Harmonic demodulation and minimum enhancement factors in field-enhanced near-field optical microscopy.

PubMed

Scarpettini, A F; Bragas, A V

2015-01-01

Field-enhanced scanning optical microscopy relies on the design and fabrication of plasmonic probes which had to provide optical and chemical contrast at the nanoscale. In order to do so, the scattering containing the near-field information recorded in a field-enhanced scanning optical microscopy experiment, has to surpass the background light, always present due to multiple interferences between the macroscopic probe and sample. In this work, we show that when the probe-sample distance is modulated with very low amplitude, the higher the harmonic demodulation is, the better the ratio between the near-field signal and the interferometric background results. The choice of working at a given n harmonic is dictated by the experiment when the signal at the n + 1 harmonic goes below the experimental noise. We demonstrate that the optical contrast comes from the nth derivative of the near-field scattering, amplified by the interferometric background. By modelling the far and near field we calculate the probe-sample approach curves, which fit very well the experimental ones. After taking a great amount of experimental data for different probes and samples, we conclude with a table of the minimum enhancement factors needed to have optical contrast with field-enhanced scanning optical microscopy. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

Environmental scanning electron microscopy gold immunolabeling in cell biology.

PubMed

Rosso, Francesco; Papale, Ferdinando; Barbarisi, Alfonso

2013-01-01

Immunogold labeling (IGL) technique has been utilized by many authors in combination with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to obtain the identification/localization of receptors and antigens, both in cells and tissues. Environmental scanning electron microscopy (ESEM) represents an important tool in biomedical research, since it does not require any severe processing of the sample, lowering the risk of generating artifacts and interfere with the IGL procedure. The absence of metal coating could yield further advantages for our purpose as the labeling detection is based on the atomic number difference between nanogold spheres and the biological material. Using the gaseous secondary electron detector, compositional contrast is easily revealed by the backscattered electron component of the signal. In spite of this fact, only few published papers present a combination of ESEM and IGL. Hereby we present our method, optimized to improve the intensity and the specificity of the labeling signal, in order to obtain a semiquantitative evaluation of the labeling signal.In particular, we used a combination of IGL and ESEM to detect the presence of a protein on the cell surface. To achieve this purpose, we chose as an experimental system 3T3 Swiss albino mouse fibroblasts and galectin-3.

Development of an add-on kit for scanning confocal microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Guo, Kaikai; Zheng, Guoan

2017-03-01

Scanning confocal microscopy is a standard choice for many fluorescence imaging applications in basic biomedical research. It is able to produce optically sectioned images and provide acquisition versatility to address many samples and application demands. However, scanning a focused point across the specimen limits the speed of image acquisition. As a result, scanning confocal microscope only works well with stationary samples. Researchers have performed parallel confocal scanning using digital-micromirror-device (DMD), which was used to project a scanning multi-point pattern across the sample. The DMD based parallel confocal systems increase the imaging speed while maintaining the optical sectioning ability. In this paper, we report the development of an add-on kit for high-speed and low-cost confocal microscopy. By adapting this add-on kit to an existing regular microscope, one can convert it into a confocal microscope without significant hardware modifications. Compared with current DMD-based implementations, the reported approach is able to recover multiple layers along the z axis simultaneously. It may find applications in wafer inspection and 3D metrology of semiconductor circuit. The dissemination of the proposed add-on kit under $1000 budget could also lead to new types of experimental designs for biological research labs, e.g., cytology analysis in cell culture experiments, genetic studies on multicellular organisms, pharmaceutical drug profiling, RNA interference studies, investigation of microbial communities in environmental systems, and etc.

Thermal radiation scanning tunnelling microscopy

NASA Astrophysics Data System (ADS)

de Wilde, Yannick; Formanek, Florian; Carminati, Rémi; Gralak, Boris; Lemoine, Paul-Arthur; Joulain, Karl; Mulet, Jean-Philippe; Chen, Yong; Greffet, Jean-Jacques

2006-12-01

In standard near-field scanning optical microscopy (NSOM), a subwavelength probe acts as an optical `stethoscope' to map the near field produced at the sample surface by external illumination. This technique has been applied using visible, infrared, terahertz and gigahertz radiation to illuminate the sample, providing a resolution well beyond the diffraction limit. NSOM is well suited to study surface waves such as surface plasmons or surface-phonon polaritons. Using an aperture NSOM with visible laser illumination, a near-field interference pattern around a corral structure has been observed, whose features were similar to the scanning tunnelling microscope image of the electronic waves in a quantum corral. Here we describe an infrared NSOM that operates without any external illumination: it is a near-field analogue of a night-vision camera, making use of the thermal infrared evanescent fields emitted by the surface, and behaves as an optical scanning tunnelling microscope. We therefore term this instrument a `thermal radiation scanning tunnelling microscope' (TRSTM). We show the first TRSTM images of thermally excited surface plasmons, and demonstrate spatial coherence effects in near-field thermal emission.

Characterisation of a resolution enhancing image inversion interferometer.

PubMed

Wicker, Kai; Sindbert, Simon; Heintzmann, Rainer

2009-08-31

Image inversion interferometers have the potential to significantly enhance the lateral resolution and light efficiency of scanning fluorescence microscopes. Self-interference of a point source's coherent point spread function with its inverted copy leads to a reduction in the integrated signal for off-axis sources compared to sources on the inversion axis. This can be used to enhance the resolution in a confocal laser scanning microscope. We present a simple image inversion interferometer relying solely on reflections off planar surfaces. Measurements of the detection point spread function for several types of light sources confirm the predicted performance and suggest its usability for scanning confocal fluorescence microscopy.

Analysis of low-field isotropic vortex glass containing vortex groups in YBa2Cu3O7−x thin films visualized by scanning SQUID microscopy

PubMed Central

Wells, Frederick S.; Pan, Alexey V.; Wang, X. Renshaw; Fedoseev, Sergey A.; Hilgenkamp, Hans

2015-01-01

The glass-like vortex distribution in pulsed laser deposited YBa2Cu3O7 − x thin films is observed by scanning superconducting quantum interference device microscopy and analysed for ordering after cooling in magnetic fields significantly smaller than the Earth's field. Autocorrelation calculations on this distribution show a weak short-range positional order, while Delaunay triangulation shows a near-complete lack of orientational order. The distribution of these vortices is finally characterised as an isotropic vortex glass. Abnormally closely spaced groups of vortices, which are statistically unlikely to occur, are observed above a threshold magnetic field. The origin of these groups is discussed, but will require further investigation. PMID:25728772

Low-temperature scanning tunneling microscopy of ring-like surface electronic structures around Co islands on InAs(110) surfaces.

PubMed

Muzychenko, D A; Schouteden, K; Savinov, S V; Maslova, N S; Panov, V I; Van Haesendonck, C

2009-08-01

We report on the experimental observation by scanning tunneling microscopy at low temperature of ring-like features that appear around Co metal islands deposited on a clean (110) oriented surface of cleaved p-type InAs crystals. These features are visible in spectroscopic images within a certain range of negative tunneling bias voltages due to the presence of a negative differential conductance in the current-voltage dependence. A theoretical model is introduced, which takes into account non-equilibrium effects in the small tunneling junction area. In the framework of this model the appearance of the ring-like features is explained in terms of interference effects between electrons tunneling directly and indirectly (via a Co island) between the tip and the InAs surface.

Fabrication of single/multi-walled hybrid buckypaper composites and their enhancement of electromagnetic interference shielding performance

NASA Astrophysics Data System (ADS)

Lu, Shaowei; Shao, Junyan; Ma, Keming; Wang, Xiaoqiang; Zhang, Lu; Meng, Qingshi

2016-11-01

Multi-walled carbon nanotubes and single-walled carbon nanotubes show great potential for the application as an electromagnetic interference shielding material. In this paper, the electromagnetic interference shielding the effectiveness of a composite surface coated single/multi-walled carbon nanotube hybrid buckypaper was measured, which showed an average shielding effectiveness of ~55 dB with a buckypaper thickness of 50 µm, and bukypaper density of 0.76 g cm-3, it is much higher than other carbon nanotube/resin materials when sample thickness is on the similar order. The structural, specific surface area and conductivity of the buckypapers were examined by field-emission scanning electron microscopy, specific surface area analyzer and four probes resistance tester, respectively.

High temporal and spatial resolution studies of bone cells using real-time confocal reflection microscopy.

PubMed

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

1994-01-01

Chick and rat bone-derived cells were mounted in sealed coverslip-covered chambers; individual osteoclasts (but also osteoblasts) were selected and studied at 37 degrees C using three different types of high-speed scanning confocal microscopes: (1) A Noran Tandem Scanning Microscope (TSM) was used with a low light level, cooled CCD camera for image transfer to a Noran TN8502 frame store-based image analysing computer to make time lapse movie sequences using 0.1 s exposure periods, thus losing some of the advantage of the high frame rate of the TSM. Rapid focus adjustment using computer controlled piezo drivers permitted two or more focus planes to be imaged sequentially: thus (with additional light-source shuttering) the reflection confocal image could be alternated with the phase contrast image at a different focus. Individual cells were followed for up to 5 days, suggesting no significant irradiation problem. (2) Exceptional temporal and spatial resolution is available in video rate laser confocal scanning microscopes (VRCSLMs). We used the Noran Odyssey unitary beam VRCSLM with an argon ion laser at 488 nm and acousto-optic deflection (AOD) on the line axis: this instrument is truly and adjustably confocal in the reflection mode. (3) We also used the Lasertec 1LM11 line scan instrument, with an He-Ne laser at 633 nm, and AOD for the frame scan. We discuss the technical problems and merits of the different approaches. The VRCSLMs documented rapid, real-time oscillatory motion: all the methods used show rapid net movement of organelles within bone cells. The interference reflection mode gives particularly strong contrasts in confocal instruments. Phase contrast and other interference methods used in the microscopy of living cells can be used simultaneously in the TSM.

Fabrication of multi-scale periodic surface structures on Ti-6Al-4V by direct laser writing and direct laser interference patterning for modified wettability applications

NASA Astrophysics Data System (ADS)

Huerta-Murillo, D.; Aguilar-Morales, A. I.; Alamri, S.; Cardoso, J. T.; Jagdheesh, R.; Lasagni, A. F.; Ocaña, J. L.

2017-11-01

In this work, hierarchical surface patterns fabricated on Ti-6Al-4V alloy combining two laser micro-machining techniques are presented. The used technologies are based on nanosecond Direct Laser Writing and picosecond Direct Laser Interference Patterning. Squared shape micro-cells with different hatch distances were produced by Direct Laser Writing with depths values in the micro-scale, forming a well-defined closed packet. Subsequently, cross-like periodic patterns were fabricated by means of Direct Laser Interference Patterning using a two-beam configuration, generating a dual-scale periodic surface structure in both micro- and nano-scale due to the formation of Laser-Induced Periodic Surface Structure after the picosecond process. As a result a triple hierarchical periodic surface structure was generated. The surface morphology of the irradiated area was characterized with scanning electron microscopy and confocal microscopy. Additionally, static contact angle measurements were made to analyze the wettability behavior of the structures, showing a hydrophobic behavior for the hierarchical structures.

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

PubMed Central

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

2010-01-01

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

Label-free tomographic reconstruction of optically thick structures using GLIM (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kandel, Mikhail E.; Kouzehgarani, Ghazal N.; Ngyuen, Tan H.; Gillette, Martha U.; Popescu, Gabriel

2017-02-01

Although the contrast generated in transmitted light microscopy is due to the elastic scattering of light, multiple scattering scrambles the image and reduces overall visibility. To image both thin and thick samples, we turn to gradient light interference microscopy (GLIM) to simultaneously measure morphological parameters such as cell mass, volume, and surfaces as they change through time. Because GLIM combines multiple intensity images corresponding to controlled phase offsets between laterally sheared beams, incoherent contributions from multiple scattering are implicitly cancelled during the phase reconstruction procedure. As the interfering beams traverse near identical paths, they remain comparable in power and interfere with optimal contrast. This key property lets us obtain tomographic parameters from wide field z-scans after simple numerical processing. Here we show our results on reconstructing tomograms of bovine embryos, characterizing the time-lapse growth of HeLa cells in 3D, and preliminary results on imaging much larger specimen such as brain slices.

Synthesis and magnetic properties of single-crystalline Na2-xMn8O16 nanorods

PubMed Central

2011-01-01

The synthesis of single-crystalline hollandite-type manganese oxides Na2-xMn8O16 nanorods by a simple molten salt method is reported for the first time. The nanorods were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and a superconducting quantum interference device magnetometer. The magnetic measurements indicated that the nanorods showed spin glass behavior and exchange bias effect at low temperatures. The low-temperature magnetic behaviors can be explained by the uncompensated spins on the surface of the nanorods. PMID:21711626

A hybrid scanning force and light microscope for surface imaging and three-dimensional optical sectioning in differential interference contrast.

PubMed

Stemmer, A

1995-04-01

The design of a scanned-cantilever-type force microscope is presented which is fully integrated into an inverted high-resolution video-enhanced light microscope. This set-up allows us to acquire thin optical sections in differential interference contrast (DIC) or polarization while the force microscope is in place. Such a hybrid microscope provides a unique platform to study how cell surface properties determine, or are affected by, the three-dimensional dynamic organization inside the living cell. The hybrid microscope presented in this paper has proven reliable and versatile for biological applications. It is the only instrument that can image a specimen by force microscopy and high-power DIC without having either to translate the specimen or to remove the force microscope. Adaptation of the design features could greatly enhance the suitability of other force microscopes for biological work.

Analysis of multi-channel microscopy: Spectral self-interference, multi-detector confocal and 4Pi systems

NASA Astrophysics Data System (ADS)

Davis, Brynmor J.

Fluorescence microscopy is an important and ubiquitous tool in biological imaging due to the high specificity with which fluorescent molecules can be attached to an organism and the subsequent nondestructive in-vivo imaging allowed. Focused-light microscopies allow three-dimensional fluorescence imaging but their resolution is restricted by diffraction. This effect is particularly limiting in the axial dimension as the diffraction-limited focal volume produced by a lens is more extensive along the optical axis than perpendicular to it. Approaches such as confocal microscopy and 4Pi microscopy have been developed to improve the axial resolution. Spectral Self-Interference Fluorescence Microscopy (SSFM) is another high-axial-resolution technique and is the principal subject of this dissertation. Nanometer-precision localization of a single fluorescent layer has been demonstrated using SSFM. This accuracy compares favorably with the axial resolutions given by confocal and 4Pi systems at similar operating parameters (these resolutions are approximately 350nm and 80nm respectively). This theoretical work analyzes the expected performance of the SSFM system when imaging a general object, i.e. an arbitrary fluorophore density function rather than a single layer. An existing model of SSFM is used in simulations to characterize the system's resolution. Several statistically-based reconstruction methods are applied to show that the expected resolution for SSFM is similar to 4Pi microscopy for a general object but does give very high localization accuracy when the object is known to consist of a limited number of layers. SSFM is then analyzed in a linear systems framework and shown to have strong connections, both physically and mathematically, to a multi-channel 4Pi microscope. Fourier-domain analysis confirms that SSFM cannot be expected to outperform this multi-channel 4Pi instrument. Differences between the channels in spatial-scanning, multi-channel microscopies are then exploited to show that such instruments can operate at a sub-Nyquist scanning rate but still produce images largely free of aliasing effects. Multi-channel analysis is also used to show how light typically discarded in confocal and 4Pi systems can be collected and usefully incorporated into the measured image.

Single shot damage mechanism of Mo/Si multilayer optics under intense pulsed XUV-exposure.

PubMed

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

2010-01-18

We investigated single shot damage of Mo/Si multilayer coatings exposed to the intense fs XUV radiation at the Free-electron LASer facility in Hamburg - FLASH. The interaction process was studied in situ by XUV reflectometry, time resolved optical microscopy, and "post-mortem" by interference-polarizing optical microscopy (with Nomarski contrast), atomic force microscopy, and scanning transmission electron microcopy. An ultrafast molybdenum silicide formation due to enhanced atomic diffusion in melted silicon has been determined to be the key process in the damage mechanism. The influence of the energy diffusion on the damage process was estimated. The results are of significance for the design of multilayer optics for a new generation of pulsed (from atto- to nanosecond) XUV sources.

Nanoscale imaging of photocurrent enhancement by resonator array photovoltaic coatings.

PubMed

Ha, Dongheon; Yoon, Yohan; Zhitenev, Nikolai B

2018-04-06

Nanoscale surface patterning commonly used to increase absorption of solar cells can adversely impact the open-circuit voltage due to increased surface area and recombination. Here, we demonstrate absorptivity and photocurrent enhancement using silicon dioxide (SiO 2 ) nanosphere arrays on a gallium arsenide (GaAs) solar cell that do not require direct surface patterning. Due to the combined effects of thin-film interference and whispering gallery-like resonances within nanosphere arrays, there is more than 20% enhancement in both absorptivity and photocurrent. To determine the effect of the resonance coupling between nanospheres, we perform a scanning photocurrent microscopy based on a near-field scanning optical microscopy measurement and find a substantial local photocurrent enhancement. The nanosphere-based antireflection coating (ARC), made by the Meyer rod rolling technique, is a scalable and a room-temperature process; and, can replace the conventional thin-film-based ARCs requiring expensive high-temperature vacuum deposition.

Nanoscale imaging of photocurrent enhancement by resonator array photovoltaic coatings

NASA Astrophysics Data System (ADS)

Ha, Dongheon; Yoon, Yohan; Zhitenev, Nikolai B.

2018-04-01

Nanoscale surface patterning commonly used to increase absorption of solar cells can adversely impact the open-circuit voltage due to increased surface area and recombination. Here, we demonstrate absorptivity and photocurrent enhancement using silicon dioxide (SiO2) nanosphere arrays on a gallium arsenide (GaAs) solar cell that do not require direct surface patterning. Due to the combined effects of thin-film interference and whispering gallery-like resonances within nanosphere arrays, there is more than 20% enhancement in both absorptivity and photocurrent. To determine the effect of the resonance coupling between nanospheres, we perform a scanning photocurrent microscopy based on a near-field scanning optical microscopy measurement and find a substantial local photocurrent enhancement. The nanosphere-based antireflection coating (ARC), made by the Meyer rod rolling technique, is a scalable and a room-temperature process; and, can replace the conventional thin-film-based ARCs requiring expensive high-temperature vacuum deposition.

Holographic maps of quasiparticle interference

NASA Astrophysics Data System (ADS)

Dalla Torre, Emanuele G.; He, Yang; Demler, Eugene

2016-11-01

The analysis of Fourier-transformed scanning tunnelling microscopy images with subatomic resolution is a common tool for studying the properties of quasiparticle excitations in strongly correlated materials. Although Fourier amplitudes are generally complex valued, earlier analysis primarily focused on their absolute values. Their complex phases were often deemed random, and thus irrelevant, due to the unknown positions of the impurities in the sample. Here we show how to factor out these random phases by analysing overlaps between Fourier amplitudes that differ by reciprocal lattice vectors. The resulting holographic maps provide important and previously unknown information about the electronic structures. When applied to superconducting cuprates, our method solves a long-standing puzzle of the dichotomy between equivalent wavevectors. We show that d-wave Wannier functions of the conduction band provide a natural explanation for experimental results that were interpreted as evidence for competing unconventional charge modulations. Our work opens a new pathway to identify the nature of electronic states in scanning tunnelling microscopy.

Scanning Tunneling Microscopy Observation of Phonon Condensate

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

Altfeder, Igor; Balatsky, Alexander V.; Voevodin, Andrey A.

Using quantum tunneling of electrons into vibrating surface atoms, phonon oscillations can be observed on the atomic scale. Phonon interference patterns with unusually large signal amplitudes have been revealed by scanning tunneling microscopy in intercalated van der Waals heterostructures. Our results show that the effective radius of these phonon quasi-bound states, the real-space distribution of phonon standing wave amplitudes, the scattering phase shifts, and the nonlinear intermode coupling strongly depend on the presence of defect-induced scattering resonance. The observed coherence of these quasi-bound states most likely arises from phase- and frequency-synchronized dynamics of all phonon modes, and indicates the formationmore » of many-body condensate of optical phonons around resonant defects. We found that increasing the strength of the scattering resonance causes the increase of the condensate droplet radius without affecting the condensate fraction inside it. The condensate can be observed at room temperature.« less

Scanning Tunneling Microscopy Observation of Phonon Condensate

PubMed Central

Altfeder, Igor; Voevodin, Andrey A.; Check, Michael H.; Eichfeld, Sarah M.; Robinson, Joshua A.; Balatsky, Alexander V.

2017-01-01

Using quantum tunneling of electrons into vibrating surface atoms, phonon oscillations can be observed on the atomic scale. Phonon interference patterns with unusually large signal amplitudes have been revealed by scanning tunneling microscopy in intercalated van der Waals heterostructures. Our results show that the effective radius of these phonon quasi-bound states, the real-space distribution of phonon standing wave amplitudes, the scattering phase shifts, and the nonlinear intermode coupling strongly depend on the presence of defect-induced scattering resonance. The observed coherence of these quasi-bound states most likely arises from phase- and frequency-synchronized dynamics of all phonon modes, and indicates the formation of many-body condensate of optical phonons around resonant defects. We found that increasing the strength of the scattering resonance causes the increase of the condensate droplet radius without affecting the condensate fraction inside it. The condensate can be observed at room temperature. PMID:28225066

Scanning Tunneling Microscopy Observation of Phonon Condensate

DOE PAGES

Altfeder, Igor; Balatsky, Alexander V.; Voevodin, Andrey A.; ...

2017-02-22

Using quantum tunneling of electrons into vibrating surface atoms, phonon oscillations can be observed on the atomic scale. Phonon interference patterns with unusually large signal amplitudes have been revealed by scanning tunneling microscopy in intercalated van der Waals heterostructures. Our results show that the effective radius of these phonon quasi-bound states, the real-space distribution of phonon standing wave amplitudes, the scattering phase shifts, and the nonlinear intermode coupling strongly depend on the presence of defect-induced scattering resonance. The observed coherence of these quasi-bound states most likely arises from phase- and frequency-synchronized dynamics of all phonon modes, and indicates the formationmore » of many-body condensate of optical phonons around resonant defects. We found that increasing the strength of the scattering resonance causes the increase of the condensate droplet radius without affecting the condensate fraction inside it. The condensate can be observed at room temperature.« less

Microscopy using source and detector arrays

NASA Astrophysics Data System (ADS)

Sheppard, Colin J. R.; Castello, Marco; Vicidomini, Giuseppe; Duocastella, Martí; Diaspro, Alberto

2016-03-01

There are basically two types of microscope, which we call conventional and scanning. The former type is a full-field imaging system. In the latter type, the object is illuminated with a probe beam, and a signal detected. We can generalize the probe to a patterned illumination. Similarly we can generalize the detection to a patterned detection. Combining these we get a range of different modalities: confocal microscopy, structured illumination (with full-field imaging), spinning disk (with multiple illumination points), and so on. The combination allows the spatial frequency bandwidth of the system to be doubled. In general we can record a four dimensional (4D) image of a 2D object (or a 6D image from a 3D object, using an acoustic tuneable lens). The optimum way to directly reconstruct the resulting image is by image scanning microscopy (ISM). But the 4D image is highly redundant, so deconvolution-based approaches are also relevant. ISM can be performed in fluorescence, bright field or interference microscopy. Several different implementations have been described, with associated advantages and disadvantages. In two-photon microscopy, the illumination and detection point spread functions are very different. This is also the case when using pupil filters or when there is a large Stokes shift.

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.

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

PubMed Central

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

2012-01-01

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

Evaluation of Delamination of X80 Pipeline Steel Coating Under Alternating Stray Current Via Scanning Electrochemical Microscopy

NASA Astrophysics Data System (ADS)

Wang, Xinhua; Liu, Qiang; Chun, Yingchun; Li, Yingchao; Wang, Zuquan

2018-04-01

The delamination of epoxy coating on X80 pipeline steel was evaluated under various stray alternating current (AC) interferences (0-300 A/m2). Qualitative and quantitative analyses were carried out using scanning electrochemical microscopy (SECM), electrochemical impedance spectroscopy (EIS), and three-dimensional digital microscopy. The results show that the SECM current is directly proportional to the soaking time and applied current density. The variation in SECM current curve shape indicates the delamination distance of epoxy coatings at the defect area. The depths of corrosion pits at 50, 100, and 300 A/m2 stray currents were 140, 160, and 240 μm, respectively. The corrosion pits also became wider with increasing current densities. With increasing stray AC densities, both the coating delamination and pit depth became more severe at the same soaking time. The EIS results show that the change in impedance was not significant without stray current, whereas the impedance first decreased and then increased when stray current was applied. These results are consistent with the SECM measurements.

Self-assembly approach toward magnetic silica-type nanoparticles of different shapes from reverse block copolymer mesophases.

PubMed

Garcia, Carlos B W; Zhang, Yuanming; Mahajan, Surbhi; DiSalvo, Francis; Wiesner, Ulrich

2003-11-05

In the present study poly(isoprene-block-ethylene oxide), PI-b-PEO, block copolymers are used to structure iron oxide and silica precursors into reverse mesophases, which upon dissolution of the organic matrix lead to well-defined nanoparticles of spheres, cylinders, and plates based on the original structure of the mesophase prepared. The hybrid mesophases with sphere, cylinder, and lamellar morphologies containing the inorganic components in the minority phases are characterized through a combination of small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and electron energy loss spectroscopy (EELS). After heat treatments the respective nanoparticles on mica surfaces are characterized by scanning force microscopy (SFM). X-ray diffraction (XRD) and superconducting quantum interference device (SQUID) magnetometer measurements are performed to demonstrate that the heat treatment leads to the formation of a magnetic gamma-Fe2O3 crystalline phase within the amorphous aluminosilicate. The results pave the way to functional, i.e., magnetic nanoparticles where the size, shape, and iron oxide concentration can be controlled opening a range of possible applications.

Doping dependence of the anisotropic quasiparticle interference in NaFe(1-x)Co(x)As iron-based superconductors.

PubMed

Cai, Peng; Ruan, Wei; Zhou, Xiaodong; Ye, Cun; Wang, Aifeng; Chen, Xianhui; Lee, Dung-Hai; Wang, Yayu

2014-03-28

We use scanning tunneling microscopy to investigate the doping dependence of quasiparticle interference (QPI) in NaFe1-xCoxAs iron-based superconductors. The goal is to study the relation between nematic fluctuations and Cooper pairing. In the parent and underdoped compounds, where fourfold rotational symmetry is broken macroscopically, the QPI patterns reveal strong rotational anisotropy. At optimal doping, however, the QPI patterns are always fourfold symmetric. We argue this implies small nematic susceptibility and, hence, insignificant nematic fluctuation in optimally doped iron pnictides. Since TC is the highest this suggests nematic fluctuation is not a prerequistite for strong Cooper pairing.

Scanning Hall probe microscopy of a diluted magnetic semiconductor

NASA Astrophysics Data System (ADS)

Kweon, Seongsoo; Samarth, Nitin; de Lozanne, Alex

2009-05-01

We have measured the micromagnetic properties of a diluted magnetic semiconductor as a function of temperature and applied field with a scanning Hall probe microscope built in our laboratory. The design philosophy for this microscope and some details are described. The samples analyzed in this work are Ga0.94Mn0.06As films grown by molecular beam epitaxy. We find that the magnetic domains are 2-4 μm wide and fairly stable with temperature. Magnetic clusters are observed above TC, which we ascribe to MnAs defects too small and sparse to be detected by a superconducting quantum interference device magnetometer.

Quasiparticle scattering in type-II Weyl semimetal MoTe2

NASA Astrophysics Data System (ADS)

Lin, Chun-Liang; Arafune, Ryuichi; Minamitani, Emi; Kawai, Maki; Takagi, Noriaki

2018-03-01

The electronic structure of type-II Weyl semimetal molybdenum ditelluride (MoTe2) is studied by using scanning tunneling microscopy and density functional theory calculations. Through measuring energy-dependent quasiparticle interference (QPI) patterns with a cryogenic scanning tunneling microscope, several characteristic features are found in the QPI patterns. Two of them arise from the Weyl semimetal nature; one is the topological Fermi arc surface state and the other can be assigned to be a Weyl point. The remaining structures are derived from the scatterings relevant to the bulk electronic states. The findings lead to further understanding of the topological electronic structure of type-II Weyl semimetal MoTe2.

Quasiparticle scattering in type-II Weyl semimetal MoTe2.

PubMed

Lin, Chun-Liang; Arafune, Ryuichi; Minamitani, Emi; Kawai, Maki; Takagi, Noriaki

2018-02-15

The electronic structure of type-II Weyl semimetal molybdenum ditelluride (MoTe 2 ) is studied by using scanning tunneling microscopy and density functional theory calculations. Through measuring energy-dependent quasiparticle interference (QPI) patterns with a cryogenic scanning tunneling microscope, several characteristic features are found in the QPI patterns. Two of them arise from the Weyl semimetal nature; one is the topological Fermi arc surface state and the other can be assigned to be a Weyl point. The remaining structures are derived from the scatterings relevant to the bulk electronic states. The findings lead to further understanding of the topological electronic structure of type-II Weyl semimetal MoTe 2 .

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

PubMed

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

2011-01-03

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

Self-interference fluorescence microscopy with three-phase detection for depth-resolved confocal epi-fluorescence imaging.

PubMed

Braaf, Boy; de Boer, Johannes F

2017-03-20

Three-dimensional confocal fluorescence imaging of in vivo tissues is challenging due to sample motion and limited imaging speeds. In this paper a novel method is therefore presented for scanning confocal epi-fluorescence microscopy with instantaneous depth-sensing based on self-interference fluorescence microscopy (SIFM). A tabletop epi-fluorescence SIFM setup was constructed with an annular phase plate in the emission path to create a spectral self-interference signal that is phase-dependent on the axial position of a fluorescent sample. A Mach-Zehnder interferometer based on a 3 × 3 fiber-coupler was developed for a sensitive phase analysis of the SIFM signal with three photon-counter detectors instead of a spectrometer. The Mach-Zehnder interferometer created three intensity signals that alternately oscillated as a function of the SIFM spectral phase and therefore encoded directly for the axial sample position. Controlled axial translation of fluorescent microsphere layers showed a linear dependence of the SIFM spectral phase with sample depth over axial image ranges of 500 µm and 80 µm (3.9 × Rayleigh range) for 4 × and 10 × microscope objectives respectively. In addition, SIFM was in good agreement with optical coherence tomography depth measurements on a sample with indocyanine green dye filled capillaries placed at multiple depths. High-resolution SIFM imaging applications are demonstrated for fluorescence angiography on a dye-filled capillary blood vessel phantom and for autofluorescence imaging on an ex vivo fly eye.

Molecular reorientation in assembled CO structures and contrast inversion in STM

NASA Astrophysics Data System (ADS)

Niemi, Eeva; Nieminen, Jouko

2004-10-01

Recent scanning tunneling microscopy experiments [S. Zöphel, J. Repp, G. Meyer, K.-H. Rieder, Chem. Phys. Lett. 310 (1999) 145; A.J. Heinrich, C.P. Lutz, J.A. Gupta, D.M. Eigler, Science 298 (2002) 1381] for CO on Cu(1 1 1) and Cu(2 1 1) surfaces show CO monomers as dark depressions, whereas dimers and trimers appear as bright patterns. The dark image of a monomer has been shown to result from a destructive interference between two tunneling paths [J. Nieminen, E. Niemi, K.-H. Rieder, Surf. Sci. 552 (2004) L47]. In this Letter, we show how switching between tunneling channels within the through molecule path can be induced by reorientation of a molecule. Hence, a destructive interference between through vacuum and through molecule paths can be reversed into constructive interference by manipulating the adsorbate geometry.

Quasiparticle Interference Studies of Quantum Materials.

PubMed

Avraham, Nurit; Reiner, Jonathan; Kumar-Nayak, Abhay; Morali, Noam; Batabyal, Rajib; Yan, Binghai; Beidenkopf, Haim

2018-06-03

Exotic electronic states are realized in novel quantum materials. This field is revolutionized by the topological classification of materials. Such compounds necessarily host unique states on their boundaries. Scanning tunneling microscopy studies of these surface states have provided a wealth of spectroscopic characterization, with the successful cooperation of ab initio calculations. The method of quasiparticle interference imaging proves to be particularly useful for probing the dispersion relation of the surface bands. Herein, how a variety of additional fundamental electronic properties can be probed via this method is reviewed. It is demonstrated how quasiparticle interference measurements entail mesoscopic size quantization and the electronic phase coherence in semiconducting nanowires; helical spin protection and energy-momentum fluctuations in a topological insulator; and the structure of the Bloch wave function and the relative insusceptibility of topological electronic states to surface potential in a topological Weyl semimetal. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Imaging electron wave functions inside open quantum rings.

PubMed

Martins, F; Hackens, B; Pala, M G; Ouisse, T; Sellier, H; Wallart, X; Bollaert, S; Cappy, A; Chevrier, J; Bayot, V; Huant, S

2007-09-28

Combining scanning gate microscopy (SGM) experiments and simulations, we demonstrate low temperature imaging of the electron probability density |Psi|(2)(x,y) in embedded mesoscopic quantum rings. The tip-induced conductance modulations share the same temperature dependence as the Aharonov-Bohm effect, indicating that they originate from electron wave function interferences. Simulations of both |Psi|(2)(x,y) and SGM conductance maps reproduce the main experimental observations and link fringes in SGM images to |Psi|(2)(x,y).

Interferences in electrochemical hydride generation of hydrogen selenide

NASA Astrophysics Data System (ADS)

Bolea, E.; Laborda, F.; Belarra, M. A.; Castillo, J. R.

2001-12-01

Interferences from Cu(II), Zn(II), Pt(IV), As(III) and nitrate on electrochemical hydride generation of hydrogen selenide were studied using a tubular flow-through generator, flow injection sample introduction and quartz tube atomic absorption spectrometry. Comparison with conventional chemical generation using tetrahydroborate was also performed. Lead and reticulated vitreous carbon (RVC), both in particulate form, were used as cathode materials. Signal supressions up to 60-75%, depending on the cathode material, were obtained in the presence of up to 200 mg l-1 of nitrate due to the competitive reduction of the anion. Interference from As(III) was similar in electrochemical and chemical generation, being related to the quartz tube atomization process. Zinc did not interfere up to Se/Zn ratios 1:100, whereas copper and platinum showed suppression levels up to 50% for Se/interferent ratios 1:100. Total signal suppression was observed in presence of Se/Cu ratios 1:100 when RVC cathodes were used. No memory effects were observed in any case. Scanning electron microscopy and squared wave voltametry studies supported the interference mechanism based on the decomposition of the hydride on the dispersed particles of the reduced metal.

Visualizing the near-field coupling and interference of bonding and anti-bonding modes in infrared dimer nanoantennas.

PubMed

Alonso-González, Pablo; Albella, Pablo; Golmar, Federico; Arzubiaga, Libe; Casanova, Félix; Hueso, Luis E; Aizpurua, Javier; Hillenbrand, Rainer

2013-01-14

We directly visualize and identify the capacitive coupling of infrared dimer antennas in the near field by employing scattering-type scanning near-field optical microscopy (s-SNOM). The coupling is identified by (i) resolving the strongly enhanced nano-localized near fields in the antenna gap and by (ii) tracing the red shift of the dimer resonance when compared to the resonance of the single antenna constituents. Furthermore, by modifying the illumination geometry we break the symmetry, providing a means to excite both the bonding and the "dark" anti-bonding modes. By spectrally matching both modes, their interference yields an enhancement or suppression of the near fields at specific locations, which could be useful in nanoscale coherent control applications.

Topographic profiling and refractive-index analysis by use of differential interference contrast with bright-field intensity and atomic force imaging.

PubMed

Axelrod, Noel; Radko, Anna; Lewis, Aaron; Ben-Yosef, Nissim

2004-04-10

A methodology is described for phase restoration of an object function from differential interference contrast (DIC) images. The methodology involves collecting a set of DIC images in the same plane with different bias retardation between the two illuminating light components produced by a Wollaston prism. These images, together with one conventional bright-field image, allows for reduction of the phase deconvolution restoration problem from a highly complex nonlinear mathematical formulation to a set of linear equations that can be applied to resolve the phase for images with a relatively large number of pixels. Additionally, under certain conditions, an on-line atomic force imaging system that does not interfere with the standard DIC illumination modes resolves uncertainties in large topographical variations that generally lead to a basic problem in DIC imaging, i.e., phase unwrapping. Furthermore, the availability of confocal detection allows for a three-dimensional reconstruction with high accuracy of the refractive-index measurement of the object that is to be imaged. This has been applied to reconstruction of the refractive index of an arrayed waveguide in a region in which a defect in the sample is present. The results of this paper highlight the synergism of far-field microscopies integrated with scanned probe microscopies and restoration algorithms for phase reconstruction.

A Low Temperature Scanning Force Microscope with a Vertical Cantilever and Interferometric Detection Scheme

NASA Astrophysics Data System (ADS)

Kim, Jeehoon; Williams, T. L.; Chu, Sang Lin; Korre, Hasan; Chalfin, Max; Hoffman, J. E.

2008-03-01

We have developed a fiber-optic interferometry system with a vertical cantilever for scanning force microscopy. A lens, mounted on a Pan-type walker, was used to collect the interference signal in the cavity between the cantilever and the single mode fiber. This vertical geometry has several advantages: (1) it is directly sensitive to lateral forces; (2) low spring constant vertical cantilevers may allow increased force sensitivity by solving the ``snap-in'' problem that occurs with soft horizontal cantilevers. We have sharpened vertical cantilevers by focused ion beam (FIB), achieving a tip radius of 20 nm. We will show test results of a magnetic force microscope (MFM) with this vertical cantilever system.

Imaging electronic states on topological semimetals using scanning tunneling microscopy

DOE PAGES

Gyenis, András; Inoue, Hiroyuki; Jeon, Sangjun; ...

2016-10-18

Following the intense studies on topological insulators, significant efforts have recently been devoted to the search for gapless topological systems. These materials not only broaden the topological classification of matter but also provide a condensed matter realization of various relativistic particles and phenomena previously discussed mainly in high energy physics. Weyl semimetals host massless, chiral, low-energy excitations in the bulk electronic band structure, whereas a symmetry protected pair of Weyl fermions gives rise to massless Dirac fermions.Weemployed scanning tunneling microscopy/spectroscopy to explore the behavior of electronic states both on the surface and in the bulk of topological semimetal phases. Bymore » mapping the quasiparticle interference (QPI) and emerging Landau levels at high magnetic field in Dirac semimetals Cd 3As 2 and Na 3Bi, we observed extended Dirac-like bulk electronic bands. QPI imaged on Weyl semimetal TaAs demonstrated the predicted momentum dependent delocalization of Fermi arc surface states in the vicinity of the surface projected Weyl nodes.« less

Tribological performance of sub-100-nm femtosecond laser-induced periodic surface structures on titanium

NASA Astrophysics Data System (ADS)

Bonse, J.; Höhm, S.; Koter, R.; Hartelt, M.; Spaltmann, D.; Pentzien, S.; Rosenfeld, A.; Krüger, J.

2016-06-01

Sub-100-nm laser-induced periodic surface structures (LIPSS) were processed on bulk titanium (Ti) surfaces by femtosecond laser pulse irradiation in air (30 fs pulse duration, 790 nm wavelength). The laser peak fluence, the spatial spot overlap, and the number of overscans were optimized in a sample-scanning geometry in order to obtain large surface areas (5 mm × 5 mm) covered homogeneously by the LIPSS. The laser-processed regions were characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). The friction coefficient of the nanostructured surfaces was tested during 1000 cycles under reciprocal sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel, both in paraffin oil and in engine oil used as lubricants. Subsequently, the corresponding wear tracks were qualified by OM, SEM, and energy dispersive X-ray analyses (EDX). The results of the tribological tests are discussed and compared to that obtained for near wavelength-sized fs-LIPSS, processed under somewhat different irradiation conditions. Some constraints for a beneficial effect of LIPSS on the tribological performance are provided.

Nafion covered core-shell structured Fe3O4@graphene nanospheres modified electrode for highly selective detection of dopamine.

PubMed

Zhang, Wuxiang; Zheng, Jianzhong; Shi, Jiangu; Lin, Zhongqiu; Huang, Qitong; Zhang, Hanqiang; Wei, Chan; Chen, Jianhua; Hu, Shirong; Hao, Aiyou

2015-01-01

Nafion covered core-shell structured Fe3O4@graphene nanospheres (GNs) modified glassy carbon electrode (GCE) was successfully prepared and used for selective detection dopamine. Firstly, the characterizations of hydro-thermal synthesized Fe3O4@GNs were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. Then Fe3O4@GNs/Nafion modified electrode exhibited excellent electrocatalytic activity toward the oxidations of dopamine (DA). The interference test showed that the coexisted ascorbic acid (AA) and uric acid (UA) had no electrochemical interference toward DA. Under the optimum conditions, the broad linear relationship was obtained in the experimental concentration from 0.020 μM to 130.0 μM with the detection limit (S/N=3) of 0.007 μM. Furthermore, the core-shell structured Fe3O4@GNs/Nafion/GCE was applied to the determination of DA in real samples and satisfactory results were got, which could provide a promising platform to develop excellent biosensor for detecting DA. Copyright © 2014 Elsevier B.V. All rights reserved.

Direct laser interference patterning of ophthalmic polydimethylsiloxane (PDMS) polymers

NASA Astrophysics Data System (ADS)

Sola, D.; Lavieja, C.; Orera, A.; Clemente, M. J.

2018-07-01

The inscription of diffractive elements in ophthalmic polymers and ocular tissues to induce refractive index changes is of great interest in the fields of Optics and Ophthalmology. In this work fabrication of linear periodic patterns in polydimethylsiloxane (PDMS) intraocular lenses by means of the direct laser interference patterning (DLIP) technique was studied. A Q-Switch Nd:YAG laser coupled to second and third harmonic modules emitting linearly polarized 4 ns pulses at 355 nm with 20 Hz repetition rate was used as the laser source. Laser processing parameters were modified to produce the linear patterns. Processed samples were characterized by means of optical confocal microscopy, Scanning Electron Microscopy SEM, Energy Dispersive X-ray Spectroscopy EDX, Attenuated Total Reflectance-Infrared Spectroscopy ATR-FTIR, and Raman Spectroscopy. Depending on the laser parameters both photo-thermal and photo-chemical damage were observed in the DLIP irradiated areas. Finally, diffractive techniques were used to characterize the diffraction gratings inscribed in the samples resulting in a refractive index change of 1.9 × 10-2 under illumination of a 632.8 nm He-Ne laser.

Imaging quantum transport using scanning gate microscopy

NASA Astrophysics Data System (ADS)

Hackens, Benoit

2014-03-01

Quantum transport in nanodevices is usually probed thanks to measurements of the electrical resistance or conductance, which lack the spatial resolution necessary to probe electron behaviour inside the devices. In this talk, we will show that scanning gate microscopy (SGM) yields real-space images of quantum transport phenomena inside archetypal mesoscopic devices such as quantum point contacts and quantum rings. We will first discuss the SGM technique, which is based on mapping the electrical conductance of a device as an electrically-biased sharp metallic tip scans in its vicinity. With SGM, we demonstrated low temperature imaging of the electron probability density and interferences in embedded mesoscopic quantum rings [B. Hackens et al., Nat. Phys. 2, 826 (2006)]. At high magnetic field, thanks to the SGM conductance maps, one can decrypt complex transport phenomena such as tunneling between quantum Hall edge state, either direct or through localized states [B. Hackens et al., Nat. Comm. 1, 39 (2010)]. Moreover, the technique also allows to perform local spectroscopy of electron transport through selected localized states [F. Martins et al., New J. of Phys. 15, 013049 (2013); F. Martins et al., Sci. Rep. 3, 1416 (2013)]. Overall, these examples show that scanning gate microscopy is a powerful tool for imaging charge carrier behavior inside devices fabricated from a variety of materials, and opens the way towards a more intimate manipulation of charge and quasiparticle transport. This work was performed in collaboration with F. Martins, S. Faniel, B. Brun, M. Pala, X. Wallart, L. Desplanque, B. Rosenow, T. Ouisse, H. Sellier, S. Huant and V. Bayot.

Bacterial cell identification in differential interference contrast microscopy images.

PubMed

Obara, Boguslaw; Roberts, Mark A J; Armitage, Judith P; Grau, Vicente

2013-04-23

Microscopy image segmentation lays the foundation for shape analysis, motion tracking, and classification of biological objects. Despite its importance, automated segmentation remains challenging for several widely used non-fluorescence, interference-based microscopy imaging modalities. For example in differential interference contrast microscopy which plays an important role in modern bacterial cell biology. Therefore, new revolutions in the field require the development of tools, technologies and work-flows to extract and exploit information from interference-based imaging data so as to achieve new fundamental biological insights and understanding. We have developed and evaluated a high-throughput image analysis and processing approach to detect and characterize bacterial cells and chemotaxis proteins. Its performance was evaluated using differential interference contrast and fluorescence microscopy images of Rhodobacter sphaeroides. Results demonstrate that the proposed approach provides a fast and robust method for detection and analysis of spatial relationship between bacterial cells and their chemotaxis proteins.

Layer-by-layer assembled hydrophobic coatings for cellulose nanofibril films and textiles, made of polylysine and natural wax particles.

PubMed

Forsman, Nina; Lozhechnikova, Alina; Khakalo, Alexey; Johansson, Leena-Sisko; Vartiainen, Jari; Österberg, Monika

2017-10-01

Herein we present a simple method to render cellulosic materials highly hydrophobic while retaining their breathability and moisture buffering properties, thus allowing for their use as functional textiles. The surfaces are coated via layer-by-layer deposition of two natural components, cationic poly-l-lysine and anionic carnauba wax particles. The combination of multiscale roughness, open film structure, and low surface energy of wax colloids, resulted in long-lasting superhydrophobicity on cotton surface already after two bilayers. Atomic force microscopy, interference microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy were used to decouple structural effects from changes in surface energy. Furthermore, the effect of thermal annealing on the coating was evaluated. The potential of this simple and green approach to enhance the use of natural cellulosic materials is discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Phase Sensitive Demodulation in Multiphoton Microscopy

NASA Astrophysics Data System (ADS)

Fisher, Walt G.; Piston, David W.; Wachter, Eric A.

2002-06-01

Multiphoton laser scanning microscopy offers advantages in depth of penetration into intact samples over other optical sectioning techniques. To achieve these advantages it is necessary to detect the emitted light without spatial filtering. In this nondescanned (nonconfocal) approach, ambient room light can easily contaminate the signal, forcing experiments to be performed in absolute darkness. For multiphoton microscope systems employing mode-locked lasers, signal processing can be used to reduce such problems by taking advantage of the pulsed characteristics of such lasers. Specifically, by recovering fluorescence generated at the mode-locked frequency, interference from stray light and other ambient noise sources can be significantly reduced. This technology can be adapted to existing microscopes by inserting demodulation circuitry between the detector and data collection system. The improvement in signal-to-noise ratio afforded by this approach yields a more robust microscope system and opens the possibility of moving multiphoton microscopy from the research lab to more demanding settings, such as the clinic.

Measurement of Trace Constituents by Electron-Excited X-Ray Microanalysis with Energy-Dispersive Spectrometry.

PubMed

Newbury, Dale E; Ritchie, Nicholas W M

2016-06-01

Electron-excited X-ray microanalysis performed with scanning electron microscopy and energy-dispersive spectrometry (EDS) has been used to measure trace elemental constituents of complex multielement materials, where "trace" refers to constituents present at concentrations below 0.01 (mass fraction). High count spectra measured with silicon drift detector EDS were quantified using the standards/matrix correction protocol embedded in the NIST DTSA-II software engine. Robust quantitative analytical results for trace constituents were obtained from concentrations as low as 0.000500 (mass fraction), even in the presence of significant peak interferences from minor (concentration 0.01≤C≤0.1) and major (C>0.1) constituents. Limits of detection as low as 0.000200 were achieved in the absence of peak interference.

Theoretical analysis of a dual-probe scanning tunneling microscope setup on graphene.

PubMed

Settnes, Mikkel; Power, Stephen R; Petersen, Dirch H; Jauho, Antti-Pekka

2014-03-07

Experimental advances allow for the inclusion of multiple probes to measure the transport properties of a sample surface. We develop a theory of dual-probe scanning tunneling microscopy using a Green's function formalism, and apply it to graphene. Sampling the local conduction properties at finite length scales yields real space conductance maps which show anisotropy for pristine graphene systems and quantum interference effects in the presence of isolated impurities. Spectral signatures in the Fourier transforms of real space conductance maps include characteristics that can be related to different scattering processes. We compute the conductance maps of graphene systems with different edge geometries or height fluctuations to determine the effects of nonideal graphene samples on dual-probe measurements.

Quasiparticle interference in the heavy-fermion superconductor CeCoIn5

NASA Astrophysics Data System (ADS)

Akbari, Alireza; Thalmeier, Peter; Eremin, Ilya

2011-10-01

We investigate the quasiparticle interference in the heavy fermion superconductor CeCoIn5 as a direct method to confirm the d-wave gap symmetry. The ambiguity between dxy and dx2-y2 symmetry remaining from earlier specific heat and thermal transport investigations has been resolved in favor of the latter by the observation of a spin resonance that can occur only in dx2-y2 symmetry. However, these methods are all indirect and depend considerably on theoretical interpretation. Here we propose that quasiparticle interference (QPI) spectroscopy by scanning tunneling microscopy (STM) can give a direct fingerprint of the superconducting gap in real space that may lead to a definite conclusion on its symmetry for CeCoIn5 and related 115 compounds. The QPI pattern for both magnetic and nonmagnetic impurities is calculated for the possible d-wave symmetries and characteristic differences are found that may be identified by use of the STM method.

LASER BIOLOGY: Peculiarities of studying an isolated neuron by the method of laser interference microscopy

NASA Astrophysics Data System (ADS)

Yusipovich, Alexander I.; Novikov, Sergey M.; Kazakova, Tatiana A.; Erokhova, Liudmila A.; Brazhe, Nadezda A.; Lazarev, Grigory L.; Maksimov, Georgy V.

2006-09-01

Actual aspects of using a new method of laser interference microscopy (LIM) for studying nerve cells are discussed. The peculiarities of the LIM display of neurons are demonstrated by the example of isolated neurons of a pond snail Lymnaea stagnalis. A comparative analysis of the images of the cell and subcellular structures of a neuron obtained by the methods of interference microscopy, optical transmission microscopy, and confocal microscopy is performed. Various aspects of the application of LIM for studying the lateral dimensions and internal structure of the cytoplasm and organelles of a neuron in cytology and cell physiology are discussed.

Tribological performance of femtosecond laser-induced periodic surface structures on titanium and a high toughness bearing steel

NASA Astrophysics Data System (ADS)

Bonse, J.; Koter, R.; Hartelt, M.; Spaltmann, D.; Pentzien, S.; Höhm, S.; Rosenfeld, A.; Krüger, J.

2015-05-01

Laser-induced periodic surface structures (LIPSS, ripples) were processed on steel (X30CrMoN15-1) and titanium (Ti) surfaces by irradiation in air with linear polarized femtosecond laser pulses with a pulse duration of 30 fs at 790 nm wavelength. For the processing of large LIPSS covered surface areas (5 mm × 5 mm), the laser fluence and the spatial spot overlap were optimized in a sample-scanning geometry. The laser-processed surfaces were characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). Spatial LIPSS periods between 450 and 600 nm were determined. The nanostructured surface regions were tribologically tested under reciprocal sliding conditions against a 10-mm diameter ball of hardened 100Cr6 steel. Paraffin oil and engine oil were used as lubricants for 1000 sliding cycles at 1 Hz with a normal load of 1.0 N. The corresponding wear tracks were analyzed by OM and SEM. In particular cases, the laser-generated nanostructures endured the tribological treatment. Simultaneously, a significant reduction of the friction coefficient and the wear was observed in the laser-irradiated (LIPSS-covered) areas when compared to the non-irradiated surface. The experiments reveal the potential benefit of laser surface structuring for tribological applications.

Microscopic analysis of Spodoptera frugiperda (Lepidoptera: Noctuidae) embryonic development before and after treatment with azadirachtin, lufenuron, and deltamethrin.

PubMed

Correia, Alicely A; Wanderley-Teixeira, Valéria; Teixeira, Alvaro A C; Oliveira, José V; Gonçalves, Gabriel G A; Cavalcanti, MaríIia G S; Brayner, Fábio A; Alves, Luiz C

2013-04-01

The botanical insecticides, growth regulators, and pyrethroids have an effect on the biology of Spodoptera frugiperda (Smith). However, no emphasis has been given to the effect of these insecticides on embryonic development of insects, in histological level. Thus, this research aimed to examine by light and scanning electron microscopy S. frugiperda eggs and to describe the embryonic development, before and after immersion treatment, using commercial concentrations and lower concentrations than commercial ones, of the compounds lufenuron (Match), azadirachtin (AzaMax), and deltamethrin (Decis-positive control). For light microscopy semithin sections of eggs were used, and for scanning electron microscopy, images of the surface of eggs, treated and untreated with insecticides. The morphological characteristics of S. frugiperda eggs, in general, were similar to those described in the literature for most of the insects in the order Lepidoptera. Spherical eggs slightly flattened at the poles, with chorion, yolk, vitelline membrane, and embryo formation. In both microscopic analysis, we observed that insecticides acted immediately and independent of concentration, resulting absence, or incomplete embryo, presented yolk granules widely dispersed, without vitellophage formation, chorion disintegration, disorganized blastoderm, presenting vacuoles, yolk region with amorphous cells, and formation of completely uncharacterized appendages. Thus, we conclude that the compounds lufenuron and azadirachtin interfere on S. frugiperda embryonic development.

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

Synthesis and characterization of dextran-coated iron oxide nanoparticles

NASA Astrophysics Data System (ADS)

Predescu, Andra Mihaela; Matei, Ecaterina; Berbecaru, Andrei Constantin; Pantilimon, Cristian; Drăgan, Claudia; Vidu, Ruxandra; Predescu, Cristian; Kuncser, Victor

2018-03-01

Synthesis and characterization of iron oxide nanoparticles coated with a large molar weight dextran for environmental applications are reported. The first experiments involved the synthesis of iron oxide nanoparticles which were coated with dextran at different concentrations. The synthesis was performed by a co-precipitation technique, while the coating of iron oxide nanoparticles was carried out in solution. The obtained nanoparticles were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectrometry, Fourier transform infrared spectroscopy and superconducting quantum interference device magnetometry. The results demonstrated a successful coating of iron oxide nanoparticles with large molar weight dextran, of which agglomeration tendency depended on the amount of dextran in the coating solution. SEM and TEM observations have shown that the iron oxide nanoparticles are of about 7 nm in size.

Rigorous quantitative elemental microanalysis by scanning electron microscopy/energy dispersive x-ray spectrometry (SEM/EDS) with spectrum processing by NIST DTSA-II

NASA Astrophysics Data System (ADS)

Newbury, Dale E.; Ritchie, Nicholas W. M.

2014-09-01

Quantitative electron-excited x-ray microanalysis by scanning electron microscopy/silicon drift detector energy dispersive x-ray spectrometry (SEM/SDD-EDS) is capable of achieving high accuracy and high precision equivalent to that of the high spectral resolution wavelength dispersive x-ray spectrometer even when severe peak interference occurs. The throughput of the SDD-EDS enables high count spectra to be measured that are stable in calibration and resolution (peak shape) across the full deadtime range. With this high spectral stability, multiple linear least squares peak fitting is successful for separating overlapping peaks and spectral background. Careful specimen preparation is necessary to remove topography on unknowns and standards. The standards-based matrix correction procedure embedded in the NIST DTSA-II software engine returns quantitative results supported by a complete error budget, including estimates of the uncertainties from measurement statistics and from the physical basis of the matrix corrections. NIST DTSA-II is available free for Java-platforms at: http://www.cstl.nist.gov/div837/837.02/epq/dtsa2/index.html).

Fabrication and characterization of CNT-based smart tips for synchrotron assisted STM

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

Yan, Hui; Cummings, Marvin; Camino, Fernando

Determination of chemical composition along with imaging at the atomic level provides critical information towards fundamental understanding of the surface of materials and, hence, yields the capability to design new materials by tailoring their ultimate functionalities. Synchrotron X-ray assisted scanning tunneling microscopy (SX-STM) is a promising new technique to achieve real space chemically specific atomic mapping. Chemical sensitivity of SX-STM relies on excitation of core electrons by incident X-rays when their energy is tuned to an absorption edge of a particular element. However, along with core-level electrons, photoelectrons are also excited, which yield additional current and interfere with the tunnelingmore » current. To reduce the background photoelectron current and to improve ultimate resolution of SX-STM, we have developed and fabricated multiwalled carbon nanotubes (MWCNT) based “smart tips” using plasma enhanced chemical vapor deposition and focused ion beam milling. As a result, the newly developed CNT-based smart tips, characterized step by step by scanning electron microscopy (SEM) during the fabrication process, demonstrate good performance and provide opportunity for realizing atomic chemical mapping.« less

Fabrication and characterization of CNT-based smart tips for synchrotron assisted STM

DOE PAGES

Yan, Hui; Cummings, Marvin; Camino, Fernando; ...

2015-08-05

Determination of chemical composition along with imaging at the atomic level provides critical information towards fundamental understanding of the surface of materials and, hence, yields the capability to design new materials by tailoring their ultimate functionalities. Synchrotron X-ray assisted scanning tunneling microscopy (SX-STM) is a promising new technique to achieve real space chemically specific atomic mapping. Chemical sensitivity of SX-STM relies on excitation of core electrons by incident X-rays when their energy is tuned to an absorption edge of a particular element. However, along with core-level electrons, photoelectrons are also excited, which yield additional current and interfere with the tunnelingmore » current. To reduce the background photoelectron current and to improve ultimate resolution of SX-STM, we have developed and fabricated multiwalled carbon nanotubes (MWCNT) based “smart tips” using plasma enhanced chemical vapor deposition and focused ion beam milling. As a result, the newly developed CNT-based smart tips, characterized step by step by scanning electron microscopy (SEM) during the fabrication process, demonstrate good performance and provide opportunity for realizing atomic chemical mapping.« less

Femtosecond laser-induced periodic surface structures on steel and titanium alloy for tribological applications

NASA Astrophysics Data System (ADS)

Bonse, J.; Koter, R.; Hartelt, M.; Spaltmann, D.; Pentzien, S.; Höhm, S.; Rosenfeld, A.; Krüger, J.

2014-10-01

Laser-induced periodic surface structures (LIPSS, ripples) were generated on stainless steel (100Cr6) and titanium alloy (Ti6Al4V) surfaces upon irradiation with multiple femtosecond laser pulses (pulse duration 30 fs, central wavelength 790 nm). The experimental conditions (laser fluence, spatial spot overlap) were optimized in a sample-scanning geometry for the processing of large surface areas (5 × 5 mm2) covered homogeneously by the nanostructures. The irradiated surface regions were subjected to white light interference microscopy and scanning electron microscopy revealing spatial periods around 600 nm. The tribological performance of the nanostructured surface was characterized by reciprocal sliding against a ball of hardened steel in paraffin oil and in commercial engine oil as lubricants, followed by subsequent inspection of the wear tracks. For specific conditions, on the titanium alloy a significant reduction of the friction coefficient by a factor of more than two was observed on the laser-irradiated (LIPSS-covered) surface when compared to the non-irradiated one, indicating the potential benefit of laser surface structuring for tribological applications.

