Science.gov

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. 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.

  3. Super-resolution spectroscopic microscopy via photon localization.

    PubMed

    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

  4. 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.

  5. 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

  6. Low dose, limited energy spectroscopic x-ray microscopy

    NASA Astrophysics Data System (ADS)

    Nelson Weker, Johanna; Li, Yiyang; Chueh, William C.

    2015-09-01

    In order to achieve high quality in situ spectroscopic X-ray microscopy of complex systems far from equilibrium, such as lithium ion batteries under standard electrochemical cycling, careful consideration of the total number of energy points is required. Enough energy points are need to accurately determine the per pixel chemical information; however, total radiation dose needs to be limited to avoid damaging the system which would produce misleading results. Here we consider the number of energy points need to accurately reproduce the state of charge maps of a LiFePO2 electrode recorded during electrochemical cycling. We observe very good per pixel agreement using only 13 energy points. Additionally, we find the quality of the agreement is heavily dependent on the number of energy points used in the post edge fit during normalization of the spectra rather than the total number of energies used. Finally, we suggest a straightforward protocol for determining the minimum number of energy points needed prior to initiating any in situ spectroscopic X-ray microscopy experiment.

  7. Spectroscopic analysis of skin intrinsic signals for multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Pena, Ana-Maria; Strupler, Mathias; Boulesteix, Thierry; Senni, Karim; Godeau, Gaston; Beaurepaire, Emmanuel; Schanne-Klein, Marie-Claire

    2006-02-01

    We recorded multiphoton images of human skin biopsies using endogenous sources of nonlinear optical signals. We detected simultaneously two-photon excited fluorescence (2PEF) from intrinsic fluorophores and second harmonic generation (SHG) from collagen. We observed SHG from fibrillar collagens in the dermis, whereas no SHG was detectable from the non fibrillar type IV collagen in the basal laminae. We compared these distinct behaviours of collagens I and IV in SHG microscopy to polarization-resolved surface SHG experiments on thin films of collagens I and IV molecules. We observed similar signals for both types of molecular films, except for the chiroptical contributions which are present only for collagen I and enhance the signal typically by a factor of 2. We concluded that SHG microscopy is a sensitive probe of the micrometer-scale structural organization of collagen in biological tissues. In order to elucidate the origin of the endogenous fluorescence signals, we recorded 2PEF spectra at various positions in the skin biopsies, and compared these data to in vitro spectroscopic analysis. In particular, we studied the keratin fluorescence and determined its 2PEF action cross section. We observed a good agreement between 2PEF spectra recorded in the keratinized upper layers of the epidermis and in a solution of purified keratin. Finally, to illustrate the capabilities of this technique, we recorded 2PEF/SHG images of skin biopsies obtained from patients of various ages.

  8. Numerical focusing in diffraction phase microscopy

    NASA Astrophysics Data System (ADS)

    Talaikova, N. A.; Grebenyuk, A. A.; Kalyanov, A. L.; Ryabukho, V. P.

    2016-04-01

    Diffraction phase microscopy (DPM) provides the possibility of high-resolution quantitative phase imaging, based on equipment of an optical microscope with a special module working in a common-path off-axis configuration. As an optical microscopy technique, DPM has a limited focus depth, which is the smaller the higher is the objective's numerical aperture. In this paper we present the results of experimental investigation of numerical focusing with the angular spectrum method in DPM.

  9. Tomographic phase microscopy using optical tweezers

    NASA Astrophysics Data System (ADS)

    Habaza, Mor; Gilboa, Barak; Roichman, Yael; Shaked, Natan T.

    2015-07-01

    We review our technique for tomographic phase microscopy with optical tweezers [1]. This tomographic phase microscopy approach enables full 3-D refractive-index reconstruction. Tomographic phase microscopy measures quantitatively the 3- D distribution of refractive-index in biological cells. We integrated our external interferometric module with holographic optical tweezers for obtaining quantitative phase maps of biological samples from a wide range of angles. The close-tocommon- path, off-axis interferometric system enables a full-rotation tomographic acquisition of a single cell using holographic optical tweezers for trapping and manipulating with a desired array of traps, while acquiring phase information of a single cell from all different angles and maintaining the native surrounding medium. We experimentally demonstrated two reconstruction algorithms: the filtered back-projection method and the Fourier diffraction method for 3-D refractive index imaging of yeast cells.

  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. Spectroscopic scanning tunneling microscopy insights into Fe-based superconductors

    NASA Astrophysics Data System (ADS)

    Hoffman, Jennifer E.

    2011-12-01

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

  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. Photorefractive phase-conjugation digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Chang, Chi-Ching; Chan, Huang-Tian; Shiu, Min-Tzung; Chew, Yang-Kun

    2015-05-01

    In this work, we propose an innovative method for digital holographic microscopy named as photorefractive phaseconjugation digital holographic microscopy (PPCDHM) technique based on the phase conjugation dynamic holographic process in photorefractive BaTiO3 crystal and the retrieval of phase and amplitude of the object wave were performed by a reflection-type digital holographic method. Both amplitude and phase reconstruction benefit from the prior amplification by self-pumped conjugation (SPPC) as they have an increased SNR. The interest of the PPCDHM is great, because its hologram is created by interfered the amplified phase-conjugate wave field generated from a photorefractive phase conjugator (PPC) correcting the phase aberration of the imaging system and the reference wave onto the digital CCD camera. Therefore, a precise three-dimensional description of the object with high SNR can be obtained digitally with only one hologram acquisition. The method requires the acquisition of a single hologram from which the phase distribution can be obtained simultaneously with distribution of intensity at the surface of the object.

  14. Video-rate tomographic phase microscopy

    PubMed Central

    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

  15. 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.

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

    PubMed

    Goldstein, Goldie; Creath, Katherine

    2014-03-12

    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. Bright-field quantitative phase microscopy (BFQPM) for accurate phase imaging using conventional microscopy hardware

    NASA Astrophysics Data System (ADS)

    Jenkins, Micah; Gaylord, Thomas K.

    2015-03-01

    Most quantitative phase microscopy methods require the use of custom-built or modified microscopic configurations which are not typically available to most bio/pathologists. There are, however, phase retrieval algorithms which utilize defocused bright-field images as input data and are therefore implementable in existing laboratory environments. Among these, deterministic methods such as those based on inverting the transport-of-intensity equation (TIE) or a phase contrast transfer function (PCTF) are particularly attractive due to their compatibility with Köhler illuminated systems and numerical simplicity. Recently, a new method has been proposed, called multi-filter phase imaging with partially coherent light (MFPI-PC), which alleviates the inherent noise/resolution trade-off in solving the TIE by utilizing a large number of defocused bright-field images spaced equally about the focal plane. Despite greatly improving the state-ofthe- art, the method has many shortcomings including the impracticality of high-speed acquisition, inefficient sampling, and attenuated response at high frequencies due to aperture effects. In this report, we present a new method, called bright-field quantitative phase microscopy (BFQPM), which efficiently utilizes a small number of defocused bright-field images and recovers frequencies out to the partially coherent diffraction limit. The method is based on a noiseminimized inversion of a PCTF derived for each finite defocus distance. We present simulation results which indicate nanoscale optical path length sensitivity and improved performance over MFPI-PC. We also provide experimental results imaging live bovine mesenchymal stem cells at sub-second temporal resolution. In all, BFQPM enables fast and accurate phase imaging with unprecedented spatial resolution using widely available bright-field microscopy hardware.

  19. Analyzing cell structure and dynamics with confocal light scattering and absorption spectroscopic microscopy

    NASA Astrophysics Data System (ADS)

    Qiu, Le; Vitkin, Edward; Fang, Hui; Zaman, Munir M.; Andersson, Charlotte; Salahuddin, Saira; Modell, Mark D.; Freedman, Steven D.; Hanlon, Eugene B.; Itzkan, Irving; Perelman, Lev T.

    2007-02-01

    We recently developed a new microscopic optical technique capable of noninvasive analysis of cell structure and cell dynamics on the submicron scale [1]. It combines confocal microscopy, a well-established high-resolution microscopic technique, with light scattering spectroscopy (LSS) and is called confocal light absorption and scattering spectroscopic (CLASS) microscopy. CLASS microscopy requires no exogenous labels and is capable of imaging and continuously monitoring individual viable cells, enabling the observation of cell and organelle functioning at scales on the order of 100 nm. To test the ability of CLASS microscopy to monitor cellular dynamics in vivo we performed experiments with human bronchial epithelial cells treated with DHA and undergoing apoptosis. The treated and untreated cells show not only clear differences in organelle spatial distribution but time sequencing experiments on a single cell show disappearance of certain types of organelles and change of the nuclear shape and density with the progression of apoptosis. In summary, CLASS microscopy provides an insight into metabolic processes within the cell and opens doors for the noninvasive real-time assessment of cellular dynamics. Noninvasive monitoring of cellular dynamics with CLASS microscopy can be used for a real-time dosimetry in a wide variety of medical and environmental applications that have no immediate observable outcome, such as photodynamic therapy, drug screening, and monitoring of toxins.

  20. Orbital lesions: proton spectroscopic phase-dependent contrast MR imaging.

    PubMed

    Atlas, S W; Grossman, R I; Axel, L; Hackney, D B; Bilaniuk, L T; Goldberg, H I; Zimmerman, R A

    1987-08-01

    Thirteen orbital lesions in 12 patients were evaluated with both conventional spin-echo magnetic resonance (MR) imaging and phase-dependent proton spectroscopic imaging. This technique, which makes use of small differences in the resonant frequencies of water and fat protons, provides excellent high-resolution images with simultaneous chemical shift information. In this method, there is 180 degrees opposition of phase between fat protons and water protons at the time of the gradient echo, resulting in signal cancellation in voxels containing equal signals from fat and water. In this preliminary series, advantages of spectroscopic images in orbital lesions included better lesion delineation, with superior anatomic definition of orbital apex involvement; more specific characterization of high-intensity hemorrhage with a single pulse sequence; elimination of potential confusion from chemical shift misregistration artifact; further clarification of possible intravascular flow abnormalities; and improved apparent intralesional contrast. PMID:3602394

  1. 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.

  2. Design Of A New In Situ Spectroscopic Phase Modulated Ellipsometer

    NASA Astrophysics Data System (ADS)

    Drevillon, Bernard; Parey, J. Y.; Stchakovsky, M.; Benferhat, Ramdane; Josserand, Yves; Schlayen, B.

    1990-02-01

    A new spectroscopic phase modulated ellipsometer (SPME) is presented. As compared to other ellipsometric techniques like rotating analyzer ellipsometry (RAE), the phase modulation uses a high frequency modulation (50 kHz) provided by a photoelastic modulator. Then SPME allows at least two orders of magnitude faster real-time mesurements than RAE. Thus, SPME is particularly suitable for in situ real-time applications. New insights on phase modulated ellipsometry are given. In particular, it is shown that an optical model, taking into account the presence of higher harmonics in the modulation, leads to an improvement of the precision measurement. Therefore, it can be inferred that both RAE and SPME provide comparable high precision measurements. Moreover SPME can be combined with numerical data processing systems. A new Fourier analysis of the signal, based on the use of a high precision analog digital converter and a fast digital processor, is presented. The adaptation of the SPME to a deposition chamber is illustrated. In particular, the use of optical fibers in both optical arms allows an increase of the compactness of the ellipsometer. Four detectors can be used simultaneously providing the spectroscopic capability for real-time applications. On-line connexions between the data acquisition system and external analog signals and triggers can also be used. Thus phase modulated ellipsometry appears a powerful technique for in situ control processing applications.

  3. Quantitative Phase Retrieval in Transmission Electron Microscopy

    NASA Astrophysics Data System (ADS)

    McLeod, Robert Alexander

    Phase retrieval in the transmission electron microscope offers the unique potential to collect quantitative data regarding the electric and magnetic properties of materials at the nanoscale. Substantial progress in the field of quantitative phase imaging was made by improvements to the technique of off-axis electron holography. In this thesis, several breakthroughs have been achieved that improve the quantitative analysis of phase retrieval. An accurate means of measuring the electron wavefront coherence in two-dimensions was developed and pratical applications demonstrated. The detector modulation-transfer function (MTF) was assessed by slanted-edge, noise, and the novel holographic techniques. It was shown the traditional slanted-edge technique underestimates the MTF. In addition, progress was made in dark and gain reference normalization of images, and it was shown that incomplete read-out is a concern for slow-scan CCD detectors. Last, the phase error due to electron shot noise was reduced by the technique of summation of hologram series. The phase error, which limits the finest electric and magnetic phenomena which can be investigated, was reduced by over 900 % with no loss of spatial resolution. Quantitative agreement between the experimental root-mean-square phase error and the analytical prediction of phase error was achieved.

  4. 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)

  5. Fast pixel shifting phase unwrapping algorithm in quantitative interferometric microscopy

    NASA Astrophysics Data System (ADS)

    Xu, Mingfei; Shan, Yanke; Yan, Keding; Xue, Liang; Wang, Shouyu; Liu, Fei

    2014-11-01

    Quantitative interferometric microscopy is an important method for observing biological samples such as cells and tissues. In order to obtain continuous phase distribution of the sample from the interferogram, phase extracting and phase unwrapping are both needed in quantitative interferometric microscopy. Phase extracting includes fast Fourier transform method and Hilbert transform method, etc., almost all of them are rapid methods. However, traditional unwrapping methods such as least squares algorithm, minimum network flow method, etc. are time-consuming to locate the phase discontinuities which lead to low processing efficiency. Other proposed high-speed phase unwrapping methods always need at least two interferograms to recover final phase distributions which cannot realize real time processing. Therefore, high-speed phase unwrapping algorithm for single interferogram is required to improve the calculation efficiency. Here, we propose a fast phase unwrapping algorithm to realize high-speed quantitative interferometric microscopy, by shifting mod 2π wrapped phase map for one pixel, then multiplying the original phase map and the shifted one, then the phase discontinuities location can be easily determined. Both numerical simulation and experiments confirm that the algorithm features fast, precise and reliable.

  6. 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.

  7. 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)

  8. 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.

  9. 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.

