autoclaving at 121 degrees C (15 psi) for 30 min (G4); and ultrasonication in a bath containing 4% Lysetol AF for 5 min at room temperature (chemical disinfection) (G5). Scanning electron micrographs of the crowns were taken before and after their sterilization or disinfection. The changes on the vestibular surface were then scored for the presence or absence of crazing, contour alteration, fracturing, and vestibular surface changes. The data were analyzed statistically using the chi-square test. No changes were observed before and after sterilization or disinfection in the stereomicroscopic evaluation of the vestibular surface of the crowns. However, all methods in which steam autoclaving was used to sterilize the crowns caused significant (P < 0.05) crazing and contour alterations of the vestibular surface of the crowns when they were examined by SEM. Chemical disinfection using an aldehyde-free disinfectant is the preferred method of disinfection for crowns that have been used previously in other dental patients.

Effect of carboxymethyl cellulose concentration on physical properties of biodegradable cassava starch-based films

PubMed Central

2011-01-01

Background Cassava starch, the economically important agricultural commodity in Thailand, can readily be cast into films. However, the cassava starch film is brittle and weak, leading to inadequate mechanical properties. The properties of starch film can be improved by adding plasticizers and blending with the other biopolymers. Results Cassava starch (5%w/v) based films plasticized with glycerol (30 g/100 g starch) were characterized with respect to the effect of carboxymethyl cellulose (CMC) concentrations (0, 10, 20, 30 and 40%w/w total solid) and relative humidity (34 and 54%RH) on the mechanical properties of the films. Additionally, intermolecular interactions were determined by Fourier transform infrared spectroscopy (FT-IR), melting temperature by differential scanning calorimetry (DSC), and morphology by scanning electron microscopy (SEM). Water solubility of the films was also determined. Increasing concentration of CMC increased tensile strength, reduced elongation at break, and decreased water solubility of the blended films. FT-IR spectra indicated intermolecular interactions between cassava starch and CMC in blended films by shifting of carboxyl (C = O) and OH groups. DSC thermograms and SEM micrographs confirmed homogeneity of cassava starch-CMC films. Conclusion The addition of CMC to the cassava starch films increased tensile strength and reduced elongation at break of the blended films. This was ascribed to the good interaction between cassava starch and CMC. Cassava starch-CMC composite films have the potential to replace conventional packaging, and the films developed in this work are suggested to be suitable for low moisture food and pharmaceutical products. PMID:21306655

Graphene oxide-silica nanohybrids as fillers for PA6 based nanocomposites

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

Maio, A.; Fucarino, R.; Khatibi, R.

Graphene oxide (GO) was prepared by oxidation of graphite flakes by a mixture of H{sub 2}SO{sub 4}/H{sub 3}PO{sub 4} and KMnO{sub 4} based on Marcano's method. Two different masterbatches containing GO (33.3%) and polyamide-6 (PA6) (66.7%) were prepared both via solvent casting in formic acid and by melt mixing in a mini-extruder (Haake). The two masterbatches were then used to prepare PA6-based nanocomposites with a content of 2% in GO. For comparison, a nanocomposite by direct mixing of PA6 and GO (2%) and PA6/graphite nanocomposites were prepared, too. The oxidation of graphite into GO was assessed by X-ray diffraction (XRD),more » Micro-Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) analyses. All these techniques demonstrated the effectiveness of the graphite modification, since the results put into evidence that, after the acid treatment, interlayer distance, oxygen content and defects increased. SEM micrographs carried out on the nanocomposites, showed GO layers totally surrounded by polyamide-6, this feature is likely due to the strong interaction between the hydrophilic moieties located both on GO and on PA6. On the contrary, no interactions were observed when graphite was used as filler. Mechanical characterization, carried out by tensile and dynamic-mechanical tests, marked an improvement of the mechanical properties observed. Photoluminescence and EPR measurements were carried out onto nanoparticles and nanocomposites to study the nature of the interactions and to assess the possibility to use this class of materials as semiconductors or optical sensors.« less

Strength and microstructure of IPS Empress 2 glass-ceramic after different treatments.

PubMed

Oh, S C; Dong, J K; Lüthy, H; Schärer, P

2000-01-01

This investigation was designed to determine whether heat pressing and/or simulated heat treatments affect the flexure strength and microstructure of the lithium disilicate glass-ceramic of the IPS Empress 2 system. Four groups of the lithium disilicate glass-ceramic were prepared as follows: group 1 = as-received material; group 2 = heat-pressed material; group 3 = heat-pressed and stimulated initial heat-treated material; and group 4 = heat-pressed and simulated heat-treated material with full firings for a final restoration. Three-point bending tests and scanning electron microscopy (SEM) analysis were conducted. The flexure strength of group 2 was significantly higher than that of group 1. However, there were no significant differences in strength among groups 2, 3, and 4, or between groups 1 and 4. The SEM micrographs of the lithium disilicate glass-ceramic showed a closely packed, multidirectionally interlocking microstructure of numerous lithium disilicate crystals protruding from the glass matrix. The crystals in the glass matrix of the heat-pressed materials (groups 2, 3, and 4) were a little more homogeneous and about 2 times bigger than those of the as-received material (group 1). These changes of the microstructure were greatest between groups 1 and 2. However, there were no marked differences among groups 2, 3, and 4. Although there were significant increases in the strength and some changes of the microstructure after the heat-pressing operation, the combination of heat pressing and simulated subsequent heat treatments did not produce an increase of strength of IPS Empress 2 glass-ceramic.

TiO₂ sol-gel for formaldehyde photodegradation using polymeric support: photocatalysis efficiency versus material stability.

PubMed

Curcio, Monique S; Oliveira, Michel P; Waldman, Walter R; Sánchez, Benigno; Canela, Maria Cristina

2015-01-01

Photocatalysts supported on polymers are not frequently used in heterogeneous photocatalysis because of problems such as wettability and stability that affect photocatalysis conditions. In this work, we used polypropylene as support for TiO2 sol-gel to evaluate its stability and efficiency under UV radiation. We also tested the effect of the thermo-pressing PP/TiO2 system on the photocatalytic efficiency and stability under UV radiation. The films were characterized by scanning electron microscopy (SEM), UV-Vis spectroscopy and X-ray diffraction (XRD). The SEM micrographs showed that the films of TiO2 sol-gel onto PP has approximately 1.0-μm thick and regular surface and the generation of polypropylene nanowires on hot-pressed samples. XRD showed the formation of TiO2 anatase on the surface of the films made by dip-coating. All photocatalysts were tested in decontaminating air-containing gaseous formaldehyde (70 ppmv) presenting degradation of the target compound to the limit of detection. The photocatalysts showed no deactivation during the entire period tested (30 h), and its reuse after washing showed better photocatalytic performance than on first use. The photocatalyst showed the best results were tested for 360 h with no observed deactivation. Aging studies showed that the film of TiO2 causes different effects on the photostability of composites, with stabilizing effect when exposed to most energetic UVC radiation (λmax = 254 nm) and degradative effects when exposed to UVA radiation (λmax = 365 nm).

Inhibitory effect of xanthan gum and synergistic surfactant additives for mild steel corrosion in 1M HCl.

PubMed

Mobin, Mohammad; Rizvi, Marziya

2016-01-20

Natural polymer xanthan gum (XG) was investigated as eco friendly corrosion inhibitor for mild steel in 1M HCl at 30 °C, 40 °C, 50 °C and 60 °C, respectively. The inhibition studies were performed using gravimetric analysis, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), quantum chemical calculations, scanning electron microscopy (SEM), and UV-visible spectrophotometry. XG significantly reduces the corrosion rates of mild steel. The inhibition efficiency (IE) of the XG increased with increase in concentration, but decreased with temperature; the maximum IE of 74.24% was obtained at concentration of 1000 ppm at 30 °C. The inhibiting action of XG is synergistically enhanced on addition of very small amount of surfactants sodium dodecyl sulfate (SDS), cetyl pyridinium chloride (CPC) and Triton X-100 (TX). The effect of SDS is more pronounced than other surfactants. Potentiodynamic polarization studies confirm XG as a mixed type inhibitor. Results of weight loss measurements are in good agreement of the results of electrochemical measurements. The UV-visible spectroscopic results indicate the formation of complex between XG and Fe(2+) ions during corrosion reaction. Mechanism of inhibition was also investigated by calculating the thermodynamic and activation parameters like ΔG(0), Ea, ΔH and ΔS. The adsorption of inhibitor on mild steel surface obeys Langmuir adsorption isotherm. SEM micrographs show a clearly different morphology in presence of XG and XG-surfactant additives and confirmed the existence of an adsorbed protective film on the mild steel surface. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of fungal decay on the hygroscopic thickness swelling rate of lignocellulosic filler-polyolefin biocomposites

NASA Astrophysics Data System (ADS)

Kord, B.; Hosseinihashemi, S. Kh.

2014-01-01

The influence of fungal decay on the hygroscopic thickness swelling rate of lignocellulosic filler-polyolefin biocomposites has been investigated. Composites based on polypropylene (PP), bagasse fiber (BF), and a coupling agent (PP-g-MA) were made by melt compounding and injection molding. The weigt ratio of BF to PP was controlled at 60/40 for all blends. The amount of coupling agent was fixed at 2% for all formulations. The samples obtained were exposed to the action of brown-rot (Coniophora puteana) and white-rot (Trametes versicolor) fungi for 8, 12, and 16 weeks according to the Kolle-flask method. The thickness swelling of the samples was evaluated by immersing them in water at room temperature for several weeks. The morphology of the composites was characterized using the scanning electron microscopy (SEM). The results indicated that the fungal decay had an adverse affect on the dimensional stability of BF/PP composites due to an increase in the thickness swelling rate. The thickness swelling of white-rotted samples was higher than that of brown-rotted ones and control samples. Also, the thickness swelling of BF/PP composites increased with increasing time of fungal decay. In addition, after 16 weeks of exposure to white-rot fungi, the composites exhibited a higher parameter of swelling rate K SR than control samples. The K SR of the composites was influenced both by the type of rooting and the exposure time. Furthermore, the SEM micrographs showed that the extent of degradation increased with growing exposure time to fungi.

Graphene oxide-silica nanohybrids as fillers for PA6 based nanocomposites

NASA Astrophysics Data System (ADS)

Maio, A.; Fucarino, R.; Khatibi, R.; Botta, L.; Rosselli, S.; Bruno, M.; Scaffaro, R.

2014-05-01

Graphene oxide (GO) was prepared by oxidation of graphite flakes by a mixture of H2SO4/H3PO4 and KMnO4 based on Marcano's method. Two different masterbatches containing GO (33.3%) and polyamide-6 (PA6) (66.7%) were prepared both via solvent casting in formic acid and by melt mixing in a mini-extruder (Haake). The two masterbatches were then used to prepare PA6-based nanocomposites with a content of 2% in GO. For comparison, a nanocomposite by direct mixing of PA6 and GO (2%) and PA6/graphite nanocomposites were prepared, too. The oxidation of graphite into GO was assessed by X-ray diffraction (XRD), Micro-Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) analyses. All these techniques demonstrated the effectiveness of the graphite modification, since the results put into evidence that, after the acid treatment, interlayer distance, oxygen content and defects increased. SEM micrographs carried out on the nanocomposites, showed GO layers totally surrounded by polyamide-6, this feature is likely due to the strong interaction between the hydrophilic moieties located both on GO and on PA6. On the contrary, no interactions were observed when graphite was used as filler. Mechanical characterization, carried out by tensile and dynamic-mechanical tests, marked an improvement of the mechanical properties observed. Photoluminescence and EPR measurements were carried out onto nanoparticles and nanocomposites to study the nature of the interactions and to assess the possibility to use this class of materials as semiconductors or optical sensors.

Wavelength Independent Optical Microscopy and Lithography

DTIC Science & Technology

1987-10-31

methods have been used in the past to fabricate the submicron apertures needed in near-field microscopy (2-4). However, under this contract we developed an...screens. Durig, et al. (4) in Zurich produced apertures at the tip of a single crystal of quartz etched using HF to make a fine point and covered...stage pulling process was used . Scanning electron li __ NO iI |06 j JlliM ° wm ..... 3 micrographs of a 100nm diameter pipette and a 500nm diameter

Effect of reactive agent and transesterification catalyst on properties of PLA/PBAT blends

NASA Astrophysics Data System (ADS)

Pitivut, S.; Suttiruengwong, S.; Seadan, M.

2015-07-01

This research aimed to study the properties of poly (lactic acid) (PLA)/poly (butylene adipate-co-terephthalate) (PBAT) blends with two different reactive systems: free radical reaction through peroxide (Perkadox) and transesterification catalyst (tetrabutyl titanate; TBT). Two blends composed of PLA as a matrix phase with the composition of 80 and 70 percent by weight. PLA/PBAT blends with Perkadox were prepared in twin screw extruder, whereas PLA/PBAT blends with TBT were prepared in an internal mixer. The morphology of the blends was investigated by scanning electron microscope (SEM). Tensile and impact testingsof the blends were reported. In case of the blends with Perkadox, SEM micrographs revealed that the size of particles was substantially reduced when adding more Perkadox. Young's modulus and the tensile strength of all blend ratios were insignificantly changed, whereas the elongation at break was decreased when compared to non-reactive blends due to the possible crosslinking reaction as observed from melt flow index (MFI) values. When adding Perkadox, the impact strength of PLA/PBAT (80/20) remained almost unchanged. However, the impact strength of PLA/PBAT (70/30) was enhanced, increasing to 110% for 0.05 phr Perkadox. In case of the blends with TBT, SEM micrographs showed the decrease in the particle size of PBAT phase when adding TBT. Young's modulus and the tensile strength of all blend ratios were not different, but the elongation at break was improved when adding TBT owing to the transesterification reaction. For PLA/PBAT (80/20), the elongation at break was increased by 39%, whereas the elongation at break was increased by 15% for PLA/PLA (70/30). The impact strength of all blend ratios unaffected.

Application of fractal and grey level co-occurrence matrix analysis in evaluation of brain corpus callosum and cingulum architecture.

PubMed

Pantic, Igor; Dacic, Sanja; Brkic, Predrag; Lavrnja, Irena; Pantic, Senka; Jovanovic, Tomislav; Pekovic, Sanja

2014-10-01

This aim of this study was to assess the discriminatory value of fractal and grey level co-occurrence matrix (GLCM) analysis methods in standard microscopy analysis of two histologically similar brain white mass regions that have different nerve fiber orientation. A total of 160 digital micrographs of thionine-stained rat brain white mass were acquired using a Pro-MicroScan DEM-200 instrument. Eighty micrographs from the anterior corpus callosum and eighty from the anterior cingulum areas of the brain were analyzed. The micrographs were evaluated using the National Institutes of Health ImageJ software and its plugins. For each micrograph, seven parameters were calculated: angular second moment, inverse difference moment, GLCM contrast, GLCM correlation, GLCM variance, fractal dimension, and lacunarity. Using the Receiver operating characteristic analysis, the highest discriminatory value was determined for inverse difference moment (IDM) (area under the receiver operating characteristic (ROC) curve equaled 0.925, and for the criterion IDM≤0.610 the sensitivity and specificity were 82.5 and 87.5%, respectively). Most of the other parameters also showed good sensitivity and specificity. The results indicate that GLCM and fractal analysis methods, when applied together in brain histology analysis, are highly capable of discriminating white mass structures that have different axonal orientation.

A scanning electron microscope technique for studying the sclerites of Cichlidogyrus.

PubMed

Fannes, Wouter; Vanhove, Maarten P M; Huyse, Tine; Paladini, Giuseppe

2015-05-01

The genus Cichlidogyrus (Monogenea: Ancyrocephalidae) includes more than 90 species, most of which are gill parasites of African cichlid fishes. Cichlidogyrus has been studied extensively in recent years, but scanning electron microscope (SEM) investigations of the isolated hard parts have not yet been undertaken. In this paper, we describe a method for isolating and scanning the sclerites of individual Cichlidogyrus worms. Twenty-year-old, formol-fixed specimens of Cichlidogyrus casuarinus were subjected to proteinase K digestion in order to release the sclerites from the surrounding soft tissues. SEM micrographs of the haptoral sclerites and the male copulatory organ are presented. The ability to digest formol-fixed specimens makes this method a useful tool for the study of historical museum collections.

The Influence of Novel Alloying Additions on the Performance of Magnesium Alloy AZ31B

DTIC Science & Technology

2013-11-01

More recently, alloys using a variety of the rare earth elements have been developed. Typically, these alloys have shown significant improvements...in mechanical properties and to a lesser degree in corrosion performance. However, rare earth elements are often costly and heavier than Mg. Thus...1.0 0.004 Max — — Note: Fe = iron; RE = rare earth . SEM micrograph and energy-dispersive x-ray (EDX) results for selected alloys are shown in

Topical Meeting on Microphysics of Surfaces, Beams, and Adsorbates Held at Santa Fe, New Mexico on 4-6 February 1985.

DTIC Science & Technology

1985-12-18

during excimer laser ablation. Results are %%% Study on the Mechanism of Ion-Assisted Etching, F. H. M. correlated with interferometric measurements of...report on real time interferometric measurements of free electron density and laser induced .,- fluorescence studies of atoms and molecules in the...compared with morphology exam- Ined with Nomarski micrographs and SEM. In addition, the struc- ture and composition of the deposited lines were analysed

Morphological and physicochemical properties of dip-coated poly {(2,5-diyl pyrrole) [4-nitrobenzylidène]} (PPNB) thin films: towards photovoltaic applications

NASA Astrophysics Data System (ADS)

Mouchaal, Younes; Gherrass, Hamou; Bendoukha Reguig, Abdelkarim; Hachemaoui, Aïcha; Yahiaoui, Ahmed; Makha, Mohamed; Khelil, Abdelbacet; Bernede, Jean-Christian

2015-02-01

A new material: conjugated poly {(2,5-diyl pyrrole) [4-nitrobenzylidène]}, that we called (PPNB), has been synthesized and characterized. The cyclic voltammetry has been used in order to estimate first oxidation (Ep) and reduction (En) potentials of our polymer. These values have been assigned, respectively, to the position of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) and determination of the energy band gap which have been estimated to be 6.16, 3.89 and 2.27 eV respectively. Energy levels values of the HOMO and LUMO of the PPNB polymeric donor material were evaluated and the results are compatible with an electron transfer to C60 within an eventual junction, such values show that PPNB could be probed for applications in organic solar cells as donor material. PPNB Thin films have been deposited by dip-coating technique from Dichloromethane solvent with different polymer concentrations, and a dipping speed of 3.0 cm/min. For morphological characterization of the films scanning electron microscopy (SEM) was carried out. The samples, when observed by SEM, reveals that the films deposited are less dense, uniform. Cross-sectional SEM micrographs PPNB films show that thickness of the layers is homogeneous and has value of 35-40 nm. Optical characteristics of the polymer thin films were studied using UV-vis spectroscopy; absorption of wide range of wavelengths from 350 to 700 nm was observed. The optical band gap energy ranges between 1.9 eV and 1.94 eV. Based on these analyzes we realized heterojunction organic solar cells with the structure: ITO/Au/PPNB/C60/BCP/Al, the cells had a photovoltaique effect after J-V measuring, however the efficiency of photo generation under AM1.5 illumination was weak (about 0.02%) and needs to be improved.

Integration of a high-NA light microscope in a scanning electron microscope.

PubMed

Zonnevylle, A C; Van Tol, R F C; Liv, N; Narvaez, A C; Effting, A P J; Kruit, P; Hoogenboom, J P

2013-10-01

We present an integrated light-electron microscope in which an inverted high-NA objective lens is positioned inside a scanning electron microscope (SEM). The SEM objective lens and the light objective lens have a common axis and focal plane, allowing high-resolution optical microscopy and scanning electron microscopy on the same area of a sample simultaneously. Components for light illumination and detection can be mounted outside the vacuum, enabling flexibility in the construction of the light microscope. The light objective lens can be positioned underneath the SEM objective lens during operation for sub-10 μm alignment of the fields of view of the light and electron microscopes. We demonstrate in situ epifluorescence microscopy in the SEM with a numerical aperture of 1.4 using vacuum-compatible immersion oil. For a 40-nm-diameter fluorescent polymer nanoparticle, an intensity profile with a FWHM of 380 nm is measured whereas the SEM performance is uncompromised. The integrated instrument may offer new possibilities for correlative light and electron microscopy in the life sciences as well as in physics and chemistry. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

Comparison of SEM and VPSEM imaging techniques with respect to Streptococcus mutans biofilm topography.

PubMed

Weber, Kathryn; Delben, Juliana; Bromage, Timothy G; Duarte, Simone

2014-01-01

The study compared images of mature Streptococcus mutans biofilms captured at increasing magnification to determine which microscopy method is most acceptable for imaging the biofilm topography and the extracellular polymeric substance (EPS). In vitro S. mutans biofilms were imaged using (1) scanning electron microscopy (SEM), which requires a dehydration process; (2) SEM and ruthenium red (SEM-RR), which has been shown to support the EPS of biofilms during the SEM dehydration; and (3) variable pressure scanning electron microscopy (VPSEM), which does not require the intensive dehydration process of SEM. The dehydration process and high chamber vacuum of both SEM techniques devastated the biofilm EPS, removed supporting structures, and caused cracking on the biofilm surface. The VPSEM offered the most comprehensive representation of the S. mutans biofilm morphology. VPSEM provides similar contrast and focus as the SEM, but the procedure is far less time-consuming, and the use of hazardous chemicals associated with SEM dehydration protocol is avoided with the VPSEM. The inaccurate representations of the biofilm EPS in SEM experimentation is a possible source of inaccurate data and impediments in the study of S. mutans biofilms. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

SEM/EDS and optical microscopy analyses of microplastics in ocean trawl and fish guts.

PubMed

Wang, Zhong-Min; Wagner, Jeff; Ghosal, Sutapa; Bedi, Gagandeep; Wall, Stephen

2017-12-15

Microplastic particles from Atlantic and Pacific Ocean trawls, lab-fed fish guts and ocean fish guts have been characterized using optical microscopy and SEM/EDS in terms of size, morphology, and chemistry. We assessed whether these measurements could serve as a rapid screening process for subsequent identification of the likely microplastic candidates by micro-spectroscopy. Optical microscopy enabled morphological classification of the types of particles or fibers present in the sample, as well as the quantification of particle size ranges and fiber lengths. SEM/EDS analysis was used to rule out non-plastic particles and screen the prepared samples for potential microplastic, based on their element signatures and surface characteristics. Chlorinated plastics such as polyvinyl chloride (PVC) could be easily identified with SEM/EDS due to their unique elemental signatures including chlorine, as could mineral species that are falsely identified as plastics by optical microscopy. Particle morphology determined by optical microscopy and SEM suggests the fish ingested particles contained both degradation fragments from larger plastic pieces and also manufactured microplastics. SEM images of microplastic particle surfaces revealed characteristic cracks consistent with environmental exposure, as well as pigment particles consistent with manufactured materials. Most of the microplastic surfaces in the fish guts and ocean trawls were covered with biofilms, radiolarians, and crustaceans. Many of the fish stomachs contained micro-shell pieces which visually resembled microplastics. Copyright © 2017 Elsevier B.V. All rights reserved.

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...

A new electron microscope technique for the study of living materials.

PubMed

Kálmán, E

1979-07-01

In order to gain informations on the real structure of biological specimens the "wet technique" for electron microscopy has been developed. The construction and the working principle of a special microchamber are described. Applications of this technique for the investigation of blood cells, gametes and various bacteries are demonstrated by micrographs.

Review of free software tools for image analysis of fluorescence cell micrographs.

PubMed

Wiesmann, V; Franz, D; Held, C; Münzenmayer, C; Palmisano, R; Wittenberg, T

2015-01-01

An increasing number of free software tools have been made available for the evaluation of fluorescence cell micrographs. The main users are biologists and related life scientists with no or little knowledge of image processing. In this review, we give an overview of available tools and guidelines about which tools the users should use to segment fluorescence micrographs. We selected 15 free tools and divided them into stand-alone, Matlab-based, ImageJ-based, free demo versions of commercial tools and data sharing tools. The review consists of two parts: First, we developed a criteria catalogue and rated the tools regarding structural requirements, functionality (flexibility, segmentation and image processing filters) and usability (documentation, data management, usability and visualization). Second, we performed an image processing case study with four representative fluorescence micrograph segmentation tasks with figure-ground and cell separation. The tools display a wide range of functionality and usability. In the image processing case study, we were able to perform figure-ground separation in all micrographs using mainly thresholding. Cell separation was not possible with most of the tools, because cell separation methods are provided only by a subset of the tools and are difficult to parametrize and to use. Most important is that the usability matches the functionality of a tool. To be usable, specialized tools with less functionality need to fulfill less usability criteria, whereas multipurpose tools need a well-structured menu and intuitive graphical user interface. © 2014 Fraunhofer-Institute for Integrated Circuits IIS Journal of Microscopy © 2014 Royal Microscopical Society.

Electrocatalytically Active Nickel-Based Electrode Coatings Formed by Atmospheric and Suspension Plasma Spraying

NASA Astrophysics Data System (ADS)

Aghasibeig, M.; Mousavi, M.; Ben Ettouill, F.; Moreau, C.; Wuthrich, R.; Dolatabadi, A.

2014-01-01

Ni-based electrode coatings with enhanced surface areas, for hydrogen production, were developed using atmospheric plasma spray (APS) and suspension plasma spray (SPS) processes. The results revealed a larger electrochemical active surface area for the coatings produced by SPS compared to those produced by APS process. SEM micrographs showed that the surface microstructure of the sample with the largest surface area was composed of a large number of small cauliflower-like aggregates with an average diameter of 10 μm.

Studies on fabrication of glass fiber reinforced composites using polymer blends

NASA Astrophysics Data System (ADS)

Patel, R. H.; Kachhia, P. H.; Patel, S. N.; Rathod, S. T.; Valand, J. K.

2018-05-01

Glass fiber reinforced PVC/NBR composites have been fabricated via hot compression moulding process. PVC is brittle in nature and thus lower thermal stability. Therefore, to improve the toughness of PVC, NBR was incorporated in certain proportions. As both are polar and thus they are compatible. To improve the strength property further, these blends were used to fabricate glass fiber reinforced composites. SEM micrograph shows good wettability of the blend with glass fibers resulting in proper bonding which increase the strength of the composites.

Internal Structure and Physical Properties of Ceramics at High Temperatures

DTIC Science & Technology

1975-06-01

E u u o u •H to... o c a u c u ■a c m a ai C OJ i- n HI C E 01 H ( UJO ßui) (V/UJV) 9" c C TCC) I5J50 1500 1450 1400 1350 1300...l500oC,24hr Figure 3. SEM Micrographs of the Fractured Cross Sections of SIC Specimens Oxidized in ISO torr 02- 10 - —-"■""-*« t • o e

Nanographite-TiO2 photoanode for dye sensitized solar cells

NASA Astrophysics Data System (ADS)

Sharma, S. S.; Sharma, Khushboo; Sharma, Vinay

2016-05-01

Nanographite-TiO2 (NG-TiO2) composite was successfully synthesized by the hydrothermal method and its performance as the photoanode for dye-sensitized solar cells (DSSCs) was investigated. Environmental Scanning electron microscope (E-SEM) micrographs show the uniform distribution of TiO2 nanoflowers deposited over nanographite sheets. The average performance characteristics of the assembled cell in terms of short-ciruit current density (JSC), open circuit voltage (VOC), fill factor (FF) and photoelectric conversion efficiency (η) were measured.

Multi-Energy Processing for Novel Coating Technologies

DTIC Science & Technology

2014-12-18

tungsten carbide (WC) substrate (BS-6S, Basic Carbide Corp.) with a dimension of 25.4 x 25.4 x 1.6 mm^ and a cobalt composition of 6% was placed on a...as dopant sources. (a) No NH3 + No laser (b) NH3 added, No laser (c) 10.591 ^m Figure 4.4 SEM micrographs of the diamond films deposited using...typed 37 diamond. Nitrogen was widely used as n-typed dopant . Nitrogen-containing additives in CVD diamond growth led to severe deterioration of the

Effect of cement dosage and early curing towards Kuala Perlis dredged marine sediments: a ɛv - σv and SEM-EDX approach

NASA Astrophysics Data System (ADS)

Syakeera Nordin, Nurul; Chan, Chee-Ming

2017-11-01

Cement is the primary material used in solidifying the soft soils. This material was applied in solidifying Kuala Perlis dredged marine sediments (DMS). These unwanted sediments are classified as high plasticity silt, MH with 3.36 LL of wc/LL value. At dosage 10 and 20 % of cemented-DMS and 3 days curing time, compression curve results shows the settlement criteria were enhanced than the natural DMS. Unfortunately, the settlement criteria are not complies with the permissible settlement limit and applicable pressure. The formation of cementing compounds appears in the SEM micrograph for 10 and 20 % of cemented-DMS. EDX analysis shows the Ca:Si ratio were increased for cemented-DMS due to the formation of C-S-H gel.

Serial block face scanning electron microscopy--the future of cell ultrastructure imaging.

PubMed

Hughes, Louise; Hawes, Chris; Monteith, Sandy; Vaughan, Sue

2014-03-01

One of the major drawbacks in transmission electron microscopy has been the production of three-dimensional views of cells and tissues. Currently, there is no one suitable 3D microscopy technique that answers all questions and serial block face scanning electron microscopy (SEM) fills the gap between 3D imaging using high-end fluorescence microscopy and the high resolution offered by electron tomography. In this review, we discuss the potential of the serial block face SEM technique for studying the three-dimensional organisation of animal, plant and microbial cells.

Antibiofilm activity of Vetiveria zizanioides root extract against methicillin-resistant Staphylococcus aureus.

PubMed

Kannappan, Arunachalam; Gowrishankar, Shanmugaraj; Srinivasan, Ramanathan; Pandian, Shunmugiah Karutha; Ravi, Arumugam Veera

2017-09-01

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading human pathogen responsible for causing chronic clinical manifestation worldwide. In addition to antibiotic resistance genes viz. mecA and vanA, biofilm formation plays a prominent role in the pathogenicity of S. aureus by enhancing its resistance to existing antibiotics. Considering the role of folk medicinal plants in the betterment of human health from the waves of multidrug resistant bacterial infections, the present study was intended to explore the effect of Vetiveria zizanioides root on the biofilm formation of MRSA and its clinical counterparts. V. zizanioides root extract (VREX) showed a concentration-dependent reduction in biofilm formation without hampering the cellular viability of the tested strains. Micrographs of scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) portrayed the devastating impact of VREX on biofilm formation. In addition to antibiofilm activity, VREX suppresses the production of biofilm related phenotypes such as exopolysaccharide, slime and α-hemolysin toxin. Furthermore, variation in FT-IR spectra evidenced the difference in cellular factors of untreated and VREX treated samples. Result of mature biofilm disruption assay and down regulation of genes like fnbA, fnbB, clfA suggested that VREX targets these adhesin genes responsible for initial adherence. GC-MS analysis revealed the presence of sesquiterpenes as a major constituent in VREX. Thus, the data of present study strengthen the ethnobotanical value of V. zizanioides and concludes that VREX contain bioactive molecules that have beneficial effect over the biofilm formation of MRSA and its clinical isolates. Copyright © 2017 Elsevier Ltd. All rights reserved.

High-resolution x-ray diffraction microscopy of specifically labeled yeast cells

PubMed Central

Nelson, Johanna; Huang, Xiaojing; Steinbrener, Jan; Shapiro, David; Kirz, Janos; Marchesini, Stefano; Neiman, Aaron M.; Turner, Joshua J.; Jacobsen, Chris

2010-01-01

X-ray diffraction microscopy complements other x-ray microscopy methods by being free of lens-imposed radiation dose and resolution limits, and it allows for high-resolution imaging of biological specimens too thick to be viewed by electron microscopy. We report here the highest resolution (11–13 nm) x-ray diffraction micrograph of biological specimens, and a demonstration of molecular-specific gold labeling at different depths within cells via through-focus propagation of the reconstructed wavefield. The lectin concanavalin A conjugated to colloidal gold particles was used to label the α-mannan sugar in the cell wall of the yeast Saccharomyces cerevisiae. Cells were plunge-frozen in liquid ethane and freeze-dried, after which they were imaged whole using x-ray diffraction microscopy at 750 eV photon energy. PMID:20368463

High-resolution x-ray diffraction microscopy of specifically labeled yeast cells

DOE PAGES

Nelson, Johanna; Huang, Xiaojing; Steinbrener, Jan; ...

2010-04-20

X-ray diffraction microscopy complements other x-ray microscopy methods by being free of lens-imposed radiation dose and resolution limits, and it allows for high-resolution imaging of biological specimens too thick to be viewed by electron microscopy. We report here the highest resolution (11-13 nm) x-ray diffraction micrograph of biological specimens, and a demonstration of molecular-specific gold labeling at different depths within cells via through-focus propagation of the reconstructed wavefield. The lectin concanavalin A conjugated to colloidal gold particles was used to label the α-mannan sugar in the cell wall of the yeast Saccharomyces cerevisiae. Cells were plunge-frozen in liquid ethane andmore » freeze-dried, after which they were imaged whole using x-ray diffraction microscopy at 750 eV photon energy.« less

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

Buck, E.C.; Dietz, N.L.; Bates, J.K.

Uranium contaminated soils from the Fernald Operation Site, Ohio, have been examined by a combination of optical microscopy, scanning electron microscopy with backscattered electron detection (SEM/BSE), and analytical electron microscopy (AEM). A method is described for preparing of transmission electron microscopy (TEM) thin sections by ultramicrotomy. By using these thin sections, SEM and TEM images can be compared directly. Uranium was found in iron oxides, silicates (soddyite), phosphates (autunites), and fluorite. Little uranium was associated with clays. The distribution of uranium phases was found to be inhomogeneous at the microscopic level.

Multi-walled carbon nanotubes/graphene oxide hybrid and nanohydroxyapatite composite: A novel coating to prevent dentin erosion.

PubMed

Nahorny, Sídnei; Zanin, Hudson; Christino, Vinie Abreu; Marciano, Fernanda Roberta; Lobo, Anderson Oliveira; Soares, Luís Eduardo Silva

2017-10-01

To date is emergent the development of novel coatings to protect erosion, especially to preventive dentistry and restorative dentistry. Here, for the first time we report the effectiveness of multi-walled carbon nanotube/graphene oxide hybrid carbon-base material (MWCNTO-GO) combined with nanohydroxyapatite (nHAp) as a protective coating for dentin erosion. Fourier transform Raman spectroscopy (FT-Raman), scanning electron (SEM), and transmission electron (TEM) microscopy were used to investigated the coatings and the effect of acidulated phosphate fluoride gel (APF) treatment on bovine teeth root dentin before and after erosion. The electrochemical corrosion performance of the coating was evaluated. Raman spectra identified that: (i) the phosphate (ν 1 PO 4 3- ) content of dentin was not significantly affected by the treatments and (ii) the carbonate (ν 1 CO 3 2- ) content in dentin increased when nHAp was used. However, the nHAp/MWCNTO-GO composite exposited lower levels of organic matrix (CH bonds) after erosion compared to other treatments. Interesting, SEM micrographs identified that the nHAp/MWCNTO-GO formed layers after erosive cycling when associate with APF treatment, indicating a possible chemical bond among them. Treatments of root dentin with nHAp, MWCNTO-GO, APF_MWCNTO-GO, and APF_nHAp/MWCNTO-GO increased the carbonate content, carbonate/phosphate ratio, and organic matrix band area after erosion. The potentiodynamic polarization curves and Nyquist plot showed that nHAp, MWCNT-GO and nHAp/MWCNT-GO composites acted as protective agents against corrosion process. Clearly, the nHAp/MWCNTO-GO composite was stable after erosive cycling and a thin and acid-resistant film was formed when associated to APF treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

Structural, Magnetic and Microwave Absorption Properties of Hydrothermally Synthesized (Gd, Mn, Co) Substituted Ba-Hexaferrite Nanoparticles

NASA Astrophysics Data System (ADS)

Torabi, Z.; Arab, A.; Ghanbari, F.

2018-02-01

Gd, Mn and Co substituted barium hexagonal ferrite nanoparticles, according to the formula Ba1- x Gd x Fe12-2 y (MnCo) y O19 and the proportion of y = x/2 (and x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1), have been prepared by hydrothermal method. Structural, magnetic and absorption microwave properties of the compositions were evaluated by x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), vibrating sample magnetometry, and vector network analysis. Studying the XRDs data showed the single-phase structure of all samples without any impurities at 900°C calcination temperature. FE-SEM micrographs demonstrated that the morphology of the nanoparticles has planar and nearly hexagonal morphology. The nanoparticles size calculated within the range of 62-85 nm. Study of the room temperature hysteresis loops of calcined samples indicated that maximum magnetizations and coercivities decreased compared to undoped composite with respect to x. The alterations of magnetizations and coercivities are related to the site occupation of substituted ions, change in grain growth inhibition and the effect of spin canting. Moreover, the results of microwave absorption measurements demonstrated that the maximum reflection loss of substituted Ba-hexaferrite equivalent to - 47 dB in sample x = 0.5 with thickness 5.6 mm at a frequency about 17.2 GHz and a bandwidth of 2 GHz greater than - 10 dB. The results showed that Gd has good potential for use as a rare-earth substitution in permanent magnet hexaferrites and these composites can be employed as absorbers in the gigahertz frequency range.

Effect of fluoride sodium mouthwash solutions on cpTI: evaluation of physicochemical properties.

PubMed

Toniollo, Marcelo Bighetti; Galo, Rodrigo; Macedo, Ana Paula; Rodrigues, Renata Cristina Silveira; Ribeiro, Ricardo Faria; Mattos, Maria da Gloria Chiarello de

2012-01-01

The effects of fluoride, which is present in different oral hygiene products, deserve more investigation because little is known about their impact on the surface of titanium, which is largely used in Implantology. This study evaluated the surface of commercially pure titanium (cpTi) after exposure to different concentrations of sodium fluoride (NaF). The hypothesis tested in this study was that different concentrations of NaF applied at different time intervals can affect the titanium surface in different ways. The treatments resulted in the following groups: GA (control): immersion in distilled water; GB: immersion in 0.05% NaF for 3 min daily; GC: immersion in 0.2% NaF for 3 min daily; GD: immersion in 0.05% NaF for 3 min every 2 weeks; and GE: immersion in 0.2% NaF for 3 min every 2 weeks. The experiment lasted 60 days. Roughness was measured initially and every 15 days subsequently up to 60 days. After 60 days, corrosion analysis and anodic polarization were done. The samples were examined by scanning electron microscopy (SEM). The roughness data were analyzed by ANOVA and there was no significant difference among groups and among time intervals. The corrosion data (i(corr)) were analyzed by the Mann-Whitney test, and significant differences were found between GA and GC, GB and GC, GC and GD, GC and GE. SEM micrographs showed that the titanium surface exposed to NaF presented corrosion that varied with the different concentrations. This study suggests that the use of 0.05% NaF solution on cpTi is safe, whereas the 0.2% NaF solution should be carefully evaluated with regard to its daily use.