Quasiparticle interference in ZrSiS: Strongly band-selective scattering depending on impurity lattice site

NASA Astrophysics Data System (ADS)

Butler, Christopher J.; Wu, Yu-Mi; Hsing, Cheng-Rong; Tseng, Yi; Sankar, Raman; Wei, Ching-Ming; Chou, Fang-Cheng; Lin, Minn-Tsong

2017-11-01

Scanning tunneling microscopy visualizations of quasiparticle interference (QPI) enable powerful insights into the k -space properties of superconducting, topological, Rashba, and other exotic electronic phases, but their reliance on impurities acting as scattering centers is rarely scrutinized. Here, we investigate QPI at the vacuum-cleaved (001) surface of the Dirac semimetal ZrSiS. We find that interference patterns around impurities located on the Zr and S lattice sites appear very different, and can be ascribed to selective scattering of different subsets of the predominantly Zr 4 d -derived band structure, namely, the m =0 and ±1 components. We show that the selectivity of scattering channels requires an explanation beyond the different bands' orbital characteristics and their respective charge density distributions over Zr and S lattice sites. Importantly, this result shows that the usual assumption of generic scattering centers allowing observations of quasiparticle interference to shed light indiscriminately and isotropically upon the q space of scattering events does not hold, and that the scope and interpretation of QPI observations can therefore be be strongly contingent on the material defect chemistry. This finding promises to spur new investigations into the quasiparticle scattering process itself, to inform future interpretations of quasiparticle interference observations, and ultimately to aid the understanding and engineering of quantum electronic transport properties.

Peculiarities of studying an isolated neuron by the method of laser interference microscopy

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

Yusipovich, Alexander I; Kazakova, Tatiana A; Erokhova, Liudmila A

2006-09-30

Actual aspects of using a new method of laser interference microscopy (LIM) for studying nerve cells are discussed. The peculiarities of the LIM display of neurons are demonstrated by the example of isolated neurons of a pond snail Lymnaea stagnalis. A comparative analysis of the images of the cell and subcellular structures of a neuron obtained by the methods of interference microscopy, optical transmission microscopy, and confocal microscopy is performed. Various aspects of the application of LIM for studying the lateral dimensions and internal structure of the cytoplasm and organelles of a neuron in cytology and cell physiology are discussed.more » (laser biology)« less

Probing Dirac fermion dynamics in topological insulator Bi2Se3 films with a scanning tunneling microscope.

PubMed

Song, Can-Li; Wang, Lili; He, Ke; Ji, Shuai-Hua; Chen, Xi; Ma, Xu-Cun; Xue, Qi-Kun

2015-05-01

Scanning tunneling microscopy and spectroscopy have been used to investigate the femtosecond dynamics of Dirac fermions in the topological insulator Bi2Se3 ultrathin films. At the two-dimensional limit, bulk electrons become quantized and the quantization can be controlled by the film thickness at a single quintuple layer level. By studying the spatial decay of standing waves (quasiparticle interference patterns) off steps, we measure directly the energy and film thickness dependence of the phase relaxation length lϕ and inelastic scattering lifetime τ of topological surface-state electrons. We find that τ exhibits a remarkable (E - EF)(-2) energy dependence and increases with film thickness. We show that the features revealed are typical for electron-electron scattering between surface and bulk states.

Quasiparticle Scattering in Type-II Weyl semimetal MoTe₂.

PubMed

Lin, Chun-Liang; Arafune, Ryuichi; Minamitani, Emi; Kawai, Maki; Takagi, Noriaki

2018-01-30

The electronic structure of type-II Weyl semimetal molybdenum ditelluride (MoTe₂) is studied by using scanning tunneling microscopy and density functional theory calculations. Through measuring energy-dependent quasiparticle interference (QPI) patterns with a cryogenic scanning tunneling microscope, several characteristic features are found in the QPI patterns. Two of them arise from the Weyl semimetal nature; one is the topological Fermi arc surface state and the other can be assigned to be a Weyl point. The remaining structures are derived from the scatterings relevant to the bulk electronic states. The findings lead to thorough understanding of the topological electronic structure of type-II Weyl semimetal MoTe₂. © 2018 IOP Publishing Ltd.

X-ray microscopy of live biological micro-organisms

NASA Astrophysics Data System (ADS)

Raja Al-Ani, Ma'an Nassar

Real-time, compact x-ray microscopy has the potential to benefit many scientific fields, including microbiology, pharmacology, organic chemistry, and physics. Single frame x-ray micro-radiography, produced by a compact, solid-state laser plasma source, allows scientists to use x-ray emission for elemental analysis, and to observe biological specimens in their natural state. In this study, x-ray images of mouse kidney tissue, live bacteria, Pseudomonas aeruginosa and Burkholderia cepacia, and the bacteria's interaction with the antibiotic gentamicin, are examined using x-ray microscopy. For the purposes of comparing between confocal microscopy and x-ray microscopy, we introduced to our work the technique of gold labeling. Indirect immunofluorescence staining and immuno-gold labeling were applied on human lymphocytes and human tumor cells. Differential interference contrast microscopy (DIC) showed the lymphocyte body and nucleus, as did x-ray microscopy. However, the high resolution of x-ray microscopy allows us to differentiate between the gold particles bound to the antibodies and the free gold. A compact, tabletop Nd: glass laser is used in this study to produce x-rays from an Yttrium target. An atomic force microscope is used to scan the x-ray images from the developed photo-resist. The use of compact, tabletop laser plasma sources, in conjunction with x-ray microscopy, is a new technique that has great potential as a flexible, user-friendly scientific research tool.

Electroless silver coating of rod-like glass particles.

PubMed

Moon, Jee Hyun; Kim, Kyung Hwan; Choi, Hyung Wook; Lee, Sang Wha; Park, Sang Joon

2008-09-01

An electroless silver coating of rod-like glass particles was performed and silver glass composite powders were prepared to impart electrical conductivity to these non-conducting glass particles. The low density Ag-coated glass particles may be utilized for manufacturing conducting inorganic materials for electromagnetic interference (EMI) shielding applications and the techniques for controlling the uniform thickness of silver coating can be employed in preparation of biosensor materials. For the surface pretreatment, Sn sensitization was performed and the coating powders were characterized by scanning electron microscopy (SEM), focused ion beam microscopy (FIB), and atomic force microscopy (AFM) along with the surface resistant measurements. In particular, the use of FIB technique for determining directly the Ag-coating thickness was very effective on obtaining the optimum conditions for coating. The surface sensitization and initial silver loading for electroless silver coating could be found and the uniform and smooth silver-coated layer with thickness of 46 nm was prepared at 2 mol/l of Sn and 20% silver loading.

LED-based interference-reflection microscopy combined with optical tweezers for quantitative three-dimensional microtubule imaging.

PubMed

Simmert, Steve; Abdosamadi, Mohammad Kazem; Hermsdorf, Gero; Schäffer, Erik

2018-05-28

Optical tweezers combined with various microscopy techniques are a versatile tool for single-molecule force spectroscopy. However, some combinations may compromise measurements. Here, we combined optical tweezers with total-internal-reflection-fluorescence (TIRF) and interference-reflection microscopy (IRM). Using a light-emitting diode (LED) for IRM illumination, we show that single microtubules can be imaged with high contrast. Furthermore, we converted the IRM interference pattern of an upward bent microtubule to its three-dimensional (3D) profile calibrated against the optical tweezers and evanescent TIRF field. In general, LED-based IRM is a powerful method for high-contrast 3D microscopy.

Laser scatter in clinical applications

NASA Astrophysics Data System (ADS)

Luther, Ed; Geddie, William

2008-02-01

Brightfield Laser Scanning Imaging (BLSI) is available on Laser Scanning Cytometers (LSCs) from CompuCyte Corporation. Briefly, digitation of photodetector outputs is coordinated with the combined motions of a small diameter (typically 2 to 10 microns) laser beam scanning a specimen in the Y direction (directed by a galvanometer-driven scanning mirror) and the microscope stage motion in the X direction. The output measurements are assembled into a two-dimensional array to provide a "non-real" digital image, where each pixel value reports the amount of laser-scattered light that is obtained when the laser beam is centered on that location. Depending on the detector positions, these images are analogous to Differential Interference Contrast or Phase Contrast microscopy. We report the incorporation of the new laser scattering capabilities into the workflow of a high-volume clinical cytology laboratory at University Health Network, Toronto, Canada. The laboratory has been employing LSC technology since 2003 for immunophenotypic fluorescence analysis of approximately 1200 cytological specimens per year, using the Clatch methodology. The new BLSI component allows visualization of cellular morphology at higher resolution levels than is possible with standard brightfield microscopic evaluation of unstained cells. BLSI is incorporated into the triage phase, where evaluation of unstained samples is combined with fluorescence evaluation to obtain specimen background levels. Technical details of the imaging methodology will be presented, as well as illustrative examples from current studies and comparisons to detailed, but obscure, historical studies of cytology specimens based on phase contrast microscopy.

Single-crystalline FeCo nanoparticle-filled carbon nanotubes: synthesis, structural characterization and magnetic properties.

PubMed

Ghunaim, Rasha; Scholz, Maik; Damm, Christine; Rellinghaus, Bernd; Klingeler, Rüdiger; Büchner, Bernd; Mertig, Michael; Hampel, Silke

2018-01-01

In the present work, we demonstrate different synthesis procedures for filling carbon nanotubes (CNTs) with equimolar binary nanoparticles of the type Fe-Co. The CNTs act as templates for the encapsulation of magnetic nanoparticles and provide a protective shield against oxidation as well as prevent nanoparticle agglomeration. By variation of the reaction parameters, we were able to tailor the sample purity, degree of filling, the composition and size of the filling particles, and therefore, the magnetic properties. The samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), superconducting quantum interference device (SQUID) and thermogravimetric analysis (TGA). The Fe-Co-filled CNTs show significant enhancement in the coercive field as compared to the corresponding bulk material, which make them excellent candidates for several applications such as magnetic storage devices.

Highly sensitive and selective electrochemical dopamine sensing properties of multilayer graphene nanobelts

NASA Astrophysics Data System (ADS)

Karthick Kannan, Padmanathan; Moshkalev, Stanislav A.; Sekhar Rout, Chandra

2016-02-01

In the present study, we report the electrochemical sensing property of multi-layer graphene nanobelts (GNBs) towards dopamine (DA). GNBs are synthesized from natural graphite and characterized by using techniques like field-emission scanning electron microscopy, atomic force microscopy and Raman spectroscopy. An electrochemical sensor based on GNBs is developed for the detection of DA. From the cyclic voltammetry and amperometry studies, it is found that GNBs possess excellent electrocatalytic activity towards DA molecules. The developed DA sensor showed a sensitivity value of 0.95 μA μM-1 cm-2 with a linear range of 2 μM to 0.2 mM. The interference data exhibited that GNB is highly selective to DA even in the presence of common interfering species like ascorbic acid, uric acid, glucose and lactic acid.

Highly sensitive and selective electrochemical dopamine sensing properties of multilayer graphene nanobelts.

PubMed

Kannan, Padmanathan Karthick; Moshkalev, Stanislav A; Rout, Chandra Sekhar

2016-02-19

In the present study, we report the electrochemical sensing property of multi-layer graphene nanobelts (GNBs) towards dopamine (DA). GNBs are synthesized from natural graphite and characterized by using techniques like field-emission scanning electron microscopy, atomic force microscopy and Raman spectroscopy. An electrochemical sensor based on GNBs is developed for the detection of DA. From the cyclic voltammetry and amperometry studies, it is found that GNBs possess excellent electrocatalytic activity towards DA molecules. The developed DA sensor showed a sensitivity value of 0.95 μA μM(-1) cm(-2) with a linear range of 2 μM to 0.2 mM. The interference data exhibited that GNB is highly selective to DA even in the presence of common interfering species like ascorbic acid, uric acid, glucose and lactic acid.

Novel methods for matter interferometry with nanosized objects

NASA Astrophysics Data System (ADS)

Arndt, Markus

2005-05-01

We discuss the current status and prospects for novel experimental methods for coherence^1,2 and decoherence^3 experiments with large molecules. Quantum interferometry with nanosized objects is interesting for the exploration of the quantum-classical transition. The same experimental setup is also promising for metrology applications and molecular nanolithography. Our coherence experiments with macromolecules employ a Talbot-Lau interferometer. We discuss some modifications to this scheme, which are required to extend it to particles with masses in excess of several thousand mass units. In particular, the detection in all previous interference experiments with large clusters and molecules, was based on either laser ionization^1 (e.g. Fullerenes) or electron impact ionization^2 (e.g. Porphyrins etc.). However, most ionization schemes run into efficiency limits when the mass and complexity of the target particle increases. Here we present experimental results for an interference detector which is truly scalable, i.e. one which will even improve with increasing particle size and complexity. ``Mechanically magnified fluorescence imaging'' (MMFI), combines the high spatial resolution, which is intrinsic to Talbot Lau interferometry with the high detection efficiency of fluorophores adsorbed onto a substrate. In the Talbot Lau setup a molecular interference pattern is revealed by scanning the 3^rd grating across the molecular beam^1. The number of transmitted molecules is a function of the relative position between the mask and the molecular density pattern. Both the particle interference pattern and the mechanical mask structure may be far smaller than any optical resolution limit. After mechanical magnification by an arbitrary factor, in our case a factor 5000, the interference pattern can still be inspected in fluorescence microscopy. The fluorescent molecules are collected on a surface which is scanned collinearly and synchronously behind the 3rd grating. The resulting image of the interference pattern is by far large enough to be easily seen by the unaided eye. High contrast interference fringes could be recorded with dyes molecules. ^1B. Brezger et al. , Phys. Rev. Lett. 88, 100404 (2002). ^2L. Hackermüller et al. Phys. Rev. Lett 91, 90408 (2003). ^3L. Hackermüller et al. Nature 427, 711 (2004).

Disruption of lipid rafts interferes with the interaction of Toxoplasma gondii with macrophages and epithelial cells.

PubMed

Cruz, Karla Dias; Cruz, Thayana Araújo; Veras de Moraes, Gabriela; Paredes-Santos, Tatiana Christina; Attias, Marcia; de Souza, Wanderley

2014-01-01

The intracellular parasite Toxoplasma gondii can penetrate any warm-blooded animal cell. Conserved molecular assemblies of host cell plasma membranes should be involved in the parasite-host cell recognition. Lipid rafts are well-conserved membrane microdomains that contain high concentrations of cholesterol, sphingolipids, glycosylphosphatidylinositol, GPI-anchored proteins, and dually acylated proteins such as members of the Src family of tyrosine kinases. Disturbing lipid rafts of mouse peritoneal macrophages and epithelial cells of the lineage LLC-MK2 with methyl-beta cyclodextrin (M β CD) and filipin, which interfere with cholesterol or lidocaine, significantly inhibited internalization of T. gondii in both cell types, although adhesion remained unaffected in macrophages and decreased only in LLC-MK2 cells. Scanning and transmission electron microscopy confirmed these observations. Results are discussed in terms of the original role of macrophages as professional phagocytes versus the LLC-MK2 cell lineage originated from kidney epithelial cells.

Electronic properties of two inequivalent surfaces in MoTe2 studied by quasi-particle interference

NASA Astrophysics Data System (ADS)

Iaia, Davide; Shichao, Yan; Madhavan, Vidya

MoTe2 has received renewed interest due to its topological properties. At a temperature below 250 K, MoTe2 is a type II Weyl semimetal hosting three-dimensional (3D) linearly dispersing states with well defined chirality. Nodes in this 3D dispersion are called Weyl points. Weyl points of opposite chirality are expected to be connected by topologically protected Fermi arcs. In this talk we discuss low temperature scanning tunneling microscopy studies of the electronic structure of MoTe2. The electronic properties are studied using quasi-particle interference technique which allows us to resolve Fermi arcs features and to clearly distinguish between two inequivalent MoTe2 surfaces. Our results provide important contributions to further our understanding of the electronic properties of this new and exotic class of materials. National Science Foundation (NSF).

Shearing interference microscope for step-height measurements.

PubMed

Trịnh, Hưng-Xuân; Lin, Shyh-Tsong; Chen, Liang-Chia; Yeh, Sheng-Lih; Chen, Chin-Sheng; Hoang, Hong-Hai

2017-05-01

A shearing interference microscope using a Savart prism as the shear plate is proposed for inspecting step-heights. Where the light beam propagates through the Savart prism and microscopic system to illuminate the sample, it then turns back to re-pass through the Savart prism and microscopic system to generate a shearing interference pattern on the camera. Two measurement modes, phase-shifting and phase-scanning, can be utilized to determine the depths of the step-heights on the sample. The first mode, which employs a narrowband source, is based on the five-step phase-shifting algorithm and has a measurement range of a quarter-wavelength. The second mode, which adopts a broadband source, is based on peak-intensity identification technology and has a measurement range up to a few micrometres. This paper is to introduce the configuration and measurement theory of this microscope, perform a setup used to implement it, and present the experimental results from the uses of the setup. The results not only verify the validity but also confirm the high measurement repeatability of the proposed microscope. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Scanning probe recognition microscopy investigation of tissue scaffold properties

PubMed Central

Fan, Yuan; Chen, Qian; Ayres, Virginia M; Baczewski, Andrew D; Udpa, Lalita; Kumar, Shiva

2007-01-01

Scanning probe recognition microscopy is a new scanning probe microscopy technique which enables selective scanning along individual nanofibers within a tissue scaffold. Statistically significant data for multiple properties can be collected by repetitively fine-scanning an identical region of interest. The results of a scanning probe recognition microscopy investigation of the surface roughness and elasticity of a series of tissue scaffolds are presented. Deconvolution and statistical methods were developed and used for data accuracy along curved nanofiber surfaces. Nanofiber features were also independently analyzed using transmission electron microscopy, with results that supported the scanning probe recognition microscopy-based analysis. PMID:18203431

Scanning probe recognition microscopy investigation of tissue scaffold properties.

PubMed

Fan, Yuan; Chen, Qian; Ayres, Virginia M; Baczewski, Andrew D; Udpa, Lalita; Kumar, Shiva

2007-01-01

Scanning probe recognition microscopy is a new scanning probe microscopy technique which enables selective scanning along individual nanofibers within a tissue scaffold. Statistically significant data for multiple properties can be collected by repetitively fine-scanning an identical region of interest. The results of a scanning probe recognition microscopy investigation of the surface roughness and elasticity of a series of tissue scaffolds are presented. Deconvolution and statistical methods were developed and used for data accuracy along curved nanofiber surfaces. Nanofiber features were also independently analyzed using transmission electron microscopy, with results that supported the scanning probe recognition microscopy-based analysis.

Imaging of endodontic biofilms by combined microscopy (FISH/cLSM - SEM).

PubMed

Schaudinn, C; Carr, G; Gorur, A; Jaramillo, D; Costerton, J W; Webster, P

2009-08-01

Scanning electron microscopy is a useful imaging approach for the visualization of bacterial biofilms in their natural environments including their medical and dental habitats, because it allows for the exploration of large surfaces with excellent resolution of topographic features. Most biofilms in nature, however, are embedded in a thick layer of extracellular matrix that prevents a clear identification of individual bacteria by scanning electron microscopy. The use of confocal laser scanning microscopy on the other hand in combination with fluorescence in situ hybridization enables the visualization of matrix embedded bacteria in multi-layered biofilms. In our study, fluorescence in situ hybridization/confocal laser scanning microscopy and scanning electron microscopy were applied to visualize bacterial biofilm in endodontic root canals. The resulting fluorescence in situ hybridization /confocal laser scanning microscopy and scanning electron microscopy and pictures were subsequently combined into one single image to provide high-resolution information on the location of hidden bacteria. The combined use of scanning electron microscopy and fluorescence in situ hybridization / confocal laser scanning microscopy has the potential to overcome the limits of each single technique.

Scanning SQUID sampler with 40-ps time resolution

NASA Astrophysics Data System (ADS)

Cui, Zheng; Kirtley, John R.; Wang, Yihua; Kratz, Philip A.; Rosenberg, Aaron J.; Watson, Christopher A.; Gibson, Gerald W.; Ketchen, Mark B.; Moler, Kathryn. A.

2017-08-01

Scanning Superconducting QUantum Interference Device (SQUID) microscopy provides valuable information about magnetic properties of materials and devices. The magnetic flux response of the SQUID is often linearized with a flux-locked feedback loop, which limits the response time to microseconds or longer. In this work, we present the design, fabrication, and characterization of a novel scanning SQUID sampler with a 40-ps time resolution and linearized response to periodically triggered signals. Other design features include a micron-scale pickup loop for the detection of local magnetic flux, a field coil to apply a local magnetic field to the sample, and a modulation coil to operate the SQUID sampler in a flux-locked loop to linearize the flux response. The entire sampler device is fabricated on a 2 mm × 2 mm chip and can be scanned over macroscopic planar samples. The flux noise at 4.2 K with 100 kHz repetition rate and 1 s of averaging is of order 1 mΦ0. This SQUID sampler will be useful for imaging dynamics in magnetic and superconducting materials and devices.

Scanning SQUID sampler with 40-ps time resolution.

PubMed

Cui, Zheng; Kirtley, John R; Wang, Yihua; Kratz, Philip A; Rosenberg, Aaron J; Watson, Christopher A; Gibson, Gerald W; Ketchen, Mark B; Moler, Kathryn A

2017-08-01

Scanning Superconducting QUantum Interference Device (SQUID) microscopy provides valuable information about magnetic properties of materials and devices. The magnetic flux response of the SQUID is often linearized with a flux-locked feedback loop, which limits the response time to microseconds or longer. In this work, we present the design, fabrication, and characterization of a novel scanning SQUID sampler with a 40-ps time resolution and linearized response to periodically triggered signals. Other design features include a micron-scale pickup loop for the detection of local magnetic flux, a field coil to apply a local magnetic field to the sample, and a modulation coil to operate the SQUID sampler in a flux-locked loop to linearize the flux response. The entire sampler device is fabricated on a 2 mm × 2 mm chip and can be scanned over macroscopic planar samples. The flux noise at 4.2 K with 100 kHz repetition rate and 1 s of averaging is of order 1 mΦ 0 . This SQUID sampler will be useful for imaging dynamics in magnetic and superconducting materials and devices.

Ultrafast laser-induced reproducible nano-gratings on a molybdenum surface

NASA Astrophysics Data System (ADS)

Dar, Mudasir H.; Saad, Nabil A.; Sahoo, Chakradhar; Naraharisetty, Sri Ram G.; Rao Desai, Narayana

2017-02-01

Wavelength-dependent reproducible nano-gratings were produced on a bulk molybdenum surface upon irradiation with femtosecond laser pulses at near normal incidence in ambient air and water environments. The surface morphology of the irradiated surfaces was characterized by field emission scanning electron microscopy. The ripple spacing was observed to decrease by half when the surface was irradiated with the second harmonic of the fundamental 800 nm radiation. Careful choice of the laser parameters such as fluence, scanning speed, polarization and wavelength were observed to be important for the formation of smooth periodic ripples. The mechanism of formation of polarization-dependent periodic ripples is explained based on the interference model. We also demonstrated the use of a laser direct writing technique for the fabrication of periodic subwavelength structures that have potential applications in photonic devices.

Synergistic effect of polyaniline coverage and surface microstructure on the inhibition of Pseudomonas aeruginosa biofilm formation.

PubMed

Gallarato, L A; Mulko, L E; Dardanelli, M S; Barbero, C A; Acevedo, D F; Yslas, E I

2017-02-01

Biofilm Formation is a survival strategy for microorganisms to adapt to their environment. Microbial cells in biofilm become tolerant and resistant to antibiotics and immune responses, increasing the difficulties for the clinical treatment of microbial infections. The surface chemistry and the micro/nano-topography of solid interfaces play a major role in mediating microorganism activity and adhesion. The effect of the surface chemical composition and topography on the adhesion and viability of Pseudomonas aeruginosa was studied. Polymeric (polyethylene terephthalate) surfaces were covered with a conducting polymer (polyaniline, PANI) film by in-situ polymerization and microstructured by Direct Laser Interference Patterning (DLIP). The viability of Pseudomonas aeruginosa on the different surfaces was investigated. The physicochemical properties of the surfaces were characterized by water contact angle measurements, scanning electron microscopy and atomic force microscopy. Bacterial biofilms were imaged by atomic force and scanning electron microscopies. The bacterial viability decreased on PANI compared with the substrate (polyethylene terephthalate) and it decreased even more upon micro-structuring the PANI films. In addition, the biofilm reduction could be improved using polymers with different chemical composition and/or the same polymer with different topographies. Both methods presented diminish the bacterial attachment and biofilm formation. These findings present a high impact related to materials for biomedical engineer applications regarding medical devices, as prostheses or catheters. Copyright © 2016 Elsevier B.V. All rights reserved.

Super-resolution differential interference contrast microscopy by structured illumination.

PubMed

Chen, Jianling; Xu, Yan; Lv, Xiaohua; Lai, Xiaomin; Zeng, Shaoqun

2013-01-14

We propose a structured illumination differential interference contrast (SI-DIC) microscopy, breaking the diffraction resolution limit of differential interference contrast (DIC) microscopy. SI-DIC extends the bandwidth of coherent transfer function of the DIC imaging system, thus the resolution is improved. With 0.8 numerical aperture condenser and objective, the reconstructed SI-DIC image of 53 nm polystyrene beads reveals lateral resolution of approximately 190 nm, doubling that of the conventional DIC image. We also demonstrate biological observations of label-free cells with improved spatial resolution. The SI-DIC microscopy can provide sub-diffraction resolution and high contrast images with marker-free specimens, and has the potential for achieving sub-diffraction resolution quantitative phase imaging.

Diffracting aperture based differential phase contrast for scanning X-ray microscopy.

PubMed

Kaulich, Burkhard; Polack, Francois; Neuhaeusler, Ulrich; Susini, Jean; di Fabrizio, Enzo; Wilhein, Thomas

2002-10-07

It is demonstrated that in a zone plate based scanning X-ray microscope, used to image low absorbing, heterogeneous matter at a mesoscopic scale, differential phase contrast (DPC) can be implemented without adding any additional optical component to the normal scheme of the microscope. The DPC mode is simply generated by an appropriate positioning and alignment of microscope apertures. Diffraction from the apertures produces a wave front with a non-uniform intensity. The signal recorded by a pinhole photo diode located in the intensity gradient is highly sensitive to phase changes introduced by the specimen to be recorded. The feasibility of this novel DPC technique was proven with the scanning X-ray microscope at the ID21 beamline of the European Synchrotron Radiation facility (ESRF) operated at 6 keV photon energy. We observe a differential phase contrast, similar to Nomarski's differential interference contrast for the light microscope, which results in a tremendous increase in image contrast of up to 20 % when imaging low absorbing specimen.

Spectroscopic scanning tunneling microscopy insights into Fe-based superconductors

NASA Astrophysics Data System (ADS)

Hoffman, Jennifer E.

2011-12-01

In the first three years since the discovery of Fe-based high Tc superconductors, scanning tunneling microscopy (STM) and spectroscopy have shed light on three important questions. First, STM has demonstrated the complexity of the pairing symmetry in Fe-based materials. Phase-sensitive quasiparticle interference (QPI) imaging and low temperature spectroscopy have shown that the pairing order parameter varies from nodal to nodeless s± within a single family, FeTe1-xSex. Second, STM has imaged C4 → C2 symmetry breaking in the electronic states of both parent and superconducting materials. As a local probe, STM is in a strong position to understand the interactions between these broken symmetry states and superconductivity. Finally, STM has been used to image the vortex state, giving insights into the technical problem of vortex pinning, and the fundamental problem of the competing states introduced when superconductivity is locally quenched by a magnetic field. Here we give a pedagogical introduction to STM and QPI imaging, discuss the specific challenges associated with extracting bulk properties from the study of surfaces, and report on progress made in understanding Fe-based superconductors using STM techniques.

Abundant Type III Lipid Transfer Proteins in Arabidopsis Tapetum Are Secreted to the Locule and Become a Constituent of the Pollen Exine1[W][OPEN

PubMed Central

Huang, Ming-Der; Chen, Tung-Ling L.; Huang, Anthony H.C.

2013-01-01

Lipid transfer proteins (LTPs) are small secretory proteins in plants with defined lipid-binding structures for possible lipid exocytosis. Special groups of LTPs unique to the anther tapetum are abundant, but their functions are unclear. We studied a special group of LTPs, type III LTPs, in Arabidopsis (Arabidopsis thaliana). Their transcripts were restricted to the anther tapetum, with levels peaking at the developmental stage of maximal pollen-wall exine synthesis. We constructed an LTP-Green Fluorescent Protein (LTP-GFP) plasmid, transformed it into wild-type plants, and monitored LTP-GFP in developing anthers with confocal laser scanning microscopy. LTP-GFP appeared in the tapetum and was secreted via the endoplasmic reticulum-trans-Golgi network machinery into the locule. It then moved to the microspore surface and remained as a component of exine. Immuno-transmission electron microscopy of native LTP in anthers confirmed the LTP-GFP observations. The in vivo association of LTP-GFP and exine in anthers was not observed with non-type III or structurally modified type III LTPs or in transformed exine-defective mutant plants. RNA interference knockdown of individual type III LTPs produced no observable mutant phenotypes. RNA interference knockdown of two type III LTPs produced microscopy-observable morphologic changes in the intine underneath the exine (presumably as a consequence of changes in the exine not observed by transmission electron microscopy) and pollen susceptible to dehydration damage. Overall, we reveal a novel transfer pathway of LTPs in which LTPs bound or nonbound to exine precursors are secreted from the tapetum to become microspore exine constituents; this pathway explains the need for plentiful LTPs to incorporate into the abundant exine. PMID:24096413

Spatial interferences in the electron transport of heavy-fermion materials

NASA Astrophysics Data System (ADS)

Zhang, Shu-feng; Liu, Yu; Song, Hai-Feng; Yang, Yi-feng

2016-08-01

The scanning tunneling microscopy/spectroscopy and the point contact spectroscopy represent major progress in recent heavy-fermion research. Both have revealed important information on the composite nature of the emergent heavy-electron quasiparticles. However, a detailed and thorough microscopic understanding of the similarities and differences in the underlying physical processes of these techniques is still lacking. Here we study the electron transport in the normal state of the periodic Anderson lattice by using the Keldysh nonequilibrium Green's function technique. In addition to the well-known Fano interference between the conduction and f -electron channels, our results further reveal the effect of spatial interference between different spatial paths at the interface on the differential conductance and their interesting interplay with the band features such as the hybridization gap and the Van Hove singularity. We find that the spatial interference leads to a weighted average in the momentum space for the electron transport and could cause suppression of the electronic band features under certain circumstances. In particular, it reduces the capability of probing the f -electron spectral weight near the edges of the hybridization gap for large interface depending on the Fermi surface of the lead. Our results indicate an intrinsic inefficiency of the point contact spectroscopy in probing the f electrons.

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

NASA Astrophysics Data System (ADS)

Wang, Dehua

2014-09-01

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

Coherent scatter-controlled phase-change grating structures in silicon using femtosecond laser pulses.

PubMed

Fuentes-Edfuf, Yasser; Garcia-Lechuga, Mario; Puerto, Daniel; Florian, Camilo; Garcia-Leis, Adianez; Sanchez-Cortes, Santiago; Solis, Javier; Siegel, Jan

2017-07-04

Periodic structures of alternating amorphous-crystalline fringes have been fabricated in silicon using repetitive femtosecond laser exposure (800 nm wavelength and 120 fs duration). The method is based on the interference of the incident laser light with far- and near-field scattered light, leading to local melting at the interference maxima, as demonstrated by femtosecond microscopy. Exploiting this strategy, lines of highly regular amorphous fringes can be written. The fringes have been characterized in detail using optical microscopy combined modelling, which enables a determination of the three-dimensional shape of individual fringes. 2D micro-Raman spectroscopy reveals that the space between amorphous fringes remains crystalline. We demonstrate that the fringe period can be tuned over a range of 410 nm - 13 µm by changing the angle of incidence and inverting the beam scan direction. Fine control over the lateral dimensions, thickness, surface depression and optical contrast of the fringes is obtained via adjustment of pulse number, fluence and spot size. Large-area, highly homogeneous gratings composed of amorphous fringes with micrometer width and millimeter length can readily be fabricated. The here presented fabrication technique is expected to have applications in the fields of optics, nanoelectronics, and mechatronics and should be applicable to other materials.

Evidence against a charge density wave on Bi(111)

DOE PAGES

Kim, T. K.; Wells, J.; Kirkegaard, C.; ...

2005-08-18

The Bi(111) surface was studied by scanning tunneling microscopy (STM), transmission electron microscopy (TEM) and angle-resolved photoemission (ARPES) in order to verify the existence of a recently proposed surface charge density wave (CDW). The STM and TEM results to not support a CDW scenario at low temperatures. Thus the quasiparticle interference pattern observed in STM confirms the spin-orbit split character of the surface states which prevents the formation of a CDW, even in the case of good nesting. The dispersion of the electronic states observed with ARPES agrees well with earlier findings. In particular, the Fermi contour of the electronmore » pocket at the centre of the surface Brillouin zone is found to have a hexagonal shape. However, no gap opening or other signatures of a CDW phase transition can be found in the temperature-dependent data.« less

A One-Step, Solvothermal Reduction Method for Producing Reduced Graphene Oxide Dispersions in Organic Solvents

PubMed Central

Dubin, Sergey; Gilje, Scott; Wang, Kan; Tung, Vincent C.; Cha, Kitty; Hall, Anthony S.; Farrar, Jabari; Varshneya, Rupal; Yang, Yang; Kaner, Richard B.

2014-01-01

Refluxing graphene oxide (GO) in N-methyl-2-pyrrolidinone (NMP) results in deoxygenation and reduction to yield a stable colloidal dispersion. The solvothermal reduction is accompanied by a color change from light brown to black. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) images of the product confirm the presence of single sheets of the solvothermally reduced graphene oxide (SRGO). X-ray photoelectron spectroscopy (XPS) of SRGO indicates a significant increase in intensity of the C=C bond character, while the oxygen content decreases markedly after the reduction is complete. X-ray diffraction analysis of SRGO shows a single broad peak at 26.24° 2θ (3.4 Å), confirming the presence of graphitic stacking of reduced sheets. SRGO sheets are redispersible in a variety of organic solvents, which may hold promise as an acceptor material for bulk heterojunction photovoltaic cells, or electromagnetic interference shielding applications. PMID:20586422

Use of Computer-Generated Holograms in Security Hologram Applications

NASA Astrophysics Data System (ADS)

Bulanovs, A.; Bakanas, R.

2016-10-01

The article discusses the use of computer-generated holograms (CGHs) for the application as one of the security features in the relief-phase protective holograms. An improved method of calculating CGHs is presented, based on ray-tracing approach in the case of interference of parallel rays. Software is developed for the calculation of multilevel phase CGHs and their integration in the application of security holograms. Topology of calculated computer-generated phase holograms was recorded on the photoresist by the optical greyscale lithography. Parameters of the recorded microstructures were investigated with the help of the atomic-force microscopy (AFM) and scanning electron microscopy (SEM) methods. The results of the research have shown highly protective properties of the security elements based on CGH microstructures. In our opinion, a wide use of CGHs is very promising in the structure of complex security holograms for increasing the level of protection against counterfeit.

Hydrothermal epitaxy and resultant properties of EuTiO3 films on SrTiO3(001) substrate

PubMed Central

2014-01-01

We report a novel epitaxial growth of EuTiO3 films on SrTiO3(001) substrate by hydrothermal method. The morphological, structural, chemical, and magnetic properties of these epitaxial EuTiO3 films were examined by scanning electron microscopy, transmission electron microscopy, high-resolution X-ray diffractometry, X-ray photoelectron spectroscopy, and superconducting quantum interference device magnetometry, respectively. As-grown EuTiO3 films with a perovskite structure were found to show an out-of-plane lattice shrinkage and room-temperature ferromagnetism, possibly resulting from an existence of Eu3+. Postannealing at 1,000°C could reduce the amount of Eu3+, relax the out-of-plane lattice shrinkage, and impact the magnetic properties of the films. PACS 81.10.Aj; 81.15.-z; 61.05.-a PMID:24948889

A masked least-squares smoothing procedure for artifact reduction in scanning-EMG recordings.

PubMed

Corera, Íñigo; Eciolaza, Adrián; Rubio, Oliver; Malanda, Armando; Rodríguez-Falces, Javier; Navallas, Javier

2018-01-11

Scanning-EMG is an electrophysiological technique in which the electrical activity of the motor unit is recorded at multiple points along a corridor crossing the motor unit territory. Correct analysis of the scanning-EMG signal requires prior elimination of interference from nearby motor units. Although the traditional processing based on the median filtering is effective in removing such interference, it distorts the physiological waveform of the scanning-EMG signal. In this study, we describe a new scanning-EMG signal processing algorithm that preserves the physiological signal waveform while effectively removing interference from other motor units. To obtain a cleaned-up version of the scanning signal, the masked least-squares smoothing (MLSS) algorithm recalculates and replaces each sample value of the signal using a least-squares smoothing in the spatial dimension, taking into account the information of only those samples that are not contaminated with activity of other motor units. The performance of the new algorithm with simulated scanning-EMG signals is studied and compared with the performance of the median algorithm and tested with real scanning signals. Results show that the MLSS algorithm distorts the waveform of the scanning-EMG signal much less than the median algorithm (approximately 3.5 dB gain), being at the same time very effective at removing interference components. Graphical Abstract The raw scanning-EMG signal (left figure) is processed by the MLSS algorithm in order to remove the artifact interference. Firstly, artifacts are detected from the raw signal, obtaining a validity mask (central figure) that determines the samples that have been contaminated by artifacts. Secondly, a least-squares smoothing procedure in the spatial dimension is applied to the raw signal using the not contaminated samples according to the validity mask. The resulting MLSS-processed scanning-EMG signal (right figure) is clean of artifact interference.

Planar Diffractive Lenses: Fundamentals, Functionalities, and Applications.

PubMed

Huang, Kun; Qin, Fei; Liu, Hong; Ye, Huapeng; Qiu, Cheng-Wei; Hong, Minghui; Luk'yanchuk, Boris; Teng, Jinghua

2018-06-01

Traditional objective lenses in modern microscopy, based on the refraction of light, are restricted by the Rayleigh diffraction limit. The existing methods to overcome this limit can be categorized into near-field (e.g., scanning near-field optical microscopy, superlens, microsphere lens) and far-field (e.g., stimulated emission depletion microscopy, photoactivated localization microscopy, stochastic optical reconstruction microscopy) approaches. However, they either operate in the challenging near-field mode or there is the need to label samples in biology. Recently, through manipulation of the diffraction of light with binary masks or gradient metasurfaces, some miniaturized and planar lenses have been reported with intriguing functionalities such as ultrahigh numerical aperture, large depth of focus, and subdiffraction-limit focusing in far-field, which provides a viable solution for the label-free superresolution imaging. Here, the recent advances in planar diffractive lenses (PDLs) are reviewed from a united theoretical account on diffraction-based focusing optics, and the underlying physics of nanofocusing via constructive or destructive interference is revealed. Various approaches of realizing PDLs are introduced in terms of their unique performances and interpreted by using optical aberration theory. Furthermore, a detailed tutorial about applying these planar lenses in nanoimaging is provided, followed by an outlook regarding future development toward practical applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Temporal overlap estimation based on interference spectrum in CARS microscopy

NASA Astrophysics Data System (ADS)

Zhang, Yongning; Jiang, Junfeng; Liu, Kun; Huang, Can; Wang, Shuang; Zhang, Xuezhi; Liu, Tiegen

2018-01-01

Coherent Anti-Stokes Raman Scattering (CARS) microscopy has attracted lots of attention because of the advantages, such as noninvasive, label-free, chemical specificity, intrinsic three-dimension spatial resolution and so on. However, the temporal overlap of pump and Stokes has not been solved owing to the ultrafast optical pulse used in CARS microscopy. We combine interference spectrum of residual pump in Stokes path and nonlinear Schrodinger equation (NLSE) to realize the temporal overlap of pump pulse and Stokes pulse. At first, based on the interference spectrum of pump pulse and residual pump in Stokes path, the optical delay is defined when optical path difference between pump path and Stokes path is zero. Then the relative optical delay between Stokes pulse and residual pump in PCF can be calculated by NLSE. According to the spectrum interference and NLSE, temporal overlap of pump pulse and Stokes pulse will be realized easily and the imaging speed will be improved in CARS microscopy.

Carbide-derived carbon (CDC) linear actuator properties in combination with conducting polymers

NASA Astrophysics Data System (ADS)

Kiefer, Rudolf; Aydemir, Nihan; Torop, Janno; Kilmartin, Paul A.; Tamm, Tarmo; Kaasik, Friedrich; Kesküla, Arko; Travas-Sejdic, Jadranka; Aabloo, Alvo

2014-03-01

Carbide-derived Carbon (CDC) material is applied for super capacitors due to their nanoporous structure and their high charging/discharging capability. In this work we report for the first time CDC linear actuators and CDC combined with polypyrrole (CDC-PPy) in ECMD (Electrochemomechanical deformation) under isotonic (constant force) and isometric (constant length) measurements in aqueous electrolyte. CDC-PPy actuators showing nearly double strain under cyclic voltammetric and square wave potential measurements in comparison to CDC linear actuators. The new material is investigated by SEM (scanning electron microscopy) and EDX (energy dispersive X-ray analysis) to reveal how the conducting polymer layer and the CDC layer interfere together.

Demodulation signal processing in multiphoton imaging

NASA Astrophysics Data System (ADS)

Fisher, Walter G.; Wachter, Eric A.; Piston, David W.

2002-06-01

Multiphoton laser scanning microscopy offers numerous advantages, but sensitivity can be seriously affected by contamination from ambient room light. Typically, this forces experiments to be performed in an absolutely dark room. Since mode-locked lasers are used to generate detectable signals, signal-processing can be used to avoid such problems by taking advantage of the pulsed characteristics of such lasers. Demodulation of the fluorescence signal generated at the mode-locked frequency can result in significant reduction of interference from ambient noise sources. Such demodulation can be readily adapted to existing microscopes by inserting appropriate processor circuitry between the detector and data collection system, yielding a more robust microscope.

Near-field optical technique applied for investigation of the characteristics of polymer fiber and waveguide structures.

PubMed

Ming, Hai; Tang, Lin; Sun, Xiaohong; Zhang, Jiangying; Wang, Pei; Lu, Yonghua; Bai, Ming; Guo, Yang; Xie, Aifang; Zhang, Zebo

2004-01-01

This article summarizes the near-field optical technique applied for investigating the characteristics of polymer fiber and waveguide structures. The near-field optical technique is used to analyze multimode interference structures of fiber. The localized fluctuation of the transmission caused by fractal cluster is carried out in Nd3+- and Eu3+-doped polymer fiber and film by means of a scanning near-field optical microscopy. The near-field optical spectrum of Nd3+-doped polymer fiber is investigated. The topography and near-field intensity images of Azo-polymer liquid crystal film for waveguide are obtained simultaneously.

Scanning Tunneling Microscopy Study on Dirac Nodal-line Semimetal ZrSiS

NASA Astrophysics Data System (ADS)

Su, Chih-Chuan; Guan, Syu-You; Wang, Tzu-Cheng; Sankar, Raman; Guo, Guang-Yu; Chou, Fangcheng; Chang, Chia-Seng; Chuang, Tien-Ming

The discovery of 3D Dirac nodal-line protected by non-symmophic symmetry in ZrSiS family has been reported by angle resolved photoemission spectroscopy (ARPES) and quantum oscillation measurements. ZrSiS also exhibits a butterfly shaped titanic angular magnetoresistance and strong Zeeman splitting in quantum oscillation. These observations with its layered crystal structure make the ZrSiS family an interesting candidate to understand the novel properties of the nodal-line semimetals. Here, we study the electronic structures of the single crystal ZrSiS by using spectroscopic-imaging scanning tunneling microscope at T= 4.2K. Our quasiparticle scattering interference imaging reveals the characteristic wave vectors with linear dispersion from Dirac line nodes in the bulk and its surface states. Our results are in excellent agreement with the first principle calculation, and also in consistent with ARPES and quantum oscillation measurements.

Investigations of Topological Surface States in Sb (111) Ultrathin Films by STM/STS Experiments and DFT Calculations

NASA Astrophysics Data System (ADS)

Luo, Ziyu; Yao, Guanggeng; Xu, Wentao; Feng, Yuanping; Wang, Xue-Sen

2014-03-01

Bulk Sb was regarded as a semimetal with a nontrivial topological order. It is worth exploring whether the Sb ultrathin film has the potential to be an elementary topological insulator. In the presence of quantum confinement effect, we investigated the evolution of topological surface states in Sb (111) ultrathin films with different thickness by the scanning tunneling microscopy/ spectroscopy (STM/STS) experiments and density functional theory (DFT) calculations. By comparing the quasiparticle interference (QPI) patterns obtained from Fourier-transform scanning tunneling spectroscopy (FT-STS) and from DFT calculations, we successfully derive the spin properties of topological surface states on Sb (111) ultrathin films. In addition, based on the DFT calculations, the 8BL Sb (111) ultrathin film was proved to possess up to 30% spinseparated topological surface states within the bandgap. Therefore, the highquality 8BL Sb (111) ultrathin film could be regarded as an elementary topological insulator.

Quantitative DIC microscopy using an off-axis self-interference approach.

PubMed

Fu, Dan; Oh, Seungeun; Choi, Wonshik; Yamauchi, Toyohiko; Dorn, August; Yaqoob, Zahid; Dasari, Ramachandra R; Feld, Michael S

2010-07-15

Traditional Normarski differential interference contrast (DIC) microscopy is a very powerful method for imaging nonstained biological samples. However, one of its major limitations is the nonquantitative nature of the imaging. To overcome this problem, we developed a quantitative DIC microscopy method based on off-axis sample self-interference. The digital holography algorithm is applied to obtain quantitative phase gradients in orthogonal directions, which leads to a quantitative phase image through a spiral integration of the phase gradients. This method is practically simple to implement on any standard microscope without stringent requirements on polarization optics. Optical sectioning can be obtained through enlarged illumination NA.

Application of scanning acoustic microscopy to advanced structural ceramics

NASA Technical Reports Server (NTRS)

Vary, Alex; Klima, Stanley J.

1987-01-01

A review is presentod of research investigations of several acoustic microscopy techniques for application to structural ceramics for advanced heat engines. Results obtained with scanning acoustic microscopy (SAM), scanning laser acoustic microscopy (SLAM), scanning electron acoustic microscopy (SEAM), and photoacoustic microscopy (PAM) are compared. The techniques were evaluated on research samples of green and sintered monolithic silicon nitrides and silicon carbides in the form of modulus-of-rupture bars containing deliberately introduced flaws. Strengths and limitations of the techniques are described with emphasis on statistics of detectability of flaws that constitute potential fracture origins.

Spin-orbit scattering visualized in quasiparticle interference

NASA Astrophysics Data System (ADS)

Kohsaka, Y.; Machida, T.; Iwaya, K.; Kanou, M.; Hanaguri, T.; Sasagawa, T.

2017-03-01

In the presence of spin-orbit coupling, electron scattering off impurities depends on both spin and orbital angular momentum of electrons—spin-orbit scattering. Although some transport properties are subject to spin-orbit scattering, experimental techniques directly accessible to this effect are limited. Here we show that a signature of spin-orbit scattering manifests itself in quasiparticle interference (QPI) imaged by spectroscopic-imaging scanning tunneling microscopy. The experimental data of a polar semiconductor BiTeI are well reproduced by numerical simulations with the T -matrix formalism that include not only scalar scattering normally adopted but also spin-orbit scattering stronger than scalar scattering. To accelerate the simulations, we extend the standard efficient method of QPI calculation for momentum-independent scattering to be applicable even for spin-orbit scattering. We further identify a selection rule that makes spin-orbit scattering visible in the QPI pattern. These results demonstrate that spin-orbit scattering can exert predominant influence on QPI patterns and thus suggest that QPI measurement is available to detect spin-orbit scattering.

Possible superconductivity in Sr₂IrO₄ probed by quasiparticle interference.

PubMed

Gao, Yi; Zhou, Tao; Huang, Huaixiang; Wang, Qiang-Hua

2015-03-18

Based on the possible superconducting (SC) pairing symmetries recently proposed, the quasiparticle interference (QPI) patterns in electron- and hole-doped Sr₂IrO₄ are theoretically investigated. In the electron-doped case, the QPI spectra can be explained based on a model similar to the octet model of the cuprates while in the hole-doped case, both the Fermi surface topology and the sign of the SC order parameter resemble those of the iron pnictides and there exists a QPI vector resulting from the interpocket scattering between the electron and hole pockets. In both cases, the evolution of the QPI vectors with energy and their behaviors in the nonmagnetic and magnetic impurity scattering cases can well be explained based on the evolution of the constant-energy contours and the sign structure of the SC order parameter. The QPI spectra presented in this paper can be compared with future scanning tunneling microscopy experiments to test whether there are SC phases in electron- and hole-doped Sr₂IrO₄ and what the pairing symmetry is.

High-speed, random-access fluorescence microscopy: I. High-resolution optical recording with voltage-sensitive dyes and ion indicators.

PubMed

Bullen, A; Patel, S S; Saggau, P

1997-07-01

The design and implementation of a high-speed, random-access, laser-scanning fluorescence microscope configured to record fast physiological signals from small neuronal structures with high spatiotemporal resolution is presented. The laser-scanning capability of this nonimaging microscope is provided by two orthogonal acousto-optic deflectors under computer control. Each scanning point can be randomly accessed and has a positioning time of 3-5 microseconds. Sampling time is also computer-controlled and can be varied to maximize the signal-to-noise ratio. Acquisition rates up to 200k samples/s at 16-bit digitizing resolution are possible. The spatial resolution of this instrument is determined by the minimal spot size at the level of the preparation (i.e., 2-7 microns). Scanning points are selected interactively from a reference image collected with differential interference contrast optics and a video camera. Frame rates up to 5 kHz are easily attainable. Intrinsic variations in laser light intensity and scanning spot brightness are overcome by an on-line signal-processing scheme. Representative records obtained with this instrument by using voltage-sensitive dyes and calcium indicators demonstrate the ability to make fast, high-fidelity measurements of membrane potential and intracellular calcium at high spatial resolution (2 microns) without any temporal averaging.

High-speed, random-access fluorescence microscopy: I. High-resolution optical recording with voltage-sensitive dyes and ion indicators.

PubMed Central

Bullen, A; Patel, S S; Saggau, P

1997-01-01

The design and implementation of a high-speed, random-access, laser-scanning fluorescence microscope configured to record fast physiological signals from small neuronal structures with high spatiotemporal resolution is presented. The laser-scanning capability of this nonimaging microscope is provided by two orthogonal acousto-optic deflectors under computer control. Each scanning point can be randomly accessed and has a positioning time of 3-5 microseconds. Sampling time is also computer-controlled and can be varied to maximize the signal-to-noise ratio. Acquisition rates up to 200k samples/s at 16-bit digitizing resolution are possible. The spatial resolution of this instrument is determined by the minimal spot size at the level of the preparation (i.e., 2-7 microns). Scanning points are selected interactively from a reference image collected with differential interference contrast optics and a video camera. Frame rates up to 5 kHz are easily attainable. Intrinsic variations in laser light intensity and scanning spot brightness are overcome by an on-line signal-processing scheme. Representative records obtained with this instrument by using voltage-sensitive dyes and calcium indicators demonstrate the ability to make fast, high-fidelity measurements of membrane potential and intracellular calcium at high spatial resolution (2 microns) without any temporal averaging. Images FIGURE 6 PMID:9199810

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

Kirtley, John R., E-mail: jkirtley@stanford.edu; Rosenberg, Aaron J.; Palmstrom, Johanna C.

Superconducting QUantum Interference Device (SQUID) microscopy has excellent magnetic field sensitivity, but suffers from modest spatial resolution when compared with other scanning probes. This spatial resolution is determined by both the size of the field sensitive area and the spacing between this area and the sample surface. In this paper we describe scanning SQUID susceptometers that achieve sub-micron spatial resolution while retaining a white noise floor flux sensitivity of ≈2μΦ{sub 0}/Hz{sup 1/2}. This high spatial resolution is accomplished by deep sub-micron feature sizes, well shielded pickup loops fabricated using a planarized process, and a deep etch step that minimizes themore » spacing between the sample surface and the SQUID pickup loop. We describe the design, modeling, fabrication, and testing of these sensors. Although sub-micron spatial resolution has been achieved previously in scanning SQUID sensors, our sensors not only achieve high spatial resolution but also have integrated modulation coils for flux feedback, integrated field coils for susceptibility measurements, and batch processing. They are therefore a generally applicable tool for imaging sample magnetization, currents, and susceptibilities with higher spatial resolution than previous susceptometers.« less

Application of Nomarski DIC and cathodoluminescence (CL) microscopy to building materials

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

Goetze, J., E-mail: goetze@mineral.tu-freiberg.de

2009-07-15

The present study discusses the potential of an integrated application of Nomarski differential interference contrast and cathodoluminescence microscopy for the investigation of building materials such as natural stone, cement, mortar and concrete. Nomarski differential interference contrast microscopy is a modern technique applied in materials sciences to visualize different phases and/or to image the surface relief on the scale of 50 nm. It is based on the principle of beam splitting by a double-crystal prism split, resulting in the superposition of laterally shifted wave fronts. In cathodoluminescence microscopy, the luminescence signal is excited by an electron beam and is generated bymore » different point defects within the material. Therefore, cathodoluminescence is a powerful method to characterize the defect structure of solid materials, to distinguish different phases and to reveal detailed information about their chemical composition. By combining Nomarski differential interference contrast and cathodoluminescence microscopy, textural, crystallographic and chemical information can be obtained from the same sample area in a polished thin section.« less

Remote optical sensing on the nanometer scale with a bowtie aperture nano-antenna on a fiber tip of scanning near-field optical microscopy

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

Atie, Elie M.; Xie, Zhihua; El Eter, Ali

2015-04-13

Plasmonic nano-antennas have proven the outstanding ability of sensing chemical and physical processes down to the nanometer scale. Sensing is usually achieved within the highly confined optical fields generated resonantly by the nano-antennas, i.e., in contact to the nanostructures. In this paper, we demonstrate the sensing capability of nano-antennas to their larger scale environment, well beyond their plasmonic confinement volume, leading to the concept of “remote” (non contact) sensing on the nanometer scale. On the basis of a bowtie-aperture nano-antenna (BNA) integrated at the apex of a SNOM (Scanning Near-field Optical Microscopy) fiber tip, we introduce an ultra-compact, moveable, andmore » background-free optical nanosensor for the remote sensing of a silicon surface (up to distance of 300 nm). Sensitivity of the BNA to its large scale environment is high enough to expect the monitoring and control of the spacing between the nano-antenna and a silicon surface with sub-nanometer accuracy. This work paves the way towards an alternative class of nanopositioning techniques, based on the monitoring of diffraction-free plasmon resonance, that are alternative to nanomechanical and diffraction-limited optical interference-based devices.« less

Scanning ion-conductance and atomic force microscope with specialized sphere-shaped nanopippettes

NASA Astrophysics Data System (ADS)

Zhukov, M. V.; Sapozhnikov, I. D.; Golubok, A. O.; Chubinskiy-Nadezhdin, V. I.; Komissarenko, F. E.; Lukashenko, S. Y.

2017-11-01

A scanning ion-conductance microscope was designed on the basis of scanning probe microscope NanoTutor. The optimal parameters of nanopipettes fabrication were found according to scanning electron microscopy diagnostics, current-distance I (Z) and current-voltage characteristics. A comparison of images of test objects, including biological samples, was carried out in the modes of optical microscopy, atomic force microscopy and scanning ion-conductance microscopy. Sphere-shaped nanopippettes probes were developed and tested to increase the stability of pipettes, reduce invasiveness and improve image quality of atomic force microscopy in tapping mode. The efficiency of sphere-shaped nanopippettes is shown.

Application of environmental scanning electron microscopy to determine biological surface structure.

PubMed

Kirk, S E; Skepper, J N; Donald, A M

2009-02-01

The use of environmental scanning electron microscopy in biology is growing as more becomes understood about the advantages and limitations of the technique. These are discussed and we include new evidence about the effect of environmental scanning electron microscopy imaging on the viability of mammalian cells. We show that although specimen preparation for high-vacuum scanning electron microscopy introduces some artefacts, there are also challenges in the use of environmental scanning electron microscopy, particularly at higher resolutions. This suggests the two technologies are best used in combination. We have used human monocyte-derived macrophages as a test sample, imaging their complicated and delicate membrane ruffles and protrusions. We have also explored the possibility of using environmental scanning electron microscopy for dynamic experiments, finding that mammalian cells cannot be imaged and kept alive in the environmental scanning electron microscopy. The dehydration step in which the cell surface is exposed causes irreversible damage, probably via loss of membrane integrity during liquid removal in the specimen chamber. Therefore, mammalian cells should be imaged after fixation where possible to protect against damage as a result of chamber conditions.

Leakage radiation interference microscopy.

PubMed

Descrovi, Emiliano; Barakat, Elsie; Angelini, Angelo; Munzert, Peter; De Leo, Natascia; Boarino, Luca; Giorgis, Fabrizio; Herzig, Hans Peter

2013-09-01

We present a proof of principle for a new imaging technique combining leakage radiation microscopy with high-resolution interference microscopy. By using oil immersion optics it is demonstrated that amplitude and phase can be retrieved from optical fields, which are evanescent in air. This technique is illustratively applied for mapping a surface mode propagating onto a planar dielectric multilayer on a thin glass substrate. The surface mode propagation constant estimated after Fourier transformation of the measured complex field is well matched with an independent measurement based on back focal plane imaging.

Visualizing ferroic domains in an all-in-all-out antiferromagnet thin film

NASA Astrophysics Data System (ADS)

Kozuka, Y.; Fujita, T. C.; Uchida, M.; Nojima, T.; Tsukazaki, A.; Matsuno, J.; Arima, T.; Kawasaki, M.

2017-12-01

Antiferromagnetic domain distribution is analyzed by a scanning superconducting quantum interference device microscopy for a pyrochlore T b2I r2O7 thin film with an all-in-all-out (AIAO) spin arrangement. The local magnetic field on the surface is found to originate predominantly from the T b3 +(J =6 ) magnetic moment. While I r4 + magnetic moment (Jeff=1 /2 ) is too small to detect even below the Néel temperature (120 K), T b3 + AIAO domains grow below 40 K following the background I r4 + domains rather than the external magnetic field, clarifying the decisive role of Ir-Tb exchange interaction in magnetic ordering.

Visual scanning with or without spatial uncertainty and time-sharing performance

NASA Technical Reports Server (NTRS)

Liu, Yili; Wickens, Christopher D.

1989-01-01

An experiment is reported that examines the pattern of task interference between visual scanning as a sequential and selective attention process and other concurrent spatial or verbal processing tasks. A distinction is proposed between visual scanning with or without spatial uncertainty regarding the possible differential effects of these two types of scanning on interference with other concurrent processes. The experiment required the subject to perform a simulated primary tracking task, which was time-shared with a secondary spatial or verbal decision task. The relevant information that was needed to perform the decision tasks were displayed with or without spatial uncertainty. The experiment employed a 2 x 2 x 2 design with types of scanning (with or without spatial uncertainty), expected scanning distance (low/high), and codes of concurrent processing (spatial/verbal) as the three experimental factors. The results provide strong evidence that visual scanning as a spatial exploratory activity produces greater task interference with concurrent spatial tasks than with concurrent verbal tasks. Furthermore, spatial uncertainty in visual scanning is identified to be the crucial factor in producing this differential effect.