  10. Drive frequency dependent phase imaging in piezoresponse force microscopy

    SciTech Connect

    Bo Huifeng; Kan Yi; Lu Xiaomei; Liu Yunfei; Peng Song; Wang Xiaofei; Cai Wei; Xue Ruoshi; Zhu Jinsong

    2010-08-15

    The drive frequency dependent piezoresponse (PR) phase signal in near-stoichiometric lithium niobate crystals is studied by piezoresponse force microscopy. It is clearly shown that the local and nonlocal electrostatic forces have a great contribution to the PR phase signal. The significant PR phase difference of the antiparallel domains are observed at the contact resonances, which is related to the electrostatic dominated electromechanical interactions of the cantilever and tip-sample system. Moreover, the modulation voltage induced frequency shift at higher eigenmodes could be attributed to the change of indention force depending on the modulation amplitude with a piezoelectric origin. The PR phase of the silicon wafer is also measured for comparison. It is certificated that the electrostatic interactions are universal in voltage modulated scanning probe microscopy and could be extended to other phase imaging techniques.

  11. Terahertz phase microscopy in the sub-wavelength regime

    NASA Astrophysics Data System (ADS)

    Yi, Minwoo; Lee, Kanghee; Song, Jin-Dong; Ahn, Jaewook

    2012-04-01

    Gouy phase shift is a well-known behavior that occurs when a propagating light is focused, but its behavior in the sub-wavelength confinement is not yet known. Here, we report the theoretical and experimental study of the aperture-size dependency of the Gouy phase shift in the sub-wavelength diffraction regime. In experiments carried out with laser-induced terahertz (THz) wave emission from various semiconductor apertures, we demonstrate the use of Guoy phase shit for sub-wavelength THz microscopy.

  12. 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

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

    PubMed Central

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

    2016-01-01

    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

  14. Structured illumination quantitative phase microscopy for enhanced resolution amplitude and phase imaging

    PubMed Central

    Chowdhury, Shwetadwip; Izatt, Joseph

    2013-01-01

    Structured illumination microscopy (SIM) is an established microscopy technique typically used to image samples at resolutions beyond the diffraction limit. Until now, however, achieving sub-diffraction resolution has predominantly been limited to intensity-based imaging modalities. Here, we introduce an analogue to conventional SIM that allows sub-diffraction resolution, quantitative phase-contrast imaging of optically transparent objects. We demonstrate sub-diffraction resolution amplitude and quantitative-phase imaging of phantom targets and enhanced resolution quantitative-phase imaging of cells. We report a phase accuracy to within 5% and phase noise of 0.06 rad. PMID:24156044

  15. Probing the duplex stainless steel phases via magnetic force microscopy

    NASA Astrophysics Data System (ADS)

    Gheno, S. M.; Santos, F. S.; Kuri, S. E.

    2008-03-01

    Duplex stainless steels are austenitic-ferritic alloys used in many applications, thanks to their excellent mechanical properties and high corrosion resistance. In this work, chemical analyses, x-ray diffraction, and magnetic force microscopy (MFM) were employed to characterize the solution annealed and aged duplex stainless steel. The samples exhibited no changes in lattice parameters and the MFM technique proved successful in clearly imaging the magnetic domain structure of the ferrite phase.

  16. 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.

  17. Hilbert phase microscopy for investigating fast dynamics in transparent systems

    NASA Astrophysics Data System (ADS)

    Ikeda, Takahiro; Popescu, Gabriel; Dasari, Ramachandra R.; Feld, Michael S.

    2005-05-01

    We introduce Hilbert phase microscopy (HPM) as a novel optical technique for measuring high transverse resolution quantitative phase images associated with optically transparent objects. Because of its single-shot nature, HPM is suitable for investigating rapid phenomena that take place in transparent structures such as biological cells. The potential of this technique for studying biological systems is demonstrated with measurements of red blood cells, and its ability to quantify dynamic processes on a millisecond scale is exemplified with measurements of evaporating micrometer-sized water droplets.

  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. Performance analysis of quantitative phase retrieval method in Zernike phase contrast X-ray microscopy

    NASA Astrophysics Data System (ADS)

    Heng, Chen; Kun, Gao; Da-Jiang, Wang; Li, Song; Zhi-Li, Wang

    2016-02-01

    Since the invention of Zernike phase contrast method in 1930, it has been widely used in optical microscopy and more recently in X-ray microscopy. Considering the image contrast is a mixture of absorption and phase information, we recently have proposed and demonstrated a method for quantitative phase retrieval in Zernike phase contrast X-ray microscopy. In this contribution, we analyze the performance of this method at different photon energies. Intensity images of PMMA samples are simulated at 2.5 keV and 6.2 keV, respectively, and phase retrieval is performed using the proposed method. The results demonstrate that the proposed phase retrieval method is applicable over a wide energy range. For weakly absorbing features, the optimal photon energy is 2.5 keV, from the point of view of image contrast and accuracy of phase retrieval. On the other hand, in the case of strong absorption objects, a higher photon energy is preferred to reduce the error of phase retrieval. These results can be used as guidelines to perform quantitative phase retrieval in Zernike phase contrast X-ray microscopy with the proposed method. Supported by the State Key Project for Fundamental Research (2012CB825801), National Natural Science Foundation of China (11475170, 11205157 and 11179004) and Anhui Provincial Natural Science Foundation (1508085MA20).

  1. High-sensitive and broad-dynamic-range quantitative phase imaging with spectral domain phase microscopy.

    PubMed

    Yan, Yangzhi; Ding, Zhihua; Shen, Yi; Chen, Zhiyan; Zhao, Chen; Ni, Yang

    2013-11-01

    Spectral domain phase microscopy for high-sensitive and broad-dynamic-range quantitative phase imaging is presented. The phase retrieval is realized in the depth domain to maintain a high sensitivity, while the phase information obtained in the spectral domain is exploited to extend the dynamic range of optical path difference. Sensitivity advantage of phase retrieved in the depth domain over that in the spectral domain is thoroughly investigated. The performance of the proposed depth domain phase based approach is illustrated by phase imaging of a resolution target and an onion skin. PMID:24216799

  2. Bitumen morphologies by phase-detection atomic force microscopy.

    PubMed

    Masson, J-F; Leblond, V; Margeson, J

    2006-01-01

    Summary Bitumen is a complex mixture of hydrocarbons for which microstructural knowledge is incomplete. In an effort to detail this microstructure, 13 bitumens were analysed by phase-detection atomic force microscopy. Based on morphology, the bitumens could be classified into three distinct groups. One group showed fine domains down to 0.1 microm, another showed domains of about 1 microm, and a third group showed up to four different domains or phases of different sizes and shapes. No correlation was found between the atomic force microscopy morphology and the composition based on asphaltenes, polar aromatics, naphthene aromatics and saturates. A high correlation was found between the area of the 'bee-like' structures and the vanadium and nickel content in bitumen, and between the atomic force microscopy groups and the average size of molecular planes made of fused aromatics. The morphology and the molecular arrangements in bitumen thus appear to be partly governed by the molecular planes and the polarity defined by metallic cations. PMID:16438686

  3. Atomic force microscopy images of lyotropic lamellar phases

    NASA Astrophysics Data System (ADS)

    Garza, C.; Thieghi, L. T.; Castillo, R.

    2007-02-01

    For the very first time, atomic force microscope images of lamellar phases were observed combined with a freeze fracture technique that does not involve the use of replicas. Samples are rapidly frozen, fractured, and scanned directly with atomic force microscopy, at liquid nitrogen temperature and in high vacuum. This procedure can be used to investigate micro-structured liquids. The lamellar phases in Sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/water and in C12E5/water systems were used to asses this new technique. Our observations were compared with x-ray diffraction measurements and with other freeze fracture methods reported in the literature. Our results show that this technique is useful to image lyotropic lamellar phases and the estimated repeat distances for lamellar periodicity are consistent with those obtained by x-ray diffraction.

  4. Atomic force microscopy images of lyotropic lamellar phases.

    PubMed

    Garza, C; Thieghi, L T; Castillo, R

    2007-02-01

    For the very first time, atomic force microscope images of lamellar phases were observed combined with a freeze fracture technique that does not involve the use of replicas. Samples are rapidly frozen, fractured, and scanned directly with atomic force microscopy, at liquid nitrogen temperature and in high vacuum. This procedure can be used to investigate micro-structured liquids. The lamellar phases in Sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/water and in C12E5/water systems were used to asses this new technique. Our observations were compared with x-ray diffraction measurements and with other freeze fracture methods reported in the literature. Our results show that this technique is useful to image lyotropic lamellar phases and the estimated repeat distances for lamellar periodicity are consistent with those obtained by x-ray diffraction. PMID:17302467

  5. Region-referenced phase unwrapping architecture for digital holographic microscopy.

    PubMed

    Hwang, Wen-Jyi; Chen, Huan-Yuan; Cheng, Chau-Jern

    2015-01-01

    This work presents a novel hardware phase-unwrapping architecture for digital holographic microscopy. The architecture is based on an iterative region-referenced algorithm because of its simplicity and effectiveness for phase unwrapping. The architecture therefore consumes fewer hardware resources for very large-scale integration implementation. In addition, a novel data reuse scheme is adopted for reducing the memory bandwidth required by the architecture. The architecture can then have fast computation speed for the iterative operations. The architecture has been implemented by field programmable gate array. It acts as a hardware accelerator in an embedded system developed by a network-on-chip platform for performance measurement. The superiorities of the proposed architecture have been confirmed by the experiments. PMID:25967024

  6. 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

  7. Quantitative Phase Contrast Digital Holographic Microscopy in Biophotonics

    NASA Astrophysics Data System (ADS)

    Kemper, Björn; Langehanenberg, Patrik; von Bally, Gert

    2010-11-01

    Label-free, non-contact, non-destructive, on-line (video repetition rate), high resolution, full field (no scanning), quantitative analysis of morphology and dynamic processes in living cells are required features in life science research and medical diagnostics. Digital Holography combined with microscopic imaging provides these features simultaneously. The modular integration of digital holographic microscopy (DHM) into commercial microscopes yields an axial resolution with interferometric resolution while the lateral resolution is diffraction limited. As amplitude and phase are available by numerical reconstruction from a single digital hologram subsequent automated focus correction is enabled. The evaluation of quantitative digital holographic phase contrast images permits also an effective detection of lateral object movements. Thus, 3D tracking is achieved. The applicability of DHM techniques for dynamic live cell analysis is demonstrated by results from tumor cells and human erythrocytes.

  8. 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

  9. Automatic deconvolution in 4Pi-microscopy with variable phase.

    PubMed

    Vicidomini, Giuseppe; Schmidt, Roman; Egner, Alexander; Hell, Stefan; Schönle, Andreas

    2010-05-10

    4Pi-microscopy doubles the aperture of the imaging system by coherent addition of the wavefronts for illumination and/or detection through opposing objective lenses. This improves the axial resolution 3-7 fold, but the raw data usually features ghost images which have to be removed by image reconstruction. This straightforward procedure is sometimes precluded by imperfect alignment of the instrument or a specimen with strong variations of its refractive index, because the image formation process now depends on the space-variant phase difference between the counter-propagating wavefronts. Here we present a computationally fast method of parametric blind deconvolution that allows for automatic and robust simultaneous estimation of both the object and the phase function in such cases. We verify the performance of our approach on both synthetic and real data. Because the method does not require a-priori knowledge of the phase function it is major step towards reliable 4Pi-imaging and automatic image restoration by non-expert users. PMID:20588870

  10. IMAGING RED BLOOD CELL DYNAMICS BY QUANTITATIVE PHASE MICROSCOPY

    PubMed Central

    Popescu, Gabriel; Park, YoungKeun; Choi, Wonshik; Dasari, Ramachandra R.; Feld, Michael S.; Badizadegan, Kamran

    2008-01-01

    Red blood cells (RBCs) play a crucial role in health and disease, and structural and mechanical abnormalities of these cells have been associated with important disorders such as Sickle cell disease and hereditary cytoskeletal abnormalities. Although several experimental methods exist for analysis of RBC mechanical properties, optical methods stand out as they enable collecting mechanical and dynamic data from live cells without physical contact and without the need for exogenous contrast agents. In this report, we present quantitative phase microscopy techniques that enable imaging RBC membrane fluctuations with nanometer sensitivity at arbitrary time scales from milliseconds to hours. We further provide a theoretical framework for extraction of membrane mechanical and dynamical properties using time series of quantitative phase images. Finally, we present an experimental approach to extend quantitative phase imaging to 3-dimensional space using tomographic methods. By providing non-invasive methods for imaging mechanics of live cells, these novel techniques provide an opportunity for high-throughput analysis and study of RBC mechanical properties in health and disease. PMID:18387320

  11. 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

  12. 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

  13. Quantitative phase microscopy: automated background leveling techniques and smart temporal phase unwrapping.

    PubMed

    Goldstein, Goldie; Creath, Katherine

    2015-06-01

    In order for time-dynamic quantitative phase microscopy to yield meaningful data to scientists, raw phase measurements must be converted to sequential time series that are consistently phase unwrapped with minimal residual background shape. Beyond the initial phase unwrapping, additional steps must be taken to convert the phase to time-meaningful data sequences. This consists of two major operations both outlined in this paper and shown to operate robustly on biological datasets. An automated background leveling procedure is introduced that consistently removes background shape and minimizes mean background phase value fluctuations. By creating a background phase value that is stable over time, the phase values of features of interest can be examined as a function of time to draw biologically meaningful conclusions. Residual differences between sequential frames of data can be present due to inconsistent phase unwrapping, causing localized regions to have phase values at similar object locations inconsistently changed by large values between frames, not corresponding to physical changes in the sample being observed. This is overcome by introducing a new method, referred to as smart temporal unwrapping that temporally unwraps and filters the phase data such that small motion between frames is accounted for and phase data are unwrapped consistently between frames. The combination of these methods results in the creation of phase data that is stable over time by minimizing errors introduced within the processing of the raw data. PMID:26192681

  14. 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

  15. Three-dimensional quantitative phase imaging via tomographic deconvolution phase microscopy.

    PubMed

    Jenkins, Micah H; Gaylord, Thomas K

    2015-11-01

    The field of three-dimensional quantitative phase imaging (3D QPI) is expanding rapidly with applications in biological, medical, and industrial research, development, diagnostics, and metrology. Much of this research has centered on developing optical diffraction tomography (ODT) for biomedical applications. In addition to technical difficulties associated with coherent noise, ODT is not congruous with optical microscopy utilizing partially coherent light, which is used in most biomedical laboratories. Thus, ODT solutions have, for the most part, been limited to customized optomechanical systems which would be relatively expensive to implement on a wide scale. In the present work, a new phase reconstruction method, called tomographic deconvolution phase microscopy (TDPM), is described which makes use of commercial microscopy hardware in realizing 3D QPI. TDPM is analogous to methods used in deconvolution microscopy which improve spatial resolution and 3D-localization accuracy of fluorescence micrographs by combining multiple through-focal scans which are deconvolved by the system point spread function. TDPM is based on the 3D weak object transfer function theory which is shown here to be capable of imaging "nonweak" phase objects with large phase excursions. TDPM requires no phase unwrapping and recovers the entire object spectrum via object rotation, mitigating the need to fill in the "missing cone" of spatial frequencies algorithmically as in limited-angle ODT. In the present work, TDPM is demonstrated using optical fibers, including single-mode, polarization-maintaining, and photonic-crystal fibers as well as an azimuthally varying CO2-laser-induced long-period fiber grating period as test phase objects. PMID:26560576

  16. 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.

