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Sample records for spectroscopic phase microscopy

  1. Spectroscopic imaging in electron microscopy

    SciTech Connect

    Pennycook, Stephen J; Colliex, C.

    2012-01-01

    In the scanning transmission electron microscope, multiple signals can be simultaneously collected, including the transmitted and scattered electron signals (bright field and annular dark field or Z-contrast images), along with spectroscopic signals such as inelastically scattered electrons and emitted photons. In the last few years, the successful development of aberration correctors for the electron microscope has transformed the field of electron microscopy, opening up new possibilities for correlating structure to functionality. Aberration correction not only allows for enhanced structural resolution with incident probes into the sub-angstrom range, but can also provide greater probe currents to facilitate mapping of intrinsically weak spectroscopic signals at the nanoscale or even the atomic level. In this issue of MRS Bulletin, we illustrate the power of the new generation of electron microscopes with a combination of imaging and spectroscopy. We show the mapping of elemental distributions at atomic resolution and also the mapping of electronic and optical properties at unprecedented spatial resolution, with applications ranging from graphene to plasmonic nanostructures, and oxide interfaces to biology.

  2. Nanosecond microscopy with spectroscopic resolution

    NASA Astrophysics Data System (ADS)

    Heinrich, Christoph; Bernet, Stefan; Ritsch-Marte, Monika

    2006-03-01

    We demonstrate coherent anti-Stokes Raman scattering (CARS) microscopy in a wide-field setup with nanosecond laser pulse excitation. In contrast to confocal setups, the image of a sample can be recorded with a single pair of excitation pulses. For this purpose, the excitation geometry is specially designed in order to satisfy the phase matching condition over the whole sample area. The spectral, temporal and spatial sensitivity of the method is demonstrated by imaging test samples, i.e. oil vesicles in sunflower seeds, on a nanosecond timescale. The method provides snapshot imaging in 3 ns with a spectral resolution of 25 cm-1.

  3. Quantitative optical phase microscopy.

    PubMed

    Barty, A; Nugent, K A; Paganin, D; Roberts, A

    1998-06-01

    We present a new method for the extraction of quantitative phase data from microscopic phase samples by use of partially coherent illumination and an ordinary transmission microscope. The technique produces quantitative images of the phase profile of the sample without phase unwrapping. The technique is able to recover phase even in the presence of amplitude modulation, making it significantly more powerful than existing methods of phase microscopy. We demonstrate the technique by providing quantitatively correct phase images of well-characterized test samples and show that the results obtained for more-complex samples correlate with structures observed with Nomarski differential interference contrast techniques.

  4. Controllable tomography phase microscopy

    NASA Astrophysics Data System (ADS)

    Xiu, Peng; Zhou, Xin; Kuang, Cuifang; Xu, Yingke; Liu, Xu

    2015-03-01

    Tomography phase microscopy (TPM) is a new microscopic method that can quantitatively yield the volumetric 3D distribution of a sample's refractive index (RI), which is significant for cell biology research. In this paper, a controllable TPM system is introduced. In this system a circulatory phase-shifting method and piezoelectric ceramic are used which enable the TPM system to record the 3D RI distribution at a more controllable speed, from 1 to 40 fps, than in the other TPM systems reported. The resolution of the RI distribution obtained by this controllable TPM is much better than that in images recorded by phase contrast microscopy and interference tomography microscopy. The realization of controllable TPM not only allows for the application of TPM to the measurement of kinds of RI sample, but also contributes to academic and technological support for the practical use of TPM.

  5. Spectral Domain Phase Microscopy

    NASA Astrophysics Data System (ADS)

    Hendargo, Hansford C.; Ellerbee, Audrey K.; Izatt, Joseph A.

    Spectral domain phase microscopy (SDPM) is a functional extension of optical coherence tomography (OCT) using common-path interferometry to produce phase-referenced images of dynamic samples. Like OCT, axial resolution in SDPM is determined by the source coherence length, while lateral resolution is limited by diffraction in the microscope optics. However, the quantitative phase information SDPM generates is sensitive to nanometer-scale displacements of scattering structures. The use of a common-path optical geometry yields an imaging system with high phase stability. Due to coherence gating, SDPM can achieve full depth discrimination, allowing for independent motion resolution of subcellular structures throughout the sample volume. Here we review the basic theory of OCT and SDPM along with applications of SDPM in cellular imaging to measure topology, Doppler flow in single-celled organisms, time-resolved motions, rheological information of the cytoskeleton, and optical signaling of neural activation. Phase imaging limitations, artifacts, and sensitivity considerations are discussed.

  6. Super-resolution spectroscopic microscopy via photon localization

    PubMed Central

    Dong, Biqin; Almassalha, Luay; Urban, Ben E.; Nguyen, The-Quyen; Khuon, Satya; Chew, Teng-Leong; Backman, Vadim; Sun, Cheng; Zhang, Hao F.

    2016-01-01

    Traditional photon localization microscopy analyses only the spatial distributions of photons emitted by individual molecules to reconstruct super-resolution optical images. Unfortunately, however, the highly valuable spectroscopic information from these photons have been overlooked. Here we report a spectroscopic photon localization microscopy that is capable of capturing the inherent spectroscopic signatures of photons from individual stochastic radiation events. Spectroscopic photon localization microscopy achieved higher spatial resolution than traditional photon localization microscopy through spectral discrimination to identify the photons emitted from individual molecules. As a result, we resolved two fluorescent molecules, which were 15 nm apart, with the corresponding spatial resolution of 10 nm—a four-fold improvement over photon localization microscopy. Using spectroscopic photon localization microscopy, we further demonstrated simultaneous multi-colour super-resolution imaging of microtubules and mitochondria in COS-7 cells and showed that background autofluorescence can be identified through its distinct emission spectra. PMID:27452975

  7. Super-resolution spectroscopic microscopy via photon localization

    NASA Astrophysics Data System (ADS)

    Dong, Biqin; Almassalha, Luay; Urban, Ben E.; Nguyen, The-Quyen; Khuon, Satya; Chew, Teng-Leong; Backman, Vadim; Sun, Cheng; Zhang, Hao F.

    2016-07-01

    Traditional photon localization microscopy analyses only the spatial distributions of photons emitted by individual molecules to reconstruct super-resolution optical images. Unfortunately, however, the highly valuable spectroscopic information from these photons have been overlooked. Here we report a spectroscopic photon localization microscopy that is capable of capturing the inherent spectroscopic signatures of photons from individual stochastic radiation events. Spectroscopic photon localization microscopy achieved higher spatial resolution than traditional photon localization microscopy through spectral discrimination to identify the photons emitted from individual molecules. As a result, we resolved two fluorescent molecules, which were 15 nm apart, with the corresponding spatial resolution of 10 nm--a four-fold improvement over photon localization microscopy. Using spectroscopic photon localization microscopy, we further demonstrated simultaneous multi-colour super-resolution imaging of microtubules and mitochondria in COS-7 cells and showed that background autofluorescence can be identified through its distinct emission spectra.

  8. Phase Aberrations in Diffraction Microscopy

    SciTech Connect

    Marchesini, S; Chapman, H N; Barty, A; Howells, M R; Spence, J H; Cui, C; Weierstall, U; Minor, A M

    2005-09-29

    In coherent X-ray diffraction microscopy the diffraction pattern generated by a sample illuminated with coherent x-rays is recorded, and a computer algorithm recovers the unmeasured phases to synthesize an image. By avoiding the use of a lens the resolution is limited, in principle, only by the largest scattering angles recorded. However, the imaging task is shifted from the experiment to the computer, and the algorithm's ability to recover meaningful images in the presence of noise and limited prior knowledge may produce aberrations in the reconstructed image. We analyze the low order aberrations produced by our phase retrieval algorithms. We present two methods to improve the accuracy and stability of reconstructions.

  9. Quantitative phase-amplitude microscopy I: optical microscopy.

    PubMed

    Barone-Nugent, E D; Barty, A; Nugent, K A

    2002-06-01

    In this paper, the application of a new optical microscopy method (quantitative phase-amplitude microscopy) to biological imaging is explored, and the issue of resolution and image quality is examined. The paper begins by presenting a theoretical analysis of the method using the optical transfer function formalism of Streibl (1985). The effect of coherence on the formation of the phase image is explored, and it is shown that the resolution of the method is not compromised over that of a conventional bright-field image. It is shown that the signal-to-noise ratio of the phase recovery, however, does depend on the degree of coherence in the illumination. Streibl (1985) notes that partially coherent image formation is a non-linear process because of the intermingling of amplitude and phase information. The work presented here shows that the quantitative phase-amplitude microscopy method acts to linearize the image formation process, and that the phase and amplitude information is properly described using a transfer function analysis. The theoretical conclusions are tested experimentally using an optical microscope and the theoretical deductions are confirmed. Samples for microscopy influence both the phase and amplitude of the light wave and it is demonstrated that the new phase recovery method can separate the amplitude and phase information, something not possible using traditional phase microscopy. In the case of a coherent wave, knowledge of the phase and amplitude constitutes complete information that can be used to emulate other forms of microscopy. This capacity is demonstrated by recovering the phase of a sample and using the data to emulate a differential interference contrast image.

  10. Tomographic phase microscopy and its biological applications

    NASA Astrophysics Data System (ADS)

    Choi, Wonshik

    2012-12-01

    Conventional interferometric microscopy techniques such as digital holographic microscopy and quantitative phase microscopy are often classified as 3D imaging techniques because a recorded complex field image can be numerically propagated to a different depth. In a strict sense, however, a single complex field image contains only 2D information on a specimen. The measured 2D image is only a subset of the 3D structure. For the 3D mapping of an object, multiple independent 2D images are to be taken, for example at multiple incident angles or wavelengths, and then combined by the so-called optical diffraction tomography (ODT). In this Letter, tomographic phase microscopy (TPM) is reviewed that experimentally realizes the concept of the ODT for the 3D mapping of biological cells in their native state, and some of its interesting biological and biomedical applications are introduced. [Figure not available: see fulltext.

  11. Phase-contrast scanning transmission electron microscopy.

    PubMed

    Minoda, Hiroki; Tamai, Takayuki; Iijima, Hirofumi; Hosokawa, Fumio; Kondo, Yukihito

    2015-06-01

    This report introduces the first results obtained using phase-contrast scanning transmission electron microscopy (P-STEM). A carbon-film phase plate (PP) with a small center hole is placed in the condenser aperture plane so that a phase shift is introduced in the incident electron waves except those passing through the center hole. A cosine-type phase-contrast transfer function emerges when the phase-shifted scattered waves interfere with the non-phase-shifted unscattered waves, which passed through the center hole before incidence onto the specimen. The phase contrast resulting in P-STEM is optically identical to that in phase-contrast transmission electron microscopy that is used to provide high contrast for weak phase objects. Therefore, the use of PPs can enhance the phase contrast of the STEM images of specimens in principle. The phase shift resulting from the PP, whose thickness corresponds to a phase shift of π, has been confirmed using interference fringes displayed in the Ronchigram of a silicon single crystal specimen. The interference fringes were found to abruptly shift at the edge of the PP hole by π.

  12. A novel phase shifting structured illumination microscopy

    NASA Astrophysics Data System (ADS)

    Singh, Veena; Dubey, Vishesh; Ahmad, Azeem; Singh, Gyanendra; Mehta, D. S.

    2016-03-01

    This paper describes a new and novel phase shifting technique for qualitative as well as quantitative measurement in microscopy. We have developed a phase shifting device which is robust, inexpensive and involves no mechanical movement. In this method, phase shifting is implemented using LED array, beam splitters and defocused projection of Ronchi grating. The light from the LEDs are made incident on the beam splitters at spatially different locations. Due to variation in the geometrical distances of LEDs from the Ronchi grating and by sequentially illuminating the grating by switching on one LED at a time the phase shifted grating patterns are generated. The phase shifted structured patterns are projected onto the sample using microscopic objective lens. The phase shifted deformed patterns are recorded by a CCD camera. The initial alignment of the setup involves a simple procedure for the calibration for equal fringe width and intensity such that the phase shifted fringes are at equal phase difference. Three frame phase shifting algorithm is employed for the reconstruction of the phase map. The method described here is fully automated so that the phase shifted images are recorded just by switching of LEDs and has been used for the shape measurement of microscopic industrial objects. The analysis of the phase shifted images provides qualitative as well as quantitative information about the sample. Thus, the method is simple, robust and low cost compared to PZT devices commonly employed for phase shifting.

  13. Video-rate tomographic phase microscopy.

    PubMed

    Fang-Yen, Christopher; Choi, Wonshik; Sung, Yongjin; Holbrow, Charles J; Dasari, Ramachandra R; Feld, Michael S

    2011-01-01

    Tomographic phase microscopy measures the 3-D refractive index distribution of cells and tissues by combining the information from a series of angle-dependent interferometric phase images. In the original device, the frame rate was limited to 0.1 frames per second (fps) by the technique used to acquire phase images, preventing measurements of moving or rapidly changing samples. We describe an improved tomographic phase microscope in which phase images are acquired via a spatial fringe pattern demodulation method, enabling a full tomogram acquisition rate of 30 fps. In addition, in this system the refractive index is calculated by a diffraction tomography algorithm that accounts for the effects of diffraction in the 3-D reconstruction. We use the instrument to quantitatively monitor rapid changes in refractive index within defined subregions of cells due to exposure to acetic acid or changes in medium osmolarity. PMID:21280892

  14. Ex-vivo holographic microscopy and spectroscopic analysis of head and neck cancer

    NASA Astrophysics Data System (ADS)

    Holler, Stephen; Wurtz, Robert; Auyeung, Kelsey; Auyeung, Kris; Paspaley-Grbavac, Milan; Mulroe, Brigid; Sobrero, Maximiliano; Miles, Brett

    2015-03-01

    Optical probes to identify tumor margins in vivo would greatly reduce the time, effort and complexity in the surgical removal of malignant tissue in head and neck cancers. Current approaches involve visual microscopy of stained tissue samples to determine cancer margins, which results in the excision of excess of tissue to assure complete removal of the cancer. Such surgical procedures and follow-on chemotherapy can adversely affect the patient's recovery and subsequent quality of life. In order to reduce the complexity of the process and minimize adverse effects on the patient, we investigate ex vivo tissue samples (stained and unstained) using digital holographic microscopy in conjunction with spectroscopic analyses (reflectance and transmission spectroscopy) in order to determine label-free, optically identifiable characteristic features that may ultimately be used for in vivo processing of cancerous tissues. The tissue samples studied were squamous cell carcinomas and associated controls from patients of varying age, gender and race. Holographic microscopic imaging scans across both cancerous and non-cancerous tissue samples yielded amplitude and phase reconstructions that were correlated with spectral signatures. Though the holographic reconstructions and measured spectra indicate variations even among the same class of tissue, preliminary results indicate the existence of some discriminating features. Further analyses are presently underway to further this work and extract additional information from the imaging and spectral data that may prove useful for in vivo surgical identification.

  15. Fourier phase microscopy with white light

    PubMed Central

    Bhaduri, Basanta; Tangella, Krishnarao; Popescu, Gabriel

    2013-01-01

    Laser-based Fourier phase microscopy (FPM) works on the principle of decomposition of an image field in two spatial components that can be controllably shifted in phase with respect to each other. However, due to the coherent illumination, the contrast in phase images is degraded by speckles. In this paper we present FPM with spatially coherent white light (wFPM), which offers high spatial phase sensitivity due to the low temporal coherence and high temporal phase stability due to common path geometry. Further, by using a fast spatial light modulator (SLM) and a fast scientific-grade complementary metal oxide semiconductor (sCMOS) camera, we report imaging at a maximum rate of 12.5 quantitative phase frames per second with 5.5 mega pixels image size. We illustrate the utility of wFPM as a contrast enhancement as well as dynamic phase measurement method by imaging section of benign colonic glands and red blood cell membrane fluctuation. PMID:24010005

  16. Quantitative Phase Microscopy: how to make phase data meaningful

    PubMed Central

    Goldstein, Goldie; Creath, Katherine

    2014-01-01

    The continued development of hardware and associated image processing techniques for quantitative phase microscopy has allowed superior phase data to be acquired that readily shows dynamic optical volume changes and enables particle tracking. Recent efforts have focused on tying phase data and associated metrics to cell morphology. One challenge in measuring biological objects using interferometrically obtained phase information is achieving consistent phase unwrapping and -dimensions and correct for temporal discrepanices using a temporal unwrapping procedure. The residual background shape due to mean value fluctuations and residual tilts can be removed automatically using a simple object characterization algorithm. Once the phase data are processed consistently, it is then possible to characterize biological samples such as myocytes and myoblasts in terms of their size, texture and optical volume and track those features dynamically. By observing optical volume dynamically it is possible to determine the presence of objects such as vesicles within myoblasts even when they are co-located with other objects. Quantitative phase microscopy provides a label-free mechanism to characterize living cells and their morphology in dynamic environments, however it is critical to connect the measured phase to important biological function for this measurement modality to prove useful to a broader scientific community. In order to do so, results must be highly consistent and require little to no user manipulation to achieve high quality nynerical results that can be combined with other imaging modalities. PMID:25309099

  17. Near-infrared spectroscopic photoacoustic microscopy using a multi-color fiber laser source

    PubMed Central

    Buma, Takashi; Wilkinson, Benjamin C.; Sheehan, Timothy C.

    2015-01-01

    We demonstrate a simple multi-wavelength optical source suitable for spectroscopic optical resolution photoacoustic microscopy (OR-PAM) of lipid-rich tissue. 1064 nm laser pulses are converted to multiple wavelengths beyond 1300 nm via nonlinear optical propagation in a birefringent optical fiber. OR-PAM experiments with lipid phantoms clearly show the expected absorption peak near 1210 nm. We believe this simple multi-color technique is a promising cost-effective approach to spectroscopic OR-PAM of lipid-rich tissue. PMID:26309746

  18. Quantitative temperature measurement of multi-layered semiconductor devices using spectroscopic thermoreflectance microscopy.

    PubMed

    Kim, Dong Uk; Park, Kwan Seob; Jeong, Chan Bae; Kim, Geon Hee; Chang, Ki Soo

    2016-06-27

    Thermoreflectance microscopy is essential in understanding the unpredictable local heating generation that occurs during microelectronic device operation. However, temperature measurements of multi-layered semiconductor devices represent a challenge because the thermoreflectance coefficient is quite small and is dramatically changed by the optical interference inside transparent layers of the device. Therefore, we propose a spectroscopic thermoreflectance microscopy system using a systematic approach for improving the quantitative temperature measurement of multi-layered semiconductor devices. We demonstrate the quantitative measurement of the temperature profile for physical defects on thin-film polycrystalline silicon resistors via thermoreflectance coefficient calibration and effective coefficient κ estimation.

  19. Quantitative temperature measurement of multi-layered semiconductor devices using spectroscopic thermoreflectance microscopy.

    PubMed

    Kim, Dong Uk; Park, Kwan Seob; Jeong, Chan Bae; Kim, Geon Hee; Chang, Ki Soo

    2016-06-27

    Thermoreflectance microscopy is essential in understanding the unpredictable local heating generation that occurs during microelectronic device operation. However, temperature measurements of multi-layered semiconductor devices represent a challenge because the thermoreflectance coefficient is quite small and is dramatically changed by the optical interference inside transparent layers of the device. Therefore, we propose a spectroscopic thermoreflectance microscopy system using a systematic approach for improving the quantitative temperature measurement of multi-layered semiconductor devices. We demonstrate the quantitative measurement of the temperature profile for physical defects on thin-film polycrystalline silicon resistors via thermoreflectance coefficient calibration and effective coefficient κ estimation. PMID:27410553

  20. Quantitative phase-amplitude microscopy. III. The effects of noise.

    PubMed

    Paganin, D; Barty, A; McMahon, P J; Nugent, K A

    2004-04-01

    We explore the effect of noise on images obtained using quantitative phase-amplitude microscopy - a new microscopy technique based on the determination of phase from the intensity evolution of propagating radiation. We compare the predictions with experimental results and also propose an approach that allows good-quality quantitative phase retrieval to be obtained even for very noisy data.

  1. Spectroscopic studies of cold, gas-phase biomolecular ions

    NASA Astrophysics Data System (ADS)

    Rizzo, Thomas R.; Stearns, Jaime A.; Boyarkin, Oleg V.

    While the marriage of mass spectrometry and laser spectroscopy is not new, developments over the last few years in this relationship have opened up new horizons for the spectroscopic study of biological molecules. The combination of electrospray ionisation for producing large biological molecules in the gas phase together with cooled ion traps and multiple-resonance laser schemes are allowing spectroscopic investigation of individual conformations of peptides with more than a dozen amino acids. Highly resolved infrared spectra of single conformations of such species provide important benchmarks for testing the accuracy of theoretical calculations. This review presents a number of techniques employed in our laboratory and in others for measuring the spectroscopy of cold, gas-phase protonated peptides. We show examples that demonstrate the power of these techniques and evaluate their extension to still larger biological molecules.

  2. Phase and fluorescence imaging by combination of digital holographic microscopy and fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Quan, Xiangyu; Nitta, Kouichi; Matoba, Osamu; Xia, Peng; Awatsuji, Yasuhiro

    2015-04-01

    Hybrid digital holographic microscopy that combines fluorescence microscopy and digital holographic microscopy into a single system for biological applications is proposed. In the proposed system, a phase image and a fluorescence image can be obtained simultaneously by selecting the different wavelengths of the fluorescent light and the phase measurement. Especially for biological applications, the cell structure can be obtained by the phase imaging based on digital holography and nucleus of the cell can be obtained by the fluorescence imaging. The measurement of fluorescence beads and egera densa presented the feasibility of simultaneous detection of both a phase image and a fluorescence image.

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

    SciTech Connect

    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.

  4. Ultrastructure of Candida albicans pleomorphic forms: phase-contrast microscopy, scanning and transmission electron microscopy.

    PubMed

    Staniszewska, Monika; Bondaryk, Małgorzata; Siennicka, Katarzyna; Kurzatkowski, Wiesław

    2012-01-01

    A modified method of glutaraldeyde-osmium tetroxide fixation was adjusted to characterize the ultrastructure of Candida albicans pleomorphic forms, using phase-contrast microscopy, scanning electron microscopy and transmission electron microscopy. The discovered morphological criteria defining the individual morphotypes are discussed in terms of mycological and histopathological diagnostics of candidiasis. The relations are discussed between fungal pleomorphism, virulence and susceptibility of different morphotypes to fungicides.

  5. 3D differential phase contrast microscopy

    NASA Astrophysics Data System (ADS)

    Chen, Michael; Tian, Lei; Waller, Laura

    2016-03-01

    We demonstrate three-dimensional (3D) optical phase and amplitude reconstruction based on coded source illumination using a programmable LED array. Multiple stacks of images along the optical axis are computed from recorded intensities captured by multiple images under off-axis illumination. Based on the first Born approximation, a linear differential phase contrast (DPC) model is built between 3D complex index of refraction and the intensity stacks. Therefore, 3D volume reconstruction can be achieved via a fast inversion method, without the intermediate 2D phase retrieval step. Our system employs spatially partially coherent illumination, so the transverse resolution achieves twice the NA of coherent systems, while axial resolution is also improved 2× as compared to holographic imaging.

  6. Phase contrast in high resolution electron microscopy

    DOEpatents

    Rose, H.H.

    1975-09-23

    This patent relates to a device for developing a phase contrast signal for a scanning transmission electron microscope. The lens system of the microscope is operated in a condition of defocus so that predictable alternate concentric regions of high and low electron density exist in the cone of illumination. Two phase detectors are placed beneath the object inside the cone of illumination, with the first detector having the form of a zone plate, each of its rings covering alternate regions of either higher or lower electron density. The second detector is so configured that it covers the regions of electron density not covered by the first detector. Each detector measures the number of electrons incident thereon and the signal developed by the first detector is subtracted from the signal developed by the record detector to provide a phase contrast signal. (auth)

  7. Detection of a MoSe{sub 2} secondary phase layer in CZTSe by spectroscopic ellipsometry

    SciTech Connect

    Demircioğlu, Özden; Riedel, Ingo; Gütay, Levent; Mousel, Marina; Redinger, Alex; Rey, Germain; Weiss, Thomas; Siebentritt, Susanne

    2015-11-14

    We demonstrate the application of Spectroscopic Ellipsometry (SE) for identification of secondary phase MoSe{sub 2} in polycrystalline Cu{sub 2}ZnSnSe{sub 4} (CZTSe) samples. A MoSe{sub 2} reference sample was analyzed, and its optical constants (ε{sub 1} and ε{sub 2}) were extracted by SE analysis. This dataset was implemented into an optical model for analyzing SE data from a glass/Mo/CZTSe sample containing MoSe{sub 2} at the back side of the absorber. We present results on the n and k values of CZTSe and show the extraction of the thickness of the secondary phase MoSe{sub 2} layer. Raman spectroscopy and scanning electron microscopy were applied to confirm the SE results.

  8. Partial wave spectroscopic microscopy can predict prostate cancer progression and mitigate over-treatment (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Zhang, Di; Graff, Taylor; Crawford, Susan; Subramanian, Hariharan; Thompson, Sebastian; Derbas, Justin R.; Lyengar, Radha; Roy, Hemant K.; Brendler, Charles B.; Backman, Vadim

    2016-02-01

    Prostate Cancer (PC) is the second leading cause of cancer deaths in American men. While prostate specific antigen (PSA) test has been widely used for screening PC, >60% of the PSA detected cancers are indolent, leading to unnecessary clinical interventions. An alternative approach, active surveillance (AS), also suffer from high expense, discomfort and complications associated with repeat biopsies (every 1-3 years), limiting its acceptance. Hence, a technique that can differentiate indolent from aggressive PC would attenuate the harms from over-treatment. Combining microscopy with spectroscopy, our group has developed partial wave spectroscopic (PWS) microscopy, which can quantify intracellular nanoscale organizations (e.g. chromatin structures) that are not accessible by conventional microscopy. PWS microscopy has previously been shown to predict the risk of cancer in seven different organs (N ~ 800 patients). Herein we use PWS measurement of label-free histologically-normal prostatic epithelium to distinguish indolent from aggressive PC and predict PC risk. Our results from 38 men with low-grade PC indicated that there is a significant increase in progressors compared to non-progressors (p=0.002, effect size=110%, AUC=0.80, sensitivity=88% and specificity=72%), while the baseline clinical characteristics were not significantly different. We further improved the diagnostic power by performing nuclei-specific measurements using an automated system that separates in real-time the cell nuclei from the remaining prostate epithelium. In the long term, we envision that the PWS based prognostication can be coupled with AS without any change to the current procedure to mitigate the harms caused by over-treatment.

  9. Phase contrast and operation regimes in multifrequency atomic force microscopy

    SciTech Connect

    Santos, Sergio

    2014-04-07

    In amplitude modulation atomic force microscopy the attractive and the repulsive force regimes induce phase shifts above and below 90°, respectively. In the more recent multifrequency approach, however, multiple operation regimes have been reported and the theory should be revisited. Here, a theory of phase contrast in multifrequency atomic force microscopy is developed and discussed in terms of energy transfer between modes, energy dissipation and the kinetic energy and energy transfer associated with externally driven harmonics. The single frequency virial that controls the phase shift might undergo transitions in sign while the average force (modal virial) remains positive (negative)

  10. Nonlinear dynamic phase contrast microscopy for microfluidic and microbiological applications

    NASA Astrophysics Data System (ADS)

    Denz, C.; Holtmann, F.; Woerdemann, M.; Oevermann, M.

    2008-08-01

    In live sciences, the observation and analysis of moving living cells, molecular motors or motion of micro- and nano-objects is a current field of research. At the same time, microfluidic innovations are needed for biological and medical applications on a micro- and nano-scale. Conventional microscopy techniques are reaching considerable limits with respect to these issues. A promising approach for this challenge is nonlinear dynamic phase contrast microscopy. It is an alternative full field approach that allows to detect motion as well as phase changes of living unstained micro-objects in real-time, thereby being marker free, without contact and non destructive, i.e. fully biocompatible. The generality of this system allows it to be combined with several other microscope techniques such as conventional bright field or fluorescence microscopy. In this article we will present the dynamic phase contrast technique and its applications in analysis of micro organismic dynamics, micro flow velocimetry and micro-mixing analysis.

  11. Quantitative Phase Microscopy of Live Biological Cell Dynamics

    NASA Astrophysics Data System (ADS)

    Shaked, Natan T.; Wax, Adam

    2010-04-01

    Interferometric phase microscopy of biological cell dynamics has the potential to provide a label-free quantitative tool for cell biology, as well as for medical diagnosis and monitoring. The current state of the art of this field, the open questions, and specific solutions developed in our laboratory will be presented.

  12. Phase contrast microscopy with full numerical aperture illumination.

    PubMed

    Maurer, Christian; Jesacher, Alexander; Bernet, Stefan; Ritsch-Marte, Monika

    2008-11-24

    A modification of the phase contrast method in microscopy is presented, which reduces inherent artifacts and improves the spatial resolution. In standard Zernike phase contrast microscopy the illumination is achieved through an annular ring aperture, and the phase filtering operation is performed by a corresponding phase ring in the back focal plane of the objective. The Zernike method increases the spatial resolution as compared to plane wave illumination, but it also produces artifacts, such as the halo- and the shade-off effect. Our modification consists in replacing the illumination ring by a set of point apertures which are randomly distributed over the whole aperture of the condenser, and in replacing the Zernike phase ring by a matched set of point-like phase shifters in the back focal plane of the objective. Experimentally this is done by illuminating the sample with light diffracted from a phase hologram displayed at a spatial light modulator (SLM). The subsequent filtering operation is then done with a second matched phase hologram displayed at another SLM in a Fourier plane of the imaging pathway. This method significantly reduces the halo- and shade-off artifacts whilst providing the full spatial resolution of the microscope. PMID:19030068

  13. Another 60 years in electron microscopy: development of phase-plate electron microscopy and biological applications.

    PubMed

    Nagayama, Kuniaki

    2011-01-01

    It has been six decades since the concept of phase-plate electron microscopy was first reported by Boersch, but an experimental report on a phase plate with a theoretically rational performance has only recently been released by a group including the present author. Currently, many laboratories around the world are attempting to develop a wide range of phase plates to enhance the capabilities of transmission electron microscopy. They are reporting not only advantages of their own developments but also a fundamental problem inherent to electron beam devices, namely charging, i.e. the accumulation of electrostatic charge. In this report, we review the 60-year history of phase-plate development, with a particular focus on the fundamental issue of phase-plate charging. Next, we review biological applications of qualified phase plates, which have been successful in avoiding charging to some extent. Finally, we compare and discuss electron microscopic images, taken with or without phase plates, of biological targets such as proteins (GroEL and TRPV4), protein complexes (flagellar motor), viruses (T4 phage, ε-15 phage and herpes simplex virus), bacterial (cyanobacteria) and mammalian (PtK2) cells. PMID:21844600

  14. Spectroscopic microscopy can quantify the statistics of subdiffractional refractive-index fluctuations in media with random rough surfaces.

    PubMed

    Zhang, Di; Cherkezyan, Lusik; Capoglu, Ilker; Subramanian, Hariharan; Chandler, John; Thompson, Sebastian; Taflove, Allen; Backman, Vadim

    2015-11-01

    We previously established that spectroscopic microscopy can quantify subdiffraction-scale refractive index (RI) fluctuations in a label-free dielectric medium with a smooth surface. However, to study more realistic samples, such as biological cells, the effect of rough surface should be considered. In this Letter, we first report an analytical theory to synthesize microscopic images of a rough surface, validate this theory by finite-difference time-domain (FDTD) solutions of Maxwell's equations, and characterize the spectral properties of light reflected from a rough surface. Then, we report a technique to quantify the RI fluctuations beneath a rough surface and demonstrate its efficacy on FDTD-synthesized spectroscopic microscopy images, as well as experimental data obtained from biological cells.

  15. Spectroscopic microscopy can quantify the statistics of subdiffractional refractive-index fluctuations in media with random rough surfaces.

    PubMed

    Zhang, Di; Cherkezyan, Lusik; Capoglu, Ilker; Subramanian, Hariharan; Chandler, John; Thompson, Sebastian; Taflove, Allen; Backman, Vadim

    2015-11-01

    We previously established that spectroscopic microscopy can quantify subdiffraction-scale refractive index (RI) fluctuations in a label-free dielectric medium with a smooth surface. However, to study more realistic samples, such as biological cells, the effect of rough surface should be considered. In this Letter, we first report an analytical theory to synthesize microscopic images of a rough surface, validate this theory by finite-difference time-domain (FDTD) solutions of Maxwell's equations, and characterize the spectral properties of light reflected from a rough surface. Then, we report a technique to quantify the RI fluctuations beneath a rough surface and demonstrate its efficacy on FDTD-synthesized spectroscopic microscopy images, as well as experimental data obtained from biological cells. PMID:26512486

  16. Label-free imaging of the native, living cellular nanoarchitecture using partial-wave spectroscopic microscopy

    PubMed Central

    Almassalha, Luay M.; Bauer, Greta M.; Chandler, John E.; Gladstein, Scott; Cherkezyan, Lusik; Stypula-Cyrus, Yolanda; Weinberg, Samuel; Zhang, Di; Thusgaard Ruhoff, Peder; Roy, Hemant K.; Subramanian, Hariharan; Chandel, Navdeep S.; Szleifer, Igal; Backman, Vadim

    2016-01-01

    The organization of chromatin is a regulator of molecular processes including transcription, replication, and DNA repair. The structures within chromatin that regulate these processes span from the nucleosomal (10-nm) to the chromosomal (>200-nm) levels, with little known about the dynamics of chromatin structure between these scales due to a lack of quantitative imaging technique in live cells. Previous work using partial-wave spectroscopic (PWS) microscopy, a quantitative imaging technique with sensitivity to macromolecular organization between 20 and 200 nm, has shown that transformation of chromatin at these length scales is a fundamental event during carcinogenesis. As the dynamics of chromatin likely play a critical regulatory role in cellular function, it is critical to develop live-cell imaging techniques that can probe the real-time temporal behavior of the chromatin nanoarchitecture. Therefore, we developed a live-cell PWS technique that allows high-throughput, label-free study of the causal relationship between nanoscale organization and molecular function in real time. In this work, we use live-cell PWS to study the change in chromatin structure due to DNA damage and expand on the link between metabolic function and the structure of higher-order chromatin. In particular, we studied the temporal changes to chromatin during UV light exposure, show that live-cell DNA-binding dyes induce damage to chromatin within seconds, and demonstrate a direct link between higher-order chromatin structure and mitochondrial membrane potential. Because biological function is tightly paired with structure, live-cell PWS is a powerful tool to study the nanoscale structure–function relationship in live cells. PMID:27702891

  17. Quantitative phase microscopy and synthetic aperture tomography of live cells

    NASA Astrophysics Data System (ADS)

    Lue, Niyom

    For more than a decade MIT's George R. Harrison Spectroscopy Laboratory has been developing quantitative phase microscopy (QPM) for biological study. Measurements of a point field were made in the mid 90s, then extended to the full 2D field, and recently, to 3D by using tomography. In the first part of this thesis improvements in the techniques of Fourier Phase Microscopy (FPM) and Hilbert Phase Microscopy (HPM) and their applications to characterize cells and tissues are reported. Tomographic phase microscopy (TPM) provides quantitative information and highly detailed structural information about a live cell, but in its current form it can only examine one cell at a time. Many biological applications including statistical analysis of a large collection of cells such as flow cytometry need a tomography technique that can measure many cells at a time. For the second part of this thesis we have developed a new tomography technique that can measure many cells continuously. In this study we demonstrate the new technique by translating a live cell across a focused beam. This beam is composed of many angular plane waves, and by applying a so-called synthetic aperture algorithm we retrieve individual wave components of the focused beam. We demonstrate for the first time that we can retrieve the field of the focused beam and synthesize any arbitrary angular plane wave. We then construct a 3D map of the variations of the refractive index in a live cell from a series of these synthesized angular plane waves. This new technique is the first step needed to analyze cells flowing through a beam to provide a high-throughput 3D refractive index tomograms that can be used as a new kind of statistical optical assay of living cells.

  18. Phase modulation mode of scanning ion conductance microscopy

    SciTech Connect

    Li, Peng; Zhang, Changlin; Liu, Lianqing E-mail: gli@engr.pitt.edu; Wang, Yuechao; Yang, Yang; Li, Guangyong E-mail: gli@engr.pitt.edu

    2014-08-04

    This Letter reports a phase modulation (PM) mode of scanning ion conductance microscopy. In this mode, an AC current is directly generated by an AC voltage between the electrodes. The portion of the AC current in phase with the AC voltage, which is the current through the resistance path, is modulated by the tip-sample distance. It can be used as the input of feedback control to drive the scanner in Z direction. The PM mode, taking the advantages of both DC mode and traditional AC mode, is less prone to electronic noise and DC drift but maintains high scanning speed. The effectiveness of the PM mode has been proven by experiments.

  19. Single beam Fourier transform digital holographic quantitative phase microscopy

    SciTech Connect

    Anand, A. Chhaniwal, V. K.; Mahajan, S.; Trivedi, V.; Faridian, A.; Pedrini, G.; Osten, W.; Dubey, S. K.; Javidi, B.

    2014-03-10

    Quantitative phase contrast microscopy reveals thickness or height information of a biological or technical micro-object under investigation. The information obtained from this process provides a means to study their dynamics. Digital holographic (DH) microscopy is one of the most used, state of the art single-shot quantitative techniques for three dimensional imaging of living cells. Conventional off axis DH microscopy directly provides phase contrast images of the objects. However, this process requires two separate beams and their ratio adjustment for high contrast interference fringes. Also the use of two separate beams may make the system more vulnerable to vibrations. Single beam techniques can overcome these hurdles while remaining compact as well. Here, we describe the development of a single beam DH microscope providing whole field imaging of micro-objects. A hologram of the magnified object projected on to a diffuser co-located with a pinhole is recorded with the use of a commercially available diode laser and an arrayed sensor. A Fourier transform of the recorded hologram directly yields the complex amplitude at the image plane. The method proposed was investigated using various phase objects. It was also used to image the dynamics of human red blood cells in which sub-micrometer level thickness variation were measurable.

  20. Laser-scanning photoacoustic microscopy with ultrasonic phased array transducer.

    PubMed

    Zheng, Fan; Zhang, Xiangyang; Chiu, Chi Tat; Zhou, Bill L; Shung, K Kirk; Zhang, Hao F; Jiao, Shuliang

    2012-11-01

    In this paper, we report our latest progress on proving the concept that ultrasonic phased array can improve the detection sensitivity and field of view (FOV) in laser-scanning photoacoustic microscopy (LS-PAM). A LS-PAM system with a one-dimensional (1D) ultrasonic phased array was built for the experiments. The 1D phased array transducer consists of 64 active elements with an overall active dimension of 3.2 mm × 2 mm. The system was tested on imaging phantom and mouse ear in vivo. Experiments showed a 15 dB increase of the signal-to-noise ratio (SNR) when beamforming was employed compared to the images acquired with each single element. The experimental results demonstrated that ultrasonic phased array can be a better candidate for LS-PAM in high sensitivity applications like ophthalmic imaging.

  1. Spiral phase plate contrast in optical and electron microscopy

    NASA Astrophysics Data System (ADS)

    Juchtmans, Roeland; Clark, Laura; Lubk, Axel; Verbeeck, Jo

    2016-08-01

    The use of phase plates in the back focal plane of a microscope is a well-established technique in optical microscopy to increase the contrast of weakly interacting samples and is gaining interest in electron microscopy as well. In this paper we study the spiral phase plate (SPP), also called helical, vortex, or two-dimensional Hilbert phase plate, which adds an angularly dependent phase of the form ei ℓ ϕk to the exit wave in Fourier space. In the limit of large collection angles, we analytically calculate that the average of a pair of ℓ =±1 SPP filtered images is directly proportional to the gradient squared of the exit wave, explaining the edge contrast previously seen in optical SPP work. We discuss the difference between a clockwise-anticlockwise pair of SPP filtered images and derive conditions under which the modulus of the wave's gradient can be seen directly from one SPP filtered image. This work provides the theoretical background to interpret images obtained with a SPP, thereby opening new perspectives for new experiments to study, for example, magnetic materials in an electron microscope.

  2. Four-dimensional ultrafast electron microscopy of phase transitions.

    PubMed

    Grinolds, Michael S; Lobastov, Vladimir A; Weissenrieder, Jonas; Zewail, Ahmed H

    2006-12-01

    Reported here is direct imaging (and diffraction) by using 4D ultrafast electron microscopy (UEM) with combined spatial and temporal resolutions. In the first phase of UEM, it was possible to obtain snapshot images by using timed, single-electron packets; each packet is free of space-charge effects. Here, we demonstrate the ability to obtain sequences of snapshots ("movies") with atomic-scale spatial resolution and ultrashort temporal resolution. Specifically, it is shown that ultrafast metal-insulator phase transitions can be studied with these achieved spatial and temporal resolutions. The diffraction (atomic scale) and images (nanometer scale) we obtained manifest the structural phase transition with its characteristic hysteresis, and the time scale involved (100 fs) is now studied by directly monitoring coordinates of the atoms themselves. PMID:17130445

  3. Examining cardiomyocyte development with spectral domain phase microscopy

    NASA Astrophysics Data System (ADS)

    Ellerbee, Audrey K.; Creazzo, Tony L.; Izatt, Joseph A.

    2007-02-01

    Phase-sensitive detection has long been recognized as a mechanism for increasing imaging contrast. The proliferation of quantitative phase contrast techniques and the breadth of emerging applications reflects the potential for achieving subdiffraction- limited resolution of cellular structure and dynamic phenomena with phase. Our laboratory developed spectral domain phase microscopy (SDPM) as a simple, phase-stable tool for studying cell dynamics and structure. As a functional extension of optical coherence tomography (OCT), SDPM inherited the high-resolution depth-sectioning capabilities for which OCT is well known, but adds to this an ability to discriminate sub-coherence length changes in optical pathlength within target samples at discrete axial positions. Early demonstrations of SDPM showed it to be extremely sensitive to thickness changes in biological and non-biological samples; the results of our previous studies investigating cell surface motion in cardiomyocyte contractility, cytoplasmic streaming rates in single-celled organisms, and rheological properties of the cytoskeleton suggest that SDPM can contribute insights of biological relevance. The principal aim of this work is to refine SDPM to enable imaging, interrogation, and quantification of parameters of interest in developing cardiomyocytes. In this manuscript, we report on the technology advances that enable multidimensional SDPM, and the results of new inotropic imaging studies of chick embryo cardiomyocytes.

  4. Efficient Phase Unwrapping Architecture for Digital Holographic Microscopy

    PubMed Central

    Hwang, Wen-Jyi; Cheng, Shih-Chang; Cheng, Chau-Jern

    2011-01-01

    This paper presents a novel phase unwrapping architecture for accelerating the computational speed of digital holographic microscopy (DHM). A fast Fourier transform (FFT) based phase unwrapping algorithm providing a minimum squared error solution is adopted for hardware implementation because of its simplicity and robustness to noise. The proposed architecture is realized in a pipeline fashion to maximize throughput of the computation. Moreover, the number of hardware multipliers and dividers are minimized to reduce the hardware costs. The proposed architecture is used as a custom user logic in a system on programmable chip (SOPC) for physical performance measurement. Experimental results reveal that the proposed architecture is effective for expediting the computational speed while consuming low hardware resources for designing an embedded DHM system. PMID:22163688

  5. Nanoscale Thermotropic Phase Transitions Enhancing Photothermal Microscopy Signals.

    PubMed

    Parra-Vasquez, A Nicholas G; Oudjedi, Laura; Cognet, Laurent; Lounis, Brahim

    2012-05-17

    The photothermal heterodyne imaging technique enables studies of individual weakly absorbing nano-objects in various environments. It uses a photoinduced change in the refractive index of the environment. Taking advantage of the dramatic index of refraction change occurring around a thermotropic liquid-crystalline phase transition, we demonstrate a 40-fold signal-to-noise ratio enhancement for gold nanoparticles imaged in 4-cyano-4'-pentylbiphenyl (5CB) liquid crystals over those in a water environment. We studied the photothermal signal as a function of probe laser polarization, heating power, and sample temperature quantifying the optimal enhancement. This study established photothermal microscopy as a valuable technique for inducing and/or detecting local phase transitions at the nanometer scales.

  6. Differential phase contrast in scanning x-ray microscopy with half-wavelength phase shifter

    NASA Astrophysics Data System (ADS)

    Suzuki, Yoshio; Takeuchi, Akihisa

    2016-01-01

    A method for differential-phase-contrast imaging in scanning x-ray microscopy is proposed. The microfocus beam is produced with an x-ray focusing optics, and a half of the optical aperture is masked with a λ/2 phase shifter. This generates a pair of focused beam at the focal plane, with π phase difference. Combining with a diaphragm in front of the transmission beam detector, differential phase contrast (contrast proportional to the phase-difference between two foci) can be obtained. Preliminary results with a Fresnel zone plate focusing optics at 12.4 keV x-ray energy are shown.

  7. Multi-pore carbon phase plate for phase-contrast transmission electron microscopy.

    PubMed

    Sannomiya, Takumi; Junesch, Juliane; Hosokawa, Fumio; Nagayama, Kuniaki; Arai, Yoshihiro; Kayama, Yoko

    2014-11-01

    A new fabrication method of carbon based phase plates for phase-contrast transmission electron microscopy is presented. This method utilizes colloidal masks to produce pores as well as disks on thin carbon membranes for phase modulation. Since no serial process is involved, carbon phase plate membranes containing hundreds of pores can be mass-produced on a large scale, which allows "disposal" of contaminated or degraded phase modulating objects after use. Due to the spherical shape of the mask colloid particles, the produced pores are perfectly circular. The pore size and distribution can be easily tuned by the mask colloid size and deposition condition. By using the stencil method, disk type phase plates can also be fabricated on a pore type phase plate. Both pore and disk type phase plates were tested by measuring amorphous samples and confirmed to convert the sinus phase contrast transfer function to the cosine shape. PMID:25129640

  8. Quantitative phase imaging by single-shot Hilbert-Huang phase microscopy.

    PubMed

    Trusiak, Maciej; Mico, Vicente; Garcia, Javier; Patorski, Krzysztof

    2016-09-15

    We propose a novel single-shot Hilbert-Huang transform-based algorithm applied to digital holographic microscopy (DHM) for robust, fast, and accurate single-shot quantitative phase imaging in on-axis and off-axis configurations. Fringe pattern with possible defects and closed fringes are adaptively filtered and accurately phase demodulated using local fringe direction estimation. Experimental validation of the proposed techniques is presented as the DHM study of microbeads and red blood cells phase samples. Obtained results compare very favorably with the Fourier approach (off-axis) and temporal phase shifting (on-axis). PMID:27628393

  9. Tomographic phase microscopy of living three-dimensional cell cultures.

    PubMed

    Kuś, Arkadiusz; Dudek, Michał; Kemper, Björn; Kujawińska, Małgorzata; Vollmer, Angelika

    2014-04-01

    A successful application of self-interference digital holographic microscopy in combination with a sample-rotation-based tomography module for three-dimensional (3-D) label-free quantitative live cell imaging with subcellular resolution is demonstrated. By means of implementation of a hollow optical fiber as the sample cuvette, the observation of living cells in different 3-D matrices is enabled. The fiber delivers a stable and accurate rotation of a cell or cell cluster, providing quantitative phase data for tomographic reconstruction of the 3-D refractive index distribution with an isotropic spatial resolution. We demonstrate that it is possible to clearly distinguish and quantitatively analyze several cells grouped in a "3-D cluster" as well as subcellular organelles like the nucleoli and local internal refractive index changes. PMID:24723114

  10. Rapid quantitative phase imaging for partially coherent light microscopy.

    PubMed

    Rodrigo, José A; Alieva, Tatiana

    2014-06-01

    Partially coherent light provides promising advantages for imaging applications. In contrast to its completely coherent counterpart, it prevents image degradation due to speckle noise and decreases cross-talk among the imaged objects. These facts make attractive the partially coherent illumination for accurate quantitative imaging in microscopy. In this work, we present a non-interferometric technique and system for quantitative phase imaging with simultaneous determination of the spatial coherence properties of the sample illumination. Its performance is experimentally demonstrated in several examples underlining the benefits of partial coherence for practical imagining applications. The programmable optical setup comprises an electrically tunable lens and sCMOS camera that allows for high-speed measurement in the millisecond range.

  11. Microsecond Scale Vibrational Spectroscopic Imaging by Multiplex Stimulated Raman Scattering Microscopy

    PubMed Central

    Liao, Chien-Sheng; Slipchenko, Mikhail N.; Wang, Ping; Li, Junjie; Lee, Seung-Young; Oglesbee, Robert A.; Cheng, Ji-Xin

    2015-01-01

    Real-time vibrational spectroscopic imaging is desired for monitoring cellular states and cellular processes in a label-free manner. Raman spectroscopic imaging of highly dynamic systems is inhibited by relatively slow spectral acquisition on millisecond to second scale. Here, we report microsecond scale vibrational spectroscopic imaging by lock-in free parallel detection of spectrally dispersed stimulated Raman scattering signal. Using a homebuilt tuned amplifier array, our method enables Raman spectral acquisition, within the window defined by the broadband pulse, at the speed of 32 microseconds and with close to shot-noise limited detection sensitivity. Incorporated with multivariate curve resolution analysis, our platform allows compositional mapping of lipid droplets in single live cells, observation of intracellular retinoid metabolism, discrimination of fat droplets from protein-rich organelles in Caenorhabditis elegans, spectral detection of fast flowing tumor cells, and monitoring drug diffusion through skin tissue in vivo. The reported technique opens new opportunities for compositional analysis of cellular compartment in a microscope setting and high-throughput spectral profiling of single cells in a flow cytometer setting. PMID:26167336

  12. Computational methods for microfluidic microscopy and phase-space imaging

    NASA Astrophysics Data System (ADS)

    Pegard, Nicolas Christian Richard

    Modern optical devices are made by assembling separate components such as lenses, objectives, and cameras. Traditionally, each part is optimized separately, even though the trade-offs typically limit the performance of the system overall. This component-based approach is particularly unfit to solve the new challenges brought by modern biology: 3D imaging, in vivo environments, and high sample throughput. In the first part of this thesis, we introduce a general method to design integrated optical systems. The laws of wave propagation, the performance of available technology, as well as other design parameters are combined as constraints into a single optimization problem. The solution provides qualitative design rules to improve optical systems as well as quantitative task-specific methods to minimize loss of information. Our results have applications in optical data storage, holography, and microscopy. The second part of this dissertation presents a direct application. We propose a more efficient design for wide-field microscopy with coherent light, based on double transmission through the sample. Historically, speckle noise and aberrations caused by undesired interferences have made coherent illumination unpopular for imaging. We were able to dramatically reduce speckle noise and unwanted interferences using optimized holographic wavefront reconstruction. The resulting microscope not only yields clear coherent images with low aberration---even in thick samples---but also increases contrast and enables optical filtering and in-depth sectioning. In the third part, we develop new imaging techniques that better respond to the needs of modern biology research through implementing optical design optimization. Using a 4D phase-space distribution, we first represent the state and propagation of incoherent light. We then introduce an additional degree of freedom by putting samples in motion in a microfluidic channel, increasing image diversity. From there, we develop a

  13. Effects of spatial coherence in diffraction phase microscopy.

    PubMed

    Edwards, Chris; Bhaduri, Basanta; Nguyen, Tan; Griffin, Benjamin G; Pham, Hoa; Kim, Taewoo; Popescu, Gabriel; Goddard, Lynford L

    2014-03-10

    Quantitative phase imaging systems using white light illumination can exhibit lower noise figures than laser-based systems. However, they can also suffer from object-dependent artifacts, such as halos, which prevent accurate reconstruction of the surface topography. In this work, we show that white light diffraction phase microscopy using a standard halogen lamp can produce accurate height maps of even the most challenging structures provided that there is proper spatial filtering at: 1) the condenser to ensure adequate spatial coherence and 2) the output Fourier plane to produce a uniform reference beam. We explain that these object-dependent artifacts are a high-pass filtering phenomenon, establish design guidelines to reduce the artifacts, and then apply these guidelines to eliminate the halo effect. Since a spatially incoherent source requires significant spatial filtering, the irradiance is lower and proportionally longer exposure times are needed. To circumvent this tradeoff, we demonstrate that a supercontinuum laser, due to its high radiance, can provide accurate measurements with reduced exposure times, allowing for fast dynamic measurements. PMID:24663853

  14. Silver nanoparticle-induced degranulation observed with quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Yang, Wenzhong; Lee, Seungrag; Lee, Jiyong; Bae, Yoonsung; Kim, Dugyoung

    2010-02-01

    The use of AgNP is becoming more and more widespread in biomedical field. But compared with the promising bactericidal function, other physiological effects of AgNP on cells are relatively scant. In this research, we propose quantitative phase microscopy (QPM) as a new method to study the degranulation, and AgNP-induced RBL-2H3 cell degranulation is studied as well. Firstly, HeLa cells as the cell control and PBS as the solvent control, we measured the cell volume and cross section profile (x-z plane) with QPM. The results showed that the volume and cross section profile changed only the RBL-2H3 cells exposed to calcium ionophore A23187, which demonstrates the validity of QPM in degranulation research. Secondly, 50μg/mL of AgNP was used instead of A23187, and the measurement of cell volume and cross section profile was carried out again. RBL-2H3 cell volume increased immediately after AgNP was added, and cross section profile showed that the cell surface became granulated, but HeLa cell was lack of that effect. Phase images obviously indicated the RBL-2H3 cell deformation. Thirdly, stained with Fluo-3/AM, intracellular calcium Ca2+]i of single RBL-2H3 cell treated with AgNP was observed with fluorescent microscopy; incubated with AgNP for 20min, the supernatant of RBL-2H3 cells was collected and reacted with o-phthalaldehyde (OPA), then the fluorescent intensity of histamine-OPA complex was assayed with spectrofluorometer. The results of Ca2+]i and histamine increase showed that degranulation of AgNP-induced RBL-2H3 cell occurred. So, the cell volume was used as a parameter of degranulation in our study and AgNP-induced RBL-2H3 cells degranulation was confirmed by the cell volume increment, cross section profile change, and [Ca2+]i and histamine in supernatant increase.

  15. Electronic Structure of the Cuprate Superconducting and Pseudogap Phases from Spectroscopic Imaging STM

    SciTech Connect

    Davis, J.C.; Schmidt, A.R.; Fujita, K.; Kim, E.-A.; Lawler, M.J.; Eisaki, H.; Uchida, S.; Lee, D.-H.

    2011-06-21

    We survey the use of spectroscopic imaging scanning tunneling microscopy (SI-STM) to probe the electronic structure of underdoped cuprates. Two distinct classes of electronic states are observed in both the d-wave superconducting (dSC) and the pseudogap (PG) phases. The first class consists of the dispersive Bogoliubov quasiparticle excitations of a homogeneous d-wave superconductor, existing below a lower energy scale E = {Delta}{sub 0}. We find that the Bogoliubov quasiparticle interference (QPI) signatures of delocalized Cooper pairing are restricted to a k-space arc, which terminates near the lines connecting k = {+-}({pi}/a{sub 0},0) to k = {+-}(0,{pi}/a{sub 0}). This arc shrinks continuously with decreasing hole density such that Luttinger's theorem could be satisfied if it represents the front side of a hole-pocket that is bounded behind by the lines between k = {+-}({pi}/a{sub 0},0) and k = {+-}(0,{pi}/a{sub 0}). In both phases, the only broken symmetries detected for the |E| < {Delta}{sub 0} states are those of a d-wave superconductor. The second class of states occurs proximate to the PG energy scale E = {Delta}{sub 1}. Here the non-dispersive electronic structure breaks the expected 90{sup o}-rotational symmetry of electronic structure within each unit cell, at least down to 180{sup o}-rotational symmetry. This electronic symmetry breaking was first detected as an electronic inequivalence at the two oxygen sites within each unit cell by using a measure of nematic (C{sub 2}) symmetry. Incommensurate non-dispersive conductance modulations, locally breaking both rotational and translational symmetries, coexist with this intra-unit-cell electronic symmetry breaking at E = {Delta}{sub 1}. Their characteristic wavevector Q is determined by the k-space points where Bogoliubov QPI terminates and therefore changes continuously with doping. The distinct broken electronic symmetry states (intra-unit-cell and finite Q) coexisting at E {approx} {Delta}{sub 1} are

  16. Photoelectrochemical fabrication of spectroscopic diffraction gratings, phase 2

    NASA Technical Reports Server (NTRS)

    Rauh, R. David; Carrabba, Michael M.; Li, Jianguo; Cartland, Robert F.; Hachey, John P.; Mathew, Sam

    1990-01-01

    This program was directed toward the production of Echelle diffraction gratings by a light-driven, electrochemical etching technique (photoelectrochemical etching). Etching is carried out in single crystal materials, and the differential rate of etching of the different crystallographic planes used to define the groove profiles. Etching of V-groove profiles was first discovered by us during the first phase of this project, which was initially conceived as a general exploration of photoelectrochemical etching techniques for grating fabrication. This highly controllable V-groove etching process was considered to be of high significance for producing low pitch Echelles, and provided the basis for a more extensive Phase 2 investigation.

  17. CONFOCAL MICROSCOPY SYSTEM PERFORMANCE: FOUNDATIONS FOR QUANTIFYING CYTOMETRIC APPLICATIONS WITH SPECTROSCOPIC INSTRUMENTS

    EPA Science Inventory

    The confocal laser-scanning microscopy (CLSM) has enormous potential in many biological fields. The goal of a CLSM is to acquire and quantify fluorescence and in some instruments acquire spectral characterization of the emitted signal. The accuracy of these measurements demands t...

  18. Atomic oxygen effects on thin film space coatings studied by spectroscopic ellipsometry, atomic force microscopy, and laser light scattering

    NASA Technical Reports Server (NTRS)

    Synowicki, R. A.; Hale, Jeffrey S.; Woollam, John A.

    1992-01-01

    The University of Nebraska is currently evaluating Low Earth Orbit (LEO) simulation techniques as well as a variety of thin film protective coatings to withstand atomic oxygen (AO) degradation. Both oxygen plasma ashers and an electron cyclotron resonance (ECR) source are being used for LEO simulation. Thin film coatings are characterized by optical techniques including Variable Angle Spectroscopic Ellipsometry, Optical spectrophotometry, and laser light scatterometry. Atomic Force Microscopy (AFM) is also used to characterize surface morphology. Results on diamondlike carbon (DLC) films show that DLC degrades with simulated AO exposure at a rate comparable to Kapton polyimide. Since DLC is not as susceptible to environmental factors such as moisture absorption, it could potentially provide more accurate measurements of AO fluence on short space flights.

  19. On measuring cell confluence in phase contrast microscopy

    NASA Astrophysics Data System (ADS)

    Dempsey, K. P.; Richardson, J. B.; Lam, K. P.

    2014-03-01

    A principal focus highlighting recent advances in cell based therapies concerns the development of effective treatments for osteoarthritis. Earlier clinicaltrials have shown that 80% of patients receiving mesenchymal stem cell(MSC) based treatment have improved their quality of life by alleviating pain whilst extending the life of their natural joints. The current challenge facing researchers is to identify the biological differences between the treatments that have worked and those which have shown little improvement. One possible candidate for the difference in treatment prognosis is an examination of the proliferation of the ( type) cells as they grow. To further understanding of the proliferation and differentiation of MSC, non-invasive live cell imaging techniques have been developed which capture important cell events and dynamics in cell divisions over an extended period of time. An automated image analysis procedure capable of tracking cell confluence over time has also been implemented, providing an objective and realistic estimation of cell growth within continuous live cell cultures. The proposed algorithm accounts for the halo artefacts that occur in phase microscopy. In addition to a favourable run-time performance, the method was also validated using continuous live MSC cultures, with consistent and meaningful results.

  20. Silver nanoparticle-induced degranulation observed with quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Yang, Wenzhong; Lee, Seungrag; Lee, Jiyong; Bae, Yoonsung; Kim, Dugyoung

    2010-07-01

    Monitoring a degranulation process in a live mast cell is a quite important issue in immunology and pharmacology. Because the size of a granule is normally much smaller than the resolution limit of an optical microscope system, there is no direct real-time live cell imaging technique for observing degranulation processes except for fluorescence imaging techniques. In this research, we propose optical quantitative phase microscopy (QPM) as a new observation tool to study degranulation processes in a live mast cell without any fluorescence labeling. We measure the cell volumes and the cross sectional profiles (x-z plane) of an RBL-2H3 cell and a HeLa cell, before and after they are exposed to calcium ionophore A23187 and silver nanoparticles (AgNPs). We verify that the volume and the cross sectional line profile of the RBL-2H3 cell were changed significantly when it was exposed to A23187. When 50 μg/mL of AgNP is used instead of A23187, the measurements of cell volume and cross sectional profiles indicate that RBL-2H3 cells also follow degranulation processes. Degranulation processes for these cells are verified by monitoring the increase of intracellular calcium ([Ca2+]i) and histamine with fluorescent methods.

  1. Scanning electron microscopy of the endometrium during the secretory phase.

    PubMed Central

    Motta, P M; Andrews, P M

    1976-01-01

    Scanning electron microscopy was used to study the surface morphology of the rabbit endometrium during the secretory phase of the oestrous cycle. The free surfaces of ciliated and of inactive active secretory cells are described. Changes in secretory cell surface morphology resulting from accumulation and secretion of material involve the apparent retraction of microvilli and the formation of one or more bulbous protrusions of the cell's apical surface. These protrusions may be relatively smooth surfaced or exhibit long slender micro-extensions. The protrusions grow in size and are eventually pinched off. Loss of the bulbous protrusions often leaves behind crater-like invaginations of the cell's surface. Secretory cells adjacent to the endometrial glands are the first to exhibit signs of mucin accumulation and secretion. The single cilium of a secretory cell is not apparently affected by the secretory process. Signs of ciliated and secretory cell degeneration, and possible sloughing, are also described. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 PMID:1033932

  2. Analytical electron microscopy in mineralogy; exsolved phases in pyroxenes

    USGS Publications Warehouse

    Nord, G.L.

    1982-01-01

    Analytical scanning transmission electron microscopy has been successfully used to characterize the structure and composition of lamellar exsolution products in pyroxenes. At operating voltages of 100 and 200 keV, microanalytical techniques of x-ray energy analysis, convergent-beam electron diffraction, and lattice imaging have been used to chemically and structurally characterize exsolution lamellae only a few unit cells wide. Quantitative X-ray energy analysis using ratios of peak intensities has been adopted for the U.S. Geological Survey AEM in order to study the compositions of exsolved phases and changes in compositional profiles as a function of time and temperature. The quantitative analysis procedure involves 1) removal of instrument-induced background, 2) reduction of contamination, and 3) measurement of correction factors obtained from a wide range of standard compositions. The peak-ratio technique requires that the specimen thickness at the point of analysis be thin enough to make absorption corrections unnecessary (i.e., to satisfy the "thin-foil criteria"). In pyroxenes, the calculated "maximum thicknesses" range from 130 to 1400 nm for the ratios Mg/Si, Fe/Si, and Ca/Si; these "maximum thicknesses" have been contoured in pyroxene composition space as a guide during analysis. Analytical spatial resolutions of 50-100 nm have been achieved in AEM at 200 keV from the composition-profile studies, and analytical reproducibility in AEM from homogeneous pyroxene standards is ?? 1.5 mol% endmember. ?? 1982.

  3. Method and apparatus for differential spectroscopic atomic-imaging using scanning tunneling microscopy

    DOEpatents

    Kazmerski, Lawrence L.

    1990-01-01

    A Method and apparatus for differential spectroscopic atomic-imaging is disclosed for spatial resolution and imaging for display not only individual atoms on a sample surface, but also bonding and the specific atomic species in such bond. The apparatus includes a scanning tunneling microscope (STM) that is modified to include photon biasing, preferably a tuneable laser, modulating electronic surface biasing for the sample, and temperature biasing, preferably a vibration-free refrigerated sample mounting stage. Computer control and data processing and visual display components are also included. The method includes modulating the electronic bias voltage with and without selected photon wavelengths and frequency biasing under a stabilizing (usually cold) bias temperature to detect bonding and specific atomic species in the bonds as the STM rasters the sample. This data is processed along with atomic spatial topography data obtained from the STM raster scan to create a real-time visual image of the atoms on the sample surface.

  4. Spectroscopic studies of gas-phase molecular clusters

    NASA Astrophysics Data System (ADS)

    Wong, Chi-Kin

    Spectroscopic investigations of hydrogen-bonding and van der Waals' interactions in molecular clusters were studied by the techniques of infrared predissociation and resonance-enhanced multiphoton ionization spectroscopies (REMPI). Ab initio calculations were applied in conjunction for data interpretation. The infrared predissociation spectroscopy of CN-·(H 2O)n (n = 2--6) clusters was reported in the region of 2950--3850 cm-1. The hydrogen bondings for the C-site and N-site binding, and among the water molecules were identified for n = 2 to 4. A spectral transition was observed for n = 5 and 6, implying that the anion was surface-bound onto the water aggregates in larger clusters. The infrared predissociation spectroscopy of Br-·(NH 3) and I-·(NH3) n (n = 1--3) clusters was reported in the region of 3050--3450 cm-1. For the Br -·(NH3) complex, a dominating ionic NH stretch appeared at 3175 cm-1, and the weaker free NH stretch appeared at 3348 cm-1. The observed spectrum was consistent to the structure in which there was one nearly linear hydrogen bond between Br- and the NH3 moiety. For the I- ·(NH3) complex, five distinct IR absorption bands were observed in the spectrum. The spectrum was not consistent with basic frequency patterns of three geometries considered in the ab initio calculations---complex with one, two and three hydrogen bondings between I- and the NH3 moiety. Substantial inhomogenous broadening were displayed in the spectra for I- ·(NH3)n (n = 2--3), suggesting the presence of multiple isomers. The REMPI spectroscopy of the bound 4p 2pi 1/2 and 2pi3/2 states, and the dissociative 3d 2Sigma+1/2 state in the Al·Ar complex was reported. The dissociative spectrum at Al+ channel suggested the coupling of the 4p 2pi 1/2,3/2 states to the repulsive 3d 2Sigma+1/2 state. The spin-electronic coupling was further manifested in the dissociative Al+ spectrum of the 3d 2Sigma+1/2 state. Using the potential energy curves obtained from ab initio

  5. Reconstruction of explicit structural properties at the nanoscale via spectroscopic microscopy.

    PubMed

    Cherkezyan, Lusik; Zhang, Di; Subramanian, Hariharan; Taflove, Allen; Backman, Vadim

    2016-02-01

    The spectrum registered by a reflected-light bright-field spectroscopic microscope (SM) can quantify the microscopically indiscernible, deeply subdiffractional length scales within samples such as biological cells and tissues. Nevertheless, quantification of biological specimens via any optical measures most often reveals ambiguous information about the specific structural properties within the studied samples. Thus, optical quantification remains nonintuitive to users from the diverse fields of technique application. In this work, we demonstrate that the SM signal can be analyzed to reconstruct explicit physical measures of internal structure within label-free, weakly scattering samples: characteristic length scale and the amplitude of spatial refractive-index (RI) fluctuations. We present and validate the reconstruction algorithm via finite-difference time-domain solutions of Maxwell's equations on an example of exponential spatial correlation of RI. We apply the validated algorithm to experimentally measure structural properties within isolated cells from two genetic variants of HT29 colon cancer cell line as well as within a prostate tissue biopsy section. The presented methodology can lead to the development of novel biophotonics techniques that create two-dimensional maps of explicit structural properties within biomaterials: the characteristic size of macromolecular complexes and the variance of local mass density. PMID:26886803

  6. Reconstruction of explicit structural properties at the nanoscale via spectroscopic microscopy

    NASA Astrophysics Data System (ADS)

    Cherkezyan, Lusik; Zhang, Di; Subramanian, Hariharan; Taflove, Allen; Backman, Vadim

    2016-02-01

    The spectrum registered by a reflected-light bright-field spectroscopic microscope (SM) can quantify the microscopically indiscernible, deeply subdiffractional length scales within samples such as biological cells and tissues. Nevertheless, quantification of biological specimens via any optical measures most often reveals ambiguous information about the specific structural properties within the studied samples. Thus, optical quantification remains nonintuitive to users from the diverse fields of technique application. In this work, we demonstrate that the SM signal can be analyzed to reconstruct explicit physical measures of internal structure within label-free, weakly scattering samples: characteristic length scale and the amplitude of spatial refractive-index (RI) fluctuations. We present and validate the reconstruction algorithm via finite-difference time-domain solutions of Maxwell's equations on an example of exponential spatial correlation of RI. We apply the validated algorithm to experimentally measure structural properties within isolated cells from two genetic variants of HT29 colon cancer cell line as well as within a prostate tissue biopsy section. The presented methodology can lead to the development of novel biophotonics techniques that create two-dimensional maps of explicit structural properties within biomaterials: the characteristic size of macromolecular complexes and the variance of local mass density.

  7. Principal Component Analysis of Spectroscopic Imaging Data in Scanning Probe Microscopy

    SciTech Connect

    Jesse, Stephen; Kalinin, Sergei V

    2009-01-01

    The approach for data analysis in band excitation family of scanning probe microscopies based on principal component analysis (PCA) is explored. PCA utilizes the similarity between spectra within the image to select the relevant response components. For small signal variations within the image, the PCA components coincide with the results of deconvolution using simple harmonic oscillator model. For strong signal variations, the PCA allows effective approach to rapidly process, de-noise and compress the data. The extension of PCA for correlation function analysis is demonstrated. The prospects of PCA as a universal tool for data analysis and representation in multidimensional SPMs are discussed.

  8. Volta potential phase plate for in-focus phase contrast transmission electron microscopy.

    PubMed

    Danev, Radostin; Buijsse, Bart; Khoshouei, Maryam; Plitzko, Jürgen M; Baumeister, Wolfgang

    2014-11-01

    We describe a phase plate for transmission electron microscopy taking advantage of a hitherto-unknown phenomenon, namely a beam-induced Volta potential on the surface of a continuous thin film. The Volta potential is negative, indicating that it is not caused by beam-induced electrostatic charging. The film must be heated to ∼ 200 °C to prevent contamination and enable the Volta potential effect. The phase shift is created "on the fly" by the central diffraction beam eliminating the need for precise phase plate alignment. Images acquired with the Volta phase plate (VPP) show higher contrast and unlike Zernike phase plate images no fringing artifacts. Following installation into the microscope, the VPP has an initial settling time of about a week after which the phase shift behavior becomes stable. The VPP has a long service life and has been used for more than 6 mo without noticeable degradation in performance. The mechanism underlying the VPP is the same as the one responsible for the degradation over time of the performance of thin-film Zernike phase plates, but in the VPP it is used in a constructive way. The exact physics and/or chemistry behind the process causing the Volta potential are not fully understood, but experimental evidence suggests that radiation-induced surface modification combined with a chemical equilibrium between the surface and residual gases in the vacuum play an important role. PMID:25331897

  9. Volta potential phase plate for in-focus phase contrast transmission electron microscopy

    PubMed Central

    Danev, Radostin; Buijsse, Bart; Khoshouei, Maryam; Plitzko, Jürgen M.; Baumeister, Wolfgang

    2014-01-01

    We describe a phase plate for transmission electron microscopy taking advantage of a hitherto-unknown phenomenon, namely a beam-induced Volta potential on the surface of a continuous thin film. The Volta potential is negative, indicating that it is not caused by beam-induced electrostatic charging. The film must be heated to ∼200 °C to prevent contamination and enable the Volta potential effect. The phase shift is created “on the fly” by the central diffraction beam eliminating the need for precise phase plate alignment. Images acquired with the Volta phase plate (VPP) show higher contrast and unlike Zernike phase plate images no fringing artifacts. Following installation into the microscope, the VPP has an initial settling time of about a week after which the phase shift behavior becomes stable. The VPP has a long service life and has been used for more than 6 mo without noticeable degradation in performance. The mechanism underlying the VPP is the same as the one responsible for the degradation over time of the performance of thin-film Zernike phase plates, but in the VPP it is used in a constructive way. The exact physics and/or chemistry behind the process causing the Volta potential are not fully understood, but experimental evidence suggests that radiation-induced surface modification combined with a chemical equilibrium between the surface and residual gases in the vacuum play an important role. PMID:25331897

  10. Detection of secondary phases in duplex stainless steel by magnetic force microscopy and scanning Kelvin probe force microscopy

    SciTech Connect

    Ramírez-Salgado, J.; Domínguez-Aguilar, M.A.; Castro-Domínguez, B.; Hernández-Hernández, P.; Newman, R.C.