Dynamical measurements of motion behavior of free fluorescent sphere using the wide field temporal focusing microscopy with astigmatism method (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lien, Chi-Hsiang; Lin, Chun-Yu; Chen, Shean-Jen; Chien, Fan-Ching

2017-02-01

A three-dimensional (3D) single fluorescent particle tracking strategy based on temporal focusing multiphoton excitation microscopy (TFMPEM) combined with astigmatism imaging is proposed for delivering nanoscale-level axial information that reveals 3D trajectories of single fluorospheres in the axially-resolved multiphoton excitation volume without z-axis scanning. It provides the dynamical ability by measuring the diffusion coefficient of fluorospheres in glycerol solutions with a position standard deviation of 14 nm and 21 nm in the lateral and axial direction and a frame rate of 100 Hz. Moreover, the optical trapping force based on the TFMPEM is minimized to avoid the interference in the tracing measurements compared to that in the spatial focusing MPE approaches. Therefore, we presented a three dimensional single particle tracking strategy to overcome the limitation of the time resolution of the multiphoton imaging using fast frame rate of TFMPEM, and provide three dimensional locations of multiple particles using an astigmatism method.

Electrical Properties of the V-Defects of Epitaxial HgCdTe

NASA Astrophysics Data System (ADS)

Novikov, V. A.; Grigoryev, D. V.; Bezrodnyy, D. A.; Voitsekhovskii, A. V.; Dvoretsky, S. A.; Mikhailov, N. N.

2017-07-01

The manufacturing process of wide-band-gap matrix photodetector devices and miniaturization of their individual pixels gave rise to increased demands on the material quality and research methods. In the present paper we propose using the methods of atomic-force microscopy to study the local distribution of electrical properties of the V-defects that form in epitaxial films of HgCdTe during their growth process via molecular beam epitaxy. We demonstrate that a complex approach to studying the electrical properties of a predefined region of a V-defect allows one to obtain more detailed information on its properties. Using scanning spreading resistance microscopy, we show that, for a V-defect when the applied bias is increased, the surface area that participates in the process of charge carrier transfer also increases almost linearly. The presence of a potential barrier on the periphery of individual crystal grains that form the V-defect interferes with the flow of current and also affects the distribution of surface potential and capacitive contrast.

Microscopy image segmentation tool: Robust image data analysis

NASA Astrophysics Data System (ADS)

Valmianski, Ilya; Monton, Carlos; Schuller, Ivan K.

2014-03-01

We present a software package called Microscopy Image Segmentation Tool (MIST). MIST is designed for analysis of microscopy images which contain large collections of small regions of interest (ROIs). Originally developed for analysis of porous anodic alumina scanning electron images, MIST capabilities have been expanded to allow use in a large variety of problems including analysis of biological tissue, inorganic and organic film grain structure, as well as nano- and meso-scopic structures. MIST provides a robust segmentation algorithm for the ROIs, includes many useful analysis capabilities, and is highly flexible allowing incorporation of specialized user developed analysis. We describe the unique advantages MIST has over existing analysis software. In addition, we present a number of diverse applications to scanning electron microscopy, atomic force microscopy, magnetic force microscopy, scanning tunneling microscopy, and fluorescent confocal laser scanning microscopy.

Chitosan coated carbon fiber microelectrode for selective in vivo detection of neurotransmitters in live zebrafish embryos

PubMed Central

Özel, Rıfat Emrah; Wallace, Kenneth N.; Andreescu, Silvana

2011-01-01

We report the development of a chitosan modified carbon fiber microelectrode for in vivo detection of serotonin. We find that chitosan has the ability to reject physiological levels of ascorbic acid interferences and facilitate selective and sensitive detection of in vivo levels of serotonin, a common catecholamine neurotransmitter. Presence of chitosan on the microelectrode surface was investigated using scanning electron microscopy (SEM) and cyclic voltammetry (CV). The electrode was characterized using differential pulse voltammetry (DPV). A detection limit of 1.6 nM serotonin with a sensitivity of 5.12 nA/µM, a linear range from 2 to 100 nM and a reproducibility of 6.5 % for n=6 electrodes were obtained. Chitosan modified microelectrodes selectively measure serotonin in presence of physiological levels of ascorbic acid. In vivo measurements were performed to measure concentration of serotonin in the live embryonic zebrafish intestine. The sensor quantifies in vivo intestinal levels of serotonin while successfully rejecting ascorbic acid interferences. We demonstrate that chitosan can be used as an effective coating to reject ascorbic acid interferences at carbon fiber microelectrodes, as an alternative to Nafion, and that chitosan modified microelectrodes are reliable tools for in vivo monitoring of changes in neurotransmitter levels. PMID:21601035

Interference Confocal Microscope Integrated with Spatial Phase Shifter.

PubMed

Wang, Weibo; Gu, Kang; You, Xiaoyu; Tan, Jiubin; Liu, Jian

2016-08-24

We present an interference confocal microscope (ICM) with a new single-body four-step simultaneous phase-shifter device designed to obtain high immunity to vibration. The proposed ICM combines the respective advantages of simultaneous phase shifting interferometry and bipolar differential confocal microscopy to obtain high axis resolution, large dynamic range, and reduce the sensitivity to vibration and reflectance disturbance seamlessly. A compact single body spatial phase shifter is added to capture four phase-shifted interference signals simultaneously without time delay and construct a stable and space-saving simplified interference confocal microscope system. The test result can be obtained by combining the interference phase response and the bipolar property of differential confocal microscopy without phase unwrapping. Experiments prove that the proposed microscope is capable of providing stable measurements with 1 nm of axial depth resolution for either low- or high-numerical aperture objective lenses.

Nanoscale electrical property studies of individual GeSi quantum rings by conductive scanning probe microscopy.

PubMed

Lv, Yi; Cui, Jian; Jiang, Zuimin M; Yang, Xinju

2012-11-29

The nanoscale electrical properties of individual self-assembled GeSi quantum rings (QRs) were studied by scanning probe microscopy-based techniques. The surface potential distributions of individual GeSi QRs are obtained by scanning Kelvin microscopy (SKM). Ring-shaped work function distributions are observed, presenting that the QRs' rim has a larger work function than the QRs' central hole. By combining the SKM results with those obtained by conductive atomic force microscopy and scanning capacitance microscopy, the correlations between the surface potential, conductance, and carrier density distributions are revealed, and a possible interpretation for the QRs' conductance distributions is suggested.

Holographic techniques for cellular fluorescence microscopy

NASA Astrophysics Data System (ADS)

Kim, Myung K.

2017-04-01

We have constructed a prototype instrument for holographic fluorescence microscopy (HFM) based on self-interference incoherent digital holography (SIDH) and demonstrate novel imaging capabilities such as differential 3D fluorescence microscopy and optical sectioning by compressive sensing.

The response of an individual vortex to local mechanical contact

NASA Astrophysics Data System (ADS)

Kremen, Anna; Wissberg, Shai; Shperber, Yishai; Kalisky, Beena

2016-05-01

Recently we reported a new way to manipulate vortices in thin superconducting films by local mechanical contact without magnetic field, current or altering the pinning landscape [1]. We use scanning superconducting interference device (SQUID) microscopy to image the vortices, and a piezo element to push the tip of a silicon chip into contact with the sample. As a result of the stress applied at the contact point, vortices in the proximity of the contact point change their location. Here we study the characteristics of this vortex manipulation, by following the response of individual vortices to single contact events. Mechanical manipulation of vortices provides local view of the interaction between strain and nanomagnetic objects, as well as controllable, effective, localized, and reproducible manipulation technique.

Intimate effects of surface functionalization of porous silicon microcavities on biosensing performance

NASA Astrophysics Data System (ADS)

Martin, M.; Massif, L.; Estephan, E.; Saab, M.-b.; Cloitre, T.; Larroque, C.; Agarwal, V.; Cuisinier, F. J. G.; Le Lay, G.; Gergely, C.

2011-10-01

We study the effect of different surface functionalization methods on the sensing performances of porous silicon (PSi) microcavities when used for detection of biomolecules. Previous research on porous silicon demonstrated versatility of these devices for sensor applications based on their photonic responses. The interface between biological molecules and the Si semiconductor surface is a key issue for improving biomolecular recognition in these devices. PSi microcavities were fabricated to reveal reflectivity pass-band spectra in the visible and near-infrared domain. To assure uniform infiltration of proteins the number of layers of Bragg mirrors was limited to five, the first layer being of high porosity. In one approach the devices were thermally oxidized and functionalized to assure covalent binding of molecules. Secondly, the as etched PSi surface was modified with adhesion peptides isolated via phage display technology and presenting high binding capacity for Si. Functionalization and molecular binding events were monitored via reflectometric interference spectra as shifts in the resonance peaks of the cavity structure due to changes in the refractive index when a biomolecule is attached to the large internal surface of PSi. Improved sensitivity is obtained due to the peptide interface linkers between the PSi and biological molecules compared to the silanized devices. We investigate the formation of peptide-Si interface layer via X-ray photoelectron spectroscopy, scanning tunneling microscopy and scanning electron microscopy.

Spectroscopic imaging scanning tunneling microscopy of a Dirac line node material ZrSiS

NASA Astrophysics Data System (ADS)

Zhou, Lihui; He, Qingyu; Queiroz, Raquel; Grüneis, Andreas; Schnyder, Andreas; Ast, Christian; Schoop, Leslie; Takagi, Hide; Rost, Andreas

3D Dirac materials are an intensive area of current condensed matter research. The related Dirac line node materials have come into focus due to many shared properties such as unconventional magneto-transport and the potential to host topologically nontrivial phases. ZrSiS is one of the first discovered materials of this new family, hosting a nodal line and an unconventional surface state. Spectroscopic imaging scanning tunneling microscopy (SI-STM) detects quasiparticle interference and has been extensively used to study the scattering mechanism and the band structures of exotic materials with high energy resolution at the atomic scale. Here in this presentation, we report the investigation of ZrSiS by SI-STM at the atomic scale, in combination with DFT calculations. We succeeded in visualizing the Dirac nodal line both in real and momentum space, adding key pieces of evidences confirming the existence of a nodal line in this material and highlighting its exceptional properties. The breaking of a non-symmorphic symmetry at the surface induces an unusual surface state whose dispersion was mapped. In particular, we observed spectroscopic signatures of a type-II Dirac fermion hosted by the surface state. Our data as seen by SI-STM has impact beyond ZrSiS providing crucial insights into the properties of Dirac line node materials in particular and non-symmorphic crystals in general.

Three-dimensional scanning near field optical microscopy (3D-SNOM) imaging of random arrays of copper nanoparticles: implications for plasmonic solar cell enhancement.

PubMed

Ezugwu, Sabastine; Ye, Hanyang; Fanchini, Giovanni

2015-01-07

In order to investigate the suitability of random arrays of nanoparticles for plasmonic enhancement in the visible-near infrared range, we introduced three-dimensional scanning near-field optical microscopy (3D-SNOM) imaging as a useful technique to probe the intensity of near-field radiation scattered by random systems of nanoparticles at heights up to several hundred nm from their surface. We demonstrated our technique using random arrays of copper nanoparticles (Cu-NPs) at different particle diameter and concentration. Bright regions in the 3D-SNOM images, corresponding to constructive interference of forward-scattered plasmonic waves, were obtained at heights Δz ≥ 220 nm from the surface for random arrays of Cu-NPs of ∼ 60-100 nm in diameter. These heights are too large to use Cu-NPs in contact of the active layer for light harvesting in thin organic solar cells, which are typically no thicker than 200 nm. Using a 200 nm transparent spacer between the system of Cu-NPs and the solar cell active layer, we demonstrate that forward-scattered light can be conveyed in 200 nm thin film solar cells. This architecture increases the solar cell photoconversion efficiency by a factor of 3. Our 3D-SNOM technique is general enough to be suitable for a large number of other applications in nanoplasmonics.

2D strain mapping using scanning transmission electron microscopy Moiré interferometry and geometrical phase analysis.

PubMed

Pofelski, A; Woo, S Y; Le, B H; Liu, X; Zhao, S; Mi, Z; Löffler, S; Botton, G A

2018-04-01

A strain characterization technique based on Moiré interferometry in a scanning transmission electron microscope (STEM) and geometrical phase analysis (GPA) method is demonstrated. The deformation field is first captured in a single STEM Moiré hologram composed of multiple sets of periodic fringes (Moiré patterns) generated from the interference between the periodic scanning grating, fixing the positions of the electron probe on the sample, and the crystal structure. Applying basic principles from sampling theory, the Moiré patterns arrangement is then simulated using a STEM electron micrograph reference to convert the experimental STEM Moiré hologram into information related to the crystal lattice periodicities. The GPA method is finally applied to extract the 2D relative strain and rotation fields. The STEM Moiré interferometry enables the local information to be de-magnified to a large length scale, comparable to what can be achieved in dark-field electron holography. The STEM Moiré GPA method thus extends the conventional high-resolution STEM GPA capabilities by providing comparable quantitative 2D strain mapping with a larger field of view (up to a few microns). Copyright © 2017 Elsevier B.V. All rights reserved.

Inorganic nanotubes reinforced polyvinylidene fluoride composites as low-cost electromagnetic interference shielding materials

PubMed Central

2011-01-01

Novel polymer nanocomposites comprising of MnO2 nanotubes (MNTs), functionalized multiwalled carbon nanotubes (f-MWCNTs), and polyvinylidene fluoride (PVDF) were synthesized. Homogeneous distribution of f-MWCNTs and MNTs in PVDF matrix were confirmed by field emission scanning electron microscopy. Electrical conductivity measurements were performed on these polymer composites using four probe technique. The addition of 2 wt.% of MNTs (2 wt.%, f-MWCNTs) to PVDF matrix results in an increase in the electrical conductivity from 10-16S/m to 4.5 × 10-5S/m (3.2 × 10-1S/m). Electromagnetic interference shielding effectiveness (EMI SE) was measured with vector network analyzer using waveguide sample holder in X-band frequency range. EMI SE of approximately 20 dB has been obtained with the addition of 5 wt.% MNTs-1 wt.% f-MWCNTs to PVDF in comparison with EMI SE of approximately 18 dB for 7 wt.% of f-MWCNTs indicating the potential use of the present MNT/f-MWCNT/PVDF composite as low-cost EMI shielding materials in X-band region. PMID:21711633

Possible superconductivity in Sr2IrO4 probed by quasiparticle interference

PubMed Central

Gao, Yi; Zhou, Tao; Huang, Huaixiang; Wang, Qiang-Hua

2015-01-01

Based on the possible superconducting (SC) pairing symmetries recently proposed, the quasiparticle interference (QPI) patterns in electron- and hole-doped Sr2IrO4 are theoretically investigated. In the electron-doped case, the QPI spectra can be explained based on a model similar to the octet model of the cuprates while in the hole-doped case, both the Fermi surface topology and the sign of the SC order parameter resemble those of the iron pnictides and there exists a QPI vector resulting from the interpocket scattering between the electron and hole pockets. In both cases, the evolution of the QPI vectors with energy and their behaviors in the nonmagnetic and magnetic impurity scattering cases can well be explained based on the evolution of the constant-energy contours and the sign structure of the SC order parameter. The QPI spectra presented in this paper can be compared with future scanning tunneling microscopy experiments to test whether there are SC phases in electron- and hole-doped Sr2IrO4 and what the pairing symmetry is. PMID:25783417

Scanning Capacitance Microscopy | Materials Science | NREL

Science.gov Websites

obtained using scanning capacitance microscopy. Top Right: Image of p-type and n-type material, obtained 'fingers' of light-colored n-type material on a yellow and blue background representing p-type material ; measurement data were obtained using scanning capacitance microscopy. Bottom Right: Image of p-type and n-type

Resonant Scanning with Large Field of View Reduces Photobleaching and Enhances Fluorescence Yield in STED Microscopy.

PubMed

Wu, Yong; Wu, Xundong; Lu, Rong; Zhang, Jin; Toro, Ligia; Stefani, Enrico

2015-10-01

Photobleaching is a major limitation of superresolution Stimulated Depletion Emission (STED) microscopy. Fast scanning has long been considered an effective means to reduce photobleaching in fluorescence microscopy, but a careful quantitative study of this issue is missing. In this paper, we show that the photobleaching rate in STED microscopy can be slowed down and the fluorescence yield be enhanced by scanning with high speed, enabled by using large field of view in a custom-built resonant-scanning STED microscope. The effect of scanning speed on photobleaching and fluorescence yield is more remarkable at higher levels of depletion laser irradiance, and virtually disappears in conventional confocal microscopy. With ≥6 GW∙cm(-2) depletion irradiance, we were able to extend the fluorophore survival time of Atto 647N and Abberior STAR 635P by ~80% with 8-fold wider field of view. We confirm that STED Photobleaching is primarily caused by the depletion light acting upon the excited fluorophores. Experimental data agree with a theoretical model. Our results encourage further increasing the linear scanning speed for photobleaching reduction in STED microscopy.

Re-scan confocal microscopy: scanning twice for better resolution.

PubMed

De Luca, Giulia M R; Breedijk, Ronald M P; Brandt, Rick A J; Zeelenberg, Christiaan H C; de Jong, Babette E; Timmermans, Wendy; Azar, Leila Nahidi; Hoebe, Ron A; Stallinga, Sjoerd; Manders, Erik M M

2013-01-01

We present a new super-resolution technique, Re-scan Confocal Microscopy (RCM), based on standard confocal microscopy extended with an optical (re-scanning) unit that projects the image directly on a CCD-camera. This new microscope has improved lateral resolution and strongly improved sensitivity while maintaining the sectioning capability of a standard confocal microscope. This simple technology is typically useful for biological applications where the combination high-resolution and high-sensitivity is required.

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

PubMed

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

2015-01-01

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

Microstructure of milk

USDA-ARS?s Scientific Manuscript database

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

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

NASA Astrophysics Data System (ADS)

Han, Wenfeng; Xiao, Zexin; Wang, Xiaofen

2009-11-01

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

Chemical mapping and quantification at the atomic scale by scanning transmission electron microscopy.

PubMed

Chu, Ming-Wen; Chen, Cheng Hsuan

2013-06-25

With innovative modern material-growth methods, a broad spectrum of fascinating materials with reduced dimensions-ranging from single-atom catalysts, nanoplasmonic and nanophotonic materials to two-dimensional heterostructural interfaces-is continually emerging and extending the new frontiers of materials research. A persistent central challenge in this grand scientific context has been the detailed characterization of the individual objects in these materials with the highest spatial resolution, a problem prompting the need for experimental techniques that integrate both microscopic and spectroscopic capabilities. To date, several representative microscopy-spectroscopy combinations have become available, such as scanning tunneling microscopy, tip-enhanced scanning optical microscopy, atom probe tomography, scanning transmission X-ray microscopy, and scanning transmission electron microscopy (STEM). Among these tools, STEM boasts unique chemical and electronic sensitivity at unparalleled resolution. In this Perspective, we elucidate the advances in STEM and chemical mapping applications at the atomic scale by energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy with a focus on the ultimate challenge of chemical quantification with atomic accuracy.

TOPICAL REVIEW: Aspects of scanning force microscope probes and their effects on dimensional measurement

NASA Astrophysics Data System (ADS)

Yacoot, Andrew; Koenders, Ludger

2008-05-01

The review will describe the various scanning probe microscopy tips and cantilevers used today for scanning force microscopy and magnetic force microscopy. Work undertaken to quantify the properties of cantilevers and tips, e.g. shape and radius, is reviewed together with an overview of the various tip-sample interactions that affect dimensional measurements.

PSD microscopy: a new technique for adaptive local scanning of microscale objects.

PubMed

Rahimi, Mehdi; Shen, Yantao

2017-01-01

A position-sensitive detector/device (PSD) is a sensor that is capable of tracking the location of a laser beam on its surface. PSDs are used in many scientific instruments and technical applications including but not limited to atomic force microscopy, human eye movement monitoring, mirrors or machine tool alignment, vibration analysis, beam position control and so on. This work intends to propose a new application using the PSD. That is a new microscopy system called scanning PSD microscopy. The working mechanism is about putting an object on the surface of the PSD and fast scanning its area with a laser beam. To achieve a high degree of accuracy and precision, a reliable framework was designed using the PSD. In this work, we first tried to improve the PSD reading and its measurement performance. This was done by minimizing the effects of noise, distortion and other disturbing parameters. After achieving a high degree of confidence, the microscopy system can be implemented based on the improved PSD measurement performance. Later to improve the scanning efficiency, we developed an adaptive local scanning system to scan the whole area of the PSD in a short matter of time. It was validated that our comprehensive and adaptive local scanning method can shorten the scanning time in order of hundreds of times in comparison with the traditional raster scanning without losing any important information about the scanned 2D objects. Methods are also introduced to scan very complicated objects with bifurcations and crossings. By incorporating all these methods, the new microscopy system is capable of scanning very complicated objects in the matter of a few seconds with a resolution that is in order of a few micrometers.

Coherent total internal reflection dark-field microscopy: label-free imaging beyond the diffraction limit.

PubMed

von Olshausen, Philipp; Rohrbach, Alexander

2013-10-15

Coherent imaging is barely applicable in life-science microscopy due to multiple interference artifacts. Here, we show how these interferences can be used to improve image resolution and contrast. We present a dark-field microscopy technique with evanescent illumination via total internal reflection that delivers high-contrast images of coherently scattering samples. By incoherent averaging of multiple coherent images illuminated from different directions we can resolve image structures that remain unresolved by conventional (incoherent) fluorescence microscopy. We provide images of 190 nm beads revealing resolution beyond the diffraction limit and slightly increased object distances. An analytical model is introduced that accounts for the observed effects and which is confirmed by numerical simulations. Our approach may be a route to fast, label-free, super-resolution imaging in live-cell microscopy.

Three-dimensional imaging of micro-specimen by optical scanning holography

NASA Astrophysics Data System (ADS)

Liu, Jung-Ping; Tsou, Cheng-Hao

2017-04-01

Optical scanning holography (OSH) is a scanning-type digital holographic technique. In OSH, a heterodyne interference pattern is generated to raster scan the object. OSH can be operated in the incoherent mode and thus is able to record a fluorescence hologram. In addition, resolution of the OSH is proportional to the density of the interference pattern. Here we use a high-NA microscope objective to generate a dynamic Fresnel zone plate to record a hologram of micro-specimen. The achieved transverse resolution and longitudinal resolution are 0.78μm and 3.1μm, respectively.

Hyperspectral imaging with laser-scanning sum-frequency generation microscopy

PubMed Central

Hanninen, Adam; Shu, Ming Wai; Potma, Eric O.

2017-01-01

Vibrationally sensitive sum-frequency generation (SFG) microscopy is a chemically selective imaging technique sensitive to non-centrosymmetric molecular arrangements in biological samples. The routine use of SFG microscopy has been hampered by the difficulty of integrating the required mid-infrared excitation light into a conventional, laser-scanning nonlinear optical (NLO) microscope. In this work, we describe minor modifications to a regular laser-scanning microscope to accommodate SFG microscopy as an imaging modality. We achieve vibrationally sensitive SFG imaging of biological samples with sub-μm resolution at image acquisition rates of 1 frame/s, almost two orders of magnitude faster than attained with previous point-scanning SFG microscopes. Using the fast scanning capability, we demonstrate hyperspectral SFG imaging in the CH-stretching vibrational range and point out its use in the study of molecular orientation and arrangement in biologically relevant samples. We also show multimodal imaging by combining SFG microscopy with second-harmonic generation (SHG) and coherent anti-Stokes Raman scattering (CARS) on the same imaging platfrom. This development underlines that SFG microscopy is a unique modality with a spatial resolution and image acquisition time comparable to that of other NLO imaging techniques, making point-scanning SFG microscopy a valuable member of the NLO imaging family. PMID:28966861

Re-scan confocal microscopy: scanning twice for better resolution

PubMed Central

De Luca, Giulia M.R.; Breedijk, Ronald M.P.; Brandt, Rick A.J.; Zeelenberg, Christiaan H.C.; de Jong, Babette E.; Timmermans, Wendy; Azar, Leila Nahidi; Hoebe, Ron A.; Stallinga, Sjoerd; Manders, Erik M.M.

2013-01-01

We present a new super-resolution technique, Re-scan Confocal Microscopy (RCM), based on standard confocal microscopy extended with an optical (re-scanning) unit that projects the image directly on a CCD-camera. This new microscope has improved lateral resolution and strongly improved sensitivity while maintaining the sectioning capability of a standard confocal microscope. This simple technology is typically useful for biological applications where the combination high-resolution and high-sensitivity is required. PMID:24298422

Frequency-controls of electromagnetic multi-beam scanning by metasurfaces.

PubMed

Li, Yun Bo; Wan, Xiang; Cai, Ben Geng; Cheng, Qiang; Cui, Tie Jun

2014-11-05

We propose a method to control electromagnetic (EM) radiations by holographic metasurfaces, including to producing multi-beam scanning in one dimension (1D) and two dimensions (2D) with the change of frequency. The metasurfaces are composed of subwavelength metallic patches on grounded dielectric substrate. We present a combined theory of holography and leaky wave to realize the multi-beam radiations by exciting the surface interference patterns, which are generated by interference between the excitation source and required radiation waves. As the frequency changes, we show that the main lobes of EM radiation beams could accomplish 1D or 2D scans regularly by using the proposed holographic metasurfaces shaped with different interference patterns. This is the first time to realize 2D scans of antennas by changing the frequency. Full-wave simulations and experimental results validate the proposed theory and confirm the corresponding physical phenomena.

Optical magnetic imaging of living cells

PubMed Central

Le Sage, D.; Arai, K.; Glenn, D. R.; DeVience, S. J.; Pham, L. M.; Rahn-Lee, L.; Lukin, M. D.; Yacoby, A.; Komeili, A.; Walsworth, R. L.

2013-01-01

Magnetic imaging is a powerful tool for probing biological and physical systems. However, existing techniques either have poor spatial resolution compared to optical microscopy and are hence not generally applicable to imaging of sub-cellular structure (e.g., magnetic resonance imaging [MRI]1), or entail operating conditions that preclude application to living biological samples while providing sub-micron resolution (e.g., scanning superconducting quantum interference device [SQUID] microscopy2, electron holography3, and magnetic resonance force microscopy [MRFM]4). Here we demonstrate magnetic imaging of living cells (magnetotactic bacteria) under ambient laboratory conditions and with sub-cellular spatial resolution (400 nm), using an optically-detected magnetic field imaging array consisting of a nanoscale layer of nitrogen-vacancy (NV) colour centres implanted at the surface of a diamond chip. With the bacteria placed on the diamond surface, we optically probe the NV quantum spin states and rapidly reconstruct images of the vector components of the magnetic field created by chains of magnetic nanoparticles (magnetosomes) produced in the bacteria, and spatially correlate these magnetic field maps with optical images acquired in the same apparatus. Wide-field sCMOS acquisition allows parallel optical and magnetic imaging of multiple cells in a population with sub-micron resolution and >100 micron field-of-view. Scanning electron microscope (SEM) images of the bacteria confirm that the correlated optical and magnetic images can be used to locate and characterize the magnetosomes in each bacterium. The results provide a new capability for imaging bio-magnetic structures in living cells under ambient conditions with high spatial resolution, and will enable the mapping of a wide range of magnetic signals within cells and cellular networks5, 6. PMID:23619694

Realistic representation of Bacillus subtilis biofilms architecture using combined microscopy (CLSM, ESEM and FESEM).

PubMed

Bridier, A; Meylheuc, T; Briandet, R

2013-05-01

In this contribution, we used a set of microscopic techniques including confocal laser scanning microscopy (CLSM), environmental scanning electron microscopy (ESEM) and field emission scanning electron microscopy (FESEM) to analyze the three-dimensional spatial arrangement of cells and their surrounding matrix in Bacillus subtilis biofilm. The combination of the different techniques enabled a deeper and realistic deciphering of biofilm architecture by providing the opportunity to overcome the limits of each single technique. Copyright © 2013 Elsevier Ltd. All rights reserved.

Scanning Transmission Electron Microscopy | Materials Science | NREL

Science.gov Websites

mode by collecting the EDS and EELS signals point-by-point as one scans the electron probe across the . Examples of Scanning Transmission Electron Microscopy Capabilities Z-contrast image microphoto taken by

Plant cell wall characterization using scanning probe microscopy techniques

PubMed Central

Yarbrough, John M; Himmel, Michael E; Ding, Shi-You

2009-01-01

Lignocellulosic biomass is today considered a promising renewable resource for bioenergy production. A combined chemical and biological process is currently under consideration for the conversion of polysaccharides from plant cell wall materials, mainly cellulose and hemicelluloses, to simple sugars that can be fermented to biofuels. Native plant cellulose forms nanometer-scale microfibrils that are embedded in a polymeric network of hemicelluloses, pectins, and lignins; this explains, in part, the recalcitrance of biomass to deconstruction. The chemical and structural characteristics of these plant cell wall constituents remain largely unknown today. Scanning probe microscopy techniques, particularly atomic force microscopy and its application in characterizing plant cell wall structure, are reviewed here. We also further discuss future developments based on scanning probe microscopy techniques that combine linear and nonlinear optical techniques to characterize plant cell wall nanometer-scale structures, specifically apertureless near-field scanning optical microscopy and coherent anti-Stokes Raman scattering microscopy. PMID:19703302

Histological Analysis of the Arabidopsis Gynoecium and Ovules Using Chloral Hydrate Clearing and Differential Interference Contrast Light Microscopy.

PubMed

Franks, Robert G

2016-01-01

The use of chloral hydrate optical clearing paired with differential interference contrast microscopy allows the analysis of internal structures of developing plant organs without the need for paraffin embedding and sectioning. This approach is appropriate for the analysis of the developing gynoecium or seedpod of the flowering plant Arabidopsis thaliana and many other types of fixed plant material. Early stages of ovule development are observable with this approach.

Dual-detection confocal fluorescence microscopy: fluorescence axial imaging without axial scanning.

PubMed

Lee, Dong-Ryoung; Kim, Young-Duk; Gweon, Dae-Gab; Yoo, Hongki

2013-07-29

We propose a new method for high-speed, three-dimensional (3-D) fluorescence imaging, which we refer to as dual-detection confocal fluorescence microscopy (DDCFM). In contrast to conventional beam-scanning confocal fluorescence microscopy, where the focal spot must be scanned either optically or mechanically over a sample volume to reconstruct a 3-D image, DDCFM can obtain the depth of a fluorescent emitter without depth scanning. DDCFM comprises two photodetectors, each with a pinhole of different size, in the confocal detection system. Axial information on fluorescent emitters can be measured by the axial response curve through the ratio of intensity signals. DDCFM can rapidly acquire a 3-D fluorescent image from a single two-dimensional scan with less phototoxicity and photobleaching than confocal fluorescence microscopy because no mechanical depth scans are needed. We demonstrated the feasibility of the proposed method by phantom studies.

Three-dimensional imaging of sulfides in silicate rocks at submicron resolution with multiphoton microscopy.

PubMed

Bénard, Antoine; Palle, Sabine; Doucet, Luc Serge; Ionov, Dmitri A

2011-12-01

We report the first application of multiphoton microscopy (MPM) to generate three-dimensional (3D) images of natural minerals (micron-sized sulfides) in thick (∼120 μm) rock sections. First, reflection mode (RM) using confocal laser scanning microscopy (CLSM), combined with differential interference contrast (DIC), was tested on polished sections. Second, two-photon fluorescence (TPF) and second harmonic signal (SHG) images were generated using a femtosecond-laser on the same rock section without impregnation by a fluorescent dye. CSLM results show that the silicate matrix is revealed with DIC and RM, while sulfides can be imaged in 3D at low resolution by RM. Sulfides yield strong autofluorescence from 392 to 715 nm with TPF, while SHG is only produced by the embedding medium. Simultaneous recording of TPF and SHG images enables efficient discrimination between different components of silicate rocks. Image stacks obtained with MPM enable complete reconstruction of the 3D structure of a rock slice and of sulfide morphology at submicron resolution, which has not been previously reported for 3D imaging of minerals. Our work suggests that MPM is a highly efficient tool for 3D studies of microstructures and morphologies of minerals in silicate rocks, which may find other applications in geosciences.

Advances in combined endoscopic fluorescence confocal microscopy and optical coherence tomography

NASA Astrophysics Data System (ADS)

Risi, Matthew D.

Confocal microendoscopy provides real-time high resolution cellular level images via a minimally invasive procedure. Results from an ongoing clinical study to detect ovarian cancer with a novel confocal fluorescent microendoscope are presented. As an imaging modality, confocal fluorescence microendoscopy typically requires exogenous fluorophores, has a relatively limited penetration depth (100 μm), and often employs specialized aperture configurations to achieve real-time imaging in vivo. Two primary research directions designed to overcome these limitations and improve diagnostic capability are presented. Ideal confocal imaging performance is obtained with a scanning point illumination and confocal aperture, but this approach is often unsuitable for real-time, in vivo biomedical imaging. By scanning a slit aperture in one direction, image acquisition speeds are greatly increased, but at the cost of a reduction in image quality. The design, implementation, and experimental verification of a custom multi-point-scanning modification to a slit-scanning multi-spectral confocal microendoscope is presented. This new design improves the axial resolution while maintaining real-time imaging rates. In addition, the multi-point aperture geometry greatly reduces the effects of tissue scatter on imaging performance. Optical coherence tomography (OCT) has seen wide acceptance and FDA approval as a technique for ophthalmic retinal imaging, and has been adapted for endoscopic use. As a minimally invasive imaging technique, it provides morphological characteristics of tissues at a cellular level without requiring the use of exogenous fluorophores. OCT is capable of imaging deeper into biological tissue (˜1-2 mm) than confocal fluorescence microscopy. A theoretical analysis of the use of a fiber-bundle in spectral-domain OCT systems is presented. The fiber-bundle enables a flexible endoscopic design and provides fast, parallelized acquisition of the optical coherence tomography data. However, the multi-mode characteristic of the fibers in the fiber-bundle affects the depth sensitivity of the imaging system. A description of light interference in a multi-mode fiber is presented along with numerical simulations and experimental studies to illustrate the theoretical analysis.

Green synthesis of soya bean sprouts-mediated superparamagnetic Fe 3O 4 nanoparticles

NASA Astrophysics Data System (ADS)

Cai, Yan; Shen, Yuhua; Xie, Anjian; Li, Shikuo; Wang, Xiufang

2010-10-01

Superparamagnetic Fe 3O 4 nanoparticles were first synthesized via soya bean sprouts (SBS) templates under ambient temperature and normal atmosphere. The reaction process was simple, eco-friendly, and convenient to handle. The morphology and crystalline phase of the nanoparticles were determined from scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and X-ray diffraction (XRD) spectra. The effect of SBS template on the formation of Fe 3O 4 nanoparticles was investigated using X-ray photoemission spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR). The results indicate that spherical Fe 3O 4 nanoparticles with an average diameter of 8 nm simultaneously formed on the epidermal surface and the interior stem wall of SBS. The SBS are responsible for size and morphology control during the whole formation of Fe 3O 4 nanoparticles. In addition, the superconducting quantum interference device (SQUID) results indicate the products are superparamagnetic at room temperature, with blocking temperature ( TB) of 150 K and saturation magnetization of 37.1 emu/g.

Sub-wavelength ripples in fused silica after irradiation of the solid/liquid interface with ultrashort laser pulses.

PubMed

Böhme, R; Vass, C; Hopp, B; Zimmer, K

2008-12-10

Laser-induced backside wet etching (LIBWE) is performed using ultrashort 248 nm laser pulses with a pulse duration of 600 fs to obtain sub-wavelength laser-induced periodic surface structures (LIPSS) on the back surface of fused silica which is in contact with a 0.5 mol l(-1) solution of pyrene in toluene. The LIPSS are strictly one-dimensional patterns, oriented parallel to the polarization of the laser radiation, and have a constant period of about 140 nm at all applied laser fluences (0.33-0.84 J cm(-2)) and pulse numbers (50-1000 pulses). The LIPSS amplitude varies due to the inhomogeneous fluence in the laser spot. The LIPSS are examined with scanning electron microscopy (SEM) and atomic force microscopy (AFM). Their power spectral density (PSD) distribution is analysed at a measured area of 10 µm × 10 µm. The good agreement of the measured and calculated LIPSS periods strongly supports a mechanism based on the interference of surface-scattered and incident waves.

One-step construction of a molybdenum disulfide/multi-walled carbon nanotubes/polypyrrole nanocomposite biosensor for the ex-vivo detection of dopamine in mouse brain tissue.

PubMed

Vijayaraj, Kathiresan; Dinakaran, Thirumalai; Lee, Yujeong; Kim, Suhkmann; Kim, Hyung Sik; Lee, Jaewon; Chang, Seung-Cheol

2017-12-09

We developed a new strategy for construction of a biosensor for the neurotransmitter dopamine. The biosensor was constructed by one-step electrochemical deposition of a nanocomposite in aqueous solution at pH 7.0, consisting of molybdenum disulfide, multi-walled carbon nanotubes, and polypyrrole. A series of analytical methods was performed to investigate the surface characteristics and the improved electrocatalytic effect of the nanocomposite, including cyclic voltammetry, electrochemical impedance spectroscopy, field-emission scanning electron microscopy, atomic force microscopy, and Raman spectroscopy. The constructed biosensor showed high sensitivity (1.130 μAμM -1 cm -2 ) with a dynamic linearity range of 25-1000 nM and a detection limit of 10 nM. Additionally, the designed sensor exhibited strong anti-interference ability and satisfactory reproducibility. The practical application of the sensor was manifested for the ex vivo determination of dopamine neurotransmitters using brain tissue samples of a mouse Parkinson's disease model. Copyright © 2017 Elsevier Inc. All rights reserved.

Characterization of Polymer Blends: Optical Microscopy (*Polarized, Interference and Phase Contrast Microscopy*) and Confocal Microscopy

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

Ramanathan, Nathan Muruganathan; Darling, Seth B.

2015-01-01

Chapter 15 surveys the characterization of macro, micro and meso morphologies of polymer blends by optical microscopy. Confocal Microscopy offers the ability to view the three dimensional morphology of polymer blends, popular in characterization of biological systems. Confocal microscopy uses point illumination and a spatial pinhole to eliminate out-of focus light in samples that are thicker than the focal plane.

Cement paste surface roughness analysis using coherence scanning interferometry and confocal microscopy

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

Apedo, K.L., E-mail: apedo@unistra.fr; Munzer, C.; He, H.

2015-02-15

Scanning electron microscopy and scanning probe microscopy have been used for several decades to better understand the microstructure of cementitious materials. Very limited work has been performed to date to study the roughness of cementitious materials by optical microscopy such as coherence scanning interferometry (CSI) and chromatic confocal sensing (CCS). The objective of this paper is to better understand how CSI can be used as a tool to analyze surface roughness and topography of cement pastes. Observations from a series of images acquired using this technique on both polished and unpolished samples are described. The results from CSI are comparedmore » with those from a STIL confocal microscopy technique (SCM). Comparison between both optical techniques demonstrates the ability of CSI to measure both polished and unpolished cement pastes. - Highlights: • Coherence scanning interferometry (CSI) was used to analyze cement paste surfaces. • The results from the CSI were compared with those from a confocal microscopy. • 3D roughness parameters were obtained using the window resizing method. • Polished and unpolished cement pastes were studied.« less

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.

Path-separated electron interferometry in a scanning transmission electron microscope

NASA Astrophysics Data System (ADS)

Yasin, Fehmi S.; Harvey, Tyler R.; Chess, Jordan J.; Pierce, Jordan S.; McMorran, Benjamin J.

2018-05-01

We report a path-separated electron interferometer within a scanning transmission electron microscope. In this setup, we use a nanofabricated grating as an amplitude-division beamsplitter to prepare multiple spatially separated, coherent electron probe beams. We achieve path separations of 30 nm. We pass the  +1 diffraction order probe through amorphous carbon while passing the 0th and  ‑1 orders through vacuum. The probes are then made to interfere via imaging optics, and we observe an interference pattern at the CCD detector with up to 39.7% fringe visibility. We show preliminary experimental results in which the interference pattern was recorded during a 1D scan of the diffracted probes across a test phase object. These results qualitatively agree with a modeled interference predicted by an independent measurement of the specimen thickness. This experimental design can potentially be applied to phase contrast imaging and fundamental physics experiments, such as an exploration of electron wave packet coherence length.

Nanoscaffold matrices for size-controlled, pulsatile transdermal testosterone delivery: nanosize effects on the time dimension

NASA Astrophysics Data System (ADS)

Malik, Ritu; Tondwal, Shailesh; Venkatesh, K. S.; Misra, Amit

2008-10-01

Pulsatile transdermal testosterone (T) has applications in hormone supplementation and male contraception. Pulsatile T delivery was achieved by assembling crystalline and nanoparticulate T in nucleation-inhibiting polymer matrices of controlled porosity. Different interference patterns observed from various polymeric films containing T were due to the various particle sizes of T present in the polymer matrices. Scanning electron microscopy was used to determine the size and shape of T crystals. Skin-adherent films containing T nanoparticles of any size between 10-500 nm could be prepared using pharmaceutically acceptable vinylic polymers. Drug release and skin permeation profiles were studied. The dissolution-diffusion behavior of nanoparticles differed from crystalline and molecular states. Nanosize may thus be used to engineer chronopharmacologically relevant drug delivery.

Electrochemical imaging of cells and tissues

PubMed Central

Lin, Tzu-En; Rapino, Stefania; Girault, Hubert H.

2018-01-01

The technological and experimental progress in electrochemical imaging of biological specimens is discussed with a view on potential applications for skin cancer diagnostics, reproductive medicine and microbial testing. The electrochemical analysis of single cell activity inside cell cultures, 3D cellular aggregates and microtissues is based on the selective detection of electroactive species involved in biological functions. Electrochemical imaging strategies, based on nano/micrometric probes scanning over the sample and sensor array chips, respectively, can be made sensitive and selective without being affected by optical interference as many other microscopy techniques. The recent developments in microfabrication, electronics and cell culturing/tissue engineering have evolved in affordable and fast-sampling electrochemical imaging platforms. We believe that the topics discussed herein demonstrate the applicability of electrochemical imaging devices in many areas related to cellular functions. PMID:29899947

Visualizing electron pockets in cuprate superconductors

NASA Astrophysics Data System (ADS)

Das, Tanmoy; Markiewicz, R. S.; Bansil, A.; Balatsky, A. V.

2012-06-01

Fingerprints of the electron pocket in cuprates have been obtained only in numerous magnetotransport measurements, but its absence in spectroscopic observations poses a long-standing mystery. We develop a theoretical tool to provide ways to detect electron pockets via spectroscopies including scanning tunneling microscopy (STM) spectra, inelastic neutron scattering (INS), and angle-resolved photoemission spectroscopy (ARPES). We show that the quasiparticle-interference (QPI) pattern, measured by STM, shows an additional seven q vectors associated with the scattering on the electron pocket than that on the hole pocket. Furthermore, the Bogolyubov quasiparticle scatterings of the electron pocket lead to a second magnetic resonance mode in the INS spectra at a higher resonance energy. Finally, we reanalyze some STM, INS, and ARPES experimental data of several cuprates which dictates the direct fingerprints of electron pockets in these systems.

Lipids in cheese

USDA-ARS?s Scientific Manuscript database

Lipids are present in cheese at levels above 20 percent and are analyzed by several techniques. Scanning electron microscopy and confocal laser scanning microscopy are used to examine the microstructure, gas chromatography is employed to look at fatty acid composition, and differential scanning cal...

Rotary-scanning optical resolution photoacoustic microscopy

NASA Astrophysics Data System (ADS)

Qi, Weizhi; Xi, Lei

2016-10-01

Optical resolution photoacoustic microscopy (ORPAM) is currently one of the fastest evolving photoacoustic imaging modalities. It has a comparable spatial resolution to pure optical microscopic techniques such as epifluorescence microscopy, confocal microscopy, and two-photon microscopy, but also owns a deeper penetration depth. In this paper, we report a rotary-scanning (RS)-ORPAM that utilizes a galvanometer scanner integrated with objective to achieve rotary laser scanning. A 15 MHz cylindrically focused ultrasonic transducer is mounted onto a motorized rotation stage to follow optical scanning traces synchronously. To minimize the loss of signal to noise ratio, the acoustic focus is precisely adjusted to reach confocal with optical focus. Black tapes and carbon fibers are firstly imaged to evaluate the performance of the system, and then in vivo imaging of vasculature networks inside the ears and brains of mice is demonstrated using this system.

Determining the vibrations between sensor and sample in SQUID microscopy

NASA Astrophysics Data System (ADS)

Schiessl, Daniel; Kirtley, John R.; Paulius, Lisa; Rosenberg, Aaron J.; Palmstrom, Johanna C.; Ullah, Rahim R.; Holland, Connor M.; Fung, Y.-K.-K.; Ketchen, Mark B.; Gibson, Gerald W.; Moler, Kathryn A.

2016-12-01

Vibrations can cause noise in scanning probe microscopies. Relative vibrations between the scanning sensor and the sample are important but can be more difficult to determine than absolute vibrations or vibrations relative to the laboratory. We measure the noise spectral density in a scanning SQUID microscope as a function of position near a localized source of magnetic field and show that we can determine the spectra of all three components of the relative sensor-sample vibrations. This method is a powerful tool for diagnosing vibrational noise in scanning microscopies.

Label-free imaging of the dynamics of cell-to-cell string-like structure bridging in the free-space by low-coherent quantitative phase microscopy

NASA Astrophysics Data System (ADS)

Yamauchi, Toyohiko; Iwai, Hidenao; Yamashita, Yutaka

2013-03-01

We succeeded in utilizing our low-coherent quantitative phase microscopy (LC-QPM) to achieve label-free and three-dimensional imaging of string-like structures bridging the free-space between live cells. In past studies, three dimensional morphology of the string-like structures between cells had been investigated by electron microscopies and fluorescence microscopies and these structures were called "membrane nanotubes" or "tunneling nanotubes." However, use of electron microscopy inevitably kills these cells and fluorescence microscopy is itself a potentially invasive method. To achieve noninvasive imaging of live cells, we applied our LC-QPM which is a reflection-type, phase resolved and full-field interference microscope employing a low-coherent light source. LC-QPM is able to visualize the three-dimensional morphology of live cells without labeling by means of low-coherence interferometry. The lateral (diffraction limit) and longitudinal (coherence-length) spatial resolution of LC-QPM were respectively 0.49 and 0.93 micrometers and the repeatability of the phase measurement was 0.02 radians (1.0 nm). We successfully obtained three-dimensional morphology of live cultured epithelial cells (cell type: HeLa, derived from cervix cancer) and were able to clearly observe the individual string-like structures interconnecting the cells. When we performed volumetric imaging, a 80 micrometer by 60 micrometer by 6.5 micrometer volume was scanned every 5.67 seconds and 70 frames of a three-dimensional movie were recorded for a duration of 397 seconds. Moreover, the optical phase images gave us detailed information about the three-dimensional morphology of the string-like structure at sub-wavelength resolution. We believe that our LC-QPM will be a useful tool for the study of three-dimensional morphology of live cells.

Scanning SQUID microscopy of a ferromanganese crust from the northwestern Pacific: Submillimeter scale magnetostratigraphy as a new tool for age determination and mapping of environmental magnetic parameters

NASA Astrophysics Data System (ADS)

Noguchi, A.; Oda, H.; Yamamoto, Y.; Usui, A.; Sato, M.; Kawai, J.

2017-06-01

Ferromanganese crusts record long-term deep-sea environmental changes. Thus, providing their reliable high-resolution age models is important. We applied a magnetostratigraphic technique to estimate the growth rate of a ferromanganese crust using scanning SQUID (superconducting quantum interference device) microscope (SSM). SSM is designed to map the magnetic field across thin sections with submillimeter resolution. The crust sample was taken from the Takuyo-Daigo Seamount, northwestern Pacific, and recorded a limited supply of dust and sediment from continents. After drift correction and removal of spike noises, the magnetic field values were stacked within the areas of high signal-to-noise ratios. By correlating the obtained profiles with a standard geomagnetic polarity timescale, we obtained an average growth rate of 3.37 ± 0.06 mm/Ma, which is consistent with that obtained by 10Be/9Be geochronology (2.93 ± 0.15 mm/Ma). S ratio mapping shows low values after 3 Ma, associated with voids between columnar structures.

[Research on lateral shearing interferometer for field monitoring of natural gas pipeline leak].

PubMed

Zhang, Xue-Feng; Gao, Yu-Bin

2012-09-01

Aimed at the mechanical scanning spectroscopy equipment with poor anti-interference and anti-jamming ability, which affects the accuracy of its natural gas pipeline leak detection in the wild, a new type of lateral shearing interferometer system was designed. The system uses a beam splitter to get optical path difference by a mechanical scanning part, and it cancel the introduction of external vibration interference through the linkage between the two beam splitterw. The interference intensity of interference fringes produced was calculated, and analysis of a rotating beam splitter corresponds to the angle of the optical path difference function, solving for the maximum angle of the forward rotation and reverse rotation, which is the maximum optical path range. Experiments using the gas tank deflated simulated natural gas pipeline leak process, in the interference conditions, and the test data of the type WQF530 spectrometer and the new type of lateral shearing interferometer system were comparedt. The experimental results show that the relative error of both systems is about 1% in indoor conditions without interference. However, in interference environment, the error of WQF530 type spectrometer becomes larger, more than 10%, but the error of the new type of lateral shearing interferometer system is still below 5%. The detection accuracy of the type WQF530 spectrometer decreased significantly due to the environment. Therefore, the seismic design of the system can effectively offset power deviation and half-width increases of center wavelength caused by external interference, and compared to conventional mechanical scanning interferometer devices the new system is more suitable for field detection.

Hydride vapor phase epitaxy of high structural perfection thick AlN layers on off-axis 6H-SiC

NASA Astrophysics Data System (ADS)

Volkova, Anna; Ivantsov, Vladimir; Leung, Larry

2011-01-01

The employment of more than 10 μm thick AlN epilayers on SiC substrates for AlGaN/GaN high-electron-mobility transistors (HEMTs) substantially raises their performance in high-power energy-efficient amplifiers for 4G wireless mobile stations. In this paper, structural properties and surface morphology of thick AlN epilayers deposited by hydride vapor phase epitaxy (HVPE) on off-axis conductive 6H-SiC substrates are reported. The epilayers were examined in detail by high-resolution X-ray diffraction (XRD), atomic force microscopy (AFM), Nomarski differential interference contrast (DIC), scanning electron microscopy (SEM), and selective wet chemical etching. At optimal substrate preparation and growth conditions, a full width at half-maximum (FWHM) of the XRD rocking curve (RC) for the symmetric (00.2) reflex was very close to that of the substrate (less than 40 arcsec) suggesting low screw dislocation density in the epilayer (˜10 6 cm -2) and small in-plane tilt misorientation. Reciprocal space mapping around asymmetric reflexes and measured lattice parameters indicated a fully relaxed state of the epilayers. The unit-cell-high stepped areas of the epilayers with 0.5 nm root mean square (RMS) roughness over 1×1 μm 2 scan were alternated with step-bunching instabilities up to 350 nm in height. Low warp of the substrates makes them suitable for precise epitaxy of HEMT structures.

Reduced graphene oxide-rose bengal hybrid film for improved ammonia detection with low humidity interference at room temperature

NASA Astrophysics Data System (ADS)

Midya, Anupam; Ghosh, Ruma; Santra, Sumita; Ray, Samit K.; Guha, Prasanta K.

2016-02-01

Development of chemoresistive ammonia sensor that does not suffer with humidity interference is highly desirable for practical environmental monitoring systems. We report enhanced ammonia sensing using chemically reduced graphene oxide (RGO) and rose bengal (RB) nanocomposite fabricated in a very simple and cost effective manner. The RGO-RB nanocomposites were synthesized using three different concentrations (2 mg mL-1, 5 mg mL-1 and 10 mg mL-1) of RB keeping the RGO concentration same. Ammonia and humidity sensing of these three different composites were explored. Interestingly, it was observed that with increasing concentration of RB, the sensitivity of the sensor towards ammonia was increased but the sensitivity towards humidity was decreased. The response of the nanocomposites varied from ˜9-45% against 400-2800 ppm of ammonia whereas intrinsic RGO showed a response of merely 17% against 2800 ppm of ammonia. On the other hand the response of the nanocomposite based sensor was reduced from 18% to 7% against 100% relative humidity. Also, the sensor was found to be selective towards ammonia when tested against other toxic volatile organic compounds. The limit of detection of the RGO-RB based sensor was calculated to be as low as 0.9 ppm. Field emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and UV-vis spectroscopy were carried out for the detailed structural characterizations of the sensing layer. These results are believed to be very useful for the cost effective fabrication of graphene based ammonia sensors which have reduced effects of humidity.

Semiclassical description of photoionization microscopy

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

Bordas, Ch.; Lepine, F.; Nicole, C.

2003-07-01

Recently, experiments have been reported where a geometrical interference pattern was observed when photoelectrons ejected in the threshold photoionization of xenon were detected in a velocity-map imaging apparatus [C. Nicole et al., Phys. Rev. Lett. 88, 133001 (2002)]. This technique, called photoionization microscopy, relies on the existence of interferences between various trajectories by which the electron moves from the atom to the plane of observation. Unlike previous predictions relevant to the hydrogenic case, the structure of the interference pattern evolves smoothly with the excess energy above the saddle point and is only weakly affected by the presence of continuum Starkmore » resonances. In this paper, we describe a semiclassical analysis of this process and present numerical simulations in excellent agreement with the experimental results. It is shown that the background contribution dominates in the observations, as opposed to the behavior expected for hydrogenic systems where the interference pattern is qualitatively different on quasidiscrete Stark resonances.« less

Fluorescence microscopy.

PubMed

Sanderson, Michael J; Smith, Ian; Parker, Ian; Bootman, Martin D

2014-10-01

Fluorescence microscopy is a major tool with which to monitor cell physiology. Although the concepts of fluorescence and its optical separation using filters remain similar, microscope design varies with the aim of increasing image contrast and spatial resolution. The basics of wide-field microscopy are outlined to emphasize the selection, advantages, and correct use of laser scanning confocal microscopy, two-photon microscopy, scanning disk confocal microscopy, total internal reflection, and super-resolution microscopy. In addition, the principles of how these microscopes form images are reviewed to appreciate their capabilities, limitations, and constraints for operation. © 2014 Cold Spring Harbor Laboratory Press.

Fluorescence Microscopy

PubMed Central

Sanderson, Michael J.; Smith, Ian; Parker, Ian; Bootman, Martin D.

2016-01-01

Fluorescence microscopy is a major tool with which to monitor cell physiology. Although the concepts of fluorescence and its optical separation using filters remain similar, microscope design varies with the aim of increasing image contrast and spatial resolution. The basics of wide-field microscopy are outlined to emphasize the selection, advantages, and correct use of laser scanning confocal microscopy, two-photon microscopy, scanning disk confocal microscopy, total internal reflection, and super-resolution microscopy. In addition, the principles of how these microscopes form images are reviewed to appreciate their capabilities, limitations, and constraints for operation. PMID:25275114

Scanning superlens microscopy for non-invasive large field-of-view visible light nanoscale imaging

NASA Astrophysics Data System (ADS)

Wang, Feifei; Liu, Lianqing; Yu, Haibo; Wen, Yangdong; Yu, Peng; Liu, Zhu; Wang, Yuechao; Li, Wen Jung

2016-12-01

Nanoscale correlation of structural information acquisition with specific-molecule identification provides new insight for studying rare subcellular events. To achieve this correlation, scanning electron microscopy has been combined with super-resolution fluorescent microscopy, despite its destructivity when acquiring biological structure information. Here we propose time-efficient non-invasive microsphere-based scanning superlens microscopy that enables the large-area observation of live-cell morphology or sub-membrane structures with sub-diffraction-limited resolution and is demonstrated by observing biological and non-biological objects. This microscopy operates in both non-invasive and contact modes with ~200 times the acquisition efficiency of atomic force microscopy, which is achieved by replacing the point of an atomic force microscope tip with an imaging area of microspheres and stitching the areas recorded during scanning, enabling sub-diffraction-limited resolution. Our method marks a possible path to non-invasive cell imaging and simultaneous tracking of specific molecules with nanoscale resolution, facilitating the study of subcellular events over a total cell period.

Interferometric Shack-Hartmann wavefront sensor with an array of four-hole apertures.

PubMed

López, David; Ríos, Susana

2010-04-20

A modified Hartmann test based on the interference produced by a four-hole mask can be used to measure an unknown wavefront. To scan the wavefront, the interference pattern is measured for different positions of the mask. The position of the central fringe of the diamond-shaped interference pattern gives a measure of the local wavefront slopes. Using a set of four-hole apertures located behind an array of lenslets in such a way that each four-hole window is inside one lenslet area, a set of four-hole interference patterns can be obtained in the back focal plane of the lenslets without having to scan the wavefront. The central fringe area of each interference pattern is narrower than the area of the central maximum of the diffraction pattern of the lenslet, increasing the accuracy in the estimate of the lobe position as compared with the Shack-Hartmann wavefront sensor.

Spectral interferometric microscopy reveals absorption by individual optical nanoantennas from extinction phase

PubMed Central

Gennaro, Sylvain D.; Sonnefraud, Yannick; Verellen, Niels; Van Dorpe, Pol; Moshchalkov, Victor V.; Maier, Stefan A.; Oulton, Rupert F.

2014-01-01

Optical antennas transform light from freely propagating waves into highly localized excitations that interact strongly with matter. Unlike their radio frequency counterparts, optical antennas are nanoscopic and high frequency, making amplitude and phase measurements challenging and leaving some information hidden. Here we report a novel spectral interferometric microscopy technique to expose the amplitude and phase response of individual optical antennas across an octave of the visible to near-infrared spectrum. Although it is a far-field technique, we show that knowledge of the extinction phase allows quantitative estimation of nanoantenna absorption, which is a near-field quantity. To verify our method we characterize gold ring-disk dimers exhibiting Fano interference. Our results reveal that Fano interference only cancels a bright mode’s scattering, leaving residual extinction dominated by absorption. Spectral interference microscopy has the potential for real-time and single-shot phase and amplitude investigations of isolated quantum and classical antennas with applications across the physical and life sciences. PMID:24781663

Microscanners for optical endomicroscopic applications

NASA Astrophysics Data System (ADS)

Hwang, Kyungmin; Seo, Yeong-Hyeon; Jeong, Ki-Hun

2017-12-01

MEMS laser scanning enables the miniaturization of endoscopic catheters for advanced endomicroscopy such as confocal microscopy, multiphoton microscopy, optical coherence tomography, and many other laser scanning microscopy. These advanced biomedical imaging modalities open a great potential for in vivo optical biopsy without surgical excision. They have huge capabilities for detecting on-demand early stage cancer with non-invasiveness. In this article, the scanning arrangement, trajectory, and actuation mechanism of endoscopic microscanners and their endomicroscopic applications will be overviewed.