  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. Analytical electron microscopy in mineralogy; exsolved phases in pyroxenes

    USGS Publications Warehouse

    Nord, G.L., Jr.

    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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  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. 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.

  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. 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

  8. 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

  9. Hyperfine spectroscopic study of Laves phase HfFe 2

    NASA Astrophysics Data System (ADS)

    Belošević-Čavor, J.; Novaković, N.; Cekić, B.; Ivanović, N.; Manasijević, M.

    2004-05-01

    Hyperfine fields in HfFe 2 were measured at 181Ta probe using the time-differential perturbed angular correlation method (TDPAC) in the temperature range 78-1200 K. Analysis of the spectra revealed two interactions with hyperfine fields of 13.82(7) T and 8.0(2) T, at 293 K. First is ascribed to the interaction at the 8a position in the cubic C15 structure. The second can be assigned to a minor amount of hexagonal C14 phase, or to an irregular position of the probe in the C15 lattice. Results of calculations using LAPW-WIEN97 are in a good agreement with experiment.

  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. Structured illumination diffraction phase microscopy for broadband, sub-diffraction resolution, quantitative phase imaging

    PubMed Central

    Chowdhury, Shwetadwip; Izatt, Joseph A.

    2015-01-01

    Structured illumination microscopy (SIM) is an established technique that allows sub-diffraction resolution imaging by heterodyning high sample frequencies into the system’s passband via structured illumination. However, until now, SIM has been typically used to achieve sub-diffraction resolution for intensity-based imaging. Here, we present a novel optical setup that uses structured illumination with a broadband-light source to obtain noise-reduced, sub-diffraction resolution, quantitative-phase (QPM) imaging of cells. We compare this with a previous work for sub-diffraction QPM imaging via SIM that used a laser source, and was thus still corrupted by coherent noise. PMID:24562266

  12. Intensity and phase fields behind Phase Shifting Masks studied with High Resolution Interference Microscopy

    NASA Astrophysics Data System (ADS)

    Puthankovilakam, Krishnaparvathy; Scharf, Toralf; Herzig, Hans Peter; Weichelt, Tina; Zeitner, Uwe; Vogler, Uwe; Voelkel, Reinhard

    2015-03-01

    The proximity printing industry is in real need of high resolution results and it can be done using Phase Shift Mask (PSM) or by applying Optical Proximity Correction (OPC). In our research we are trying to find out details of how light fields behind the structures of photo masks develop in order to determine the best conditions and designs for proximity printing. We focus here on parameters that are used in real situation with gaps up to 50 μm and structure sizes down to 2 μm. The light field evolution behind the structures is studied and delivers insight in to precisions and tolerances that need to be respected. It is the first time that an experimental analysis of light propagation through mask is presented in detail, which includes information on intensity and phase. The instrument we use is known as High Resolution Interference Microscopy (HRIM). 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 and therefore printable structure till the desired proximity gap. In this paper we discuss in detail the evolution of intensity and phase fields of elbow or corner structure at different position behind a phase mask and interpret the main parameters. Of particular interest are tolerances against proximity gap variation and the resolution in printed structures.

  13. High-Temperature Phase Transition in Enstatite : Raman Spectroscopic Results

    NASA Astrophysics Data System (ADS)

    Reynard, B.; Bass, J.

    2003-12-01

    (Mg,Fe)SiO3 enstatite has various polymorphs of which orthoenstatite with space group Pbca is the most common in natural rocks. The existence of a high temperature form has been suggested from various experiments but its symmetry remains unknown. Recent high-temperature Brillouin measurements on nearly pure MgSiO3 show that this transition is first order with a strong hysteresis (Tc at about 1200-1250° C with increasing temperature, Tc around 1000° C with decreasing temperature; Jackson et al, 2003). It is accompanied by strong pretransitional softening of some elastic constants and has some important consequences in the understanding of upper mantle seismic properties especially in hot regions. In order to more fully understand the nature of this transition and possibly the structural changes associated with it, we have performed in situ Raman spectroscopy on pure enstatite up to the transition temperature. The transition is observed in the same temperature range with increasing temperature, and is characterized by a decrease of the number of Raman modes, which can be interpreted as the transition to a space group with reduced Wigner-Seitz cell. Pretransitional effects are observed especially on a low frequency mode at 80 cm-1, which displays pronounced anharmonic behaviour. Possible space groups are Pbcn (protoenstatite), C2/c (high-clinoenstatite) or a previously unreported Cmca structure. The latter is a supergroup of Pbca and could account for the pretransitional softening. On decreasing temperature, backtransformation to orthoenstatite is marked by the appearance of cracks along simple crystallographic directions, which eventually leads to the breaking of the submillimeter-sized single crystals used as starting materials. Areas of untransformed high-temperature phase can be preserved down to about 750° C. This large hysteresis is strongly controlled by crystal shape and size as well as thermal history. In a parallel experiments, needle shaped thin (5x50

  14. 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.

  15. 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.

  16. Effects of polarization and phase modulation on the focal spot in 4Pi microscopy

    NASA Astrophysics Data System (ADS)

    Liu, Shaocong; You, Shangting; Fang, Yue; Wang, Yifan; Kuang, Cuifang; Liu, Xu

    2016-07-01

    In 4Pi microscopy, the intensity and polarization distributions of the focal spot directly determine the system resolution, influencing its extended applications. This paper illustrates how the focal spot is affected by the polarization and phase modulation of the incident beams. Various combinations of polarization states and phase modulations are considered and their effects on the focal spot are investigated. The optimal configurations for generating a solid spot and a doughnut-shaped spot are proposed. This paper provides the theoretical basis and reference for extended applications, such as super-resolution confocal microscopy, 4Pi microscopy or 4Pi-STED microscopy.

  17. 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.

  18. Super-resolution microscopy of lipid bilayer phases.

    PubMed

    Kuo, Chinkuei; Hochstrasser, Robin M

    2011-04-01

    Sub-diffraction optical imaging with nanometer resolution of lipid phase-separated regions is reported. Merocyanine 540, a probe whose fluorescence is sensitive to the lipid phase, is combined with super-resolution imaging to distinguish the liquid- and gel-phase nanoscale domains of lipid bilayers supported on glass. The monomer-dimer equilibrium of MC540 in membranes is deemed responsible for the population difference of single-molecule fluorescence bursts in the different phase regions. The extension of this method to other binary or ternary lipid models or natural systems provides a promising new super-resolution strategy. PMID:21405121

  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. 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.

  2. 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.

  3. Raman Spectroscopic and Ultrasonic Measurements to Monitor the HMX ( ) Phase Transition

    SciTech Connect

    GIESKE,JOHN H.; MILLER,JILL C.; RENLUND,ANITA M.; TAPPAN,ALEXANDER S.

    1999-10-14

    The HMX {beta}-{delta} solid-solid phase transition, which occurs as HMX is heated near 170 C, is clearly 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 a predictive safety model for HMX and HMX-containing EMs. We report work in progress on monitoring the phase transition with real-time Raman spectroscopy and ultrasonic measurements aimed towards a better understanding of physical properties through the phase transition. HMX samples were confined with minimal free volume.in a cell with constant volume. The cell was heated at a controlled rate and real-time Raman spectroscopic or ultrasonic measurements were performed. Raman spectroscopy provides a clear distinction between the two phases because the vibrational transitions of the molecule change with confirmational changes associated with the phase transition. Ultrasonic time-of-flight measurements provide an additional method of distinguishing the two phases because the sound speed through the material changes with the phase transition. Ultrasonic attenuation measurements also provide information about microstructural changes such as increased porosity due to evolution of gaseous decomposition products.

  4. 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.

  5. 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.

  6. Dynamic speckle illumination wide-field reflection phase microscopy

    PubMed Central

    Choi, Youngwoon; Hosseini, Poorya; Choi, Wonshik; Dasari, Ramachandra R.; So, Peter T. C.; Yaqoob, Zahid

    2014-01-01

    We demonstrate a quantitative reflection-phase microscope based on time-varying speckle-field illumination. Due to the short spatial coherence length of the speckle field, the proposed imaging system features superior lateral resolution, 520 nm, as well as high-depth selectivity, 1.03 µm. Off-axis interferometric detection enables wide-field and single-shot imaging appropriate for high-speed measurements. In addition, the measured phase sensitivity of this method, which is the smallest measurable axial motion, is more than 40 times higher than that available using a transmission system. We demonstrate the utility of our method by successfully distinguishing the motion of the top surface from that of the bottom in red blood cells. The proposed method will be useful for studying membrane dynamics in complex eukaryotic cells. PMID:25361156

  7. 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.

  8. Geometric phase-shifting for low-coherence interference microscopy

    NASA Astrophysics Data System (ADS)

    Roy, M.; Svahn, P.; Cherel, L.; Sheppard, C. J. R.

    2002-06-01

    A low-coherence Linnik interference microscope using high numerical aperture optics has been constructed. The system uses a tungsten halogen lamp and Köhler illumination, with separate control over field and aperture stops, so that experiments can be conducted with a range of different operating conditions. The novel feature of the system is the use of an achromatic phase-shifter operating on the principle of the geometric phase, achieved by using a polarising beam splitter, a quarter wave plate and a rotating polariser. Image information is extracted from the visibility of the fringes, the position of the visibility peak along the scanning axis yielding the height of the test surface at the corresponding point.

  9. 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.

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

    PubMed Central

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

    2014-01-01

    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. PMID:24940535

  11. A phase space model of Fourier ptychographic microscopy

    PubMed Central

    Horstmeyer, Roarke; Yang, Changhuei

    2014-01-01

    A new computational imaging technique, termed Fourier ptychographic microscopy (FPM), uses a sequence of low-resolution images captured under varied illumination to iteratively converge upon a high-resolution complex sample estimate. Here, we propose a mathematical model of FPM that explicitly connects its operation to conventional ptychography, a common procedure applied to electron and X-ray diffractive imaging. Our mathematical framework demonstrates that under ideal illumination conditions, conventional ptychography and FPM both produce datasets that are mathematically linked by a linear transformation. We hope this finding encourages the future cross-pollination of ideas between two otherwise unconnected experimental imaging procedures. In addition, the coherence state of the illumination source used by each imaging platform is critical to successful operation, yet currently not well understood. We apply our mathematical framework to demonstrate that partial coherence uniquely alters both conventional ptychography’s and FPM’s captured data, but up to a certain threshold can still lead to accurate resolution-enhanced imaging through appropriate computational post-processing. We verify this theoretical finding through simulation and experiment. PMID:24514995

  12. 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

  13. 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

  14. Neural stem cell tracking with phase contrast video microscopy

    NASA Astrophysics Data System (ADS)

    Rigaud, Stéphane U.; Loménie, Nicolas

    2011-03-01

    Tracking and segmenting objects for video surveillance is a well known field of research and very efficient methods exist. Usually embedded in traffic surveillance camera, these processes are not necessary adapted for biological surveillance context. In stem cell study, the design of a framework to monitor cell development in real time improves the stem cell analysis and biological understanding. In this purpose, we propose to test the Σ - ▵ motion filter, normally developed for security and surveillance camera, in order to track neural stem cells and their evolution over time, based on phase contrast image sequences. The motion filter is based on the difference between the current frame and a reference image of the background and uses a recursive spatio-temporal morphological operator called hybrid reconstruction to compensate for ghost and trace usually occurring with those kinds of methods.

  15. Phase-shifting by means of an electronically tunable lens: quantitative phase imaging of biological specimens with digital holographic microscopy.

    PubMed

    Trujillo, Carlos; Doblas, Ana; Saavedra, Genaro; Martínez-Corral, Manuel; García-Sucerquia, Jorge

    2016-04-01

    The use of an electronically tunable lens (ETL) to produce controlled phase shifts in interferometric arrangements is shown. The performance of the ETL as a phase-shifting device is experimentally validated in phase-shifting digital holographic microscopy. Quantitative phase maps of a section of the thorax of a Drosophila melanogaster fly and of human red blood cells have been obtained using our proposal. The experimental results validate the possibility of using the ETL as a reliable phase-shifter device. PMID:27192250

  16. Unstained viable cell recognition in phase-contrast microscopy

    NASA Astrophysics Data System (ADS)

    Skoczylas, M.; Rakowski, W.; Cherubini, R.; Gerardi, S.

    2011-09-01

    Individual cell recognition is a relevant task to be accomplished when single-ion microbeam irradiations are performed. At INFN-LNL facility cell visualization system is based on a phase-contrast optical microscope, without the use of any cell dye. Unstained cells are seeded in the special designed Petri dish, between two mylar foils, and at present the cell recognition is achieved manually by an expert operator. Nevertheless, this procedure is time consuming and sometimes it could be not practical if the amount of living cells to be irradiated is large. To reduce the time needed to recognize unstained cells on the Petri dish, it has been designed and implemented an automated, parallel algorithm. Overlapping ROIs sliding in steps over the captured grayscale image are firstly pre-classified and potential cell markers for the segmentation are obtained. Segmented objects are additionally classified to categorize cell bodies from other structures considered as sample dirt or background. As a result, cell coordinates are passed to the dedicated CELLView program that controls all the LNL single-ion microbeam irradiation protocol, including the positioning of individual cells in front of the ion beam. Unstained cell recognition system was successfully tested in experimental conditions with two different mylar surfaces. The recognition time and accuracy was acceptable, however, improvements in speed would be useful.

