JOURNAL OF FOOD PROCESS ENGINEERING, Issue 5 2010
PETER WAMBURA
ABSTRACT Peanut oil migrates to the outer surface during roasting, where it comes into contact with oxygen, leading to the oxidation reactions. Because of its cleaning effect, power ultrasound (sonication) was used for removing surface lipid of roasted peanuts. Georgia green runner-type peanuts were roasted at 178C for 15 min. Roasted peanuts were subjected to lipid extraction in n-hexane by sonication. Fluorescent and electron scanning micrographs revealed that the surface of sonicated peanuts was free of oil stains, as opposed to that of freshly roasted peanuts. These results showed that power ultrasound could remove the lipids from peanut surfaces very effectively. Details of microstructure of sonicated peanuts as was observed using scanning electron microscope reveal that 10 min sonication was sufficient to extract most of the lipids on the roasted peanut surfaces. Fluorescence and scanning electron microscopy are useful in peanut analysis because they can detect lipids in low concentration. PRACTICAL APPLICATIONS There is increasing interest of quick procedures to examine the surfaces of roasted peanut samples after undergoing treatments, such as removal of lipids. This research demonstrated the significant use of fluorescent and scanning electron microscopes to quickly study the extent of lipid removal from the surface of roasted peanuts after power ultrasound treatment (sonication). [source]

PROBING THE SURFACE OF LIVING DIATOMS WITH ATOMIC FORCE MICROSCOPY: THE NANOSTRUCTURE AND NANOMECHANICAL PROPERTIES OF THE MUCILAGE LAYER,

JOURNAL OF PHYCOLOGY, Issue 4 2003
Michael J. Higgins
Atomic force microscopy (AFM) is used to investigate the topography and material properties of the mucilage layer of live cells of three benthic diatoms, the marine species Crasepdostauros australis E. J. Cox and Nitzschia navis-varingica Lundholm et Moestrup and the freshwater species Pinnularia viridis (Nitzsch) Ehrenberg. Contrary to previous studies, we show that this surface mucilage layer displays unique nanostructural features. In C. australis, tapping mode images revealed a soft mucilage layer encasing the silica cell wall, consisting of a smooth flat surface that was interrupted by regions with groove-like indentations, whereas force measurements revealed the adhesive binding of polymer chains. The elastic responses of these polymer chains, as they were stretched during force measurements, were successfully fitted to the worm-like chain model, indicating the stretching of mostly single macromolecules from which quantitative information was extracted. In P. viridis, tapping mode images of cells revealed a mucilage layer that had the appearance of densely packed spheres, whereas force measurements exhibited no adhesion. In N. navis-varingica, tapping mode images of the outer surface of this cell in the girdle region revealed the absence of a mucilage layer, in contrast to the other two species. In addition to these topographic and adhesion studies, the first quantitative measurement of the elastic properties of microalgal extracellular polymeric substance is presented and reveals significant spatial variation in the C. australis and P. viridis mucilage layers. This study highlights the capacity of AFM in elucidating the topography and mechanical properties of hydrated microalgal extracellular polymeric substance on a nanoscale. [source]

Local Electrochemical Functionality in Energy Storage Materials and Devices by Scanning Probe Microscopies: Status and Perspectives

ADVANCED MATERIALS, Issue 35 2010
Sergei V. Kalinin
Abstract Energy storage and conversion systems are an integral component of emerging green technologies, including mobile electronic devices, automotive, and storage components of solar and wind energy economics. Despite the rapidly expanding manufacturing capabilities and wealth of phenomenological information on the macroscopic device behaviors, the microscopic mechanisms underpinning battery and fuel cell operations in the nanometer,micrometer range are virtually unknown. This lack of information is due to the dearth of experimental techniques capable of addressing elementary mechanisms involved in battery operation, including electronic and ion transport, vacancy injection, and interfacial reactions, on the nanometer scale. In this article, a brief overview of scanning probe microscopy (SPM) methods addressing nanoscale electrochemical functionalities is provided and compared with macroscopic electrochemical methods. Future applications of emergent SPM methods, including near field optical, electromechanical, microwave, and thermal probes and combined SPM-(S)TEM (scanning transmission electron microscopy) methods in energy storage and conversion materials are discussed. [source]