Label-free, multi-scale imaging of ex-vivo mouse brain using spatial light interference microscopy

NASA Astrophysics Data System (ADS)

Min, Eunjung; Kandel, Mikhail E.; Ko, Chemyong J.; Popescu, Gabriel; Jung, Woonggyu; Best-Popescu, Catherine

2016-12-01

Brain connectivity spans over broad spatial scales, from nanometers to centimeters. In order to understand the brain at multi-scale, the neural network in wide-field has been visualized in detail by taking advantage of light microscopy. However, the process of staining or addition of fluorescent tags is commonly required, and the image contrast is insufficient for delineation of cytoarchitecture. To overcome this barrier, we use spatial light interference microscopy to investigate brain structure with high-resolution, sub-nanometer pathlength sensitivity without the use of exogenous contrast agents. Combining wide-field imaging and a mosaic algorithm developed in-house, we show the detailed architecture of cells and myelin, within coronal olfactory bulb and cortical sections, and from sagittal sections of the hippocampus and cerebellum. Our technique is well suited to identify laminar characteristics of fiber tract orientation within white matter, e.g. the corpus callosum. To further improve the macro-scale contrast of anatomical structures, and to better differentiate axons and dendrites from cell bodies, we mapped the tissue in terms of its scattering property. Based on our results, we anticipate that spatial light interference microscopy can potentially provide multiscale and multicontrast perspectives of gross and microscopic brain anatomy.

Fluorescent Imaging of Single Nanoparticles and Viruses on a Smart Phone

PubMed Central

Wei, Qingshan; Qi, Hangfei; Luo, Wei; Tseng, Derek; Ki, So Jung; Wan, Zhe; Göröcs, Zoltán; Bentolila, Laurent A.; Wu, Ting-Ting; Sun, Ren; Ozcan, Aydogan

2014-01-01

Optical imaging of nanoscale objects, whether it is based on scattering or fluorescence, is a challenging task due to reduced detection signal-to-noise ratio and contrast at subwavelength dimensions. Here, we report a field-portable fluorescence microscopy platform installed on a smart phone for imaging of individual nanoparticles as well as viruses using a lightweight and compact opto-mechanical attachment to the existing camera module of the cell phone. This hand-held fluorescent imaging device utilizes (i) a compact 450 nm laser diode that creates oblique excitation on the sample plane with an incidence angle of ~75°, (ii) a long-pass thin-film interference filter to reject the scattered excitation light, (iii) an external lens creating 2× optical magnification, and (iv) a translation stage for focus adjustment. We tested the imaging performance of this smart-phone-enabled microscopy platform by detecting isolated 100 nm fluorescent particles as well as individual human cytomegaloviruses that are fluorescently labeled. The size of each detected nano-object on the cell phone platform was validated using scanning electron microscopy images of the same samples. This field-portable fluorescence microscopy attachment to the cell phone, weighing only ~186 g, could be used for specific and sensitive imaging of subwavelength objects including various bacteria and viruses and, therefore, could provide a valuable platform for the practice of nanotechnology in field settings and for conducting viral load measurements and other biomedical tests even in remote and resource-limited environments. PMID:24016065

Fabrication of [001]-oriented tungsten tips for high resolution scanning tunneling microscopy

PubMed Central

Chaika, A. N.; Orlova, N. N.; Semenov, V. N.; Postnova, E. Yu.; Krasnikov, S. A.; Lazarev, M. G.; Chekmazov, S. V.; Aristov, V. Yu.; Glebovsky, V. G.; Bozhko, S. I.; Shvets, I. V.

2014-01-01

The structure of the [001]-oriented single crystalline tungsten probes sharpened in ultra-high vacuum using electron beam heating and ion sputtering has been studied using scanning and transmission electron microscopy. The electron microscopy data prove reproducible fabrication of the single-apex tips with nanoscale pyramids grained by the {011} planes at the apexes. These sharp, [001]-oriented tungsten tips have been successfully utilized in high resolution scanning tunneling microscopy imaging of HOPG(0001), SiC(001) and graphene/SiC(001) surfaces. The electron microscopy characterization performed before and after the high resolution STM experiments provides direct correlation between the tip structure and picoscale spatial resolution achieved in the experiments. PMID:24434734

An Improved Fungal Mounting Technique for Nomarski Microscopy.

ERIC Educational Resources Information Center

Fairclough, Andrew; And Others

1985-01-01

Conventional sellotape techniques for fungal mounting produce interference patterns when using Normarsky microscopy. A technique is described which overcomes this problem and produces a permanent mount with a completely clear background. (Author/JN)

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

PubMed

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

2017-01-01

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

Use of CdS quantum dot-functionalized cellulose nanocrystal films for anti-counterfeiting applications

NASA Astrophysics Data System (ADS)

Chen, L.; Lai, C.; Marchewka, R.; Berry, R. M.; Tam, K. C.

2016-07-01

Structural colors and photoluminescence have been widely used for anti-counterfeiting and security applications. We report for the first time the use of CdS quantum dot (QD)-functionalized cellulose nanocrystals (CNCs) as building blocks to fabricate nanothin films via layer-by-layer (LBL) self-assembly for anti-counterfeiting applications. Both negatively- and positively-charged CNC/QD nanohybrids with a high colloidal stability and a narrow particle size distribution were prepared. The controllable LBL coating process was characterized by scanning electron microscopy and ellipsometry. The rigid structure of CNCs leads to nanoporous structured films on poly(ethylene terephthalate) (PET) substrates with high transmittance (above 70%) over the entire range of visible light and also resulted in increased hydrophilicity (contact angles of ~40 degrees). Nanothin films on PET substrates showed good flexibility and enhanced stability in both water and ethanol. The modified PET films with structural colors from thin-film interference and photoluminescence from QDs can be used in anti-counterfeiting applications.Structural colors and photoluminescence have been widely used for anti-counterfeiting and security applications. We report for the first time the use of CdS quantum dot (QD)-functionalized cellulose nanocrystals (CNCs) as building blocks to fabricate nanothin films via layer-by-layer (LBL) self-assembly for anti-counterfeiting applications. Both negatively- and positively-charged CNC/QD nanohybrids with a high colloidal stability and a narrow particle size distribution were prepared. The controllable LBL coating process was characterized by scanning electron microscopy and ellipsometry. The rigid structure of CNCs leads to nanoporous structured films on poly(ethylene terephthalate) (PET) substrates with high transmittance (above 70%) over the entire range of visible light and also resulted in increased hydrophilicity (contact angles of ~40 degrees). Nanothin films on PET substrates showed good flexibility and enhanced stability in both water and ethanol. The modified PET films with structural colors from thin-film interference and photoluminescence from QDs can be used in anti-counterfeiting applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03039d

Software electron counting for low-dose scanning transmission electron microscopy.

PubMed

Mittelberger, Andreas; Kramberger, Christian; Meyer, Jannik C

2018-05-01

The performance of the detector is of key importance for low-dose imaging in transmission electron microscopy, and counting every single electron can be considered as the ultimate goal. In scanning transmission electron microscopy, low-dose imaging can be realized by very fast scanning, however, this also introduces artifacts and a loss of resolution in the scan direction. We have developed a software approach to correct for artifacts introduced by fast scans, making use of a scintillator and photomultiplier response that extends over several pixels. The parameters for this correction can be directly extracted from the raw image. Finally, the images can be converted into electron counts. This approach enables low-dose imaging in the scanning transmission electron microscope via high scan speeds while retaining the image quality of artifact-free slower scans. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Scanning ultrafast electron microscopy.

PubMed

Yang, Ding-Shyue; Mohammed, Omar F; Zewail, Ahmed H

2010-08-24

Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for which the pulse contains at most one or a few electrons, thus achieving imaging without the space-charge effect between electrons, and still in ten(s) of seconds. For imaging, the secondary electrons from surface structures are detected, as demonstrated here for material surfaces and biological specimens. By recording backscattered electrons, diffraction patterns from single crystals were also obtained. Scanning pulsed-electron microscopy with the acquired spatiotemporal resolutions, and its efficient heat-dissipation feature, is now poised to provide in situ 4D imaging and with environmental capability.

Scanning fluorescent microscopy is an alternative for quantitative fluorescent cell analysis.

PubMed

Varga, Viktor Sebestyén; Bocsi, József; Sipos, Ferenc; Csendes, Gábor; Tulassay, Zsolt; Molnár, Béla

2004-07-01

Fluorescent measurements on cells are performed today with FCM and laser scanning cytometry. The scientific community dealing with quantitative cell analysis would benefit from the development of a new digital multichannel and virtual microscopy based scanning fluorescent microscopy technology and from its evaluation on routine standardized fluorescent beads and clinical specimens. We applied a commercial motorized fluorescent microscope system. The scanning was done at 20 x (0.5 NA) magnification, on three channels (Rhodamine, FITC, Hoechst). The SFM (scanning fluorescent microscopy) software included the following features: scanning area, exposure time, and channel definition, autofocused scanning, densitometric and morphometric cellular feature determination, gating on scatterplots and frequency histograms, and preparation of galleries of the gated cells. For the calibration and standardization Immuno-Brite beads were used. With application of shading compensation, the CV of fluorescence of the beads decreased from 24.3% to 3.9%. Standard JPEG image compression until 1:150 resulted in no significant change. The change of focus influenced the CV significantly only after +/-5 microm error. SFM is a valuable method for the evaluation of fluorescently labeled cells. Copyright 2004 Wiley-Liss, Inc.

AC conductivity, magnetic and shielding effectiveness studies on polyaniline embedded Co0.5Mn0.5Fe2O4 nanoparticles for electromagnetic interference suppression

NASA Astrophysics Data System (ADS)

Gurusiddesh, M.; Madhu, B. J.; Shankaramurthy, G. J.

2018-05-01

Electrically conducting Polyaniline (PANI)/Co0.5Mn0.5Fe2O4 nanocomposites are synthesized by in situ polymerization of aniline monomer in the presence of Co0.5Mn0.5Fe2O4 nanoparticles. Structural studies on the synthesized samples have been carried out using X-ray diffraction technique, Field emission scanning electron microscopy and Energy dispersive X-ray spectroscopy. Frequency dependent ac conductivity studies on the prepared samples revealed that conductivity of the composite is high compared to Co0.5Mn0.5Fe2O4 nanoparticles. Further, both the samples exhibited hysteresis behavior under the applied magnetic field. Electromagnetic interference (EMI) shielding effectiveness of both the samples decreases with increase in the applied frequency in the studied frequency range. Maximum shielding effectiveness (SE) of 31.49 dB and 62.84 dB were obtained for Co0.5Mn0.5Fe2O4 nanoparticles and PANI/Co0.5Mn0.5Fe2O4 nanocomposites respectively in the studied frequency range. Observed higher EMI shielding in the composites was attributed to its high electrical conductivity.

Annealing-Induced Bi Bilayer on Bi2Te3 Investigated via Quasi-Particle-Interference Mapping.

PubMed

Schouteden, Koen; Govaerts, Kirsten; Debehets, Jolien; Thupakula, Umamahesh; Chen, Taishi; Li, Zhe; Netsou, Asteriona; Song, Fengqi; Lamoen, Dirk; Van Haesendonck, Chris; Partoens, Bart; Park, Kyungwha

2016-09-27

Topological insulators (TIs) are renowned for their exotic topological surface states (TSSs) that reside in the top atomic layers, and hence, detailed knowledge of the surface top atomic layers is of utmost importance. Here we present the remarkable morphology changes of Bi2Te3 surfaces, which have been freshly cleaved in air, upon subsequent systematic annealing in ultrahigh vacuum and the resulting effects on the local and area-averaging electronic properties of the surface states, which are investigated by combining scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and Auger electron spectroscopy (AES) experiments with density functional theory (DFT) calculations. Our findings demonstrate that the annealing induces the formation of a Bi bilayer atop the Bi2Te3 surface. The adlayer results in n-type doping, and the atomic defects act as scattering centers of the TSS electrons. We also investigated the annealing-induced Bi bilayer surface on Bi2Te3 via voltage-dependent quasi-particle-interference (QPI) mapping of the surface local density of states and via comparison with the calculated constant-energy contours and QPI patterns. We observed closed hexagonal patterns in the Fourier transform of real-space QPI maps with secondary outer spikes. DFT calculations attribute these complex QPI patterns to the appearance of a "second" cone due to the surface charge transfer between the Bi bilayer and the Bi2Te3. Annealing in ultrahigh vacuum offers a facile route for tuning of the topological properties and may yield similar results for other topological materials.

Correcting nonlinear drift distortion of scanning probe and scanning transmission electron microscopies from image pairs with orthogonal scan directions

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

Ophus, Colin; Ciston, Jim; Nelson, Chris T.

Unwanted motion of the probe with respect to the sample is a ubiquitous problem in scanning probe and scanning transmission electron microscopies, causing both linear and nonlinear artifacts in experimental images. We have designed a procedure to correct these artifacts by using orthogonal scan pairs to align each measurement line-by-line along the slow scan direction, by fitting contrast variation along the lines. We demonstrate the accuracy of our algorithm on both synthetic and experimental data and provide an implementation of our method.

Correcting nonlinear drift distortion of scanning probe and scanning transmission electron microscopies from image pairs with orthogonal scan directions

DOE PAGES

Ophus, Colin; Ciston, Jim; Nelson, Chris T.

2015-12-10

Unwanted motion of the probe with respect to the sample is a ubiquitous problem in scanning probe and scanning transmission electron microscopies, causing both linear and nonlinear artifacts in experimental images. We have designed a procedure to correct these artifacts by using orthogonal scan pairs to align each measurement line-by-line along the slow scan direction, by fitting contrast variation along the lines. We demonstrate the accuracy of our algorithm on both synthetic and experimental data and provide an implementation of our method.

Simultaneous X-ray fluorescence and scanning X-ray diffraction microscopy at the Australian Synchrotron XFM beamline

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

Jones, Michael W. M.; Phillips, Nicholas W.; van Riessen, Grant A.

2016-08-11

Owing to its extreme sensitivity, quantitative mapping of elemental distributionsviaX-ray fluorescence microscopy (XFM) has become a key microanalytical technique. The recent realisation of scanning X-ray diffraction microscopy (SXDM) meanwhile provides an avenue for quantitative super-resolved ultra-structural visualization. The similarity of their experimental geometries indicates excellent prospects for simultaneous acquisition. Here, in both step- and fly-scanning modes, robust, simultaneous XFM-SXDM is demonstrated.

Combined frequency modulated atomic force microscopy and scanning tunneling microscopy detection for multi-tip scanning probe microscopy applications

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

Morawski, Ireneusz; Institute of Experimental Physics, University of Wrocław, pl. M. Borna 9, 50-204 Wrocław; Spiegelberg, Richard

A method which allows scanning tunneling microscopy (STM) tip biasing independent of the sample bias during frequency modulated atomic force microscopy (AFM) operation is presented. The AFM sensor is supplied by an electronic circuit combining both a frequency shift signal and a tunneling current signal by means of an inductive coupling. This solution enables a control of the tip potential independent of the sample potential. Individual tip biasing is specifically important in order to implement multi-tip STM/AFM applications. An extensional quartz sensor (needle sensor) with a conductive tip is applied to record simultaneously topography and conductivity of the sample. Themore » high resonance frequency of the needle sensor (1 MHz) allows scanning of a large area of the surface being investigated in a reasonably short time. A recipe for the amplitude calibration which is based only on the frequency shift signal and does not require the tip being in contact is presented. Additionally, we show spectral measurements of the mechanical vibration noise of the scanning system used in the investigations.« less

Evaluation of conjunctival inflammatory status by confocal scanning laser microscopy and conjunctival brush cytology in patients with atopic keratoconjunctivitis (AKC)

PubMed Central

Wakamatsu, Tais Hitomi; Okada, Naoko; Kojima, Takashi; Matsumoto, Yukihiro; Ibrahim, Osama M.A.; Adan, Enrique Sato; Fukagawa, Kazumi; Katakami, Chikako; Tsubota, Kazuo; Shimazaki, Jun; Fujishima, Hiroshi

2009-01-01

Purpose To elucidate the status of the conjunctival inflammation in atopic keratoconjunctivitis (AKC) using laser scanning confocal microscopy and compare the relevant findings with conjunctival brush cytology in a prospective controlled study. Methods Twenty eyes from 20 AKC patients as well as 16 eyes from 16 age and sex matched normal subjects were studied. The subjects underwent tear film break-up time (BUT), fluorescein and Rose Bengal staining of the ocular surface, conjunctival confocal microscopy, Schirmer test, and brush cytology. Brush cytology specimens and in vivo confocal microscopy scans underwent evaluation for inflammatory cell densities. Results Brush cytology specimens and in vivo confocal microscopy scans from AKC patients revealed significantly higher numbers of inflammatory cells (p<0.05). Conjunctival inflammatory cell density showed a negative correlation with tear stability and a positive correlation with vital staining scores and conjunctival injection grades. The extent of conjunctival inflammation assessed by in vivo confocal microscopy showed a strong positive linear correlation with the inflammation status evaluated by brush cytology. The corneal inflammatory cell density assessed by in vivo confocal microscopy showed a significant negative correlation with tear stability and a positive linear correlation with corneal fluorescein staining. Conclusions Confocal scanning laser microscopy is an efficient, noninvasive, and a promising tool for the quantitative assessment of conjunctival inflammation, a parameter of this new technology which correlated well with subjective and objective ocular surface clinical findings. PMID:19693288

Unraveling Cell Processes: Interference Imaging Interwoven with Data Analysis

PubMed Central

Brazhe, A. R.; Pavlov, A. N.; Erokhova, L. A.; Yusipovich, A. I.; Maksimov, G. V.; Mosekilde, E.; Sosnovtseva, O. V.

2006-01-01

The paper presents results on the application of interference microscopy and wavelet-analysis for cell visualization and studies of cell dynamics. We demonstrate that interference imaging of erythrocytes can reveal reorganization of the cytoskeleton and inhomogenity in the distribution of hemoglobin, and that interference imaging of neurons can show intracellular compartmentalization and submembrane structures. We investigate temporal and spatial variations of the refractive index for different cell types: isolated neurons, mast cells and erythrocytes. We show that the refractive dynamical properties differ from cell type to cell type and depend on the cellular compartment. Our results suggest that low frequency variations (0.1–0.6 Hz) result from plasma membrane processes and that higher frequency variations (20–26 Hz) are related to the movement of vesicles. Using double-wavelet analysis, we study the modulation of the 1 Hz rhythm in neurons and reveal its changes under depolarization and hyperpolarization of the plasma membrane. We conclude that interference microscopy combined with wavelet analysis is a useful technique for non-invasive cell studies, cell visualization, and investigation of plasma membrane properties. PMID:19669463

Helium ion microscopy and ultra-high-resolution scanning electron microscopy analysis of membrane-extracted cells reveals novel characteristics of the cytoskeleton of Giardia intestinalis.

PubMed

Gadelha, Ana Paula Rocha; Benchimol, Marlene; de Souza, Wanderley

2015-06-01

Giardia intestinalis presents a complex microtubular cytoskeleton formed by specialized structures, such as the adhesive disk, four pairs of flagella, the funis and the median body. The ultrastructural organization of the Giardia cytoskeleton has been analyzed using different microscopic techniques, including high-resolution scanning electron microscopy. Recent advances in scanning microscopy technology have opened a new venue for the characterization of cellular structures and include scanning probe microscopy techniques such as ultra-high-resolution scanning electron microscopy (UHRSEM) and helium ion microscopy (HIM). Here, we studied the organization of the cytoskeleton of G. intestinalis trophozoites using UHRSEM and HIM in membrane-extracted cells. The results revealed a number of new cytoskeletal elements associated with the lateral crest and the dorsal surface of the parasite. The fine structure of the banded collar was also observed. The marginal plates were seen linked to a network of filaments, which were continuous with filaments parallel to the main cell axis. Cytoplasmic filaments that supported the internal structures were seen by the first time. Using anti-actin antibody, we observed a labeling in these filamentous structures. Taken together, these data revealed new surface characteristics of the cytoskeleton of G. intestinalis and may contribute to an improved understanding of the structural organization of trophozoites. Copyright © 2015 Elsevier Inc. All rights reserved.

Functional Scanning Probe Imaging of Nanostructured Solar Energy Materials.

PubMed

Giridharagopal, Rajiv; Cox, Phillip A; Ginger, David S

2016-09-20

From hybrid perovskites to semiconducting polymer/fullerene blends for organic photovoltaics, many new materials being explored for energy harvesting and storage exhibit performance characteristics that depend sensitively on their nanoscale morphology. At the same time, rapid advances in the capability and accessibility of scanning probe microscopy methods over the past decade have made it possible to study processing/structure/function relationships ranging from photocurrent collection to photocarrier lifetimes with resolutions on the scale of tens of nanometers or better. Importantly, such scanning probe methods offer the potential to combine measurements of local structure with local function, and they can be implemented to study materials in situ or devices in operando to better understand how materials evolve in time in response to an external stimulus or environmental perturbation. This Account highlights recent advances in the development and application of scanning probe microscopy methods that can help address such questions while filling key gaps between the capabilities of conventional electron microscopy and newer super-resolution optical methods. Focusing on semiconductor materials for solar energy applications, we highlight a range of electrical and optoelectronic scanning probe microscopy methods that exploit the local dynamics of an atomic force microscope tip to probe key properties of the solar cell material or device structure. We discuss how it is possible to extract relevant device properties using noncontact scanning probe methods as well as how these properties guide materials development. Specifically, we discuss intensity-modulated scanning Kelvin probe microscopy (IM-SKPM), time-resolved electrostatic force microscopy (trEFM), frequency-modulated electrostatic force microscopy (FM-EFM), and cantilever ringdown imaging. We explain these developments in the context of classic atomic force microscopy (AFM) methods that exploit the physics of cantilever motion and photocarrier generation to provide robust, nanoscale measurements of materials physics that are correlated with device operation. We predict that the multidimensional data sets made possible by these types of methods will become increasingly important as advances in data science expand capabilities and opportunities for image correlation and discovery.

Fast and reliable method of conductive carbon nanotube-probe fabrication for scanning probe microscopy

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

Dremov, Vyacheslav, E-mail: dremov@issp.ac.ru; Fedorov, Pavel; Grebenko, Artem

2015-05-15

We demonstrate the procedure of scanning probe microscopy (SPM) conductive probe fabrication with a single multi-walled carbon nanotube (MWNT) on a silicon cantilever pyramid. The nanotube bundle reliably attached to the metal-covered pyramid is formed using dielectrophoresis technique from the MWNT suspension. It is shown that the dimpled aluminum sample can be used both for shortening/modification of the nanotube bundle by applying pulse voltage between the probe and the sample and for controlling the probe shape via atomic force microscopy imaging the sample. Carbon nanotube attached to cantilever covered with noble metal is suitable for SPM imaging in such modulationmore » regimes as capacitance contrast microscopy, Kelvin probe microscopy, and scanning gate microscopy. The majority of such probes are conductive with conductivity not degrading within hours of SPM imaging.« less

Theory for measurements of penetration depth in magnetic superconductors by magnetic force microscopy and scanning SQUID microscopy

NASA Astrophysics Data System (ADS)

Lin, Shi-Zeng; Bulaevskii, Lev N.

2012-07-01

The working principle of magnetic force microscopy and scanning SQUID microscopy is introducing a magnetic source near a superconductor and measuring the magnetic field distribution near the superconductor, from which one can obtain the penetration depth. We investigate the magnetic field distribution near the surface of a magnetic superconductor when a magnetic source is placed close to the superconductor, which can be used to extract both the penetration depth λL and magnetic susceptibility χ by magnetic force microscopy or scanning SQUID microscopy. When the magnetic moments are parallel to the surface, one extracts λL/1-4πχ. When the moments are perpendicular to the surface, one obtains λL. By changing the orientation of the crystal, one thus is able to extract both χ and λL.

Performance of a three-dimensional-printed microscanner in a laser scanning microscopy application

NASA Astrophysics Data System (ADS)

Oyman, Hilmi Artun; Gokdel, Yigit Daghan; Ferhanoglu, Onur; Yalcinkaya, Arda Deniz

2018-04-01

A magnetically actuated microscanner is used in a laser scanning microscopy application. Stress distribution along the circular-profiled flexure is compared with a rectangular counterpart in finite-element environment. Magnetic actuation mechanism of the scanning unit is explained in detail. Moreover, reliability of the scanner is tested for 3×106 cycle. The scanning device is designed to meet a confocal microscopy application providing 100 μm×100 μm field of view and <3-μm lateral resolution. The resonance frequencies of the device were analytically modeled, where we obtained 130- and 268-Hz resonance values for the out-of-plane and torsion modes, respectively. The scanning device provided an optical scan angle about 2.5 deg for 170-mA drive current, enabling the desired field of view for our custom built confocal microscope setup. Finally, imaging experiments were conducted on a resolution target, showcasing the desired scan area and resolution.

Full information acquisition in scanning probe microscopy and spectroscopy

DOEpatents

Jesse, Stephen; Belianinov, Alex; Kalinin, Sergei V.; Somnath, Suhas

2017-04-04

Apparatus and methods are described for scanning probe microscopy and spectroscopy based on acquisition of full probe response. The full probe response contains valuable information about the probe-sample interaction that is lost in traditional scanning probe microscopy and spectroscopy methods. The full probe response is analyzed post data acquisition using fast Fourier transform and adaptive filtering, as well as multivariate analysis. The full response data is further compressed to retain only statistically significant components before being permanently stored.

Cell Membrane Tracking in Living Brain Tissue Using Differential Interference Contrast Microscopy.

PubMed

Lee, John; Kolb, Ilya; Forest, Craig R; Rozell, Christopher J

2018-04-01

Differential interference contrast (DIC) microscopy is widely used for observing unstained biological samples that are otherwise optically transparent. Combining this optical technique with machine vision could enable the automation of many life science experiments; however, identifying relevant features under DIC is challenging. In particular, precise tracking of cell boundaries in a thick ( ) slice of tissue has not previously been accomplished. We present a novel deconvolution algorithm that achieves the state-of-the-art performance at identifying and tracking these membrane locations. Our proposed algorithm is formulated as a regularized least squares optimization that incorporates a filtering mechanism to handle organic tissue interference and a robust edge-sparsity regularizer that integrates dynamic edge tracking capabilities. As a secondary contribution, this paper also describes new community infrastructure in the form of a MATLAB toolbox for accurately simulating DIC microscopy images of in vitro brain slices. Building on existing DIC optics modeling, our simulation framework additionally contributes an accurate representation of interference from organic tissue, neuronal cell-shapes, and tissue motion due to the action of the pipette. This simulator allows us to better understand the image statistics (to improve algorithms), as well as quantitatively test cell segmentation and tracking algorithms in scenarios, where ground truth data is fully known.

Comparative study viruses with computer-aided phase microscope AIRYSCAN

NASA Astrophysics Data System (ADS)

Tychinsky, Vladimir P.; Koufal, Georgy E.; Perevedentseva, Elena V.; Vyshenskaia, Tatiana V.

1996-12-01

Traditionally viruses are studied with scanning electron microscopy (SEM) after complicated procedure of sample preparation without the possibility to study it under natural conditions. We obtained images of viruses (Vaccinia virus, Rotavirus) and rickettsias (Rickettsia provazekii, Coxiella burnetti) in native state with computer-aided phase microscope airyscan -- the interference microscope of Linnik layout with phase modulation of the reference wave with dissector image tube as coordinate-sensitive photodetector and computer processing of phase image. A light source was the He-Ne laser. The main result is coincidence of dimensions and shape of phase images with available information concerning their morphology obtained with SEM and other methods. The fine structure of surface and nuclei is observed. This method may be applied for virus recognition and express identification, investigation of virus structure and the analysis of cell-virus interaction.

Identification of novel compositions of ferromagnetic shape-memory alloys using composition spreads.

PubMed

Takeuchi, I; Famodu, O O; Read, J C; Aronova, M A; Chang, K-S; Craciunescu, C; Lofland, S E; Wuttig, M; Wellstood, F C; Knauss, L; Orozco, A

2003-03-01

Exploration of new ferroic (ferroelectric, ferromagnetic or ferroelastic) materials continues to be a central theme in condensed matter physics and to drive advances in key areas of technology. Here, using thin-film composition spreads, we have mapped the functional phase diagram of the Ni-Mn-Ga system whose Heusler composition Ni(2)MnGa is a well known ferromagnetic shape-memory alloy. A characterization technique that allows detection of martensitic transitions by visual inspection was combined with quantitative magnetization mapping using scanning SQUID (superconducting quantum interference device) microscopy. We find that a large, previously unexplored region outside the Heusler composition contains reversible martensites that are also ferromagnetic. A clear relationship between magnetization and the martensitic transition temperature is observed, revealing a strong thermodynamical coupling between magnetism and martensitic instability across a large fraction of the phase diagram.

Photothermal imaging scanning microscopy

DOEpatents

Chinn, Diane [Pleasanton, CA; Stolz, Christopher J [Lathrop, CA; Wu, Zhouling [Pleasanton, CA; Huber, Robert [Discovery Bay, CA; Weinzapfel, Carolyn [Tracy, CA

2006-07-11

Photothermal Imaging Scanning Microscopy produces a rapid, thermal-based, non-destructive characterization apparatus. Also, a photothermal characterization method of surface and subsurface features includes micron and nanoscale spatial resolution of meter-sized optical materials.

Sensitive and selective determination of gallic acid in green tea samples based on an electrochemical platform of poly(melamine) film.

PubMed

Su, Ya-Ling; Cheng, Shu-Hua

2015-12-11

In this work, an electrochemical sensor coupled with an effective flow-injection amperometry (FIA) system is developed, targeting the determination of gallic acid (GA) in a mild neutral condition, in contrast to the existing electrochemical methods. The sensor is based on a thin electroactive poly(melamine) film immobilized on a pre-anodized screen-printed carbon electrode (SPCE*/PME). The characteristics of the sensing surface are well-characterized by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and surface water contact angle experiments. The proposed assay exhibits a wide linear response to GA in both pH 3 and pH 7.0 phosphate buffer solutions (PBS) under the optimized flow-injection amperometry. The detection limit (S/N = 3) is 0.076 μM and 0.21 μM in the pH 3 and pH 7 solutions, respectively. A relative standard deviation (RSD) of 3.9% is obtained for 57 successive measurements of 50 μM GA in pH 7 solutions. Interference studies indicate that some inorganic salts, catechol, caffeine and ascorbic acid do not interfere with the GA assay. The interference effects from some orthodiphenolic compounds are also investigated. The proposed method and a conventional Folin-Ciocalteu method are applied to detect GA in green tea samples using the standard addition method, and satisfactory spiked recoveries are obtained. Copyright © 2015 Elsevier B.V. All rights reserved.

Phase resolved and coherence gated en face reflection imaging of multilayered embryonal carcinoma cells

NASA Astrophysics Data System (ADS)

Yamauchi, Toyohiko; Fukami, Tadashi; Iwai, Hidenao; Yamashita, Yutaka

2012-03-01

Embryonal carcinoma (EC) cells, which are cell lines derived from teratocarcinomas, have characteristics in common with stem cells and differentiate into many kinds of functional cells. Similar to embryonic stem (ES) cells, undifferentiated EC cells form multi-layered spheroids. In order to visualize the three-dimensional structure of multilayered EC cells without labeling, we employed full-field interference microscopy with the aid of a low-coherence quantitative phase microscope, which is a reflection-type interference microscope employing the digital holographic technique with a low-coherent light source. Owing to the low-coherency of the light-source (halogen lamp), only the light reflected from reflective surface at a specific sectioning height generates an interference image on the CCD camera. P19CL6 EC cells, derived from mouse teratocarcinomas, formed spheroids that are about 50 to 200 micrometers in diameter. Since the height of each cell is around 10 micrometers, it is assumed that each spheroid has 5 to 20 cell layers. The P19CL6 spheroids were imaged in an upright configuration and the horizontally sectioned reflection images of the sample were obtained by sequentially and vertically scanning the zero-path-length height. Our results show the threedimensional structure of the spheroids, in which plasma and nuclear membranes were distinguishably imaged. The results imply that our technique is further capable of imaging induced pluripotent stem (iPS) cells for the assessment of cell properties including their pluripotency.

Scanning electrochemical microscopy of precursor sites for pitting corrosion on titanium

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

Casillas, N.; Charlebois, S.J.; Smyrl, W.H.

1993-09-01

Scanning electrochemical microscopy, SECM, of oxide-covered titanium foils ([approximately]50 [angstrom] oxide thickness) immersed in potassium bromide solutions is reported. Electrogeneration of bromine (2 Br[sup [minus

Publications - GMC 357 | Alaska Division of Geological & Geophysical

Science.gov Websites

DGGS GMC 357 Publication Details Title: Thin Section and Scanning Electron Microscopy summary Laboratories, Inc., 2008, Thin Section and Scanning Electron Microscopy summary photographs from plugs taken

Ultrafast photon counting applied to resonant scanning STED microscopy.

PubMed

Wu, Xundong; Toro, Ligia; Stefani, Enrico; Wu, Yong

2015-01-01

To take full advantage of fast resonant scanning in super-resolution stimulated emission depletion (STED) microscopy, we have developed an ultrafast photon counting system based on a multigiga sample per second analogue-to-digital conversion chip that delivers an unprecedented 450 MHz pixel clock (2.2 ns pixel dwell time in each scan). The system achieves a large field of view (∼50 × 50 μm) with fast scanning that reduces photobleaching, and advances the time-gated continuous wave STED technology to the usage of resonant scanning with hardware-based time-gating. The assembled system provides superb signal-to-noise ratio and highly linear quantification of light that result in superior image quality. Also, the system design allows great flexibility in processing photon signals to further improve the dynamic range. In conclusion, we have constructed a frontier photon counting image acquisition system with ultrafast readout rate, excellent counting linearity, and with the capacity of realizing resonant-scanning continuous wave STED microscopy with online time-gated detection. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

Multi-Probe SPM using Interference Patterns for a Parallel Nano Imaging

NASA Astrophysics Data System (ADS)

Koyama, Hirotaka; Oohira, Fumikazu; Hosogi, Maho; Hashiguchi, Gen

This paper proposes a new composition of the multi-probe using optical interference patterns for a parallel nano imaging in a large area scanning. We achieved large-scale integration with 50,000 probes fabricated with MEMS technology, and measured the optical interference patterns with CCD, which was difficult in a conventional single scanning probe. In this research, the multi-probes are made of Si3N4 by MEMS process, and, the multi-probes are joined with a Pyrex glass by an anodic bonding. We designed, fabricated, and evaluated the characteristics of the probe. In addition, we changed the probe shape to decrease the warpage of the Si3N4 probe. We used the supercritical drying to avoid stiction of the Si3N4 probe with the glass surface and fabricated 4 types of the probe shapes without stiction. We took some interference patterns by CCD and measured the position of them. We calculate the probe height using the interference displacement and compared the result with the theoretical deflection curve. As a result, these interference patterns matched the theoretical deflection curve. We found that this multi-probe chip using interference patterns is effective in measurement for a parallel nano imaging.

Femtosecond laser-induced periodic surface structures on titanium nitride coatings for tribological applications

NASA Astrophysics Data System (ADS)

Bonse, J.; Kirner, S. V.; Koter, R.; Pentzien, S.; Spaltmann, D.; Krüger, J.

2017-10-01

Titanium nitride (TiN) was coated on different substrate materials, namely pure titanium (Ti), titanium alloy (Ti6Al4V) and steel (100Cr6), generating 2.5 μm thick TiN layers. Using femtosecond laser pulses (30 fs, 790 nm, 1 kHz pulse repetition rate), large surface areas (5 mm × 5 mm) of laser-induced periodic surface structures (LIPSS) with sub-wavelength periods ranging between 470 nm and 600 nm were generated and characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). In tribological tests, coefficients of friction (COF) of the nanostructured surfaces were determined under reciprocating sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel during 1000 cycles using two different lubricants, namely paraffin oil and engine oil. It turned out that the substrate material, the laser fluence and the lubricant are crucial for the tribological performance. However, friction and wear could not be significantly reduced by LIPSS on TiN layers in comparison to unstructured TiN surfaces. Finally, the resulting wear tracks on the nanostructured surfaces were investigated with respect to their morphology (OM, SEM), depth (WLIM) and chemical composition by energy dispersive X-ray spectroscopy (EDX) and, on one hand, compared with each other, on the other hand, with non-structured TiN surfaces.

Laser scanning saturated structured illumination microscopy based on phase modulation

NASA Astrophysics Data System (ADS)

Huang, Yujia; Zhu, Dazhao; Jin, Luhong; Kuang, Cuifang; Xu, Yingke; Liu, Xu

2017-08-01

Wide-field saturated structured illumination microscopy has not been widely used due to the requirement of high laser power. We propose a novel method called laser scanning saturated structured illumination microscopy (LS-SSIM), which introduces high order of harmonics frequency and greatly reduces the required laser power for SSIM imaging. To accomplish that, an excitation PSF with two peaks is generated and scanned along different directions on the sample. Raw images are recorded cumulatively by a CCD detector and then reconstructed to form a high-resolution image with extended optical transfer function (OTF). Our theoretical analysis and simulation results show that LS-SSIM method reaches a resolution of 0.16 λ, equivalent to 2.7-fold resolution than conventional wide-field microscopy. In addition, LS-SSIM greatly improves the optical sectioning capability of conventional wide-field illumination system by diminishing our-of-focus light. Furthermore, this modality has the advantage of implementation in multi-photon microscopy with point scanning excitation to image samples in greater depths.

Scanning ultrafast electron microscopy

PubMed Central

Yang, Ding-Shyue; Mohammed, Omar F.; Zewail, Ahmed H.

2010-01-01

Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for which the pulse contains at most one or a few electrons, thus achieving imaging without the space-charge effect between electrons, and still in ten(s) of seconds. For imaging, the secondary electrons from surface structures are detected, as demonstrated here for material surfaces and biological specimens. By recording backscattered electrons, diffraction patterns from single crystals were also obtained. Scanning pulsed-electron microscopy with the acquired spatiotemporal resolutions, and its efficient heat-dissipation feature, is now poised to provide in situ 4D imaging and with environmental capability. PMID:20696933

High-resolution photoluminescence electro-modulation microscopy by scanning lock-in

NASA Astrophysics Data System (ADS)

Koopman, W.; Muccini, M.; Toffanin, S.

2018-04-01

Morphological inhomogeneities and structural defects in organic semiconductors crucially determine the charge accumulation and lateral transport in organic thin-film transistors. Photoluminescence Electro-Modulation (PLEM) microscopy is a laser-scanning microscopy technique that relies on the modulation of the thin-film fluorescence in the presence of charge-carriers to image the spatial distribution of charges within the active organic semiconductor. Here, we present a lock-in scheme based on a scanning beam approach for increasing the PLEM microscopy resolution and contrast. The charge density in the device is modulated by a sinusoidal electrical signal, phase-locked to the scanning beam of the excitation laser. The lock-in detection scheme is achieved by acquiring a series of images with different phases between the beam scan and the electrical modulation. Application of high resolution PLEM to an organic transistor in accumulation mode demonstrates its potential to image local variations in the charge accumulation. A diffraction-limited precision of sub-300 nm and a signal to noise ratio of 21.4 dB could be achieved.

Laser interference microscopy: a novel approach to the visualization of structural changes in myelin during the propagation of nerve impulses

NASA Astrophysics Data System (ADS)

Yusipovich, A. I.; Cherkashin, A. A.; Verdiyan, E. E.; Sogomonyan, I. A.; Maksimov, G. V.

2016-08-01

We used 3D phase images obtained by laser interference microscopy (LIM) for ex vivo evaluation of changes in the structure of myelin during repetitive stimulation. In this work we propose a simple model of myelinated nerve fiber (mNF), which describes phase images as a result of different geometry and membrane-to-cytoplasm ratio in various regions, particularly, the internode and paranodal-nodal-paranodal region, including the node of Ranvier. Application of this model provides clear interpretation of the phase images and also demonstrates that repetitive action potentials are accompanied by structural changes in myelin in the internode and cytoplasmic modification in the node of Ranvier. The first 20 min of stimulation did not induce significant changes in the measured parameters, but then the optical path difference at the periphery of mNF and at the node of Ranvier declined reversibly. We believe that our model is also applicable to other modifications of interference and non-interference imaging.

X-ray induced chemical reaction revealed by in-situ X-ray diffraction and scanning X-ray microscopy in 15 nm resolution (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ge, Mingyuan; Liu, Wenjun; Bock, David; De Andrade, Vincent; Yan, Hanfei; Huang, Xiaojing; Marschilok, Amy; Takeuchi, Esther; Xin, Huolin; Chu, Yong S.

2016-09-01

The detection sensitivity of synchrotron-based X-ray techniques has been largely improved due to the ever increasing source brightness, which have significantly advanced ex-situ and in-situ research for energy materials, such as lithium-ion batteries. However, the strong beam-matter interaction arisen from the high beam flux can significantly modify the material structure. The parasitic beam-induced effect inevitably interferes with the intrinsic material property, which brings difficulties in interpreting experimental results, and therefore requires comprehensive evaluation. Here we present a quantitative in-situ study of the beam-effect on one electrode material Ag2VO2PO4 using four different X-ray probes with different radiation dose rate. The material system we reported exhibits interesting and reversible radiation-induced thermal and chemical reactions, which was further evaluated under electron microscopy to illustrate the underlying mechanism. The work we presented here will provide a guideline in using synchrotron X-rays to distinguish the materials' intrinsic behavior from extrinsic structure changed induced by X-rays, especially in the case of in-situ and operando study where the materials are under external field of either temperature or electric field.

Preparation and characterization of polymer layer systems for validation of 3D Micro X-ray fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Schaumann, Ina; Malzer, Wolfgang; Mantouvalou, Ioanna; Lühl, Lars; Kanngießer, Birgit; Dargel, Rainer; Giese, Ulrich; Vogt, Carla

2009-04-01

For the validation of the quantification of the newly-developed method of 3D Micro X-ray fluorescence spectroscopy (3D Micro-XRF) samples with a low average Z matrix and minor high Z elements are best suited. In a light matrix the interferences by matrix effects are minimized so that organic polymers are appropriate as basis for analytes which are more easily detected by X-ray fluorescence spectroscopy. Polymer layer systems were assembled from single layers of ethylene-propylene-diene rubber (EPDM) filled with changing concentrations of silica and zinc oxide as inorganic additives. Layer thicknesses were in the range of 30-150 μm. Before the analysis with 3D Micro-XRF all layers have been characterized by scanning micro-XRF with regard to filler dispersion, by infrared microscopy and light microscopy in order to determine the layer thicknesses and by ICP-OES to verify the concentration of the X-ray sensitive elements in the layers. With the results obtained for stacked polymer systems the validity of the analytical quantification model for the determination of stratified materials by 3D Micro-XRF could be demonstrated.

Integration of a highly ordered gold nanowires array with glucose oxidase for ultra-sensitive glucose detection.

PubMed

Cui, Jiewu; Adeloju, Samuel B; Wu, Yucheng

2014-01-27

A highly sensitive amperometric nanobiosensor has been developed by integration of glucose oxidase (GO(x)) with a gold nanowires array (AuNWA) by cross-linking with a mixture of glutaraldehyde (GLA) and bovine serum albumin (BSA). An initial investigation of the morphology of the synthesized AuNWA by field emission scanning electron microscopy (FESEM) and field emission transmission electron microscopy (FETEM) revealed that the nanowires array was highly ordered with rough surface, and the electrochemical features of the AuNWA with/without modification were also investigated. The integrated AuNWA-BSA-GLA-GO(x) nanobiosensor with Nafion membrane gave a very high sensitivity of 298.2 μA cm(-2) mM(-1) for amperometric detection of glucose, while also achieving a low detection limit of 0.1 μM, and a wide linear range of 5-6000 μM. Furthermore, the nanobiosensor exhibited excellent anti-interference ability towards uric acid (UA) and ascorbic acid (AA) with the aid of Nafion membrane, and the results obtained for the analysis of human blood serum indicated that the device is capable of glucose detection in real samples. Copyright © 2013 Elsevier B.V. All rights reserved.

One-pot synthesis of NiO/Mn2O3 nanoflake arrays and their application in electrochemical biosensing

NASA Astrophysics Data System (ADS)

Wang, Yao; Cui, Jiewu; Luo, Lan; Zhang, Jingcheng; Wang, Yan; Qin, Yongqiang; Zhang, Yong; Shu, Xia; Lv, Jun; Wu, Yucheng

2017-11-01

The exploration of novel nanomaterials employed as substrate to construct glucose biosensors is still of significance in the field of clinical diagnosis. In this work, NiO/Mn2O3 nanoflake arrays were synthesized by hydrothermal approach in combination with calcination process. As-prepared NiO/Mn2O3 nanoflake arrays were utilized to construct electrochemical biosensors for glucose detection. NiO/Mn2O3 nanoflake arrays were investigated systematically by scanning electron microscopy (SEM), X-ray diffractionmeter (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy, the formation mechanism of NiO/Mn2O3 nanoflake arrays was proposed. As-prepared glucose biosensors based on NiO/Mn2O3 nanoflake arrays were characterized by cyclic voltammgrams and chronoamperometry. The results indicated that glucose biosensors based on optimized NiO/Mn2O3 nanoflake arrays exhibited a high sensitivity of 167.0 μA mM-1 Cm-2 and good anti-interference ability, suggesting the NiO/Mn2O3 nanoflake arrays are an attractive substrate for the construction of oxidase-based biosensors.

New morphological data on Cucullanus pinnai pinnai (Nematoda) parasitizing Pimelodus maculatus (Pimelodidae) in southeastern Brazil.

PubMed

Vieira, Vivian Suane de Freitas; Vieira, Fabiano Matos; Luque, José Luis

2015-01-01

This paper describes the morphology of Cucullanus pinnai pinnai parasitizing Pimelodus maculatus in the Guandu River, Brazil, based on differential interference contrast (DIC) microscopy and scanning electron microscopy (SEM), providing new morphological data about this species of parasite. Nematodes were collected between May and October 2012 from specimens of Pimelodus maculatus in the Guandu River (22°48'2"S, 43°37'35"W), in the state of Rio de Janeiro, Brazil. Some characteristics of specimens of Cucullanus in this study fall within the range of morphological variations of previously studied C. pinnai pinnai. Most of the specimens studied here had excretory pore and deirids located at the posterior end of the oesophagus, a feature not recorded in previous studies of this species. In addition, the size of the gubernaculum was larger than the other specimens previously studied. The SEM and DIC analyses of C. pinnai revealed several morphological details of the cephalic region and the tail papillae. With regard to the polymorphism of C. pinnai, morphological and genetic studies of this cucullanid nematode are needed, involving large numbers of host species and a wide geographical distribution.

Residual matrix from different separation techniques impacts exosome biological activity.

PubMed

Paolini, Lucia; Zendrini, Andrea; Di Noto, Giuseppe; Busatto, Sara; Lottini, Elisabetta; Radeghieri, Annalisa; Dossi, Alessandra; Caneschi, Andrea; Ricotta, Doris; Bergese, Paolo

2016-03-24

Exosomes are gaining a prominent role in research due to their intriguing biology and several therapeutic opportunities. However, their accurate purification from body fluids and detailed physicochemical characterization remain open issues. We isolated exosomes from serum of patients with Multiple Myeloma by four of the most popular purification methods and assessed the presence of residual contaminants in the preparations through an ad hoc combination of biochemical and biophysical techniques - including Western Blot, colloidal nanoplasmonics, atomic force microscopy (AFM) and scanning helium ion microscopy (HIM). The preparations obtained by iodixanol and sucrose gradients were highly pure. To the contrary, those achieved with limited processing (serial centrifugation or one step precipitation kit) resulted contaminated by a residual matrix, embedding the exosomes. The contaminated preparations showed lower ability to induce NfkB nuclear translocation in endothelial cells with respect to the pure ones, probably because the matrix prevents the interaction and fusion of the exosomes with the cell membrane. These findings suggest that exosome preparation purity must be carefully assessed since it may interfere with exosome biological activity. Contaminants can be reliably probed only by an integrated characterization approach aimed at both the molecular and the colloidal length scales.

Light-induced covalent immobilization of monolayers of magnetic nanoparticles on hydrogen-terminated silicon.

PubMed

Leem, Gyu; Zhang, Shishan; Jamison, Andrew C; Galstyan, Eduard; Rusakova, Irene; Lorenz, Bernd; Litvinov, Dmitri; Lee, T Randall

2010-10-01

Specifically tailored ω-alkenyl-1-carboxylic acids were synthesized for use as surfactants in the single-step preparation of manganese ferrite (MnFe2O4) nanoparticles (NPs). Monodisperse manganese ferrite NPs terminated with ω-alkenyl moieties were prepared via a one-pot reaction at high temperature without the need of ligand exchange. Using this approach, simple adjustment of the rate of heating allowed precise tuning of the size of the nanoparticles, which were characterized in bulk form by transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD). These surfactant-coated magnetic nanoparticles were then deposited onto hydrogen-terminated silicon(111) wafers and covalently anchored to the surface by UV-initiated covalent bonding. Analysis by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) confirmed that the UV treatment led to covalent immobilization of the NPs on the silicon surface with a consistent packing density across the surface. The magnetic properties of the stable, surface-bound nanoparticle arrays were characterized using a superconducting quantum interference device (SQUID) magnetometer. The materials and methods described here are being developed for use in bit-patterned ultrahigh density magnetic recording media and nanoscale biomagnetic sensing.

Soybean extracts facilitate bacterial agglutination and prevent biofilm formation on orthodontic wire.

PubMed

Lee, Heon-Jin; Kwon, Tae-Yub; Kim, Kyo-Han; Hong, Su-Hyung

2014-01-01

Soybean is an essential food ingredient that contains a class of organic compounds known as isoflavones. It is also well known that several plant agglutinins interfere with bacterial adherence to smooth surfaces. However, little is known about the effects of soybean extracts or genistein (a purified isoflavone from soybean) on bacterial biofilm formation. We evaluated the effects of soybean (Glycine max) extracts, including fermented soybean and genistein, on streptococcal agglutination and attachment onto stainless steel orthodontic wire. After cultivating streptococci in biofilm medium containing soybean extracts and orthodontic wire, the viable bacteria attached to the wire were counted. Phase-contrast microscopy and scanning electron microscopy (SEM) analyses were conducted to evaluate bacterial agglutination and attachment. Our study showed that soybean extracts induce agglutination between streptococci, which results in bacterial precipitation. Conversely, viable bacterial counting and SEM image analysis of Streptococcus mutans attached to the orthodontic wire show that bacterial attachment decreases significantly when soybean extracts were added. However, there was no significant change in pre-attached S. mutans biofilm in response to soybean. A possible explanation for these results is that increased agglutination of planktonic streptococci by soybean extracts results in inhibition of bacterial attachment onto the orthodontic wire.

In situ KPFM imaging of local photovoltaic characteristics of structured organic photovoltaic devices.

PubMed

Watanabe, Satoshi; Fukuchi, Yasumasa; Fukasawa, Masako; Sassa, Takafumi; Kimoto, Atsushi; Tajima, Yusuke; Uchiyama, Masanobu; Yamashita, Takashi; Matsumoto, Mutsuyoshi; Aoyama, Tetsuya

2014-02-12

Here, we discuss the local photovoltaic characteristics of a structured bulk heterojunction, organic photovoltaic devices fabricated with a liquid carbazole, and a fullerene derivative based on analysis by scanning kelvin probe force microscopy (KPFM). Periodic photopolymerization induced by an interference pattern from two laser beams formed surface relief gratings (SRG) in the structured films. The surface potential distribution in the SRGs indicates the formation of donor and acceptor spatial distribution. Under illumination, the surface potential reversibly changed because of the generation of fullerene anions and hole transport from the films to substrates, which indicates that we successfully imaged the local photovoltaic characteristics of the structured photovoltaic devices. Using atomic force microscopy, we confirmed the formation of the SRG because of the material migration to the photopolymerized region of the films, which was induced by light exposure through photomasks. The structuring technique allows for the direct fabrication and the control of donor and acceptor spatial distribution in organic photonic and electronic devices with minimized material consumption. This in situ KPFM technique is indispensable to the fabrication of nanoscale electron donor and electron acceptor spatial distribution in the devices.

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.

Simultaneous determination of epinephrine and dopamine by electrochemical reduction on the hybrid material SiO₂/graphene oxide decorated with Ag nanoparticles.

PubMed

Cincotto, Fernando H; Canevari, Thiago C; Campos, Anderson M; Landers, Richard; Machado, Sérgio A S

2014-09-21

This paper describes the synthesis, characterization and applications of a new hybrid material composed of mesoporous silica (SiO2) modified with graphene oxide (GO), SiO2/GO, obtained by the sol-gel process using HF as the catalyst. The hybrid material, SiO2/GO, was decorated with silver nanoparticles (AgNPs) with a size of less than 20 nanometres, prepared directly on the surface of the material using N,N-dimethylformamide (DMF) as the reducing agent. The resulting material was designated as AgNP/SiO2/GO. The Ag/SiO2/GO material was characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and high-resolution transmission electron microscopy (HR-TEM). A glassy carbon electrode modified with AgNP/SiO2/GO was used in the development of a sensitive electrochemical sensor for the simultaneous determination of epinephrine and dopamine employing electrocatalytic reduction using squarewave voltammetry. Well-defined and separate reduction peaks were observed in PBS buffer at pH 7. No significant interference was seen for primarily biological interferents such as uric acid and ascorbic acid in the detection of dopamine and epinephrine. Our study demonstrated that the resultant AgNP/SiO2/GO-modified electrode is highly sensitive for the simultaneous determination of dopamine and epinephrine, with the limits of detection being 0.26 and 0.27 μmol L(-1), respectively. The AgNP/SiO2/GO-modified electrode is highly selective and can be used to detect dopamine and epinephrine in a human urine sample.

Dynamic light scattering microscopy

NASA Astrophysics Data System (ADS)

Dzakpasu, Rhonda

An optical microscope technique, dynamic light scattering microscopy (DLSM) that images dynamically scattered light fluctuation decay rates is introduced. Using physical optics we show theoretically that within the optical resolution of the microscope, relative motions between scattering centers are sufficient to produce significant phase variations resulting in interference intensity fluctuations in the image plane. The time scale for these intensity fluctuations is predicted. The spatial coherence distance defining the average distance between constructive and destructive interference in the image plane is calculated and compared with the pixel size. We experimentally tested DLSM on polystyrene latex nanospheres and living macrophage cells. In order to record these rapid fluctuations, on a slow progressive scan CCD camera, we used a thin laser line of illumination on the sample such that only a single column of pixels in the CCD camera is illuminated. This allowed the use of the rate of the column-by-column readout transfer process as the acquisition rate of the camera. This manipulation increased the data acquisition rate by at least an order of magnitude in comparison to conventional CCD cameras rates defined by frames/s. Analysis of the observed fluctuations provides information regarding the rates of motion of the scattering centers. These rates, acquired from each position on the sample are used to create a spatial map of the fluctuation decay rates. Our experiments show that with this technique, we are able to achieve a good signal-to-noise ratio and can monitor fast intensity fluctuations, on the order of milliseconds. DLSM appears to provide dynamic information about fast motions within cells at a sub-optical resolution scale and provides a new kind of spatial contrast.

Coherent x-ray zoom condenser lens for diffractive and scanning microscopy.

PubMed

Kimura, Takashi; Matsuyama, Satoshi; Yamauchi, Kazuto; Nishino, Yoshinori

2013-04-22

We propose a coherent x-ray zoom condenser lens composed of two-stage deformable Kirkpatrick-Baez mirrors. The lens delivers coherent x-rays with a controllable beam size, from one micrometer to a few tens of nanometers, at a fixed focal position. The lens is suitable for diffractive and scanning microscopy. We also propose non-scanning coherent diffraction microscopy for extended objects by using an apodized focused beam produced by the lens with a spatial filter. The proposed apodized-illumination method will be useful in highly efficient imaging with ultimate storage ring sources, and will also open the way to single-shot coherent diffraction microscopy of extended objects with x-ray free-electron lasers.

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

PubMed

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

2005-01-01

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

Further description of Cruzia tentaculata (Rudolphi, 1819) Travassos, 1917 (Nematoda: Cruzidae) by light and scanning electron microscopy.

PubMed

Adnet, F A O; Anjos, D H S; Menezes-Oliveira, A; Lanfredi, R M

2009-04-01

Species of Cruzia are parasites of the large intestine of marsupials, reptiles, amphibians, and mammalians. Cruzia tentaculata specimens were collected from the large intestine of Didelphis marsupialis (Mammalia: Didelphidae) from Colombia (new geographical record) and from Brazil and analyzed by light and scanning electron microscopy. The morphology of males and females by light microscopy corroborated most of the previous description and the ultrastructure by scanning electron microscopy evidence: the topography of the cuticle, deirids, amphids, phasmids in both sexes, a pair of papillae near the vulva opening, and the number and location of male caudal papillae, adding new features for species identification only observed by this technique.

Scanning tunneling microscopy measurements of the spin Hall effect in tungsten films by using iron-coated tungsten tips

NASA Astrophysics Data System (ADS)

Xie, Ting; Dreyer, Michael; Bowen, David; Hinkel, Dan; Butera, R. E.; Krafft, Charles; Mayergoyz, Isaak

2018-05-01

Scanning tunneling microscopy experiments using iron-coated tungsten tips and current-carrying tungsten films have been conducted. An asymmetry of the tunneling current with respect to the change of the direction of the bias current through a tungsten film has been observed. It is argued that this asymmetry is a manifestation of the spin Hall effect in the current-carrying tungsten film. Nanoscale variations of this asymmetry across the tungsten film have been studied by using the scanning tunneling microscopy technique.

A scanning electron microscopy study of the macro-crystalline structure of 2-(2,4-dinitrobenzyl) pyridine

NASA Technical Reports Server (NTRS)

Ware, Jacqueline; Hammond, Ernest C., Jr.

1989-01-01

The compound, 2-(2,4-dinitrobenzyl) pyridine, was synthesized in the laboratory; an introductory level electron microscopy study of the macro-crystalline structure was conducted using the scanning electron microscope (SEM). The structure of these crystals was compared with the macrostructure of the crystal of 2-(2,4-dinitrobenzyl) pyridinium bromide, the hydrobromic salt of the compound which was also synthesized in the laboratory. A scanning electron microscopy crystal study was combined with a study of the principle of the electron microscope.

Application of laser scanning speckle-microscopy for high-resolution express diagnostics of chlamydial infection

NASA Astrophysics Data System (ADS)

Ulyanov, Sergey; Larionova, Olga; Ulianova, Onega; Zaitsev, Sergey; Saltykov, Yury; Polyanina, Tatiana; Lyapina, Anna; Filonova, Nadezhda; Subbotina, Irina; Kalduzova, Irina; Utz, Sergey; Moiseeva, Yulia; Feodorova, Valentina

2018-04-01

Method of speckle-microscopy has been adapted to the problem of detection of Chlamydia trachomatis microbial cells in clinical samples. Prototype of laser scanning speckle-microscope has been designed. Spatial resolution and output characteristics of this microscope have been analyzed for the case of scanning of C. trachomatis bacteria inclusions - Elementary Bodies (EBs) inside the human cells, fixed on the glass. It has been demonstrated, that presence of C. trachomatis microbial cells in the sample can be easily detected using speckle microscopy.

Accurate Virus Quantitation Using a Scanning Transmission Electron Microscopy (STEM) Detector in a Scanning Electron Microscope

DTIC Science & Technology

2017-06-29

Accurate Virus Quantitation Using a Scanning Transmission Electron Microscopy (STEM) Detector in a Scanning Electron Microscope Candace D Blancett1...L Norris2, Cynthia A Rossi4 , Pamela J Glass3, Mei G Sun1,* 1 Pathology Division, United States Army Medical Research Institute of Infectious...Diseases (USAMRIID), 1425 Porter Street, Fort Detrick, Maryland, 21702 2Biostatistics Division, United States Army Medical Research Institute of

Development of clinical dosage forms for a poorly water-soluble drug II: formulation and characterization of a novel solid microemulsion preconcentrate system for oral delivery of a poorly water-soluble drug.