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

    PubMed

    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

  19. 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

  20. 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.

  1. Combining microscopy with spectroscopic and chemical methods for tracing the origin of atmospheric fallouts from mining sites.

    PubMed

    Navel, Aline; Uzu, Gaëlle; Spadini, Lorenzo; Sobanska, Sophie; Martins, Jean M F

    2015-12-30

    Populations living close to mining sites are often exposed to important heavy metal concentrations, especially through atmospheric fallouts. Identifying the main sources of metal-rich particles remains a challenge because of the similarity of the particle signatures from the polluted sites. This work provides an original combination of physical and chemical methods to determine the main sources of airborne particles impacting inhabited zones. Raman microspectrometry (RMS), X-ray diffraction (DRX), morphology analyses by microscopy and chemical composition were assessed. Geochemical analysis allowed the identification of target and source areas; XRD and RMS analysis identified the main mineral phases in association with their metal content and speciation. The characterization of the dominant minerals was combined with particle morphology analysis to identify fallout sources. The complete description of dust morphologies permitted the successful determination of a fingerprint of each source site. The analysis of these chemical and morphological fingerprints allowed identification of the mine area as the main contributor of metal-rich particles impacting the inhabited zone. In addition to the identification of the main sources of airborne particles, this study will also permit to better define the extent of polluted zones requiring remediation or protection from eolian erosion inducing metal-rich atmospheric fallouts. PMID:26253233

  2. 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.

  3. Recent Developments in Solid-Phase Extraction for Near and Attenuated Total Reflection Infrared Spectroscopic Analysis.

    PubMed

    Huck, Christian W

    2016-01-01

    A review with more than 100 references on the principles and recent developments in the solid-phase extraction (SPE) prior and for in situ near and attenuated total reflection (ATR) infrared spectroscopic analysis is presented. New materials, chromatographic modalities, experimental setups and configurations are described. Their advantages for fast sample preparation for distinct classes of compounds containing different functional groups in order to enhance selectivity and sensitivity are discussed and compared. This is the first review highlighting both the fundamentals of SPE, near and ATR spectroscopy with a view to real sample applicability and routine analysis. Most of real sample analyses examples are found in environmental research, followed by food- and bioanalysis. In this contribution a comprehensive overview of the most potent SPE-NIR and SPE-ATR approaches is summarized and provided. PMID:27187347

  4. 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

  5. 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.

  6. Nanothermal characterization of amorphous and crystalline phases in chalcogenide thin films with scanning thermal microscopy

    NASA Astrophysics Data System (ADS)

    Bosse, J. L.; Timofeeva, M.; Tovee, P. D.; Robinson, B. J.; Huey, B. D.; Kolosov, O. V.

    2014-10-01

    The thermal properties of amorphous and crystalline phases in chalcogenide phase change materials (PCM) play a key role in device performance for non-volatile random-access memory. Here, we report the nanothermal morphology of amorphous and crystalline phases in laser pulsed GeTe and Ge2Sb2Te5 thin films by scanning thermal microscopy (SThM). By SThM measurements and quantitative finite element analysis simulations of two film thicknesses, the PCM thermal conductivities and thermal boundary conductances between the PCM and SThM probe are independently estimated for the amorphous and crystalline phase of each stoichiometry.

  7. Phase stabilized homodyne of infrared scattering type scanning near-field optical microscopy

    SciTech Connect

    Xu, Xiaoji G.; Gilburd, Leonid; Walker, Gilbert C.

    2014-12-29

    Scattering type scanning near-field optical microscopy (s-SNOM) allows sub diffraction limited spatial resolution. Interferometric homodyne detection in s-SNOM can amplify the signal and extract vibrational responses based on sample absorption. A stable reference phase is required for a high quality homodyne-detected near-field signal. This work presents the development of a phase stabilization mechanism for s-SNOM to provide stable homodyne conditions. The phase stability is found to be better than 0.05 rad for the mid infrared light source. Phase stabilization results in improved near field images and vibrational spectroscopies. Spatial inhomogeneities of the boron nitride nanotubes are measured and compared.

  8. 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

  9. Benzyl alcohol oxidation in supercritical carbon dioxide: spectroscopic insight into phase behaviour and reaction mechanism.

    PubMed

    Caravati, Matteo; Grunwaldt, Jan-Dierk; Baiker, Alfons

    2005-01-21

    Selective oxidation of benzyl alcohol to benzaldehyde with molecular oxygen over an alumina-supported palladium catalyst was performed with high rate at about 95% selectivity in supercritical carbon dioxide. The experiments in a continuous flow fixed-bed reactor showed that the pressure has a strong influence on the reaction rate. A marked increase of the rate (turnover frequency) from 900 h(-1) to 1800 h(-1) was observed when increasing the pressure from 140 to 150 bar. Video monitoring of the bulk fluid phase behavior and the simultaneous investigation by transmission and attenuated total reflection (ATR) infrared spectroscopy at two positions of the view cell showed that the sharp increase in activity is correlated to a transition from a biphasic to a monophasic reaction mixture. In the single phase region, both oxygen and benzyl alcohol are dissolved in the supercritical CO2 phase, which leads to a reduction of the mass transport resistances (both in the external fluid film and in the catalyst pores) and thus to the high reaction rate measured in the catalytic experiments. The phase transition could be effectively and easily monitored by transmission and ATR-IR spectroscopy despite the small concentration of the dense liquid like phase. Deposition of the Pd/Al2O3 catalyst on the ATR-crystal at the bottom of the view cell allowed to gain insight into the chemical changes and mass transfer processes occurring in the solid/liquid interface region during reaction. Analyzing the shift of the upsilon2 bending mode of CO2 gave information on the fluid composition in and outside the catalyst pores. Moreover, the catalytic reaction could be investigated in situ in this spectroscopic batch reactor cell by monitoring simultaneously the reaction progress, the phase behaviour and the catalytic interface. PMID:19785149

  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. High-resolution transmission electron microscopy with an electrostatic Zach phase plate

    NASA Astrophysics Data System (ADS)

    Hettler, S.; Dries, M.; Zeelen, J.; Oster, M.; Schröder, R. R.; Gerthsen, D.

    2016-05-01

    A new method to control lattice-fringe contrast in high-resolution transmission electron microscopy (HRTEM) images by the implementation of a physical phase plate (PP) is proposed. PPs are commonly used in analogy to Zernike PPs in light microscopy to enhance the phase contrast of weak-phase objects with nm-sized features, which often occur in life science applications. Such objects otherwise require strong defocusing, which leads to a degradation of the instrumental resolution and impedes intuitive image interpretation. The successful application of an electrostatic Zach PP in HRTEM is demonstrated by the investigation of single crystalline Si and Ge samples. The influence of the Zach PP on the image formation process is assessed by analyzing the amplitudes of (111) reflections in power spectra which show a cosine-type dependence on the induced phase shift under certain conditions as predicted by theory.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. Time-resolved imaging refractometry of microbicidal films using quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Rinehart, Matthew T.; Drake, Tyler K.; Robles, Francisco E.; Rohan, Lisa C.; Katz, David; Wax, Adam

    2011-12-01

    Quantitative phase microscopy is applied to image temporal changes in the refractive index (RI) distributions of solutions created by microbicidal films undergoing hydration. We present a novel method of using an engineered polydimethylsiloxane structure as a static phase reference to facilitate calibration of the absolute RI across the entire field. We present a study of dynamic structural changes in microbicidal films during hydration and subsequent dissolution. With assumptions about the smoothness of the phase changes induced by these films, we calculate absolute changes in the percentage of film in regions across the field of view.

  20. Phase measurements of erythrocytes affected by metal ions with quantitative interferometric microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Shouyu; Yan, Keding; Shan, Yanke; Xu, Mingfei; Liu, Fei; Xue, Liang

    2015-12-01

    Erythrocyte morphology is an important factor in disease diagnosis, however, traditional setups as microscopes and cytometers cannot provide enough quantitative information of cellular morphology for in-depth statistics and analysis. In order to capture variations of erythrocytes affected by metal ions, quantitative interferometric microscopy (QIM) is applied to monitor their morphology changes. Combined with phase retrieval and cell recognition, erythrocyte phase images, as well as phase area and volume, can be accurately and automatically obtained. The research proves that QIM is an effective tool in cellular observation and measurement.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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)].

  6. Magnetosome size distribution in uncultured rod-shaped bacteria as determined by electron microscopy and electron spectroscopic imaging.

    PubMed

    Lins, U; Farina, M

    1998-09-15

    We report uncultured rod-shaped magnetotactic bacteria from natural waters that biomineralize magnetic crystals in two different size ranges. Electron spectroscopic imaging of whole bacteria deposited over formvar-coated grids permitted a better visualization and measurement of the magnetosomes. All magnetosomes of individual bacteria could be observed by this technique. The magnetosomes formed one large chain, composed of three to four columns of crystals, disposed in parallel to the main axis of the bacteria. The magnetosomes ranged from 19 to 136 nm in length and 14 to 112 nm width. Smaller magnetosomes (less than 80 nm in length) localized mostly in extremities of the bacterial body while larger preferentially localized in the middle part of the cell. Electron spectroscopic diffraction and X-ray microanalysis indicate that both types of magnetosomes contain magnetite (Fe3O4). In projection, most magnetosomes seem to present pseudo-hexagonal morphologies described for magnetite. As the aspect ratios for smaller and larger magnetosomes are different, we suggest that different levels of control on biomineralization of magnetosomes may exist. PMID:9817552

  7. 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

  8. 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.

  9. 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.

  10. Using imaging raman microscopy to explore phase evolution in composite ceramic superconductors.

    SciTech Connect

    Fischer, A. K.; Maroni, V. A.; Wu, K. T.

    1998-09-17

    Raman microspectroscopy and imaging Raman microscopy have proven to be powerful tools for studying the evolution and spatial distribution of chemical phases in the bismuth-based (BSCCO) and thallium-based (TBCCO) families of high-critical-temperature (high- Tc) superconducting ceramics. These techniques have been applied to compressed/sintered powders and silver-clad composite conductors in conjunction with scanning electron microscopy and energy dispersive x-ray spectroscopy. Many important insights have been gained about the identity, size, shape, orientation, and spatial distribution of the various nonsuperconducting secondary phases (NSPS) that form and dissipate during heat treatment of the BSCCO and TBCCO silver-clad composite tapes. The resuIts have aHowed us to determine key mechanistic features that influence the formation of the super- conducting phases as heat treatment progresses, incIuding the location of lead-rich NSPS and the identification of the constituent phases in certain NSP agglomerations that tend to resist dissipation as high-Tc phase formation proceeds to completion.

  11. Intracellular subsurface imaging using a hybrid shear-force feedback/scanning quantitative phase microscopy technique

    NASA Astrophysics Data System (ADS)

    Edward, Kert

    Quantitative phase microscopy (QPM) allows for the imaging of translucent or transparent biological specimens without the need for exogenous contrast agents. This technique is usually applied towards the investigation of simple cells such as red blood cells which are typically enucleated and can be considered to be homogenous. However, most biological cells are nucleated and contain other interesting intracellular organelles. It has been established that the physical characteristics of certain subsurface structures such as the shape and roughness of the nucleus is well correlated with onset and progress of pathological conditions such as cancer. Although the acquired quantitative phase information of biological cells contains surface information as well as coupled subsurface information, the latter has been ignored up until now. A novel scanning quantitative phase imaging system unencumbered by 2pi ambiguities is hereby presented. This system is incorporated into a shear-force feedback scheme which allows for simultaneous phase and topography determination. It will be shown how subsequent image processing of these two data sets allows for the extraction of the subsurface component in the phase data and in vivo cell refractometry studies. Both fabricated samples and biological cells ranging from rat fibroblast cells to malaria infected human erythrocytes were investigated as part of this research. The results correlate quite well with that obtained via other microscopy techniques.

  12. Quantitative phase microscopy using defocusing by means of a spatial light modulator.

    PubMed

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

    2010-03-29

    A new method for recovery the quantitative phase information of microscopic samples is presented. It is based on a spatial light modulator (SLM) and digital image processing as key elements to extract the sample's phase distribution. By displaying a set of lenses with different focal power, the SLM produces a set of defocused images of the input sample at the CCD plane. Such recorded images are then numerically processed to retrieve phase information. This iterative process is based on the wave propagation equation and leads on a complex amplitude image containing information of both amplitude and phase distributions of the input sample diffracted wave front. The proposed configuration is a non-interferometric architecture (conventional transmission imaging mode) where no moving elements are included. Experimental results perfectly correlate with the results obtained by conventional digital holographic microscopy (DHM). PMID:20389696

  13. Single-shot slightly-off-axis interferometry based Hilbert phase microscopy of red blood cells

    PubMed Central

    Xue, Liang; Lai, Jiancheng; Wang, Shouyu; Li, Zhenhua

    2011-01-01

    A slightly-off-axis interferometry based Hilbert phase microscopy (HPM) method is developed to quantitatively obtain the phase distribution. Owing to its single-shot nature and details detection ability, HPM can be used to investigate rapid phenomena that take place in transparent structures such as biological cells. Moreover, the slightly-off-axis interferometry owns higher effective bandwidth and more sensitivity than traditional off-axis interferometry. The proposed method takes advantages of the above techniques to obtain the phase image of the red blood cells and compared with the traditional off-axis interferometry and phase retrieval algorithm based on the FFT. The experimental results show that the proposed method owns fine spatial details and real-time imaging ability. We are sure that the proposed method provides a breakthrough for real-time observing and quantitative analyzing of cells in vivo. PMID:21483620

  14. On the role of inelastic scattering in phase-plate transmission electron microscopy.

    PubMed

    Hettler, Simon; Wagner, Jochen; Dries, Manuel; Oster, Marco; Wacker, Christian; Schröder, Rasmus R; Gerthsen, Dagmar

    2015-08-01

    The phase contrast of Au nanoparticles on amorphous-carbon films with different thicknesses is analyzed using an electrostatic Zach phase plate in a Zeiss 912 Ω transmission electron microscope with in-column energy filter. Specifically, unfiltered and plasmon-filtered phase-plate transmission electron microscopy (PP TEM) images are compared to gain insight in the role of coherence after inelastic scattering processes. A considerable phase-contrast contribution resulting from a combined elastic-inelastic scattering process is found in plasmon-filtered PP TEM images. The contrast reduction compared to unfiltered images mainly originates from zero-order beam broadening caused by the inelastic scattering process. The effect of the sequence of the elastic and inelastic scattering processes is studied by varying the position of the nanoparticles, which can be either located on top or at the bottom of the amorphous-carbon film with respect to the incident electron beam direction. PMID:25879156

  15. Physical phase compensation in digital holographic microscopy by using of electrical tunable lens

    NASA Astrophysics Data System (ADS)

    Qu, Weijuan; Cheng, Chee Yuen; Asundi, Anand

    2013-06-01

    An electrical tunable lens is applied in digital holographic microscopy for physical spherical phase compensation. When different microscope objectives are applied to one digital holographic microscope, the physical spherical phase compensation needs different reference wavefronts. The focal length of the electric tunable lens can be adjusted by applying different voltages. We have measured the morphology changes of the tunable lens under different voltages. According to the measurement, the tunable lens has the capability to change wavefront via changing of the applied voltages. Thus we apply the tunable lens in the digital holographic microscope with multiple microscope objectives to fulfill the physical spherical phase compensation. The measurement results for the tunable lens together with the phase compensation results are presented.