Phase Competition Induced Bio-Electrochemical Resistance and Bio-Compatibility Effect in Nanocrystalline Zr x -Cu100-x Thin Films.

PubMed

Badhirappan, Geetha Priyadarshini; Nallasivam, Vignesh; Varadarajan, Madhuri; Leobeemrao, Vasantha Priya; Bose, Sivakumar; Venugopal, Elakkiya; Rajendran, Selvakumar; Angleo, Peter Chrysologue

2018-07-01

Nano-crystalline Zrx-Cu100-x (x = 20-100 at.%) thin films with thickness ranging from 50 to 185 nm were deposited by magnetron co-sputtering with individual Zr and Cu targets. The as-sputtered thin films were characterized by Field Emission Scanning Electron Microscope (FE-SEM), Atomic Force Microscopy (AFM) and Glancing Incidence X-ray Diffraction (GIXRD) for structural and morphological properties. The crystallite size was found to decrease from 57 nm to 37 nm upon increasing the Zr content from 20 to 30 at.% with slight increase in the lattice strain from 0.17 to 0.33%. Further, increase in Zr content to 40 at.% leads to increase in the crystallite size to 57 nm due to stabilization of C10Zr7 phase along with the presence of nanocrystalline Cu-Zr phase. A bimodal distribution of grain size was observed from FE-SEM micrograph was attributed to the highest surface roughness in Zr30Cu70 thin films comprised of Cu10Zr7, Cu9Zr2, Cu-Zr intermetallic phases. In-vitro electrochemical behaviors of nano-crystalline Zrx-Cu100-x thin films in simulated body fluid (SBF) were investigated using potentiodynamic polarization studies. Electrochemical impedance spectroscopy (EIS) data fitting by equivalent electrical circuit fit model suggests that inner bulk layer contributes to high bio-corrosion resistance in Zrx-Cu100-x thin films with increase in Zr content. The results of cyto-compatibility assay suggested that Zr-Cu thin film did not introduce cytotoxicity to osteoblast cells, indicating its suitability as a bio-coating for minimally invasive medical devices.

Investigation of physico-chemical properties and microbial community during poultry manure co-composting process.

PubMed

Farah Nadia, Omar; Xiang, Loo Yu; Lie, Lee Yei; Chairil Anuar, Dzulkornain; Mohd Afandi, Mohammed P; Azhari Baharuddin, Samsu

2015-02-01

Co-composting of poultry manure and rubber wood sawdust was performed with the ratio of 2:1 (V/V) for a period of 60 days. An investigation was carried out to study the extracellular enzymatic activities and structural degradation utilizing Fourier transform infrared spectroscopy (FT-IR), thermogravimetry and differential thermal analysis (TG/DTA) and scanning electron microscopy (SEM). The microbial succession was also determined by using denaturing gel gradient electrophoresis (DGGE). The compost was able to reach its highest temperature of 71°C at day 3 and stabilized between 30 and 40°C for 8 weeks. CMCase, FPase and β-glucosidase acted synergistically in order to degrade the cellulosic substrate. The xylanase activities increased gradually during the composting and reached the peak value of 11.637 U/g on day 35, followed by a sharp decline. Both LiP and MnP activities reached their peak values on day 35 with 0.431 and 0.132 U/g respectively. The FT-IR spectra revealed an increase in aromaticity and a decrease in aliphatic compounds such as carbohydrates as decomposition proceeded. TGA/DTG data exhibited significant changes in weight loss in compost samples, indicating degradation of organic matter. SEM micrographs showed higher amounts of parenchyma exposed on the surface of rubber wood sawdust at day 60, showing significant degradation. DGGE and 16S rDNA analyses showed that Burkholderia sp., Pandoraea sp., and Pseudomonas sp. were present throughout the composting process. Ornithinibacillus sp. and Castellaniella ginsengisoli were only found in the initial stage of the composting, while different strains of Burkholderia sp. also occurred in the later stage of composting. Copyright © 2014. Published by Elsevier B.V.

Evaluation of fracture toughness and mechanical properties of ternary thiol-ene-methacrylate systems as resin matrix for dental restorative composites.

PubMed

Beigi, Saeed; Yeganeh, Hamid; Atai, Mohammad

2013-07-01

Study and evaluation of fracture toughness, flexural and dynamic mechanical properties, and crosslink density of ternary thiol-ene-methacrylate systems and comparison with corresponding conventional methacrylate system were considered in the present study. Urethane tetra allyl ether monomer (UTAE) was synthesized as ene monomer. Different formulations were prepared based on combination of UTAE, BisGMA/TEGDMA and a tetrathiol monomer (PETMP). The photocuring reaction was conducted under visible light using BD/CQ combination as photoinitiator system. Mechanical properties were evaluated via measuring flexural strength, flexural modulus and fracture toughness. Scanning electron microscopy (SEM) was utilized to study the morphology of the fractured specimen's cross section. Viscoelastic properties of the samples were also determined by dynamic mechanical thermal analysis (DMTA). The same study was performed on a conventional methacrylate system. The data were analyzed and compared by ANOVA and Tukey HSD tests (significance level=0.05). The results showed improvement in fracture toughness of the specimens containing thiol-ene moieties. DMTA revealed a lower glass transition temperature and more homogenous structure for thiol-ene containing specimens in comparison to the system containing merely methacrylate monomer. The flexural modulus and flexural strength of the specimens with higher thiol-ene content were lower than the neat methacrylate system. The SEM micrographs of the fractured surface of specimens with higher methacrylate content were smooth and mirror-like (shiny) which represent brittle fracture. The thiol-ene-methacrylate system can be used as resin matrix of dental composites with enhanced fracture toughness in comparison to the methacrylate analogous. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Optimal endothelialisation of a new compliant poly(carbonate-urea)urethane vascular graft with effect of physiological shear stress.

PubMed

Salacinski, H J; Tai, N R; Punshon, G; Giudiceandrea, A; Hamilton, G; Seifalian, A M

2000-10-01

to define the optimal seeding conditions of a new stress free poly(carbonate-urea)urethane (CPU) graft with compliance similar to that of human artery with honeycomb structure engineered during the manufacturing process to enhance adhesion and growth of endothelial cells. (111)Indium-oxine radiolabeled human umbilical vein endothelial cells (HUVEC) were seeded onto CPU grafts at (a) concentrations from 2-24x10(5)cells/cm(2)and (b) incubated for 0.5, 1, 2, 4 and 6 h. Following incubation, graft segments were subjected to three washing/gamma counting procedures and scanning electron microscopy (SEM). Cell viability was measured using a modified Alamar blue(TM)assay. To test physiological retention a pulsatile flow phantom was used to subject optimally seeded (16x10(5), 4 h) CPU grafts to arterial shear stress for 6 h with real time acquisition of scintigraphic images of seeded grafts using a nuclear medicine gamma camera system. the seeding efficiency of 54+/-13% post three washes was achieved using 16x10(5)cells/cm(2). Similarly in SEM micrographs a seeding density of 16x10(5)cells/cm(2)resulted in a confluent monolayer. Seeded CPU segments incubated for 4 h exhibited significantly higher resistance to wash-off than segments incubated for 30 min (p <0.05). Exposure of seeded grafts to pulsatile shear stress resulted in some cell loss with 67+/-3% of cells adherent following 6 h of perfusion with ongoing metabolic activity. Thus, optimal conditions were 16x10(5)cells/cm(2)at 4 h. the optimal seeding conditions have been defined for "tissue-engineered" vascular graft which allow complete endothelialisation and high cell-to-substrate strength that resists hydrodynamic stress. Copyright 2000 Harcourt Publishers Ltd.

Facial synthesis of nanostructured ZnCo2O4 on carbon cloth for supercapacitor application

NASA Astrophysics Data System (ADS)

Patil, Swati J.; Park, Jungsung; Lee, Dong-Weon

2017-12-01

In this work, we have synthesized the ZnCo2O4 electrode by a facial one-step hydrothermal method on a carbon cloth for the supercapacitor application. The structural and phase purity of the prepared electrode material was confirmed by X-ray diffraction (XRD) technique. The surface morphology and elemental stoichiometry were studied using field emission scanning electron microscopy (FE-SEM). The FE-SEM micrograph illustrates that the ZnCo2O4 material is composed of microstrips with a ~0.5 μm width and length in micron uniformly covered the carbon cloth surface. The ZnCo2O4 electrode material further investigated for electrochemical analyses. The cyclic voltammetry results showed that the ZnCo2O4 microstrips electrode exhibited the highest specific capacitance of 1084 F/g at 2 mV/s scan rate. Remarkably, a maximum energy density of 12.5 Wh/kg was attained at a current density of 2 mA/cm2 with the power density of 3.6 kW/kg for the ZnCo2O4 microstrips electrode. Furthermore, the 96.2 % capacitive retention is obtained at a higher scan rate of 100 mV/s after 1000 CV cycles, indicating excellent cycling stability of the ZnCo2O4 microstrips electrode. The frequency-dependent rate capability and an ideal capacitive behaviour of the ZnCo2O4 microstrips electrode were analyzed using impedance analyses; a representing the ion diffusion structure of the material. These results show that the ZnCo2O4 microstrips electrode could be a promising material for supercapacitor application.

Fabrication, characterization, and evaluation of microsponge delivery system for facilitated fungal therapy

PubMed Central

Moin, Afrasim; Deb, Tamal K.; Osmani, Riyaz Ali M.; Bhosale, Rohit R.; Hani, Umme

2016-01-01

Objective: The rationale behind present research vocation was to develop and investigate a novel microsponge based gel as a topical carrier for the prolonged release and cutaneous drug deposition of fluconazole (FLZ); destined for facilitated fungal therapy. Materials and Methods: Microsponges were prepared using quasi-emulsion solvent diffusion method using Eudragit S-100. In the direction of optimization, the effect of formulation variables (drug-polymer ratio and amount of emulsifier) and diverse factors affecting physical characteristics of microsponge were investigated as well. Fabricated microsponges were characterized by differential scanning calorimetry, Fourier transform-infrared, scanning electron microscopy (SEM), particle size analysis, and also evaluated for drug content, encapsulation efficiency, in vitro drug release and in vitro antifungal activity. Results: Compatibility studies results reflected no sign of any chemical interaction between the drug and polymers used. Whereas, varied drug-polymer ratios and emulsifier concentration indicated significant effect on production yield, drug content, encapsulation efficiency, particle size and drug release. Spherical microsponges with a porous surface and 29.327 ± 0.31 μm mean particle size were evident from SEM micrographs. In vitro release outcomes, from microsponge loaded gels depicted that F1 formulation was more efficient to give extended drug release of 85.38% at the end of 8 h, while conventional formulation by releasing 83.17% of drug got exhausted incredibly earlier at the end of 4 h merely. Moreover, microsponge gels demonstrated substantial spreadability and extrudability along with promising antifungal activity. Conclusions: Fabricated microsponges would be impending pharmaceutical topical carriers of FLZ and a leading alternative to conventional therapy for efficient, safe and facilitated eradication of fungal infections. PMID:27057125

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.

SEM analysis of defects and wear on Ni-Ti rotary instruments.

PubMed

Arantes, Werington Borges; da Silva, Celso Monteiro; Lage-Marques, José Luiz; Habitante, Sandramarcia; da Rosa, Luiz Carlos Laureano; de Medeiros, João Marcelo Ferreira

2014-01-01

SEM analysis of endodontic instruments from a Ni-Ti rotary system was assessed, before and after using them, considering their defects and deformations. Twenty Twisted File®, BioRąCe®, Mtwo®, and EndoWave® instruments were micrographed at 190× magnification. The files were washed and micrographed again to view alterations as to the presence or absence of irregular edges, grooves, microcavities, and scraping. Simulated root canal preparations were performed using these instruments. The instruments were cleaned and received a microscopic analysis after being used five times. After analysis tests were tested using Fisher's exact test and Kappa to evaluate the concordance among examiners. There was a statistically significant difference with respect to deformations between Twisted File® and other instruments (p < 0.05). There was no statistically significant difference in strains between the other groups (p > 0.05). All Twisted File® instruments showed the same defects; however damage were lower than those found in BioRace® and Mtwo®. The Endowave® did not show the same defects. In accordance with the data we conclude that the presence of defects was higher in Twisted File® instruments as the instruments and BioRace® Mtwo® brand, the defect rate was smaller and Endowave® instruments had no defects. Regarding the presence of wear after five uses among the groups all instruments showed changes in their cutting blades. © 2014 Wiley Periodicals, Inc.

A Mobile Nanoscience and Electron Microscopy Outreach Program

NASA Astrophysics Data System (ADS)

Coffey, Tonya; Kelley, Kyle

2013-03-01

We have established a mobile nanoscience laboratory outreach program in Western NC that puts scanning electron microscopy (SEM) directly in the hands of K-12 students and the general public. There has been a recent push to develop new active learning materials to educate students at all levels about nanoscience and nanotechnology. Previous projects, such as Bugscope, nanoManipulator, or SPM Live! allowed remote access to advanced microscopies. However, placing SEM directly in schools has not often been possible because the cost and steep learning curve of these technologies were prohibitive, making this project quite novel. We have developed new learning modules for a microscopy outreach experience with a tabletop SEM (Hitachi TM3000). We present here an overview of our outreach and results of the assessment of our program to date.

EVALUATION OF COMPUTER-CONTROLLED SCANNING ELECTRON MICROSCOPY APPLIED TO AN AMBIENT URBAN AEROSOL SAMPLE

EPA Science Inventory

Recent interest in monitoring and speciation of particulate matter has led to increased application of scanning electron microscopy (SEM) coupled with energy-dispersive x-ray analysis (EDX) to individual particle analysis. SEM/EDX provides information on the size, shape, co...

Different effects of a novel CaO-MgO-SiO₂-based multiphase glass-ceramic on cell behaviors of normal and cancer cells in vitro.

PubMed

Zhang, Mengjiao; Chen, Xianchun; Pu, Ximing; Liao, Xiaoming; Huang, Zhongbing; Yin, Guangfu

2014-04-01

The effects in vitro of a novel multiphase glass-ceramic (with nominal composition of 43.19% CaO, 7.68% MgO, and 49.13% SiO2 in weight percent) on cell adhesion, proliferation, differentiation and ultrastructure of human osteosarcoma cell line MG63, mouse fibroblasts L929, and human lung adenocarcinoma epithelial cell line A549 were investigated in this research. Scanning electron microscopy (SEM) micrographs revealed that the surface morphology of this glass-ceramic was beneficial to cell adhesion. The glass-ceramic extracts at certain concentrations could stimulate the proliferation and differentiation of MG63 and L929 cells, whereas inhibit A549 proliferation, which might be resulted from the released Si ions. In addition, when cultured with 0.1mg/mL glass-ceramic powder suspension, the cell ultrastructure of MG63 showed abundant organelles and L929 displayed the phenomena of cellular stress response. While more interestingly, A549 exhibited chromatin condensation, mitochondria swell and RER expansion, which was presumed to be early signs of apoptosis. These results suggest that this novel CaO-MgO-SiO2-based multiphase glass-ceramic has potential for bone regeneration and tissue engineering applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Mango kernel starch-gum composite films: Physical, mechanical and barrier properties.

PubMed

Nawab, Anjum; Alam, Feroz; Haq, Muhammad Abdul; Lutfi, Zubala; Hasnain, Abid

2017-05-01

Composite films were developed by the casting method using mango kernel starch (MKS) and guar and xanthan gums. The concentration of both gums ranged from 0% to 30% (w/w of starch; db). Mechanical properties, oxygen permeability (OP), water vapor permeability (WVP), solubility in water and color parameters of composite films were evaluated. The crystallinity and homogeneity between the starch and gums were also evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The scanning electron micrographs showed homogeneous matrix, with no signs of phase separation between the components. XRD analysis demonstrated diminished crystalline peak. Regardless of gum type the tensile strength (TS) of composite films increased with increasing gum concentration while reverse trend was noted for elongation at break (EAB) which found to be decreased with increasing gum concentration. The addition of both guar and xanthan gums increased solubility and WVP of the composite films. However, the OP was found to be lower than that of the control with both gums. Furthermore, addition of both gums led to changes in transparency and opacity of MKS films. Films containing 10% (w/w) xanthan gum showed lower values for solubility, WVP and OP, while film containing 20% guar gum showed good mechanical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

Novel Organically Modified Core-Shell Clay for Epoxy Composites-"SOBM Filler 1".

PubMed

Iheaturu, Nnamdi Chibuike; Madufor, Innocent Chimezie

2014-01-01

Preparation of a novel organically modified clay from spent oil base drilling mud (SOBM) that could serve as core-shell clay filler for polymers is herein reported. Due to the hydrophilic nature of clay, its compatibility with polymer matrix was made possible through modification of the surface of the core clay sample with 3-aminopropyltriethoxysilane (3-APTES) compound prior to its use. Fourier transform infrared (FT-IR) spectroscopy was used to characterize clay surface modification. Electron dispersive X-ray diffraction (EDX) and scanning electron microscopy (SEM) were used to expose filler chemical composition and morphology, while electrophoresis measurement was used to examine level of filler dispersion. Results show an agglomerated core clay powder after high temperature treatment, while EDX analysis shows that the organically modified clay is composed of chemical inhomogeneities, wherein elemental compositions in weight percent vary from one point to the other in a probe of two points. Micrographs of the 3-APTES coupled SOBM core-shell clay filler clearly show cloudy appearance, while FT-IR indicates 25% and 5% increases in fundamental vibrations band at 1014 cm(-1) and 1435 cm(-1), respectively. Furthermore, 3-APTES coupled core-shell clay was used to prepare epoxy composites and tested for mechanical properties.

Influence of samarium substitution on the structural and magnetic properties of M-type hexagonal ferrites

NASA Astrophysics Data System (ADS)

Yasmin, Nazia; Mirza, Misbah; Muhammad, Safdar; Zahid, Maria; Ahmad, Mukhtar; Awan, M. S.; Muhammad, Altaf

2018-01-01

The M-type hexagonal ferrites with chemical formula SrFe12-xSmxO19 (x = 0, 0.01, 0.02, 0.03) were synthesized via sol-gel method. We studied the effects of substitution of rare earth on the structural and magnetic temperament of M-type hexaferrites. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) strategies are employed for the systematical examination of micrographs and structures of the samples. The magnetic particularities are studied by the use of vibrating sample magnetometery. The M-H loops are used to investigate the hard magnetic behavior of all the samples. The substantial value of coercivity (>1 kOe) for all the samples shows that the particular sample is permanent magnet and reveals the hard magnetic action. It is observed that values of saturation magnetization (Mr) and remanence (Ms) decline with increasing the rare earth ions substitution. This decrease may follow spin canting and the magnetic dilution, which results in dislocation of superexchange interactions. The improvement in Hc may be because of large anisotropy of magnetocrystalline, where ion anisotropy of Fe2+ ion on the 2a site probably overriding in all hexaferrites series. The synthesized composites were useful for applications in magnetic microwave absorbing materials.

Metallurgical Analysis of Cracks Formed on Coal Fired Boiler Tube

NASA Astrophysics Data System (ADS)

Kishor, Rajat; Kyada, Tushal; Goyal, Rajesh K.; Kathayat, T. S.

2015-02-01

Metallurgical failure analysis was carried out for cracks observed on the outer surface of a boiler tube made of ASME SA 210 GR A1 grade steel. The cracks on the surface of the tube were observed after 6 months from the installation in service. A careful visual inspection, chemical analysis, hardness measurement, detailed microstructural analysis using optical and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy were carried out to ascertain the cause for failure. Visual inspection of the failed tube revealed the presence of oxide scales and ash deposits on the surface of the tube exposed to fire. Many cracks extending longitudinally were observed on the surface of the tube. Bulging of the tube was also observed. The results of chemical analysis, hardness values and optical micrographs did not exhibit any abnormality at the region of failure. However, detailed SEM with EDS analysis confirmed the presence of various oxide scales. These scales initiated corrosion at both the inner and outer surfaces of the tube. In addition, excessive hoop stress also developed at the region of failure. It is concluded that the failure of the boiler tube took place owing to the combined effect of the corrosion caused by the oxide scales as well as the excessive hoop stress.

Resistance of nanobacteria isolated from urinary and kidney stones to broad-spectrum antibiotics.

PubMed

Sardarabadi, Hadi; Mashreghi, Mansour; Jamialahmadi, Khadijeh; Dianat, Tahere

2014-08-01

Nanoscopic life forms called Nanobacteria or calcifying nanoparticles (CNP) are unconventional agents. These novel organisms are very small (0.1 to 0.5 microns) and possess unusual properties such as high resistance to heat and routine antimicrobial agents. Nanobacteria are 100 times smaller than bacteria and protected by a shell of apatite, so they could be as candidate for emerging and progress of in vivo pathological calcification. In this study, the inhibitory effect of broad-spectrum antibiotics on growth of these new forms of life has been investigated. Powdered urinary and kidney stones were demineralized with HCl and neutralized with appropriate buffers and became filtered. Finally suspension was incubated in DMEM medium with Fetal Bovine Serum (FBS) and broad-spectrum antibiotics (100U/ml for penicillin and 100μg/ml for streptomycin) for 60 days. In the presence of broad-spectrum antibiotics, Scanning Electron Micrographs (SEM) showed a spherical shape of these nanobacteria. Also, Energy Dispersive X-ray spectroscopy (EDS) showed a pick for calcium and phosphor. Transmission Electron Microscopy (TEM) results illustrated cover around the nanobacteria. The growth of calcifying nanoparticles after adding the broad-spectrum antibiotics may be due to their apatite hard shells supporting them against penetration of the antibiotics.

Novel Organically Modified Core-Shell Clay for Epoxy Composites—“SOBM Filler 1”

PubMed Central

Iheaturu, Nnamdi Chibuike; Madufor, Innocent Chimezie

2014-01-01

Preparation of a novel organically modified clay from spent oil base drilling mud (SOBM) that could serve as core-shell clay filler for polymers is herein reported. Due to the hydrophilic nature of clay, its compatibility with polymer matrix was made possible through modification of the surface of the core clay sample with 3-aminopropyltriethoxysilane (3-APTES) compound prior to its use. Fourier transform infrared (FT-IR) spectroscopy was used to characterize clay surface modification. Electron dispersive X-ray diffraction (EDX) and scanning electron microscopy (SEM) were used to expose filler chemical composition and morphology, while electrophoresis measurement was used to examine level of filler dispersion. Results show an agglomerated core clay powder after high temperature treatment, while EDX analysis shows that the organically modified clay is composed of chemical inhomogeneities, wherein elemental compositions in weight percent vary from one point to the other in a probe of two points. Micrographs of the 3-APTES coupled SOBM core-shell clay filler clearly show cloudy appearance, while FT-IR indicates 25% and 5% increases in fundamental vibrations band at 1014 cm−1 and 1435 cm−1, respectively. Furthermore, 3-APTES coupled core-shell clay was used to prepare epoxy composites and tested for mechanical properties. PMID:27355022

Preliminary study on zinc-air battery using zinc regeneration electrolysis with propanol oxidation as a counter electrode reaction

NASA Astrophysics Data System (ADS)

Wen, Yue-Hua; Cheng, Jie; Ning, Shang-Qi; Yang, Yu-Sheng

A zinc-air battery using zinc regeneration electrolysis with propanol oxidation as a counter electrode reaction is reported in this paper. It possesses functions of both zincate reduction and electrochemical preparation, showing the potential for increasing the electronic energy utilization. Charge/discharge tests and scanning electron microscopy (SEM) micrographs reveal that when a nickel sheet plated with the high-H 2-overpotential metal, cadmium, was used as the negative substrate electrode, the dendritic formation and hydrogen evolution are suppressed effectively, and granular zinc deposits become larger but relatively dense with the increase of charge time. The performance of batteries is favorable even if the charge time is as long as 5 h at the current density of 20 mA cm -2. Better discharge performance is achieved using a 'cavity-opening' configuration for the discharge cell rather than a 'gas-introducing' configuration. The highest energy efficiency is up to 59.2%. That is, the energy consumed by organic electro-synthesis can be recovered by 59.2%. Cyclic voltammograms show that the sintered nickel electrode exhibits a good electro-catalysis activity for the propanol oxidation. The increase of propanol concentration conduces to an enhancement in the organic electro-synthesis efficiency. The organic electro-synthesis current efficiency of 82% can be obtained.

Efficient in situ synthetic routes of polyaniline/poly(vinyl alcohol)/TiO2 nanocomposites using gamma irradiation

NASA Astrophysics Data System (ADS)

Afify, T. A.; Ghazy, O. A.; Saleh, H. H.; Ali, Z. I.

2018-02-01

Gamma radiation was used to prepare nanocomposites based on polyaniline/titanium dioxide (PANI/TiO2) or polyaniline/poly (vinyl alcohol)/titanium dioxide (PANI/PVA/TiO2). It was found that PANI/TiO2 in the form of nanocomposite as shown by the UV/vis spectroscopy. This was through the appearance and shift of two absorption peaks at 340 and 598 nm. The SEM micrographs of the PANI/TiO2 nanocomposites showed a fibrous morphology before the treatment with HCl. The TiO2 nanoparticles are clearly seen to be precipitated on the PANI fibers and the morphology changed towards the sheets shape with highly distribution on PANI surface. The transmission electron microscopy (TEM) image confirms the fibrous shape of the PANI and spherical shape of TiO2 nanoparticles. The XRD study showed a several diffraction patterns of TiO2 nanoparticles confirming the PANI/TiO2 and PANI/PVA/TiO2 nanocomposites. The FT-IR analysis indicated that there is an interfacial interaction existed between the PANI and its inorganic counterpart of TiO2 nanoparticles. The dielectric constant of the PANI/PVA showed the lowest values and was increased by either doping with TiO2 or increasing irradiation dose.

Signal-to-noise ratio estimation on SEM images using cubic spline interpolation with Savitzky-Golay smoothing.

PubMed

Sim, K S; Kiani, M A; Nia, M E; Tso, C P

2014-01-01

A new technique based on cubic spline interpolation with Savitzky-Golay noise reduction filtering is designed to estimate signal-to-noise ratio of scanning electron microscopy (SEM) images. This approach is found to present better result when compared with two existing techniques: nearest neighbourhood and first-order interpolation. When applied to evaluate the quality of SEM images, noise can be eliminated efficiently with optimal choice of scan rate from real-time SEM images, without generating corruption or increasing scanning time. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

Two novel approaches to study arthropod anatomy by using dualbeam FIB/SEM.

PubMed

Di Giulio, Andrea; Muzzi, Maurizio

2018-03-01

Transmission Electron Microscopy (TEM) has always been the conventional method to study arthropod ultrastructure, while the use of Scanning Electron Microscopy (SEM) was mainly devoted to the examination of the external cuticular structures by secondary electrons. The new generation field emission SEMs are capable to generate images at sub-cellular level, comparable to TEM images employing backscattered electrons. The potential of this kind of acquisition becomes very powerful in the dual beam FIB/SEM where the SEM column is combined with a Focused Ion Beam (FIB) column. FIB uses ions as a nano-scalpel to slice samples fixed and embedded in resin, replacing traditional ultramicrotomy. We here present two novel methods, which optimize the use of FIB/SEM for studying arthropod anatomy. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

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.

Microstructural and optical properties of Mn doped NiO nanostructures synthesized via sol-gel method

NASA Astrophysics Data System (ADS)

Shah, Shamim H.; Khan, Wasi; Naseem, Swaleha; Husain, Shahid; Nadeem, M.

2018-04-01

Undoped and Mn(0, 5%, 10% and 15%) doped NiO nanostructures were synthesized by sol-gel method. Structure, morphology and optical properties were investigated through XRD, FTIR, SEM/EDS and UV-visible absorption spectroscopy techniques. XRD data analysis reveals the single phase nature with cubic crystal symmetry of the samples and the average crystallite size decreases with the doping of Mn ions upto 10%. FTIR spectra further confirmed the purity and composition of the synthesized samples. The non-spherical shape of the nanostructures was observed from SEM micrographs and gain size of the nanostructures reduces with Mn doping in NiO, whereas agglomeration increases in doped sample. Optical band gap was estimated using Tauc'srelation and found to increase on incorporation of Mn upto 10% in host lattice and then decreases for further doping.

HRTEMFringeAnalyzer a free python module for an automated analysis of fringe pattern in transmission electron micrographs.

PubMed

Alxneit, Ivo

2018-03-30

A python module (HRTEMFringeAnalyzer) is reported to evaluate the local crystallinity of samples from high-resolution transmission electron microscopy images in a mostly automated fashion. The user only selects the size of a square analyser window and a step size which translates the window in the micrograph. Together they define the resolution of the results obtained. Regions where fringe patterns are visible are identified and their lattice spacing d and direction ϕ as well as the corresponding mean errors σ determined. 1/σd is proportional to the coherence length of the structure, whereas σφ is a measure of how well the direction of the fringes is defined. Maps of these four indicators are computed. The performance of the program is demonstrated on two very different samples: ill-crystalline carbon deposits on a coked Ni/LFNO (reduced LaFe 0.8 Ni 0.2 O3±δ) catalyst and well-crystallized nanoparticles of zinc doped ceria. In the latter case, the automatic segmentation of large aggregates into individual crystalline domains is achieved by ϕ maps. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

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.

A novel cell culture technique for electron microscopy.

PubMed

Wang, F; Ledford, L B; Head, J F; Elliott, R L

1993-12-15

A simplified technique for the monolayer growth of cultured cells and their in situ embedment on the inner surface of the pyramidal portion of the Beem capsule for electron microscopy has been developed. The results demonstrated that the cell monolayers grew well on the surface of the Beem capsule and could be embedded in situ. Electron micrographs showed cells in their natural state of contact with one another. The plasma membrane and intracellular organelles were well preserved. This method minimizes many difficult steps and eliminates the disruption of cells by scraping, pelleting, or enzymatic reaction to remove them.

Effect of lanthanum substitution on structural and magnetic properties of nickel zinc ferrites

NASA Astrophysics Data System (ADS)

Šoka, Martin; Ušáková, Mariana; Dosoudil, Rastislav; Ušák, Elemír; Lokaj, Ján

2018-04-01

The purpose of the presented research is to investigate the effect of La3+ ions substitution for Fe3+ ions in Ni0.42Zn0.58LaxFe2-xO4 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10) ferrite compositions prepared by the innovated glycine-nitrate process based on auto-combustion method. Structural and magnetic properties of examined samples were estimated by the analysis of X-ray spectra, EDAX spectrum, SEM micrographs, thermomagnetic characteristics, magnetic hysteresis loops and complex permeability spectra.

Mechanical Reinforcement of Epoxy Composites with Carbon Fibers and HDPE

NASA Astrophysics Data System (ADS)

He, R.; Chang, Q.; Huang, X.; Li, J.

2018-01-01

Silanized carbon fibers (CFs) and a high-density polyethylene with amino terminal groups (HDPE) were introduced into epoxy resins to fabricate high-performance composites. A. mechanical characterization of the composites was performed to investigate the effect of CFs in cured epoxy/HDPE systems. The composites revealed a noticeable improvement in the tensile strength, elongation at break, flexural strength, and impact strength in comparison with those of neat epoxy and cured epoxy/HDPE systems. SEM micrographs showed that the toughening effect could be explained by yield deformations, phase separation, and microcracking.

Microstructural investigations of 0.2% carbon content steel

NASA Astrophysics Data System (ADS)

Tollabimazraehno, Sajjad; Hingerl, Kurt

2011-10-01

The effect of thermal annealing to get different phases on low carbon steel was investigated. Steel sheets (0.2 wt. % C) of 900 μm thickness were heat treated to produce different structures. All the samples have the same starting point, transformation to coarse austenite at 900 degree Celsius. The nano indentation results revealed that samples have different hadness. By making conventional SEM micrographs, focus ion beam maps, and Electron backscatter diffraction (EBSD) the microstructural development and grain boundary variation of transformed phases martensite, biainte, tempered martensite and different combination of these phases were studied.

Exploring the interior of cuticles and compressions of fossil plants by FIB-SEM milling and image microscopy.

PubMed

Sender, L M; Escapa, I; Benedetti, A; Cúneo, R; Diez, J B

2018-01-01

We present the first study of cuticles and compressions of fossil leaves by Focused Ion Beam Scanning Electron Microscopy (FIB-SEM). Cavities preserved inside fossil leaf compressions corresponding to substomatal chambers have been observed for the first time and several new features were identified in the cross-section cuts. These results open a new way in the investigation of the three-dimensional structures of both micro- and nanostructural features of fossil plants. Moreover, the application of the FIB-SEM technique to both fossils and extant plant remains represent a new source of taxonomical, palaeoenvironmental and palaeoclimatic information. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

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

Data for automated, high-throughput microscopy analysis of intracellular bacterial colonies using spot detection.

PubMed

Ernstsen, Christina L; Login, Frédéric H; Jensen, Helene H; Nørregaard, Rikke; Møller-Jensen, Jakob; Nejsum, Lene N

2017-10-01

Quantification of intracellular bacterial colonies is useful in strategies directed against bacterial attachment, subsequent cellular invasion and intracellular proliferation. An automated, high-throughput microscopy-method was established to quantify the number and size of intracellular bacterial colonies in infected host cells (Detection and quantification of intracellular bacterial colonies by automated, high-throughput microscopy, Ernstsen et al., 2017 [1]). The infected cells were imaged with a 10× objective and number of intracellular bacterial colonies, their size distribution and the number of cell nuclei were automatically quantified using a spot detection-tool. The spot detection-output was exported to Excel, where data analysis was performed. In this article, micrographs and spot detection data are made available to facilitate implementation of the method.

Electron microscopy localization and characterization of functionalized composite organic-inorganic SERS nanoparticles on leukemia cells.

PubMed

Koh, Ai Leen; Shachaf, Catherine M; Elchuri, Sailaja; Nolan, Garry P; Sinclair, Robert

2008-12-01

We demonstrate the use of electron microscopy as a powerful characterization tool to identify and locate antibody-conjugated composite organic-inorganic nanoparticle (COINs) surface enhanced Raman scattering (SERS) nanoparticles on cells. U937 leukemia cells labeled with antibody CD54-conjugated COINs were characterized in their native, hydrated state using wet scanning electron microscopy (SEM) and in their dehydrated state using high-resolution SEM. In both cases, the backscattered electron (BSE) detector was used to detect and identify the silver constituents in COINs due to its high sensitivity to atomic number variations within a specimen. The imaging and analytical capabilities in the SEM were further complemented by higher resolution transmission electron microscopy (TEM) images and scanning Auger electron spectroscopy (AES) data to give reliable and high-resolution information about nanoparticles and their binding to cell surface antigens.

Antibacterial characteristics of thermal plasma spray system.

PubMed

Goudarzi, M; Saviz, Sh; Ghoranneviss, M; Salar Elahi, A

2018-03-15

The objective of this study is to investigate antibacterial characteristics of a thermal plasma spray system. For this purpose, copper powder was coated on a handmade atmospheric plasma spraying system made by the stainless steel 316 substrate, which is preheated at different temperatures before spraying. A number of deposition characteristics such as antibacterial characteristics, adhesion strength and hardness of coating, was investigated. All of the spray parameters are fixed except the substrate temperature. The chemical composition was analyzed by X-ray diffraction (XRD). A scanning electron microscopy (SEM) and back scattering electron microscopy (BSE) were used to show the coating microstructure, its thickness and also the powder micrograph. The energy dispersive X-ray spectroscopy (EDX) was used to analyze the coating particles. Hardness of the deposition was examined by Vickers tester (HV0.1). Its adhesion strength was declared by cross cut tester (TQC). In addition, the percentage of bactericidal coating was evidenced with Staphylococcus aurous and Escherichia coli bacteria. Study results show that as the substrates temperature increases, the number of splats in the shape of pancake increases, the greatness and percentage of the deposition porosity both decrease. The increment of the substrate temperature leads to more oxidation and makes thicker dendrites on the splat. The enhancement of the substrate temperature also enlarges thickness and efficiency of coating. The interesting results are that antibacterial properties of coatings against the Escherichia coli are more than Staphylococcus aurous bacteria. However the bactericidal percentage of the coatings against Staphylococcus aurous and Escherichia coli bacteria roughly does not change with increasing the substrate temperature. Furthermore, by increment of the substrate temperature, coatings with both high adhesion and hardness are obtained. Accordingly, the temperature of substrate can be an important parameter for progressing mechanical properties of the antiseptic deposition.

Loading Mode and Environment Effects on Surface Profile Characteristics of Martensite Plates in Cu-Based SMAs

NASA Astrophysics Data System (ADS)

Suru, Marius-Gabriel; Paraschiv, Adrian-Liviu; Lohan, Nicoleta Monica; Pricop, Bogdan; Ozkal, Burak; Bujoreanu, Leandru-Gheorghe

2014-07-01

The present work reports the influence of the loading mode provided during training under constant stress, in bending, applied to lamellar specimens of Cu-Zn-Al shape memory alloys (SMAs). During training, the specimens were bent by a load fastened at their free end, while being martensitic at room temperature and they lifted the load by one-way effect (1WE), during heating up to austenitic field. On cooling to martensite field, the lower concave surface of bent specimens was compressed, and during heating it was elongated, being subjected to a series of tension-compression cycles, during heating-cooling, respectively. Conversely, the upper convex surface of bent specimens was elongated during cooling and compressed during heating, being subjected to compression-tension cycles. Furthermore, 2WE-trained actuators were tested by means of a hydraulic installation where, this time heating-cooling cycles were performed in oil conditions. Considering that the lower concave surface of the specimens was kept in compressed state, while the upper convex surface was kept in elongated state, the study reveals the influence of the two loading modes and environments on the width of martensite plates of the specimens trained under various numbers of cycles. In this purpose, Cu-Zn-Al specimens, trained under 100-300-500 cycles, were prepared and analyzed by atomic force microscopy (AFM) as well as optical and scanning electron microscopy (OM and SEM, respectively). The analysis also included AFM micrographs corroborated with statistical evaluations in order to reveal the effects of loading mode (tension or compression) in different environmental conditions of the specimens, on the surface profile characteristics of martensite plates, revealed by electropolishing.