Intracellular Imaging of HCV RNA and Cellular Lipids by Using Simultaneous Two-Photon Fluorescence and Coherent Anti-Stokes Raman Scattering Microscopies

CHEMBIOCHEM, Issue 12 2006
Xiaolin Nan
Hepatitis C virus (HCV) infection is associated with changes in host-cell lipid metabolism. Here we describe a new approach for detecting HCV RNA using two-photon fluorescence (TPF), and HCV-associated changes in cellular lipids using coherent anti-Stokes Raman scattering (CARS) microscopy. By combining the two types of microscopy with a common laser source, we visualized both phenomena simultaneously and profiled cellular lipids and subcellular localization of RNA in real time. [source]

Preparation and characterization of ZnO nanofibers by electrospinning

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2006
R. Siddheswaran
Abstract Electrospun ZnO nanofibers were obtained by calcinating PVA/Zinc Acetate composite fibers at various temperatures. Atomic Force Microscopy (AFM) revealed that the ZnO fibers have diameters in the range of 100-200 nm. The fibers were characterized by FT- IR, TGA-DTA, and XRD studies. The XRD results showed that the crystal structure and the morphology of the fibers were largely dependent on the calcination temperature (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Optimization of Cr8O21 targets for Pulsed Laser Deposition

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2005
L. Tortet
Abstract This work describes the preparation of Cr8O21 pellets with optimised mass density to be used as targets for Pulsed Laser Deposition (PLD) of chromium dioxide thin films. Cr8O21 is synthesised by thermal decomposition of CrO3, at 270 °C. An attempt to reduce the grain size of the Cr8O21 powder to the nanometer scale has been made in order to increase the density of the pressed and sintered pellets serving as targets. The morphology of those starting fine powders as well as of targets (before and after laser ablation) and the corresponding thin films were characterized and studied using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Raman spectroscopy. The composition of the films is a mixture of crystallised Cr2O3 and amorphous CrO2. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

The effect of alloying elements on the crystallization behaviour and on the properties of galvanized coatings

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2004
G. Vourlias
Abstract The influence of the alloying elements on the interface reactions of zinc coatings during the galvanization process was examined. These reactions affect the crystallization and the structure and properties of the outer layer of the coatings. Depending on the type and concentration of the alloying additions in the galvanizing bath differences were induced in the crystallization process of the Fe-Zn phases. It was found that both the concentration and the distribution of the alloying elements played an important role in the growth of the phases. The formation of the phases and the distribution of the alloying elements in the coatings were determined using X-Ray diffraction (XRD) and Scanning Electron Microscopy (SEM) associated with an Energy Dispersive X-Ray Spectroscopy (EDS) analysis. Finally the behaviour of the galvanized coatings was examined under accelerated salt spray corrosion conditions. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Simulated microgravity activates MAPK pathways in fibroblasts cultured on microgrooved surface topography

CYTOSKELETON, Issue 2 2008
W. A. Loesberg
Abstract This study evaluated in vitro the differences in morphological behaviour between fibroblast cultured on smooth and microgrooved substrata (groove depth: 0.5 ,m, width: 1 ,m), which were subjected to simulated microgravity. The aim of the study was to clarify which of these parameters was more dominant to determine cell behaviour. Morphological characteristics were investigated using scanning electron microscopy and fluorescence microscopy in order to obtain qualitative information on cell alignment. Expression of collagen type I, and ,1-, ,1-, ,3-integrin were investigated by QPCR. Finally, immunoblotting was applied to visualise MAPK signalling pathways. Microscopy and image analysis showed that the fibroblasts aligned along the groove direction on all textured surfaces. On the smooth substrata, cells had spread out in a random fashion. The alignment of cells cultured on grooved surfaces under simulated microgravity, after 48 h of culturing appeared similar to those cultured at 1g, although cell shape was different. Analysis of variance proved that all main parameters: topography, gravity force, and time were significant. In addition, gene levels were reduced by simulated microgravity particularly those of ,3-integrin and collagen, however alpha-1 and beta-1 integrin levels were up-regulated. ERK1/2 was reduced in RPM, however, JNK/SAPK and p38 remained active. The members of the small GTPases family were stimulated under microgravity, particularly RhoA and Cdc42. The results are in agreement that application of microgravity to fibroblasts promotes a change in their morphological appearance and their expression of cell-substratum proteins through the MAPK intracellular signalling pathways. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source]