  16. Variable multimodal light microscopy with interference contrast and phase contrast; dark or bright field.

    PubMed

    Piper, T; Piper, J

    2014-07-01

    Using the optical methods described, specimens can be observed with modified multimodal light microscopes based on interference contrast combined with phase contrast, dark- or bright-field illumination. Thus, the particular visual information associated with interference and phase contrast, dark- and bright-field illumination is joined in real-time composite images appearing in enhanced clarity and purified from typical artefacts, which are apparent in standard phase contrast and dark-field illumination. In particular, haloing and shade-off are absent or significantly reduced as well as marginal blooming and scattering. The background brightness and thus the range of contrast can be continuously modulated and variable transitions can be achieved between interference contrast and complementary illumination techniques. The methods reported should be of general interest for all disciplines using phase and interference contrast microscopy, especially in biology and medicine, and also in material sciences when implemented in vertical illuminators. PMID:24832212

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

    NASA Astrophysics Data System (ADS)

    Glaeser, Robert M.

    2013-11-01

    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.

  18. 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

  19. 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

    2014-01-01

    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

  20. Deconvolution approach for 3D scanning microscopy with helical phase engineering.

    PubMed

    Roider, Clemens; Heintzmann, Rainer; Piestun, Rafael; Jesacher, Alexander

    2016-07-11

    RESCH (refocusing after scanning using helical phase engineering) microscopy is a scanning technique using engineered point spread functions which provides volumetric information. We present a strategy for processing the collected raw data with a multi-view maximum likelihood deconvolution algorithm, which inherently comprises the resolution gain of pixel-reassignment microscopy. The method, which we term MD-RESCH (for multi-view deconvolved RESCH), achieves in our current implementation a 20% resolution advantage along all three axes compared to RESCH and confocal microscopy. Along the axial direction, the resolution is comparable to that of image scanning microscopy. However, because the method inherently reconstructs a volume from a single 2D scan, a significantly higher optical sectioning becomes directly visible to the user, which would otherwise require collecting multiple 2D scans taken at a series of axial positions. Further, we introduce the use of a single-helical detection PSF to obtain an increased post-acquisition refocusing range. We present data from numerical simulations as well as experiments to confirm the validity of our approach. PMID:27410820

  1. 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.

  2. 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.

  3. Sulfur doping of diamond films: Spectroscopic, electronic, and gas-phase studies

    NASA Astrophysics Data System (ADS)

    Petherbridge, James R.; May, Paul W.; Fuge, Gareth M.; Robertson, Giles F.; Rosser, Keith N.; Ashfold, Michael N. R.

    2002-03-01

    Chemical vapor deposition (CVD) has been used to grow sulfur doped diamond films on undoped Si and single crystal HPHT diamond as substrates, using a 1% CH4/H2 gas mixture with various levels of H2S addition (100-5000 ppm), using both microwave (MW) plasma enhanced CVD and hot filament (HF) CVD. The two deposition techniques yield very different results. HFCVD produces diamond films containing only trace amounts of S (as analyzed by x-ray photoelectron spectroscopy), the film crystallinity is virtually unaffected by gas phase H2S concentration, and the films remain highly resistive. In contrast, MWCVD produces diamond films with S incorporated at levels of up to 0.2%, and the amount of S incorporation is directly proportional to the H2S concentration in the gas phase. Secondary electron microscopy observations show that the crystal quality of these films reduces with increasing S incorporation. Four point probe measurements gave the room temperature resistivities of these S-doped and MW grown films as ˜200 Ω cm, which makes them ˜3 times more conductive than undoped diamond grown under similar conditions. Molecular beam mass spectrometry has been used to measure simultaneously the concentrations of the dominant gas phase species present during growth, for H2S doping levels (1000-10 000 ppm in the gas phase) in 1% CH4/H2 mixtures, and for 1% CS2/H2 gas mixtures, for both MW and HF activation. CS2 and CS have both been detected in significant concentrations in all of the MW plasmas that yield S-doped diamond films, whereas CS was not detected in the gas phase during HF growth. This suggests that CS may be an important intermediary facilitating S incorporation into diamond. Furthermore, deposition of yellow S was observed on the cold chamber walls when using H2S concentrations >5000 ppm in the MW system, but very little S deposition was observed for the HF system under similar conditions. All of these results are rationalized by a model of the important gas phase

  4. Spectral-domain optical coherence phase microscopy for label-free multiplexed protein microarray assay

    PubMed Central

    Joo, Chulmin; Özkumur, Emre; Ünlü, M. Selim; de Boer, Johannes F.

    2009-01-01

    Quantitative measurement of affinities and kinetics of various biomolecular interactions such as protein-protein, protein-DNA and receptor-ligand is central to our understanding of basic molecular and cellular functions and is useful for therapeutic evaluation. Here, we describe a laser-scanning quantitative imaging method, referred to as spectral-domain optical coherence phase microscopy, as an optical platform for label-free detection of biomolecular interactions. The instrument is based on a confocal interferometric microscope that enables depth-resolved quantitative phase measurements on sensor surface with high spatial resolution and phase stability. We demonstrate picogram per square millimeter surface mass sensitivity, and show its sensing capability by presenting static and dynamic detection of multiplexed protein microarray as immobilized antigens capture their corresponding antibodies. PMID:19674885

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

    NASA Astrophysics Data System (ADS)

    Wahlen-Strothman, Jacob; Pan, Zhen Wen; Manning, Lane; Furis, Madalina; Chu, Kelvin

    2011-03-01

    Tetraphenylporphyrin (TPP) is a synthetic heterocyclic compound that serves as a model system for heme proteins and cytochromes. TPP can accomodate 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 the heme protoporphyrin IX analogue tetra-phenyl porphyrin, complexed with Zn and Mn, deposited through a capillary pen technique that produces 100um to 1 mm sized grains. Our novel experimental setup measures the UV/VIS, linear dichroism and magnetic circular dichorism simultaneously, incorporates a photoelastic modulator and a microscopy superconducting magnet for high-field (5T) measurements. 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. This work supported by NSF DMR-0821268, DUE-0942562 and EPS-0701410.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. Self interference digital holographic microscopy approach for inspection of technical and biological phase specimens

    NASA Astrophysics Data System (ADS)

    Kemper, Björn; Schlichthaber, Frank; Vollmer, Angelika; Ketelhut, Steffi; Przibilla, Sabine; von Bally, Gert

    2011-05-01

    Quantitative holographic phase contrast imaging enables high-resolution inspection of reflective surfaces and technical phase specimen as well as the minimally invasive analysis of living cells. However, a drawback of many experimental arrangements is the requirement for a separate reference wave which results in a phase stability decrease and the demand for a precise adjustment of the intensity ratio between object and reference wave. Thus, a self interference digital holographic microscopy (DHM) approach was explored which only requires a single object illumination wave. Due to the Michelson interferometer design of the proposed setup two wave fronts with an almost identical curvature are superimposed. This results in a nearly ideal pattern of spatial off-axis carrier fringes and a constant interferogram contrast in the hologram plane. Moreover, the hologram evaluation with spatial phase shifting reconstruction algorithms and Fourier transformation-based spatial filtering methods as well as the integration of DHM in common research microscopes is simplified. Furthermore, the use of laser light sources with a short coherence length is enabled. The applicability of the proposed self interference principle is illustrated by data from the analysis of technical and biological phase specimens. The obtained results demonstrate that the method prospects to be a versatile tool for quantitative phase contrast imaging.

  11. Single-shot and phase-shifting digital holographic microscopy using a 2-D grating.

    PubMed

    Yang, Taeseok Daniel; Kim, Hyung-Jin; Lee, Kyoung J; Kim, Beop-Min; Choi, Youngwoon

    2016-05-01

    We demonstrate digital holographic microscopy that, while being based on phase-shifting interferometry, is capable of single-shot measurements. A two-dimensional (2-D) diffraction grating placed in a Fourier plane of a standard in-line holographic phase microscope generates multiple copies of a sample image on a camera sensor. The identical image copies are spatially separated with different overall phase shifts according to the diffraction orders. The overall phase shifts are adjusted by controlling the lateral position of the grating. These phase shifts are then set to be multiples of π/2. Interferograms composed of four image copies combined with a parallel reference beam are acquired in a single shot. The interferograms are processed through a phase-shifting algorithm to produce a single complex image. By taking advantage of the higher sampling capacity of the in-line holography, we can increase the imaging information density by a factor of 3 without compromising the imaging acquisition speed. PMID:27137562

  12. 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.

  13. 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

  14. Spectroscopic microscopy as a powerful tool for the assessment of dermal exposure to pesticides and environmental pollutants

    SciTech Connect

    Saleh, M.A.; Dary, C.; Blancato, J.N.

    1995-12-01

    FTIR Microscopy and Computerized Video Optical Imaging in Ultraviolet Induced Visible fluorescence Techniques were used to study the behavior of malathion and deltamethrin through die skin layers of rats exposed to dermal doses of the individual insecticide. The technique was also shown to be useful for monitoring penetration of pesticide through protective clothing and therefore may serve as a straight forward direct tool for assessing human dermal exposure to pesticides. One advantage of this techniques is the ability to detect both parent compounds and their metabolites by scanning for the desired wave numbers in the IR spectra or by controlling excitation and emission wavelengths. The technique was also compared to microscopic autoradiography where the skin was treated with radioactive malathion and distribution of the radioactivity was located by gel X Ray film on the microscope slide.

  15. 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

  16. 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.

  17. 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.

  18. Nanoscale nuclear architecture for cancer diagnosis by spatial-domain low-coherence quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Pin; Bista, Rajan K.; Khalbuss, Walid E.; Qiu, Wei; Staton, Kevin D.; Zhang, Lin; Brentnall, Teresa A.; Brand, Randall E.; Liu, Yang

    2011-03-01

    Alterations in nuclear architecture are the hallmark diagnostic characteristic of cancer cells. In this work, we show that the nuclear architectural characteristics quantified by spatial-domain low-coherence quantitative phase microscopy (SL-QPM), is more sensitive for the identification of cancer cells than conventional cytopathology. We demonstrated the importance of nuclear architectural characteristics in both an animal model of intestinal carcinogenesis - APC/Min mouse model and human cytology specimens with colorectal cancer by identifying cancer from cytologically noncancerous appearing cells. The determination of nanoscale nuclear architecture using this simple and practical optical instrument is a significant advance towards cancer diagnosis.

  19. 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.

  20. 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.

  1. 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

  2. In operando tracking phase transformation evolution of lithium iron phosphate with hard X-ray microscopy.

    PubMed

    Wang, Jiajun; Chen-Wiegart, Yu-chen Karen; Wang, Jun

    2014-01-01

    The delithiation reaction in lithium ion batteries is often accompanied by an electrochemically driven phase transformation process. Tracking the phase transformation process at nanoscale resolution during battery operation provides invaluable information for tailoring the kinetic barrier to optimize the physical and electrochemical properties of battery materials. Here, using hard X-ray microscopy--which offers nanoscale resolution and deep penetration of the material, and takes advantage of the elemental and chemical sensitivity--we develop an in operando approach to track the dynamic phase transformation process in olivine-type lithium iron phosphate at two size scales: a multiple-particle scale to reveal a rate-dependent intercalation pathway through the entire electrode and a single-particle scale to disclose the intraparticle two-phase coexistence mechanism. These findings uncover the underlying two-phase mechanism on the intraparticle scale and the inhomogeneous charge distribution on the multiple-particle scale. This in operando approach opens up unique opportunities for advancing high-performance energy materials. PMID:25087693

  3. Phase noise induced due to amplitude fluctuations in dynamic force microscopy

    NASA Astrophysics Data System (ADS)

    Rast, S.; Gysin, U.; Meyer, E.

    2009-02-01

    In dynamic force microscopy, the force sensor is driven on its resonance frequency and the amplitude of the cantilever is sustained at a constant value. The amplitude typically ranges between 0.1 and 30 nm. If a large amplitude is set, the cantilever tip senses both long-range and short-range interaction forces provided that the tip is close to the sample surface. The short-range interactions are decisive for the atomic contrast in atomic force microscopy (AFM) images. They can be separated from the long-range interactions by setting an amplitude which encompasses the typical range of the interaction force, i.e., the subangstrom regime for van der Waals contribution. It is distinctive for cantilevers operated at small driving amplitudes that the cantilever deflection can be considered as a sinusoidal signal superimposed with a quasimonochromatic random signal originating from fluctuations. If one measures experimentally the standard deviation of the phase σφ of the signal with respect to a monochromatic reference signal, a universal relationship between the standard deviation of the phase σφ and the cantilever amplitude x0 is found. The smaller the ratio of rms amplitude of the sinusoidal signal and the rms value of random signal is, the larger the phase fluctuations are. Phase fluctuations are of importance for measurements at small amplitudes, since they determine the limit of phase-sensitive measurements or the lateral imaging resolution in the so-called pendulum mode of AFM operation. In this paper we develop a heuristic model, which provides an analytical formula for the probability density of phase noise of a sinusoidal signal superimposed by a quasimonochromatic one with respect to a reference oscillator. The variance of the phase noise can be deduced from the distribution functions. The suggested model is verified experimentally and is compared with theoretical predictions. The amplitude-dependent phase fluctuations are a powerful tool to determine the

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. Phase II of the Small Main-Belt Asteroid Spectroscopic Survey. A Feature-Based Taxonomy

    NASA Astrophysics Data System (ADS)

    Bus, Schelte J.; Binzel, Richard P.