    2013-12-15

    The secondary phase transformations in a commercial super duplex stainless steel were investigated by micro-chemical analyses and high resolution scanning probe microscopy. Energy dispersive X-ray and electron probe detected ferrite and austenite as well as secondary phases in unetched aged duplex stainless steel type 25Cr-7Ni-3Mo. Volta potential indicated that nitride and sigma appeared more active than ferrite, while secondary austenite and austenite presented a nobler potential. Reversal order in nobility is thought to be attributable to the potential ranking provided by oxide nature diversity as a result of secondary phase surface compositions on steel. After eutectoid transformation, secondary austenite was detected by electron probe microanalysis, whereas atomic force microscopy distinguished this phase from former austenite by image contrast. Magnetic force microscopy revealed a “ghosted” effect on the latter microstructure probably derived from metal memory reminiscence of mechanical polishing at passivity and long range magnetic forces of ferrite phase. - Highlights: • Nobility detection of secondary phases by SKPFM in DSS particles is not a straightforward procedure. • As Volta potential and contrast are not always consistent SKPFM surface oxides is thought played an important role in detection. • AFM distinguished secondary austenite from former austenite by image contrast though SEM required EPMA.

  11. GAS PHASE MOLECULAR DYNAMICS: HIGH-RESOLUTION SPECTROSCOPIC PROBES OF CHEMICAL DYNAMICS.

    SciTech Connect

    HALL, G.E.

    2006-05-30

    This research is carried out as part of the Gas Phase Molecular Dynamics group program in the Chemistry Department at Brookhaven National Laboratory. High-resolution spectroscopic tools are developed and applied to problems in chemical dynamics. Recent topics have included the state-resolved studies of collision-induced electronic energy transfer, dynamics of barrierless unimolecular reactions, and the kinetics and spectroscopy of transient species.

  12. Spectroscopic microscopy analysis of the interior pH of individual phospholipid vesicles.

    PubMed

    Heider, Emily C; Myers, Grant A; Harris, Joel M

    2011-11-01

    The use of phospholipid vesicles as reaction containers, as vehicles for pharmaceutical drug delivery, and as model systems for cells has prompted the development of new methods for analyzing the structure of vesicles and their contents. The pH of the interior of vesicles is of particular interest when analytes are encapsulated and concentrated with the use of a pH gradient. While the interior pH is generally measured for large populations of vesicles, we report the measurement of the interior pH of individual vesicles as their buffer contents are titrated by transfer of N-methylbutylamine (NMBA) into the vesicle by a pH gradient. The initially acidic buffer within the vesicles is titrated along with a small concentration of an encapsulated pH sensitive dye, 5,6-carboxy SNARF-1-dextran. Images of the indicator fluorescence from each vesicle and its dispersed fluorescence spectrum are recorded using epi-illumination spectral fluorescence microscopy. From a fit of the spectra to the respective acid and base forms of the fluorescent indicator, the interior pH of individual vesicles as a function of the concentration of the NMBA titrant in the external solution could be determined.

  13. Development of in-situ full-field spectroscopic imaging analysis and application on Li-ion battery using transmission x-ray microscopy

    NASA Astrophysics Data System (ADS)

    Chen-Wiegart, Yu-chen K.; Wang, Jiajun; Wang, Jun

    2013-09-01

    This paper presents the advance in spectroscopic imaging technique and analysis method from the newly developed transmission x-ray microscopy (TXM) at the beamline X8C of National Synchrotron Light Source. Through leastsquares linear combination fitting we developed on the in situ spectroscopic images, a time-dependent and spatially resolved chemical composition mapping can be obtained and quantitatively analyzed undergone chemical/electrochemical reactions. A correlation of morphological evolution, chemical state distribution changes and reaction conditions can be revealed. We successfully applied this method to study the electrochemical evolution of CuO, an anode material of Li-ion battery, during the lithiation-delitiation cycling.

  14. A view of the implanted SiC damage by Rutherford backscattering spectroscopy, spectroscopic ellipsometry, and transmission electron microscopy

    SciTech Connect

    Battistig, G.; Khanh, N. Q.; Petrik, P.; Lohner, T.; Dobos, L.; Pecz, B.; Garcia Lopez, J.; Morilla, Y.

    2006-11-01

    4H-SiC single crystalline substrates were implanted at room temperature with 150 keV Al{sup +} ions using fluences of 4x10{sup 14}, 1x10{sup 15}, and 2x10{sup 15} cm{sup -2} with current density of 2.5 {mu}A cm{sup -2}. The samples were subsequently annealed at 1100 deg. C in N{sub 2} for 1 h in order to analyze their structural recovery. The disorder induced in both sublattices by the Al{sup +} ions was studied by backscattering spectrometry in channeling geometry with a 3.5 MeV He{sup 2+} beam. The results were compared with the optical properties of the samples measured by spectroscopic ellipsometry. In a previous work, we concluded that during the postimplantation annealing of a highly damaged SiC crystalline material the short distance order can be recovered, while the long distance disorder remains. We also presented the possibility to have grains of different polytypes oriented faraway from the original direction. Now, this alternative is confirmed by the cross-sectional transmission and high resolution electron microscopy studies, carried out to obtain information about the crystal structure.

  15. Intensity and phase fields behind phase-shifting masks studied with high-resolution interference microscopy

    NASA Astrophysics Data System (ADS)

    Puthankovilakam, Krishnaparvathy; Scharf, Toralf; Kim, Myun Sik; Naqavi, Ali; Herzig, Hans Peter; Weichelt, Tina; Zeitner, Uwe; Vogler, Uwe; Voelkel, Reinhard

    2016-04-01

    We try to find out the details of how light fields behind the structures of photomasks develop in order to determine the best conditions and designs for proximity printing. The parameters that we use approach real situations like structure printing at proximity gaps of 20 to 50 μm and structure sizes down to 2 μm. This is the first time that an experimental analysis of light propagation through a mask is presented in detail, which includes information on intensity and phase. We use high-resolution interference microscopy (HRIM) for the measurement. HRIM is a Mach-Zehnder interferometer, which is capable of recording three-dimensional distributions of intensity and phase with diffraction-limited resolution. Our characterization technique allows plotting the evolution of the desired light field, usually called the aerial image, and therefore gives access to the printable structure until the desired proximity gap. Here, we discuss in detail the evolution of intensity and phase fields of elbow or corner structures at different positions behind a phase mask and interpret the main parameters. Of particular interest are tolerances against proximity gap variation and the theoretical explanation of the resolution in printed structures.

  16. X-ray Phase Imaging Microscopy using a Fresnel Zone Plate and a Transmission Grating

    SciTech Connect

    Yashiro, Wataru; Momose, Atsushi; Takeuchi, Akihisa; Suzuki, Yoshio

    2010-06-23

    We report on a hard X-ray phase imaging microscopy (a phase-difference microscopy) that consists of an objective and a transmission grating. The simple optical system provides a quantitative phase image, and does not need a wave field mostly coherent on the objective. Our method has a spatial resolution almost same as that of the absorption contrast microscope image obtained by removing the grating. We demonstrate how our approach provides a phase image from experimentally obtained images. Our approach is attractive for easily appending a quantitative phase-sensitive mode to normal X-ray microscopes, and has potentially broad applications in biology and material sciences.

  17. Dynamic phase imaging of host cells attacked by Vibrio vulnificus using quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Lee, Seungrag; Yang, Wenzhong; Lee, Ji Yong; Cha, Mi Hye; Kim, Young Ran; Kim, Dug Young

    2010-02-01

    We present the real time quantitative analysis of Vibrio vulnificus-infected host cells using high stability quantitative phase microscopy (HSQPM). It provides the ability to retrieve the phase or optical path length distribution over the cell from a single interferogram image, which has been measured with nanometer path length sensitivity for long periods of time. We have applied HSQPM to study dynamic cell morphologic changes and to quantify noninvasively cell volumes of rat basophilic leukemia RBL-2H3 cells infected with pathogenic bacteria V. vulnificus strains, wild type (MO6-24/O) and RTX toxin mutant (CMM770). During the process of V. vulnificus wild type infection to RBL-2H3 cells, the dynamic changes of quantitative phase images, cell volumes and areas were observed in real time using HSQPM. In contrast, the dramatic changes were not detected in RBL-2H3 cells infected with RTX toxin mutant. The results showed the good correlation between HSQPM analysis and biochemical assays such as lactate dehydrogenase (LDH) assay and β-hexosaminidase release assay. We suggest that HSQPM is useful real time quantitative method to study the dynamic process of host cells infected with pathogen in a noninvasive manner.

  18. LDRD final report : raman spectroscopic measurements to monitor the HMX beta-delta phase transition.

    SciTech Connect

    Renlund, Anita Mariana; Tappan, Alexander Smith; Miller, Jill C.

    2000-11-01

    The HMX {beta}-{delta} solid-solid phase transition, which occurs as HMX is heated near 170 C, is linked to increased reactivity and sensitivity to initiation. Thermally damaged energetic materials (EMs) containing HMX therefore may present a safety concern. Information about the phase transition is vital to predictive safety models for HMX and HMX-containing EMs. We report work on monitoring the phase transition with real-time Raman spectroscopy aimed towards obtaining a better understanding of physical properties of HMX through the phase transition. HMX samples were confined in a cell of minimal free volume in a displacement-controlled or load-controlled arrangement. The cell was heated and then cooled at controlled rates while real-time Raman spectroscopic measurements were performed. Raman spectroscopy provides a clear distinction between the phases of HMX because the vibrational transitions of the molecule change with conformational changes associated with the phase transition. Temperature of phase transition versus load data are presented for both the heating and cooling cycles in the load-controlled apparatus, and general trends are discussed. A weak dependence of the temperature of phase transition on load was discovered during the heating cycle, with higher loads causing the phase transition to occur at a higher temperature. This was especially true in the temperature of completion of phase transition data as opposed to the temperature of onset of phase transition data. A stronger dependence on load was observed in the cooling cycle, with higher loads causing the reverse phase transitions to occur at a higher cooling temperature. Also, higher loads tended to cause the phase transition to occur over a longer period of time in the heating cycle and over a shorter period of time in the cooling cycle. All three of the pure HMX phases ({alpha}, {beta} and {delta}) were detected on cooling of the heated samples, either in pure form or as a mixture.

  19. 4D phase-space multiplexing for fluorescent microscopy

    NASA Astrophysics Data System (ADS)

    Liu, Hsiou-Yuan; Zhong, Jingshan; Waller, Laura

    2016-03-01

    Phase-space measurements enable characterization of second-order spatial coherence properties and can be used for digital aberration removal or 3D position reconstruction. Previous methods use a scanning aperture to measure the phase space spectrogram, which is slow and light inefficient, while also attenuating information about higher-order correlations. We demonstrate a significant improvement of speed and light throughput by incorporating multiplexing techniques into our phase-space imaging system. The scheme implements 2D coded aperture patterning in the Fourier (pupil) plane of a microscope using a Spatial Light Modulator (SLM), while capturing multiple intensity images in real space. We compare various multiplexing schemes to scanning apertures and show that our phase-space reconstructions are accurate for experimental data with biological samples containing many 3D fluorophores.

  20. Artifact characterization and reduction in scanning X-ray Zernike phase contrast microscopy.

    PubMed

    Vartiainen, Ismo; Holzner, Christian; Mohacsi, Istvan; Karvinen, Petri; Diaz, Ana; Pigino, Gaia; David, Christian

    2015-05-18

    Zernike phase contrast microscopy is a well-established method for imaging specimens with low absorption contrast. It has been successfully implemented in full-field microscopy using visible light and X-rays. In microscopy Cowley's reciprocity principle connects scanning and full-field imaging. Even though the reciprocity in Zernike phase contrast has been discussed by several authors over the past thirty years, only recently it was experimentally verified using scanning X-ray microscopy. In this paper, we investigate the image and contrast formation in scanning Zernike phase contrast microscopy with a particular and detailed focus on the origin of imaging artifacts that are typically associated with Zernike phase contrast. We demonstrate experimentally with X-rays the effect of the phase mask design on the contrast and halo artifacts and present an optimized design of the phase mask with respect to photon efficiency and artifact reduction. Similarly, due to the principle of reciprocity the observations and conclusions of this work have direct applicability to Zernike phase contrast in full-field microscopy as well. PMID:26074579

  1. Spectroscopic and Structural Investigations of alpha-beta-, and gamma-AIH3 Phases

    SciTech Connect

    Manciu, F.S.; Graetz, J.; Reza, L.; Durrer, W.G.; Bronson, A.; Lacina, D.

    2010-07-01

    With its reputation as a high-energy density fuel, aluminum hydride (AlH{sub 3}) has received renewed attention as a material that is particularly suitable, not only for hydrogen storage but also for rocket propulsion. While the various phases of AlH{sub 3} have been investigated theoretically, there is a shortage of experimental studies corroborating the theoretical findings. In response to this, we present here an investigation of these compounds based primarily on two research areas in which there is the greatest scarcity of information in the literature, namely Raman and infrared (IR) absorption analysis. To the authors knowledge, this is the first report of experimental far-IR absorption results on these compounds. Two different samples prepared by broadly similar ethereal reactions of AlCl{sub 3} with LiAlH{sub 4} were analyzed. Both Raman and IR absorption measurements indicate that one sample is purely {gamma}-AlH{sub 3} and that the other is a mixture of {alpha}-, {beta}-, and {gamma}-AlH{sub 3} phases. X-ray diffraction confirms the spectroscopic findings, most notably for the {beta}-AlH{sub 3} phase, for which optical spectroscopic data are reported here for the first time.

  2. Simultaneous microscopic measurements of thermal and spectroscopic fields of a phase change material

    NASA Astrophysics Data System (ADS)

    Romano, M.; Ryu, M.; Morikawa, J.; Batsale, J. C.; Pradere, C.

    2016-05-01

    In this paper, simultaneous microscopic measurements of thermal and spectroscopic fields of a paraffin wax n-alkane phase change material are reported. Measurements collected using an original set-up are presented and discussed with emphasis on the ability to perform simultaneous characterization of the system when the proposed imaging process is used. Finally, this work reveals that the infrared wavelength contains two sets of important information. Furthermore, this versatile and flexible technique is well adapted to characterize many systems in which the mass and heat transfers effects are coupled.

  3. Compact diffraction phase microscopy for quantitative visualization of cells in biomedical applications

    NASA Astrophysics Data System (ADS)

    Talaikova, N. A.; Ryabukho, V. P.

    2016-08-01

    We consider a simplified and compact scheme of interference phase microscopy using a diffraction grating and spatial filtering of the diffracted field, i.e., diffraction phase microscopy. The scheme and the parameters of the device with the possibility of using the optical system of a smartphone and its software are analysed. The results of experimental determination of the spatial structure parameters of erythrocytes are presented.

  4. Enlightening intracellular complexity of living cells with quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Martinez Torres, C.; Laperrousaz, B.; Berguiga, L.; Boyer Provera, E.; Elezgaray, J.; Nicolini, F. E.; Maguer-Satta, V.; Arneodo, A.; Argoul, F.

    2016-03-01

    The internal distribution of refractive indices (RIs) of a living cell is much more complex than usually admitted in multi-shell models. The reconstruction of RI maps from single phase images has rarely been achieved for several reasons: (i) we still have very little knowledge of the impact of internal macromolecular complexes on the local RI and (ii) phase changes produced by light propagation through the sample are mixed with diffraction effects by internal cell bodies. We propose the implementation a 2D wavelet-based contour chain detection method to distinguish internal boundaries thanks to their greatest optical path difference gradients. These contour chains correspond to the highest image phase contrast and follow the local RI inhomogeneities linked to the intracellular structural intricacy. Their statistics and spatial distribution are morphological indicators for distinguishing cells of different origins and to follow their transformation in pathologic situations. We use this method to compare non adherent blood cells from primary and laboratory culture origins, in healthy and pathological situations (chronic myelogenous leukaemia). In a second part of this presentation, we concentrate on the temporal dynamics of the phase contour chains and we discuss the spectral decomposition of their dynamics in both health and disease.

  5. 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.

  6. Time Resolved Phase Transitions via Dynamic Transmission Electron Microscopy

    SciTech Connect

    Reed, B W; Armstrong, M R; Blobaum, K J; Browning, N D; Burnham, A K; Campbell, G H; Gee, R; Kim, J S; King, W E; Maiti, A; Piggott, W T; Torralva, B R

    2007-02-22

    The Dynamic Transmission Electron Microscope (DTEM) project is developing an in situ electron microscope with nanometer- and nanosecond-scale resolution for the study of rapid laser-driven processes in materials. We report on the results obtained in a year-long LDRD-supported effort to develop DTEM techniques and results for phase transitions in molecular crystals, reactive multilayer foils, and melting and resolidification of bismuth. We report the first in situ TEM observation of the HMX {beta}-{delta} phase transformation in sub-{micro}m crystals, computational results suggesting the importance of voids and free surfaces in the HMX transformation kinetics, and the first electron diffraction patterns of intermediate states in fast multilayer foil reactions. This project developed techniques which are applicable to many materials systems and will continue to be employed within the larger DTEM effort.

  7. Off-axis digital holographic camera for quantitative phase microscopy.

    PubMed

    Monemhaghdoust, Zahra; Montfort, Frédéric; Emery, Yves; Depeursinge, Christian; Moser, Christophe

    2014-06-01

    We propose and experimentally demonstrate a digital holographic camera which can be attached to the camera port of a conventional microscope for obtaining digital holograms in a self-reference configuration, under short coherence illumination and in a single shot. A thick holographic grating filters the beam containing the sample information in two dimensions through diffraction. The filtered beam creates the reference arm of the interferometer. The spatial filtering method, based on the high angular selectivity of the thick grating, reduces the alignment sensitivity to angular displacements compared with pinhole based Fourier filtering. The addition of a thin holographic grating alters the coherence plane tilt introduced by the thick grating so as to create high-visibility interference over the entire field of view. The acquired full-field off-axis holograms are processed to retrieve the amplitude and phase information of the sample. The system produces phase images of cheek cells qualitatively similar to phase images extracted with a standard commercial DHM.

  8. Spectroscopic Studies of Cyclopentane under Extreme Conditions and Implications for the P-T Phase Diagram

    NASA Astrophysics Data System (ADS)

    Ma, Chunli; Liu, Zhenxian; Cui, Qiliang; Hemley, Russell

    2013-06-01

    Infrared (IR) spectroscopy and Raman scattering combined with diamond anvil cell (DAC) and cryogenic techniques have been employed to investigate cyclopentane up to 4 GPa in the temperature range of 100-350 K and isothermal compression up to 84 GPa at room temperature. Four phases including liquid, plastic phases I and II, and truly crystalline phase III are clearly identified in the P-T range studied based on the changes of the ring breathing mode and CH2 rocking modes. The phase diagram is extended to the pressure and temperature range of 0 - 4.0 GPa and 105 - 350 K. Further compression at room temperature up to 84 GPa, another high-pressure phase (IV) is observed based on the appearance of low frequency peaks related to the lattice vibrational modes in the synchrotron far-IR spectra. The spectroscopic results indicate that cyclopentane persists the orientation ordered crystalline phase up to 84 GPa at room temperature. This work was supported by NSF (DMR-0805056; EAR 06-49658, COMPRES) and DOE/ NNSA (DE-FC03-03N00144, CDAC). NSLS is supported by the DOE/BES (DE-AC02-98CH10886).

  9. Two-step phase-shifting fluorescence incoherent holographic microscopy

    PubMed Central

    Qin, Wan; Yang, Xiaoqi; Li, Yingying; Peng, Xiang; Yao, Hai; Qu, Xinghua; Gao, Bruce Z.

    2014-01-01

    Abstract. Fluorescence holographic microscope (FINCHSCOPE) is a motionless fluorescence holographic imaging technique based on Fresnel incoherent correlation holography (FINCH) that shows promise in reconstructing three-dimensional fluorescence images of biological specimens with three holograms. We report a developing two-step phase-shifting method that reduces the required number of holograms from three to two. Using this method, we resolved microscopic fluorescent beads that were three-dimensionally distributed at different depths with two interferograms captured by a CCD camera. The method enables the FINCHSCOPE to work in conjunction with the frame-straddling technique and significantly enhance imaging speed. PMID:24972355

  10. Understanding the Phase Contrast Optics to Restore Artifact-free Microscopy Images for Segmentation

    PubMed Central

    Yin, Zhaozheng; Kanade, Takeo; Chen, Mei

    2012-01-01

    Phase contrast, a noninvasive microscopy imaging technique, is widely used to capture time-lapse images to monitor the behavior of transparent cells without staining or altering them. Due to the optical principle, phase contrast microscopy images contain artifacts such as the halo and shade-off that hinder image segmentation, a critical step in automated microscopy image analysis. Rather than treating phase contrast microscopy images as general natural images and applying generic image processing techniques on them, we propose to study the optical properties of the phase contrast microscope to model its image formation process. The phase contrast imaging system can be approximated by a linear imaging model. Based on this model and input image properties, we formulate a regularized quadratic cost function to restore artifact-free phase contrast images that directly correspond to the specimen's optical path length. With artifacts removed, high quality segmentation can be achieved by simply thresholding the restored images. The imaging model and restoration method are quantitatively evaluated on microscopy image sequences with thousands of cells captured over several days. We also demonstrate that accurate restoration lays the foundation for high performance in cell detection and tracking. PMID:22386070

  11. Understanding the phase contrast optics to restore artifact-free microscopy images for segmentation.

    PubMed

    Yin, Zhaozheng; Kanade, Takeo; Chen, Mei

    2012-07-01

    Phase contrast, a noninvasive microscopy imaging technique, is widely used to capture time-lapse images to monitor the behavior of transparent cells without staining or altering them. Due to the optical principle, phase contrast microscopy images contain artifacts such as the halo and shade-off that hinder image segmentation, a critical step in automated microscopy image analysis. Rather than treating phase contrast microscopy images as general natural images and applying generic image processing techniques on them, we propose to study the optical properties of the phase contrast microscope to model its image formation process. The phase contrast imaging system can be approximated by a linear imaging model. Based on this model and input image properties, we formulate a regularized quadratic cost function to restore artifact-free phase contrast images that directly correspond to the specimen's optical path length. With artifacts removed, high quality segmentation can be achieved by simply thresholding the restored images. The imaging model and restoration method are quantitatively evaluated on microscopy image sequences with thousands of cells captured over several days. We also demonstrate that accurate restoration lays the foundation for high performance in cell detection and tracking. PMID:22386070

  12. The lamina splendens of articular cartilage is an artefact of phase contrast microscopy.

    PubMed

    Aspden, R M; Hukins, D W

    1979-11-30

    The so-called lamina splendens of articular cartilage is shown to be a characteristic of phase contrast microscopy; this technique provides no evidence for an anatomically distinct surface layer. Fresnel diffraction occurs at edges separating regions of different refractive indices. These diffraction effects, when viewed under phase contrast, lead to the appearance of a bright line along the edge. PMID:42065

  13. Controlling stimulated coherent spectroscopy and microscopy by a position-dependent phase

    NASA Astrophysics Data System (ADS)

    Chung, Chao-Yu; Hsu, Julie; Mukamel, Shaul; Potma, Eric O.

    2013-03-01

    We study the role of geometry-dependent phase shifts of the optical electric field in stimulated coherent spectroscopy, a special class of heterodyne optical spectroscopy techniques. We generalize the theoretical description of stimulated spectroscopy to include spatial phase effects, and study the measured material response for several representative excitation and detection configurations. Using stimulated Raman scattering microscopy as an example, we show that different components of the material response are measured by varying the position of the object in focus. We discuss the implications of the position-dependent phase in stimulated coherent microscopy and point out a detection configuration in which its effects are minimized.

  14. Quantitative interferometric microscopy with improved full-field phase aberration compensation

    NASA Astrophysics Data System (ADS)

    Xue, Liang; Wang, Shouyu; Yan, Keding; Sun, Nan; Li, Zhenhua; Liu, Fei

    2014-11-01

    Single-shot quantitative interferometric microscopy (QIM) needs a high-accuracy and rapid phase retrieval algorithm. Retrieved phase distributions are often influenced by phase aberration background caused by both imaging system and phase retrieval algorithms. Here, we propose an improved phase aberration compensation (PAC) approach in order to eliminate the phase aberrations inherent in the data. With this method, sample-free parts are identified and used to calculate the background phase, reducing phase errors induced in samples and providing high-quality phase images. We now demonstrate that QIM based on this PAC approach realizes high-quality phase imaging from a single interferogram. This is of great potential for a real-time speedy diagnosis.

  15. Phase reconstruction in annular bright-field scanning transmission electron microscopy.

    PubMed

    Ishida, Takafumi; Kawasaki, Tadahiro; Tanji, Takayoshi; Kodama, Tetsuji; Matsutani, Takaomi; Ogai, Keiko; Ikuta, Takashi

    2015-04-01

    A novel technique for reconstructing the phase shifts of electron waves was applied to Cs-corrected scanning transmission electron microscopy (STEM). To realize this method, a new STEM system equipped with an annular aperture, annularly arrayed detectors and an arrayed image processor has been developed and evaluated in experiments. We show a reconstructed phase image of graphite particles and demonstrate that this new method works effectively for high-resolution phase imaging. PMID:25387907

  16. Phase reconstruction in annular bright-field scanning transmission electron microscopy.

    PubMed

    Ishida, Takafumi; Kawasaki, Tadahiro; Tanji, Takayoshi; Kodama, Tetsuji; Matsutani, Takaomi; Ogai, Keiko; Ikuta, Takashi

    2015-04-01

    A novel technique for reconstructing the phase shifts of electron waves was applied to Cs-corrected scanning transmission electron microscopy (STEM). To realize this method, a new STEM system equipped with an annular aperture, annularly arrayed detectors and an arrayed image processor has been developed and evaluated in experiments. We show a reconstructed phase image of graphite particles and demonstrate that this new method works effectively for high-resolution phase imaging.

  17. Whole-cell-analysis of live cardiomyocytes using wide-field interferometric phase microscopy

    PubMed Central

    Shaked, Natan T.; Satterwhite, Lisa L.; Bursac, Nenad; Wax, Adam

    2010-01-01

    We apply wide-field interferometric microscopy techniques to acquire quantitative phase profiles of ventricular cardiomyocytes in vitro during their rapid contraction with high temporal and spatial resolution. The whole-cell phase profiles are analyzed to yield valuable quantitative parameters characterizing the cell dynamics, without the need to decouple thickness from refractive index differences. Our experimental results verify that these new parameters can be used with wide field interferometric microscopy to discriminate the modulation of cardiomyocyte contraction dynamics due to temperature variation. To demonstrate the necessity of the proposed numerical analysis for cardiomyocytes, we present confocal dual-fluorescence-channel microscopy results which show that the rapid motion of the cell organelles during contraction preclude assuming a homogenous refractive index over the entire cell contents, or using multiple-exposure or scanning microscopy. PMID:21258502

  18. Spectroscopic Identification of p-CHLORO-α-METHYLBENZYL Radical in the Gas Phase

    NASA Astrophysics Data System (ADS)

    Lee, Seung Woon; Lee, Gi Woo; Lee, Sang Kuk

    2009-06-01

    We report the first spectroscopic identification of the p-fluoro-α-methylbenzyl radical in the gas phase. Precursor p-fluoro-ethylbenzene seeded in a large amount of inert carrier gas helium was electrically discharged to produce the benzyl-type radicals in a corona excited supersonic expansion using a pinhole-type glass nozzle, from which the vibronic emission spectrum was recorded in the visible region using a long path monochromator. From an analysis of the spectrum observed, we found the formation of p-fluoro-α-methylbenzyl radical as well as p-fluorobenzyl radical in the jet from the precursor. After eliminating the bands belonging to p-fluorobenzyl radical using the known data, we identified spectroscopically the formation of the p-fluoro-α-methylbenzyl radical, in which the energy of the D_1 → D_0 electronic transition and a few vibrational mode frequencies in the ground electronic state were determined by comparison with those from an ab initio calculation and with those from the known data of the precursor. S. K. Lee and D. Y. Baek Chem. Phys. Lett. 301(3-4), 407-412 (1999).

  19. Halo suppression in full-field x-ray Zernike phase contrast microscopy.

    PubMed

    Vartiainen, Ismo; Mokso, Rajmund; Stampanoni, Marco; David, Christian

    2014-03-15

    Visible light Zernike phase contrast (ZPC) microscopy is a well established method for imaging weakly absorbing samples. The method is also used with hard x-ray photon energies for structural evaluation of material science and biological applications. However, the method suffers from artifacts that are inherent for the Zernike image formation. In this Letter, we investigate their origin and experimentally show how to suppress them in x-ray full-field ZPC microscopy based on diffractive x-ray optics.

  20. Etch depth mapping of phase binary computer-generated holograms by means of specular spectroscopic scatterometry

    NASA Astrophysics Data System (ADS)

    Korolkov, Victor P.; Konchenko, Alexander S.; Cherkashin, Vadim V.; Mironnikov, Nikolay G.; Poleshchuk, Alexander G.

    2013-09-01

    Detailed analysis of etch depth map for phase binary computer-generated holograms intended for testing aspheric optics is a very important task. In particular, diffractive Fizeau null lenses need to be carefully tested for uniformity of etch depth. We offer a simplified version of the specular spectroscopic scatterometry method. It is based on the spectral properties of binary phase multi-order gratings. An intensity of zero order is a periodical function of illumination light wave number. The grating grooves depth can be calculated as it is inversely proportional to the period. Measurement in reflection allows one to increase the phase depth of the grooves by a factor of 2 and measure more precisely shallow phase gratings. Measurement uncertainty is mainly defined by the following parameters: shifts of the spectrum maximums that occur due to the tilted grooves sidewalls, uncertainty of light incidence angle measurement, and spectrophotometer wavelength error. It is theoretically and experimentally shown that the method we describe can ensure 1% error. However, fiber spectrometers are more convenient for scanning measurements of large area computer-generated holograms. Our experimental system for characterization of binary computer-generated holograms was developed using a fiber spectrometer.

  1. Multimodal imaging of human cerebellum - merging X-ray phase microtomography, magnetic resonance microscopy and histology

    NASA Astrophysics Data System (ADS)

    Schulz, Georg; Waschkies, Conny; Pfeiffer, Franz; Zanette, Irene; Weitkamp, Timm; David, Christian; Müller, Bert

    2012-11-01

    Imaging modalities including magnetic resonance imaging and X-ray computed tomography are established methods in daily clinical diagnosis of human brain. Clinical equipment does not provide sufficient spatial resolution to obtain morphological information on the cellular level, essential for applying minimally or non-invasive surgical interventions. Therefore, generic data with lateral sub-micrometer resolution have been generated from histological slices post mortem. Sub-cellular spatial resolution, lost in the third dimension as a result of sectioning, is obtained using magnetic resonance microscopy and micro computed tomography. We demonstrate that for human cerebellum grating-based X-ray phase tomography shows complementary contrast to magnetic resonance microscopy and histology. In this study, the contrast-to-noise values of magnetic resonance microscopy and phase tomography were comparable whereas the spatial resolution in phase tomography is an order of magnitude better. The registered data with their complementary information permit the distinct segmentation of tissues within the human cerebellum.

  2. Double-twist cylinders in liquid crystalline cholesteric blue phases observed by transmission electron microscopy

    PubMed Central

    Tanaka, Shu; Yoshida, Hiroyuki; Kawata, Yuto; Kuwahara, Ryusuke; Nishi, Ryuji; Ozaki, Masanori

    2015-01-01

    Cholesteric blue phases are liquid crystalline phases in which the constituent rod-like molecules spontaneously form three-dimensional, helical structures. Despite theoretical predictions that they are composed of cylindrical substructures within which the liquid crystal molecules are doubly twisted, real space observation of the arrangement of such structures had not been performed. Through transmission electron microscopy of photopolymerized blue phases with controlled lattice plane orientations, we report real space observation and comparison of the lattice structures of blue phases I and II. The two systems show distinctly different contrasts, reflecting the theoretically predicted, body centred and simple cubic arrangement of the double-twist cylinders. Transmission electron microscopy also reveals different tendencies of the two blue phases to align on unidirectionally rubbed surfaces. We thus show that TEM observation of alignment-controlled, photopolymerized liquid crystals can be a powerful tool to investigate complex liquid crystalline order. PMID:26530779

  3. Double-twist cylinders in liquid crystalline cholesteric blue phases observed by transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Tanaka, Shu; Yoshida, Hiroyuki; Kawata, Yuto; Kuwahara, Ryusuke; Nishi, Ryuji; Ozaki, Masanori

    2015-11-01

    Cholesteric blue phases are liquid crystalline phases in which the constituent rod-like molecules spontaneously form three-dimensional, helical structures. Despite theoretical predictions that they are composed of cylindrical substructures within which the liquid crystal molecules are doubly twisted, real space observation of the arrangement of such structures had not been performed. Through transmission electron microscopy of photopolymerized blue phases with controlled lattice plane orientations, we report real space observation and comparison of the lattice structures of blue phases I and II. The two systems show distinctly different contrasts, reflecting the theoretically predicted, body centred and simple cubic arrangement of the double-twist cylinders. Transmission electron microscopy also reveals different tendencies of the two blue phases to align on unidirectionally rubbed surfaces. We thus show that TEM observation of alignment-controlled, photopolymerized liquid crystals can be a powerful tool to investigate complex liquid crystalline order.

  4. Spectroscopic-ellipsometric study of native oxide removal by liquid phase HF process

    NASA Astrophysics Data System (ADS)

    Kurhekar, Anil Sudhakar; Apte, Prakash R.

    2013-02-01

    Ex situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effect of liquid-phase hydrofluoric acid (HF) cleaning on Si<100> surfaces for microelectromechanical systems application. The hydrogen terminated (H-terminated) Si surface was realized as an equivalent dielectric layer, and SE measurements are performed. The SE analyses indicate that after a 20-s 100:5 HF dip with rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed and analyzed by the ex-situ SE. Evidence for desorption of the H-terminated Si surface layer is studied using Fourier transform infrared spectroscopy and ellipsometry, and discussed. This piece of work explains the usage of an ex situ, non-destructive technique capable of showing state of passivation, the H-termination of Si<100> surfaces.

  5. Spectroscopic-ellipsometric study of native oxide removal by liquid phase HF process

    PubMed Central

    Kurhekar, Anil Sudhakar; Apte, Prakash R

    2014-01-01

    Ex situ spectroscopic ellipsometry (SE) measurements have been employed to investigate the effect of liquid-phase hydrofluoric acid (HF) cleaning on Si<100> surfaces for microelectromechanical systems application. The hydrogen terminated (H-terminated) Si surface was realized as an equivalent dielectric layer, and SE measurements are performed. The SE analyses indicate that after a 20-s 100:5 HF dip with rinse, the Si (100) surface was passivated by the hydrogen termination and remained chemically stable. Roughness of the HF-etched bare Si (100) surface was observed and analyzed by the ex-situ SE. Evidence for desorption of the H-terminated Si surface layer is studied using Fourier transform infrared spectroscopy and ellipsometry, and discussed. This piece of work explains the usage of an ex situ, non-destructive technique capable of showing state of passivation, the H-termination of Si<100> surfaces. PMID:24619506

  6. Phase extraction in microscopy using tunable defocusing by means of a SLM

    NASA Astrophysics Data System (ADS)

    Camacho, Luis; Micó, Vicente; Zalevsky, Zeev; García, Javier

    2011-05-01

    In many practical microscopy applications the use of phase information is crucial. In this contribution we propose a method for phase extraction in a microscopy system based on analysis of images with varying defocusing. The system has no mobile parts owing to the defocusing by means of a spatial light modulator. The base of the method is the captre of images in a microscope with varying tube lens focal lengths. This produce a set of intensity images, all of them related, because the can be generated by free space propagation of a complex distribution which is unknown.

  7. Infrared external reflection spectroscopic studies of phase transitions in Langmuir monolayers of stearyl alcohol

    NASA Astrophysics Data System (ADS)

    Buontempo, Joseph T.; Rice, Stuart A.

    1993-11-01

    There is a steadily growing body of evidence that much of the information available concerning the properties of Langmuir monolayers concerns systems which are not in a state of equilibrium. What are now known to be unrelaxed monolayers of stearyl alcohol exhibit a high surface pressure phase transition whose signature in the isotherm changes from a ``kink'' (0-8 °C), to a small nearly flat region (8-15 °C), and finally to another kink (at higher temperatures). We have carried out external reflection infrared spectroscopic studies of relaxed monolayers of stearyl alcohol along a representative isotherm from each of the mentioned temperature regions. The results of our studies indicate that in each region the surfactant hydrocarbon chain becomes more ordered (i.e., has fewer gauche conformations) as the surface pressure is increased. We find that (i) at 5 °C, throughout the surface pressure range where the change in intramolecular chain order occurs, the collective tilt of the hydrocarbon chains remains nearly constant. For this isotherm the kink signals the point at which the hydrocarbon chains have achieved a very high degree of intramolecular order, perhaps the all-trans limit. (ii) In the 11 °C monolayer, in the phase often referred to as ``superfluid'', the intramolecular disorder in the hydrocarbon chains is measurably greater than in the equivalent phases in the higher and lower temperature regions. We also show that in the relaxed monolayer the nearly flat portion of the isotherm observed in the unrelaxed monolayer is almost totally absent, leaving only a kink very similar to those observed at higher and lower temperatures. (iii) At 25 °C, although the hydrocarbon chains in the relaxed monolayer attain a relatively high degree of intramolecular order, the high surface pressure phase transition is not observed. Instead, the surface pressure levels off at a value below that at which the transition is expected, and below the equilibrium spreading pressure

  8. Conformations and spectroscopic properties of laccaic acid A in the gas phase and in implicit water.

    PubMed

    Dokmaisrijan, Supaporn; Payaka, Apirak; Tantishaiyakul, Vimon; Chairat, Montra; Nimmanpipug, Piyarat; Lee, Vannajan Sanghiran

    2013-03-15

    Conformations and spectroscopic properties of laccaic acid A (lacA) were studied by means of the experimental and theoretical approaches. The minimum energy conformers of lacA in the gas phase and in implicit water obtained from the B3LYP/6-311G(d,p) calculations displayed the same orientation of the COOH and OH groups on the anthraquinone-based component. The intramolecular hydrogen bonds (H-bonds) formed between the COOH, C=O and OH groups are very strong. In contrast, the orientations of the Ph(OH)CH(2)CH(2)NHCOCH(3) substituent moiety on the anthraquinone-based component in the gas phase and in implicit water are completely different. The substituent prefers to bind with the anthraquinone-based component in the gas phase while it moves away from the anthraquinone-based component in implicit water. The calculated IR spectra of the two lowest-lying energy conformers of lacA in the gas phase fit to the experimental FTIR spectrum. The full assignments of the vibrational modes with the correlated vibrational wavenumbers of those conformers were proposed here, for the first time. The intramolecular H-bond formations in lacA can cause the shift of the vibrational wavenumber for the COOH, C=O, OH and NH groups as compared to the normal vibrations of these groups. The NMR spectra showed that the stabilities of the two lowest-lying energy conformers of lacA in the gas phase are comparable and this is consistent with their computational energies. The UV-Vis spectra of the lowest-lying energy conformers of lacA in implicit water were compared with the experimental UV-Vis spectrum. The calculations suggested that the electronic transition in the visible region involves with the singlet π→π(*) excitation which the electron density transfers to a COOH group on the anthraquinone ring.

  9. Observation of dendritic cell morphology under light, phase-contrast or confocal laser scanning microscopy.

    PubMed

    Tan, Yuen-Fen; Leong, Chooi-Fun; Cheong, Soon-Keng

    2010-12-01

    Dendritic cells (DCs) are professional antigen presenting cells of the immune system. They can be generated in vitro from peripheral blood monocytes supplemented with GM-CSF, IL-4 and TNF alpha. During induction, DCs will increase in size and acquire multiple cytoplasmic projections when compared to their precursor cells such as monocytes or haematopoietic stem cells which are usually round or spherical. Morphology of DCs can be visualized by conventional light microscopy after staining or phase-contrast inverted microscopy or confocal laser scanning microscopy. In this report, we described the morphological appearances of DCs captured using the above-mentioned techniques. We found that confocal laser scanning microscopy yielded DCs images with greater details but the operating cost for such a technique is high. On the other hand, the images obtained through light microscopy after appropriate staining or phase contrast microscopy were acceptable for identification purpose. Besides, these equipments are readily available in most laboratories and the cost of operation is affordable. Nevertheless, morphological identification is just one of the methods to characterise DCs. Other methods such as phenotypic expression markers and mixed leukocyte reactions are additional tools used in the characterisation of DCs. PMID:21329180

  10. Phase aberration compensation of digital holographic microscopy based on least squares surface fitting

    NASA Astrophysics Data System (ADS)

    Di, Jianglei; Zhao, Jianlin; Sun, Weiwei; Jiang, Hongzhen; Yan, Xiaobo

    2009-10-01

    Digital holographic microscopy allows the numerical reconstruction of the complex wavefront of samples, especially biological samples such as living cells. In digital holographic microscopy, a microscope objective is introduced to improve the transverse resolution of the sample; however a phase aberration in the object wavefront is also brought along, which will affect the phase distribution of the reconstructed image. We propose here a numerical method to compensate for the phase aberration of thin transparent objects with a single hologram. The least squares surface fitting with points number less than the matrix of the original hologram is performed on the unwrapped phase distribution to remove the unwanted wavefront curvature. The proposed method is demonstrated with the samples of the cicada wings and epidermal cells of garlic, and the experimental results are consistent with that of the double exposure method.

  11. Parallel-quadrature phase-shifting digital holographic microscopy using polarization beam splitter

    PubMed Central

    Das, Bhargab; Yelleswarapu, Chandra S; Rao, DVGLN

    2012-01-01

    We present a digital holography microscopy technique based on parallel-quadrature phase-shifting method. Two π/2 phase-shifted holograms are recorded simultaneously using polarization phase-shifting principle, slightly off-axis recording geometry, and two identical CCD sensors. The parallel phase-shifting is realized by combining circularly polarized object beam with a 45° degree polarized reference beam through a polarizing beam splitter. DC term is eliminated by subtracting the two holograms from each other and the object information is reconstructed after selecting the frequency spectrum of the real image. Both amplitude and phase object reconstruction results are presented. Simultaneous recording eliminates phase errors caused by mechanical vibrations and air turbulences. The slightly off-axis recording geometry with phase-shifting allows a much larger dimension of the spatial filter for reconstruction of the object information. This leads to better reconstruction capability than traditional off-axis holography. PMID:23109732

  12. Parallel-quadrature phase-shifting digital holographic microscopy using polarization beam splitter.

    PubMed

    Das, Bhargab; Yelleswarapu, Chandra S; Rao, Dvgln

    2012-11-01

    We present a digital holography microscopy technique based on parallel-quadrature phase-shifting method. Two π/2 phase-shifted holograms are recorded simultaneously using polarization phase-shifting principle, slightly off-axis recording geometry, and two identical CCD sensors. The parallel phase-shifting is realized by combining circularly polarized object beam with a 45° degree polarized reference beam through a polarizing beam splitter. DC term is eliminated by subtracting the two holograms from each other and the object information is reconstructed after selecting the frequency spectrum of the real image. Both amplitude and phase object reconstruction results are presented. Simultaneous recording eliminates phase errors caused by mechanical vibrations and air turbulences. The slightly off-axis recording geometry with phase-shifting allows a much larger dimension of the spatial filter for reconstruction of the object information. This leads to better reconstruction capability than traditional off-axis holography.

  13. Refractive-index profiling of optical fibers with axial symmetry by use of quantitative phase microscopy.

    PubMed

    Roberts, A; Ampem-Lassen, E; Barty, A; Nugent, K A; Baxter, G W; Dragomir, N M; Huntington, S T

    2002-12-01

    The application of quantitative phase microscopy to refractive-index profiling of optical fibers is demonstrated. Phase images of axially symmetric optical fibers immersed in index-matching fluid are obtained, and the inverse Abel transform is used to obtain the radial refractive-index profile. This technique is straightforward, nondestructive, repeatable, and accurate. Excellent agreement, to within approximately 0.0005, between this method and the index profile obtained with a commercial profiler is obtained.

  14. High Resolution Phase-Sensitive Magnetomotive Optical Coherence Microscopy for Tracking Magnetic Microbeads and Cellular Mechanics

    PubMed Central

    Crecea, Vasilica; Graf, Benedikt W.; Kim, Taewoo; Popescu, Gabriel; Boppart, Stephen A.

    2014-01-01

    We present a real-time multimodal near-infrared imaging technology that tracks externally induced axial motion of magnetic microbeads in single cells in culture. The integrated multimodal imaging technique consists of phase-sensitive magnetomotive optical coherence microscopy (MM-OCM) and multiphoton microscopy (MPM).MPMis utilized for the visualization of multifunctional fluorescent and magnetic microbeads, while MM-OCM detects, with nanometer-scale sensitivity, periodic displacements of the microbeads induced by the modulation of an external magnetic field. Magnetomotive signals are measured from mouse macrophages, human breast primary ductal carcinoma cells, and human breast epithelial cells in culture, and validated with full-field phase-sensitive microscopy. This methodology demonstrates the capability for imaging controlled cell dynamics and has the potential for measuring cell biomechanical properties, which are important in assessing the health and pathological state of cells. PMID:25400496

  15. High Resolution Phase-Sensitive Magnetomotive Optical Coherence Microscopy for Tracking Magnetic Microbeads and Cellular Mechanics.

    PubMed

    Crecea, Vasilica; Graf, Benedikt W; Kim, Taewoo; Popescu, Gabriel; Boppart, Stephen A

    2014-03-01

    We present a real-time multimodal near-infrared imaging technology that tracks externally induced axial motion of magnetic microbeads in single cells in culture. The integrated multimodal imaging technique consists of phase-sensitive magnetomotive optical coherence microscopy (MM-OCM) and multiphoton microscopy (MPM).MPMis utilized for the visualization of multifunctional fluorescent and magnetic microbeads, while MM-OCM detects, with nanometer-scale sensitivity, periodic displacements of the microbeads induced by the modulation of an external magnetic field. Magnetomotive signals are measured from mouse macrophages, human breast primary ductal carcinoma cells, and human breast epithelial cells in culture, and validated with full-field phase-sensitive microscopy. This methodology demonstrates the capability for imaging controlled cell dynamics and has the potential for measuring cell biomechanical properties, which are important in assessing the health and pathological state of cells.

  16. Multi-modal digital holographic microscopy for wide-field fluorescence and 3D phase imaging

    NASA Astrophysics Data System (ADS)

    Quan, Xiangyu; Xia, Peng; Matoba, Osamu; Nitta, Koichi; Awatsuji, Yasuhiro

    2016-03-01

    Multi-modal digital holographic microscopy is a combination of epifluorescence microscopy and digital holographic microscopy, the main function of which is to obtain images from fluorescence intensity and quantified phase contrasts, simultaneously. The proposed system is mostly beneficial to biological studies, with the reason that often the studies are depending on fluorescent labeling techniques to detect certain intracellular molecules, while phase information reflecting properties of unstained transparent elements. This paper is presenting our latest researches on applications such as randomly moving micro-fluorescent beads and living cells of Physcomitrella patens. The experiments are succeeded on obtaining a succession of wide-field fluorescent images and holograms from micro-beads, and different depths focusing is realized via numerical reconstruction. Living cells of Physcomitrella patens are recorded in the static manner, the reconstruction distance indicates thickness of cellular structure. These results are implementing practical applications toward many biomedical science researches.

  17. Total internal reflection holographic microscopy (TIRHM) for quantitative phase characterization of cell-substrate adhesion

    NASA Astrophysics Data System (ADS)

    Ash, William Mason, III

    Total Internal Reflection Holographic Microscopy (TIRHM) combines near-field microscopy with digital holography to produce a new form of near-field phase microscopy. Using a prism in TIR as a near-field imager, the presence of microscopic organisms, cell-substrate interfaces, and adhesions, causes relative refractive index (RRI) and frustrated TIR (f-TIR) to modulate the object beam's evanescent wave phase front. Quantitative phase images of test specimens such as Amoeba proteus, Dictyostelium Discoideum and cells such as SKOV-3 ovarian cancer and 3T3 fibroblasts are produced without the need to introduce stains or fluorophores. The angular spectrum method of digital holography to compensate for tilt anamorphism due to the inclined TIR plane is also discussed. The results of this work conclusively demonstrate, for the first time, the integration of near-field microscopy with digital holography. The cellular images presented show a correlation between the physical extent of the Amoeba proteus plasma membrane and the adhesions that are quantitatively profiled by phase cross-sectioning of the holographic images obtained by digital holography. With its ability to quantitatively characterise cellular adhesion and motility, it is anticipated that TIRHM can be a tool for characterizing and combating cancer metastasis, as well as improving our understanding of morphogenesis and embryogenesis itself.

  18. Monitoring cells in engineered tissues with optical coherence phase microscopy: Optical phase fluctuations as endogenous sources of contrast

    NASA Astrophysics Data System (ADS)

    Bagnaninchi, P. O.; Holmes, Christina; Tabrizian, Maryam

    2013-02-01

    There is a need in tissue engineering to monitor cell growth and health within 3D constructs non-invasively and in a label-free manner. We have previously shown that optical coherence phase microscopy was sensitive enough to monitor intracellular motion. Here we demonstrate that intracellular motility can be used as an endogeneous contrast agent to image cells in various 3D engineered tissue architectures. Phase and intensity-based reconstruction algorithms are compared. In this study, we used an optical coherence phase microscope set up in a common path configuration, developed around a Callisto OCT engine (Thorlbas) centred at 930nm and an inverted microscope with a custom scanning head. Intensity data were used to perform in-depth microstructural imaging. In addition, phase fluctuations were measured by collecting several successive B scans at the same location, and the first time derivative of the phase, i.e. time fluctuations, was analysed over the acquisition time interval to map the motility. Alternative intensity-based Doppler variance algorithms were also investigated. Two distinct scaffold systems seeded with adult stem cells; algimatrix (Invitrogen) and custom microfabricated poly(D,L-lactic-co-glycolic acid) fibrous scaffolds, as well as cell pellets were imaged. We showed that optical phase fluctuations resulting from intracellular motility can be used as an endogenous source of contrast for optical coherence phase microscopy enabling the distinction of viable cells from the surrounding scaffold.

  19. Extension of spectral domain phase microscopy to three-dimensional nanoscale displacement mapping in cardiomyocytes

    NASA Astrophysics Data System (ADS)

    Ellerbee, Audrey K.; Hendargo, Hansford C.; Motomura, Amy R.; Izatt, Joseph A.

    2008-02-01

    Spectral domain phase microscopy (SDPM) is a functional extension of optical coherence tomography (OCT) whose common-path interferometric design enables phase-referenced imaging of dynamic samples. Like OCT, axial resolution in SDPM is determined by the source coherence length, while lateral resolution is limited by diffraction in the microscope optics. Nonetheless, the quantitative phase information SDPM generates is sensitive to sub-Angstrom displacements of scattering structures. Integrative quantitative phase imaging techniques, such as Fourier phase microscopy, Hilbert phase microscopy, and Digital holographic microscopy, have achieved sub-micron motion detection in live cells. In contrast with the techniques, SDPM can achieve full depth discrimination, allowing for resolution of the motion of independent, sub-cellular structures at various cross-sectional planes within the sample. The ability of SDPM to measure Doppler flow in single-celled organisms, time-resolved cellular motions, and rheological information of the cytoskeleton has been previously demonstrated. The objective of this study is to extend the use of SDPM to produce three-dimensional reconstructions of the internal and surface motions of beating cardiomyocytes. Phase information is used to the motion of quantify cellular structures in the axial dimension. Our gated acquisition process involves synchronization of the SDPM detection system with and applied electrical field used to stimulate beating in isolated cardiomyocytes. For a given pacing protocol, we obtain repeat motion measurements in two-dimensions during cellular contraction, building a volume image by repeating the process at multiple discrete slices through the cell. This experiment serves as a proof-of-principle for volumetric imaging of beating cardiomyocytes.

  20. Pre-phase A: Development of a far-ultraviolet photometric- and spectroscopic-survey small-explorer experiment

    NASA Technical Reports Server (NTRS)

    Martin, Christopher

    1993-01-01

    We propose to perform a far ultraviolet photometric and spectroscopic survey covering the lambda lambda 1300-2000 band with a sensitivity comparable to that of the Palomar Sky Survey. This survey will proceed in three phases: an all-sky survey in three bands to 18-19.5(sup m), deep surveys of selected targets of interest in the same bands to 21-22(sup m), and a spectroscopic survey of 2 percent of the sky to 18(sup m) with a resolution of 3-20A. This mission, the Joint Ultraviolet Nightsky Observer (JUNO), can be performed by a Small-Explorer-class satellite.

  1. Measurements of adipose derived stem cell vitality with optical coherence phase microscopy

    NASA Astrophysics Data System (ADS)

    Bagnaninchi, P. O.; Holmes, C.; Drummond, N.; Daoud, J.; Tabrizian, M.

    2011-03-01

    Live cells display a constant vertical motility due partly to a constant rearrangement of focal contacts and to cell shape fluctuations. This cellular micromotion has been clearly demonstrated with electric cell impedance sensing (ECIS) on 2D micro-electrodes, and correlated to cell vitality. In this study we investigated if optical coherence phase microscopy (OCPM) was able to report phase fluctuations of adult stem cells in 2D and 3D that could be correlated to cell motility. An OCPM has been developed around a Thorlabs engine (λο=930nm FWHM: 90nm) and integrated in an inverted microscope with a custom scanning head. Human adipose derived stem cells (ADSCs, Invitrogen) were cultured in Mesenpro RS medium and seeded either on ECIS arrays, 2D cell culture dishes, or in 3D highly porous microplotted polymeric scaffolds. ADSC motility was measured by ECIS and a spectral analysis was performed to retrieve the power spectral density (PSD) of the fluctuations. Cells in standard media and fixed cells were investigated. The same conditions were then investigated for ADSCs in 2D and in 3D with optical coherence phase microscopy. Significant differences were found in phase fluctuations between the different conditions, which correlated well with ECIS experiments. These preliminary results indicated that optical coherence phase microscopy could assess cell vitality in 2D and potentially in 3D microstructures.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

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

    PubMed

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

    2016-01-01

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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-02-29

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

  6. 22 nm node wafer inspection using diffraction phase microscopy and image post-processing

    NASA Astrophysics Data System (ADS)

    Zhou, Renjie; Popescu, Gabriel; Goddard, Lynford L.

    2013-04-01

    We applied epi-illumination diffraction phase microscopy to measure the amplitude and phase of the scattered field from a SEMATECH 22 nm node intentional defect array (IDA) wafer. We used several imaging processing techniques to remove the wafer's underlying structure and reduce both the spatial and temporal noise and eliminate the system calibration error to produce stretched panoramic amplitude and phase images. From the stretched images, we detected defects down to 20 nm × 160 nm for a parallel bridge, 20 nm × 100 nm for perpendicular bridge, and 35 nm × 70 nm for an isolated dot.

  7. Computational illumination for real-time gigapixel phase microscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Waller, Laura

    2016-03-01

    This talk will describe new source coding methods for rapid acquisition of high-resolution phase images across a very large field of view, using a modified commercial microscope with LED array illumination. Our methods are inspired by a hybrid combination of Fourier Ptychography and differential phase contrast imaging, combined with source multiplexing strategies for fast capture and significantly reduced data requirements. Such computational approaches to optical microscopy add significant new capabilities to commercial microscopes without much cost or hardware modification. We demonstrate our system on live samples in vivo, validating our results for unstained, label-free samples against other popular phase retrieval methods.

  8. Quantitative tracking of tumor cells in phase-contrast microscopy exploiting halo artifact pattern

    NASA Astrophysics Data System (ADS)

    Kang, Mi-Sun; Song, Soo-Min; Lee, Hana; Kim, Myoung-Hee

    2012-03-01

    Tumor cell morphology is closely related to its invasiveness characteristics and migratory behaviors. An invasive tumor cell has a highly irregular shape, whereas a spherical cell is non-metastatic. Thus, quantitative analysis of cell features is crucial to determine tumor malignancy or to test the efficacy of anticancer treatment. We use phase-contrast microscopy to analyze single cell morphology and to monitor its change because it enables observation of long-term activity of living cells without photobleaching and phototoxicity, which is common in other fluorescence-labeled microscopy. Despite this advantage, there are image-level drawbacks to phase-contrast microscopy, such as local light effect and contrast interference ring, among others. Thus, we first applied a local filter to compensate for non-uniform illumination. Then, we used intensity distribution information to detect the cell boundary. In phase-contrast microscopy images, the cell normally appears as a dark region surrounded by a bright halo. As the halo artifact around the cell body is minimal and has an asymmetric diffusion pattern, we calculated the cross-sectional plane that intersected the center of each cell and was orthogonal to the first principal axis. Then, we extracted the dark cell region by level set. However, a dense population of cultured cells still rendered single-cell analysis difficult. Finally, we measured roundness and size to classify tumor cells into malignant and benign groups. We validated segmentation accuracy by comparing our findings with manually obtained results.

  9. Halo suppression in full-field x-ray Zernike phase contrast microscopy.

    PubMed

    Vartiainen, Ismo; Mokso, Rajmund; Stampanoni, Marco; David, Christian

    2014-03-15

    Visible light Zernike phase contrast (ZPC) microscopy is a well established method for imaging weakly absorbing samples. The method is also used with hard x-ray photon energies for structural evaluation of material science and biological applications. However, the method suffers from artifacts that are inherent for the Zernike image formation. In this Letter, we investigate their origin and experimentally show how to suppress them in x-ray full-field ZPC microscopy based on diffractive x-ray optics. PMID:24690848

  10. Using quantitative interference phase microscopy for sperm acrosome evaluation (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Balberg, Michal; Kalinowski, Ksawery; Levi, Mattan; Shaked, Natan T.

    2016-03-01

    We demonstrate quantitative assessment of sperm cell morphology, primarily acrosomal volume, using quantitative interference phase microscopy (IPM). Normally, the area of the acrosome is assessed using dyes that stain the acrosomal part of the cell. We have imaged fixed individual sperm cells using IPM. Following, the sample was stained and the same cells were imaged using bright field microscopy (BFM). We identified the acrosome using the stained BFM image, and used it to define a quantitative corresponding area in the IPM image and determine a quantitative threshold for evaluating the volume of the acrosome.

  11. One-particle spectroscopic intensities as a signature of shape phase transition: The {gamma}-unstable case

    SciTech Connect

    Alonso, C. E.; Arias, J. M.; Vitturi, A.

    2006-08-15

    We investigate the evolution of one-particle spectroscopic intensities as a possible signature of shape phase transitions. The study describes the odd systems in terms of the interacting boson-fermion model. We consider the particular case of an odd j=3/2 particle coupled to an even-even boson core that undergoes a phase transition from spherical U(5) to {gamma}-unstable O(6) situation. At the critical point, our findings are compared with the one-particle spectroscopic intensities that can be obtained within the E(5/4) model proposed by[F. Iachello, Phys. Rev. Lett. 95, 052503 (2005); F. Iachello, in Symmetries and Low-Energy Phase Transitions in Nuclear Structure Physics, edited by G. Lo Bianco (University of Camerino Press, Camerino, Italy, in press)].

  12. Cell segmentation in phase contrast microscopy images via semi-supervised classification over optics-related features.

    PubMed

    Su, Hang; Yin, Zhaozheng; Huh, Seungil; Kanade, Takeo

    2013-10-01

    Phase-contrast microscopy is one of the most common and convenient imaging modalities to observe long-term multi-cellular processes, which generates images by the interference of lights passing through transparent specimens and background medium with different retarded phases. Despite many years of study, computer-aided phase contrast microscopy analysis on cell behavior is challenged by image qualities and artifacts caused by phase contrast optics. Addressing the unsolved challenges, the authors propose (1) a phase contrast microscopy image restoration method that produces phase retardation features, which are intrinsic features of phase contrast microscopy, and (2) a semi-supervised learning based algorithm for cell segmentation, which is a fundamental task for various cell behavior analysis. Specifically, the image formation process of phase contrast microscopy images is first computationally modeled with a dictionary of diffraction patterns; as a result, each pixel of a phase contrast microscopy image is represented by a linear combination of the bases, which we call phase retardation features. Images are then partitioned into phase-homogeneous atoms by clustering neighboring pixels with similar phase retardation features. Consequently, cell segmentation is performed via a semi-supervised classification technique over the phase-homogeneous atoms. Experiments demonstrate that the proposed approach produces quality segmentation of individual cells and outperforms previous approaches.

  13. Flipping interferometry and its application for quantitative phase microscopy in a micro-channel.

    PubMed

    Roitshtain, Darina; Turko, Nir A; Javidi, Bahram; Shaked, Natan T

    2016-05-15

    We present a portable, off-axis interferometric module for quantitative phase microscopy of live cells, positioned at the exit port of a coherently illuminated inverted microscope. The module creates on the digital camera an interference pattern between the image of the sample and its flipped version. The proposed simplified module is based on a retro-reflector modification in an external Michelson interferometer. The module does not contain any lenses, pinholes, or gratings and its alignment is straightforward. Still, it allows full control of the off-axis angle and does not suffer from ghost images. As experimentally demonstrated, the module is useful for quantitative phase microscopy of live cells rapidly flowing in a micro-channel. PMID:27177001

  14. Spectroscopic characterization of charged defects in polycrystalline pentacene by time- and wavelength-resolved electric force microscopy.

    PubMed

    Luria, Justin L; Schwarz, Kathleen A; Jaquith, Michael J; Hennig, Richard G; Marohn, John A

    2011-02-01

    Spatial maps of topography and trapped charge are acquired for polycrystalline pentacene thin-film transistors using electric and atomic force microscopy. In regions of trapped charge, the rate of trap clearing is studied as a function of the wavelength of incident radiation.

  15. Doppler flow imaging of cytoplasmic streaming using spectral domain phase microscopy

    NASA Astrophysics Data System (ADS)

    Choma, Michael A.; Ellerbee, Audrey K.; Yazdanfar, Siavash; Izatt, Joseph A.

    2006-03-01

    Spectral domain phase microscopy (SDPM) is a function extension of spectral domain optical coherence tomography. SDPM achieves exquisite levels of phase stability by employing common-path interferometry. We discuss the theory and limitations of Doppler flow imaging using SDPM, demonstrate monitoring the thermal contraction of a glass sample with nanometer per second velocity sensitivity, and apply this technique to measurement of cytoplasmic streaming in an Amoeba proteus pseudopod. We observe reversal of cytoplasmic flow induced by extracellular CaCl2, and report results that suggest parabolic flow of cytoplasm in the A. proteus pseudopod.

  16. Projection phase contrast microscopy with a hard x-ray nanofocused beam: Defocus and contrast transfer

    SciTech Connect

    Salditt, T.; Giewekemeyer, K.; Fuhse, C.; Krueger, S. P.; Tucoulou, R.; Cloetens, P.

    2009-05-01

    We report a projection phase contrast microscopy experiment using hard x-ray pink beam undulator radiation focused by an adaptive mirror system to 100-200 nm spot size. This source is used to illuminate a lithographic test pattern with a well-controlled range of spatial frequencies. The oscillatory nature of the contrast transfer function with source-to-sample distance in this holographic imaging scheme is quantified and the validity of the weak phase object approximation is confirmed for the experimental conditions.

  17. Confocal reflectance quantitative phase microscopy system for cell biology studies (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Singh, Vijay Raj; So, Peter T. C.

    2016-03-01

    Quantitative phase microscopy (QPM), used to measure the refractive index, provides the optical path delay measurement at each point of the specimen under study and becomes an active field in biological science. In this work we present development of confocal reflection phase microscopy system to provide depth resolved quantitative phase information for investigation of intracellular structures and other biological specimen. The system hardware development is mainly divided into two major parts. First, creates a pinhole array for parallel confocal imaging of specimen at multiple locations simultaneously. Here a digital micro mirror device (DMD) is used to generate pinhole array by turning on a subset micro-mirrors arranged on a grid. Second is the detection of phase information of confocal imaging foci by using a common path interferometer. With this novel approach, it is possible to measure the nuclei membrane fluctuations and distinguish them from the plasma membrane fluctuations. Further, depth resolved quantitative phase can be correlated to the intracellular contents and 3D map of refractive index measurements.

  18. Online quantitative phase imaging of vascular endothelial cells under fluid shear stress utilizing digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Odenthal-Schnittler, Maria; Schnittler, Hans Joachim; Kemper, Björn

    2016-03-01

    We have explored the utilization of quantitative phase imaging with digital holographic microscopy (DHM) as a novel tool for quantifying the dynamics of morphologic parameters (morphodynamics) of confluent endothelial cell layers under fluid shear stress conditions. Human umbilical vein endothelial cells (HUVECs) were exposed to fluid shear stress in a transparent cone/plate flow device (BioTech-Flow-System) and imaged with a modular setup for quantitative DHM phase imaging for up to 48 h. The resulting series of quantitative phase image sequences were analyzed for the average surface roughness of the cell layers and cell alignment. Our results demonstrate that quantitative phase imaging is a powerful and reliable tool to quantify the dynamics of morphological adaptation of endothelial cells to fluid shear stress.

  19. Magneto-optical spectroscopic studies of solid and solution-phase tetra-phenyl porphyrin

    NASA Astrophysics Data System (ADS)

    Wahlen-Strothman, Jacob; Pan, Zhen Wen; Lamarche, Cody; Manning, Lane; Rawat, Naveen; Tokumoto, Takahisa; McGill, Stephen; Furis, Madalina; Chu, Kelvin

    2012-02-01

    Tetraphenylporphyrin (TPP) is a heterocyclic model system for porphyrins found in heme proteins, cytochromes and photosynthetic cofactors. TPP can accommodate a metal ion in the center; D-shell ion porphyrin complexes with a crystalline solid phase are of interest for magnetic studies because of the possibility of macroscopic long-range magnetic order of the ion spins. We have investigated the 5K magnetic properties of poly-crystalline thin films of TPP complexed with Zn, Mn and Cu and deposited through a room temperature capillary pen technique that produces grain size in the 100 micron to 1mm range. Our novel setup measures the UV/VIS, linear dichroism and MCD simultaneously and incorporates a photoelastic modulator and a microscopy superconducting magnet for high-field (5T) measurements. In addition, we present 25T data on samples from the new split magnet at NHMFL. We present solution and crystalline data on metal-complexed TPP; data are analyzed in terms of A and B-type MCD using a perimeter model. We find good agreement with previous solution data, and novel crystalline phase spectra that are correlated to the long range ordering of the solid state.

  20. Laser Spectroscopic Study of Cold Gas-Phase Host-Guest Complexes of Crown Ethers.

    PubMed

    Ebata, Takayuki; Inokuchi, Yoshiya

    2016-06-01

    The structure, molecular recognition, and inclusion effect on the photophysics of guest species are investigated for neutral and ionic cold host-guest complexes of crown ethers (CEs) in the gas phase. Here, the cold neutral host-guest complexes are produced by a supersonic expansion technique and the cold ionic complexes are generated by the combination of electrospray ionization (ESI) and a cryogenically cooled ion trap. The host species are 3n-crown-n (3nCn; n = 4, 5, 6, 8) and (di)benzo-3n-crown-n ((D)B3nCn; n = 4, 5, 6, 8). For neutral guests, we have chosen water and aromatic molecules, such as phenol and benzenediols, and as ionic species we have chosen alkali-metal ions (M(+) ). The electronic spectra and isomer-specific vibrational spectra for the complexes are observed with various laser spectroscopic methods: laser-induced fluorescence (LIF); ultraviolet-ultraviolet hole-burning (UV-UV HB); and IR-UV double resonance (IR-UV DR) spectroscopy. The obtained spectra are analyzed with the aid of quantum chemical calculations. We will discuss how the host and guest species change their flexible structures for forming best-fit stable complexes (induced fitting) and what kinds of interactions are operating for the stabilization of the complexes. For the alkali metal ion•CE complexes, we investigate the solvation effect by attaching water molecules. In addition to the ground-state stabilization problem, we will show that the complexation leads to a drastic effect on the excited-state electronic structure and dynamics of the guest species, which we call a "cage-like effect". PMID:27006080

  1. Invited Review Article: Methods for imaging weak-phase objects in electron microscopy

    PubMed Central

    Glaeser, Robert M.

    2013-01-01

    Contrast has traditionally been produced in electron-microscopy of weak phase objects by simply defocusing the objective lens. There now is renewed interest, however, in using devices that apply a uniform quarter-wave phase shift to the scattered electrons relative to the unscattered beam, or that generate in-focus image contrast in some other way. Renewed activity in making an electron-optical equivalent of the familiar “phase-contrast” light microscope is based in part on the improved possibilities that are now available for device microfabrication. There is also a better understanding that it is important to take full advantage of contrast that can be had at low spatial frequency when imaging large, macromolecular objects. In addition, a number of conceptually new phase-plate designs have been proposed, thus increasing the number of options that are available for development. The advantages, disadvantages, and current status of each of these options is now compared and contrasted. Experimental results that are, indeed, superior to what can be accomplished with defocus-based phase contrast have been obtained recently with two different designs of phase-contrast aperture. Nevertheless, extensive work also has shown that fabrication of such devices is inconsistent, and that their working lifetime is short. The main limitation, in fact, appears to be electrostatic charging of any device that is placed into the electron diffraction pattern. The challenge in fabricating phase plates that are practical to use for routine work in electron microscopy thus may be more in the area of materials science than in the area of electron optics. PMID:24289381

  2. Quantitative X-ray projection microscopy: phase-contrast and multi-spectral imaging.

    PubMed

    Mayo, S C; Miller, P R; Wilkins, S W; Davis, T J; Gao, D; Gureyev, T E; Paganin, D; Parry, D J; Pogany, A; Stevenson, A W

    2002-08-01

    We outline a new approach to X-ray projection microscopy in a scanning electron microscope (SEM), which exploits phase contrast to boost the quality and information content of images. These developments have been made possible by the combination of a high-brightness field-emission gun (FEG)-based SEM, direct detection CCD technology and new phase retrieval algorithms. Using this approach we have been able to obtain spatial resolution of < 0.2 micro m and have demonstrated novel features such as: (i) phase-contrast enhanced visibility of high spatial frequency image features (e.g. edges and boundaries) over a wide energy range; (ii) energy-resolved imaging to simultaneously produce multiple quasi-monochromatic images using broad-band polychromatic illumination; (iii) easy implementation of microtomography; (iv) rapid and robust phase/amplitude-retrieval algorithms to enable new real-time and quantitative modes of microscopic imaging. These algorithms can also be applied successfully to recover object-plane information from intermediate-field images, unlocking the potentially greater contrast and resolution of the intermediate-field regime. Widespread applications are envisaged for fields such as materials science, biological and biomedical research and microelectronics device inspection. Some illustrative examples are presented. The quantitative methods described here are also very relevant to projection microscopy using other sources of radiation, such as visible light and electrons.

  3. 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

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

    PubMed

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

    2014-04-30

    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.

  5. Cell morphology classification in phase contrast microscopy image reducing halo artifact

    NASA Astrophysics Data System (ADS)

    Kang, Mi-Sun; Song, Soo-Min; Lee, Hana; Kim, Myoung-Hee

    2012-03-01

    Since the morphology of tumor cells is a good indicator of their invasiveness, we used time-lapse phase-contrast microscopy to examine the morphology of tumor cells. This technique enables long-term observation of the activity of live cells without photobleaching and phototoxicity which is common in other fluorescence-labeled microscopy. However, it does have certain drawbacks in terms of imaging. Therefore, we first corrected for non-uniform illumination artifacts and then we use intensity distribution information to detect cell boundary. In phase contrast microscopy image, cell is normally appeared as dark region surrounded by bright halo ring. Due to halo artifact is minimal around the cell body and has non-symmetric diffusion pattern, we calculate cross sectional plane which intersects center of each cell and orthogonal to first principal axis. Then, we extract dark cell region by analyzing intensity profile curve considering local bright peak as halo area. Finally, we examined cell morphology to classify tumor cells as malignant and benign.