The effect of combined simulated microgravity and microgrooved surface topography on fibroblasts

CYTOSKELETON, Issue 3 2007
W. A. Loesberg
Abstract This study evaluated in vitro the differences in morphological behaviour between fibroblast cultured on smooth and microgrooved substrata (groove depth: 0.5 ,m, width: 1, 2, 5, and 10 ,m), which were subjected to simulated microgravity. The aim of the study was to clarify which of these parameters was more dominant to determine cell behaviour. Morphological characteristics were investigated using scanning electron microscopy and fluorescence microscopy in order to obtain qualitative information on cell alignment and area. Confocal laser scanning microscopy visualised distribution of actin filaments and focal adhesion points. Finally, expression of collagen type I, fibronectin, and ,1- and ,1-integrin were investigated by PCR. Microscopy and image analysis showed that the fibroblasts aligned along the groove direction on all textured surfaces. On the smooth substrata, cells had spread out in a random fashion. The alignment of cells cultured on grooved surfaces decreased under simulated microgravity, especially after 24 h of culturing. Cell surface area on grooved substrata were significantly smaller than on smooth substrata, but simulated microgravity on the grooved groups resulted in an enlargement of cell area. ANOVA was performed on all main parameters: topography, gravity force, and time. In this analysis, all parameters proved significant. In addition, gene levels were reduced by microgravity particularly those of ,1-integrin and fibronectin. From our data it is concluded that the fibroblasts primarily adjust their shape according to morphological environmental cues like substratum surface whilst a secondary, but significant, role is played by microgravity conditions. Cell Motil. Cytoskeleton 2007. © 2007 Wiley-Liss, Inc. [source]

The effect of combined hypergravity and microgrooved surface topography on the behaviour of fibroblasts

CYTOSKELETON, Issue 7 2006
W. A. Loesberg
Abstract This study evaluated in vitro the differences in morphological behaviour between fibroblast cultured on smooth and microgrooved substrata (groove depth: 1 ,m, width: 1, 2, 5, 10 ,m), which undergo artificial hypergravity by centrifugation (10, 24 and 50 g; or 1 g control). The aim of the study was to clarify which of these parameters was more important to determine cell behaviour. Morphological characteristics were investigated using scanning electron microscopy and fluorescence microscopy in order to obtain qualitative information on cell spreading and alignment. Confocal laser scanning microscopy visualised distribution of actin filaments and vinculin anchoring points through immunostaining. Finally, expression of collagen type I, fibronectin, and ,1 - and ,1 -integrin were investigated by PCR. Microscopy and image analysis showed that the fibroblasts aligned along the groove direction on all textured surfaces. On the smooth substrata (control), cells spread out in a random fashion. The alignment of cells cultured on grooved surfaces increased with higher g-forces until a peak value at 25 g. An ANOVA was performed on the data, for all main parameters: topography, gravity force, and time. In this analysis, all parameters proved significant. In addition, most gene levels were reduced by hypergravity. Still, collagen type 1 and fibronectin are seemingly unaffected by time or force. From our data it is concluded that the fibroblasts primarily adjust their shape according to morphological environmental cues like substratum surface whilst a secondary, but significant, role is played by hypergravity forces. Cell Motil. Cytoskeleton 2006. © 2006 Wiley-Liss, Inc. [source]

Four Views of Areolar Melanosis: Clinical Appearance, Dermoscopy, Confocal Microscopy, and Histopathology

DERMATOLOGIC SURGERY, Issue 8 2008
MARYANN MIKHAIL MD
No abstract is available for this article. [source]