Effect of non-magnetic ions substitution on the structure and magnetic properties of Y3-xSrxFe5-xZrxO12 nanoparticles

NASA Astrophysics Data System (ADS)

Mahmoudi, Soulmaz; Gholizadeh, Ahmad

2018-06-01

In this work, Y3-xSrxZrxFe5O12 (0.0 ≤ x ≤ 0.7) were synthesized by citrate precursor method at 1050 °C. The structural and magnetic properties of Y3-xSrxFe5-xZrxO12 were studied by using the X-ray diffraction technique, scanning electron microscopy, transmission electron microscopy, the Fourier transform infrared spectroscopy and vibrating sample magnetometer. XRD analysis using X'Pert package show a pure garnet phase with cubic structure (space group Ia-3d) and the impurity phase SrZrO3 is observed when the range of x value is exceeded from 0.6. Rietveld refinement using Fullprof program shows the lattice volume expansion with increasing the degree of Sr/Zr substitution. The crystallite sizes remain constant in the range of x = 0.0 - 0.5 and then increase. The different morphology observed in SEM micrographs of the samples can be related to different values of the microstrain in the samples. The hysteresis loops of the samples reveal a superparamagnetic behaviour. Also, the drop in coercivity with increasing of the substitution is mainly originated from a reduction in the magneto-elastic anisotropy energy. The values of the saturation magnetization (MS) indicate a non-monotonically variant with increasing the Sr/Zr substitution and reach a maximum 26.14 emu/g for the sample x = 0.1 and a minimum 17.64 emu/g for x = 0.0 and x = 0.2. The variation of MS, in these samples results from a superposition of three factors; reduction of Fe3+ in a-site, change in angle FeT-O-FeO, and magnetic core size.

Platinum and palladium incorporation into phosphate/viologen-phosphonates of zirconium and hafnium: synthesis and characterization

NASA Astrophysics Data System (ADS)

Dokoutchaev, Alexandre; Krishnan, Venkatesan V.; Thompson, Mark E.; Balasubramanian, Mahalingam

1998-10-01

We have continued previous efforts to synthesize and characterize a microporous metal phosphate/viologen-phosphonate compound, [(ZrF) 2(PO 4)(O 3PCH 2CH 2-4,4'-bipyridinium-CH 2CH 2PO 3)] ṡF·2H 2O, ZrPO PV. A derivative of this material has been shown to be an efficient catalyst for the production of hydrogen peroxide from hydrogen and oxygen. This paper has two objectives—one is to optimize the synthetic routes leading to the preparation of MPO PV (M=zirconium or hafnium) and the second is to characterize MPO PV and the derivatives formed by Pt or Pd incorporation by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), inductively coupled plasma-mass spectrometry (ICP-MS) and X-ray absorption fine structure analysis (XAFS). Powder XRD data have shown much higher crystallinity in MPO PV samples prepared by hydrothermal methods than those prepared by reflux methods. In the hydrothermal synthesis, the amount of mineralizer (HF) present controlled the crystallite size (as determined from TEM micrographs). The larger the quantity of HF in the bomb, the larger the size of the crystals but the lower the yield of the MPO PV material. Crystal sizes of about 2.5 μm in length and 0.15 μm in diameter have been made with very large quantities of HF as mineralizer (10 times the required stoichiometric amount). Ion exchange of the material by PdCl 42- has resulted in the incorporation of the PdCl 42- ions in place of X - in the material. This has been confirmed by XAFS studies that demonstrate the oxidation state of Pd is 2+ and show four Cl atoms bound to Pd. Upon reduction it has been confirmed (by XAFS) that the palladium exists as metal with oxidation state of zero. Ion exchange by PdCl 42- and PtCl 42- and subsequent reduction of the material suspension by hydrogen result in the formation of separate Pt and Pd colloids in the close vicinity of the crystallites. TEM micrographs show clearly that the Pt metal obtained after reduction forms much smaller particles in comparison to Pd. These exchanged and reduced materials have also been investigated as catalysts for production of hydrogen peroxide in mixed acetone/water medium. The production of hydrogen peroxide is enhanced by increasing amounts of Pd in the catalyst. Hydrogen peroxide yields are the highest for catalysts containing only Pd as opposed to a mixture of Pt and Pd.

Electron Microscopy of Living Cells During in Situ Fluorescence Microscopy

PubMed Central

Liv, Nalan; van Oosten Slingeland, Daan S. B.; Baudoin, Jean-Pierre; Kruit, Pieter; Piston, David W.; Hoogenboom, Jacob P.

2016-01-01

We present an approach toward dynamic nanoimaging: live fluorescence of cells encapsulated in a bionanoreactor is complemented with in situ scanning electron microscopy (SEM) on an integrated microscope. This allows us to take SEM snapshots on-demand, that is, at a specific location in time, at a desired region of interest, guided by the dynamic fluorescence imaging. We show that this approach enables direct visualization, with EM resolution, of the distribution of bioconjugated quantum dots on cellular extensions during uptake and internalization. PMID:26580231

Does your SEM really tell the truth?--How would you know? Part 1.

PubMed

Postek, Michael T; Vladár, András E

2013-01-01

The scanning electron microscope (SEM) has gone through a tremendous evolution to become a critical tool for many and diverse scientific and industrial applications. The high resolution of the SEM is especially suited for both qualitative and quantitative applications especially for nanotechnology and nanomanufacturing. Quantitatively, measurement, or metrology is one of the main uses. It is likely that one of the first questions asked before even the first scanning electron micrograph was ever recorded was: "… how big is that?" The quality of that answer has improved a great deal over the past few years especially since today these instruments are being used as a primary measurement tool on semiconductor processing lines to monitor the manufacturing processes. The well-articulated needs of semiconductor production prompted a rapid evolution of the instrument and its capabilities. Over the past 20 years or so, instrument manufacturers, through substantial semiconductor industry investment of research and development (R&D) money, have vastly improved the performance of these instruments. All users have benefited from this investment, especially where quantitative measurements with an SEM are concerned. But, how good are these data? This article discusses some of the most important aspects and larger issues associated with imaging and measurements with the SEM that every user should know, and understand before any critical quantitative work is attempted. © Wiley Periodicals, Inc.

Attempt of correlative observation of morphological synaptic connectivity by combining confocal laser-scanning microscope and FIB-SEM for immunohistochemical staining technique.

PubMed

Sonomura, Takahiro; Furuta, Takahiro; Nakatani, Ikuko; Yamamoto, Yo; Honma, Satoru; Kaneko, Takeshi

2014-11-01

Ten years have passed since a serial block-face scanning electron microscopy (SBF-SEM) method was developed [1]. In this innovative method, samples were automatically sectioned with an ultramicrotome placed inside a scanning electron microscope column, and the block surfaces were imaged one after another by SEM to capture back-scattered electrons. The contrast-inverted images obtained by the SBF-SEM were very similar to those acquired using conventional TEM. SFB-SEM has made easy to acquire image stacks of the transmission electron microscopy (TEM) in the mesoscale, which is taken with the confocal laser-scanning microcopy(CF-LSM).Furthermore, serial-section SEM has been combined with the focused ion beam (FIB) milling method [2]. FIB-incorporated SEM (FIB-SEM) has enabled the acquisition of three-dimensional images with a higher z-axis resolution com- pared to ultramicrotome-equipped SEM.We tried immunocytochemistry for FIB-SEM and correlated this immunoreactivity with that in CF-LSM. Dendrites of neurons in the rat neostriatum were visualized using a recombinant viral vector. Moreover, the thalamostriatal afferent terminals were immunolabeled with Cy5 fluorescence for vesicular glutamate transporter 2 (VGluT2). After detection of the sites of terminals apposed to the dendrites by using CF-LSM, GFP and VGluT2 immunoreactivities were further developed for EM by using immunogold/silver enhancement and immunoperoxidase/diaminobenzidine (DAB) methods, respectively.We showed that conventional immuno-cytochemical staining for TEM was applicable to FIB-SEM. Furthermore, several synaptic contacts, which were thought to exist on the basis of CF-LSM findings, were confirmed with FIB-SEM, revealing the usefulness of the combined method of CF-LSM and FIB-SEM. © 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.

Hydrothermal synthesis and magnetic properties of Mn doped ZnS nanoparticles

NASA Astrophysics Data System (ADS)

Rashad, M. M.; Rayan, D. A.; El-Barawy, K.

2010-01-01

Nanocrystallite Mn doped Zn1-XS (X = 0 to 0.4) powders have been synthesized through a hydrothermal route. The effect of the hydrothermal temperature and Mn2+ ions substitution on the crystal structure, crystallite size, microstructure and magnetic properties were investigated using (XRD), (SEM) and (VSM). The results revealed that wurtzite zinc sulfide phase was formed using thiourea as a sulfur source at temperature 150- 200oC for 24 h. The crystallite size was (7.9-15.1 nm) was obtained at the same conditions. The doping of Mn2+ ions decreased the crystallite size of the formed ZnS wurtzite phase was in the range between 7.9 and 3.8 nm. SEM micrographs showed that the produced ZnS and Mn doped ZnS particles were appeared as spherical shape. The magnetic properties were improved by substitution of Mn2+ ions up to 0.2.

[Spectral characteristics of decomposition of incorporated straw in compound polluted arid loess].

PubMed

Fan, Chun-Hui; Zhang, Ying-Chao; Xu, Ji-Ting; Wang, Jia-Hong

2014-04-01

The original loess from western China was used as soil sample, the spectral methods of scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS), elemental analysis, Fourier transform infrared spectroscopy (FT-IR) and 13C nuclear magnetic resonance (13C NMR) were used to investigate the characteristics of decomposed straw and formed humic acids in compound polluted arid loess. The SEM micrographs show the variation from dense to decomposed surface, and finally to damaged structure, and the EDS data reveal the phenomenon of element transfer. The newly-formed humic acids are of low aromaticity, helpful for increasing the activity of organic matters in loess. The FTIR spectra in the whole process are similar, indicating the complexity of transformation dynamics of humic acids. The molecular structure of humic acids becomes simpler, shown from 13C NMR spectra. The spectral methods are useful for humic acids identification in loess region in straw incorporation process.

Examination of Scanning Electron Microscope and Computed Tomography Images of PICA

NASA Technical Reports Server (NTRS)

Lawson, John W.; Stackpoole, Margaret M.; Shklover, Valery

2010-01-01

Micrographs of PICA (Phenolic Impregnated Carbon Ablator) taken using a Scanning Electron Microscope (SEM) and 3D images taken with a Computed Tomography (CT) system are examined. PICA is a carbon fiber based composite (Fiberform ) with a phenolic polymer matrix. The micrographs are taken at different surface depths and at different magnifications in a sample after arc jet testing and show different levels of oxidative removal of the charred matrix (Figs 1 though 13). CT scans, courtesy of Xradia, Inc. of Concord CA, were captured for samples of virgin PICA, charred PICA and raw Fiberform (Fig. 14). We use these images to calculate the thermal conductivity (TC) of these materials using correlation function (CF) methods. CF methods give a mathematical description of how one material is embedded in another and is thus ideally suited for modeling composites like PICA. We will evaluate how the TC of the materials changes as a function of surface depth. This work is in collaboration with ETH-Zurich, which has expertise in high temperature materials and TC modeling (including CF methods).

Study of SEM preparation artefacts with correlative microscopy: Cell shrinkage of adherent cells by HMDS-drying.

PubMed

Katsen-Globa, Alisa; Puetz, Norbert; Gepp, Michael M; Neubauer, Julia C; Zimmermann, Heiko

2016-11-01

One of the often reported artefacts during cell preparation to scanning electron microscopy (SEM) is the shrinkage of cellular objects, that mostly occurs at a certain time-dependent stage of cell drying. Various methods of drying for SEM, such as critical point drying, freeze-drying, as well as hexamethyldisilazane (HMDS)-drying, were usually used. The latter becomes popular since it is a low cost and fast method. However, the correlation of drying duration and real shrinkage of objects was not investigated yet. In this paper, cell shrinkage at each stage of preparation for SEM was studied. We introduce a shrinkage coefficient using correlative light microscopy (LM) and SEM of the same human mesenchymal stem cells (hMSCs). The influence of HMDS-drying duration on the cell shrinkage is shown: the longer drying duration, the more shrinkage is observed. Furthermore, it was demonstrated that cell shrinkage is inversely proportional to cultivation time: the longer cultivation time, the more cell spreading area and the less cell shrinkage. Our results can be applicable for an exact SEM quantification of cell size and determination of cell spreading area in engineering of artificial cellular environments using biomaterials. SCANNING 38:625-633, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

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

A high resolution electron microscopy investigation of curvature in carbon nanotubes

NASA Astrophysics Data System (ADS)

Weldon, D. N.; Blau, W. J.; Zandbergen, H. W.

1995-07-01

Evidence for heptagon inclusion in multi-walled carbon nanotubes was sought in arc-produced carbon deposits. Transmission electron microscopy revealed many curved nanotubes although their relative abundance was low. Close examination of the micrographs in the regions of expected heptagon inclusion shows that the curvature is accomplished by folding or fracture of the lattice planes. This observed phenomenon contradicts the theoretical modelling studies which predict stable structures with negative curvature accomplished by heptagon/pentagon pairs. A possible explanation for curvature in single-walled tubes is presented based on a molecular mechanics geometry optimisation study of spa inclusion in a graphite sheet.

Cellular morphometry of the bronchi of human and dog lungs

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

Robbins, E.S.

1991-09-01

One hundred and forty-seven bronchial samples (generations 3--6) from 66 patients (62 usable; 36 female, 26 male; median age 61) have been dissected by generation from fixed surgical lung specimens obtained after the removal of pathological lesions. In addition, one hundred and fifty-six mongol dog bronchi (generations 2--6) dissected from different lobes of 26 dog lungs have also been similarly prepared. One hundred and twenty-seven human samples have been completely processed for electron microscopy and have yielded 994 electron micrographs of which 655 have been entered into the Computerized Stereological Analysis System (COSAS) and been used for the measurement ofmore » the distances of basal and mucous cell nuclei to the epithelial free surface. Similarly 328 micrographs of dog epithelium from 33 bronchial samples have been used to measure the distances of basal and mucous cell nuclei to the epithelial free surface and have been entered into COSAS. Using the COSAS planimetry program, we continue to expand our established data bases which describe the volume density and nuclear numbers per electron micrograph for 5 cell types of the human bronchial epithelial lining of men and women, as well as smokers, non-smokers and ex-smokers and similar parameters for the same 5 epithelial cell types of dog bronchi. Our micrographs of human bronchial epithelium have allowed us to analyze the recent suggestion that the DNA of lymphocytes may be subject to significant damage from Rn progeny while within the lung. Since the last progress report three papers have been submitted for publication. 17 refs., 4 tabs.« less

Nanoscale Subsurface Imaging of Nanocomposites via Resonant Difference-Frequency Atomic Force Ultrasonic Microscopy

NASA Technical Reports Server (NTRS)

Cantrell, Sean A.; Cantrell, John H.; Lillehei, Peter T.

2007-01-01

A scanning probe microscope methodology, called resonant difference-frequency atomic force ultrasonic microscopy (RDF-AFUM), has been developed. The method employs an ultrasonic wave launched from the bottom of a sample while the cantilever of an atomic force microscope engages the sample top surface. The cantilever is driven at a frequency differing from the ultrasonic frequency by one of the contact resonance frequencies of the cantilever. The nonlinear mixing of the oscillating cantilever and the ultrasonic wave at the sample surface generates difference-frequency oscillations at the cantilever contact resonance. The resonance-enhanced difference-frequency signals are used to create amplitude and phase-generated images of nanoscale near-surface and subsurface features. RDF-AFUM phase images of LaRC-CP2 polyimide polymer containing embedded nanostructures are presented. A RDF-AFUM micrograph of a 12.7 micrometer thick film of LaRC-CP2 containing a monolayer of gold nanoparticles embedded 7 micrometers below the specimen surface reveals the occurrence of contiguous amorphous and crystalline phases within the bulk of the polymer and a preferential growth of the crystalline phase in the vicinity of the gold nanoparticles. A RDF-AFUM micrograph of LaRC-CP2 film containing randomly dispersed carbon nanotubes reveals the growth of an interphase region at certain nanotube-polymer interfaces.

Fabrication Studies of Ternary Rare Earth Sulfides for Infrared Applications.

DTIC Science & Technology

1981-05-01

sulfides. 1 The initial thrust of this investigation has been two-fold. The first objective was to satisfy a need for small , fully dense samples of...0I 60 55.50 45 40 15 30 25 20 28, CuKa Figure 3. X-ray diffraction pattern of CaLa 2S 4fired for 100 hours at 10600C. Small amounts of CaS (and...been increased 9 PBN-81-511 100 urn Figure 4. SEM micrograph of a mixture of La O and CaCO 3 before firing. The small cubes are CaCO The Ia2ോ

Calcinations effect on the grain size distributions Al2O3 powder

NASA Astrophysics Data System (ADS)

Issa, Tarik Talib; Mohammed, Awattif A.; Kamil, Dunia

2012-09-01

Fine of Al2O3 Powder was calcined at 200°C, 400°C, 600°C, and 800°C respectively for 2 hours under static air, x-ray diffraction, optical microscope and grain size distribution were done to analysis the resulting data after calcinations process. Batter particle size was achieved at 800°C of value (0.486) μm, while batter particles mean value of size 7.18 μm was found at 400°C. SEM micrographs shows that the agglomerate particles were vanished due to the calcinations process.

Synthesis of n-type Bi4-xLaxTi3O12 (x=0 to 0.45) by alternative mechanochemical method

NASA Astrophysics Data System (ADS)

Sharanappa, Nagbasavanna

2017-05-01

Lanthanum doped bismuth titanate ceramic samples have been successfully synthesized by mechanochemical method showed good properties and have investigated the structure, microstructure, dielectric, Curie-Weiss behavior, thermoelectric properties, which resulted from substitution of La-ions in bismuth titanate. Plate-like shape with enhanced density is observed in the SEM micrographs. Ceramic samples exhibiting relaxor ferroelectric behavior by satisfying Curie-Weiss law. Thermoelectric studies reveal n-type semiconducting behavior of these samples. Synthesized compounds explored these desirable properties for innovative semiconductor based device applications.

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.

Cellular morphometry of the bronchi of human and dog lungs

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

Robbins, E.S.

1991-03-01

One hundred and thirty-one bronchial samples from 62 patients have been dissected by generation from fixed surgical lung specimens obtained after the removal of pathological lesions. Complete patient records including occupational and smoking histories, as well as possible exposure to radon, are obtained. In addition, one hundred and sixty-two mongol dog bronchi dissected from different lobes of 23 dog lungs have also been similarly prepared. Ninety-four human samples have been completely processed for electron microscopy and have yielded 994 electron micrographs of which 532 have been entered into the Computerized Stereological Analysis System (COSAS) and been used for the measurementmore » of the distances of basal and mucous cell nuclei to the epithelial free surface. Similarly 240 micrographs of dog epithelium from 31 bronchial samples have been entered into COSAS. We have, using the COSAS planimetry program, established data bases which describe the volume density and nuclear numbers per electron micrograph for 5 cell types of the human bronchial epithelial lining of men and women, as well as smokers, non-smokers and ex-smokers and similar parameters for the epithelial cell types of dog bronchi. The data are being used to develop weighting factors for dosimetry and radon risk analysis. 26 refs., 7 figs., 4 tabs.« less

Mosaic construction, processing, and review of very large electron micrograph composites

NASA Astrophysics Data System (ADS)

Vogt, Robert C., III; Trenkle, John M.; Harmon, Laurel A.

1996-11-01

A system of programs is described for acquisition, mosaicking, cueing and interactive review of large-scale transmission electron micrograph composite images. This work was carried out as part of a final-phase clinical analysis study of a drug for the treatment of diabetic peripheral neuropathy. MOre than 500 nerve biopsy samples were prepared, digitally imaged, processed, and reviewed. For a given sample, typically 1000 or more 1.5 megabyte frames were acquired, for a total of between 1 and 2 gigabytes of data per sample. These frames were then automatically registered and mosaicked together into a single virtual image composite, which was subsequently used to perform automatic cueing of axons and axon clusters, as well as review and marking by qualified neuroanatomists. Statistics derived from the review process were used to evaluate the efficacy of the drug in promoting regeneration of myelinated nerve fibers. This effort demonstrates a new, entirely digital capability for doing large-scale electron micrograph studies, in which all of the relevant specimen data can be included at high magnification, as opposed to simply taking a random sample of discrete locations. It opens up the possibility of a new era in electron microscopy--one which broadens the scope of questions that this imaging modality can be used to answer.

An overview of state-of-the-art image restoration in electron microscopy.

PubMed

Roels, J; Aelterman, J; Luong, H Q; Lippens, S; Pižurica, A; Saeys, Y; Philips, W

2018-06-08

In Life Science research, electron microscopy (EM) is an essential tool for morphological analysis at the subcellular level as it allows for visualization at nanometer resolution. However, electron micrographs contain image degradations such as noise and blur caused by electromagnetic interference, electron counting errors, magnetic lens imperfections, electron diffraction, etc. These imperfections in raw image quality are inevitable and hamper subsequent image analysis and visualization. In an effort to mitigate these artefacts, many electron microscopy image restoration algorithms have been proposed in the last years. Most of these methods rely on generic assumptions on the image or degradations and are therefore outperformed by advanced methods that are based on more accurate models. Ideally, a method will accurately model the specific degradations that fit the physical acquisition settings. In this overview paper, we discuss different electron microscopy image degradation solutions and demonstrate that dedicated artefact regularisation results in higher quality restoration and is applicable through recently developed probabilistic methods. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

Annual Research Report 1 October 1978-30 September 1979.

DTIC Science & Technology

1979-01-01

Roeder, R. G. and Rutter, W. J. Multiple acid polymerases in ribonucleic acid synthesis during sea urchin development. Biochemistry 9: 2543-2554...with ultrastructural transmission electron microscopy (TEM) studies and scanning electron microscopy ( SEM ) stud- ies of lateral ventricular lining and...1I alterations in animals about 100 days after Silastic implantation. SEM studies show flattening and stretching of ependymal cells in the dorsomedial

Application of Edible Films Containing Oregano (Origanum vulgare) Essential Oil on Queso Blanco Cheese Prepared with Flaxseed (Linum usitatissimum) Oil.

PubMed

Gurdian, Cristhiam; Chouljenko, Alexander; Solval, Kevin Mis; Boeneke, Charles; King, Joan M; Sathivel, Subramaniam

2017-06-01

Fortification of queso blanco (QB) with flaxseed oil (FO) containing omega-3 polyunsaturated fatty acids may provide a functional food with health benefits such as improved cell, brain, and retina functionality, and protection against cardiovascular and immune-inflammatory diseases. However, QB experiences a short shelf life because of the early development of yeasts and molds and addition of FO may increase susceptibility to lipid oxidation. Oregano essential oil (OEO) is known for its antimicrobial and antioxidant properties, but due to its intense flavor compounds it may not be suitable for direct incorporation into QB. Thus, incorporation of OEO into an edible film prepared with whey protein isolate (WPI) may improve the shelf life of QB. Scanning electron microscopy (SEM) micrographs revealed that FO was successfully retained by the cheese after homogenization. The thiobarbituric-acid-reactive-substances (TBARS) and yeast and mold counts (YMC) of the wrapped cheeses were analyzed during 60 d of refrigerated storage. The oxidation rate increased significantly for nonwrapped QB containing FO (QBFO) during storage, however wrapping with WPI edible films containing OEO (WOF) significantly limited lipid oxidation and prevented growth of yeasts and molds. This study demonstrated the antioxidant and antimicrobial properties of WOF for preservation of QBFO during refrigerated storage. © 2017 Institute of Food Technologists®.

Effect of γ-aminopropyltriethoxy silane (γ-APS) coupling agent on mechanical and morphological properties of high density polyethylene (HDPE)/acrylonitrile butadiene rubber (NBR)/palm pressed fibre (PPF) composites

NASA Astrophysics Data System (ADS)

Norizan, Nabila Najwa; Santiagoo, Ragunathan; Ismail, Hanafi

2017-07-01

The fabrication of High Density Polyethylene (HDPE)/ Acrylonitrile-butadiene rubber (NBR)/ Palm Pressed Fibre (PPF) composite were investigated. The effect of γ-Aminopropyltriethoxy Silane (APS) as coupling agent on the properties of HDPE/ NBR/ PPF composite were studied. The composites were melt mixed using heated two roll mill at 180°C and speed of 15rpm with six different loading (100/0/10, 80/20/10, 70/30/10, 60/40/10, 50/50/10, and 40/60/10). The effects of γ-APS silane on mechanical, and morphological properties were examined using universal tensile machine (UTM) and scanning electron microscopy (SEM), respectively. Tensile strength and Young's modulus of HDPE/ NBR/ PPF composites decrease with increasing of NBR loading, whilst increasing the elongation at break. However, treated composites have resulted 3% to 29%, and 9% to 19%, higher in tensile strength and young's modulus compared to untreated composites. This was due to the better adhesion between HDPE/ NBR matrices and PPF filler with the presence of silanol moieties. From the morphological study, the micrograph of treated composites has proved the well bonded and good attachment of PPF filler with HDPE/ NBR matrices which resulted to better tensile strength to the HDPE/ NBR/ PPF composites.

Controlling the biodegradability of poly(butylene succinate-co-butylene adipate) (PBSA) by solvents used in the dried-gel process

NASA Astrophysics Data System (ADS)

Yamazaki, Hana; Kamitabira, Saya; Maeda, Tomoki; Hotta, Atsushi

Considering an environmentally friendly material, poly(butylene succinate-co-butylene adipate)(PBSA) is one of the attractive biodegradable plastics that can be eventually degraded into H2O and CO2 by neighboring water molecules and microorganisms after the disposal. In order to expand the application of PBSA, the precise control of the biodegradability of PBSA is necessary. In this study, the dried-gel process was introduced to control the biodegradability of PBSA. The dried PBSA gels were prepared by using three different solvents (toluene, cyclohexanone, and o-dichlorobenzene). The scanning electron microscopy (SEM) micrographs revealed that the PBSA prepared by toluene had smaller spherocrystals than the other PBSA dried-gels prepared by cyclohexanone or o-dichlorobenzene. The biodegradability testing by immersing the three types of PBSA in NaOH aq. showed that the percentage of the weight loss of the PBSA produced by toluene was the highest. The results indicated that the microstructures of PBSA could be controlled by changing solvents during the gel preparations, and that the biodegradability of PBSA could therefore be efficiently modified by changing solvents. This work was supported by a Grant-in-Aid for Scientific Research (A) (No. 15H02298 to A.H.) and a Grant-in-Aid for Research Activity Start-up (No.15H06586 to T.M.) from JSPS: KAKENHI\\x9D.

Immobilization of glucose oxidase into a nanoporous TiO₂ film layered on metallophthalocyanine modified vertically-aligned carbon nanotubes for efficient direct electron transfer.

PubMed

Cui, Hui-Fang; Zhang, Kuan; Zhang, Yong-Fang; Sun, Yu-Long; Wang, Jia; Zhang, Wei-De; Luong, John H T

2013-08-15

Glucose oxidase (GOD) was adsorbed into a nanoporous TiO₂ film layered on the surface of an iron phthalocyanine (FePc) vertically-aligned carbon nanotube (CNT) modified electrode. A Nafion film was then dropcast on the electrode's surface to improve operational and storage stabilities of the GOD-based electrode. Scanning electron microscopy (SEM) micrographs revealed the formation of FePc and nanoporous TiO₂ nanoparticles along the sidewall and the tip of CNTs. Cyclic voltammograms of the GOD electrode in neutral PBS exhibited a pair of well-defined redox peaks, attesting the direct electron transfer of GOD (FAD/FADH₂) with the underlying electrode. The potential of glucose electro-oxidation under nitrogen was ∼+0.12 V with an oxidation current density of 65.3 μA cm(-2) at +0.77 V. Voltammetric and amperometric responses were virtually unaffected by oxygen, illustrating an efficient and fast direct electron transfer. The modification of the CNT surface with FePc resulted in a biosensor with remarkable detection sensitivity with an oxygen-independent bioelectrocatalysis. In deaerated PBS, the biosensor displayed average response time of 12 s, linearity from 50 μM to 4 mM, and a detection limit of 30 μM (S/N=3) for glucose. Copyright © 2013 Elsevier B.V. All rights reserved.

Phosphatase mediated bioprecipitation of lead as pyromorphite by Achromobacter xylosoxidans.

PubMed

Sharma, Jaya; Shamim, Kashif; Dubey, Santosh Kumar

2018-07-01

Achromobacter xylosoxidans strain SJ11, tolerating up to 4.0 mM lead nitrate, in a defined minimal medium was isolated from the waste of a battery manufacturing industry, Goa, India. Interestingly, it formed white precipitate on exposure to lead nitrate which was also evident from scanning electron micrograph (SEM). Energy dispersive X-ray spectroscopic analysis revealed the presence of lead (48.5% by weight) along with phosphorus and chlorine in the precipitate. Transmission electron microscopy (TEM) of bacterial cells clearly refuted the possibility of intracellular lead uptake confirming extracellular precipitation as a predominant mechanism of lead resistance in this bacterium. The extracellular precipitate was further identified as pyromorphite [Pb 5 (PO 4 ) 3 Cl] by X-ray diffraction analysis. This was also corroborated by fourier transformed infrared spectroscopy (FTIR) indicating a significant involvement of phosphate groups. Atomic absorption spectroscopic analysis clearly demonstrated that 465.8 mg g -1 lead was precipitated by the bacterial cells. There was remarkable increase of 160% in phosphatase activity suggesting it's important role in lead precipitation. This was further substantiated by significant up-regulation of phosphatase, CheZ using LC-MS/MS. Therefore phosphatase mediated extracellular precipitation of lead as pyromorphite by A. xylosoxidans strain SJ11 clearly demonstrated it's potential in bioremediation of lead contaminated environmental sites. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ziegler-Natta Catalyst Based on MgCl₂/Clay/ID/TiCl₄ for the Synthesis of Spherical Particles of Polypropylene Nanocomposites.

PubMed

Cardoso, Renata da Silva; Oliveira, Jaqueline da Silva; Ramis, Luciana Bortolin; Marques, Maria de Fátima V

2018-07-01

In the present work, we have designed MgCl2/clay/internal donor (ID)/TiCl4 based bisupported Ziegler-Natta catalysts containing varying amounts of organoclay (montmorillonite) in order to synthesize spherical particles of polypropylene/clay nanocomposites (PCN). The organoclay was introduced into the catalyst support formulation and PCN was obtained using the in situ polymerization technique. Decreasing the reaction time, it was possible to obtain nanocomposites with high concentrations of clay (masterbatches). Micrographs of SEM confirmed the spherical morphology of the catalysts. In addition, XRD patterns show that the active sites for polymerization were inserted in the clay galleries. The catalytic performance was evaluated in slurry propylene polymerization using triethylaluminium as cocatalyst and silane as external electron donor at 70 °C, 4 bar, and different reaction times. The PCNs obtained containing different clay amounts were characterized by X-ray diffraction, thermal analyses, transmission electronic microscopy, and extractables in heptane. The results revealed that the synthesized PP/clay particles were also spherical showing that the morphological control is possible even using catalysts containing high amounts of clay. The PCN presented high degradation temperature (459 °C). The XRD peak related to the clay interlamellar distance has shifted to lower angles, and TEM images confirmed the formation of exfoliated/intercalated clay on the PP matrix and absence of microparticles of clay.

Physicochemical and antifungal properties of bio-nanocomposite film based on gelatin-chitin nanoparticles.

PubMed

Sahraee, Samar; Milani, Jafar M; Ghanbarzadeh, Babak; Hamishehkar, Hamed

2017-04-01

The gelatin-based nanocomposite films containing chitin nanoparticles (N-chitin) with concentrations of 0, 3, 5 and 10% were prepared and their physical, thermal and anti-microbial properties were investigated. Scanning electron microscopy (SEM) micrographs showed that N-chitin size distribution was around 60-70nm which dispersed appropriately at low concentration in gelatin matrix. The results showed that incorporation of N-chitin significantly influenced apparent color and transparency of the gelatin films. The reduced water vapor permeability (WVP) and solubility and higher surface hydrophobicity of the nanocomposite films were obtained by enhancing N-chitin concentration in film formulation. The use of N-chitin up to 5% concentration in the gelatin based nanocomposite film led to improved mechanical properties. Also, the results of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) confirmed improved stability of nanocomposite films against melting and degradation at high temperatures in comparison to neat gelatin film. The well compatibility of chitin nanoparticles with gelatin polymer was concluded from Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) plots. Finally, the gelatin based nanocomposite films had anti-fungal properties against Aspergillus niger in the contact surface zone. Increasing the concentration of N-chitin up to 5% enlarged inhibition zone diameter, but the nanocomposite film containing 10% N-chitin showed smaller inhibition zone. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of lattice strain on structural and magnetic properties of Ca substituted barium hexaferrite

NASA Astrophysics Data System (ADS)

Kumar, Sunil; Supriya, Sweety; Pandey, Rabichandra; Pradhan, Lagen Kumar; Singh, Rakesh Kumar; Kar, Manoranjan

2018-07-01

The calcium (Ca2+) substituted M-type barium hexaferrite (Ba1-xCaxFe12O19) for Ca2+ (x = 0.00, 0.025, 0.050, 0.075, 0.100, 0.150, and 0.200) have been synthesized by the citrate sol-gel method. The X-ray diffraction (XRD) patterns with Rietveld refinement reveal the formation of hexagonal crystal structure with P63/mmc space group. The lattice parameters a = b and c decrease, whereas lattice strain found to increase with the increase in Ca concentration in the samples. The analysis of Raman spectra well supports the XRD patterns analysis. The average particle size is obtained from the FE-SEM (Field Emission Scanning Electron Microscopy) micrographs and these are similar to that of crystallite size obtained from the XRD pattern analysis. The saturation magnetization and magnetocrystalline anisotropy have been obtained by employing the "Law of Approach (LA) to Saturation magnetization" technique at room temperature. The saturation magnetization and magnetocrystalline anisotropy constant are maximum for 5% Ca substitution in barium hexaferrite. It could be due to lattice strain mediated magnetism. However, these magnetic properties decrease for more than the 5% Ca substitution in barium hexaferrite. It could be due to decrease of magnetic exchange interaction (Fe-O-Fe) in the sample. A correlation between magnetic interaction and lattice strain has been observed in Ca2+ substituted M-type barium hexaferrite.

Study of Acidithiobacillus ferrooxidans and enzymatic bio-Fenton process-mediated corrosion of copper-nickel alloy.

PubMed

Jadhav, U; Hocheng, H

2016-10-01

This study presents the corrosion behavior of the copper-nickel (Cu-Ni) alloy in the presence of Acidithiobacillus ferrooxidans (A. ferrooxidans) and glucose oxidase (GOx) enzyme. In both the cases ferric ions played an important role in weight loss and thereby to carry out the corrosion of the Cu-Ni alloy. A corrosion rate of 0.6 (±0.008), 2.11 (±0.05), 3.69 (±0.26), 0.7 (±0.006) and 0.08 (±0.002) mm/year was obtained in 72 h using 9K medium with ferrous sulfate, A. ferrooxidans culture supernatant, A. ferrooxidans cells, GOx enzyme and hydrogen peroxide (H2O2) solution respectively. The scanning electron microscopy (SEM) micrographs showed that a variable extent of corrosion was caused by 9K medium with ferrous sulfate, GOx and A. ferrooxidans cells. An arithmetic average surface roughness (Ra) of 174.78 nm was observed for the control work-piece using optical profilometer. The change in Ra was observed with the treatment of the Cu-Ni alloy using various systems. The Ra for 9K medium with ferrous sulfate, GOx and A. ferrooxidans cells was 374.54, 607.32 and 799.48 nm, respectively, after 24 h. These results suggest that A. ferrooxidans cells were responsible for more corrosion of the Cu-Ni alloy than other systems used.

Thermal, mechanical, and physical properties of seaweed/sugar palm fibre reinforced thermoplastic sugar palm Starch/Agar hybrid composites.

PubMed

Jumaidin, Ridhwan; Sapuan, Salit M; Jawaid, Mohammad; Ishak, Mohamad R; Sahari, Japar

2017-04-01

The aim of this research is to investigate the effect of sugar palm fibre (SPF) on the mechanical, thermal and physical properties of seaweed/thermoplastic sugar palm starch agar (TPSA) composites. Hybridized seaweed/SPF filler at weight ratio of 25:75, 50:50 and 75:25 were prepared using TPSA as a matrix. Mechanical, thermal and physical properties of hybrid composites were carried out. Obtained results indicated that hybrid composites display improved tensile and flexural properties accompanied with lower impact resistance. The highest tensile (17.74MPa) and flexural strength (31.24MPa) was obtained from hybrid composite with 50:50 ratio of seaweed/SPF. Good fibre-matrix bonding was evident in the scanning electron microscopy (SEM) micrograph of the hybrid composites' tensile fracture. Fourier transform infrared spectroscopy (FT-IR) analysis showed increase in intermolecular hydrogen bonding following the addition of SPF. Thermal stability of hybrid composites was enhanced, indicated by a higher onset degradation temperature (259°C) for 25:75 seaweed/SPF composites than the individual seaweed composites (253°C). Water absorption, thickness swelling, water solubility, and soil burial tests showed higher water and biodegradation resistance of the hybrid composites. Overall, the hybridization of SPF with seaweed/TPSA composites enhances the properties of the biocomposites for short-life application; that is, disposable tray, plate, etc. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of ex vivo effectiveness of commercial desensitizing dentifrices

PubMed Central

Mockdeci, Hanny; Polonini, Hudson; Granato, Ana-Paula; Raposo, Nádia; Chaves, Maria-das Graças

2017-01-01

Background Dentin hypersensitivity is a short, severe pain with fast onset. Therapy aims to either prevent or decrease neural transmission or physically occlude the dentinal tubules. This study aimed to evaluate the effectiveness of commercial desensitizing dentifrice by means of an ex vivo method. Material and Methods Samples (n=8 lower human premolars for each group) were randomly allocated into: G1- brushing with Colgate®Sensitive Pro-Relief; G2- brushing with Sensodyne®Rapid Relief; G3- brushing with Sensodyne®Repair & Protect; and G4- brushing with Colgate®Maximum Cavity Protection. The test bodies were submitted to simulated toothbrushing and dentifrices were analyzed regarding their hydrodynamic size, polydispersity index (PI) and zeta potential. Specimens were evaluated using: scanning electron microscopy (SEM); spectroscopy energy dispersive X-ray (EDS); and profilometry. A qualitative analysis of the photomicrographs and topographies was performed. Results The dentifrices showed statistical similar physical and chemical characteristics. They also demonstrated obliteration of dentinal tubules when micrographs were observed. Regarding the chemical elements present in the dentin samples, there was a statistically significant difference between the control and experimental surfaces in the four groups. Conclusions Joint data analysis shows that the desensitizing dentifrice showed better results with regards to the obliteration of dentinal tubules compared to positive and negative controls. Key words:Dentin hypersensitivity, dentin desensitizing agents, toothpastes. PMID:28469813

Cytotoxic effect of silver nanoparticles synthesized from Padina tetrastromatica on breast cancer cell line

NASA Astrophysics Data System (ADS)

Gnana Selvi, B. Clara; Madhavan, J.; Santhanam, Amutha

2016-09-01

In recent years researchers were attracted towards marine sources due to the presence of active components in it. Seaweeds were widely used in pharmaceutical research for their known biological activities. The biological synthesis method of silver nanoparticles (AgNPs) using Padina tetrastromatica seaweed extract and their cytotoxicity against breast cancer MCF-7 cells was reported in this study. The synthesized AgNPs using seaweed extract were subjected to x-ray diffraction, UV-visible spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscope, energy dispersive x-ray, zeta potential to elucidate the structural, morphology, size as well as surface potential parameters. An absorption peak at 430 nm in UV-visible spectrum reveals the excitation and surface plasmon resonance of AgNPs. FE-SEM micrographs exhibits the biosynthesized AgNPs, which are pre-dominantly round shaped and the size ranges between 40-50 nm. The zeta potential value of -27.6 mV confirms the stable nature of biosynthesized silver nanoparticles. Furthermore, the biological synthesized Ag NPs exhibited a dose-dependent cytotoxicity against human breast cancer cell (MCF-7) and the inhibitory concentration (IC50) was found for AgNPs against MCF-7 at 24 h incubation. Biological method of synthesizing silver nanoparticles shows a environmental friendly property which helps in effective electrifying usage in many fields.