  6. Characterization of Homopolymer and Polymer Blend Films by Phase Sensitive Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Ngwa, Wilfred; Wannemacher, Reinhold; Grill, Wolfgang

    2003-03-01

    CHARACTERIZATION OF HOMOPOLYMER AND POLYMER BLEND FILMS BY PHASE SENSITIVE ACOUSTIC MICROSCOPY W Ngwa, R Wannemacher, W Grill Institute of Experimental Physics II, University of Leipzig, 04103 Leipzig, Germany Abstract We have used phase sensitive acoustic microscopy (PSAM) to study homopolymer thin films of polystyrene (PS) and poly (methyl methacrylate) (PMMA), as well as PS/PMMA blend films. We show from our results that PSAM can be used as a complementary and highly valuable technique for elucidating the three-dimensional (3D) morphology and micromechanical properties of thin films. Three-dimensional image acquisition with vector contrast provides the basis for: complex V(z) analysis (per image pixel), 3D image processing, height profiling, and subsurface image analysis of the polymer films. Results show good agreement with previous studies. In addition, important new information on the three dimensional structure and properties of polymer films is obtained. Homopolymer film structure analysis reveals (pseudo-) dewetting by retraction of droplets, resulting in a morphology that can serve as a starting point for the analysis of polymer blend thin films. The outcome of confocal laser scanning microscopy studies, performed on the same samples are correlated with the obtained results. Advantages and limitations of PSAM are discussed.

  7. Digital Holographic Microscopy: Quantitative Phase Imaging and Applications in Live Cell Analysis

    NASA Astrophysics Data System (ADS)

    Kemper, Björn; Langehanenberg, Patrik; Kosmeier, Sebastian; Schlichthaber, Frank; Remmersmann, Christian; von Bally, Gert; Rommel, Christina; Dierker, Christian; Schnekenburger, Jürgen

    The analysis of complex processes in living cells creates a high demand for fast and label-free methods for online monitoring. Widely used fluorescence methods require specific labeling and are often restricted to chemically fixated samples. Thus, methods that offer label-free and minimally invasive detection of live cell processes and cell state alterations are of particular interest. In combination with light microscopy, digital holography provides label-free, multi-focus quantitative phase imaging of living cells. In overview, several methods for digital holographic microscopy (DHM) are presented. First, different experimental setups for the recording of digital holograms and the modular integration of DHM into common microscopes are described. Then the numerical processing of digitally captured holograms is explained. This includes the description of spatial and temporal phase shifting techniques, spatial filtering based reconstruction, holographic autofocusing, and the evaluation of self-interference holograms. Furthermore, the usage of partial coherent light and multi-wavelength approaches is discussed. Finally, potentials of digital holographic microscopy for quantitative cell imaging are illustrated by results from selected applications. It is shown that DHM can be used for automated tracking of migrating cells and cell thickness monitoring as well as for refractive index determination of cells and particles. Moreover, the use of DHM for label-free analysis in fluidics and micro-injection monitoring is demonstrated. The results show that DHM is a highly relevant method that allows novel insights in dynamic cell biology, with applications in cancer research and for drugs and toxicity testing.

  8. In situ transmission electron microscopy of solid-liquid phase transition of silica encapsulated bismuth nanoparticles

    NASA Astrophysics Data System (ADS)

    Hu, Jianjun; Hong, Yan; Muratore, Chris; Su, Ming; Voevodin, Andrey A.

    2011-09-01

    The solid-liquid phase transition of silica encapsulated bismuth nanoparticles was studied by in situ transmission electron microscopy (TEM). The nanoparticles were prepared by a two-step chemical synthesis process involving thermal decomposition of organometallic precursors for nucleating bismuth and a sol-gel process for growing silica. The microstructural and chemical analyses of the nanoparticles were performed using high-resolution TEM, Z-contrast imaging, focused ion beam milling, and X-ray energy dispersive spectroscopy. Solid-liquid-solid phase transitions of the nanoparticles were directly recorded by electron diffractions and TEM images. The silica encapsulation of the nanoparticles prevented agglomeration and allowed particles to preserve their original volume upon melting, which is desirable for applications of phase change nanoparticles with consistently repeatable thermal properties.

  9. In situ transmission electron microscopy of solid-liquid phase transition of silica encapsulated bismuth nanoparticles.

    PubMed

    Hu, Jianjun; Hong, Yan; Muratore, Chris; Su, Ming; Voevodin, Andrey A

    2011-09-01

    The solid-liquid phase transition of silica encapsulated bismuth nanoparticles was studied by in situ transmission electron microscopy (TEM). The nanoparticles were prepared by a two-step chemical synthesis process involving thermal decomposition of organometallic precursors for nucleating bismuth and a sol-gel process for growing silica. The microstructural and chemical analyses of the nanoparticles were performed using high-resolution TEM, Z-contrast imaging, focused ion beam milling, and X-ray energy dispersive spectroscopy. Solid-liquid-solid phase transitions of the nanoparticles were directly recorded by electron diffractions and TEM images. The silica encapsulation of the nanoparticles prevented agglomeration and allowed particles to preserve their original volume upon melting, which is desirable for applications of phase change nanoparticles with consistently repeatable thermal properties.

  10. Coherent scattering microscopy as an effective inspection tool for analyzing performance of phase shift mask.

    PubMed

    Woo, Dong Gon; Lee, Jae Uk; Hong, Seong Chul; Kim, Jung Sik; Ahn, Jinho

    2016-05-30

    The imaging performance of a half-tone phase shift mask (PSM) has been analyzed using coherent scattering microscopy (CSM), which allows analysis of the actinic characteristics of an extreme ultraviolet (EUV) mask such as its reflectivity, diffraction efficiency, and phase information. This paper presents the 1st experimental result showing the effect of 180° phase difference between the absorber and reflector in EUV mask. This reveals that a PSM offers a 46% improvement in 1st/0th diffraction efficiency and 14% improvement in image contrast when compared to a binary intensity mask (BIM). The horizontal-vertical critical dimension (H-V CD) bias is also reduced by 1.37 nm at 22 nm line and space (L/S) patterns. Since the performance of PSM can be evaluated without a wafer patterning process, CSM is expected to be a useful inspection tool for the development of novel EUV masks. PMID:27410126

  11. Analysis of mixed cell cultures with quantitative digital holographic phase microscopy

    NASA Astrophysics Data System (ADS)

    Kemper, Björn; Wibbeling, Jana; Ketelhut, Steffi

    2014-05-01

    In order to study, for example, the influence of pharmaceuticals or pathogens on different cell types under identical measurement conditions and to analyze interactions between different cellular specimens a minimally-invasive quantitative observation of mixed cell cultures is of particular interest. Quantitative phase microscopy (QPM) provides high resolution detection of optical path length changes that is suitable for stain-free minimally-invasive live cell analysis. Due to low light intensities for object illumination, QPM minimizes the interaction with the sample and is in particular suitable for long term time-lapse investigations, e.g., for the detection of cell morphology alterations due to drugs and toxins. Furthermore, QPM has been demonstrated to be a versatile tool for the quantification of cellular growth, the extraction morphological parameters and cell motility. We studied the feasibility of QPM for the analysis of mixed cell cultures. It was explored if quantitative phase images provide sufficient information to distinguish between different cell types and to extract cell specific parameters. For the experiments quantitative phase imaging with digital holographic microscopy (DHM) was utilized. Mixed cell cultures with different types of human pancreatic tumor cells were observed with quantitative DHM phase contrast up to 35 h. The obtained series of quantitative phase images were evaluated by adapted algorithms for image segmentation. From the segmented images the cellular dry mass and the mean cell thickness were calculated and used in the further analysis as parameters to quantify the reliability the measurement principle. The obtained results demonstrate that it is possible to characterize the growth of cell types with different morphologies in a mixed cell culture separately by consideration of specimen size and cell thickness in the evaluation of quantitative DHM phase images.

  12. FT-IR spectroscopic study of phase transformation of chloropinnoite in boric acid solution at 303 K

    NASA Astrophysics Data System (ADS)

    Zhihong, Liu; Shiyang, Gao; Shuping, Xia

    2003-01-01

    The dissolution and transformation of chloropinnoite in boric acid solution at 303 K has been studied using FT-IR difference spectroscopic technique. After equilibrium was reached, liquid and solid phases were separated and FT-IR spectra of each phase were recorded, FT-IR spectroscopic analysis of solid phases indicated that the transformation products, with the increase of boron-concentration in solution, were 2MgO · 3B 2O 3 · 15H 2O (inderite), 2MgO · 3B 2O 3 · 15H 2O (kurnakovite), MgO · 3B 2O 3 · 7.5H 2O, and MgO · 3B 2O 3 · 7H 2O, respectively. The main polyborate anions and their interaction in each borate saturated aqueous solution have been proposed according to the FT-IR difference spectra of borate in liquid phase, and some assignments were tentatively given firstly. The relations between the existing forms of polyborate anions and the crystallizing solid phases have been gained.

  13. Total three-dimensional imaging of phase objects using defocusing microscopy: Application to red blood cells

    NASA Astrophysics Data System (ADS)

    Roma, P. M. S.; Siman, L.; Amaral, F. T.; Agero, U.; Mesquita, O. N.

    2014-06-01

    We introduce Defocusing Microscopy (DM), a bright-field optical microscopy technique able to perform total three-dimensional (3D) imaging of transparent objects. By total 3D imaging, we mean the determination of the actual shapes of the upper and lower surfaces of a phase object. We propose a methodology using DM and apply it to red blood cells subject to different osmolality conditions: hypotonic, isotonic, and hypertonic solutions. For each situation, the shapes of the upper and lower cell surface-membranes (lipid bilayer/cytoskeleton) are completely recovered, displaying the deformation of red blood cell (RBC) surfaces due to adhesion on the glass-substrate. The axial resolution of our technique allowed us to image surface-membranes separated by distances as small as 300 nm. Finally, we determine the volume, surface area, sphericity index, and RBC refractive index for each osmotic condition.

  14. Superresolution Microscopy of the Volume Phase Transition of pNIPAM Microgels

    NASA Astrophysics Data System (ADS)

    Conley, Gaurasundar Marc; Nöjd, Sofi; Braibanti, Marco; Schurtenberger, Peter; Scheffold, Frank

    Hierarchical polymer structures such as pNIPAM microgels have been extensively studied for their ability to undergo significant structural and physical transformations that can be controlled by external stimuli such as temperature, pH or solvent composition. Here we discuss in-situ three-dimensional superresolution microscopy of dye-labeled submicron sized PNiPAM microgels. We use direct STochastic Optical Reconstruction Microscopy (dSTORM) to study the internal density distribution and the particle-to-particle variability of the volume phase transition. Moreover we discuss the potential of this technique towards future applications to more complex architectures for example microgel with anisotropic shape or ones that are doped or decorated with nanoparticles.

  15. An improved phase shift reconstruction algorithm of fringe scanning technique for X-ray microscopy

    SciTech Connect

    Lian, S.; Yang, H.; Kudo, H.; Momose, A.; Yashiro, W.

    2015-02-15

    The X-ray phase imaging method has been applied to observe soft biological tissues, and it is possible to image the soft tissues by using the benefit of the so-called “Talbot effect” by an X-ray grating. One type of the X-ray phase imaging method was reported by combining an X-ray imaging microscope equipped by a Fresnel zone plate with a phase grating. Using the fringe scanning technique, a high-precision phase shift image could be obtained by displacing the grating step by step and measuring dozens of sample images. The number of the images was selected to reduce the error caused by the non-sinusoidal component of the Talbot self-image at the imaging plane. A larger number suppressed the error more but increased radiation exposure and required higher mechanical stability of equipment. In this paper, we analyze the approximation error of fringe scanning technique for the X-ray microscopy which uses just one grating and proposes an improved algorithm. We compute the approximation error by iteration and substitute that into the process of reconstruction of phase shift. This procedure will suppress the error even with few sample images. The results of simulation experiments show that the precision of phase shift image reconstructed by the proposed algorithm with 4 sample images is almost the same as that reconstructed by the conventional algorithm with 40 sample images. We also have succeeded in the experiment with real data.

  16. Accurate phase measurements for thick spherical objects using optical quadrature microscopy

    NASA Astrophysics Data System (ADS)

    Warger, William C., II; DiMarzio, Charles A.

    2009-02-01

    In vitro fertilization (IVF) procedures have resulted in the birth of over three million babies since 1978. Yet the live birth rate in the United States was only 34% in 2005, with 32% of the successful pregnancies resulting in multiple births. These multiple pregnancies were directly attributed to the transfer of multiple embryos to increase the probability that a single, healthy embryo was included. Current viability markers used for IVF, such as the cell number, symmetry, size, and fragmentation, are analyzed qualitatively with differential interference contrast (DIC) microscopy. However, this method is not ideal for quantitative measures beyond the 8-cell stage of development because the cells overlap and obstruct the view within and below the cluster of cells. We have developed the phase-subtraction cell-counting method that uses the combination of DIC and optical quadrature microscopy (OQM) to count the number of cells accurately in live mouse embryos beyond the 8-cell stage. We have also created a preliminary analysis to measure the cell symmetry, size, and fragmentation quantitatively by analyzing the relative dry mass from the OQM image in conjunction with the phase-subtraction count. In this paper, we will discuss the characterization of OQM with respect to measuring the phase accurately for spherical samples that are much larger than the depth of field. Once fully characterized and verified with human embryos, this methodology could provide the means for a more accurate method to score embryo viability.

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

    DOE PAGESBeta

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

    2016-02-29

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

  18. Nanoimaging and spectroscopic analysis of rubber/ZnO interfaces by energy-filtering transmission electron microscopy.

    PubMed

    Horiuchi, Shin; Dohi, Hidehiko

    2006-05-01

    Energy-filtering transmission electron microscopy (EFTEM) was employed for investigating interactions between rubber and ZnO particles in the accelerated vulcanization process. Combining elemental mapping and electron energy loss spectroscopy (EELS) by EFTEM enabled the characterization of the interfaces with spatial resolutions of less than 10 nm and with high elemental detection sensitivity. We found that a sulfur- and zinc-rich compound was generated around ZnO particles, and that product was then revealed to be ZnS-generated as a byproduct in the accelerated vulcanization process. Through this study, it is indicated that the accelerated vulcanization with ZnO does not occur uniformly in the rubber matrix; it occurs locally around ZnO particles at a higher reaction rate, implying that the rubber network structure is not uniform on the nanoscale. PMID:16649771

  19. Calibration of Two Difrerent Types of Modulators for an Application in Spectroscopic Phase Modulated Ellipsometry

    NASA Astrophysics Data System (ADS)

    Kouko, S. L.; Llinares, C.

    1995-08-01

    In order to choose a photoelastic modulator for an application in spectroscopic phase modulated ellipsometry a complete calibration of two different types of photoelastic modulators is achieved. First the model that describes the behavior of each of them is accurately determined since the calibration procedure depends on it. Both modulators behave as a static strain model with a phase shift of the form δ = δ_0 + {\\cal A}sin ω t. Using the suitable procedures, the driving voltage V_mod and the static strain δ_0 of both devices are accurately determined as a function of the wavelength from 0.25 μm to 0.75 μm. A method to reduce the errors due to incorrect settings of the modulation voltage and the static birefringence is also proposed. An accuracy check of the calibration done by comparing the indexes of refraction of two silica prisms obtained with our ellipsometer and with the high precision goniometer method shows a very good agreement. Dans le but de choisir un modulateur photoélastique pour une application en ellipsométrie spectroscopique à modulation de phase, le calibrage de deux modulateurs a été réalisé. Dans un premier temps, le modèle décrivant chacun des modulateurs a été déterminé avec précision vu que la procédure de calibrage dépend de celui-ci : les deux modulateurs fonctionnent suivant le modèle avec biréfringence statique ayant un déphasage de la forme δ = δ_0 + {\\cal A}sin ω t. En utilisant les procédures de calibrage appropriées, la tension de pilotage V_mod et la biréfringence statique δ_0 ont été déterminées avec précision en fonction de la longueur d'onde dans la gamme spectrale s'étendant de 0,25 μm à 0,75 μm. Une méthode pour réduire les erreurs dues au calibrage de la tension de modulation et à la biréfringence résiduelle est également proposée. Un test de la précision du calibrage fait en comparant les indices de réfraction de deux prismes de silice obtenus avec notre ellipsomètre et avec

  20. Nanosecond switching in GeSe phase change memory films by atomic force microscopy

    SciTech Connect

    Bosse, James L.; Huey, Bryan D.; Grishin, Ilya; Kolosov, Oleg V.; Gyu Choi, Yong; Cheong, Byung-ki; Lee, Suyoun

    2014-02-03

    Nanosecond scale threshold switching is investigated with conducting atomic force microscopy (AFM) for an amorphous GeSe film. Switched bits exhibit 2–3 orders of magnitude variations in conductivity, as demonstrated in phase change based memory devices. Through the nm-scale AFM probe, this crystallization was achieved with pulse durations of as low as 15 ns, the fastest reported with scanning probe based methods. Conductance AFM imaging of the switched bits further reveals correlations between the switched volume, pulse amplitude, and pulse duration. The influence of film heterogeneities on switching is also directly detected, which is of tremendous importance for optimal device performance.

  1. Quantitative phase and refractive index measurements with point-source digital in-line holographic microscopy.

    PubMed

    Jericho, M H; Kreuzer, H J; Kanka, M; Riesenberg, R

    2012-04-01

    Point-source digital in-line holographic microscopy with numerical reconstruction is ideally suited for quantitative phase measurements to determine optical path lengths and to extract changes in refractive index within accuracy close to 0.001 on the submicrometer length scale. This is demonstrated with simulated holograms and with detailed measurements on a number of different micrometer-sized samples such as suspended drops, optical fibers, as well as organisms of biological interest such as E. coli bacteria, HeLa cells, and fibroblast cells.

  2. Spatially resolved quantitative mapping of thermomechanical properties and phase transition temperatures using scanning probe microscopy

    DOEpatents

    Jesse, Stephen; Kalinin, Sergei V; Nikiforov, Maxim P

    2013-07-09

    An approach for the thermomechanical characterization of phase transitions in polymeric materials (polyethyleneterephthalate) by band excitation acoustic force microscopy is developed. This methodology allows the independent measurement of resonance frequency, Q factor, and oscillation amplitude of a tip-surface contact area as a function of tip temperature, from which the thermal evolution of tip-surface spring constant and mechanical dissipation can be extracted. A heating protocol maintained a constant tip-surface contact area and constant contact force, thereby allowing for reproducible measurements and quantitative extraction of material properties including temperature dependence of indentation-based elastic and loss moduli.

  3. Atomic force microscopy studies of domain structures in phase-separated monolayers

    NASA Astrophysics Data System (ADS)

    Xiao, Shou-Jun; Wu, Hai-Ming; Yang, Xiao-Min; Wei, Yu; Tai, Zi-Hou; Sun, Xing-Zhong

    1994-10-01

    Domain structures were studied with atomic force microscopy (AFM) in binary phase-separated monolayer films composed of 5, 10, 15-triphenyl-20-(4-dl-α-phenylalanylamindo) phenyl porphyrin (TPPP) and one of a series of fatty acids which are arachidic acid (AA), palmitic acid (PA), and lauric acid (LA). The liquid-condensed (LC) domain structures of AA and PA were observed in their corresponding mixed monolayers. However, instead of the fatty acid domain, a liquid-expanded (LE) domain structure of TPPP appears in the mixed monolayer of LA/TPPP.

  4. Practical factors affecting the performance of a thin-film phase plate for transmission electron microscopy

    PubMed Central

    Danev, Radostin; Glaeser, Robert M.; Nagayama, Kuniaki

    2011-01-01

    A number of practical issues must be addressed when using thin carbon films as quarter-wave plates for Zernike phase-contrast electron microscopy. We describe, for example, how we meet the more stringent requirements that must be satisfied for beam alignment in this imaging mode. In addition we address the concern that one might have regarding the loss of some of the scattered electrons as they pass through such a phase plate. We show that two easily measured parameters, (1) the low-resolution image contrast produced in cryo-EM images of tobacco mosaic virus particles and (2) the fall-off of the envelope function at high resolution, can be used to quantitatively compare the data quality for Zernike phase-contrast images and for defocused bright-field images. We describe how we prepare carbon-film phase plates that are initially free of charging or other effects that degrade image quality. We emphasize, however, that even though the buildup of hydrocarbon contamination can be avoided by heating the phase plates during use, their performance nevertheless deteriorates over the time scale of days to weeks, thus requiring their frequent replacement in order to maintain optimal performance. PMID:19157711

  5. Electron microscopy and phase analysis of fly ash from pressurized fluidized bed combustion

    SciTech Connect

    Maenami, Hiroki; Isu, Norifumi; Ishida, Emile H.; Mitsuda, Takeshi

    2004-05-01

    The characterization of the typical fly ashes from pressurized fluidized bed combustion system (PFBC) in Japan and Europe was carried out by electron microscopy and phase analysis using energy-dispersive X-ray spectroscopy (EDX). The purity of limestone as in-bed sulfur removal sorbent influences the desulfurization reaction. The high-purity limestone yielded both hydroxyl ellestadite and anhydrite in Japanese PFBC ashes, while dolomite-rich limestone yielded anhydrite in European PFBC ashes. When the high-purity limestone was used, hydroxyl ellestadite particles were observed as the independent particles or the rim around limestone particles. The Al{sub 2}O{sub 3} content in the glassy phase was inversely proportional to the CaO content in the glassy phase, suggesting that the glassy phases were formed from metakaoline and calcite as end members. Since hydroxyl ellestadite, glassy phase and metakaoline are reactive under hydrothermal conditions, PFBC ashes are expected to be used as raw materials for autoclaved products.

  6. Spectral domain phase microscopy: a new tool for measuring cellular dynamics and cytoplasmic flow

    NASA Astrophysics Data System (ADS)

    McDowell, Emily J.; Choma, Michael A.; Ellerbee, Audrey K.; Izatt, Joseph A.

    2005-03-01

    Broadband interferometry is an attractive technique for the detection of cellular motions because it provides depth-resolved interferometric phase information via coherence gating. Here a phase sensitive technique called spectral domain phase microscopy (SDPM) is presented. SDPM is a functional extension of spectral domain optical coherence tomography that allows for the detection of cellular motions and dynamics with nanometer-scale sensitivity. This sensitivity is made possible by the inherent phase stability of spectral domain OCT combined with common-path interferometry. The theory that underlies this technique is presented, the sensitivity of the technique is demonstrated by the measurement of the thermal expansion coefficient of borosilicate glass, and the response of an Amoeba proteus to puncture of its cell membrane is measured. We also exploit the phase stability of SDPM to perform Doppler flow imaging of cytoplasmic streaming in A. proteus. We show reversal of cytoplasmic flow in response to stimuli, and we show that the cytoplasmic flow is laminar (i.e. parabolic) in nature. We are currently investigating the use of SDPM in a variety of different cell types.

  7. Coherence-controlled holographic microscopy for live-cell quantitative phase imaging

    NASA Astrophysics Data System (ADS)

    Slabý, TomáÅ.¡; Křížová, Aneta; Lošt'ák, Martin; Čolláková, Jana; Jůzová, Veronika; Veselý, Pavel; Chmelík, Radim

    2015-03-01

    In this paper we present coherence-controlled holographic microscopy (CCHM) and various examples of observations of living cells including combination of CCHM with fluorescence microscopy. CCHM is a novel technique of quantitative phase imaging (QPI). It is based on grating off-axis interferometer, which is fully adapted for the use of incoherent illumination. This enables high-quality QPI free from speckles and parasitic interferences and lateral resolution of classical widefield microscopes. Label-free nature of QPI makes CCHM a useful tool for long-term observations of living cells. Moreover, coherence-gating effect induced by the use of incoherent illumination enables QPI of cells even in scattering media. Combination of CCHM with common imaging techniques brings the possibility to exploit advantages of QPI while simultaneously identifying the observed structures or processes by well-established imaging methods. We used CCHM for investigation of general parameters of cell life cycles and for research of cells reactions to different treatment. Cells were also visualized in 3D collagen gel with the use of CCHM. It was found that both the cell activity and movement of the collagen fibers can be registered. The method of CCHM in combination with fluorescence microscopy was used in order to obtain complementary information about cell morphology and identify typical morphological changes associated with different types of cell death. This combination of CCHM with common imaging technique has a potential to provide new knowledge about various processes and simultaneously their confirmation by comparison with known imaging method.

  8. Label-free imaging of developing vasculature in zebrafish with phase variance optical coherence microscopy

    NASA Astrophysics Data System (ADS)

    Chen, Yu; Fingler, Jeff; Trinh, Le A.; Fraser, Scott E.

    2016-03-01

    A phase variance optical coherence microscope (pvOCM) has been created to visualize blood flow in the vasculature of zebrafish embryos, without using exogenous labels. The pvOCM imaging system has axial and lateral resolutions of 2 μm in tissue, and imaging depth of more than 100 μm. Imaging of 2-5 days post-fertilization zebrafish embryos identified the detailed structures of somites, spinal cord, gut and notochord based on intensity contrast. Visualization of the blood flow in the aorta, veins and intersegmental vessels was achieved with phase variance contrast. The pvOCM vasculature images were confirmed with corresponding fluorescence microscopy of a zebrafish transgene that labels the vasculature with green fluorescent protein. The pvOCM images also revealed functional information of the blood flow activities that is crucial for the study of vascular development.

  9. New approaches for the analysis of confluent cell layers with quantitative phase digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Pohl, L.; Kaiser, M.; Ketelhut, S.; Pereira, S.; Goycoolea, F.; Kemper, Björn

    2016-03-01

    Digital holographic microscopy (DHM) enables high resolution non-destructive inspection of technical surfaces and minimally-invasive label-free live cell imaging. However, the analysis of confluent cell layers represents a challenge as quantitative DHM phase images in this case do not provide sufficient information for image segmentation, determination of the cellular dry mass or calculation of the cell thickness. We present novel strategies for the analysis of confluent cell layers with quantitative DHM phase contrast utilizing a histogram based-evaluation procedure. The applicability of our approach is illustrated by quantification of drug induced cell morphology changes and it is shown that the method is capable to quantify reliable global morphology changes of confluent cell layers.

  10. In situ high temperature microscopy study of the surface oxidation and phase transformations in titanium alloys.

    PubMed

    Malinov, S; Sha, W; Voon, C S

    2002-09-01

    Two popular commercial titanium alloys, Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo-0.08Si, were used for in situ high temperature microscopy study. The experiments were performed on an optical microscope equipped with high temperature stage using both normal and florescence lights. Two kinds of experiments were performed, at continuous heating/cooling with different rates and in isothermal conditions at different temperatures. The changes taking place on the sample surface during the experiments were monitored. The morphology of the alpha ==> beta ==> alpha phase transformation was recorded at different heat treatment conditions using the effect of thermal etching. An effect of sample surface oxidation and deoxidation was observed during continuous heating. The appearance and disappearance of ordered titanium oxides Ti3O and Ti2O are discussed based on the phase equilibrium diagram. The kinetics of the surface oxidation was monitored in both isothermal and continuous cooling conditions.

  11. Lensless transport-of-intensity phase microscopy and tomography with a color LED matrix

    NASA Astrophysics Data System (ADS)

    Zuo, Chao; Sun, Jiasong; Zhang, Jialin; Hu, Yan; Chen, Qian

    2015-07-01

    We demonstrate lens-less quantitative phase microscopy and diffraction tomography based on a compact on-chip platform, using only a CMOS image sensor and a programmable color LED array. Based on multi-wavelength transport-of- intensity phase retrieval and multi-angle illumination diffraction tomography, this platform offers high quality, depth resolved images with a lateral resolution of ˜3.7μm and an axial resolution of ˜5μm, over wide large imaging FOV of 24mm2. The resolution and FOV can be further improved by using a larger image sensors with small pixels straightforwardly. This compact, low-cost, robust, portable platform with a decent imaging performance may offer a cost-effective tool for telemedicine needs, or for reducing health care costs for point-of-care diagnostics in resource-limited environments.

  12. Fast microstructure and phase analyses of nanopowders using combined analysis of transmission electron microscopy scattering patterns.

    PubMed

    Boullay, P; Lutterotti, L; Chateigner, D; Sicard, L

    2014-09-01

    The full quantitative characterization of nanopowders using transmission electron microscopy scattering patterns is shown. This study demonstrates the feasibility of the application of so-called combined analysis, a global approach for phase identification, structure refinement, characterization of anisotropic crystallite sizes and shapes, texture analysis and texture variations with the probed scale, using electron diffraction patterns of TiO2 and Mn3O4 nanocrystal aggregates and platinum films. Electron diffraction pattern misalignments, positioning, and slight changes from pattern to pattern are directly integrated and refined within this approach. The use of a newly developed full-pattern search-match methodology for phase identification of nanopowders and the incorporation of the two-wave dynamical correction for diffraction patterns are also reported and proved to be efficient. PMID:25176993

  13. Fast microstructure and phase analyses of nanopowders using combined analysis of transmission electron microscopy scattering patterns.

    PubMed

    Boullay, P; Lutterotti, L; Chateigner, D; Sicard, L

    2014-09-01

    The full quantitative characterization of nanopowders using transmission electron microscopy scattering patterns is shown. This study demonstrates the feasibility of the application of so-called combined analysis, a global approach for phase identification, structure refinement, characterization of anisotropic crystallite sizes and shapes, texture analysis and texture variations with the probed scale, using electron diffraction patterns of TiO2 and Mn3O4 nanocrystal aggregates and platinum films. Electron diffraction pattern misalignments, positioning, and slight changes from pattern to pattern are directly integrated and refined within this approach. The use of a newly developed full-pattern search-match methodology for phase identification of nanopowders and the incorporation of the two-wave dynamical correction for diffraction patterns are also reported and proved to be efficient.

  14. Studies on the interaction of heparin with lysozyme by multi-spectroscopic techniques and atomic force microscopy.

    PubMed

    Tian, Lunfu; Hu, Xiaoli; Liu, Zhongfang; Liu, Shaopu

    2016-02-01

    The interaction between heparin (Hep) and lysozyme (Lyso) in vitro was studied by fluorescence, UV-vis, circular dichroism (CD), resonance Rayleigh scattering (RRS) spectroscopy and atomic force microscopy (AFM) under normal physiological conditions. UV-vis spectra of Lyso showed the absorbance was significantly increased with the addition of Hep. Fluorescence studies revealed that the emission quenching of Lyso with Hep was initiated by static quenching mechanism. CD spectral studies showed that Hep induced conformational changes in the secondary structure of Lyso. RRS spectra of Lyso showed the intensity of scattering was significantly increased with the addition of Hep and the enhanced RRS intensities were proportional to the concentration of Hep in a certain range. Thus, a new RRS method using Lyso as a probe could be used for the determination of Hep. The detection limit for Hep was 3.9 ng mL(-1). In addition, the shape of the complex was characterized by AFM. The possible reaction mechanism and the reasons for the enhancement of RRS intensity had been discussed through experimental results.

  15. Investigation of the Interaction between Patulin and Human Serum Albumin by a Spectroscopic Method, Atomic Force Microscopy, and Molecular Modeling

    PubMed Central

    Yuqin, Li; Guirong, You; Zhen, Yang; Caihong, Liu; Baoxiu, Jia; Jiao, Chen; Yurong, Guo

    2014-01-01

    The interaction of patulin with human serum albumin (HSA) was studied in vitro under normal physiological conditions. The study was performed using fluorescence, ultraviolet-visible spectroscopy (UV-Vis), circular dichroism (CD), atomic force microscopy (AFM), and molecular modeling techniques. The quenching mechanism was investigated using the association constants, the number of binding sites, and basic thermodynamic parameters. A dynamic quenching mechanism occurred between HSA and patulin, and the binding constants (K) were 2.60 × 104, 4.59 × 104, and 7.01 × 104 M−1 at 288, 300, and 310 K, respectively. Based on fluorescence resonance energy transfer, the distance between the HSA and patulin was determined to be 2.847 nm. The ΔG0, ΔH0, and ΔS0 values across various temperatures indicated that hydrophobic interaction was the predominant binding force. The UV-Vis and CD results confirmed that the secondary structure of HSA was altered in the presence of patulin. The AFM results revealed that the individual HSA molecule dimensions were larger after interaction with patulin. In addition, molecular modeling showed that the patulin-HSA complex was stabilized by hydrophobic and hydrogen bond forces. The study results suggested that a weak intermolecular interaction occurred between patulin and HSA. Overall, the results are potentially useful for elucidating the toxigenicity of patulin when it is combined with the biomolecular function effect, transmembrane transport, toxicological, testing and other experiments. PMID:25110690

  16. Au Colloids Formed by Ion Implantation in Muscovite Mica Studied by Vibrational and Electronic Spectroscopes and Atomic Force Microscopy

    NASA Technical Reports Server (NTRS)

    Tung, Y. S.; Henderson, D. O.; Mu, R.; Ueda, A.; Collins, W. E.; White, C. W.; Zuhr, R. A.; Zhu, Jane G.

    1997-01-01

    Au was implanted into the (001) surface of Muscovite mica at an energy of 1.1 MeV and at doses of 1, 3, 6, and 10 x 10(exp 16) ions/cu cm. Optical spectra of the as-implanted samples revealed a peak at 2.28 eV (545 nm) which is attributed to the surface plasmon absorption of Au colloids. The infrared reflectance measurements show a decreasing reflectivity with increasing ion dose in the Si-O stretching region (900-1200 /cm). A new peak observed at 967 /cm increases with the ion dose and is assigned to an Si-O dangling bond. Atomic force microscopy images of freshly cleaved samples implanted with 6 and 10 x 10(exp 16) ions/sq cm indicated metal colloids with diameters between 0.9- 1.5 nm. AFM images of the annealed samples showed irregularly shaped structures with a topology that results from the fusion of smaller colloids.

  17. Studies on the interaction of heparin with lysozyme by multi-spectroscopic techniques and atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Tian, Lunfu; Hu, Xiaoli; Liu, Zhongfang; Liu, Shaopu

    2016-02-01

    The interaction between heparin (Hep) and lysozyme (Lyso) in vitro was studied by fluorescence, UV-vis, circular dichroism (CD), resonance Rayleigh scattering (RRS) spectroscopy and atomic force microscopy (AFM) under normal physiological conditions. UV-vis spectra of Lyso showed the absorbance was significantly increased with the addition of Hep. Fluorescence studies revealed that the emission quenching of Lyso with Hep was initiated by static quenching mechanism. CD spectral studies showed that Hep induced conformational changes in the secondary structure of Lyso. RRS spectra of Lyso showed the intensity of scattering was significantly increased with the addition of Hep and the enhanced RRS intensities were proportional to the concentration of Hep in a certain range. Thus, a new RRS method using Lyso as a probe could be used for the determination of Hep. The detection limit for Hep was 3.9 ng mL- 1. In addition, the shape of the complex was characterized by AFM. The possible reaction mechanism and the reasons for the enhancement of RRS intensity had been discussed through experimental results.

  18. Dual-modality wide-field photothermal quantitative phase microscopy and depletion of cell populations

    NASA Astrophysics Data System (ADS)

    Turko, Nir A.; Barnea, Itay; Blum, Omry; Korenstein, Rafi; Shaked, Natan T.

    2015-03-01

    We review our dual-modality technique for quantitative imaging and selective depletion of populations of cells based on wide-field photothermal (PT) quantitative phase imaging and simultaneous PT cell extermination. The cells are first labeled by plasmonic gold nanoparticles, which evoke local plasmonic resonance when illuminated by light in a wavelength corresponding to their specific plasmonic resonance peak. This reaction creates changes of temperature, resulting in changes of phase. This phase changes are recorded by a quantitative phase microscope (QPM), producing specific imaging contrast, and enabling bio-labeling in phase microscopy. Using this technique, we have shown discrimination of EGFR over-expressing (EGFR+) cancer cells from EGFR under-expressing (EGFR-) cancer cells. Then, we have increased the excitation power in order to evoke greater temperatures, which caused specific cell death, all under real-time phase acquisition using QPM. Close to 100% of all EGFR+ cells were immediately exterminated when illuminated with the strong excitation beam, while all EGFR- cells survived. For the second experiment, in order to simulate a condition where circulating tumor cells (CTCs) are present in blood, we have mixed the EGFR+ cancer cells with white blood cells (WBCs) from a healthy donor. Here too, we have used QPM to observe and record the phase of the cells as they were excited for selective visualization and then exterminated. The WBCs survival rate was over 95%, while the EGFR+ survival rate was under 5%. The technique may be the basis for real-time detection and controlled treatment of CTCs.

  19. Real time quantitative phase microscopy based on single-shot transport of intensity equation (ssTIE) method

    NASA Astrophysics Data System (ADS)

    Yu, Wei; Tian, Xiaolin; He, Xiaoliang; Song, Xiaojun; Xue, Liang; Liu, Cheng; Wang, Shouyu

    2016-08-01

    Microscopy based on transport of intensity equation provides quantitative phase distributions which opens another perspective for cellular observations. However, it requires multi-focal image capturing while mechanical and electrical scanning limits its real time capacity in sample detections. Here, in order to break through this restriction, real time quantitative phase microscopy based on single-shot transport of the intensity equation method is proposed. A programmed phase mask is designed to realize simultaneous multi-focal image recording without any scanning; thus, phase distributions can be quantitatively retrieved in real time. It is believed the proposed method can be potentially applied in various biological and medical applications, especially for live cell imaging.

  20. Broadband quantitative phase microscopy with extended field of view using off-axis interferometric multiplexing.

    PubMed

    Girshovitz, Pinhas; Frenklach, Irena; Shaked, Natan T

    2015-11-01

    We propose a new portable imaging configuration that can double the field of view (FOV) of existing off-axis interferometric imaging setups, including broadband off-axis interferometers. This configuration is attached at the output port of the off-axis interferometer and optically creates a multiplexed interferogram on the digital camera, which is composed of two off-axis interferograms with straight fringes at orthogonal directions. Each of these interferograms contains a different FOV of the imaged sample. Due to the separation of these two FOVs in the spatial-frequency domain, they can be fully reconstructed separately, while obtaining two complex wavefronts from the sample at once. Since the optically multiplexed off-axis interferogram is recorded by the camera in a single exposure, fast dynamics can be recorded with a doubled imaging area. We used this technique for quantitative phase microscopy of biological samples with extended FOV. We demonstrate attaching the proposed module to a diffractive phase microscopy interferometer, illuminated by a broadband light source. The biological samples used for the experimental demonstrations include microscopic diatom shells, cancer cells, and flowing blood cells. PMID:26440914

  1. Cell cycle phase classification in 3D in vivo microscopy of Drosophila embryogenesis

    PubMed Central

    2011-01-01

    Background Cell divisions play critical roles in disease and development. The analysis of cell division phenotypes in high content image-based screening and time-lapse microscopy relies on automated nuclear segmentation and classification of cell cycle phases. Automated identification of the cell cycle phase helps biologists quantify the effect of genetic perturbations and drug treatments. Most existing studies have dealt with 2D images of cultured cells. Few, if any, studies have addressed the problem of cell cycle classification in 3D image stacks of intact tissues. Results We developed a workflow for the automated cell cycle phase classification in 3D time-series image datasets of live Drosophila embryos expressing the chromatin marker histone-GFP. Upon image acquisition by laser scanning confocal microscopy and 3D nuclear segmentation, we extracted 3D intensity, shape and texture features from interphase nuclei and mitotic chromosomes. We trained different classifiers, including support vector machines (SVM) and neural networks, to distinguish between 5 cell cycles phases (Interphase and 4 mitotic phases) and achieved over 90% accuracy. As the different phases occur at different frequencies (58% of samples correspond to interphase), we devised a strategy to improve the identification of classes with low representation. To investigate which features are required for accurate classification, we performed feature reduction and selection. We were able to reduce the feature set from 42 to 9 without affecting classifier performance. We observed a dramatic decrease of classification performance when the training and testing samples were derived from two different developmental stages, the nuclear divisions of the syncytial blastoderm and the cell divisions during gastrulation. Combining samples from both developmental stages produced a more robust and accurate classifier. Conclusions Our study demonstrates that automated cell cycle phase classification, besides 2D

  2. Determination of the misalignment error of a compound zero-order waveplate using the spectroscopic phase shifting method

    NASA Astrophysics Data System (ADS)

    Zheng, Quan; Han, Zhigang; Chen, Lei

    2016-09-01

    The spectroscopic phase shifting method was proposed to determine the misalignment error of a compound zero-order waveplate. The waveplate, which is composed of two separate multi-order quartz waveplates, was measured by a polarizer-waveplate-analyser setup with a spectrometer as the detector. The theoretical relationship between the misalignment error and the azimuth of the polarized light that emerged from the waveplate was studied by comparing two forms of the Jones matrix of the waveplate. Four spectra were obtained to determine the wavelength-dependent azimuth using a phase shifting algorithm when the waveplate was rotated to four detection angles. The misalignment error was ultimately solved from the wavelength-dependent azimuth by the Levenberg-Marquardt method. Experiments were conducted at six misalignment angles. The measured results of the misalignment angle agree well with their nominal values, indicating that the spectroscopic phase shifting method can be a reliable way to measure the misalignment error of a compound zero-order waveplate.

  3. Spectroscopic Characterization and Reactivity of Triplet and Quintet Iron(IV) Oxo Complexes in the Gas Phase

    PubMed Central

    Andris, Erik; Jašík, Juraj; Gómez, Laura

    2016-01-01

    Abstract Closely structurally related triplet and quintet iron(IV) oxo complexes with a tetradentate aminopyridine ligand were generated in the gas phase, spectroscopically characterized, and their reactivities in hydrogen‐transfer and oxygen‐transfer reactions were compared. The spin states were unambiguously assigned based on helium tagging infrared photodissociation (IRPD) spectra of the mass‐selected iron complexes. It is shown that the stretching vibrations of the nitrate counterion can be used as a spectral marker of the central iron spin state. PMID:26878833

  4. Multinuclear NMR microscopy of two-phase fluid systems in porous rock.

    PubMed

    Doughty, D A; Tomutsa, L

    1996-01-01

    The high-field magnetic resonance (MR) characteristics of fluids in porous reservoir rock exhibit short T2 relaxation times and broad natural line widths. These characteristics severely restrict which MR imaging (MRI) methodology can be used to obtain high-resolution porescale images of fluids in porous rock. An MR microscopy protocol based on 3D backprojection using strong imaging gradients was developed to overcome many of these constraints. To improve the image quality of two-phase systems, multinuclear MRI using proton MR to image the brine phase and 19F MR of a fluorinated hydrocarbon to image the oil phase was used. Resolution as high as 25 microns per pixel has been obtained for fluid systems in Bentheim and Fontainebleau sandstones. Separate proton and 19F images of brine and oil phases show good agreement with total saturation images. Software has been developed to perform 3D erosion/dilations and to extract the pore size distribution from binarized 3D images of fluid filled porosity. Results from pore size measurements show significant differences in the nature of the pore network in Fontainebleau and Bentheim sandstones. PMID:8970097

  5. Atomic force microscopy reveals two phases in single stranded DNA self-assembled monolayers.

    PubMed

    Kosaka, Priscila M; González, Sheila; Domínguez, Carmen M; Cebollada, Alfonso; San Paulo, Alvaro; Calleja, Montserrat; Tamayo, Javier

    2013-08-21

    We have investigated the structure of single-stranded (ss) DNA self-assembled monolayers (SAMs) on gold by combining peak force tapping, Kelvin probe and phase contrast atomic force microscopy (AFM) techniques. The adhesion, surface potential and phase shift signals show heterogeneities in the DNA film structure at two levels: microscale and nanoscale; which cannot be clearly discerned in the topography. Firstly, there is multilayer aggregation covering less than 5% of the surface. The DNA multilayers seem to be ordered phases and their existence suggests that DNA end-to-end interaction can play a role in the self-assembly process. Secondly, we find the formation of two phases in the DNA monolayer, which differ both in surface energy and surface potential. We relate the two domains to differences in the packing density and in the ssDNA conformation. The discovered heterogeneities in ssDNA SAMs provide a new scenario in our vision of these relevant films that have direct consequences on their biological, chemical and physical properties. PMID:23832284

  6. Atomic force microscopy reveals two phases in single stranded DNA self-assembled monolayers.

    PubMed

    Kosaka, Priscila M; González, Sheila; Domínguez, Carmen M; Cebollada, Alfonso; San Paulo, Alvaro; Calleja, Montserrat; Tamayo, Javier

    2013-08-21

    We have investigated the structure of single-stranded (ss) DNA self-assembled monolayers (SAMs) on gold by combining peak force tapping, Kelvin probe and phase contrast atomic force microscopy (AFM) techniques. The adhesion, surface potential and phase shift signals show heterogeneities in the DNA film structure at two levels: microscale and nanoscale; which cannot be clearly discerned in the topography. Firstly, there is multilayer aggregation covering less than 5% of the surface. The DNA multilayers seem to be ordered phases and their existence suggests that DNA end-to-end interaction can play a role in the self-assembly process. Secondly, we find the formation of two phases in the DNA monolayer, which differ both in surface energy and surface potential. We relate the two domains to differences in the packing density and in the ssDNA conformation. The discovered heterogeneities in ssDNA SAMs provide a new scenario in our vision of these relevant films that have direct consequences on their biological, chemical and physical properties.

  7. Sinter-free phase conversion and scanning transmission electron microscopy of FePt nanoparticle monolayers.

    PubMed

    Johnston-Peck, Aaron C; Scarel, Giovanna; Wang, Junwei; Parsons, Gregory N; Tracy, Joseph B

    2011-10-01

    Thermally robust monolayers of 4-6 nm diameter FePt nanoparticles (NPs) were fabricated by combining chemical synthesis and atomic layer deposition. Spin-cast monolayers of FePt NPs were coated with thin, 11 nm-thick layers of amorphous Al(2)O(3), followed by annealing to convert the FePt NPs from an alloy (A1) into intermetallic FePt (L1(0)) and FePt(3) (L1(2)) phases. The Al(2)O(3) layer serves as a barrier that prevents sintering between NPs during annealing at temperatures up to 730 °C. Electron and X-ray diffraction in conjunction with high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) show that as-synthesized A1 FePt NPs convert into L1(0) and L1(2) phase NPs through annealing. HAADF-STEM measurements of individual NPs reveal imperfect ordering and show that the NP composition determines which intermetallic phase is obtained. Mixed-phase NPs with L1(0) cores and FePt(3) L1(2) shells were also observed, as well as a smaller number of unconverted A1 NPs. These results highlight the need for improved control over the compositional uniformity of FePt NPs for their use in bit-patterned magnetic recording.

  8. Combined optical coherence phase microscopy and impedance sensing measurements of differentiating adipose derived stem cells

    NASA Astrophysics Data System (ADS)

    Bagnaninchi, P. O.

    2010-02-01

    There is a growing interest in monitoring differentiating stem cells in 2D culture without the use of labelling agents. In this study we explore the feasibility of a multimodality method that combines impedance sensing (IS) and optical coherence phase microscopy (OCPM) to monitor the main biological events associated with adipose derived stem cells differentiation into different lineages. Adipose derived stem cells were cultured in Mesenpro RS medium on gold electrode arrays. The system (ECIS, Applied biophysics) is connected to a lock-in amplifier controlled by a computer, and the complex impedance is derived from the in phase and out of phase voltages. Multi-frequency measurements spanning from 500Hz to 100 kHz are recorded every 2 minutes. The Optical coherence phase microscope is build around a Thorlabs engine (930nm FWHM: 90nm) and connected to a custom build microscope probe. The IS and OCPM were successfully integrated. The electrode area (250um) was imaged with a lateral resolution of 1.5um during impedance measurements. Impedance sensing gave an average measurement of differentiation, as a change in impedance over the electrode area, whereas OCPM provides additional information on the cellular events occurring on top of the electrode. The information retrieved from OCPM will feed a mathematical model correlating cellular differentiation and impedance variation. In this study we have demonstrated the feasibility of integrating two non-invasive monitoring techniques that will be instrumental in designing stem cell based screening assays.

  9. Phase-transition thresholds and vaporization phenomena for ultrasound phase-change nanoemulsions assessed via high-speed optical microscopy.

    PubMed

    Sheeran, Paul S; Matsunaga, Terry O; Dayton, Paul A

    2013-07-01

    Ultrasonically activated phase-change contrast agents (PCCAs) based on perfluorocarbon droplets have been proposed for a variety of therapeutic and diagnostic clinical applications. When generated at the nanoscale, droplets may be small enough to exit the vascular space and then be induced to vaporize with high spatial and temporal specificity by externally-applied ultrasound. The use of acoustical techniques for optimizing ultrasound parameters for given applications can be a significant challenge for nanoscale PCCAs due to the contributions of larger outlier droplets. Similarly, optical techniques can be a challenge due to the sub-micron size of nanodroplet agents and resolution limits of optical microscopy. In this study, an optical method for determining activation thresholds of nanoscale emulsions based on the in vitro distribution of bubbles resulting from vaporization of PCCAs after single, short (<10 cycles) ultrasound pulses is evaluated. Through ultra-high-speed microscopy it is shown that the bubbles produced early in the pulse from vaporized droplets are strongly affected by subsequent cycles of the vaporization pulse, and these effects increase with pulse length. Results show that decafluorobutane nanoemulsions with peak diameters on the order of 200 nm can be optimally vaporized with short pulses using pressures amenable to clinical diagnostic ultrasound machines. PMID:23760161

  10. Phase states of water near the surface of a polymer membrane. Phase microscopy and luminescence spectroscopy experiments

    SciTech Connect

    Bunkin, N. F.; Gorelik, V. S.; Kozlov, V. A. Shkirin, A. V. Suyazov, N. V.

    2014-11-15

    Phase microscopy is used to show that the refractive index in the near-surface layer of water at the surface of a polymer Nafion membrane increases by a factor of 1.1 as compared to bulk water. Moreover, this layer exhibits birefringence. Experiments on UV irradiation of dry (anhydrous) and water-soaked Nafion are performed in grazing-incidence geometry to study their stimulated luminescence spectra. These spectra are found to be identical in both cases. For dry Nafion, luminescence can only be excited if probing radiation illuminates the polymer surface. The luminescence of water-soaked Nafion can also be excited if the distance between the optical axis and the surface is several hundred micrometers.

  11. Spectroscopic evidence of α-methylbenzyl radical in the gas phase

    NASA Astrophysics Data System (ADS)

    Lee, Gi Woo; Ahn, Hyeon Geun; Kim, Tae Kyu; Lee, Sang Kuk

    2008-11-01

    We report the observation of the spectroscopic evidence of the α-methylbenzyl radical in a corona excited supersonic expansion using a pinhole-type glass nozzle for the first time. The precursors, toluene, ethylbenzene, and isopropylbenzene, seeded in a large amount of inert carrier gas helium, were electrically discharged to produce benzyl-type radicals as a result of the breaking off of a C-H or a C-C bond from the alkyl chain. The vibronic emission spectra, obtained in the visible region from the precursors, were compared to identify the species generated in the corona discharge of the precursors, from which we found the spectroscopic evidence of the α-methylbenzyl radical.

  12. Mössbauer Spectroscopic Investigation of the Metallic Phases in the Almahata Sitta Meteorite (Fragment #051)

    NASA Astrophysics Data System (ADS)

    Abdu, Y. A.; Gismelseed, A. M.; Shaddad, M. H.; Attaelmanan, A. G.

    2016-08-01

    Mössbauer spectroscopy identify the phases in the metal particles of fragment #051 ureilite: kamacite, taenite, cohenite, schreibersite, and a Fe-oxide phase. Results discussed relate to the occurrence of these phases in ureilites and other meteorites.

  13. Concomitant use of polarization and positive phase contrast microscopy for the study of microbial cells.

    PubMed

    Žižka, Zdeněk; Gabriel, Jiří

    2015-11-01

    Polarization and positive phase contrast microscope were concomitantly used in the study of the internal structure of microbial cells. Positive phase contrast allowed us to view even the fine cell structure with a refractive index approaching that of the surrounding environment, e.g., the cytoplasm, and transferred the invisible phase image to a visible amplitude image. With polarization microscopy, crossed polarizing filters together with compensators and a rotary stage showed the birefringence of different cell structures. Material containing algae was collected in ponds in Sýkořice and Zbečno villages (Křivoklát region). The objects were studied in laboratory microscopes LOMO MIN-8 Sankt Petersburg and Polmi A Carl Zeiss Jena fitted with special optics for positive phase contrast, polarizers, analyzers, compensators, rotary stages, and digital SLR camera Nikon D 70 for image capture. Anisotropic granules were found in the cells of flagellates of the order Euglenales, in green algae of the orders Chlorococcales and Chlorellales, and in desmid algae of the order Desmidiales. The cell walls of filamentous algae of the orders Zygnematales and Ulotrichales were found to exhibit significant birefringence; in addition, relatively small amounts of small granules were found in the cytoplasm. A typical shape-related birefringence of the cylindrical walls and the septa between the cells differed in intensity, which was especially apparent when using a Zeiss compensator RI-c during its successive double setting. In conclusion, the anisotropic granules found in the investigated algae mostly showed strong birefringence and varied in number, size, and location of the cells. Representatives of the order Chlorococcales contained the highest number of granules per cell, and the size of these granules was almost double than that of the other monitored microorganisms. Very strong birefringence was exhibited by cell walls of filamentous algae; it differed in the intensity

  14. Towards non-invasive 3D hepatotoxicity assays with optical coherence phase microscopy

    NASA Astrophysics Data System (ADS)

    Nelson, Leonard J.; Koulovasilopoulos, Andreas; Treskes, Philipp; Hayes, Peter C.; Plevris, John N.; Bagnaninchi, Pierre O.

    2015-03-01

    Three-dimensional tissue-engineered models are increasingly recognised as more physiologically-relevant than standard 2D cell culture for pre-clinical drug toxicity testing. However, many types of conventional toxicity assays are incompatible with dense 3D tissues. This study investigated the use of optical coherence phase microscopy (OCPM) as a novel approach to assess cell death in 3D tissue culture. For 3D micro-spheroid formation Human hepatic C3A cells were encapsulated in hyaluronic acid gels and cultured in 100μl MEME/10%FBS in 96-well plates. After spheroid formation the 3D liver constructs were exposed to acetaminophen on culture day 8. Acetaminophen hepatotoxicity in 3D cultures was evaluated using standard biochemical assays. An inverted OCPM in common path configuration was developed with a Callisto OCT engine (Thorlabs), centred at 930nm and a custom scanning head. Intensity data were used to perform in-depth microstructural imaging. In addition, phase fluctuations were measured by collecting several successive B scans at the same location, and statistics on the first time derivative of the phase, i.e. time fluctuations, were analysed over the acquisition time interval to retrieve overall cell viability. OCPM intensity (cell cluster size) and phase fluctuation statistics were directly compared with biochemical assays. In this study, we investigated optical coherence phase tomography to assess cell death in a 3d liver model after exposure to a prototypical hepatotoxin, acetaminophen. We showed that OCPM has the potential to assess noninvasively and label-free drug toxicity in 3D tissue models.

  15. Video-rate processing in tomographic phase microscopy of biological cells using CUDA.

    PubMed

    Dardikman, Gili; Habaza, Mor; Waller, Laura; Shaked, Natan T

    2016-05-30

    We suggest a new implementation for rapid reconstruction of three-dimensional (3-D) refractive index (RI) maps of biological cells acquired by tomographic phase microscopy (TPM). The TPM computational reconstruction process is extremely time consuming, making the analysis of large data sets unreasonably slow and the real-time 3-D visualization of the results impossible. Our implementation uses new phase extraction, phase unwrapping and Fourier slice algorithms, suitable for efficient CPU or GPU implementations. The experimental setup includes an external off-axis interferometric module connected to an inverted microscope illuminated coherently. We used single cell rotation by micro-manipulation to obtain interferometric projections from 73 viewing angles over a 180° angular range. Our parallel algorithms were implemented using Nvidia's CUDA C platform, running on Nvidia's Tesla K20c GPU. This implementation yields, for the first time to our knowledge, a 3-D reconstruction rate higher than video rate of 25 frames per second for 256 × 256-pixel interferograms with 73 different projection angles (64 × 64 × 64 output). This allows us to calculate additional cellular parameters, while still processing faster than video rate. This technique is expected to find uses for real-time 3-D cell visualization and processing, while yielding fast feedback for medical diagnosis and cell sorting. PMID:27410107

  16. High throughput imaging of blood smears using white light diffraction phase microscopy

    NASA Astrophysics Data System (ADS)

    Majeed, Hassaan; Kandel, Mikhail E.; Bhaduri, Basanta; Han, Kevin; Luo, Zelun; Tangella, Krishnarao; Popescu, Gabriel

    2015-03-01

    While automated blood cell counters have made great progress in detecting abnormalities in blood, the lack of specificity for a particular disease, limited information on single cell morphology and intrinsic uncertainly due to high throughput in these instruments often necessitates detailed inspection in the form of a peripheral blood smear. Such tests are relatively time consuming and frequently rely on medical professionals tally counting specific cell types. These assays rely on the contrast generated by chemical stains, with the signal intensity strongly related to staining and preparation techniques, frustrating machine learning algorithms that require consistent quantities to denote the features in question. Instead we opt to use quantitative phase imaging, understanding that the resulting image is entirely due to the structure (intrinsic contrast) rather than the complex interplay of stain and sample. We present here our first steps to automate peripheral blood smear scanning, in particular a method to generate the quantitative phase image of an entire blood smear at high throughput using white light diffraction phase microscopy (wDPM), a single shot and common path interferometric imaging technique.

  17. Depth-Encoded Spectral Domain Phase Microscopy for Simultaneous Multi-Site Nanoscale Optical Measurements

    PubMed Central

    Hendargo, Hansford C.; Bower, Bradley A.; Reinstein, Alex S.; Shepherd, Neal; Tao, Yuankai K.; Izatt, Joseph A.

    2011-01-01

    Spectral domain phase microscopy (SDPM) is an extension of spectral domain optical coherence tomography (SDOCT) that exploits the extraordinary phase stability of spectrometer-based systems with common-path geometry to resolve sub-wavelength displacements within a sample volume. This technique has been implemented for high resolution axial displacement and velocity measurements in biological samples, but since axial displacement information is acquired serially along the lateral dimension, it has been unable to measure fast temporal dynamics in extended samples. Depth-Encoded SDPM (DESDPM) uses multiple sample arms with unevenly spaced common path reference reflectors to multiplex independent SDPM signals from separate lateral positions on a sample simultaneously using a single interferometer, thereby reducing the time required to detect unique optical events to the integration period of the detector. Here, we introduce DESDPM and demonstrate the ability to acquire useful phase data concurrently at two laterally separated locations in a phantom sample as well as a biological preparation of spontaneously beating chick cardiomyocytes. DESDPM may be a useful tool for imaging fast cellular phenomena such as nervous conduction velocity or contractile motion. PMID:21886940

  18. Depth-Encoded Spectral Domain Phase Microscopy for Simultaneous Multi-Site Nanoscale Optical Measurements.

    PubMed

    Hendargo, Hansford C; Bower, Bradley A; Reinstein, Alex S; Shepherd, Neal; Tao, Yuankai K; Izatt, Joseph A

    2011-09-01

    Spectral domain phase microscopy (SDPM) is an extension of spectral domain optical coherence tomography (SDOCT) that exploits the extraordinary phase stability of spectrometer-based systems with common-path geometry to resolve sub-wavelength displacements within a sample volume. This technique has been implemented for high resolution axial displacement and velocity measurements in biological samples, but since axial displacement information is acquired serially along the lateral dimension, it has been unable to measure fast temporal dynamics in extended samples. Depth-Encoded SDPM (DESDPM) uses multiple sample arms with unevenly spaced common path reference reflectors to multiplex independent SDPM signals from separate lateral positions on a sample simultaneously using a single interferometer, thereby reducing the time required to detect unique optical events to the integration period of the detector. Here, we introduce DESDPM and demonstrate the ability to acquire useful phase data concurrently at two laterally separated locations in a phantom sample as well as a biological preparation of spontaneously beating chick cardiomyocytes. DESDPM may be a useful tool for imaging fast cellular phenomena such as nervous conduction velocity or contractile motion.

  19. Atomic force microscopy study of laser induced phase transitions in Ge2Sb2Te5

    NASA Astrophysics Data System (ADS)

    Weidenhof, V.; Friedrich, I.; Ziegler, S.; Wuttig, M.

    1999-11-01

    Micron- and submicron-size changes induced by local laser heating in thin films of Ge2Sb2Te5 are studied by atomic force microscopy (AFM). This material is presently used for rewritable data storage that employs phase change recording. Reversible switching between the amorphous and crystalline states, which is accompanied by a considerable change in optical properties and film density, is exploited to store bits of information. The density change can be detected by AFM, which we use here to study the amorphization (writing) and recrystallization (erasure) of single bits. Both processes have been measured as a function of modification pulse power and duration. Morphology changes can be detected even if the phase change film is covered by a thin protective layer. AFM allows a precise determination of the bit size and bit depth, which characterizes the progress of the phase change in the direction of the surface normal. The present setup allows the correlation of the change in optical reflectance ΔR caused by a specific laser pulse to the bit topography. This enables a detailed study of the mechanisms of bit writing and erasure.

  20. Evaluation of Chemical Interactions between Small Molecules in the Gas Phase Using Chemical Force Microscopy

    PubMed Central

    Lee, Jieun; Ju, Soomi; Kim, In Tae; Jung, Sun-Hwa; Min, Sun-Joon; Kim, Chulki; Sim, Sang Jun; Kim, Sang Kyung

    2015-01-01

    Chemical force microscopy analyzes the interactions between various chemical/biochemical moieties in situ. In this work we examined force-distance curves and lateral force to measure the interaction between modified AFM tips and differently functionalized molecular monolayers. Especially for the measurements in gas phase, we investigated the effect of humidity on the analysis of force-distance curves and the images in lateral force mode. Flat chemical patterns composed of different functional groups were made through micro-contact printing and lateral force mode provided more resolved analysis of the chemical patterns. From the images of 1-octadecanethiol/11-mercapto-1-undecanoic acid patterns, the amine group functionalized tip brought out higher contrast of the patterns than an intact silicon nitride tip owing to the additional chemical interaction between carboxyl and amine groups. For more complex chemical interactions, relative chemical affinities toward specific peptides were assessed on the pattern of 1-octadecanethiol/phenyl-terminated alkanethiol. The lateral image of chemical force microscopy reflected specific preference of a peptide to phenyl group as well as the hydrophobic interaction. PMID:26690165

  1. Multifocus microscopy with precise color multi-phase diffractive optics applied in functional neuronal imaging.

    PubMed

    Abrahamsson, Sara; Ilic, Rob; Wisniewski, Jan; Mehl, Brian; Yu, Liya; Chen, Lei; Davanco, Marcelo; Oudjedi, Laura; Fiche, Jean-Bernard; Hajj, Bassam; Jin, Xin; Pulupa, Joan; Cho, Christine; Mir, Mustafa; El Beheiry, Mohamed; Darzacq, Xavier; Nollmann, Marcelo; Dahan, Maxime; Wu, Carl; Lionnet, Timothée; Liddle, J Alexander; Bargmann, Cornelia I

    2016-03-01

    Multifocus microscopy (MFM) allows high-resolution instantaneous three-dimensional (3D) imaging and has been applied to study biological specimens ranging from single molecules inside cells nuclei to entire embryos. We here describe pattern designs and nanofabrication methods for diffractive optics that optimize the light-efficiency of the central optical component of MFM: the diffractive multifocus grating (MFG). We also implement a "precise color" MFM layout with MFGs tailored to individual fluorophores in separate optical arms. The reported advancements enable faster and brighter volumetric time-lapse imaging of biological samples. In live microscopy applications, photon budget is a critical parameter and light-efficiency must be optimized to obtain the fastest possible frame rate while minimizing photodamage. We provide comprehensive descriptions and code for designing diffractive optical devices, and a detailed methods description for nanofabrication of devices. Theoretical efficiencies of reported designs is ≈90% and we have obtained efficiencies of > 80% in MFGs of our own manufacture. We demonstrate the performance of a multi-phase MFG in 3D functional neuronal imaging in living C. elegans. PMID:27231594

  2. Multifocus microscopy with precise color multi-phase diffractive optics applied in functional neuronal imaging

    PubMed Central

    Abrahamsson, Sara; Ilic, Rob; Wisniewski, Jan; Mehl, Brian; Yu, Liya; Chen, Lei; Davanco, Marcelo; Oudjedi, Laura; Fiche, Jean-Bernard; Hajj, Bassam; Jin, Xin; Pulupa, Joan; Cho, Christine; Mir, Mustafa; El Beheiry, Mohamed; Darzacq, Xavier; Nollmann, Marcelo; Dahan, Maxime; Wu, Carl; Lionnet, Timothée; Liddle, J. Alexander; Bargmann, Cornelia I.

    2016-01-01

    Multifocus microscopy (MFM) allows high-resolution instantaneous three-dimensional (3D) imaging and has been applied to study biological specimens ranging from single molecules inside cells nuclei to entire embryos. We here describe pattern designs and nanofabrication methods for diffractive optics that optimize the light-efficiency of the central optical component of MFM: the diffractive multifocus grating (MFG). We also implement a “precise color” MFM layout with MFGs tailored to individual fluorophores in separate optical arms. The reported advancements enable faster and brighter volumetric time-lapse imaging of biological samples. In live microscopy applications, photon budget is a critical parameter and light-efficiency must be optimized to obtain the fastest possible frame rate while minimizing photodamage. We provide comprehensive descriptions and code for designing diffractive optical devices, and a detailed methods description for nanofabrication of devices. Theoretical efficiencies of reported designs is ≈90% and we have obtained efficiencies of > 80% in MFGs of our own manufacture. We demonstrate the performance of a multi-phase MFG in 3D functional neuronal imaging in living C. elegans. PMID:27231594

  3. Multifocus microscopy with precise color multi-phase diffractive optics applied in functional neuronal imaging.

    PubMed

    Abrahamsson, Sara; Ilic, Rob; Wisniewski, Jan; Mehl, Brian; Yu, Liya; Chen, Lei; Davanco, Marcelo; Oudjedi, Laura; Fiche, Jean-Bernard; Hajj, Bassam; Jin, Xin; Pulupa, Joan; Cho, Christine; Mir, Mustafa; El Beheiry, Mohamed; Darzacq, Xavier; Nollmann, Marcelo; Dahan, Maxime; Wu, Carl; Lionnet, Timothée; Liddle, J Alexander; Bargmann, Cornelia I

    2016-03-01

    Multifocus microscopy (MFM) allows high-resolution instantaneous three-dimensional (3D) imaging and has been applied to study biological specimens ranging from single molecules inside cells nuclei to entire embryos. We here describe pattern designs and nanofabrication methods for diffractive optics that optimize the light-efficiency of the central optical component of MFM: the diffractive multifocus grating (MFG). We also implement a "precise color" MFM layout with MFGs tailored to individual fluorophores in separate optical arms. The reported advancements enable faster and brighter volumetric time-lapse imaging of biological samples. In live microscopy applications, photon budget is a critical parameter and light-efficiency must be optimized to obtain the fastest possible frame rate while minimizing photodamage. We provide comprehensive descriptions and code for designing diffractive optical devices, and a detailed methods description for nanofabrication of devices. Theoretical efficiencies of reported designs is ≈90% and we have obtained efficiencies of > 80% in MFGs of our own manufacture. We demonstrate the performance of a multi-phase MFG in 3D functional neuronal imaging in living C. elegans.

  4. Evaluation of Chemical Interactions between Small Molecules in the Gas Phase Using Chemical Force Microscopy.

    PubMed

    Lee, Jieun; Ju, Soomi; Kim, In Tae; Jung, Sun-Hwa; Min, Sun-Joon; Kim, Chulki; Sim, Sang Jun; Kim, Sang Kyung

    2015-12-04

    Chemical force microscopy analyzes the interactions between various chemical/biochemical moieties in situ. In this work we examined force-distance curves and lateral force to measure the interaction between modified AFM tips and differently functionalized molecular monolayers. Especially for the measurements in gas phase, we investigated the effect of humidity on the analysis of force-distance curves and the images in lateral force mode. Flat chemical patterns composed of different functional groups were made through micro-contact printing and lateral force mode provided more resolved analysis of the chemical patterns. From the images of 1-octadecanethiol/11-mercapto-1-undecanoic acid patterns, the amine group functionalized tip brought out higher contrast of the patterns than an intact silicon nitride tip owing to the additional chemical interaction between carboxyl and amine groups. For more complex chemical interactions, relative chemical affinities toward specific peptides were assessed on the pattern of 1-octadecanethiol/phenyl-terminated alkanethiol. The lateral image of chemical force microscopy reflected specific preference of a peptide to phenyl group as well as the hydrophobic interaction.

  5. The direct determination of magnetic domain wall profiles by differential phase contrast electron microscopy.

    PubMed

    Chapman, J N; Batson, P E; Waddell, E M; Ferrier, R P

    1978-01-01

    A new technique for the quantitative investigation of magnetic structures in ferromagnetic thin films is proposed. Unlike previous techniques the detected signal is simply related to the magnetic induction in the film, and as such the direct determination of domain wall profiles is possible. The technique utilizes a differential phase contrast mode of scanning transmission electron microscopy in which the normal bright field detector is replaced by a split-detector lying symmetrically about the optic axis of the system. The difference signal from the two halves of the detector provides the required magnetic information. Analysis of the image formation mechanism shows that, using a commercially available scanning transmission electron microscope equipped with a field emission gun, wall profiles should be obtainable directly from most structures of interest in Lorentz microscopy. Furthermore, signal-to-noise considerations indicate that these results can be obtained in acceptably short recording times. Finally, experimental results using both polycrystalline and single crystal specimens are presented, which confirm the theoretical predictions. PMID:358526

  6. Phasing of the Triatoma virus diffraction data using a cryo-electron microscopy reconstruction

    SciTech Connect

    Estrozi, L.F.; Neumann, E.; Squires, G.; Rozas-Dennis, G.; Costabel, M.; Rey, F.A.; Guerin, D.M.A. Navaza, J.

    2008-05-25

    The blood-sucking reduviid bug Triatoma infestans, one of the most important vector of American human trypanosomiasis (Chagas disease) is infected by the Triatoma virus (TrV). TrV has been classified as a member of the Cripavirus genus (type cricket paralysis virus) in the Dicistroviridae family. This work presents the three-dimensional cryo-electron microscopy (cryo-EM) reconstruction of the TrV capsid at about 25 A resolution and its use as a template for phasing the available crystallographic data by the molecular replacement method. The main structural differences between the cryo-EM reconstruction of TrV and other two viruses, one from the same family, the cricket paralysis virus (CrPV) and the human rhinovirus 16 from the Picornaviridae family are presented and discussed.

  7. Automatic neuron segmentation and neural network analysis method for phase contrast microscopy images

    PubMed Central

    Pang, Jincheng; Özkucur, Nurdan; Ren, Michael; Kaplan, David L.; Levin, Michael; Miller, Eric L.

    2015-01-01

    Phase Contrast Microscopy (PCM) is an important tool for the long term study of living cells. Unlike fluorescence methods which suffer from photobleaching of fluorophore or dye molecules, PCM image contrast is generated by the natural variations in optical index of refraction. Unfortunately, the same physical principles which allow for these studies give rise to complex artifacts in the raw PCM imagery. Of particular interest in this paper are neuron images where these image imperfections manifest in very different ways for the two structures of specific interest: cell bodies (somas) and dendrites. To address these challenges, we introduce a novel parametric image model using the level set framework and an associated variational approach which simultaneously restores and segments this class of images. Using this technique as the basis for an automated image analysis pipeline, results for both the synthetic and real images validate and demonstrate the advantages of our approach. PMID:26601004

  8. Bacteria-clay interactions investigated by light scattering and phase contrast microscopy

    NASA Astrophysics Data System (ADS)

    Alimova, Alexandra; Block, Karin; Rudolph, Elizabeth; Katz, A.; Steiner, J. C.; Gottlieb, P.; Alfano, R. R.

    2006-02-01

    Light scattering experiments and phase contrast microscopy are used to evaluate the aggregate-forming characteristics of simple clay-bacteria mixtures. Colloidal suspensions of negatively charged Pseudomonas syringae (Ps) and Mg 2+-, Li + - or Ca 2+ -exchanged smectite (and non-exchanged smectite) are flocculated in neutral (pH 7) aqueous media. Aggregate formation is monitored using changes in optical transmission. Clustering is observed in all the clay-bacteria preparations. The Li +-substituted clay aggregates average 50-300 microns in diameter, in contrast to the Ca 2+- substituted clay that produces aggregates of 10-50 microns in diameter. Light scattering measurements indicate that aggregates begin forming 3 hours after mixing and that the (larger sized) aggregates exhibit less scattering than a mixture with an equivalent concentration of unattached Ps and clay particles.