Detecting Biorecognition Events at Blocked Interface Polymeric Membrane Ion-Selective Electrodes Using Electrochemical Impedance Spectroscopy and Atomic Force Microscopy

ELECTROANALYSIS, Issue 3 2008
Marco, Roland De
Abstract Immobilization of a biorecognition element onto a polymeric membrane ion-selective electrode (ISE) using a self-assembly approach may provide scope for a novel biosensor technology platform based on the altered potentiometric response at the blocked ISE interface. In this paper, the authors have investigated the influence of solution adsorption of the model biorecognition element, avidin-biotin, on the electrode kinetics of a conventional polymeric membrane Ca2+ ISE using atomic force microscopy (AFM) coupled with electrochemical impedance spectroscopy (EIS). It is demonstrated that solution adsorption of avidin followed by biotin incorporation leads to a demonstrable biorecognition event characterized by an impediment in the Ca2+ ion transfer kinetics of the modified ISE surface. This kinetic principle is amenable to biosensing using pulsed chronopotentiometric polymeric ISEs, which is an established dynamic electrode technique for use with polymeric membrane ISEs. [source]

Fabrication of Active Horseradish Peroxidase Micropatterns with a High Resolution by Scanning Electrochemical Microscopy

ELECTROANALYSIS, Issue 16 2007
Xuemei Li
Abstract We used a new reactive species OH, to fabricate active horseradish peroxidase (HRP) micropatterns with a high resolution by scanning electrochemical microscopy (SECM) coupled with a carbon fiber disk electrode as the SECM tip. In this method, except for active HRP micropatterns predesigned other regions on a HRP-immobilized substrate were deactivated by OH, generated at the tip held at ,1.7,V in 1.0,mol/L KCl containing 2.0×10,3 mol/L benzoquinone (BQ) (pH,8.0). The feedback mode of SECM with a tip potential of ,0.2,V was used to characterize the active HRP micropatterns in 1.0,mol/L KCl containing 2.0×10,3 mol/L BQ and 2.0×10,3 mol/L H2O2. [source]

Spatial Imaging of Cu2+ -Ion Release by Combining Alternating Current and Underpotential Stripping Mode Scanning Electrochemical Microscopy

ELECTROANALYSIS, Issue 2-3 2007
Dirk Ruhlig
Abstract Anodic underpotential stripping voltammetry was integrated into SECM in order to characterize local corrosion of metallic copper deposits on metal surfaces as a model for copper containing alloys. Primarily, the alternating current mode of SECM was applied in an electrolyte of low ionic strength for localizing possible corrosion sites without any perturbation of the corroding surface, e.g., by the presence of any redox mediator. Sequentially, the release of Cu2+ -ions was confirmed and locally visualized at the previously detected electrochemically active sites by means of spatially resolved anodic underpotential stripping voltammetry performed during SECM scanning. Underpotential stripping voltammetry of Cu2+ -ions was performed at a specifically developed 15,,m gold-coated Pt microelectrode used as SECM tip with a detection limit of 0.15,nM Cu2+ (N=4, RSD=6%) for an accumulation of 45,s at ,0.4,V. SECM images of model samples such as copper coated microelectrodes and lacquered metallic copper workpieces demonstrated the feasibility and applicability of combining AC- and underpotential stripping mode of SECM for local visualization of Cu2+ -ion release from corroding surfaces. [source]

Scanning Electrochemical Microscopy as an In Vitro Technique for Measuring Convective Flow Rates Across Dentine and the Efficacy of Surface Blocking Treatments