FIB-SEM tomography in biology.

PubMed

Kizilyaprak, Caroline; Bittermann, Anne Greet; Daraspe, Jean; Humbel, Bruno M

2014-01-01

Three-dimensional information is much easier to understand than a set of two-dimensional images. Therefore a layman is thrilled by the pseudo-3D image taken in a scanning electron microscope (SEM) while, when seeing a transmission electron micrograph, his imagination is challenged. First approaches to gain insight in the third dimension were to make serial microtome sections of a region of interest (ROI) and then building a model of the object. Serial microtome sectioning is a tedious and skill-demanding work and therefore seldom done. In the last two decades with the increase of computer power, sophisticated display options, and the development of new instruments, an SEM with a built-in microtome as well as a focused ion beam scanning electron microscope (FIB-SEM), serial sectioning, and 3D analysis has become far easier and faster.Due to the relief like topology of the microtome trimmed block face of resin-embedded tissue, the ROI can be searched in the secondary electron mode, and at the selected spot, the ROI is prepared with the ion beam for 3D analysis. For FIB-SEM tomography, a thin slice is removed with the ion beam and the newly exposed face is imaged with the electron beam, usually by recording the backscattered electrons. The process, also called "slice and view," is repeated until the desired volume is imaged.As FIB-SEM allows 3D imaging of biological fine structure at high resolution of only small volumes, it is crucial to perform slice and view at carefully selected spots. Finding the region of interest is therefore a prerequisite for meaningful imaging. Thin layer plastification of biofilms offers direct access to the original sample surface and allows the selection of an ROI for site-specific FIB-SEM tomography just by its pronounced topographic features.

Feature evaluation of complex hysteresis smoothing and its practical applications to noisy SEM images.

PubMed

Suzuki, Kazuhiko; Oho, Eisaku

2013-01-01

Quality of a scanning electron microscopy (SEM) image is strongly influenced by noise. This is a fundamental drawback of the SEM instrument. Complex hysteresis smoothing (CHS) has been previously developed for noise removal of SEM images. This noise removal is performed by monitoring and processing properly the amplitude of the SEM signal. As it stands now, CHS may not be so utilized, though it has several advantages for SEM. For example, the resolution of image processed by CHS is basically equal to that of the original image. In order to find wide application of the CHS method in microscopy, the feature of CHS, which has not been so clarified until now is evaluated correctly. As the application of the result obtained by the feature evaluation, cursor width (CW), which is the sole processing parameter of CHS, is determined more properly using standard deviation of noise Nσ. In addition, disadvantage that CHS cannot remove the noise with excessively large amplitude is improved by a certain postprocessing. CHS is successfully applicable to SEM images with various noise amplitudes. © Wiley Periodicals, Inc.

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.

Scanning EM of non-heavy metal stained biosamples: Large-field of view, high contrast and highly efficient immunolabeling

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

Kuipers, Jeroen; Boer, Pascal de; Giepmans, Ben N.G., E-mail: b.n.g.giepmans@umcg.nl

Scanning electron microscopy (SEM) is increasing its application in life sciences for electron density measurements of ultrathin sections. These are traditionally analyzed with transmission electron microscopy (TEM); by most labs, SEM analysis still is associated with surface imaging only. Here we report several advantages of SEM for thin sections over TEM, both for structural inspection, as well as analyzing immuno-targeted labels such as quantum dots (QDs) and gold, where we find that QD-labeling is ten times more efficient than gold-labeling. Furthermore, we find that omitting post-staining with uranyl and lead leads to QDs readily detectable over the ultrastructure, but undermore » these conditions ultrastructural contrast was even almost invisible in TEM examination. Importantly, imaging in SEM with STEM detection leads to both outstanding QDs and ultrastructural contrast. STEM imaging is superior over back-scattered electron imaging of these non-contrasted samples, whereas secondary electron detection cannot be used at all. We conclude that examination of ultrathin sections by SEM, which may be immunolabeled with QDs, will allow rapid and straightforward analysis of large fields with more efficient labeling than can be achieved with immunogold. The large fields of view routinely achieved with SEM, but not with TEM, allows straightforward raw data sharing using virtual microscopy, also known as nanotomy when this concerns EM data in the life sciences. - Highlights: • High resolution and large fields of view via nanotomy or virtual microscopy. • Highly relevant for EM‐datasets where information density is high. • Sample preparation with low contrast good for STEM, not TEM. • Quantum dots now stand out in STEM‐based detection. • 10 Times more efficient labeling with quantum dots compared to gold.« less

3D imaging of cells and tissues by focused ion beam/scanning electron microscopy (FIB/SEM).

PubMed

Drobne, Damjana

2013-01-01

Integration of a scanning electron microscope (SEM) and focused ion beam (FIB) technology into a single FIB/SEM system permits use of the FIB as a nano-scalpel to reveal site-specific subsurface microstructures which can be examined in great detail by SEM. The FIB/SEM technology is widely used in the semiconductor industry and material sciences, and recently its use in the life sciences has been initiated. Samples for FIB/SEM investigation can be either embedded in a plastic matrix, the traditional means of preparation of transmission electron microscopy (TEM) specimens, or simply dried as in samples prepared for SEM imaging. Currently, FIB/SEM is used in the life sciences for (a) preparation by the lift-out technique of lamella for TEM analysis, (b) tomography of samples embedded in a matrix, and (c) in situ site-specific FIB milling and SEM imaging using a wide range of magnifications. Site-specific milling and imaging has attracted wide interest as a technique in structural research of single eukaryotic and prokaryotic cells, small animals, and different animal tissue, but it still remains to be explored more thoroughly. In the past, preparation of samples for site-specific milling and imaging by FIB/SEM has typically adopted the embedding techniques used for TEM samples, and which have been very well described in the literature. Sample preparation protocols for the use of dried samples in FIB/SEM have been less well investigated. The aim of this chapter is to encourage application of FIB/SEM on dried biological samples. A detailed description of conventional dried sample preparation and FIB/SEM investigation of dried biological samples is presented. The important steps are described and illustrated, and direct comparison between embedded and dried samples of same tissues is provided. The ability to discover links between gross morphology of the tissue or organ, surface characteristics of any selected region, and intracellular structural details on the nanometer scale is an appealing application of electron microscopy in the life sciences and merits further exploration.

Does your SEM really tell the truth? How would you know? Part 2.

PubMed

Postek, Michael T; Vladár, András E; Purushotham, Kavuri P

2014-01-01

The scanning electron microscope (SEM) has gone through a tremendous evolution to become indispensable for many and diverse scientific and industrial applications. The improvements have significantly enriched and augmented the overall SEM performance and have made the instrument far easier to operate. But, the ease of operation also might lead, through operator complacency, to poor results. In addition, the user friendliness has seemingly reduced the need for thorough operator training for using these complex instruments. One might then conclude that the SEM is just a very expensive digital camera or another peripheral device for a computer. Hence, a person using the instrument may be lulled into thinking that all of the potential pitfalls have been eliminated and they believe everything they see on the micrograph is always correct. But, this may not be the case. An earlier paper (Part 1), discussed some of the potential issues related to signal generation in the SEM, instrument calibration, electron beam interactions and the need for physics-based modeling to understand the actual image formation mechanisms. All these were summed together in a discussion of how these issues effect measurements made with the instrument. This second paper discusses another major issue confronting the microscopist: electron-beam-induced specimen contamination. Over the years, NIST has done a great deal of research into the issue of sample contamination and its removal and elimination and some of this work is reviewed and discussed here. © 2013 Wiley Periodicals, Inc.

Magnetic resonance investigation of magnetic-labeled baker's yeast cells

NASA Astrophysics Data System (ADS)

Godoy Morais, J. P. M.; Azevedo, R. B.; Silva, L. P.; Lacava, Z. G. M.; Báo, S. N.; Silva, O.; Pelegrini, F.; Gansau, C.; Buske, N.; Safarik, I.; Safarikova, M.; Morais, P. C.

2004-05-01

In this study, the interaction of DMSA-coated magnetite nanoparticles (5 and 10 nm core-size) with Saccharomyces cerevisae was investigated using magnetic resonance (MR) and transmission electron microscopy (TEM). The TEM micrographs revealed magnetite nanoparticles attached externally to the cell wall. The MR data support the strong interaction among the nanoparticles supported by the cells. A remarkable shift in the resonance field was used as signature of particle attachment to the cell wall.

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

Buck, E.C.; Cunnane, J.C.; Brown, N.R.

A combination of optical microscopy, scanning electron microscopy with backscattered electron detection (SEM/BSE), and analytical electron microscopy (AEM) is being used to determine the nature of uranium in soils from the Fernald Environmental Management Project. The information gained from these studies is being used to develop and test remediation technologies. Investigations using SEM have shown that uranium is contained within particles that are typically 1 to 100 {mu}m in diameter. Further analysis with AEM has shown that these uranium-rich regions are made up of discrete uranium-bearing phases. The distribution of these uranium phases was found to be inhomogeneous at themore » microscopic level.« less

Testing and comparison of the coating materials for immunosensors on QCM

NASA Astrophysics Data System (ADS)

Oztuna, Ali; Nazir, Hasan

2012-06-01

In immunoassay based biosensors development studies polymers, as a matrix, and thiol, amine and aldehyde derivative compounds, as a antibody linker, are to be experimented. Aim of this study is to test amine and acetate functional group containing derivatives in liquid phase in order to develop an antibody immobilization strategy for Quartz Crystal Microbalance (QCM) system. In our study, 4-aminothiophenol (4-AT), carboxylated-PVC (PVC-COOH) and aminated- PVC (PVC-NH2) compared with each other as a coating material. Surface of the coated AT-cut gold crystals were characterized with Fourier Transform Infrared spectrometry (FTIR) and Scanning Electron Microscobe (SEM) and tested in a Bacillus anthracis (GenBank: GQ375871) spores immunoassay model system. Subsequently, a series of SEM micrographs were taken again in order to investigate surface morphology and show the presence of the B. anthracis spores on the sensor surface. When experimental results and SEM images were evaluated together, it was suggested that with the synthesis of PVC like open-chained polymers, containing -NH2 and -SH functional groups, B. anthracis spore detection can be accomplished on QCM without requiring complicated immobilization procedures and expensive preliminary preparations.

Helium ion microscopy and energy selective scanning electron microscopy - two advanced microscopy techniques with complementary applications

NASA Astrophysics Data System (ADS)

Rodenburg, C.; Jepson, M. A. E.; Boden, Stuart A.; Bagnall, Darren M.

2014-06-01

Both scanning electron microscopes (SEM) and helium ion microscopes (HeIM) are based on the same principle of a charged particle beam scanning across the surface and generating secondary electrons (SEs) to form images. However, there is a pronounced difference in the energy spectra of the emitted secondary electrons emitted as result of electron or helium ion impact. We have previously presented evidence that this also translates to differences in the information depth through the analysis of dopant contrast in doped silicon structures in both SEM and HeIM. Here, it is now shown how secondary electron emission spectra (SES) and their relation to depth of origin of SE can be experimentally exploited through the use of energy filtering (EF) in low voltage SEM (LV-SEM) to access bulk information from surfaces covered by damage or contamination layers. From the current understanding of the SES in HeIM it is not expected that EF will be as effective in HeIM but an alternative that can be used for some materials to access bulk information is presented.

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

Focused ion beam and field-emission microscopy of metallic filaments in memory devices based on thin films of an ambipolar organic compound consisting of oxadiazole, carbazole, and fluorene units

USGS Publications Warehouse

Pearson, Christopher; Bowen, Leon; Lee, Myung Won; Fisher, Alison L.; Linton, Katherine E.; Bryce, Martin R.; Petty, Michael C.

2013-01-01

We report on the mechanism of operation of organic thin film resistive memory architectures based on an ambipolar compound consisting of oxadiazole, carbazole, and fluorene units. Cross-sections of the devices have been imaged by electron microscopy both before and after applying a voltage. The micrographs reveal the growth of filaments, with diameters of 50 nm–100 nm, on the metal cathode. We suggest that these are formed by the drift of aluminium ions from the anode and are responsible for the observed switching and negative differential resistance phenomena in the memory devices.

Cellular morphometry of the bronchi of human and dog lungs. Progress report, April 1, 1991--October 1, 1991

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

Robbins, E.S.

1991-09-01

One hundred and forty-seven bronchial samples (generations 3--6) from 66 patients (62 usable; 36 female, 26 male; median age 61) have been dissected by generation from fixed surgical lung specimens obtained after the removal of pathological lesions. In addition, one hundred and fifty-six mongol dog bronchi (generations 2--6) dissected from different lobes of 26 dog lungs have also been similarly prepared. One hundred and twenty-seven human samples have been completely processed for electron microscopy and have yielded 994 electron micrographs of which 655 have been entered into the Computerized Stereological Analysis System (COSAS) and been used for the measurement ofmore » the distances of basal and mucous cell nuclei to the epithelial free surface. Similarly 328 micrographs of dog epithelium from 33 bronchial samples have been used to measure the distances of basal and mucous cell nuclei to the epithelial free surface and have been entered into COSAS. Using the COSAS planimetry program, we continue to expand our established data bases which describe the volume density and nuclear numbers per electron micrograph for 5 cell types of the human bronchial epithelial lining of men and women, as well as smokers, non-smokers and ex-smokers and similar parameters for the same 5 epithelial cell types of dog bronchi. Our micrographs of human bronchial epithelium have allowed us to analyze the recent suggestion that the DNA of lymphocytes may be subject to significant damage from Rn progeny while within the lung. Since the last progress report three papers have been submitted for publication. 17 refs., 4 tabs.« less

Method for observation of deembedded sections of fish gonad by scanning electron microscopy

NASA Astrophysics Data System (ADS)

Mao, Lian-Ju

2000-09-01

This article reports a method for examining the intracellular structure of fish gonads using a scanning electron microscope(SEM). The specimen preparation procedure is similar to that for transmission electron microscopy wherein samples cut into semi-thin sections are fixed and embedded in plastic. The embedment matrix was removed by solvents. Risen-free specimens could be observed by SEM. The morphology of matured sperms in the gonad was very clear, and the oocyte internal structures appeared in three-dimensional images. Spheroidal nucleoli and yolk vesicles and several bundles of filaments adhered on the nucleoli could be viewed by SEM for the first time.

[Evaluation of three methods for forensic diatom test].

PubMed

Wang, Yuzhong; Zhao, Jian; Li, Peng; Hu, Sunlin; Wang, Huipin; Wang, Huijun; Liu, Chao

2015-03-01

To compare the efficacy of three methods for forensic diatom test, namely strong acid digestion-centrifuge enrichment-light microscopy (SD-CE-LM), microwave digestion-membrane filtration-automated scanning electron microscopy (MD-ME-SEM), and microwave digestion-membrane filtration-light microscopy (MD-MF-LM). Sixty samples were randomly divided into 3 groups for diatom test using three methods, and the sample preparation time, degree of digestion and recovery rate of diatoms were compared. The sample preparation time was the shortest with MD-MF-LM and the longest with SD-CE-LM (P<0.05). MD-ME-SEM and MD-MF-LM allowed more thorough tissue digestion than SD-CE-LM. MD-ME-SEM resulted in the highest total recovery rate of diatom, followed by MD-MF-LM and then by SD-CE-LM (P<0.05); the recover rate of different diatom species was the highest with MD-ME-SEM, followed by MD-MF-LM and SD-CE-LM (P<0.05). SD-CE-LM has a low recovery rate of diatoms especially for those with lengths shorter than 40 µm or densities less than 1/5. With a high recovery rate and accuracy in diatom test, MD-ME-SEM is suitable for diagnosis of suspected drowning cases. MD-MF-LM is highly efficient, sensitive and convenient for forensic diatom test.

Sub-50 nm metrology on extreme ultra violet chemically amplified resist—A systematic assessment

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

Maas, D. J., E-mail: diederik.maas@tno.nl; Herfst, R.; Veldhoven, E. van

2015-10-15

With lithographic patterning dimensions decreasing well below 50 nm, it is of high importance to understand metrology at such small scales. This paper presents results obtained from dense arrays of contact holes (CHs) with various Critical Dimension (CD) between 15 and 50 nm, as patterned in a chemically amplified resist using an ASML EUV scanner and measured at ASML and TNO. To determine the differences between various (local) CD metrology techniques, we conducted an experiment using optical scatterometry, CD-Scanning Electron Microscopy (CD-SEM), Helium ion Microscopy (HIM), and Atomic Force Microscopy (AFM). CD-SEM requires advanced beam scan strategies to mitigate samplemore » charging; the other tools did not need that. We discuss the observed main similarities and differences between the various techniques. To this end, we assessed the spatial frequency content in the raw images for SEM, HIM, and AFM. HIM and AFM resolve the highest spatial frequencies, which are attributed to the more localized probe-sample interaction for these techniques. Furthermore, the SEM, HIM, and AFM waveforms are analyzed in detail. All techniques show good mutual correlation, albeit the reported CD values systematically differ significantly. HIM systematically reports a 25% higher CD uniformity number than CD-SEM for the same arrays of CHs, probably because HIM has a higher resolution than the CD-SEM used in this assessment. A significant speed boost for HIM and AFM is required before these techniques are to serve the demanding industrial metrology applications like optical critical dimension and CD-SEM do nowadays.« less

Sub-50 nm metrology on extreme ultra violet chemically amplified resist—A systematic assessment

NASA Astrophysics Data System (ADS)

Maas, D. J.; Fliervoet, T.; Herfst, R.; van Veldhoven, E.; Meessen, J.; Vaenkatesan, V.; Sadeghian, H.

2015-10-01

With lithographic patterning dimensions decreasing well below 50 nm, it is of high importance to understand metrology at such small scales. This paper presents results obtained from dense arrays of contact holes (CHs) with various Critical Dimension (CD) between 15 and 50 nm, as patterned in a chemically amplified resist using an ASML EUV scanner and measured at ASML and TNO. To determine the differences between various (local) CD metrology techniques, we conducted an experiment using optical scatterometry, CD-Scanning Electron Microscopy (CD-SEM), Helium ion Microscopy (HIM), and Atomic Force Microscopy (AFM). CD-SEM requires advanced beam scan strategies to mitigate sample charging; the other tools did not need that. We discuss the observed main similarities and differences between the various techniques. To this end, we assessed the spatial frequency content in the raw images for SEM, HIM, and AFM. HIM and AFM resolve the highest spatial frequencies, which are attributed to the more localized probe-sample interaction for these techniques. Furthermore, the SEM, HIM, and AFM waveforms are analyzed in detail. All techniques show good mutual correlation, albeit the reported CD values systematically differ significantly. HIM systematically reports a 25% higher CD uniformity number than CD-SEM for the same arrays of CHs, probably because HIM has a higher resolution than the CD-SEM used in this assessment. A significant speed boost for HIM and AFM is required before these techniques are to serve the demanding industrial metrology applications like optical critical dimension and CD-SEM do nowadays.

Effect of propolis gel on the in vitro reduction of dentin permeability

PubMed Central

SALES-PERES, Silvia Helena de Carvalho; de CARVALHO, Flávia Negreiros; MARSICANO, Juliane Avansini; MATTOS, Maria Cecília; PEREIRA, José Carlos; FORIM, Moacir Rossi; da SILVA, Maria Fatima das Graças Fernandes

2011-01-01

Objective The aim of this study was to evaluate the capacity of potassium oxalate, fluoride gel and two kinds of propolis gel to reduce the hydraulic conductance of dentin, in vitro. Material and Methods The methodology used for the measurement of hydraulic conductance of dentin in the present study was based on a model proposed in literature. Thirty-six 1-mm-thick dentin discs, obtained from extracted human third molars were divided into 4 groups (n=9). The groups corresponded to the following experimental materials: GI-10% propolis gel, pH 4.1; GII-30% propolis gel; GIII-3% potassium oxalate gel, pH 4,1; and GIV-1.23% fluoride gel, pH 4.1, applied to the dentin under the following surface conditions: after 37% phosphoric acid and before 6% citric acid application. The occluding capacity of the dentin tubules was evaluated using scanning electron microscopy (SEM) at ×500, ×1,000 and ×2,000 magnifications. Data were analyzed statistically by two-way ANOVA and Tukey's test at 5% significance level. Results Groups I, II, III, IV did not differ significantly from the others in any conditions by reducing in hydraulic conductance. The active agents reduced dentin permeability; however they produced the smallest reduction in hydraulic conductance when compared to the presence of smear layer (P<0.05). The effectiveness in reducing dentin permeability did not differ significantly from 10% or 30% propolis gels. SEM micrographs revealed that dentin tubules were partially occluded after treatment with propolis. Conclusions Under the conditions of this study, the application of 10% and 30% propolis gels did not seem to reduce the hydraulic conductance of dentin in vitro, but it showed capacity of partially obliterating the dentin tubules. Propolis is used in the treatment of different oral problems without causing significant great collateral effects, and can be a good option in the treatment of patients with dentin sensitivity. PMID:21956588

Spectroscopic study of the inhibition of calcium oxalate calculi by Larrea tridentata

NASA Astrophysics Data System (ADS)

Pinales, Luis Alonso

The causes of urolithiasis include such influences as diet, metabolic disorders, and genetic factors which have been documented as sources that aggravate urinary calculi depositions and aggregations, and, implicitly, as causes of urolithiasis. This study endeavors to detail the scientific mechanisms involved in calcium oxalate calculi formation, and, more importantly, their inhibition under growth conditions imposed by the traditional medicinal approach using the herbal extract, Larrea tridentata. The calculi were synthesized without and with Larrea tridentata infusion by employing the single diffusion gel technique. A visible decrease in calcium oxalate crystal growth with increasing amounts of Larrea tridentata herbal infusion was observed in photomicrographs, as well as a color change from white-transparent for pure crystals to light orange-brown for crystals with inhibitor. Analysis of the samples, which includes Raman, infrared absorption, scanning electron microscopy (SEM), and X-ray powder diffraction (XRD) techniques, demonstrate an overall transition in morphology of the crystals from monohydrate without herbal extract to dihydrate with inhibitor. Furthermore, the resulting data from Raman and infrared absorption support the possibilities of the influences, in this complex process, of NDGA and its derivative compounds from Larrea tridentata, and of the bonding of the magnesium of the inhibitor with the oxalate ion on the surface of the calculi crystals. This assumption corroborates well with the micrographs obtained under higher magnification, which show that the separated small crystallites consist of darker brownish cores, which we attribute to the dominance of growth inhibition by NDGA, surrounded by light transparent thin shells, which possibly correspond to passivation of the crystals by magnesium oxalate. The SEM results reveal the transformation from the dominant monoclinic structure of the calcium oxalate crystals grown alone to the tetragonal dipyramidal crystal structure of the calcium oxalate crystals grown with Larrea tridentata. Comparison between XRD experimental and simulated data, besides corroborating with our previous results, show that each sample is a combination of different structures.

Fabrication and characterization of regenerated cellulose films obtained from oil palm empty fruit bunch

NASA Astrophysics Data System (ADS)

Nor Amalini, A.; Melina Cheah, M. Y.; Wan Rosli, W. D.; Hayati, S.; Mohamad Haafiz, M. K.

2017-12-01

Development of regenerated cellulose (RC) derived from underutilized cellulosic biomass has recently gained attention as potential petroleum-based polymer replacers. The objective of this current work is to evaluate the properties of RC films obtained from oil palm empty fruit bunch microcrystalline cellulose (OPEFB-MCC) through environmental process. The RC films were fabricated by using different amounts of OPEFB-MCC (4, 6 and 8 %) and 1-butyl-3-methylimidazolium chloride (BMIMCl) was used as green OPEFB-MCC dissolving medium. The resultant RC films were then characterized by means of Fourier transform infrared (FTIR) spectroscopy, mechanical, thermal and morphological properties by using tensile test, differential scanning colorimetry (DSC), and scanning electron microscopy (SEM) respectively. Increase in OPEFB-MCC amounts from 4 to 8 % enhanced the tensile strength and elongation at break of RC by 101 and 78 %, respectively, indicating stronger and more flexible films were formed. It is interesting to note that the Tg (101-154 °C) and Tm(130-187 °C) were found shifted to higher temperature with higher proportions of OPEFB-MCC in RC films. Meanwhile, FTIR analysis showed no new peak presented in RC films, suggesting that BMIMCl is a non-derivatizing solvent to OPEFB-MCC. Conspicuous changes in the spectra of RC films compared to OPEFB-MCC at 3200-3600 cm-1, 1430 cm-1, 1162 cm-1, 1111 cm-1, 1020-1040 cm-1 and 896 cm-1 were associated with transformation of cellulose I to cellulose II structure or/and decrease in crystallinity occurred after regeneration process. SEM micrographs of the RC films revealed that higher OPEFB-MCC contents exhibited smoother and more homogeneous surfaces morphology. Overall, OPEFB-MCC exhibited good film forming ability for RC production and may offer potential application in various industries including food packaging, medical goods and electronic devices.

Effect of different nickel precursors on capacitive behavior of electrodeposited NiO thin films

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

Kore, R. M.; Ghadge, T. S.; Ambare, R. C.

2016-04-13

In the present study, the effect of nickel precursors containing different anions like nitrate, chloride and sulphate on the morphology and pseudocapacitance behavior of NiO is investigated. The NiO samples were prepared by using a potentiondynamic electrodeposition technique in the three electrode cell. Cyclic voltammetry technique was exploited for potentiodynamic deposition of the films. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), etc. The XRD reveals the cubic crystal structure for all samples. The SEM micrograph shows nanoflakelike, up grown nanoflakes and honeycomb like nanostructured morphologies for nitrate, chloride and sulphate precursors respectively. The capacitivemore » behavior of these samples was recorded using cyclic voltammetry (CV), charge-discharge and electrochemical impedance spectroscopy (EIS) in 1 M KOH electrolyte. The specific capacitance values of NiO samples obtained using CV for nitrate, chloride and sulphate precursors were 136, 214 and 893 Fg{sup −1} respectively, at the scan rate of 5 mVs{sup −1}. The charge discharge study shows high specific energy for the sample obtained from sulphate (23.98 Whkg{sup −1}) as compared to chloride (9.67 Whkg{sup −1}) and nitrate (4.9 Whkg{sup −1}), whereas samples of cholride (13.9 kWkg{sup −1} and nitrate (10.5 kWkg{sup −1}) shows comparatively more specific power than samples obtained from sulphate (7.6 kWkg{sup −1}). The equivalent series resistance of NiO samples observed from EIS study are 1.34, 1.29 and 1.27 Ω respectively for nitrate, chloride and sulphate precursors. These results emphasizes that the samples obtained from sulphate precursors provides very low impedance through honeycomb like nanostructured morphology which supports good capacitive behavior of NiO.« less

Chromatographic and Spectroscopic Identification and Recognition of Natural Dyes, Uncommon Dyestuff Components, and Mordants: Case Study of a 16th Century Carpet with Chintamani Motifs.

PubMed

Otłowska, Olga; Ślebioda, Marek; Kot-Wasik, Agata; Karczewski, Jakub; Śliwka-Kaszyńska, Magdalena

2018-02-06

A multi-tool analytical practice was used for the characterisation of a 16th century carpet manufactured in Cairo. A mild extraction method with hydrofluoric acid has been evaluated in order to isolate intact flavonoids and their glycosides, anthraquinones, tannins, and indigoids from fibre samples. High-performance liquid chromatography coupled to spectroscopic and mass spectrometric detectors was used for the identification of possible marker compounds with special attention paid to natural dyes present in the historical samples. Weld, young fustic, and soluble redwood dye were identified as the dye sources in yellow thread samples. Based on the developed method, it was possible to establish that red fibres were coloured with lac dye, whereas green fibre shades were obtained with indigo and weld. Tannin-containing plant material in combination with indigo and weld were used to obtain the brown hue of the thread. Hyphenation of high-performance liquid chromatography (HPLC) with quadrupole time-of-flight mass spectrometry (QTOF MS) and triple-quadrupole mass spectrometry (QqQ MS) enabled us to recognise four uncommon and thus-far unknown dye components that were also found in the historical samples. These compounds probably represent a unique fingerprint of dyed threads manufactured in a Turkish workshop. Scanning electron microscopy with energy-dispersive X-ray detector (SEM-EDS) and Fourier transform infrared spectroscopy (FT-IR) were used for the identification and characterisation of substrates and mordants present in the historical carpet. Carbon and oxygen were detected in large quantities as a part of the wool protein. The presence of aluminium, iron, and calcium indicated their usage as mordants. Trace amounts of copper, silica, and magnesium might originate from the contaminants. FT-IR analysis showed bands characteristic for woollen fibres and SEM micrographs defined the structure of the wool.

Electron Microscopy Localization and Characterization of Functionalized Composite Organic-Inorganic SERS Nanoparticles on Leukemia Cells

PubMed Central

Koh, Ai Leen; Shachaf, Catherine M.; Elchuri, Sailaja; Nolan, Garry P.; Sinclair, Robert

2008-01-01

We demonstrate the use of electron microscopy as a powerful characterization tool to identify and locate antibody-conjugated composite organic-inorganic (COINs) surface enhanced Raman scattering (SERS) nanoparticles on cells. U937 leukemia cells labeled with antibody CD54-conjugated COINs were characterized in their native, hydrated state using wet Scanning Electron Microscopy (SEM) and in their dehydrated state using high-resolution SEM. In both cases, the backscattered electron detector (BSE) was used to detect and identify the silver constituents in COINs due to its high sensitivity to atomic number variations within a specimen. The imaging and analytical capabilities in the SEM were further complemented by higher resolution Transmission Electron Microscope (TEM) images and Scanning Auger Electron Spectroscopy (AES) data to give reliable and high-resolution information about nanoparticles and their binding to cell surface antigens. PMID:18995965

Mechanical characterization of TiO{sub 2} nanofibers produced by different electrospinning techniques

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

Vahtrus, Mikk; Šutka, Andris; Institute of Silicate Materials, Riga Technical University, P. Valdena 3/7, Riga LV-1048

2015-02-15

In this work TiO{sub 2} nanofibers produced by needle and needleless electrospinning processes from the same precursor were characterized and compared using Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and in situ SEM nanomechanical testing. Phase composition, morphology, Young's modulus and bending strength values were found. Weibull statistics was used to evaluate and compare uniformity of mechanical properties of nanofibers produced by two different methods. It is shown that both methods yield nanofibers with very similar properties. - Graphical abstract: Display Omitted - Highlights: • TiO{sub 2} nanofibers were produced by needle and needleless electrospinning processes. •more » Structure was studied by Raman spectroscopy and electron microscopy methods. • Mechanical properties were measured using advanced in situ SEM cantilevered beam bending technique. • Both methods yield nanofibers with very similar properties.« less

Microstructure-Sensitive Investigation of Fracture Using Acoustic Emission Coupled With Electron Microscopy

NASA Technical Reports Server (NTRS)

Wisner, Brian; Cabal, Mike; Vanniamparambiland, Prashanth A.; Leser, William; Hochhalter, Jacob; Kontsos, Antonios

2015-01-01

A novel technique using Scanning Electron Microscopy (SEM) in conjunction with Acoustic Emission (AE) monitoring is proposed to investigate microstructure-sensitive fatigue and fracture of metals. The coupling between quasi in situ microscopy with actual in situ nondestructive evaluation falls into the ICME framework and the idea of quantitative data-driven characterization of material behavior. To validate the use of AE monitoring inside the SEM chamber, Aluminum 2024-B sharp notch specimen were tested both inside and outside the microscope using a small scale mechanical testing device. Subsequently, the same type of specimen was tested inside the SEM chamber. Load data were correlated with both AE information and observations of microcracks around grain boundaries as well as secondary cracks, voids, and slip bands. The preliminary results are in excellent agreement with similar findings at the mesoscale. Extensions of the application of this novel technique are discussed.

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.

Fast response of sprayed vanadium pentoxide (V2O5) nanorods towards nitrogen dioxide (NO2) gas detection

NASA Astrophysics Data System (ADS)

Mane, A. A.; Suryawanshi, M. P.; Kim, J. H.; Moholkar, A. V.

2017-05-01

The V2O5 nanorods have been successfully spray deposited at optimized substrate temperature of 400 °C onto the glass substrates using vanadium trichloride (VCl3) solution of different concentrations. The effect of solution concentration on the physicochemical and NO2 gas sensing properties of sprayed V2O5 nanorods is studied at different operating temperatures and gas concentrations. The XRD study reveals the formation of V2O5 having an orthorhombic symmetry. The FE-SEM micrographs show the nanorods-like morphology of V2O5. The AFM micrographs exhibit a well covered granular surface topography. For direct allowed transition, the band gap energy values are found to be decreased from 2.45 eV to 2.42 eV. The nanorods deposited with 30 mM solution concentration shows the maximum response of 24.2% for 100 ppm NO2 gas concentration at an operating temperature of 200 °C with response and recovery times of 13 s and 140 s, respectively. Finally, the chemisorption mechanism of NO2 gas on the V2O5 nanorods is discussed.

Synthesis and fungicidal activity of novel 2,5-disubstituted-1,3,4- thiadiazole derivatives containing 5-phenyl-2-furan

NASA Astrophysics Data System (ADS)

Cui, Zi-Ning; Li, Ya-Sheng; Hu, De-Kun; Tian, Hao; Jiang, Jia-Zhen; Wang, Yuan; Yan, Xiao-Jing

2016-01-01

A series of 2,5-disubstituted-1,3,4-thiadiazoles were synthesized using Lawesson’s reagent by an efficient approach under microwave irradiation in good yields. Their structures were characterized by MS, IR, 1H NMR, 13C NMR, and elemental analysis. Their in vitro and in vivo fungicidal activities revealed that the title compounds exhibited considerable activity against five selected fungi, especially to Phytophthora infestans. In order to illustrate the mechanism of title compounds against P. infestans, scanning electron micrographs (SEM) and transmission electron micrographs (TEM) were applied. The morphological and ultrastructural studies demonstrated that compound I18 led to swelling of hyphae, thickening and proliferating multilayer cell walls, excessive septation and accumulation of dense bodies. The bioassay results indicated compound I18 might act on cell wall biosynthesis, and blocked the nutrition transportation and led to cells senescence and death. Meanwhile, compound I18 had broad fungicidal activity against other twenty different kinds of fungi. These results suggested that title compounds were eligible to be development candidates and compound I18 as a promising lead compound was worthy to be further discovery, especially against P. infestans.

Conductive polymer/reduced graphene oxide/Au nano particles as efficient composite materials in electrochemical supercapacitors

NASA Astrophysics Data System (ADS)

Shabani Shayeh, J.; Ehsani, A.; Ganjali, M. R.; Norouzi, P.; Jaleh, B.

2015-10-01

Polyaniline/reduced graphene oxide/Au nano particles (PANI/rGO/AuNPs) as a hybrid supercapacitor were deposited on a glassy carbon electrode (GCE) by cyclic voltammetry (CV) method as ternary composites and their electrochemical performance was evaluated in acidic medium. Scanning electron micrographs clearly revealed the formation of nanocomposites on the surface of the working electrode. Scanning electron micrographs (SEM) clearly revealed the formation of nanocomposites on the surface of working electrode. Different electrochemical methods including galvanostatic charge-discharge (CD) experiments, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were carried out in order to investigate the applicability of the system as a supercapacitor. Based on the cyclic voltammogram results obtained, PANI/rGO/AuNPs gave higher specific capacitance, power and energy values than PANI at a current density of 1 mA cm-2. Specific capacitance (SC) of PANI and PANI/rGO/AuNPs electrodes calculated using CV method are 190 and 303 F g-1, respectively. The present study introduces new nanocomposite materials for electrochemical redox capacitors with advantages including long life cycle and stability due to synergistic effects of each component.

Study of sintering temperature on the structure of silicon carbide membrane

NASA Astrophysics Data System (ADS)

Sadighzadeh, A.; Mashayekhan, Sh.; Nedaie, B.; Ghorashi, A. H.

2014-09-01

Study of the microstructure of silicon carbide (SiC) membrane as a function of sintering temperature and the percentage amount of additive kaolin is the outcome of the experimental fabrications presented in this paper. The SEM micrographs are used to investigate the impact of above parameters on the porosity of membrane. The experimental results show that the rise in the temperature causes more sintering of powder particles, growing granules, augmentation of the number of pores and consequently increasing the total porosity of membrane. Using XRD analyses, it is found that SiC amorphous phase is highly sensitive to the temperature and its crystallization physically grows with temperature increase.

New, hybrid pectin-based biosorbents

PubMed Central

Jakóbik-Kolon, Agata; Milewski, Andrzej K.; Karoń, Krzysztof; Bok-Badura, Joanna

2016-01-01

ABSTRACT In this work hybrid pectin-based biosorbents with secondary polysaccharide additives (gellan, carob and xanthan gum, ratio to pectin 1:1, 1:1 and 1:3, respectively) were obtained at two temperatures. The presence of these additives in prepared beads was confirmed by Raman spectra. The SEM micrographs show better homogeneity of blends and grater differences between structures of beads with various additives obtained at higher temperature. The sorption capacity of our hybrid biosorbents as well as sole pectin sorbent is rather the same, and equals 0.85 and 0.70 mmol/g for lead and cadmium, respectively, in pH 4–6. PMID:27812233

Synthesis of multiwalled carbon nanotube from different grades of carbon black using arc discharge method

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

Arora, Neha, E-mail: n4neha31@gmail.com; Sharma, N. N.; Director, School of Automobile, Mechanical & Mechatronics, Manipal University,Jaipur,India

2016-04-13

This paper describes the synthesis of nanotube from different grades (Tread * A(non-ASTM), N134,N121,N660 and N330)of carbon black using DC arc discharge method at 40A current for 60sec. Carbon black samples of different grades were procured from industry (Aditya Birla Science and Technology Limited, India). Scanning Electron Micrographs (SEM) of the deposited carbon nanostructures suggests that MWCNTs are formed at 40A and for a minimal exposure time of 60sec.The result formed indicates the N330 grade of carbon black gets converted to MWCNTs (Multiwall Carbon nanotube) as compared to other grades.