  9. Primary ciliary dyskinesia assessment by means of optical flow analysis of phase-contrast microscopy images.

    PubMed

    Parrilla, Eduardo; Armengot, Miguel; Mata, Manuel; Sánchez-Vílchez, José Manuel; Cortijo, Julio; Hueso, José L; Riera, Jaime; Moratal, David

    2014-04-01

    Primary ciliary dyskinesia implies cilia with defective or total absence of motility, which may result in sinusitis, chronic bronchitis, bronchiectasis and male infertility. Diagnosis can be difficult and is based on an abnormal ciliary beat frequency (CBF) and beat pattern. In this paper, we present a method to determine CBF of isolated cells through the analysis of phase-contrast microscopy images, estimating cilia motion by means of an optical flow algorithm. After having analyzed 28 image sequences (14 with a normal beat pattern and 14 with a dyskinetic pattern), the normal group presented a CBF of 5.2 ± 1.6 Hz, while the dyskinetic patients presented a 1.9 ± 0.9 Hz CBF. The cutoff value to classify a dyskinetic specimen was set to 3.45 Hz (sensitivity 0.86, specificity 0.93). The presented methodology has provided excellent results to objectively diagnose PCD. PMID:24438822

  10. [The spectroscopic study on the interaction between edible pigment and human serum albumin in two-phase aqueous systems].

    PubMed

    Deng, Fan-zheng; Guo, Dong-fang; Wang, Hai-rong

    2007-02-01

    In polyethylene glycol 2000 (PEG)-(NH4)2SO4-edible pigment two-phase aqueous systems, the spectroscopic behaviour of the complexes of edible pigment and human serum albumin in PEG phase was investigated. Effects of different acidity, quantities of PEG and salt, reaction time, and coexistent matter on the determination of systems were discussed. Experimental results show that compared to BS spectra, the maximum wavelength of the complex of human serum albumin shifted to the red by 13 nm in buffer solution at pH 8, the maximum binding number of 40 was measured by molar ratio method, and the apparent molar absorptivity was 9.4 x 10(4) L x mol(-1) x cm(-1). The linear range was 0-21.07 mg x L(-1). With different surfactant, the interaction mechanism of protein and edible pigment was discussed.

  11. Atomic-force-microscopy studies of phase separations in macromolecular systems

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Yu. G.; Malkin, A. J.; McPherson, A.

    1998-09-01

    Atomic force microscopy (AFM) has been used to visualize events arising from the formation of intervening metastable phases at the surfaces of macromolecular crystals growing from solution. Crystals investigated were of the proteins canavalin, thaumatin, lipase, xylanase, and catalase, crystals of transfer RNA, and crystals of satellite tobacco mosaic virus. Two types of aggregates were observed. The first were small, linear and branched aggregates, perhaps fractile in structure. These were incorporated into growing crystals as impurities, and they produced defects of various kinds. The second aggregate form we infer to be liquid-protein droplets which were particularly evident in freshly mixed protein-precipitant solutions. Droplets, upon sedimentation, have two possible fates. In some cases they immediately restructured as crystalline multilayer stacks whose development was guided by and contiguous with the underlying lattice. These contributed to the ordered growth of the crystal by serving as sources of growth steps. In other cases, liquid-protein droplets formed distinct microcrystals, somehow discontinuous with the underlying lattice, and these were subsequently incorporated into the growing substrate crystal with the formation of defects. Scarring experiments with the AFM tip indicated that liquid-protein droplets with the potential to rapidly crystallize were a consequence of concentration instabilities near the crystal's surfaces. The AFM study suggests that phase separation and the appearance of aggregates having limited order is a common occurrence in supersaturated macromolecular solutions such as the protein-precipitant solutions used for crystallization.

  12. Absolute polarity determination of teeth cementum by phase sensitive second harmonic generation microscopy.

    PubMed

    Aboulfadl, Hanane; Hulliger, Jürg

    2015-10-01

    The absolute sign of local polarity in relation to the biological growth direction has been investigated for teeth cementum using phase sensitive second harmonic generation microscopy (PS-SHGM) and a crystal of 2-cyclooctylamino-5-nitropyridine (COANP) as a nonlinear optic (NLO) reference material. A second harmonic generation (SHG) response was found in two directions of cementum: radial (acellular extrinsic fibers that are oriented more or less perpendicular to the root surface) and circumferential (cellular intrinsic fibers that are oriented more or less parallel to the surface). A mono-polar state was demonstrated for acellular extrinsic cementum. However, along the different parts of cementum in circumferential direction, two corresponding domains were observed featuring an opposite sign of polarity indicative for a bi-polar microscopic state of cellular intrinsic cementum. The phase information showed that the orientation of radial collagen fibrils of cementum is regularly organized with the donor (D) groups pointing to the surface. Circumferential collagen molecules feature orientational disorder and are oriented up and down in random manner showing acceptor or donor groups at the surface of cementum. Considering that the cementum continues to grow in thickness throughout life, we can conclude that the cementum is growing circumferentially in two opposite directions and radially in one direction. A Markov chain type model for polarity formation in the direction of growth predicts D-groups preferably appearing at the fiber front.

  13. Comparison of Fluorescence Microscopy and Solid-Phase Cytometry Methods for Counting Bacteria in Water

    PubMed Central

    Lisle, John T.; Hamilton, Martin A.; Willse, Alan R.; McFeters, Gordon A.

    2004-01-01

    Total direct counts of bacterial abundance are central in assessing the biomass and bacteriological quality of water in ecological and industrial applications. Several factors have been identified that contribute to the variability in bacterial abundance counts when using fluorescent microscopy, the most significant of which is retaining an adequate number of cells per filter to ensure an acceptable level of statistical confidence in the resulting data. Previous studies that have assessed the components of total-direct-count methods that contribute to this variance have attempted to maintain a bacterial cell abundance value per filter of approximately 106 cells filter−1. In this study we have established the lower limit for the number of bacterial cells per filter at which the statistical reliability of the abundance estimate is no longer acceptable. Our results indicate that when the numbers of bacterial cells per filter were progressively reduced below 105, the microscopic methods increasingly overestimated the true bacterial abundance (range, 15.0 to 99.3%). The solid-phase cytometer only slightly overestimated the true bacterial abundances and was more consistent over the same range of bacterial abundances per filter (range, 8.9 to 12.5%). The solid-phase cytometer method for conducting total direct counts of bacteria was less biased and performed significantly better than any of the microscope methods. It was also found that microscopic count data from counting 5 fields on three separate filters were statistically equivalent to data from counting 20 fields on a single filter. PMID:15345419

  14. Absolute polarity determination of teeth cementum by phase sensitive second harmonic generation microscopy.

    PubMed

    Aboulfadl, Hanane; Hulliger, Jürg

    2015-10-01

    The absolute sign of local polarity in relation to the biological growth direction has been investigated for teeth cementum using phase sensitive second harmonic generation microscopy (PS-SHGM) and a crystal of 2-cyclooctylamino-5-nitropyridine (COANP) as a nonlinear optic (NLO) reference material. A second harmonic generation (SHG) response was found in two directions of cementum: radial (acellular extrinsic fibers that are oriented more or less perpendicular to the root surface) and circumferential (cellular intrinsic fibers that are oriented more or less parallel to the surface). A mono-polar state was demonstrated for acellular extrinsic cementum. However, along the different parts of cementum in circumferential direction, two corresponding domains were observed featuring an opposite sign of polarity indicative for a bi-polar microscopic state of cellular intrinsic cementum. The phase information showed that the orientation of radial collagen fibrils of cementum is regularly organized with the donor (D) groups pointing to the surface. Circumferential collagen molecules feature orientational disorder and are oriented up and down in random manner showing acceptor or donor groups at the surface of cementum. Considering that the cementum continues to grow in thickness throughout life, we can conclude that the cementum is growing circumferentially in two opposite directions and radially in one direction. A Markov chain type model for polarity formation in the direction of growth predicts D-groups preferably appearing at the fiber front. PMID:26297858

  15. Comparison of fluorescence microscopy and solid-phase cytometry methods for counting bacteria in water

    USGS Publications Warehouse

    Lisle, John T.; Hamilton, Martin A.; Willse, Alan R.; McFeters, Gordon A.

    2004-01-01

    Total direct counts of bacterial abundance are central in assessing the biomass and bacteriological quality of water in ecological and industrial applications. Several factors have been identified that contribute to the variability in bacterial abundance counts when using fluorescent microscopy, the most significant of which is retaining an adequate number of cells per filter to ensure an acceptable level of statistical confidence in the resulting data. Previous studies that have assessed the components of total-direct-count methods that contribute to this variance have attempted to maintain a bacterial cell abundance value per filter of approximately 106 cells filter-1. In this study we have established the lower limit for the number of bacterial cells per filter at which the statistical reliability of the abundance estimate is no longer acceptable. Our results indicate that when the numbers of bacterial cells per filter were progressively reduced below 105, the microscopic methods increasingly overestimated the true bacterial abundance (range, 15.0 to 99.3%). The solid-phase cytometer only slightly overestimated the true bacterial abundances and was more consistent over the same range of bacterial abundances per filter (range, 8.9 to 12.5%). The solid-phase cytometer method for conducting total direct counts of bacteria was less biased and performed significantly better than any of the microscope methods. It was also found that microscopic count data from counting 5 fields on three separate filters were statistically equivalent to data from counting 20 fields on a single filter.

  16. Identifying ferroelectric phase and domain structure using angle-resolved piezoresponse force microscopy

    SciTech Connect

    Kim, K. L.; Huber, J. E.

    2014-03-24

    We used angle-resolved piezoresponse force microscopy (AR-PFM), vertical PFM (VPFM), and electron backscatter diffraction (EBSD) to provide a systematic interpretation of domain patterns in polycrystalline, near-morphotropic lead zirconate titanate. This material was used to illustrate the power of AR-PFM methods in resolving complex domain patterns where multiple phases may be present. AR-PFM was carried out with a 30° rotation interval, and the resulting data were analysed to identify the orientation of the underlying axis of piezoelectricity. The additional information provided by AR-PFM was studied, comparing its capabilities to those of 3-dimensional PFM, consisting of one VPFM image and two orthogonal lateral PFM (LPFM) images. We show that, in certain conditions, using AR-PFM can identify the phases present at the sub-grain scale. This was confirmed using VPFM and EBSD data. Furthermore, the method can discriminate laminated domain patterns that appear similar in VPFM and can reliably expose domain patterns that may not be seen in LPFM data from a single orientation, or even in 3D PFM data.

  17. Study of Martensitic Phase transformation in a NiTiCu Thin Film Shape Memory Alloy Using Photoelectron Emission Microscopy

    SciTech Connect

    Cai, Mingdong; Langford, Stephen C.; Wu, Maggie J.; Huang, W. M.; Xiong, Gang; Droubay, Timothy C.; Joly, Alan G.; Beck, Kenneth; Hess, Wayne P.; Dickinson, J. T.

    2007-01-01

    The thermally-induced martensitic phase transformation in a polycrystalline NiTiCu thin film shape memory alloy was probed by photoelectron emission microscopy (PEEM). In situ PEEM images reveal distinct changes in microstructure and photoemission intensity at the phase transition temperatures. In particular, images of the low temperature, martensite phase are brighter than that of the high temperature, austenite phase, due to the relatively lower work function of the martensite. Ultra-violet photoelectron spectroscopy shows that the effective work function changes by about 0.16 eV during thermal cycling. In situ PEEM images also show that the network of trenches observed on the room temperature film disappear suddenly during heating and reappear suddenly during subsequent cooling. These trenches are also characterized by atomic force microscopy at selected temperatures. We describe implications of these observations with respect to the spatial distribution of phases during thermal cycling in this thin film shape memory alloy.

  18. Estimation of age based on tooth cementum annulations: A comparative study using light, polarized, and phase contrast microscopy

    PubMed Central

    Kaur, Prabhpreet; Astekar, Madhusudan; Singh, Jappreet; Arora, Karandeep Singh; Bhalla, Gagandeep

    2015-01-01

    Context: The identification of living or deceased persons using unique traits and characteristics of the teeth and jaws is a cornerstone of forensic science. Teeth have been used to estimate age both in the young and old, as well as in the living and dead. Gradual structural changes in teeth throughout life are the basis for age estimation. Tooth cementum annulation (TCA) is a microscopic method for the determination of an individual's age based on the analysis of incremental lines of cementum. Aim: To compare ages estimated using incremental lines of cementum as visualized by bright field microscopy, polarized microscopy, and phase contrast microscopy with the actual age of subject and to determine accuracy and feasibility of the method used. Materials and Methods: Cementum annulations of 60 permanent teeth were analyzed after longitudinal ground sections were made in the mesiodistal plane. The incremental lines were counted manually using a light, polarized and phase contrast microscopy. Ages were estimated and then compared with the actual age of individual. Statistical Analysis: Analysis of variance (ANOVA), Student's t-test, the Pearson product-moment corre (PPMCC) and regression analysis were performed. Results: PPMCC value r = 0.347, 0.542 and 0.989 were obtained using light, polarized and phase contrast microscopy methods respectively. Conclusion: It was concluded that incremental lines of cementum were most clearly visible under a phase contrast microscope, followed by a polarized microscope, and then a light microscope when used for age estimation. PMID:26816462

  19. Theoretical Investigation of OCN(-) Charge Transfer Complexes in Condensed Phase Media: Spectroscopic Properties in Amorphous Ice

    NASA Technical Reports Server (NTRS)

    Park, Jin-Young; Woon, David E.

    2004-01-01

    Density functional theory (DFT) calculations of cyanate (OCN(-)) charge-transfer complexes were performed to model the "XCN" feature observed in interstellar icy grain mantles. OCN(-) charge-transfer complexes were formed from precursor combinations of HNCO or HOCN with either NH3 or H2O. Three different solvation strategies for realistically modeling the ice matrix environment were explored, including (1) continuum solvation, (2) pure DFT cluster calculations, and (3) an ONIOM DFT/PM3 cluster calculation. The model complexes were evaluated by their ability to reproduce seven spectroscopic measurements associated with XCN: the band origin of the OCN(-) asymmetric stretching mode, shifts in that frequency due to isotopic substitutions of C, N, O, and H, plus two weak features. The continuum solvent field method produced results consistent with some of the experimental data but failed to account for other behavior due to its limited capacity to describe molecular interactions with solvent. DFT cluster calculations successfully reproduced the available spectroscopic measurements very well. In particular, the deuterium shift showed excellent agreement in complexes where OCN(-) was fully solvated. Detailed studies of representative complexes including from two to twelve water molecules allowed the exploration of various possible solvation structures and provided insights into solvation trends. Moreover, complexes arising from cyanic or isocyanic acid in pure water suggested an alternative mechanism for the formation of OCN(-) charge-transfer complexes without the need for a strong base such as NH3 to be present. An extended ONIOM (B3LYP/PM3) cluster calculation was also performed to assess the impact of a more realistic environment on HNCO dissociation in pure water.

  20. Terahertz spectroscopic study on order-disorder phase transition of nonadecane

    NASA Astrophysics Data System (ADS)

    Tanno, Takenori; Asari, Junya; Yodokawa, Shinichi; Kurabayashi, Toru

    2015-11-01

    Terahertz transmission spectra of nonadecane (C19H40) in the crystalline and rotator phases were measured over the frequency range of 1-5.5 THz. The absorption peak at 2.2 THz, related to intermolecular interaction, was observed only in the crystalline phase. Using the absorbance at this frequency, the transition between the two phases was investigated. A model of the orientational order-disorder transition of the molecule is presented to qualitatively explain the transition rate.

  1. Comments on "Venus' spectroscopic phase variation: Implications of the Mariner 10 photographs

    NASA Technical Reports Server (NTRS)

    Young, A. T.

    1975-01-01

    From a misinterpretation of Mariner 10 pictures, Chamberlain (1974) constructed a model in which he used horizontal variations in the Venus atmosphere to explain the phase-variation of CO2 absorption at small phase angles. Published observations of spatial variations in CO2 absorption on Venus show that they are too small to explain the phase effect. The question of uniqueness that is, if more than one model can explain the phase-effect observations is discussed. Before this question can be answered, a realistic model that does account for the data must be constructed. No such calculations exist.

  2. Phase diagram of ammonium perchlorate: Raman spectroscopic constrains at high pressures and temperatures

    NASA Astrophysics Data System (ADS)

    Dunuwille, Mihindra; Yoo, Choong-Shik

    2016-06-01

    We present the pressure-temperature (PT) induced physical and chemical transformations in ammonium perchlorates (APs) up to 50 GPa and 450 °C, using diamond anvil cells and confocal micro-Raman spectroscopy, which provide new constraints for the phase diagram of AP. The results show spectral evidences for three new polymorphs (III, IV, and VI) of AP, in addition to two previously known phases (I and II), at various PT conditions with varying degrees of hydrogen bonding and lack of strong spectral evidence for previously known high-temperature cubic phase (phase V). Upon further heating, AP chemically decomposes to N2, N2O, and H2O. The present phase diagram is, therefore, in sharp contrast to the previous one, underscoring a rich polymorphism, a large stability field for solids, and a replacement of the melt with a decomposition line.

  3. Quantitative phase-digital holographic microscopy: a new imaging modality to identify original cellular biomarkers of diseases

    NASA Astrophysics Data System (ADS)

    Marquet, P.; Rothenfusser, K.; Rappaz, B.; Depeursinge, C.; Jourdain, P.; Magistretti, P. J.

    2016-03-01

    Quantitative phase microscopy (QPM) has recently emerged as a powerful label-free technique in the field of living cell imaging allowing to non-invasively measure with a nanometric axial sensitivity cell structure and dynamics. Since the phase retardation of a light wave when transmitted through the observed cells, namely the quantitative phase signal (QPS), is sensitive to both cellular thickness and intracellular refractive index related to the cellular content, its accurate analysis allows to derive various cell parameters and monitor specific cell processes, which are very likely to identify new cell biomarkers. Specifically, quantitative phase-digital holographic microscopy (QP-DHM), thanks to its numerical flexibility facilitating parallelization and automation processes, represents an appealing imaging modality to both identify original cellular biomarkers of diseases as well to explore the underlying pathophysiological processes.

  4. High-resolution microscopy with low-resolution objectives: correcting phase aberrations in Fourier ptychography

    NASA Astrophysics Data System (ADS)

    Konda, Pavan Chandra; Taylor, Jonathan M.; Harvey, Andrew R.

    2015-09-01

    The spatial resolution of a microscope is inversely proportionate to the sum of the objective numerical aperture (NA) and the illumination NA. Fourier Ptychography (FP) microscopy achieves high-resolution, wide-field imaging by the use of a low-NA, wide-field objective combined with time-sequential synthesis of high NA illumination using an array of LEDs. We describe reconstruction algorithms based on Fresnel propagation, rather than the traditional Fraunhofer propagation, which enables more accurate representation of LED illumination and hence reduced aberration in the image reconstruction. This also enables the new technique of Multi-Aperture Fourier Ptychography in the near-field. In this work the implementation of this algorithm is described together with some experimental results. The performance of this algorithm is validated by comparing to Fraunhofer based algorithm. More sophisticated update functions in the reconstruction procedures developed for FP are implemented with this algorithm and their performance is validated. The pupil phase can also be reconstructed during the reconstruction procedure hence allowing us to correct for the aberrations in the optical system without the need of any additional measurements.

  5. System model enabling fast tomographic phase microscopy with total variation regularisation

    NASA Astrophysics Data System (ADS)

    Guo, Min; Chen, Lijun; Shen, Xiaoyan; Iwai, Hidenao; Chen, Yunmei; Liu, Huafeng

    2015-12-01

    Tomographic phase microscopy (TPM) facilitates three-dimensional imaging of live cells based on quantitative measurement of the distribution of the refractive index, but without the need for specific staining. However, the limited imaging speed and the anisotropic resolution of the reconstructed refractive index map remain major obstacles to the extension and further application of TPM. To address these obstacles, we first formulate a general measurement model that linearises the relationship between the measurement data and refractive index map based on a system matrix. In this way, the measurement system is interpreted as a linear system in a complete manner. Then we propose a reconstruction framework for retrieving the refractive index map from the measurement data with reduced angular sample frequency and limited angular coverage of illumination. The framework aims to transform the reconstruction task into an optimisation scheme based on total variation norm regularisation, followed by an efficient solution using the accelerated alternating direction method of multipliers algorithm. Using this method, only sparse angular illuminations need to be collected, thus speeding up the imaging process. We obtained experimental results from both cell-mimic phantom data and real measurement data, which showed that the proposed method can improve the imaging speed while still providing refractive index images with better quality compared with a conventional reconstruction method.

  6. System model enabling fast tomographic phase microscopy with total variation regularisation.

    PubMed

    Guo, Min; Chen, Lijun; Shen, Xiaoyan; Iwai, Hidenao; Chen, Yunmei; Liu, Huafeng

    2015-12-01

    Tomographic phase microscopy (TPM) facilitates three-dimensional imaging of live cells based on quantitative measurement of the distribution of the refractive index, but without the need for specific staining. However, the limited imaging speed and the anisotropic resolution of the reconstructed refractive index map remain major obstacles to the extension and further application of TPM. To address these obstacles, we first formulate a general measurement model that linearises the relationship between the measurement data and refractive index map based on a system matrix. In this way, the measurement system is interpreted as a linear system in a complete manner. Then we propose a reconstruction framework for retrieving the refractive index map from the measurement data with reduced angular sample frequency and limited angular coverage of illumination. The framework aims to transform the reconstruction task into an optimisation scheme based on total variation norm regularisation, followed by an efficient solution using the accelerated alternating direction method of multipliers algorithm. Using this method, only sparse angular illuminations need to be collected, thus speeding up the imaging process. We obtained experimental results from both cell-mimic phantom data and real measurement data, which showed that the proposed method can improve the imaging speed while still providing refractive index images with better quality compared with a conventional reconstruction method. PMID:26562522

  7. Thermodynamic Prediction of Compositional Phases Confirmed by Transmission Electron Microscopy on Tantalum-Based Alloy Weldments

    SciTech Connect

    Moddeman, William E.; Birkbeck, Janine C.; Barklay, Chadwick D.; Kramer, Daniel P.; Miller, Roger G.; Allard, Lawrence F.

    2007-01-30

    Tantalum alloys have been used by the U.S. Department of Energy as structural alloys for radioisotope based thermal to electrical power systems since the 1960s. Tantalum alloys are attractive for high temperature structural applications due to their high melting point, excellent formability, good thermal conductivity, good ductility (even at low temperatures), corrosion resistance, and weldability. Tantalum alloys have demonstrated sufficient high-temperature toughness to survive prolonged exposure to the radioisotope power-system working environment. Typically, the fabrication of power systems requires the welding of various components including the structural members made of tantalum alloys. Issues such as thermodynamics, lattice structure, weld pool dynamics, material purity and contamination, and welding atmosphere purity all potentially confound the understanding of the differences between the weldment properties of the different tantalum-based alloys. The objective of this paper is to outline the thermodynamically favorable material phases in tantalum alloys, with and without small amounts of hafnium, during and following solidification, based on the results derived from the FactSage(c) Integrated Thermodynamic Databank. In addition, Transition Electron Microscopy (TEM) data will show for the first time, the changes occurring in the HfC before and after welding, and the data will elucidate the role HfC plays in pinning grain boundaries.

  8. Microwave spectroscopic observation of distinct electron solid phases in wide quantum wells.

    PubMed

    Hatke, A T; Liu, Yang; Magill, B A; Moon, B H; Engel, L W; Shayegan, M; Pfeiffer, L N; West, K W; Baldwin, K W

    2014-06-20

    In high magnetic fields, two-dimensional electron systems can form a number of phases in which interelectron repulsion plays the central role, since the kinetic energy is frozen out by Landau quantization. These phases include the well-known liquids of the fractional quantum Hall effect, as well as solid phases with broken spatial symmetry and crystalline order. Solids can occur at the low Landau-filling termination of the fractional quantum Hall effect series but also within integer quantum Hall effects. Here we present microwave spectroscopy studies of wide quantum wells that clearly reveal two distinct solid phases, hidden within what in d.c. transport would be the zero diagonal conductivity of an integer quantum-Hall-effect state. Explanation of these solids is not possible with the simple picture of a Wigner solid of ordinary (quasi) electrons or holes.

  9. Microwave spectroscopic observation of distinct electron solid phases in wide quantum wells

    PubMed Central

    Hatke, A. T.; Liu, Yang; Magill, B. A.; Moon, B. H.; Engel, L. W.; Shayegan, M.; Pfeiffer, L. N.; West, K. W.; Baldwin, K. W.

    2014-01-01

    In high magnetic fields, two-dimensional electron systems can form a number of phases in which interelectron repulsion plays the central role, since the kinetic energy is frozen out by Landau quantization. These phases include the well-known liquids of the fractional quantum Hall effect, as well as solid phases with broken spatial symmetry and crystalline order. Solids can occur at the low Landau-filling termination of the fractional quantum Hall effect series but also within integer quantum Hall effects. Here we present microwave spectroscopy studies of wide quantum wells that clearly reveal two distinct solid phases, hidden within what in d.c. transport would be the zero diagonal conductivity of an integer quantum-Hall-effect state. Explanation of these solids is not possible with the simple picture of a Wigner solid of ordinary (quasi) electrons or holes. PMID:24948190

  10. Spectroscopic Fingerprint of Phase-Incoherent Superconductivity in the Underdoped Bi2Sr2CaCu2O8+δ

    SciTech Connect

    Lee, J.; Davis, J.; Fujita, K.; Schmidt, A.R.; Kim, C.K.; Eisaki, H.; Uchida, S.

    2009-08-28

    A possible explanation for the existence of the cuprate 'pseudogap' state is that it is a d-wave superconductor without quantum phase rigidity. Transport and thermodynamic studies provide compelling evidence that supports this proposal, but few spectroscopic explorations of it have been made. One spectroscopic signature of d-wave superconductivity is the particle-hole symmetric 'octet' of dispersive Bogoliubov quasiparticle interference modulations. Here we report on this octet's evolution from low temperatures to well into the underdoped pseudogap regime. No pronounced changes occur in the octet phenomenology at the superconductor's critical temperature T{sub c}, and it survives up to at least temperature T {approx} 1.5 T{sub c}. In this pseudogap regime, we observe the detailed phenomenology that was theoretically predicted for quasiparticle interference in a phase-incoherent d-wave superconductor. Thus, our results not only provide spectroscopic evidence to confirm and extend the transport and thermodynamics studies, but they also open the way for spectroscopic explorations of phase fluctuation rates, their effects on the Fermi arc, and the fundamental source of the phase fluctuations that suppress superconductivity in underdoped cuprates.

  11. Using digital inline holographic microscopy and quantitative phase contrast imaging to assess viability of cultured mammalian cells

    NASA Astrophysics Data System (ADS)

    Missan, Sergey; Hrytsenko, Olga

    2015-03-01

    Digital inline holographic microscopy was used to record holograms of mammalian cells (HEK293, B16, and E0771) in culture. The holograms have been reconstructed using Octopus software (4Deep inwater imaging) and phase shift maps were unwrapped using the FFT-based phase unwrapping algorithm. The unwrapped phase shifts were used to determine the maximum phase shifts in individual cells. Addition of 0.5 mM H2O2 to cell media produced rapid rounding of cultured cells, followed by cell membrane rupture. The cell morphology changes and cell membrane ruptures were detected in real time and were apparent in the unwrapped phase shift images. The results indicate that quantitative phase contrast imaging produced by the digital inline holographic microscope can be used for the label-free real time automated determination of cell viability and confluence in mammalian cell cultures.

  12. Mesoscopic structural phase progression in photo-excited VO2 revealed by time-resolved x-ray diffraction microscopy

    DOE PAGESBeta

    Zhu, Yi; Cai, Zhonghou; Chen, Pice; Zhang, Qingteng; Highland, Matthew J.; Jung, II Woong; Walko, Donald A.; Dufresne, Eric M.; Jaewoo, Jeong; Samant, Mahesh G.; et al

    2016-02-26

    Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase seperated regions. The ability to simultanousely track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of- the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation is initiatedmore » at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, which is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO2. Lastly, the direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems.« less

  13. Mesoscopic structural phase progression in photo-excited VO2 revealed by time-resolved x-ray diffraction microscopy

    NASA Astrophysics Data System (ADS)

    Zhu, Yi; Cai, Zhonghou; Chen, Pice; Zhang, Qingteng; Highland, Matthew J.; Jung, Il Woong; Walko, Donald A.; Dufresne, Eric M.; Jeong, Jaewoo; Samant, Mahesh G.; Parkin, Stuart S. P.; Freeland, John W.; Evans, Paul G.; Wen, Haidan

    2016-02-01

    Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase separated regions. The ability to simultaneously track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of-the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation is initiated at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, and is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO2. The direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems.

  14. Mesoscopic structural phase progression in photo-excited VO2 revealed by time-resolved x-ray diffraction microscopy

    PubMed Central

    Zhu, Yi; Cai, Zhonghou; Chen, Pice; Zhang, Qingteng; Highland, Matthew J.; Jung, Il Woong; Walko, Donald A.; Dufresne, Eric M.; Jeong, Jaewoo; Samant, Mahesh G.; Parkin, Stuart S. P.; Freeland, John W.; Evans, Paul G.; Wen, Haidan

    2016-01-01

    Dynamical phase separation during a solid-solid phase transition poses a challenge for understanding the fundamental processes in correlated materials. Critical information underlying a phase transition, such as localized phase competition, is difficult to reveal by measurements that are spatially averaged over many phase separated regions. The ability to simultaneously track the spatial and temporal evolution of such systems is essential to understanding mesoscopic processes during a phase transition. Using state-of-the-art time-resolved hard x-ray diffraction microscopy, we directly visualize the structural phase progression in a VO2 film upon photoexcitation. Following a homogenous in-plane optical excitation, the phase transformation is initiated at discrete sites and completed by the growth of one lattice structure into the other, instead of a simultaneous isotropic lattice symmetry change. The time-dependent x-ray diffraction spatial maps show that the in-plane phase progression in laser-superheated VO2 is via a displacive lattice transformation as a result of relaxation from an excited monoclinic phase into a rutile phase. The speed of the phase front progression is quantitatively measured, and is faster than the process driven by in-plane thermal diffusion but slower than the sound speed in VO2. The direct visualization of localized structural changes in the time domain opens a new avenue to study mesoscopic processes in driven systems. PMID:26915398

  15. Spectroscopic studies of the ferroelectric and magnetic phase transitions in multiferroic Sr1-xBaxMnO3.

    PubMed

    Goian, V; Kadlec, F; Kadlec, C; Dabrowski, B; Kolesnik, S; Chmaissem, O; Nuzhnyy, D; Kempa, M; Bovtun, V; Savinov, M; Hejtmánek, J; Prokleška, J; Kamba, S

    2016-05-01

    Dielectric response of perovskite Sr1-xBaxMnO3 (x = 0.43 and 0.45) ceramics was investigated using microwave, THz and infrared spectroscopic techniques in order to study the ferroelectric and antiferromagnetic phase transitions with critical temperatures TC ≈ 350 K and TN ≈ 200 K, respectively. The two lowest-frequency polar phonons are overdamped above TN and they exhibit pronounced softening on heating towards TC. Nevertheless, permittivity ε' in the THz range shows only a small anomaly at TC because the phonon contribution to ε' is rather small. The phonons are coupled with a central mode which provides the main contribution to the dielectric anomaly at TC. Thus, the ferroelectric phase transition has characteristics of a crossover from displacive to order-disorder type. At the same time, the intrinsic THz central peak is partially screened by conductivity and related Maxwell-Wagner relaxation, which dominates the microwave and lower-frequency spectra. Below TN, the ferroelectric distortion markedly decreases, which has an influence on the frequencies of both the central and soft modes. Therefore, ε' in the THz range increases at TN on cooling. In spite of the strong spin-phonon coupling near TN, surprisingly no magnetodielectric effect was observed in the THz spectra upon applying magnetic field of up to 7 T, which is in contradiction with the theoretically expected huge magnetoelectric coupling. We explain this fact as due to the insensitivity of TN to magnetic field. PMID:27023160

  16. Nanoparticle flow velocimetry with image phase correlation for confocal laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Jun, Brian H.; Giarra, Matthew; Yang, Haisheng; Main, Russell; Vlachos, Pavlos P.

    2016-10-01

    We present a new particle image correlation technique for resolving nanoparticle flow velocity using confocal laser scanning microscopy (CLSM). The two primary issues that complicate nanoparticle scanning laser image correlation (SLIC)-based velocimetry are (1) the use of diffusion-dominated nanoparticles as flow tracers, which introduce a random decorrelating error into the velocity estimate, and (2) the effects of the scanning laser image acquisition, which introduces a bias error. To date, no study has quantified these errors or demonstrated a means to deal with them in SLIC velocimetry. In this work, we build upon the robust phase correlation (RPC) and existing methods of SLIC to quantify and mitigate these errors. First, we implement an ensemble RPC instead of using an ensemble standard cross-correlation, and develop a SLIC optimal filter that maximizes the correlation strength in order to reliably and accurately detect the correlation peak representing the most probable average displacement of the nanoparticles. Secondly, we developed an analytical model of the SLIC measurement bias error due to image scanning of diffusion-dominated tracer particles. We show that the bias error depends only on the ratio of the mean velocity of the tracer particles to that of the laser scanner and we use this model to correct the induced errors. We validated our technique using synthetic images and experimentally obtained SLIC images of nanoparticle flow through a micro-channel. Our technique reduced the error by up to a factor of ten compared to other SLIC algorithms for the images tested in this study. Moreover, our optimized RPC filter reduces the number of image pairs required for the convergence of the ensemble correlation by two orders of magnitude compared to the standard cross correlation. This feature has broader implications to ensemble correlation methods and should be further explored in depth in the future.

  17. Multimodal Quantitative Phase Imaging with Digital Holographic Microscopy Accurately Assesses Intestinal Inflammation and Epithelial Wound Healing.

    PubMed

    Lenz, Philipp; Brückner, Markus; Ketelhut, Steffi; Heidemann, Jan; Kemper, Björn; Bettenworth, Dominik

    2016-01-01

    The incidence of inflammatory bowel disease, i.e., Crohn's disease and Ulcerative colitis, has significantly increased over the last decade. The etiology of IBD remains unknown and current therapeutic strategies are based on the unspecific suppression of the immune system. The development of treatments that specifically target intestinal inflammation and epithelial wound healing could significantly improve management of IBD, however this requires accurate detection of inflammatory changes. Currently, potential drug candidates are usually evaluated using animal models in vivo or with cell culture based techniques in vitro. Histological examination usually requires the cells or tissues of interest to be stained, which may alter the sample characteristics and furthermore, the interpretation of findings can vary by investigator expertise. Digital holographic microscopy (DHM), based on the detection of optical path length delay, allows stain-free quantitative phase contrast imaging. This allows the results to be directly correlated with absolute biophysical parameters. We demonstrate how measurement of changes in tissue density with DHM, based on refractive index measurement, can quantify inflammatory alterations, without staining, in different layers of colonic tissue specimens from mice and humans with colitis. Additionally, we demonstrate continuous multimodal label-free monitoring of epithelial wound healing in vitro, possible using DHM through the simple automated determination of the wounded area and simultaneous determination of morphological parameters such as dry mass and layer thickness of migrating cells. In conclusion, DHM represents a valuable, novel and quantitative tool for the assessment of intestinal inflammation with absolute values for parameters possible, simplified quantification of epithelial wound healing in vitro and therefore has high potential for translational diagnostic use. PMID:27685659

  18. Optomechanical properties of cancer cells revealed by light-induced deformation and quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Kastl, Lena; Budde, Björn; Isbach, Michael; Rommel, Christina; Kemper, Björn; Schnekenburger, Jürgen

    2015-05-01

    There is a growing interest in cell biology and clinical diagnostics in label-free, optical techniques as the interaction with the sample is minimized and substances like dyes or fixatives do not affect the investigated cells. Such techniques include digital holographic microscopy (DHM) and the optical stretching by fiber optical two beam traps. DHM enables quantitative phase contrast imaging and thereby the determination of the cellular refractive index, dry mass and the volume, whereas optical cell stretching reveals the deformability of cells. Since optical stretching strongly depends on the optical properties and the shape of the investigated material we combined the usage of fiber optical stretching and DHM for the characterization of pancreatic tumor cells. The risk of tumors is their potential to metastasize, spread through the bloodstream and build distal tumors/metastases. The grade of dedifferentiation in which the cells lose their cell type specific properties is a measure for this metastatic potential. The less differentiated the cells are, the higher is their risk to metastasize. Our results demonstrate that pancreatic tumor cells, which are from the same tumor but vary in their grade of differentiation, show significant differences in their deformability. The retrieved data show that differentiated cells have a higher stiffness than less differentiated cells of the same tumor. Even cells that differ only in the expression of a single tumor suppressor gene which is responsible for cell-cell adhesions can be distinguished by their mechanical properties. Additionally, results from DHM measurements yield that the refractive index shows only few variations, indicating that it does not significantly influence optical cell stretching. The obtained results show a promising new approach for the phenotyping of different cell types, especially in tumor cell characterization and cancer diagnostics.

  19. Scattering-type scanning near-field optical microscopy with low-repetition-rate pulsed light source through phase-domain sampling

    NASA Astrophysics Data System (ADS)

    Wang, Haomin; Wang, Le; Xu, Xiaoji G.

    2016-10-01

    Scattering-type scanning near-field optical microscopy (s-SNOM) allows spectroscopic imaging with spatial resolution below the diffraction limit. With suitable light sources, s-SNOM is instrumental in numerous discoveries at the nanoscale. So far, the light sources have been limited to continuous wave or high-repetition-rate pulsed lasers. Low-repetition-rate pulsed sources cannot be used, due to the limitation of the lock-in detection mechanism that is required for current s-SNOM techniques. Here, we report a near-field signal extraction method that enables low-repetition-rate pulsed light sources. The method correlates scattering signals from pulses with the mechanical phases of the oscillating s-SNOM probe to obtain near-field signal, by-passing the apparent restriction imposed by the Nyquist-Shannon sampling theorem on the repetition rate. The method shall enable s-SNOM with low-repetition-rate pulses with high-peak-powers, such as femtosecond laser amplifiers, to facilitate investigations of strong light-matter interactions and nonlinear processes at the nanoscale.

  20. Scattering-type scanning near-field optical microscopy with low-repetition-rate pulsed light source through phase-domain sampling

    PubMed Central

    Wang, Haomin; Wang, Le; Xu, Xiaoji G.

    2016-01-01

    Scattering-type scanning near-field optical microscopy (s-SNOM) allows spectroscopic imaging with spatial resolution below the diffraction limit. With suitable light sources, s-SNOM is instrumental in numerous discoveries at the nanoscale. So far, the light sources have been limited to continuous wave or high-repetition-rate pulsed lasers. Low-repetition-rate pulsed sources cannot be used, due to the limitation of the lock-in detection mechanism that is required for current s-SNOM techniques. Here, we report a near-field signal extraction method that enables low-repetition-rate pulsed light sources. The method correlates scattering signals from pulses with the mechanical phases of the oscillating s-SNOM probe to obtain near-field signal, by-passing the apparent restriction imposed by the Nyquist–Shannon sampling theorem on the repetition rate. The method shall enable s-SNOM with low-repetition-rate pulses with high-peak-powers, such as femtosecond laser amplifiers, to facilitate investigations of strong light–matter interactions and nonlinear processes at the nanoscale. PMID:27748360

  1. Mineralogical composition and phase-to-phase relationships in natural hydraulic lime and/or natural cement - raw materials and burnt products revealed by scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Kozlovcev, Petr; Přikryl, Richard; Racek, Martin; Přikrylová, Jiřina

    2016-04-01

    In contrast to modern process of production of cement clinker, traditional burning of natural hydraulic lime below sintering temperature relied on the formation of new phases from ion migration between neighbouring mineral grains composing raw material. The importance of the mineralogical composition and spatial distribution of rock-forming minerals in impure limestones used as a raw material for natural hydraulic lime presents not well explored issue in the scientific literature. To fill this gap, the recent study focuses in detailed analysis of experimentally burnt impure limestones (mostly from Barrandian area, Bohemian Massif). The phase changes were documented by optical microscopy, X-ray diffraction, and scanning electron microscopy with an energy dispersive spectrometer (SEM-EDS) coupled with x-ray elemental mapping. The latest allowed for visualization of distribution of elements within raw materials and burnt products. SEM/EDS study brought valuable data on the presence of transitional and/or minor phases, which were poorly detectable by other methods.

  2. Optical spectroscopic and reverse-phase HPLC analyses of Hg(II) binding to phytochelatins.

    PubMed

    Mehra, R K; Miclat, J; Kodati, V R; Abdullah, R; Hunter, T C; Mulchandani, P

    1996-02-15

    Optical spectroscopy and reverse-phase HPLC were used to investigate the binding of Hg(II) to plant metal-binding peptides (phytochelatins) with the structure (gammaGlu-Cys)2Gly, (gammaGlu-Cys)3Gly and (gammaGlu-Cys)4Gly. Glutathione-mediated transfer of Hg(II) into phytochelatins and the transfer of the metal ion from one phytochelatin to another was also studied using reverse-phase HPLC. The saturation of Hg(II)-induced bands in the UV/visible and CD spectra of (gammaGlu-Cys)2Gly suggested the formation of a single Hg(II)-binding species of this peptide with a stoichiometry of one metal ion per peptide molecule. The separation of apo-(gammaGlu-Cys)2Gly from its Hg(II) derivative on a C18 reverse-phase column also indicated the same metal-binding stoichiometry. The UV/visible spectra of both (gammaGlu-Cys)3Gly and (gammaGlu-Cys)4Gly at pH 7.4 showed distinct shoulders in the ligand-to-metal charge-transfer region at 280-290 mm. Two distinct Hg(II)-binding species, occurring at metal-binding stoichiometries of around 1.25 and 2.0 Hg(II) ions per peptide molecule, were observed for (gammaGlu-Cys)3Gly. These species exhibited specific spectral features in the charge-transfer region and were separable by HPLC. Similarly, two main Hg(II)-binding species of (gammaGlu-Cys)4Gly were observed by UV/visible and CD spectroscopy at metal-binding stoichiometries of around 1.25 and 2.5 respectively. Only a single peak of Hg(II)-(gammaGlu-Cys)4Gly complexes was resolved under the conditions used for HPLC. The overall Hg(II)-binding stoichiometries of phytochelatins were similar at pH 2.0 and at pH 7.4, indicating that pH did not influence the final Hg(II)-binding capacity of these peptides. The reverse-phase HPLC assays indicated a rapid transfer of Hg(II) from glutathione to phytochelatins. These assays also demonstrated a facile transfer of the metal ion from shorter- to longer-chain phytochelatins. The strength of Hg(II) binding to glutathione and phytochelatins followed the

  3. Comprehensive Size-Determination of Whole Virus Vaccine Particles Using Gas-Phase Electrophoretic Mobility Macromolecular Analyzer, Atomic Force Microscopy, and Transmission Electron Microscopy

    PubMed Central

    Havlik, Marlene; Marchetti-Deschmann, Martina; Friedbacher, Gernot; Winkler, Wolfgang; Messner, Paul; Perez-Burgos, Laura; Tauer, Christa; Allmaier, Günter

    2015-01-01

    Biophysical properties including particle size distribution, integrity, and shape of whole virus vaccine particles at different stages in tick-borne encephalitis (TBE) vaccines formulation were analyzed by a new set of methods. Size-exclusion chromatography (SEC) was used as a conservative sample preparation for vaccine particle fractionation and gas-phase electrophoretic mobility macromolecular analyzer (GEMMA) for analyzing electrophoretic mobility diameters of isolated TBE virions. The derived particle diameter was then correlated with molecular weight. The diameter of the TBE virions determined after SEC by GEMMA instrumentation was 46.8 ± 1.1 nm. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) were implemented for comparison purposes and to gain morphological information on the virion particle. Western blotting (Dot Blot) as an immunological method confirmed biological activity of the particles at various stages of the developed analytical strategy. AFM and TEM measurements revealed higher diameters with much higher SD for a limited number of virions, 60.4 ± 8.5 and 53.5 ± 5.3 nm, respectively. GEMMA instrumentation was also used for fractionation of virions with specifically selected diameters in the gas-phase, which were finally collected by means of an electrostatic sampler. At that point (i.e., after particle collection), AFM and TEM showed that the sampled virions were still intact, exhibiting a narrow size distribution (i.e., 59.8 ± 7.8 nm for AFM and 47.5 ± 5.2 nm for TEM images), and most importantly, dot blotting confirmed immunological activity of the collected samples. Furthermore dimers and virion artifacts were detected, too. PMID:26266988

  4. Infrared spectroscopic characterization of dehydration and accompanying phase transition behaviors in NAT-topology zeolites

    SciTech Connect

    Wang, Hsiu-Wen; Bishop, David

    2012-01-01

    Relative humidity (PH2O, partial pressure of water)-dependent dehydration and accompanying phase transitions in NAT-topology zeolites (natrolite, scolecite, and mesolite) were studied under controlled temperature and known PH2O conditions by in situ diffuse-reflectance infrared Fourier transform spectroscopy and parallel X-ray powder diffraction. Dehydration was characterized by the disappearance of internal H2O vibrational modes. The loss of H2O molecules caused a sequence of structural transitions in which the host framework transformation path was coupled primarily via the thermal motion of guest Na?/Ca2? cations and H2O molecules. The observation of different interactions of H2O molecules and Na?/Ca2? cations with host aluminosilicate frameworks under highand low-PH2O conditions indicated the development of different local strain fields, arising from cation H2O interactions in NAT-type channels. These strain fields influence the Si O/Al O bond strength and tilting angles within and between tetrahedra as the dehydration temperature is approached. The newly observed infrared bands (at 2,139 cm-1 in natrolite, 2,276 cm-1 in scolecite, and 2,176 and 2,259 cm-1 in mesolite) result from strong cation H2O Al Si framework interactions in NAT-type channels, and these bands can be used to evaluate the energetic evolution of Na?/Ca2? cations before and after phase transitions, especially for scolecite and mesolite. The 2,176 and 2,259 cm-1 absorption bands in mesolite also appear to be related to Na?/Ca2? order disorder that occur when mesolite loses its Ow4 H2O molecules.

  5. A Combined Gas-Phase Photoelectron Spectroscopic and Theoretical Study of Zeise's Anion and Its Bromine and Iodine Analogues

    SciTech Connect

    Hou, Gaolei; Wen, Hui; Lopata, Kenneth A.; Zheng, Weijun; Kowalski, Karol; Govind, Niranjan; Wang, Xue B.; Xantheas, Sotiris S.

    2012-06-25

    We report the first photoelectron spectroscopic study of Zeise’s anion, [PtCl3(C2H4)], and its Br- and I- analogs in the gas phase. Well-resolved and rich spectral features are obtained for each species, yielding detailed electronic structure information, which is assigned with the aid of highlevel electronic structure calculations at the Coupled Cluster (CC) level of theory. The electron binding energies of [PtX3(C2H4)] are found to decrease with the size of halogen (4.57, 4.51, and 4.18 eV for X = Cl, Br, and I, respectively). The calculations indicate a synergistic η2 interaction [with interaction strengths of 1.54 (Cl), 1.37 (Br) and 1.10 eV (I)] between the perpendicular C2H4 fragment and the nearly horizontal planar PtX3- anions, resulting in activating the ethylene molecule. The detailed insights of the chemical bonding and underlying electronic structure can be used to benchmark interactions between olefins and transition metal complexes, which are crucial to a wide range of catalytic processes.

  6. Phase transformation of calcium oxalate dihydrate-monohydrate: Effects of relative humidity and new spectroscopic data

    NASA Astrophysics Data System (ADS)

    Conti, Claudia; Casati, Marco; Colombo, Chiara; Realini, Marco; Brambilla, Luigi; Zerbi, Giuseppe

    2014-07-01

    New data on vibrational properties of calcium oxalates and their controversial transformation mechanism are presented. We have focused on whewellite (CaC2O4·H2O) and weddellite [CaC2O4·(2 + x) H2O], the most common phases of calcium oxalate; these compounds occur in many organisms, in kidney stones and in particular kinds of films found on the surface of many works of art. Low temperature experiments carried out by Fourier transform infrared spectroscopy have highlighted both the high structural order in the crystalline state of whewellite and the disordered distribution of the zeolitic water molecules in weddellite. The synthesised nanocrystals of weddellite have been kept under different hygrometric conditions in order to study, by X-ray powder diffraction, the role of “external” water molecules on their stability. Moreover, in order to identify the different kinds of water molecules, a re-investigation, supported by quantum chemical calculations, of the observed vibrational spectra (IR and Raman) of whewellite has been conducted.

  7. Spectroscopic studies of the ferroelectric and magnetic phase transitions in multiferroic Sr1-x Ba x MnO3

    NASA Astrophysics Data System (ADS)

    Goian, V.; Kadlec, F.; Kadlec, C.; Dabrowski, B.; Kolesnik, S.; Chmaissem, O.; Nuzhnyy, D.; Kempa, M.; Bovtun, V.; Savinov, M.; Hejtmánek, J.; Prokleška, J.; Kamba, S.

    2016-05-01

    Dielectric response of perovskite Sr1-x Ba x MnO3 (x  =  0.43 and 0.45) ceramics was investigated using microwave, THz and infrared spectroscopic techniques in order to study the ferroelectric and antiferromagnetic phase transitions with critical temperatures T C  ≈  350 K and T N  ≈  200 K, respectively. The two lowest-frequency polar phonons are overdamped above T N and they exhibit pronounced softening on heating towards T C. Nevertheless, permittivity ɛ‧ in the THz range shows only a small anomaly at T C because the phonon contribution to ɛ‧ is rather small. The phonons are coupled with a central mode which provides the main contribution to the dielectric anomaly at T C. Thus, the ferroelectric phase transition has characteristics of a crossover from displacive to order-disorder type. At the same time, the intrinsic THz central peak is partially screened by conductivity and related Maxwell-Wagner relaxation, which dominates the microwave and lower-frequency spectra. Below T N, the ferroelectric distortion markedly decreases, which has an influence on the frequencies of both the central and soft modes. Therefore, ɛ‧ in the THz range increases at T N on cooling. In spite of the strong spin-phonon coupling near T N, surprisingly no magnetodielectric effect was observed in the THz spectra upon applying magnetic field of up to 7 T, which is in contradiction with the theoretically expected huge magnetoelectric coupling. We explain this fact as due to the insensitivity of T N to magnetic field.

  8. X-ray Phase Imaging Microscopy with Two-Dimensional Knife-Edge Filters

    NASA Astrophysics Data System (ADS)

    Choi, Jaeho; Park, Yong-Sung

    2012-04-01

    A novel scheme of X-ray differential phase imaging was implemented with an array source and a two-dimensional Foucault knife-edge (2DFK). A pinhole array lens was employed to manipulate the X-ray beam on the Fourier space. An emerging biaxial scanning procedure was also demonstrated with the periodic 2DFK. The differential phase images (DPIs) of the midrib in a leaf of a rose bush were visualized to verify the phase imaging of biological specimens by the proposed method. It also has features of depicting multiple-stack phase images, and rendering morphological DPIs, because it acquires pure phase information.

  9. Coherence-controlled holographic microscopy principle embodiment into Q-PHASE microscope: story of a successful technology transfer

    NASA Astrophysics Data System (ADS)

    Lostak, M.; Chmelik, R.

    2016-03-01

    Curiously, the coherence-controlled holographic microscopy (CCHM) was brought into the world owing to the endeavor of Chmelik's team at Brno University of Technology (BUT) to avoid scanning in confocal microscopy. As coherence gating seemed to be the way, the Leith & Upatnieks proposal of incoherent holography had been considered attractive. Their method made interference system free from strict dependence on both spatial and temporal coherence. Off axis holographic system proposed on such basis has been proved capable of coherence based depth discrimination in single wide-field shot in reflected-light arrangement. Consequently, extremely low-coherence holographic imaging had been found highly contributive also to the image quality depriving it from coherence artefacts and improving its transversal resolution. This is why CCHM promised high precision of quantitative phase imaging (QPI) in transmitted light set up that was realized for cell biology. However the cost of necessarily complicated optical design and need of very precise mechanics forced the team of prof Chmelik at BUT to search for a company capable of mastering the instrument. It was TESCAN ORSAY the highly successful scanning electron microscopes producer that finally took charge of the commercial design. Long-term collaboration of the company with BUT made possible both the CCHM technology successful transfer up to Q-PHASE microscope production as well as the company Light microscopy division reinforcement. This contribution merges views of CCHM technology author and the TESCAN development team.

  10. Calorimetric and spectroscopic studies of the thermotropic phase behavior of lipid bilayer model membranes composed of a homologous series of linear saturated phosphatidylserines.

    PubMed Central

    Lewis, R N; McElhaney, R N

    2000-01-01

    The thermotropic phase behavior of lipid bilayer model membranes composed of the even-numbered, N-saturated 1,2-diacyl phosphatidylserines was studied by differential scanning calorimetry and by Fourier-transform infrared and (31)P-nuclear magnetic resonance spectroscopy. At pH 7.0, 0.1 M NaCl and in the absence of divalent cations, aqueous dispersions of these lipids, which have not been incubated at low temperature, exhibit a single calorimetrically detectable phase transition that is fully reversible, highly cooperative, and relatively energetic, and the transition temperatures and enthalpies increase progressively with increases in hydrocarbon chain length. Our spectroscopic observations confirm that this thermal event is a lamellar gel (L(beta))-to-lamellar liquid crystalline (L(alpha)) phase transition. However, after low temperature incubation, the L(beta)/L(alpha) phase transition of dilauroyl phosphatidylserine is replaced by a higher temperature, more enthalpic, and less cooperative phase transition, and an additional lower temperature, less enthalpic, and less cooperative phase transition appears in the longer chain phosphatidylserines. Our spectroscopic results indicate that this change in thermotropic phase behavior when incubated at low temperatures results from the conversion of the L(beta) phase to a highly ordered lamellar crystalline (L(c)) phase. Upon heating, the L(c) phase of dilauroyl phosphatidylserine converts directly to the L(alpha) phase at a temperature slightly higher than that of its original L(beta)/L(alpha) phase transition. Calorimetrically, this process is manifested by a less cooperative but considerably more energetic, higher-temperature phase transition, which replaces the weaker L(beta)/L(alpha) phase transition alluded to above. However, with the longer chain compounds, the L(c) phase first converts to the L(beta) phase at temperatures some 10-25 degrees C below that at which the L(beta) phase converts to the L(alpha) phase

  11. Assessment of amide I spectroscopic maps for a gas-phase peptide using IR-UV double-resonance spectroscopy and density functional theory calculations

    NASA Astrophysics Data System (ADS)

    Carr, J. K.; Zabuga, A. V.; Roy, S.; Rizzo, T. R.; Skinner, J. L.

    2014-06-01

    The spectroscopy of amide I vibrations has become a powerful tool for exploring protein structure and dynamics. To help with spectral interpretation, it is often useful to perform molecular dynamics (MD) simulations. To connect spectroscopic experiments to simulations in an efficient manner, several researchers have proposed "maps," which relate observables in classical MD simulations to quantum spectroscopic variables. It can be difficult to discern whether errors in the theoretical results (compared to experiment) arise from inaccuracies in the MD trajectories or in the maps themselves. In this work, we evaluate spectroscopic maps independently from MD simulations by comparing experimental and theoretical spectra for a single conformation of the α-helical model peptide Ac-Phe-(Ala)5-Lys-H+ in the gas phase. Conformation-specific experimental spectra are obtained for the unlabeled peptide and for several singly and doubly 13C-labeled variants using infrared-ultraviolet double-resonance spectroscopy, and these spectra are found to be well-modeled by density functional theory (DFT) calculations at the B3LYP/6-31G** level. We then compare DFT results for the deuterated and 13C18O-labeled peptide with those from spectroscopic maps developed and used previously by the Skinner group. We find that the maps are typically accurate to within a few cm-1 for both frequencies and couplings, having larger errors only for the frequencies of terminal amides.

  12. Assessment of amide I spectroscopic maps for a gas-phase peptide using IR-UV double-resonance spectroscopy and density functional theory calculations

    SciTech Connect

    Carr, J. K.; Roy, S.; Skinner, J. L.; Zabuga, A. V.; Rizzo, T. R.

    2014-06-14

    The spectroscopy of amide I vibrations has become a powerful tool for exploring protein structure and dynamics. To help with spectral interpretation, it is often useful to perform molecular dynamics (MD) simulations. To connect spectroscopic experiments to simulations in an efficient manner, several researchers have proposed “maps,” which relate observables in classical MD simulations to quantum spectroscopic variables. It can be difficult to discern whether errors in the theoretical results (compared to experiment) arise from inaccuracies in the MD trajectories or in the maps themselves. In this work, we evaluate spectroscopic maps independently from MD simulations by comparing experimental and theoretical spectra for a single conformation of the α-helical model peptide Ac-Phe-(Ala){sub 5}-Lys-H{sup +} in the gas phase. Conformation-specific experimental spectra are obtained for the unlabeled peptide and for several singly and doubly {sup 13}C-labeled variants using infrared-ultraviolet double-resonance spectroscopy, and these spectra are found to be well-modeled by density functional theory (DFT) calculations at the B3LYP/6-31G** level. We then compare DFT results for the deuterated and {sup 13}C{sup 18}O-labeled peptide with those from spectroscopic maps developed and used previously by the Skinner group. We find that the maps are typically accurate to within a few cm{sup −1} for both frequencies and couplings, having larger errors only for the frequencies of terminal amides.

  13. Non-iterative determination of pattern phase in structured illumination microscopy using auto-correlations in Fourier space.

    PubMed

    Wicker, Kai

    2013-10-21

    The artefact-free reconstruction of structured illumination microscopy images requires precise knowledge of the pattern phases in the raw images. If this parameter cannot be controlled precisely enough in an experimental setup, the phases have to be determined a posteriori from the acquired data. While an iterative optimisation based on cross-correlations between individual Fourier images yields accurate results, it is rather time-consuming. Here I present a fast non-iterative technique which determines each pattern phase from an auto-correlation of the respective Fourier image. In addition to improving the speed of the reconstruction, simulations show that this method is also more robust, yielding errors of typically less than λ/500 under realistic signal-to-noise levels.

  14. Contrast transfer functions for Zernike phase contrast in full-field transmission hard X-ray microscopy.

    PubMed

    Yang, Yang; Cheng, Yin; Heine, Ruth; Baumbach, Tilo

    2016-03-21

    Full-field transmission hard X-ray microscopy (TXM) has been widely applied to study morphology and structures with high spatial precision and to dynamic processes. Zernike phase contrast (ZPC) in hard X-ray TXM is often utilized to get an in-line phase contrast enhancement for weak-absorbing materials with little contrast differences. Here, following forward image formation, we derive and simplify the contrast transfer functions (CTFs) of the Zernike phase imaging system in TXM based on a linear space-shift-invariant imaging mode under certain approximations. The CTFs in ZPC in their simplified forms show a high similarity to the one in free-space propagation X-ray imaging systems. PMID:27136800

  15. Superconducting scanning tunneling microscopy tips in a magnetic field: Geometry-controlled order of the phase transition

    SciTech Connect

    Eltschka, Matthias Jäck, Berthold; Assig, Maximilian; Etzkorn, Markus; Ast, Christian R.; Kondrashov, Oleg V.; Skvortsov, Mikhail A.; Kern, Klaus

    2015-09-21

    The properties of geometrically confined superconductors significantly differ from their bulk counterparts. Here, we demonstrate the geometrical impact for superconducting scanning tunneling microscopy (STM) tips, where the confinement ranges from the atomic to the mesoscopic scale. To this end, we compare the experimentally determined magnetic field dependence for several vanadium tips to microscopic calculations based on the Usadel equation. For our theoretical model of a superconducting cone, we find a direct correlation between the geometry and the order of the superconducting phase transition. Increasing the opening angle of the cone changes the phase transition from first to second order. Comparing our experimental findings to the theory reveals first and second order quantum phase transitions in the vanadium STM tips. In addition, the theory also explains experimentally observed broadening effects by the specific tip geometry.

  16. Super resolution microscopy of lipid bilayer phases and single molecule kinetic studies on merocyanine 540 bound lipid vesicles

    NASA Astrophysics Data System (ADS)

    Kuo, Chin-Kuei

    Recently, observing biological process and structural details in live cell became feasible after the introduction of super-resolution microscopy. Super-resolution microscopy by single molecule localization is the method that has commonly been used for such purpose. There are mainly three approaches to it: stochastic optical reconstruction microscopy (STORM), photoactivated localization microscopy (PALM), and point accumulation in nanoscale topology (PAINT). STORM and PALM rely on external laser control and use of photoactivable fluorescent protein or photoswitchable dyes and are technically challenging. The PAINT method relies on the control of thermal reaction rates to enable the switching between bright and dark states. Therefore, many conventional fluorescent probes can be applied in PAINT method and the images denote different information composed of interactions between the probe and its immediate environment by variations of probe parameters. The existence of lipid rafts has been under debates for decades due to the lack of a tool to directly visualize them in live cells. In the thesis, we combine PAINT with a phase sensitive dye, Merocyanine 540, to enable nanoscale observation of phase separation on supported lipid bilayers of mixed liquid/gel phases. The imaging results are presented in the chapter 3. Given that this is the first example of visualization of nanoscale phase separation of lipid bilayers using an optical microscope, we further looked into the kinetics of MC540 monomer dimer equilibrium in lipid bilayers using single molecule intensity time trajectory analysis and polarization dependent imaging. Our finding confirms that perpendicular monomeric MC540 (to the membrance surface) is the emitting speices in our system and it stays fluorescent for roughly 3 ms before it switches off to dark states. This part of analysis is presented in the chapter 4. All the materials, procedures to carry out experiments and data analysis, methods involved in our

  17. Imaging the three orientation variants of the DO22 phase by 3D atom probe microscopy.

    PubMed

    Marteau, L; Pareige, C; Blavette, D

    2001-12-01

    Three-phase NiAlV alloys were investigated using a three-dimensional atom probe. Ageing at 800 degrees C gives rise to the precipitation of two ordered phases within the supersaturated FCC solid solution, namely Ni3Al (L1(2) structure) and Ni3V (DO22 structure). The DO22 phase has three orientation variants which need to be identified in 3DAP images. It is shown that an appropriate choice of analysis site enables us to image the chemical order within both L1(2) and DO22 ordered phases and to distinguish the three orientation variants of the DO22 phase in reconstructed images. The lateral resolution of 3DAP in these experimental conditions was estimated through simple considerations to be less than 0.3 nm.

  18. The HCP To BCC Phase Transformation in Ti Characterized by Nanosecond Electron Microscopy

    SciTech Connect

    Campbell, G; LaGrange, T; King, W; Colvin, J; Ziegler, A; Browning, N; Kleinschmidt, H; Bostanjoglo, O

    2005-06-21

    The general class of martensitic phase transformations occurs by a rapid lattice-distortive mechanism, where kinetics and morphology of the transformation are dominated by the strain energy. Since transformation is diffusionless, phase fronts propagate through a crystal with great speed that can approach the speed of sound. We have observed a particular example of this class of phase transformation, the hexagonal close packed (HCP) to body centered cubic (BCC) transformation in titanium that is driven by a rapid increase in temperature. We have used a novel nanosecond electron microscope (the dynamic transmission electron microscope, DTEM) to acquire diffraction and imaging information on the transformation, which is driven in-situ by nanosecond laser irradiation. Using nanosecond exposure times that are possible in the DTEM, data can be collected about the transient events in these fast transformations. We have identified the phase transformation with diffraction patterns and correlated the time of the phase transformation with calculated conditions in the sample.

  19. Direct observation of mesoscopic phase separation in KxFeySe2 by scanning microwave microscopy

    NASA Astrophysics Data System (ADS)

    Maeda, Atsutaka; Takahashi, Hideyuki; Imai, Yoshinori

    2015-03-01

    KxFeySe2 is isostructural to 122-FeAs compounds. However, its electronic structure is unique among Fe-based superconductors in the sense that hole Fermi pocket is absent at the center of the Brillouin zone. Therefore, it is important to study this compounds in terms of the mechanism of superconductivity since some pairing (for example, s +/- -wave) needs the interaction between hole and electron Fermi pockets. However, the phase separation in this material makes studies using conventional macroscopic measurement techniques very difficult. Scanning near-field microwave microscope (SMM), which can measure local electric property of inhomogeneous conducting samples, should be a powerful tool. Recently we developed the combined instrument of STM and SMM with high sensitivity, and investigated the local electric property of KxFeySe2 (x = 0.8, y = 1.6 ~2, Tc = 31 K) using this scanning tunneling/microwave microscope. The characteristic pattern of mesoscopic phase separation of the metallic and the semiconducting phase was observed. From the comparison with previously reported SEM/EDS result we identified the metallic phase and the semiconducting phase as the minor Fe-rich phase and the major K2Fe4Se5 phase, respectively.

  20. Parallel preparation of plan-view transmission electron microscopy specimens by vapor-phase etching with integrated etch stops.

    PubMed

    English, Timothy S; Provine, J; Marshall, Ann F; Koh, Ai Leen; Kenny, Thomas W

    2016-07-01

    Specimen preparation remains a practical challenge in transmission electron microscopy and frequently limits the quality of structural and chemical characterization data obtained. Prevailing methods for thinning of specimens to electron transparency are serial in nature, time consuming, and prone to producing artifacts and specimen failure. This work presents an alternative method for the preparation of plan-view specimens using isotropic vapor-phase etching with integrated etch stops. An ultrathin amorphous etch-stop layer simultaneously serves as an electron transparent support membrane whose thickness is defined by a controlled growth process such as atomic layer deposition with sub-nanometer precision. This approach eliminates the need for mechanical polishing or ion milling to achieve electron transparency, and reduces the occurrence of preparation induced artifacts. Furthermore, multiple specimens from a plurality of samples can be thinned in parallel due to high selectivity of the vapor-phase etching process. These features enable dramatic reductions in preparation time and cost without sacrificing specimen quality and provide advantages over wet etching techniques. Finally, we demonstrate a platform for high-throughput transmission electron microscopy of plan-view specimens by combining the parallel preparation capabilities of vapor-phase etching with wafer-scale micro- and nanofabrication.

  1. High Resolution Electron Microscopy Study of Phase Composition of Yttrium Oxide Nanoparticles

    NASA Astrophysics Data System (ADS)

    Mamtsev, D. I.; Murzakaev, A. M.

    2015-10-01

    Phase composition and structural features of the yttrium oxide nanoparticles produced by laser evaporation are studied. Initial and annealed samples were examined. Initial samples contain several phases. The phase composition is found to depend on the particle size. Small crystallites (5-12 nm) possess a FCC lattice (Fm-3m) and larger ones have a BCC lattice (Ia-3). Annealing at temperatures T = 930-1000°C allowed to obtain samples containing only particles with the BCC lattice that may be used for the manufacture of transparent ceramics.

  2. Quantitative Carré differential interference contrast microscopy to assess phase and amplitude.

    PubMed

    Duncan, Donald D; Fischer, David G; Dayton, Amanda; Prahl, Scott A

    2011-06-01

    We present a method of using an unmodified differential interference contrast microscope to acquire quantitative information on scatter and absorption of thin tissue samples. A simple calibration process is discussed that uses a standard optical wedge. Subsequently, we present a phase-stepping procedure for acquiring phase gradient information exclusive of absorption effects. The procedure results in two-dimensional maps of the local angular (polar and azimuthal) ray deviation. We demonstrate the calibration process, discuss details of the phase-stepping algorithm, and present representative results for a porcine skin sample.

  3. Ratioed scatter diagrams - An erotetic method for phase identification on complex surfaces using scanning Auger microscopy

    NASA Technical Reports Server (NTRS)

    Browning, R.

    1984-01-01

    By ratioing multiple Auger intensities and plotting a two-dimensional occupational scatter diagram while digitally scanning across an area, the number and elemental association of surface phases can be determined. This can prove a useful tool in scanning Auger microscopic analysis of complex materials. The technique is illustrated by results from an anomalous region on the reaction zone of a SiC/Ti-6Al-4V metal matrix composite material. The anomalous region is shown to be a single phase associated with sulphur and phosphorus impurities. Imaging of a selected phase from the ratioed scatter diagram is possible and may be a useful technique for presenting multiple scanning Auger images.

  4. Electron microscopy analyses and electrical properties of the layered Bi{sub 2}WO{sub 6} phase

    SciTech Connect

    Taoufyq, A.; Ait Ahsaine, H.; Patout, L.; Benlhachemi, A.; Ezahri, M.; and others

    2013-07-15

    The bismuth tungstate Bi{sub 2}WO{sub 6} was synthesized using a classical coprecipitation method followed by a calcination process at different temperatures. The samples were characterized by X-ray diffraction, simultaneous thermogravimetry and differential thermal analysis (TGA/DTA), scanning and transmission electron microscopy (SEM, TEM) analyses. The Rietveld analysis and electron diffraction clearly confirmed the Pca2{sub 1} non centrosymmetric space group previously proposed for this phase. The layers Bi{sub 2}O{sub 2}{sup 2+} and WO{sub 4}{sup 2−} have been directly evidenced from the HRTEM images. The electrical properties of Bi{sub 2}WO{sub 6} compacted pellets systems were determined from electrical impedance spectrometry (EIS) and direct current (DC) analyses, under air and argon, between 350 and 700 °C. The direct current analyses showed that the conduction observed from EIS analyses was mainly ionic in this temperature range, with a small electronic contribution. Electrical change above the transition temperature of 660 °C is observed under air and argon atmospheres. The strong conductivity increase observed under argon is interpreted in terms of formation of additional oxygen vacancies coupled with electron conduction. - Graphical abstract: High resolution transmission electron microscopy: inverse fast Fourier transform giving the layered structure of the Bi{sub 2}WO{sub 6} phase, with a representation of the cell dimensions (b and c vectors). The Bi{sub 2}O{sub 2}{sup 2+} and WO{sub 4}{sup 2−} sandwiches are visible in the IFFT image. - Highlights: • Using transmission electron microscopy, we visualize the layered structure of Bi{sub 2}WO{sub 6}. • Electrical analyses under argon gas show some increase in conductivity. • The phase transition at 660 °C is evidenced from electrical modification.

  5. Direct observation by laser scanning confocal microscopy of microstructure and phase migration of PVC gels in an applied electric field.

    PubMed

    Xia, Hong; Ueki, Takamitsu; Hirai, Toshihiro

    2011-02-01

    The fluorescent probe lucigenin was incorporated in poly(vinyl chloride) (PVC) gels, and laser scanning confocal microscopy (LSCM) was used to clarify the internal structures of the gels. From the two-dimensional and three-dimensional information by LSCM, we first observed the internal structure of the PVC gel at a wet status, where the PVC gels comprised a polymer-rich phase and a polymer-poor phase uniformly with a three-dimensional network structure. After an electric field was applied, an effect of the electric field resulted in the change of internal structure in the gels. The polymer-poor phase moved from the cathode to the anode and the polymer-rich phase formed linelike arrangement between electrodes due to the attraction force. On the other hand, the freeze-dried PVC gels with/without in-situ dc voltage casting were particularly fabricated to confirm above results by the field emission scanning electron microscopy (FE-SEM). It was found that many craters remained on the surface of the gel near the anode due to sublimation in freeze-drying. This phenomenon did not appear on the surface near the cathode. The results of in-situ dc voltage casting also suggested that a substantial amount of polymer-poor phase was moved and fixed at the anode. Thus, results of both LSCM and in-situ dc voltage casting corresponded to the effect of electric field on PVC gels and provided a convincing evidence for the interpretation of the deformation mechanism of PVC gel actuators by an applied electric field.