ELECTROANALYSIS, Issue 3 2005
Julie
Abstract Scanning electrochemical microscopy (SECM) is shown to be a powerful technique for both the measurement of local solution velocities through human dentine slices, in vitro, and for assessing quantitatively the effect of surface treatments on the flow process. SECM employs a small ultramicroelectrode (micron dimensions) as an imaging probe to provide information on the topography and transport characteristics of dentine, with high spatial resolution. In these studies the dentine sample is a membrane in a two compartment cell, which contains solutions of identical composition, including a redox active mediator (Fe(CN). In the absence of an applied pressure, the transport-limited current response at the probe electrode is due to diffusion of Fe(CN) to the UME, which depends on the probe to sample separation. Under an applied hydrostatic pressure, hydrodynamic flow across the sample enhances mass transport to the UME. With this methodology it was possible to accurately measure effective fluid velocities, by recording tip currents with and without pressure, and assess the efficacy of potential flow retarding agents for the treatment of dentinal hypersensitivity. For native dentine, the solution velocity was found to vary dramatically with location on the sample. The application of a glycerol monooleate - base paste treatment to the surface of dentine was found to lower local flow velocities significantly. This electroanalytical methodology is simple to implement and is generally applicable to assessing the efficacy and mode of action of a wide variety of potential fluid flow retarding agents. [source]

Development of Live Cell Chips to Monitor Cell Differentiation Processes

ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 1 2008
C. Maercker
Abstract A big demand exists for high-throughput functional in vitro assays which can measure cellular phenotypes by molecular methods and therefore improve the resources of primary cells for cell therapy, tissue engineering and high-content screenings in drug development. This approach focuses on cellular adhesion which is an important differentiation process during homing of stem cells. Moreover, it is a promising method especially for adherent cells which are not accessible by classical cell sorting methods. The chip design includes a housing with electrodes to measure electric field densities and impedance, respectively. Moreover, specific coatings of the wells permit a perfect growth of the selected cell types. In parallel, protein biomarkers can be followed by light microscopy. So far, experiments have been started to discriminate between different cell densities and cell types. In addition, after stimulating human cardiac fibroblasts and human umbilical vein endothelial cells, concentrations of proteins involved in adhesion had been increased, and proteins were translocated within the cells. In ongoing experiments, different human cell lines and fibroblastoid mesenchymal stem cells isolated from fat tissue, umbilical cord, or bone marrow are tested in the chip. To optimize the adhesion conditions, the surfaces within the vials of the chip were specifically activated. Microscopy was adjusted to be able to measure cellular morphology in parallel. This concept allows to identify the behavior of mesenchymal stem cells, which cannot be described so far by standard biomarkers. In addition, simulation of the homing process of the cells within its stem cell niche in an in vitro assay is a promising setup for large-scale gain-of-function or loss-of-function screenings in functional genomics as well as for generating precursor cells relevant for the therapy of various diseases. [source]

Ultrastructural and electron energy-loss spectroscopic analysis of an extracellular filamentous matrix of an environmental bacterial isolate

ENVIRONMENTAL MICROBIOLOGY, Issue 9 2007
Uta Böckelmann
Summary Strain F8, a bacterial isolate from ,river snow', was found to produce extracellular fibres in the form of a filamentous network. These extracellular filaments, which were previously shown to be composed of DNA, have been studied for the first time by ultrastructural and electron energy-loss spectroscopy in the present work. ,Whole mount' preparations of strain F8 indicate these polymers are ultrastructurally homogeneous and form a network of elemental filaments, which have a width of 1.8,2.0 nm. When incubated at pH 3.5 with colloidal cationic ThO2 tracers they become intensely stained (electron dense), affording direct evidence that the fibres are negatively charged and thus acidic chemically. Elemental analysis of the extracellular filaments by Energy-filtered Transmission Electron Microscopy revealed phosphorus to be the main element present and, because pretreatment of F8 cells with DNase prevented thorium labelling, the fibres must be composed of extracellular DNA (eDNA). Neither ultrathin sections nor ,whole mount negative stain' caused DNA release by general cell lysis. Additionally, cells infected with phages were never observed in ultrathin sections and phage particles were never detected in whole mount samples, which rules out the possibility of phages being directly involved in eDNA release. [source]

Hypolithic community shifts occur as a result of liquid water availability along environmental gradients in China's hot and cold hyperarid deserts