    2002-07-01

    The second phase of the Small Main-belt Asteroid Spectroscopic Survey (SMASSII) produced an internally consistent set of visible-wavelength charge-coupled device (CCD) spectra for 1447 asteroids (Bus and Binzel 2002, Icarus, ). These data provide a basis for developing a new asteroid taxonomy that utilizes more of the information contained in CCD spectra. Here we construct a classification system that builds on the robust framework provided by existing asteroid taxonomies. In particular, we define three major groupings (the S-, C-, and X-complexes) that adhere to the classical definitions of the S-, C-, and X-type asteroids. A total of 26 classes are defined, based on the presence or absence of specific spectral features. Definitions and boundary parameters are provided for each class, allowing new spectral observations to be placed in this system. Of these 26 classes, 12 bear familiar single-letter designations that follow previous conventions: A, B, C, D, K, O, Q, R, S, T, V, and X. A new L-class is introduced to describe 35 objects with spectra having a steep UV slope shortward of 0.75 μm, but which are relatively flat longward of 0.75 μm. Asteroids with intermediate spectral characteristics are assigned multiletter designations: Cb, Cg, Cgh, Ch, Ld, Sa, Sk, Sl, Sq, Sr, Xc, Xe, and Xk. Members of the Cgh- and Ch-classes have spectra containing a 0.7-μm feature that is generally attributed to hydration. Although previously considered featureless, CCD observations reveal distinct features of varying strengths in the spectra of asteroids in the X-complex, thus allowing the Xc-, Xe-, and Xk-classes to be established. Most notably, the spectra of Xe-type asteroids contain an absorption feature centered near 0.49 μm that may be associated with troilite. Several new members are identified for previously unique or sparsely populated classes: 12 A-types, 3 O-types, and 3 R-types. Q-types are common within the near-Earth asteroid population but remain unobserved in

  11. 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.

  12. 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

  13. Tracking of migrating cells under phase-contrast video microscopy with combined mean-shift processes.

    PubMed

    Debeir, O; Van Ham, P; Kiss, R; Decaestecker, C

    2005-06-01

    In this paper, we propose a combination of mean-shift-based tracking processes to establish migrating cell trajectories through in vitro phase-contrast video microscopy. After a recapitulation on how the mean-shift algorithm permits efficient object tracking we describe the proposed extension and apply it to the in vitro cell tracking problem. In this application, the cells are unmarked (i.e., no fluorescent probe is used) and are observed under classical phase-contrast microscopy. By introducing an adaptive combination of several kernels, we address several problems such as variations in size and shape of the tracked objects (e.g., those occurring in the case of cell membrane extensions), the presence of incomplete (or noncontrasted) object boundaries, partially overlapping objects and object splitting (in the case of cell divisions or mitoses). Comparing the tracking results automatically obtained to those generated manually by a human expert, we tested the stability of the different algorithm parameters and their effects on the tracking results. We also show how the method is resistant to a decrease in image resolution and accidental defocusing (which may occur during long experiments, e.g., dozens of hours). Finally, we applied our methodology on cancer cell tracking and showed that cytochalasin-D significantly inhibits cell motility. PMID:15957594

  14. Deciphering complex, functional structures with synchrotron-based absorption and phase contrast tomographic microscopy

    NASA Astrophysics Data System (ADS)

    Stampanoni, M.; Reichold, J.; Weber, B.; Haberthür, D.; Schittny, J.; Eller, J.; Büchi, F. N.; Marone, F.

    2010-09-01

    Nowadays, thanks to the high brilliance available at modern, third generation synchrotron facilities and recent developments in detector technology, it is possible to record volumetric information at the micrometer scale within few minutes. High signal-to-noise ratio, quantitative information on very complex structures like the brain micro vessel architecture, lung airways or fuel cells can be obtained thanks to the combination of dedicated sample preparation protocols, in-situ acquisition schemes and cutting-edge imaging analysis instruments. In this work we report on recent experiments carried out at the TOMCAT beamline of the Swiss Light Source [1] where synchrotron-based tomographic microscopy has been successfully used to obtain fundamental information on preliminary models for cerebral fluid flow [2], to provide an accurate mesh for 3D finite-element simulation of the alveolar structure of the pulmonary acinus [3] and to investigate the complex functional mechanism of fuel cells [4]. Further, we introduce preliminary results on the combination of absorption and phase contrast microscopy for the visualization of high-Z nanoparticles in soft tissues, a fundamental information when designing modern drug delivery systems [5]. As an outlook we briefly discuss the new possibilities offered by high sensitivity, high resolution grating interferomtery as well as Zernike Phase contrast nanotomography [6].

  15. 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

  16. 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

  17. Microstructure of massively transformed {gamma}-TiAl phase studied by high-resolution electron microscopy

    SciTech Connect

    Abe, E.; Kumagai, T.; Kajiwara, S.; Nakamura, M.

    1997-12-31

    A microstructure of the massively transformed {gamma}-TiAl ({gamma}{sub m}) phase in a Ti-48at.%Al alloy, which was heat treated in the high-temperature {alpha}-Ti (disordered hcp) single phase field (1,683 K), followed by ice water quenching, has been examined using high-resolution electron microscopy. The characteristic features of the microstructure originated from the {alpha}{yields}{gamma} massive transformation have been clarified in detail, which are as follows. (1) Extremely thin hcp plates (about 0.8--2nm in thickness), which are considered to be a retained {alpha} phase, are found to exist in the {gamma}{sub m} phase. (2) Twin boundaries are found to be not flat interfaces, that is, twin interfaces are not on the exact (111) mirror plane. This situation is attributed to the existence of a number of partial dislocations at the twin boundaries. (3) Antiphase relationship between the regions either side of the thin rotated domain wall is confirmed. The validity of this situation is explained by assuming that the thin rotated domain wall has been grown from a simple antiphase domain boundary. On the basis of these facts, mechanism of the {alpha}{yields}{gamma} massive transformation has been discussed.

  18. 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.

  19. Early responses of human cancer cells upon photodynamic treatment monitored by laser phase microscopy

    NASA Astrophysics Data System (ADS)

    Roelofs, Theo A.; Graschew, Georgi; Perevedentseva, Elena V.; Rakowsky, Stefan; Dressler, Cathrin; Beuthan, Juergen; Schlag, Peter M.

    2001-04-01

    Photodynamic treatment of cancer cells is known to eventually cause cell death in most cases. The precise pathways and the time course seem to vary among different cell types and modes of photodynamic treatment. In this contribution, the focus was put on the responses of human colon carcinoma cells HCT-116 within the first 15 minutes after laser irradiation in the presence of Photofrin« II (PII). To monitor the cell response in this early time period laser phase microscopic imaging was used, a method sensitive to changes in overall cell shape and intracellular structures, mediated by changes in the local refractive index. Laser irradiation of cells loaded with PII induced a significant reduction of the phase shifts, which probably reflects the induced damage to the different cellular membrane structures. The data suggest that even within the first 30 s after the onset of laser illumination, a significant reduction of the phase shifts can be detected. These results underline that laser phase microscopy is a suitable diagnostic tool for cellular research, also in the early time domain.

  20. 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

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

    PubMed Central

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

    2015-01-01

    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

  2. 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.

  3. Local orbital angular momentum revealed by spiral-phase-plate imaging in transmission-electron microscopy

    NASA Astrophysics Data System (ADS)

    Juchtmans, Roeland; Verbeeck, Jo

    2016-02-01

    The orbital angular momentum (OAM) of light and matter waves is a parameter that has been getting increasingly more attention over the past couple of years. Beams with a well-defined OAM, the so-called vortex beams, are applied already in, e.g., telecommunication, astrophysics, nanomanipulation, and chiral measurements in optics and electron microscopy. Also, the OAM of a wave induced by the interaction with a sample has attracted a lot of interest. In all these experiments it is crucial to measure the exact (local) OAM content of the wave, whether it is an incoming vortex beam or an exit wave after interacting with a sample. In this work we investigate the use of spiral phase plates (SPPs) as an alternative to the programmable phase plates used in optics to measure OAM. We derive analytically how these can be used to study the local OAM components of any wave function. By means of numerical simulations we illustrate how the OAM of a pure vortex beam can be measured. We also look at a sum of misaligned vortex beams and show how, by using SPPs, the position and the OAM of each individual beam can be detected. Finally, we look at the OAM induced by a magnetic dipole on a free-electron wave and show how the SPP can be used to localize the magnetic poles and measure their "magnetic charge." Although our findings can be applied to study the OAM of any wave function, our findings are of particular interest for electron microscopy where versatile programmable phase plates do not yet exist.

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. Investigations of the ultrafast laser induced melt dynamics by means of transient quantitative phase microscopy (TQPm)

    NASA Astrophysics Data System (ADS)

    Mingareev, Ilya; Horn, Alexander

    2008-05-01

    Modifications of bulk aluminum irradiated well above ablation threshold (F < 300 J.cm-2) have been investigated in situ by means of shadowgraphy and transient quantitative phase microscopy (TQPm) using ultrafast laser radiation (tp=80 fs, λ=800 nm). This novel pump-probe technique enables quantitative time-resolved measurements of object's properties, e.g. dimensions of melt droplets and layer thickness or transient refractive index changes. A series of time-resolved phase images of vaporized material and/or melt, which are induced by n=1..8 pulses on an aluminum target, are obtained using TQPm. Dynamics and characteristics of melting, dependence of the ablated material volume on process parameters and thereby induced structural modifications have been studied. An increase of material ejection rate is observed at delay time of approximately τ=300 ns and τ>800 ns after the incident pulse. Transient refractive index modifications have been investigated in technical glass (Schott D263) by means of TQPm. By using high-repetition rate ultra-short pulsed laser radiation (tp=400 fs, λ=1045 nm, frep=1 MHz) focused by a microscope objective (w0 ~ 4 μm) heat accumulation and thereby glass melting as well as welding is enabled. Transient optical phase variation has been measured up to τ=2.1 μs after the incident pulse and can be attributed to the generation of free charge carriers and compression forces inside glass.

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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.

  16. 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

  17. Inclusion interaction of chloramphenicol and heptakis (2,6-di- O-methyl)-β-cyclodextrin: Phase solubility and spectroscopic methods

    NASA Astrophysics Data System (ADS)

    Shi, Jie-Hua; Zhou, Ya-fang

    2011-12-01

    The inclusion interaction between chloramphenicol and heptakis (2,6-di- O-methyl)-β-cyclodextrin (DMBCD) had been investigated by phase solubility and spectroscopic methods such as UV-vis spectroscopy, circular dichroism, Fourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance spectroscopy ( 1H NMR) as well as 2D-ROESY spectra. Phase solubility analysis showed A L-type diagram with DMBCD, which suggested the formation of 1:1 inclusion complex of DMBCD with chloramphenicol. The estimated stability constant ( Ks) of the inclusion complex of chloramphenicol with DMBCD is 493 M -1 at 293 K. The solubility enhancement of chloramphenicol in the presence of DMBCD is stronger than that in the presence of β-CD, HP-β-CD and M-β-CD. The results obtained by spectroscopic methods showed that the nitrophenyl moiety of chloramphenicol is deeply inserted into inner cavity of DMBCD from the narrow rim of DMBCD, which the inclusion model of chloramphenicol with DMBCD differs from that with β-CD.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. Oxidation of β-Zr and related phases in Zr Nb alloys: an electron microscopy investigation

    NASA Astrophysics Data System (ADS)

    Lin, Y. P.; Woo, O. T.

    2000-01-01

    The oxidation of the metastable β-Zr phase in Zr-Nb alloys, primarily Zr-2.5Nb, in 673 K steam or in lithiated water at 583 K, was investigated using electron microscopy and microanalyses. In the SEM, oxidised β-Zr regions in the Zr-2.5Nb alloy were imaged via a field effect contrast mechanism. In the TEM, microanalyses consistently showed the presence of Nb associated with the oxidised β-regions in suitably prepared samples. The β-Zr was found to form a Nb 2Zr x-2O 2x+1 oxide, while the β-Nb exhibited delayed oxidation with respect to α-Zr, forming a metallic sub-oxide initially and becoming amorphous when oxidised. For the partially decomposed β-Zr, the ω-phase was found to form monoclinic ZrO 2, while the Nb-enriched β-Zr followed the behaviour of either β-Zr or β-Nb depending on the Nb concentration.

  3. Study on the interaction between pelargonidin-3-O-glucoside and bovine serum albumin using spectroscopic, transmission electron microscopy and molecular modeling techniques.

    PubMed

    Li, Shu; Tang, Lin; Bi, Hongna

    2016-03-01

    The aim of this study is to evaluate the binding behavior between pelargonidin-3-O-glucoside (P3G) and bovine serum albumin (BSA) using multi-spectroscopic, transmission electron microscopy (TEM) and molecular docking methods under physiological conditions. Fluorescence spectroscopy and time-resolved fluorescence showed that the fluorescence of BSA could be quenched remarkably by P3G via a static quenching mechanism, and there is a single class of binding site on BSA. In addition, the thermodynamic functions ΔH and ΔS were -21.69 kJ/mol and 24.46 J/mol/K, indicating that an electrostatic interaction was a main acting force. The distance between BSA and P3G was 2.74 nm according to Förster's theory, illustrating that energy transfer occurred. In addition, the secondary structure of BSA changed with a decrease in the α-helix content from 66.2% to 64.0% as seen using synchronous fluorescence, UV/vis, circular dichroism and Fourier transform infrared spectroscopies, whereas TEM images showed that P3G led to BSA aggregation and fibrillation. Furthermore, site marker competitive experiments and molecular docking indicated that P3G could bind with subdomain IIA of BSA. The calculated results of the equilibrium fraction showed that the concentration of free P3G in plasma was high enough to be stored and transported from the circulatory system to its target sites to provide therapeutic effects. PMID:26249529

  4. 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

  5. Polymorphic phase behavior of lysophosphatidylethanolamine dispersions. A thermodynamic and spectroscopic characterization.