  6. Measuring phase shifts and energy dissipation with amplitude modulation atomic force microscopy.

    PubMed

    Martínez, Nicolás F; García, Ricardo

    2006-04-14

    By recording the phase angle difference between the excitation force and the tip response in amplitude modulation AFM it is possible to image compositional variations in heterogeneous samples. In this contribution we address some of the experimental issues relevant to perform phase contrast imaging measurements. Specifically, we study the dependence of the phase shift on the tip-surface separation, interaction regime, cantilever parameters, free amplitude and tip-surface dissipative processes. We show that phase shift measurements can be converted into energy dissipation values. Energy dissipation curves show a maximum (∼10 eV/cycle) with the amplitude ratio. Furthermore, energy dissipation maps provide a robust method to image material properties because they do not depend directly on the tip-surface interaction regime. Compositional contrast images are illustrated by imaging conjugated molecular islands deposited on silicon surfaces. PMID:21727409

  7. Measuring phase shifts and energy dissipation with amplitude modulation atomic force microscopy.

    PubMed

    Martínez, Nicolás F; García, Ricardo

    2006-04-14

    By recording the phase angle difference between the excitation force and the tip response in amplitude modulation AFM it is possible to image compositional variations in heterogeneous samples. In this contribution we address some of the experimental issues relevant to perform phase contrast imaging measurements. Specifically, we study the dependence of the phase shift on the tip-surface separation, interaction regime, cantilever parameters, free amplitude and tip-surface dissipative processes. We show that phase shift measurements can be converted into energy dissipation values. Energy dissipation curves show a maximum (∼10 eV/cycle) with the amplitude ratio. Furthermore, energy dissipation maps provide a robust method to image material properties because they do not depend directly on the tip-surface interaction regime. Compositional contrast images are illustrated by imaging conjugated molecular islands deposited on silicon surfaces.

  8. Fluorescence spectroscopy and confocal microscopy of the mycotoxin citrinin in condensed phase and hydrogel films.

    PubMed

    Lauer, Milena H; Gehlen, Marcelo H; de Jesus, Karen; Berlinck, Roberto G S

    2014-05-01

    The emission spectra, quantum yields and fluorescence lifetimes of citrinin in organic solvents and hydrogel films have been determined. Citrinin shows complex fluorescence decays due to the presence of two tautomers in solution and interconversion from excited-state double proton transfer (ESDPT) process. The fluorescence decay times associated with the two tautomers have values near 1 and 5 ns depending on the medium. In hydrogel films of agarose and alginate, fluorescence imaging showed that citrinin is not homogeneously dispersed and highly emissive micrometer spots may be formed. Fluorescence spectrum and decay analysis are used to recognize the presence of citrinin in hydrogel films using confocal fluorescence microscopy and spectroscopy.

  9. Obstructed diffusion in phase-separated supported lipid bilayers: a combined atomic force microscopy and fluorescence recovery after photobleaching approach.

    PubMed Central

    Ratto, Timothy V; Longo, Marjorie L

    2002-01-01

    Proteins and other macromolecules are believed to hinder molecular lateral diffusion in cellular membranes. We have constructed a well-characterized model system to better understand how obstacles in lipid bilayers obstruct diffusion. Fluorescence recovery after photobleaching was used to measure the lateral diffusion coefficient in single supported bilayers composed of mixtures of 1,2-dilauroylphosphotidylcholine (DLPC) and 1,2-distearoylphosphotidylcholine (DSPC). Because these lipids are immiscible and phase separate at room temperature, a novel quenching technique allowed us to construct fluid DLPC bilayers containing small disk-shaped gel-phase DSPC domains that acted as obstacles to lateral diffusion. Our experimental setup enabled us to analyze the same samples with atomic force microscopy and exactly characterize the size, shape, and number of gel-phase domains before measuring the obstacle-dependent diffusion coefficient. Lateral obstructed diffusion was found to be dependent on obstacle area fraction, size, and geometry. Analysis of our results using a free area diffusion model shows the possibility of unexpected long-range ordering of fluid-phase lipids around the gel-phase obstacles. This lipid ordering has implications for lipid-mediated protein interactions in cellular membranes. PMID:12496105

  10. The nanoscale phase distinguishing of PCL-PB-PCL blended in epoxy resin by tapping mode atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Li, Huiqin; Sun, Limin; Shen, Guangxia; Liang, Qi

    2012-02-01

    In this work, we investigated the bulk phase distinguishing of the poly(ɛ-caprolactone)-polybutadiene-poly(ɛ-caprolactone) (PCL-PB-PCL) triblock copolymer blended in epoxy resin by tapping mode atomic force microscopy (TM-AFM). We found that at a set-point amplitude ratio ( r sp) less than or equal to 0.85, a clear phase contrast could be obtained using a probe with a force constant of 40 N/m. When r sp was decreased to 0.1 or less, the measured size of the PB-rich domain relatively shrank; however, the height images of the PB-rich domain would take reverse (translating from the original light to dark) at r sp = 0.85. Force-probe measurements were carried out on the phase-separated regions by TM-AFM. According to the phase shift angle vs. r sp curve, it could be concluded that the different force exerting on the epoxy matrix or on the PB-rich domain might result in the height and phase image reversion. Furthermore, the indentation depth vs. r sp plot showed that with large tapping force (lower r sp), the indentation depth for the PB-rich domain was nearly identical for the epoxy resin matrix.

  11. The nanoscale phase distinguishing of PCL-PB-PCL blended in epoxy resin by tapping mode atomic force microscopy

    PubMed Central

    2012-01-01

    In this work, we investigated the bulk phase distinguishing of the poly(ε-caprolactone)-polybutadiene-poly(ε-caprolactone) (PCL-PB-PCL) triblock copolymer blended in epoxy resin by tapping mode atomic force microscopy (TM-AFM). We found that at a set-point amplitude ratio (rsp) less than or equal to 0.85, a clear phase contrast could be obtained using a probe with a force constant of 40 N/m. When rsp was decreased to 0.1 or less, the measured size of the PB-rich domain relatively shrank; however, the height images of the PB-rich domain would take reverse (translating from the original light to dark) at rsp = 0.85. Force-probe measurements were carried out on the phase-separated regions by TM-AFM. According to the phase shift angle vs. rsp curve, it could be concluded that the different force exerting on the epoxy matrix or on the PB-rich domain might result in the height and phase image reversion. Furthermore, the indentation depth vs. rsp plot showed that with large tapping force (lower rsp), the indentation depth for the PB-rich domain was nearly identical for the epoxy resin matrix. PMID:22360980

  12. Automated method for the rapid and precise estimation of adherent cell culture characteristics from phase contrast microscopy images.

    PubMed

    Jaccard, Nicolas; Griffin, Lewis D; Keser, Ana; Macown, Rhys J; Super, Alexandre; Veraitch, Farlan S; Szita, Nicolas

    2014-03-01

    The quantitative determination of key adherent cell culture characteristics such as confluency, morphology, and cell density is necessary for the evaluation of experimental outcomes and to provide a suitable basis for the establishment of robust cell culture protocols. Automated processing of images acquired using phase contrast microscopy (PCM), an imaging modality widely used for the visual inspection of adherent cell cultures, could enable the non-invasive determination of these characteristics. We present an image-processing approach that accurately detects cellular objects in PCM images through a combination of local contrast thresholding and post hoc correction of halo artifacts. The method was thoroughly validated using a variety of cell lines, microscope models and imaging conditions, demonstrating consistently high segmentation performance in all cases and very short processing times (<1 s per 1,208 × 960 pixels image). Based on the high segmentation performance, it was possible to precisely determine culture confluency, cell density, and the morphology of cellular objects, demonstrating the wide applicability of our algorithm for typical microscopy image processing pipelines. Furthermore, PCM image segmentation was used to facilitate the interpretation and analysis of fluorescence microscopy data, enabling the determination of temporal and spatial expression patterns of a fluorescent reporter. We created a software toolbox (PHANTAST) that bundles all the algorithms and provides an easy to use graphical user interface. Source-code for MATLAB and ImageJ is freely available under a permissive open-source license. PMID:24037521

  13. Effects of phase and coupling between the vibrational modes on selective excitation in coherent anti-Stokes Raman scattering microscopy

    SciTech Connect

    Patel, Vishesha; Malinovsky, Vladimir S.; Malinovskaya, Svetlana

    2010-06-15

    Coherent anti-Stokes Raman scattering (CARS) microscopy has been a major tool of investigation of biological structures as it contains the vibrational signature of molecules. A quantum control method based on chirped pulse adiabatic passage was recently proposed for selective excitation of a predetermined vibrational mode in CARS microscopy [Malinovskaya and Malinovsky, Opt. Lett. 32, 707 (2007)]. The method utilizes the chirp sign variation at the peak pulse amplitude and gives a robust adiabatic excitation of the desired vibrational mode. Using this method, we investigate the impact of coupling between vibrational modes in molecules on controllability of excitation of the CARS signal. We analyze two models of two coupled two-level systems (TLSs) having slightly different transitional frequencies. The first model, featuring degenerate ground states of the TLSs, gives robust adiabatic excitation and maximum coherence in the resonant TLS for positive value of the chirp. In the second model, implying nondegenerate ground states in the TLSs, a population distribution is observed in both TLSs, resulting in a lack of selectivity of excitation and low coherence. It is shown that the relative phase and coupling between the TLSs play an important role in optimizing coherence in the desired vibrational mode and suppressing unwanted transitions in CARS microscopy.

  14. Automated method for the rapid and precise estimation of adherent cell culture characteristics from phase contrast microscopy images.

    PubMed

    Jaccard, Nicolas; Griffin, Lewis D; Keser, Ana; Macown, Rhys J; Super, Alexandre; Veraitch, Farlan S; Szita, Nicolas

    2014-03-01

    The quantitative determination of key adherent cell culture characteristics such as confluency, morphology, and cell density is necessary for the evaluation of experimental outcomes and to provide a suitable basis for the establishment of robust cell culture protocols. Automated processing of images acquired using phase contrast microscopy (PCM), an imaging modality widely used for the visual inspection of adherent cell cultures, could enable the non-invasive determination of these characteristics. We present an image-processing approach that accurately detects cellular objects in PCM images through a combination of local contrast thresholding and post hoc correction of halo artifacts. The method was thoroughly validated using a variety of cell lines, microscope models and imaging conditions, demonstrating consistently high segmentation performance in all cases and very short processing times (<1 s per 1,208 × 960 pixels image). Based on the high segmentation performance, it was possible to precisely determine culture confluency, cell density, and the morphology of cellular objects, demonstrating the wide applicability of our algorithm for typical microscopy image processing pipelines. Furthermore, PCM image segmentation was used to facilitate the interpretation and analysis of fluorescence microscopy data, enabling the determination of temporal and spatial expression patterns of a fluorescent reporter. We created a software toolbox (PHANTAST) that bundles all the algorithms and provides an easy to use graphical user interface. Source-code for MATLAB and ImageJ is freely available under a permissive open-source license.

  15. Repeated crack healing in MAX-phase ceramics revealed by 4D in situ synchrotron X-ray tomographic microscopy

    PubMed Central

    Sloof, Willem G.; Pei, Ruizhi; McDonald, Samuel A.; Fife, Julie L.; Shen, Lu; Boatemaa, Linda; Farle, Ann-Sophie; Yan, Kun; Zhang, Xun; van der Zwaag, Sybrand; Lee, Peter D.; Withers, Philip J.

    2016-01-01

    MAX phase materials are emerging as attractive engineering materials in applications where the material is exposed to severe thermal and mechanical conditions in an oxidative environment. The Ti2AlC MAX phase possesses attractive thermomechanical properties even beyond a temperature of 1000 K. An attractive feature of this material is its capacity for the autonomous healing of cracks when operating at high temperatures. Coupling a specialized thermomechanical setup to a synchrotron X-ray tomographic microscopy endstation at the TOMCAT beamline, we captured the temporal evolution of local crack opening and healing during multiple cracking and autonomous repair cycles at a temperature of 1500 K. For the first time, the rate and position dependence of crack repair in pristine Ti2AlC material and in previously healed cracks has been quantified. Our results demonstrate that healed cracks can have sufficient mechanical integrity to make subsequent cracks form elsewhere upon reloading after healing. PMID:26972608

  16. Repeated crack healing in MAX-phase ceramics revealed by 4D in situ synchrotron X-ray tomographic microscopy.

    PubMed

    Sloof, Willem G; Pei, Ruizhi; McDonald, Samuel A; Fife, Julie L; Shen, Lu; Boatemaa, Linda; Farle, Ann-Sophie; Yan, Kun; Zhang, Xun; van der Zwaag, Sybrand; Lee, Peter D; Withers, Philip J

    2016-01-01

    MAX phase materials are emerging as attractive engineering materials in applications where the material is exposed to severe thermal and mechanical conditions in an oxidative environment. The Ti2AlC MAX phase possesses attractive thermomechanical properties even beyond a temperature of 1000 K. An attractive feature of this material is its capacity for the autonomous healing of cracks when operating at high temperatures. Coupling a specialized thermomechanical setup to a synchrotron X-ray tomographic microscopy endstation at the TOMCAT beamline, we captured the temporal evolution of local crack opening and healing during multiple cracking and autonomous repair cycles at a temperature of 1500 K. For the first time, the rate and position dependence of crack repair in pristine Ti2AlC material and in previously healed cracks has been quantified. Our results demonstrate that healed cracks can have sufficient mechanical integrity to make subsequent cracks form elsewhere upon reloading after healing. PMID:26972608

  17. Digitally tunable, wide-band amplitude, phase, and frequency detection for atomic-resolution scanning force microscopy.

    PubMed

    Khan, Z; Leung, C; Tahir, B A; Hoogenboom, B W

    2010-07-01

    Frequency-modulation atomic force microscopy (FM-AFM) relies on an accurate tracking of the resonance frequency of a scanning probe. It is now used in environments ranging from ultrahigh vacuum to aqueous solutions, for slow and for fast imaging, with probes resonating from a few kilohertz up to several megahertz. Here we present a versatile experimental setup that detects amplitude, phase, and frequency of AFM probes for resonance frequencies up to 15 MHz and with >70 kHz maximum bandwidth for amplitude/phase detection. We provide generic parameter settings for variable-bandwidth frequency detection and test these using our setup. The signal-to-noise ratio of the frequency detector is sufficiently high to record atomic-resolution images of mica by FM-AFM in aqueous solution.

  18. Dual-wavelength common-path digital holographic microscopy for quantitative phase imaging based on lateral shearing interferometry.

    PubMed

    Di, Jianglei; Li, Ying; Xie, Min; Zhang, Jiwei; Ma, Chaojie; Xi, Teli; Li, Enpu; Zhao, Jianlin

    2016-09-10

    A dual-wavelength common-path digital holographic microscopy based on a single parallel glass plate is presented to achieve quantitative phase imaging, which combines the dual-wavelength technique with lateral shearing interferometry. Two illumination laser beams with different wavelengths (λ1=532  nm and λ2=632.8  nm) are reflected by the front and back surfaces of the parallel glass plate to create the lateral shear and form the digital hologram, and then the hologram is reconstructed to obtain the phase distribution with a synthetic wavelength Λ=3339.8  nm. The experimental configuration is very compact, with the advantages of vibration resistance and measurement range extension. The experimental results of the laser-ablated pit, groove, and staircase specimens show the feasibility of the proposed configuration. PMID:27661364

  19. Simultaneous calorimetric and polarization microscopy investigations of light induced changes over phase transitions in a liquid crystal-napthopyran mixture

    NASA Astrophysics Data System (ADS)

    Paoloni, S.; Mercuri, F.; Marinelli, M.; Pizzoferrato, R.; Zammit, U.; Kosa, T.; Sukhomlinova, L.; Taheri, B.

    2015-10-01

    We have studied the specific heat and the thermal conductivity in a 4-(n-octyl)-4'-cyanobiphenyl liquid crystal (LC)-photochromic molecules mixture, before, during, and after the photo-activation of the dispersed photochromic molecules, over both the smectic A-nematic and the nematic-isotropic phase transitions. The evaluation of the specific heat has enabled the determination of the changes of the phase transition characteristics induced by the photochromic molecules photoisomerization, while that of the thermal conductivity could be used to monitor the modifications induced in the average LC molecular orientation. The polarization microscopy imaging of the sample texture constituted a valuable support for the interpretation of the obtained thermal conductivity results.

  20. 3D X-ray Strain Microscopy in Two-Phase Composites at Submicron Length Scale

    SciTech Connect

    Barabash, Rozaliya; Bei, Hongbin; Ice, Gene E; Gao, Yanfei; Barabash, Oleg M

    2011-01-01

    Author note: Part of this research summary is based on findings first reported in Refs. [3-5, 18]. Renewed interest in composite materials is driven by the fact that their mechanical properties can be superior to those of individual constituent phases. Interfaces between the phases are the key elements responsible for the unique micro-mechanisms of plastic deformation in composites. In this study the depth-dependent residual strain distributed in the two phases and partitioned across the composite interfaces is directly measured at submicron length-scale using X-ray microdiffraction and compared to a detailed simulation within the framework of micromechanical stress analysis. Interface strength is determined from the analysis of the so-called slip zone caused by the near-surface stress relaxation. Two examples are discussed including NiAl/Mo and Ni/Mo composites.

  1. Phase retrieval using polychromatic illumination for transmission X-ray microscopy.

    PubMed

    Liu, Yijin; Andrews, Joy C; Wang, Junyue; Meirer, Florian; Zhu, Peiping; Wu, Ziyu; Pianetta, Piero

    2011-01-17

    An alternative method for quantitative phase retrieval in a transmission X-ray microscope system at sub-50-nm resolution is presented. As an alternative to moving the sample in the beam direction in order to analyze the propagation-introduced phase effect, we have illuminated the TXM using X-rays of different energy without any motor movement in the TXM system. Both theoretical analysis and experimental studies have confirmed the feasibility and the advantage of our method, because energy tuning can be performed with very high energy resolution using a double crystal monochromator at a synchrotron beam line, and there is zero motor error in TXM system in our approach. High-spatial-resolution phase retrieval is accomplished using the proposed method. PMID:21263593

  2. Color-coded LED microscopy for multi-contrast and quantitative phase-gradient imaging.

    PubMed

    Lee, Donghak; Ryu, Suho; Kim, Uihan; Jung, Daeseong; Joo, Chulmin

    2015-12-01

    We present a multi-contrast microscope based on color-coded illumination and computation. A programmable three-color light-emitting diode (LED) array illuminates a specimen, in which each color corresponds to a different illumination angle. A single color image sensor records light transmitted through the specimen, and images at each color channel are then separated and utilized to obtain bright-field, dark-field, and differential phase contrast (DPC) images simultaneously. Quantitative phase imaging is also achieved based on DPC images acquired with two different LED illumination patterns. The multi-contrast and quantitative phase imaging capabilities of our method are demonstrated by presenting images of various transparent biological samples. PMID:26713205

  3. Phase retrieval using polychromatic illumination for transmission X-ray microscopy

    PubMed Central

    Liu, Yijin; Andrews, Joy C.; Wang, Junyue; Meirer, Florian; Zhu, Peiping; Wu, Ziyu; Pianetta, Piero

    2011-01-01

    An alternative method for quantitative phase retrieval in a transmission X-ray microscope system at sub-50-nm resolution is presented. As an alternative to moving the sample in the beam direction in order to analyze the propagation-introduced phase effect, we have illuminated the TXM using X-rays of different energy without any motor movement in the TXM system. Both theoretical analysis and experimental studies have confirmed the feasibility and the advantage of our method, because energy tuning can be performed with very high energy resolution using a double crystal monochromator at a synchrotron beam line, and there is zero motor error in TXM system in our approach. High-spatial-resolution phase retrieval is accomplished using the proposed method. PMID:21263593

  4. Optofluidic bioimaging platform for quantitative phase imaging of lab on a chip devices using digital holographic microscopy.

    PubMed

    Pandiyan, Vimal Prabhu; John, Renu

    2016-01-20

    We propose a versatile 3D phase-imaging microscope platform for real-time imaging of optomicrofluidic devices based on the principle of digital holographic microscopy (DHM). Lab-on-chip microfluidic devices fabricated on transparent polydimethylsiloxane (PDMS) and glass substrates have attained wide popularity in biological sensing applications. However, monitoring, visualization, and characterization of microfluidic devices, microfluidic flows, and the biochemical kinetics happening in these devices is difficult due to the lack of proper techniques for real-time imaging and analysis. The traditional bright-field microscopic techniques fail in imaging applications, as the microfluidic channels and the fluids carrying biological samples are transparent and not visible in bright light. Phase-based microscopy techniques that can image the phase of the microfluidic channel and changes in refractive indices due to the fluids and biological samples present in the channel are ideal for imaging the fluid flow dynamics in a microfluidic channel at high resolutions. This paper demonstrates three-dimensional imaging of a microfluidic device with nanometric depth precisions and high SNR. We demonstrate imaging of microelectrodes of nanometric thickness patterned on glass substrate and the microfluidic channel. Three-dimensional imaging of a transparent PDMS optomicrofluidic channel, fluid flow, and live yeast cell flow in this channel has been demonstrated using DHM. We also quantify the average velocity of fluid flow through the channel. In comparison to any conventional bright-field microscope, the 3D depth information in the images illustrated in this work carry much information about the biological system under observation. The results demonstrated in this paper prove the high potential of DHM in imaging optofluidic devices; detection of pathogens, cells, and bioanalytes on lab-on-chip devices; and in studying microfluidic dynamics in real time based on phase changes. PMID

  5. Insights into the nanoscale lateral and vertical phase separation in organic bulk heterojunctions via scanning probe microscopy.

    PubMed

    Chintala, R; Tait, J G; Eyben, P; Voroshazi, E; Surana, S; Fleischmann, C; Conard, T; Vandervorst, W

    2016-02-14

    Solution processed polymer (donor) and fullerene (acceptor) bulk heterojunctions are widely used as the photo active layer in organic solar cells. Intimate mixing of these two materials is essential for efficient charge separation and transport. Identifying relative positions of acceptor and donor rich regions in the bulk heterojunction with nanometer scale precision is crucial in understanding intricate details of operation. In this work, a combination of Ar(+)2000 gas cluster ion beam and scanning probe microscopy is used to examine the lateral and vertical phase separation within regio-regular poly(3-hexylthiophene)(P3HT):phenyl-C60-butyric acid methyl ester (PCBM) bulk heterojunction. While the Ar(+)2000 gas cluster ion beam is used as a sputter tool to expose the underneath layers, scanning probe microscopy techniques are used to obtain two-dimensional (2D) electrical maps (with sub-2 nm lateral resolution). The electrical mapping is decoded to chemical composition, essentially producing lateral and vertical maps of phase separation. Thermal stress causes large PCBM-rich hillocks to form, and consequently affecting the balance of P3HT:PCBM heterojunctions, hence a negative impact on the efficiency of the solar cell. We further developed a method to analyze the efficiency of exciton dissociation based on the current maps and a loss of 20% in efficiency is observed for thermally degraded samples compared to fresh un-annealed samples. PMID:26810305

  6. Deciphering the internal complexity of living cells with quantitative phase microscopy: a multiscale approach

    NASA Astrophysics Data System (ADS)

    Martinez-Torres, Cristina; Laperrousaz, Bastien; Berguiga, Lotfi; Boyer-Provera, Elise; Elezgaray, Juan; Nicolini, Franck E.; Maguer-Satta, Veronique; Arneodo, Alain; Argoul, Françoise

    2015-09-01

    The distribution of refractive indices (RIs) of a living cell contributes in a nonintuitive manner to its optical phase image and quite rarely can be inverted to recover its internal structure. The interpretation of the quantitative phase images of living cells remains a difficult task because (1) we still have very little knowledge on the impact of its internal macromolecular complexes on the local RI and (2) phase changes produced by light propagation through the sample are mixed with diffraction effects by the internal cell bodies. We propose to implement a two-dimensional wavelet-based contour chain detection method to distinguish internal boundaries based on their greatest optical path difference gradients. These contour chains correspond to the highest image phase contrast and follow the local RI inhomogeneities linked to the intracellular structural intricacy. Their statistics and spatial distribution are the morphological indicators suited for comparing cells of different origins and/or to follow their transformation in pathologic situations. We use this method to compare nonadherent blood cells from primary and laboratory culture origins and to assess the internal transformation of hematopoietic stem cells by the transduction of the BCR-ABL oncogene responsible for the chronic myelogenous leukemia.

  7. DESIGN OF A MICROFABRICATED, TWO-ELECTRODE PHASE-CONTRAST ELEMENTSUITABLE FOR ELECTRON MICROSCOPY

    SciTech Connect

    Cambie, Rossana; Downing, Kenneth H.; Typke, Dieter; Glaeser,Robert M.; Jin, Jian

    2006-09-20

    A miniature electrostatic element has been designed to selectively apply a ninety-degree phase shift to the unscattered beam in the back focal plane of the objective lens, in order to realize Zernike-type, in-focus phase contrast in an electron microscope. The design involves a cylindrically shaped, biased-voltage electrode, which is surrounded by a concentric grounded electrode. Electrostatic calculations have been used to determine that the fringing fields in the region of the scattered electron beams will cause a negligible phase shift as long as the ratio of electrode length to the transverse feature-size is greater than 5:1. Unlike the planar, three-electrode einzel lens originally proposed by Boersch for the same purpose, this new design does not require insulating layers to separate the biased and grounded electrodes, and it can thus be produced by a very simple microfabrication process. Scanning electron microscope images confirm that mechanically robust devices with feature sizes of {approx}1 {micro}m can be easily fabricated. Preliminary experimental images demonstrate that these devices do apply a 90-degree phase shift between the scattered and unscattered electrons, as expected.

  8. III-V on silicon: Observation of gallium phosphide anti-phase disorder by low-energy electron microscopy

    NASA Astrophysics Data System (ADS)

    Döscher, Henning; Borkenhagen, Benjamin; Lilienkamp, Gerhard; Daum, Winfried; Hannappel, Thomas

    2011-08-01

    The formation of anti-phase disorder is a major obstacle in the heteroepitaxy of III-V semiconductors on silicon. For an investigation of the anti-phase domain (APD) structure of GaP/Si(100) samples on mesoscopic length scales, we applied dark-field imaging in a low-energy electron microscope (LEEM) to thin GaP films grown on Si(100) substrates by metal organic vapor phase epitaxy (MOVPE). A contamination-free transfer of the samples from the MOVPE ambient to the ultra-high vacuum chamber of the microscope ensured that the atomically well-ordered, P-rich (2 × 2)/c(4 × 2) reconstruction of the surface was preserved. Mutually perpendicular oriented domains of the characteristic GaP(100) reconstruction identify the APDs in the GaP film at the surface and enabled us to achieve high contrast LEEM images. Striped patterns of APDs reflect the regular terrasse structure of the two-domain Si(100)(2 × 1) substrate far away from defects. APDs in the proximity of the defects have larger lateral extensions and are arranged in target pattern-like structures around the defects. In contrast to transmission electron microscopy, which was also applied in a specific dark-field mode for comparison, the characterization of anti-phase disorder by LEEM is non-destructive, does not require elaborate sample preparation, and addresses extended length scales.

  9. Programmable aperture microscopy: A computational method for multi-modal phase contrast and light field imaging

    NASA Astrophysics Data System (ADS)

    Zuo, Chao; Sun, Jiasong; Feng, Shijie; Zhang, Minliang; Chen, Qian

    2016-05-01

    We demonstrate a simple and cost-effective programmable aperture microscope to realize multi-modal computational imaging by integrating a programmable liquid crystal display (LCD) into a conventional wide-field microscope. The LCD selectively modulates the light distribution at the rear aperture of the microscope objective, allowing numerous imaging modalities, such as bright field, dark field, differential phase contrast, quantitative phase imaging, multi-perspective imaging, and full resolution light field imaging to be achieved and switched rapidly in the same setup, without requiring specialized hardwares and any moving parts. We experimentally demonstrate the success of our method by imaging unstained cheek cells, profiling microlens array, and changing perspective views of thick biological specimens. The post-exposure refocusing of a butterfly mouthpart and RFP-labeled dicot stem cross-section is also presented to demonstrate the full resolution light field imaging capability of our system for both translucent and fluorescent specimens.

  10. High-speed line-scanning confocal holographic microscopy for quantitative phase imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Liu, Changgeng; Knitter, Sebastian; Cong, Zhilong; Sencan, Ikbal; Cao, Hui; Choma, Michael A.

    2016-03-01

    We present a high speed, phase-sensitive, line-scanning reflectance confocal interference microscope. We achieved rapid confocal imaging using a fast line-scan camera and quantitative phase imaging using off-axis digital holography on a 1D, line-by-line basis. In our prototype system, a He-Ne laser (~1.2 mW) was used to demonstrate the principle of operation. Using a 20 kHz line scan rate (1024 pixels per line scan), we achieved a video-rate frame rate of 20 Hz for 1024x500 pixel en-face confocal images (20 MHz total pixel rate). By using an objective lens of a NA 0.65, we achieved an axial and lateral resolution of ~3.5 micrometers and ~0.8 micrometers, respectively. By z-stack imaging of a custom silicon target with a stepped structure, we confirmed that the axial sectioning of the interference microscope is similar to that of a traditional line-scan confocal microscope (our microscope with the reference arm blocked). The utility of phase-sensitive holographic detection in line-scan confocal was demonstrated in two ways. First, using a custom axial height phantom fabricated using chrome deposition, we demonstrated variations in phase corresponding to heights in the 100 nm range with a contrast-to-noise ratio of ~31 dB. Second, we demonstrate digital refocusing of an out-of-focus holographic image. The mechanism of confocality in our line-scan system is 1D physical pinholing. Our ongoing work aims to add an additional mechanism of confocality by using low spatial coherence sources to impose interferometric pinholing.

  11. Phase imaging microscopy for the diagnostics of plasma-cell interaction

    NASA Astrophysics Data System (ADS)

    Ohene, Yolanda; Marinov, Ilya; de Laulanié, Lucie; Dupuy, Corinne; Wattelier, Benoit; Starikovskaia, Svetlana

    2015-06-01

    Phase images of biological specimens were obtained by the method of Quadriwave Lateral Shearing Interferometry (QWLSI). The QWLSI technique produces, at high resolution, phase images of the cells having been exposed to a plasma treatment and enables the quantitative analysis of the changes in the surface area of the cells over time. Morphological changes in the HTori normal thyroid cells were demonstrated using this method. There was a comparison of the cell behaviour between control cells, cells treated by plasma of a nanosecond dielectric barrier discharge, including cells pre-treated by catalase, and cells treated with an equivalent amount of H2O2. The major changes in the cell membrane morphology were observed at only 5 min after the plasma treatment. The primary role of reactive oxygen species (ROS) in this degradation is suggested. Deformation and condensation of the cell nucleus were observed 2-3 h after the treatment and are supposedly related to apoptosis induction. The coupling of the phase QWLSI with immunofluorescence imaging would give a deeper insight into the mechanisms of plasma induced cell death.

  12. Cryo X-ray microscopy with high spatial resolution in amplitude and phase contrast.

    PubMed

    Schneider, G

    1998-11-01

    The resolution of transmission X-ray microscopes (TXMs) using zone plate optics is presently about 30 nm. Theory and experiments presented here show that this resolution can be obtained in radiation sensitive hydrated biological material by using shock frozen samples. For this purpose the interaction of X-rays with matter and the image formation with zone plates is described. For the first time the influence of the limited apertures of the condenser and the zone plate objective are in included in calculations of the image contrast, the photon density and radiation dose required for the object illumination. Model considerations show that lowest radiation dose and high image contrast are obtained in optimized phase contrast which exploits absorption as well as phase shift. The damaging effect of the absorbed X-rays is quantitatively evaluated by radiation-induced kinetics showing that cryogenic samples are structurally stable. To verify these theoretical models the TXM was modified to allow imaging of frozen-hydrated samples at atmospheric pressure. Details inside cells and algae as small as 35 nm are visible at 2.4 nm wavelength in amplitude contrast mode. At this resolution the cryogenic samples show no structural changes. As predicted, optimized phase contrast shows structures inside the frozen-hydrated objects with high contrast. Stereo-pair images of algae reveal the 3D organization of the organelles. Element analysis and micro-tomography of whole cryogenic cells are possible. PMID:9836467

  13. Lab on chip optical imaging of biological sample by quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Memmolo, P.; Miccio, L.; Merola, F.; Gennari, O.; Mugnano, M.; Netti, P. A.; Ferraro, P.

    2015-03-01

    Quantitative imaging and three dimensional (3D) morphometric analysis of flowing and not-adherent cells is an important aspect for diagnostic purposes at Lab on Chip scale. Diagnostics tools need to be quantitative, label-free and, as much as possible, accurate. In recent years digital holography (DH) has been improved to be considered as suitable diagnostic method in several research field. In this paper we demonstrate that DH can be used for retrieving 3D morphometric data for sorting and diagnosis aims. Several techniques exist for 3D morphological study as optical coherent tomography and confocal microscopy, but they are not the best choice in case of dynamic events as flowing samples. Recently, a DH approach, based on shape from silhouette algorithm (SFS), has been developed for 3D shape display and calculation of cells biovolume. Such approach, adopted in combination with holographic optical tweezers (HOT) was successfully applied to cells with convex shape. Unfortunately, it's limited to cells with convex surface as sperm cells or diatoms. Here, we demonstrate an improvement of such procedure. By decoupling thickness information from refractive index ones and combining this with SFS analysis, 3D shape of concave cells is obtained. Specifically, the topography contour map is computed and used to adjust the 3D shape retrieved by the SFS algorithm. We prove the new procedure for healthy red blood cells having a concave surface in their central region. Experimental results are compared with theoretical model.

  14. Quantitative phase imaging of biological cells and tissues using singleshot white light interference microscopy and phase subtraction method for extended range of measurement

    NASA Astrophysics Data System (ADS)

    Mehta, Dalip Singh; Sharma, Anuradha; Dubey, Vishesh; Singh, Veena; Ahmad, Azeem

    2016-03-01

    We present a single-shot white light interference microscopy for the quantitative phase imaging (QPI) of biological cells and tissues. A common path white light interference microscope is developed and colorful white light interferogram is recorded by three-chip color CCD camera. The recorded white light interferogram is decomposed into the red, green and blue color wavelength component interferograms and processed it to find out the RI for different color wavelengths. The decomposed interferograms are analyzed using local model fitting (LMF)" algorithm developed for reconstructing the phase map from single interferogram. LMF is slightly off-axis interferometric QPI method which is a single-shot method that employs only a single image, so it is fast and accurate. The present method is very useful for dynamic process where path-length changes at millisecond level. From the single interferogram a wavelength-dependent quantitative phase imaging of human red blood cells (RBCs) are reconstructed and refractive index is determined. The LMF algorithm is simple to implement and is efficient in computation. The results are compared with the conventional phase shifting interferometry and Hilbert transform techniques.

  15. Characterization of LiBC by phase-contrast scanning transmission electron microscopy.

    PubMed

    Krumeich, Frank; Wörle, Michael; Reibisch, Philipp; Nesper, Reinhard

    2014-08-01

    LiBC was used as a model compound for probing the applicability of phase-contrast (PC) imaging in an aberration-corrected scanning transmission electron microscope (STEM) to visualize lithium distributions. In the LiBC structure, boron and carbon are arranged to hetero graphite layers between which lithium is incorporated. The crystal structure is reflected in the PC-STEM images recorded perpendicular to the layers. The experimental images and their defocus dependence match with multi-slice simulations calculated utilizing the reciprocity principle. The observation that a part of the Li positions is not occupied is likely an effect of the intense electron beam triggering Li displacement.

  16. Zernike phase contrast cryo-electron microscopy reveals 100 kDa component in a protein complex

    NASA Astrophysics Data System (ADS)

    Wu, Yi-Min; Wang, Chun-Hsiung; Chang, Jen-wei; Chen, Yi-yun; Miyazaki, Naoyuki; Murata, Kazuyoshi; Nagayama, Kuniaki; Chang, Wei-Hau

    2013-12-01

    Cryo-electron microscopy (cryo-EM) has become a powerful technique for obtaining near atomic structures for large protein assemblies or large virus particles, but the application to protein particles smaller than 200-300 kDa has been hampered by the feeble phase contrast obtained for such small samples and the limited number of electrons tolerated by them without incurring excessive radiation damage. By implementing a thin-film quarter-wave phase plate to a cryo-EM, Nagayama, one of the present authors, has recently restored the long-lost very low spatial frequencies, generating in-focus phase contrast superior to that of conventional defocusing phase contrast, and successfully applied the so-called Zernike phase-plate cryo-EM to target various biological samples in native state. Nevertheless, the sought-after goal of using enhanced phase contrast to reveal a native protein as small as 100 kDa waits to be realized. Here, we report a study in which 200 kV Zernike phase-plate cryo-EM with a plate cut-on periodicity of 36 nm was applied to visualize 100 kDa components of various protein complexes, including the small domains on the surface of an icosahedral particle of ˜38 nm derived from the dragon grouper nervous necrosis virus (DGNNV) and the labile sub-complex dissociated from yeast RNA polymerase III of 17 nm. In the former case, we observed a phase contrast reversal phenomenon at the centre of the icosahedral particle and traced its root cause to the near matching of the cut-on size and the particle size. In summary, our work has demonstrated that Zernike phase-plate implementation can indeed expand the size range of proteins that can be successfully investigated by cryo-EM, opening the door for countless proteins. Finally, we briefly discuss the possibility of using a transfer lens system to enlarge the cut-on periodicity without further miniaturizing the plate pinhole.

  17. Dynamic DIC by digital holography microscopy for enhancing phase-contrast visualization.

    PubMed

    Miccio, Lisa; Finizio, Andrea; Puglisi, Roberto; Balduzzi, Donatella; Galli, Andrea; Ferraro, Pietro

    2011-01-13

    Differential image contrast (DIC), through the numerical managing and manipulation of complex wavefronts obtained by digital holography (DH), is investigated. We name the approach Dynamical Differential Holographic Image Contrast (DDHIC). DDHIC dispenses from special optics and/or complex setup configurations with moveable components, as usually occurs in classical DIC, that is not well-suited for investigating objects experiencing dynamic evolution during the measurement. In fact, the technique presented here, is useful for floating samples since it allows, from a single recording, to set a posteriori the best conditions for DIC imaging in conjunction with the numerical focusing feature of DH. By DDHIC, the movies can be easily built-up to offering dynamic representation of phase-contrast along all directions, thus improving the visualization. Furthermore, the dynamic representation is useful for making the proper choice of other key parameters of DIC such as the amount of shear and the bias, with the aim to optimize the visualized phase-contrast imaging as favorite representation for bio-scientists. Investigation is performed on various biological samples.

  18. Phase-contrast imaging in aberration-corrected scanning transmission electron microscopy.

    PubMed

    Krumeich, F; Müller, E; Wepf, R A

    2013-06-01

    Although the presence of phase-contrast information in bright field images recorded with a scanning transmission electron microscope (STEM) has been known for a long time, its systematic exploitation for the structural characterization of materials began only with the availability of aberration-corrected microscopes that allow sufficiently large illumination angles. Today, phase-contrast STEM (PC-STEM) imaging represents an increasingly important alternative to the well-established HRTEM method. In both methods, the image contrast is coherently generated and thus depends not only on illumination and collection angles but on defocus and specimen thickness as well. By PC-STEM, a projection of the crystal potential is obtained in thin areas, with the scattering sites being represented either with dark or bright contrast at two different defocus values which are both close to Gaussian defocus. This imaging behavior can be further investigated by image simulations performed with standard HRTEM simulation software based on the principle of reciprocity. As examples for the application of this method, PC-STEM results obtained on metal nanoparticles and dodecagonal quasicrystals dd-(Ta,V)₁.₆Te are discussed.

  19. Interaction potentials of anisotropic nanocrystals from the trajectory sampling of particle motion using in situ liquid phase transmission electron microscopy

    DOE PAGESBeta

    Chen, Qian; Cho, Hoduk; Manthiram, Karthish; Yoshida, Mark; Ye, Xingchen; Alivisatos, A. Paul

    2015-03-23

    We demonstrate a generalizable strategy to use the relative trajectories of pairs and groups of nanocrystals, and potentially other nanoscale objects, moving in solution which can now be obtained by in situ liquid phase transmission electron microscopy (TEM) to determine the interaction potentials between nanocrystals. Such nanoscale interactions are crucial for collective behaviors and applications of synthetic nanocrystals and natural biomolecules, but have been very challenging to measure in situ at nanometer or sub-nanometer resolution. Here we use liquid phase TEM to extract the mathematical form of interaction potential between nanocrystals from their sampled trajectories. We show the power ofmore » this approach to reveal unanticipated features of nanocrystal–nanocrystal interactions by examining the anisotropic interaction potential between charged rod-shaped Au nanocrystals (Au nanorods); these Au nanorods assemble, in a tip-to-tip fashion in the liquid phase, in contrast to the well-known side-by-side arrangements commonly observed for drying-mediated assembly. These observations can be explained by a long-range and highly anisotropic electrostatic repulsion that leads to the tip-selective attachment. As a result, Au nanorods stay unassembled at a lower ionic strength, as the electrostatic repulsion is even longer-ranged. Our study not only provides a mechanistic understanding of the process by which metallic nanocrystals assemble but also demonstrates a method that can potentially quantify and elucidate a broad range of nanoscale interactions relevant to nanotechnology and biophysics.« less

  20. Interaction Potentials of Anisotropic Nanocrystals from the Trajectory Sampling of Particle Motion using in Situ Liquid Phase Transmission Electron Microscopy

    PubMed Central

    2015-01-01

    We demonstrate a generalizable strategy to use the relative trajectories of pairs and groups of nanocrystals, and potentially other nanoscale objects, moving in solution which can now be obtained by in situ liquid phase transmission electron microscopy (TEM) to determine the interaction potentials between nanocrystals. Such nanoscale interactions are crucial for collective behaviors and applications of synthetic nanocrystals and natural biomolecules, but have been very challenging to measure in situ at nanometer or sub-nanometer resolution. Here we use liquid phase TEM to extract the mathematical form of interaction potential between nanocrystals from their sampled trajectories. We show the power of this approach to reveal unanticipated features of nanocrystal–nanocrystal interactions by examining the anisotropic interaction potential between charged rod-shaped Au nanocrystals (Au nanorods); these Au nanorods assemble, in a tip-to-tip fashion in the liquid phase, in contrast to the well-known side-by-side arrangements commonly observed for drying-mediated assembly. These observations can be explained by a long-range and highly anisotropic electrostatic repulsion that leads to the tip-selective attachment. As a result, Au nanorods stay unassembled at a lower ionic strength, as the electrostatic repulsion is even longer-ranged. Our study not only provides a mechanistic understanding of the process by which metallic nanocrystals assemble but also demonstrates a method that can potentially quantify and elucidate a broad range of nanoscale interactions relevant to nanotechnology and biophysics. PMID:27162944

  1. Automated Method for the Rapid and Precise Estimation of Adherent Cell Culture Characteristics from Phase Contrast Microscopy Images

    PubMed Central

    Jaccard, Nicolas; Griffin, Lewis D; Keser, Ana; Macown, Rhys J; Super, Alexandre; Veraitch, Farlan S; Szita, Nicolas

    2014-01-01

    The quantitative determination of key adherent cell culture characteristics such as confluency, morphology, and cell density is necessary for the evaluation of experimental outcomes and to provide a suitable basis for the establishment of robust cell culture protocols. Automated processing of images acquired using phase contrast microscopy (PCM), an imaging modality widely used for the visual inspection of adherent cell cultures, could enable the non-invasive determination of these characteristics. We present an image-processing approach that accurately detects cellular objects in PCM images through a combination of local contrast thresholding and post hoc correction of halo artifacts. The method was thoroughly validated using a variety of cell lines, microscope models and imaging conditions, demonstrating consistently high segmentation performance in all cases and very short processing times (<1 s per 1,208 × 960 pixels image). Based on the high segmentation performance, it was possible to precisely determine culture confluency, cell density, and the morphology of cellular objects, demonstrating the wide applicability of our algorithm for typical microscopy image processing pipelines. Furthermore, PCM image segmentation was used to facilitate the interpretation and analysis of fluorescence microscopy data, enabling the determination of temporal and spatial expression patterns of a fluorescent reporter. We created a software toolbox (PHANTAST) that bundles all the algorithms and provides an easy to use graphical user interface. Source-code for MATLAB and ImageJ is freely available under a permissive open-source license. Biotechnol. Bioeng. 2014;111: 504–517. © 2013 Wiley Periodicals, Inc. PMID:24037521

  2. Dynamic observation of an atom-sized gold wire by phase electron microscopy.

    PubMed

    Takai, Y; Kawasaki, T; Kimura, Y; Ikuta, T; Shimizu, R

    2001-09-01

    A single-atom-sized gold wire was successfully observed in real time by a newly developed defocus-image modulation processing electron microscope. Because of phase retrieval processing with spherical aberration correction, the single-atom strand wire was observed with high contrast and without contrast blurring. By carefully looking at the atomic distance, the contrast, and the dynamic behavior of the wire, we recognized that there are two stages of the wire. In the first stage the wire maintained the atomic distance in the bulk crystal, but in the second stage the wire showed the atomic distance of the nearest-neighbor atoms with weaker contrast. The gold wire was rather stable for a few seconds under strong electron beam illumination.

  3. Multiplexed off-axis interferometric phase microscopy for dynamic cell measurements

    NASA Astrophysics Data System (ADS)

    Shaked, Natan T.; Girshovitz, Pinhas; Frenklach, Irena

    2015-03-01

    We present a new approach of optically multiplexing several off-axis interferograms on the same digital camera, each of which encodes a different field of view of the sample. Since the fringes of these interferograms are in different directions, as obtained experimentally by the optical system, we are able to double or even triple the amount of information that can be acquired in a single camera exposure, with the same number of camera pixels, while sharing the camera dynamic range. We show that this method can partially solve the problem of limited off-axis interferometric field of view due to low-coherence illumination. Our experimental demonstrations include quantitative phase imaging of microscopic diatom shells, fast swimming sperm cells and microorganisms, and contracting cardiomyocytes.

  4. Helium ion microscopy based wall thickness and surface roughness analysis of polymer foams obtained from high internal phase emulsion.

    PubMed

    Rodenburg, C; Viswanathan, P; Jepson, M A E; Liu, X; Battaglia, G

    2014-04-01

    Due to their wide range of applications, porous polymers obtained from high internal phase emulsions have been widely studied using scanning electron microscopy. However, due to their lack of electrical conductivity, quantitative information of wall thicknesses and surface roughness, which are of particular interest to tissue engineering, has not been obtained. Here, Helium Ion Microscopy is used to examine uncoated polymer foams and some very strong but unexpected contrast is observed, the origin of which is established here. Based on this analysis, a method for the measurement of wall thickness variations and wall roughness measurements has been developed, based on the modeling of Helium ion transmission. The results presented here indicate that within the walls of the void structure there exist small features with height variations of ~30 nm and wall thickness variations from ~100 nm to larger 340 nm in regions surrounding interconnecting windows within the structure. The suggested imaging method is applicable to other porous carbon based structures with wall thicknesses in the range of 40-340 nm.

  5. Rapid, High-Throughput Tracking of Bacterial Motility in 3D via Phase-Contrast Holographic Video Microscopy

    PubMed Central

    Cheong, Fook Chiong; Wong, Chui Ching; Gao, YunFeng; Nai, Mui Hoon; Cui, Yidan; Park, Sungsu; Kenney, Linda J.; Lim, Chwee Teck

    2015-01-01

    Tracking fast-swimming bacteria in three dimensions can be extremely challenging with current optical techniques and a microscopic approach that can rapidly acquire volumetric information is required. Here, we introduce phase-contrast holographic video microscopy as a solution for the simultaneous tracking of multiple fast moving cells in three dimensions. This technique uses interference patterns formed between the scattered and the incident field to infer the three-dimensional (3D) position and size of bacteria. Using this optical approach, motility dynamics of multiple bacteria in three dimensions, such as speed and turn angles, can be obtained within minutes. We demonstrated the feasibility of this method by effectively tracking multiple bacteria species, including Escherichia coli, Agrobacterium tumefaciens, and Pseudomonas aeruginosa. In addition, we combined our fast 3D imaging technique with a microfluidic device to present an example of a drug/chemical assay to study effects on bacterial motility. PMID:25762336

  6. Insights into the nanoscale lateral and vertical phase separation in organic bulk heterojunctions via scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Chintala, R.; Tait, J. G.; Eyben, P.; Voroshazi, E.; Surana, S.; Fleischmann, C.; Conard, T.; Vandervorst, W.

    2016-02-01

    Solution processed polymer (donor) and fullerene (acceptor) bulk heterojunctions are widely used as the photo active layer in organic solar cells. Intimate mixing of these two materials is essential for efficient charge separation and transport. Identifying relative positions of acceptor and donor rich regions in the bulk heterojunction with nanometer scale precision is crucial in understanding intricate details of operation. In this work, a combination of Ar+2000 gas cluster ion beam and scanning probe microscopy is used to examine the lateral and vertical phase separation within regio-regular poly(3-hexylthiophene)(P3HT):phenyl-C60-butyric acid methyl ester (PCBM) bulk heterojunction. While the Ar+2000 gas cluster ion beam is used as a sputter tool to expose the underneath layers, scanning probe microscopy techniques are used to obtain two-dimensional (2D) electrical maps (with sub-2 nm lateral resolution). The electrical mapping is decoded to chemical composition, essentially producing lateral and vertical maps of phase separation. Thermal stress causes large PCBM-rich hillocks to form, and consequently affecting the balance of P3HT:PCBM heterojunctions, hence a negative impact on the efficiency of the solar cell. We further developed a method to analyze the efficiency of exciton dissociation based on the current maps and a loss of 20% in efficiency is observed for thermally degraded samples compared to fresh un-annealed samples.Solution processed polymer (donor) and fullerene (acceptor) bulk heterojunctions are widely used as the photo active layer in organic solar cells. Intimate mixing of these two materials is essential for efficient charge separation and transport. Identifying relative positions of acceptor and donor rich regions in the bulk heterojunction with nanometer scale precision is crucial in understanding intricate details of operation. In this work, a combination of Ar+2000 gas cluster ion beam and scanning probe microscopy is used to examine the

  7. Alterations of filopodia by near infrared photoimmunotherapy: evaluation with 3D low-coherent quantitative phase microscopy

    PubMed Central

    Nakamura, Yuko; Nagaya, Tadanobu; Sato, Kazuhide; Harada, Toshiko; Okuyama, Shuhei; Choyke, Peter L.; Yamauchi, Toyohiko; Kobayashi, Hisataka

    2016-01-01

    Filopodia are highly organized cellular membrane structures that facilitate intercellular communication. Near infrared photoimmunotherapy (NIR-PIT) is a newly developed cancer treatment that causes necrotic cell death. Three-dimensional low-coherent quantitative phase microscopy (3D LC-QPM) is based on a newly established low-coherent interference microscope designed to obtain serial topographic images of the cellular membrane. Herein, we report rapid involution of filopodia after NIR-PIT using 3D LC-QPM. For 3T3/HER2 cells, the number of filopodia decreased immediately after treatment with significant differences. Volume and relative height of 3T3/HER2 cells increased immediately after NIR light exposure, but significant differences were not observed. Thus, disappearance of filopodia, evaluated by 3D LC-QPM, is an early indicator of cell membrane damage after NIR-PIT. PMID:27446702

  8. Alterations of filopodia by near infrared photoimmunotherapy: evaluation with 3D low-coherent quantitative phase microscopy.

    PubMed

    Nakamura, Yuko; Nagaya, Tadanobu; Sato, Kazuhide; Harada, Toshiko; Okuyama, Shuhei; Choyke, Peter L; Yamauchi, Toyohiko; Kobayashi, Hisataka

    2016-07-01

    Filopodia are highly organized cellular membrane structures that facilitate intercellular communication. Near infrared photoimmunotherapy (NIR-PIT) is a newly developed cancer treatment that causes necrotic cell death. Three-dimensional low-coherent quantitative phase microscopy (3D LC-QPM) is based on a newly established low-coherent interference microscope designed to obtain serial topographic images of the cellular membrane. Herein, we report rapid involution of filopodia after NIR-PIT using 3D LC-QPM. For 3T3/HER2 cells, the number of filopodia decreased immediately after treatment with significant differences. Volume and relative height of 3T3/HER2 cells increased immediately after NIR light exposure, but significant differences were not observed. Thus, disappearance of filopodia, evaluated by 3D LC-QPM, is an early indicator of cell membrane damage after NIR-PIT. PMID:27446702

  9. A phase-contrast microscopy-based method for modeling the mechanical behavior of mesenchymal stem cells.

    PubMed

    Saeed, Mayssam; Sharabani-Yosef, Orna; Weihs, Daphne; Gefen, Amit

    2016-10-01

    We present three-dimensional (3D) finite element (FE) models of single, mesenchymal stem cells (MSCs), generated from images obtained by optical phase-contrast microscopy and used to quantify the structural responses of the studied cells to externally applied mechanical loads. Mechanical loading has been shown to affect cell morphology and structure, phenotype, motility and other biological functions. Cells experience mechanical loads naturally, yet under prolonged or sizable loading, damage and cell death may occur, which motivates research regarding the structural behavior of loaded cells. For example, near the weight-bearing boney prominences of the buttocks of immobile persons, tissues may become highly loaded, eventually leading to massive cell death that manifests as pressure ulcers. Cell-specific computational models have previously been developed by our group, allowing simulations of cell deformations under compressive or stretching loads. These models were obtained by reconstructing specific cell structures from series of 2D fluorescence, confocal image-slices, requiring cell-specific fluorescent-staining protocols and costly (confocal) microscopy equipment. Alternative modeling approaches represent cells simply as half-spheres or half-ellipsoids (i.e. idealized geometries), which neglects the curvature details of the cell surfaces associated with changes in concentrations of strains and stresses. Thus, we introduce here for the first time an optical image-based FE modeling, where loads are simulated on reconstructed 3D geometrical cell models from a single 2D, phase-contrast image. Our novel modeling method eliminates the need for confocal imaging and fluorescent staining preparations (both expensive), and makes cell-specific FE modeling affordable and accessible to the biomechanics community. We demonstrate the utility of this cost-effective modeling method by performing simulations of compression of MSCs embedded in a gel. PMID:26856632

  10. A phase-contrast microscopy-based method for modeling the mechanical behavior of mesenchymal stem cells.

    PubMed

    Saeed, Mayssam; Sharabani-Yosef, Orna; Weihs, Daphne; Gefen, Amit

    2016-10-01

    We present three-dimensional (3D) finite element (FE) models of single, mesenchymal stem cells (MSCs), generated from images obtained by optical phase-contrast microscopy and used to quantify the structural responses of the studied cells to externally applied mechanical loads. Mechanical loading has been shown to affect cell morphology and structure, phenotype, motility and other biological functions. Cells experience mechanical loads naturally, yet under prolonged or sizable loading, damage and cell death may occur, which motivates research regarding the structural behavior of loaded cells. For example, near the weight-bearing boney prominences of the buttocks of immobile persons, tissues may become highly loaded, eventually leading to massive cell death that manifests as pressure ulcers. Cell-specific computational models have previously been developed by our group, allowing simulations of cell deformations under compressive or stretching loads. These models were obtained by reconstructing specific cell structures from series of 2D fluorescence, confocal image-slices, requiring cell-specific fluorescent-staining protocols and costly (confocal) microscopy equipment. Alternative modeling approaches represent cells simply as half-spheres or half-ellipsoids (i.e. idealized geometries), which neglects the curvature details of the cell surfaces associated with changes in concentrations of strains and stresses. Thus, we introduce here for the first time an optical image-based FE modeling, where loads are simulated on reconstructed 3D geometrical cell models from a single 2D, phase-contrast image. Our novel modeling method eliminates the need for confocal imaging and fluorescent staining preparations (both expensive), and makes cell-specific FE modeling affordable and accessible to the biomechanics community. We demonstrate the utility of this cost-effective modeling method by performing simulations of compression of MSCs embedded in a gel.

  11. The measurement of red blood cell volume change induced by Ca2+ based on full field quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Lee, Seungrag; Lee, Ji Yong; Yang, Wenzhong; Kim, Dug Young

    2009-02-01

    We present the measurement of red blood cell (RBC) volume change induced by Ca2+ for a live cell imaging with full field quantitative phase microscopy (FFQPM). FFQPM is based on the Mach-Zehnder interferometer combined with an inverted microscopy system. We present the effective method to obtain a clear image and an accurate volume of the cells. An edge detection technique is used to accurately resolve the boundary between the cell line and the suspension medium. The measurement of the polystyrene bead diameter and volume has been demonstrated the validity of our proposed method. The measured phase profile can be easily converted into thickness profile. The measured polystyrene bead volume and the simulated result are about 14.74 μm3 and 14.14 μm3, respectively. The experimental results of our proposed method agree well with the simulated results within less than 4 %. We have also measured the volume variation of a single RBC on a millisecond time scale. Its mean volume is 54.02 μm3 and its standard deviation is 0.52 μm3. With the proposed system, the shape and volume changes of RBC induced by the increased intracellular Ca2+ are measured after adding ionophore A23187. A discocyte RBC is deformed to a spherocyte due to the increased intracellular Ca2+ in RBC. The volume of the spherocyte is 47.88 μm3 and its standard deviation is 0.19 μm3. We have demonstrated that the volume measurement technique is easy, accurate, and robust method with high volume sensitivity (<0.0000452 μm3) and this provides the ability to study a biological phenomenon in Hematology.

  12. Reduction of frequency noise and frequency shift by phase shifting elements in frequency modulation atomic force microscopy

    SciTech Connect

    Kobayashi, Kei; Yamada, Hirofumi; Matsushige, Kazumi

    2011-03-15

    We recently reported the analysis of the frequency noise in the frequency modulation atomic force microscopy (FM-AFM) both in high-Q and low-Q environments [Rev. Sci. Instrum. 80, 043708 (2009)]. We showed in the paper that the oscillator noise, the frequency fluctuation of the oscillator, becomes prominent in the modulation frequency lower than f{sub 0}/2Q, where f{sub 0} and Q are the resonance frequency and Q-factor. The magnitude of the oscillator noise is determined by the slope of the phase versus frequency curve of the cantilever at f{sub 0}. However, in actual FM-AFM in liquids, the phase versus frequency curve may not be always ideal because of the existence of various phase shifting elements (PSEs). For example, the spurious resonance peaks caused by the acoustic excitation and a band-pass filter in the self-oscillation loop increase the slope of the phase versus frequency curve. Due to those PSEs, the effective Q-factor is often increased from the intrinsic Q-factor of the cantilever. In this article, the frequency noise in the FM-AFM system with the PSEs in the self-oscillation loop is analyzed to show that the oscillator noise is reduced by the increase of the effective Q-factor. It is also shown that the oscillation frequency deviates from the resonance frequency due to the increase of the effective Q-factor, thereby causing the reduction in the frequency shift signal with the same factor. Therefore the increase of the effective Q-factor does not affect the signal-to-noise ratio in the frequency shift measurement, but it does affect the quantitativeness of the measured force in the FM-AFM. Furthermore, the reduction of the frequency noise and frequency shift by the increase of the effective Q-factor were confirmed by the experiments.

  13. The crystalline nanocluster phase as a medium for structural and spectroscopic studies of light absorption of photosensitizer dyes on semiconductor surfaces.

    PubMed

    Benedict, Jason B; Coppens, Philip

    2010-03-10

    The crystalline nanocluster phase, in which nanoscale metal oxide clusters are self-assembled in three-dimensional periodic arrays, is described. The crystalline assembly of nanoparticles functionalized with technologically relevant ligands offers the opportunity to obtain unambiguous structural information that can be combined with theoretical calculations based on the known geometry and used to interpret spectroscopic and other information. A series of Ti/O clusters up to approximately 2.0 nm in diameter have been synthesized and functionalized with the adsorbents catechol and isonicotinic acid. Whereas the isonicotinate is always adsorbed in a bridging monodentate mode, four different adsorption modes of catechol have been identified. The particles show a significantly larger variation of the Ti-O distances than observed in the known TiO(2) phases and exhibit both sevenfold overcoordination and five- and fourfold undercoordination of the Ti atoms. Theoretical calculations show only a moderate dependence of the catecholate net charge on the geometry of adsorption. All of the catechol-functionalized clusters have a deep-red color due to penetration of the highest occupied catechol levels into the band gap of the Ti/O particles. Spectroscopic measurements of the band gap of the Ti(17) cluster are in good agreement with the theoretical values and show a blue shift of approximately 0.22 eV relative to those reported for anatase nanoparticles.

  14. High-Resolution Scanning Tunneling Microscopy of Fully Hydrated Ripple-Phase Bilayers

    PubMed Central

    Woodward IV, J. T.; Zasadzinski, J. A.

    1997-01-01

    A modified freeze-fracture replication technique for use with the scanning tunneling microscope (STM) has provided a quantitative, high-resolution description of the waveform and amplitude of rippled bilayers in the Pβ, phase of dimyristoylphosphatidylcholine (DMPC) in excess water. The ripples are uniaxial and asymmetrical, with a temperature-dependent amplitude of 2.4 nm near the chain melting temperature that decreases to zero at the chain crystallization temperature. The wavelength of 11 nm does not change with temperature. The observed ripple shape and the temperature-induced structural changes are not predicted by any current theory. Calibration and reproducibility of the STM/replica technique were tested with replicas of well-characterized bilayers of cadmium arachidate on mica that provide regular 5.5-nm steps. STM images were analyzed using a cross-correlation averaging program to eliminate the effects of noise and the finite size and shapes of the metal grains that make up the replica. The correlation averaging allowed us to develop a composite ripple profile averaged over hundreds of individual ripples measured on different samples with different STM tips. The STM/replica technique avoids many of the previous artifacts of biological STM imaging and can be used to examine a variety of periodic hydrated lipid and protein samples at a lateral resolution of about 1 nm and a vertical resolution of about 0.3 nm. This resolution is superior to conventional and tapping mode AFM of soft biological materials; the technique is substrate-free, and the conductive and chemically uniform replicas make image interpretation simple and direct. ImagesFIGURE 1FIGURE 2FIGURE 3FIGURE 5 PMID:9017222

  15. Transmission electron microscopy convergent beam measurement of S-phase volume fraction in Al-Li-Cu-Mg-Zr alloy (8090)

    SciTech Connect

    Martin, J.W. ): Xiaoxin, X. )

    1990-12-01

    A statistical study of S-phase particle distribution in thin foils, measuring foil thickness by a transmission electron microscopy convergent beam technique, has shown the change of S-phase average length and volume fraction by varying treatments prior to artificial aging. The investigation shows that the average length and volume fraction of S-phase particles increases with increasing degrees of predeformation in the Al-Li-Cu-Mg-Zr alloy studied.

  16. GPU-based rapid reconstruction of cellular 3D refractive index maps from tomographic phase microscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Dardikman, Gili; Shaked, Natan T.

    2016-03-01

    We present highly parallel and efficient algorithms for real-time reconstruction of the quantitative three-dimensional (3-D) refractive-index maps of biological cells without labeling, as obtained from the interferometric projections acquired by tomographic phase microscopy (TPM). The new algorithms are implemented on the graphic processing unit (GPU) of the computer using CUDA programming environment. The reconstruction process includes two main parts. First, we used parallel complex wave-front reconstruction of the TPM-based interferometric projections acquired at various angles. The complex wave front reconstructions are done on the GPU in parallel, while minimizing the calculation time of the Fourier transforms and phase unwrapping needed. Next, we implemented on the GPU in parallel the 3-D refractive index map retrieval using the TPM filtered-back projection algorithm. The incorporation of algorithms that are inherently parallel with a programming environment such as Nvidia's CUDA makes it possible to obtain real-time processing rate, and enables high-throughput platform for label-free, 3-D cell visualization and diagnosis.

  17. A hybrid analog-digital phase-locked loop for frequency mode non-contact scanning probe microscopy.

    PubMed

    Mehta, M M; Chandrasekhar, V

    2014-01-01

    Non-contact scanning probe microscopy (SPM) has developed into a powerful technique to image many different properties of samples. The conventional method involves monitoring the amplitude, phase, or frequency of a cantilever oscillating at or near its resonant frequency as it is scanned across the surface of a sample. For high Q factor cantilevers, monitoring the resonant frequency is the preferred method in order to obtain reasonable scan times. This can be done by using a phase-locked-loop (PLL). PLLs can be obtained as commercial integrated circuits, but these do not have the frequency resolution required for SPM. To increase the resolution, all-digital PLLs requiring sophisticated digital signal processors or field programmable gate arrays have also been implemented. We describe here a hybrid analog/digital PLL where most of the components are implemented using discrete analog integrated circuits, but the frequency resolution is provided by a direct digital synthesis chip controlled by a simple peripheral interface controller (PIC) microcontroller. The PLL has excellent frequency resolution and noise, and can be controlled and read by a computer via a universal serial bus connection. PMID:24517775

  18. One- and two-dimensional infrared spectroscopic studies of solution-phase homogeneous catalysis and spin-forbidden reactions

    SciTech Connect

    Sawyer, Karma Rae

    2008-12-01

    Understanding chemical reactions requires the knowledge of the elementary steps of breaking and making bonds, and often a variety of experimental techniques are needed to achieve this goal. The initial steps occur on the femto- through picosecond time-scales, requiring the use of ultrafast spectroscopic methods, while the rate-limiting steps often occur more slowly, requiring alternative techniques. Ultrafast one and two-dimensional infrared and step-scan FTIR spectroscopies are used to investigate the photochemical reactions of four organometallic complexes. The analysis leads to a detailed understanding of mechanisms that are general in nature and may be applicable to a variety of reactions.

  19. Horse heart cytochrome c entrapped into the hydrated liquid-crystalline phases of phytantriol: X-ray diffraction and Raman spectroscopic characterization.

    PubMed

    Misiūnas, Audrius; Niaura, Gediminas; Barauskas, Justas; Meškys, Rolandas; Rutkienė, Rasa; Razumas, Valdemaras; Nylander, Tommy

    2012-07-15

    Small angle X-ray diffraction (SAXD), resonance Raman (RR) spectroscopy with 413 nm excitation, and non-resonance Raman technique with 785 nm excitation were used to probe the influence of entrapped cytochrome c (Cyt c) on the structure of hydrated phytantriol (Phyt) liquid-crystalline phases as well as conformational changes of heme group and secondary structure of the protein. SAXD measurements indicated that incorporation of Cyt c affects both nanostructure dimensions and type of liquid-crystalline phases of hydrated Phyt. The unit cell dimensions decrease with increasing Cyt c concentration for all phases. In addition, protein perturbs the nanostructure of Q(230) and Q(224) liquid-crystalline phases of hydrated Phyt to such an extent that they transform into the Q(229) phase with the Im3m space group. RR data revealed that entrapment of oxidized Cyt c into the Q(230) phase at 1 wt.% content results in near complete reduction of central iron ion of the heme group, while its low-spin state and six-ligand coordination configuration are preserved. Based on the analysis of heme out-of-plane folding vibration near 568 cm(-1) (γ(21)) and ν(48) mode at 633 cm(-1), it was demonstrated that the protein matrix tension on the heme group is relaxed upon incorporation of protein into Q(230) phase. Non-resonant Raman bands of difference spectra showed the preservation of α-helix secondary structure of Cyt c in the liquid-crystalline phase at relatively high (5 wt.%) content. The Cyt c induced spectroscopic changes of Phyt bands were found to be similar as decrease in temperature.

  20. Direct spectroscopic evidence for phase competition between the pseudogap and superconductivity in Bi2Sr2CaCu2O(8+δ).

    PubMed

    Hashimoto, Makoto; Nowadnick, Elizabeth A; He, Rui-Hua; Vishik, Inna M; Moritz, Brian; He, Yu; Tanaka, Kiyohisa; Moore, Robert G; Lu, Donghui; Yoshida, Yoshiyuki; Ishikado, Motoyuki; Sasagawa, Takao; Fujita, Kazuhiro; Ishida, Shigeyuki; Uchida, Shinichi; Eisaki, Hiroshi; Hussain, Zahid; Devereaux, Thomas P; Shen, Zhi-Xun

    2015-01-01

    In the high-temperature (T(c)) cuprate superconductors, a growing body of evidence suggests that the pseudogap phase, existing below the pseudogap temperature T*, is characterized by some broken electronic symmetries distinct from those associated with superconductivity. In particular, recent scattering experiments have suggested that charge ordering competes with superconductivity. However, no direct link of an interplay between the two phases has been identified from the important low-energy excitations. Here, we report an antagonistic singularity at T(c) in the spectral weight of Bi2Sr2CaCu2O(8+δ) as compelling evidence for phase competition, which persists up to a high hole concentration p ~ 0.22. Comparison with theoretical calculations confirms that the singularity is a signature of competition between the order parameters for the pseudogap and superconductivity. The observation of the spectroscopic singularity at finite temperatures over a wide doping range provides new insights into the nature of the competitive interplay between the two orders and the complex phase diagram near the pseudogap critical point.

  1. MR Spectroscopic Imaging of Peripheral Zone in Prostate Cancer Using a 3T MRI Scanner: Endorectal versus External Phased Array Coils.

    PubMed

    Nagarajan, Rajakumar; Margolis, Daniel Ja; Raman, Steven S; Ouellette, David; Sarma, Manoj K; Reiter, Robert E; Thomas, M Albert

    2013-01-01

    Magnetic resonance spectroscopic imaging (MRSI) detects alterations in major prostate metabolites, such as citrate (Cit), creatine (Cr), and choline (Ch). We evaluated the sensitivity and accuracy of three-dimensional MRSI of prostate using an endorectal compared to an external phased array "receive" coil on a 3T MRI scanner. Eighteen patients with prostate cancer (PCa) who underwent endorectal MR imaging and proton (1H) MRSI were included in this study. Immediately after the endorectal MRSI scan, the PCa patients were scanned with the external phased array coil. The endorectal coil-detected metabolite ratio [(Ch+Cr)/Cit] was significantly higher in cancer locations (1.667 ± 0.663) compared to non-cancer locations (0.978 ± 0.420) (P < 0.001). Similarly, for the external phased array, the ratio was significantly higher in cancer locations (1.070 ± 0.525) compared to non-cancer locations (0.521 ± 0.310) (P < 0.001). The sensitivity and accuracy of cancer detection were 81% and 78% using the endorectal 'receive' coil, and 69% and 75%, respectively using the external phased array 'receive' coil.

  2. Direct spectroscopic evidence for phase competition between the pseudogap and superconductivity in Bi2Sr2CaCu2O(8+δ).

    PubMed

    Hashimoto, Makoto; Nowadnick, Elizabeth A; He, Rui-Hua; Vishik, Inna M; Moritz, Brian; He, Yu; Tanaka, Kiyohisa; Moore, Robert G; Lu, Donghui; Yoshida, Yoshiyuki; Ishikado, Motoyuki; Sasagawa, Takao; Fujita, Kazuhiro; Ishida, Shigeyuki; Uchida, Shinichi; Eisaki, Hiroshi; Hussain, Zahid; Devereaux, Thomas P; Shen, Zhi-Xun

    2015-01-01

    In the high-temperature (T(c)) cuprate superconductors, a growing body of evidence suggests that the pseudogap phase, existing below the pseudogap temperature T*, is characterized by some broken electronic symmetries distinct from those associated with superconductivity. In particular, recent scattering experiments have suggested that charge ordering competes with superconductivity. However, no direct link of an interplay between the two phases has been identified from the important low-energy excitations. Here, we report an antagonistic singularity at T(c) in the spectral weight of Bi2Sr2CaCu2O(8+δ) as compelling evidence for phase competition, which persists up to a high hole concentration p ~ 0.22. Comparison with theoretical calculations confirms that the singularity is a signature of competition between the order parameters for the pseudogap and superconductivity. The observation of the spectroscopic singularity at finite temperatures over a wide doping range provides new insights into the nature of the competitive interplay between the two orders and the complex phase diagram near the pseudogap critical point. PMID:25362356

  3. Accelerated proton echo planar spectroscopic imaging (PEPSI) using GRAPPA with a 32-channel phased-array coil.

    PubMed

    Tsai, Shang-Yueh; Otazo, Ricardo; Posse, Stefan; Lin, Yi-Ru; Chung, Hsiao-Wen; Wald, Lawrence L; Wiggins, Graham C; Lin, Fa-Hsuan

    2008-05-01

    Parallel imaging has been demonstrated to reduce the encoding time of MR spectroscopic imaging (MRSI). Here we investigate up to 5-fold acceleration of 2D proton echo planar spectroscopic imaging (PEPSI) at 3T using generalized autocalibrating partial parallel acquisition (GRAPPA) with a 32-channel coil array, 1.5 cm(3) voxel size, TR/TE of 15/2000 ms, and 2.1 Hz spectral resolution. Compared to an 8-channel array, the smaller RF coil elements in this 32-channel array provided a 3.1-fold and 2.8-fold increase in signal-to-noise ratio (SNR) in the peripheral region and the central region, respectively, and more spatial modulated information. Comparison of sensitivity-encoding (SENSE) and GRAPPA reconstruction using an 8-channel array showed that both methods yielded similar quantitative metabolite measures (P > 0.1). Concentration values of N-acetyl-aspartate (NAA), total creatine (tCr), choline (Cho), myo-inositol (mI), and the sum of glutamate and glutamine (Glx) for both methods were consistent with previous studies. Using the 32-channel array coil the mean Cramer-Rao lower bounds (CRLB) were less than 8% for NAA, tCr, and Cho and less than 15% for mI and Glx at 2-fold acceleration. At 4-fold acceleration the mean CRLB for NAA, tCr, and Cho was less than 11%. In conclusion, the use of a 32-channel coil array and GRAPPA reconstruction can significantly reduce the measurement time for mapping brain metabolites.