Synthesis of optically transparent ceramic of CaF2 doped with Mn and Ce for thermoluminescent dosimetry

NASA Astrophysics Data System (ADS)

Sen, Shashwati; Singh, S. G.; Patra, G. D.; Shinde, S.; Bhattacharya, S.; Gadkari, S. C.

2012-06-01

Nano-particles of CaF2: Mn were synthesized by a co-precipitation method. Optically transparent ceramics were obtained by vacuum hot-pressing at 1000°C under 20 MPa pressure for 2 h. The duration of pressure and dehydration of the initial powder was found important to achieve the transparency. 50% transparency was observed for a polished disc of 1 mm thickness. SEM micrographs revealed the absence of voids in hot pressed samples. These samples were found to be highly sensitive and linear for TLD and can measure doses from mGy to kGy.

Two new species of the genus Paramitraceras Pickard-Cambridge, 1905 (Opiliones: Laniatores: Stygnopsidae) from Chiapas, Mexico.

PubMed

Cruz-López, Jesús A; Francke, Oscar F

2013-01-01

Parainitraceras pickardcanibridgei sp. nov. and Paramitraceras tzotzil sp. nov. from Chiapas, Mexico are described based on specimens previously determined as Paramitraceras granulatum Pickard-Cambridge, 1905 by Goodnight and Goodnight. The male genitalia of the new species and P. granulatum are illustrated with scanning electronic micrographs (SEMs) or drawings derived from them. The importance of the ocular tubercle, cheliceral dentition and sexual dimorphism, pedipalpal armature and male genitalia as taxonomic characters within the genus is discussed as well as differences and similarities between Paramitraceras Pickard-Cambridge, 1905 and its most similar genus, Sbordonia Šilhavý, 1977.

Spray deposited gallium doped tin oxide thinfilm for acetone sensor application

NASA Astrophysics Data System (ADS)

Preethi, M. S.; Bharath, S. P.; Bangera, Kasturi V.

2018-04-01

Undoped and gallium doped (1 at.%, 2 at.% and 3 at.%) tin oxide thin films were prepared using spray pyrolysis technique by optimising the deposition conditions such as precursor concentration, substrate temperature and spraying rate. X-ray diffraction analysis revealed formation of tetragonally structured polycrystalline films. The SEM micrographs of Ga doped films showed microstructures. The electrical resistivity of the doped films was found to be more than that of the undoped films. The Ga-doped tin oxide thin films were characterised for gas sensors. 1 at.% Ga doped thin films were found to be better acetone gas sensor, showed 68% sensitivity at 350°C temperature.

A new species of the genus Ammonicera (Prosobranchia, Omalogyridae) in a coralline algae community from Jeju Island, off the south coast of Korea

NASA Astrophysics Data System (ADS)

Waki, Tsukasa; Rolán, Emilio; Noseworthy, Ronald G.; Kang, Hyun-Sil; Choi, Kwang-Sik

2017-12-01

A species of the genus Ammonicera Vayssière, 1893 collected from coralline algae communities in Jeju Island, South Korea, is described as a new species, A. aurea, for science. Its morphological characters are described and illustrated by SEM micrographs. This new species can be clearly distinguished from other Ammonicera species from the Pacific Ocean by the presence of a spiral cord and about 25 slightly-elevated axial ribs, resulting in about 25 nodules at intersecting points of the cord and ribs on the last whorl of the teleoconch.

Investigation of multiferroic behavior on flakes-like BiFeO{sub 3}

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

Sheikh, Javed R.; Gaikwad, Vishwajit M.; Acharya, Smita A., E-mail: saha275@yahoo.com

2016-05-23

In present work, multiferroic BiFeO{sub 3} was synthesized by hydrothermal route. The rhombohedral structure was confirmed X-ray diffraction pattern and data fitted with Reitveld refinement using Full-Prof software suite. SEM micrograph shows flake like morphology. Frequency and temperature dependence of dielectric constant and dielectric loss were studied and detected enhancement in dielectric constant. The magnetic measurement indicates antiferromagnetic nature of BFO. P-E curve shows ferroelectic hysteresis loop with remanent polarization (2Pr) 0.3518 µC/cm{sup 2}. The dielectric anomaly observed near T{sub N} can be assigned to magnetoelectric coupling which is useful in device application.

Observation of ferromagnetism in Mn doped KNbO3

NASA Astrophysics Data System (ADS)

Manikandan, M.; Venkateswaran, C.

2015-06-01

Pure and Mn doped KNbO3 have been prepared by ball milling assisted ceramic method. Mn ion had been doped at Nb site to induce ferromagnetism at room temperature. X-ray diffraction (XRD) patterns reveal the formation of orthorhombic phase. High resolution scanning electron micrograph (HR-SEM) of both pure and Mn doped samples show a mixture of spherical and plate like particles. Room temperature magnetic behavior of both the samples were analyzed using vibrating sample magnetometer (VSM). 5% Mn doped KNbO3 exhibits ferromagnetic behavior. Observed ferromagnetic feature has been explained by interactions between bound magnetic polarons which are created by Mn4+ ions.

Synthesis and characterization of laminated Si/SiC composites.

PubMed

Naga, Salma M; Kenawy, Sayed H; Awaad, Mohamed; Abd El-Wahab, Hamada S; Greil, Peter; Abadir, Magdi F

2013-01-01

Laminated Si/SiC ceramics were synthesized from porous preforms of biogenous carbon impregnated with Si slurry at a temperature of 1500 °C for 2 h. Due to the capillarity infiltration with Si, both intrinsic micro- and macrostructure in the carbon preform were retained within the final ceramics. The SEM micrographs indicate that the final material exhibits a distinguished laminar structure with successive Si/SiC layers. The produced composites show weight gain of ≈5% after heat treatment in air at 1300 °C for 50 h. The produced bodies could be used as high temperature gas filters as indicated from the permeability results.

Description of larva and puparium of Oplodontha rubrithorax (Diptera: Stratiomyidae) from the Oriental Region.

PubMed

Nerudová, Jana; Kovac, Damir; Tóthová, Andrea

2015-05-01

This is the first description of larva and puparium of Oplodontha rubrithorax (Macquart, 1838) from the Oriental Region. Larvae were found at a hot spring in North Thailand. The morphological features and cuticular structures of the larva are documented by drawings and SEM micrographs and the main characters are compared with the European O. viridula (Fabricius, 1775), the only described larva of this genus. Differences between larvae of both species were only found in pubescence. The characteristic, somewhat dilated and slightly clavate hairs on the dorsal surface of the body segments of O. viridula larva are apparently lacking in the larva of O. rubrithorax.

Applications of emerging transmission electron microscopy technology in PCD research and diagnosis.

PubMed

Shoemark, Amelia

2017-01-01

Primary Ciliary Dyskinesia (PCD) is a heterogeneous genetic condition characterized by dysfunction of motile cilia. Patients suffer from chronic infection and inflammation of the upper and lower respiratory tract. Diagnosis of PCD is confirmed by identification of a hallmark defect of ciliary ultrastructure or by identification of biallelic pathogenic mutations in a known PCD gene. Since the first description of PCD in 1976, assessment of ciliary ultrastructure by transmission electron microscopy (TEM) has been central to diagnosis and research. Electron tomography is a technique whereby a series of transmission electron micrographs are collected at different angles and reconstructed into a single 3D model of a specimen. Electron tomography provides improved spatial information and resolution compared to a single micrograph. Research by electron tomography has revealed new insight into ciliary ultrastructure and consequently ciliary function at a molecular and cellular level. Gene discovery studies in PCD have utilized electron tomography to define the structural consequences of variants in cilia genes. Modern transmission electron microscopes capable of electron tomography are increasingly being installed in clinical laboratories. This presents the possibility for the use of tomography technique in a diagnostic setting. This review describes the electron tomography technique, the contribution tomography has made to the understanding of basic cilia structure and function and finally the potential of the technique for use in PCD diagnosis.

A history of scanning electron microscopy developments: towards "wet-STEM" imaging.

PubMed

Bogner, A; Jouneau, P-H; Thollet, G; Basset, D; Gauthier, C

2007-01-01

A recently developed imaging mode called "wet-STEM" and new developments in environmental scanning electron microscopy (ESEM) allows the observation of nano-objects suspended in a liquid phase, with a few manometers resolution and a good signal to noise ratio. The idea behind this technique is simply to perform STEM-in-SEM, that is SEM in transmission mode, in an environmental SEM. The purpose of the present contribution is to highlight the main advances that contributed to development of the wet-STEM technique. Although simple in principle, the wet-STEM imaging mode would have been limited before high brightness electron sources became available, and needed some progresses and improvements in ESEM. This new technique extends the scope of SEM as a high-resolution microscope, relatively cheap and widely available imaging tool, for a wider variety of samples.

Nail Damage (Severe Onychodystrophy) Induced by Acrylate Glue: Scanning Electron Microscopy and Energy Dispersive X-Ray Investigations

PubMed Central

Pinteala, Tudor; Chiriac, Anca Eduard; Rosca, Irina; Larese Filon, Francesca; Pinteala, Mariana; Chiriac, Anca; Podoleanu, Cristian; Stolnicu, Simona; Coros, Marius Florin; Coroaba, Adina

2017-01-01

Background Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques have been used in various fields of medical research, including different pathologies of the nails; however, no studies have focused on obtaining high-resolution microscopic images and elemental analysis of disorders caused by synthetic nails and acrylic adhesives. Methods Damaged/injured fingernails caused by the use of acrylate glue and synthetic nails were investigated using SEM and EDX methods. Results SEM and EDX proved that synthetic nails, acrylic glue, and nails damaged by contact with acrylate glue have a different morphology and different composition compared to healthy human nails. Conclusions SEM and EDX analysis can give useful information about the aspects of topography (surface sample), morphology (shape and size), hardness or reflectivity, and the elemental composition of nails. PMID:28232921

The effects of kinetic structure and micrograph content on achievement in reading micrographs by college biology students

NASA Astrophysics Data System (ADS)

Johnson, Virginia Abbott; Lockard, J. David

The effects of kinetic structure and micrograph content on student achievement of reading micrograph skills were examined. The purpose of the study was to determine which form of kinetic structure, high or low, and/or micrograph content, unified or varied, was most effective and if there were any interactive effects. Randomly assigned to four treatment groups, 100 introductory college biology students attended three audiovisual presentations and practice sessions on reading light, transmission electron, and scanning electron micrographs. The micrograph skills test, administered at two points in time, assessed knowledge acquisition and retention. The test measured general concept skills and actual reading micrograph skills separately. All significant tests were considered with an = 0.05. High kinetic structure was found to be more effective than low kinetic structure in developing general concepts about micrographs. This finding supports Anderson's kinetic theory research. High kinetic structure instruction does not affect actual reading micrograph skills, but micrograph content does. Unified micrograph content practice sessions were more effective than varied micrograph content practice sessions. More attention should be given to the visual components of perceptual learning tasks.

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

Garcia-Mateo, Carlos, E-mail: cgm@cenim.csic.es

Since the major strengthening mechanisms in nanocrystalline bainitic steels arise from the exceptionally small size of the bainitc ferrite plate, accurate determination of this parameter is fundamental for quantitative relating the microstructure to the mechanical properties. In this work, the thickness of the bainitic ferrite subunits obtained by different bainitic heat treatments was determined in two steels, with carbon contents of 0.3 and 0.7 wt.%, from SEM and TEM micrographs. As these measurements were made on 2D images taken from random sections, the method includes some stereological correction factors to obtain accurate information. Finally, the determined thicknesses of bainitic ferritemore » plates were compared with the crystallite size calculated from the analysis of X-ray diffraction peak broadening. Although in some case the values obtained for crystallite size and plate thickness can be similar, this study confirms that indeed they are two different parameters. - Highlights: •Bainitic microstructure in a nanostructured and sub-micron steel •Bainitic ferrite plate thickness measured by SEM and TEM •Crystallite size determined by X-ray analysis.« less

A comparative study: Effect of plasma on V2O5 nanostructured thin films

NASA Astrophysics Data System (ADS)

Singh, Megha; Kumar, Prabhat; Sharma, Rabindar K.; Reddy, G. B.

2016-05-01

Vanadium pentoxide nanostructured thin films (NSTs) have been studied to analyze the effect of plasma on nanostructures grown and morphology of films deposited using sublimation process. Nanostructured thin films were deposited on glass substrates, one in presence of oxygen plasma and other in oxygen environment (absence of plasma). Films were characterized using XRD, Raman spectroscopy, SEM and HRTEM. XRD studies revealed α-V2O5 films (orthorhombic phase) with good crystallinity. However, film deposited in presence of plasma have higher peak intensities as compared to those deposited in absence of plasma. Raman studies also support these finding following same trends of considerable increase in intensity in case of film deposited in presence of plasma. SEM micrographs makes the difference more visible, as film deposited in plasma have well defined plate like structures whereas other film have not-clearly-defined petal-like structures. HRTEM results show orthorhombic phase with 0.39 nm interplanar spacing, as reported by XRD. Results are hereby in good agreement with each other.

Structural, thermal and electrical characterizations of multiwalled carbon nanotubes and polyaniline composite

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

Singh, Kamal, E-mail: singhkamal204@gmail.com; Garg, Leena; Singh, Jaspal

2016-05-06

The undoped and doped composite of MWNTs (Multiwalled Carbon Nanotubes) with PANI (/Polyaniline) was prepared by chemical oxidative polymerization. The MWNTs/PANI composites have been characterized by using various techniques like Thermogravometric Analysis (TGA), Fourier transform infrared (FT-IR) spectrometer and Field emission scanning electron microscope (FE-SEM) and conductivity measurement by using two probe method. TGA results has shown that thermal stability followed the pattern undoped MWNTs/PANI composite < doped MWNTs/PANI composite. FE-SEM micrographs demonstrated the morphological changes on the surface of MWNTs as a result of composite formation. Fourier transformed infrared (FT-IR) spectra ascertained the formation of the composite. Study ofmore » electrical characteristics demonstrated that the doped MWNTs/PANI composite (1.2 × 10{sup 1} Scm{sup −1}) have better conductivity than the undoped MWNTs/PANI composite (10{sup −4} Scm{sup −1}). These CNTs based polymeric composites are of great importance in developing new nano-scale devices for future chemical, mechanical and electronic applications.« less

Sol-gel synthesis and characterizations of crystalline NaGd(WO4)2 powder for anisotropic transparent ceramic laser application

NASA Astrophysics Data System (ADS)

Durairajan, A.; Thangaraju, D.; Balaji, D.; Moorthy Babu, S.

2013-02-01

NaGd(WO4)2 powders were synthesized at different pH (3.5, 4.5, 5.5, 6.5 and 7.5) values by conventional Pechini method. Sodium and gadolinium nitrate salts and ammonium paratungstate are used as starting precursors. Metal cations were chelated by citric acid and individual citrates were bound together with ethylene glycol. Synthesized gel was analyzed using differential thermal analysis (DTA), thermo gravimetric (TG) and FT-IR spectroscopy to understand the degradation of gel and formation of metal citrates. Calcined powders (250, 600, 700 and 800 °C) were characterized by powder XRD, FT-IR, Raman and FE-SEM analysis. The temperature dependent phase formation was examined by powder XRD. The morphological changes at different pH derived powders were observed with FE-SEM micrographs. Stepwise organic liberation with respect to temperature and presence of carbon content in the pre-fired powder were analyzed using FT-IR analysis. Raman spectrum reveals disordered tungstate vibrations in the NGW matrix.

Electrochemical synthesis of poly(pyrrole-co-o-anisidine)/chitosan composite films

NASA Astrophysics Data System (ADS)

Yalçınkaya, Süleyman; Çakmak, Didem

2017-05-01

In this study, poly(pyrrole-co-o-anisidine)/chitosan composite films were electrochemically synthesized in various monomers feed ratio (pyrrole: o-anisidine; 9:1, 7:3, 1:1, 3:7 and 1:9) of pyrrole and o-anisidine on the platinum electrode. Electrochemical synthesis of the composite films was carried out via cyclic voltammetry technique. They were characterized by FT-IR, cyclic voltammetry, SEM micrographs, digital images, TGA and DSC techniques. The SEM results indicated that the particle size of the composite decreased with increasing o-anisidine ratio and the films became more likely to be smooth morphology. The TGA results proved that the film of the composite with 1:1 ratio showed highest final degradation temperature and lowest weight loss (83%) compared to copolymer and 9:1 1:9 composite films. The 1:1 composite film had higher thermal stability than copolymer and the other composite films (9:1 1:9). Meanwhile, electrochemical studies exhibited that the 1/9 composite film had good electrochemical stability as well.

Peat Water Purification by Hydroxyapatite (HAp) Synthesized from Waste Pensi (Corbicula moltkiana) Shells

NASA Astrophysics Data System (ADS)

Fajri Alif, Matlal; Aprillia, Wandha; Arief, Syukri

2018-01-01

Hydroxyapatite (HAP) were synthesized from Pensi (Corbicula moltkiana) sheels by hydrothermal method and used as adsorbent for peat water purification. Batch adsorption experiments were performed to investigate the effects of various factors such as contact time, adsorbent dosage, and pH. The obtained materials were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM). Results showed that HAP calcined at 900°C (HAP900) and 1000°C (HAP1000) have a poorly crystalline shape. HAP900 also contain Tetracalsium Phosphate (TTCP) with a Ca/P molar ratio 2.18, while HAP 1000 contain HAp with a Ca/P molar ratio 1.67. Optimum condition for peat water purification with HAP900 and HAP1000 were both achieved at 1 hours, 1 grams adsorben mass at pH 2. SEM micrographs show that after purification, the surface of HAP were covered by organic compounds from peat water.

Microwave assisted synthesis and characterization of barium titanate nanoparticles for multi layered ceramic capacitor applications.

PubMed

Thirumalai, Sundararajan; Shanmugavel, Balasivanandha Prabu

2011-01-01

Barium titanate is a common ferroelectric electro-ceramic material having high dielectric constant, with photorefractive effect and piezoelectric properties. In this research work, nano-scale barium titanate powders were synthesized by microwave assisted mechano-chemical route. Suitable precursors were ball milled for 20 hours. TGA studies were performed to study the thermal stability of the powders. The powders were characterized by XRD, SEM and EDX Analysis. Microwave and Conventional heating were performed at 1000 degrees C. The overall heating schedule was reduced by 8 hours in microwave heating thereby reducing the energy and time requirement. The nano-scale, impurity-free and defect-free microstructure was clearly evident from the SEM micrograph and EDX patterns. LCR meter was used to measure the dielectric constant and dielectric loss values at various frequencies. Microwave heated powders showed superior dielectric constant value with low dielectric loss which is highly essential for the fabrication of Multi Layered Ceramic Capacitors.

Tensile experiments and SEM fractography on bovine subchondral bone.

PubMed

Braidotti, P; Bemporad, E; D'Alessio, T; Sciuto, S A; Stagni, L

2000-09-01

Subchondral bone undecalcified samples, extracted from bovine femoral heads, are subjected to a direct tensile load. The Young's modulus of each sample is determined from repeated tests within the elastic limit. In a last test, the tensile load is increased up to the specimen failure, determining the ultimate tensile strength. The investigation is performed on both dry and wet specimens. The measured Young's modulus for dry samples is 10.3+/-2.5GPa, while that of wet samples is 3.5+/-1.2GPa. The ultimate tensile strengths are 36+/-10 and 30+/-7.5MPa for dry and wet specimens, respectively. SEM micrographs of failure surfaces show characteristic lamellar bone structures, with lamellae composed of calcified collagen fibers. Rudimentary osteon-like structures are also observed. Failure surfaces of wet samples show a marked fiber pull-out, while delamination predominates in dry samples. The obtained results are interpreted on the basis of the deformation mechanisms typical of fiber-reinforced laminated composite materials.

Fractality and growth of He bubbles in metals

NASA Astrophysics Data System (ADS)

Kajita, Shin; Ito, Atsushi M.; Ohno, Noriyasu

2017-08-01

Pinholes are formed on surfaces of metals by the exposure to helium plasmas, and they are regarded as the initial process of the growth of fuzzy nanostructures. In this study, number density of the pinholes is investigated in detail from the scanning electron microscope (SEM) micrographs of tungsten and tantalum exposed to the helium plasmas. A power law relation was identified between the number density and the size of pinholes. From the slope and the region where the power law was satisfied, the fractal dimension D and smin, which characterize the SEM images, are deduced. Parametric dependences and material dependence of D and smin are revealed. To explain the fractality, simple Monte-Carlo simulations including random walks of He atoms and absorption on bubble was introduced. It is shown that the initial position of the random walk is one of the key factors to deduce the fractality. The results indicated that new nucleations of bubbles are necessary to reproduce the number-density distribution of bubbles.

Nanosilver microalgae biosynthesis: cell appearance based on SEM and EDX methods

NASA Astrophysics Data System (ADS)

Pancasakti Kusumaningrum, Hermin; Zainuri, Muhammad; Marhaendrajaya, Indras; Subagio, Agus

2018-05-01

Microbial contamination has caused public health problems in the world population. This problem has spurred the development of methods to overcome and prevent microbial invasion. The extensive use of antibiotics has facilitated the continued emergence and spread of resistant organisms. Synthesized of silver nanoparticle (AgNPs) on microalgae Chlorella pyrenoidosa offer environmentally safe antimicrobial agent. The present study is focused on the biosynthesis of AgNPs using microalgae C. pyrenoidosa. The research methods was conducted by insertion of nanosilver particle into microalgae cells with and without agitation to speed up the process of formation nanosilver microalgae. The formation of microalgae SNP was analyzes by UV-Vis spectrophotometer, Scanning Electron Micrograph (SEM) and Energy-dispersive X-ray spectroscopy (EDX) methods. The research result showed that nanosilver microalgae biosynthesis using the agitation treatment was exhibited better performance in particle insertion and cell stability, comparing with no agitation treatment. However, synthesis of nanosilver microalgae tend to reduce the cell size.

Isolation of Mesophyll Cells and Bundle Sheath Cells from Digitaria sanguinalis (L.) Scop. Leaves and a Scanning Microscopy Study of the Internal Leaf Cell Morphology 1

PubMed Central

Edwards, Gerald E.; Black, Clanton C.

1971-01-01

A technique is described for the separation of mesophyll and bundle sheath cells from Digitaria sanguinalis leaves and evidence for separation is given with light and scanning electron micrographs. Gentle grinding of fully differentiated leaves in a mortar releases mesophyll cells which are isolated on nylon nets by filtration. More extensive grinding of the remaining tissue yields bundle sheath strands which are isolated by filtration with stainless steel sieves and nylon nets. Further grinding of bundle sheath strands in a tissue homogenizer releases bundle sheath cells which are collected on nylon nets. Percentage of purity derived from cell counts and yield data on a chlorophyll basis are given. The internal leaf cell morphology is presented in scanning electron micrographs and compared with light micrographs of fully-differentiated D. sanguinalis leaves. In leaves of plants which possess the C4-dicarboxylic acid cycle of photosynthesis, the relationship of leaf morphology to photosynthesis in mesophyll and bundle sheath cells is considered, and the hypothesis is presented that as atmospheric CO2 enters a leaf about 85% is fixed by the C4-dicarboxylic acid cycle in the mesophyll cells and 10 to 15% is fixed by the reductive pentose phosphate cycle in the bundle sheath cells. A technique also is given for the isolation of mesophyll cells from spinach leaves. Images PMID:16657571

Isolation of Mesophyll Cells and Bundle Sheath Cells from Digitaria sanguinalis (L.) Scop. Leaves and a Scanning Microscopy Study of the Internal Leaf Cell Morphology.

PubMed

Edwards, G E; Black, C C

1971-01-01

A technique is described for the separation of mesophyll and bundle sheath cells from Digitaria sanguinalis leaves and evidence for separation is given with light and scanning electron micrographs. Gentle grinding of fully differentiated leaves in a mortar releases mesophyll cells which are isolated on nylon nets by filtration. More extensive grinding of the remaining tissue yields bundle sheath strands which are isolated by filtration with stainless steel sieves and nylon nets. Further grinding of bundle sheath strands in a tissue homogenizer releases bundle sheath cells which are collected on nylon nets. Percentage of purity derived from cell counts and yield data on a chlorophyll basis are given.The internal leaf cell morphology is presented in scanning electron micrographs and compared with light micrographs of fully-differentiated D. sanguinalis leaves. In leaves of plants which possess the C(4)-dicarboxylic acid cycle of photosynthesis, the relationship of leaf morphology to photosynthesis in mesophyll and bundle sheath cells is considered, and the hypothesis is presented that as atmospheric CO(2) enters a leaf about 85% is fixed by the C(4)-dicarboxylic acid cycle in the mesophyll cells and 10 to 15% is fixed by the reductive pentose phosphate cycle in the bundle sheath cells.A technique also is given for the isolation of mesophyll cells from spinach leaves.

Human cardiac telocytes: 3D imaging by FIB-SEM tomography

PubMed Central

Cretoiu, D; Hummel, E; Zimmermann, H; Gherghiceanu, M; Popescu, L M

2014-01-01

Telocyte (TC) is a newly identified type of cell in the cardiac interstitium (www.telocytes.com). TCs are described by classical transmission electron microscopy as cells with very thin and long telopodes (Tps; cellular prolongations) having podoms (dilations) and podomers (very thin segments). TCs’ three-dimensional (3D) morphology is still unknown. Cardiac TCs seem to be particularly involved in long and short distance intercellular signalling and, therefore, their 3D architecture is important for understanding their spatial connections. Using focused ion beam scanning electron microscopy (FIB-SEM) we show, for the first time, the whole ultrastructural anatomy of cardiac TCs. 3D reconstruction of cardiac TCs by FIB-SEM tomography confirms that they have long, narrow but flattened (ribbon-like) telopodes, with humps generated by the podoms. FIB-SEM tomography also confirms the network made by TCs in the cardiac interstitium through adherens junctions. This study provides the first FIB-SEM tomography of a human cell type. PMID:25327290

Scanning Tunneling Microscopy, Atomic Force Microscopy, and Related Techniques.

DTIC Science & Technology

1992-06-15

images of the heaoal ekdprotein monolayer pressed powder samples of pismO claim and sea urchin shells found ~ ~ sx inteotrcelwl fDincoccu radioduran...can be in- Semiconductor Substrates. The atomic structure of sem - vastigated using AFM but has not been as extensively re- iconductor-detal interfaces...from SEM mage (D99). Komaica and p-type Si(00) and p-n junctions formed by implantation of ANALYTICAL CHEMISTRY. VOL 84, NO. 12. JILNE 18. 1992 121R

Three-dimensional imaging of adherent cells using FIB/SEM and STEM.

PubMed

Villinger, Clarissa; Schauflinger, Martin; Gregorius, Heiko; Kranz, Christine; Höhn, Katharina; Nafeey, Soufi; Walther, Paul

2014-01-01

In this chapter we describe three different approaches for three-dimensional imaging of electron microscopic samples: serial sectioning transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) tomography, and focused ion beam/scanning electron microscopy (FIB/SEM) tomography. With these methods, relatively large volumes of resin-embedded biological structures can be analyzed at resolutions of a few nm within a reasonable expenditure of time. The traditional method is serial sectioning and imaging the same area in all sections. Another method is TEM tomography that involves tilting a section in the electron beam and then reconstruction of the volume by back projection of the images. When the scanning transmission (STEM) mode is used, thicker sections (up to 1 μm) can be analyzed. The third approach presented here is focused ion beam/scanning electron microscopy (FIB/SEM) tomography, in which a sample is repeatedly milled with a focused ion beam (FIB) and each newly produced block face is imaged with the scanning electron microscope (SEM). This process can be repeated ad libitum in arbitrary small increments allowing 3D analysis of relatively large volumes such as eukaryotic cells. We show that resolution of this approach is considerably improved when the secondary electron signal is used. However, the most important prerequisite for three-dimensional imaging is good specimen preparation. For all three imaging methods, cryo-fixed (high-pressure frozen) and freeze-substituted samples have been used.

Scanning electron microscopy fractography analysis of fractured hollow implants.

PubMed

Sbordone, Ludovico; Traini, Tonino; Caputi, Sergio; Scarano, Antonio; Bortolaia, Claudia; Piattelli, Adriano

2010-01-01

Fracture of the implant is one of the possible complications affecting dental implants; it is a rare event but of great clinical relevance. The aim of the present study was to perform a scanning electron microscopy (SEM) fractography evaluation of 7 International Team for oral Implantology (ITI) hollow implants removed because of fracture. The most common clinical risk factors, such as malocclusion, bruxism, and cantilevers on the prosthesis, were absent. Seven fractured ITI hollow implants were retrieved from 5 patients and were analyzed with the use of SEM. SEM analysis showed typical signs of a cleavage-type fracture. Fractures could be due to an association of multiple factors such as fatigue, inner defects, material electrochemical problems, and tensocorrosion.

New advances in scanning microscopy and its application to study parasitic protozoa.

PubMed

de Souza, Wanderley; Attias, Marcia

2018-07-01

Scanning electron microscopy has been used to observe and study parasitic protozoa for at least 40 years. However, field emission electron sources, as well as improvements in lenses and detectors, brought the resolution power of scanning electron microscopes (SEM) to a new level. Parallel to the refinement of instruments, protocols for preservation of the ultrastructure, immunolabeling, exposure of cytoskeleton and inner structures of parasites and host cells were developed. This review is focused on protozoan parasites of medical and veterinary relevance, e.g., Toxoplasma gondii, Tritrichomonas foetus, Giardia intestinalis, and Trypanosoma cruzi, compilating the main achievements in describing the fine ultrastructure of their surface, cytoskeleton and interaction with host cells. Two new resources, namely, Helium Ion Microscopy (HIM) and Slice and View, using either Focused Ion Beam (FIB) abrasion or Microtome Serial Sectioning (MSS) within the microscope chamber, combined to backscattered electron imaging of fixed (chemically or by quick freezing followed by freeze substitution and resin embedded samples is bringing an exponential amount of valuable information. In HIM there is no need of conductive coating and the depth of field is much higher than in any field emission SEM. As for FIB- and MSS-SEM, high resolution 3-D models of areas and volumes larger than any other technique allows can be obtained. The main results achieved with all these technological tools and some protocols for sample preparation are included in this review. In addition, we included some results obtained with environmental/low vacuum scanning microscopy and cryo-scanning electron microscopy, both promising, but not yet largely employed SEM modalities. Copyright © 2018. Published by Elsevier Inc.

A SIMPLE FREEZE-FRACTURE REPLICATION METHOD FOR ELECTRON MICROSCOPY

PubMed Central

Bullivant, Stanley; Ames, Adelbert

1966-01-01

A simple method to achieve results similar to the freeze-etching technique of Moor et al. (1961) is described. The frozen tissue is cut under liquid nitrogen with a razor blade outside the evaporator rather than inside with a cooled microtome. The conditions of the experiment do not favor sublimation, and it is proposed that the structure of the replica be explained by local faults in the cleavage plane which leaves structures, such as membranes, standing above the ice. Micrographs of replicas of glycerol-protected frozen small intestine of mouse prepared by the method are presented and the structural details they show are discussed. The problem of vapor-deposited contamination is discussed. It is concluded that this is a practical method for obtaining electron micrographs that are relatively free of artifact, and that further improvements may be expected from the use of rapidly frozen fresh tissue and a clean vacuum system, possibly of the ion-pumped type. PMID:5962938

High-Resolution Microscopy-Coil MR Imaging of Skin Tumors: Techniques and Novel Clinical Applications.

PubMed

Budak, Matthew J; Weir-McCall, Jonathan R; Yeap, Phey M; White, Richard D; Waugh, Shelley A; Sudarshan, Thiru A P; Zealley, Ian A

2015-01-01

High-resolution magnetic resonance (MR) imaging performed with a microscopy coil is a robust radiologic tool for the evaluation of skin lesions. Microscopy-coil MR imaging uses a small surface coil and a 1.5-T or higher MR imaging system. Simple T1- and T2-weighted imaging protocols can be implemented to yield high-quality, high-spatial-resolution images that provide an excellent depiction of dermal anatomy. The primary application of microscopy-coil MR imaging is to delineate the deep margins of skin tumors, thereby providing a preoperative road map for dermatologic surgeons. This information is particularly useful for surgeons who perform Mohs micrographic surgery and in cases of nasofacial neoplasms, where the underlying anatomy is complex. Basal cell carcinoma is the most common nonmelanocytic skin tumor and has a predilection to manifest on the face, where it can be challenging to achieve complete surgical excision while preserving the cosmetic dignity of the patient. Microscopy-coil MR imaging provides dermatologic surgeons with valuable preoperative anatomic information that is not available at conventional clinical examination. ©RSNA, 2015.

High-resolution Single Particle Analysis from Electron Cryo-microscopy Images Using SPHIRE

PubMed Central

Moriya, Toshio; Saur, Michael; Stabrin, Markus; Merino, Felipe; Voicu, Horatiu; Huang, Zhong; Penczek, Pawel A.; Raunser, Stefan; Gatsogiannis, Christos

2017-01-01

SPHIRE (SPARX for High-Resolution Electron Microscopy) is a novel open-source, user-friendly software suite for the semi-automated processing of single particle electron cryo-microscopy (cryo-EM) data. The protocol presented here describes in detail how to obtain a near-atomic resolution structure starting from cryo-EM micrograph movies by guiding users through all steps of the single particle structure determination pipeline. These steps are controlled from the new SPHIRE graphical user interface and require minimum user intervention. Using this protocol, a 3.5 Å structure of TcdA1, a Tc toxin complex from Photorhabdus luminescens, was derived from only 9500 single particles. This streamlined approach will help novice users without extensive processing experience and a priori structural information, to obtain noise-free and unbiased atomic models of their purified macromolecular complexes in their native state. PMID:28570515

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.

Correlating microscopy techniques and ToF-SIMS analysis of fully grown mammalian oocytes.

PubMed

Gulin, Alexander; Nadtochenko, Victor; Astafiev, Artyom; Pogorelova, Valentina; Rtimi, Sami; Pogorelov, Alexander

2016-06-20

The 2D-molecular thin film analysis protocol for fully grown mice oocytes is described using an innovative approach. Time-of-flight secondary ion mass spectrometry (ToF-SIMS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and optical microscopy imaging were applied to the same mice oocyte section on the same sample holder. A freeze-dried mice oocyte was infiltrated into embedding media, e.g. Epon, and then was cut with a microtome and 2 μm thick sections were transferred onto an ITO coated conductive glass. Mammalian oocytes can contain "nucleolus-like body" (NLB) units and ToF-SIMS analysis was used to investigate the NLB composition. The ion-spatial distribution in the cell components was identified and compared with the images acquired by SEM, AFM and optical microscopy. This study presents a significant advancement in cell embryology, cell physiology and cancer-cell biochemistry.

Advantages of indium-tin oxide-coated glass slides in correlative scanning electron microscopy applications of uncoated cultured cells.

PubMed

Pluk, H; Stokes, D J; Lich, B; Wieringa, B; Fransen, J

2009-03-01

A method of direct visualization by correlative scanning electron microscopy (SEM) and fluorescence light microscopy of cell structures of tissue cultured cells grown on conductive glass slides is described. We show that by growing cells on indium-tin oxide (ITO)-coated glass slides, secondary electron (SE) and backscatter electron (BSE) images of uncoated cells can be obtained in high-vacuum SEM without charging artefacts. Interestingly, we observed that BSE imaging is influenced by both accelerating voltage and ITO coating thickness. By combining SE and BSE imaging with fluorescence light microscopy imaging, we were able to reveal detailed features of actin cytoskeletal and mitochondrial structures in mouse embryonic fibroblasts. We propose that the application of ITO glass as a substrate for cell culture can easily be extended and offers new opportunities for correlative light and electron microscopy studies of adherently growing cells.

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.

Correlative SEM SERS for quantitative analysis of dimer nanoparticles.

PubMed

Timmermans, F J; Lenferink, A T M; van Wolferen, H A G M; Otto, C

2016-11-14

A Raman microscope integrated with a scanning electron microscope was used to investigate plasmonic structures by correlative SEM-SERS analysis. The integrated Raman-SEM microscope combines high-resolution electron microscopy information with SERS signal enhancement from selected nanostructures with adsorbed Raman reporter molecules. Correlative analysis is performed for dimers of two gold nanospheres. Dimers were selected on the basis of SEM images from multi aggregate samples. The effect of the orientation of the dimer with respect to the polarization state of the laser light and the effect of the particle gap size on the Raman signal intensity is observed. Additionally, calculations are performed to simulate the electric near field enhancement. These simulations are based on the morphologies observed by electron microscopy. In this way the experiments are compared with the enhancement factor calculated with near field simulations and are subsequently used to quantify the SERS enhancement factor. Large differences between experimentally observed and calculated enhancement factors are regularly detected, a phenomenon caused by nanoscale differences between the real and 'simplified' simulated structures. Quantitative SERS experiments reveal the structure induced enhancement factor, ranging from ∼200 to ∼20 000, averaged over the full nanostructure surface. The results demonstrate correlative Raman-SEM microscopy for the quantitative analysis of plasmonic particles and structures, thus enabling a new analytical method in the field of SERS and plasmonics.

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.

EMHP: an accurate automated hole masking algorithm for single-particle cryo-EM image processing.

PubMed

Berndsen, Zachary; Bowman, Charles; Jang, Haerin; Ward, Andrew B

2017-12-01

The Electron Microscopy Hole Punch (EMHP) is a streamlined suite of tools for quick assessment, sorting and hole masking of electron micrographs. With recent advances in single-particle electron cryo-microscopy (cryo-EM) data processing allowing for the rapid determination of protein structures using a smaller computational footprint, we saw the need for a fast and simple tool for data pre-processing that could run independent of existing high-performance computing (HPC) infrastructures. EMHP provides a data preprocessing platform in a small package that requires minimal python dependencies to function. https://www.bitbucket.org/chazbot/emhp Apache 2.0 License. bowman@scripps.edu. Supplementary data are available at Bioinformatics online. © The Author(s) 2017. Published by Oxford University Press.