PubMed

Li, Ping; Hynes, Sara R; Haefele, Thomas F; Pudipeddi, Madhu; Royce, Alan E; Serajuddin, Abu T M

2009-05-01

The solution of a poorly water-soluble drug in a liquid lipid-surfactant mixture, which served as a microemulsion preconcentrate, was converted into a solid form by incorporating it in a solid polyethylene glycol (PEG) matrix. The solid microemulsion preconcentrates thus formed consisted of Capmul PG8 (propylene glycol monocaprylate) as oil, Cremophor EL (polyoxyl 35 castor oil) as surfactant, and hydrophilic polymer PEG 3350 as solid matrix. The drug (aqueous solubility: 0.17 microg/mL at pH 1-8 and 25 degrees C) was dissolved in a melt of the mixture at 65-70 degrees C and then the hot solution was filled into hard gelatin capsules; the liquid gradually solidified upon cooling below 55 degrees C. The solid system was characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), confocal Raman microscopy (CRM), and the dispersion testing in water. It was confirmed that a solid microemulsion preconcentrate is a two-phase system, where clusters of crystalline PEG 3350 formed the solid structure (m.p. 55-60 degrees C) and the liquid microemulsion preconcentrate dispersed in between PEG 3350 crystals as a separate phase. The drug remained dissolved in the liquid phase. In vitro release testing showed that the preconcentrate dispersed readily in water forming a microemulsion with the drug dissolved in the oil particles (<150 nm) and the presence of PEG 3350 did not interfere with the process of self-microemulsification.

Electron probe X-ray microanalysis of cultured myogenic C2C12 cells with scanning and scanning transmission electron microscopy.

PubMed

Tylko, G; Karasiński, J; Wróblewski, R; Roomans, G M; Kilarski, W M

2000-01-01

Heterogeneity of the elemental content of myogenic C2C12 cultured cells was studied by electron probe X-ray microanalysis (EPXMA) with scanning (SEM EPXMA) and scanning transmission electron microscopy (STEM EPXMA). The best plastic substrate for growing cells was Thermanox. For STEM EPXMA, a Formvar film coated with carbon was found to be suitable substrate. The cells examined by scanning transmission electron microscopy showed great heterogeneity in their elemental content in comparison with the cells examined in the scanning electron microscope despite of an almost identical preparation procedure for EPXMA. Nevertheless the K/Na ratios obtained from both methods of EPXMA were very close (4.1 and 4.3). We conclude that the observed discrepancy in the elemental content obtained by the two methods may be due to differences in instrumentation and this must be taken into account when planning a comparative study.

Superresolution upgrade for confocal spinning disk systems using image scanning microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Isbaner, Sebastian; Hähnel, Dirk; Gregor, Ingo; Enderlein, Jörg

2017-02-01

Confocal Spinning Disk Systems are widely used for 3D cell imaging because they offer the advantage of optical sectioning at high framerates and are easy to use. However, as in confocal microscopy, the imaging resolution is diffraction limited, which can be theoretically improved by a factor of 2 using the principle of Image Scanning Microscopy (ISM) [1]. ISM with a Confocal Spinning Disk setup (CSDISM) has been shown to improve contrast as well as lateral resolution (FWHM) from 201 +/- 20 nm to 130 +/- 10 nm at 488 nm excitation. A minimum total acquisition time of one second per ISM image makes this method highly suitable for 3D live cell imaging [2]. Here, we present a multicolor implementation of CSDISM for the popular Micro-Manager Open Source Microscopy platform. Since changes in the optical path are not necessary, this will allow any researcher to easily upgrade their standard Confocal Spinning Disk system at remarkable low cost ( 5000 USD) with an ISM superresolution option. [1]. Müller, C.B. and Enderlein, J. Image Scanning Microscopy. Physical Review Letters 104, (2010). [2]. Schulz, O. et al. Resolution doubling in fluorescence microscopy with confocal spinning-disk image scanning microscopy. Proceedings of the National Academy of Sciences of the United States of America 110, 21000-5 (2013).

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.

Video image processing greatly enhances contrast, quality, and speed in polarization-based microscopy

PubMed Central

1981-01-01

Video cameras with contrast and black level controls can yield polarized light and differential interference contrast microscope images with unprecedented image quality, resolution, and recording speed. The theoretical basis and practical aspects of video polarization and differential interference contrast microscopy are discussed and several applications in cell biology are illustrated. These include: birefringence of cortical structures and beating cilia in Stentor, birefringence of rotating flagella on a single bacterium, growth and morphogenesis of echinoderm skeletal spicules in culture, ciliary and electrical activity in a balancing organ of a nudibranch snail, and acrosomal reaction in activated sperm. PMID:6788777

Live cell refractometry based on non-SPR microparticle sensor.

PubMed

Liu, Chang; Chen, David D Y; Yu, Lirong; Luo, Yong

2013-06-01

Unlike the nanoparticles with surface plasmon resonance, the optical response of polystyrene microparticles (PSMPs) is insensitive to the chemical components of the surrounding medium under the wavelength-dependent differential interference contrast microscopy. This fact is exploited for the measurement of the refractive index of cytoplasm in this study. PSMPs of 400 nm in diameter were loaded into the cell to contact cytoplasm seamlessly, and the refractive index information of cytoplasm could be extracted by differential interference contrast microscopy operated at 420 nm illumination wavelength through the contrast analysis of PSMPs images. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nomarski differential interference contrast microscopy for surface slope measurements: an examination of techniques

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

Hartman, J.S.; Gordon, R.L.; Lessor, D.L.

1981-08-01

Alternate measurement and data analysis procedures are discussed and compared for the application of reflective Nomarski differential interference contrast microscopy for the determination of surface slopes. The discussion includes the interpretation of a previously reported iterative procedure using the results of a detailed optical model and the presentation of a new procedure based on measured image intensity extrema. Surface slope determinations from these procedures are presented and compared with results from a previously reported curve fit analysis of image intensity data. The accuracy and advantages of the different procedures are discussed.

Publications - GMC 58 | Alaska Division of Geological & Geophysical Surveys

Science.gov Websites

DGGS GMC 58 Publication Details Title: X-ray diffraction and scanning electron microscopy mineral , Michael, and Core Laboratories, 1985, X-ray diffraction and scanning electron microscopy mineral analyses

Measuring Roughnesses Of Optical Surfaces

NASA Technical Reports Server (NTRS)

Coulter, Daniel R.; Al-Jumaily, Gahnim A.; Raouf, Nasrat A.; Anderson, Mark S.

1994-01-01

Report discusses use of scanning tunneling microscopy and atomic force microscopy to measure roughnesses of optical surfaces. These techniques offer greater spatial resolution than other techniques. Report notes scanning tunneling microscopes and atomic force microscopes resolve down to 1 nm.

Emulation and design of terahertz reflection-mode confocal scanning microscopy based on virtual pinhole

NASA Astrophysics Data System (ADS)

Yang, Yong-fa; Li, Qi

2014-12-01

In the practical application of terahertz reflection-mode confocal scanning microscopy, the size of detector pinhole is an important factor that determines the performance of spatial resolution characteristic of the microscopic system. However, the use of physical pinhole brings some inconvenience to the experiment and the adjustment error has a great influence on the experiment result. Through reasonably selecting the parameter of matrix detector virtual pinhole (VPH), it can efficiently approximate the physical pinhole. By using this approach, the difficulty of experimental calibration is reduced significantly. In this article, an imaging scheme of terahertz reflection-mode confocal scanning microscopy that is based on the matrix detector VPH is put forward. The influence of detector pinhole size on the axial resolution of confocal scanning microscopy is emulated and analyzed. Then, the parameter of VPH is emulated when the best axial imaging performance is reached.

Predicting scattering scanning near-field optical microscopy of mass-produced plasmonic devices

NASA Astrophysics Data System (ADS)

Otto, Lauren M.; Burgos, Stanley P.; Staffaroni, Matteo; Ren, Shen; Süzer, Özgün; Stipe, Barry C.; Ashby, Paul D.; Hammack, Aeron T.

2018-05-01

Scattering scanning near-field optical microscopy enables optical imaging and characterization of plasmonic devices with nanometer-scale resolution well below the diffraction limit. This technique enables developers to probe and understand the waveguide-coupled plasmonic antenna in as-fabricated heat-assisted magnetic recording heads. In order to validate and predict results and to extract information from experimental measurements that is physically comparable to simulations, a model was developed to translate the simulated electric field into expected near-field measurements using physical parameters specific to scattering scanning near-field optical microscopy physics. The methods used in this paper prove that scattering scanning near-field optical microscopy can be used to determine critical sub-diffraction-limited dimensions of optical field confinement, which is a crucial metrology requirement for the future of nano-optics, semiconductor photonic devices, and biological sensing where the near-field character of light is fundamental to device operation.

Self-mixing laser diode included in scanning microwave microscope to the control of probe nanodisplacement

NASA Astrophysics Data System (ADS)

Usanov, D. A.; Skripal, A. V.; Astakhov, E. I.; Dobdin, S. Y.

2018-04-01

The possibilities of self-mixing interferometry for measuring nanodisplacement of a probe included in a near-field scanning microwave microscope have been considered. The features of the formation of a laser interference signal at current modulation of the wavelength of laser radiation have been investigated. Experimental responses of a semiconductor laser system included in scanning microwave microscope to control nanodisplacement of the probe have been demonstrated.To register the nanodisplacement of the probe, it is proposed to use the method of determining the stationary phase of a laser interference signal by low-frequency spectrum of a semiconductor laser. The change of the amplitudes of the spectral components in the spectrum of the interference signal due to creation of the standing wave in the external resonator of the laser self-mixing system has been shown. The form of the interference signal at current modulation of the radiation wavelength was experimentally obtained when the probe moves with a step of 80 nm. The results of measuring nanodisplacements of an electromagnetic translator STANDA 8MVT40-13 have been demonstrated. Deviation of the nanodisplacement of the proposed method does not exceed 15%.

Probing cytotoxicity of nanoparticles and organic compounds using scanning proton microscopy, scanning electron microscopy and fluorescence microscopy

NASA Astrophysics Data System (ADS)

Tong, Yongpeng; Li, Changming; Liang, Feng; Chen, Jianmin; Zhang, Hong; Liu, Guoqing; Sun, Huibin; Luong, John H. T.

2008-12-01

Scanning proton microscopy, scanning electron microscopy (SEM) and fluorescence microscopy have been used to probe the cytotoxicity effect of benzo[a]pyrene (BaP), ethidium bromide (EB) and nanoparticles (ZnO, Al 2O 3 and TiO 2) on a T lymphoblastic leukemia Jurkat cell line. The increased calcium ion (from CaCl 2) in the culture medium stimulated the accumulation of BaP and EB inside the cell, leading to cell death. ZnO, Al 2O 3 and TiO 2 nanoparticles, however, showed a protective effect against these two organic compounds. Such inorganic nanoparticles complexed with BaP or EB which became less toxic to the cell. Fe 2O 3 nanoparticles as an insoluble particle model scavenged by macrophage were investigated in rats. They were scavenged out of the lung tissue about 48 h after infection. This result suggest that some insoluble inorganic nanoparticles of PM (particulate matters) showed protective effects on organic toxins induced acute toxic effects as they can be scavenged by macrophage cells. Whereas, some inorganic ions such as calcium ion in PM may help environmental organic toxins to penetrate cell membrane and induce higher toxic effect.

Functional Scanning Probe Imaging of Nanostructured Solar Energy Materials

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

Giridharagopal, Rajiv; Cox, Phillip A.; Ginger, David S.

From hybrid perovskites to semiconducting polymer/fullerene blends for organic photovoltaics, many new materials being explored for energy harvesting and storage exhibit performance characteristics that depend sensitively on their nanoscale morphology. At the same time, rapid advances in the capability and accessibility of scanning probe microscopy methods over the past decade have made it possible to study processing/structure/function relationships ranging from photocurrent collection to photocarrier lifetimes with resolutions on the scale of tens of nanometers or better. Importantly, such scanning probe methods offer the potential to combine measurements of local structure with local function, and they can be implemented to studymore » materials in situ or devices in operando to better understand how materials evolve in time in response to an external stimulus or environmental perturbation. This Account highlights recent advances in the development and application of scanning probe microscopy methods that can help address such questions while filling key gaps between the capabilities of conventional electron microscopy and newer super-resolution optical methods. Focusing on semiconductor materials for solar energy applications, we highlight a range of electrical and optoelectronic scanning probe microscopy methods that exploit the local dynamics of an atomic force microscope tip to probe key properties of the solar cell material or device structure. We discuss how it is possible to extract relevant device properties using noncontact scanning probe methods as well as how these properties guide materials development. Specifically, we discuss intensity-modulated scanning Kelvin probe microscopy (IM-SKPM), time-resolved electrostatic force microscopy (trEFM), frequency-modulated electrostatic force microscopy (FM-EFM), and cantilever ringdown imaging. We explain these developments in the context of classic atomic force microscopy (AFM) methods that exploit the physics of cantilever motion and photocarrier generation to provide robust, nanoscale measurements of materials physics that are correlated with device operation. We predict that the multidimensional data sets made possible by these types of methods will become increasingly important as advances in data science expand capabilities and opportunities for image correlation and discovery.« less

Functional Scanning Probe Imaging of Nanostructured Solar Energy Materials

DOE PAGES

Giridharagopal, Rajiv; Cox, Phillip A.; Ginger, David S.

2016-08-30

From hybrid perovskites to semiconducting polymer/fullerene blends for organic photovoltaics, many new materials being explored for energy harvesting and storage exhibit performance characteristics that depend sensitively on their nanoscale morphology. At the same time, rapid advances in the capability and accessibility of scanning probe microscopy methods over the past decade have made it possible to study processing/structure/function relationships ranging from photocurrent collection to photocarrier lifetimes with resolutions on the scale of tens of nanometers or better. Importantly, such scanning probe methods offer the potential to combine measurements of local structure with local function, and they can be implemented to studymore » materials in situ or devices in operando to better understand how materials evolve in time in response to an external stimulus or environmental perturbation. This Account highlights recent advances in the development and application of scanning probe microscopy methods that can help address such questions while filling key gaps between the capabilities of conventional electron microscopy and newer super-resolution optical methods. Focusing on semiconductor materials for solar energy applications, we highlight a range of electrical and optoelectronic scanning probe microscopy methods that exploit the local dynamics of an atomic force microscope tip to probe key properties of the solar cell material or device structure. We discuss how it is possible to extract relevant device properties using noncontact scanning probe methods as well as how these properties guide materials development. Specifically, we discuss intensity-modulated scanning Kelvin probe microscopy (IM-SKPM), time-resolved electrostatic force microscopy (trEFM), frequency-modulated electrostatic force microscopy (FM-EFM), and cantilever ringdown imaging. We explain these developments in the context of classic atomic force microscopy (AFM) methods that exploit the physics of cantilever motion and photocarrier generation to provide robust, nanoscale measurements of materials physics that are correlated with device operation. We predict that the multidimensional data sets made possible by these types of methods will become increasingly important as advances in data science expand capabilities and opportunities for image correlation and discovery.« less

Determination of the thickness and structure of the skin barrier by in vivo laser scanning microscopy

NASA Astrophysics Data System (ADS)

Lademann, J.; Richter, H.; Astner, S.; Patzelt, A.; Knorr, F.; Sterry, W.; Antoniou, Ch

2008-04-01

Normal skin barrier function is an essential aspect of skin homeostasis and regeneration. Dynamic inflammatory, proliferative and neoplastic skin processes such as wound healing, psoriasis and contact dermatitis are associated with a significant disruption of the skin barrier. In recent years, there has been increasing interest in evaluating cosmetic and pharmacologic products for their ability to restore these protective properties. The gold standard for characterization of barrier function has been the measurement of the transepidermal water loss, however the disadvantage of this method is its interference with several endogenous and exogenous factors such as hydration, perspiration and topically applied substances. This study was aimed to test the clinical applicability of a fluorescence confocal laser scanning microscope (LSM) for a systematic morphologic analysis of the structure, integrity and thickness of the stratum corneum in 10 otherwise healthy volunteers. The influence of skin treatment with commercial moisturizing cream on skin barrier function was evaluated in serial non-invasive examinations. Our findings showed that in vivo LSM may represent a simple and efficient method for the characterization of skin barrier properties, such as the thickness and hydration of the stratum corneum.

Evaluation of PAN-based manganese dioxide composite for the sorptive removal of cesium-137 from aqueous solutions.

PubMed

Nilchi, A; Saberi, R; Garmarodi, S Rasouli; Bagheri, A

2012-02-01

Hydrous manganese dioxide-polyacrylonitrile (MnO(2)-PAN) was chemically synthesized and evaluated, as an organic-inorganic composite material, for the removal of radio-contaminant cesium-137 from aqueous solutions. The physico-chemical characterization was carried out by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), CHN elemental analysis, scanning electron microscopy (SEM), nitrogen adsorption-desorption studies and thermogravimetry-differential scanning calorimetry (TGA-DSC). Batch experiments were carried out as a function of contact time, interference of the coexisting ions and initial pH of adsorptive solution applying a radiotracer technique. The effect of temperature on the distribution coefficient of cesium has been utilized in order to evaluate the changes in the standard thermodynamic parameters. The results indicated that Cs(+) ions could be efficiently removed using MnO(2)-PAN composite in the pH range of 4-9 from aqueous solutions and the uptake of cesium is affected to varying degrees by the presence of some diverse co-ions. The equilibrium isotherms have been determined and the sorption data were successfully modeled using Freundlich model. Copyright © 2011 Elsevier Ltd. All rights reserved.

U-10Mo Sample Preparation and Examination using Optical and Scanning Electron Microscopy

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

Prabhakaran, Ramprashad; Joshi, Vineet V.; Rhodes, Mark A.

2016-10-01

The purpose of this document is to provide guidelines to prepare specimens of uranium alloyed with 10 weight percent molybdenum (U-10Mo) for optical metallography and scanning electron microscopy. This document also provides instructions to set up an optical microscope and a scanning electron microscope to analyze U-10Mo specimens and to obtain the required information.

U-10Mo Sample Preparation and Examination using Optical and Scanning Electron Microscopy

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

Prabhakaran, Ramprashad; Joshi, Vineet V.; Rhodes, Mark A.

2016-03-30

The purpose of this document is to provide guidelines to prepare specimens of uranium alloyed with 10 weight percent molybdenum (U-10Mo) for optical metallography and scanning electron microscopy. This document also provides instructions to set up an optical microscope and a scanning electron microscope to analyze U-10Mo specimens and to obtain the required information.

The design and construction of a cost-efficient confocal laser scanning microscope

NASA Astrophysics Data System (ADS)

Xi, Peng; Rajwa, Bartlomiej; Jones, James T.; Robinson, J. Paul

2007-03-01

The optical dissection ability of confocal microscopy makes it a powerful tool for biological materials. However, the cost and complexity of confocal scanning laser microscopy hinders its wide application in education. We describe the construction of a simplified confocal scanning laser microscope and demonstrate three-dimensional projection based on cost-efficient commercial hardware, together with available open source software.

"We Actually Saw Atoms with Our Own Eyes": Conceptions and Convictions in Using the Scanning Tunneling Microscope in Junior High School

ERIC Educational Resources Information Center

Margel, Hannah; Eylon, Bat-Sheva; Scherz, Zahava

2004-01-01

The feasibility and the potential contribution of the scanning tunneling microscopy (STM) in junior high school (JHS) as an instructional tool for learning the particulate nature of matter is described. The use and power of new technologies can probably be demonstrated by the scanning tunneling microscopy (STM).

Recommendations for the design and the installation of large laser scanning microscopy systems

NASA Astrophysics Data System (ADS)

Helm, P. Johannes

2012-03-01

Laser Scanning Microscopy (LSM) has since the inventions of the Confocal Scanning Laser Microscope (CLSM) and the Multi Photon Laser Scanning Microscope (MPLSM) developed into an essential tool in contemporary life science and material science. The market provides an increasing number of turn-key and hands-off commercial LSM systems, un-problematic to purchase, set up and integrate even into minor research groups. However, the successful definition, financing, acquisition, installation and effective use of one or more large laser scanning microscopy systems, possibly of core facility character, often requires major efforts by senior staff members of large academic or industrial units. Here, a set of recommendations is presented, which are helpful during the process of establishing large systems for confocal or non-linear laser scanning microscopy as an effective operational resource in the scientific or industrial production process. Besides the description of technical difficulties and possible pitfalls, the article also illuminates some seemingly "less scientific" processes, i.e. the definition of specific laboratory demands, advertisement of the intention to purchase one or more large systems, evaluation of quotations, establishment of contracts and preparation of the local environment and laboratory infrastructure.

Scanning Probe Microscopy | Materials Science | NREL

Science.gov Websites

. Capability of use with ultra-high vacuum makes NREL Scanning Probe Microscopy particularly valuable for vacuum, as appropriate Field of view from atoms up to about 100 µm (vertical limit of about 7 µm

CONFOCAL LASER SCANNING MICROSCOPY OF APOPTOSIS IN WHOLE MOUSE OVARIES

EPA Science Inventory

Confocal Laser Scanning Microscopy of Apoptosis in Whole Mouse Ovaries. Robert M. Zucker Susan C. Jeffay and Sally D. Perreault Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle...

Gold Coating of Fiber Tips in Near-Field Scanning Optical Microscopy

NASA Technical Reports Server (NTRS)

Vikram, Chandra S.; Witherow, William K.

2000-01-01

We report what is believed to be the first experimental demonstration of gold coating by a chemical baking process on tapered fiber tips used in near-field scanning optical microscopy. Many tips can be simultaneously coated.

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,

Two-dimensional profiling of carriers in terahertz quantum cascade lasers using calibrated scanning spreading resistance microscopy and scanning capacitance microscopy.

PubMed

Dhar, R S; Ban, D

2013-07-01

The distribution of charge carriers inside the active region of a terahertz (THz) quantum cascade laser (QCL) has been measured with scanning spreading resistance microscopy (SSRM) and scanning capacitance microscopy (SCM). Individual quantum well-barrier modules with a 35.7-nm single module thickness in the active region of the device have been resolved for the first time using high-resolution SSRM and SCM techniques at room temperature. SSRM and SCM measurements on the quantum well-barrier structure were calibrated utilizing known GaAs dopant staircase samples. Doping concentrations derived from SSRM and SCM measurements were found to be in quantitative agreement with the designed average doping values of the n-type active region in the terahertz quantum cascade laser. The secondary ion mass spectroscopy provides a partial picture of internal device parameters, and we have demonstrated with our results the efficacy of uniting calibrated SSRM and SCM to delineate quantitatively the transverse cross-sectional structure of complex two-dimensional terahertz quantum cascade laser devices. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

Ice recrystallization inhibition in ice cream by propylene glycol monostearate.

PubMed

Aleong, J M; Frochot, S; Goff, H D

2008-11-01

The effectiveness of propylene glycol monostearate (PGMS) to inhibit ice recrystallization was evaluated in ice cream and frozen sucrose solutions. PGMS (0.3%) dramatically reduced ice crystal sizes in ice cream and in sucrose solutions frozen in a scraped-surface freezer before and after heat shock, but had no effect in quiescently frozen solutions. PGMS showed limited emulsifier properties by promoting smaller fat globule size distributions and enhanced partial coalescence in the mix and ice cream, respectively, but at a much lower level compared to conventional ice cream emulsifier. Low temperature scanning electron microscopy revealed highly irregular crystal morphology in both ice cream and sucrose solutions frozen in a scraped-surface freezer. There was strong evidence to suggest that PGMS directly interacts with ice crystals and interferes with normal surface propagation. Shear during freezing may be required for its distribution around the ice and sufficient surface coverage.

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

S. K. Kushwaha; Pletikosic, I.; Liang, T.

A long-standing issue in topological insulator research has been to find a bulk single crystal material that provides a high quality platform for characterizing topological surface states without interference from bulk electronic states. This material would ideally be a bulk insulator, have a surface state Dirac point energy well isolated from the bulk valence and conduction bands, display quantum oscillations from the surface state electrons, and be growable as large, high quality bulk single crystals. Here we show that this materials obstacle is overcome by bulk crystals of lightly Sn-doped Bi 1.1Sb 0.9Te 2S grown by the Vertical Bridgeman method.more » We characterize Sn-BSTS via angle-resolved photoemission spectroscopy, scanning tunneling microscopy, transport studies, X-ray diffraction, and Raman scattering. We present this material as a high quality topological insulator that can be reliably grown as bulk single crystals and thus studied by many researchers interested in topological surface states.« less

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

Gyenis, András; Inoue, Hiroyuki; Jeon, Sangjun

Following the intense studies on topological insulators, significant efforts have recently been devoted to the search for gapless topological systems. These materials not only broaden the topological classification of matter but also provide a condensed matter realization of various relativistic particles and phenomena previously discussed mainly in high energy physics. Weyl semimetals host massless, chiral, low-energy excitations in the bulk electronic band structure, whereas a symmetry protected pair of Weyl fermions gives rise to massless Dirac fermions.Weemployed scanning tunneling microscopy/spectroscopy to explore the behavior of electronic states both on the surface and in the bulk of topological semimetal phases. Bymore » mapping the quasiparticle interference (QPI) and emerging Landau levels at high magnetic field in Dirac semimetals Cd 3As 2 and Na 3Bi, we observed extended Dirac-like bulk electronic bands. QPI imaged on Weyl semimetal TaAs demonstrated the predicted momentum dependent delocalization of Fermi arc surface states in the vicinity of the surface projected Weyl nodes.« less

Visualizing One-Dimensional Electronic States and their Scattering in Semi-conducting Nanowires

NASA Astrophysics Data System (ADS)

Beidenkopf, Haim; Reiner, Jonathan; Norris, Andrew; Nayak, Abhay Kumar; Avraham, Nurit; Shtrikman, Hadas

One-dimensional electronic systems constitute a fascinating playground for the emergence of exotic electronic effects and phases, within and beyond the Tomonaga-Luttinger liquid paradigm. More recently topological superconductivity and Majorana modes were added to that long list of phenomena. We report scanning tunneling microscopy and spectroscopy measurements conducted on pristine, epitaxialy grown InAs nanowires. We resolve the 1D electronic band structure manifested both via Van-Hove singularities in the local density-of-states, as well as by the quasi-particle interference patterns, induced by scattering from surface impurities. By studying the scattering of the one-dimensional electronic states off various scatterers, including crystallographic defects and the nanowire end, we identify new one-dimensional relaxation regimes and yet unexplored effects of interactions. Some of these may bear implications on the topological superconducting state and Majorana modes therein. The authors acknowledge support from the Israeli Science Foundation (ISF).

Delocalized Surface State in Epitaxial Si(111) Film with Spontaneous √3 × √3 Superstructure

PubMed Central

Chen, Jian; Du, Yi; Li, Zhi; Li, Wenbin; Feng, Baojie; Qiu, Jinlan; Cheng, Peng; Xue Dou, Shi; Chen, Lan; Wu, Kehui

2015-01-01

The “multilayer silicene” films were grown on Ag(111), with increasing thickness above 30 monolayers (ML). Scanning tunneling microscopy (STM) observations suggest that the “multilayer silicene” is indeed a bulk-like Si(111) film with a (√3 × √3)R30° honeycomb superstructure on surface. The possibility for formation of Si(111)(√3 × √3)R30°-Ag reconstruction on the surface can be distinctively ruled out by peeling off the surface layer with the STM tip. On this surface, delocalized surface state as well as linear energy-momentum dispersion was observed from quasiparticle interference patterns. Our results indicate that a bulklike silicon film with diamondlike structure can also host delocalized surface state, which is even more attractive for potential applications, such as new generation of nanodevices based on Si. PMID:26316281

Analysis of Long Bone and Vertebral Failure Patterns.

DTIC Science & Technology

1982-09-30

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

Scanning electron microscopy combined with image processing technique: Analysis of microstructure, texture and tenderness in Semitendinous and Gluteus Medius bovine muscles.

PubMed

Pieniazek, Facundo; Messina, Valeria

2016-11-01

In this study the effect of freeze drying on the microstructure, texture, and tenderness of Semitendinous and Gluteus Medius bovine muscles were analyzed applying Scanning Electron Microscopy combined with image analysis. Samples were analyzed by Scanning Electron Microscopy at different magnifications (250, 500, and 1,000×). Texture parameters were analyzed by Texture analyzer and by image analysis. Tenderness by Warner-Bratzler shear force. Significant differences (p < 0.05) were obtained for image and instrumental texture features. A linear trend with a linear correlation was applied for instrumental and image features. Image texture features calculated from Gray Level Co-occurrence Matrix (homogeneity, contrast, entropy, correlation and energy) at 1,000× in both muscles had high correlations with instrumental features (chewiness, hardness, cohesiveness, and springiness). Tenderness showed a positive correlation in both muscles with image features (energy and homogeneity). Combing Scanning Electron Microscopy with image analysis can be a useful tool to analyze quality parameters in meat.Summary SCANNING 38:727-734, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

Serial sectioning methods for 3D investigations in materials science.

PubMed

Zankel, Armin; Wagner, Julian; Poelt, Peter

2014-07-01

A variety of methods for the investigation and 3D representation of the inner structure of materials has been developed. In this paper, techniques based on slice and view using scanning microscopy for imaging are presented and compared. Three different methods of serial sectioning combined with either scanning electron or scanning ion microscopy or atomic force microscopy (AFM) were placed under scrutiny: serial block-face scanning electron microscopy, which facilitates an ultramicrotome built into the chamber of a variable pressure scanning electron microscope; three-dimensional (3D) AFM, which combines an (cryo-) ultramicrotome with an atomic force microscope, and 3D FIB, which delivers results by slicing with a focused ion beam. These three methods complement one another in many respects, e.g., in the type of materials that can be investigated, the resolution that can be obtained and the information that can be extracted from 3D reconstructions. A detailed review is given about preparation, the slice and view process itself, and the limitations of the methods and possible artifacts. Applications for each technique are also provided. Copyright © 2014 Elsevier Ltd. All rights reserved.

Infrared spectroscopy of molecular submonolayers on surfaces by infrared scanning tunneling microscopy: tetramantane on Au111.

PubMed

Pechenezhskiy, Ivan V; Hong, Xiaoping; Nguyen, Giang D; Dahl, Jeremy E P; Carlson, Robert M K; Wang, Feng; Crommie, Michael F

2013-09-20

We have developed a new scanning-tunneling-microscopy-based spectroscopy technique to characterize infrared (IR) absorption of submonolayers of molecules on conducting crystals. The technique employs a scanning tunneling microscope as a precise detector to measure the expansion of a molecule-decorated crystal that is irradiated by IR light from a tunable laser source. Using this technique, we obtain the IR absorption spectra of [121]tetramantane and [123]tetramantane on Au(111). Significant differences between the IR spectra for these two isomers show the power of this new technique to differentiate chemical structures even when single-molecule-resolved scanning tunneling microscopy (STM) images look quite similar. Furthermore, the new technique was found to yield significantly better spectral resolution than STM-based inelastic electron tunneling spectroscopy, and to allow determination of optical absorption cross sections. Compared to IR spectroscopy of bulk tetramantane powders, infrared scanning tunneling microscopy (IRSTM) spectra reveal narrower and blueshifted vibrational peaks for an ordered tetramantane adlayer. Differences between bulk and surface tetramantane vibrational spectra are explained via molecule-molecule interactions.

Digital Hilbert transformation for separation measurement of thicknesses and refractive indices of layered objects by use of a wavelength-scanning heterodyne interference confocal microscope.

PubMed

Watanabe, Yuuki; Yamaguchi, Ichirou

2002-08-01

A wavelength-scanning heterodyne interference confocal microscope quickly accomplishes the simultaneous measurement of the thickness and the refractive index of a sample by detection of the amplitude and the phase of the interference signal during a sample scan. However, the measurement range of the optical path difference (OPD) that is obtained from the phase changes is limited by the time response of the phase-locked loop circuit in the FM demodulator. To overcome this limitation and to improve the accuracy of the separation measurement, we propose an OPD detection using digital signal processing with a Hilbert transform. The measurement range is extended approximately five times, and the resolution of the OPD is improved to 5.5 from 9 microm without the electrical noise of the FM demodulator circuit. By applying this method for simultaneous measurement of thickness and the refractive index, we can measure samples 20-30-microm thick with refractive indices between 1 and 1.5.

Digital Hilbert transformation for separation measurement of thicknesses and refractive indices of layered objects by use of a wavelength-scanning heterodyne interference confocal microscope

NASA Astrophysics Data System (ADS)

Watanabe, Yuuki; Yamaguchi, Ichirou

2002-08-01

A wavelength-scanning heterodyne interference confocal microscope quickly accomplishes the simultaneous measurement of the thickness and the refractive index of a sample by detection of the amplitude and the phase of the interference signal during a sample scan. However, the measurement range of the optical path difference (OPD) that is obtained from the phase changes is limited by the time response of the phase-locked loop circuit in the FM demodulator. To overcome this limitation and to improve the accuracy of the separation measurement, we propose an OPD detection using digital signal processing with a Hilbert transform. The measurement range is extended approximately five times, and the resolution of the OPD is improved to 5.5 from 9 mum without the electrical noise of the FM demodulator circuit. By applying this method for simultaneous measurement of thickness and the refractive index, we can measure samples 20-30-mum thick with refractive indices between 1 and 1.5.

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

Spatial Resolution in Scanning Electron Microscopy and Scanning Transmission Electron Microscopy Without a Specimen Vacuum Chamber.

PubMed

Nguyen, Kayla X; Holtz, Megan E; Richmond-Decker, Justin; Muller, David A

2016-08-01

A long-standing goal of electron microscopy has been the high-resolution characterization of specimens in their native environment. However, electron optics require high vacuum to maintain an unscattered and focused probe, a challenge for specimens requiring atmospheric or liquid environments. Here, we use an electron-transparent window at the base of a scanning electron microscope's objective lens to separate column vacuum from the specimen, enabling imaging under ambient conditions, without a specimen vacuum chamber. We demonstrate in-air imaging of specimens at nanoscale resolution using backscattered scanning electron microscopy (airSEM) and scanning transmission electron microscopy. We explore resolution and contrast using Monte Carlo simulations and analytical models. We find that nanometer-scale resolution can be obtained at gas path lengths up to 400 μm, although contrast drops with increasing gas path length. As the electron-transparent window scatters considerably more than gas at our operating conditions, we observe that the densities and thicknesses of the electron-transparent window are the dominant limiting factors for image contrast at lower operating voltages. By enabling a variety of detector configurations, the airSEM is applicable to a wide range of environmental experiments including the imaging of hydrated biological specimens and in situ chemical and electrochemical processes.

Spatial Resolution in Scanning Electron Microscopy and Scanning Transmission Electron Microscopy Without a Specimen Vacuum Chamber

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

Nguyen, Kayla X.; Holtz, Megan E.; Richmond-Decker, Justin

2016-07-25

Abstract A long-standing goal of electron microscopy has been the high-resolution characterization of specimens in their native environment. However, electron optics require high vacuum to maintain an unscattered and focused probe, a challenge for specimens requiring atmospheric or liquid environments. Here, we use an electron-transparent window at the base of a scanning electron microscope’s objective lens to separate column vacuum from the specimen, enabling imaging under ambient conditions, without a specimen vacuum chamber. We demonstrate in-air imaging of specimens at nanoscale resolution using backscattered scanning electron microscopy (airSEM) and scanning transmission electron microscopy. We explore resolution and contrast using Montemore » Carlo simulations and analytical models. We find that nanometer-scale resolution can be obtained at gas path lengths up to 400μm, although contrast drops with increasing gas path length. As the electron-transparent window scatters considerably more than gas at our operating conditions, we observe that the densities and thicknesses of the electron-transparent window are the dominant limiting factors for image contrast at lower operating voltages. By enabling a variety of detector configurations, the airSEM is applicable to a wide range of environmental experiments including the imaging of hydrated biological specimens andin situchemical and electrochemical processes.« less

Note: Development of a wideband amplifier for cryogenic scanning tunneling microscopy.

PubMed

Zhang, Chao; Jeon, Hoyeon; Oh, Myungchul; Lee, Minjun; Kim, Sungmin; Yi, Sunwouk; Lee, Hanho; Zoh, Inhae; Yoo, Yongchan; Kuk, Young

2017-06-01

A wideband cryogenic amplifier has been developed for low temperature scanning tunneling microscopy. The amplifier consisting of a wideband complementary metal oxide semiconductor field effect transistors operational amplifier together with a feedback resistor of 100 kΩ and a capacitor is mounted within a 4 K Dewar. This amplifier has a wide bandwidth and is successfully applied to scanning tunneling microscopy applications at low temperatures down to ∼7 K. The quality of the designed amplifier is validated by high resolution imaging. More importantly, the amplifier has also proved to be capable of performing scanning tunneling spectroscopy measurements, showing the detection of the Shockley surface state of the Au(111) surface and the superconducting gap of Nb(110).

Note: Development of a wideband amplifier for cryogenic scanning tunneling microscopy

NASA Astrophysics Data System (ADS)

Zhang, Chao; Jeon, Hoyeon; Oh, Myungchul; Lee, Minjun; Kim, Sungmin; Yi, Sunwouk; Lee, Hanho; Zoh, Inhae; Yoo, Yongchan; Kuk, Young

2017-06-01

A wideband cryogenic amplifier has been developed for low temperature scanning tunneling microscopy. The amplifier consisting of a wideband complementary metal oxide semiconductor field effect transistors operational amplifier together with a feedback resistor of 100 kΩ and a capacitor is mounted within a 4 K Dewar. This amplifier has a wide bandwidth and is successfully applied to scanning tunneling microscopy applications at low temperatures down to ˜7 K. The quality of the designed amplifier is validated by high resolution imaging. More importantly, the amplifier has also proved to be capable of performing scanning tunneling spectroscopy measurements, showing the detection of the Shockley surface state of the Au(111) surface and the superconducting gap of Nb(110).

Sustained Nitric Oxide-Releasing Nanoparticles Interfere with Methicillin-Resistant Staphylococcus aureus Adhesion and Biofilm Formation in a Rat Central Venous Catheter Model

PubMed Central

Mihu, Mircea Radu; Cabral, Vitor; Pattabhi, Rodney; Tar, Moses T.; Davies, Kelvin P.; Friedman, Adam J.

2016-01-01

ABSTRACT Staphylococcus aureus is frequently isolated in the setting of infections of indwelling medical devices, which are mediated by the microbe's ability to form biofilms on a variety of surfaces. Biofilm-embedded bacteria are more resistant to antimicrobial agents than their planktonic counterparts and often cause chronic infections and sepsis, particularly in patients with prolonged hospitalizations. In this study, we demonstrate that sustained nitric oxide-releasing nanoparticles (NO-np) interfere with S. aureus adhesion and prevent biofilm formation on a rat central venous catheter (CVC) model of infection. Confocal and scanning electron microscopy showed that NO-np-treated staphylococcal biofilms displayed considerably reduced thicknesses and bacterial numbers compared to those of control biofilms in vitro and in vivo, respectively. Although both phenotypes, planktonic and biofilm-associated staphylococci, of multiple clinical strains were susceptible to NO-np, bacteria within biofilms were more resistant to killing than their planktonic counterparts. Furthermore, chitosan, a biopolymer found in the exoskeleton of crustaceans and structurally integrated into the nanoparticles, seems to add considerable antimicrobial activity to the technology. Our findings suggest promising development and translational potential of NO-np for use as a prophylactic or therapeutic against bacterial biofilms on CVCs and other medical devices. PMID:27821454

Sustained Nitric Oxide-Releasing Nanoparticles Interfere with Methicillin-Resistant Staphylococcus aureus Adhesion and Biofilm Formation in a Rat Central Venous Catheter Model.

PubMed

Mihu, Mircea Radu; Cabral, Vitor; Pattabhi, Rodney; Tar, Moses T; Davies, Kelvin P; Friedman, Adam J; Martinez, Luis R; Nosanchuk, Joshua D

2017-01-01

Staphylococcus aureus is frequently isolated in the setting of infections of indwelling medical devices, which are mediated by the microbe's ability to form biofilms on a variety of surfaces. Biofilm-embedded bacteria are more resistant to antimicrobial agents than their planktonic counterparts and often cause chronic infections and sepsis, particularly in patients with prolonged hospitalizations. In this study, we demonstrate that sustained nitric oxide-releasing nanoparticles (NO-np) interfere with S. aureus adhesion and prevent biofilm formation on a rat central venous catheter (CVC) model of infection. Confocal and scanning electron microscopy showed that NO-np-treated staphylococcal biofilms displayed considerably reduced thicknesses and bacterial numbers compared to those of control biofilms in vitro and in vivo, respectively. Although both phenotypes, planktonic and biofilm-associated staphylococci, of multiple clinical strains were susceptible to NO-np, bacteria within biofilms were more resistant to killing than their planktonic counterparts. Furthermore, chitosan, a biopolymer found in the exoskeleton of crustaceans and structurally integrated into the nanoparticles, seems to add considerable antimicrobial activity to the technology. Our findings suggest promising development and translational potential of NO-np for use as a prophylactic or therapeutic against bacterial biofilms on CVCs and other medical devices. Copyright © 2016 American Society for Microbiology.

Imaging of single retinal ganglion cell with differential interference contrast microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Oh, Juyeong; Kim, Yu Jeong; Kim, Chul-Ki; Lee, Taik Jin; Seo, Mina; Lee, Seok; Woo, Deok Ha; Jun, Seong Chan; Park, Ki-Ho; Kim, Seok Hwan; Kim, Jae Hun

2017-02-01

Glaucoma is a progressive optic neuropathy, characterized by the selective loss of retinal ganglion cells (RGCs). Therefore, monitoring the change of number or morphology of RGC is essential for the early detection as well as investigation of pathophysiology of glaucoma. Since RGC layer is transparent and hyporeflective, the direct optical visualization of RGCs has not been successful so far. Therefore, glaucoma evaluation mostly depends on indirect diagnostic methods such as the evaluation of optic disc morphology or retinal nerve fiber layer thickness measurement by optical coherence tomography. We have previously demonstrated single photoreceptor cell imaging with differential interference contrast (DIC) microscopy. Herein, we successfully visualized single RGC using DIC microscopy. Since RGC layer is much less reflective than photoreceptor layer, various techniques including the control of light wavelength and bandwidth using a tunable band pass filter were adopted to reduce the chromatic aberration in z-axis for higher and clearer resolution. To verify that the imaged cells were the RGCs, the flat-mounted retina of Sprague-Dawley rat, in which the RGCs were retrogradely labeled with fluorescence, was observed by both fluorescence and DIC microscopies for direct comparison. We have confirmed that the cell images obtained by fluorescence microscopy were perfectly matched with cell images by DIC microscopy. As conclusion, we have visualized single RGC with DIC microscopy, and confirmed with fluorescence microscopy.

Super-Resolution Scanning Laser Microscopy Based on Virtually Structured Detection

PubMed Central

Zhi, Yanan; Wang, Benquan; Yao, Xincheng

2016-01-01

Light microscopy plays a key role in biological studies and medical diagnosis. The spatial resolution of conventional optical microscopes is limited to approximately half the wavelength of the illumination light as a result of the diffraction limit. Several approaches—including confocal microscopy, stimulated emission depletion microscopy, stochastic optical reconstruction microscopy, photoactivated localization microscopy, and structured illumination microscopy—have been established to achieve super-resolution imaging. However, none of these methods is suitable for the super-resolution ophthalmoscopy of retinal structures because of laser safety issues and inevitable eye movements. We recently experimentally validated virtually structured detection (VSD) as an alternative strategy to extend the diffraction limit. Without the complexity of structured illumination, VSD provides an easy, low-cost, and phase artifact–free strategy to achieve super-resolution in scanning laser microscopy. In this article we summarize the basic principles of the VSD method, review our demonstrated single-point and line-scan super-resolution systems, and discuss both technical challenges and the potential of VSD-based instrumentation for super-resolution ophthalmoscopy of the retina. PMID:27480461

Portable automated imaging in complex ceramics with a microwave interference scanning system

NASA Astrophysics Data System (ADS)

Goitia, Ryan M.; Schmidt, Karl F.; Little, Jack R.; Ellingson, William A.; Green, William; Franks, Lisa P.

2013-01-01

An improved portable microwave interferometry system has been automated to permit rapid examination of components with minimal operator attendance. Functionalities include stereo and multiplexed, frequency-modulated at multiple frequencies, producing layered volumetric images of complex ceramic structures. The technique has been used to image composite ceramic armor and ceramic matrix composite components, as well as other complex dielectric materials. The system utilizes Evisive Scan microwave interference scanning technique. Validation tests include artificial and in-service damage of ceramic armor, surrogates and ceramic matrix composite samples. Validation techniques include micro-focus x-ray and computed tomography imaging. The microwave interference scanning technique has demonstrated detection of cracks, interior laminar features and variations in material properties such as density. The image yields depth information through phase angle manipulation, and shows extent of feature and relative dielectric property information. It requires access to only one surface, and no coupling medium. Data are not affected by separation of layers of dielectric material, such as outer over-wrap. Test panels were provided by the US Army Research Laboratory, and the US Army Tank Automotive Research, Development and Engineering Center (TARDEC), who with the US Air Force Research Laboratory have supported this work.

Neuroanatomy from Mesoscopic to Nanoscopic Scales: An Improved Method for the Observation of Semithin Sections by High-Resolution Scanning Electron Microscopy

PubMed Central

Rodríguez, José-Rodrigo; Turégano-López, Marta; DeFelipe, Javier; Merchán-Pérez, Angel

2018-01-01

Semithin sections are commonly used to examine large areas of tissue with an optical microscope, in order to locate and trim the regions that will later be studied with the electron microscope. Ideally, the observation of semithin sections would be from mesoscopic to nanoscopic scales directly, instead of using light microscopy and then electron microscopy (EM). Here we propose a method that makes it possible to obtain high-resolution scanning EM images of large areas of the brain in the millimeter to nanometer range. Since our method is compatible with light microscopy, it is also feasible to generate hybrid light and electron microscopic maps. Additionally, the same tissue blocks that have been used to obtain semithin sections can later be used, if necessary, for transmission EM, or for focused ion beam milling and scanning electron microscopy (FIB-SEM). PMID:29568263

Neuroanatomy from Mesoscopic to Nanoscopic Scales: An Improved Method for the Observation of Semithin Sections by High-Resolution Scanning Electron Microscopy.

PubMed

Rodríguez, José-Rodrigo; Turégano-López, Marta; DeFelipe, Javier; Merchán-Pérez, Angel

2018-01-01

Semithin sections are commonly used to examine large areas of tissue with an optical microscope, in order to locate and trim the regions that will later be studied with the electron microscope. Ideally, the observation of semithin sections would be from mesoscopic to nanoscopic scales directly, instead of using light microscopy and then electron microscopy (EM). Here we propose a method that makes it possible to obtain high-resolution scanning EM images of large areas of the brain in the millimeter to nanometer range. Since our method is compatible with light microscopy, it is also feasible to generate hybrid light and electron microscopic maps. Additionally, the same tissue blocks that have been used to obtain semithin sections can later be used, if necessary, for transmission EM, or for focused ion beam milling and scanning electron microscopy (FIB-SEM).

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

PubMed

Peckys, Diana B; Bandmann, Vera; de Jonge, Niels

2014-01-01

Correlative fluorescence microscopy combined with scanning transmission electron microscopy (STEM) of cells fully immersed in liquid is a new methodology with many application areas. Proteins, in live cells immobilized on microchips, are labeled with fluorescent quantum dot nanoparticles. In this protocol, the epidermal growth factor receptor (EGFR) is labeled. The cells are fixed after a selected labeling time, for example, 5 min as needed to form EGFR dimers. The microchip with cells is then imaged with fluorescence microscopy. Thereafter, STEM can be accomplished in two ways. The microchip with the labeled cells and one microchip with a spacer are assembled into a special microfluidic device and imaged with dedicated high-voltage STEM. Alternatively, thin edges of cells can be studied with environmental scanning electron microscopy with a STEM detector, by placing a microchip with cells in a cooled wet environment. © 2014 Elsevier Inc. All rights reserved.

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

Roberson, G P; Logan, C M

We have estimated interference from external background radiation for a computed tomography (CT) scanner. Our intention is to estimate the interference that would be expected for the high-resolution SkyScan 1072 desk-top x-ray microtomography system. The SkyScan system uses a Microfocus x-ray source capable of a 10-{micro}m focal spot at a maximum current of 0.1 mA and a maximum energy of 130 kVp. All predictions made in this report assume using the x-ray source at the smallest spot size, maximum energy, and operating at the maximum current. Some of the systems basic geometry that is used for these estimates are: (1)more » Source-to-detector distance: 250 mm, (2) Minimum object-to-detector distance: 40 mm, and (3) Maximum object-to-detector distance: 230 mm. This is a first-order, rough estimate of the quantity of interference expected at the system detector caused by background radiation. The amount of interference is expressed by using the ratio of exposure expected at the detector of the CT system. The exposure values for the SkyScan system are determined by scaling the measured values of an x-ray source and the background radiation adjusting for the difference in source-to-detector distance and current. The x-ray source that was used for these measurements was not the SkyScan Microfocus x-ray tube. Measurements were made using an x-ray source that was operated at the same applied voltage but higher current for better statistics.« less

CONFOCAL LASER SCANNING MICROSCOPY OF RAT FOLLICLE DEVELOPMENT

EPA Science Inventory

This study used confocal laser scanning microscopy (CLSM) to study follicular development in millimeter pieces of rat ovary. To use this technology, it is essential to stain the tissue before laser excitation with the confocal microscope. Various fluorescent stains (Yo-Pro, Bo-Pr...

MAMMALIAN APOPTOSIS IN WHOLE NEONATAL OVARIES USING CONFOCAL LASER SCANNING MICROSCOPY

EPA Science Inventory

MAMMALIAN APOPTOSIS IN WHOLE NEONATAL OVARIES USING CONFOCAL LASER SCANNING MICROSCOPY

Robert M. Zucker Susan C. Jeffery and Sally D. Perreault

Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Prot...

CONFOCAL LASER SCANNING MICROSCOPY OF APOPTOSIS IN WHOLE MOUSE AND RAT OVARIES

EPA Science Inventory

Confocal Laser Scanning Microscopy of Apoptosis in Whole Mouse and Rat Ovaries. Robert M. Zucker Susan C. Jeffay and Sally D. Perreault Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research ...

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

EPA Science Inventory

Concerns about the environmental and public health effects of particulate matter (PM) have stimulated interest in analytical techniques capable of measuring the size and chemical composition of individual aerosol particles. Computer-controlled scanning electron microscopy (CCSE...

Atomic force microscopy of biological samples

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

Doktycz, Mitchel John

2010-01-01

The ability to evaluate structural-functional relationships in real time has allowed scanning probe microscopy (SPM) to assume a prominent role in post genomic biological research. In this mini-review, we highlight the development of imaging and ancillary techniques that have allowed SPM to permeate many key areas of contemporary research. We begin by examining the invention of the scanning tunneling microscope (STM) by Binnig and Rohrer in 1982 and discuss how it served to team biologists with physicists to integrate high-resolution microscopy into biological science. We point to the problems of imaging nonconductive biological samples with the STM and relate howmore » this led to the evolution of the atomic force microscope (AFM) developed by Binnig, Quate, and Gerber, in 1986. Commercialization in the late 1980s established SPM as a powerful research tool in the biological research community. Contact mode AFM imaging was soon complemented by the development of non-contact imaging modes. These non-contact modes eventually became the primary focus for further new applications including the development of fast scanning methods. The extreme sensitivity of the AFM cantilever was recognized and has been developed into applications for measuring forces required for indenting biological surfaces and breaking bonds between biomolecules. Further functional augmentation to the cantilever tip allowed development of new and emerging techniques including scanning ion-conductance microscopy (SICM), scanning electrochemical microscope (SECM), Kelvin force microscopy (KFM) and scanning near field ultrasonic holography (SNFUH).« less

Efficient Imaging and Real-Time Display of Scanning Ion Conductance Microscopy Based on Block Compressive Sensing

NASA Astrophysics Data System (ADS)

Li, Gongxin; Li, Peng; Wang, Yuechao; Wang, Wenxue; Xi, Ning; Liu, Lianqing

2014-07-01

Scanning Ion Conductance Microscopy (SICM) is one kind of Scanning Probe Microscopies (SPMs), and it is widely used in imaging soft samples for many distinctive advantages. However, the scanning speed of SICM is much slower than other SPMs. Compressive sensing (CS) could improve scanning speed tremendously by breaking through the Shannon sampling theorem, but it still requires too much time in image reconstruction. Block compressive sensing can be applied to SICM imaging to further reduce the reconstruction time of sparse signals, and it has another unique application that it can achieve the function of image real-time display in SICM imaging. In this article, a new method of dividing blocks and a new matrix arithmetic operation were proposed to build the block compressive sensing model, and several experiments were carried out to verify the superiority of block compressive sensing in reducing imaging time and real-time display in SICM imaging.

Interference techniques in fluorescence microscopy

NASA Astrophysics Data System (ADS)

Dogan, Mehmet

We developed a set of interference-based optical microscopy techniques to study biological structures through nanometer-scale axial localization of fluorescent biomarkers. Spectral self-interference fluorescence microscopy (SSFM) utilizes interference of direct and reflected waves emitted from fluorescent molecules in the vicinity of planar reflectors to reveal the axial position of the molecules. A comprehensive calculation algorithm based on Green's function formalism is presented to verify the validity of approximations used in a far-field approach that describes the emission of fluorescent markers near interfaces. Using the validated model, theoretical limits of axial localization were determined with emphasis given to numerical aperture (NA) dependence of localization uncertainty. SSFM was experimentally demonstrated in conformational analysis of nucleoproteins. In particular, interaction between surface-tethered 75-mer double strand DNA and integration host factor (IHF) protein was probed on Si-SiO2 substrates by determining the axial position of fluorescent labels attached to the free ends of DNA molecules. Despite its sub-nanometer precision axial localization capability, SSFM lacks high lateral resolution due to the low-NA requirement for planar reflectors. We developed a second technique, 4Pi-SSFM, which improves the lateral resolution of a conventional SSFM system by an order of magnitude while achieving nanometer-scale axial localization precision. Using two opposing high-NA objectives, fluorescence signal is interferometrically collected and spectral interference pattern is recorded. Axial position of emitters is found from analysis of the spectra. The 4Pi-SSFM technique was experimentally demonstrated by determining the surface profiles of fabricated glass surfaces and outer membranes of Shigella, a type of Gram-negative bacteria. A further discussion is presented to localize surface O antigen, which is an important oligosaccharide structure in the virulence mechanism of the Gram-negative bacteria, including E. coli and Shigella.

(Gene sequencing by scanning molecular exciton microscopy)

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

Not Available

1991-01-01

This report details progress made in setting up a laboratory for optical microscopy of genes. The apparatus including a fluorescence microscope, a scanning optical microscope, various spectrometers, and supporting computers is described. Results in developing photon and exciton tips, and in preparing samples are presented. (GHH)

Correlative imaging of biological tissues with apertureless scanning near-field optical microscopy and confocal laser scanning microscopy

PubMed Central

Stanciu, Stefan G.; Tranca, Denis E.; Hristu, Radu; Stanciu, George A.

2017-01-01

Apertureless scanning near-field optical microscopy (ASNOM) has attracted considerable interest over the past years as a result of its valuable contrast mechanisms and capabilities for optical resolutions in the nanoscale range. However, at this moment the intersections between ASNOM and the realm of bioimaging are scarce, mainly due to data interpretation difficulties linked to the limited body of work performed so far in this field and hence the reduced volume of supporting information. We propose an imaging approach that holds significant potential for alleviating this issue, consisting of correlative imaging of biological specimens using a multimodal system that incorporates ASNOM and confocal laser scanning microscopy (CLSM), which allows placing near-field data into a well understood context of anatomical relevance. We demonstrate this approach on zebrafish retinal tissue. The proposed method holds important implications for the in-depth understanding of biological items through the prism of ASNOM and CLSM data complementarity. PMID:29296474

Scanning ion conductance microscopy for visualizing the three-dimensional surface topography of cells and tissues.

PubMed

Nakajima, Masato; Mizutani, Yusuke; Iwata, Futoshi; Ushiki, Tatsuo

2018-01-01

Scanning ion conductance microscopy (SICM), which belongs to the family of scanning probe microscopy, regulates the tip-sample distance by monitoring the ion current through the use of an electrolyte-filled nanopipette as the probing tip. Thus, SICM enables "contact-free" imaging of cell surface topography in liquid conditions. In this paper, we applied hopping mode SICM for obtaining topographical images of convoluted tissue samples such as trachea and kidney in phosphate buffered saline. Some of the SICM images were compared with the images obtained by scanning electron microscopy (SEM) after drying the same samples. We showed that the imaging quality of hopping mode SICM was excellent enough for investigating the three-dimensional surface structure of the soft tissue samples. Thus, SICM is expected to be used for imaging a wide variety of cells and tissues - either fixed or alive- at high resolution under physiologically relevant liquid conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparison of macroscopic and microscopic (stereomicroscopy and scanning electron microscopy) features of bone lesions due to hatchet hacking trauma.

PubMed

Nogueira, Luísa; Quatrehomme, Gérald; Bertrand, Marie-France; Rallon, Christophe; Ceinos, Romain; du Jardin, Philippe; Adalian, Pascal; Alunni, Véronique

2017-03-01

This experimental study examined the lesions produced by a hatchet on human bones (tibiae). A total of 30 lesions were produced and examined macroscopically (naked eye) and by stereomicroscopy. 13 of them were also analyzed using scanning electron microscopy. The general shape of the lesion, both edges, both walls, the kerf floor and the extremities were described. The length and maximum width of the lesions were also recorded. The microscopic analysis of the lesions led to the description of a sharp-blunt mechanism. Specific criteria were identified (lateral pushing back, fragmentation of the upraising, fossa dug laterally to the edge and vertical striae) enabling the forensic expert to conclude that a hacking instrument was used. These criteria are easily identifiable using scanning electron microscopy, but can also be observed with stereomicroscopy. Overall, lateral pushing back and vertical striae visible using stereomicroscopy and scanning electron microscopy signal the use of a hacking tool.

Multi-MHz laser-scanning single-cell fluorescence microscopy by spatiotemporally encoded virtual source array

PubMed Central

Wu, Jianglai; Tang, Anson H. L.; Mok, Aaron T. Y.; Yan, Wenwei; Chan, Godfrey C. F.; Wong, Kenneth K. Y.; Tsia, Kevin K.

2017-01-01

Apart from the spatial resolution enhancement, scaling of temporal resolution, equivalently the imaging throughput, of fluorescence microscopy is of equal importance in advancing cell biology and clinical diagnostics. Yet, this attribute has mostly been overlooked because of the inherent speed limitation of existing imaging strategies. To address the challenge, we employ an all-optical laser-scanning mechanism, enabled by an array of reconfigurable spatiotemporally-encoded virtual sources, to demonstrate ultrafast fluorescence microscopy at line-scan rate as high as 8 MHz. We show that this technique enables high-throughput single-cell microfluidic fluorescence imaging at 75,000 cells/second and high-speed cellular 2D dynamical imaging at 3,000 frames per second, outperforming the state-of-the-art high-speed cameras and the gold-standard laser scanning strategies. Together with its wide compatibility to the existing imaging modalities, this technology could empower new forms of high-throughput and high-speed biological fluorescence microscopy that was once challenged. PMID:28966855

Demonstration of bacterial biofilms in culture-negative silicone stent and jones tube.