  4. Accelerated proton echo planar spectroscopic imaging (PEPSI) using GRAPPA with a 32-channel phased-array coil.

    PubMed

    Tsai, Shang-Yueh; Otazo, Ricardo; Posse, Stefan; Lin, Yi-Ru; Chung, Hsiao-Wen; Wald, Lawrence L; Wiggins, Graham C; Lin, Fa-Hsuan

    2008-05-01

    Parallel imaging has been demonstrated to reduce the encoding time of MR spectroscopic imaging (MRSI). Here we investigate up to 5-fold acceleration of 2D proton echo planar spectroscopic imaging (PEPSI) at 3T using generalized autocalibrating partial parallel acquisition (GRAPPA) with a 32-channel coil array, 1.5 cm(3) voxel size, TR/TE of 15/2000 ms, and 2.1 Hz spectral resolution. Compared to an 8-channel array, the smaller RF coil elements in this 32-channel array provided a 3.1-fold and 2.8-fold increase in signal-to-noise ratio (SNR) in the peripheral region and the central region, respectively, and more spatial modulated information. Comparison of sensitivity-encoding (SENSE) and GRAPPA reconstruction using an 8-channel array showed that both methods yielded similar quantitative metabolite measures (P > 0.1). Concentration values of N-acetyl-aspartate (NAA), total creatine (tCr), choline (Cho), myo-inositol (mI), and the sum of glutamate and glutamine (Glx) for both methods were consistent with previous studies. Using the 32-channel array coil the mean Cramer-Rao lower bounds (CRLB) were less than 8% for NAA, tCr, and Cho and less than 15% for mI and Glx at 2-fold acceleration. At 4-fold acceleration the mean CRLB for NAA, tCr, and Cho was less than 11%. In conclusion, the use of a 32-channel coil array and GRAPPA reconstruction can significantly reduce the measurement time for mapping brain metabolites. PMID:18429025

  5. Effect of confinement on phase-separation processes in a polymer blend observed by laser scanning confocal microscopy.

    PubMed

    Jinnai, Hiroshi; Kitagishi, Hitoshi; Hamano, Kazuki; Nishikawa, Yukihiro; Takahashi, Masaoki

    2003-02-01

    Structure self-assembling in the late stage spinodal decomposition of a polymer blend at its critical composition has been explored by laser-scanning confocal microscopy with particular emphasis on the effects of confinement (dimensionality) and preferential wetting of solid surface by one of the constituent polymers. A mixture of deuterated polybutadiene and polybutadiene (PB) with relatively narrow thickness (D congruent with 55 microm) was observed in three dimensions over the entire thickness. Formation of a wetting layer was clearly observed near the glass surface, while a bicontinuous structure evolved in the middle of the specimen. Global as well as local features of the phase-separating structures were quantified by several structural parameters, e.g., characteristic length Lambda(m)(t), structure factor S(q), interfacial area per unit volume Sigma(t), probability densities of interfacial curvatures P(H,K;t), etc. (t is a phase-separation time). From the time evolution of these structural parameters, a deviation from the self-similar growth of a bicontinuous structure was found to occur at a transition time, t(tr), at which a scaled thickness, D/Lambda(m), approached unity. The breakdown of the self-similar growth was most sensitively observed by the local characteristics, i.e., Sigma(t) and P(H,K;t). On the other hand, the global characteristic, Lambda(m)(t), did not provide useful insight into the effects of dimensionality. It turned out that the bicontinuous structure, initially growing with dynamical self-similarity, eventually transformed into a "columnlike" structure (at t congruent with t(tr)) in which cylindrical PB-rich domains bridge the upper and lower PB wetting layers. PMID:12636702

  6. Effect of confinement on phase-separation processes in a polymer blend observed by laser scanning confocal microscopy

    NASA Astrophysics Data System (ADS)

    Jinnai, Hiroshi; Kitagishi, Hitoshi; Hamano, Kazuki; Nishikawa, Yukihiro; Takahashi, Masaoki

    2003-02-01

    Structure self-assembling in the late stage spinodal decomposition of a polymer blend at its critical composition has been explored by laser-scanning confocal microscopy with particular emphasis on the effects of confinement (dimensionality) and preferential wetting of solid surface by one of the constituent polymers. A mixture of deuterated polybutadiene and polybutadiene (PB) with relatively narrow thickness (D≅55 μm) was observed in three dimensions over the entire thickness. Formation of a wetting layer was clearly observed near the glass surface, while a bicontinuous structure evolved in the middle of the specimen. Global as well as local features of the phase-separating structures were quantified by several structural parameters, e.g., characteristic length Λm(t), structure factor S(q), interfacial area per unit volume Σ(t), probability densities of interfacial curvatures P(H,K;t), etc. (t is a phase-separation time). From the time evolution of these structural parameters, a deviation from the self-similar growth of a bicontinuous structure was found to occur at a transition time, ttr, at which a scaled thickness, D/Λm, approached unity. The breakdown of the self-similar growth was most sensitively observed by the local characteristics, i.e., Σ(t) and P(H,K;t). On the other hand, the global characteristic, Λm(t), did not provide useful insight into the effects of dimensionality. It turned out that the bicontinuous structure, initially growing with dynamical self-similarity, eventually transformed into a “columnlike” structure (at t≅ttr) in which cylindrical PB-rich domains bridge the upper and lower PB wetting layers.

  7. Identifying the crystallinity, phase, and arsenic uptake of the nanomineral schwertmannite using analytical high resolution transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    French, R. A.; Kim, B.; Murayama, M.; Hochella, M. F.

    2010-12-01

    Schwertmannite, an iron oxyhydroxide sulfate nanomineral, plays a significant role in the geochemistry of acid mine drainage (AMD) as a metastable phase with respect to goethite and by retaining toxic metals, e.g. arsenic [1]. Schwertmannite’s characteristic morphology is needles 100-300 nm long and only 5-10 nm in diameter extending from a dense aggregate. The poorly-and nano-crystalline nature of this mineral requires using high resolution electron microscopy (HRTEM) to be fully characterized. We used HRTEM to identify the polyphasic nature of natural samples of schwertmannite collected from the Iberian Pyrite Belt in Spain. In order to analyze the dense core, samples were prepared in thin section using an ultramicrotome. Data on a sample identified as pure schwertmannite through powder XRD shows the presence of 5-10 nm goethite nanocrystals making up a significant portion of one of the nanoneedle tips (Figure 1). These nanocrystals exhibit lattice fringes and faceted surfaces, both of which match that expected for goethite. The great majority of the nanoneedles are poorly-crystalline (no lattice fringes) with atomically rough surfaces which may be highly active in the uptake of As. The presence of a range of phases and crystallinities in this sample demonstrate incipient stages of the mechanism that results in transformation of schwertmannite to goethite. Further analytical TEM analyses will help us track sorption/desorption, as well as the specific locations of As within these materials upon initial formation, as well as during transformation. [1] Acero et al. (2006) GCA 70, 4130-4139. Figure 1. HRTEM image of 'schwertmannite' nanoneedle with FFT data (inset).

  8. Dynamic phase microscopy, a new method to detect viable and killed spores and to estimate the heterogeneity of spore populations

    NASA Astrophysics Data System (ADS)

    Tychinsky, Vladimir P.; Mulyukin, Andrey L.; Lisovskii, Vitalii V.; Nikolaev, Yury A.; Kretushev, Aleksander V.; Vyshenskaya, Tatyana V.; Suzina, Nataliya E.; Duda, Vitalii I.; El-Registan, Galina I.

    One of the challenging tasks in monitoring studies is to estimate heterogeneity of microbial populations by the physiological state and potential viability of individual cells, especially with regard of their ability to withstand various environmental assaults. Previously, we described some approaches based on electron microscopy methods to discriminate vegetative, dormant, and dead cells in both aged microbial cultures and environmental samples, including permafrost. We propose to extend the arsenal of microscopy methods for monitoring studies by a new non-invasive and informative method - dynamic phase microscopy (DPM). The substantial advantage of DPM is that it gives quantitative (digitized) data of undestroyed (living) microscopic objects, exemplified in our work by Bacillus licheniformis spores. Using DPM made it possible to record interference images of objects (spores) and to produce picture of their "phase thickness" (PT) that is the optical path difference in nm. Thus, it was demonstrated the remarkable difference in the PT of spores at different physiological states: dormant, germinating, and heat-killed spores had PT values of 80, 40-50, and 20 nm, respectively. The other found criterion to distinguish between spores was the PT fluctuations. In contrast to dormant and killed spores, the PT of germinating spores oscillated with amplitude of up to 7 nm, with typical frequencies of 1.3 and 3.4 Hz. A combination of the recorded PT values and PT fluctuations gave a key to detect viable and dead cells. Under the conditions that did not support germination (the lack of nutrients), we were able to follow the response of a single dormant spore and a spore population to heating from 25 °C to 70 °C. Thus, a very small temperature change (from 40 °C to 42 °C) under conditions non-favorable for germination, caused a drastic decrease in the spores' PT; the second drop in the PT values was observed during heating from 60 °C to 70 °C. These changes were

  9. Three-dimensional imaging of chemical phase transformations at the nanoscale with full-field transmission X-ray microscopy

    PubMed Central

    Meirer, Florian; Cabana, Jordi; Liu, Yijin; Mehta, Apurva; Andrews, Joy C.; Pianetta, Piero

    2011-01-01

    The ability to probe morphology and phase distribution in complex systems at multiple length scales unravels the interplay of nano- and micrometer-scale factors at the origin of macroscopic behavior. While different electron- and X-ray-based imaging techniques can be combined with spectroscopy at high resolutions, owing to experimental time limitations the resulting fields of view are too small to be representative of a composite sample. Here a new X-ray imaging set-up is proposed, combining full-field transmission X-ray microscopy (TXM) with X-ray absorption near-edge structure (XANES) spectroscopy to follow two-dimensional and three-dimensional morphological and chemical changes in large volumes at high resolution (tens of nanometers). TXM XANES imaging offers chemical speciation at the nanoscale in thick samples (>20 µm) with minimal preparation requirements. Further, its high throughput allows the analysis of large areas (up to millimeters) in minutes to a few hours. Proof of concept is provided using battery electrodes, although its versatility will lead to impact in a number of diverse research fields. PMID:21862859

  10. Three-dimensional imaging of chemical phase transformations at the nanoscale with full-field transmission X-ray microscopy.

    PubMed

    Meirer, Florian; Cabana, Jordi; Liu, Yijin; Mehta, Apurva; Andrews, Joy C; Pianetta, Piero

    2011-09-01

    The ability to probe morphology and phase distribution in complex systems at multiple length scales unravels the interplay of nano- and micrometer-scale factors at the origin of macroscopic behavior. While different electron- and X-ray-based imaging techniques can be combined with spectroscopy at high resolutions, owing to experimental time limitations the resulting fields of view are too small to be representative of a composite sample. Here a new X-ray imaging set-up is proposed, combining full-field transmission X-ray microscopy (TXM) with X-ray absorption near-edge structure (XANES) spectroscopy to follow two-dimensional and three-dimensional morphological and chemical changes in large volumes at high resolution (tens of nanometers). TXM XANES imaging offers chemical speciation at the nanoscale in thick samples (>20 µm) with minimal preparation requirements. Further, its high throughput allows the analysis of large areas (up to millimeters) in minutes to a few hours. Proof of concept is provided using battery electrodes, although its versatility will lead to impact in a number of diverse research fields. PMID:21862859

  11. Correlative transmission electron microscopy and electrical properties study of switchable phase-change random access memory line cells

    SciTech Connect

    Oosthoek, J. L. M.; Kooi, B. J.; Voogt, F. C.; Attenborough, K.; Verheijen, M. A.; Hurkx, G. A. M.; Gravesteijn, D. J.

    2015-02-14

    Phase-change memory line cells, where the active material has a thickness of 15 nm, were prepared for transmission electron microscopy (TEM) observation such that they still could be switched and characterized electrically after the preparation. The result of these observations in comparison with detailed electrical characterization showed (i) normal behavior for relatively long amorphous marks, resulting in a hyperbolic dependence between SET resistance and SET current, indicating a switching mechanism based on initially long and thin nanoscale crystalline filaments which thicken gradually, and (ii) anomalous behavior, which holds for relatively short amorphous marks, where initially directly a massive crystalline filament is formed that consumes most of the width of the amorphous mark only leaving minor residual amorphous regions at its edges. The present results demonstrate that even in (purposely) thick TEM samples, the TEM sample preparation hampers the probability to observe normal behavior and it can be debated whether it is possible to produce electrically switchable TEM specimen in which the memory cells behave the same as in their original bulk embedded state.

  12. The study on RBC characteristic in paroxysmal nocturnal hemoglobinuria (PNH) patients using common path interferometric quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Park, Byung Jun; Won, Youngjae; Kim, Byungyeon; Lee, Seungrag

    2016-03-01

    We have studied the RBC membrane properties between a normal RBC and a RBC in Paroxysrnal nocturnal hemoglobinuria (PNH) patient using common path interferometric quantitative phase microscopy (CPIQPM). CPIQPM system has provided the subnanometer optical path length sensitivity on a millisecond. We have measured the dynamic thickness fluctuations of a normal RBC membrane and a RBC membrane in PNH patient over the whole cell surface with CPIQPM. PNH is a rare and serious disease of blood featured by destruction of red blood cells (RBCs). This destruction happens since RBCs show the defect of protein which protects RBCs from the immune system. We have applied CPIQPM to study the characteristic of RBC membrane in PNH patient. We have shown the morphological shape, volume, and projected surface for both different RBC types. The results have showed both RBCs had the similar shape with donut, but membrane fluctuations in PNH patient was shown to reveal the difference of temporal properties compared with a normal RBC. In order to demonstrate the practical tool of the CPIQPM technique, we have also obtained the time series thickness fluctuation outside a cell.

  13. Scanning force microscopy study of phase segregation in fuel cell membrane materials as a function of solvent polarity and relative humidity

    SciTech Connect

    Hawley, Marilyn Emily; Kim, Yu S; Hjelm, Rex P

    2010-01-01

    Scanning force microscopy (SFM) phase imaging provides a powerful method for directly studying and comparing phase segregation in fuel cell membrane materials due to different preparation and under different temperature and hwnidity exposures. In this work, we explored two parameters that can influence phase segregation: the properties of the solvents used in casting membrane films and how these solvents alter phase segregation after exposure to boiling water as a function of time. SFM was used under ambient conditions to image phase segregation in Nafion samples prepared using five different solvents. Samples were then subjected to water vapor maintained at 100C for periods ranging from 30 minutes to three hours and re-imaged using the same phase imaging conditions. SFM shows what appears to be an increase in phase segregation as a function of solvent polarity that changes as a function of water exposure.

  14. Evaluation of the dark-medium objective lens in counting asbestos fibers by phase-contrast microscopy.

    PubMed

    Lee, Eun Gyung; Nelson, John H; Kashon, Michael L; Harper, Martin

    2015-06-01

    AIHA PAT chrysotile slides using the DM objective. The comparison of fiber count ratios (DM/standard) between the AIHA PAT chrysotile samples and chrysotile field samples indicates that there is a fraction of fibers in the PAT samples approaching the theoretical limit of visibility of the phase-contrast microscope with 3-degree phase-shift. These fibers become more clearly visible through the greater contrast from the phase plate absorption of the DM objective. However, as such fibers are not present in field samples, no difference in counts between the two objectives was observed in this study. The DM objective, therefore, could be allowed for routine fiber counting as it will maintain continuity with risk assessments based on earlier phase-contrast microscopy fiber counts from field samples. Published standard methods would need to be modified to allow a higher aperture specification for the objective. PMID:25737333

  15. Evaluation of the dark-medium objective lens in counting asbestos fibers by phase-contrast microscopy.

    PubMed

    Lee, Eun Gyung; Nelson, John H; Kashon, Michael L; Harper, Martin

    2015-06-01

    AIHA PAT chrysotile slides using the DM objective. The comparison of fiber count ratios (DM/standard) between the AIHA PAT chrysotile samples and chrysotile field samples indicates that there is a fraction of fibers in the PAT samples approaching the theoretical limit of visibility of the phase-contrast microscope with 3-degree phase-shift. These fibers become more clearly visible through the greater contrast from the phase plate absorption of the DM objective. However, as such fibers are not present in field samples, no difference in counts between the two objectives was observed in this study. The DM objective, therefore, could be allowed for routine fiber counting as it will maintain continuity with risk assessments based on earlier phase-contrast microscopy fiber counts from field samples. Published standard methods would need to be modified to allow a higher aperture specification for the objective.

  16. Review of quantitative phase-digital holographic microscopy: promising novel imaging technique to resolve neuronal network activity and identify cellular biomarkers of psychiatric disorders

    PubMed Central

    Marquet, Pierre; Depeursinge, Christian; Magistretti, Pierre J.

    2014-01-01

    Abstract. Quantitative phase microscopy (QPM) has recently emerged as a new powerful quantitative imaging technique well suited to noninvasively explore a transparent specimen with a nanometric axial sensitivity. In this review, we expose the recent developments of quantitative phase-digital holographic microscopy (QP-DHM). Quantitative phase-digital holographic microscopy (QP-DHM) represents an important and efficient quantitative phase method to explore cell structure and dynamics. In a second part, the most relevant QPM applications in the field of cell biology are summarized. A particular emphasis is placed on the original biological information, which can be derived from the quantitative phase signal. In a third part, recent applications obtained, with QP-DHM in the field of cellular neuroscience, namely the possibility to optically resolve neuronal network activity and spine dynamics, are presented. Furthermore, potential applications of QPM related to psychiatry through the identification of new and original cell biomarkers that, when combined with a range of other biomarkers, could significantly contribute to the determination of high risk developmental trajectories for psychiatric disorders, are discussed. PMID:26157976

  17. Investigation of dynamic morphological changes of cancer cells during photoimmuno therapy (PIT) by low-coherence quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Ogawa, Mikako; Yamauchi, Toyohiko; Iwai, Hidenao; Magata, Yasuhiro; Choyke, Peter L.; Kobayashi, Hisataka

    2014-03-01

    We have reported a new molecular-targeted cancer phototherapy, photoimmunotherapy (PIT), which killed implanted tumors in mice without side-effects. To understand the mechanism of cell killing with PIT, three-dimentional dynamic low-coherence quantitative phase microscopy (3D LC-QPM), a device developed by Hamamatsu Photonics K.K, was used to detect morphologic changes in cancer cells during PIT. 3T3/HER2 cells were incubated with anti-HER2 trastuzumab-IR700 (10 μg/mL, 0.1 μM as IR700) for 24 hours, then, three-dimensionally imaged with the LC-QPM during the exposure of two different optically filtered lights for excitation of IR700 (500-780 nm) and imaging (780-950 nm). For comparison with traditional PDT, the same experiments were performed with Photofrin (10 and 1 μM). Serial changes in the cell membrane were readily visualized on 3D LC-QPM. 3T3/HER2 cells began to swell rapidly after exposure to 500-780 nm light excitation. The cell volume reached a maximum within 1 min after continuous exposure, and then the cells appeared to burst. This finding suggests that PIT damages the cell membrane by photo-reaction inducing an influx of water into the cell causing swelling and bursting of the cells. Interestingly, even after only 5 seconds of light exposure, the cells demonstrated swelling and bursting albeit more slowly, implying that sufficient cumulative damage occurs on the cell membrane to induce lethal damage to cells even at minimal light exposure. Similar but non-selective membrane damage was shown in PDT-treated cells Photofrin. Thus, PIT induces sufficient damage to the cell membrane within 5 seconds to induce rapid necrotic cell death which can be observed directly with 3D LC-QPM. Further investigation is needed to evaluate the biochemical mechanisms underlying PIT-induced cellular membrane damage.

  18. Comparative Raman spectroscopic study of phase stability and anharmonic effects in AZr2(PO4)3 (A = K, Rb and Cs)

    NASA Astrophysics Data System (ADS)

    Kamali, K.; Ravindran, T. R.; Ravi, C.

    2016-02-01

    AZr2(PO4)3 (A = Na, K, Rb, Cs) are a set of framework structured compounds that exhibit tunable ultralow thermal expansion over the wide temperature range of 293-1273 K. We report a systematic Raman spectroscopic investigation on AZr2(PO4)3 (A = K, Rb and Cs) compounds as a function of temperature in the range 80-860 K and pressures of up to 32 GPa. To get insight into the thermal expansion property, phonon anharmonicity has been investigated by studying the temperature and pressure dependence of Raman peak shifts and line widths and computed bulk modulus. We have compared the phase transition and amorphization pressures of the various members of AZr2(PO4)3 to account for the stability of the ambient rhombohedral phase. We find that unlike most of the anomalous thermal expansion materials, in AZr2(PO4)3 (A = K, Rb and Cs), the phonons that are anharmonic with temperature do not necessarily exhibit anharmonicity with pressure.

  19. Noble gases in oxidized residue prepared from the Saratov L4 chondrite and Raman spectroscopic study of residues to characterize phase Q

    NASA Astrophysics Data System (ADS)

    Matsuda, Jun-Ichi; Morishita, Kazuhiko; Nara, Masayuki; Amari, Sachiko

    2016-01-01

    We analyzed noble gases in an oxidized residue prepared from a HF-HCl residue of the Saratov L4 chondrite. The Ar, Kr, and Xe concentrations in the oxidized residue are two orders of magnitude lower than those in the HF-HCl residue, and they are close to concentrations in the bulk. The He and Ne concentrations are similar in the three samples. The Ne isotopic ratios are almost purely cosmogenic, indicating absence of presolar diamonds (the carrier of the HL component). Thus, Saratov contains phase Q without presolar diamond. A study of the Raman spectroscopic parameters for the HF-HCl residue and the oxidized residue shows large changes due to oxidation. The directions of these changes are the same as observed in Allende, except oxidation increased the ID/IG (intensity ratio of the D band to the G band) in Saratov but decreased in Allende. This difference may be attributed to the different crystalline stages of carbon in both meteorites. The shifts in the Raman parameters to a discrete and/or more expanded region suggest that (1) oxidation changes the crystalline condition of graphitic carbon, (2) phase Q is not a dissolved site, and (3) the release of Q-gas is simply related to the rearrangement of the carbon structure during oxidation.

  20. Magnetism in grain-boundary phase of a NdFeB sintered magnet studied by spin-polarized scanning electron microscopy

    SciTech Connect

    Kohashi, Teruo Motai, Kumi; Nishiuchi, Takeshi; Hirosawa, Satoshi

    2014-06-09

    The magnetism in the grain-boundary phase of a NdFeB sintered magnet was measured by spin-polarized scanning electron microscopy (spin SEM). A sample magnet was fractured in the ultra-high-vacuum chamber to avoid oxidation, and its magnetizations in the exposed grain-boundary phase on the fracture surface were evaluated through the spin polarization of secondary electrons. Spin-SEM images were taken as the fracture surface was milled gradually by argon ions, and the magnetization in the grain-boundary phase was quantitatively obtained separately from that of the Nd{sub 2}Fe{sub 14}B phase. The obtained magnetization shows that the grain-boundary phase of this magnet has substantial magnetization, which was confirmed to be ferromagnetic.

  1. Phase behavior and 13C NMR spectroscopic analysis of the mixed methane + ethane + propane hydrates in mesoporous silica gels.

    PubMed

    Lee, Seungmin; Cha, Inuk; Seo, Yongwon

    2010-11-25

    In this study, the phase behavior and quantitative determination of hydrate composition and cage occupancy for the mixed CH(4) + C(2)H(6) + C(3)H(8) hydrates were closely investigated through the experimental measurement of three-phase hydrate (H)-water-rich liquid (L(W))-vapor (V) equilibria and (13)C NMR spectra. To examine the effect of pore size and salinity, we measured hydrate phase equilibria for the quaternary CH(4) (90%) + C(2)H(6) (7%) + C(3)H(8) (3%) + water mixtures in silica gel pores of nominal diameters of 6.0, 15.0, and 30.0 nm and for the quinary CH(4) (90%) + C(2)H(6) (7%) + C(3)H(8) (3%) + NaCl + water mixtures of two different NaCl concentrations (3 and 10 wt %) in silica gel pores of a nominal 30.0 nm diameter. The value of hydrate-water interfacial tension for the CH(4) (90%) + C(2)H(6) (7%) + C(3)H(8) (3%) hydrate was found to be 47 ± 4 mJ/m(2) from the relation of the dissociation temperature depression with the pore size of silica gels at a given pressure. At a specified temperature, three-phase H-L(W)-V equilibrium curves of pore hydrates were shifted to higher pressure regions depending on pore sizes and NaCl concentrations. From the cage-dependent (13)C NMR chemical shifts of enclathrated guest molecules, the mixed CH(4) (90%) + C(2)H(6) (7%) + C(3)H(8) (3%) gas hydrate was confirmed to be structure II. The cage occupancies of each guest molecule and the hydration number of the mixed gas hydrates were also estimated from the (13)C NMR spectra.

  2. Spectroscopic characterization of co-precipitated arsenic- and iron-bearing sulfide phases at circum-neutral pH

    NASA Astrophysics Data System (ADS)

    Illera, V.; Rivera, N. A.; O'Day, P. A.

    2009-12-01

    Precipitation of arsenic- and iron-sulfide phases from porewaters is an important mechanism for removing arsenic and other contaminant metals from solution, thus reducing their bioaccessibility and potential toxicity. Although sulfide phases form readily at low pH, the identity, crystallinity, and local structure of arsenic and iron co-precipitated phases that form at circum-neutral pH are less well known. In this study, co-precipitated As+Fe sulfide phases and end-member As-sulfides and Fe-sulfides were synthesized in batch experiments and in a gas-tight reaction vessel at 25°C. Reduced conditions were maintained by keeping a constant flow of a 95%N2 /5%H2 mixture gas. Fresh saturated solutions of 0.3 M Fe(II) or Fe(III), 0.3 M S2- and 0.2 M As(III) ions were mixed and pH was maintained at pH 4, 6 and 8 by small additions of concentrated HCl or NaOH. At different time intervals, aliquots were extracted from suspensions aged from hours to 1 month and analyzed for total iron, arsenic and sulfur (by ICP-OES and ICP-MS). The Fe-S-As precipitates were characterized by X-ray diffraction (XRD) and synchrotron X-ray absorption spectroscopy (XAS). X-ray diffraction and Fe k-edge EXAFS showed the precipitation of amorphous to poorly crystalline iron sulfide when Fe(II) was co-precipitated with sulfide (no arsenic) at pH 4, 6, and 8. The precipitate that formed in ~1-4 h was nanoparticle-sized and disordered mackinawite (FeS), which showed a characteristic broad, low-intensity Bragg peaks in the XRD patterns. After aging for ~7 d, XRD patterns showed a change to more crystalline mackinawite. In contrast, co-precipitation of As(III) with Fe(II) and sulfide resulted in x-ray amorphous (both synchrotron and laboratory XRD) precipitates for all pH and aging times (~4 h to 1 m). Arsenic and iron XANES and EXAFS spectra of precipitates at pH 4 showed a mixture of amorphous orpiment-type (As2S3) and mackinawite-type (FeS) phases. At pH 6 and 8, XANES showed As sulfide and a

  3. Quantitative asymmetric-detection time-stretch optical microscopy (Q-ATOM) for ultrafast quantitative phase imaging flow cytometry (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Lau, Andy K. S.; Tang, Anson H. L.; Chung, Bob M. F.; Tsang, Kwok Yeung; Chan, Antony C. S.; Wei, Xiaoming; Wong, Kenneth K.; Lam, Edmund Y.; Cheah, Kathryn S. E.; Shum, Anderson H. C.; Tsia, Kevin K.

    2016-03-01

    Based on the interferometric or holographic approaches, recent QPM techniques provide quantitative-phase information, e.g cell volume, dry mass and optical scattering properties for label-free cellular physical phenotyping. These approaches generally rely on iterative phase-retrieval algorithms to obtain quantitative-phase information, which are computationally intensive. Moreover, current QPM techniques can only offer limited image acquisition rate by using CMOS/CCD image sensors, these two limitations hinder QPM for high-throughput quantitative image-based single-cell analysis in real-time. To this end, we demonstrate an interferometry-free quantitative phase microscopy developed on a new generation of time-stretch microscopy, asymmetric-detection time-stretch optical microscopy (ATOM), which is coined quantitative ATOM (Q-ATOM) - featuring an unprecedented cell measurement throughput together with the assorted intrinsic optical phenotypes (e.g. angular light scattering profile) and the derived physical properties of the cells (e.g. cell size, dry mass density etc.). Based on a similar concept to Schlieren imaging, Q-ATOM retrieves quantitative-phase information through multiple off-axis light-beam detection at a line-scan rate of <10 MHz - a speed unachievable by any existing QPM techniques. Phase retrieval in Q-ATOM relies on a non-iterative method, significantly reducing the computational complexity of the technique. It is a particularly important feature which facilitates real-time continuous label-free single-cell analysis in Q-ATOM. With the use of a non-interferometric configuration, we demonstrate ultrafast Q-ATOM of mouse chondrocytes and hypertrophic chondrocytes in ultrafast microfluidic flow with sub-cellular resolution at an imaging throughput equivalent to ~100,000 cells/sec without image blur. This technique shows a great potential for ultrahigh throughput label-free image-based single-cell biophysical phentotyping.

  4. Laser-induced carbon plasma emission spectroscopic measurements on solid targets and in gas-phase optical breakdown.

    PubMed

    Nemes, László; Keszler, Anna M; Hornkohl, James O; Parigger, Christian G

    2005-06-20

    We report measurements of time- and spatially averaged spontaneous-emission spectra following laser-induced breakdown on a solid graphite/ambient gas interface and on solid graphite in vacuum, and also emission spectra from gas-phase optical breakdown in allene C3H4 and helium, and in CO2 and helium mixtures. These emission spectra were dominated by CII (singly ionized carbon), CIII (doubly ionized carbon), hydrogen Balmer beta (Hbeta), and Swan C2 band features. Using the local thermodynamic equilibrium and thin plasma assumptions, we derived electron number density and electron temperature estimates. The former was in the 10(16) cm(-3) range, while the latter was found to be near 20000 K. In addition, the vibration-rotation temperature of the Swan bands of the C2 radical was determined to be between 4500 and 7000 K, using an exact theoretical model for simulating diatomic emission spectra. This temperature range is probably caused by the spatial inhomogeneity of the laser-induced plasma plume. Differences are pointed out in the role of ambient CO2 in a solid graphite target and in gas-phase breakdown plasma.

  5. Laser-induced carbon plasma emission spectroscopic measurements on solid targets and in gas-phase optical breakdown

    SciTech Connect

    Nemes, Laszlo; Keszler, Anna M.; Hornkohl, James O.; Parigger, Christian

    2005-06-20

    We report measurements of time- and spatially averaged spontaneous-emission spectra following laser-induced breakdown on a solid graphite/ambient gas interface and on solid graphite in vacuum, and also emission spectra from gas-phase optical breakdown in allene C3H4 and helium, and in CO2 and helium mixtures. These emission spectra were dominated by CII (singly ionized carbon), CIII (doubly ionized carbon), hydrogen Balmer beta (H{sub b}eta), and Swan C2 band features. Using the local thermodynamic equilibrium and thin plasma assumptions, we derived electron number density and electron temperature estimates. The former was in the 1016 cm{sup -3} range, while the latter was found to be near 20000 K. In addition, the vibration-rotation temperature of the Swan bands of the C2 radical was determined to be between 4500 and 7000 K, using an exact theoretical model for simulating diatomic emission spectra. This temperature range is probably caused by the spatial inhomogeneity of the laser-induced plasma plume. Differences are pointed out in the role of ambient CO2 in a solid graphite target and in gas-phase breakdown plasma.

  6. Laser intensity effects in carrier-envelope phase-tagged time of flight-photoemission electron microscopy

    NASA Astrophysics Data System (ADS)

    Chew, S. H.; Gliserin, A.; Schmidt, J.; Bian, H.; Nobis, S.; Schertz, F.; Kübel, M.; Yang, Y.-Y.; Loitsch, B.; Stettner, T.; Finley, J. J.; Späth, C.; Ouacha, H.; Azzeer, A. M.; Kleineberg, U.

    2016-04-01

    A time of flight-photoemission electron microscope is combined with a single-shot stereographic above-threshold ionization phase meter for studying attosecond control of electrons in tailored plasmonic nanostructures spatially and energetically via a carrier-envelope phase tagging technique. First carrier-envelope phase-resolved measurements of gold nanoparticles on gold plane and surface roughness from a gold film show an apparent carrier-envelope phase modulation with a period of π. This modulation is found to originate from an intensity dependence of the photoelectron spectra and the carrier-envelope phase measurement rather than from an intrinsic carrier-envelope phase dependence, which is confirmed by simulations. This useful finding suggests that intensity tagging should be considered for phase tagging experiments on plasmonic nanostructures with low carrier-envelope phase sensitivity in order to correct for the intensity-related carrier-envelope phase artifact.

  7. [THE ATOMIC-FORCE MICROSCOPY STUDY OF STRUCTURAL FUNCTIONAL CHARACTERISTICS OF NEUTROPHILS IN PATIENTS WITH CHRONIC OBSTRUCTIVE LUNG DISEASES IN PHASE OF EXACERBATION].

    PubMed

    Gainitdinova, V V; Sharafutdinova, L A; Kamaltdinov, I M; Avdeev, S N

    2015-05-01

    The technique of atomic-force microscopy was applied to analyze the structural functional characteristics (morphology, force of adhesion, rigidity of membrane) of neutrophils in patients with chronic obstructive disease of lungs in phase of exacerbation. The regimen of force spectroscopy was applied to implement quantitative evaluation of module of elasticity (Young module) of cell membrane and force of adhesion of neutrophils. The study established decreasing of size of neutrophils, increasing of granularity of cytoplasm, increasing of Young module and force of adhesion in patients with chronic obstructive disease of lungs in phase of exacerbation.

  8. Fast numerical autofocus of multispectral complex fields in digital holographic microscopy with a criterion based on the phase in the Fourier domain.

    PubMed

    Dohet-Eraly, Jérôme; Yourassowsky, Catherine; Dubois, Frank

    2016-09-01

    The knowledge of the complex amplitude of optical fields, that is, both quantitative phase and intensity, enables numeric reconstruction along the optical axis. Nonetheless, a criterion is required for autofocusing. This Letter presents a robust and rapid refocusing criterion suitable for color interferometric digital holographic microscopy, and, more generally, for applications where complex amplitude is known for at least two different wavelengths. This criterion uses the phase in the Fourier domain, which is compared among wavelengths. It is applicable whatever the nature of the observed object: opaque, refractive, or both mixed. The method is validated with simulated and experimental holograms. PMID:27607975

  9. Evaluation of Al3Mg2 precipitates and Mn-rich phase in aluminum-magnesium alloy based on scanning transmission electron microscopy imaging

    SciTech Connect

    Zhu, Yakun; Cullen, David A; Kar, Soumya; Free, Michael P; Allard Jr, Lawrence Frederick

    2012-01-01

    Scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDS) were used to observe intergranular and intragranular -phase (Al3Mg2) formation and growth in as-received sample and long-term (~ 1 year) thermally treated samples of 5083-H131 alloy. Rod-shaped and equiaxed particles rich in Mn, Fe, and Cr were present in the as-received and heat treated samples. The -phase precipitated along grain boundaries as well as around and between preexisting Mn-Fe-Cr rich particles. The measured thickness of -phase along grain boundaries was lower than Zener Hillert diffusion model predicted value and the potential reasons were theoretically analyzed. Dislocation networks, grain boundaries, and different preexisting particles were observed to contribute to Mg diffusion and -phase precipitation.

  10. Introduction of a valence space in quasiparticle random-phase approximation: Impact on vibrational mass parameters and spectroscopic properties

    NASA Astrophysics Data System (ADS)

    Lechaftois, F.; Deloncle, I.; Péru, S.

    2015-09-01

    For the first time, using a unique finite-range interaction (D1M Gogny force), a fully coherent and time-feasible calculation of the Bohr Hamiltonian vibrational mass is envisioned in a Hartree-Fock-Bogoliubov + quasiparticle random-phase approximation (QRPA) framework. In order to reach a reasonable computation time, we evaluate the feasibility of this method by considering two restrictions for the QRPA: the Tamm-Dancoff approximation and the insertion of a valence space. We validate our approach in the even-even tin isotopes by comparing the convergence scheme of the mass parameter with those of built-in QRPA outputs: excited-state energy and reduced transition probability. The seeming convergence of these intrinsic quantities is shown to be misleading and the difference with the theoretical expected value is quantified. This work is a primary step towards the systematic calculation of mass parameters.

  11. Spectroscopic, nonlinear optical and quantum chemical studies on Pyrrolidinium p-Hydroxybenzoate--a phase matchable organic NLO crystal.

    PubMed

    Shanmugam, G; Belsley, M S; Isakov, D; Gomes, E de Matos; Nehru, K; Brahadeeswaran, S

    2013-10-01

    Good quality and bulk single crystals of Pyrrolidinium p-Hydroxybenzoate (PYPHB), a newly identified nonlinear optical material, were grown for the first time. It crystallizes in monoclinic system with an acentric space group Cc. The molecular structure including carbon, proton positions and functional groups has been confirmed through nuclear magnetic resonance and Fourier transform infrared spectra. Its transmission window has been observed for UV-VIS-NIR region along with its theoretical limit. The photoluminescence behavior has been observed by exciting the crystal at 310 nm. The principal refractive indices and second order NLO coefficient of PYPHB are determined by Mach-Zehnder interferometer and Maker-Fringe experiments respectively. The coherence length and phase-matchablility of PYPHB crystals are measured to explore its efficacy towards device fabrications. The dipole moment, polarizability and molecular orbital energy of an isolated PYPHB molecule have also been calculated theoretically and the results are found to corroborate the experimental values.

  12. An Unexpected Gas-Phase Binding Motif for Metal Dication Complexation with Peptides: Irmpd Spectroscopic Structure Determination

    NASA Astrophysics Data System (ADS)

    Dunbar, Robert C.; Steill, Jeffrey; Polfer, Nicolas; Berden, Giel; Oomens, Jos

    2011-06-01

    The favorable orientation of the amide linkage and the aromatic side chain of N-terminal Phe or Trp leads to several favorable motifs for metal ion binding to dipeptides, having distinct characteristics in the IR spectrum. Infrared multiple photon photodissociation spectroscopy using the FELIX free electron laser has enabled clear resolution of these isomeric forms. The spectral patterns of complexes of small dications (Mg2+, Ni2+ and Co2+) reveal an unexpected new isomeric form, in which the metal ion displaces the amide hydrogen, forming a metal-nitrogen bond with covalent character which is unprecedented in such gas-phase complexes. Spectra of the ions were acquired by irradiating the cell of the Fourier-transform ion cyclotron resonance mass spectrometer with infrared light from the FELIX laser at wavelengths in the approximate range 500 to 1900 Cm-1.

  13. Fast, noninvasive and simultaneous near-infrared spectroscopic characterisation of physicochemical stationary phases' properties: from silica particles towards monoliths.

    PubMed

    Petter, Christine H; Heigl, Nico; Bonn, Günther K; Huck, Christian W

    2008-08-01

    The design of novel stationary phases is a permanent demanding challenge in chromatographic separation science to enable analysis with enhanced selectivity, specificity and speed. Therefore, the characterisation of chemical and physical properties is next to calculation of chromatographic parameters essential. Conventionally, chemical parameters including surface coverage are determined by burning combustion or frontal analysis, physical parameters including particle size, pore size, pore volume and surface area are determined by SEM, mercury intrusion porosimetry (MIP) and Brunauer-Emmett-Teller (BET). All these methods are time consuming, invasive and require besides special equipment some special trained laboratory staff. Therefore, we introduced near-infrared spectroscopy (NIRS) as a noninvasive, easy-to-handle technology with wavenumber ranging from 4000 to 10,000 cm(-1) enabling analysis within only a few seconds at higher precision than the conventional methods. Investigated materials comprise porous and nonporous silica gel, carbon-based nanomaterials (fullerenes), polymer beads and monoliths. Different carriers themselves and their kind of derivatisations (RP, normal-phase, ion-exchanger, IMAC (immobilised metal affinity chromatography), affinity) can be determined by applying principal component analysis (PCA) of recorded spectra. Partial least square regression (PLSR) enables the determination of particle size, pore size, pore volume, porosity, total porosity and surface area with one single measurement. For the optimised design of well-defined polymer beads and monoliths, real-time in situ monitoring to control, e. g. particle and pore sizes as well as monomer content during the polymerisation process, can be extremely helpful. In this article, the advantages of this fast, noninvasive high-throughput NIRS methods are summarised, discussed in detail and different applications of the individual characterised materials are shown.

  14. Innovative tribometer for in situ spectroscopic analyses of wear mechanisms and phase transformation in ceramic femoral heads.

    PubMed

    Puppulin, Leonardo; Leto, Andrea; Wenliang, Zhu; Sugano, Nobuhiko; Pezzotti, Giuseppe

    2014-03-01

    The literature on tribological assessments of artificial hip joints usually focuses on correlations between joint composition, size, and specific wear rates, but conspicuously ignores the physical aspects behind the occurrence of degradation mechanisms of friction and wear. Surface degradation in artificial joints occurs because of increases in temperature and local exacerbation of contact stresses inside the moving contact as a consequence of physical and chemical modifications of the sliding surfaces. This article reports about the development of a new pin-on-ball spectroscopy-assisted tribometer device that enables investigating also physical rather than merely engineering aspects of wear processes using in situ Raman and fluorescence techniques. This innovative tribometer is designed to bring about, in addition to conventional tribological parameters, also information of temperature, stress and phase transformations in the femoral heads as received from the manufacturer. Raman and fluorescence spectra at the point of sliding contact are recorded durilng reciprocating hard-on-hard dry-sliding tests. Preliminary results were collected on two different commercially available ceramic-on-ceramic hip joint bearing couples, made of monolithic alumina and alumina-zirconia composites. Although the composite couple showed direct evidence of tetragonal-to-monoclinic phase transformation, which enhanced the coefficient of friction, the specific wear rate was significantly lower than that of the monolithic one (i.e., by a factor 2.63 and 4.48 on the pin and head side, respectively). In situ collected data compared to ex situ analyses elucidated the surface degradation processes and clarified the origin for the higher wear resistance of the composite as compared to the monolithic couple.

  15. Quantitative phase separation in multiferroic Bi{sub 0.88}Sm{sub 0.12}FeO{sub 3} ceramics via piezoresponse force microscopy

    SciTech Connect

    Alikin, D. O. Turygin, A. P.; Shur, V. Ya.; Walker, J.; Rojac, T.; Shvartsman, V. V.; Kholkin, A. L.

    2015-08-21

    BiFeO{sub 3} (BFO) is a classical multiferroic material with both ferroelectric and magnetic ordering at room temperature. Doping of this material with rare-earth oxides was found to be an efficient way to enhance the otherwise low piezoelectric response of unmodified BFO ceramics. In this work, we studied two types of bulk Sm-modified BFO ceramics with compositions close to the morphotropic phase boundary (MPB) prepared by different solid-state processing methods. In both samples, coexistence of polar R3c and antipolar P{sub bam} phases was detected by conventional X-ray diffraction (XRD); the non-polar P{sub nma} or P{sub bnm} phase also has potential to be present due to the compositional proximity to the polar-to-non-polar phase boundary. Two approaches to separate the phases based on the piezoresponse force microscopy measurements have been proposed. The obtained fractions of the polar and non-polar/anti-polar phases were close to those determined by quantitative XRD analysis. The results thus reveal a useful method for quantitative determination of the phase composition in multi-phase ceramic systems, including the technologically most important MPB systems.

  16. Statistical mechanical analysis of Raman spectroscopic order parameter changes in pressure-induced lipid bilayer phase transitions.

    PubMed Central

    Yager, P; Peticolas, W L

    1980-01-01

    The statistical mechanical cluster theory of Fisher as applied by Kanehisa and Tsong to phospholipid bilayers is modified to describe the effects of hydrostatic pressure on the state of an aqueous dispersion of the phospholipid dipalmitoyl phosphatidylcholine. A high pressure Raman scattering cell has been built to obtain the Raman spectra of aqueous dispersions of phospholipids as a function of the applied hydrostatic pressure from 0 to 100 atmospheres. Predicted thermal and pressure-induced phase transitions are compared with an experimentally obtained Raman order parameter derived from the ratio of two bands in the C-H stretching region of the Raman spectrum of the sample. The parameters of the theory are adjusted to obtain a satisfactory fit of the Raman order parameter versus temperature. The theory is then found to give an excellent prediction of the observed pressure dependence of the Raman order parameter with no changes in the adjustable parameters. The implications of the success of the theoretical fit is discussed. Particularly of interest is the rather high value of the critical temperature, Tc, for lipid bilayers which is predicted by the model. PMID:6894876

  17. Ruthenium trisbipyridine as a candidate for gas-phase spectroscopic studies in a Fourier transform mass spectrometer

    DOE PAGESBeta

    Scott, Jill R.; Ham, Jason E.; Durham, Bill; Tremblay, Paul L.

    2004-01-01

    Metal polypyridines are excellent candidates for gas-phase optical experiments where their intrinsic properties can be studied without complications due to the presence of solvent. The fluorescence lifetimes of [Ru(bpy) 3 ] 1+ trapped in an optical detection cell within a Fourier transform mass spectrometer were obtained using matrix-assisted laser desorption/ionization to generate the ions with either 2,5-dihydroxybenzoic acid (DHB) or sinapinic acid (SA) as matrix. All transients acquired, whether using DHB or SA for ion generation, were best described as approximately exponential decays. The rate constant for transients derived using DHB as matrix was 4×10 7 s −1 ,more » while the rate constant using SA was 1×10 7 s −1 . Some suggestions of multiple exponential decay were evident although limited by the quality of the signals. Photodissociation experiments revealed that [Ru(bpy) 3 ] 1+ generated using DHB can decompose to [Ru(bpy) 2 ] 1+ , whereas ions generated using SA showed no decomposition. Comparison of the mass spectra with the fluorescence lifetimes illustrates the promise of incorporating optical detection with trapped ion mass spectrometry techniques.« less

  18. Spectroscopic Investigation of H Atom Transfer in a Gas-phase Dissociation Reaction: McLafferty Rearrangement of Model Gas-phase Peptide Ions

    SciTech Connect

    Michael J. Van Stipdonk; Dale R. Kersetter; Christopher M. Leavitt; Gary S. Groenewold; Jeffrey Steill; Jos Oomens

    2008-07-01

    Wavelength-selective infrared multiple-photon photodissociation (WS-IRMPD) was used to study isotopically-labeled ions generated by McLafferty rearrangement of nicotinyl-glycine-tert-butyl ester and betaine-glycine-tert-butyl ester. The tert-butyl esters were incubated in a mixture of D2O and CH3OD to induce solution-phase hydrogen-deuterium exchange and then converted to gas-phase ions using electrospray ionization. McLafferty rearrangement was used to generate the free-acid forms of the respective model peptides through transfer of an H atom and elimination of butene. The specific aim was to use vibrational spectra generated by WS-IRMPD technique to determine whether the H atom remains at the acid group, or migrates to one or more of the other exchangeable sites. Comparison of the IRMPD results in the region from 1200-1900 cm-1 to theoretical spectra for different isotopically-labeled isomers clearly shows that the H atom is situated at the C-terminal acid group and migration to amide positions is negligible on the time scale of the experiment. The results of this study suggest that use of the McLafferty rearrangement for peptide esters could be an effective approach for generation of H-atom isotope tracers, in-situ, for subsequent investigation of intra-molecular proton migration during peptide fragmentation studies.

  19. A high-resolution transmission electron microscopy study of interfaces between the γ, B2, and α2 phases in a Ti-Al-Mo alloy

    NASA Astrophysics Data System (ADS)

    Das, S.; Howe, J. M.; Perepezko, J. H.

    1996-06-01

    Conventional and high-resolution transmission electron microscopy (HRTEM) were used to examine the interfacial structures in a Ti-50Al-5Mo (at. pct) alloy which was processed to produce combinations of γ, B2, and α2 phases in a single sample. A small amount of a fourth phase labeled ζ was also found in the microstructure. It may be the phase Ti2AlN but confirmation requires analysis of the N content in the phase.In this alloy, the orientation relationship between the γ and B2 phases is {111}γ ∥}110}B2 and <101]γ ∥ <111>B2 with a coherent habit-plane interface parallel to (474)γ. The orientation relationship between the B2 and α2 (and also the ζ @#@) phases is {110}B2 ∥(0001)α2/ζ and <111>B2 ∥<11-20>α2/ζ with a coherent interface parallel to the close-packed planes and along other orientations. The orientation relationship between the α2 (and also the ζ @#@) and γ phases is (0001)α2/ζ ∥{lll}γ and (11•20)α2/ζ ∥<10•1]γ. The α2 phase has a coherent interface parallel to the close-packed planes, while the ζ phase appears to adopt the (474)γ interface plane of the γ phase, similar to the B2 phase. In some cases, the interface configuration between the γ and B2 phases appears to be altered by the presence of α2 phase, resulting in a semicoherent interface. The phase labeled ζ in this study has the same orientation relationship with the γ and B2 phases as α2 but consists of an ABABAC... stacking of close-packed basal planes. The (474)γ habit plane interface between the γ and B2 phases is analyzed by several different theories of interfacial structure, and microstructural evolution in this system is also discussed.

  20. Direct observation of the intergrown {alpha}-phase in {beta}-TmAlB{sub 4} via high-resolution electron microscopy

    SciTech Connect

    Yubuta, Kunio; Mori, Takao; Leithe-Jasper, Andreas; Grin, Yuri; Okada, Shigeru; Shishido, Toetsu

    2009-08-05

    A TmAlB{sub 4} crystal with a ThMoB{sub 4}-type ({beta}-type) structure phase related to a hexagonal AlB{sub 2}-type structure was studied by electron diffraction and high-resolution electron microscopy. A high-resolution image clearly exhibits an intergrown lamellar structure of a YCrB{sub 4}-type ({alpha}-type) phase in the matrix of the {beta}-type phase in TmAlB{sub 4} crystal. The lamellar structure can be characterized by a tiling of deformed hexagons, which are a common structure unit in the {alpha}-type and {beta}-type structures. The intergrown nanostructure is considered to be attributed to the origin of low temperature anomalies in physical properties.

  1. High-throughput, high-resolution X-ray phase contrast tomographic microscopy for visualisation of soft tissue

    NASA Astrophysics Data System (ADS)

    McDonald, S. A.; Marone, F.; Hintermüller, C.; Bensadoun, J.-C.; Aebischer, P.; Stampanoni, M.

    2009-09-01

    The use of conventional absorption based X-ray microtomography can become limited for samples showing only very weak absorption contrast. However, a wide range of samples studied in biology and materials science can produce significant phase shifts of the X-ray beam, and thus the use of the phase signal can provide substantially increased contrast and therefore new and otherwise inaccessible information. The application of two approaches for high-throughput, high-resolution X-ray phase contrast tomography, both available on the TOMCAT beamline of the SLS, is illustrated. Differential Phase Contrast (DPC) imaging uses a grating interferometer and a phase-stepping technique. It has been integrated into the beamline environment on TOMCAT in terms of the fast acquisition and reconstruction of data and the availability to scan samples within an aqueous environment. The second phase contrast approach is a modified transfer of intensity approach that can yield the 3D distribution of the phase (refractive index) of a weakly absorbing object from a single tomographic dataset. These methods are being used for the evaluation of cell integrity in 3D, with the specific aim of following and analyzing progressive cell degeneration to increase knowledge of the mechanistic events of neurodegenerative disorders such as Parkinson's disease.

  2. Spectroscopic detection

    DOEpatents

    Woskov, Paul P.; Hadidi, Kamal

    2003-01-01

    In embodiments, spectroscopic monitor monitors modulated light signals to detect low levels of contaminants and other compounds in the presence of background interference. The monitor uses a spectrometer that includes a transmissive modulator capable of causing different frequency ranges to move onto and off of the detector. The different ranges can include those with the desired signal and those selected to subtract background contributions from those with the desired signal. Embodiments of the system are particularly useful for monitoring metal concentrations in combustion effluent.

  3. Multimodal label-free growth and morphology characterization of different cell types in a single culture with quantitative digital holographic phase microscopy

    NASA Astrophysics Data System (ADS)

    Kemper, Björn; Wibbeling, Jana; Kastl, Lena; Schnekenburger, Jürgen; Ketelhut, Steffi

    2015-03-01

    For the analysis of the impact of pharmaceuticals or pathogens on different cellular phenotypes under identical measurement conditions and to analyze interactions between different cellular specimens a minimally-invasive quantitative observation of different cell types in a single culture is of particular interest. Digital holographic microscopy (DHM), a var-iant of quantitative phase microscopy (QPM), provides high resolution detection of optical path length changes that is suitable for stain-free minimally-invasive live cell analysis. Due to low light intensities for object illumination, QPM minimizes the interaction with the sample and has been demonstrated in particular to be suitable for long-term time-lapse investigations, e.g., for the detection of cell morphology alterations due to drugs and toxins. Furthermore, QPM has been demonstrated to be a versatile tool for the quantification of cellular growth and motility. Thus, we studied the feasibility of QPM for the analysis of mixed cell cultures and explored if quantitative phase images provide sufficient information to distinguish between different cell types and to extract cell specific parameters. For the experiments quantitative phase imaging with DHM was utilized. Mixed cell cultures with different cell types were observed with quantitative DHM phase contrast up to 35 h. The obtained series of quantitative phase images were evaluated by adapted algorithms for image segmentation. From the segmented images the area covered by the cells, the cellular dry mass and the mean cell thickness were calculated and used in the further analysis as parameters to quantify the reliability of the measurement principle. The obtained results demonstrate that it is possible to characterize the growth of cell types with different mor-phology features separately in a single culture.

  4. Active phase distribution changes within a catalyst particle during Fischer–Tropsch synthesis as revealed by multi-scale microscopy

    DOE PAGESBeta

    Cats, K. H.; Andrews, J. C.; Stephan, O.; March, K.; Karunakaran, C.; Meirer, F.; de Groot, F. M. F.; Weckhuysen, B. M.

    2016-02-16

    In this study, the Fischer-Tropsch synthesis (FTS) reaction is one of the most promising processes to convert alternative energy sources, such as natural gas, coal or biomass, into liquid fuels and other high-value products. Despite its commercial implementation, we still lack fundamental insights into the various deactivation processes taking place during FTS. In this work, a combination of three methods for studying single catalyst particles at different length scales has been developed and applied to study the deactivation of Co/TiO2 Fischer-Tropsch synthesis (FTS) catalysts. By combining transmission X-ray microscopy (TXM), scanning transmission X-ray microscopy (STXM) and scanning transmission electron microscopy-electronmore » energy loss spectroscopy (STEM-EELS) we visualized changes in the structure, aggregate size and distribution of supported Co nanoparticles that occur during FTS. At the microscale, Co nanoparticle aggregates are transported over several μm leading to a more homogeneous Co distribution, while at the nanoscale Co forms a thin layer of ~1-2 nm around the TiO2 support. The formation of the Co layer is the opposite case to the “classical” strong metal-support interaction (SMSI) in which TiO2 surrounds the Co, and is possibly related to the surface oxidation of Co metal nanoparticles in combination with coke formation. In other words, the observed migration and formation of a thin CoOx layer are similar to a previously discussed reaction-induced spreading of metal oxides across a TiO2 surface.« less

  5. Temperature effect on thin lipid film elasticity and phase separation: insights from Langmuir monolayer and fluorescence microscopy techniques

    NASA Astrophysics Data System (ADS)

    Khattari, Z.; Maghrabi, M.; Al-Abdullah, T.

    2015-07-01

    Langmuir monolayer pressure isotherms and compressibility modulus measurements of phospholipid mixtures in several Langmuir monolayer systems at the air/water interface were investigated in this study. The ultimate aim was to carry out a comparison of the elasticity modulus for monolayers with different mixtures of l,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), l,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and chicken egg yolk sphingomyelin (eSM), in the presence/absence of cholesterol (Chol). In particular, we were able to propose that the leading force beyond the phase separation into liquid expanded (LE-) and liquid condensed (LC-) phases emerges from the increasing barrier to incorporate DOPC molecules into a highly ordered LC-phase. In addition, our findings suggest that DOPC lipid molecules have a priority to incorporate in a disordered LE-phase, while DPPC and eSM prefer the ordered one. Also, Chol seems to split almost equally into both phases, indicating that Chol has no priority for either phase and there are no particular interactions between Chol and saturated lipid molecules.

  6. Phase Boundary Propagation in Li-Alloying Battery Electrodes Revealed by Liquid-Cell Transmission Electron Microscopy.

    PubMed

    Leenheer, Andrew J; Jungjohann, Katherine L; Zavadil, Kevin R; Harris, Charles T

    2016-06-28

    Battery cycle life is directly influenced by the microstructural changes occurring in the electrodes during charge and discharge cycles. Here, we image in situ the nanoscale phase evolution in negative electrode materials for Li-ion batteries using a fully enclosed liquid cell in a transmission electron microscope (TEM) to reveal early degradation that is not evident in the charge-discharge curves. To compare the electrochemical phase transformation behavior between three model materials, thin films of amorphous Si, crystalline Al, and crystalline Au were lithiated and delithiated at controlled rates while immersed in a commercial liquid electrolyte. This method allowed for the direct observation of lithiation mechanisms in nanoscale negative electrodes, revealing that a simplistic model of a surface-to-interior lithiation front is insufficient. For the crystalline films, a lithiation front spread laterally from a few initial nucleation points, with continued grain nucleation along the growing interface. The intermediate lithiated phases were identified using electron diffraction, and high-resolution postmortem imaging revealed the details of the final microstructure. Our results show that electrochemically induced solid-solid phase transformations can lead to highly concentrated stresses at the laterally propagating phase boundary which should be considered for future designs of nanostructured electrodes for Li-ion batteries.

  7. Phase Boundary Propagation in Li-Alloying Battery Electrodes Revealed by Liquid-Cell Transmission Electron Microscopy

    DOE PAGESBeta

    Leenheer, Andrew J.; Jungjohann, Katherine L.; Zavadil, Kevin R.; Harris, Charles T.

    2016-05-31

    Battery cycle life is directly influenced by the microstructural changes occurring in the electrodes during charge and discharge cycles. In this study, we image in situ the nanoscale phase evolution in negative electrode materials for Li-ion batteries using a fully enclosed liquid cell in a transmission electron microscope (TEM) to reveal early degradation that is not evident in the charge–discharge curves. To compare the electrochemical phase transformation behavior between three model materials, thin films of amorphous Si, crystalline Al, and crystalline Au were lithiated and delithiated at controlled rates while immersed in a commercial liquid electrolyte. This method allowed formore » the direct observation of lithiation mechanisms in nanoscale negative electrodes, revealing that a simplistic model of a surface-to-interior lithiation front is insufficient. For the crystalline films, a lithiation front spread laterally from a few initial nucleation points, with continued grain nucleation along the growing interface. The intermediate lithiated phases were identified using electron diffraction, and high-resolution postmortem imaging revealed the details of the final microstructure. Lastly, our results show that electrochemically induced solid–solid phase transformations can lead to highly concentrated stresses at the laterally propagating phase boundary which should be considered for future designs of nanostructured electrodes for Li-ion batteries.« less

  8. Phase Boundary Propagation in Li-Alloying Battery Electrodes Revealed by Liquid-Cell Transmission Electron Microscopy.

    PubMed

    Leenheer, Andrew J; Jungjohann, Katherine L; Zavadil, Kevin R; Harris, Charles T

    2016-06-28

    Battery cycle life is directly influenced by the microstructural changes occurring in the electrodes during charge and discharge cycles. Here, we image in situ the nanoscale phase evolution in negative electrode materials for Li-ion batteries using a fully enclosed liquid cell in a transmission electron microscope (TEM) to reveal early degradation that is not evident in the charge-discharge curves. To compare the electrochemical phase transformation behavior between three model materials, thin films of amorphous Si, crystalline Al, and crystalline Au were lithiated and delithiated at controlled rates while immersed in a commercial liquid electrolyte. This method allowed for the direct observation of lithiation mechanisms in nanoscale negative electrodes, revealing that a simplistic model of a surface-to-interior lithiation front is insufficient. For the crystalline films, a lithiation front spread laterally from a few initial nucleation points, with continued grain nucleation along the growing interface. The intermediate lithiated phases were identified using electron diffraction, and high-resolution postmortem imaging revealed the details of the final microstructure. Our results show that electrochemically induced solid-solid phase transformations can lead to highly concentrated stresses at the laterally propagating phase boundary which should be considered for future designs of nanostructured electrodes for Li-ion batteries. PMID:27243921

  9. Hybrid random walk-linear discriminant analysis method for unwrapping quantitative phase microscopy images of biological samples

    PubMed Central

    Kim, Diane N. H.; Teitell, Michael A.; Reed, Jason; Zangle, Thomas A.

    2015-01-01

    Abstract. Standard algorithms for phase unwrapping often fail for interferometric quantitative phase imaging (QPI) of biological samples due to the variable morphology of these samples and the requirement to image at low light intensities to avoid phototoxicity. We describe a new algorithm combining random walk-based image segmentation with linear discriminant analysis (LDA)-based feature detection, using assumptions about the morphology of biological samples to account for phase ambiguities when standard methods have failed. We present three versions of our method: first, a method for LDA image segmentation based on a manually compiled training dataset; second, a method using a random walker (RW) algorithm informed by the assumed properties of a biological phase image; and third, an algorithm which combines LDA-based edge detection with an efficient RW algorithm. We show that the combination of LDA plus the RW algorithm gives the best overall performance with little speed penalty compared to LDA alone, and that this algorithm can be further optimized using a genetic algorithm to yield superior performance for phase unwrapping of QPI data from biological samples. PMID:26305212

  10. Deciphering the atomic structure of a complex Sr/Ge (100) phase via scanning tunneling microscopy and first-principles calculations

    NASA Astrophysics Data System (ADS)

    Lukanov, Boris; Garrity, Kevin; Ismail-Beigi, Sohrab; Altman, Eric I.

    2012-05-01

    The details of a Sr-induced (3×4) reconstruction on Ge(100) were examined using scanning tunneling microscopy (STM) and density functional theory. At 1/6 ML of Sr, this reconstruction is similar to the 1/6 ML (3×2) Sr phase previously observed on Si. In contrast to Si, however, atomic-resolution images of the Sr-Ge phase exhibit more dramatic and unusual bias dependence in STM that could be explained with the help of first-principles calculations of minimum energy structures. Simulated STM images are in excellent agreement with the experimental data and allow the (3×2) Sr-Si double dimer vacancy alloy model to be extended to the Ge surface through a more complex (3×4) arrangement of its building blocks. The difference between Si and Ge is interpreted in terms of the lower Ge-Ge binding energy and differences in the interatomic bond lengths.

  11. Influence of sample preparation and reliability of automated numerical refocusing in stain-free analysis of dissected tissues with quantitative phase digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Kemper, Björn; Lenz, Philipp; Bettenworth, Dominik; Krausewitz, Philipp; Domagk, Dirk; Ketelhut, Steffi

    2015-05-01

    Digital holographic microscopy (DHM) has been demonstrated to be a versatile tool for high resolution non-destructive quantitative phase imaging of surfaces and multi-modal minimally-invasive monitoring of living cell cultures in-vitro. DHM provides quantitative monitoring of physiological processes through functional imaging and structural analysis which, for example, gives new insight into signalling of cellular water permeability and cell morphology changes due to toxins and infections. Also the analysis of dissected tissues quantitative DHM phase contrast prospects application fields by stain-free imaging and the quantification of tissue density changes. We show that DHM allows imaging of different tissue layers with high contrast in unstained tissue sections. As the investigation of fixed samples represents a very important application field in pathology, we also analyzed the influence of the sample preparation. The retrieved data demonstrate that the quality of quantitative DHM phase images of dissected tissues depends strongly on the fixing method and common staining agents. As in DHM the reconstruction is performed numerically, multi-focus imaging is achieved from a single digital hologram. Thus, we evaluated the automated refocussing feature of DHM for application on different types of dissected tissues and revealed that on moderately stained samples highly reproducible holographic autofocussing can be achieved. Finally, it is demonstrated that alterations of the spatial refractive index distribution in murine and human tissue samples represent a reliable absolute parameter that is related of different degrees of inflammation in experimental colitis and Crohn's disease. This paves the way towards the usage of DHM in digital pathology for automated histological examinations and further studies to elucidate the translational potential of quantitative phase microscopy for the clinical management of patients, e.g., with inflammatory bowel disease.

  12. Imaging the morphological change of tissue structure during the early phase of esophageal tumor progression using multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Kang, Deyong; Xu, Meifang; Zhu, Xiaoqin; Zhuo, Shuangmu; Chen, Jianxin

    2012-12-01

    Esophageal cancer is a common malignancy with a very poor prognosis. Successful strategies for primary prevention and early detection are critically needed to control this disease. Multiphoton microscopy (MPM) is becoming a novel optical tool of choice for imaging tissue architecture and cellular morphology by two-photon excited fluorescence. In this study, we used MPM to image microstructure of human normal esophagus, carcinoma in situ (CIS), and early invasive carcinoma in order to establish the morphological features to differentiate these tissues. The diagnostic features such as the appearance of cancerous cells, the significant loss of stroma, the absence of the basement membrane were extracted to distinguish between normal and cancerous esophagus tissue. These results correlated well with the paired histological findings. With the advancement of clinically miniaturized MPM and the multi-photon probe, combining MPM with standard endoscopy will therefore allow us to make a real-time in vivo diagnosis of early esophageal cancer at the cellular level.

  13. Topographical and Chemical Imaging of a Phase Separated Polymer Using a Combined Atomic Force Microscopy/Infrared Spectroscopy/Mass Spectrometry Platform.

    PubMed

    Tai, Tamin; Karácsony, Orsolya; Bocharova, Vera; Van Berkel, Gary J; Kertesz, Vilmos

    2016-03-01

    In this paper, the use of a hybrid atomic force microscopy/infrared spectroscopy/mass spectrometry imaging platform was demonstrated for the acquisition and correlation of nanoscale sample surface topography and chemical images based on infrared spectroscopy and mass spectrometry. The infrared chemical imaging component of the system utilized photothermal expansion of the sample at the tip of the atomic force microscopy probe recorded at infrared wave numbers specific to the different surface constituents. The mass spectrometry-based chemical imaging component of the system utilized nanothermal analysis probes for thermolytic surface sampling followed by atmospheric pressure chemical ionization of the gas phase species produced with subsequent mass analysis. The basic instrumental setup, operation, and image correlation procedures are discussed, and the multimodal imaging capability and utility are demonstrated using a phase separated poly(2-vinylpyridine)/poly(methyl methacrylate) polymer thin film. The topography and both the infrared and mass spectral chemical images showed that the valley regions of the thin film surface were comprised primarily of poly(2-vinylpyridine) and hill or plateau regions were primarily poly(methyl methacrylate). The spatial resolution of the mass spectral chemical images was estimated to be 1.6 μm based on the ability to distinguish surface features in those images that were also observed in the topography and infrared images of the same surface.

  14. Abnormal cubic-tetragonal phase transition of barium strontium titanate nanoparticles studied by in situ Raman spectroscopy and transmission electron microscopy heating experiments

    SciTech Connect

    Zhang, Yin; Chen, Chen; Gao, Ran; Xia, Feng; Li, YueSheng; Che, Renchao

    2015-11-02

    Phase stability of the ferroelectric materials at high temperature is extremely important to their device performance. Ba{sub x}Sr{sub 1−x}TiO{sub 3} (BST) nanoparticles with different Sr contents (x = 1, 0.91, 0.65, 0.4, and 0) are prepared by a facile hydrothermal method. Using Raman spectroscopy and transmission electron microscopy (TEM) analyses under in situ heating conditions (up to 300 °C), the phase transitions of BST nanoparticles between 25 °C and 280 °C are comprehensively investigated. The original Curie temperature of BST nanoparticles decreases abruptly with the increase in Sr content, which is more obvious than in the bulk or film material. Besides, an abnormal phase transition from cubic to tetragonal structure is observed from BST nanoparticles and the transition temperature rises along with the increase in Sr content. Direct TEM evidences including a slight lattice distortion have been provided. Differently, BaTiO{sub 3} nanoparticles remained in the tetragonal phase during the above temperature ranges.

  15. Structure refinement of the δ1p phase in the Fe-Zn system by single-crystal X-ray diffraction combined with scanning transmission electron microscopy.

    PubMed

    Okamoto, Norihiko L; Tanaka, Katsushi; Yasuhara, Akira; Inui, Haruyuki

    2014-04-01

    The structure of the δ1p phase in the iron-zinc system has been refined by single-crystal synchrotron X-ray diffraction combined with scanning transmission electron microscopy. The large hexagonal unit cell of the δ1p phase with the space group of P63/mmc comprises more or less regular (normal) Zn12 icosahedra, disordered Zn12 icosahedra, Zn16 icosioctahedra and dangling Zn atoms that do not constitute any polyhedra. The unit cell contains 52 Fe and 504 Zn atoms so that the compound is expressed with the chemical formula of Fe13Zn126. All Fe atoms exclusively occupy the centre of normal and disordered icosahedra. Iron-centred normal icosahedra are linked to one another by face- and vertex-sharing forming two types of basal slabs, which are bridged with each other by face-sharing with icosioctahedra, whereas disordered icosahedra with positional disorder at their vertex sites are isolated from other polyhedra. The bonding features in the δ1p phase are discussed in comparison with those in the Γ and ζ phases in the iron-zinc system.

  16. Transmission electron microscopy studying of structural features of NiTi B2 phase formed under pulsed electron-beam impact

    SciTech Connect

    Meisner, Ludmila L.; Semin, Viktor O.; Gudimova, Ekaterina Y.; Neiman, Alexey A. Lotkov, Alexander I.; Ostapenko, Marina G.; Koval, Nikolai N.; Teresov, Anton D.

    2015-10-27

    By transmission electron microscopy method the evolution of structural-phase states on a depth of close to equiatomic NiTi modified layer has been studied. Modification performed by pulse impact on its surface low-energy high-current electron beam (beam energy density 10 J/sm{sup 2}, 10 pulses, pulse duration 50mks). It is established that during the treatment in the layer thickness of 8–10 μm, the melting of primary B2 phase and contained therein as Ti2Ni phase particles occurs. The result is change in the concentration ratio of titanium and nickel in the direction of increasing titanium content, which was confirmed by X-ray analysis in the form of increased unit cell parameter B2 phase. Analysis of the electron diffraction pattern showed that the modified layer is characterized as a highly distorted structure on the basis of bcc lattice. Lattice distortions are maximal near the surface and extends to a depth of melt. In subjacent layer there is gradual decline lattice distortions is observed.