Structural and morphological study of chemically synthesized CdSe thin films

NASA Astrophysics Data System (ADS)

Agrawal, P.; Singh, Randhir; Sharma, Jeewan; Sachdeva, M.; Singh, Anupinder; Bhargava, A.

2018-05-01

Nanocrystalline CdSe thin films were prepared by Chemical Bath Deposition (CBD) method using potassium nitrilo-triacetic acid cadmium complex and sodium selenosulphite. The as deposited films were red in color, uniform and well adherent to the glass substrate. These films were strongly dependent on the deposition parameters such as bath composition, deposition temperature and time. Films were annealed at 350 °C for four hours. The morphological, structural and optical properties were studied using X-ray diffraction (XRD), UV-VIS spectrophotometer measurements, scanning electron microscopy and atomic force microscopy. The XRD analysis confirmed that films are predominantly in hexagonal phase. Scanning electron micrograph shows that the grains are uniformly spread all over the film and each grain contains many nanocrystals with spherical shapes.

Effect of surface topography on structural growth of thick sputtered films

NASA Technical Reports Server (NTRS)

Spalvins, T.; Brainard, W. A.

1974-01-01

Primarily thick sputtered S-Monel, silver, and 304 stainless steel coatings were deposited on mica, glass, and metal substrates with various surface finishes to investigate the structural growth of the coating by scanning electron microscopy. Compositional changes within the coating were analyzed by X-ray dispersion microscopy. Defects in the surface finish act as preferential nucleation sites and form isolated and complex nodules and various surface overgrowths in the coating. These nodules do not disappear after full annealing. Further, they have undesirable effects on mechanial properties; cracks are initiated at the nodules when the coating is stressed by mechanical forces. These effects are illustrated by micrographs. Nodular growth within a coating can be minimized or eliminated by reducing the surface roughness.

Rethinking cell structure.

PubMed Central

Penman, S

1995-01-01

Cell structure, emerging from behind the veil of conventional electron microscopy, appears far more complex than formerly realized. The standard plastic-embedded, ultrathin section can image only what is on the section surface and masks the elaborate networks of the cytoplasm and nucleus. Embedment-free electron microscopy gives clear, high-contrast micrographs of cell structure when combined with removal of obscuring material such as soluble proteins. The resinless ultrathin section is the technique of choice; it is simple and inexpensive, and it uses ordinary electron microscopes. The resulting pictures reveal a world of complex cell structure and function. These images necessarily change our conception of the cytoskeleton, nuclear matrix, mitosis, and the relation of membranes to cytostructure. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:7777493

Imaging of surface spin textures on bulk crystals by scanning electron microscopy

NASA Astrophysics Data System (ADS)

Akamine, Hiroshi; Okumura, So; Farjami, Sahar; Murakami, Yasukazu; Nishida, Minoru

2016-11-01

Direct observation of magnetic microstructures is vital for advancing spintronics and other technologies. Here we report a method for imaging surface domain structures on bulk samples by scanning electron microscopy (SEM). Complex magnetic domains, referred to as the maze state in CoPt/FePt alloys, were observed at a spatial resolution of less than 100 nm by using an in-lens annular detector. The method allows for imaging almost all the domain walls in the mazy structure, whereas the visualisation of the domain walls with the classical SEM method was limited. Our method provides a simple way to analyse surface domain structures in the bulk state that can be used in combination with SEM functions such as orientation or composition analysis. Thus, the method extends applications of SEM-based magnetic imaging, and is promising for resolving various problems at the forefront of fields including physics, magnetics, materials science, engineering, and chemistry.

Correlative scanning-transmission electron microscopy reveals that a chimeric flavivirus is released as individual particles in secretory vesicles.

PubMed

Burlaud-Gaillard, Julien; Sellin, Caroline; Georgeault, Sonia; Uzbekov, Rustem; Lebos, Claude; Guillaume, Jean-Marc; Roingeard, Philippe

2014-01-01

The intracellular morphogenesis of flaviviruses has been well described, but flavivirus release from the host cell remains poorly documented. We took advantage of the optimized production of an attenuated chimeric yellow fever/dengue virus for vaccine purposes to study this phenomenon by microscopic approaches. Scanning electron microscopy (SEM) showed the release of numerous viral particles at the cell surface through a short-lived process. For transmission electron microscopy (TEM) studies of the intracellular ultrastructure of the small number of cells releasing viral particles at a given time, we developed a new correlative microscopy method: CSEMTEM (for correlative scanning electron microscopy - transmission electron microscopy). CSEMTEM analysis suggested that chimeric flavivirus particles were released as individual particles, in small exocytosis vesicles, via a regulated secretory pathway. Our morphological findings provide new insight into interactions between flaviviruses and cells and demonstrate that CSEMTEM is a useful new method, complementary to SEM observations of biological events by intracellular TEM investigations.

Correlative Scanning-Transmission Electron Microscopy Reveals that a Chimeric Flavivirus Is Released as Individual Particles in Secretory Vesicles

PubMed Central

Burlaud-Gaillard, Julien; Sellin, Caroline; Georgeault, Sonia; Uzbekov, Rustem; Lebos, Claude; Guillaume, Jean-Marc; Roingeard, Philippe

2014-01-01

The intracellular morphogenesis of flaviviruses has been well described, but flavivirus release from the host cell remains poorly documented. We took advantage of the optimized production of an attenuated chimeric yellow fever/dengue virus for vaccine purposes to study this phenomenon by microscopic approaches. Scanning electron microscopy (SEM) showed the release of numerous viral particles at the cell surface through a short-lived process. For transmission electron microscopy (TEM) studies of the intracellular ultrastructure of the small number of cells releasing viral particles at a given time, we developed a new correlative microscopy method: CSEMTEM (for correlative scanning electron microscopy - transmission electron microscopy). CSEMTEM analysis suggested that chimeric flavivirus particles were released as individual particles, in small exocytosis vesicles, via a regulated secretory pathway. Our morphological findings provide new insight into interactions between flaviviruses and cells and demonstrate that CSEMTEM is a useful new method, complementary to SEM observations of biological events by intracellular TEM investigations. PMID:24681578

Characterization of konjac glucomannan-ethyl cellulose film formation via microscopy.

PubMed

Xiao, Man; Wan, Li; Corke, Harold; Yan, Wenli; Ni, Xuewen; Fang, Yapeng; Jiang, Fatang

2016-04-01

Konjac glucomannan-ethyl cellulose (KGM-EC, 7:3, w/w) blended film shows good mechanical and moisture resistance properties. To better understand the basis for the KGM-EC film formation, optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) were used to observe the formation of the film from emulsion. Optical microscopy images showed that EC oil droplets were homogeneously dispersed in KGM water phase without obviously coalescence throughout the entire drying process. SEM images showed the surface and cross-sectional structures of samples maintained continuous and homogeneous appearance from the emulsion to dried film. AFM images indicated that KGM molecules entangled EC molecules in the emulsion. Interactions between KGM and EC improved the stability of KGM-EC emulsion, and contributed to uniformed structures of film formation. Based on these output information, a schematic model was built to elucidate KGM-EC film-forming process. Copyright © 2015 Elsevier B.V. All rights reserved.

Novel Electrochemical Process for Treatment of Perchlorate in Waste Water

DTIC Science & Technology

2011-03-06

Prepared in Different Processes: (b) in 0.1 M Pyrrole Solution with 0.1 M NaCl at 0.8 V for 20 min; (c) at 0.5 V for 400 s in 0.1 M ClO4- Solution and...polypyrrole Py pyrrole SEM scanning electron microscopy SON statement of need XPS X-ray photoelectron spectroscopy v Acknowledgments This work is...shows the scanning electron microscopy (SEM) images of carbon fiber paper and a CNT array grown on carbon fiber paper. Pyrrole (Py) deposition

X-ray microscopy using reflection targets based on SEM with tungsten filament

NASA Astrophysics Data System (ADS)

Liu, Junbiao; Ma, Yutian; Zhao, Weixia; Niu, Geng; Chu, Mingzhang; Yin, Bohua; Han, Li; Liu, Baodong

2016-10-01

X-ray MicroandNano imaging is developed based on the conventional x-ray tomography, it can not only provide nondestructive testing with higher resolution measurement, but also be used to examine the material or the structure with low atomic number and low density. The source with micro-focal spot size is one of the key components of x-ray MicroandNano imaging. The focused electron beam from SEM bombarding the metal target can generate x-ray with ultra-small size. It is convenient to set up x-ray microscopy based on SEM for laboratory use. This paper describes a new x-ray microscopy using reflection targets based on FEI Quanta600 SEM with tungsten filament. The flat panel detector is placed outside of the vacuum chamber with 300μm thickness Be-window to isolate vacuum from the air. A stage with 3 DOFs is added to adjust the positions of the target, the SEM's sample stage is used to move sample. And the shape of target is designed as cone with 60° half cone angle to get the maximum x-ray dosage. The attenuation coefficient of Bewindow for x-ray is about 25%. Finally, the line pair card is used to evaluate the resolution and the result shows that the resolution of the system can receive less than 750nm, when the acceleration voltage is 30keV, the beam current is 160nA, the SEM working distance is 5mm and the acquisition time of the detector is 60s.

The detection of metallic residues in skin stab wounds by means of SEM-EDS: A pilot study.

PubMed

Palazzo, Elisa; Amadasi, Alberto; Boracchi, Michele; Gentile, Guendalina; Maciocco, Francesca; Marchesi, Matteo; Zoja, Riccardo

2018-05-01

The morphological analysis of stab wounds may often not be accurate enough to link it with the type of wounding weapon, but a further evaluation may be performed with the search for metallic residues left during the contact between the instrument and the skin. In this study, Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) was applied to the study of cadaveric stab wounds performed with kitchen knives composed of iron, chromium and nickel, in order to verify the presence of metallic residues on the wound's edge. Two groups of 10 corpses were selected: group A, including victims of stab wounds and a control group B (died of natural causes). Samplings were performed on the lesions and in intact areas of group A, whereas in group B sampling were performed in non-exposed intact skin. Samples were then analysed with optical microscopy and SEM-EDS. In group A, optical microscopic analysis showed the presence of vital haemorrhagic infiltration, while SEM-EDS showed evidence of microscopic metal traces, isolated or clustered, consisting of iron, chromium and nickel. Moreover, in two cases organic residues of calcium and phosphate were detected, as a probable sign of bone lesion. Control samples (group A in intact areas and group B), were negative for the search of exogenous material to optical microscopy and SEM-EDS. The results show the utility and possible application of the SEM-EDS in theidentification of metallic residues from sharp weapons on the skin. Copyright © 2017 The Chartered Society of Forensic Sciences. Published by Elsevier B.V. All rights reserved.

Counting Synapses Using FIB/SEM Microscopy: A True Revolution for Ultrastructural Volume Reconstruction.

PubMed

Merchán-Pérez, Angel; Rodriguez, José-Rodrigo; Alonso-Nanclares, Lidia; Schertel, Andreas; Defelipe, Javier

2009-01-01

The advent of transmission electron microscopy (TEM) in the 1950s represented a fundamental step in the study of neuronal circuits. The application of this technique soon led to the realization that the number of synapses changes during the course of normal life, as well as under certain pathological or experimental circumstances. Since then, one of the main goals in neurosciences has been to define simple and accurate methods to estimate the magnitude of these changes. Contrary to analysing single sections, TEM reconstructions are extremely time-consuming and difficult. Therefore, most quantitative studies use stereological methods to define the three-dimensional characteristics of synaptic junctions that are studied in two dimensions. Here, to count the exact number of synapses per unit of volume we have applied a new three-dimensional reconstruction method that involves the combination of focused ion beam milling and scanning electron microscopy (FIB/SEM). We show that the images obtained with FIB/SEM are similar to those obtained with TEM, but with the advantage that FIB/SEM permits serial reconstructions of large volumes of tissue to be generated rapidly and automatically. Furthermore, we compared the estimates of the number of synapses obtained with stereological methods with the values obtained by FIB/SEM reconstructions. We concluded that FIB/SEM not only provides the actual number of synapses per volume but it is also much easier and faster to use than other currently available TEM methods. More importantly, it also avoids most of the errors introduced by stereological methods and overcomes the difficulties associated with these techniques.

In-Situ Preparation of Aramid-Multiwalled CNT Nano-Composites: Morphology, Thermal Mechanical and Electric Properties

PubMed Central

Shiju, Jessy; Al-Sagheer, Fakhreia; Bumajdad, Ali; Ahmad, Zahoor

2018-01-01

In this work in-situ polymerization technique has been used to chemically link the functionalized multiwalled carbon nanotubes (CNTs) with aramid matrix chains. Phenylene diamine monomers were reacted in the first stage with the carboxylic acid functionalized CNTs and then amidized in-situ using terephthaloyl chloride generating chemically bonded CNTs with the matrix. Various proportions of the CNTs were used to prepare the hybrid materials. The functionalization procedure was studied by Fourier transform infrared (FTIR) spectroscopy and composite morphology investigated by scanning electron microscopy (SEM). Thermal mechanical properties of these hybrids, together with those where pristine CNTs with similar loadings were used, are compared using tensile and dynamic mechanical analysis (DMA). The tensile strength and temperature involving α-relaxations on CNT loading increased with CNT loading in both systems, but much higher values, i.e., 267 MPa and 353 °C, respectively, were obtained in the chemically bonded system, which are related to the nature of the interface developed as observed in SE micrographs. The water absorption capacity of the films was significantly reduced from 6.2 to 1.45% in the presence pristine CNTs. The inclusion of pristine CNTs increased the electric conductivity of the aramid films with a minimum threshold value at the loading of 3.5 wt % of CNTs. Such mechanically strong and thermally stable aramid and easily processable composites can be suitable for various applications including high performance films, electromagnetic shielding and radar absorption. PMID:29735952

Antioxidative study of Cerium Oxide nanoparticle functionalised PCL-Gelatin electrospun fibers for wound healing application.

PubMed

Rather, Hilal Ahmad; Thakore, Ria; Singh, Ragini; Jhala, Dhwani; Singh, Sanjay; Vasita, Rajesh

2018-06-01

Skin wound healing involves a coordinated cellular response to achieve complete reepithelialisation. Elevated levels of reactive oxygen species (ROS) in the wound environment often pose a hindrance in wound healing resulting in impaired wound healing process. Cerium oxide nanoparticles (CeNPs) have the ability to protect the cells from oxidative damage by actively scavenging the ROS. Furthermore, matrices like nanofibers have also been explored for enhancing wound healing. In the current study CeNP functionalised polycaprolactone (PCL)-gelatin nanofiber (PGNPNF) mesh was fabricated by electrospinning and evaluated for its antioxidative potential. Wide angle XRD analysis of randomly oriented nanofibers revealed ∼2.6 times reduced crystallinity than pristine PCL which aided in rapid degradation of nanofibers and release of CeNP. However, bioactive composite made between nanoparticles and PCL-gelatin maintained the fibrous morphology of PGNPNF upto 14 days. The PGNPNF mesh exhibited a superoxide dismutase (SOD) mimetic activity due to the incorporated CeNPs. The PGNPNF mesh enhanced proliferation of 3T3-L1 cells by ∼48% as confirmed by alamar blue assay and SEM micrographs of cells grown on the nanofibrous mesh. Furthermore, the PGNPNF mesh scavenged ROS, which was measured by relative DCF intensity and fluorescence microscopy; and subsequently increased the viability and proliferation of cells by three folds as it alleviated the oxidative stress. Overall, the results of this study suggest the potential of CeNP functionalised PCL-gelatin nanofibrous mesh for wound healing applications.

Influence of different restorative techniques on marginal seal of class II composite restorations

PubMed Central

RODRIGUES JUNIOR, Sinval Adalberto; PIN, Lúcio Fernando da Silva; MACHADO, Giovanna; DELLA BONA, Álvaro; DEMARCO, Flávio Fernando

2010-01-01

Objective To evaluate the gingival marginal seal in class II composite restorations using different restorative techniques. Material and Methods Class II box cavities were prepared in both proximal faces of 32 sound human third molars with gingival margins located in either enamel or dentin/cementum. Restorations were performed as follows: G1 (control): composite, conventional light curing technique; G2: composite, soft-start technique; G3: amalgam/composite association (amalcomp); and G4: resin-modified glass ionomer cement/ composite, open sandwich technique. The restored specimens were thermocycled. Epoxy resin replicas were made and coated for scanning electron microscopy examination. For microleakage evaluation, teeth were coated with nail polish and immersed in dye solution. Teeth were cut in 3 slices and dye penetration was recorded (mm), digitized and analyzed with Image Tool software. Microleakage data were analyzed statistically by non-parametric Kruskal-Wallis and Mann-Whitney tests. Results Leakage in enamel was lower than in dentin (p<0.001). G2 exhibited the lowest leakage values (p<0.05) in enamel margins, with no differences between the other groups. In dentin margins, groups G1 and G2 had similar behavior and both showed less leakage (p<0.05) than groups G3 and G4. SEM micrographs revealed different marginal adaptation patterns for the different techniques and for the different substrates. Conclusion The soft-start technique showed no leakage in enamel margins and produced similar values to those of the conventional (control) technique for dentin margins. PMID:20379680

Computer-aided screening system for cervical precancerous cells based on field emission scanning electron microscopy and energy dispersive x-ray images and spectra

NASA Astrophysics Data System (ADS)

Jusman, Yessi; Ng, Siew-Cheok; Hasikin, Khairunnisa; Kurnia, Rahmadi; Osman, Noor Azuan Bin Abu; Teoh, Kean Hooi

2016-10-01

The capability of field emission scanning electron microscopy and energy dispersive x-ray spectroscopy (FE-SEM/EDX) to scan material structures at the microlevel and characterize the material with its elemental properties has inspired this research, which has developed an FE-SEM/EDX-based cervical cancer screening system. The developed computer-aided screening system consisted of two parts, which were the automatic features of extraction and classification. For the automatic features extraction algorithm, the image and spectra of cervical cells features extraction algorithm for extracting the discriminant features of FE-SEM/EDX data was introduced. The system automatically extracted two types of features based on FE-SEM/EDX images and FE-SEM/EDX spectra. Textural features were extracted from the FE-SEM/EDX image using a gray level co-occurrence matrix technique, while the FE-SEM/EDX spectra features were calculated based on peak heights and corrected area under the peaks using an algorithm. A discriminant analysis technique was employed to predict the cervical precancerous stage into three classes: normal, low-grade intraepithelial squamous lesion (LSIL), and high-grade intraepithelial squamous lesion (HSIL). The capability of the developed screening system was tested using 700 FE-SEM/EDX spectra (300 normal, 200 LSIL, and 200 HSIL cases). The accuracy, sensitivity, and specificity performances were 98.2%, 99.0%, and 98.0%, respectively.

Focused ion beam (FIB)/scanning electron microscopy (SEM) in tissue structural research.

PubMed

Leser, Vladka; Milani, Marziale; Tatti, Francesco; Tkalec, Ziva Pipan; Strus, Jasna; Drobne, Damjana

2010-10-01

The focused ion beam (FIB) and scanning electron microscope (SEM) are commonly used in material sciences for imaging and analysis of materials. Over the last decade, the combined FIB/SEM system has proven to be also applicable in the life sciences. We have examined the potential of the focused ion beam/scanning electron microscope system for the investigation of biological tissues of the model organism Porcellio scaber (Crustacea: Isopoda). Tissue from digestive glands was prepared as for conventional SEM or as for transmission electron microscopy (TEM). The samples were transferred into FIB/SEM for FIB milling and an imaging operation. FIB-milled regions were secondary electron imaged, back-scattered electron imaged, or energy dispersive X-ray (EDX) analyzed. Our results demonstrated that FIB/SEM enables simultaneous investigation of sample gross morphology, cell surface characteristics, and subsurface structures. The same FIB-exposed regions were analyzed by EDX to provide basic compositional data. When samples were prepared as for TEM, the information obtained with FIB/SEM is comparable, though at limited magnification, to that obtained from TEM. A combination of imaging, micro-manipulation, and compositional analysis appears of particular interest in the investigation of epithelial tissues, which are subjected to various endogenous and exogenous conditions affecting their structure and function. The FIB/SEM is a promising tool for an overall examination of epithelial tissue under normal, stressed, or pathological conditions.

Seeing a Mycobacterium-Infected Cell in Nanoscale 3D: Correlative Imaging by Light Microscopy and FIB/SEM Tomography

PubMed Central

Beckwith, Marianne Sandvold; Beckwith, Kai Sandvold; Sikorski, Pawel; Skogaker, Nan Tostrup

2015-01-01

Mycobacteria pose a threat to the world health today, with pathogenic and opportunistic bacteria causing tuberculosis and non-tuberculous disease in large parts of the population. Much is still unknown about the interplay between bacteria and host during infection and disease, and more research is needed to meet the challenge of drug resistance and inefficient vaccines. This work establishes a reliable and reproducible method for performing correlative imaging of human macrophages infected with mycobacteria at an ultra-high resolution and in 3D. Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM) tomography is applied, together with confocal fluorescence microscopy for localization of appropriately infected cells. The method is based on an Aclar poly(chloro-tri-fluoro)ethylene substrate, micropatterned into an advantageous geometry by a simple thermomoulding process. The platform increases the throughput and quality of FIB/SEM tomography analyses, and was successfully applied to detail the intracellular environment of a whole mycobacterium-infected macrophage in 3D. PMID:26406896

Respiratory assessment of refractory ceramic fibers in a heating technician population.

PubMed

Lucas, David; Clamagirand, Vincent; Capellmann, Pascale; Hervé, Agnès; Mauguen, Gilles; Le Mer, Yannik; Jegaden, Dominique

2018-04-01

Refractory ceramic fibers (RCF) have been extensively used for insulation in condensing boilers. The aim of this study was to evaluate the respiratory exposure to these fibers among maintenance heating technicians. We first created a working group (Carsat Brittany and Finistère Occupational Health Services) and carried out a sampling strategy. Atmospheric measurements were done during work tasks, and filters were analyzed by phase contrast microscopy (PCM) and scanning electron microscopy (SEM) in French approved laboratories. Four companies were included for a total of 15 days of work. During those 15 workdays, 12 SEM and 21 PCM samples were taken and analyzed. The phase contrast microscopy and SEM average results were 0.04 and 0.004 fibers/cm 3 , respectively. In conclusion, the study confirms heating technician RCF respiratory exposure during maintenance work for both condensation gas boilers and atmospheric boilers. Collective and individual prevention measures should be implemented along with appropriate medical follow-up.

Three-dimensional ultrastructure of osteocytes assessed by focused ion beam-scanning electron microscopy (FIB-SEM).

PubMed

Hasegawa, Tomoka; Yamamoto, Tomomaya; Hongo, Hiromi; Qiu, Zixuan; Abe, Miki; Kanesaki, Takuma; Tanaka, Kawori; Endo, Takashi; de Freitas, Paulo Henrique Luiz; Li, Minqi; Amizuka, Norio

2018-04-01

The aim of this study is to demonstrate the application of focused ion beam-scanning electron microscopy, FIB-SEM for revealing the three-dimensional features of osteocytic cytoplasmic processes in metaphyseal (immature) and diaphyseal (mature) trabeculae. Tibiae of eight-week-old male mice were fixed with aldehyde solution, and treated with block staining prior to FIB-SEM observation. While two-dimensional backscattered SEM images showed osteocytes' cytoplasmic processes in a fragmented fashion, three-dimensional reconstructions of FIB-SEM images demonstrated that osteocytes in primary metaphyseal trabeculae extended their cytoplasmic processes randomly, thus maintaining contact with neighboring osteocytes and osteoblasts. In contrast, diaphyseal osteocytes extended thin cytoplasmic processes from their cell bodies, which ran perpendicular to the bone surface. In addition, these osteocytes featured thick processes that branched into thinner, transverse cytoplasmic processes; at some point, however, these transverse processes bend at a right angle to run perpendicular to the bone surface. Osteoblasts also possessed thicker cytoplasmic processes that branched off as thinner processes, which then connected with cytoplasmic processes of neighboring osteocytes. Thus, FIB-SEM is a useful technology for visualizing the three-dimensional structures of osteocytes and their cytoplasmic processes.

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.

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.

Sub-diffraction-limit localization imaging of a plasmonic nanoparticle pair with wavelength-resolved dark-field microscopy.

PubMed

Wei, Lin; Ma, Yanhong; Zhu, Xupeng; Xu, Jianghong; Wang, Yaxin; Duan, Huigao; Xiao, Lehui

2017-06-29

In this work, with wavelength-resolved dark-field microscopy, the center-of-mass localization information from nanoparticle pairs (i.e., spherical (45 nm in diameter) and rod (45 × 70 nm) shaped gold nanoparticle pairs with different gap distances and orientations) was explored and compared with the results determined by scanning electron microscopy (SEM) measurements. When the gap distance was less than 20 nm, the scattering spectrum of the nanoparticle pair was seriously modulated by the plasmonic coupling effect. The measured coordinate information determined by the optical method (Gaussian fitting) was not consistent with the true results determined by SEM measurement. A good correlation between the optical and SEM measurements was achieved when the gap distance was further increased (e.g., 20, 40 and 60 nm). Under these conditions, well-defined scattering peaks assigned to the corresponding individual nanoparticles could be distinguished from the obtained scattering spectrum. These results would afford valuable information for the studies on single plasmonic nanoparticle imaging applications with the optical microscopy method such as super-localization imaging, high precision single particle tracking in a crowding environment and so on.

Short range shooting distance estimation using variable pressure SEM images of the surroundings of bullet holes in textiles.

PubMed

Hinrichs, Ruth; Frank, Paulo Ricardo Ost; Vasconcellos, M A Z

2017-03-01

Modifications of cotton and polyester textiles due to shots fired at short range were analyzed with a variable pressure scanning electron microscope (VP-SEM). Different mechanisms of fiber rupture as a function of fiber type and shooting distance were detected, namely fusing, melting, scorching, and mechanical breakage. To estimate the firing distance, the approximately exponential decay of GSR coverage as a function of radial distance from the entrance hole was determined from image analysis, instead of relying on chemical analysis with EDX, which is problematic in the VP-SEM. A set of backscattered electron images, with sufficient magnification to discriminate micrometer wide GSR particles, was acquired at different radial distances from the entrance hole. The atomic number contrast between the GSR particles and the organic fibers allowed to find a robust procedure to segment the micrographs into binary images, in which the white pixel count was attributed to GSR coverage. The decrease of the white pixel count followed an exponential decay, and it was found that the reciprocal of the decay constant, obtained from the least-square fitting of the coverage data, showed a linear dependence on the shooting distance. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

Atomic force microscopy imaging of fragments from the Martian meteorite ALH84001

NASA Technical Reports Server (NTRS)

Steele, A.; Goddard, D.; Beech, I. B.; Tapper, R. C.; Stapleton, D.; Smith, J. R.

1998-01-01

A combination of scanning electron microscopy (SEM) and environmental scanning electron microscopy (ESEM) techniques, as well as atomic force microscopy (AFM) methods has been used to study fragments of the Martian meteorite ALH84001. Images of the same areas on the meteorite were obtained prior to and following gold/palladium coating by mapping the surface of the fragment using ESEM coupled with energy-dispersive X-ray analysis. Viewing of the fragments demonstrated the presence of structures, previously described as nanofossils by McKay et al. (Search for past life on Mars--possible relic biogenic activity in martian meteorite ALH84001. Science, 1996, pp. 924-930) of NASA who used SEM imaging of gold-coated meteorite samples. Careful imaging of the fragments revealed that the observed structures were not an artefact introduced by the coating procedure.

A compilation of cold cases using scanning electron microscopy at the University of Rhode Island

NASA Astrophysics Data System (ADS)

Platek, Michael J.; Gregory, Otto J.

2015-10-01

Scanning electron microscopy combined with microchemical analysis has evolved into one of the most widely used instruments in forensic science today. In particular, the environmental scanning electron microscope (SEM) in conjunction with energy dispersive spectroscopy (EDS), has created unique opportunities in forensic science in regard to the examination of trace evidence; i.e. the examination of evidence without altering the evidence with conductive coatings, thereby enabling criminalists to solve cases that were previously considered unsolvable. Two cold cases were solved at URI using a JEOL 5900 LV SEM in conjunction with EDS. A cold case murder and a cold missing person case will be presented from the viewpoint of the microscopist and will include sample preparation, as well as image and chemical analysis of the trace evidence using electron microscopy and optical microscopy.

Development of an in-situ multi-component reinforced Al-based metal matrix composite by direct metal laser sintering technique — Optimization of process parameters

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

Ghosh, Subrata Kumar, E-mail: subratagh82@gmail.com; Bandyopadhyay, Kaushik; Saha, Partha

2014-07-01

In the present investigation, an in-situ multi-component reinforced aluminum based metal matrix composite was fabricated by the combination of self-propagating high-temperature synthesis and direct metal laser sintering process. The different mixtures of Al, TiO{sub 2} and B{sub 4}C powders were used to initiate and maintain the self-propagating high-temperature synthesis by laser during the sintering process. It was found from the X-ray diffraction analysis and scanning electron microscopy that the reinforcements like Al{sub 2}O{sub 3}, TiC, and TiB{sub 2} were formed in the composite. The scanning electron microscopy revealed the distribution of the reinforcement phases in the composite and phase identities.more » The variable parameters such as powder layer thickness, laser power, scanning speed, hatching distance and composition of the powder mixture were optimized for higher density, lower porosity and higher microhardness using Taguchi method. Experimental investigation shows that the density of the specimen mainly depends upon the hatching distance, composition and layer thickness. On the other hand, hatching distance, layer thickness and laser power are the significant parameters which influence the porosity. The composition, laser power and layer thickness are the key influencing parameters for microhardness. - Highlights: • The reinforcements such as Al{sub 2}O{sub 3}, TiC, and TiB{sub 2} were produced in Al-MMC through SHS. • The density is mainly influenced by the material composition and hatching distance. • Hatching distance is the major influencing parameter on porosity. • The material composition is the significant parameter to enhance the microhardness. • The SEM micrographs reveal the distribution of TiC, TiB{sub 2} and Al{sub 2}O{sub 3} in the composite.« less

Chemically synthesized TiO2 and PANI/TiO2 thin films for ethanol sensing applications

NASA Astrophysics Data System (ADS)

Gawri, Isha; Ridhi, R.; Singh, K. P.; Tripathi, S. K.

2018-02-01

Ethanol sensing properties of chemically synthesized titanium dioxide (TiO2) and polyaniline/titanium dioxide nanocomposites (PANI/TiO2) had been performed at room temperature. In-situ oxidative polymerization process had been employed with aniline as a monomer in presence of anatase titanium dioxide nanoparticles. The prepared samples were structurally and morphologically characterized by x-ray diffraction, fourier transform infrared spectra, high resolution-transmission electron microscopy and field emission-scanning electron microscopy. The crystallinity of PANI/TiO2 nanocomposite was revealed by XRD and FTIR spectra confirmed the presence of chemical bonding between the polymer chains and metal oxide nanoparticles. HR-TEM micrographs depicted that TiO2 particles were embedded in polymer matrix, which provides an advantage over pure TiO2 nanoparticles in efficient adsorption of vapours. These images also revealed that the TiO2 nanoparticles were irregular in shape with size around 17 nm. FE-SEM studies revealed that in the porous structure of PANI/TiO2 film, the intercalation of TiO2 in PANI chains provides an advantage over pure TiO2 film for uniform interaction with ethanol vapors. The sensitivity values of prepared samples were examined towards ethanol vapours at room temperature. The PANI/TiO2 nanocomposite exhibited better sensing response and faster response-recovery examined at different ethanol concentrations ranging from 5 ppm to 20 ppm in comparison to pure TiO2 nanoparticles. The increase in vapour sensing of PANI/TiO2 sensing film as compared to pure TiO2 film had been explained in detail with the help of gas sensing mechanism of TiO2 and PANI/TiO2. This provides strong evidence that gas sensing properties of TiO2 had been considerably improved and enhanced with the addition of polymer matrix.

New Insights on Subsurface Imaging of Carbon Nanotubes in Polymer Composites via Scanning Electron Microscopy

NASA Technical Reports Server (NTRS)

Zhao, Minhua; Ming, Bin; Kim, Jae-Woo; Gibbons, Luke J.; Gu, Xiaohong; Nguyen, Tinh; Park, Cheol; Lillehei, Peter T.; Villarrubia, J. S.; Vladar, Andras E.;

High-Resolution Scanning Electron Microscopy and Immuno-Gold Labeling of the Nuclear Lamina and Nuclear Pore Complex.

PubMed

Goldberg, Martin W

2016-01-01

Scanning electron microscopy (SEM) is a technique used to image surfaces. Field emission SEMs (feSEMs) can resolve structures that are ~0.5-1.5 nm apart. FeSEM, therefore is a useful technique for imaging molecular structures that exist at surfaces such as membranes. The nuclear envelope consists of four membrane surfaces, all of which may be accessible for imaging. Imaging of the cytoplasmic face of the outer membrane gives information about ribosomes and cytoskeletal attachments, as well as details of the cytoplasmic peripheral components of the nuclear pore complex, and is the most easily accessed surface. The nucleoplasmic face of the inner membrane is easily accessible in some cells, such as amphibian oocytes, giving valuable details about the organization of the nuclear lamina and how it interacts with the nuclear pore complexes. The luminal faces of both membranes are difficult to access, but may be exposed by various fracturing techniques. Protocols are presented here for the preparation, labeling, and feSEM imaging of Xenopus laevis oocyte nuclear envelopes.

Human cardiac telocytes: 3D imaging by FIB-SEM tomography.

PubMed

Cretoiu, D; Hummel, E; Zimmermann, H; Gherghiceanu, M; Popescu, L M

2014-11-01

Telocyte (TC) is a newly identified type of cell in the cardiac interstitium (www.telocytes.com). TCs are described by classical transmission electron microscopy as cells with very thin and long telopodes (Tps; cellular prolongations) having podoms (dilations) and podomers (very thin segments). TCs' three-dimensional (3D) morphology is still unknown. Cardiac TCs seem to be particularly involved in long and short distance intercellular signalling and, therefore, their 3D architecture is important for understanding their spatial connections. Using focused ion beam scanning electron microscopy (FIB-SEM) we show, for the first time, the whole ultrastructural anatomy of cardiac TCs. 3D reconstruction of cardiac TCs by FIB-SEM tomography confirms that they have long, narrow but flattened (ribbon-like) telopodes, with humps generated by the podoms. FIB-SEM tomography also confirms the network made by TCs in the cardiac interstitium through adherens junctions. This study provides the first FIB-SEM tomography of a human cell type. © 2014 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Optical characterization of fritted glass for architectural applications

NASA Astrophysics Data System (ADS)

Jonsson, Jacob C.; Rubin, Michael D.; Nilsson, Annica M.; Jonsson, Andreas; Roos, Arne

2009-04-01

Fritted glass is commonly used as a light diffusing element in modern buildings. Traditionally it has been used for aesthetic purposes but it can also be used for energy savings by incorporating it in novel daylighting systems? To answer such questions the light scattering properties must be properly characterized. This paper contains measurements of different varieties of fritted glass, ranging from the simplest direct-hemispherical measurements to angle-resolved goniometer measurements. Modeling the light scattering to obtain the full bidirectional scattering distribution function (BSDF) extends the measured data, making it useful in simulation programs such as Window 6 and Radiance. Surface profilometry results and SEM micrographs are included to demonstrate the surface properties of the samples studied.

Synthesis and characterization of laminated Si/SiC composites

PubMed Central

Naga, Salma M.; Kenawy, Sayed H.; Awaad, Mohamed; Abd El-Wahab, Hamada S.; Greil, Peter; Abadir, Magdi F.

2012-01-01

Laminated Si/SiC ceramics were synthesized from porous preforms of biogenous carbon impregnated with Si slurry at a temperature of 1500 °C for 2 h. Due to the capillarity infiltration with Si, both intrinsic micro- and macrostructure in the carbon preform were retained within the final ceramics. The SEM micrographs indicate that the final material exhibits a distinguished laminar structure with successive Si/SiC layers. The produced composites show weight gain of ≈5% after heat treatment in air at 1300 °C for 50 h. The produced bodies could be used as high temperature gas filters as indicated from the permeability results. PMID:25685404

Biodegradation of thermoplastic starch/eggshell powder composites.

PubMed

Bootklad, Munlika; Kaewtatip, Kaewta

2013-09-12

Thermoplastic starch (TPS) was prepared using compression molding and chicken eggshell was used as a filler. The effect of the eggshell powder (EP) on the properties of TPS was compared with the effect of commercial calcium carbonate (CC). The organic compound on the surface of the eggshell powder acted as a coupling agent that resulted in a strong adhesion between the eggshell powder and the TPS matrix, as confirmed by SEM micrographs. The biodegradation was determined by the soil burial test. The TPS/EP composites were more rapidly degraded than the TPS/CC composites. In addition, the eggshell powder improved the water resistance and thermal stability of the TPS. Copyright © 2013 Elsevier Ltd. All rights reserved.

Ecology and life history of an amoebomastigote, Paratetramitus jugosus, from a microbial mat: new evidence for multiple fission

NASA Technical Reports Server (NTRS)

Enzien, M.; McKhann, H. I.; Margulis, L.

1989-01-01

Five microbial habitats (gypsum crust, gypsum photosynthetic community, Microcoleus mat, Thiocapsa scum, and black mud) were sampled for the presence of the euryhaline, rapidly growing amoebomastigote, Paratetramitus jugosus. Field investigations of microbial mats from Baja California Norte, Mexico, and Salina Bido near Matanzas, Cuba, reveal that P. jugosus is most frequently found in the Thiocapsa layer of microbial mats. Various stages of the life history were studied using phase-contrast, differential-interference, and transmission electron microscopy. Mastigote stages were induced and studied by electron microscopy; mastigotes that actively feed on bacteria bear two or more undulipodia. A three-dimensional drawing of the kinetid ("basal apparatus") based on electron micrographs is presented. Although promitoses were occasionally observed, it is unlikely that they can account for the rapid growth of P. jugosus populations on culture media. Dense, refractile, spherical, and irregular-shaped bodies were seen at all times in all cultures along with small mononucleate (approximately 2-7 micrometers diameter) amoebae. Cytochemical studies employing two different fluorescent stains for DNA (DAPI, mithramycin) verified the presence of DNA in these small bodies. Chromatin-like material seen in electron micrographs within the cytoplasm and blebbing off nuclei were interpreted to the chromatin bodies. Our interpretation, consistent with the data but not proven, is that propagation by multiple fission of released chromatin bodies that become small amoebae may occur in Paratetramitus jugosus. These observations are consistent with descriptions of amoeba propagules in the early literature (Hogue, 1914).

Morphology selection for cupric oxide thin films by electrodeposition.