ENVIRONMENTAL MICROBIOLOGY, Issue 2 2007
Stephen B. Pointing
Summary Hypolithic cyanobacterial communities occur in hot and cold hyperarid environments but the physical factors determining their diversity are not well understood. Here we report hypolithic diversity and colonization of a common quartz substrate at several hyperarid locations in the ancient deserts of north-western China, that experience varying mean annual temperature, rainfall and concomitant availability of liquid water in soil. Microscopy and enrichment culture resulted only in Chroococcidiopsis morphotypes which were ubiquitous, but community phylogenetic analysis revealed considerable cyanobacterial and heterotrophic bacterial diversity. Species Richness and Shannon's Diversity Index displayed a significant positive linear correlation with availability of liquid water but not temperature or rainfall alone. Several taxonomic groups occurred only in specific climatically defined locations, while for Chroococcidiopsis, Deinococcus and Phormidium location specific lineages within these genera were also evident. Multivariate analysis was used to illustrate pronounced community shifts due to liquid water availability, although these did not significantly affect the predicted functional relationships within any given assemblage in either hot or cold, wet or dry hyperarid deserts. This study clearly demonstrates that availability of liquid water, rather than temperature or rainfall per se is the key determinant of hypolithic diversity in hyperarid locations, and furthermore that functionally similar yet taxonomically distinct communities occur, characterized by the presence of taxa that are specific to defined levels of aridity. [source]

Study of the Defects in Sintered SnO2 by High-Resolution Transmission Electron Microscopy and Cathodoluminescence

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2007
David Maestre
Abstract The defect structure of sintered SnO2 was investigated by high-resolution transmission electron microscopy (HRTEM), cathodoluminescence (CL), and electrical measurements. HRTEM shows the presence of the SnO phase in the sintered samples as well as twinning, stacking faults, and disordered intergrowths. The sintered samples annealed under an oxygen atmosphere show changes in the defect structure and in the CL spectra. In particular, the intensity of a CL band at 1.94 eV, related to oxygen vacancies, decreased as the electrical resistivity increased. The results are discussed by considering the presence of stoichiometric defects such as oxygen vacancies and Sn interstitials in the final structure and their evolution during the annealing process under an oxygen atmosphere. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Current-Voltage Characterisation of Monolayer-Supported Au-Nanoclusters by Scanning Tunnelling Microscopy under Ambient Conditions

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2005
Volker Jacobsen
Abstract The current-voltage characteristics of a double-tunnel junction based on a gold crystallite with a diameter of ca. 2 nm, separated from a gold surface by ca. 1 nm was investigated by scanning tunnelling microscopy. The sample architecture was built by attaching gold nanoparticles covered with 2-mercaptosuccinic acid to an atomically flat gold surface which was covered by a self-assembled monolayer (SAM) of 6-amino-1-hexanethiol. Surface plasmon and infrared spectroscopy as well as STM imaging were employed to identify suitable preparation conditions and prove the existence of the desired architecture. No reproducible steps in the current-voltage characteristics are observed on this system under ambient conditions. Nonetheless, a sound signature for tunnelling through the double-tunnel junction is established by a quantitative fit of the averaged experimental data to a theoretical model of a single-tunnel junction. Firstly, the current on the particle is strongly reduced at low absolute external voltage and secondly the current voltage characteristics are asymmetric. Since both deviations from theory are absent in reference experiments on the bare monolayer, they may serve as a robust signature for double-tunnel junctions and open the door to the investigation of single-electron tunnelling under ambient conditions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