  17. Molecular ordering in a biaxial smectic-A phase studied by scanning transmission X-ray microscopy (STXM).

    PubMed

    Kaznacheev, Konstantin; Hegmann, Torsten

    2007-04-14

    Results of STXM investigations of a binary mixture (-TNF = 2 : 1; SmA(b) 140 M 180 Iso) known to form a SmA(b) phase [T. Hegmann, J. Kain, S. Diele, G. Pelzl and C. Tschierske, Angew. Chem. Int. Ed., 2001, 40, 887] are presented. Near edge X-ray absorption fine spectra (NEXAFS) of the -TNF board-like aggregates, in particular the intensity of the low energy peaks associated with aromatic ring pi* orbitals (284.5-286.5 eV), show that the molecular plane of these aggregates is very sensitive to the relative orientation of electric field vector E of linearly polarized light, which is used to determine the molecular orientation in the LC phase. The observed strong in-plane dichroic signal suggests the predominant orientation of the -TNF aggregates to be along the smectic layer normal as well as long-range ordering of the in-plane molecular orientation (biaxiality). Orientational maps derived from series of measurements at different sample rotation angles around the specimen normal clearly show a Schlieren-type texture, and permit a detailed examination of exclusive +/-(1/2) disclination theoretically predicted for the SmA(b) phase.

  18. In-situ x-ray microscopy of phase and composition distributions in metal alloys during solidification

    NASA Astrophysics Data System (ADS)

    Kaukler, William F.; Curreri, Peter A.

    1999-07-01

    This research applies a state of the art x-ray transmission microscope, to image the solidification of metallic or semiconductor alloys in real-time. By employing a hard x-ray source with sub-micron dimensions, resolutions of up to 2 micrometers can be obtained with magnifications of over 800 X. Specimen growth conditions were optimized and the best imaging technologies applied to maintain x-ray image resolution, contrast and sensitivity. In addition, a special furnace design is required to permit controlled growth conditions and still offer maximum resolution and image contrast. We have successfully imaged in real-time: interfacial morphologies, phase growth, coalescence, incorporation of phases into the growing interface, and the solute boundary layer in the liquid at the solid-liquid interface. We have also measured true local growth rates and can evaluate segregation structures in the solid; a form of in situ metallography. Composition gradients within the specimen cause variations in absorption of the flux such that the final image represents a spatial integration of composition. During this study, the growth of secondary phase fibers and lamellae form eutectic and monotectic alloys have been imaged during solidification, in real-time, for the first time in bulk metal alloys.

  19. In-Situ X-Ray Microscopy of Phase and Composition Distributions in Metal Alloys During Solidification

    NASA Technical Reports Server (NTRS)

    Kaukler, William F.; Curreri, Peter A.

    1999-01-01

    This research applies a state of the art X-ray Transmission Microscope, to image the solidification of metallic or semiconductor alloys in real-time. By employing a hard x-ray source with sub-micron dimensions, resolutions of up to 3 gm can be obtained with magnifications of over 800 X. Specimen growth conditions were optimized and the best imaging technologies applied to maintain x-ray image resolution, contrast and sensitivity. In addition, a special furnace design is required to permit controlled growth conditions and still offer maximum resolution and image contrast. We have successfully imaged in real-time: interfacial morphologies, phase growth, coalescence, incorporation of phases into the growing interface, and the solute boundary layer in the liquid at the solid-liquid inter-face. We have also measured true local growth rates and can evaluate segregation structures in the solid; a form of in-situ metallography. Composition gradients within the specimen cause vafiations in absorption of the flux such that the final image represents a spatial integral of composition (or thickness). During this study, the growth of secondary phase fibers and lameilae from eutectic and monotectic alloys have been imaged during solidification, in real-time, for the first time in bulk metal alloys. Keywords: x-ray, microscope, solidification, microfocus, real-time, microstructure

  20. Molecular ordering in a biaxial smectic-A phase studied byscanning transmission X-ray microscopy (STXM)

    SciTech Connect

    Kaznacheev, Konstaintin; Hegmann, Torsten

    2007-01-25

    Results of STXM investigations of a binary mixture (1-TNF =2 :1; SmAb 140 M 180 Iso) known to form a SmAb phase [T. Hegmann, J.Kain, S. Diele, G. Pelzl and C. Tschierske, Angew. Chem. Int. Ed., 2001,40, 887]are presented. Near edge X-ray absorption fine spectra (NEXAFS)of the 1-TNF board-like aggregates, in particular the intensity of thelow energy peaks associated with aromatic ring * orbitals (284.5 286.5eV), show that the molecular plane of these aggregates is very sensitiveto the relative orientation of electric field vector E of linearlypolarized light, which is used to determine the molecular orientation inthe LC phase. The observed strong in-plane dichroic signal suggests thepredominant orientation of the 1-TNF aggregates to be along the smecticlayer normal as well as long-range ordering of the in-plane molecularorientation (biaxiality). Orientational maps derived from series ofmeasurements at different sample rotation angles around the specimennormal clearly show a Schlieren-type texture, and permit a detailedexamination of exclusive +-1/2 disclination theoretically predicted forthe SmAb phase.

  1. Estimation of minimum electron dose necessary to resolve molecular structure of deoxyribonucleic acid by phase transmission electron microscopy

    SciTech Connect

    Nomaguchi, Tsunenori; Kimura, Yoshihide; Takai, Yoshizo

    2006-12-04

    The minimum electron dose that is necessary to resolve the molecular structure of deoxyribonucleic acid (DNA) was estimated based on experimental measurements of information limits and simulated DNA images, considering conditions of a low electron dose. From these results, a dose of {approx}400 e/A{sup 2} was found to be necessary to achieve observation of DNA on a molecular scale under the present experimental setup. A DNA molecule was observed by a phase reconstruction method using through-focus images under the limited electron dose. In the reconstructed images, the helical structure and the intervals of the base pairs of DNA were partially resolved.

  2. Single shot white light interference microscopy with colour fringe analysis for quantitative phase imaging of biological cells

    NASA Astrophysics Data System (ADS)

    Srivastava, Vishal; Mehta, D. S.

    2013-02-01

    To quantitatively obtain the phase map of Onion and human red blood cell (RBC) from white light interferogram we used Hilbert transform color fringe analysis technique. The three Red, Blue and Green color components are decomposed from single white light interferogram and Refractive index profile for Red, Blue and Green colour were computed in a completely non-invasive manner for Onion and human RBC. The present technique might be useful for non-invasive determination of the refractive index variation within cells and tissues and morphological features of sample with ease of operation and low cost.

  3. Quantitative phase imaging of cell division in yeast cells and E.coli using digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Pandiyan, Vimal Prabhu; John, Renu

    2015-12-01

    Digital holographic microscope (DHM) is an emerging quantitative phase imaging technique with unique imaging scales and resolutions leading to multitude of applications. DHM is promising as a novel investigational and applied tool for cell imaging, studying the morphology and real time dynamics of cells and a number of related applications. The use of numerical propagation and computational digital optics offer unique flexibility to tune the depth of focus, and compensate for image aberrations. In this work, we report imaging the dynamics of cell division in E.coli and yeast cells using a DHM platform. We demonstrate 3-D and depth imaging as well as reconstruction of phase profiles of E.coli and yeast cells using the system. We record a digital hologram of E.coli and yeast cells and reconstruct the image using Fresnel propagation algorithm. We also use aberration compensation algorithms for correcting the aberrations that are introduced by the microscope objective in the object path using linear least square fitting techniques. This work demonstrates the strong potential of a DHM platform in 3-D live cell imaging, fast clinical quantifications and pathological applications.

  4. Electron Microscopy.

    ERIC Educational Resources Information Center

    Beer, Michael

    1980-01-01

    Reviews technical aspects of structure determination in biological electron microscopy (EM). Discusses low dose EM, low temperature microscopy, electron energy loss spectra, determination of mass or molecular weight, and EM of labeled systems. Cites 34 references. (CS)

  5. Long-term measurement of spontaneous membrane fluctuations over a wide dynamic range in the living cell by low-coherent quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Yamauchi, Toyohiko; Sakurai, Takashi; Iwai, Hidenao; Yamashita, Yutaka

    2012-03-01

    Surface topography and its dynamic fluctuations in live cultured cells were obtained by low-coherent quantitative phase microscopy (LC-QPM), using 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, only the light reflected at a specific sectioning height of the sample generates interference fringes on the CCD camera. Because the digital holographic technique enables us to quantitatively measure the intensity and phase of the optical field, a nanometer-scale surface profile of a living cell can be obtained by capturing the light reflected by the cell membrane. The lateral and the vertical spatial resolution was 0.56 microns and 0.93 microns, respectively, and the mechanical stability of the phase measurement was better than 2 nanometers. The measurements were made at fast (21 frames/sec) and slow (2 frames/sec, time-lapse) frame rates and the slow measurements were performed over a period of 10 minutes. The temporal fluctuations of the cell membrane were analyzed by the mean-square-displacement (MSD) as a function of the time-difference τ. By merging the fast and slow data, the MSDs from τ = 50 msec to τ = 300 sec were obtained and wide-dynamic-range measurements of the MSDs from 2 nm2 to over 100000 nm2 were demonstrated. The results show significant differences among different cell types under various conditions.

  6. Interaction potentials of anisotropic nanocrystals from the trajectory sampling of particle motion using in situ liquid phase transmission electron microscopy

    SciTech Connect

    Chen, Qian; Cho, Hoduk; Manthiram, Karthish; Yoshida, Mark; Ye, Xingchen; Alivisatos, A. Paul

    2015-03-23

    We demonstrate a generalizable strategy to use the relative trajectories of pairs and groups of nanocrystals, and potentially other nanoscale objects, moving in solution which can now be obtained by in situ liquid phase transmission electron microscopy (TEM) to determine the interaction potentials between nanocrystals. Such nanoscale interactions are crucial for collective behaviors and applications of synthetic nanocrystals and natural biomolecules, but have been very challenging to measure in situ at nanometer or sub-nanometer resolution. Here we use liquid phase TEM to extract the mathematical form of interaction potential between nanocrystals from their sampled trajectories. We show the power of this approach to reveal unanticipated features of nanocrystal–nanocrystal interactions by examining the anisotropic interaction potential between charged rod-shaped Au nanocrystals (Au nanorods); these Au nanorods assemble, in a tip-to-tip fashion in the liquid phase, in contrast to the well-known side-by-side arrangements commonly observed for drying-mediated assembly. These observations can be explained by a long-range and highly anisotropic electrostatic repulsion that leads to the tip-selective attachment. As a result, Au nanorods stay unassembled at a lower ionic strength, as the electrostatic repulsion is even longer-ranged. Our study not only provides a mechanistic understanding of the process by which metallic nanocrystals assemble but also demonstrates a method that can potentially quantify and elucidate a broad range of nanoscale interactions relevant to nanotechnology and biophysics.

  7. The role of nanographitic phase on enhancing the electron field emission properties of hybrid granular structured diamond films: the electron energy loss spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Kurian, Joji; Jothiramalingam Sankaran, Kamatchi; Thomas, Joseph P.; Tai, N. H.; Chen, Huang-Chin; Lin, I.-Nan

    2014-10-01

    The electron field emission (EFE) properties of the hybrid granular structured diamond (HiD) films were markedly improved by N-ion implantation and annealing processes. The evolution of microstructure/bonding structure of the films due to these processes was investigated using the transmission electron microscopy (TEM) and the electron energy loss spectroscopy (EELS), respectively. The N-ion implanted/annealed HiD films showed a low turn-on field of (E0)HiD = 7.4 V µm-1 with large current density of (Je)HiD = 600 µA cm-2, at 17.8 V µm-1, compared with pristine HiD films ((E0) = 10.3 V µm-1, (Je) = 95 µA cm-2 at the same applied field). While the TEM studies revealed only the microstructural evolution due to N-ion implantation/annealing processes, the EELS elucidated the change in bonding structure, namely the transformation between the sp3-bonded carbons and the sp2-bonded ones. Therefore, the combined TEM/EELS analyses provided more insight into understand the mechanism by which the N-ion implantation/annealing processes enhanced the EFE properties of HiD films. These studies clearly demonstrated that the N-ion implantation/annealing processes induced the formation of nanographitic clusters. These nanographitic phases form an interconnected path throughout the film surface facilitating the easy transport of electrons and thereby markedly enhancing the EFE properties for the N implanted/annealed HiD films.

  8. Real-time atomic-resolution imaging of crystal growth process in water by phase modulation atomic force microscopy at one frame per second

    SciTech Connect

    Miyata, Kazuki; Asakawa, Hitoshi; Fukuma, Takeshi

    2013-11-11

    Recent advancement in dynamic-mode atomic force microscopy (AFM) has enabled its operation in liquid with atomic-scale resolution. However, its imaging speed has often been too slow to visualize atomic-scale dynamic processes. Here, we propose a method for making a significant improvement in the operation speed of dynamic-mode AFM. In this method, we use a wideband and low-latency phase detector with an improved algorithm for the signal complexification. We demonstrate atomic-scale imaging of a calcite crystal growth process in water at one frame per second. The significant improvement in the imaging speed should enable various studies on unexplored atomic-scale interfacial processes.

  9. [Investigation of characteristic microstructures of adhesive interface in wood/bamboo composite material by synchrotron radiation X-ray phase contrast microscopy].

    PubMed

    Peng, Guan-Yun; Wang, Yu-Rong; Ren, Hai-Qing; Yang, Shu-Min; Ma, Hong-Xia; Xie, Hong-Lan; Deng, Biao; Du, Guo-Hao; Xiao, Ti-Qiao

    2013-03-01

    Third-generation synchrotron radiation X-ray phase-contrast microscopy(XPCM)can be used for obtaining image with edge enhancement, and achieve the high contrast imaging of low-Z materials with the spatial coherence peculiarity of X-rays. In the present paper, the characteristic microstructures of adhesive at the interface and their penetration in wood/bamboo composite material were investigated systematically by XPCM at Shanghai Synchrotron Radiation Facility (SSRF). And the effect of several processing techniques was analyzed for the adhesive penetration in wood/bamboo materials. The results show that the synchrotron radiation XPCM is expected to be one of the important precision detection methods for wood-based panels.

  10. Nonlinear vibrational microscopy

    DOEpatents

    Holtom, Gary R.; Xie, Xiaoliang Sunney; Zumbusch, Andreas

    2000-01-01

    The present invention is a method and apparatus for microscopic vibrational imaging using coherent Anti-Stokes Raman Scattering or Sum Frequency Generation. Microscopic imaging with a vibrational spectroscopic contrast is achieved by generating signals in a nonlinear optical process and spatially resolved detection of the signals. The spatial resolution is attained by minimizing the spot size of the optical interrogation beams on the sample. Minimizing the spot size relies upon a. directing at least two substantially co-axial laser beams (interrogation beams) through a microscope objective providing a focal spot on the sample; b. collecting a signal beam together with a residual beam from the at least two co-axial laser beams after passing through the sample; c. removing the residual beam; and d. detecting the signal beam thereby creating said pixel. The method has significantly higher spatial resolution then IR microscopy and higher sensitivity than spontaneous Raman microscopy with much lower average excitation powers. CARS and SFG microscopy does not rely on the presence of fluorophores, but retains the resolution and three-dimensional sectioning capability of confocal and two-photon fluorescence microscopy. Complementary to these techniques, CARS and SFG microscopy provides a contrast mechanism based on vibrational spectroscopy. This vibrational contrast mechanism, combined with an unprecedented high sensitivity at a tolerable laser power level, provides a new approach for microscopic investigations of chemical and biological samples.

  11. Liquid-phase sample preparation method for real-time monitoring of airborne asbestos fibers by dual-mode high-throughput microscopy.

    PubMed

    Cho, Myoung-Ock; Kim, Jung Kyung; Han, Hwataik; Lee, Jeonghoon

    2013-01-01

    Asbestos that had been used widely as a construction material is a first-level carcinogen recognized by the World Health Organization. It can be accumulated in body by inhalation causing virulent respiratory diseases including lung cancer. In our previous study, we developed a high-throughput microscopy (HTM) system that can minimize human intervention accompanied by the conventional phase contrast microscopy (PCM) through automated counting of fibrous materials and thus significantly reduce analysis time and labor. Also, we attempted selective detection of chrysotile using DksA protein extracted from Escherichia coli through a recombinant protein production technique, and developed a dual-mode HTM (DM-HTM) by upgrading the HTM device. We demonstrated that fluorescently-labeled chrysotile asbestos fibers can be identified and enumerated automatically among other types of asbestos fibers or non-asbestos particles in a high-throughput manner through a newly modified HTM system for both reflection and fluorescence imaging. However there is a limitation to apply DM-HTM to airborne sample with current air collecting method due to the difficulty of applying the protein to dried asbestos sample. Here, we developed a technique for preparing liquid-phase asbestos sample using an impinger normally used to collect odor molecules in the air. It would be possible to improve the feasibility of the dual-mode HTM by integrating a sample preparation unit for making collected asbestos sample dispersed in a solution. The new technique developed for highly sensitive and automated asbestos detection can be a potential alternative to the conventional manual counting method, and it may be applied on site as a fast and reliable environmental monitoring tool.

  12. Transmission Electron Microscopy Characterization of the Bake-Hardening Behavior of Transformation-Induced Plasticity and Dual-Phase Steels

    NASA Astrophysics Data System (ADS)

    Timokhina, I. B.; Hodgson, P. D.; Pereloma, E. V.

    2007-10-01

    The effect of prestraining (PS) and bake hardening (BH) on the microstructures and mechanical properties has been studied in transformation-induced plasticity (TRIP) and dual-phase (DP) steels after intercritical annealing. The DP steel showed an increase in the yield strength and the appearance of the upper and lower yield points after a single BH treatment as compared with the as-received condition, whereas the mechanical properties of the TRIP steel remained unchanged. This difference appears to be because of the formation of plastic deformation zones with high dislocation density around the “as-quenched” martensite in the DP steel, which allowed carbon to pin these dislocations, which, in turn, increased the yield strength. It was found for both steels that the BH behavior depends on the dislocation rearrangement in ferrite with the formation of cell, microbands, and shear band structures after PS. The strain-induced transformation of retained austenite to martensite in the TRIP steel contributes to the formation of a complex dislocation structure.

  13. Three-dimensional morphological imaging of human induced pluripotent stem cells by using low-coherence quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Yamauchi, Toyohiko; Kakuno, Yumi; Goto, Kentaro; Fukami, Tadashi; Sugiyama, Norikazu; Iwai, Hidenao; Mizuguchi, Yoshinori; Yamashita, Yutaka

    2014-03-01

    There is an increasing need for non-invasive imaging techniques in the field of stem cell research. Label-free techniques are the best choice for assessment of stem cells because the cells remain intact after imaging and can be used for further studies such as differentiation induction. To develop a high-resolution label-free imaging system, we have been working on a low-coherence quantitative phase microscope (LC-QPM). LC-QPM is a Linnik-type interference microscope equipped with nanometer-resolution optical-path-length control and capable of obtaining three-dimensional volumetric images. The lateral and vertical resolutions of our system are respectively 0.5 and 0.93 μm and this performance allows capturing sub-cellular morphological features of live cells without labeling. Utilizing LC-QPM, we reported on three-dimensional imaging of membrane fluctuations, dynamics of filopodia, and motions of intracellular organelles. In this presentation, we report three-dimensional morphological imaging of human induced pluripotent stem cells (hiPS cells). Two groups of monolayer hiPS cell cultures were prepared so that one group was cultured in a suitable culture medium that kept the cells undifferentiated, and the other group was cultured in a medium supplemented with retinoic acid, which forces the stem cells to differentiate. The volumetric images of the 2 groups show distinctive differences, especially in surface roughness. We believe that our LC-QPM system will prove useful in assessing many other stem cell conditions.

  14. Analytical Microscopy

    SciTech Connect

    Not Available

    2006-06-01

    In the Analytical Microscopy group, within the National Center for Photovoltaic's Measurements and Characterization Division, we combine two complementary areas of analytical microscopy--electron microscopy and proximal-probe techniques--and use a variety of state-of-the-art imaging and analytical tools. We also design and build custom instrumentation and develop novel techniques that provide unique capabilities for studying materials and devices. In our work, we collaborate with you to solve materials- and device-related R&D problems. This sheet summarizes the uses and features of four major tools: transmission electron microscopy, scanning electron microscopy, the dual-beam focused-ion-beam workstation, and scanning probe microscopy.

  15. Advances in Urine Microscopy.

    PubMed

    Becker, Gavin J; Garigali, Giuseppe; Fogazzi, Giovanni B

    2016-06-01

    Urine microscopy is an important tool for the diagnosis and management of several conditions affecting the kidneys and urinary tract. In this review, we describe the automated instruments, based either on flow cytometry or digitized microscopy, that are currently in use in large clinical laboratories. These tools allow the examination of large numbers of samples in short periods. We also discuss manual urinary microscopy commonly performed by nephrologists, which we encourage. After discussing the advantages of phase contrast microscopy over bright field microscopy, we describe the advancements of urine microscopy in various clinical conditions. These include persistent isolated microscopic hematuria (which can be classified as glomerular or nonglomerular on the basis of urinary erythrocyte morphology), drug- and toxin-related cystalluria (which can be a clue for the diagnosis of acute kidney injury associated with intrarenal crystal precipitation), and some inherited conditions (eg, adenine phosphoribosyltransferase deficiency, which is associated with 2,8-dihydroxyadenine crystalluria, and Fabry disease, which is characterized by unique urinary lamellated fatty particles). Finally, we describe the utility of identifying "decoy cells" and atypical malignant cells, which can be easily done with phase contrast microscopy in unfixed samples. PMID:26806004

  16. An inter-laboratory study to determine the effectiveness of procedures for discriminating amphibole asbestos fibers from amphibole cleavage fragments in fiber counting by phase-contrast microscopy.

    PubMed

    Harper, Martin; Lee, Eun Gyung; Slaven, James E; Bartley, David L

    2012-07-01

    The US Occupational Safety and Health Administration (OSHA) and Mine Safety and Health Administration do not regulate cleavage fragments of amphibole and serpentine minerals as asbestos, even when particles meet the dimensional criteria for counting under standard phase-contrast microscopy methods. The OSHA ID-160 method cautions that discriminatory counting is difficult and should not be attempted unless necessary and no procedure is provided for differentiation. A standard published by the American Society for Testing and Materials (ASTM International D7200-06) includes an attempt to codify a procedure but recognizes that the procedure should be validated in an inter-laboratory study. The US National Institute for Occupational Safety and Health has carried out such a study with multiple laboratories using slides made from riebeckite and crocidolite, grunerite and amosite, tremolite and tremolite asbestos, and actinolite and actinolite asbestos using two different measurement aids (graticules). The asbestos fibers had dimensions consistent with those reported for air samples from actual amphibole asbestos operations, and the cleavage fragments were also dimensionally consistent with those found in non-asbestos mining and milling operations. The procedure for discriminating asbestos fibers from other mineral particles in the ASTM Standard calls for the recognition of characteristics supposedly common to asbestos. For the asbestos fibers created in this study, these characteristics were found not to be common and generally a function of length. More importantly, different laboratories did not recognize these features consistently. Laboratories were much more consistent in measuring dimensions, but excessive overlap in the lengths of asbestos fibers and cleavage fragments rendered length a poor criterion for discrimination. The ASTM discrimination procedure as written could not be supported on the basis of this study. Width was a much more consistent parameter for

  17. Ab initio structural and spectroscopic study of HPS{sup x} and HSP{sup x} (x = 0,+1,−1) in the gas phase

    SciTech Connect

    Yaghlane, Saida Ben; Cotton, C. Eric; Francisco, Joseph S. E-mail: hochlaf@univ-mlv.fr; Linguerri, Roberto; Hochlaf, Majdi E-mail: hochlaf@univ-mlv.fr

    2013-11-07

    Accurate ab initio computations of structural and spectroscopic parameters for the HPS/HSP molecules and corresponding cations and anions have been performed. For the electronic structure computations, standard and explicitly correlated coupled cluster techniques in conjunction with large basis sets have been adopted. In particular, we present equilibrium geometries, rotational constants, harmonic vibrational frequencies, adiabatic ionization energies, electron affinities, and, for the neutral species, singlet-triplet relative energies. Besides, the full-dimensional potential energy surfaces (PESs) for HPS{sup x} and HSP{sup x} (x = −1,0,1) systems have been generated at the standard coupled cluster level with a basis set of augmented quintuple-zeta quality. By applying perturbation theory to the calculated PESs, an extended set of spectroscopic constants, including τ, first-order centrifugal distortion and anharmonic vibrational constants has been obtained. In addition, the potentials have been used in a variational approach to deduce the whole pattern of vibrational levels up to 4000 cm{sup −1} above the minima of the corresponding PESs.

  18. A comparative calorimetric and spectroscopic study of the effects of cholesterol and of the plant sterols β-sitosterol and stigmasterol on the thermotropic phase behavior and organization of dipalmitoylphosphatidylcholine bilayer membranes.

    PubMed

    Mannock, David A; Benesch, Matthew G K; Lewis, Ruthven N A H; McElhaney, Ronald N

    2015-08-01

    We performed comparative DSC and FTIR spectroscopic measurements of the effects of β-sitosterol (Sito) and stigmasterol (Stig) on the thermotropic phase behavior and organization of DPPC bilayers. Sito and Stig are the major sterols in the biological membranes of higher plants, whereas cholesterol (Chol) is the major sterol in mammalian membranes. Sito differs in structure from Chol in having an ethyl group at C24 of the alkyl side-chain, and Stig in having both the C24 ethyl group and trans-double bond at C22. Our DSC studies indicate that the progressive incorporation of Sito and Stig decrease the temperature and cooperativity of the pretransition of DPPC to a slightly lesser and greater extent than Chol, respectively, but the pretransition persists to 10 mol % sterol concentration in all cases. All three sterols produce essentially identical effects on the thermodynamic parameters of the sharp component of the DPPC main phase transition. However, the ability to increase the temperature and decrease the cooperativity and enthalpy of the broad component decreases in the order Chol>Sito>Stig. Nevertheless, at higher Sito/Stig concentrations, there is no evidence of sterol crystallites. Our FTIR spectroscopic studies demonstrate that Sito and especially Stig incorporation produces a smaller ordering of the hydrocarbon chains of fluid DPPC bilayers than does Chol. In general, the presence of a C24 ethyl group in the alkyl side-chain reduces the characteristic effects of Chol on the thermotropic phase behavior and organization of DPPC bilayer membranes, and a trans-double bond at C22 magnifies this effect.

  19. Spectroscopic optical coherence elastography

    PubMed Central

    Adie, Steven G.; Liang, Xing; Kennedy, Brendan F.; John, Renu; Sampson, David D.; Boppart, Stephen A.

    2010-01-01

    We present an optical technique to image the frequency-dependent complex mechanical response of a viscoelastic sample. Three-dimensional hyperspectral data, comprising two-dimensional B-mode images and a third dimension corresponding to vibration frequency, were acquired from samples undergoing external mechanical excitation in the audio-frequency range. We describe the optical coherence tomography (OCT) signal when vibration is applied to a sample and detail the processing and acquisition techniques used to extract the local complex mechanical response from three-dimensional data that, due to a wide range of vibration frequencies, possess a wide range of sample velocities. We demonstrate frequency-dependent contrast of the displacement amplitude and phase of a silicone phantom containing inclusions of higher stiffness. Measurements of an ex vivo tumor margin demonstrate distinct spectra between adipose and tumor regions, and images of displacement amplitude and phase demonstrated spatially-resolved contrast. Contrast was also observed in displacement amplitude and phase images of a rat muscle sample. These results represent the first demonstration of mechanical spectroscopy based on B-mode OCT imaging. Spectroscopic optical coherence elastography (S-OCE) provides a high-resolution imaging capability for the detection of tissue pathologies that are characterized by a frequency-dependent viscoelastic response. PMID:21164898

  20. Spectroscopic optical coherence elastography.

    PubMed

    Adie, Steven G; Liang, Xing; Kennedy, Brendan F; John, Renu; Sampson, David D; Boppart, Stephen A

    2010-12-01

    We present an optical technique to image the frequency-dependent complex mechanical response of a viscoelastic sample. Three-dimensional hyperspectral data, comprising two-dimensional B-mode images and a third dimension corresponding to vibration frequency, were acquired from samples undergoing external mechanical excitation in the audio-frequency range. We describe the optical coherence tomography (OCT) signal when vibration is applied to a sample and detail the processing and acquisition techniques used to extract the local complex mechanical response from three-dimensional data that, due to a wide range of vibration frequencies, possess a wide range of sample velocities. We demonstrate frequency-dependent contrast of the displacement amplitude and phase of a silicone phantom containing inclusions of higher stiffness. Measurements of an ex vivo tumor margin demonstrate distinct spectra between adipose and tumor regions, and images of displacement amplitude and phase demonstrated spatially-resolved contrast. Contrast was also observed in displacement amplitude and phase images of a rat muscle sample. These results represent the first demonstration of mechanical spectroscopy based on B-mode OCT imaging. Spectroscopic optical coherence elastography (S-OCE) provides a high-resolution imaging capability for the detection of tissue pathologies that are characterized by a frequency-dependent viscoelastic response. PMID:21164898

  1. High-resolution transmission electron microscopy study of solid phase crystallized silicon thin films on SiO2: Crystal growth and defects formation

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Lee, J. Y.; Nam, K. S.

    1995-01-01

    A high-resolution transmission electron microscopy study of the solid phase crystallization of amorphous silicon thin films deposited on SiO2 at 520 C by low pressure chemical vapor deposition and annealed at 550 C in a dry N2 ambient was carried out so that the grain growth mechanism, various types of defects, and the origins of defect formation could be understood on an atomic level. Silicon crystallites formed at the initial stage of the crystallization had a circular shape and grains had a branched elliptical or a dendritic shape. Many twins, of which (111) coherent boundaries were parallel to the long axis of a grain, were observed in the interior of all the elongated grains. In addition to twins, the following defects are observed in the grain: intrinsic stacking faults, extrinsic stacking faults, perfect dislocations, extended screw dislocations, and Shockley partial dislocations. These defects were formed by the following reasons: errors in the stacking sequence at the amorphous/crystalline interface; jumps of a twin plane; the intersecting of two crystal growth fronts slightly misoriented; and the intersecting of two twin planes at the amorphous/crystalline interface. Among those defects, twins and stacking faults provided a preferable nucleation site for an atomic step of a (111) plane. As a result, it was concluded that grain growth in the (112) direction along the (111) plane parallel to the long axis of a grain was accelerated by twins and stacking faults.

  2. A Cell Derived Active Contour (CDAC) Method for Robust Tracking in Low Frame Rate, Low Contrast Phase Microscopy - an Example: The Human hNT Astrocyte

    PubMed Central

    Nejati Javaremi, Alireza; Unsworth, Charles P.; Graham, E. Scott

    2013-01-01

    The problem of automated segmenting and tracking of the outlines of cells in microscope images is the subject of active research. While great progress has been made on recognizing cells that are of high contrast and of predictable shape, many situations arise in practice where these properties do not exist and thus many interesting potential studies - such as the migration patterns of astrocytes to scratch wounds - have been relegated to being largely qualitative in nature. Here we analyse a select number of recent developments in this area, and offer an algorithm based on parametric active contours and formulated by taking into account cell movement dynamics. This Cell-Derived Active Contour (CDAC) method is compared with two state-of-the-art segmentation methods for phase-contrast microscopy. Specifically, we tackle a very difficult segmentation problem: human astrocytes that are very large, thin, and irregularly-shaped. We demonstrate quantitatively better results for CDAC as compared to similar segmentation methods, and we also demonstrate the reliable segmentation of qualitatively different data sets that were not possible using existing methods. We believe this new method will enable new and improved automatic cell migration and movement studies to be made. PMID:24358233

  3. Quenching Phase Separation by Vapor Deposition Polymerization

    NASA Astrophysics Data System (ADS)

    Tao, Ran; Anthamatten, Mitchell

    2015-03-01

    Initiated chemical vapor deposition (iCVD) is a solventless, free radical technique predominately used to deposit homogeneous films of linear and crosslinked polymers directly from gas phase feeds. We report a template-free method to fabricate continuous-phase porous polymer films by simultaneous phase separation during iCVD. Phase separation during film growth is achieved by condensing an inert porogen, along with initiator, monomer, and crosslinker. When the vapor mixture transports to the cooled substrate, phase separation occurs along with polymerization and crosslinking, which quench the state of phase separation. The kinetics of spontaneously phase separation can be qualitatively understood on the basis of Cahn-Hilliard theory. A series of films were grown by varying monomer and porogen's degree of saturation. Deposited films were studied by electron microscopy and spectroscopic techniques.

  4. Correlative microscopy.

    PubMed

    Loussert Fonta, Céline; Humbel, Bruno M

    2015-09-01

    In recent years correlative microscopy, combining the power and advantages of different imaging system, e.g., light, electrons, X-ray, NMR, etc., has become an important tool for biomedical research. Among all the possible combinations of techniques, light and electron microscopy, have made an especially big step forward and are being implemented in more and more research labs. Electron microscopy profits from the high spatial resolution, the direct recognition of the cellular ultrastructure and identification of the organelles. It, however, has two severe limitations: the restricted field of view and the fact that no live imaging can be done. On the other hand light microscopy has the advantage of live imaging, following a fluorescently tagged molecule in real time and at lower magnifications the large field of view facilitates the identification and location of sparse individual cells in a large context, e.g., tissue. The combination of these two imaging techniques appears to be a valuable approach to dissect biological events at a submicrometer level. Light microscopy can be used to follow a labelled protein of interest, or a visible organelle such as mitochondria, in time, then the sample is fixed and the exactly same region is investigated by electron microscopy. The time resolution is dependent on the speed of penetration and fixation when chemical fixatives are used and on the reaction time of the operator for cryo-fixation. Light microscopy can also be used to identify cells of interest, e.g., a special cell type in tissue or cells that have been modified by either transfections or RNAi, in a large population of non-modified cells. A further application is to find fluorescence labels in cells on a large section to reduce searching time in the electron microscope. Multiple fluorescence labelling of a series of sections can be correlated with the ultrastructure of the individual sections to get 3D information of the distribution of the marked proteins: array

  5. Correlative microscopy.

    PubMed

    Loussert Fonta, Céline; Humbel, Bruno M

    2015-09-01

    In recent years correlative microscopy, combining the power and advantages of different imaging system, e.g., light, electrons, X-ray, NMR, etc., has become an important tool for biomedical research. Among all the possible combinations of techniques, light and electron microscopy, have made an especially big step forward and are being implemented in more and more research labs. Electron microscopy profits from the high spatial resolution, the direct recognition of the cellular ultrastructure and identification of the organelles. It, however, has two severe limitations: the restricted field of view and the fact that no live imaging can be done. On the other hand light microscopy has the advantage of live imaging, following a fluorescently tagged molecule in real time and at lower magnifications the large field of view facilitates the identification and location of sparse individual cells in a large context, e.g., tissue. The combination of these two imaging techniques appears to be a valuable approach to dissect biological events at a submicrometer level. Light microscopy can be used to follow a labelled protein of interest, or a visible organelle such as mitochondria, in time, then the sample is fixed and the exactly same region is investigated by electron microscopy. The time resolution is dependent on the speed of penetration and fixation when chemical fixatives are used and on the reaction time of the operator for cryo-fixation. Light microscopy can also be used to identify cells of interest, e.g., a special cell type in tissue or cells that have been modified by either transfections or RNAi, in a large population of non-modified cells. A further application is to find fluorescence labels in cells on a large section to reduce searching time in the electron microscope. Multiple fluorescence labelling of a series of sections can be correlated with the ultrastructure of the individual sections to get 3D information of the distribution of the marked proteins: array

  6. Structural phase transition of ternary dielectric SmGdO{sub 3}: Evidence from angle dispersive x-ray diffraction and Raman spectroscopic studies

    SciTech Connect

    Sharma, Yogesh E-mail: satya504@gmail.com Sahoo, Satyaprakash E-mail: satya504@gmail.com Misra, Pankaj; Pavunny, Shojan P.; Katiyar, Ram S. E-mail: satya504@gmail.com; Mishra, A. K.; Dwivedi, Abhilash; Sharma, S. M.

    2015-03-07

    High-pressure synchrotron based angle dispersive x-ray diffraction (ADXRD) studies were carried out on SmGdO{sub 3} (SGO) up to 25.7 GPa at room temperature. ADXRD results indicated a reversible pressure-induced phase transition from ambient monoclinic to hexagonal phase at ∼8.9 GPa. The observed pressure-volume data were fitted with the third order Birch-Murnaghan equation of state yielding zero pressure bulk modulus B{sub 0} = 132(22) and 177(9) GPa for monoclinic (B-type) and hexagonal (A-type) phases, respectively. Pressure dependent micro-Raman spectroscopy further confirmed the monoclinic to hexagonal phase transition at about 5.24 GPa. The mode Grüneisen parameters and pressure coefficients for different Raman modes corresponding to each individual phases of SGO were calculated using pressure dependent Raman mode analysis.

  7. Spectroscopic study on the active site of a SiO2 supported niobia catalyst used for the gas-phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam.

    PubMed

    Maronna, M M; Kruissink, E C; Parton, R F; Soulimani, F; Weckhuysen, B M; Hoelderich, W F

    2016-08-10

    NbOx/SiO2 with a very high catalytic activity for the gas-phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam, was investigated by different spectroscopic methods in order to obtain new insights in the formation and nature of the active sites. FT-IR spectroscopy in combination with pyridine adsorption measurements revealed that the catalyst material contains Lewis-acidic sites, most probably related to the Nb[double bond, length as m-dash]O groups of isolated tetrahedral NbO4 surface species, whereas no Brønsted-acidic sites were observed. Results from in situ Raman and complementary FT-IR measurements strongly suggest that Brønsted-acidic Nb-OH sites can be generated from Nb[double bond, length as m-dash]O groups by reaction with ethanol. This is in agreement with the observation that ethanol is essential for obtaining a very good catalyst performance. However, the Brønsted-acidic sites can be detected in significant amounts in particular in the presence of a Lewis-base, e.g. pyridine, most probably because the formation and/or the stability of these Brønsted-acidic sites are enhanced by a basic molecule. Assuming that cyclohexanone oxime, being a base, can play a similar role as pyridine, we propose on the basis of the spectroscopic findings obtained in this work and our kinetic results published recently, a reaction scheme for the formation of the active site at the Nb[double bond, length as m-dash]O group as well as for the recovery of the Nb[double bond, length as m-dash]O site during the final stage of the gas-phase Beckmann rearrangement.

  8. A calorimetric and spectroscopic comparison of the effects of cholesterol and its sulfur-containing analogs thiocholesterol and cholesterol sulfate on the thermotropic phase behavior and organization of dipalmitoylphosphatidylcholine bilayer membranes.

    PubMed

    Benesch, Matthew G K; Lewis, Ruthven N A H; McElhaney, Ronald N

    2016-02-01

    We performed differential scanning calorimetric (DSC) and Fourier transform infrared (FTIR) spectroscopic studies of the effects of cholesterol (Chol), thiocholesterol (tChol) and cholesterol sulfate (CholS) on the thermotropic phase behavior and organization of dipalmitoylphosphatidylcholine (DPPC) bilayer membranes. Our DSC results indicate that Chol and tChol incorporation produce small temperature increases in the main phase transition broad component while CholS markedly decreases it, but Chol decreases cooperativity and enthalpy more strongly than CholS and especially tChol. Hence, Chol and tChol thermally stabilize fluid DPPC bilayer sterol-rich domains while CholS markedly destabilizes them, and CholS and particularly tChol are less miscible in such domains. Our FTIR spectroscopic results indicate that Chol incorporation increases the rotational conformational order of fluid DPPC bilayers to a slightly and somewhat greater degree than tChol and CholS, respectively, consistent with our DSC findings. Also, Chol and CholS produce comparable degrees of H-bonding (hydration) of the DPPC ester carbonyls in fluid bilayers, whereas tChol increases H-bonding. At low temperatures, Chol is fully soluble in gel-state DPPC bilayers, whereas tChol and CholS are not. Thus tChol and CholS incorporation can produce considerably different effects on DPPC bilayers. In particular, the tChol thiol group markedly reduces its lateral miscibility and increases DPPC carbonyl H-bonding without significantly affecting the other characteristic effects of Chol itself, while the CholS sulfate group significantly reduces its ability to thermally stabilize and order fluid DPPC membranes. This latter result suggests that the molecular basis for the purported ability of CholS to "stabilize" various biological membranes should be re-examined.

  9. Two experimental tests of a fluctuation-induced first-order phase transition: intensity fluctuation microscopy at the nematic-smectic-A transition.

    PubMed

    Yethiraj, Anand; Mukhopadhyay, Ranjan; Bechhoefer, John

    2002-02-01

    We have developed a new, extremely sensitive real-space technique (intensity fluctuation microscopy) to probe the order of the nematic-smectic-A (NA) transition. Using this technique, we show that the NA transition in 4'-n-octyl-4-cyanobiphenyl (8CB) is clearly first order, contrary to calorimetric studies but in agreement with conclusions drawn from front-velocity measurements. We characterize the strength of the discontinuity at the first-order transition by the dimensionless quantity t(0)=(T(NA)-T*)/T(*). By precisely measuring t(0), we have made the first detailed tests of predictions based on the Halperin-Lubensky-Ma (HLM) theory of fluctuation-induced, first-order phase transitions. First, we explore the effect of an external magnetic field on the NA transition. Although modest fields (of order 10 T) are predicted to drive the weakly first-order transition in pure 8CB second order, we observe no such effect; we establish instead that the lower bound on this critical field is approximately 30 T. Likewise, we observe no effect in mixtures of 8CB with its longer chemical homolog 4'-n-decyl-4-cyanobiphenyl (10CB). Second, we examine the dependence of t(0) as a function of 8CB-10CB mixture concentration and find that the data in mixtures with small nematic temperature range are well-fit by the parameters derived by Anisimov et al. based on calorimetric measurements. As we increase the nematic range (by using concentrations closer to pure 8CB), the measured t(0) deviates more and more from the HLM predictions. Smectic fluctuations, which are neglected in the HLM calculation, are an obvious candidate to explain such a discrepancy, but one's naive expectation is that they would reduce t(0) below the HLM levels, whereas the observed values are too large. However, a recent renormalization-group calculation concludes that smectic fluctuations, surprisingly, should indeed increase t(0), explaining the observations presented here.

  10. Direct Spectroscopic Evidence for Phase Competition between the Pseudogap and Superconductivity in Bi2Sr2CaCu2O8+δ

    SciTech Connect

    Hashimoto, Makoto; Nowadnick, Elizabeth A.; He, Rui-Hua; Vishik, Inna M.; Moritz, Brian; He, Yu; Tanaka, Kiyohisa; Moore, Robert G.; Lu, Donghui; Yoshida, Yoshiyuki; Ishikado, Motoyuki; Sasagawa, Takao; Fujita, Kazuhiro; Ishida, Shigeyuku; Uchida, Shinichi; Eisaki, Hiroshi; Hussain, Zahid; Devereaux, Thomas P.; Shen, Zhi-Xun

    2014-11-02

    In the high-temperature (Tc) cuprate superconductors, increasing evidence suggests that the pseudogap, existing below the pseudogap temperature T*, has a distinct broken electronic symmetry from that of superconductivity. Particularly, recent scattering experiments on the underdoped cuprates have suggested that a charge ordering competes with superconductivity. However, no direct link of this physics and the important low-energy excitations has been identified. We report an antagonistic singularity at Tc in the spectral weight of Bi2Sr2CaCu2O8+δ as a compelling evidence for phase competition, which persists up to a high hole concentration p ~ 0.22. Comparison with a theoretical calculation confirms that the singularity is a signature of competition between the order parameters for the pseudogap and superconductivity. Our observation of the spectroscopic singularity at finite temperatures over a wide doping range provides new insights into the nature of the competitive interplay between the two intertwined phases and the complex phase diagram near the pseudogap critical point.

  11. Spectroscopic and chemical-kinetic analysis of the phases of HCCI autoignition and combustion for single- and two-stage ignition fuels

    SciTech Connect

    Hwang, Wontae; Dec, John; Sjoeberg, Magnus

    2008-08-15

    The temporal phases of autoignition and combustion in an HCCI engine have been investigated in both an all-metal engine and a matching optical engine. Gasoline, a primary reference fuel mixture (PRF80), and several representative real-fuel constituents were examined. Only PRF80, which is a two-stage ignition fuel, exhibited a ''cool-flame'' low-temperature heat-release (LTHR) phase. For all fuels, slow exothermic reactions occurring at intermediate temperatures raised the charge temperature to the hot-ignition point. In addition to the amount of LTHR, differences in this intermediate-temperature heat-release (ITHR) phase affect the fuel ignition quality. Chemiluminescence images of iso-octane show a weak and uniform light emission during this phase. This is followed by the main high-temperature heat-release (HTHR) phase. Finally, a ''burnout'' phase was observed, with very weak uniform emission and near-zero heat-release rate (HRR). To better understand these combustion phases, chemiluminescence spectroscopy and chemical-kinetic analysis were applied for the single-stage ignition fuel, iso-octane, and the two-stage fuel, PRF80. For both fuels, the spectrum obtained during the ITHR phase was dominated by formaldehyde chemiluminescence. This was similar to the LTHR spectrum of PRF80, but the emission intensity and the temperature were much higher, indicating differences between the ITHR and LTHR phases. Chemical-kinetic modeling clarified the differences and similarities between the LTHR and ITHR phases and the cause of the enhanced ITHR with PRF80. The HTHR spectra for both fuels were dominated by a broad CO continuum with some contribution from bands of HCO, CH, and OH. The modeling showed that the CO+ O{yields}CO{sub 2}+h{nu} reaction responsible for the CO continuum emission tracks the HTHR well, explaining the strong correlation observed experimentally between the total chemiluminescence and HRR during the HTHR phase. It also showed that the CO continuum does

  12. Photoacoustic Microscopy

    PubMed Central

    Yao, Junjie; Wang, Lihong V.

    2012-01-01

    Photoacoustic microscopy (PAM) is a hybrid in vivo imaging technique that acoustically detects optical contrast via the photoacoustic effect. Unlike pure optical microscopic techniques, PAM takes advantage of the weak acoustic scattering in tissue and thus breaks through the optical diffusion limit (~1 mm in soft tissue). With its excellent scalability, PAM can provide high-resolution images at desired maximum imaging depths up to a few millimeters. Compared with backscattering-based confocal microscopy and optical coherence tomography, PAM provides absorption contrast instead of scattering contrast. Furthermore, PAM can image more molecules, endogenous or exogenous, at their absorbing wavelengths than fluorescence-based methods, such as wide-field, confocal, and multi-photon microscopy. Most importantly, PAM can simultaneously image anatomical, functional, molecular, flow dynamic and metabolic contrasts in vivo. Focusing on state-of-the-art developments in PAM, this Review discusses the key features of PAM implementations and their applications in biomedical studies. PMID:24416085

  13. Gas-Phase Folding of a Prototypical Protonated Pentapeptide: Spectroscopic Evidence for Formation of a Charge-Stabilized β-Hairpin.

    PubMed

    Burke, Nicole L; DeBlase, Andrew F; Redwine, James G; Hopkins, John R; McLuckey, Scott A; Zwier, Timothy S

    2016-03-01

    Ultraviolet and infrared-ultraviolet (IR-UV) double-resonance photofragment spectroscopy has been carried out in a tandem mass spectrometer to determine the three-dimensional structure of cryogenically cooled protonated C-terminally methyl esterified leucine enkephalin [YGGFL-OMe+H](+). By comparing the experimental IR spectrum of the dominant conformer with the predictions of DFT M05-2X/6-31+G(d) calculations, a backbone structure was assigned that is analogous to that previously assigned by our group for the unmodified peptide [ Burke, N.L.; et al. Int. J. Mass Spectrom. 2015 , 378 , 196 ], despite the loss of a C-terminal OH binding site that was thought to play an important role in its stabilization. Both structures are characterized by a type II' β-turn around Gly(3)-Phe(4) and a γ-turn around Gly(2), providing spectroscopic evidence for the formation of a β-hairpin hydrogen bonding pattern. Rather than disrupting the peptide backbone structure, the protonated N-terminus serves to stabilize the β-hairpin by positioning itself in a pocket above the turn where it can form H-bonds to the Gly(3) and C-terminus C═O groups. This β-hairpin type structure has been previously proposed as the biologically active conformation of leucine enkephalin and its methyl ester in the nonpolar cell membrane environment [ Naito, A.; Nishimura, K. Curr. Top. Med. Chem. 2004 , 4 , 135 - 143 ]. PMID:26853832

  14. Theoretical spectroscopic investigations of HNS{sup q} and HSN{sup q} (q = 0, +1, −1) in the gas phase

    SciTech Connect

    Ben Yaghlane, S. E-mail: saidayagh@gmail.com; Jaidane, N.-E.; Cotton, C. E.; Francisco, J. S.; Al Mogren, M. M.; Linguerri, R. E-mail: saidayagh@gmail.com; Hochlaf, M.

    2014-06-28

    We performed accurate ab initio investigations of the geometric parameters and the vibrational structure of neutral HNS/HSN triatomics and their singly charged anions and cations. We used standard and explicitly correlated coupled cluster approaches in connection with large basis sets. At the highest levels of description, we show that results nicely approach those obtained at the complete basis set limit. Moreover, we generated the three-dimensional potential energy surfaces (3D PESs) for these molecular entities at the coupled cluster level with singles and doubles and a perturbative treatment of triple excitations, along with a basis set of augmented quintuple-zeta quality (aug-cc-pV5Z). A full set of spectroscopic constants are deduced from these potentials by applying perturbation theory. In addition, these 3D PESs are incorporated into variational treatment of the nuclear motions. The pattern of the lowest vibrational levels and corresponding wavefunctions, up to around 4000 cm{sup −1} above the corresponding potential energy minimum, is presented for the first time.

  15. 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.

  16. Calorimetric, spectroscopic and structural investigations of phase polymorphism in [Ru(NH{sub 3}){sub 6}](BF{sub 4}){sub 3}. Part I

    SciTech Connect

    Dolega, Diana; Mikuli, Edward; Inaba, Akira; Gorska, Natalia; Holderna-Natkaniec, Krystyna; Nitek, Wojciech

    2013-01-15

    Four crystalline phases of the coordination compound [Ru(NH{sub 3}){sub 6}](BF{sub 4}){sub 3} are identified by adiabatic calorimetry. Three phase transitions, one at T{sub C3}(IV{yields}III)=30.7 K, the second at T{sub C2}(III{yields}II)=91.7 K (both accompanied by comparable entropy changes 3.0 and 3.1 J K{sup -1} mol{sup -1}, respectively) and the third at T{sub C1}(II{yields}I)=241.6 K (accompanied by an entropy change of 8.1 J K{sup -1} mol{sup -1}) were discovered. X-ray single crystal diffraction (at 293 K) demonstrates that phase I is a highly dynamic disordered cubic phase (Fm3{sup Macron }m, No. 225) with two types of BF{sub 4}{sup -} anions differing in a degree of disorder. In phase II (at 170 K) the structure remains cubic (Ia3{sup Macron }, No. 206), with two different types of cations and four different types of anions. Splitting of certain IR bands connected with NH{sub 3} ligands at the observed phase transitions suggests a lowering of the symmetry of the [Ru(NH{sub 3}){sub 6}]{sup 3+} complex cation. Both NH{sub 3} ligands and BF{sub 4}{sup -} anions perform fast reorientations ({tau}{sub R} Almost-Equal-To 10{sup -12} s), which are significantly slowed down below the phase transition at T{sub C3}. {sup 1}H NMR studies led to estimate the values of the activation energy of NH{sub 3} ligands reorientation in the phases II and I as equal to {approx}8 kJ mol{sup -1}. In phase I the whole hexammineruthenium(III) cations reorientation as a tumbling process can be noticed. The activation energy value of this motion is {approx}24 kJ mol{sup -1}. {sup 19}F NMR studies give the values of the activation energy of BF{sub 4}{sup -} anions reorientation as {approx}6 kJ mol{sup -1}. Above the phase transition temperature half of BF{sub 4}{sup -} anions perform a tumbling motion with E{sub a} Almost-Equal-To 8 kJ mol{sup -1}. - Graphical abstract: A series of complementary methods, such as Adiabatic Calorimetry, Differential Scanning Calorimetry, Fourier

  17. Applied quantum chemistry: Spectroscopic detection and characterization of the F{sub 2}BS and Cl{sub 2}BS free radicals in the gas phase

    SciTech Connect

    Jin, Bing; Clouthier, Dennis J.; Sheridan, Phillip M.

    2015-03-28

    In this and previous work [D. J. Clouthier, J. Chem. Phys. 141, 244309 (2014)], the spectroscopic signatures of the X{sub 2}BY (X = H, halogen, Y = O, S) free radicals have been predicted using high level ab initio theory. The theoretical results have been used to calculate the electronic absorption and single vibronic level (SVL) emission spectra of the radicals under typical jet-cooled conditions. Using these diagnostic predictions, the previously unknown F{sub 2}BS and Cl{sub 2}BS free radicals have been identified and characterized. The radicals were prepared in a free jet expansion by subjecting precursor mixtures of BF{sub 3} or BCl{sub 3} and CS{sub 2} vapor to an electric discharge at the exit of a pulsed molecular beam valve. The B{sup ~2}A{sub 1}–X{sup ~} {sup 2}B{sub 2} laser-induced fluorescence spectra were found within 150 cm{sup −1} of their theoretically predicted positions with vibronic structure consistent with our Franck-Condon simulations. The B{sup ~2}A{sub 1} state emits down to the ground state and to the low-lying A{sup ~2}B{sub 1} excited state and the correspondence between the observed and theoretically derived SVL emission Franck-Condon profiles was used to positively identify the radicals and make assignments. Excited state Coriolis coupling effects complicate the emission spectra of both radicals. In addition, a forbidden component of the electronically allowed B{sup ~}–X{sup ~} band system of Cl{sub 2}BS is evident, as signaled by the activity in the b{sub 2} modes in the spectrum. Symmetry arguments indicate that this component gains intensity due to a vibronic interaction of the B{sup ~2}A{sub 1} state with a nearby electronic state of {sup 2}B{sub 2} symmetry.

  18. Applied quantum chemistry: Spectroscopic detection and characterization of the F2BS and Cl2BS free radicals in the gas phase.

    PubMed

    Jin, Bing; Sheridan, Phillip M; Clouthier, Dennis J

    2015-03-28

    In this and previous work [D. J. Clouthier, J. Chem. Phys. 141, 244309 (2014)], the spectroscopic signatures of the X2BY (X = H, halogen, Y = O, S) free radicals have been predicted using high level ab initio theory. The theoretical results have been used to calculate the electronic absorption and single vibronic level (SVL) emission spectra of the radicals under typical jet-cooled conditions. Using these diagnostic predictions, the previously unknown F2BS and Cl2BS free radicals have been identified and characterized. The radicals were prepared in a free jet expansion by subjecting precursor mixtures of BF3 or BCl3 and CS2 vapor to an electric discharge at the exit of a pulsed molecular beam valve. The B̃(2)A1-X̃(2)B2 laser-induced fluorescence spectra were found within 150 cm(-1) of their theoretically predicted positions with vibronic structure consistent with our Franck-Condon simulations. The B̃(2)A1 state emits down to the ground state and to the low-lying Ã(2)B1 excited state and the correspondence between the observed and theoretically derived SVL emission Franck-Condon profiles was used to positively identify the radicals and make assignments. Excited state Coriolis coupling effects complicate the emission spectra of both radicals. In addition, a forbidden component of the electronically allowed B̃-X̃ band system of Cl2BS is evident, as signaled by the activity in the b2 modes in the spectrum. Symmetry arguments indicate that this component gains intensity due to a vibronic interaction of the B̃(2)A1 state with a nearby electronic state of (2)B2 symmetry.

  19. Nuclear magnetic resonance spectroscopic investigations of phase biaxiality in the nematic glass of a shape-persistent V-shaped mesogen.

    PubMed

    Figueirinhas, João L; Feio, Gabriel; Cruz, Carlos; Lehmann, Matthias; Köhn, Christiane; Dong, Ronald Y

    2010-11-01

    Deuterium and carbon-13 NMR spectroscopy were used to study both the high temperature uniaxial nematic and the low temperature biaxial nematic glass of a shape-persistent V-shaped mesogen. It was found that biaxial ordering determined in the domains of the latter has symmetry lower than D(2h) and is compatible with C(2h) symmetry or lower. In particular, elements of the ordering matrix including biaxial phase order parameters were determined from (2)H NMR at two temperatures, one just below the glass transition, and the other deep inside the biaxial glass, which allowed for the characterization of the dominant molecular motions at these temperatures. (13)C NMR magic angle spinning sideband patterns, collected both in the high temperature nematic phase and in the nematic glass, clearly show the difference between them in terms of the phase symmetry.

  20. FT-IR Spectroscopic Evidence Of Phase Transition For NaA-ROH-Kerosine-H2O Microemulsion System Containing Nd3+ Ions

    NASA Astrophysics Data System (ADS)

    Liao, Hua; Xu, Zhen-Hua; Shi, Nai; Wu, Jin-Guang; Xu, Guang-Xian

    1989-12-01

    In the previous investigation, the saponification of naphthenic acid extractant system has been proved to be a process of the formation of a microemulsion of 14/0 type, and its full extraction of rare earths is a process of destruction of the W/O microemulsion[1]. When NdCl3 is partially extracted with NaA (sodium naphthenate) secoctylalcohol-- kerosine-- water microemulsion system (ME), both the NdA3 and the NaA co-exist in the same organic phase. However,the formation mechanism of microemulsion containing neodymium has not been much studied. In this paper, 10 aliquots of fully saponificated extractants were equilibrated with various amounts of NdC13 solutions respectively, then ten organic phases with different extraction efficiencies of neodymium from 094 to 9094 were obtained. After extraction,the volume of neodymium containing organic phase increased by 5 to 4594, because of the transfer of water molecules. The appearance of these organic phase still remained clear and transparent. The average hydrodynamic radius of the drops were found to be 100-300 Angstrom by using light scattering techniques. The results give a direct evidence of the microemulsion formation in the organic phase. Their FT-IR spectra were measured with CaFa liquid cells utilizing a Nicolet 7199B FT-IR spectrometer. The presence of various amounts of water in the organic phases was clearly detected from the relative intensity changes of 1644 cm-I, which is assigned to the bending mode of 1110 molecules. Fig.1 shows the change of water contents to the percent extraction of neodymium. Comparsion with the FT-IR spectra, it is seen that the 1560 cm-1 peak of the full saponificated extractant is attributed to the asym. stretching vibration of COO''' group, it shifted to 1536 for 100% extration of Nd ions, indicating the formation of neodymium naphthenate (NdA ) from ionic sodium naphthenate. The sym. strethching vibration of COO''' located at 1406 cm-1, it shifted to 1408 cm in 45% Nd extration

  1. Theoretical Modeling of the Chirality Discrimination of Enantiomers by Nanotubular Cyclic Peptides using Gas-Phase Photoelectron Spectroscopy: An ONIOM Spectroscopic Calculations.

    PubMed

    Farrokhpour, H; Karachi, S; Chermahini, A Najafi

    2016-09-01

    In the present work, the chirality recognition of the enantiomers of a chiral molecule (1-phenyl-1-propanol) interacting with a nanotubular cyclic peptide (E-type cyclic decapeptide) was investigated by their ionization in the gas phase, theoretically. The absolute energy difference between the interaction of the S- and R-enantiomer with the cyclic peptide, calculated at the M06-2X/6-311++G(d, p) level of theory, was 4.70 kcal·mol(-1). Two different schemes of "Our own N-layered Integrated molecular Orbital and molecular Mechanics (ONIOM)" method such as (quantum mechanics (QM):molecular mechanics (MM)) and (QM:QM) were employed to study the effect of the interaction on the gas-phase ionization energies of the enantiomers and cyclic peptide, separately. The symmetry-adapted cluster/configuration interaction (SAC-CI) methodology was used for the calculation of the ionization energies. It was found that the difference between the interactions of R- and S-enantiomer with the cyclic peptide caused different changes in the photoelectron spectrum of each enantiomer so that these changes could be used for the chirality discrimination of the enantiomers in the gas phase. Similarly, the photoelectron spectrum of the cyclic peptide interacting with the R and S-enantiomer were calculated, separately, and it was observed that the difference in the interaction with the R- and S-enantiomer created different changes in the spectrum of cyclic peptide. Finally, it was shown that the difference in the interaction of cyclic peptide with the enantiomers of a chiral molecule in the gas phase can be used for the identification of enantiomers in the gas phase by the direct ionization. PMID:27500312

  2. Variations in elemental compositions of rat hippocampal formation between acute and latent phases of pilocarpine-induced epilepsy: an X-ray fluorescence microscopy study.

    PubMed

    Chwiej, J; Dulinska, J; Janeczko, K; Appel, K; Setkowicz, Z

    2012-06-01

    There is growing experimental evidence that tracing the elements involved in brain hyperexcitability, excitotoxicity, and/or subsequent neurodegeneration could be a valuable source of data on the molecular mechanisms triggering or promoting further development of epilepsy. The most frequently used experimental model of the temporal lobe epilepsy observed in clinical practice is the one based on pilocarpine-induced seizures. In the frame of this study, the elemental anomalies occurring for the rat hippocampal tissue in acute and silent periods after injection of pilocarpine in rats were compared. X-ray fluorescence microscopy was applied for the topographic and quantitative elemental analysis. The differences in the levels of elements such as P, S, K, Ca, Fe, Cu, and Zn between the rats 3 days (SE72) and 6 h (SE6) after pilocarpine injection as well as naive controls were examined. Comparison of SE72 and control groups showed, for specific areas of the hippocampal formation, lower levels of P, K, Cu, and Zn, and an increase in Ca accumulation. These results as well as further analysis of the differences between the SE72 and SE6 groups confirmed that seizure-induced excitotoxicity as well as mossy fiber sprouting are the mechanisms involved in the neurodegenerative processes which may finally lead to spontaneous seizures in the chronic period of the pilocarpine model. Moreover, in the light of the results obtained, Cu seems to play a very important role in the pathogenesis of epilepsy in this animal model. For all areas analyzed, the levels of this element recorded in the latent period were not only lower than those for controls but were even lower than the levels found in the acute period. The decreased hippocampal accumulation of Cu in the phase of behavior and EEG stabilization, a possible inhibitory effect of this element on excitatory amino acid receptors, and enhanced seizure susceptibility in Menkes disease (an inherited Cu transport disorder leading to Cu

  3. Endoscopic Microscopy

    PubMed Central

    Sokolov, Konstantin; Sung, Kung-Bin; Collier, Tom; Clark, Anne; Arifler, Dizem; Lacy, Alicia; Descour, Michael; Richards-Kortum, Rebecca

    2002-01-01

    In vivo endoscopic optical microscopy provides a tool to assess tissue architecture and morphology with contrast and resolution similar to that provided by standard histopathology – without need for physical tissue removal. In this article, we focus on optical imaging technologies that have the potential to dramatically improve the detection, prevention, and therapy of epithelial cancers. Epithelial pre-cancers and cancers are associated with a variety of morphologic, architectural, and molecular changes, which currently can be assessed only through invasive, painful biopsy. Optical imaging is ideally suited to detecting cancer-related alterations because it can detect biochemical and morphologic alterations with sub-cellular resolution throughout the entire epithelial thickness. Optical techniques can be implemented non-invasively, in real time, and at low cost to survey the tissue surface at risk. Our manuscript focuses primarily on modalities that currently are the most developed: reflectance confocal microscopy (RCM) and optical coherence tomography (OCT). However, recent advances in fluorescence-based endoscopic microscopy also are reviewed briefly. We discuss the basic principles of these emerging technologies and their current and potential applications in early cancer detection. We also present research activities focused on development of exogenous contrast agents that can enhance the morphological features important for cancer detection and that have the potential to allow vital molecular imaging of cancer-related biomarkers. In conclusion, we discuss future improvements to the technology needed to develop robust clinical devices. PMID:14646041

  4. Synthesis of few layer graphene by direct exfoliation of graphite and a Raman spectroscopic study

    NASA Astrophysics Data System (ADS)

    Gayathri, S.; Jayabal, P.; Kottaisamy, M.; Ramakrishnan, V.

    2014-02-01

    The exfoliation of graphene from pristine graphite in a liquid phase was achieved successfully via sonication followed by centrifugation method. Ultraviolet-visible (UV-vis) spectra of the obtained graphene dispersions at different exfoliation time indicated that the concentration of graphene dispersion increased markedly with increasing exfoliation time. The sheet-like morphology of the exfoliated graphene was revealed by Scanning Electron Microscopy (SEM) image. Further, the morphological change in different exfoliation time was investigated by Atomic Force Microscopy (AFM). A complete structural and defect characterization was probed using micro-Raman spectroscopic technique. The shape and position of the 2D band of Raman spectra revealed the formation of bilayer to few layer graphene. Also, Raman mapping confirmed the presence of uniformly distributed bilayer graphene sheets on the substrate.

  5. Noninvasive in-vivo near-infrared vibrational spectroscopic study of lipid and aqueous phases of skin and near-surface tissues

    NASA Astrophysics Data System (ADS)

    Chaiken, Joseph; Finney, William F.; Peterson, Karen P.; Peterson, Charles M.; Knudson, Paul E.; Weinstock, Ruth S.; Lein, Paul

    2000-05-01

    We report the use of near infrared vibrational spectroscopy to noninvasively probe the in-vivo lipid and aqueous phases of skin and near surface tissues under conditions of thermal and chemical modulation. We demonstrate thermally induced order- disorder transitions in lipids that can be directly compared to well known behavior of in-vitro samples of phospholipid bilayers and bulk fatty acids. We show reversible chemical modification of aqueous phase proteins which are also directly comparable to well known phenomena involving in-vitro proteins. The results of these studies demonstrate the capacity for noninvasively probing live human tissues on the molecular level using near infrared vibrational spectroscopy. This capacity suggests numerous potential applications ranging from assessing the efficacy of cosmetics, skin care treatments and transdermal therapeutic agents/treatments to serving as a diagnostic of various skin ailments, e.g. melanoma.

  6. Theoretical interpretation of electron energy-loss spectroscopic images

    DOE PAGESBeta

    Allen, L. J.; D'Alfonso, Adrian J.; Findlay, Scott D.; Oxley, Mark P.; Bosman, M.; Keast, V. J.; Cossgriff, E. C.; Behan, G.; Nellist, P. D.; Kirkland, Angus I.

    2008-04-10

    In this paper, we discuss the theory of electron energy-loss spectroscopic images in scanning transmission electron microscopy. Three case studies are presented which have as common themes issues of inelastic scattering, coherence and image interpretation. The first is a state-by-state inelastic transitions analysis of a spectroscopic image which does not admit direct visual interpretation. The second compares theory and experiment for two-dimensional mapping. Finally, the third considers imaging in three dimensions via depth sectioning.

  7. A new miniature hydrostatic pressure chamber for microscopy. Strain- free optical glass windows facilitate phase-contrast and polarized- light microscopy of living cells. Optional fixture permits simultaneous control of pressure and temperature

    PubMed Central

    1975-01-01

    This paper describes the development of a miniature, temperature- controlled, stainless steel pressure chamber which uses strain-free optical glass for windows. It is directly adaptable to standard phase- contrast and polarized-light microscopes and requires a minimum amount of equipment to generate and measure pressure. Birefringence retardation (BR) og 0.1 nm up to 3,000 psi, 0.4 nm up to 5,000 psi and 1.0 nm up to 10,000 psi can be detected over a 0.75-mm central field with two strain-free Leitz 20 times UM objectives, one used as a condenser. In phase-contrast studies a Nikon DML 40 times phase objective and Zeiss model IS long working-distance phase condenser were used, with little deterioration of image quality or contrast at pressures as high as 12,000 psi. The actual design process required a synthesis of various criteria which may be categorized under four main areas of consideration: (a) specimen physiology; (b) constraints imposed by available optical equipment and standard microscope systems; (c) mechanical strength and methods for generating pressure; and (d) optical requirements of the chamber windows. Procedures for using the chambers, as well as methods for shifting and controlling the temperature within the chamber, are included. PMID:1094021

  8. A new miniature hydrostatic pressure chamber for microscopy. Strain-free optical glass windows facilitate phase-contrast and polarized-light microscopy of living cells. Optional fixture permits simultaneous control of pressure and temperature.

    PubMed

    Salmon, E D; Ellis, G W

    1975-06-01

    This paper describes the development of a miniature, temperature-controlled, stainless steel pressure chamber which uses strain-free optical glass for windows. It is directly adaptable to standard phase-contrast and polarized-light microscopes and requires a minimum amount of equipment to generate and measure pressure. Birefringence retardation (BR) og 0.1 nm up to 3,000 psi, 0.4 nm up to 5,000 psi and 1.0 nm up to 10,000 psi can be detected over a 0.75-mm central field with two strain-free Leitz 20 times UM objectives, one used as a condenser. In phase-contrast studies a Nikon DML 40 times phase objective and Zeiss model IS long working-distance phase condenser were used, with little deterioration of image quality or contrast at pressures as high as 12,000 psi. The actual design process required a synthesis of various criteria which may be categorized under four main areas of consideration: (a) specimen physiology; (b) constraints imposed by available optical equipment and standard microscope systems; (c) mechanical strength and methods for generating pressure; and (d) optical requirements of the chamber windows. Procedures for using the chambers, as well as methods for shifting and controlling the temperature within the chamber, are included. PMID:1094021

  9. Topographical and Chemical Imaging of a Phase Separated Polymer Using a Combined Atomic Force Microscopy/Infrared Spectroscopy/Mass Spectrometry Platform

    DOE PAGESBeta

    Tai, Tamin; Karácsony, Orsolya; Bocharova, Vera; Van Berkel, Gary J.; Kertesz, Vilmos

    2016-02-18

    This article describes how the use of a hybrid atomic force microscopy/infrared spectroscopy/mass spectrometry imaging platform was demonstrated for the acquisition and correlation of nanoscale sample surface topography and chemical images based on infrared spectroscopy and mass spectrometry.

  10. Calibration method for spectroscopic systems

    DOEpatents

    Sandison, David R.

    1998-01-01

    Calibration spots of optically-characterized material placed in the field of view of a spectroscopic system allow calibration of the spectroscopic system. Response from the calibration spots is measured and used to calibrate for varying spectroscopic system operating parameters. The accurate calibration achieved allows quantitative spectroscopic analysis of responses taken at different times, different excitation conditions, and of different targets.

  11. Calibration method for spectroscopic systems

    DOEpatents

    Sandison, D.R.

    1998-11-17

    Calibration spots of optically-characterized material placed in the field of view of a spectroscopic system allow calibration of the spectroscopic system. Response from the calibration spots is measured and used to calibrate for varying spectroscopic system operating parameters. The accurate calibration achieved allows quantitative spectroscopic analysis of responses taken at different times, different excitation conditions, and of different targets. 3 figs.

  12. Growth models of coexisting p(2 × 1) and c(6 × 2) phases on an oxygen-terminated Cu(110) surface studied by noncontact atomic force microscopy at 78 K.

    PubMed

    Li, Yan Jun; Lee, Seung Hwan; Kinoshita, Yukinori; Ma, Zong Min; Wen, Huanfei; Nomura, Hikaru; Naitoh, Yoshitaka; Sugawara, Yasuhiro

    2016-05-20

    We present an experimental study of coexisting p(2 × 1) and c(6 × 2) phases on an oxygen-terminated Cu(110) surface by noncontact atomic force microscopy (NC-AFM) at 78 K. Ball models of the growth processes of coexisting p(2 × 1)/c(6 × 2) phases on a terrace and near a step are proposed. We found that the p(2 × 1) and c(6 × 2) phases are grown from the super Cu atoms on both sides of O-Cu-O rows of an atomic spacing. In this paper, we summarize our investigations of an oxygen-terminated Cu(110) surface by NC-AFM employing O- and Cu-terminated tips. Also, we state several problems and issues for future investigation.

  13. Spectroscopic and modeling investigations of the gas phase chemistry and composition in microwave plasma activated B2H6/CH4/Ar/H2 mixtures.