    PubMed Central

    Slater, J L; Huang, C H; Adams, R G; Levin, I W

    1989-01-01

    We have investigated the phase behavior of aqueous dispersions of a series of synthetic lysophosphatidylethanolamines as a function of the acyl chain length. Lysophosphatidylethanolamines exhibit phase polymorphism encompassing a well-ordered crystalline phase which may arise either from a metastable interdigitated lamellar gel phase or a metastable micellar phase. The time course of interconversion between these various phases have been outlined by observing the low temperature incubation time dependence of the calorimetric thermograms. We have determined differences in structure of these phases by Raman spectroscopy and 31P nuclear magnetic resonance spectroscopy. It appears that a principal contribution to this polymorphic phase behavior lies in the nature of headgroup hydration and headgroup-headgroup interactions. PMID:2775827

  6. Context based mixture model for cell phase identification in automated fluorescence microscopy

    PubMed Central

    Wang, Meng; Zhou, Xiaobo; King, Randy W; Wong, Stephen TC

    2007-01-01

    Background Automated identification of cell cycle phases of individual live cells in a large population captured via automated fluorescence microscopy technique is important for cancer drug discovery and cell cycle studies. Time-lapse fluorescence microscopy images provide an important method to study the cell cycle process under different conditions of perturbation. Existing methods are limited in dealing with such time-lapse data sets while manual analysis is not feasible. This paper presents statistical data analysis and statistical pattern recognition to perform this task. Results The data is generated from Hela H2B GFP cells imaged during a 2-day period with images acquired 15 minutes apart using an automated time-lapse fluorescence microscopy. The patterns are described with four kinds of features, including twelve general features, Haralick texture features, Zernike moment features, and wavelet features. To generate a new set of features with more discriminate power, the commonly used feature reduction techniques are used, which include Principle Component Analysis (PCA), Linear Discriminant Analysis (LDA), Maximum Margin Criterion (MMC), Stepwise Discriminate Analysis based Feature Selection (SDAFS), and Genetic Algorithm based Feature Selection (GAFS). Then, we propose a Context Based Mixture Model (CBMM) for dealing with the time-series cell sequence information and compare it to other traditional classifiers: Support Vector Machine (SVM), Neural Network (NN), and K-Nearest Neighbor (KNN). Being a standard practice in machine learning, we systematically compare the performance of a number of common feature reduction techniques and classifiers to select an optimal combination of a feature reduction technique and a classifier. A cellular database containing 100 manually labelled subsequence is built for evaluating the performance of the classifiers. The generalization error is estimated using the cross validation technique. The experimental results show

  7. 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.

  8. Characterization of connective tissue progenitors through phase contrast and multicolor fluorescence time-lapse microscopy

    NASA Astrophysics Data System (ADS)

    Kwee, Edward; Powell, Kimerly; Muschler, George

    2015-03-01

    Connective tissue progenitors (CTPs) are defined as the heterogeneous population of tissue resident stem and progenitor cells capable of proliferating and differentiating into connective tissue phenotypes. The prevalence and variation in clonal progeny of CTPs can be characterized using a colony formation assay. However, colony assays do not directly assess the characteristics of the colony founding CTP. We developed a large field of view, time lapse microscopy system with phase contrast and fluorescence capabilities that enables tracking from seeding through colony formation. Cells derived from the trabecular surface of bone were prepared and seeded in an Ibidi-Ph+ chamber slide. Phase contrast images of the slide were obtained every hour using a DMI6000 Leica microscope, 10X objective, and Retiga 2000R camera. Cells were stained using fluorescent antibodies for multiple markers at the time of plating to determine marker expression on seeded cells and re-stained to determine expression on their progeny. Colonies were identified and characterized using automated image processing and quantitative analysis methods. Following colony identification, the time lapse was reversed to identify and characterize the colony founding CTP according to morphology and marker expression. As a representative example, a CD73+/CD90-/CD105- and a CD73+/CD90+/CD105- CTP resulted in a colony with an area of 3720826 microns2 and percent area expression of 2.98%, 3.62%, and 1.13% for CD73, CD90, and CD105, respectively. This method can be used to study CTPs and other stem and progenitor cell populations to benefit point-of-care methods for assay and isolation in cell based therapies.

  9. Phase stability and atom probe field ion microscopy of type 308 cre stainless steel weld metal

    NASA Astrophysics Data System (ADS)

    Babu, S. S.; David, S. A.; Vitek, J. M.; Miller, M. K.

    1996-03-01

    Improvement in high-temperature creep-rupture properties of type 308 stainless steel welds due to the controlled addition of boron is related to microstructural evolution during welding and thermal phase stability at creep service temperatures. The microstructure of boron-containing type 308 austenitic stainless steel welds, in the as-welded state, consisted of 8 to 10 pct ferrite in an austenite matrix. Atom probe field ion microscopy studies revealed segregation of boron and carbon to ferriteaustenite boundaries in the as-welded state; the segregation level was less than one monolayer coverage. On aging at 923 K for 100 hours, M23C6 carbides precipitated at ferrite-austenite boundaries. On further aging at 923 K for 1000 hours, the ferrite transformed into σ phase. Similar microstructural evolution was observed in a type 308 stainless steel weld without boron addition. The volume fractions of M23C6 carbides were identical in boron-containing and boron-free welds. Atom probe results from the welds with boron addition in the aged condition showed that the boron dissolved in the M23C6 carbides. However, lattice parameter analysis showed no apparent difference in the extracted carbides from the welds with and without boron. Creep property improvement due to boron addition could not be related to any change in the volume fraction of carbides. However, the results suggest that the incorporation of boron into M23C6 carbides may reduce the tendency for cavity formation along the M23C6 carbide-austenite boundaries and hence improve the resistance to creep fracture. The observed microstructural evolution in welds is consistent with thermodynamic calculations by THERMOCALC software.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. USE OF IMMUNOFLUORESCENCE AND PHASE-CONTRAST MICROSCOPY FOR DETECTION AND IDENTIFICATION OF 'GIARDIA' CYSTS IN WATER SAMPLES

    EPA Science Inventory

    A method was developed in which indirect immunofluorescence and phase-contrast microscopy are used for rapid detection and identification of Giardia cysts in raw and finished water supplies. When anti-Giardia cyst antiserum and fluorescein conjugate were applied to known Giardia ...

  15. 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.

  16. 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

    2014-01-01

    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

  17. Spectroscopic studies of kinetically trapped conformations in the gas phase: the case of triply protonated bradykinin.

    PubMed

    Voronina, Liudmila; Rizzo, Thomas R

    2015-10-21

    Understanding the relation between the gas-phase structure of biological molecules and their solution-phase structure is important when attempting to use gas-phase techniques to address biologically relevant questions. Directly after electrospray ionization, molecules can be kinetically trapped in a state that retains some "memory" of its conformation in solution and is separated from the lowest-energy gas-phase structure by barriers on the potential energy surface. In order to identify and characterize kinetically trapped structures, we have explored the conformational space of triply protonated bradykinin in the gas phase by combining field-asymmetric ion mobility spectrometry (FAIMS) with cold ion spectroscopy. We isolate three distinct conformational families and characterize them by recording their UV-photofragment spectra and vibrational spectra. Annealing of the initial conformational distribution produced by electrospray reveals that one of the conformational families is kinetically trapped, while two others are stable, gas-phase structures. We compare our results to previously published results obtained using drift-tube ion mobility spectrometry (IMS) and propose a correspondence between the conformational families separated by FAIMS and those by IMS. PMID:25940085

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. Graphene Near-Degenerate Four-Wave Mixing for Phase Characterization of Broadband Pulses in Ultrafast Microscopy.

    PubMed

    Ciesielski, Richard; Comin, Alberto; Handloser, Matthias; Donkers, Kevin; Piredda, Giovanni; Lombardo, Antonio; Ferrari, Andrea C; Hartschuh, Achim

    2015-08-12

    We investigate near-degenerate four-wave mixing in graphene using femtosecond laser pulse shaping microscopy. Intense near-degenerate four-wave mixing signals on either side of the exciting laser spectrum are controlled by amplitude and phase shaping. Quantitative signal modeling for the input pulse parameters shows a spectrally flat phase response of the near-degenerate four-wave mixing due to the linear dispersion of the massless Dirac Fermions in graphene. Exploiting these properties we demonstrate that graphene is uniquely suited for the intrafocus phase characterization and compression of broadband laser pulses, circumventing disadvantages of common methods utilizing second or third harmonic light. PMID:26121487

  3. 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.

  4. 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.

  5. Spectroscopic Study of the Effects of Pressure Media on High-Pressure Phase Transitions in Natrolite

    SciTech Connect

    D Liu; W Lei; Z Liu; Y Lee

    2011-12-31

    Structural phase transitions in natrolite have been investigated as a function of pressure and different hydrostatic media using micro-Raman scattering and synchrotron infrared (IR) spectroscopy. Natrolite undergoes two reversible phase transitions at 0.86 and 1.53 GPa under pure water pressure medium. These phase transitions are characterized by the changes in the vibrational frequencies of four- and eight-membered rings related to the variations in the bridging T-O-T angles and the geometry of the elliptical eight-ring channels under pressure. Concomitant to the changes in the framework vibrational modes, the number of the O-H stretching vibrational modes of natrolite changes as a result of the rearrangements of the hydrogen bonds in the channels caused by a successive increase in the hydration level under hydrostatic pressure. Similar phase transitions were also observed at relatively higher pressures (1.13 and 1.59 GPa) under alcohol-water pressure medium. Furthermore, no phase transition was found up to 2.52 GPa if a lower volume ratio of the alcohol-water to natrolite was employed. This indicates that the water content in the pressure media plays a crucial role in triggering the pressure-induced phase transitions in natrolite. In addition, the average of the mode Grueneisen parameters is calculated to be about 0.6, while the thermodynamic Grueneisen parameter is found to be 1.33. This might be attributed to the contrast in the rigidity between the TO{sub 4} tetrahedral primary building units and other flexible secondary building units in the natrolite framework upon compression and subsequent water insertion.

  6. Serpentines, talc, chlorites, and their high-pressure phase transitions: a Raman spectroscopic study

    NASA Astrophysics Data System (ADS)

    Reynard, Bruno; Bezacier, Lucile; Caracas, Razvan

    2015-09-01

    Raman spectra of magnesian phyllosilicates belonging to the serpentine, talc, and chlorite groups have been obtained at ambient conditions, and at high pressures and up to 200 °C in order to study high-pressure transformations in the 10 GPa range. The complex and distinct Raman spectra of these minerals allow straightforward identification, which may otherwise be difficult from optical microscopy. High-pressure measurements are in good agreement with DFT calculations for talc and lizardite. Pressure-induced displacive modifications are identified in lizardite and antigorite serpentines, and in chlorite at ~4, 7 and 8 GPa, respectively, while talc shows no transition up to ~11 GPa. At high temperature, the high-pressure distortions of serpentines shift to higher pressures. Given the stability limits of these minerals, and the natural range of P-T conditions, none of the high-pressure distortions observed at high pressure are likely to occur at depth in the Earth.

  7. 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.

  8. 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

  9. Comprehensive size-determination of whole virus vaccine particles using gas-phase electrophoretic mobility macromolecular analyzer, atomic force microscopy, and transmission electron microscopy.

    PubMed

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

    2015-09-01

    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

  10. 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

  11. New pressure-induced phase transitions of L-threonine crystal: A Raman spectroscopic study

    NASA Astrophysics Data System (ADS)

    Holanda, R. O.; Lima, J. A.; Freire, P. T. C.; Melo, F. E. A.; Mendes Filho, J.; Polian, A.

    2015-07-01

    L-threonine crystal was studied by Raman spectroscopy under pressure in the spectral range from 50 to 3300 cm-1. The pressure range of a previous study has been extended from 4 to 27.0 GPa. Modifications in the whole spectrum give us evidence of three structural phase transitions undergone by this amino acid as well as two conformational change. The classification of the vibrational modes and the behavior of their frequencies as a function of the pressure are presented.

  12. In-situ microscopy of the first-order magnetic phase transition in FeRh thin films

    NASA Astrophysics Data System (ADS)

    Baldasseroni, Chloe

    Simple ferromagnetic (FM) and antiferromagnetic (AF) materials such as Fe and Cr become paramagnetic when heated above some critical temperature, in what is known as a second-order phase transition. Less usual magnetic transitions are found in the magnetic world, for example a first-order magnetic phase transition from AF to FM with increasing temperature. Equiatomic FeRh has been known to exhibit such a transition for over 50 years, with a transition temperature slightly above room temperature. Interest in this material has been renewed in the recent years due to its potential application for heat-assisted magnetic recording, as well as a test system for fundamental studies of the physics of magnetic phase transitions. Similarly to crystallization, this AF-FM transition is expected to proceed by nucleation of magnetic domains but the features of the first-order hysteretic transition have been difficult to study with macroscopic measurements and very few microscopic studies have been performed. In this work, FeRh thin films were synthesized by magnetron sputtering and structurally and magnetically characterized. A membrane-based heating device was designed to enable temperature-dependent microscopy measurements, providing a thermally uniform and well-controlled sample area. Synchrotron x-ray magnetic microscopy was used to study the temperature-driven AF-FM phase transition in epitaxial FeRh thin films in zero field. Using magnetic microscopy with x-ray magnetic circular dichroism, the different stages of nucleation, growth and coalescence of FM domains were observed across the transition and details of the nucleation were identified. The FM phase nucleates into single domain islands and the width of the transition of the individual nuclei upon heating is sharper than that of the macroscopic transition. Using magnetic microscopy with x-ray magnetic linear dichroism, the evolution of the AF phase was studied. Differences in the morphology of AF and FM phases were

  13. Crystallization kinetics of the phase change material GeSb6Te measured with dynamic transmission electron microscopy.