PubMed

Parsa, Kami; Schaudinn, Christoph; Gorur, Amita; Sedghizadeh, Parish P; Johnson, Thomas; Tse, David T; Costerton, John W

2010-01-01

To demonstrate the presence of bacterial biofilms on a dacryocystorhinostomy silicone stent and a Jones tube. One dacryocystorhinostomy silicone stent and one Jones tube were removed from 2 patients who presented with an infection of their respective nasolacrimal system. Cultures were obtained, and the implants were processed for scanning electron microscopy and confocal laser scanning microscopy, advanced microscopic methods that are applicable for detection of uncultivable biofilm organisms. Routine bacterial cultures revealed no growth, but bacterial biofilms on outer and inner surfaces of both implants were confirmed by advanced microscopic techniques. To the authors' knowledge, this is the first article that documents the presence of biofilms on a Crawford stent or a Jones tube on patients who presented with infections involving the nasolacrimal system. Although initial cultures revealed absence of any bacterial growth, confocal laser scanning microscopy and scanning electron microscopy documented bacterial colonization. Clinicians should consider the role of biofilms and the limitation of our standard culturing techniques while treating patients with device- or implant-related infections.

Atmospheric scanning electron microscope observes cells and tissues in open medium through silicon nitride film.

PubMed

Nishiyama, Hidetoshi; Suga, Mitsuo; Ogura, Toshihiko; Maruyama, Yuusuke; Koizumi, Mitsuru; Mio, Kazuhiro; Kitamura, Shinichi; Sato, Chikara

2010-03-01

Direct observation of subcellular structures and their characterization is essential for understanding their physiological functions. To observe them in open environment, we have developed an inverted scanning electron microscope with a detachable, open-culture dish, capable of 8 nm resolution, and combined with a fluorescence microscope quasi-simultaneously observing the same area from the top. For scanning electron microscopy from the bottom, a silicon nitride film window in the base of the dish maintains a vacuum between electron gun and open sample dish while allowing electrons to pass through. Electrons are backscattered from the sample and captured by a detector under the dish. Cells cultured on the open dish can be externally manipulated under optical microscopy, fixed, and observed using scanning electron microscopy. Once fine structures have been revealed by scanning electron microscopy, their component proteins may be identified by comparison with separately prepared fluorescence-labeled optical microscopic images of the candidate proteins, with their heavy-metal-labeled or stained ASEM images. Furthermore, cell nuclei in a tissue block stained with platinum-blue were successfully observed without thin-sectioning, which suggests the applicability of this inverted scanning electron microscope to cancer diagnosis. This microscope visualizes mesoscopic-scale structures, and is also applicable to non-bioscience fields including polymer chemistry. (c) 2010 Elsevier Inc. All rights reserved.

Large area scanning probe microscope in ultra-high vacuum demonstrated for electrostatic force measurements on high-voltage devices.

PubMed

Gysin, Urs; Glatzel, Thilo; Schmölzer, Thomas; Schöner, Adolf; Reshanov, Sergey; Bartolf, Holger; Meyer, Ernst

2015-01-01

The resolution in electrostatic force microscopy (EFM), a descendant of atomic force microscopy (AFM), has reached nanometre dimensions, necessary to investigate integrated circuits in modern electronic devices. However, the characterization of conducting or semiconducting power devices with EFM methods requires an accurate and reliable technique from the nanometre up to the micrometre scale. For high force sensitivity it is indispensable to operate the microscope under high to ultra-high vacuum (UHV) conditions to suppress viscous damping of the sensor. Furthermore, UHV environment allows for the analysis of clean surfaces under controlled environmental conditions. Because of these requirements we built a large area scanning probe microscope operating under UHV conditions at room temperature allowing to perform various electrical measurements, such as Kelvin probe force microscopy, scanning capacitance force microscopy, scanning spreading resistance microscopy, and also electrostatic force microscopy at higher harmonics. The instrument incorporates beside a standard beam deflection detection system a closed loop scanner with a scan range of 100 μm in lateral and 25 μm in vertical direction as well as an additional fibre optics. This enables the illumination of the tip-sample interface for optically excited measurements such as local surface photo voltage detection. We present Kelvin probe force microscopy (KPFM) measurements before and after sputtering of a copper alloy with chromium grains used as electrical contact surface in ultra-high power switches. In addition, we discuss KPFM measurements on cross sections of cleaved silicon carbide structures: a calibration layer sample and a power rectifier. To demonstrate the benefit of surface photo voltage measurements, we analysed the contact potential difference of a silicon carbide p/n-junction under illumination.

Nanocapsules: The Weapons for Novel Drug Delivery Systems

PubMed Central

Kothamasu, Pavankumar; Kanumur, Hemanth; Ravur, Niranjan; Maddu, Chiranjeevi; Parasuramrajam, Radhika; Thangavel, Sivakumar

2012-01-01

Introduction Nanocapsules, existing in miniscule size, range from 10 nm to 1000 nm. They consist of a liquid/solid core in which the drug is placed into a cavity, which is surrounded by a distinctive polymer membrane made up of natural or synthetic polymers. They have attracted great interest, because of the protective coating, which are usually pyrophoric and easily oxidized and delay the release of active ingredients. Methods Various technical approaches are utilized for obtaining the nanocapsules; however, the methods of interfacial polymerization for monomer and the nano-deposition for preformed polymer are chiefly preferred. Most important characteristics in their preparation is particle size and size distribution which can be evaluated by using various techniques like X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolu¬tion transmission electron microscopy, X-ray photoelectron spectroscopy, superconducting quantum interference device, multi angle laser light scattering and other spectroscopic techniques. Results Nanocapsules possessing extremely high reproducibility have a broad range of life science applications. They may be applied in agrochemicals, genetic engineering, cosmetics, cleansing products, wastewater treatments, adhesive component applications, strategic delivery of the drug in tumors, nanocapsule bandages to fight infec¬tion, in radiotherapy and as liposomal nanocapsules in food science and agriculture. In addition, they can act as self-healing materials. Conclusion The enhanced delivery of bio¬active molecules through the targeted delivery by means of a nanocapsule opens numerous challenges and opportunities for the research and future development of novel improved therapies. PMID:23678444

Transformation and motility of human platelets: details of the shape change and release reaction observed by optical and electron microscopy

PubMed Central

1979-01-01

Blood platelets from 10 normal human subjects have been examined with a sensitive differential interference contrast (DIC) microscope. The entire transformation process during adhesion to glass is clearly visible and has been recorded cinematographically, including the disk to sphere change of shape, the formation of sessile protuberances, the extension and retraction of pseudopodia, and the spreading, ruffling, and occasional regression of the hyalomere. The exocytosis of intact dense bodies can be observed either by DIC microscopy, or by epifluorescence microscopy in platelets stained with mepacrine. Details of fluorescent flashes indicate that the dense bodies usually release their contents extracellularly, may do so intracytoplasmically under the influence of strong, short wavelength light on some preparations of mepacrine-stained platelets. The release of one or more dense bodies leaves a crater of variable size on the upper surface of the granulomere. Such craters represent the surface component of the open canalicular system and their formation and disappearance can be directly observed. Because these techniques permit quantitation of several parameters of motility which are not readily observable by other techniques, it is suggested that high extinction DIC microscope examination may become a rapid and useful method of studying congenital and acquired platelet disorders. Many features of platelet transformation have been confirmed and extended by scanning electron micrographs. These can in turn be interpreted by reference to time- lapse films of living platelets. PMID:511936

Nanocapsules: the weapons for novel drug delivery systems.

PubMed

Kothamasu, Pavankumar; Kanumur, Hemanth; Ravur, Niranjan; Maddu, Chiranjeevi; Parasuramrajam, Radhika; Thangavel, Sivakumar

2012-01-01

Nanocapsules, existing in miniscule size, range from 10 nm to 1000 nm. They consist of a liquid/solid core in which the drug is placed into a cavity, which is surrounded by a distinctive polymer membrane made up of natural or synthetic polymers. They have attracted great interest, because of the protective coating, which are usually pyrophoric and easily oxidized and delay the release of active ingredients. Various technical approaches are utilized for obtaining the nanocapsules; however, the methods of interfacial polymerization for monomer and the nano-deposition for preformed polymer are chiefly preferred. Most important characteristics in their preparation is particle size and size distribution which can be evaluated by using various techniques like X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolu¬tion transmission electron microscopy, X-ray photoelectron spectroscopy, superconducting quantum interference device, multi angle laser light scattering and other spectroscopic techniques. Nanocapsules possessing extremely high reproducibility have a broad range of life science applications. They may be applied in agrochemicals, genetic engineering, cosmetics, cleansing products, wastewater treatments, adhesive component applications, strategic delivery of the drug in tumors, nanocapsule bandages to fight infec¬tion, in radiotherapy and as liposomal nanocapsules in food science and agriculture. In addition, they can act as self-healing materials. The enhanced delivery of bio¬active molecules through the targeted delivery by means of a nanocapsule opens numerous challenges and opportunities for the research and future development of novel improved therapies.

Direct laser interference patterning of magnetic thin films

NASA Astrophysics Data System (ADS)

Aktag, Aliekber

Recently, patterned magnetic thin films have attracted much attention for a variety of applications such as high density magnetic recording, magnetoresistive sensing, and magnetic random access memories. In the case of magnetic recording, one scheme calls for the films to be patterned into single domain "dots", where every dot represents a thermally stable bit. In this thesis, we extended a technique called direct laser interference patterning (DLIP), originally developed by Polushkin and co-workers, to pattern and locally modify the materials properties of magnetic thin films. In this technique, a high-intensity Nd:YAG pulse laser beam was split into two, three, or four beams, which are then recombined to interfere on a sample surface. The interference intensity maxima can modify the local materials properties of the film through local "annealing" or, more drastically, by ablation. We carried out some preliminary investigations of the DLIP process in several films including co-sputtered Co-C, amorphous Dy/Co:SiO2 multilayers, and Co/SiO2 multilayers in order to refine our techniques. We successfully produced regular arrays of lines, dots, or antidots formed by ablation of the thin film. The preliminary studies also showed that, in the regime of more modest pulse energies, it is possible to modify the magnetic properties of the films without noticeably changing the film topography. We then prepared perpendicular magnetic anisotropy Co/Pt multilayers with a SiO x passivation layer and applied DLIP at fairly modest intensities to pattern the film. We then studied the structural and magnetic changes that occurred in some detail. X-ray diffraction scans showed the Co/Pt:SiO x multilayer films to be nanocrystalline before and after patterning. Atomic force microscopy images showed no evidence for topographic changes of the Co/Pt:SiOx during patterning. In contrast, magnetic force microscopy showed regular periodic dot arrays, indicating that the local magnetic properties were significantly affected by the patterning process. Alternating-gradient-force magnetometry and magneto-optic measurements also showed that the magnetic properties were markedly changed by the DLIP process. Our results offer strong evidence that local heating causes the moments to change from perpendicular to in-plane, with the consequent formation of an "anisotropy lattice": dots of in-plane magnetization within a matrix of perpendicular magnetization. We also carried out some optical interference calculations to predict the light intensity distributions for two, three, and four interfering beams of light. We found that the patterns could be controlled by varying the angles of incidence, the polarizations of the beams, and the wavelength and intensity of the beams, and that a wide variety of patterns are possible. The predicted patterns were in quite good agreement with those observed experimentally.

Menadione metabolism to thiodione in hepatoblastoma by scanning electrochemical microscopy

PubMed Central

Mauzeroll, Janine; Bard, Allen J.; Owhadian, Omeed; Monks, Terrence J.

2004-01-01

The cytotoxicity of menadione on hepatocytes was studied by using the substrate generation/tip collection mode of scanning electrochemical microscopy by exposing the cells to menadione and detecting the menadione-S-glutathione conjugate (thiodione) that is formed during the cellular detoxication process and is exported from the cell by an ATP-dependent pump. This efflux was electrochemically detected and allowed scanning electrochemical microscopy monitoring and imaging of single cells and groups of highly confluent live cells. Based on a constant flux model, ≈6 × 106 molecules of thiodione per cell per second are exported from monolayer cultures of Hep G2 cells. PMID:15601769

Enhanced Axial Resolution of Wide-Field Two-Photon Excitation Microscopy by Line Scanning Using a Digital Micromirror Device.

PubMed

Park, Jong Kang; Rowlands, Christopher J; So, Peter T C

2017-01-01

Temporal focusing multiphoton microscopy is a technique for performing highly parallelized multiphoton microscopy while still maintaining depth discrimination. While the conventional wide-field configuration for temporal focusing suffers from sub-optimal axial resolution, line scanning temporal focusing, implemented here using a digital micromirror device (DMD), can provide substantial improvement. The DMD-based line scanning temporal focusing technique dynamically trades off the degree of parallelization, and hence imaging speed, for axial resolution, allowing performance parameters to be adapted to the experimental requirements. We demonstrate this new instrument in calibration specimens and in biological specimens, including a mouse kidney slice.

Enhanced Axial Resolution of Wide-Field Two-Photon Excitation Microscopy by Line Scanning Using a Digital Micromirror Device

PubMed Central

Park, Jong Kang; Rowlands, Christopher J.; So, Peter T. C.

2017-01-01

Temporal focusing multiphoton microscopy is a technique for performing highly parallelized multiphoton microscopy while still maintaining depth discrimination. While the conventional wide-field configuration for temporal focusing suffers from sub-optimal axial resolution, line scanning temporal focusing, implemented here using a digital micromirror device (DMD), can provide substantial improvement. The DMD-based line scanning temporal focusing technique dynamically trades off the degree of parallelization, and hence imaging speed, for axial resolution, allowing performance parameters to be adapted to the experimental requirements. We demonstrate this new instrument in calibration specimens and in biological specimens, including a mouse kidney slice. PMID:29387484

Laser Window Studies

DTIC Science & Technology

1975-08-01

CONT’D) Nuniln 21 23 24 26 20 30 31 34 3 5 ■A 6 37 39 Title Page Nomarski Fnterference Microscopy of Surface of 61 Film Substrates Tes...Potassium Chloride Surfaces 83 Anomalous Indentation Behavior 85 Indentations in As.;S Films - Nomarski Microscopy 92 Indentations in As9S...minimum load required to remove the film. Nomarski interference microscopy was used to inspect the scratched surfaces. The method was found to be less

Keggin-type polyoxometalate nanosheets: synthesis and characterization via scanning transmission electron microscopy.

PubMed

Hiyoshi, Norihito

2018-05-17

Polyoxometalate nanosheets were synthesized at the gas/liquid interface of an aqueous solution of Keggin-type silicotungstic acid, cesium chloride, and n-octylamine. The structure of the nanosheets was elucidated via aberration-corrected scanning transmission electron microscopy at the atomic and molecular levels.

Scanning electron microscopy analysis of corrosion degradation on tinplate substrates.

PubMed

Zumelzu, E; Cabezas, C; Vera, A

2003-01-01

The degradation of electrolytic tinplate used in food containers was analysed and evaluated, using scanning electron microscopy and electrochemical measurements of microcorrosion and ion dissolution by atomic absorption to prevent food contamination caused by metal traces and to increase the durability of such tinplates.

Confocal laser scanning microscopy of apoptosis in organogenesis-stage mouse embryos

EPA Science Inventory

Confocal laser scanning microscopy combined with a vital stain has been used to study apoptosis in organogenesis-stage mouse embryos. In order to achieve optical sectioning through embryos, it was necessary to use low power objectives and to prepare the sample appropriately. Mous...

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...

Ultra-thin resin embedding method for scanning electron microscopy of individual cells on high and low aspect ratio 3D nanostructures.

PubMed

Belu, A; Schnitker, J; Bertazzo, S; Neumann, E; Mayer, D; Offenhäusser, A; Santoro, F

2016-07-01

The preparation of biological cells for either scanning or transmission electron microscopy requires a complex process of fixation, dehydration and drying. Critical point drying is commonly used for samples investigated with a scanning electron beam, whereas resin-infiltration is typically used for transmission electron microscopy. Critical point drying may cause cracks at the cellular surface and a sponge-like morphology of nondistinguishable intracellular compartments. Resin-infiltrated biological samples result in a solid block of resin, which can be further processed by mechanical sectioning, however that does not allow a top view examination of small cell-cell and cell-surface contacts. Here, we propose a method for removing resin excess on biological samples before effective polymerization. In this way the cells result to be embedded in an ultra-thin layer of epoxy resin. This novel method highlights in contrast to standard methods the imaging of individual cells not only on nanostructured planar surfaces but also on topologically challenging substrates with high aspect ratio three-dimensional features by scanning electron microscopy. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

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.

Three-dimensional nanoscale imaging by plasmonic Brownian microscopy

NASA Astrophysics Data System (ADS)

Labno, Anna; Gladden, Christopher; Kim, Jeongmin; Lu, Dylan; Yin, Xiaobo; Wang, Yuan; Liu, Zhaowei; Zhang, Xiang

2017-12-01

Three-dimensional (3D) imaging at the nanoscale is a key to understanding of nanomaterials and complex systems. While scanning probe microscopy (SPM) has been the workhorse of nanoscale metrology, its slow scanning speed by a single probe tip can limit the application of SPM to wide-field imaging of 3D complex nanostructures. Both electron microscopy and optical tomography allow 3D imaging, but are limited to the use in vacuum environment due to electron scattering and to optical resolution in micron scales, respectively. Here we demonstrate plasmonic Brownian microscopy (PBM) as a way to improve the imaging speed of SPM. Unlike photonic force microscopy where a single trapped particle is used for a serial scanning, PBM utilizes a massive number of plasmonic nanoparticles (NPs) under Brownian diffusion in solution to scan in parallel around the unlabeled sample object. The motion of NPs under an evanescent field is three-dimensionally localized to reconstruct the super-resolution topology of 3D dielectric objects. Our method allows high throughput imaging of complex 3D structures over a large field of view, even with internal structures such as cavities that cannot be accessed by conventional mechanical tips in SPM.

Self-interference 3D super-resolution microscopy for deep tissue investigations.

PubMed

Bon, Pierre; Linarès-Loyez, Jeanne; Feyeux, Maxime; Alessandri, Kevin; Lounis, Brahim; Nassoy, Pierre; Cognet, Laurent

2018-06-01

Fluorescence localization microscopy has achieved near-molecular resolution capable of revealing ultra-structures, with a broad range of applications, especially in cellular biology. However, it remains challenging to attain such resolution in three dimensions and inside biological tissues beyond the first cell layer. Here we introduce SELFI, a framework for 3D single-molecule localization within multicellular specimens and tissues. The approach relies on self-interference generated within the microscope's point spread function (PSF) to simultaneously encode equiphase and intensity fluorescence signals, which together provide the 3D position of an emitter. We combined SELFI with conventional localization microscopy to visualize F-actin 3D filament networks and reveal the spatial distribution of the transcription factor OCT4 in human induced pluripotent stem cells at depths up to 50 µm inside uncleared tissue spheroids. SELFI paves the way to nanoscale investigations of native cellular processes in intact tissues.

Non-invasive and high-sensitivity scanning detection of magnetic nanoparticles in animals using high-Tc scanning superconducting-quantum-interference-device biosusceptometry.

PubMed

Chieh, J J; Hong, C Y

2011-08-01

Although magnetic nanoparticles (MNPs) have been widely applied to animals in biomedicine, MNPs within animals should be examined in real time, in vivo, and without bio-damaged possibility to evaluate whether the bio-function of MNPs is valid or to further controls the biomedicinal process because of accompanying complex problems such as MNPs distribution and MNPs biodegradation. The non-invasive and high-sensitivity scanning detection of MNPs in animals using ac susceptometry based on a high-T(c) superconducting quantum interference device (SQUID) is presented. The non-invasive results and biopsy results show good agreement, and two gold-standard biomedicine methods, Prussian blue stain and inductively coupled plasma, prove the magnetic results. This confirms that the future clinical diagnosis of bio-functional MNPs could be operated by using scanning SQUID biosusceptometry as conveniently as an ultrasonic probe.

Synthesis and characterization of microparticles based on poly-methacrylic acid with glucose oxidase for biosensor applications.

PubMed

Hervás Pérez, J P; López-Ruiz, B; López-Cabarcos, E

2016-01-01

In the line of the applicability of biocompatible monomers pH and temperature dependent, we assayed poly-methacrylic acid (p-MAA) microparticles as immobilization system in the design of enzymatic biosensors. Glucose oxidase was used as enzyme model for the study of microparticles as immobilization matrices and as biological material in the performance of glucose biosensors. The enzyme immobilization method was optimized by investigating the influence of monomer concentration and cross-linker content (N',N'-methylenebisacrylamide), used in the preparation of the microparticles in the response of the biosensors. The kinetics of the polymerization and the effects of the temperature were studied, also the conversion of the polymerization was determinates by a weight method. The structure of the obtained p-MAA microparticles were studied through scanning electron microscopy (SEM) and differential scanning microscopy (DSC). The particle size measurements were performed with a Galai-Cis 1 particle analyzer system. Furthermore, the influence of the swelling behavior of hydrogel matrix as a function of pH and temperature were studied. Analytical properties such as sensitivity, linear range, response time and detection limit were studied for the glucose biosensors. The sensitivity for glucose detection obtained with poly-methacrylic acid (p-MAA) microparticles was 11.98mAM(-1)cm(-2) and 10μM of detection limit. A Nafion® layer was used to eliminate common interferents of the human serum such as uric and ascorbic acids. The biosensors were used to determine glucose in human serum samples with satisfactory results. When stored in a frozen phosphate buffer solution (pH 6.0) at -4°C, the useful lifetime of all biosensors was at least 550 days. Copyright © 2015 Elsevier B.V. All rights reserved.

Enhancement of the Microscopy Facilities at the NSLS X1A Beamline

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

Jacobson, Chris

1999-08-31

As originally proposed, the authors constructed a new Scanning Transmission X-ray Microscope, STXM IV. The design and construction was led by Chris Jacobsen, and involved graduate students Michael Feser, Mary Carlucci-Dayton and Tobias Beetz. This microscope has the following new features: It has a new and improved high resolution scanning stage that should make it possible to perform higher resolution imaging without distortions. Preliminary results indicate that the stage performs as designed. It has an enclosure that can be evacuated and backfilled with helium. This makes it possible to perform imaging in the neighborhood of the nitrogen and oxygen edgesmore » without interference from residual air. It has a motorized detector stage for easy interchange of detectors and alignment microscope. We expect to use this to align the new segmented detector which makes it possible to perform brightfield and dark field microscopy simultaneously, and to record images in differential phase contrast as well. The microscope is located upstream of cryoSTXM, the instrument we use to examine specimens in a frozen hydrated state. The design of STXM IV is such that it makes it quick and easy to switch between STXM IV and cryo-STXM operations and vice versa. IEEE488 based control electronics provides multiple channels of data collection. The microscope is run from a LINUX PC with all new software, developed in-house. The stages for the zone plate and the order sorting aperture (OSA) have kinematic mounts. This way different sets of zone plates (optimized for different wavelengths and working distances) can be exchanged without the need for complete realignment of the instrument. The enclosure can be used as a glove-box, making it possible to examine specimens which require anaerobic handling.« less

Effects of fluoride and epigallocatechin gallate on soft-drink-induced dental erosion of enamel and root dentin.

PubMed

Wang, Yin-Lin; Chang, Hao-Hueng; Chiang, Yu-Chih; Lu, Yu-Chen; Lin, Chun-Pin

2018-04-01

Fluoride and epigallocatechin gallate (EGCG) have been proven to prevent dental caries. The purpose of this study was to evaluate the effects of fluoride and EGCG on soft-drink-induced dental erosion in vitro. Forty enamel and dentin specimens were prepared from extracted human teeth. The specimens were divided into 4 groups and treated separately with distilled water (as control), 0.5 M sodium fluoride (NF), 400 μM EGCG (EG), and a solution containing 0.5 M NaF and 400 μM EGCG (FG). Cyclic erosive treatment was performed according to the experimental procedures. The specimens were analyzed using laser scanning confocal microscopy, scanning electron microscopy, and a microhardness tester. The data were analyzed using ANOVA and Bonferroni's post hoc test. The significance level was set at 5%. The amount of substance loss was lower in the NF and EG groups than in the control group (p < 0.05). The erosion-caused substance loss was more pronounced in the dentin than in the enamel specimens. Surface microhardness loss was lower in the NF and EG groups than in the control group (p < 0.05). The diameter of the dentinal tubule was wider in the control group than in the NF and EG groups (p < 0.05). No combined effects were observed in the FG group. Both fluoride and EGCG are effective in preventing soft-drink-induced erosion compared with the control group. Fluoride and EGCG may interfere with each other. The mechanisms of the anti-erosive effect need to be explored in the future. Copyright © 2018. Published by Elsevier B.V.

Effects of G6PD activity inhibition on the viability, ROS generation and mechanical properties of cervical cancer cells.

PubMed

Fang, Zishui; Jiang, Chengrui; Feng, Yi; Chen, Rixin; Lin, Xiaoying; Zhang, Zhiqiang; Han, Luhao; Chen, Xiaodan; Li, Hongyi; Guo, Yibin; Jiang, Weiying

2016-09-01

Glucose-6-phosphate dehydrogenase (G6PD) deficiency has been revealed to be involved in the efficacy to anti-cancer therapy but the mechanism remains unclear. We aimed to investigate the anti-cancer mechanism of G6PD deficiency. In our study, dehydroepiandrosterone (DHEA) and shRNA technology were used for inhibiting the activity of G6PD of cervical cancer cells. Peak Force QNM Atomic Force Microscopy was used to assess the changes of topography and biomechanical properties of cells and detect the effects on living cells in a natural aqueous environment. Flow cytometry was used to detect the apoptosis and reactive oxygen species (ROS) generation. Scanning electron microscopy was used to observe cell morphology. Moreover, a laser scanning confocal microscope was used to observe the alterations in cytoskeleton to explore the involved mechanism. When G6PD was inhibited by DHEA or RNA interference, the abnormal Young's modulus and increased roughness of cell membrane were observed in HeLa cells, as well as the idioblasts. Simultaneously, G6PD deficiency resulted in decreased HeLa cells migration and proliferation ability but increased ROS generation inducing apoptosis. What's more, the inhibition of G6PD activity caused the disorganization of microfilaments and microtubules of cytoskeletons and cell shrinkage. Our results indicated the anti-cervix cancer mechanism of G6PD deficiency may be involved with the decreased cancer cells migration and proliferation ability as a result of abnormal reorganization of cell cytoskeleton and abnormal biomechanical properties caused by the increased ROS. Suppression of G6PD may be a promising strategy in developing novel therapeutic methods for cervical cancer. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

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

2015-08-01

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

Liquid scanning transmission electron microscopy: imaging protein complexes in their native environment in whole eukaryotic cells.

PubMed

Peckys, Diana B; de Jonge, Niels

2014-04-01

Scanning transmission electron microscopy (STEM) of specimens in liquid, so-called Liquid STEM, is capable of imaging the individual subunits of macromolecular complexes in whole eukaryotic cells in liquid. This paper discusses this new microscopy modality within the context of state-of-the-art microscopy of cells. The principle of operation and equations for the resolution are described. The obtained images are different from those acquired with standard transmission electron microscopy showing the cellular ultrastructure. Instead, contrast is obtained on specific labels. Images can be recorded in two ways, either via STEM at 200 keV electron beam energy using a microfluidic chamber enclosing the cells, or via environmental scanning electron microscopy at 30 keV of cells in a wet environment. The first series of experiments involved the epidermal growth factor receptor labeled with gold nanoparticles. The labels were imaged in whole fixed cells with nanometer resolution. Since the cells can be kept alive in the microfluidic chamber, it is also feasible to detect the labels in unfixed, live cells. The rapid sample preparation and imaging allows studies of multiple whole cells.

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

PubMed Central

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

2015-01-01

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

Artifact mitigation of ptychography integrated with on-the-fly scanning probe microscopy

DOE PAGES

Huang, Xiaojing; Yan, Hanfei; Ge, Mingyuan; ...

2017-07-11

In this paper, we report our experiences with conducting ptychography simultaneously with the X-ray fluorescence measurement using the on-the-fly mode for efficient multi-modality imaging. We demonstrate that the periodic artifact inherent to the raster scan pattern can be mitigated using a sufficiently fine scan step size to provide an overlap ratio of >70%. This allows us to obtain transmitted phase contrast images with enhanced spatial resolution from ptychography while maintaining the fluorescence imaging with continuous-motion scans on pixelated grids. Lastly, this capability will greatly improve the competence and throughput of scanning probe X-ray microscopy.

Use of scanning electron microscopy and microanalysis to determine chloride content of concrete and raw materials.

DOT National Transportation Integrated Search

2013-02-01

Standard sample sets of cement and mortar formulations with known levels of Cl as well as concrete samples subject to Cl diffusion were all prepared for and analyzed with scanning electron microscopy (SEM) and electron microprobe (EPMA). Using x-ray ...

USE OF MULTIPHOTON LASER SCANNING MICROSCOPY TO IMAGE BENZO[A]PYRENE AND METABOLITES IN FISH EGGS

EPA Science Inventory

Multiphoton laser scanning microscopy (MPLSM) is a promising tool to study the tissue distribution of environmental chemical contaminants during fish early life stages. One such chemical for which this is possible is benzo[a]pyrene (BaP), a polycyclic aromatic hydrocarbon that a...

THE INTEGRATED USE OF COMPUTATIONAL CHEMISTRY, SCANNING PROBE MICROSCOPY, AND VIRTUAL REALITY TO PREDICT THE CHEMICAL REACTIVITY OF ENVIRONMENTAL SURFACES

EPA Science Inventory

In the last decade three new techniques scanning probe microscopy (SPM), virtual reality (YR) and computational chemistry ave emerged with the combined capability of a priori predicting the chemically reactivity of environmental surfaces. Computational chemistry provides the cap...

PREDICTING CHEMICAL REACTIVITY OF HUMIC SUBSTANCES FOR MINERALS AND XENOBIOTICS: USE OF COMPUTATIONAL CHEMISTRY, SCANNING PROBE MICROSCOPY AND VIRTUAL REALITY

EPA Science Inventory

In this chapter we review the literature on scanning probe microscopy (SPM), virtual reality (VR), and computational chemistry and our earlier work dealing with modeling lignin, lignin-carbohydrate complexes (LCC), humic substances (HSs) and non-bonded organo-mineral interactions...

Writing silica structures in liquid with scanning transmission electron microscopy.

PubMed

van de Put, Marcel W P; Carcouët, Camille C M C; Bomans, Paul H H; Friedrich, Heiner; de Jonge, Niels; Sommerdijk, Nico A J M

2015-02-04

Silica nanoparticles are imaged in solution with scanning transmission electron microscopy (STEM) using a liquid cell with silicon nitride (SiN) membrane windows. The STEM images reveal that silica structures are deposited in well-defined patches on the upper SiN membranes upon electron beam irradiation. The thickness of the deposits is linear with the applied electron dose. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) demonstrate that the deposited patches are a result of the merging of the original 20 nm-diameter nanoparticles, and that the related surface roughness depends on the electron dose rate used. Using this approach, sub-micrometer scale structures are written on the SiN in liquid by controlling the electron exposure as function of the lateral position. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Resolution enhancement in a double-helix phase engineered scanning microscope (RESCH microscope) (Presentation Recording)

NASA Astrophysics Data System (ADS)

Jesacher, Alexander; Ritsch-Marte, Monika; Piestun, Rafael

2015-08-01

Recently we introduced RESCH microscopy [1] - a scanning microscope that allows slightly refocusing the sample after the acquisition has been performed, solely by performing appropriate data post-processing. The microscope features a double-helix phase-engineered emission point spread function in combination with camera-based detection. Based on the principle of transverse resolution enhancement in Image Scanning Microscopy [2,3], we demonstrate similar resolution improvement in RESCH. Furthermore, we outline a pathway for how the collected 3D sample information can be used to construct sharper optical sections. [1] A. Jesacher, M. Ritsch-Marte and R. Piestun, accepted for Optica. [2] C.J.R. Sheppard, "Super-resolution in Confocal imaging," Optik, 80, 53-54 (1988). [3] C.B. Müller and J. Enderlein "Image Scanning Microscopy," Phys. Rev. Lett. 104, 198101 (2010).

Transfer doping of single isolated nanodiamonds, studied by scanning probe microscopy techniques.

PubMed

Bolker, Asaf; Saguy, Cecile; Kalish, Rafi

2014-09-26

The transfer doping of diamond surfaces has been applied in various novel two-dimensional electronic devices. Its extension to nanodiamonds (ND) is essential for ND-based applications in many fields. In particular, understanding the influence of the crystallite size on transfer doping is desirable. Here, we report the results of a detailed study of the electronic energetic band structure of single, isolated transfer-doped nanodiamonds with nanometric resolution using a combination of scanning tunneling spectroscopy and Kelvin force microscopy measurements. The results show how the band gap, the valence band maximum, the electron affinity and the work function all depend on the ND's size and nanoparticle surface properties. The present analysis, which combines information from both scanning tunneling spectroscopy and Kelvin force microscopy, should be applicable to any nanoparticle or surface that can be measured with scanning probe techniques.

Photonic crystal fibre enables short-wavelength two-photon laser scanning fluorescence microscopy with fura-2

NASA Astrophysics Data System (ADS)

McConnell, Gail; Riis, Erling

2004-10-01

We report on a novel and compact reliable laser source capable of short-wavelength two-photon laser scanning fluorescence microscopy based on soliton self-frequency shift effects in photonic crystal fibre. We demonstrate the function of the system by performing two-photon microscopy of smooth muscle cells and cardiac myocytes from the rat pulmonary vein and Chinese hamster ovary cells loaded with the fluorescent calcium indicator fura-2/AM.

Scanning Tunneling Microscopy, Atomic Force Microscopy, and Related Techniques

DTIC Science & Technology

1992-02-26

92. (B47) Fujui, T.; Suzuki, MA.; Miyashita, MA.; Yamaguchi, M.; Onuki , T.; Nakamura, H .; Matsubara, T.; Yamada, H .; Nakayamia, K. J. Vac. Sd...and seven deflection detection systems (A 15). (Al) Binnig, G.; Rohrer, H .; Gerber, Ch.; Weibel, E. Phys. Rev. Lett. 1982, 49, 57. (A2) Ray, M.A...J. J. Vac Sci. Technol. A 1ඣ, 9, 44-50. (AS) Scanning Tunneling Microscopy and Related Methods; Behm, RJ., Garcia, N., Rohrer, H ., Eds.; NATO ASI

Optical and Calorimetric Studies of Cholesterol-Rich Filamentous, Helical Ribbon and Crystal Microstructures

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

Miroshnikova, Y. A.; Elsenbeck, M.; Zastavker, Y. V.

2009-04-19

Formation of biological self-assemblies at all scales is a focus of studies in fields ranging from biology to physics to biomimetics. Understanding the physico-chemical properties of these self-assemblies may lead to the design of bio-inspired structures and technological applications. Here we examine self-assembled filamentous, helical ribbon, and crystal microstructures formed in chemically defined lipid concentrate (CDLC), a model system for cholesterol crystallization in gallbladder bile. CDLC consists of cholesterol, bilayer-forming amphiphiles, micelle-forming amphiphiles, and water. Phase contrast and differential interference contrast (DIC) microscopy indicate the presence of three microstructure types in all samples studied, and allow for an investigation ofmore » the structures' unique geometries. Additionally, confocal microscopy is used for qualitative assessment of surface and internal composition. To complement optical observations, calorimetric (differential-scanning and modulation) experiments, provide the basis for an in-depth understanding of collective and individual thermal behavior. Observed ''transition'' features indicate clustering and ''straightening'' of helical ribbons into short, increasingly thickening, filaments that dissolve with increasing temperature. These results suggest that all microstructures formed in CDLC may coexist in a metastable chemical equilibrium. Further investigation of the CDLC thermal profile should uncover the process of cholesterol crystallization as well as the unique design and function of microstructures formed in this system.« less

Nanometer Scale Titanium Surface Texturing Are Detected by Signaling Pathways Involving Transient FAK and Src Activations

PubMed Central

Zambuzzi, Willian F.; Bonfante, Estevam A.; Jimbo, Ryo; Hayashi, Mariko; Andersson, Martin; Alves, Gutemberg; Takamori, Esther R.; Beltrão, Paulo J.; Coelho, Paulo G.; Granjeiro, José M.

2014-01-01

Background It is known that physico/chemical alterations on biomaterial surfaces have the capability to modulate cellular behavior, affecting early tissue repair. Such surface modifications are aimed to improve early healing response and, clinically, offer the possibility to shorten the time from implant placement to functional loading. Since FAK and Src are intracellular proteins able to predict the quality of osteoblast adhesion, this study evaluated the osteoblast behavior in response to nanometer scale titanium surface texturing by monitoring FAK and Src phosphorylations. Methodology Four engineered titanium surfaces were used for the study: machined (M), dual acid-etched (DAA), resorbable media microblasted and acid-etched (MBAA), and acid-etch microblasted (AAMB). Surfaces were characterized by scanning electron microscopy, interferometry, atomic force microscopy, x-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy. Thereafter, those 4 samples were used to evaluate their cytotoxicity and interference on FAK and Src phosphorylations. Both Src and FAK were investigated by using specific antibody against specific phosphorylation sites. Principal Findings The results showed that both FAK and Src activations were differently modulated as a function of titanium surfaces physico/chemical configuration and protein adsorption. Conclusions It can be suggested that signaling pathways involving both FAK and Src could provide biomarkers to predict osteoblast adhesion onto different surfaces. PMID:24999733

The impact of diamond nanocrystallinity on osteoblast functions.

PubMed

Yang, Lei; Sheldon, Brian W; Webster, Thomas J

2009-07-01

Nanocrystalline diamond has been proposed as an anti-abrasive film on orthopedic implants. In this study, osteoblast (bone forming cells) functions including adhesion (up to 4h), proliferation (up to 5 days) and differentiation (up to 21 days) on different diamond film topographies were systematically investigated. In order to exclude interferences from changes in surface chemistry and wettability (energy), diamond films with nanometer and micron scale topographies were fabricated through microwave plasma enhanced chemical-vapor-deposition and hydrogen plasma treatment. Scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy and water contact angle measurements verified the similar surface chemistry and wettability but varied topographies for all of the diamond films prepared on silicon in this study. Cytocompatibility assays demonstrated enhanced osteoblast functions (including adhesion, proliferation, intracellular protein synthesis, alkaline phosphatase activity and extracellular calcium deposition) on nanocrystalline diamond compared to submicron diamond grain size films for all time periods tested up to 21 days. An SEM study of osteoblast attachment helped to explain the topographical impact diamond had on osteoblast functions by showing altered filopodia extensions on the different diamond topographies. In summary, these results provided insights into understanding the role diamond nanotopography had on osteoblast interactions and more importantly, the application of diamond films to improve orthopedic implant lifetimes.

Modeling and prediction of copper removal from aqueous solutions by nZVI/rGO magnetic nanocomposites using ANN-GA and ANN-PSO.

PubMed

Fan, Mingyi; Hu, Jiwei; Cao, Rensheng; Xiong, Kangning; Wei, Xionghui

2017-12-21

Reduced graphene oxide-supported nanoscale zero-valent iron (nZVI/rGO) magnetic nanocomposites were prepared and then applied in the Cu(II) removal from aqueous solutions. Scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and superconduction quantum interference device magnetometer were performed to characterize the nZVI/rGO nanocomposites. In order to reduce the number of experiments and the economic cost, response surface methodology (RSM) combined with artificial intelligence (AI) techniques, such as artificial neural network (ANN), genetic algorithm (GA) and particle swarm optimization (PSO), has been utilized as a major tool that can model and optimize the removal processes, because a tremendous advance has recently been made on AI that may result in extensive applications. Based on RSM, ANN-GA and ANN-PSO were employed to model the Cu(II) removal process and optimize the operating parameters, e.g., operating temperature, initial pH, initial concentration and contact time. The ANN-PSO model was proven to be an effective tool for modeling and optimizing the Cu(II) removal with a low absolute error and a high removal efficiency. Furthermore, the isotherm, kinetic, thermodynamic studies and the XPS analysis were performed to explore the mechanisms of Cu(II) removal process.

Selective Removal of Hemoglobin from Blood Using Hierarchical Copper Shells Anchored to Magnetic Nanoparticles

PubMed Central

Wang, Yaokun; Yan, Mingyang

2017-01-01

Hierarchical copper shells anchored on magnetic nanoparticles were designed and fabricated to selectively deplete hemoglobin from human blood by immobilized metal affinity chromatography. Briefly, CoFe2O4 nanoparticles coated with polyacrylic acid were first synthesized by a one-pot solvothermal method. Hierarchical copper shells were then deposited by immobilizing Cu2+ on nanoparticles and subsequently by reducing between the solid CoFe2O4@COOH and copper solution with NaBH4. The resulting nanoparticles were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy, and vibrating sample magnetometry. The particles were also tested against purified bovine hemoglobin over a range of pH, contact time, and initial protein concentration. Hemoglobin adsorption followed pseudo-second-order kinetics and reached equilibrium in 90 min. Isothermal data also fit the Langmuir model well, with calculated maximum adsorption capacity 666 mg g−1. Due to the high density of Cu2+ on the shell, the nanoparticles efficiently and selectively deplete hemoglobin from human blood. Taken together, the results demonstrate that the particles with hierarchical copper shells effectively remove abundant, histidine-rich proteins, such as hemoglobin from human blood, and thereby minimize interference in diagnostic and other assays. PMID:28316987

System and method for compressive scanning electron microscopy

DOEpatents

Reed, Bryan W

2015-01-13

A scanning transmission electron microscopy (STEM) system is disclosed. The system may make use of an electron beam scanning system configured to generate a plurality of electron beam scans over substantially an entire sample, with each scan varying in electron-illumination intensity over a course of the scan. A signal acquisition system may be used for obtaining at least one of an image, a diffraction pattern, or a spectrum from the scans, the image, diffraction pattern, or spectrum representing only information from at least one of a select subplurality or linear combination of all pixel locations comprising the image. A dataset may be produced from the information. A subsystem may be used for mathematically analyzing the dataset to predict actual information that would have been produced by each pixel location of the image.

Characterization of two-dimensional hexagonal boron nitride using scanning electron and scanning helium ion microscopy

NASA Astrophysics Data System (ADS)

Guo, Hongxuan; Gao, Jianhua; Ishida, Nobuyuki; Xu, Mingsheng; Fujita, Daisuke

2014-01-01

Characterization of the structural and physical properties of two-dimensional (2D) materials, such as layer number and inelastic mean free path measurements, is very important to optimize their synthesis and application. In this study, we characterize the layer number and morphology of hexagonal boron nitride (h-BN) nanosheets on a metallic substrate using field emission scanning electron microscopy (FE-SEM) and scanning helium ion microscopy (HIM). Using scanning beams of various energies, we could analyze the dependence of the intensities of secondary electrons on the thickness of the h-BN nanosheets. Based on the interaction between the scanning particles (electrons and helium ions) and h-BN nanosheets, we deduced an exponential relationship between the intensities of secondary electrons and number of layers of h-BN. With the attenuation factor of the exponential formula, we calculate the inelastic mean free path of electrons and helium ions in the h-BN nanosheets. Our results show that HIM is more sensitive and consistent than FE-SEM for characterizing the number of layers and morphology of 2D materials.

Topography and refractometry of nanostructures using spatial light interference microscopy.

PubMed

Wang, Zhuo; Chun, Ik Su; Li, Xiuling; Ong, Zhun-Yong; Pop, Eric; Millet, Larry; Gillette, Martha; Popescu, Gabriel

2010-01-15

Spatial light interference microscopy (SLIM) is a novel method developed in our laboratory that provides quantitative phase images of transparent structures with a 0.3 nm spatial and 0.03 nm temporal accuracy owing to the white light illumination and its common path interferometric geometry. We exploit these features and demonstrate SLIM's ability to perform topography at a single atomic layer in graphene. Further, using a decoupling procedure that we developed for cylindrical structures, we extract the axially averaged refractive index of semiconductor nanotubes and a neurite of a live hippocampal neuron in culture. We believe that this study will set the basis for novel high-throughput topography and refractometry of man-made and biological nanostructures.

Quantitative phase imaging of human red blood cells using phase-shifting white light interference microscopy with colour fringe analysis

NASA Astrophysics Data System (ADS)

Singh Mehta, Dalip; Srivastava, Vishal

2012-11-01

We report quantitative phase imaging of human red blood cells (RBCs) using phase-shifting interference microscopy. Five phase-shifted white light interferograms are recorded using colour charge coupled device camera. White light interferograms were decomposed into red, green, and blue colour components. The phase-shifted interferograms of each colour were then processed by phase-shifting analysis and phase maps for red, green, and blue colours were reconstructed. Wavelength dependent refractive index profiles of RBCs were computed from the single set of white light interferogram. The present technique has great potential for non-invasive determination of refractive index variation and morphological features of cells and tissues.

Mapping optical path length and image enhancement using quantitative orientation-independent differential interference contrast microscopy

PubMed Central

Shribak, Michael; Larkin, Kieran G.; Biggs, David

2017-01-01

Abstract. We describe the principles of using orientation-independent differential interference contrast (OI-DIC) microscopy for mapping optical path length (OPL). Computation of the scalar two-dimensional OPL map is based on an experimentally received map of the OPL gradient vector field. Two methods of contrast enhancement for the OPL image, which reveal hardly visible structures and organelles, are presented. The results obtained can be used for reconstruction of a volume image. We have confirmed that a standard research grade light microscope equipped with the OI-DIC and 100×/1.3 NA objective lens, which was not specially selected for minimum wavefront and polarization aberrations, provides OPL noise level of ∼0.5  nm and lateral resolution if ∼300  nm at a wavelength of 546 nm. The new technology is the next step in the development of the DIC microscopy. It can replace standard DIC prisms on existing commercial microscope systems without modification. This will allow biological researchers that already have microscopy setups to expand the performance of their systems. PMID:28060991

Scanning capacitance microscopy of ErAs nanoparticles embedded in GaAs pn junctions

NASA Astrophysics Data System (ADS)

Park, K. W.; Nair, H. P.; Crook, A. M.; Bank, S. R.; Yu, E. T.

2011-09-01

Scanning capacitance microscopy is used to characterize the electronic properties of ErAs nanoparticles embedded in GaAs pn junctions grown by molecular beam epitaxy. Voltage-dependent capacitance images reveal localized variations in subsurface electronic structure near buried ErAs nanoparticles at lateral length scales of 20-30 nm. Numerical modeling indicates that these variations arise from inhomogeneities in charge modulation due to Fermi level pinning behavior associated with the embedded ErAs nanoparticles. Statistical analysis of image data yields an average particle radius of 6-8 nm—well below the direct resolution limit in scanning capacitance microscopy but discernible via analysis of patterns in nanoscale capacitance images.

Low-temperature and conventional scanning electron microscopy of human urothelial neoplasms.

PubMed

Hopkins, D M; Morris, J A; Oates, K; Huddart, H; Staff, W G

1989-05-01

The appearance of neoplastic human urothelium viewed by low-temperature scanning electron microscopy (LTSEM) and conventional scanning electron microscopy (CSEM) was compared. Fixed, dehydrated neoplastic cells viewed by CSEM had well-defined, often raised cell junctions; no intercellular gaps; and varying degrees of pleomorphic surface microvilli. The frozen hydrated material viewed by LTSEM, however, was quite different. The cells had a flat or dimpled surface, but no microvilli. There were labyrinthine lateral processes which interdigitated with those of adjacent cells and outlined large intercellular gaps. The process of fixation and dehydration will inevitably distort cell contours and on theoretical grounds, the images of frozen hydrated material should more closely resemble the in vivo appearance.

Growth of single-layer graphene on Ge (1 0 0) by chemical vapor deposition

NASA Astrophysics Data System (ADS)

Mendoza, C. D.; Caldas, P. G.; Freire, F. L.; Maia da Costa, M. E. H.

2018-07-01

The integration of graphene into nanoelectronic devices is dependent on the availability of direct deposition processes, which can provide uniform, large-area and high-quality graphene on semiconductor substrates such as Ge or Si. In this work, we synthesised graphene directly on p-type Ge (1 0 0) substrates by chemical vapour deposition. The influence of the CH4:H2 flow ratio on the graphene growth was investigated. Raman Spectroscopy, Raman mapping, Scanning Electron Microscopy, Atomic Force Microscopy and Scanning Tunnelling Microscopy/Scanning Tunnelling Spectroscopy results showed that good quality and homogeneous monolayer graphene over a large area can be achieved on Ge substrates directly with optimal growth conditions.

Airway recovery after face transplantation.

PubMed

Fischer, Sebastian; Wallins, Joe S; Bueno, Ericka M; Kueckelhaus, Maximilian; Chandawarkar, Akash; Diaz-Siso, J Rodrigo; Larson, Allison; Murphy, George F; Annino, Donald J; Caterson, Edward J; Pomahac, Bohdan

2014-12-01

Severe facial injuries can compromise the upper airway by reducing airway volume, obstructing or obliterating the nasal passage, and interfering with oral airflow. Besides the significant impact on quality of life, upper airway impairments can have life-threatening or life-altering consequences. The authors evaluated improvements in functional airway after face transplantation. Between 2009 and 2011, four patients underwent face transplantation at the authors' institution, the Brigham and Women's Hospital. Patients were examined preoperatively and postoperatively and their records reviewed for upper airway infections and sleeping disorders. The nasal mucosa was biopsied after face transplantation and analyzed using scanning electron microscopy. Volumetric imaging software was used to evaluate computed tomographic scans of the upper airway and assess airway volume changes before and after transplantation. Before transplantation, two patients presented an exposed naked nasal cavity and two suffered from occlusion of the nasal passage. Two patients required tracheostomy tubes and one had a prosthetic nose. Sleeping disorders were seen in three patients, and chronic cough was diagnosed in one. After transplantation, there was no significant improvement in sleeping disorders. The incidence of sinusitis increased because of mechanical interference of the donor septum and disappeared after surgical correction. All patients were decannulated after transplantation and were capable of nose breathing. Scanning electron micrographs of the respiratory mucosa revealed viable tissue capable of mucin production. Airway volume significantly increased in all patients. Face transplantation successfully restored the upper airway in four patients. Unhindered nasal breathing, viable respiratory mucosa, and a significant increase in airway volume contributed to tracheostomy decannulation.

Reprint of: Atmospheric scanning electron microscope observes cells and tissues in open medium through silicon nitride film.

PubMed

Nishiyama, Hidetoshi; Suga, Mitsuo; Ogura, Toshihiko; Maruyama, Yuusuke; Koizumi, Mitsuru; Mio, Kazuhiro; Kitamura, Shinichi; Sato, Chikara

2010-11-01

Direct observation of subcellular structures and their characterization is essential for understanding their physiological functions. To observe them in open environment, we have developed an inverted scanning electron microscope with a detachable, open-culture dish, capable of 8 nm resolution, and combined with a fluorescence microscope quasi-simultaneously observing the same area from the top. For scanning electron microscopy from the bottom, a silicon nitride film window in the base of the dish maintains a vacuum between electron gun and open sample dish while allowing electrons to pass through. Electrons are backscattered from the sample and captured by a detector under the dish. Cells cultured on the open dish can be externally manipulated under optical microscopy, fixed, and observed using scanning electron microscopy. Once fine structures have been revealed by scanning electron microscopy, their component proteins may be identified by comparison with separately prepared fluorescence-labeled optical microscopic images of the candidate proteins, with their heavy-metal-labeled or stained ASEM images. Furthermore, cell nuclei in a tissue block stained with platinum-blue were successfully observed without thin-sectioning, which suggests the applicability of this inverted scanning electron microscope to cancer diagnosis. This microscope visualizes mesoscopic-scale structures, and is also applicable to non-bioscience fields including polymer chemistry. Copyright © 2010 Elsevier Inc. All rights reserved.

Molecular Rotors

DTIC Science & Technology

2006-10-31

microwave signal processing components, and micro-fluidic devices. The projected involved the preparation, surface mounting, and characterization of...Guisinger, R. Basu, and M. C. Hersam, “Atomic-level characterization and control of free radical surface chemistry using scanning tunneling microscopy...Basu, and M. C. Hersam, “Atomic level characterization and control of organosilicon surface chemistry using scanning tunneling microscopy,” presented

[Gene sequencing by scanning molecular exciton microscopy]. Progress report, October 1, 1990--September 30, 1991

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

Not Available

1991-12-31

This report details progress made in setting up a laboratory for optical microscopy of genes. The apparatus including a fluorescence microscope, a scanning optical microscope, various spectrometers, and supporting computers is described. Results in developing photon and exciton tips, and in preparing samples are presented. (GHH)

Low temperature–scanning electron microscopy to evaluate morphology and predation of Scolothrips sexmaculatus Pergande (Thysanoptera: Thripidae) against spider mites (Acari: Tetranychidae: Tetranychus species)

USDA-ARS?s Scientific Manuscript database

This paper evaluates the potential usefulness of low temperature-scanning electron microscopy (LT-SEM) to evaluate morphology and predation behavior of the six-spotted thrips (Scolothrips sexmaculatus Pergande) against the two-spotted spider mite (Tetranychus urticae (Koch)). Morphological features...

Preparation of Chemically Etched Tips for Ambient Instructional Scanning Tunneling Microscopy

ERIC Educational Resources Information Center

Zaccardi, Margot J.; Winkelmann, Kurt; Olson, Joel A.

2010-01-01

A first-year laboratory experiment that utilizes concepts of electrochemical tip etching for scanning tunneling microscopy (STM) is described. This experiment can be used in conjunction with any STM experiment. Students electrochemically etch gold STM tips using a time-efficient method, which can then be used in an instructional grade STM that…

Sparse imaging for fast electron microscopy

NASA Astrophysics Data System (ADS)

Anderson, Hyrum S.; Ilic-Helms, Jovana; Rohrer, Brandon; Wheeler, Jason; Larson, Kurt

2013-02-01

Scanning electron microscopes (SEMs) are used in neuroscience and materials science to image centimeters of sample area at nanometer scales. Since imaging rates are in large part SNR-limited, large collections can lead to weeks of around-the-clock imaging time. To increase data collection speed, we propose and demonstrate on an operational SEM a fast method to sparsely sample and reconstruct smooth images. To accurately localize the electron probe position at fast scan rates, we model the dynamics of the scan coils, and use the model to rapidly and accurately visit a randomly selected subset of pixel locations. Images are reconstructed from the undersampled data by compressed sensing inversion using image smoothness as a prior. We report image fidelity as a function of acquisition speed by comparing traditional raster to sparse imaging modes. Our approach is equally applicable to other domains of nanometer microscopy in which the time to position a probe is a limiting factor (e.g., atomic force microscopy), or in which excessive electron doses might otherwise alter the sample being observed (e.g., scanning transmission electron microscopy).

Scanning transmission X-ray, laser scanning, and transmission electron microscopy mapping of the exopolymeric matrix of microbial biofilms.

PubMed

Lawrence, J R; Swerhone, G D W; Leppard, G G; Araki, T; Zhang, X; West, M M; Hitchcock, A P

2003-09-01

Confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and soft X-ray scanning transmission X-ray microscopy (STXM) were used to map the distribution of macromolecular subcomponents (e.g., polysaccharides, proteins, lipids, and nucleic acids) of biofilm cells and matrix. The biofilms were developed from river water supplemented with methanol, and although they comprised a complex microbial community, the biofilms were dominated by heterotrophic bacteria. TEM provided the highest-resolution structural imaging, CLSM provided detailed compositional information when used in conjunction with molecular probes, and STXM provided compositional mapping of macromolecule distributions without the addition of probes. By examining exactly the same region of a sample with combinations of these techniques (STXM with CLSM and STXM with TEM), we demonstrate that this combination of multimicroscopy analysis can be used to create a detailed correlative map of biofilm structure and composition. We are using these correlative techniques to improve our understanding of the biochemical basis for biofilm organization and to assist studies intended to investigate and optimize biofilms for environmental remediation applications.

Insights into radiation damage from atomic resolution scanning transmission electron microscopy imaging of mono-layer CuPcCl16 films on graphene.

PubMed

Mittelberger, Andreas; Kramberger, Christian; Meyer, Jannik C

2018-03-19

Atomically resolved images of monolayer organic crystals have only been obtained with scanning probe methods so far. On the one hand, they are usually prepared on surfaces of bulk materials, which are not accessible by (scanning) transmission electron microscopy. On the other hand, the critical electron dose of a monolayer organic crystal is orders of magnitudes lower than the one for bulk crystals, making (scanning) transmission electron microscopy characterization very challenging. In this work we present an atomically resolved study on the dynamics of a monolayer CuPcCl 16 crystal under the electron beam as well as an image of the undamaged molecules obtained by low-dose electron microscopy. The results show the dynamics and the radiation damage mechanisms in the 2D layer of this material, complementing what has been found for bulk crystals in earlier studies. Furthermore, being able to image the undamaged molecular crystal allows the characterization of new composites consisting of 2D materials and organic molecules.

Velocity servo for continuous scan Fourier interference spectrometer

NASA Technical Reports Server (NTRS)

Schindler, R. A. (Inventor)

1980-01-01

A velocity servo for continuous scan Fourier interference spectrometer of the double pass retroreflector type having two cat's eye retroreflectors is described. The servo uses an open loop, lead screw drive system for one retroreflector with compensation for any variations in speed of drive of the lead screw provided by sensing any variation in the rate of reference laser fringes, and producing an error signal from such variation used to compensate by energizing a moving coil actuator for the other retroreflector optical path, and energizing (through a highpass filter) piezoelectric actuators for the secondary mirrors of the retroreflectors.

A hybrid scanning mode for fast scanning ion conductance microscopy (SICM) imaging

PubMed Central

Zhukov, Alex; Richards, Owen; Ostanin, Victor; Korchev, Yuri; Klenerman, David

2012-01-01

We have developed a new method of controlling the pipette for scanning ion conductance microscopy to obtain high-resolution images faster. The method keeps the pipette close to the surface during a single line scan but does not follow the exact surface topography, which is calculated by using the ion current. Using an FPGA platform we demonstrate this new method on model test samples and then on live cells. This method will be particularly useful to follow changes occurring on relatively flat regions of the cell surface at high spatial and temporal resolutions. PMID:22902298

Three-Dimensional Intercalated Porous Graphene on Si(111)

NASA Astrophysics Data System (ADS)

Pham, Trung T.; Sporken, Robert

2018-02-01

Three-dimensional intercalated porous graphene has been formed on Si(111) by electron beam evaporation under appropriate conditions and its structural and electronic properties investigated in detail by reflection high-energy electron diffraction, x-ray photoemission spectroscopy, Raman spectroscopy, high-resolution scanning electron microscopy, atomic force microscopy, and scanning tunneling microscopy. The results show that the crystalline quality of the porous graphene depended not only on the substrate temperature but also on the SiC layer thickness during carbon atom deposition.