    PubMed

    Ma, Jie; Richley, James C; Davies, David R W; Ashfold, Michael N R

    2010-09-23

    A comprehensive study of microwave (MW) activated B2H6/CH4/Ar/H2 plasmas used for the chemical vapor deposition of B-doped diamond is reported. Absolute column densities of ground state B atoms, electronically excited H(n = 2) atoms, and BH, CH, and C2 radicals have been determined by cavity ring down spectroscopy, as functions of height (z) above a molybdenum substrate and of the plasma process conditions (B2H6, CH4, and Ar partial pressures; total pressure, p; and supplied MW power, P). Optical emission spectroscopy has also been used to explore variations in the relative densities of electronically excited H atoms, H2 molecules, and BH, CH, and C2 radicals, as functions of the same process conditions. These experimental data are complemented by extensive 2D(r, z) modeling of the plasma chemistry, which result in substantial refinements to the existing B/C/H/O thermochemistry and chemical kinetics. Comparison with the results of analogous experimental/modeling studies of B2H6/Ar/H2 and CH4/Ar/H2 plasmas in the same MW reactor show that: (i) trace B2H6 additions have negligible effect on a pre-established CH4/Ar/H2 plasma; (ii) the spatial extent of the B and BH concentration profiles in a B2H6/CH4/Ar/H2 plasma is smaller than in a hydrocarbon-free B2H6/Ar/H2 plasma operating at the same p, P, etc.; (iii) B/C coupling reactions (probably supplemented by reactions involving trace O2 present as air impurity in the process gas mixture) play an important role in determining the local BHx (x = 0-3) radical densities; and (iv) gas phase B atoms are the most likely source of the boron that incorporates into the growing B-doped diamond film. PMID:20735120

  14. Divalent cation-induced variations in polyelectrolyte conformation and controlling calcite morphologies: direct observation of the phase transition by atomic force microscopy.

    PubMed

    Pai, Ranjith Krishna; Pillai, Saju

    2008-10-01

    In the biomineralization process, the changes in conformation of organic matrix may be a widespread phenomenon. Investigation of the structural relationship between organic and inorganic materials is the main subject. The approach taken was to extract quantitative information of the variations in polyelectrolyte conformation during the mineralization process using atomic force microscopy. The results infer the evidence of the role of polyelectrolyte conformation in mineralization of calcium carbonate and the methods for understanding the principle that govern biomineralization.

  15. 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

  16. Scanning Tunneling Optical Resonance Microscopy Developed

    NASA Technical Reports Server (NTRS)

    Bailey, Sheila G.; Raffaelle, Ryne P.; Lau, Janis E.; Jenkins, Phillip P.; Castro, Stephanie L.; Tin, Padetha; Wilt, David M.; Pal, Anna Maria; Fahey, Stephen D.

    2004-01-01

    The ability to determine the in situ optoelectronic properties of semiconductor materials has become especially important as the size of device architectures has decreased and the development of complex microsystems has increased. Scanning Tunneling Optical Resonance Microscopy, or STORM, can interrogate the optical bandgap as a function of its position within a semiconductor micro-structure. This technique uses a tunable solidstate titanium-sapphire laser whose output is "chopped" using a spatial light modulator and is coupled by a fiber-optic connector to a scanning tunneling microscope in order to illuminate the tip-sample junction. The photoenhanced portion of the tunneling current is spectroscopically measured using a lock-in technique. The capabilities of this technique were verified using semiconductor microstructure calibration standards that were grown by organometallic vapor-phase epitaxy. Bandgaps characterized by STORM measurements were found to be in good agreement with the bulk values determined by transmission spectroscopy and photoluminescence and with the theoretical values that were based on x-ray diffraction results.

  17. A scanning tunneling microscopy investigation of the phases formed by the sulfur adsorption on Au(100) from an alkaline solution of 1,4-piperazine(bis)-dithiocarbamate of potassium

    NASA Astrophysics Data System (ADS)

    Martínez, Javier A.; Valenzuela B., José; Cao Milán, R.; Herrera, José; Farías, Mario H.; Hernández, Mayra P.

    2014-11-01

    Piperazine-dithiocarbamate of potassium (K2DTC2pz) was used as a new precursor for the spontaneous deposition of sulfur on the Au(100) surface in alkaline solution. Two new sulfur phases were studied by scanning tunneling microscopy (STM). These phases were formed by six sulfur atoms (S6 phase, hexamer) and by four sulfur atoms (S4 phase, tetramer with (√{ 2} ×√{ 2}) structure), and they were observed in coexistence with the well-known quasi-square patterns formed by eight sulfur atoms (S8 phase, octomer). A model was proposed where sulfur multilayers were formed by a (√{ 2} ×√{ 2}) phase adsorbed directly on the gold surface while one of the other structures: hexamers or octomers were deposited on top. Sulfur layers were formed on gold terraces, vacancies and islands produced by lifting reconstructed surface. Sequential high-resolution STM images allowed the direct observation of the dynamic of the octomers, while the (√{ 2} ×√{ 2}) structure remained static. Images also showed the reversible association/dissociation of the octomer.

  18. Phase transformations in 40-60-GPa shocked gneisses from the Haughton Crater (Canada): An Analytical Transmission Electron Microscopy (ATEM) study

    NASA Technical Reports Server (NTRS)

    Martinez, I.; Guyot, F.; Schaerer, U.

    1992-01-01

    In order to better understand phase transformations, chemical migration, and isotopic disequilibrium in highly shocked rocks, we have performed a microprobe and an ATEM study on gneisses shocked up to 60 GPa from the Haughton Crater. This study reveals the following chemical and structural characteristics: (1) SiO2 dominant areas are formed by a mixture of pure SiO2 polycrystalline quartz identified by electron diffraction pattern and chemical analysis and a silica-rich amorphous phase containing minor amounts of aluminium, potassium, and iron; (2) Areas with biotitelike composition are formed by less than 200-nm grains of iron-rich spinels embedded in a silica-rich amorphous phase that is very similar to the one described above; (3) Layers with feldsparlike composition are constituted by 100-200-nm-sized alumina-rich grains (the indexation of the crystalline structure is under progress) and the silica-rich amorphous phase; (4) Zones characterized by the unusual Al/Si ratio close to 1 are formed by spinel grains (200-nm-sized) embedded in the same silica-rich amorphous phase; and (5) The fracturated sillimanites contain domains with a lamellar structure, defined by the intercalation of 100-nm-wide lamellae of mullite crystals and of a silica-rich amorphous phase. These mullite crystals preserved the crystallographical orientation of the preshock sillimanite. All compositional domains, identified at the microprobe scale, can thus be explained by a mixture in different proportion between the following phases: (1) a silica-rich amorphous phase, with minor Al and K; (2) quartz crystals; (3) spinel crystals and alumina-rich crystals; (4) sillimanite; and (5) mullite. Such mixtures of amorphous phases and crystals in different proportions explain disturbed isotope systems in these rocks and chemical heterogeneities observed on the microprobe.

  19. Confocal microscopy in transmitted light

    NASA Astrophysics Data System (ADS)

    Dodt, Hans-Ulrich; Becker, Klaus

    2003-10-01

    We developed a confocal microscope for transmitted light to visualize fine details in phase objects like unstained biological specimens. The main difficulty of confocal microscopy in transmission is the alignment of illumination and detector pinholes. This alignment was achieved by using "electronic pinholes" on the detector side. As a first step, we were able to image cells in onion skin at greater depths and with higher resolution than by using conventional microscopy.

  20. Temperature dependence of Peierls-Hubbard phase transition in [Pd(cptn)2Br]Br2 studied by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Hosomi, Yuka; Yoshida, Shoji; Taninaka, Atsushi; Yoshida, Takefumi; Takaishi, Shinya; Takeuchi, Osamu; Yamashita, Masahiro; Shigekawa, Hidemi

    2016-08-01

    The temperature dependence of the Peierls-Hubbard phase transition in [Pd(cptn)2Br]Br2 (cptn: 1R,2R-diaminocyclopentane) was directly observed using a low-temperature scanning tunneling microscope. A short ligand without alkyl chains was used to form a rigid crystal lattice to reduce the effect of structural changes in the crystal with temperature. The hysteresis in the temperature dependence of the ratio between the areas of the charge density wave (CDW) state produced by the PdII-PdIV mixed-valence state and the Mott-Hubbard (MH) state with a PdIII-averaged valence state which is a characteristic of the first-order phase transition, was directly observed at the atomic scale. Pinning of the CDW phase by defects was observed below the critical temperature, suggesting the growth of the CDW phase with defects as nuclei.

  1. Quasiparticles in the pseudogap Phase of Underdoped Cuprate

    SciTech Connect

    Yang, K.; Yang, H; Johnson, P; Rice, T; Zhang, F

    2009-01-01

    Recent angle-resolved photoemission (Yang H.-B. et al., Nature, 456 (2008) 77) and scanning tunneling microscopy (Kohsaka Y. et al., Nature, 454 (2008) 1072) measurements on underdoped cuprates have yielded new spectroscopic information on quasiparticles in the pseudogap phase. New features of the normal state such as particle-hole asymmetry, maxima in the energy dispersion, and accompanying drops in the spectral weight of quasiparticles agree with the ansatz of Yang et al. for the single-particle propagator in the pseudogap phase. The coherent quasiparticle dispersion and reduced asymmetry in the tunneling density of states in the superconducting state can also be described by this propagator.

  2. Scanning electron microscopy and transmitted electron backscatter diffraction examination of asbestos standard reference materials, amphibole particles of differing morphology, and particle phase discrimination from talc ores.

    PubMed

    Bandli, Bryan R; Gunter, Mickey E

    2014-12-01

    Since 1972, when the US Occupational Health and Safety Administration established the first limits on occupational exposure to asbestos fibers, numerous analytical methods employing several microscopy techniques have been developed to identify a group of minerals defined by legislation as asbestos. While transmission electron microscopy (TEM) is implemented in standardized analytical methods, these methods specify the use of selected area electron diffraction. Because of this constraint, the diffraction data a TEM can provide are often underutilized due to challenges associated with collecting and interpreting individual diffraction patterns. It has been shown that transmission electron backscatter diffraction (tEBSD) produces diffraction patterns nearly identical to electron backscatter diffraction, but from smaller crystal domains. This paper explores the utility of tEBSD for characterization of asbestiform particles from reference asbestos materials, a suite of amphibole minerals of varying morphologies to determine if there is a correlation between mineral habit (i.e., crystal form), microscopic particle shape preferred orientation, and mineral specimens from an industrial talc deposit to provide a case study of the utility and limitations of the technique.

  3. Analytical electron microscopy studies of interfaces and phase transformations in zirconia ceramic systems: Progress report, July 1, 1987-June 30, 1988

    SciTech Connect

    Notis, M.R.

    1988-01-01

    Goal is to gain an understanding of the nature of interphase interfaces, phase-equilibria and phase transformations in ceramic systems which have high potential for property improvement through transformation toughening. We have focused our attention on studies concerning: (1) the nature of interphase interfaces in zirconia based eutectics, and (2) the effects of ternary additions on the growth kinetics of precipitates in magnesia partially stabilized zirconia (Mg-PSZ) ceramics. We have been able to use our understanding of twinning behavior to explain the nature of twin structure present in ceramic superconductors.

  4. Analytical electron microscopy studies of interfaces and phase transformations in zirconia ceramic systems: Progress report, July 1, 1988--June 30, 1989

    SciTech Connect

    Notis, M.R.

    1989-01-01

    The goal of this research is to gain an understanding of the nature of interphase interfaces, phase-equilibria and phase transformations in ceramic systems which have high potential for property improvement through transformation toughening. We have focused our attention on studies concerning: (1) The nature of interphase interfaces in zirconia based eutectics (because of the well defined orientation relationships present at eutectic interfaces). The first model system which we have extensively studied is the NiO-ZrO/sub 2/ (CaO) (NZ) DSE system. (2) The effects of ternary additions on the growth kinetics of precipitates in magnesia partially stabilized zirconia (Mg PSZ) ceramics.

  5. Interband electronic transitions and phase transformation of multiferroic Bi{sub 1−x}La{sub x}Fe{sub 1−y}Ti{sub y}O{sub 3} ceramics revealed by temperature-dependent spectroscopic ellipsometry

    SciTech Connect

    Xu, L. P.; Jiang, P. P.; Duan, Z. H.; Hu, Z. G. Zhu, Z. Q.; Chu, J. H.; Zhang, L. L.; Yu, J.

    2013-12-21

    Optical properties and phase transition of Bi{sub 1−x}La{sub x}Fe{sub 1−y}Ti{sub y}O{sub 3} (BLFTO) ceramics with different composition (0.02 ≤ x ≤ 0.10, 0.01 ≤ y ≤ 0.06) have been investigated by spectroscopic ellipsometry (SE) in the temperature range of −70–450 °C. The real part of the complex dielectric function ε{sub 1} increases with the temperature. Meanwhile, the imaginary part ε{sub 2} in the low-energy region decreases with the temperature and has an opposite trend in the high-energy side. Four typical interband transitions (E{sub a} ∼ 2.50 eV, E{sub b} ∼ 2.70 eV, E{sub c} ∼ 3.60 eV, and E{sub d} ∼ 4.25 eV) can be observed from the second derivative of the complex dielectric functions with aid of the standard critical point model. The critical point (CP) transition becomes broadening and shifts to a lower energy side as La and Ti compositions increase. Moreover, the CP transition energies show a red-shift trend with increasing the temperature until 320 °C, due to the lattice thermal expansion and electron-phonon interaction. The typical interband transitions and partial spectral weight present anomalies in the proximity of antiferromagnetic transition owing to the coupling between magnetic and ferroelectric order parameters and spin-lattice coupling for BLFTO multiferroic materials. It was found that the Néel temperature of BLFTO ceramics decreases from 364 to 349 °C with increasing doping composition of La and Ti elements. These phenomena can be attributed to the modification of electronic structure and magnetic order because the differences of electronegativity and ionic radii between Bi and La, Fe and Ti induce the variations on the bond angle and bond length between cations and anions. Moreover, the substitution for magnetic Fe{sup 3+} ions with nonmagnetic Ti{sup 4+} ions can reduce the exchange interaction between adjacent magnetic moments. Therefore, SE technique can be sensitive for

  6. A DSC and FTIR spectroscopic study of the effects of the epimeric coprostan-3-ols and coprostan-3-one on the thermotropic phase behaviour and organization of dipalmitoylphosphatidylcholine bilayer membranes: Comparison with their 5-cholesten analogues.

    PubMed

    Benesch, Matthew G K; Lewis, Ruthven N A H; Mannock, David A; McElhaney, Ronald N

    2015-05-01

    We present the results of a comparative differential calorimetric and Fourier transform infrared spectroscopic study of the effect of cholesterol and five analogues on the thermotropic phase behaviour and organization of dipalmitoylphosphatidylcholine bilayer membranes. These sterols/steroids differ in both the nature and stereochemistry of the polar head group at C3 (β-OH, α-OH or CO) and in the presence or absence of a double bond in ring B and in the orientation of rings A and B. The Δ(5) sterols/steroid have a trans rather than a cis ring A/B junction, and the concentration of these compounds required to abolish the DPPC pretransition, inversely related to their relative ability to disorder gel state DPPC bilayers, decreases in the order β-OH > α-OH > CO. However, in the saturated ring junction-inverted (cis) series, these concentrations are much more similar, regardless of polar head group chemical structure. Similarly, the residual enthalpy of the DPPC main phase transition at 50 mol% sterol/steroid, which is inversely related to the miscibility of these compounds in fluid DPPC bilayers, also increases in the order β-OH > α-OH > CO, but this effect is attenuated in the saturated series with an inverted ring A/B orientation. Moreover, replacement of the double bond at C5-C6 with a saturated linkage and inversion of the ring A/B junction reduces both sterol/steroid solubility and the ability to order the hydrocarbon chains of fluid DPPC molecules all cases. Thus, the characteristic effects of sterols/steroids on fluid lipid bilayers are generally optimal when an OH group rather than CO group is present at C3, and when this OH group is in the equatorial (β) orientation, and when the orientation of the ring A/B fusion is trans rather than cis. Overall, these results demonstrate that variations in the saturation and stereochemistry of the steroid ring system influence the effect of variations in the nature and stereochemistry of the polar headgroup at C3

  7. Space group and atomic structure determination of a nano-sized ordered phase derived from a f c c structure in maraging steel 12Cr-9Ni-4Mo-2Cu using transmission electron microscopy.

    PubMed

    Liu, Ping

    2003-04-01

    The unique properties of maraging steel Sandvik 1RK91 were attributed to unique precipitation: a nano-sized L phase in addition to the quasi-crystalline R' phase, which differs from any precipitation system in conventional maraging steels. The L phase was observed after ageing at either 748 or 823 K. It has flake morphology with dimensions approximately 100 x 500 x 500 A. In the present study the structure of the L phase was examined using convergent-beam electron diffraction (CBED), energy-dispersive X-ray analysis (EDX) and high-resolution electron microscopy (HREM). The L phase could be described as Ti(19)Fe(9)Mo(9)Al(8)Cr(5)Ni(50) or simply M(50)Ni(50) (M = Ti, Fe, Mo, Al and Cr). The L phase is isostructural to FeNi. Its crystal structure was determined to have the ordered structure of the uAu-I type (L1(0), P4/mmm, a = 3.52, c = 3.63 A and Z = 2) with two Ni atoms at (1/2) 0 (1/2) and 0 (1/2) (1/2), and two M atoms at 0 0 0 and (1/2) (1/2) 0. The crystal structure of the L phase can also be described using a primitive tetragonal cell and lattice parameters: a = 2.49 and c = 3.63 A, Z = 1. The Volume of the primitive tetragonal unit cell is 22.5 A(3) and the density is approximately 6.98 g cm(-3). The present study has demonstrated the possibility of determining the structure of an extremely small crystal by utilizing the information from CBED, EDX analysis and HREM.

  8. The structure of dodecagonal (Ta,V){sub 1.6}Te imaged by phase-contrast scanning transmission electron microscopy

    SciTech Connect

    Krumeich, F.; Mueller, E.; Wepf, R.A.; Conrad, M.; Reich, C.; Harbrecht, B.; Nesper, R.

    2012-10-15

    While HRTEM is the well-established method to characterize the structure of dodecagonal tantalum (vanadium) telluride quasicrystals and their periodic approximants, phase-contrast imaging performed on an aberration-corrected scanning transmission electron microscope (STEM) represents a favorable alternative. The (Ta,V){sub 151}Te{sub 74} clusters, the basic structural unit in all these phases, can be visualized with high resolution. A dependence of the image contrast on defocus and specimen thickness has been observed. In thin areas, the projected crystal potential is basically imaged with either dark or bright contrast at two defocus values close to Scherzer defocus as confirmed by image simulations utilizing the principle of reciprocity. Models for square-triangle tilings describing the arrangement of the basic clusters can be derived from such images. - Graphical abstract: PC-STEM image of a (Ta,V){sub 151}Te{sub 74} cluster. Highlights: Black-Right-Pointing-Pointer C{sub s}-corrected STEM is applied for the characterization of dodecagonal quasicrystals. Black-Right-Pointing-Pointer The projected potential of the structure is mirrored in the images. Black-Right-Pointing-Pointer Phase-contrast STEM imaging depends on defocus and thickness. Black-Right-Pointing-Pointer For simulations of phase-contrast STEM images, the reciprocity theorem is applicable.

  9. MAMA Spectroscopic Throughputs

    NASA Astrophysics Data System (ADS)

    Lennon, Daniel

    2009-07-01

    This activity sets new baseline post-SM4 sensitivity/throughput measurements for all the STIS/MAMA spectroscopic modes, and establishes if there changes with respect to perfomance prior to the LVPS failure. It also checks the NUV focus of STIS and its dependence on wavelength.

  10. Biomolecular Imaging with Coherent Nonlinear Vibrational Microscopy

    PubMed Central

    Chung, Chao-Yu; Boik, John; Potma, Eric O.

    2014-01-01

    Optical imaging with spectroscopic vibrational contrast is a label-free solution for visualizing, identifying, and quantifying a wide range of biomolecular compounds in biological materials. Both linear and nonlinear vibrational microscopy techniques derive their imaging contrast from infrared active or Raman allowed molecular transitions, which provide a rich palette for interrogating chemical and structural details of the sample. Yet nonlinear optical methods, which include both second-order sum-frequency generation (SFG) and third-order coherent Raman scattering (CRS) techniques, offer several improved imaging capabilities over their linear precursors. Nonlinear vibrational microscopy features unprecedented vibrational imaging speeds, provides strategies for higher spatial resolution, and gives access to additional molecular parameters. These advances have turned vibrational microscopy into a premier tool for chemically dissecting live cells and tissues. This review discusses the molecular contrast of SFG and CRS microscopy and highlights several of the advanced imaging capabilities that have impacted biological and biomedical research. PMID:23245525

  11. The C-S-H gel of Portland cement mortars: Part I. The interpretation of energy-dispersive X-ray microanalyses from scanning electron microscopy, with some observations on C-S-H, AFm and AFt phase compositions

    SciTech Connect

    Famy, C.; Brough, A.R.; Taylor, H.F.W

    2003-09-01

    Scanning electron microscopy (SEM) microanalyses of the calcium-silicate-hydrate (C-S-H) gel in Portland cement pastes rarely represent single phases. Essential experimental requirements are summarised and new procedures for interpreting the data are described. These include, notably, plots of Si/Ca against other atom ratios, 3D plots to allow three such ratios to be correlated and solution of linear simultaneous equations to test and quantify hypotheses regarding the phases contributing to individual microanalyses. Application of these methods to the C-S-H gel of a 1-day-old mortar identified a phase with Al/Ca=0.67 and S/Ca=0.33, which we consider to be a highly substituted ettringite of probable composition C{sub 6}A{sub 2}S-bar{sub 2}H{sub 34} or {l_brace}Ca{sub 6}[Al(OH){sub 6}]{sub 2}{center_dot}24H{sub 2}O{r_brace}(SO{sub 4}){sub 2}[Al(OH){sub 4}]{sub 2}. If this is true for Portland cements in general, it might explain observed discrepancies between observed and calculated aluminate concentrations in the pore solution. The C-S-H gel of a similar mortar aged 600 days contained unsubstituted ettringite and an AFm phase with S/Ca=0.125.

  12. Condensed-phase thermal decomposition of TATB investigated by atomic force microscopy (AFM) and simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS)

    SciTech Connect

    Land, T.A.; Siekhaus, W.J.; Foltz, M.F.; Behrens, R. Jr.

    1993-05-01

    A combination of techniques has been used to investigate the condensed-phase thermal decomposition of TATB. STMBMS has been used to identify the thermal decomposition products and their temporal correlation`s. These experiments have shown that the condensed-phase decomposition proceeds through several autocatalytic pathways. Both low and high molecular weight decomposition products have been identified. Mono-, di- and tri-furazans products have been identified and, their temporal behaviors are consistent with a stepwise loss of water. AFM has been used to correlate the decomposition chemistry with morphological changes occurring as a function of heating. Patches of small 25-140 nm round holes were observed throughout the lattice of TATB crystals that were heated briefly to 300C. It is likely that these holes show where decomposition reactions have started. Evidence of decomposition products have been seen in TATB that has been held at 250C for one hour.

  13. SLM-based microscopy

    NASA Astrophysics Data System (ADS)

    Hasler, Malte; Haist, Tobias; Osten, Wolfgang

    2012-04-01

    In microscopy it is customary to use a wide variety of imaging methods. Unfortunately, for most of these it is necessary to physically change the setup (filters, special objectives, etc.). We present a programmable microscope in which an integrated spatial light modulator (SLM) is incorporated in order to realize a number of otherwise physically intricate modifications. We employ a HDTV LCOS SLM (Holoeye Pluto, 1920x1080 pixel, 8 μm pixel pitch), 2 different LED illuminations in reflection and transmission, an Olympus UmPlanFl 50x objective with a NA of 0.8 and a CCD camera (SVS-Vistek eco204 1/3") with 1024x768 resolution. By the use of computer generated holograms (CGHs) we are able to recreate a number of classical phase contrast imaging techniques such as Zernike phase contrast or DIC, and modify them in unconventional ways. Additionally, the SLM enables us to compensate various kinds of aberrations. Other imaging methods like stereovision for three dimensional object reconstruction on a microscopic scale, structured illumination or confocal microscopy are also possible if the setup is extended to a state in which not only the imaging light but also the illumination light is propagated over an SLM with a CGH.

  14. Structural phase transitions in Au thin films on Si (1 1 0): An in situ temperature dependent transmission electron microscopy study

    NASA Astrophysics Data System (ADS)

    Bhatta, Umananda M.; Dash, J. K.; Rath, A.; Satyam, P. V.

    2009-10-01

    We present a review on the formation of gold silicide nanostructures using in situ temperature dependent transmission electron microscopy (TEM) measurements. Thin Au films of two thicknesses (2.0 nm and 5.0 nm) were deposited on Si (1 1 0) substrate under ultra-high vacuum (UHV) conditions in a molecular beam epitaxy (MBE) system. Also a 2.0 nm thick Au film was deposited under high vacuum condition (with the native oxide at the interface of Au and Si) using thermal evaporation. In situ TEM measurements (for planar samples) were made at various temperatures (from room temperature, RT to 950 °C). We show that, in the presence of native oxide (UHV-MBE) at the interface, high aspect ratio (≈15.0) aligned gold silicide nanorods were observed. For the films that were grown with UHV conditions, a small aspect ratio (˜1.38) nanogold silicide was observed. For 5.0 nm thick gold thin film, thicker and lesser aspect ratio silicides were observed. Selected area diffraction pattern taken at RT after the sample for the case of 5.0 nm Au on Si (1 1 0)-MBE was annealed at 475 °C show the signature of gold silicide formation.

  15. On Ultrafast Time-Domain TeraHertz Spectroscopy in the Condensed Phase: Linear Spectroscopic Measurements of Hydrogen-Bond Dynamics of Astrochemical Ice Analogs and Nonlinear TeraHertz Kerr Effect Measurements of Vibrational Quantum Beats

    NASA Astrophysics Data System (ADS)

    Allodi, Marco A.

    Much of the chemistry that affects life on planet Earth occurs in the condensed phase. The TeraHertz (THz) or far-infrared (far-IR) region of the electromagnetic spectrum (from 0.1 THz to 10 THz) has been shown to provide unique possibilities in the study of condensed-phase processes. The goal of this work is to expand the possibilities available in the THz region and undertake new investigations of fundamental interest to chemistry. Since we are fundamentally interested in condensed-phase processes, this thesis focuses on two areas where THz spectroscopy can provide new understanding: astrochemistry and solvation science. To advance these fields, we had to develop new instrumentation that would enable the experiments necessary to answer new questions in either astrochemistry or solvation science. We first developed a new experimental setup capable of studying astrochemical ice analogs in both the TeraHertz (THz), or far-Infrared (far-IR), region (0.3 - 7.5 THz; 10 - 250 wavenumbers) and the mid-IR (400 - 4000 wavenumbers). The importance of astrochemical ices lies in their key role in the formation of complex organic molecules, such as amino acids and sugars in space. Thus, the instruments are capable of performing variety of spectroscopic studies that can provide especially relevant laboratory data to support astronomical observations from telescopes such as the Herschel Space Telescope, the Stratospheric Observatory for Infrared Astronomy (SOFIA), and the Atacama Large Millimeter Array (ALMA). The experimental apparatus uses a THz time-domain spectrometer, with a 1750/875 nm plasma source and a GaP detector crystal, to cover the bandwidth mentioned above with 10 GHz (0.3 wavenumber) resolution. Using the above instrumentation, experimental spectra of astrochemical ice analogs of water and carbon dioxide in pure, mixed, and layered ices were collected at different temperatures under high-vacuum conditions with the goal of investigating the structure of the ice

  16. Spectroscopic Low Coherence Interferometry

    NASA Astrophysics Data System (ADS)

    Bosschaart, Nienke; van Leeuwen, T. G.; Aalders, Maurice C.; Hermann, Boris; Drexler, Wolfgang; Faber, Dirk J.

    Low-coherence interferometry (LCI) allows high-resolution volumetric imaging of tissue morphology and provides localized optical properties that can be related to the physiological status of tissue. This chapter discusses the combination of spatial and spectroscopic information by means of spectroscopic OCT (sOCT) and low-coherence spectroscopy (LCS). We describe the theory behind these modalities for the assessment of spatially resolved optical absorption and (back)scattering coefficient spectra. These spectra can be used for the highly localized quantification of chromophore concentrations and assessment of tissue organization on (sub)cellular scales. This leads to a wealth of potential clinical applications, ranging from neonatology for the determination of billibrubin concentrations, to oncology for the optical assessment of the aggressiveness of a cancerous lesion.

  17. Spectroscopic Binary Stars

    NASA Astrophysics Data System (ADS)

    Batten, A.; Murdin, P.

    2000-11-01

    Historically, spectroscopic binary stars were binary systems whose nature was discovered by the changing DOPPLER EFFECT or shift of the spectral lines of one or both of the component stars. The observed Doppler shift is a combination of that produced by the constant RADIAL VELOCITY (i.e. line-of-sight velocity) of the center of mass of the whole system, and the variable shift resulting from the o...

  18. SEM, EDX, Infrared and Raman spectroscopic characterization of the silicate mineral yuksporite

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; López, Andrés; Scholz, Ricardo; Theiss, Frederick L.; Romano, Antônio Wilson

    2015-02-01

    The mineral yuksporite (K,Ba)NaCa2(Si,Ti)4O11(F,OH)ṡH2O has been studied using the combination of SEM with EDX and vibrational spectroscopic techniques of Raman and infrared spectroscopy. Scanning electron microscopy shows a single pure phase with cleavage fragment up to 1.0 mm. Chemical analysis gave Si, Al, K, Na and Ti as the as major elements with small amounts of Mn, Ca, Fe and REE. Raman bands are observed at 808, 871, 930, 954, 980 and 1087 cm-1 and are typical bands for a natural zeolite. Intense Raman bands are observed at 514, 643 and 668 cm-1. A very sharp band is observed at 3668 cm-1 and is attributed to the OH stretching vibration of OH units associated with Si and Ti. Raman bands resolved at 3298, 3460, 3562 and 3628 cm-1 are assigned to water stretching vibrations.

  19. Spectroscopically Unlocking Exoplanet Characteristics

    NASA Astrophysics Data System (ADS)

    Lewis, Nikole

    2016-05-01

    Spectroscopy plays a critical role in a number of areas of exoplanet research. The first exoplanets were detected by precisely measuring Doppler shifts in high resolution (R ~ 100,000) stellar spectra, a technique that has become known as the Radial Velocity (RV) method. The RV method provides critical constraints on exoplanet masses, but is currently limited to some degree by robust line shape predictions. Beyond the RV method, spectroscopy plays a critical role in the characterization of exoplanets beyond their mass and radius. The Hubble Space Telescope has spectroscopically observed the atmospheres of exoplanets that transit their host stars as seen from Earth giving us key insights into atmospheric abundances of key atomic and molecular species as well as cloud optical properties. Similar spectroscopic characterization of exoplanet atmospheres will be carried out at higher resolution (R ~ 100-3000) and with broader wavelength coverage with the James Webb Space Telescope. Future missions such as WFIRST that seek to the pave the way toward the detection and characterization of potentially habitable planets will have the capability of directly measuring the spectra of exoplanet atmospheres and potentially surfaces. Our ability to plan for and interpret spectra from exoplanets relies heavily on the fidelity of the spectroscopic databases available and would greatly benefit from further laboratory and theoretical work aimed at optical properties of atomic, molecular, and cloud/haze species in the pressure and temperature regimes relevant to exoplanet atmospheres.

  20. Unexpected bismuth concentration profiles in metal-organic vapor phase epitaxy-grown Ga(As{sub 1−x}Bi{sub x})/GaAs superlattices revealed by Z-contrast scanning transmission electron microscopy imaging

    SciTech Connect

    Wood, A. W.; Babcock, S. E.; Guan, Y.; Forghani, K.; Anand, A.; Kuech, T. F.

    2015-03-01

    A set of GaAs{sub 1−x}Bi{sub x}/GaAs multilayer quantum-well structures was deposited by metal-organic vapor phase epitaxy at 390 °C and 420 °C. The precursor fluxes were introduced with the intent of growing discrete and compositionally uniform GaAs{sub 1−x}Bi{sub x} well and GaAs barrier layers in the epitaxial films. High-resolution high-angle annular-dark-field (or “Z-contrast”) scanning transmission electron microscopy imaging revealed concentration profiles that were periodic in the growth direction, but far more complicated in shape than the intended square wave. The observed composition profiles could explain various reports of physical properties measurements that suggest compositional inhomogeneity in GaAs{sub 1−x}Bi{sub x} alloys as they currently are grown.

  1. Intergrowth structure of α-phase in β-type TmAlB4 compound studied by high-angle annular detector dark-field scanning transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Yubuta, Kunio; Mori, Takao; Leithe-Jasper, Andreas; Borrmann, Horst; Grin, Yuri; Okada, Shigeru; Shishido, Toetsu

    2014-11-01

    Nanostructure of a ThMoB4-type (β-type) TmAlB4 compound, in which YCrB4-type (α-type) domains are locally intergrown, is studied by high-angle annular detector dark-field scanning transmission electron microscopy (HAADF-STEM). Z-contrast images by HAADF-STEM directly represent the arrangements of Tm atoms located at centers of heptagonal atomic columns of B atoms as bright dots, and give us detailed information of intergrowth of type domains in the matrix of the β-type phase, which coherently occurs. Structural and bonding analyses for β-TmAlB4 point out the closeness in atomic interactions and energy of the α- and β-type structures which support the easy formation of such nanostructure intergrowths. From combination between HAADF-STEM and electronic structure calculation, a detailed local crystal structure with intrinsic building defects is effectively revealed.

  2. Microscopic and spectroscopic investigation of an explanted opacified intraocular lens

    NASA Astrophysics Data System (ADS)

    Simon, V.; Radu, T.; Vulpoi, A.; Rosca, C.; Eniu, D.

    2015-01-01

    The investigated polymethylmethacrylate intraocular lens explanted an year after implantation presented a fine granularity consisting of ring-like grains of about 15 μm in diameter. In order to evidence the changes occurred on intraocular lens relative to morphology, elemental composition and atomic environments, microscopic and spectroscopic analyses were carried out using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), energy-dispersive X-ray (EDS), and X-ray photoelectron (XPS) spectroscopies. The results revealed that the grains contain hydroxyapatite mineral phase. A protein layer covers the lens both in opacified and transparent zones. The amide II band is like in basal epithelial cells. The shape and size of the grains, and the XPS depth profiling results indicate the possibility of a cell-mediated process involving lens epithelial cells which fagocitated apoptotic epithelial cells, and in which the debris derived from cell necrosis were calcified. To the best of our knowledge, this is the first investigation on explanted intraocular lenses using XPS depth profiling in order to examine the inside of the opacifying deposits.

  3. Intergrowth structure of α-phase in β-type TmAlB{sub 4} compound studied by high-angle annular detector dark-field scanning transmission electron microscopy

    SciTech Connect

    Yubuta, Kunio; Mori, Takao; Leithe-Jasper, Andreas; Borrmann, Horst; Grin, Yuri; Okada, Shigeru; Shishido, Toetsu

    2014-11-15

    Nanostructure of a ThMoB{sub 4}-type (β-type) TmAlB{sub 4} compound, in which YCrB{sub 4}-type (α-type) domains are locally intergrown, is studied by high-angle annular detector dark-field scanning transmission electron microscopy (HAADF-STEM). Z-contrast images by HAADF-STEM directly represent the arrangements of Tm atoms located at centers of heptagonal atomic columns of B atoms as bright dots, and give us detailed information of intergrowth of type domains in the matrix of the β-type phase, which coherently occurs. Structural and bonding analyses for β-TmAlB{sub 4} point out the closeness in atomic interactions and energy of the α- and β-type structures which support the easy formation of such nanostructure intergrowths. From combination between HAADF-STEM and electronic structure calculation, a detailed local crystal structure with intrinsic building defects is effectively revealed. - Graphical abstract: Nanostructure of a ThMoB{sub 4}-type (β-type) TmAlB{sub 4} compound, in which YCrB{sub 4}-type (α-type) domains are locally intergrown, is studied by high-angle annular detector dark-field scanning transmission electron microscopy (HAADF-STEM). Z-contrast images by HAADF-STEM directly represent arrangements of Tm atoms located at centers of heptagonal atomic columns of B atoms as bright dots, and give us detailed information of the characteristic intergrowth structure of type domains in the matrix of the β-type phase. - Highlights: • HAADF-STEM images directly represent arrangements of Tm atoms as bright dots. • The α-type planar domains coherently intergrown in the β-type matrix. • Bright strips appear at overlapped regions of Tm hexagons along interfaces between α- and β-type domains.

  4. Coherent Nonlinear Optical Imaging: Beyond Fluorescence Microscopy

    PubMed Central

    Min, Wei; Freudiger, Christian W.; Lu, Sijia; Xie, X. Sunney

    2012-01-01

    The quest for ultrahigh detection sensitivity with spectroscopic contrasts other than fluorescence has led to various novel approaches to optical microscopy of biological systems. Coherent nonlinear optical imaging, especially the recently developed nonlinear dissipation microscopy, including stimulated Raman scattering and two photon absorption, and pump-probe microscopy, including stimulated emission, excited state absorption and ground state depletion, provide distinct and powerful image contrasts for non-fluorescent species. Thanks to high-frequency modulation transfer scheme, they exhibit superb detection sensitivity. By directly interrogating vibrational and/or electronic energy levels of molecules, they offer high molecular specificity. Here we review the underlying principles, excitation and detection schemes, as well as exemplary biomedical applications of this emerging class of molecular imaging techniques. PMID:21453061

  5. The HITRAN 2008 Molecular Spectroscopic Database

    NASA Technical Reports Server (NTRS)

    Rothman, Laurence S.; Gordon, Iouli E.; Barbe, Alain; Benner, D. Chris; Bernath, Peter F.; Birk, Manfred; Boudon, V.; Brown, Linda R.; Campargue, Alain; Champion, J.-P.; Chance, Kelly V.; Coudert, L. H.; Sung, K.; Toth, R. A.

    2009-01-01

    This paper describes the status of the 2008 edition of the HITRAN molecular spectroscopic database. The new edition is the first official public release since the 2004 edition, although a number of crucial updates had been made available online since 2004. The HITRAN compilation consists of several components that serve as input for radiative-transfer calculation codes: individual line parameters for the microwave through visible spectra of molecules in the gas phase; absorption cross-sections for molecules having dense spectral features, i.e., spectra in which the individual lines are not resolved; individual line parameters and absorption cross sections for bands in the ultra-violet; refractive indices of aerosols, tables and files of general properties associated with the database; and database management software. The line-by-line portion of the database contains spectroscopic parameters for forty-two molecules including many of their isotopologues.

  6. Spectroscopic survey of LAMOST

    NASA Astrophysics Data System (ADS)

    Zhao, Yongheng

    2014-07-01

    LAMOST is a special reflecting Schmidt telescope. LAMOST breaks through the bottleneck of the large scale spectroscopic survey observation with both large aperture (effective aperture of 3.6 - 4.9m) and wide field of view (5 degrees). It is an innovative active reflecting Schmidt configuration achieved by changing mirror surface continuously to achieve a series different reflecting Schmidt system in different moments. By using the parallel controllable fiber positioning technique, the focal surface of 1.75 meters in diameter accommodates 4000 optical fibers. Also, LAMOST has 16 spectrographs with 32 CCD cameras. LAMOST is the telescope of the highest spectrum acquiring rate. As a national large scientific project, LAMOST project was proposed formally in 1996. The construction was started in 2001 and completed in 2008. After commission period, LAMOST pilot survey was started in October 2011 and spectroscopic survey began in September 2012. From October 2011 to June 2013, LAMOST has obtained more than 2 million spectra of celestial objects. There are 1.7 million spectra of stars, in which the stellar parameters (effective temperature, surface gravity, metalicitiy and radial velocity) of more than 1 million stars was obtained. In the first period of spectroscopic survey of LAMOST, 5 million of stellar spectra will be obtained and will make substantial contribution to the study of the stellar astrophysics and the structure of the Galaxy, such as the spheroid substructure of the Galaxy, the galactic gravitational potential and the distribution of the dark matter in the Galaxy, the extremely metal poor stars and hypervelocity stars, the 3D extinction in the Galaxy, the structure of thin and thick disks of the Galaxy, and so on.

  7. Imaging theory of structured pump-probe microscopy.

    PubMed

    Massaro, Eric S; Hill, Andrew H; Kennedy, Casey L; Grumstrup, Erik M

    2016-09-01

    With sub-micron spatial resolution and femtosecond temporal resolution, pump probe microscopy provides a powerful spectroscopic probe of complex electronic environments in bulk and nanoscale materials. However, the electronic structure of many materials systems are governed by compositional and morphological heterogeneities on length scales that lie below the diffraction limit. We have recently demonstrated Structured Pump Probe Microscopy (SPPM), which employs a patterned pump excitation field to provide spectroscopic interrogation of sub-diffraction limited sample volumes. Herein, we develop the imaging theory of SPPM in two dimensions to accompany the previously published experimental methodology. We show that regardless of pump and probe wavelengths, a nearly two-fold reduction in spectroscopic probe volume can be achieved. We also examine the limitations of the approach, with a detailed discussion of ringing in the point spread function that can reduce imaging performance. PMID:27607691

  8. Spectroscopic survey of LAMOST

    NASA Astrophysics Data System (ADS)

    Zhao, Yongheng

    2015-08-01

    LAMOST is a special reflecting Schmidt telescope. LAMOST breaks through the bottleneck of the large scale spectroscopic survey observation with both large aperture (effective aperture of 3.6 - 4.9m) and wide field of view (5 degrees). It is an innovative active reflecting Schmidt configuration achieved by changing mirror surface continuously to achieve a series different reflecting Schmidt system in different moments. By using the parallel controllable fiber positioning technique, the focal surface of 1.75 meters in diameter accommodates 4000 optical fibers. Also, LAMOST has 16 spectrographs with 32 CCD cameras. LAMOST is the telescope of the highest spectrum acquiring rate.In the spectroscopic survey of LAMOST from October 2011 to June 2014, LAMOST has obtained more than 4.13 million spectra of celestial objects. There are 3.27 million spectra of stars, in which the stellar parameters of 2.16 million stars were obtained.In the five-year regular survey upto 2017, LAMOST will obtaine 5 million stellar spectra, which would make substantial contribution to the study of the stellar astrophysics and the structure of the Galaxy, such as the spheroid substructure of the Galaxy, the galactic gravitational potential and the distribution of the dark matter in the Galaxy, the extremely metal poor stars and hypervelocity stars, the 3D extinction in the Galaxy, the structure of thin and thick disks of the Galaxy, and so on.

  9. Hyperspectral holographic Fourier-microscopy

    NASA Astrophysics Data System (ADS)

    Kalenkov, G. S.; Kalenkov, S. G.; Shtan'ko, A. E.

    2015-04-01

    A detailed theory of the method of holographic recording of hyperspectral wave fields is developed. New experimentally obtained hyperspectral holographic images of microscopic objects are presented. The possibilities of the method are demonstrated experimentally using the examples of urgent microscopy problems: speckle noise suppression, obtaining hyperspectral image of a microscopic object, as well as synthesis of a colour image and obtaining an optical profile of a phase object.

  10. Dictionary of Microscopy

    NASA Astrophysics Data System (ADS)

    Heath, Julian

    2005-10-01

    The past decade has seen huge advances in the application of microscopy in all areas of science. This welcome development in microscopy has been paralleled by an expansion of the vocabulary of technical terms used in microscopy: terms have been coined for new instruments and techniques and, as microscopes reach even higher resolution, the use of terms that relate to the optical and physical principles underpinning microscopy is now commonplace. The Dictionary of Microscopy was compiled to meet this challenge and provides concise definitions of over 2,500 terms used in the fields of light microscopy, electron microscopy, scanning probe microscopy, x-ray microscopy and related techniques. Written by Dr Julian P. Heath, Editor of Microscopy and Analysis, the dictionary is intended to provide easy navigation through the microscopy terminology and to be a first point of reference for definitions of new and established terms. The Dictionary of Microscopy is an essential, accessible resource for: students who are new to the field and are learning about microscopes equipment purchasers who want an explanation of the terms used in manufacturers' literature scientists who are considering using a new microscopical technique experienced microscopists as an aide mémoire or quick source of reference librarians, the press and marketing personnel who require definitions for technical reports.

  11. Electron diffraction and high-resolution transmission electron microscopy of the high temperature crystal structures of GexSb2Te3+x (x=1,2,3) phase change material

    NASA Astrophysics Data System (ADS)

    Kooi, B. J.; De Hosson, J. Th. M.

    2002-10-01

    The crystal structures of GeSb2Te4, Ge2Sb2Te5, and Ge3Sb2Te6 were determined using electron diffraction and high-resolution transmission electron microscopy. The structure determined for the former two crystals deviates from the ones proposed in the literature. These crystal structures were developed jointly upon cooling of liquid Ge2Sb2Te5. A stacking disorder parallel to the basal plane was observed that increases with increasing cooling rates. For the GexSb2Te3+x (x=1,2,3) crystals it is shown that an a,b,c stacking holds with an alternating stacking of x GeTe double layers identically present in binary GeTe and one Te-Sb-Te-Te-Sb- repeat unit also present in binary Sb2Te3. A stacking disorder is a logical consequence of building crystals with these two principal units. On the other hand, it is likely that all stable crystals of the Ge-Sb-Te systems are an ordered sequence of these two units. Some of the implications of these findings of the stable and metastable crystal structures that develop from amorphous Ge2Sb2Te5 are presented so as to understand the crucial crystallization process in Ge2Sb2Te5 phase change material.

  12. High-Definition Infrared Spectroscopic Imaging

    PubMed Central

    Reddy, Rohith K.; Walsh, Michael J.; Schulmerich, Matthew V.; Carney, P. Scott; Bhargava, Rohit

    2013-01-01

    The quality of images from an infrared (IR) microscope has traditionally been limited by considerations of throughput and signal-to-noise ratio (SNR). An understanding of the achievable quality as a function of instrument parameters, from first principals is needed for improved instrument design. Here, we first present a model for light propagation through an IR spectroscopic imaging system based on scalar wave theory. The model analytically describes the propagation of light along the entire beam path from the source to the detector. The effect of various optical elements and the sample in the microscope is understood in terms of the accessible spatial frequencies by using a Fourier optics approach and simulations are conducted to gain insights into spectroscopic image formation. The optimal pixel size at the sample plane is calculated and shown much smaller than that in current mid-IR microscopy systems. A commercial imaging system is modified, and experimental data are presented to demonstrate the validity of the developed model. Building on this validated theoretical foundation, an optimal sampling configuration is set up. Acquired data were of high spatial quality but, as expected, of poorer SNR. Signal processing approaches were implemented to improve the spectral SNR. The resulting data demonstrated the ability to perform high-definition IR imaging in the laboratory by using minimally-modified commercial instruments. PMID:23317676

  13. Ultraminiature one-shot Fourier-spectroscopic tomography

    NASA Astrophysics Data System (ADS)

    Sato, Shun; Qi, Wei; Kawashima, Natsumi; Nogo, Kosuke; Hosono, Satsuki; Nishiyama, Akira; Wada, Kenji; Ishimaru, Ichiro

    2016-02-01

    We propose one-shot Fourier-spectroscopic tomography as a method of ultraminiature spectroscopic imaging. The apparatus used in this technique consists solely of a glass slab with a portion of its surface polished at a certain inclination angle-a device we term a relative-inclination phase shifter-simply mounted on an infinite-distance-corrected optical imaging system. For this reason, the system may be ultraminiaturized to sizes on the order of a few tens of millimeters. Moreover, because our technique uses a near-common-path wavefront-division phase-shift interferometer and has absolutely no need for a mechanical drive unit, it is highly robust against mechanical vibrations. In addition, because the proposed technique uses Fourier-transform spectroscopy, it offers highly efficient light utilization and an outstanding signal-to-noise ratio compared to devices that incorporate distributed or hyperspectral acousto-optical tunable filters. The interferogram, which is a pattern formed by interference of waves at all wavelengths, reflects the spatial variation in the intensity of the interference depending on the magnitude of the phase shift. We first discuss the design of the phase shifter and the results of tests to validate the principles underlying one-shot Fourier-spectroscopic tomography. We then report the results of one-dimensional spectroscopic imaging using this technique.

  14. Spectroscopic studies of the several isomers of UO3

    NASA Astrophysics Data System (ADS)

    Sweet, Lucas E.; Reilly, Dallas D.; Abrecht, David G.; Buck, Edgar C.; Meier, David E.; Su, Yin-Fong; Brauer, Carolyn S.; Schwantes, Jon M.; Tonkyn, Russell G.; Szecsody, James E.; Blake, Thomas A.; Johnson, Timothy J.

    2013-10-01

    Uranium trioxide is known to adopt seven different structural forms. While these structural forms have been well characterized using x-ray or neutron diffraction techniques, little work has been done to characterize their spectroscopic properties, particularly of the pure phases. Since the structural isomers of UO3 all have similar thermodynamic stabilities and most tend to hydrolyze under open atmospheric conditions, mixtures of UO3 phases and the hydrolysis products are common. Much effort went into isolating pure phases of UO3. Utilizing x-ray diffraction as a sample identification check, UV/Vis/NIR spectroscopic signatures of α-UO3, β-UO3, γ-UO3 and α-UO2(OH)2 products were obtained. The spectra of the pure phases can now be used to characterize typical samples of UO3, which are often mixtures of isomers.

  15. Spectroscopic Studies of the Several Isomers of UO3

    SciTech Connect

    Sweet, Lucas E.; Reilly, Dallas D.; Abrecht, David G.; Buck, Edgar C.; Meier, David E.; Su, Yin-Fong; Brauer, Carolyn S.; Schwantes, Jon M.; Tonkyn, Russell G.; Szecsody, James E.; Blake, Thomas A.; Johnson, Timothy J.

    2013-09-26

    Uranium trioxide is known to adopt seven different structural forms. While these structural forms have been well characterized using x-ray or neutron diffraction techniques, little work has been done to characterize their spectroscopic properties, particularly of the pure phases. Since the structural isomers of UO3 all have similar thermodynamic stabilities and most tend to hydrolyze under open atmospheric conditions, mixtures of UO3 phases and the hydrolysis products are common. Much effort went into isolating pure phases of UO3. Utilizing x-ray diffraction as a sample identification check, UV/Vis/NIR spectroscopic signatures of α-UO3, β-UO3, γ-UO3 and UO2(OH)2 products were obtained. The spectra of the pure phases can now be used to characterize typical samples of UO3, which are often mixtures of isomers.

  16. Infrared and fluorescence spectroscopic studies of a phospholipid bilayer supported by a soft cationic hydrogel scaffold.

    PubMed

    Grossutti, Michael; Seenath, Ryan; Noël, John A; Lipkowski, Jacek

    2016-07-01

    Polarized attenuated total reflection (ATR-IR) spectroscopy and fluorescence microscopy techniques were used to characterize a 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) membrane supported on porous, cationic hydrogel beads. Fluorescence microscopy images showed that the DPhPC coated the external surface of the hydrogel scaffold. In addition, a fluorescence assay of the emission intensity of the Tb(3+)/dipicolinic acid complex demonstrated that the DPhPC coating acted as a barrier to Tb(3+) efflux from the scaffolded vesicle and successfully sealed the porous hydrogel bead. Fluorescence quenching and ATR-IR spectroscopic measurements revealed that the lipid coating has a bilayer structure. The phytanoyl chains were found to exhibit significant trans-gauche isomerization, characteristic of the fluid liquid phase. However, no lipid lateral mobility was observed by fluorescence recovery after photobleaching (FRAP) measurements. The phosphocholine headgroup was found to be well hydrated and oriented such that the cationic choline group tucked in behind the anionic phosphate group, consistent with an electrostatic attraction between the cationic scaffold and zwitterionic lipid. The absence of lipid lateral mobility may be due to the strength of this attraction.

  17. Spectroscopic Detection of Pathogens

    SciTech Connect

    ALAM,M. KATHLEEN; TIMLIN,JERILYN A.; MARTIN,LAURA E.; HJELLE,DRIAN; LYONS,RICK; GARRISON,KRISTIN

    2000-11-01

    The goal of this LDRD Research project was to provide a preliminary examination of the use of infrared spectroscopy as a tool to detect the changes in cell cultures upon activation by an infectious agent. Due to a late arrival of funding, only 5 months were available to transfer and setup equipment at UTTM,develop cell culture lines, test methods of in-situ activation and collect kinetic data from activated cells. Using attenuated total reflectance (ATR) as a sampling method, live cell cultures were examined prior to and after activation. Spectroscopic data were collected from cells immediately after activation in situ and, in many cases for five successive hours. Additional data were collected from cells activated within a test tube (pre-activated), in both transmission mode as well as in ATR mode. Changes in the infrared data were apparent in the transmission data collected from the pre-activated cells as well in some of the pre-activated ATR data. Changes in the in-situ activated spectral data were only occasionally present due to (1) the limited time cells were studied and (2) incomplete activation. Comparison of preliminary data to infrared bands reported in the literature suggests the primary changes seen are due an increase in ribonucleic acid (RNA) production. This work will be continued as part of a 3 year DARPA grant.

  18. Spectroscopic classification of supernova candidates

    NASA Astrophysics Data System (ADS)

    Hodgkin, S. T.; Hall, A.; Fraser, M.; Campbell, H.; Wyrzykowski, L.; Kostrzewa-Rutkowska, Z.; Pietro, N.

    2014-09-01

    We report the spectroscopic classification of four supernovae at the 2.5m Isaac Newton Telescope on La Palma, using the Intermediate Dispersion Spectrograph and the R300V grating (3500-8000 Ang; ~6 Ang resolution).

  19. Magnetic and Mössbauer spectroscopic studies of NiZn ferrite nanoparticles synthesized by a combustion method

    NASA Astrophysics Data System (ADS)

    Sreeja, V.; Vijayanand, S.; Deka, S.; Joy, P. A.

    2008-04-01

    The properties of nanocrystalline Ni0.5Zn0.5Fe2O4 synthesized by an auto-combustion method have been investigated by magnetic measurements and Mössbauer spectroscopy. The as-synthesized single phase nanosized ferrite powder is annealed at different temperatures in the range 673 1,273 K to obtain nanoparticles of different sizes. The powders are characterized by powder X-ray diffraction, vibrating sample magnetometer, transmission electron microscopy and Mössbauer spectroscopy. The as-synthesized powder with average particle size of ~9 nm is superparamagnetic. Magnetic transition temperature increases up to 665 K for the nanosized powder as compared to the transition temperature of 548 K for the bulk ferrite. This has been confirmed as due to the abnormal cation distribution, as evidenced from room temperature Mössbauer spectroscopic studies.

  20. Axial Plane Optical Microscopy

    PubMed Central

    Li, Tongcang; Ota, Sadao; Kim, Jeongmin; Wong, Zi Jing; Wang, Yuan; Yin, Xiaobo; Zhang, Xiang

    2014-01-01

    We present axial plane optical microscopy (APOM) that can, in contrast to conventional microscopy, directly image a sample's cross-section parallel to the optical axis of an objective lens without scanning. APOM combined with conventional microscopy simultaneously provides two orthogonal images of a 3D sample. More importantly, APOM uses only a single lens near the sample to achieve selective-plane illumination microscopy, as we demonstrated by three-dimensional (3D) imaging of fluorescent pollens and brain slices. This technique allows fast, high-contrast, and convenient 3D imaging of structures that are hundreds of microns beneath the surfaces of large biological tissues. PMID:25434770

  1. Light sheet microscopy.

    PubMed

    Weber, Michael; Mickoleit, Michaela; Huisken, Jan

    2014-01-01

    This chapter introduces the concept of light sheet microscopy along with practical advice on how to design and build such an instrument. Selective plane illumination microscopy is presented as an alternative to confocal microscopy due to several superior features such as high-speed full-frame acquisition, minimal phototoxicity, and multiview sample rotation. Based on our experience over the last 10 years, we summarize the key concepts in light sheet microscopy, typical implementations, and successful applications. In particular, sample mounting for long time-lapse imaging and the resulting challenges in data processing are discussed in detail.

  2. [Artefacts of confocal microscopy].

    PubMed

    Vekshin, N L; Frolov, M S

    2014-01-01

    Typical artefacts caused by using confocal fluorescent microscopy while studying living cells are considered. The role of light scattering, mobility, staining, local concentrations, etc. is discussed.

  3. Axial Plane Optical Microscopy

    NASA Astrophysics Data System (ADS)

    Li, Tongcang; Ota, Sadao; Kim, Jeongmin; Wong, Zi Jing; Wang, Yuan; Yin, Xiaobo; Zhang, Xiang

    2014-12-01

    We present axial plane optical microscopy (APOM) that can, in contrast to conventional microscopy, directly image a sample's cross-section parallel to the optical axis of an objective lens without scanning. APOM combined with conventional microscopy simultaneously provides two orthogonal images of a 3D sample. More importantly, APOM uses only a single lens near the sample to achieve selective-plane illumination microscopy, as we demonstrated by three-dimensional (3D) imaging of fluorescent pollens and brain slices. This technique allows fast, high-contrast, and convenient 3D imaging of structures that are hundreds of microns beneath the surfaces of large biological tissues.

  4. Dynamic imaging with electron microscopy

    ScienceCinema

    Campbell, Geoffrey; McKeown, Joe; Santala, Melissa

    2016-07-12

    Livermore researchers have perfected an electron microscope to study fast-evolving material processes and chemical reactions. By applying engineering, microscopy, and laser expertise to the decades-old technology of electron microscopy, the dynamic transmission electron microscope (DTEM) team has developed a technique that can capture images of phenomena that are both very small and very fast. DTEM uses a precisely timed laser pulse to achieve a short but intense electron beam for imaging. When synchronized with a dynamic event in the microscope's field of view, DTEM allows scientists to record and measure material changes in action. A new movie-mode capability, which earned a 2013 R&D 100 Award from R&D Magazine, uses up to nine laser pulses to sequentially capture fast, irreversible, even one-of-a-kind material changes at the nanometer scale. DTEM projects are advancing basic and applied materials research, including such areas as nanostructure growth, phase transformations, and chemical reactions.

  5. Dynamic imaging with electron microscopy

    SciTech Connect

    Campbell, Geoffrey; McKeown, Joe; Santala, Melissa

    2014-02-20

    Livermore researchers have perfected an electron microscope to study fast-evolving material processes and chemical reactions. By applying engineering, microscopy, and laser expertise to the decades-old technology of electron microscopy, the dynamic transmission electron microscope (DTEM) team has developed a technique that can capture images of phenomena that are both very small and very fast. DTEM uses a precisely timed laser pulse to achieve a short but intense electron beam for imaging. When synchronized with a dynamic event in the microscope's field of view, DTEM allows scientists to record and measure material changes in action. A new movie-mode capability, which earned a 2013 R&D 100 Award from R&D Magazine, uses up to nine laser pulses to sequentially capture fast, irreversible, even one-of-a-kind material changes at the nanometer scale. DTEM projects are advancing basic and applied materials research, including such areas as nanostructure growth, phase transformations, and chemical reactions.

  6. Limits to magnetic resonance microscopy

    NASA Astrophysics Data System (ADS)

    Glover, Paul; Mansfield, Peter, Sir

    2002-10-01

    The last quarter of the twentieth century saw the development of magnetic resonance imaging (MRI) grow from a laboratory demonstration to a multi-billion dollar worldwide industry. There is a clinical body scanner in almost every hospital of the developed nations. The field of magnetic resonance microscopy (MRM), after mostly being abandoned by researchers in the first decade of MRI, has become an established branch of the science. This paper reviews the development of MRM over the last decade with an emphasis on the current state of the art. The fundamental principles of imaging and signal detection are examined to determine the physical principles which limit the available resolution. The limits are discussed with reference to liquid, solid and gas phase microscopy. In each area, the novel approaches employed by researchers to push back the limits of resolution are discussed. Although the limits to resolution are well known, the developments and applications of MRM have not reached their limit.

  7. Electron microscopy of electromagnetic waveforms.

    PubMed

    Ryabov, A; Baum, P

    2016-07-22

    Rapidly changing electromagnetic fields are the basis of almost any photonic or electronic device operation. We report how electron microscopy can measure collective carrier motion and fields with subcycle and subwavelength resolution. A collimated beam of femtosecond electron pulses passes through a metamaterial resonator that is previously excited with a single-cycle electromagnetic pulse. If the probing electrons are shorter in duration than half a field cycle, then time-frozen Lorentz forces distort the images quasi-classically and with subcycle time resolution. A pump-probe sequence reveals in a movie the sample's oscillating electromagnetic field vectors with time, phase, amplitude, and polarization information. This waveform electron microscopy can be used to visualize electrodynamic phenomena in devices as small and fast as available. PMID:27463670

  8. Electron microscopy of electromagnetic waveforms

    NASA Astrophysics Data System (ADS)

    Ryabov, A.; Baum, P.

    2016-07-01

    Rapidly changing electromagnetic fields are the basis of almost any photonic or electronic device operation. We report how electron microscopy can measure collective carrier motion and fields with subcycle and subwavelength resolution. A collimated beam of femtosecond electron pulses passes through a metamaterial resonator that is previously excited with a single-cycle electromagnetic pulse. If the probing electrons are shorter in duration than half a field cycle, then time-frozen Lorentz forces distort the images quasi-classically and with subcycle time resolution. A pump-probe sequence reveals in a movie the sample’s oscillating electromagnetic field vectors with time, phase, amplitude, and polarization information. This waveform electron microscopy can be used to visualize electrodynamic phenomena in devices as small and fast as available.

  9. Electron microscopy of electromagnetic waveforms.

    PubMed

    Ryabov, A; Baum, P

    2016-07-22

    Rapidly changing electromagnetic fields are the basis of almost any photonic or electronic device operation. We report how electron microscopy can measure collective carrier motion and fields with subcycle and subwavelength resolution. A collimated beam of femtosecond electron pulses passes through a metamaterial resonator that is previously excited with a single-cycle electromagnetic pulse. If the probing electrons are shorter in duration than half a field cycle, then time-frozen Lorentz forces distort the images quasi-classically and with subcycle time resolution. A pump-probe sequence reveals in a movie the sample's oscillating electromagnetic field vectors with time, phase, amplitude, and polarization information. This waveform electron microscopy can be used to visualize electrodynamic phenomena in devices as small and fast as available.

  10. Lasers for nonlinear microscopy.

    PubMed

    Wise, Frank

    2013-03-01

    Various versions of nonlinear microscopy are revolutionizing the life sciences, almost all of which are made possible because of the development of ultrafast lasers. In this article, the main properties and technical features of short-pulse lasers used in nonlinear microscopy are summarized. Recent research results on fiber lasers that will impact future instruments are also discussed.

  11. Polymorphism and disorder in natural active ingredients. Low and high-temperature phases of anhydrous caffeine: Spectroscopic ((1)H-(14)N NMR-NQR/(14)N NQR) and solid-state computational modelling (DFT/QTAIM/RDS) study.

    PubMed

    Seliger, Janez; Žagar, Veselko; Apih, Tomaž; Gregorovič, Alan; Latosińska, Magdalena; Olejniczak, Grzegorz Andrzej; Latosińska, Jolanta Natalia

    2016-03-31

    The polymorphism of anhydrous caffeine (1,3,7-trimethylxanthine; 1,3,7-trimethyl-1H-purine-2,6-(3H,7H)-dione) has been studied by (1)H-(14)N NMR-NQR (Nuclear Magnetic Resonance-Nuclear Quadrupole Resonance) double resonance and pure (14)N NQR (Nuclear Quadrupole Resonance) followed by computational modelling (Density Functional Theory, supplemented Quantum Theory of Atoms in Molecules with Reduced Density Gradient) in solid state. For two stable (phase II, form β) and metastable (phase I, form α) polymorphs the complete NQR spectra consisting of 12 lines were recorded. The assignment of signals detected in experiment to particular nitrogen sites was verified with the help of DFT. The shifts of the NQR frequencies, quadrupole coupling constants and asymmetry parameters at each nitrogen site due to polymorphic transition were evaluated. The strongest shifts were observed at N(3) site, while the smallest at N(9) site. The commercial pharmaceutical sample was found to contain approximately 20-25% of phase I and 75-80% of phase II. The orientational disorder in phase II with a local molecular arrangement mimics that in phase I. Substantial differences in the intermolecular interaction phases I and II of caffeine were analysed using computational (DFT/QTAIM/RDS) approach. The analysis of local environment of each nitrogen nucleus permitted drawing some conclusions on the topology of interactions in both polymorphs. For the most stable orientations in phase I and phase II the maps of the principal component qz of EFG tensor and its asymmetry parameter at each point of the molecular system were calculated and visualized. The relevant maps calculated for both phases I and II indicates small variation in electrostatic potential upon phase change. Small differences between packings in phases slightly disturb the neighbourhood of the N(1) and N(7) nitrogens, thus are meaningless from the biological point of view. The composition of two phases in pharmaceutical material

  12. 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.

  13. Stabilization of copper catalysts for liquid-phase reactions by atomic layer deposition.

    PubMed

    O'Neill, Brandon J; Jackson, David H K; Crisci, Anthony J; Farberow, Carrie A; Shi, Fengyuan; Alba-Rubio, Ana C; Lu, Junling; Dietrich, Paul J; Gu, Xiangkui; Marshall, Christopher L; Stair, Peter C; Elam, Jeffrey W; Miller, Jeffrey T; Ribeiro, Fabio H; Voyles, Paul M; Greeley, Jeffrey; Mavrikakis, Manos; Scott, Susannah L; Kuech, Thomas F; Dumesic, James A

    2013-12-16

    Atomic layer deposition (ALD) of an alumina overcoat can stabilize a base metal catalyst (e.g., copper) for liquid-phase catalytic reactions (e.g., hydrogenation of biomass-derived furfural in alcoholic solvents or water), thereby eliminating the deactivation of conventional catalysts by sintering and leaching. This method of catalyst stabilization alleviates the need to employ precious metals (e.g., platinum) in liquid-phase catalytic processing. The alumina overcoat initially covers the catalyst surface completely. By using solid state NMR spectroscopy, X-ray diffraction, and electron microscopy, it was shown that high temperature treatment opens porosity in the overcoat by forming crystallites of γ-Al2 O3 . Infrared spectroscopic measurements and scanning tunneling microscopy studies of trimethylaluminum ALD on copper show that the remarkable stability imparted to the nanoparticles arises from selective armoring of under-coordinated copper atoms on the nanoparticle surface. PMID:24282166

  14. X-ray diffraction and Raman spectroscopic investigations on CaZrTi2O7sbnd Y2Ti2O7 system: Delineation of phase fields consisting of potential ceramic host materials

    NASA Astrophysics Data System (ADS)

    Jafar, M.; Achary, S. N.; Salke, Niliesh P.; Sahu, A. K.; Rao, Rekha; Tyagi, A. K.

    2016-07-01

    Phase evolution from CaZrTi2O7 (zirconolite) to Y2Ti2O7 (pyrochlore) have been delineated by systematic characterization of a series of sample with composition as Ca1-xZr1-xY2xTi2O7 (0.00 ≤ x ≤ 1.00) by powder XRD, Raman spectroscopy, SEM and EDS analyses. Comparative analyses of XRD and Raman spectra revealed sequential evolution of phases with increasing concentration of Y3+ in the compositions. From the XRD studies, three distinct phase fields, namely two layer (2M) and four layer (4M) zirconolite-types and cubic pyrochlore-type are observed in between zirconolite (CaZrTi2O7) and Y2Ti2O7. 4M-zirconolite phase is observed in a narrow range of composition, viz. 0.35 ≤ x ≤ 0.40 while cubic pyrochlore type phase is observed in the compositions with x ≥ 1.20. The unit cell volume of different phases shows a non-linear increasing trend with Y3+ ion concentration which has been attributed to the distribution of cations in different structure and change in their coordination number.

  15. Photo-induced force for spectroscopic imaging at the nanoscale

    NASA Astrophysics Data System (ADS)

    Jahng, Junghoon; Tork Ladani, Faezeh; Khan, Ryan M.; Potma, Eric O.

    2016-03-01

    Photo-induced force microscopy (PiFM) is a new scan probe method that enables imaging with spectroscopic contrast at the nanoscale. The operating principle of PiFM is based on the coupling between a sharp atomic tip and a polarizable object, as mediated by the electromagnetic field in the vicinity of the tip-sample junction. In this contribution, we develop a description of the photo-induced force in the limit where the tip and object can be approximated as dipoles. This description provides an insightful picture of the forces at play in the tip-sample junction in terms of the gradient and scattering forces. We consider various approximations that are relevant to experimental conditions. The theoretical approach described here successfully explains the previous spectroscopic PiFM measurements in the visible and in the near-IR range, and the anticipated spectral information that can be retrieved under mid infrared illumination.

  16. Spectroscopic methods for the photodiagnosis of nonmelanoma skin cancer.

    PubMed

    Drakaki, Eleni; Vergou, Theognosia; Dessinioti, Clio; Stratigos, Alexander J; Salavastru, Carmen; Antoniou, Christina

    2013-06-01

    The importance of dermatological noninvasive imaging techniques has increased over the last decades, aiming at diagnosing nonmelanoma skin cancer (NMSC). Technological progress has led to the development of various analytical tools, enabling the in vivo/in vitro examination of lesional human skin with the aim to increase diagnostic accuracy and decrease morbidity and mortality. The structure of the skin layers, their chemical composition, and the distribution of their compounds permits the noninvasive photodiagnosis of skin diseases, such as skin cancers, especially for early stages of malignant tumors. An important role in the dermatological diagnosis and disease monitoring has been shown for promising spectroscopic and imaging techniques, such as fluorescence, diffuse reflectance, Raman and near-infrared spectroscopy, optical coherence tomography, and confocal laser-scanning microscopy. We review the use of these spectroscopic techniques as noninvasive tools for the photodiagnosis of NMSC.

  17. Fractals in microscopy.

    PubMed

    Landini, G

    2011-01-01

    Fractal geometry, developed by B. Mandelbrot, has provided new key concepts necessary to the understanding and quantification of some aspects of pattern and shape randomness, irregularity, complexity and self-similarity. In the field of microscopy, fractals have profound implications in relation to the effects of magnification and scaling on morphology and to the methodological approaches necessary to measure self-similar structures. In this article are reviewed the fundamental concepts on which fractal geometry is based, their relevance to the microscopy field as well as a number of technical details that can help improving the robustness of morphological analyses when applied to microscopy problems.

  18. Super resolution fluorescence microscopy

    PubMed Central

    Huang, Bo; Bates, Mark; Zhuang, Xiaowei

    2010-01-01

    Achieving a spatial resolution that is not limited by the diffraction of light, recent developments of super-resolution fluorescence microscopy techniques allow the observation of many biological structures not resolvable in conventional fluorescence microscopy. New advances in these techniques now give them the ability to image three-dimensional (3D) structures, measure interactions by multicolor colocalization, and record dynamic processes in living cells at the nanometer scale. It is anticipated that super-resolution fluorescence microscopy will become a widely used tool for cell and tissue imaging to provide previously unobserved details of biological structures and processes. PMID:19489737

  19. EPSILON AURIGAE: AN IMPROVED SPECTROSCOPIC ORBITAL SOLUTION

    SciTech Connect

    Stefanik, Robert P.; Torres, Guillermo; Lovegrove, Justin; Latham, David W.; Zajac, Joseph; Pera, Vivian E.; Mazeh, Tsevi

    2010-03-15

    A rare eclipse of the mysterious object {epsilon} Aurigae will occur in 2009-2011. We report an updated single-lined spectroscopic solution for the orbit of the primary star based on 20 years of monitoring at the CfA, combined with historical velocity observations dating back to 1897. There are 518 new CfA observations obtained between 1989 and 2009. Two solutions are presented. One uses the velocities outside the eclipse phases together with mid-times of previous eclipses, from photometry dating back to 1842, which provide the strongest constraint on the ephemeris. This yields a period of 9896.0 {+-} 1.6 days (27.0938 {+-} 0.0044 years) with a velocity semi-amplitude of 13.84 {+-} 0.23 km s{sup -1} and an eccentricity of 0.227 {+-} 0.011. The middle of the current ongoing eclipse predicted by this combined fit is JD 2,455,413.8 {+-} 4.8, corresponding to 2010 August 5. If we use only the radial velocities, we find that the predicted middle of the current eclipse is nine months earlier. This would imply that the gravitating companion is not the same as the eclipsing object. Alternatively, the purely spectroscopic solution may be biased by perturbations in the velocities due to the short-period oscillations of the supergiant.

  20. A DVD Spectroscope: A Simple, High-Resolution Classroom Spectroscope

    ERIC Educational Resources Information Center

    Wakabayashi, Fumitaka; Hamada, Kiyohito

    2006-01-01

    Digital versatile disks (DVDs) have successfully made up an inexpensive but high-resolution spectroscope suitable for classroom experiments that can easily be made with common material and gives clear and fine spectra of various light sources and colored material. The observed spectra can be photographed with a digital camera, and such images can…