STED Microscopy to Monitor Agglomeration of Silica Particles Inside A549 Cells,

ADVANCED ENGINEERING MATERIALS, Issue 5 2010
Sabrina Schübbe
The widespread use of engineered nanomaterials increases the exposure of the materials to humans. Therefore, it is necessary to know how these materials interact with cells. One approach is to trace particles by fluorescent labeling. The aim of the present work was to study the behavior of silica particles in A549 cells. For the first time, we applied stimulated emission depletion (STED) microscopy for this approach. Therefore, SiO2 particles conjugated with Atto647N were prepared by L -arginine-catalyzed hydrolysis of tetraethoxysilane. The Atto647N labeled SiO2 particles exhibit a mean size of 128,±,7,nm and a zeta-potential of ,11,mV in cell culture medium. STED microscopy enables subdiffraction resolution imaging of single Atto647N labeled SiO2 particles not only in pure solution but also in a cellular environment. To visualize Atto647N labeled SiO2 particles inside A549 cells, the membrane was labeled and image stacks, that give three-dimensional information, were taken after 5, 24, and 48 h exposure of particles to cells. During this incubation period, an increase in particle uptake was observed and STED micrographs allowed us to evaluate the agglomeration of Atto647N labeled SiO2 particles inside A549 cells. Our results show that STED microscopy is a powerful technique to study particles in a cellular environment. [source]

In Situ Characterization of a Nb and Mo Containing , -TiAl Based Alloy Using Neutron Diffraction and High-Temperature Microscopy,

ADVANCED ENGINEERING MATERIALS, Issue 11 2009
Ian J. Watson
Abstract In recent times, novel titanium aluminides containing the bcc , -phase at high temperatures are being developed for improved hot-working capabilities, however, predictions of the phase diagrams are merely uncertain. Here we present in-situ neutron studies, which are particularly sensitive to the atomic disorder in the ordered phases. Complementary laser scanning confocal microscopy is employed for in-situ microstructural investigations. [source]

Nano-characterization of Cast Structures by FIB-Tomography,

ADVANCED ENGINEERING MATERIALS, Issue 1-2 2008
F. Lasagni
In this communication, the three dimensional architectures of different Al-Si-(Mg) alloys are analyzed using SEM (Scanning Electron Microscopy)/FIB (Focus Ion Beam), EDS (Energy Dispersive Spectroscopy)/FIB and SEM-EDS/FIB tomographic methods. Several aspects for the imaging and quantification of the results are discussed describing the advantages and limitations of the methods to resolve submicron structures. [source]

Nanocrystallized Al92Sm8 Amorphous Alloy Investigated by High-Resolution Microscopy and 3D Atom-Probe Analysis

ADVANCED ENGINEERING MATERIALS, Issue 3 2007
T. Gloriant
A partially nanocrystallized amorphous Al92Sm8 (at.%) alloy was obtained directly by rapid solidification (one-step method). Because of the significant retained plasticity of the as-quenched alloy, the nanostructure and the atomic species distribution within the nanocomposite material could be characterized by field-ion microscopy (FIM) and by three-dimensional atom-probe analysis (3DAP). [source]

Transmission Electron Microscopy and Nano-Precipitation,

ADVANCED ENGINEERING MATERIALS, Issue 12 2006
T. Epicier
Abstract We have presented here a rapid survey of some of the stringent results obtained by TEM and associated techniques in the precipitation studies conducted during the CPR ,Précipitation'. It clearly appears that TEM plays an irreplaceable role in the link between the understanding of the structure and chemistry of small precipitates and the modelling of the precipitation kinetics. [source]

Combined Confocal Microscopy and Stereology: a Highly Efficient and Unbiased Approach to Quantitative Structural Measurement in Tissues

EXPERIMENTAL PHYSIOLOGY, Issue 6 2002
Katherine Howell
Understanding the relationship of the structure of organs to their function is a key component of integrative physiological research. The structure of the organs of the body is not constant but changes, both during growth and development and under conditions of sustained stress (e.g. high altitude exposure and disease). Recently, powerful new techniques have become available in molecular biology, which promise to provide novel insights into the mechanisms and consequences of these altered structure-function relationships. Conventionally structure-function relationships are studied by microscopic examination of tissue sections. However, drawing conclusions about the three-dimensional structure of an organ based on this two-dimensional information frequently leads to serious errors. The techniques of stereology allow precise and accurate quantification of structural features within three-dimensional organs that relate in a meaningful way to integrated function. For example, knowledge of changes in the total surface area of the capillary endothelium in an organ can be related directly to changes in fluid filtration and permeability, or knowledge of total vessel length and mean radius allows deductions about vascular resistance. Confocal microscopy adds enormously to the power of stereological approaches. It reduces the difficulties and labour involved in obtaining suitable images. Moreover, when used in conjunction with new analytical software, it allows convenient application of stereology to small samples and those in which it is essential to maintain a specific orientation for interpretation. The information obtained will allow us to examine in a quantitative manner the altered structure-function relationships produced by manipulation of single genes and regulatory pathways in whole organisms. [source]