PubMed

Dhanasekaran, V; Mahalingam, T; Chandramohan, R

2011-10-01

Polycrystalline cupric oxide thin films were deposited using alkaline solution bath employing cathodic electrodeposition method. The thin films were electrodeposited at various solution pH. The surface morphology and elemental analyzes of the films were studied using scanning electron microscopy (SEM) and energy dispersive X-ray analysis, respectively. SEM studies revealed that the surface morphology could be tailored suitably by adjusting the pH value during deposition. Mesh average on multiple lattice mode atomic force microscopy image was obtained and reported. Copyright © 2011 Wiley-Liss, Inc.

Surface characteristics of isopod digestive gland epithelium studied by SEM.

PubMed

Millaku, Agron; Leser, Vladka; Drobne, Damjana; Godec, Matjaz; Torkar, Matjaz; Jenko, Monika; Milani, Marziale; Tatti, Francesco

2010-05-01

The structure of the digestive gland epithelium of a terrestrial isopod Porcellio scaber has been investigated by conventional scanning electron microscopy (SEM), focused ion beam-scanning electron microscopy (FIB/SEM), and light microscopy in order to provide evidence on morphology of the gland epithelial surface in animals from a stock culture. We investigated the shape of cells, extrusion of lipid droplets, shape and distribution of microvilli, and the presence of bacteria on the cell surface. A total of 22 animals were investigated and we found some variability in the appearance of the gland epithelial surface. Seventeen of the animals had dome-shaped digestive gland "normal" epithelial cells, which were densely and homogeneously covered by microvilli and varying proportions of which extruded lipid droplets. On the surface of microvilli we routinely observed sparsely distributed bacteria of different shapes. Five of the 22 animals had "abnormal" epithelial cells with a significantly altered shape. In three of these animals, the cells were much smaller, partly or completely flat or sometimes pyramid-like. A thick layer of bacteria was detected on the microvillous border, and in places, the shape and size of microvilli were altered. In two animals, hypertrophic cells containing large vacuoles were observed indicating a characteristic intracellular infection. The potential of SEM in morphological investigations of epithelial surfaces is discussed.

SEM-EDX analysis of an unknown "known" white powder found in a shipping container from Peru

NASA Astrophysics Data System (ADS)

Albright, Douglas C.

2009-05-01

In 2008, an unknown white powder was discovered spilled inside of a shipping container of whole kernel corn during an inspection by federal inspectors in the port of Baltimore, Maryland. The container was detained and quarantined while a sample of the powder was collected and sent to a federal laboratory where it was screened using chromatography for the presence of specific poisons and pesticides with negative results. Samples of the corn kernels and the white powder were forwarded to the Food and Drug Administration, Forensic Chemistry Center for further analysis. Stereoscopic Light Microscopy (SLM), Scanning Electron Microscopy/Energy Dispersive X-ray Spectrometry (SEM/EDX), and Polarized Light Microscopy/Infrared Spectroscopy (PLM-IR) were used in the analysis of the kernels and the unknown powder. Based on the unique particle analysis by SLM and SEM as well as the detection of the presence of aluminum and phosphorous by EDX, the unknown was determined to be consistent with reacted aluminum phosphide (AlP). While commonly known in the agricultural industry, aluminum phosphide is relatively unknown in the forensic community. A history of the use and acute toxicity of this compound along with some very unique SEM/EDX analysis characteristics of aluminum phosphide will be discussed.

FIB-SEM tomography of human skin telocytes and their extracellular vesicles

PubMed Central

Cretoiu, Dragos; Gherghiceanu, Mihaela; Hummel, Eric; Zimmermann, Hans; Simionescu, Olga; Popescu, Laurentiu M

2015-01-01

We have shown in 2012 the existence of telocytes (TCs) in human dermis. TCs were described by transmission electron microscopy (TEM) as interstitial cells located in non-epithelial spaces (stroma) of many organs (see www.telocytes.com). TCs have very long prolongations (tens to hundreds micrometers) named Telopodes (Tps). These Tps have a special conformation with dilated portions named podoms (containing mitochondria, endoplasmic reticulum and caveolae) and very thin segments (below resolving power of light microscopy), called podomers. To show the real 3D architecture of TC network, we used the most advanced available electron microscope technology: focused ion beam scanning electron microscopy (FIB-SEM) tomography. Generally, 3D reconstruction of dermal TCs by FIB-SEM tomography revealed the existence of Tps with various conformations: (i) long, flattened irregular veils (ribbon-like segments) with knobs, corresponding to podoms, and (ii) tubular structures (podomers) with uneven calibre because of irregular dilations (knobs) – the podoms. FIB-SEM tomography also showed numerous extracellular vesicles (diameter 438.6 ± 149.1 nm, n = 30) released by a human dermal TC. Our data might be useful for understanding the role(s) of TCs in intercellular signalling and communication, as well as for comprehension of pathologies like scleroderma, multiple sclerosis, psoriasis, etc. PMID:25823591

Fabrication of nano ZrO2 dispersed novel W79Ni10Ti5Nb5 alloy by mechanical alloying and pressureless sintering

NASA Astrophysics Data System (ADS)

Sahoo, R. R.; Patra, A.; Karak, S. K.

2017-02-01

A high energy planetary ball-mill was employed to synthesize tungsten (W) based alloy with nominal composition of W79Ni10Ti5Nb5(ZrO2)1 (in wt. %) for 20 h with chrome steel as grinding media, toluene as process control agent (PCA) along with compaction at 500 MPa pressure for 5 mins and sintering at 1500°C for 2 h using Ar atmosphere. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), elemental mapping and Transmission electron microscopy (TEM) was used to study the phase formation, microstructure of both milled powder and consolidated alloy. The crystallite size of W in W79Ni10Ti5Nb5(ZrO2)1 powder was 37 nm, 14.7 nm at 10 h and 20 h of milling respectively and lattice strain enhances to 0.54% at 20 h of milling. The crystallite size reduction is more at 10 h of milling and the rate drop beyond 10 to 20 h of milling. The intense improvement in dislocation density was evident upto 10 h of milling and the rate decreases between 10 to 20 h of milling. Increase in the lattice parameter of tungsten in W79Ni10Ti5Nb5(ZrO2)1 alloy upto 0.09% was observed at 10 h of milling owing to severe stress assisted deformation followed by contraction upto 0.07% at 20 h of milling due to formation of solid solution. The large spherical particles at 0 h of milling transformed to elongated shape at 10 h of milling and finer morphology at 20 h of milling. The average particle size reduced from 100 µm to 4.5 µm with the progress of milling from 0 to 20 h. Formation of fine polycrystallites of W was revealed by bright field TEM analysis and the observed crystallite size from TEM study was well supported by the evaluated crystallite size from XRD. XRD pattern and SEM micrograph of sintered alloy revealed the formation of NbNi, Ni3Ti intermetallic phases. Densification of 91.5% was attained in the 20 h milled and sintered alloy. Mechanical behaviour of the sintered product was evaluated by hardness and wear study. W79Ni10Ti5Nb5(ZrO2)1 alloy showed increase in hardness with decreasing load. The wear rate increases with increasing load due to higher abrasion effect at higher load.

Multipulse nanosecond laser irradiation of silicon for the investigation of surface morphology and photoelectric properties

NASA Astrophysics Data System (ADS)

Sardar, Maryam; Chen, Jun; Ullah, Zaka; Jelani, Mohsan; Tabassum, Aasma; Cheng, Ju; Sun, Yuxiang; Lu, Jian

2017-12-01

We irradiate the single crystal boron-doped silicon (Si) with different number of laser pulses at constant fluence (7.5 J cm-2) in ambient air using Nd:YAG laser and examine its surface morphology and photoelectric properties in details. The results obtained from optical micrographs reveal the increase in heat affected zone (HAZ) and melted area of laser irradiated Si with increasing number of laser pulses. The SEM micrographs evidence the formation of various surface morphologies like laser induced periodic surface structures, crater, microcracks, clusters, cavities, pores, trapped bubbles, nucleation sites, micro-bumps, redeposited material and micro- and nano-particles on the surface of irradiated Si. The surface profilometry analysis informs that the depth of crater is increased with increase in number of incident laser pulses. The spectroscopic ellipsometry reveals that the multipulse irradiation of Si changes its optical properties (refractive index and extinction coefficient). The current-voltage (I-V) characteristic curves of laser irradiated Si show that although the multipulse laser irradiation produces considerable number of surface defects and damages, the electrical properties of Si are well sustained after the multipulse irradiation. The current findings suggest that the multipulse irradiation can be an effective way to tune the optical properties of Si for the fabrication of wide range of optoelectronic devices.

Ex vivo confocal microscopy: an emerging technique in dermatology

PubMed Central

Perrot, Jean Luc; Labeille, Bruno; Cambazard, Frédéric; Rubegni, Pietro

2018-01-01

This review aims to give an overview of the current available applications of ex vivo confocal microscopy (EVCM) in dermatology. EVCM is a relatively new imaging technique that allows microscopic examination of freshly excised unfixed tissue. It enables a rapid examination of the skin sample directly in the surgery room and thus represents an alternative to the intraoperative micrographic control of the surgical margins of cutaneous tumors by standard microscopic examination on cryopreserved sections during Mohs surgery. Although this technique has mainly been developed for the margin’s control of basal cell carcinoma, many other skin tumors have been studied, including melanoma. Use of EVCM is continuing to evolve, and many possible applications are under investigation, such as the study of nails and hair diseases and the diagnosis of skin infections. PMID:29785327

Single clay sheets inside electrospun polymer nanofibers

NASA Astrophysics Data System (ADS)

Sun, Zhaohui

2005-03-01

Nanofibers were prepared from polymer solution with clay sheets by electrospinning. Plasma etching, as a well controlled process, was used to supply electrically excited gas molecules from a glow discharge. To reveal the structure and arrangement of clay layers in the polymer matrix, plasma etching was used to remove the polymer by controlled gasification to expose the clay sheets due to the difference in reactivity. The shape, flexibility, and orientation of clay sheets were studied by transmission and scanning electron microscopy. Additional quantitative information on size distribution and degree of exfoliation of clay sheets were obtained by analyzing electron micrograph of sample after plasma etching. Samples in various forms including fiber, film and bulk, were thinned by plasma etching. Morphology and dispersion of inorganic fillers were studied by electron microscopy.

Optimization study of direct morphology observation by cold field emission SEM without gold coating.

PubMed

He, Dan; Fu, Cheng; Xue, Zhigang

2018-06-01

Gold coating is a general operation that is generally applied on non-conductive or low conductive materials, during which the morphology of the materials can be examined by scanning electron microscopy (SEM). However, fatal deficiencies in the materials can result in irreversible distortion and damage. The present study directly characterized different low conductive materials such as hydroxyapatite, modified poly(vinylidene fluoride) (PVDF) fiber, and zinc oxide nanopillar by cold field emission scanning electron microscopy (FE-SEM) without a gold coating. According to the characteristics of the low conductive materials, various test conditions, such as different working signal modes, accelerating voltages, electron beam spots, and working distances, were characterized to determine the best morphological observations of each sample. Copyright © 2018 Elsevier Ltd. All rights reserved.

Applications of synchrotron x-ray diffraction topography to fractography

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

Bilello, J.C.

1983-01-01

Fractographs have been taken using a variety of probes each of which produces different types of information. Methods which have been used to examine fracture surfaces include: (a) optical microscopy, particularly interference contrast methods, (b) scanning electron microscopy (SEM), (c) SEM with electron channelling, (d) SEM with selected-area electron channelling, (e) Berg-Barrett (B-B) topography, and now (f) synchrotron x-radiation fractography (SXRF). This review concentrated on the role that x-ray methods can play in such studies. In particular, the ability to nondestructively assess the subsurface microstructure associated with the fracture to depths of the order of 5 to 10 ..mu..m becomesmore » an important attribute for observations of a large class of semi-brittle metals, semiconductors and ceramics.« less

The effect of home bleaching agents on the surface roughness of five different composite resins: A SEM evaluation.

PubMed

Cengiz, Esra; Kurtulmus-Yilmaz, Sevcan; Ulusoy, Nuran; Deniz, Sule Tugba; Yuksel-Devrim, Ece

2016-05-01

The aim of this study was to investigate the effect of hydrogen peroxide (HP) and carbamide peroxide (CP) on the surface roughness of five different composite resins using profilometer and scanning electron microscope (SEM). Thirty-six specimens (1 mm thick, 10 mm in diameter) of five composite resins were fabricated. Each composite group was equally divided into three subgroups as control, CP and HP. In control group, specimens were stored in daily refreshed distilled water during the 14-day testing period. In other groups, 10% HP (Opalescence Treswhite) and 10% CP (Opalescence PF) were applied and surface roughness values (Ra) of each specimen were measured with a profilometer at the end of 14 days. Additionally, SEM analysis was performed to evaluate the surface deformations of composite resins. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests. Ra values of composite groups exposed to bleaching agents were statistically higher than control group (p < 0.05). There was no significant difference between Ra values after HP and CP application within each composite group while SEM micrographs showed higher surface alterations at HP group compared to CP. Among the composite resins tested, Ceram-X Mono revealed the lowest Ra values after CP and HP applications as seen at SEM images. Home bleaching agents increased the surface roughness of all composites. Except CP applied Ceram-X mono specimens, Ra values of all composite resins evaluated in this study exceeded the critical limit of 0.2 μm. Ceram-X mono was the least affected composite material after bleaching application. SCANNING 38:277-283, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

Direct observation for atomically flat and ordered vertical {111} side-surfaces on three-dimensionally figured Si(110) substrate using scanning tunneling microscopy

NASA Astrophysics Data System (ADS)

Yang, Haoyu; Hattori, Azusa N.; Ohata, Akinori; Takemoto, Shohei; Hattori, Ken; Daimon, Hiroshi; Tanaka, Hidekazu

2017-11-01

A three-dimensional Si{111} vertical side-surface structure on a Si(110) wafer was fabricated by reactive ion etching (RIE) followed by wet-etching and flash-annealing treatments. The side-surface was studied with scanning tunneling microscopy (STM) in atomic scale for the first time, in addition to atomic force microscopy (AFM), scanning electron microscopy (SEM), and low-energy electron diffraction (LEED). AFM and SEM showed flat and smooth vertical side-surfaces without scallops, and STM proved the realization of an atomically-flat 7 × 7-reconstructed structure, under optimized RIE and wet-etching conditions. STM also showed that a step-bunching occurred on the produced {111} side-surface corresponding to a reversely taped side-surface with a tilt angle of a few degrees, but did not show disordered structures. Characteristic LEED patterns from both side- and top-reconstructed surfaces were also demonstrated.

Gaps analysis for CD metrology beyond the 22nm node

NASA Astrophysics Data System (ADS)

Bunday, Benjamin; Germer, Thomas A.; Vartanian, Victor; Cordes, Aaron; Cepler, Aron; Settens, Charles

2013-04-01

This paper will examine the future for critical dimension (CD) metrology. First, we will present the extensive list of applications for which CD metrology solutions are needed, showing commonalities and differences among the various applications. We will then report on the expected technical limits of the metrology solutions currently being investigated by SEMATECH and others in the industry to address the metrology challenges of future nodes, including conventional CD scanning electron microscopy (CD-SEM) and optical critical dimension (OCD) metrology and new potential solutions such as He-ion microscopy (HeIM, sometimes elsewhere referred to as HIM), CD atomic force microscopy (CD-AFM), CD small-angle x-ray scattering (CD-SAXS), high-voltage scanning electron microscopy (HV-SEM), and other types. A technical gap analysis matrix will then be demonstrated, showing the current state of understanding of the future of the CD metrology space.

Three-dimensional textures and defects of soft material layering revealed by thermal sublimation.

PubMed

Yoon, Dong Ki; Kim, Yun Ho; Kim, Dae Seok; Oh, Seong Dae; Smalyukh, Ivan I; Clark, Noel A; Jung, Hee-Tae

2013-11-26

Layering is found and exploited in a variety of soft material systems, ranging from complex macromolecular self-assemblies to block copolymer and small-molecule liquid crystals. Because the control of layer structure is required for applications and characterization, and because defects reveal key features of the symmetries of layered phases, a variety of techniques have been developed for the study of soft-layer structure and defects, including X-ray diffraction and visualization using optical transmission and fluorescence confocal polarizing microscopy, atomic force microscopy, and SEM and transmission electron microscopy, including freeze-fracture transmission electron microscopy. Here, it is shown that thermal sublimation can be usefully combined with such techniques to enable visualization of the 3D structure of soft materials. Sequential sublimation removes material in a stepwise fashion, leaving a remnant layer structure largely unchanged and viewable using SEM, as demonstrated here using a lamellar smectic liquid crystal.

Study of nanoscale structural biology using advanced particle beam microscopy

NASA Astrophysics Data System (ADS)

Boseman, Adam J.

This work investigates developmental and structural biology at the nanoscale using current advancements in particle beam microscopy. Typically the examination of micro- and nanoscale features is performed using scanning electron microscopy (SEM), but in order to decrease surface charging, and increase resolution, an obscuring conductive layer is applied to the sample surface. As magnification increases, this layer begins to limit the ability to identify nanoscale surface structures. A new technology, Helium Ion Microscopy (HIM), is used to examine uncoated surface structures on the cuticle of wild type and mutant fruit flies. Corneal nanostructures observed with HIM are further investigated by FIB/SEM to provide detailed three dimensional information about internal events occurring during early structural development. These techniques are also used to reconstruct a mosquito germarium in order to characterize unknown events in early oogenesis. Findings from these studies, and many more like them, will soon unravel many of the mysteries surrounding the world of developmental biology.

Chapter 14: Electron Microscopy on Thin Films for Solar Cells

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

Romero, Manuel; Abou-Ras, Daniel; Nichterwitz, Melanie

2016-07-22

This chapter overviews the various techniques applied in scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and highlights their possibilities and also limitations. It gives the various imaging and analysis techniques applied on a scanning electron microscope. The chapter shows that imaging is divided into that making use of secondary electrons (SEs) and of backscattered electrons (BSEs), resulting in different contrasts in the images and thus providing information on compositions, microstructures, and surface potentials. Whenever aiming for imaging and analyses at scales of down to the angstroms range, TEM and its related techniques are appropriate tools. In many cases,more » also SEM techniques provide the access to various material properties of the individual layers, not requiring specimen preparation as time consuming as TEM techniques. Finally, the chapter dedicates to cross-sectional specimen preparation for electron microscopy. The preparation decides indeed on the quality of imaging and analyses.« less

Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography

NASA Astrophysics Data System (ADS)

Jesse, S.; Chi, M.; Belianinov, A.; Beekman, C.; Kalinin, S. V.; Borisevich, A. Y.; Lupini, A. R.

2016-05-01

Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called “big-data” methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. However, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy.

The combination of scanning electron and scanning probe microscopy

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

Sapozhnikov, I. D.; Gorbenko, O. M., E-mail: gorolga64@gmail.com; Felshtyn, M. L.

2016-06-17

We suggest the SPM module to combine SEM and SPM methods for studying surfaces. The module is based on the original mechanical moving and scanning system. The examples of studies of the steel surface microstructure in both SEM and SPM modes are presented.

Image contrast enhancement of Ni/YSZ anode during the slice-and-view process in FIB-SEM.

PubMed

Liu, Shu-Sheng; Takayama, Akiko; Matsumura, Syo; Koyama, Michihisa

2016-03-01

Focused ion beam-scanning electron microscopy (FIB-SEM) is a widely used and easily operational equipment for three-dimensional reconstruction with flexible analysis volume. It has been using successfully and increasingly in the field of solid oxide fuel cell. However, the phase contrast of the SEM images is indistinct in many cases, which will bring difficulties to the image processing. Herein, the phase contrast of a conventional Ni/yttria stabilized zirconia anode is tuned in an FIB-SEM with In-Lens secondary electron (SE) and backscattered electron detectors. Two accessories, tungsten probe and carbon nozzle, are inserted during the observation. The former has no influence on the contrast. When the carbon nozzle is inserted, best and distinct contrast can be obtained by In-Lens SE detector. This method is novel for contrast enhancement. Phase segmentation of the image can be automatically performed. The related mechanism for different images is discussed. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Analysis of leaf surfaces using scanning ion conductance microscopy.

PubMed

Walker, Shaun C; Allen, Stephanie; Bell, Gordon; Roberts, Clive J

2015-05-01

Leaf surfaces are highly complex functional systems with well defined chemistry and structure dictating the barrier and transport properties of the leaf cuticle. It is a significant imaging challenge to analyse the very thin and often complex wax-like leaf cuticle morphology in their natural state. Scanning electron microscopy (SEM) and to a lesser extent Atomic force microscopy are techniques that have been used to study the leaf surface but their remains information that is difficult to obtain via these approaches. SEM is able to produce highly detailed and high-resolution images needed to study leaf structures at the submicron level. It typically operates in a vacuum or low pressure environment and as a consequence is generally unable to deal with the in situ analysis of dynamic surface events at submicron scales. Atomic force microscopy also possess the high-resolution imaging required and can follow dynamic events in ambient and liquid environments, but can over exaggerate small features and cannot image most leaf surfaces due to their inherent roughness at the micron scale. Scanning ion conductance microscopy (SICM), which operates in a liquid environment, provides a potential complementary analytical approach able to address these issues and which is yet to be explored for studying leaf surfaces. Here we illustrate the potential of SICM on various leaf surfaces and compare the data to SEM and atomic force microscopy images on the same samples. In achieving successful imaging we also show that SICM can be used to study the wetting of hydrophobic surfaces in situ. This has potentially wider implications than the study of leaves alone as surface wetting phenomena are important in a range of fundamental and applied studies. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Detailed methodology for high resolution scanning electron microscopy (SEM) of murine malaria parasitized-erythrocytes.

PubMed

Hayakawa, Eri H; Matsuoka, Hiroyuki

2016-10-01

Scanning electron microscopy (SEM) is a powerful tool used to investigate object surfaces and has been widely applied in both material science and biology. With respect to the study of malaria, SEM revealed that erythrocytes infected with Plasmodium falciparum, a human parasite, display 'knob-like' structures on their surface comprising parasitized proteins. However, detailed methodology for SEM studies of malaria parasites is lacking in the literature making such studies challenging. Here, we provide a step-by-step guide to preparing Plasmodium-infected erythrocytes from two mouse strains for SEM analysis with minimal structural deterioration. We tested three species of murine malaria parasites, P. berghei, P. yoelii, and P. chabaudi, as well as non-parasitized human erythrocytes and P. falciparum-infected erythrocytes for comparisons. Our data demonstrated that the surface structures of parasitized erythrocytes between the three species of murine parasites in the two different strains of mice were indistinguishable and no surface alterations were observed in P. falciparum-erythrocytes. Our SEM observations contribute towards an understanding of the molecular mechanisms of parasite maturation in the erythrocyte cytoplasm and, along with future studies using our detailed methodology, may help to gain insight into the clinical phenomena of human malaria. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Synthesis and electrochemical studies on Al 2O 3 coated LiNi 0.5Co 0.44Fe 0.06VO 4 for lithium ion batteries

NASA Astrophysics Data System (ADS)

Fey, George Ting-Kuo; Muralidharan, Pandurangan; Cho, Yung-Da

LiNi 0.5Co 0.44Fe 0.06VO 4 cathode material has been synthesized by a citric acid:polyethylene glycol polymeric method at 723 K for 5 h in air. The surface of the LiNi 0.5Co 0.44Fe 0.06VO 4 was coated with various wt.% of Al 2O 3 by a wet chemical procedure and heat treated 873 K for 2 h in air. The samples were characterized by XRD, FTIR, SEM, and TEM techniques. XRD patterns expose that the complete crystalline phase occurred at 723 K and there was no indication of new peaks for the coated samples. FTIR spectra show that the complete removal of organic residues and the formation of LiNi 0.5Co 0.44Fe 0.06VO 4. TG/DTGA results reveal that the formation of LiNi 0.5Co 0.44Fe 0.06VO 4 occurred between 480 and 670 K and the complete crystalline occurred at 723 K. SEM micrographs show the various morphological stages of the polymeric intermediates. TEM micrographs of the pristine LiNi 0.5Co 0.44Fe 0.06VO 4 reveal that the particle size ranged from 130 to 150 nm and Al 2O 3 coating on the fine particles was compact and had an average thickness of about 15 nm. The charge-discharge experiments were carried out between 2.8 and 4.9 V (versus Li) at a current rate of 0.15 C. The 1.0 wt.% Al 2O 3 coated sample had the best electrochemical performance, with an initial capacity of 65 mAh g -1 and capacity retention of 60% after 50 cycles. The electrochemical impedance behavior suggests that the failure of pristine cathode performance is associated with an increase in the impedance growth on the surface of the cathode material upon continuous cycling.

Field emission scanning electron microscopy (FE-SEM) as an approach for nanoparticle detection inside cells.

PubMed

Havrdova, M; Polakova, K; Skopalik, J; Vujtek, M; Mokdad, A; Homolkova, M; Tucek, J; Nebesarova, J; Zboril, R

2014-12-01

When developing new nanoparticles for bio-applications, it is important to fully characterize the nanoparticle's behavior in biological systems. The most common techniques employed for mapping nanoparticles inside cells include transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). These techniques entail passing an electron beam through a thin specimen. STEM or TEM imaging is often used for the detection of nanoparticles inside cellular organelles. However, lengthy sample preparation is required (i.e., fixation, dehydration, drying, resin embedding, and cutting). In the present work, a new matrix (FTO glass) for biological samples was used and characterized by field emission scanning electron microscopy (FE-SEM) to generate images comparable to those obtained by TEM. Using FE-SEM, nanoparticle images were acquired inside endo/lysosomes without disruption of the cellular shape. Furthermore, the initial steps of nanoparticle incorporation into the cells were captured. In addition, the conductive FTO glass endowed the sample with high stability under the required accelerating voltage. Owing to these features of the sample, further analyses could be performed (material contrast and energy-dispersive X-ray spectroscopy (EDS)), which confirmed the presence of nanoparticles inside the cells. The results showed that FE-SEM can enable detailed characterization of nanoparticles in endosomes without the need for contrast staining or metal coating of the sample. Images showing the intracellular distribution of nanoparticles together with cellular morphology can give important information on the biocompatibility and demonstrate the potential of nanoparticle utilization in medicine. Copyright © 2014 Elsevier Ltd. All rights reserved.

Anticorrosion Coating using Olea sp. Leaves Extract

NASA Astrophysics Data System (ADS)

Ikhmal, W. M. K. W. M.; Yasmin, M. Y. N.; Fazira, M. F. M.; Rafizah, W. A. W.; Nik, W. B. Wan; Sabri, M. G. M.

2018-04-01

Olive leaves extract (OLE) was evaluated as green corrosion inhibitor for stainless steel grade 316L (SS316L) in several media using scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The Fourier Transform Infrared (FTIR) spectroscopy results reveals several active compound indicated by O-H stretch, C=O stretch, C-OH stretch and C-N stretch which can be attributed to oleuropein and hydroxtyrosol acting as the main inhibiting sources for corrosion. The results obtained also show the inhibition efficiency of OLE increase with the increase of OLE concentration. Through its inhibitive action elucidate from the electrochemical analysis, the extract was found to act as a mixed type inhibitor. Micrographs by SEM showed that the surface of steel which has been coated with 0% and 20% of OLE coating extract possess a lot of pin holes or pores while the steel with 10% of OLE coating extract shows the surface has multiple cracks. This study clearly shows the efficiency of OLE as anticorrosion coating for control of stainless steel in marine application.

A novel biphasic calcium phosphate derived from fish otoliths

NASA Astrophysics Data System (ADS)

Montañez-Supelano, N. D.; Sandoval-Amador, A.; Estupiñan-Durán, H. A.; Y Peña-Ballesteros, D.

2017-12-01

Calcium phosphates are bioceramics that have been widely used as bone substitutes because they encourage the formation of bone on their surface and can improve the healing of the bone. Hydroxyapatite HA (calcium/phosphorus ratio of 1.67) and tricalcium phosphate TCP (calcium/phosphorus ratio of 1.50) are the most common calcium phosphates. Natural materials have begun to be tested to make HA or TCP such as shells of cardiidae (family of mollusks) and eggshells. The calcium phosphate obtained has a high ability to precipitate apatite. In this work, the mixed phase ceramic of beta-Tri-calcium phosphate / hydroxyapatite (β-TCP/HA) was synthesized by aqueous precipitation from fish otoliths, which are monomineralic species composed of aragonite. Otoliths of the specie Plagioscion squamosissimus, commonly called the river croaker, were used. Techniques such as DRX, Raman spectroscopy and SEM-EDS were used to characterize the raw material and the obtained material. X-ray diffraction analysis revealed the presence of two crystalline phases of calcium phosphates with 86.2% crystallinity. SEM micrographs showed agglomeration of particles with porous structure and submicron particle sizes.

The Microstructure and Physical Properties of Incinerated Paper-Cullet-Clay Ceramics

NASA Astrophysics Data System (ADS)

Sahar, M. R.; Hamzah, K.; Rohani, M. S.; Samah, K. A.; Razi, M. M.

A series of ceramic based on (x) incinerated recycle paper - (80-x) cullet - 20 Kaolin clay (where 10×45 wt%) has successfully been made by slip casting technique followed by sintering at 1000 °C. The actual composition of ceramic is analyzed using Energy Dispersive of X-Ray (EDAX) while the phase existence is determined using X-Ray Diffraction (XRD) technique. Their microstructural morphology is observed under Scanning Electron Microscope (SEM) and the physical properties are measured in term of their thermal shrinkage and hardness. It is found that the ceramic contain mostly of Silica and the phase is dominated by the existence of Quartz (SiO2), Wollastonite (CaSiO3) and Anorthite (Ca(Al2SiO8)). The SEM micrograph shows that the morphology is dominated by the existence of granular structure, and then become smoother as the cullet level is further increased. It is also found out that the thermal shrinkage is in the range 18% - 6.5% while the hardness is in the range of 152MPa- 1.463 GPa depending on composition.

Micro-mechanics of ionic electroactive polymer actuators

NASA Astrophysics Data System (ADS)

Punning, Andres; Põldsalu, Inga; Kaasik, Friedrich; Vunder, Veiko; Aabloo, Alvo

2015-04-01

Commonly, modeling of the bending behavior of the ionic electroactive polymer (IEAP) actuators is based on the classical mechanics of cantilever beam. It is acknowledged, that the actuation of the ionic electroactive polymer (IEAP) actuators is symmetric about the centroid - the convex side of the actuator is expanding and the concave side is contracting for exactly the same amount, while the thickness of the actuator remains invariant. Actuating the IEAP actuators and sensors under scanning electron microscope (SEM), in situ, reveals that for some types of them this approach is incorrect. Comparison of the SEM micrographs using the Digital Image Correction (DIC) method results with the precise strain distribution of the IEAP actuators in two directions: in the axial direction, and in the direction of thickness. This information, in turn, points to the physical processes taking place within the electrodes as well as membrane of the trilayer laminate of sub-millimeter thickness. Comparison of the EAP materials, engaged as an actuator as well as a sensor, reveals considerable differences between the micro-mechanics of the two modes.

How Hedstrom files fail during clinical use? A retrieval study based on SEM, optical microscopy and micro-XCT analysis.

PubMed

Zinelis, Spiros; Al Jabbari, Youssef S

2018-05-01

This study was conducted to evaluate the failure mechanism of clinically failed Hedstrom (H)-files. Discarded H-files (n=160) from #8 to #40 ISO sizes were collected from different dental clinics. Retrieved files were classified according to their macroscopic appearance and they were investigated under scanning electron microscopy (SEM) and X-ray micro-computed tomography (mXCT). Then the files were embedded in resin along their longitudinal axis and after metallographic grinding and polishing, studied under an incident light microscope. The macroscopic evaluation showed that small ISO sizes (#08-#15) failed by extensive plastic deformation, while larger sizes (≥#20) tended to fracture. Light microscopy and mXCT results coincided showing that unused and plastically deformed files were free of internal defects, while fractured files demonstrate the presence of intense cracking in the flute region. SEM analysis revealed the presence of striations attributed to the fatigue mechanism. Secondary cracks were also identified by optical microscopy and their distribution was correlated to fatigue under bending loading. Experimental results demonstrated that while overloading of cutting instruments is the predominating failure mechanism of small file sizes (#08-#15), fatigue should be considered the fracture mechanism for larger sizes (≥#20).

An inexpensive approach for bright-field and dark-field imaging by scanning transmission electron microscopy in scanning electron microscopy.

PubMed

Patel, Binay; Watanabe, Masashi

2014-02-01

Scanning transmission electron microscopy in scanning electron microscopy (STEM-in-SEM) is a convenient technique for soft materials characterization. Various specimen-holder geometries and detector arrangements have been used for bright-field (BF) STEM-in-SEM imaging. In this study, to further the characterization potential of STEM-IN-SEM, a new specimen holder has been developed to facilitate direct detection of BF signals and indirect detection of dark-field (DF) signals without the need for substantial instrument modification. DF imaging is conducted with the use of a gold (Au)-coated copper (Cu) plate attached to the specimen holder which directs highly scattered transmitted electrons to an off-axis yttrium-aluminum-garnet (YAG) detector. A hole in the copper plate allows for BF imaging with a transmission electron (TE) detector. The inclusion of an Au-coated Cu plate enhanced DF signal intensity. Experiments validating the acquisition of true DF signals revealed that atomic number (Z) contrast may be achieved for materials with large lattice spacing. However, materials with small lattice spacing still exhibit diffraction contrast effects in this approach. The calculated theoretical fine probe size is 1.8 nm. At 30 kV, in this indirect approach, DF spatial resolution is limited to 3.2 nm as confirmed experimentally.

Transmission electron microscope studies of extraterrestrial materials

NASA Technical Reports Server (NTRS)

Keller, Lindsay P.

1995-01-01

Transmission Electron Microscopy, X-Ray spectrometry and electron-energy-loss spectroscopy are used to analyse carbon in interplanetary dust particles. Optical micrographs are shown depicting cross sections of the dust particles embedded in sulphur. Selected-area electron diffraction patterns are shown. Transmission Electron Microscope specimens of lunar soil were prepared using two methods: ion-milling and ultramicrotomy. A combination of high resolution TEM imaging and electron diffraction is used to characterize the opaque assemblages. The opaque assemblages analyzed in this study are dominated by ilmenite with lesser rutile and spinel exsolutions, and traces of Fe metal.

Amorphization induced by focused ion beam milling in metallic and electronic materials.

PubMed

Huh, Yoon; Hong, Ki Jung; Shin, Kwang Soo

2013-08-01

Focused ion beam (FIB) milling using high-energy gallium ions is widely used in the preparation of specimens for transmission electron microscopy (TEM). However, the energetic ion beam induces amorphization on the edge of specimens during milling, resulting in a mischievous influence on the clearness of high-quality transmission electron micrographs. In this work, the amorphization induced by the FIB milling was investigated by TEM for three kinds of materials, metallic materials in bulk shape, and semiconductive and electronic ceramic materials as a substrate for the deposition of thin films.

Structural, morphological and optical properties of chromium oxide nanoparticles

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

Babukutty, Blessy; Parakkal, Fasalurahman; Nair, Swapna S., E-mail: swapna.s.nair@gmail.com

2015-06-24

Chromium oxide nanoparticles are synthesized by reduction route from chloride precursors with surfactant, trioctylphosphine oxide (TOPO). Structural and morphological characterization are analyzed using X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Transmission Electron micrographs show that the average grain size lies in the range 5nm to 10nm. Optical characterization has been done by UV-VIS spectrophotometer. Distinct optical absorptions of Cr{sup 3+} ions show hinting towards the presence of Cr{sub 2}O{sub 3}. Presence of oxygen is also confirmed from Electron Energy Loss Spectroscopy (EELS) studies.

Ecology and thermal inactivation of microbes in and on interplanetary space vehicle components. [examined with a scanning electron microscope

NASA Technical Reports Server (NTRS)

Campbell, J. E.

1974-01-01

The uses of scanning electron microscopy in assessing changes that occur in spores exposed to wet and dry heat cycles at elevated temperatures were examined. Several species of Bacillus and other nonspore-forming species of organisms were used for the experiment. Surface morphology of viable and nonviable organisms was clearly detectable by this method, making it a potentially useful technique for investigating microbial inactivation on space vehicle surfaces and components. Micrographs of the spores and bacterial cells are provided.

Hard X-ray full field microscopy and magnifying microtomography using compound refractive lenses

NASA Astrophysics Data System (ADS)

Schroer, Christian G.; Günzler, Til Florian; Benner, Boris; Kuhlmann, Marion; Tümmler, Johannes; Lengeler, Bruno; Rau, Christoph; Weitkamp, Timm; Snigirev, Anatoly; Snigireva, Irina

2001-07-01

For hard X-rays, parabolic compound refractive lenses (PCRLs) are genuine imaging devices like glass lenses for visible light. Based on these new lenses, a hard X-ray full field microscope has been constructed that is ideally suited to image the interior of opaque samples with a minimum of sample preparation. As a result of a large depth of field, CRL micrographs are sharp projection images of most samples. To obtain 3D information about a sample, tomographic techniques are combined with magnified imaging.

Structural characterization and gas reactions of small metal particles by high resolution in-situ TEM (Transmission Electron Microscopy) and TED (Transmission Electron Diffraction)

NASA Technical Reports Server (NTRS)

Heinemann, K.

1987-01-01

The detection and size analysis of small metal particles supported on amorphous substrates becomes increasingly difficult when the particle size approaches that of the phase contrast background structures of the support. An approach of digital image analysis, involving Fourier transformation of the original image, filtering, and image reconstruction was studied with respect to the likelihood of unambiguously detecting particles of less than 1 nm diameter on amorphous substrates from a single electron micrograph.

An analysis of the circuitry of the visual pathway of the lateral eye of limullus

NASA Technical Reports Server (NTRS)

Sjoestrand, F. S.

1970-01-01

The methodology is discussed for three-dimensional analysis of the nervous system on the basis of electron micrographs of serial sections. An analysis is presented of a part of the circuitry of the rabbit retina. In addition, some exploratory work is reported with respect to the visual cortex of the cat brain. A proper technique for preservation of the visual cortex was worked out and a technique to localize microelectrode tips in the tissue in connection with electron microscopy was partially worked out.

GUIDELINES FOR THE APPLICATION OF SEM/EDX ANALYTICAL TECHNIQUES FOR FINE AND COARSE PM SAMPLES

EPA Science Inventory

Scanning Electron Microscopy (SEM) coupled with Energy-Dispersive X-ray analysis (EDX) is a powerful tool in the characterization and source apportionment of environmental particulate matter (PM), providing size, chemistry, and morphology of particles as small as a few tenths ...

A Barcoding Strategy Enabling Higher-Throughput Library Screening by Microscopy.