Spectrally resolved laser interference microscopy

NASA Astrophysics Data System (ADS)

Butola, Ankit; Ahmad, Azeem; Dubey, Vishesh; Senthilkumaran, P.; Singh Mehta, Dalip

2018-07-01

We developed a new quantitative phase microscopy technique, namely, spectrally resolved laser interference microscopy (SR-LIM), with which it is possible to quantify multi-spectral phase information related to biological specimens without color crosstalk using a color CCD camera. It is a single shot technique where sequential switched on/off of red, green, and blue (RGB) wavelength light sources are not required. The method is implemented using a three-wavelength interference microscope and a customized compact grating based imaging spectrometer fitted at the output port. The results of the USAF resolution chart while employing three different light sources, namely, a halogen lamp, light emitting diodes, and lasers, are discussed and compared. The broadband light sources like the halogen lamp and light emitting diodes lead to stretching in the spectrally decomposed images, whereas it is not observed in the case of narrow-band light sources, i.e. lasers. The proposed technique is further successfully employed for single-shot quantitative phase imaging of human red blood cells at three wavelengths simultaneously without color crosstalk. Using the present technique, one can also use a monochrome camera, even though the experiments are performed using multi-color light sources. Finally, SR-LIM is not only limited to RGB wavelengths, it can be further extended to red, near infra-red, and infra-red wavelengths, which are suitable for various biological applications.

Three-dimensional electron microscopy simulation with the CASINO Monte Carlo software.

PubMed

Demers, Hendrix; Poirier-Demers, Nicolas; Couture, Alexandre Réal; Joly, Dany; Guilmain, Marc; de Jonge, Niels; Drouin, Dominique

2011-01-01

Monte Carlo softwares are widely used to understand the capabilities of electron microscopes. To study more realistic applications with complex samples, 3D Monte Carlo softwares are needed. In this article, the development of the 3D version of CASINO is presented. The software feature a graphical user interface, an efficient (in relation to simulation time and memory use) 3D simulation model, accurate physic models for electron microscopy applications, and it is available freely to the scientific community at this website: www.gel.usherbrooke.ca/casino/index.html. It can be used to model backscattered, secondary, and transmitted electron signals as well as absorbed energy. The software features like scan points and shot noise allow the simulation and study of realistic experimental conditions. This software has an improved energy range for scanning electron microscopy and scanning transmission electron microscopy applications. Copyright © 2011 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.

Three-Dimensional Electron Microscopy Simulation with the CASINO Monte Carlo Software

PubMed Central

Demers, Hendrix; Poirier-Demers, Nicolas; Couture, Alexandre Réal; Joly, Dany; Guilmain, Marc; de Jonge, Niels; Drouin, Dominique

2011-01-01

Monte Carlo softwares are widely used to understand the capabilities of electron microscopes. To study more realistic applications with complex samples, 3D Monte Carlo softwares are needed. In this paper, the development of the 3D version of CASINO is presented. The software feature a graphical user interface, an efficient (in relation to simulation time and memory use) 3D simulation model, accurate physic models for electron microscopy applications, and it is available freely to the scientific community at this website: www.gel.usherbrooke.ca/casino/index.html. It can be used to model backscattered, secondary, and transmitted electron signals as well as absorbed energy. The software features like scan points and shot noise allow the simulation and study of realistic experimental conditions. This software has an improved energy range for scanning electron microscopy and scanning transmission electron microscopy applications. PMID:21769885

Confocal raman microscopy as a non-invasive tool to investigate the phase composition of frozen complex cryopreservation media.

PubMed

Kreiner-Møller, A; Stracke, F; Zimmermann, H

2013-01-01

Various cryoprotective agents (CPA) are added to cell media in order to avoid cell injury during cryo preservation. The resulting complex environment of the preserved cell, consisting of crystalline and liquid phases can however not be investigated non-invasively by established methods in cryobiology. This study shows how scanning confocal Raman microscopy can non-invasively extract information on chemical composition, phase domain and distribution at cryogenic temperatures. The formation of the salt hydrate, hydrohalite NaCl∙H2O, in solutions comprised of phosphate buffered saline (PBS) and dimethyl sulphoxide (DMSO) is studied in particular. Scanning confocal Raman microscopy can be used to unambiguously identify hydrohalite in a medium containing DMSO and saline. The confocal Raman microscopy imaging along with differential scanning calorimetric measurements further show that the hydrohalite is formed without eutectic formation. This method also allows for discrimination between closely packed hydrohalite crystals that are oriented differently.

Simultaneous Scanning Ion Conductance Microscopy and Atomic Force Microscopy with Microchanneled Cantilevers

NASA Astrophysics Data System (ADS)

Ossola, Dario; Dorwling-Carter, Livie; Dermutz, Harald; Behr, Pascal; Vörös, János; Zambelli, Tomaso

2015-12-01

We combined scanning ion conductance microscopy (SICM) and atomic force microscopy (AFM) into a single tool using AFM cantilevers with an embedded microchannel flowing into the nanosized aperture at the apex of the hollow pyramid. An electrode was positioned in the AFM fluidic circuit connected to a second electrode in the bath. We could thus simultaneously measure the ionic current and the cantilever bending (in optical beam deflection mode). First, we quantitatively compared the SICM and AFM contact points on the approach curves. Second, we estimated where the probe in SICM mode touches the sample during scanning on a calibration grid and applied the finding to image a network of neurites on a Petri dish. Finally, we assessed the feasibility of a double controller using both the ionic current and the deflection as input signals of the piezofeedback. The experimental data were rationalized in the framework of finite elements simulations.

Surface polymerization of (3,4-ethylenedioxythiophene) probed by in situ scanning tunneling microscopy on Au(111) in ionic liquids.

PubMed

Ahmad, Shahzada; Carstens, Timo; Berger, Rüdiger; Butt, Hans-Jürgen; Endres, Frank

2011-01-01

The electropolymerization of 3,4-ethylenedioxythiophene (EDOT) to poly(3,4-ethylenedioxythiophene) (PEDOT) was investigated in the air and water-stable ionic liquids 1-hexyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate [HMIm]FAP and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) amide [EMIm]TFSA. In situ scanning tunnelling microscopy (STM) results show that the electropolymerization of EDOT in the ionic liquid can be probed on the nanoscale. In contrast to present understanding, it was observed that the EDOT can be oxidised in ionic liquids well below its oxidation potential and the under potential growth of polymer was visualized by in situ STM. These results serve as the first study to confirm the under potential growth of conducting polymers in ionic liquids. Furthermore, ex situ microscopy measurements were performed. Quite a high current of 670 nA was observed on the nanoscale by conductive scanning force microscopy (CSFM).

Cytocompatibility and uptake of halloysite clay nanotubes.

PubMed

Vergaro, Viviana; Abdullayev, Elshad; Lvov, Yuri M; Zeitoun, Andre; Cingolani, Roberto; Rinaldi, Ross; Leporatti, Stefano

2010-03-08

Halloysite is aluminosilicate clay with hollow tubular structure of 50 nm external diameter and 15 nm diameter lumen. Halloysite biocompatibility study is important for its potential applications in polymer composites, bone implants, controlled drug delivery, and for protective coating (e.g., anticorrosion or antimolding). Halloysite nanotubes were added to different cell cultures for toxicity tests. Its fluorescence functionalization by aminopropyltriethosilane (APTES) and with fluorescently labeled polyelectrolyte layers allowed following halloysite uptake by the cells with confocal laser scanning microscopy (CLSM). Quantitative Trypan blue and MTT measurements performed with two neoplastic cell lines model systems as a function of the nanotubes concentration and incubation time indicate that halloysite exhibits a high level of biocompatibility and very low cytotoxicity, rendering it a good candidate for household materials and medicine. A combination of transmission electron microscopy (TEM), scanning electron microscopy (SEM), and scanning force microscopy (SFM) imaging techniques have been employed to elucidate the structure of halloysite nanotubes.

Design and construction of a cost-efficient Arduino-based mirror galvanometer system for scanning optical microscopy

NASA Astrophysics Data System (ADS)

Hsu, Jen-Feng; Dhingra, Shonali; D'Urso, Brian

2017-01-01

Mirror galvanometer systems (galvos) are commonly employed in research and commercial applications in areas involving laser imaging, laser machining, laser-light shows, and others. Here, we present a robust, moderate-speed, and cost-efficient home-built galvo system. The mechanical part of this design consists of one mirror, which is tilted around two axes with multiple surface transducers. We demonstrate the ability of this galvo by scanning the mirror using a computer, via a custom driver circuit. The performance of the galvo, including scan range, noise, linearity, and scan speed, is characterized. As an application, we show that this galvo system can be used in a confocal scanning microscopy system.

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

PubMed

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

2010-07-27

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

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

PubMed Central

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

2010-01-01

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

Pure optical photoacoustic microscopy

PubMed Central

Xie, Zhixing; Chen, Sung-Liang; Ling, Tao; Guo, L. Jay; Carson, Paul L.; Wang, Xueding

2011-01-01

The concept of pure optical photoacoustic microscopy(POPAM) was proposed based on optical rastering of a focused excitation beam and optically sensing the photoacoustic signal using a microring resonator fabricated by a nanoimprinting technique. After the refinements of the microring’s working wavelength and in the resonator structure and mold fabrication, an ultrahigh Q factor of 3.0×105 was achieved which provided high sensitivity with a noise equivalent detectable pressure(NEDP) value of 29Pa. This NEDP is much lower than the hundreds of Pascals achieved with existing optical resonant structures such as etalons, fiber gratings and dielectric multilayer interference filters available for acoustic measurement. The featured high sensitivity allowed the microring resonator to detect the weak photoacoustic signals from micro- or submicroscale objects. The inherent superbroad bandwidth of the optical microring resonator combined with an optically focused scanning beam provided POPAM with high resolution in the axial as well as both lateral directions while the axial resolution of conventional photoacoustic microscopy (PAM) suffers from the limited bandwidth of PZT detectors. Furthermore, the broadband microring resonator showed similar sensitivity to that of our most sensitive PZT detector. The current POPAM system provides a lateral resolution of 5 μm and an axial resolution of 8 μm, comparable to that achieved by optical microscopy while presenting the unique contrast of optical absorption and functional information complementing other optical modalities. The 3D structure of microvasculature, including capillary networks, and even individual red blood cells have been discerned successfully in the proof-of-concept experiments on mouse bladders ex vivo and mouse ears in vivo. The potential of approximately GHz bandwidth of the microring resonator also might allow much higher resolution than shown here in microscopy of optical absorption and acoustic propagation properties at depths in unfrozen tissue specimens or thicker tissue sections, which is not now imageable with current optical or acoustic microscopes of comparable resolution. PMID:21643156

Magnetic elements for switching magnetization magnetic force microscopy tips.

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

Cambel, V.; Elias, P.; Gregusova, D.

2010-09-01

Using combination of micromagnetic calculations and magnetic force microscopy (MFM) imaging we find optimal parameters for novel magnetic tips suitable for switching magnetization MFM. Switching magnetization MFM is based on two-pass scanning atomic force microscopy with reversed tip magnetization between the scans. Within the technique the sum of the scanned data with reversed tip magnetization depicts local atomic forces, while their difference maps the local magnetic forces. Here we propose the design and calculate the magnetic properties of tips suitable for this scanning probe technique. We find that for best performance the spin-polarized tips must exhibit low magnetic moment, lowmore » switching fields, and single-domain state at remanence. The switching field of such tips is calculated and optimum shape of the Permalloy elements for the tips is found. We show excellent correspondence between calculated and experimental results for Py elements.« less

Multi-scale Imaging of Cellular and Sub-cellular Structures using Scanning Probe Recognition Microscopy.

NASA Astrophysics Data System (ADS)

Chen, Q.; Rice, A. F.

2005-03-01

Scanning Probe Recognition Microscopy is a new scanning probe capability under development within our group to reliably return to and directly interact with a specific nanobiological feature of interest. In previous work, we have successfully recognized and classified tubular versus globular biological objects from experimental atomic force microscope images using a method based on normalized central moments [ref. 1]. In this paper we extend this work to include recognition schemes appropriate for cellular and sub-cellular structures. Globular cells containing tubular actin filaments are under investigation. Thus there are differences in external/internal shapes and scales. Continuous Wavelet Transform with a differential Gaussian mother wavelet is employed for multi- scale analysis. [ref. 1] Q. Chen, V. Ayres and L. Udpa, ``Biological Investigation Using Scanning Probe Recognition Microscopy,'' Proceedings 3rd IEEE Conference on Nanotechnology, vol. 2, p 863-865 (2003).

Transfer doping of single isolated nanodiamonds, studied by scanning probe microscopy techniques

NASA Astrophysics Data System (ADS)

Bolker, Asaf; Saguy, Cecile; Kalish, Rafi

2014-09-01

The transfer doping of diamond surfaces has been applied in various novel two-dimensional electronic devices. Its extension to nanodiamonds (ND) is essential for ND-based applications in many fields. In particular, understanding the influence of the crystallite size on transfer doping is desirable. Here, we report the results of a detailed study of the electronic energetic band structure of single, isolated transfer-doped nanodiamonds with nanometric resolution using a combination of scanning tunneling spectroscopy and Kelvin force microscopy measurements. The results show how the band gap, the valence band maximum, the electron affinity and the work function all depend on the ND’s size and nanoparticle surface properties. The present analysis, which combines information from both scanning tunneling spectroscopy and Kelvin force microscopy, should be applicable to any nanoparticle or surface that can be measured with scanning probe techniques.

The application of scanning electron microscopy to fractography

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

Brooks, C.R.; McGill, B.L.

1994-10-01

Many failures involve fracture, and determination of the fracture process is a key factor in understanding the failure. This is frequently accomplished by characterizing the topography of the fracture surface. Scanning electron microscopy has a prominent role in fractography due to three features of the scanning electron microscope (SEM): high resolution, great depth of field, and the ability to obtain chemical information via analysis of the X-rays generated by the electrons. A qualitative treatment is presented of the interaction of electrons with a sample and the effect of the SEM operating parameters on image formation, quality, and X-ray analysis. Fractographsmore » are presented to illustrate these features of scanning electron microscopy and to illustrate the limitations and precautions in obtaining fractographs and x-ray analyses. The review is concluded with examples of fracture surface features of metallic, ceramic, and polymeric materials.« less

Identification of Foreign Particles in Human Tissues using Raman Microscopy.

PubMed

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

2018-06-12

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

Confocal laser scanning microscopy of porcine skin: implications for human wound healing studies

PubMed Central

VARDAXIS, N. J.; BRANS, T. A.; BOON, M. E.; KREIS, R. W.; MARRES, L. M.

1997-01-01

The structure of porcine skin as examined by light microscopy is reviewed and its similarities to and differences from human skin are highlighted. Special imaging techniques and staining procedures are described and their use in gathering morphological information in porcine skin is discussed. Confocal laser scanning microscopy (CLSM) was employed to examine the structure of porcine skin and the findings are presented as an adjunct to the information already available in the literature. It is concluded that CLSM provides valuable additional morphological information to material examined by conventional microscopy and is useful for wound healing studies in the porcine model. PMID:9183682

Refixation of Osteochondral Fractures by an Ultrasound-Activated Pin System - An Ovine In Vivo Examination Using CT and Scanning Electron Microscope.

PubMed

H, Neumann; A P, Schulz; S, Breer; A, Unger; B, Kienast

2015-01-01

Osteochondral injuries, if not treated appropriately, often lead to severe osteoarthritis of the affected joint. Without refixation of the osteochondral fragment, human cartilage only repairs these defects imperfectly. All existing refixation systems for chondral defects have disadvantages, for instance bad MRI quality in the postoperative follow-up or low anchoring forces. To address the problem of reduced stability in resorbable implants, ultrasound-activated pins were developed. By ultrasound-activated melting of the tip of these implants a higher anchoring is assumed. Aim of the study was to investigate, if ultrasound-activated pins can provide a secure refixation of osteochondral fractures comparing to conventional screw and conventional, resorbable pin osteosynthesis. CT scans and scanning electron microscopy should proovegood refixation results with no further tissue damage by the melting of the ultrasound-activated pins in comparison to conventional osteosynthesis. Femoral osteochondral fragments in sheep were refixated with ultrasound-activated pins (SonicPin™), Ethipins(®) and screws (Asnis™). The quality of the refixated fragments was examined after three month of full weight bearing by CT scans and scanning electron microscopy of the cartilage surface. The CT examination found almost no statistically significant difference in the quality of refixation between the three different implants used. Concerning the CT morphology, ultrasound-activated pins demonstrated at least the same quality in refixation of osteochondral fragments as conventional resorbable pins or screws. The scanning electron microscopy showed no major surface damage by the three implants, especially any postulated cartilage damage induced by the heat of the ultrasound-activated pin. The screws protruded above the cartilage surface, which may affect the opposingtibial surface. Using CT scans and scanning electron microscopy, the SonicPin™, the Ethipin(®) and screws were at least equivalent in refixation quality of osteochondral fragments.

Image scanning fluorescence emission difference microscopy based on a detector array.

PubMed

Li, Y; Liu, S; Liu, D; Sun, S; Kuang, C; Ding, Z; Liu, X

2017-06-01

We propose a novel imaging method that enables the enhancement of three-dimensional resolution of confocal microscopy significantly and achieve experimentally a new fluorescence emission difference method for the first time, based on the parallel detection with a detector array. Following the principles of photon reassignment in image scanning microscopy, images captured by the detector array were arranged. And by selecting appropriate reassign patterns, the imaging result with enhanced resolution can be achieved with the method of fluorescence emission difference. Two specific methods are proposed in this paper, showing that the difference between an image scanning microscopy image and a confocal image will achieve an improvement of transverse resolution by approximately 43% compared with that in confocal microscopy, and the axial resolution can also be enhanced by at least 22% experimentally and 35% theoretically. Moreover, the methods presented in this paper can improve the lateral resolution by around 10% than fluorescence emission difference and 15% than Airyscan. The mechanism of our methods is verified by numerical simulations and experimental results, and it has significant potential in biomedical applications. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

A novel glucose oxidase biosensor based on poly([2,2';5',2″]-terthiophene-3'-carbaldehyde) modified electrode.

PubMed

Guler, Muhammet; Turkoglu, Vedat; Kivrak, Arif

2015-08-01

In the study, the electrochemical behavior of glucose oxidase (GOx) immobilized on poly([2,2';5',2″]-terthiophene-3'-carbaldehyde) (poly(TTP)) modified glassy carbon electrode (GCE) was investigated. The biosensor (poly(TTP)/GOx/GCE) showed a pair of redox peaks in 0.1 M phosphate buffer (pH 7.4) solution in the absence of oxygen the co-substrate of GOx. In here, Poly(TTP)/GOx/GCE biosensor acts as the co-substrate instead of oxygen. Upon the addition of glucose, the reduction and oxidation peak currents increased until the active site of GOx was fully saturated with glucose. The apparent m was estimated 26.13 mM from Lineweaver-Burk graph. The biosensor displayed a good stability and bioactivity. The biosensor showed a high sensitivity (56.1 nA/mM), a linear range (from 0.5 to 20.15 mM), and a good reproducibility with 3.6% of relative standard deviation. In addition, the interference currents of glycin, ascorbic acid, histidine, uric acid, dopamine, arginine, and fructose on GOx biosensor were investigated. All that substances exhibited an interference current under 10%. It was not shown a marked difference between GOx biosensor and spectrophotometric measurement of glucose in serum examples. UV-visible spectroscopy and scanning electron microscopy (SEM) experiments of the biosensor were also performed. Copyright © 2015 Elsevier B.V. All rights reserved.

Landau quantization and quasiparticle interference in the three-dimensional Dirac semimetal Cd₃As₂.

PubMed

Jeon, Sangjun; Zhou, Brian B; Gyenis, Andras; Feldman, Benjamin E; Kimchi, Itamar; Potter, Andrew C; Gibson, Quinn D; Cava, Robert J; Vishwanath, Ashvin; Yazdani, Ali

2014-09-01

Condensed-matter systems provide a rich setting to realize Dirac and Majorana fermionic excitations as well as the possibility to manipulate them for potential applications. It has recently been proposed that chiral, massless particles known as Weyl fermions can emerge in certain bulk materials or in topological insulator multilayers and give rise to unusual transport properties, such as charge pumping driven by a chiral anomaly. A pair of Weyl fermions protected by crystalline symmetry effectively forming a massless Dirac fermion has been predicted to appear as low-energy excitations in a number of materials termed three-dimensional Dirac semimetals. Here we report scanning tunnelling microscopy measurements at sub-kelvin temperatures and high magnetic fields on the II-V semiconductor Cd3As2. We probe this system down to atomic length scales, and show that defects mostly influence the valence band, consistent with the observation of ultrahigh-mobility carriers in the conduction band. By combining Landau level spectroscopy and quasiparticle interference, we distinguish a large spin-splitting of the conduction band in a magnetic field and its extended Dirac-like dispersion above the expected regime. A model band structure consistent with our experimental findings suggests that for a magnetic field applied along the axis of the Dirac points, Weyl fermions are the low-energy excitations in Cd3As2.

Potentiation of femtosecond laser intratissue refractive index shaping (IRIS) in the living cornea with sodium fluorescein.

PubMed

Nagy, Lana J; Ding, Li; Xu, Lisen; Knox, Wayne H; Huxlin, Krystel R

2010-02-01

To assess the effectiveness of intratissue refractive index shaping (IRIS) in living corneas and test the hypothesis that it can be enhanced by increasing the two-photon absorption (TPA) of the tissue. Three corneas were removed from adult cats and cut into six pieces, which were placed in preservative (Optisol-GS; Bausch & Lomb, Inc., Irvine, CA) containing 0%, 0.25%, 1%, 1.5%, or 2.5% sodium fluorescein (Na-Fl). An 800-nm Ti:Sapphire femtosecond laser with a 100-fs pulse duration and 80-MHz repetition rate was used to perform IRIS in each piece, creating several refractive index (RI) modification lines at different speeds (between 0.1 and 5 mm/s). The lines were 1 mum wide, 10 microm apart, and approximately 150 microm below the tissue surface. The RI change of each grating was measured using calibrated, differential interference contrast microscopy. TUNEL staining was performed to assess whether IRIS or Na-Fl doping causes cell death. Scanning at 0.1 mm/s changed the RI of undoped, living corneas by 0.005. In doped corneas, RI changes between 0.01 and 0.02 were reliably achieved with higher scanning speeds. The magnitude of RI changes attained was directly proportional to Na-Fl doping concentration and inversely proportional to the scanning speed used to create the gratings. IRIS can be efficiently performed in living corneal tissue. Increasing the TPA of the tissue with Na-Fl increased both the scanning speeds and the magnitude of RI changes in a dose-dependent manner. Ongoing studies are exploring the use of IRIS to alter the optical properties of corneal tissue in situ, over an extended period.

Potentiation of Femtosecond Laser Intratissue Refractive Index Shaping (IRIS) in the Living Cornea with Sodium Fluorescein

PubMed Central

Nagy, Lana J.; Ding, Li; Xu, Lisen; Knox, Wayne H.

2010-01-01

Purpose. To assess the effectiveness of intratissue refractive index shaping (IRIS) in living corneas and test the hypothesis that it can be enhanced by increasing the two-photon absorption (TPA) of the tissue. Methods. Three corneas were removed from adult cats and cut into six pieces, which were placed in preservative (Optisol-GS; Bausch & Lomb, Inc., Irvine, CA) containing 0%, 0.25%, 1%, 1.5%, or 2.5% sodium fluorescein (Na-Fl). An 800-nm Ti:Sapphire femtosecond laser with a 100-fs pulse duration and 80-MHz repetition rate was used to perform IRIS in each piece, creating several refractive index (RI) modification lines at different speeds (between 0.1 and 5 mm/s). The lines were 1 μm wide, 10 μm apart, and ∼150 μm below the tissue surface. The RI change of each grating was measured using calibrated, differential interference contrast microscopy. TUNEL staining was performed to assess whether IRIS or Na-Fl doping causes cell death. Results. Scanning at 0.1 mm/s changed the RI of undoped, living corneas by 0.005. In doped corneas, RI changes between 0.01 and 0.02 were reliably achieved with higher scanning speeds. The magnitude of RI changes attained was directly proportional to Na-Fl doping concentration and inversely proportional to the scanning speed used to create the gratings. Conclusions. IRIS can be efficiently performed in living corneal tissue. Increasing the TPA of the tissue with Na-Fl increased both the scanning speeds and the magnitude of RI changes in a dose-dependent manner. Ongoing studies are exploring the use of IRIS to alter the optical properties of corneal tissue in situ, over an extended period. PMID:19815735

Quasiparticle interference in unconventional 2D systems.

PubMed

Chen, Lan; Cheng, Peng; Wu, Kehui

2017-03-15

At present, research of 2D systems mainly focuses on two kinds of materials: graphene-like materials and transition-metal dichalcogenides (TMDs). Both of them host unconventional 2D electronic properties: pseudospin and the associated chirality of electrons in graphene-like materials, and spin-valley-coupled electronic structures in the TMDs. These exotic electronic properties have attracted tremendous interest for possible applications in nanodevices in the future. Investigation on the quasiparticle interference (QPI) in 2D systems is an effective way to uncover these properties. In this review, we will begin with a brief introduction to 2D systems, including their atomic structures and electronic bands. Then, we will discuss the formation of Friedel oscillation due to QPI in constant energy contours of electron bands, and show the basic concept of Fourier-transform scanning tunneling microscopy/spectroscopy (FT-STM/STS), which can resolve Friedel oscillation patterns in real space and consequently obtain the QPI patterns in reciprocal space. In the next two parts, we will summarize some pivotal results in the investigation of QPI in graphene and silicene, in which systems the low-energy quasiparticles are described by the massless Dirac equation. The FT-STM experiments show there are two different interference channels (intervalley and intravalley scattering) and backscattering suppression, which associate with the Dirac cones and the chirality of quasiparticles. The monolayer and bilayer graphene on different substrates (SiC and metal surfaces), and the monolayer and multilayer silicene on a Ag(1 1 1) surface will be addressed. The fifth part will introduce the FT-STM research on QPI in TMDs (monolayer and bilayer of WSe 2 ), which allow us to infer the spin texture of both conduction and valence bands, and present spin-valley coupling by tracking allowed and forbidden scattering channels.

Chemistry Viewed through the Eyes of High-Resolution Microscopy.

ERIC Educational Resources Information Center

Beer, Michael; And Others

1981-01-01

This special report, prepared by several chemists working in the field of electron microscopy, provides information regarding the most recent developments in transmission and scanning electron microscopy that have chemical significance. (CS)

Characterizing individual particles on tree leaves using computer automated scanning electron microscopy

Treesearch

D. L. Johnson; D. J. Nowak; V. A. Jouraeva

1999-01-01

Leaves from twenty-three deciduous tree species and five conifer species were collected within a limited geographic range (1 km radius) and evaluated for possible application of scanning electron microscopy and X-ray microanalysis techniques of individual particle analysis (IPA). The goal was to identify tree species with leaves suitable for the automated...

STEM VQ Method, Using Scanning Transmission Electron Microscopy (STEM) for Accurate Virus Quantification

DTIC Science & Technology

2017-02-02

Corresponding Author Abstract Accurate virus quantification is sought, but a perfect method still eludes the scientific community. Electron...unlimited. UNCLASSIFIED 2 provides morphology data and counts all viral particles, including partial or noninfectious particles; however, EM methods ...consistent, reproducible virus quantification method called Scanning Transmission Electron Microscopy – Virus Quantification (STEM-VQ) which simplifies

Observing Tin-Lead Alloys by Scanning Electron Microscopy: A Physical Chemistry Experiment Investigating Macro-Level Behaviors and Micro-Level Structures

ERIC Educational Resources Information Center

Wang, Yue; Xu, Xinhua; Wu, Meifen; Hu, Huikang; Wang, Xiaogang

2015-01-01

Scanning electron microscopy (SEM) was introduced into undergraduate physical chemistry laboratory curriculum to help students observe the phase composition and morphology characteristics of tin-lead alloys and thus further their understanding of binary alloy phase diagrams. The students were captivated by this visual analysis method, which…

Chemical Silver Coating of Fiber Tips in Near-Field Scanning Optical Microscopy

NASA Technical Reports Server (NTRS)

Vikram, Chandra S.; Witherow, William K.

1998-01-01

We report what is believed to be the first experimental demonstration of silver coating by a wet chemical process on tapered fiber tips used in near-field scanning optical microscopy. The process is at room temperature and pressure and takes only a few minutes to complete. Many tips can be simultaneously coated.

Reflection imaging of China ink-perfused brain vasculature using confocal laser-scanning microscopy after clarification of brain tissue by the Spalteholz method.

PubMed

Gutierre, R C; Vannucci Campos, D; Mortara, R A; Coppi, A A; Arida, R M

2017-04-01

Confocal laser-scanning microscopy is a useful tool for visualizing neurons and glia in transparent preparations of brain tissue from laboratory animals. Currently, imaging capillaries and venules in transparent brain tissues requires the use of fluorescent proteins. Here, we show that vessels can be imaged by confocal laser-scanning microscopy in transparent cortical, hippocampal and cerebellar preparations after clarification of China ink-injected specimens by the Spalteholz method. This method may be suitable for global, three-dimensional, quantitative analyses of vessels, including stereological estimations of total volume and length and of surface area of vessels, which constitute indirect approaches to investigate angiogenesis. © 2017 Anatomical Society.

A fast image simulation algorithm for scanning transmission electron microscopy.

PubMed

Ophus, Colin

2017-01-01

Image simulation for scanning transmission electron microscopy at atomic resolution for samples with realistic dimensions can require very large computation times using existing simulation algorithms. We present a new algorithm named PRISM that combines features of the two most commonly used algorithms, namely the Bloch wave and multislice methods. PRISM uses a Fourier interpolation factor f that has typical values of 4-20 for atomic resolution simulations. We show that in many cases PRISM can provide a speedup that scales with f 4 compared to multislice simulations, with a negligible loss of accuracy. We demonstrate the usefulness of this method with large-scale scanning transmission electron microscopy image simulations of a crystalline nanoparticle on an amorphous carbon substrate.

A fast image simulation algorithm for scanning transmission electron microscopy

DOE PAGES

Ophus, Colin

2017-05-10

Image simulation for scanning transmission electron microscopy at atomic resolution for samples with realistic dimensions can require very large computation times using existing simulation algorithms. Here, we present a new algorithm named PRISM that combines features of the two most commonly used algorithms, namely the Bloch wave and multislice methods. PRISM uses a Fourier interpolation factor f that has typical values of 4-20 for atomic resolution simulations. We show that in many cases PRISM can provide a speedup that scales with f 4 compared to multislice simulations, with a negligible loss of accuracy. We demonstrate the usefulness of this methodmore » with large-scale scanning transmission electron microscopy image simulations of a crystalline nanoparticle on an amorphous carbon substrate.« less

Two-dimensional displacement measurement based on two parallel gratings

NASA Astrophysics Data System (ADS)

Wei, Peipei; Lu, Xi; Qiao, Decheng; Zou, Limin; Huang, Xiangdong; Tan, Jiubin; Lu, Zhengang

2018-06-01

In this paper, a two-dimensional (2-D) planar encoder based on two parallel gratings, which includes a scanning grating and scale grating, is presented. The scanning grating is a combined transmission rectangular grating comprised of a 2-D grating located at the center and two one-dimensional (1-D) gratings located at the sides. The grating lines of the two 1-D gratings are perpendicular to each other and parallel with the 2-D grating lines. The scale grating is a 2-D reflective-type rectangular grating placed in parallel with the scanning grating, and there is an angular difference of 45° between the grating lines of the two 2-D gratings. With the special structural design of the scanning grating, the encoder can measure the 2-D displacement in the grating plane simultaneously, and the measured interference signals in the two directions are uncoupled. Moreover, by utilizing the scanning grating to modulate the phase of the interference signals instead of the prisms, the structure of the encoder is compact. Experiments were implemented, and the results demonstrate the validity of the 2-D planar grating encoder.

Two-Wavelength Multi-Gigahertz Frequency Comb-Based Interferometry for Full-Field Profilometry

NASA Astrophysics Data System (ADS)

Choi, Samuel; Kashiwagi, Ken; Kojima, Shuto; Kasuya, Yosuke; Kurokawa, Takashi

2013-10-01

The multi-gigahertz frequency comb-based interferometer exhibits only the interference amplitude peak without the phase fringes, which can produce a rapid axial scan for full-field profilometry and tomography. Despite huge technical advantages, there remain problems that the interference intensity undulations occurred depending on the interference phase. To avoid such problems, we propose a compensation technique of the interference signals using two frequency combs with slightly varied center wavelengths. The compensated full-field surface profile measurements of cover glass and onion skin were demonstrated experimentally to verify the advantages of the proposed method.

The Effect of Electron Beam Irradiation in Environmental Scanning Transmission Electron Microscopy of Whole Cells in Liquid.

PubMed

Hermannsdörfer, Justus; Tinnemann, Verena; Peckys, Diana B; de Jonge, Niels

2016-06-01

Whole cells can be studied in their native liquid environment using electron microscopy, and unique information about the locations and stoichiometry of individual membrane proteins can be obtained from many cells thus taking cell heterogeneity into account. Of key importance for the further development of this microscopy technology is knowledge about the effect of electron beam radiation on the samples under investigation. We used environmental scanning electron microscopy (ESEM) with scanning transmission electron microscopy (STEM) detection to examine the effect of radiation for whole fixed COS7 fibroblasts in liquid. The main observation was the localization of nanoparticle labels attached to epidermal growth factor receptors (EGFRs). It was found that the relative distances between the labels remained mostly unchanged (<1.5%) for electron doses ranging from the undamaged native state at 10 e-/Å2 toward 103 e-/Å2. This dose range was sufficient to determine the EGFR locations with nanometer resolution and to distinguish between monomers and dimers. Various different forms of radiation damage became visible at higher doses, including severe dislocation, and the dissolution of labels.

Analysis of liquid suspensions using scanning electron microscopy in transmission: estimation of the water film thickness using Monte-Carlo simulations.

PubMed

Xiao, J; Foray, G; Masenelli-Varlot, K

2018-02-01

Environmental scanning electron microscopy (ESEM) allows the observation of liquids under specific conditions of pressure and temperature. Moreover, when working in the transmission mode, that is in scanning transmission electron microscopy (STEM), nano-objects can be analysed inside a liquid. The contrast in the images is mass-thickness dependent as in STEM-in-TEM (transmission electron microscopy) using closed cells. However, in STEM-in-ESEM, as the liquid-vapour equilibrium is kept dynamically, the thickness of the water droplet remains unknown. In this paper, the contrasts measured in the experimental images are compared with calculations using Monte-Carlo simulations in order to estimate the thickness of water. Two examples are given. On gold nanoparticles, the thickness of a thick film can be estimated thanks to a contrast inversion. On core-shell latex particles, the grey level of the shell compared with those of the core and of the water film gives a relatively precise measurement of the water film thickness. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Topography and refractometry of nanostructures using spatial light interference microscopy (SLIM)

PubMed Central

Wang, Zhuo; Chun, Ik Su; Li, Xiuling; Ong, Zhun-Yong; Pop, Eric; Millet, Larry; Gillette, Martha; Popescu, Gabriel

2010-01-01

Spatial Light Interference Microscopy (SLIM) is a novel method developed in our laboratory that provides quantitative phase images of transparent structures with 0.3 nm spatial and 0.03 nm temporal accuracy owing to the white light illumination and its common path interferometric geometry. We exploit these features and demonstrate SLIM's ability to perform topography at a single atomic layer in graphene. Further, using a decoupling procedure that we developed for cylindrical structures, we extract the axially-averaged refractive index of semiconductor nanotubes and a neurite of a live hippocampal neuron in culture. We believe that this study will set the basis for novel high-throughput topography and refractometry of man-made and biological nanostructures. PMID:20081970

Compressed-sensing wavenumber-scanning interferometry

NASA Astrophysics Data System (ADS)

Bai, Yulei; Zhou, Yanzhou; He, Zhaoshui; Ye, Shuangli; Dong, Bo; Xie, Shengli

2018-01-01

The Fourier transform (FT), the nonlinear least-squares algorithm (NLSA), and eigenvalue decomposition algorithm (EDA) are used to evaluate the phase field in depth-resolved wavenumber-scanning interferometry (DRWSI). However, because the wavenumber series of the laser's output is usually accompanied by nonlinearity and mode-hop, FT, NLSA, and EDA, which are only suitable for equidistant interference data, often lead to non-negligible phase errors. In this work, a compressed-sensing method for DRWSI (CS-DRWSI) is proposed to resolve this problem. By using the randomly spaced inverse Fourier matrix and solving the underdetermined equation in the wavenumber domain, CS-DRWSI determines the nonuniform sampling and spectral leakage of the interference spectrum. Furthermore, it can evaluate interference data without prior knowledge of the object. The experimental results show that CS-DRWSI improves the depth resolution and suppresses sidelobes. It can replace the FT as a standard algorithm for DRWSI.

Sparse sampling and reconstruction for electron and scanning probe microscope imaging

DOEpatents

Anderson, Hyrum; Helms, Jovana; Wheeler, Jason W.; Larson, Kurt W.; Rohrer, Brandon R.

2015-07-28

Systems and methods for conducting electron or scanning probe microscopy are provided herein. In a general embodiment, the systems and methods for conducting electron or scanning probe microscopy with an undersampled data set include: driving an electron beam or probe to scan across a sample and visit a subset of pixel locations of the sample that are randomly or pseudo-randomly designated; determining actual pixel locations on the sample that are visited by the electron beam or probe; and processing data collected by detectors from the visits of the electron beam or probe at the actual pixel locations and recovering a reconstructed image of the sample.

Availability of feature-oriented scanning probe microscopy for remote-controlled measurements on board a space laboratory or planet exploration Rover.

PubMed

Lapshin, Rostislav V

2009-06-01

Prospects for a feature-oriented scanning (FOS) approach to investigations of sample surfaces, at the micrometer and nanometer scales, with the use of scanning probe microscopy under space laboratory or planet exploration rover conditions, are examined. The problems discussed include decreasing sensitivity of the onboard scanning probe microscope (SPM) to temperature variations, providing autonomous operation, implementing the capabilities for remote control, self-checking, self-adjustment, and self-calibration. A number of topical problems of SPM measurements in outer space or on board a planet exploration rover may be solved via the application of recently proposed FOS methods.

Pitting corrosion of titanium

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

Casillas, N.; Charlebois, S.; Smyrl, W.H.

1994-03-01

The breakdown of native and anodically grown oxide films on Ti electrodes is investigated by scanning electrochemical microscopy (SECM), video microscopy, transmission electron microscopy, and voltammetry. SECM is used to demonstrated that the oxidation of Br[sup [minus

Lightweight reduced graphene oxide-Fe3O4 nanoparticle composite in the quest for an excellent electromagnetic interference shielding material.

PubMed

Singh, Ashwani Kumar; Kumar, Ajit; Haldar, Krishna Kamal; Gupta, Vinay; Singh, Kedar

2018-06-15

This work reports a detailed study of reduced graphene oxide (rGO)-Fe 3 O 4 nanoparticle composite as an excellent electromagnetic (EM) interference shielding material in GHz range. A rGO-Fe 3 O 4 nanoparticle composite was synthesized using a facile, one step, and modified solvothermal method with the reaction of FeCl 3 , ethylenediamine and graphite oxide powder in the presence of ethylene glycol. Various structural, microstructural and optical characterization tools were used to determine its synthesis and various properties. Dielectric, magnetic and EM shielding parameters were also evaluated to estimate its performance as a shielding material for EM waves. X-ray diffraction patterns have provided information about the structural and crystallographic properties of the as-synthesized material. Scanning electron microscopy micrographs revealed the information regarding the exfoliation of graphite into rGO. Well-dispersed Fe 3 O 4 nanoparticles over the surface of the graphene can easily be seen by employing transmission electron microscopy. For comparison, rGO nanosheets and Fe 3 O 4 nanoparticles have also been synthesized and characterized in a similar fashion. A plot of the dielectric and magnetic characterizations provides some useful information related to various losses and the relaxation process. Shielding effectiveness due to reflection (SE R ), shielding effectiveness due to absorption (SE A ), and total shielding effectiveness (SE T ) were also plotted against frequency over a broad range (8-12 GHz). A significant change in all parameters (SE A value from 5 dB to 35 dB for Fe 3 O 4 nanoparticles to rGO-Fe 3 O 4 nanoparticle composite) was found. An actual shielding effectiveness (SE T ) up to 55 dB was found in the rGO-Fe 3 O 4 nanoparticle composite. These graphs give glimpses of how significantly this material shows shielding effectiveness over a broad range of frequency.

Lightweight reduced graphene oxide-Fe3O4 nanoparticle composite in the quest for an excellent electromagnetic interference shielding material

NASA Astrophysics Data System (ADS)

Singh, Ashwani Kumar; Kumar, Ajit; Kamal Haldar, Krishna; Gupta, Vinay; Singh, Kedar

2018-06-01

This work reports a detailed study of reduced graphene oxide (rGO)-Fe3O4 nanoparticle composite as an excellent electromagnetic (EM) interference shielding material in GHz range. A rGO-Fe3O4 nanoparticle composite was synthesized using a facile, one step, and modified solvothermal method with the reaction of FeCl3, ethylenediamine and graphite oxide powder in the presence of ethylene glycol. Various structural, microstructural and optical characterization tools were used to determine its synthesis and various properties. Dielectric, magnetic and EM shielding parameters were also evaluated to estimate its performance as a shielding material for EM waves. X-ray diffraction patterns have provided information about the structural and crystallographic properties of the as-synthesized material. Scanning electron microscopy micrographs revealed the information regarding the exfoliation of graphite into rGO. Well-dispersed Fe3O4 nanoparticles over the surface of the graphene can easily be seen by employing transmission electron microscopy. For comparison, rGO nanosheets and Fe3O4 nanoparticles have also been synthesized and characterized in a similar fashion. A plot of the dielectric and magnetic characterizations provides some useful information related to various losses and the relaxation process. Shielding effectiveness due to reflection (SER), shielding effectiveness due to absorption (SEA), and total shielding effectiveness (SET) were also plotted against frequency over a broad range (8–12 GHz). A significant change in all parameters (SEA value from 5 dB to 35 dB for Fe3O4 nanoparticles to rGO-Fe3O4 nanoparticle composite) was found. An actual shielding effectiveness (SET) up to 55 dB was found in the rGO-Fe3O4 nanoparticle composite. These graphs give glimpses of how significantly this material shows shielding effectiveness over a broad range of frequency.

Optimal lens design and use in laser-scanning microscopy

PubMed Central

Negrean, Adrian; Mansvelder, Huibert D.

2014-01-01

In laser-scanning microscopy often an off-the-shelf achromatic doublet is used as a scan lens which can reduce the available diffraction-limited field-of-view (FOV) by a factor of 3 and introduce chromatic aberrations that are scan angle dependent. Here we present several simple lens designs of superior quality that fully make use of high-NA low-magnification objectives, offering diffraction-limited imaging over a large FOV and wavelength range. We constructed a two-photon laser-scanning microscope with optimized custom lenses which had a near diffraction limit point-spread-function (PSF) with less than 3.6% variation over a 400 µm FOV and less than 0.5 µm lateral color between 750 and 1050 nm. PMID:24877017

Quantitative assessment of neural outgrowth using spatial light interference microscopy

NASA Astrophysics Data System (ADS)

Lee, Young Jae; Cintora, Pati; Arikkath, Jyothi; Akinsola, Olaoluwa; Kandel, Mikhail; Popescu, Gabriel; Best-Popescu, Catherine

2017-06-01

Optimal growth as well as branching of axons and dendrites is critical for the nervous system function. Neuritic length, arborization, and growth rate determine the innervation properties of neurons and define each cell's computational capability. Thus, to investigate the nervous system function, we need to develop methods and instrumentation techniques capable of quantifying various aspects of neural network formation: neuron process extension, retraction, stability, and branching. During the last three decades, fluorescence microscopy has yielded enormous advances in our understanding of neurobiology. While fluorescent markers provide valuable specificity to imaging, photobleaching, and photoxicity often limit the duration of the investigation. Here, we used spatial light interference microscopy (SLIM) to measure quantitatively neurite outgrowth as a function of cell confluence. Because it is label-free and nondestructive, SLIM allows for long-term investigation over many hours. We found that neurons exhibit a higher growth rate of neurite length in low-confluence versus medium- and high-confluence conditions. We believe this methodology will aid investigators in performing unbiased, nondestructive analysis of morphometric neuronal parameters.

Frequency dependence of tissue attenuation measured by acoustic microscopy.

PubMed

Daft, C M; Briggs, G A; O'Brien, W D

1989-05-01

Broadband scanning acoustic microscopy (SAM) has been used to investigate the mechanical properties of sections of tissue with a resolution of around 8 microns. The work reported here extends these results by reporting the frequency dependence of the attenuation coefficient from 100-500 MHz. A discussion of the theory of the measurements is presented. The scanning laser acoustic microscope (SLAM) is used to characterize similar tissue sections at 100 MHz. The data obtained with the two forms of acoustic microscopy are compared with results from the literature.

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

PubMed Central

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

2007-01-01

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

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.

Volumetric structured illumination microscopy enabled by tunable focus lens (Conference Presentation)

NASA Astrophysics Data System (ADS)

Hinsdale, Taylor; Malik, Bilal; Olsovsky, Cory; Jo, Javier A.; Maitland, Kristen C.

2016-03-01

We present a volumetric imaging method for biological tissue that is free of mechanically scanning components. The optical sectioning in the system is obtained by structured illumination microscopy (SIM) with the depth of focus being varied by the use of an electronic tunable-focus lens (ETL). The performance of the axial scanning mechanism was evaluated and characterized in conjunction with SIM to ensure volumetric images could be recorded and reconstructed without significant losses in optical section thickness and lateral resolution over the full desired scan range. It was demonstrated that sub-cellular image resolutions were obtainable in both microsphere films and in ex vivo oral mucosa, spanning multiple cell layers, without significant losses in image quality. The mechanism proposed here has the ability to be integrated into any wide-field microscopy system to convert it into a three-dimensional imaging platform without the need for axial scanning of the sample or imaging optics. The ability to axially scan independent of mechanical movement also provides the opportunity for the development of endoscopic systems which can create volumetric images of tissue in vivo.

Identification of nanoparticles and nanosystems in biological matrices with scanning probe microscopy.

PubMed

Angeloni, Livia; Reggente, Melania; Passeri, Daniele; Natali, Marco; Rossi, Marco

2018-04-17

Identification of nanoparticles and nanosystems into cells and biological matrices is a hot research topic in nanobiotechnologies. Because of their capability to map physical properties (mechanical, electric, magnetic, chemical, or optical), several scanning probe microscopy based techniques have been proposed for the subsurface detection of nanomaterials in biological systems. In particular, atomic force microscopy (AFM) can be used to reveal stiff nanoparticles in cells and other soft biomaterials by probing the sample mechanical properties through the acquisition of local indentation curves or through the combination of ultrasound-based methods, like contact resonance AFM (CR-AFM) or scanning near field ultrasound holography. Magnetic force microscopy can detect magnetic nanoparticles and other magnetic (bio)materials in nonmagnetic biological samples, while electric force microscopy, conductive AFM, and Kelvin probe force microscopy can reveal buried nanomaterials on the basis of the differences between their electric properties and those of the surrounding matrices. Finally, scanning near field optical microscopy and tip-enhanced Raman spectroscopy can visualize buried nanostructures on the basis of their optical and chemical properties. Despite at a still early stage, these methods are promising for detection of nanomaterials in biological systems as they could be truly noninvasive, would not require destructive and time-consuming specific sample preparation, could be performed in vitro, on alive samples and in water or physiological environment, and by continuously imaging the same sample could be used to dynamically monitor the diffusion paths and interaction mechanisms of nanomaterials into cells and biological systems. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Nanotechnology Approaches to Biology > Nanoscale Systems in Biology. © 2018 Wiley Periodicals, Inc.

Rapid Prototyping of a High Sensitivity Graphene Based Glucose Sensor Strip.

PubMed

Tehrani, Farshad; Reiner, Lisa; Bavarian, Behzad

2015-01-01

A rapid prototyping of an inexpensive, disposable graphene and copper nanocomposite sensor strip using polymeric flexible substrate for highly sensitive and selective nonenzymatic glucose detection has been developed and tested for direct oxidization of glucose. The CuNPs were electrochemically deposited on to the graphene sheets to improve electron transfer rates and to enhance electrocatalytic activity toward glucose. The graphene based electrode with CuNPs demonstrated a high degree of sensitivity (1101.3 ± 56 μA/mM.cm2), excellent selectivity (without an interference with Ascorbic Acid, Uric Acid, Dopamine, and Acetaminophen), good stability with a linear response to glucose ranging from 0.1 mM to 0.6 mM concentration, and detection limits of 0.025 mM to 0.9 mM. Characterization of the electrodes was performed by scanning electron microscopy (FESEM and SEM). The electrochemical properties of the modified graphene electrodes were inspected by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry.

Adhesion of the clay minerals montmorillonite, kaolinite, and attapulgite reduces respiration of Histoplasma capsulatum.

PubMed Central

Lavie, S; Stotzky, G

1986-01-01

The respiration of three phenotypes of Histoplasma capsulatum, the causal agent of histoplasmosis in humans, was markedly reduced by low concentrations of montmorillonite but was reduced less by even higher concentrations of kaolinite or attapulgite (palygorskite). The reduction in respiration followed a pattern that suggested saturation-type kinetics: an initial sharp reduction that occurred with low concentrations of clay (0.01 to 0.5% [wt/vol]), followed by a more gradual reduction with higher concentrations (1 to 8%). Increases in viscosity (which could impair the movement of O2) caused by the clays were not responsible for the reduction in respiration, and the clays did not interfere with the availability of nutrients. Scanning electron microscopy after extensive washing showed that the clay particles were tightly bound to the hyphae, suggesting that the clays reduced the rate of respiration of H. capsulatum by adhering to the mycelial surface and, thereby, interfered with the movement of nutrients, metabolites, and gases across the mycelial wall. Images PMID:3954340

Adhesion of the clay minerals montmorillonite, kaolinite, and attapulgite reduces respiration of Histoplasma capsulatum.

PubMed

Lavie, S; Stotzky, G

1986-01-01

The respiration of three phenotypes of Histoplasma capsulatum, the causal agent of histoplasmosis in humans, was markedly reduced by low concentrations of montmorillonite but was reduced less by even higher concentrations of kaolinite or attapulgite (palygorskite). The reduction in respiration followed a pattern that suggested saturation-type kinetics: an initial sharp reduction that occurred with low concentrations of clay (0.01 to 0.5% [wt/vol]), followed by a more gradual reduction with higher concentrations (1 to 8%). Increases in viscosity (which could impair the movement of O2) caused by the clays were not responsible for the reduction in respiration, and the clays did not interfere with the availability of nutrients. Scanning electron microscopy after extensive washing showed that the clay particles were tightly bound to the hyphae, suggesting that the clays reduced the rate of respiration of H. capsulatum by adhering to the mycelial surface and, thereby, interfered with the movement of nutrients, metabolites, and gases across the mycelial wall.

Concentration polarization-based nonlinear electrokinetics in porous media: induced-charge electroosmosis.

PubMed

Leinweber, Felix C; Tallarek, Ulrich

2005-11-24

We have investigated induced-charge electroosmotic flow in a fixed bed of ion-permselective glass beads by quantitative confocal laser scanning microscopy. Externally applied electrical fields induce concentration polarization (CP) in the porous medium due to coupled mass and charge transport normal to the charge-selective interfaces. These data reveal the generation of a nonequilibrium electrical double layer in the depleted CP zones and the adjoining anodic hemispheres of the (cation-selective) glass beads above a critical field strength. This initiates CP-based induced-charge electroosmosis along curved interfaces of the quasi-electroneutral macropore space between glass beads. Caused by mutual interference of resulting nonlinear flow with (flow-inducing) space charge regions, an electrohydrodynamic instability can appear locally and realize turbulent flow behavior at low Reynolds numbers. It is characterized by a local destruction of the CP zones and concomitant removal of diffusion-limited mass transfer. More efficient pore-scale lateral mixing also improves macroscopic transport, which is reflected in the significantly reduced axial dispersion of a passive tracer.

Quasiparticle interference mapping of ZrSiS

NASA Astrophysics Data System (ADS)

Lodge, Michael; Hosen, Md Mofazzle; Neupane, Madhab; Ishigami, Masa; Chang, Guoqing; Singh, Bahadur; Lin, Hsin; Weber, Bent; Hellerstedt, Jack; Edmonds, Mark; Fuhrer, Michael; Kaczorowski, Dariusz

The emergent class of 3D Dirac semimetals presents intriguing new systems in which to study the rich physics of the robust, topologically-protected quasiparticles hosted within their bulk. For example, in nodal-line Dirac semimetals, the conductance and valence bands meet along a closed loop in momentum space and disperse linearly in the vicinity of the resultant line node. This results in novel scattering phenomena, owing to the unique Fermi surfaces and scattering selection rules of these systems. Here, we have performed scanning tunneling microscopy and spectroscopy of ZrSiS, one such nodal-line Dirac semimetal,at 4.5 K. We have visualized quasiparticle scattering using differential conductance mapping. In conjunction with numerical modeling, we identify at least six allowed scattering vectors in the material, which gives insight into the scattering selection rules of these novel materials. This work is based upon research supported by the National Science Foundation under Grant No. 0955625 (MSL and MI) and Fellowship No. 1614303 (MSL), and by the Australian Research Council under DECRA Fellowship No. DE160101334 (BW).

Fusions between green fluorescent protein and beta-glucuronidase as sensitive and vital bifunctional reporters in plants.

PubMed

Quaedvlieg, N E; Schlaman, H R; Admiraal, P C; Wijting, S E; Stougaard, J; Spaink, H P

1998-07-01

By fusing the genes encoding green fluorescent protein (GFP) and beta-glucuronidase (GUS) we have created a set of bifunctional reporter constructs which are optimized for use in transient and stable expression studies in plants. This approach makes it possible to combine the advantage of GUS, its high sensitivity in histochemical staining, with the advantages of GFP as a vital marker. The fusion proteins were functional in transient expression studies in tobacco using either DNA bombardment or potato virus X as a vector, and in stably transformed Arabidopsis thaliana and Lotus japonicus plants. The results show that high level of expression does not interfere with efficient stable transformation in A. thaliana and L. japonicus. Using confocal laser scanning microscopy we show that the fusion constructs are very suitable for promoter expression studies in all organs of living plants, including root nodules. The use of these reporter constructs in the model legume L. japonicus offers exciting new possibilities for the study of the root nodulation process.

Fusions between green fluorescent protein and beta-glucuronidase as sensitive and vital bifunctional reporters in plants.

PubMed

Quaedvlieg, N E; Schlaman, H R; Admiraal, P C; Wijting, S E; Stougaard, J; Spaink, H P

1998-11-01

By fusing the genes encoding green fluorescent protein (GFP) and beta-glucuronidase (GUS) we have created a set of bifunctional reporter constructs which are optimized for use in transient and stable expression studies in plants. This approach makes it possible to combine the advantage of GUS, its high sensitivity in histochemical staining, with the advantages of GFP as a vital marker. The fusion proteins were functional in transient expression studies in tobacco using either DNA bombardment or potato virus X as a vector, and in stably transformed Arabidopsis thaliana and Lotus japonicus plants. The results show that high level of expression does not interfere with efficient stable transformation in A. thaliana and L. japonicus. Using confocal laser scanning microscopy we show that the fusion constructs are very suitable for promoter expression studies in all organs of living plants, including root nodules. The use of these reporter constructs in the model legume L. japonicus offers exciting new possibilities for the study of the root nodulation process.

Rapid Prototyping of a High Sensitivity Graphene Based Glucose Sensor Strip

PubMed Central

Tehrani, Farshad; Reiner, Lisa; Bavarian, Behzad

2015-01-01

A rapid prototyping of an inexpensive, disposable graphene and copper nanocomposite sensor strip using polymeric flexible substrate for highly sensitive and selective nonenzymatic glucose detection has been developed and tested for direct oxidization of glucose. The CuNPs were electrochemically deposited on to the graphene sheets to improve electron transfer rates and to enhance electrocatalytic activity toward glucose. The graphene based electrode with CuNPs demonstrated a high degree of sensitivity (1101.3±56 μA/mM.cm2), excellent selectivity (without an interference with Ascorbic Acid, Uric Acid, Dopamine, and Acetaminophen), good stability with a linear response to glucose ranging from 0.1 mM to 0.6 mM concentration, and detection limits of 0.025 mM to 0.9 mM. Characterization of the electrodes was performed by scanning electron microscopy (FESEM and SEM). The electrochemical properties of the modified graphene electrodes were inspected by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry. PMID:26678700

Sn-doped Bi 1.1Sb 0.9Te 2S bulk crystal topological insulator with excellent properties

DOE PAGES

S. K. Kushwaha; Pletikosic, I.; Liang, T.; ...

2016-04-27

A long-standing issue in topological insulator research has been to find a bulk single crystal material that provides a high quality platform for characterizing topological surface states without interference from bulk electronic states. This material would ideally be a bulk insulator, have a surface state Dirac point energy well isolated from the bulk valence and conduction bands, display quantum oscillations from the surface state electrons, and be growable as large, high quality bulk single crystals. Here we show that this materials obstacle is overcome by bulk crystals of lightly Sn-doped Bi 1.1Sb 0.9Te 2S grown by the Vertical Bridgeman method.more » We characterize Sn-BSTS via angle-resolved photoemission spectroscopy, scanning tunneling microscopy, transport studies, X-ray diffraction, and Raman scattering. We present this material as a high quality topological insulator that can be reliably grown as bulk single crystals and thus studied by many researchers interested in topological surface states.« less

Ripple-modulated electronic structure of a 3D topological insulator.

PubMed

Okada, Yoshinori; Zhou, Wenwen; Walkup, D; Dhital, Chetan; Wilson, Stephen D; Madhavan, V

2012-01-01

Three-dimensional topological insulators host linearly dispersing states with unique properties and a strong potential for applications. An important ingredient in realizing some of the more exotic states in topological insulators is the ability to manipulate local electronic properties. Direct analogy to the Dirac material graphene suggests that a possible avenue for controlling local properties is via a controlled structural deformation such as the formation of ripples. However, the influence of such ripples on topological insulators is yet to be explored. Here we use scanning tunnelling microscopy to determine the effects of one-dimensional buckling on the electronic properties of Bi(2)Te(3.) By tracking spatial variations of the interference patterns generated by the Dirac electrons we show that buckling imposes a periodic potential, which locally modulates the surface-state dispersion. This suggests that forming one- and two-dimensional ripples is a viable method for creating nanoscale potential landscapes that can be used to control the properties of Dirac electrons in topological insulators.

In situ fabrication of quasi-free-standing epitaxial graphene nanoflakes on gold.

PubMed

Leicht, Philipp; Zielke, Lukas; Bouvron, Samuel; Moroni, Riko; Voloshina, Elena; Hammerschmidt, Lukas; Dedkov, Yuriy S; Fonin, Mikhail

2014-04-22

Addressing the multitude of electronic phenomena theoretically predicted for confined graphene structures requires appropriate in situ fabrication procedures yielding graphene nanoflakes (GNFs) with well-defined geometries and accessible electronic properties. Here, we present a simple strategy to fabricate quasi-free-standing GNFs of variable sizes, performing temperature programmed growth of graphene flakes on the Ir(111) surface and subsequent intercalation of gold. Using scanning tunneling microscopy (STM), we show that epitaxial GNFs on a perfectly ordered Au(111) surface are formed while maintaining an unreconstructed, singly hydrogen-terminated edge structure, as confirmed by the accompanying density functional theory (DFT) calculations. Using tip-induced lateral displacement of GNFs, we demonstrate that GNFs on Au(111) are to a large extent decoupled from the Au(111) substrate. The direct accessibility of the electronic states of a single GNF is demonstrated upon analysis of the quasiparticle interference patterns obtained by low-temperature STM. These findings open up an interesting playground for diverse investigations of graphene nanostructures with possible implications for device fabrication.