Preparation and Characterization of Styrene Butadiene Rubber Based Nanocomposites and Study of their Mechanical Properties

ADVANCED ENGINEERING MATERIALS, Issue 9 2004
S. Sadhu
Nanocomposites were prepared from styrene butadiene rubber (SBR) having different styrene contents and octadecyl amine modified Na-montmorillonite clay (OC). The modified and the unmodified clays were characterized with the help of X-ray diffraction technique (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microscopy (TEM). All these nanocomposites were then subjected to tensile testing. The modified clay-rubber nanocomposites showed improved tensile strength (55% increase) and elongation at break (76% increase) compared to those of the gum vulcanizates. [source]

Nanostructure and Optoelectronic Characterization of Small Molecule Bulk Heterojunction Solar Cells by Photoconductive Atomic Force Microscopy

ADVANCED FUNCTIONAL MATERIALS, Issue 19 2010
Xuan-Dung Dang
Abstract Photoconductive atomic force microscopy is employed to study the nanoscale morphology and optoelectronic properties of bulk heterojunction solar cells based on small molecules containing a benzofuran substituted diketopyrrolopyrrole (DPP) core (3,6-bis(5-(benzofuran-2-yl)thiophen-2-yl)-2,5-bis(2-ethylhexyl)pyrrolo[3,4-c]pyrrole-1,4-dione, DPP(TBFu)2, and [6,6],phenyl-C71 -butyric acid methyl ester (PC71BM), which were recently reported to have power conversion efficiencies of 4.4%. Electron and hole collection networks are visualized for blends with different donor:acceptor ratios. Formation of nanostructures in the blends leads to a higher interfacial area for charge dissociation, while maintaining bicontinuous collection networks; conditions that lead to the high efficiency observed in the devices. An excellent agreement between nanoscale and bulk open-circuit voltage measurements is achieved by surface modification of the indium tin oxide (ITO) substrate by using aminopropyltrimethoxysilane. The local open-circuit voltage is linearly dependent on the cathode work function. These results demonstrate that photoconductive atomic force microscopy coupled with surface modification of ITO substrate can be used to study nanoscale optoelectronic phenomena of organic solar cells. [source]

Nanostructure and Optoelectronic Characterization of Small Molecule Bulk Heterojunction Solar Cells by Photoconductive Atomic Force Microscopy

Comparative single-strand conformation polymorphism (SSCP) and microscopy-based analysis of nitrogen cultivation interactive effects on the fungal community of a semiarid steppe soil

FEMS MICROBIOLOGY ECOLOGY, Issue 2-3 2001
Jennifer L. Lowell
Abstract The effects of nitrogen accretion on fungal diversity and community structure in early-seral (cultivated) and native (uncultivated) shortgrass steppe soils were evaluated using single-strand conformation polymorphism (SSCP) and microscopy in a comparative experiment. Selected haplotypes generated from fungal 18S gene fragments were also sequenced for species identification. Microscopy-based analyses showed significantly shorter fungal hyphal lengths in the early-seral control plots in comparison with the native control plots (P<0.0003), independent of nitrogen addition. Although diversity indices did not show significant differences between the plots, SSCP analyses indicated that fungal community structure differed in the native and early-seral control sites. In nitrogen-amended sites, gene sequences from dominant haplotypes indicated a shift to a more common nitrogen-impacted fungal community. While nitrogen amendments appear to be more important than cultivation in influencing these soil fungal communities, hyphal lengths were only decreased due to cultivation. The use of microscopic and molecular techniques, as carried out in this study, provided integrative information concerning fungal community responses to wide spread stresses being imposed globally on terrestrial ecosystems, that is not provided by the individual techniques. [source]