PubMed

Chen, Robert; Rishi, Harneet S; Potapov, Vladimir; Yamada, Masaki R; Yeh, Vincent J; Chow, Thomas; Cheung, Celia L; Jones, Austin T; Johnson, Terry D; Keating, Amy E; DeLoache, William C; Dueber, John E

2015-11-20

Dramatic progress has been made in the design and build phases of the design-build-test cycle for engineering cells. However, the test phase usually limits throughput, as many outputs of interest are not amenable to rapid analytical measurements. For example, phenotypes such as motility, morphology, and subcellular localization can be readily measured by microscopy, but analysis of these phenotypes is notoriously slow. To increase throughput, we developed microscopy-readable barcodes (MiCodes) composed of fluorescent proteins targeted to discernible organelles. In this system, a unique barcode can be genetically linked to each library member, making possible the parallel analysis of phenotypes of interest via microscopy. As a first demonstration, we MiCoded a set of synthetic coiled-coil leucine zipper proteins to allow an 8 × 8 matrix to be tested for specific interactions in micrographs consisting of mixed populations of cells. A novel microscopy-readable two-hybrid fluorescence localization assay for probing candidate interactions in the cytosol was also developed using a bait protein targeted to the peroxisome and a prey protein tagged with a fluorescent protein. This work introduces a generalizable, scalable platform for making microscopy amenable to higher-throughput library screening experiments, thereby coupling the power of imaging with the utility of combinatorial search paradigms.

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

Evaluation of hemocompatibility and in vitro immersion on microwave-assisted hydroxyapatite-alumina nanocomposites.

PubMed

Radha, G; Balakumar, S; Venkatesan, Balaji; Vellaichamy, Elangovan

2015-05-01

This study reports the microwave-assisted synthesis and characterization of nHAp (nano-hydroxyapatite)-alumina composites. The crystalline phase and interaction of alumina with nHAp was analyzed using X-ray diffraction (XRD) and Raman microscopy analysis, respectively. High resolution transmission electron microscopy (HRTEM) micrographs exhibit morphological changes of nHAp composites with increasing alumina concentrations. Microhardness studies reveal the enhanced mechanical strength of nHAp10 and nHAp20 nanocomposites than pure nHAp. In vitro bioactivity of the nanocomposites was studied by immersing samples in simulated body fluid (Hank's solution) for 21 days. The surface of biomineralized samples were analyzed using field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDX). Hemolytic assay revealed acceptable compatibility for varying concentrations of all the samples. Cell proliferation assay was systematically investigated for 1 day and 3 days on Saos-2 osteoblast-like cell lines and it was found that nHAp nanocomposites improved the proliferation. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

Using simulated fluorescence cell micrographs for the evaluation of cell image segmentation algorithms.

PubMed

Wiesmann, Veit; Bergler, Matthias; Palmisano, Ralf; Prinzen, Martin; Franz, Daniela; Wittenberg, Thomas

2017-03-18

Manual assessment and evaluation of fluorescent micrograph cell experiments is time-consuming and tedious. Automated segmentation pipelines can ensure efficient and reproducible evaluation and analysis with constant high quality for all images of an experiment. Such cell segmentation approaches are usually validated and rated in comparison to manually annotated micrographs. Nevertheless, manual annotations are prone to errors and display inter- and intra-observer variability which influence the validation results of automated cell segmentation pipelines. We present a new approach to simulate fluorescent cell micrographs that provides an objective ground truth for the validation of cell segmentation methods. The cell simulation was evaluated twofold: (1) An expert observer study shows that the proposed approach generates realistic fluorescent cell micrograph simulations. (2) An automated segmentation pipeline on the simulated fluorescent cell micrographs reproduces segmentation performances of that pipeline on real fluorescent cell micrographs. The proposed simulation approach produces realistic fluorescent cell micrographs with corresponding ground truth. The simulated data is suited to evaluate image segmentation pipelines more efficiently and reproducibly than it is possible on manually annotated real micrographs.

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

Cooke, Gary A.; Pestovich, John A.; Huber, Heinz J.

This report presents the results for solid phase characterization (SPC) of solid samples removed from tank 241-C-108 (C-108) on August 12-13,2012, using the off-riser sampler. Samples were received at the 222-S Laboratory on August 13 and were described and photographed. The SPC analyses that were performed include scanning electron microscopy (SEM) using the ASPEX(R)l scanning electron microscope, X-ray diffraction (XRD) using the Rigaku(R) 2 MiniFlex X-ray diffractometer, and polarized light microscopy (PLM) using the Nikon(R) 3 Eclipse Pol optical microscope. The SEM is equipped with an energy dispersive X-ray spectrometer (EDS) to provide chemical information. Gary A. Cooke conducted themore » SEM analysis, John A. Pestovich performed the XRD analysis, and Dr. Heinz J. Huber performed the PLM examination. The results of these analyses are presented here.« less

Healing of broken multiwalled carbon nanotubes using very low energy electrons in SEM: a route toward complete recovery.

PubMed

Kulshrestha, Neha; Misra, Abhishek; Hazra, Kiran Shankar; Roy, Soumyendu; Bajpai, Reeti; Mohapatra, Dipti Ranjan; Misra, D S

2011-03-22

We report the healing of electrically broken multiwalled carbon nanotubes (MWNTs) using very low energy electrons (3-10 keV) in scanning electron microscopy (SEM). Current-induced breakdown caused by Joule heating has been achieved by applying suitably high voltages. The broken tubes were examined and exposed to electrons of 3-10 keV in situ in SEM with careful maneuvering of the electron beam at the broken site, which results in the mechanical joining of the tube. Electrical recovery of the same tube has been confirmed by performing the current-voltage measurements after joining. This easy approach is directly applicable for the repairing of carbon nanotubes incorporated in ready devices, such as in on-chip horizontal interconnects or on-tip probing applications, such as in scanning tunneling microscopy.

RBS, TEM and SEM Characterization of Gold Nanoclusters in TiO2(110)

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

Shutthanandan, V; Zhang, Yanwen; Wang, Chong M.

2004-05-01

Nucleation of gold nanoclusters in TiO2(110) single crystal using ion implantation and subsequent annealing were studied by Rutherford backscattering spectrometry /channeling (RBS/C), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Approximately 1000 Au2+/nm2 was implanted at room temperature in TiO2(110) substrates. TEM and SEM measurements revel that rounded nanoclusters were formed during the implantation. In contrast subsequent annealing in air for 10 hours at 1275 K promoted the formation of faceted (rectangular shaped) Au nano structures in TiO2. RBS channeling measurements further reveled that Au atoms randomly occupied in the host TiO2 lattice during the implantation. However, some ofmore » the gold atoms were moved into the Ti lattice position after annealing.« less

Advantages and Disadvantages of using a Focused Ion Beam to Prepare TEM Samples From Irradiated U-10Mo Monolithic Nuclear Fuel

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

B. D. Miller; J. Gan; J. Madden

2012-05-01

Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and focused ion beam (FIB) milling were performed on an irradiated U-10Mo monolithic fuel to understand its irradiation microstructure. This is the first reported TEM work of irradiated fuel sample prepared using a FIB. Advantages and disadvantages of using the FIB to create TEM samples from this irradiated fuel will be presented along with some results from the work. Sample preparation techniques used to create SEM and FIB samples from the brittle irradiated monolithic sample will also be discussed.

A new scanning electron microscopy approach to image aerogels at the nanoscale

NASA Astrophysics Data System (ADS)

Solá, F.; Hurwitz, F.; Yang, J.

2011-04-01

A new scanning electron microscopy (SEM) technique to image poor electrically conductive aerogels is presented. The process can be performed by non-expert SEM users. We showed that negative charging effects on aerogels can be minimized significantly by inserting dry nitrogen gas close to the region of interest. The process involves the local recombination of accumulated negative charges with positive ions generated from ionization processes. This new technique made possible the acquisition of images of aerogels with pores down to approximately 3 nm in diameter using a positively biased Everhart-Thornley (ET) detector.

Bioaccumulation and distribution of selenium in Enterococcus durans.

PubMed

Pieniz, Simone; Andreazza, Robson; Mann, Michele Bertoni; Camargo, Flávio; Brandelli, Adriano

2017-03-01

Selenium is an essential nutrient for all living organisms. Under appropriate conditions lactic acid bacteria (LAB) are capable for accumulating large amounts of trace elements, such as selenium, and incorporating them into organic compounds. In this study, the capacity of selenium bioaccumulation by Enterococcus durans LAB18s was evaluated. The distribution of organic selenium in selenium-enriched E. durans LAB18s biomass was analyzed, and the highest percentage of organic selenium was found in the fraction of total protein, followed by the fractions of polysaccharides and nucleic acids. When the protein fraction was obtained by different extractions (water, NaCl, ethanol and NaOH) it was demonstrated that alkali-soluble protein showed the higher Selenium content. Analysis of protein fractions by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed that selenium was present in the proteins ranging from 23 to 100kDa. The cells were analyzed by scanning electron microscopy (SEM); scanning electron microscopy/energy dispersive spectrometry (SEM/EDS) and transmission electron microscopy (TEM). SEM, TEM and SEM/EDS showed the morphology, the selenium particles bioaccumulated into and on the cells and the amounts of selenium present into the cells, respectively. Thus, the isolate E. durans LAB18s can be a promising probiotic to be used as selenium-enriched biomass in feed trials. Copyright © 2016 Elsevier GmbH. All rights reserved.

Anterior lens epithelium in intumescent white cataracts - scanning and transmission electron microscopy study.

PubMed

Andjelic, Sofija; Drašlar, Kazimir; Hvala, Anastazija; Hawlina, Marko

2016-02-01

Our purpose was to study the structure of the lens epithelial cells (LECs) of intumescent white cataracts (IC) in comparison with nuclear cataracts (NC) in order to investigate possible structural reasons for development of IC. The anterior lens capsule (aLC: basement membrane and associated LECs) were obtained from cataract surgery and prepared for scanning electron microscopy (SEM) and transmission electron microscopy (TEM). We observed by SEM that in IC, LEC swelling was pronounced with the clefts surrounding the groups of LECs. Another structural feature was spherical formations, that were observed on the apical side of LEC's, towards the fibre cell layer, both by SEM and TEM. Development of these structures, bulging out from the apical cell membrane of the LEC's and disrupting it, could be followed in steps towards the sphere formation. The degeneration of the lens epithelium and the structures of the aLC in IC similar to Morgagnian globules were also observed. None of these structural changes were observed in NC. We show by SEM and TEM that, in IC, LECs have pronounced structural features not observed in NC. This supports the hypothesis that the disturbed structure of LECs plays a role in water accumulation in the IC lens. We also suggest that, in IC, LECs produce bulging spheres that represent unique structures of degenerated material, extruded from the LEC.

A scanning electron microscopy study of early development in vitro of Contracaecum multipapillatum s.l. (Nematoda: Anisakidae) from a brown pelican (Pelecanus occidentalis) from the Gulf of California, Mexico.

PubMed

Molina-Fernández, Dolores; Valles-Vega, Isabel; Hernández-Trujillo, Sergio; Adroher, Francisco Javier; Benítez, Rocío

2017-10-01

Eggs obtained from the uteri of female nematodes, genetically identified as Contracaecum multipapillatum s.l., found in a brown pelican (Pelecanus occidentalis) from Bahía de La Paz, Gulf of California, Mexico, were used to study the early developmental stages of this anisakid by scanning electron microscopy (SEM). Egg dimensions were approximately 54 × 45 μm measured by SEM. Observation of the eggs revealed an outer surface of fibrous appearance. The newly hatched larvae were ensheathed and highly motile. Observation with SEM showed that the sheaths of the larvae were striated and revealed an excretory pore and a cleft near the anterior end of the sheath, presumably to facilitate the opening of the sheath for the emergence of the larva. The hatched larvae were placed in nutritive culture medium, where they grew within their sheath, some exsheathing completely 2 weeks later. The surface patterns of the sheath and the cuticle of the exsheathed larvae were clearly different. Although they did not moult during culture, SEM revealed a morphology typical of third-stage larvae of Contracaecum from fish, as previously observed by optical microscopy. Thus, we suggest that newly hatched larvae from eggs of C. multipapillatum are third larval stage but with sheath of the second larval stage, as occuring in other anisakids.

FIB-SEM tomography of human skin telocytes and their extracellular vesicles.

PubMed

Cretoiu, Dragos; Gherghiceanu, Mihaela; Hummel, Eric; Zimmermann, Hans; Simionescu, Olga; Popescu, Laurentiu M

2015-04-01

We have shown in 2012 the existence of telocytes (TCs) in human dermis. TCs were described by transmission electron microscopy (TEM) as interstitial cells located in non-epithelial spaces (stroma) of many organs (see www.telocytes.com). TCs have very long prolongations (tens to hundreds micrometers) named Telopodes (Tps). These Tps have a special conformation with dilated portions named podoms (containing mitochondria, endoplasmic reticulum and caveolae) and very thin segments (below resolving power of light microscopy), called podomers. To show the real 3D architecture of TC network, we used the most advanced available electron microscope technology: focused ion beam scanning electron microscopy (FIB-SEM) tomography. Generally, 3D reconstruction of dermal TCs by FIB-SEM tomography revealed the existence of Tps with various conformations: (i) long, flattened irregular veils (ribbon-like segments) with knobs, corresponding to podoms, and (ii) tubular structures (podomers) with uneven calibre because of irregular dilations (knobs) - the podoms. FIB-SEM tomography also showed numerous extracellular vesicles (diameter 438.6 ± 149.1 nm, n = 30) released by a human dermal TC. Our data might be useful for understanding the role(s) of TCs in intercellular signalling and communication, as well as for comprehension of pathologies like scleroderma, multiple sclerosis, psoriasis, etc. © 2015 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

The influence of chemical surface modification of kenaf fiber using hydrogen peroxide on the mechanical properties of biodegradable kenaf fiber/poly(lactic acid) composites.

PubMed

Razak, Nur Inani Abdul; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Rayung, Marwah; Saad, Wan Zuhainis

2014-03-07

Bleaching treatment of kenaf fiber was performed in alkaline medium containing hydrogen peroxide solution maintained at pH 11 and 80 °C for 60 min. The bleached kenaf fiber was analyzed using Fourier Transform Infrared (FTIR) and X-ray Diffraction (XRD) analysis. The bleached kenaf fiber was then compounded with poly-(lactic acid) (PLA) via a melt blending method. The mechanical (tensile, flexural and impact) performance of the product was tested. The fiber treatment improved the mechanical properties of PLA/bleached kenaf fiber composites. Scanning electron micrograph (SEM) morphological analysis showed improvement of the interfacial adhesion between the fiber surface and polymer matrix.

Effect of laser irradiation on the structural, morphological and electrical properties of polycrystalline TiO2 thin films

NASA Astrophysics Data System (ADS)

Khan, M. I.; Ali, Asghar

TiO2 thin film is deposited on glass substrate by sol-gel dip coating technique. After deposition, films were irradiated by continuous wave (CW) diode laser at an angle of 45°. XRD shows both the anatase and brookite phases of TiO2. Nano particles of regular and control sizes are appeared in SEM micrographs. Therefore, shape and size of nano particles can be control by using Laser irradiation. The average sheet resistivity of TiO2 thin film irradiated by 0, 2, 4 and 6 min are 6.72 × 105, 5.32 × 105, 3.44 × 105 and 4.95 × 105 (ohm-m) respectively, according to four point probe.

Review on Microstructure Analysis of Metals and Alloys Using Image Analysis Techniques

NASA Astrophysics Data System (ADS)

Rekha, Suganthini; Bupesh Raja, V. K.

2017-05-01

The metals and alloys find vast application in engineering and domestic sectors. The mechanical properties of the metals and alloys are influenced by their microstructure. Hence the microstructural investigation is very critical. Traditionally the microstructure is studied using optical microscope with suitable metallurgical preparation. The past few decades the computers are applied in the capture and analysis of the optical micrographs. The advent of computer softwares like digital image processing and computer vision technologies are a boon to the analysis of the microstructure. In this paper the literature study of the various developments in the microstructural analysis, is done. The conventional optical microscope is complemented by the use of Scanning Electron Microscope (SEM) and other high end equipments.

Hydrothermal synthesis of TiO2-ZnO-graphene nanocomposite towards photocatalytic and photovoltaic applications

NASA Astrophysics Data System (ADS)

Gayathri, S.; Jayabal, P.; Ramakrishnan, V.

2015-06-01

Titanium dioxide (TiO2) - Zinc oxide (ZnO) - Graphene (G) nanocomposite was successfully synthesized through facile hydrothermal method. The X-ray diffraction (XRD) pattern and the micro-Raman spectroscopic technique revealed the formation of TiO2-ZnO-Graphene (TZG) nanocomposite. The ZnO and TiO2 nanoparticles decorated graphene sheets were clearly noticeable in the Field Emission Scanning Electron Micrograph (FE-SEM). The UV-Visible absorption spectra clearly indicated that the formation of TZG nanocomposite enriched the absorption in the visible region. Hence, the prepared nanocomposite can be used as photocatalyst to remove organic dyes from water and as photoanode in the fabrication of dye sensitized solar cells (DSSCs).

The effect of epoxidized soybean oil on mechanical and rheological properties of poly(butylene succinate)/lignin via vane extruder

NASA Astrophysics Data System (ADS)

Liu, Huanyu; Huang, Zhaoxia; Qu, Jinping; Meng, Cong

2016-03-01

Epoxidized Soybean Oil (ESO) have been used as the compatilizer in the Poly (butylene succinate)/lignin (PBS/lignin) composites. Compatibilized composites were fabricated by a novel vane extruder (VE) which can generate global and dynamic elongational flow. The effects of ESO on the mechanical, rheological properties and morphology of PBS/lignin were studied. The results indicated that the use of ESO had plasticizing effect on the matrix PBS while the addition reduced tensile strength. From SEM micrographs it could be clearly observed that there was a better interfacial adhesion between lignin and matrix. Meanwhile, rheological tests showed the incorporation of ESO improved its Newtonian behavior and can enhance PBS's flexibility.

Documentation of operational protocol for the use of MAMA software

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

Schwartz, Daniel S.

2016-01-21

Image analysis of Scanning Electron Microscope (SEM) micrographs is a complex process that can vary significantly between analysts. The factors causing the variation are numerous, and the purpose of Task 2b is to develop and test a set of protocols designed to minimize variation in image analysis between different analysts and laboratories, specifically using the MAMA software package, Version 2.1. The protocols were designed to be “minimally invasive”, so that expert SEM operators will not be overly constrained in the way they analyze particle samples. The protocols will be tested using a round-robin approach where results from expert SEM usersmore » at Los Alamos National Laboratory, Lawrence Livermore National Laboratory, Pacific Northwest National Laboratory, Savannah River National Laboratory, and the National Institute of Standards and Testing will be compared. The variation of the results will be used to quantify uncertainty in the particle image analysis process. The round-robin exercise will proceed with 3 levels of rigor, each with their own set of protocols, as described below in Tasks 2b.1, 2b.2, and 2b.3. The uncertainty will be developed using NIST standard reference material SRM 1984 “Thermal Spray Powder – Particle Size Distribution, Tungsten Carbide/Cobalt (Acicular)” [Reference 1]. Full details are available in the Certificate of Analysis, posted on the NIST website (http://www.nist.gov/srm/).« less

Endobacterial morphotypes in nudibranch cerata tips: a SEM analysis

NASA Astrophysics Data System (ADS)

Schuett, Christian; Doepke, Hilke

2013-06-01

The SEM investigation of nudibranch cerata material exhibits endobacterial morphotypes found in 12 out of 13 species tested: Aeolidia papillosa, Berghia caerulescens, Coryphella brownii, Coryphella lineata, Coryphella verrucosa, Cuthona amoena, Facelina coronata, Flabellina pedata, Dendronotus frondosus, Doto coronata, Tritonia plebeia and Janolus cristatus. Endobacteria could not be detected inside Tritonia hombergi. Endobacterial morphology found inside nudibranch species was compared to bacterial morphotypes detected earlier in tentacles of cnidarian species. SEM micrographs show endobacterial analogy among nudibranch species, but also similarity to cnidarian endobacteria investigated earlier. Of course, morphological data of microbes do not allow their identification. However, since most of these nudibranch species prey on cnidaria, it cannot be excluded that many of the endobacteria detected inside nudibranch species may originate from their cnidarian prey. Our previous data describing genetic affiliation of endobacteria from nudibranchian and cnidarian species support this assumption. Dominant coccoid endobacteria mostly exhibit smooth surface and are tightly packed as aggregates and/or wrapped in envelopes. Such bacterial aggregate type has been described previously in tentacles of the cnidarian species Sagartia elegans. Similar coccoid bacteria, lacking envelopes were also found in other nudibranch species. A different type of coccoid bacteria, characterized by a rough surface, was detected inside cerata of the nudibranch species Berghia caerulescens, and surprisingly, inside tentacles of the cnidarian species Tubularia indivisa. In contrast to cnidarian endobacteria, rod-shaped microorganisms are largely absent in nudibranch cerata.

WEATHERING DEGRADATION OF A POLYURETHANE COATING. (R828081E01)

EPA Science Inventory

The degradation of polyurethane topcoat over a chromate pigmented epoxy primer was examined by atomic force microscopy (AFM), scanning electronic microscopy (SEM), X-ray photo-electron spectroscopy (XPS) and Fourier transform infra-red spectroscopy (FTIR) after the coated pane...

CTER-rapid estimation of CTF parameters with error assessment.

PubMed

Penczek, Pawel A; Fang, Jia; Li, Xueming; Cheng, Yifan; Loerke, Justus; Spahn, Christian M T

2014-05-01

In structural electron microscopy, the accurate estimation of the Contrast Transfer Function (CTF) parameters, particularly defocus and astigmatism, is of utmost importance for both initial evaluation of micrograph quality and for subsequent structure determination. Due to increases in the rate of data collection on modern microscopes equipped with new generation cameras, it is also important that the CTF estimation can be done rapidly and with minimal user intervention. Finally, in order to minimize the necessity for manual screening of the micrographs by a user it is necessary to provide an assessment of the errors of fitted parameters values. In this work we introduce CTER, a CTF parameters estimation method distinguished by its computational efficiency. The efficiency of the method makes it suitable for high-throughput EM data collection, and enables the use of a statistical resampling technique, bootstrap, that yields standard deviations of estimated defocus and astigmatism amplitude and angle, thus facilitating the automation of the process of screening out inferior micrograph data. Furthermore, CTER also outputs the spatial frequency limit imposed by reciprocal space aliasing of the discrete form of the CTF and the finite window size. We demonstrate the efficiency and accuracy of CTER using a data set collected on a 300kV Tecnai Polara (FEI) using the K2 Summit DED camera in super-resolution counting mode. Using CTER we obtained a structure of the 80S ribosome whose large subunit had a resolution of 4.03Å without, and 3.85Å with, inclusion of astigmatism parameters. Copyright © 2014 Elsevier B.V. All rights reserved.

Colocalization analysis in fluorescence micrographs: verification of a more accurate calculation of pearson's correlation coefficient.

PubMed

Barlow, Andrew L; Macleod, Alasdair; Noppen, Samuel; Sanderson, Jeremy; Guérin, Christopher J

2010-12-01

One of the most routine uses of fluorescence microscopy is colocalization, i.e., the demonstration of a relationship between pairs of biological molecules. Frequently this is presented simplistically by the use of overlays of red and green images, with areas of yellow indicating colocalization of the molecules. Colocalization data are rarely quantified and can be misleading. Our results from both synthetic and biological datasets demonstrate that the generation of Pearson's correlation coefficient between pairs of images can overestimate positive correlation and fail to demonstrate negative correlation. We have demonstrated that the calculation of a thresholded Pearson's correlation coefficient using only intensity values over a determined threshold in both channels produces numerical values that more accurately describe both synthetic datasets and biological examples. Its use will bring clarity and accuracy to colocalization studies using fluorescent microscopy.

Influence of the forming conditions on Black Carbon properties

NASA Astrophysics Data System (ADS)

Soucemarianadin, L. N.; MacKenzie, M. D.; Wasylishen, R. E.; Quideau, S. A.

2012-04-01

Black carbon (BC) is an important residue of wildfires in Quebec black spruce forests. Because of its recalcitrance, it is considered a valuable passive pool in the global carbon cycle. However, BC characteristics depend on its conditions of formation. The objective of this study was to characterize BC chemical and physical properties under varying fire severity. BC samples were produced, under controlled conditions, from fuels originating from mosses (Sphagnum spp. and Pleurozium shreberi), ericaceous shrubs (Ledum groenlandicum) and trees (Picea mariana), as they constitute the major types available in black spruce forests. In order to mimic a gradient of fire severity as it could occur in the field, we varied the maximum temperature (MT) from 75 to 800°C, and the duration of charring from 0.5 to 24 hours. Charcoalification was conducted either under partial (covered tins with holes) or complete pyrolysis (samples buried in sand bath). Samples were analyzed for aromaticity and porosity using elemental and proximate analyses, solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy (SEM) and surface area (SA) analysis. MT was the most significant factor affecting both chemical and physical changes. BC produced above 250°C started to show signs of condensation (H/C = 0.89; O/C = 0.36 average of all fuel types), which increased with MT (at 800°C, H/C = 0.20; O/C = 0.12 average for all fuels). Results from the 13C NMR spectroscopy highlighted that 350°C was the threshold temperature, at which point spectra were dominated by aromatic structures for all fuels. Specific SA first experienced a decrease (2.3 to 0.8 m2/g) with increasing temperature, then increased drastically for MT above 350°C (10.6 to 435 m2/g at 800°C). Porosity was also largely affected by the type of fuel. SEM micrographs showed a visible increase in porosity for all the BC produced above 250°C/350°C. All results demonstrate that increasing thermal treatment has major effects on BC properties, which in turn may determine its potential as a carbon sink and a catalyst of post-fire regeneration.

Fabrication and characterization of nano-Y2O3 and Al2O3 dispersed W-Ni alloys by mechanical alloying and pressureless conventional sintering

NASA Astrophysics Data System (ADS)

Talekar, V. R.; Patra, A.; Karak, S. K.

2018-03-01

Nano Y2O3 and Al2O3 dispersed W-Ni alloys with nominal composition of W89Ni10 (Y2O3)1 (alloy A), W89Ni10 (Al2O3)1 (alloy B) were mechanically alloyed for 10 h followed by compaction at 0.5 GPa pressure with 5 min of dwell time and conventional sintering at 1400°C with 2 h soaking time in Ar atmosphere with Ar flow rate of 100 ml/min. The microstructure of milled and sintered alloy was investigated using X-ray Diffraction (XRD), Scanning electron Microscopy (SEM), Energy dispersive spectroscopy (EDS) and Elemental mapping. Minimum crystallite size of 31.9 nm and maximum lattice strain, dislocation density of 0.23%, 9.12(1016/m2) respectively was found in alloy A at 10 h of milling. Uneven and coarse particles at 0 h of milling converted to elongated flake shape at 10 h of milling. Bimodal (fine and coarse) particle size distribution is revealed in both the alloys and minimum particle size of 0.69 μm is achieved in 10 h milled alloy A. Evidences of formation of intermetallic phases like Y2WO6, Y6WO12 and Y10W2O21 in sintered alloy A and Al2(WO4)3, NiAl10O16, NiAl2O4 and AlWO4 in sintered alloy B were revealed by XRD pattern and SEM micrograph. Minimum grain size of 1.50 μm was recorded in sintered alloy A. Both faceted and spherical W matrix is evident in both the alloys which suggests occurrence of both solid phase and liquid phase sintering. Maximum % relative sintered density and hardness of 85.29% and 5.13 GPa respectively was found in alloy A. Wear study at 20N force at 25 rpm for 15 min on ball on plate wear tester revealed that minimum wear depth (48.99 μm) and wear track width (272 μm) was found for alloy A as compared to alloy B.

Halloysite nanotube incorporation into adhesive systems—effect on bond strength to human dentin.

PubMed

Alkatheeri, Mohammed S; Palasuk, Jadesada; Eckert, George J; Platt, Jeffrey A; Bottino, Marco C

2015-11-01

This study aimed to evaluate the effect of Halloysite® aluminosilicate clay nanotube (HNT) incorporation into a two-step etch-and-rinse (ER) and a one-step self-etch (SE) adhesive on human dentin shear bond strength (SBS). Ten groups (n = 12) were prepared according to the adhesive system (i.e., ER or SE) and amount of HNT incorporated (5-20%, w/v), as follows: commercial control (i.e., the adhesive was used as purchased, 0% HNT); experimental control (i.e., the adhesive was processed through mixing/stirring and sonication similarly to the HNT-incorporated experimental groups, but without HNT); and 5, 10, and 20% HNT. SBS testing was performed after 24 h of storage in deionized water at 37 °C. Failure modes were examined using a stereomicroscope (×40). Scanning electron microscopy (SEM) of the resin-dentin interface of selected specimens was carried out. Two-way ANOVA revealed that incorporation of HNT up to 20% (w/v) in ER and up to 10% (w/v) in SE demonstrated an increased SBS compared to their experimental controls. Compared to the commercial control, SBS of HNT-modified dentin adhesives was not significantly different for ER adhesives (p > 0.05) but was significantly higher with 5% HNT in the SE adhesive (p < 0.05). Failure modes were predominantly adhesive and mixed failures. SEM micrographs of resin-dentin interfaces for ER-commercial control and ER-10% showed a similar morphology. A thicker adhesive layer and the presence of agglomerated HNT on the resin tags were seen in ER-10%. An increased number of short resin tags in SE-5% compared with SE-commercial control were observed. HNT addition up to 20% in ER and up to 10 % in SE showed increased SBS to dentin compared with the experimental control. HNT can be used not only to reinforce adhesive resins but also hold potential for the development of bioactive adhesives by the encapsulation of matrix metalloproteinase (MMP) inhibitors or anticariogenic agents.

Ni-CeO2 spherical nanostructures for magnetic and electrochemical supercapacitor applications.

PubMed

Murugan, Ramachandran; Ravi, Ganesan; Vijayaprasath, Gandhi; Rajendran, Somasundharam; Thaiyan, Mahalingam; Nallappan, Maheswari; Gopalan, Muralidharan; Hayakawa, Yasuhiro

2017-02-08

The synthesis of nanoparticles has great control over the structural and functional characteristics of materials. In this study, CeO 2 and Ni-CeO 2 spherical nanoparticles were prepared using a microwave-assisted method. The prepared nanoparticles were characterized via thermogravimetry, X-ray diffraction (XRD), Raman, FTIR, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM) and cyclic voltammetry (CV). The pure CeO 2 sample exhibited a flake-like morphology, whereas Ni-doped CeO 2 showed spherical morphology with uniform shapes. Spherical morphologies for the Ni-doped samples were further confirmed via TEM micrographs. Thermogravimetric analyses revealed that decomposition varies with Ni-doping in CeO 2 . XRD revealed that the peak shifts towards lower angles for the Ni-doped samples. Furthermore, a diamagnetic to ferromagnetic transition was observed in Ni-doped CeO 2 . The ferromagnetic property was attributed to the introduction of oxygen vacancies in the CeO 2 lattice upon doping with Ni, which were confirmed by Raman and XPS. The pseudo-capacitive properties of pure and Ni-doped CeO 2 samples were evaluated via cyclic voltammetry and galvanostatic charge-discharge studies, wherein 1 M KOH was used as the electrolyte. The specific capacitances were 235, 351, 382, 577 and 417 F g -1 corresponding to the pure 1%, 3%, 5% and 7% of Ni doped samples at the current density of 2 A g -1 , respectively. The 5% Ni-doped sample showed an excellent cyclic stability and maintained 94% of its maximum specific capacitance after 1000 cycles.

Synthesis and characterization of oleic acid surface modified magnetic iron oxide nanoparticles by using biocompatible w/o microemulsion for heavy metal removal

NASA Astrophysics Data System (ADS)

Rose, Laili Che; Suhaimi, Hamdan; Mamat, Mazidah; Lik, Thang Zhe

2017-09-01

Oleic acid modified magnetic iron oxide nanoparticles (OA-MIONs) was prepared for removal of Cu2+ ion from aqueous solution. OA-MIONs was prepared by W/O microemulsion template which composed of mixed non-ionic surfactants and 1-hexanol as emulsifier. The effect of weight ratio of the constituent of microemulsion template on the physical and chemical properties of OA-MIONs was studied by characterization using Fourier transform infrared (FT-IR), scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) analysis. FT-IR spectra showed that all templates shared similar chemical structure with slight difference in the peak intensity. Scanning electron micrograph illustrated that the OA-MIONs synthesized via template with the lowest weight ratio of emulsifier to heptane had a more regular spherical shape and was well-distributed. XRD had confirmed that the identity of synthesized OA-MIONs was Fe3O4. Based on the characterization result, the template with lowest weight ratio of emulsifier to heptane was chosen for the heavy metal adsorption study. The adsorption capacity OA-MIONs as a function of pH, contact time and adsorbent dosage were studied. The adsorption process reached equilibrium for 90 minutes and successfully adsorbed 43% of Cu2+ ion from aqueous solution. The adsorption behavior was well described by Langmuir isotherm. The maximum adsorption capacity was determined and found to be 555.56 mg/g. The value of Langmuir equilibrium parameter, RL was found between 0 and 1, suggested that a favorable monolayer adsorption process had taken out.

First report on soapnut extract-mediated synthesis of sulphur-substituted nanoscale NdFeB permanent magnets and their characterization

NASA Astrophysics Data System (ADS)

Jayapala Rao, G. V. S.; Prasad, T. N. V. K. V.; Shameer, Syed; Arun, T.; Purnachandra Rao, M.

2017-10-01

Biosynthesis of nanoscale materials has its own advantages over other physical and chemical methods. Using soapnut extract as reducing and stabilizing agent for the synthesis of inorganic nanoscale materials is novel and has not been exploited to its potential so far. Herein, we report for the first time on the effects of sulphur substitution on soapnut extract-mediated synthesis of nanoscale NdFeB (S-NdFeB) permanent magnetic powders (Nd 15%, Fe 77.5%, B 7.5% and S with molar ratios: 0.1, 0.2, 0.3, 0.4, and 0.5). To synthesize, a 10 ml of 10% soapnut extract was added to 90 ml of respective chemical composition and heated to 60 °C for 30 min and aged for 24 h. The dried powder was sintered at 500 °C for 1 h. The characterization of the as-prepared nanoscale S-NdFeB magnetic materials was done using the techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersion spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS for size and zeta potential measurements) and vibrating sample magnetometer (VSM)-hysteresis loop studies. The results revealed that particles were highly stable (with a negative zeta potential of 25.7 mV) with irregular and spherical shape (with measured hydrodynamic diameter 6.7 and 63.5 nm). The tetragonal structures of the formed powders were revealed by XRD micrographs. Hysteresis loop studies clearly indicate the effect of S concentration on the enhanced magnetization of the materials.

Preparation of Ag@AgCl-doped TiO2/sepiolite and its photocatalytic mechanism under visible light.

PubMed

Liu, Shaomin; Zhu, Dinglong; Zhu, Jinglin; Yang, Qing; Wu, Huijun

2017-10-01

A cube-like Ag@AgCl-doped TiO 2 /sepiolite (denoted Ag@AgCl-TiO 2 /sepiolite) was successfully synthesized via a novel method. X-ray diffraction, scanning electron microscopy, energy dispersion X-ray fluorescence, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and diffuse reflectance ultraviolet-visible spectroscopy were performed to determine the structure and physicochemical properties of Ag@AgCl-TiO 2 /sepiolite. SEM micrographs revealed that Ag@AgCl nanoparticles and TiO 2 film are well deposited on the surface of tube-like sepiolite. As a result, Ag@AgCl-TiO 2 /sepiolite exhibits a red shift relative to TiO 2 /sepiolite. Photocatalytic experiments demonstrated that the dosage of catalysts plays an important role during photocatalysis. The photoelectrochemical activities of Ag@AgCl-TiO 2 /sepiolite and TiO 2 /sepiolite were also investigated. Photocurrent responses confirmed that the ability of Ag@AgCl-TiO 2 /sepiolite to separate photo-generated electron-hole pairs is stronger than that of TiO 2 /sepiolite. Methylene Blue degradation is also improved under alkaline conditions and visible light irradiation because more OH is produced by visible light excitation. This excellent catalytic ability is mainly attributed to the formed Ag nanoparticles and the Schottky barrier at the Ag/TiO 2 interface. Active species analysis indicated that O 2 - and h + are implicated as active species in photocatalysis. Therefore, catalysts are excited to produce abundant electron-hole pairs after they absorb photons in photocatalysis. Copyright © 2017. Published by Elsevier B.V.

Ultrastructural organization of the hamster renal pelvis.

PubMed

Lacy, E R; Schmidt-Nielsen, B

1979-08-01

The renal pelvis of the hamster has been studied by light microscopy (epoxy resin sections), transmission electron microscopy, and morphometric analysis of electron micrographs. Three morphologically distinct epithelia line the pelvis, and each covers a different zone of the kidney. A thin epithelium covering the outer medulla (OM) consists of two cell types: (1) granular cells are most numerous and have apically positioned granules which stain intensely with toluidine blue, are membrane-bound, and contain a fine particulate matter that stains light grey to black in electron micrographs. (2) Basal cells do not have granules, are confined to the basal lamina region, and do not reach the mucosal epithelial surface. The inner medulla (IM) is covered by a pelvic epithelium morphologically similar to collecting duct epithelium of IM. Some cells in this portion of the pelvic epithelium (IM) stain intensely dark with toluidine blue, osmium tetroxide, lead, and uranyl acetate. Transitional epithelium, which separates cortex (C) from pelvic urine, has an asymmetric luminal plasma membrane and discoid vesicles, each of which is similar to those previously observed in mammalian ureter and urinary bladder epithelia. Based on morphological comparisons with other epithelia, the IM and OM pelvic epithelia would appear permeable to solutes and/or water, while the transitional epithelium covering the C appears relatively impermeable. It would also appear that the exchange of solutes and water between pelvic urine and OM would involve capillaries, primarily, since morphometric analysis showed that both fenestrated and continuous capillaries of the OM were extremely abundant (greater than 60% of OM pelvic surface area) just under the thin pelvic epithelium.

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.

Scanning electron microscopy of clays and clay minerals

USGS Publications Warehouse

Bohor, B.F.; Hughes, R.E.

1971-01-01

The scanning electron microscope (SEM) proves to be ideally suited for studying the configuration, texture, and fabric of clay samples. Growth mechanics of crystalline units—interpenetration and interlocking of crystallites, crystal habits, twinning, helical growth, and topotaxis—also are uniquely revealed by the SEM.Authigenic kaolins make up the bulk of the examples because their larger crystallite size, better crystallinity, and open texture make them more suited to examination by the SEM than most other clay mineral types.