Use of CdS quantum dot-functionalized cellulose nanocrystal films for anti-counterfeiting applications.

PubMed

Chen, L; Lai, C; Marchewka, R; Berry, R M; Tam, K C

2016-07-21

Structural colors and photoluminescence have been widely used for anti-counterfeiting and security applications. We report for the first time the use of CdS quantum dot (QD)-functionalized cellulose nanocrystals (CNCs) as building blocks to fabricate nanothin films via layer-by-layer (LBL) self-assembly for anti-counterfeiting applications. Both negatively- and positively-charged CNC/QD nanohybrids with a high colloidal stability and a narrow particle size distribution were prepared. The controllable LBL coating process was characterized by scanning electron microscopy and ellipsometry. The rigid structure of CNCs leads to nanoporous structured films on poly(ethylene terephthalate) (PET) substrates with high transmittance (above 70%) over the entire range of visible light and also resulted in increased hydrophilicity (contact angles of ∼40 degrees). Nanothin films on PET substrates showed good flexibility and enhanced stability in both water and ethanol. The modified PET films with structural colors from thin-film interference and photoluminescence from QDs can be used in anti-counterfeiting applications.

Accuracy of parameter estimates for closely spaced optical targets using multiple detectors

NASA Astrophysics Data System (ADS)

Dunn, K. P.

1981-10-01

In order to obtain the cross-scan position of an optical target, more than one scanning detector is used. As expected, the cross-scan position estimation performance degrades when two nearby optical targets interfere with each other. Theoretical bounds on the two-dimensional parameter estimation performance for two closely spaced optical targets are found. Two particular classes of scanning detector arrays, namely, the crow's foot and the brickwall (or mosaic) patterns, are considered.

Two Simple Classroom Demonstrations for Scanning Probe Microscopy Based on a Macroscopic Analogy

ERIC Educational Resources Information Center

Hajkova, Zdenka; Fejfar, Antonin; Smejkal, Petr

2013-01-01

This article describes two simple classroom demonstrations that illustrate the principles of scanning probe microscopy (SPM) based on a macroscopic analogy. The analogy features the bumps in an egg carton to represent the atoms on a chemical surface and a probe that can be represented by a dwarf statue (illustrating an origin of the prefix…

Chemical Characterization of Outdoor and Subway Fine (PM2.5-1.0) and Coarse (PM10-2.5) Particulate Matter in Seoul (Korea) Computer-Controlled Scanning Electron Microscopy (CCSEM)

EPA Science Inventory

Outdoor and indoor (subway) samples were collected by passive sampling in urban Seoul and analyzed with computer-controlled scanning electron microscopy coupled with energy dispersive x-ray spectroscopy (CCSEM-EDX). Soil/road dust particles accounted for 42-60% (by weight) of fin...

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

Band excitation method applicable to scanning probe microscopy

DOEpatents

Jesse, Stephen; Kalinin, Sergei V.

2015-08-04

Scanning probe microscopy may include a method for generating a band excitation (BE) signal and simultaneously exciting a probe at a plurality of frequencies within a predetermined frequency band based on the excitation signal. A response of the probe is measured across a subset of frequencies of the predetermined frequency band and the excitation signal is adjusted based on the measured response.

Band excitation method applicable to scanning probe microscopy

DOEpatents

Jesse, Stephen; Kalinin, Sergei V.

2017-01-03

Scanning probe microscopy may include a method for generating a band excitation (BE) signal and simultaneously exciting a probe at a plurality of frequencies within a predetermined frequency band based on the excitation signal. A response of the probe is measured across a subset of frequencies of the predetermined frequency band and the excitation signal is adjusted based on the measured response.

Scalp imaging techniques

NASA Astrophysics Data System (ADS)

Otberg, Nina; Shapiro, Jerry; Lui, Harvey; Wu, Wen-Yu; Alzolibani, Abdullateef; Kang, Hoon; Richter, Heike; Lademann, Jürgen

2017-05-01

Scalp imaging techniques are necessary tools for the trichological practice and for visualization of permeation, penetration and absorption processes into and through the scalp and for the research on drug delivery and toxicology. The present letter reviews different scalp imaging techniques and discusses their utility. Moreover, two different studies on scalp imaging techniques are presented in this letter: (1) scalp imaging with phototrichograms in combination with laser scanning microscopy, and (2) follicular measurements with cyanoacrylate surface replicas and light microscopy in combination with laser scanning microscopy. The experiments compare different methods for the determination of hair density on the scalp and different follicular measures. An average terminal hair density of 132 hairs cm-2 was found in 6 Caucasian volunteers and 135 hairs cm-2 in 6 Asian volunteers. The area of the follicular orifices accounts to 16.3% of the skin surface on average measured with laser scanning microscopy images. The potential volume of the follicular infundibulum was calculated based on the laser scanning measurements and is found to be 4.63 mm3 per cm2 skin on average. The experiments show that hair follicles are quantitatively relevant pathways and potential reservoirs for topically applied drugs and cosmetics.

Cross-section imaging and p-type doping assessment of ZnO/ZnO:Sb core-shell nanowires by scanning capacitance microscopy and scanning spreading resistance microscopy

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

Wang, Lin, E-mail: lin.wang@insa-lyon.fr; Brémond, Georges; Sallet, Vincent

2016-08-29

ZnO/ZnO:Sb core-shell structured nanowires (NWs) were grown by the metal organic chemical vapor deposition method where the shell was doped with antimony (Sb) in an attempt to achieve ZnO p-type conduction. To directly investigate the Sb doping effect in ZnO, scanning capacitance microscopy (SCM) and scanning spreading resistance microscopy (SSRM) were performed on the NWs' cross-sections mapping their two dimensional (2D) local electrical properties. Although no direct p-type inversion in ZnO was revealed, a lower net electron concentration was pointed out for the Sb-doped ZnO shell layer with respect to the non-intentionally doped ZnO core, indicating an evident compensating effectmore » as a result of the Sb incorporation, which can be ascribed to the formation of Sb-related acceptors. The results demonstrate SCM/SSRM investigation being a direct and effective approach for characterizing radial semiconductor one-dimensional (1D) structures and, particularly, for the doping study on the ZnO nanomaterial towards its p-type realization.« less

New Insights into Mutable Collagenous Tissue: Correlations between the Microstructure and Mechanical State of a Sea-Urchin Ligament

PubMed Central

Ribeiro, Ana R.; Barbaglio, Alice; Benedetto, Cristiano D.; Ribeiro, Cristina C.; Wilkie, Iain C.; Carnevali, Maria D. C.; Barbosa, Mário A.

2011-01-01

The mutable collagenous tissue (MCT) of echinoderms has the ability to undergo rapid and reversible changes in passive mechanical properties that are initiated and modulated by the nervous system. Since the mechanism of MCT mutability is poorly understood, the aim of this work was to provide a detailed morphological analysis of a typical mutable collagenous structure in its different mechanical states. The model studied was the compass depressor ligament (CDL) of a sea urchin (Paracentrotus lividus), which was characterized in different functional states mimicking MCT mutability. Transmission electron microscopy, histochemistry, cryo-scanning electron microscopy, focused ion beam/scanning electron microscopy, and field emission gun-environmental scanning electron microscopy were used to visualize CDLs at the micro- and nano-scales. This investigation has revealed previously unreported differences in both extracellular and cellular constituents, expanding the current knowledge of the relationship between the organization of the CDL and its mechanical state. Scanning electron microscopies in particular provided a three-dimensional overview of CDL architecture at the micro- and nano-scales, and clarified the micro-organization of the ECM components that are involved in mutability. Further evidence that the juxtaligamental cells are the effectors of these changes in mechanical properties was provided by a correlation between their cytology and the tensile state of the CDLs. PMID:21935473

Sheet-scanned dual-axis confocal microscopy using Richardson-Lucy deconvolution.

PubMed

Wang, D; Meza, D; Wang, Y; Gao, L; Liu, J T C

2014-09-15

We have previously developed a line-scanned dual-axis confocal (LS-DAC) microscope with subcellular resolution suitable for high-frame-rate diagnostic imaging at shallow depths. Due to the loss of confocality along one dimension, the contrast (signal-to-background ratio) of a LS-DAC microscope is deteriorated compared to a point-scanned DAC microscope. However, by using a sCMOS camera for detection, a short oblique light-sheet is imaged at each scanned position. Therefore, by scanning the light sheet in only one dimension, a thin 3D volume is imaged. Both sequential two-dimensional deconvolution and three-dimensional deconvolution are performed on the thin image volume to improve the resolution and contrast of one en face confocal image section at the center of the volume, a technique we call sheet-scanned dual-axis confocal (SS-DAC) microscopy.

Local carrier distribution imaging on few-layer MoS2 exfoliated on SiO2 by scanning nonlinear dielectric microscopy

NASA Astrophysics Data System (ADS)

Yamasue, Kohei; Cho, Yasuo

2018-06-01

We demonstrate that scanning nonlinear dielectric microscopy (SNDM) can be used for the nanoscale characterization of dominant carrier distribution on atomically thin MoS2 mechanically exfoliated on SiO2. For stable imaging without damaging microscopy tips and samples, SNDM was combined with peak-force tapping mode atomic force microscopy. The identification of dominant carriers and their spatial distribution becomes possible even for single and few-layer MoS2 on SiO2 using the proposed method allowing differential capacitance (dC/dV) imaging. We can expect that SNDM can also be applied to the evaluation of other two-dimensional semiconductors and devices.

Scanning tunneling spectroscopy under large current flow through the sample.

PubMed

Maldonado, A; Guillamón, I; Suderow, H; Vieira, S

2011-07-01

We describe a method to make scanning tunneling microscopy/spectroscopy imaging at very low temperatures while driving a constant electric current up to some tens of mA through the sample. It gives a new local probe, which we term current driven scanning tunneling microscopy/spectroscopy. We show spectroscopic and topographic measurements under the application of a current in superconducting Al and NbSe(2) at 100 mK. Perspective of applications of this local imaging method includes local vortex motion experiments, and Doppler shift local density of states studies.

Remote focusing for programmable multi-layer differential multiphoton microscopy

PubMed Central

Hoover, Erich E.; Young, Michael D.; Chandler, Eric V.; Luo, Anding; Field, Jeffrey J.; Sheetz, Kraig E.; Sylvester, Anne W.; Squier, Jeff A.

2010-01-01

We present the application of remote focusing to multiphoton laser scanning microscopy and utilize this technology to demonstrate simultaneous, programmable multi-layer imaging. Remote focusing is used to independently control the axial location of multiple focal planes that can be simultaneously imaged with single element detection. This facilitates volumetric multiphoton imaging in scattering specimens and can be practically scaled to a large number of focal planes. Further, it is demonstrated that the remote focusing control can be synchronized with the lateral scan directions, enabling imaging in orthogonal scan planes. PMID:21326641

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.

Qualitative and quantitative interpretation of SEM image using digital image processing.

PubMed

Saladra, Dawid; Kopernik, Magdalena

2016-10-01

The aim of the this study is improvement of qualitative and quantitative analysis of scanning electron microscope micrographs by development of computer program, which enables automatic crack analysis of scanning electron microscopy (SEM) micrographs. Micromechanical tests of pneumatic ventricular assist devices result in a large number of micrographs. Therefore, the analysis must be automatic. Tests for athrombogenic titanium nitride/gold coatings deposited on polymeric substrates (Bionate II) are performed. These tests include microshear, microtension and fatigue analysis. Anisotropic surface defects observed in the SEM micrographs require support for qualitative and quantitative interpretation. Improvement of qualitative analysis of scanning electron microscope images was achieved by a set of computational tools that includes binarization, simplified expanding, expanding, simple image statistic thresholding, the filters Laplacian 1, and Laplacian 2, Otsu and reverse binarization. Several modifications of the known image processing techniques and combinations of the selected image processing techniques were applied. The introduced quantitative analysis of digital scanning electron microscope images enables computation of stereological parameters such as area, crack angle, crack length, and total crack length per unit area. This study also compares the functionality of the developed computer program of digital image processing with existing applications. The described pre- and postprocessing may be helpful in scanning electron microscopy and transmission electron microscopy surface investigations. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

Volumetry of human taste buds using laser scanning microscopy.

PubMed

Just, T; Srur, E; Stachs, O; Pau, H W

2009-10-01

In vivo laser scanning confocal microscopy is a relatively new, non-invasive method for assessment of oral cavity epithelia. The penetration depth of approximately 200-400 microm allows visualisation of fungiform papillae and their taste buds. This paper describes the technique of in vivo volumetry of human taste buds. Confocal laser scanning microscopy used a diode laser at 670 nm for illumination. Digital laser scanning confocal microscopy equipment consisted of the Heidelberg Retina Tomograph HRTII and the Rostock Cornea Module. Volume scans of fungiform papillae were used for three-dimensional reconstruction of the taste bud. This technique supplied information on taste bud structure and enabled measurement and calculation of taste bud volume. Volumetric data from a 23-year-old man over a nine-day period showed only a small deviation in values. After three to four weeks, phenomenological changes in taste bud structures were found (i.e. a significant increase in volume, followed by disappearance of the taste bud and appearance of a new taste bud). The data obtained indicate the potential application of this non-invasive imaging modality: to evaluate variation of taste bud volume in human fungiform papillae with ageing; to study the effects of chorda tympani nerve transection on taste bud volume; and to demonstrate recovery of taste buds in patients with a severed chorda tympani nerve who show recovery of gustatory sensibility after surgery.

Direct observation of iron-induced conformational changes of mitochondrial DNA by high-resolution field-emission in-lens scanning electron microscopy.

PubMed Central

Yaffee, M; Walter, P; Richter, C; Müller, M

1996-01-01

When respiring rat liver mitochondria are incubated in the presence of Fe(III) gluconate, their DNA (mtDNA) relaxes from the supercoiled to the open circular form dependent on the iron dose. Anaerobiosis or antioxidants fail to completely inhibit the unwinding. High-resolution field-emission in-lens scanning electron microscopy imaging, in concert with backscattered electron detection, pinpoints nanometer-range iron colloids bound to mtDNA isolated from iron-exposed mitochondria. High-resolution field-emission in-lens scanning electron microscopy with backscattered electron detection imaging permits simultaneous detailed visual analysis of DNA topology, iron dose-dependent mtDNA unwinding, and assessment of iron colloid formation on mtDNA strands. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8643576

Seeing through walls at the nanoscale: Microwave microscopy of enclosed objects and processes in liquids

DOE PAGES

Velmurugan, Jeyavel; Kalinin, Sergei V.; Kolmakov, Andrei; ...

2016-02-11

Here, noninvasive in situ nanoscale imaging in liquid environments is a current imperative in the analysis of delicate biomedical objects and electrochemical processes at reactive liquid–solid interfaces. Microwaves of a few gigahertz frequencies offer photons with energies of ≈10 μeV, which can affect neither electronic states nor chemical bonds in condensed matter. Here, we describe an implementation of scanning near-field microwave microscopy for imaging in liquids using ultrathin molecular impermeable membranes separating scanning probes from samples enclosed in environmental cells. We imaged a model electroplating reaction as well as individual live cells. Through a side-by-side comparison of the microwave imagingmore » with scanning electron microscopy, we demonstrate the advantage of microwaves for artifact-free imaging.« less

PtyNAMi: ptychographic nano-analytical microscope at PETRA III: interferometrically tracking positions for 3D x-ray scanning microscopy using a ball-lens retroreflector

NASA Astrophysics Data System (ADS)

Schroer, Christian G.; Seyrich, Martin; Kahnt, Maik; Botta, Stephan; Döhrmann, Ralph; Falkenberg, Gerald; Garrevoet, Jan; Lyubomirskiy, Mikhail; Scholz, Maria; Schropp, Andreas; Wittwer, Felix

2017-09-01

In recent years, ptychography has revolutionized x-ray microscopy in that it is able to overcome the diffraction limit of x-ray optics, pushing the spatial resolution limit down to a few nanometers. However, due to the weak interaction of x rays with matter, the detection of small features inside a sample requires a high coherent fluence on the sample, a high degree of mechanical stability, and a low background signal from the x-ray microscope. The x-ray scanning microscope PtyNAMi at PETRA III is designed for high-spatial-resolution 3D imaging with high sensitivity. The design concept is presented with a special focus on real-time metrology of the sample position during tomographic scanning microscopy.

Is phase measurement necessary for incoherent holographic 3D imaging?

NASA Astrophysics Data System (ADS)

Rosen, Joseph; Vijayakumar, A.; Rai, Mani Ratnam; Mukherjee, Saswata

2018-02-01

Incoherent digital holography can be used for several applications, among which are high resolution fluorescence microscopy and imaging through a scattering medium. Historically, an incoherent digital hologram has been usually recorded by self-interference systems in which both interfering beams are originated from the same observed object. The self-interference system enables to read the phase distribution of the wavefronts propagating from an object and consequently to decode the 3D location of the object points. In this presentation, we survey several cases in which 3D holographic imaging can be done without the phase information and without two-wave interference.

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

PubMed

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

2012-01-01

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

Gold Nanoparticle Quantitation by Whole Cell Tomography.

PubMed

Sanders, Aric W; Jeerage, Kavita M; Schwartz, Cindi L; Curtin, Alexandra E; Chiaramonti, Ann N

2015-12-22

Many proposed biomedical applications for engineered gold nanoparticles require their incorporation by mammalian cells in specific numbers and locations. Here, the number of gold nanoparticles inside of individual mammalian stem cells was characterized using fast focused ion beam-scanning electron microscopy based tomography. Enhanced optical microscopy was used to provide a multiscale map of the in vitro sample, which allows cells of interest to be identified within their local environment. Cells were then serially sectioned using a gallium ion beam and imaged using a scanning electron beam. To confirm the accuracy of single cross sections, nanoparticles in similar cross sections were imaged using transmission electron microscopy and scanning helium ion microscopy. Complete tomographic series were then used to count the nanoparticles inside of each cell and measure their spatial distribution. We investigated the influence of slice thickness on counting single particles and clusters as well as nanoparticle packing within clusters. For 60 nm citrate stabilized particles, the nanoparticle cluster packing volume is 2.15 ± 0.20 times the volume of the bare gold nanoparticles.

Environmental scanning electron microscopy in cell biology.

PubMed

McGregor, J E; Staniewicz, L T L; Guthrie Neé Kirk, S E; Donald, A M

2013-01-01

Environmental scanning electron microscopy (ESEM) (1) is an imaging technique which allows hydrated, insulating samples to be imaged under an electron beam. The resolution afforded by this technique is higher than conventional optical microscopy but lower than conventional scanning electron microscopy (CSEM). The major advantage of the technique is the minimal sample preparation needed, making ESEM quick to use and the images less susceptible to the artifacts that the extensive sample preparation usually required for CSEM may introduce. Careful manipulation of both the humidity in the microscope chamber and the beam energy are nevertheless essential to prevent dehydration and beam damage artifacts. In some circumstances it is possible to image live cells in the ESEM (2).In the following sections we introduce the fundamental principles of ESEM imaging before presenting imaging protocols for plant epidermis, mammalian cells, and bacteria. In the first two cases samples are imaged using the secondary electron (topographic) signal, whereas a transmission technique is employed to image bacteria.

Scanning electron microscopy study of adhesion in sea urchin blastulae. M.S. Thesis

NASA Technical Reports Server (NTRS)

Crowther, Susan D.

1988-01-01

The dissociation supernatant (DS) isolated by disaggregating Strongylocentrotus purpuratus blastulae in calcium- and magnesium-free seawater specifically promotes reaggregation of S. purpuratus blastula cells. The purpose of this study was to use scanning electron microscopy to examine the gross morphology of aggregates formed in the presence of DS to see if it resembles adhesion in partially dissociated blastulae. A new reaggregation procedure developed here, using large volumes of cell suspension and a large diameter of rotation, was utilized to obtain sufficient quantities of aggregates for scanning electron microscopy. The results indicate that aggregates formed in the presence of DS resemble partially dissociated intact embryos in terms of the direct cell-cell adhesion observed. DS did not cause aggregation to form as a result of the entrapment of cells in masses of extracellular material. These studies provide the groundwork for further studies using transmission electron microscopy to more precisely define the adhesive contacts made by cells in the presence of the putative adhesion molecules present in DS.

Thermally oxidized Inconel 600 and 690 nickel-based alloys characterizations by combination of global photoelectrochemistry and local near-field microscopy techniques (STM, STS, AFM, SKPFM)

NASA Astrophysics Data System (ADS)

Mechehoud, F.; Benaioun, N. E.; Hakiki, N. E.; Khelil, A.; Simon, L.; Bubendorff, J. L.

2018-03-01

Thermally oxidized nickel-based alloys are studied by scanning tunnelling microscopy (STM), scanning tunnelling spectroscopy (STS), atomic force microscopy (AFM), scanning kelvin probe force microscopy (SKPFM) and photoelectro-chemical techniques as a function of oxidation time at a fixed temperature of 623 K. By photoelectrochemistry measurements we identify the formation of three oxides NiO, Fe2O3, Cr2O3 and determine the corresponding gap values. We use these values as parameter for imaging the surface at high bias voltage by STM allowing the spatial localization and identification of both NiO, Fe2O3 oxide phases using STS measurements. Associated to Kelvin probe measurements we show also that STS allow to distinguished NiO from Cr2O3 and confirm that the Cr2O3 is not visible at the surface and localized at the oxide/steel interface.

Epidermal growth factor receptor subunit locations determined in hydrated cells with environmental scanning electron microscopy.

PubMed

Peckys, Diana B; Baudoin, Jean-Pierre; Eder, Magdalena; Werner, Ulf; de Jonge, Niels

2013-01-01

Imaging single epidermal growth factor receptors (EGFR) in intact cells is presently limited by the available microscopy methods. Environmental scanning electron microscopy (ESEM) of whole cells in hydrated state in combination with specific labeling with gold nanoparticles was used to localize activated EGFRs in the plasma membranes of COS7 and A549 cells. The use of a scanning transmission electron microscopy (STEM) detector yielded a spatial resolution of 3 nm, sufficient to identify the locations of individual EGFR dimer subunits. The sizes and distribution of dimers and higher order clusters of EGFRs were determined. The distance between labels bound to dimers amounted to 19 nm, consistent with a molecular model. A fraction of the EGFRs was found in higher order clusters with sizes ranging from 32-56 nm. ESEM can be used for quantitative whole cell screening studies of membrane receptors, and for the study of nanoparticle-cell interactions in general.

Epidermal growth factor receptor subunit locations determined in hydrated cells with environmental scanning electron microscopy

PubMed Central

Peckys, Diana B.; Baudoin, Jean-Pierre; Eder, Magdalena; Werner, Ulf; de Jonge, Niels

2013-01-01

Imaging single epidermal growth factor receptors (EGFR) in intact cells is presently limited by the available microscopy methods. Environmental scanning electron microscopy (ESEM) of whole cells in hydrated state in combination with specific labeling with gold nanoparticles was used to localize activated EGFRs in the plasma membranes of COS7 and A549 cells. The use of a scanning transmission electron microscopy (STEM) detector yielded a spatial resolution of 3 nm, sufficient to identify the locations of individual EGFR dimer subunits. The sizes and distribution of dimers and higher order clusters of EGFRs were determined. The distance between labels bound to dimers amounted to 19 nm, consistent with a molecular model. A fraction of the EGFRs was found in higher order clusters with sizes ranging from 32–56 nm. ESEM can be used for quantitative whole cell screening studies of membrane receptors, and for the study of nanoparticle-cell interactions in general. PMID:24022088

Optical toolkits for in vivo deep tissue laser scanning microscopy: a primer

NASA Astrophysics Data System (ADS)

Lee, Woei Ming; McMenamin, Thomas; Li, Yongxiao

2018-06-01

Life at the microscale is animated and multifaceted. The impact of dynamic in vivo microscopy in small animals has opened up opportunities to peer into a multitude of biological processes at the cellular scale in their native microenvironments. Laser scanning microscopy (LSM) coupled with targeted fluorescent proteins has become an indispensable tool to enable dynamic imaging in vivo at high temporal and spatial resolutions. In the last few decades, the technique has been translated from imaging cells in thin samples to mapping cells in the thick biological tissue of living organisms. Here, we sought to provide a concise overview of the design considerations of a LSM that enables cellular and subcellular imaging in deep tissue. Individual components under review include: long working distance microscope objectives, laser scanning technologies, adaptive optics devices, beam shaping technologies and photon detectors, with an emphasis on more recent advances. The review will conclude with the latest innovations in automated optical microscopy, which would impact tracking and quantification of heterogeneous populations of cells in vivo.

Facile Preparation of a Platinum Silicide Nanoparticle-Modified Tip Apex for Scanning Kelvin Probe Microscopy.

PubMed

Lin, Chun-Ting; Chen, Yu-Wei; Su, James; Wu, Chien-Ting; Hsiao, Chien-Nan; Shiao, Ming-Hua; Chang, Mao-Nan

2015-12-01

In this study, we propose an ultra-facile approach to prepare a platinum silicide nanoparticle-modified tip apex (PSM tip) used for scanning Kelvin probe microscopy (SKPM). We combined a localized fluoride-assisted galvanic replacement reaction (LFAGRR) and atmospheric microwave annealing (AMA) to deposit a single platinum silicide nanoparticle with a diameter of 32 nm on the apex of a bare silicon tip of atomic force microscopy (AFM). The total process was completed in an ambient environment in less than 3 min. The improved potential resolution in the SKPM measurement was verified. Moreover, the resolution of the topography is comparable to that of a bare silicon tip. In addition, the negative charges found on the PSM tips suggest the possibility of exploring the use of current PSM tips to sense electric fields more precisely. The ultra-fast and cost-effective preparation of the PSM tips provides a new direction for the preparation of functional tips for scanning probe microscopy.

Image correlation microscopy for uniform illumination.

PubMed

Gaborski, T R; Sealander, M N; Ehrenberg, M; Waugh, R E; McGrath, J L

2010-01-01

Image cross-correlation microscopy is a technique that quantifies the motion of fluorescent features in an image by measuring the temporal autocorrelation function decay in a time-lapse image sequence. Image cross-correlation microscopy has traditionally employed laser-scanning microscopes because the technique emerged as an extension of laser-based fluorescence correlation spectroscopy. In this work, we show that image correlation can also be used to measure fluorescence dynamics in uniform illumination or wide-field imaging systems and we call our new approach uniform illumination image correlation microscopy. Wide-field microscopy is not only a simpler, less expensive imaging modality, but it offers the capability of greater temporal resolution over laser-scanning systems. In traditional laser-scanning image cross-correlation microscopy, lateral mobility is calculated from the temporal de-correlation of an image, where the characteristic length is the illuminating laser beam width. In wide-field microscopy, the diffusion length is defined by the feature size using the spatial autocorrelation function. Correlation function decay in time occurs as an object diffuses from its original position. We show that theoretical and simulated comparisons between Gaussian and uniform features indicate the temporal autocorrelation function depends strongly on particle size and not particle shape. In this report, we establish the relationships between the spatial autocorrelation function feature size, temporal autocorrelation function characteristic time and the diffusion coefficient for uniform illumination image correlation microscopy using analytical, Monte Carlo and experimental validation with particle tracking algorithms. Additionally, we demonstrate uniform illumination image correlation microscopy analysis of adhesion molecule domain aggregation and diffusion on the surface of human neutrophils.

Fabrication of sapphire-based high performance step-edge HTS Josephson junctions and SQUIDs and their application to scanning SQUID microscopy

NASA Astrophysics Data System (ADS)

Ming, Bin

Josephson junctions are at the heart of any superconductor device applications. A SQUID (Superconducting Quantum Interference Device), which consists of two Josephson junctions, is by far the most important example. Unfortunately, in the case of high-Tc superconductors (HTS), the quest for a robust, flexible, and high performance junction technology is yet far from the end. Currently, the only proven method to make HTS junctions is the SrTiO3(STO)-based bicrystal technology. In this thesis we concentrate on the fabrication of YBCO step-edge junctions and SQUIDs on sapphire. The step-edge method provides complete control of device locations and facilitates sophisticated, high-density layout. We select CeO2 as the buffer layer, as the key step to make device quality YBCO thin films on sapphire. With an "overhang" shadow mask produced by a novel photolithography technique, a steep step edge was fabricated on the CeO2 buffer layer by Ar+ ion milling with optimized parameters for minimum ion beam divergence. The step angle was determined to be in excess of 80° by atomic force microscopy (AFM). Josephson junctions patterned from those step edges exhibited resistively shunted junction (RSJ) like current-voltage characteristics. IcR n values in the 200--500 mV range were measured at 77K. Shapiro steps were observed under microwave irradiation, reflecting the true Josephson nature of those junctions. The magnetic field dependence of the junction Ic indicates a uniform current distribution. These results suggest that all fabrication processes are well controlled and the step edge is relatively straight and free of microstructural defects. The SQUIDs made from the same process exhibit large voltage modulation in a varying magnetic field. At 77K, our sapphire-based step-edge SQUID has a low white noise level at 3muphi0/ Hz , as compared to typically >10muphi0/ Hz from the best bicrystal STO SQUIDS. Our effort at device fabrication is chiefly motivated by the scanning SQUID microscopy (SSM) application. A scanning SQUID microscope is a non-contact, non-destructive imaging tool that can resolve weak currents beneath the sample surface by detecting their magnetic fields. Our low-noise sapphire-based step-edge SQUIDs should be particularly suitable for such an application. An earlier effort to make SNS trench junctions using focused ion beam (FIB) is reviewed in a separate chapter. (Abstract shortened by UMI.)

Temperature Driven Topological Switch in 1T'-MoTe2 and Strain Induced Nematicity in NaFeAs

NASA Astrophysics Data System (ADS)

Berger, Ayelet Denise Notis

Quasiparticle interference (QPI) is a powerful technique within Scanning Tunneling Microscopy (STM) that is used to probe the electronic bandstructure of materials. This thesis presents two examples using QPI to measure the bandstructure in materials with exotic electronic states that can be tuned via outside parameters (temperature and strain). In Part I of the thesis, we discuss the temperature dependence of Fermi Arcs in 1T'-MoTe 2, and then in Part II, the strain dependent nematic state in NaFeAs. The recent discovery of Weyl semimetals has introduced a new family of materials with topologically protected electronic properties and potential applications due to their anomalous transport effects. Even more useful is a Weyl semimetal that can be turned "on" and "off," switching between a topological and trivial state. One possible material is MoTe2, which undergoes a phase transition at 240K. This thesis consists of experiments using Scanning Tunneling Microscopy (STM) and Spectroscopy (STS) at different temperatures to visualize changes in the electronic bandstructure of MoTe2 across the topological phase transition. We show that a signature of topologically protected Fermi Arcs is present at low temperatures but disappears at room temperature, in the trivial phase. We include an in-depth discussion of how to account for thermal effects when comparing these two types of measurements. In Part II, we discuss strain induced nematicity in NaFeAs, an iron pnictide. Nematic fluctuations and spin correlations play an important role in the phase diagram of the iron pnictides, a family of unconventional superconductors. Illuminating the mechanism behind this symmetry breaking is key to understanding the superconducting state. Previous work has shown that nematicity in the iron pnictides responds strongly to applied strain [1, 2]. In this thesis, I present results from a new experimental technique, elasto-scanning tunneling microscopy (E-STM), which combines in situ strain and atomic resolution STM/STS. For the first time, we are able to observe the effects of strain on nematicity at the local level. We perform E-STM measurements in both the spin density wave phase and the tetragonal phase of NaFeAs and measure a distinct response in each. We successfully use strain to manipulate domain boundaries in the spin density wave state and we find the intensity of nematic fluctuations is coupled to strain in NaFeAs in the tetragonal phase.

Ultrafast Microscopy of Spin-Momentum-Locked Surface Plasmon Polaritons.

PubMed

Dai, Yanan; Dąbrowski, Maciej; Apkarian, Vartkess A; Petek, Hrvoje

2018-06-26

Using two-photon photoemission electron microscopy (2P-PEEM) we image the polarization dependence of coupling and propagation of surface plasmon polaritons (SPPs) launched from edges of a triangular, micrometer size, single-crystalline Ag crystal by linearly or circularly polarized light. 2P-PEEM records interferences between the optical excitation field and SPPs it creates with nanofemto space-time resolution. Both the linearly and circularly polarized femtosecond light pulses excite spatially asymmetric 2PP yield distributions, which are imaged. We attribute the asymmetry for linearly polarized light to the relative alignments of the laser polarization and triangle edges, which affect the efficiency of excitation of the longitudinal component of the SPP field. For circular polarization, the asymmetry is caused by matching of the spin angular momenta (SAM) of light and the transverse SAM of SPPs. Moreover, we show that the interference patterns recorded in the 2P-PEEM images are cast by phase shifts and amplitudes for coupling of light into the longitudinal and transverse components of SPP fields. While the interference patterns depend on the excitation polarization, nanofemto movies show that the phase and group velocities of SPPs are independent of SAM of light in time-reversal invariant media. Simulations of the wave interference reproduce the polarization and spin-dependent coupling of optical pulses into SPPs.

High-resolution imaging of magnetic fields using scanning superconducting quantum interference device (SQUID) microscopy

NASA Astrophysics Data System (ADS)

Fong de Los Santos, Luis E.

Development of a scanning superconducting quantum interference device (SQUID) microscope system with interchangeable sensor configurations for imaging magnetic fields of room-temperature (RT) samples with sub-millimeter resolution. The low-critical-temperature (Tc) niobium-based monolithic SQUID sensor is mounted in the tip of a sapphire rod and thermally anchored to the cryostat helium reservoir. A 25 mum sapphire window separates the vacuum space from the RT sample. A positioning mechanism allows adjusting the sample-to-sensor spacing from the top of the Dewar. I have achieved a sensor-to-sample spacing of 100 mum, which could be maintained for periods of up to 4 weeks. Different SQUID sensor configurations are necessary to achieve the best combination of spatial resolution and field sensitivity for a given magnetic source. For imaging thin sections of geological samples, I used a custom-designed monolithic low-Tc niobium bare SQUID sensor, with an effective diameter of 80 mum, and achieved a field sensitivity of 1.5 pT/Hz1/2 and a magnetic moment sensitivity of 5.4 x 10-18 Am2/Hz1/2 at a sensor-to-sample spacing of 100 mum in the white noise region for frequencies above 100 Hz. Imaging action currents in cardiac tissue requires higher field sensitivity, which can only be achieved by compromising spatial resolution. I developed a monolithic low-Tc niobium multiloop SQUID sensor, with sensor sizes ranging from 250 mum to 1 mm, and achieved sensitivities of 480 - 180 fT/Hz1/2 in the white noise region for frequencies above 100 Hz, respectively. For all sensor configurations, the spatial resolution was comparable to the effective diameter and limited by the sensor-to-sample spacing. Spatial registration allowed us to compare high-resolution images of magnetic fields associated with action currents and optical recordings of transmembrane potentials to study the bidomain nature of cardiac tissue or to match petrography to magnetic field maps in thin sections of geological samples.

Three-dimensional characterization of extreme ultraviolet mask blank defects by interference contrast photoemission electron microscopy.

PubMed

Lin, Jingquan; Weber, Nils; Escher, Matthias; Maul, Jochen; Han, Hak-Seung; Merkel, Michael; Wurm, Stefan; Schönhense, Gerd; Kleineberg, Ulf

2008-09-29

A photoemission electron microscope based on a new contrast mechanism "interference contrast" is applied to characterize extreme ultraviolet lithography mask blank defects. Inspection results show that positioning of interference destructive condition (node of standing wave field) on surface of multilayer in the local region of a phase defect is necessary to obtain best visibility of the defect on mask blank. A comparative experiment reveals superiority of the interference contrast photoemission electron microscope (Extreme UV illumination) over a topographic contrast one (UV illumination with Hg discharge lamp) in detecting extreme ultraviolet mask blank phase defects. A depth-resolved detection of a mask blank defect, either by measuring anti-node peak shift in the EUV-PEEM image under varying inspection wavelength condition or by counting interference fringes with a fixed illumination wavelength, is discussed.

Electrical characterization of grain boundaries of CZTS thin films using conductive atomic force microscopy techniques

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

Muhunthan, N.; Singh, Om Pal; Toutam, Vijaykumar, E-mail: toutamvk@nplindia.org

2015-10-15

Graphical abstract: Experimental setup for conducting AFM (C-AFM). - Highlights: • Cu{sub 2}ZnSnS{sub 4} (CZTS) thin film was grown by reactive co-sputtering. • The electronic properties were probed using conducting atomic force microscope, scanning Kelvin probe microscopy and scanning capacitance microscopy. • C-AFM current flow mainly through grain boundaries rather than grain interiors. • SKPM indicated higher potential along the GBs compared to grain interiors. • The SCM explains that charge separation takes place at the interface of grain and grain boundary. - Abstract: Electrical characterization of grain boundaries (GB) of Cu-deficient CZTS (Copper Zinc Tin Sulfide) thin films wasmore » done using atomic force microscopic (AFM) techniques like Conductive atomic force microscopy (CAFM), Kelvin probe force microscopy (KPFM) and scanning capacitance microscopy (SCM). Absorbance spectroscopy was done for optical band gap calculations and Raman, XRD and EDS for structural and compositional characterization. Hall measurements were done for estimation of carrier mobility. CAFM and KPFM measurements showed that the currents flow mainly through grain boundaries (GB) rather than grain interiors. SCM results showed that charge separation mainly occurs at the interface of grain and grain boundaries and not all along the grain boundaries.« less

Developing new optical imaging techniques for single particle and molecule tracking in live cells

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

Sun, Wei

Differential interference contrast (DIC) microscopy is a far-field as well as wide-field optical imaging technique. Since it is non-invasive and requires no sample staining, DIC microscopy is suitable for tracking the motion of target molecules in live cells without interfering their functions. In addition, high numerical aperture objectives and condensers can be used in DIC microscopy. The depth of focus of DIC is shallow, which gives DIC much better optical sectioning ability than those of phase contrast and dark field microscopies. In this work, DIC was utilized to study dynamic biological processes including endocytosis and intracellular transport in live cells.more » The suitability of DIC microscopy for single particle tracking in live cells was first demonstrated by using DIC to monitor the entire endocytosis process of one mesoporous silica nanoparticle (MSN) into a live mammalian cell. By taking advantage of the optical sectioning ability of DIC, we recorded the depth profile of the MSN during the endocytosis process. The shape change around the nanoparticle due to the formation of a vesicle was also captured. DIC microscopy was further modified that the sample can be illuminated and imaged at two wavelengths simultaneously. By using the new technique, noble metal nanoparticles with different shapes and sizes were selectively imaged. Among all the examined metal nanoparticles, gold nanoparticles in rod shapes were found to be especially useful. Due to their anisotropic optical properties, gold nanorods showed as diffraction-limited spots with disproportionate bright and dark parts that are strongly dependent on their orientation in the 3D space. Gold nanorods were developed as orientation nanoprobes and were successfully used to report the self-rotation of gliding microtubules on kinesin coated substrates. Gold nanorods were further used to study the rotational motions of cargoes during the endocytosis and intracellular transport processes in live mammalian cells. New rotational information was obtained: (1) during endocytosis, cargoes lost their rotation freedom at the late stage of internalization; (2) cargoes performed train-like motion when they were transported along the microtubule network by motor proteins inside live cells; (3) During the pause stage of fast axonal transport, cargoes were still bound to the microtubule tracks by motor proteins. Total internal reflection fluorescence microscopy (TIRFM) is another non-invasive and far-field optical imaging technique. Because of its near-field illumination mechanism, TIRFM has better axial resolution than epi-fluorescence microscopy and confocal microscopy. In this work, an auto-calibrated, prism type, angle-scanning TIRFM instrument was built. The incident angle can range from subcritical angles to nearly 90°, with an angle interval less than 0.2°. The angle precision of the new instrument was demonstrated through the finding of the surface plasmon resonance (SPR) angle of metal film coated glass slide. The new instrument improved significantly the precision in determining the axial position. As a result, the best obtained axial resolution was ~ 8 nm, which is better than current existing instruments similar in function. The instrument was further modified to function as a pseudo TIRF microscope. The illumination depth can be controlled by changing the incident angle of the excitation laser beam or adjusting the horizontal position of the illumination laser spot on the prism top surface. With the new technique, i.e., variable-illumination-depth pseudo TIRF microscopy, the whole cell body from bottom to top was scanned.« less

PScan 1.0: flexible software framework for polygon based multiphoton microscopy

NASA Astrophysics Data System (ADS)

Li, Yongxiao; Lee, Woei Ming

2016-12-01

Multiphoton laser scanning microscopes exhibit highly localized nonlinear optical excitation and are powerful instruments for in-vivo deep tissue imaging. Customized multiphoton microscopy has a significantly superior performance for in-vivo imaging because of precise control over the scanning and detection system. To date, there have been several flexible software platforms catered to custom built microscopy systems i.e. ScanImage, HelioScan, MicroManager, that perform at imaging speeds of 30-100fps. In this paper, we describe a flexible software framework for high speed imaging systems capable of operating from 5 fps to 1600 fps. The software is based on the MATLAB image processing toolbox. It has the capability to communicate directly with a high performing imaging card (Matrox Solios eA/XA), thus retaining high speed acquisition. The program is also designed to communicate with LabVIEW and Fiji for instrument control and image processing. Pscan 1.0 can handle high imaging rates and contains sufficient flexibility for users to adapt to their high speed imaging systems.

Accurate virus quantitation using a Scanning Transmission Electron Microscopy (STEM) detector in a scanning electron microscope.

PubMed

Blancett, Candace D; Fetterer, David P; Koistinen, Keith A; Morazzani, Elaine M; Monninger, Mitchell K; Piper, Ashley E; Kuehl, Kathleen A; Kearney, Brian J; Norris, Sarah L; Rossi, Cynthia A; Glass, Pamela J; Sun, Mei G

2017-10-01

A method for accurate quantitation of virus particles has long been sought, but a perfect method still eludes the scientific community. Electron Microscopy (EM) quantitation is a valuable technique because it provides direct morphology information and counts of all viral particles, whether or not they are infectious. In the past, EM negative stain quantitation methods have been cited as inaccurate, non-reproducible, and with detection limits that were too high to be useful. To improve accuracy and reproducibility, we have developed a method termed Scanning Transmission Electron Microscopy - Virus Quantitation (STEM-VQ), which simplifies sample preparation and uses a high throughput STEM detector in a Scanning Electron Microscope (SEM) coupled with commercially available software. In this paper, we demonstrate STEM-VQ with an alphavirus stock preparation to present the method's accuracy and reproducibility, including a comparison of STEM-VQ to viral plaque assay and the ViroCyt Virus Counter. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Electronic heterodyne recording of interference patterns

NASA Technical Reports Server (NTRS)

Merat, F. L.; Claspy, P. C.

1979-01-01

An electronic heterodyne technique is being investigated for video (i.e., television rate and format) recording of interference patterns. In the heterodyne technique electro-optic modulation is used to introduce a sinusoidal phase shift between the beams of an interferometer. For phase modulation frequencies between 0.1 and 15 MHz an image dissector camera may be used to scan the resulting temporally modulated interference pattern. Heterodyne detection of the camera output is used to selectively record the interference pattern. An advantage of such synchronous recording is that it permits recording of low-contrast fringes in high ambient light conditions. The application of this technique to the recording of holograms is discussed.

Surface Characterization.

ERIC Educational Resources Information Center

Fulghum, J. E.; And Others

1989-01-01

This review is divided into the following analytical methods: ion spectroscopy, electron spectroscopy, scanning tunneling microscopy, atomic force microscopy, optical spectroscopy, desorption techniques, and X-ray techniques. (MVL)

Interference fringes on GLORIA side-scan sonar images from the Bering Sea and their implications

USGS Publications Warehouse

Huggett, Q.J.; Cooper, A. K.; Somers, M.L.; Stubbs, A.R.

1992-01-01

GLORIA side-scan sonographs from the Bering Sea Basin show a complex pattern of interference fringes sub-parallel to the ship's track. Surveys along the same trackline made in 1986 and 1987 show nearly identical patterns. It is concluded from this that the interference patterns are caused by features in the shallow subsurface rather than in the water column. The fringes are interpreted as a thin-layer interference effect that occurs when some of the sound reaching the seafloor passes through it and is reflected off a subsurface layer. The backscattered sound interferes (constructively or desctructively) with the reflected sound. Constructive/destructive interference occurs when the difference in the length of the two soundpaths is a whole/half multiple of GLORIA's 25 cm wavelength. Thus as range from the ship increases, sound moves in and out of phase causing bands of greater and lesser intensity on the GLORIA sonograph. Fluctuations (or 'wiggles') of the fringes on the GLORIA sonographs relate to changes in layer thickness. In principle, a simple three dimensional image of the subsurface layer may be obtained using GLORIA and bathymetric data from adjacent (parallel) ship's tracks. These patterns have also been identified in images from two other systems; SeaMARC II (12 kHz) long-range sonar, and TOBI (30 kHz) deep-towed sonar. In these, and other cases world-wide, the fringes do not appear with the same persistence as those seen in the Bering Sea. ?? 1992 Kluwer Academic Publishers.

Impact of membrane-induced particle immobilization on seeded growth monitored by in situ liquid scanning transmission electron microscopy

DOE PAGES

Weiner, Rebecca G.; Chen, Dennis P.; Unocic, Raymond R.; ...

2016-04-01

In situ liquid cell scanning transmission electron microscopy probes seeded growth in real time. The growth of Pd on Au nanocubes is monitored as a model system to compare growth within a liquid cell and traditional colloidal synthesis. Furthermore, different growth patterns are observed due to seed immobilization and the highly reducing environment within the liquid cell.

Application of carbon nanotubes to topographical resolution enhancement of tapered fiber scanning near field optical microscopy probes

NASA Astrophysics Data System (ADS)

Huntington, S. T.; Jarvis, S. P.

2003-05-01

Scanning near field optical microscopy (SNOM) probes are typically tapered optical fibers with metallic coatings. The tip diameters are generally in excess of 300 nm and thus provide poor topographical resolution. Here we report on the attachment multiwalled carbon nanotubes to the probes in order to substantially enhance the topographical resolution, without adversely affecting the optical resolution.

Recombinant Reflectin-Based Optical Materials

DTIC Science & Technology

2012-01-01

sili- con substrates were placed in a sealed plastic box. The RH was controlled using a Dydra electronic cigar humidifier and monitored using a Fisher...diffraction gratings to generate diffraction patterns. Nano-spheres and la- mellar microstructures of refCBA samples were observed by scanning electron ...samples were observed by scanning electron microscopy and atomic force microscopy. Despite the reduced complexity of the refCBA protein compared to natural

Image formation of thick three-dimensional objects in differential-interference-contrast microscopy.

PubMed

Trattner, Sigal; Kashdan, Eugene; Feigin, Micha; Sochen, Nir

2014-05-01

The differential-interference-contrast (DIC) microscope is of widespread use in life sciences as it enables noninvasive visualization of transparent objects. The goal of this work is to model the image formation process of thick three-dimensional objects in DIC microscopy. The model is based on the principles of electromagnetic wave propagation and scattering. It simulates light propagation through the components of the DIC microscope to the image plane using a combined geometrical and physical optics approach and replicates the DIC image of the illuminated object. The model is evaluated by comparing simulated images of three-dimensional spherical objects with the recorded images of polystyrene microspheres. Our computer simulations confirm that the model captures the major DIC image characteristics of the simulated object, and it is sensitive to the defocusing effects.

Invited Review Article: Imaging techniques for harmonic and multiphoton absorption fluorescence microscopy

PubMed Central

Carriles, Ramón; Schafer, Dawn N.; Sheetz, Kraig E.; Field, Jeffrey J.; Cisek, Richard; Barzda, Virginijus; Sylvester, Anne W.; Squier, Jeffrey A.

2009-01-01

We review the current state of multiphoton microscopy. In particular, the requirements and limitations associated with high-speed multiphoton imaging are considered. A description of the different scanning technologies such as line scan, multifoci approaches, multidepth microscopy, and novel detection techniques is given. The main nonlinear optical contrast mechanisms employed in microscopy are reviewed, namely, multiphoton excitation fluorescence, second harmonic generation, and third harmonic generation. Techniques for optimizing these nonlinear mechanisms through a careful measurement of the spatial and temporal characteristics of the focal volume are discussed, and a brief summary of photobleaching effects is provided. Finally, we consider three new applications of multiphoton microscopy: nonlinear imaging in microfluidics as applied to chemical analysis and the use of two-photon absorption and self-phase modulation as contrast mechanisms applied to imaging problems in the medical sciences. PMID:19725639

Structural, optical, magnetic and electrical properties of hematite (α-Fe2O3) nanoparticles synthesized by two methods: polyol and precipitation

NASA Astrophysics Data System (ADS)

Mansour, Houda; Letifi, Hanen; Bargougui, Radhouane; De Almeida-Didry, Sonia; Negulescu, Beatrice; Autret-Lambert, Cécile; Gadri, Abdellatif; Ammar, Salah

2017-12-01

Hematite (α-Fe2O3) nanoparticles have been successfully synthesized via two methods: (1) polyol and (2) precipitation in water. The influence of synthesis methods on the crystalline structure, morphological, optical, magnetic and electrical properties were investigated using X-ray diffraction, RAMAN spectroscopy, scanning electron microscopy, transmission electron microscopy, UV-visible diffuse reflectance spectroscopy (UV-vis DRS), superconducting quantum interference device and impedance spectroscopy. The structural properties showed that the obtained hematite α-Fe2O3 nanoparticles with two preparation methods exhibit hexagonal phase with high crystallinity and high-phase stability at room temperature. It was found that the average hematite nanoparticle size is estimated to be 36.86 nm for the sample synthesized by precipitation and 54.14 nm for the sample synthesized by polyol. Moreover, the optical properties showed that the band gap energy value of α-Fe2O3 synthesized by precipitation (2.07 eV) was higher than that of α-Fe2O3 synthesized by polyol (1.97 eV) and they showed a red shift to the visible region. Furthermore, the measurements of magnetic properties indicated a magnetization loop typical of ferromagnetic systems at room temperature. Measurements of electrical properties show higher dielectric permittivity (5.64 × 103) and relaxation phenomenon for α-Fe2O3 issued from the precipitation method than the other sample.

A new measure of molecular attractions between nanoparticles near kT adhesion energy

NASA Astrophysics Data System (ADS)

Kendall, Kevin; Dhir, Aman; Du, Shangfeng

2009-07-01

The weak molecular attractions of nanoparticles are important because they drive self-assembly mechanisms, allow processing in dispersions e.g. of pigments, catalysts or device structures, influence disease through the attraction of viruses to cells and also cause potential toxic effects through nanoparticle interference with biomolecules and organs. The problem is to understand these small forces which pull nanoparticles into intimate contact; forces which are comparable with 3kT/2z the thermal impact force experienced by an average Brownian particle hitting a linear repulsive potential of range z. Here we describe a new method for measuring the atomic attractions of nanoparticles based on the observation of aggregates produced by these small forces. The method is based on the tracking of individual monosize nanoparticles whose diameter can be calculated from the Stokes-Einstein analysis of the tracks in aqueous suspensions. Then the doublet aggregates are distinguished because they move slower and are also very much brighter than the dispersed nanoparticles. By finding the ratio of doublets to singlets, the adhesive energy between the particles can be calculated from known statistical thermodynamic theory using assumptions about the shape of the interaction potential. In this way, very small adhesion energies of 2kT have been measured, smaller than those seen previously by atomic force microscopy (AFM) and scanning tunneling microscopy (STM).

Pilosebaceous targeting by isotretenoin-loaded invasomal gel for the treatment of eosinophilic pustular folliculitis: optimization, efficacy and cellular analysis.

PubMed

Dwivedi, Mohit; Sharma, Vijay; Pathak, Kamla

2017-02-01

Eosinophilic pustular folliculitis is a secondary symptom associated with HIV infection appears as levels of CD4 lymphocyte cells and T4 lymphocyte cell. Isotretinoin, an analog of vitamin A (retinoid) alters the DNA transcription mechanism and interferes in the process of DNA formation. It also inhibits the eosinophilic chemotactic factors present in sebaceous lipids and in the stratum corneum of patients suffering from this ailment. The present research was aimed to formulate isotretenoin-loaded invasomal gel to deliver and target the drug to pilosebaceous follicular unit. Nine invasomal formulations (F1-F9) were prepared applying 3 2 factorial designs and characterized. Formulation F9 was selected as optimized formulation due to optimum results and highest %CDP of 85.94 ± 1.86% in 8 h. Transmission electron microscopy (TEM) suggested uniformity in vesicles shape and size in F9 and developed as invasomal gel (IG). Clinical phase-I, phase-II, and phase-III studies will be required before using on human patients. Confocal laser scanning microscopy (CLSM) validates that IG successfully reaches the pilosebaceous follicular unit and further studied on cell line (SZ-95) exhibited IC50 of ≤8 (25 μM of isotretenoin). Cell cycle analysis confirmed IG arrested the cell growth up to 82% with insignificant difference to pure isotretenion.

Microstructural evolution and magnetic properties of ultrafine solute-atom particles formed in a Cu75-Ni20-Fe5 alloy on isothermal annealing

NASA Astrophysics Data System (ADS)

Kim, Jun-Seop; Takeda, Mahoto; Bae, Dong-Sik

2016-12-01

Microstructural features strongly affect magnetism in nano-granular magnetic materials. In the present work we have investigated the relationship between the magnetic properties and the self-organized microstructure formed in a Cu75-Ni20-Fe5 alloy comprising ferromagnetic elements and copper atoms. High resolution transmission electron microscopy (HRTEM) observations showed that on isothermal annealing at 873 K, nano-scale solute (Fe,Ni)-rich clusters initially formed with a random distribution in the Cu-rich matrix. Superconducting quantum interference device (SQUID) measurements revealed that these ultrafine solute clusters exhibited super-spinglass and superparamagnetic states. On further isothermal annealing the precipitates evolved to cubic or rectangular ferromagnetic particles and aligned along the <100> directions of the copper-rich matrix. Electron energy-band calculations based on the first-principle Korringa-Kohn-Rostocker (KKR) method were also implemented to investigate both the electronic structure and the magnetic properties of the alloy. Inputting compositions obtained experimentally by scanning transmission electron microscopy-electron dispersive X-ray spectroscopy (STEM-EDS) analysis, the KKR calculation confirmed that ferromagnetic precipitates (of moment 1.07μB per atom) formed after annealing for 2 × 104 min. Magneto-thermogravimetric (MTG) analysis determined with high sensitivity the Curie temperatures and magnetic susceptibility above room temperature of samples containing nano-scale ferromagnetic particles.

Comparative morphology analysis of live blood platelets using scanning ion conductance and robotic dark-field microscopy.

PubMed

Kraus, Max-Joseph; Seifert, Jan; Strasser, Erwin F; Gawaz, Meinrad; Schäffer, Tilman E; Rheinlaender, Johannes

2016-09-01

Many conventional microscopy techniques for investigating platelet morphology such as electron or fluorescence microscopy require highly invasive treatment of the platelets such as fixation, drying and metal coating or staining. Here, we present two unique but entirely different microscopy techniques for direct morphology analysis of live, unstained platelets: scanning ion conductance microscopy (SICM) and robotic dark-field microscopy (RDM). We demonstrate that both techniques allow for a quantitative evaluation of the morphological features of live adherent platelets. We show that their morphology can be quantified by both techniques using the same geometric parameters and therefore can be directly compared. By imaging the same identical platelets subsequently with SICM and RDM, we found that area, perimeter and circularity of the platelets are directly correlated between SICM and dark-field microscopy (DM), while the fractal dimension (FD) differed between the two microscopy techniques. We show that SICM and RDM are both valuable tools for the ex vivo investigation of the morphology of live platelets, which might contribute to new insights into the physiological and pathophysiological role of platelet spreading.

Improved axial point spread function in a two-frequency laser scanning confocal fluorescence microscope

NASA Astrophysics Data System (ADS)

Wu, Jheng-Syong; Chung, Yung-Chin; Chien, Jun-Jei; Chou, Chien

2018-01-01

A two-frequency laser scanning confocal fluorescence microscope (TF-LSCFM) based on intensity modulated fluorescence signal detection was proposed. The specimen-induced spherical aberration and scattering effect were suppressed intrinsically, and high image contrast was presented due to heterodyne interference. An improved axial point spread function in a TF-LSCFM compared with a conventional laser scanning confocal fluorescence microscope was demonstrated and discussed.

Scanning dimensional measurement using laser-trapped microsphere with optical standing-wave scale

NASA Astrophysics Data System (ADS)

Michihata, Masaki; Ueda, Shin-ichi; Takahashi, Satoru; Takamasu, Kiyoshi; Takaya, Yasuhiro

2017-06-01

We propose a laser trapping-based scanning dimensional measurement method for free-form surfaces. We previously developed a laser trapping-based microprobe for three-dimensional coordinate metrology. This probe performs two types of measurements: a tactile coordinate and a scanning measurement in the same coordinate system. The proposed scanning measurement exploits optical interference. A standing-wave field is generated between the laser-trapped microsphere and the measured surface because of the interference from the retroreflected light. The standing-wave field produces an effective length scale, and the trapped microsphere acts as a sensor to read this scale. A horizontal scan of the trapped microsphere produces a phase shift of the standing wave according to the surface topography. This shift can be measured from the change in the microsphere position. The dynamics of the trapped microsphere within the standing-wave field was estimated using a harmonic model, from which the measured surface can be reconstructed. A spherical lens was measured experimentally, yielding a radius of curvature of 2.59 mm, in agreement with the nominal specification (2.60 mm). The difference between the measured points and a spherical fitted curve was 96 nm, which demonstrates the scanning function of the laser trapping-based microprobe for free-form surfaces.

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.

Large-scale Scanning Transmission Electron Microscopy (Nanotomy) of Healthy and Injured Zebrafish Brain.

PubMed

Kuipers, Jeroen; Kalicharan, Ruby D; Wolters, Anouk H G; van Ham, Tjakko J; Giepmans, Ben N G

2016-05-25

Large-scale 2D electron microscopy (EM), or nanotomy, is the tissue-wide application of nanoscale resolution electron microscopy. Others and we previously applied large scale EM to human skin pancreatic islets, tissue culture and whole zebrafish larvae(1-7). Here we describe a universally applicable method for tissue-scale scanning EM for unbiased detection of sub-cellular and molecular features. Nanotomy was applied to investigate the healthy and a neurodegenerative zebrafish brain. Our method is based on standardized EM sample preparation protocols: Fixation with glutaraldehyde and osmium, followed by epoxy-resin embedding, ultrathin sectioning and mounting of ultrathin-sections on one-hole grids, followed by post staining with uranyl and lead. Large-scale 2D EM mosaic images are acquired using a scanning EM connected to an external large area scan generator using scanning transmission EM (STEM). Large scale EM images are typically ~ 5 - 50 G pixels in size, and best viewed using zoomable HTML files, which can be opened in any web browser, similar to online geographical HTML maps. This method can be applied to (human) tissue, cross sections of whole animals as well as tissue culture(1-5). Here, zebrafish brains were analyzed in a non-invasive neuronal ablation model. We visualize within a single dataset tissue, cellular and subcellular changes which can be quantified in various cell types including neurons and microglia, the brain's macrophages. In addition, nanotomy facilitates the correlation of EM with light microscopy (CLEM)(8) on the same tissue, as large surface areas previously imaged using fluorescent microscopy, can subsequently be subjected to large area EM, resulting in the nano-anatomy (nanotomy) of tissues. In all, nanotomy allows unbiased detection of features at EM level in a tissue-wide quantifiable manner.