    PubMed

    Winseck, M M; Cheng, H-Y; Campbell, G H; Santala, M K

    2016-06-14

    GeSb6Te is a chalcogenide-based phase change material that has shown great ptoential for use in solid-state memory devices. The crystallization kinetics of amorphous thin films of GeSb6Te during laser crystallization were followed with dynamic transmission electron microscopy, a photo-emission electron microscopy technique with nanosecond-scale time resolution. Nine-frame movies of crystal growth were taken during laser crystallization. The nucleation rate is observed to be very low and the growth rates are very high, up to 10.8 m s(-1) for amorphous as-deposited films and significantly higher for an amorphous film subject to sub-threshold laser annealing before crystallization. The measured growth rates exceed any directly measured growth rate of a phase change material. The crystallization is reminiscent of explosive crystallization of elemental semiconductors both in the magnitude of the growth rate and in the resulting crystalline microstructures. PMID:27026479

  14. 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

  15. Influence of the phase effect on gradient-based and statistics-based focus measures in bright field microscopy.

    PubMed

    Schoell, S; Mualla, F; Sommerfeldt, B; Steidl, S; Maier, A; Buchholz, R; Hornegger, J

    2014-05-01

    Autofocusing is essential to high throughput microscopy and live cell imaging and requires reliable focus measures. Phase objects such as separated single Chinese hamster ovary cells are almost invisible at the optical focus position in bright field microscopy images. Because of the phase effect, defocused images of phase objects have more contrast. In this paper, we show that widely used focus measures exhibit an untypical behaviour for such images. In the case of homogeneous cells, that is, when most cells tend to lie in the same focal plane, both gradient-based and statistics-based focus measures tend to have a local minimum instead of a global maximum at the optical focus position. On the other hand, if images show inhomogeneous cells, gradient-based focus measures tend to yield typical focus curves, whereas statistics-based focus measures deliver curves similar to the case of homogeneous cells. These results were interpreted using the equation describing the phase effect and patch-wise analysis of the focus curves. Bioprocess engineering experts are also influenced by the phase effect. Forty-four focus positions selected by them led to the conclusion that they prefer to look at defocused images instead of those at the optical focus. PMID:24611652

  16. 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.

  17. The investigation of phase evolution in composite ceramic superconductors using Raman microscopy techniques

    SciTech Connect

    Maroni, V. A.; Fischer, A. K.; Wu, K. T.

    1999-12-23

    Raman microspectroscopy and imaging techniques have been used to investigate key mechanistic features that influence the formation of layered Bi- and Tl-based superconducting phases during the thermal treatment employed to produce BSCCO and TBCCO composite conductors. Seminal information gained from these studies includes the location of lead-rich nonsuperconducting second phases (NSPS) and the identification of the constituent phases in certain NSP agglomerations that tend to resist dissipation as high-Tc phase formation proceeds to completion.

  18. The investigation of phase evolution in composite ceramic superconductors using Raman microscopy techniques

    NASA Astrophysics Data System (ADS)

    Maroni, V. A.; Fischer, A. K.; Wu, K. T.

    Raman microspectroscopy and imaging techniques are being used to investigate key mechanistic features that influence the formation of layered Bi-based superconducting phases during the thermal treatment employed to produce silversheathed Bi-2223 composite conductors. Seminal information gained from these studies includes the identification of the constituent phases in certain nonsuperconducting second phase (NSP) agglomerations that tend to resist dissipation as high-Tc phase formation proceeds to completion.

  19. Gas-Phase Spectroscopic Signatures of Carboxylate-Li(+) Contact Ion Pairs: New Benchmarks For Characterizing Ion Pairing in Solution.

    PubMed

    Habka, Sana; Brenner, Valérie; Mons, Michel; Gloaguen, Eric

    2016-04-01

    The coexistence of several types of ion pairs in solution together with their elusive nature hampers their experimental characterization, which relies in practice on theoretical models resorting to numerous approximations. In this context, a series of isolated contact ion pairs between a lithium cation and phenyl-tagged carboxylate anions of various lengths (Ph-(CH2)n-COO(-), n = 1-3) has been investigated in a conformer-selective manner by IR and UV laser spectroscopy, in conjunction with quantum chemistry calculations. The typical gas-phase IR signature of the bidentate structure formed between the carboxylate moiety and Li(+) has thus been obtained in the CO2(-) stretch region. In addition to the cation-anion interaction, a cation-π interaction occurs simultaneously in the largest system investigated (n = 3). The resulting distorted ion pair structure has been evidenced from both the IR signature of the CO2(-) stretches and the unique vibrationally resolved UV spectroscopy of a phenyl ring interacting with a cation. Such specific spectroscopic signatures of contact ion pairs provide experimental benchmarks, alternative to theoretical predictions, that can assist the assignment of vibrational spectra in solution. PMID:26978595

  20. 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.

  1. 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.

  2. 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.

  3. Spectroscopic investigation of the high-current phase of a pulsed GMAW process

    NASA Astrophysics Data System (ADS)

    Rouffet, M. E.; Wendt, M.; Goett, G.; Kozakov, R.; Schoepp, H.; Weltmann, K. D.; Uhrlandt, D.

    2010-11-01

    While metal vapours have an important impact on the efficiency of the pulsed gas metal arc welding process, only a few papers are focused on this effect. In this paper, methods based on emission spectroscopy are performed to improve the understanding of the physical phenomena occurring during the high-current pulse. Boltzmann plots applied to iron lines, the Stark broadening of the 696.5 nm argon line and composition calculations assuming local thermodynamic equilibrium are used to determine characteristic parameters of the plasma. It is observed that the central part of the arc is composed mainly of iron. The percentage of iron increases quickly at the beginning of the high-current pulse, and slowly decreases when the central part broadens. During the high-current phase the temperature profile has a minimum value of around 8000 K at the axis of the arc while the argon envelope of the central part reaches temperatures of approximately 13.000 K. The high percentage of iron and the high radiation of the plasma at the centre can explain the measured shape of the temperature profile.

  4. A computational and spectroscopic study of the gas-phase conformers of adrenaline

    NASA Astrophysics Data System (ADS)

    Çarçabal, P.; Snoek, L. C.; van Mourik, T.

    The conformational landscapes of the neurotransmitter l-adrenaline (l-epinephrine) and its diastereoisomer pseudo-adrenaline, isolated in the gas phase and un-protonated, have been investigated by using a combination of mass-selected ultraviolet and infrared holeburn spectroscopy, following laser desorption of the sample into a pulsed supersonic argon jet, and DFT and ab initio computation (at the B3LYP/6-31+G*, MP2/6-31+G* and MP2/aug-cc-pVDZ levels of theory). Both for adrenaline and its diastereoisomer, pseudo-adrenaline, one dominant molecular conformation, very similar to the one seen in noradrenaline, has been observed. It could be assigned to an extended side-chain structure (AG1a) stabilized by an OH → N intramolecular hydrogen bond. An intramolecular hydrogen bond is also formed between the neighbouring hydroxyl groups on the catechol ring. The presence of further conformers for both diastereoisomers could not be excluded, but overlapping electronic spectra and low ion signals prevented further assignments.

  5. Characterization of U(VI)-phases in corroded cement products by micro(μ)-spectroscopic methods

    NASA Astrophysics Data System (ADS)

    Rothe, J.; Brendebach, B.; Bube, C.; Dardenne, K.; Denecke, M. A.; Kienzler, B.; Metz, V.; Prüßmann, T.; Rickers-Appel, K.; Schild, D.; Soballa, E.; Vitova, T.

    2013-04-01

    Cementation is an industrial scale conditioning method applied to fix and solidify liquid low and intermediate level radioactive wastes (LLW/ILW) prior to underground disposal in geological formations.To assist prognosis of the long-term safety of cemented waste, alteration of uranium doped cement productswas studied in chloride-rich solutions relevant for final LLW/ILW disposal in rock salt. After long-time exposure of the full-scale LLW/ILW simulates to concentrated NaCl and MgCl2 brines, solid samples were retrieved for chemical and mineralogical analysis with an emphasis on uranium speciation in the corroded cement matrix.Bulk and recent spatially resolved micro(μ) U L3-XAFS measurements point to the occurrence of a diuranate type U(VI) phase forming throughout the corroded cement monoliths. U-enriched hot spots with dimensions up to several tens of μm turn out to be generally X-ray amorphous.

  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. Comparison of the layer structure of vapor phase and leached SRL glass by use of AEM [analytical electron microscopy

    SciTech Connect

    Biwer, B.M.; Bates, J.K.; Abrajano, T.A. Jr.; Bradley, J.P.

    1989-12-31

    Test samples of 131 type glass that have been reacted for extended time periods in water vapor atmospheres of different relative humidities and in static leaching solution have been examined to characterize the reaction products. Analytical electron microscopy (AEM) was used to characterize the leached samples, and a complicated layer structure was revealed, consisting of phases that precipitate from solution and also form within the residual glass layer. The precipitated phases include birnes-site, saponite, and an iron species, while the intralayer phases include the U-Ti containing phase brannerite distributed within a matrix consisting of bands of an Fe rich montmorillonite clay. Comparison is made between samples leached at 40{degrees}C for 4 years with those leached at 90{degrees}C for 3-1/2 years. The samples reacted in water vapor were examined with scanning electron microscopy and show increasing reaction as both the relative humidity and time of reaction increases. These samples also contain a layered structure with reaction products on the glass surface. 15 refs., 5 figs.

  8. 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.

  9. 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

  10. Enhanced quantitative phase imaging in self-interference digital holographic microscopy using an electrically focus tunable lens

    PubMed Central

    Schubert, Robin; Vollmer, Angelika; Ketelhut, Steffi; Kemper, Björn

    2014-01-01

    Self-interference digital holographic microscopy (DHM) has been found particular suitable for simplified quantitative phase imaging of living cells. However, a main drawback of the self-interference DHM principle are scattering patterns that are induced by the coherent nature of the laser light which affect the resolution for detection of optical path length changes. We present a simple and efficient technique for the reduction of coherent disturbances in quantitative phase images. Therefore, amplitude and phase of the sample illumination are modulated by an electrically focus tunable lens. The proposed method is in particular convenient with the self-interference DHM concept. Results from the characterization of the method show that a reduction of coherence induced disturbances up to 70 percent can be achieved. Finally, the performance for enhanced quantitative imaging of living cells is demonstrated. PMID:25574433

  11. 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.

  12. Multifrequency imaging in the intermittent contact mode of atomic force microscopy: beyond phase imaging

    SciTech Connect

    Guo, Senli; Santiago, Solares D; Mochalin, Vadym; Neitzel, Ioannis; Gogotsi, Yury G.; Kalinin, Sergei V; Jesse, Stephen

    2012-01-01

    Force-based scanning probe microscopies have emerged as a mainstay for probing structural and mechanical properties of materials on the nanometer and molecular scales. Despite tremendous progress achieved to date, the cantilever dynamics in single frequency scanning probe microscopies (SPM) is undefined due to having only two output variables. Here we demonstrate on diamond nanoparticles with different functionalization layers that the use of broad band detection by multiple frequency SPM allows complete information on tip-surface interactions in intermittent contact SPM to be acquired. The obtained data allows sub-3nm resolution even in ambient environment. By tuning the strength of tip-surface interaction, the information on surface state can be obtained.

  13. Dissecting eukaryotic cells by coherent phase microscopy: quantitative analysis of quiescent and activated T lymphocytes

    NASA Astrophysics Data System (ADS)

    Tychinsky, Vladimir P.; Kretushev, Alexander V.; Vyshenskaya, Tatiana V.; Shtil, Alexander A.

    2012-07-01

    We present a concept for quantitative characterization of a functional state of an individual eukaryotic cell based on interference imaging. The informative parameters of the phase images of quiescent and mitogen-activated T lymphocytes included the phase thickness, phase volume, the area, and the size of organelles. These parameters were obtained without a special hypothesis about cell structure. Combinations of these parameters generated a ``phase portrait'' of the cell. A simplified spherical multilayer optic model of a T lymphocyte was used to calculate the refractivity profile, to identify structural elements of the image with the organelles, and to interpret the parameters of the phase portrait. The values of phase image parameters underwent characteristic changes in the course of mitogenic stimulation of T cells; thereby, the functional state of individual cells can be described using these parameters. Because the values of the components of the phase portrait are measured in absolute units, it is possible to compare the parameters of images obtained with different interference microscopes. Thus, the analysis of phase portraits provides a new and perspective approach for quantitative, real-time analysis of subcellular structure and physiologic state of an individual cell.

  14. Physical compensation of phase curvature in digital holographic microscopy by use of programmable liquid lens.

    PubMed

    Doblas, Ana; Hincapie-Zuluaga, Diego; Saavedra, Genaro; Martínez-Corral, Manuel; Garcia-Sucerquia, Jorge

    2015-06-01

    Quantitative phase measurements obtained with digital holographic microscopes are strongly dependent on the optical arrangement of the imaging system. The nontelecentric operation provides phase measurements affected by a parabolic phase factor and requires numerical postprocessing, which does not always remove all the perturbation. Accurate phase measurements are achieved by using the imaging system in telecentric mode. Unfortunately, this condition is not accomplished when a commercial microscope is used as the imaging system. In this paper, we present an approach for obtaining accurate phase measurements in nontelecentric imaging systems without the need for numerical postprocessing. The method uses an electrically tunable liquid lens to illuminate the sample so that the perturbing parabolic wavefront is cancelled out. Experimental holograms of a Fresnel lens and a section of the thorax of a Drosophila melanogaster fly are captured to verify the proposed method. PMID:26192688

  15. 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.

  16. Subsurface imaging and cell refractometry using quantitative phase/ shear-force feedback microscopy

    NASA Astrophysics Data System (ADS)

    Edward, Kert; Farahi, Faramarz

    2009-10-01

    Over the last few years, several novel quantitative phase imaging techniques have been developed for the study of biological cells. However, many of these techniques are encumbered by inherent limitations including 2π phase ambiguities and diffraction limited spatial resolution. In addition, subsurface information in the phase data is not exploited. We hereby present a novel quantitative phase imaging system without 2 π ambiguities, which also allows for subsurface imaging and cell refractometry studies. This is accomplished by utilizing simultaneously obtained shear-force topography information. We will demonstrate how the quantitative phase and topography data can be used for subsurface and cell refractometry analysis and will present results for a fabricated structure and a malaria infected red blood cell.

  17. 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.

  18. 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.

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

    PubMed Central

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

    2014-01-01

    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. PMID:24929378

  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. PMID:27160487

  1. Imaging microscopy by phase-contrast engine: retardation-modulated differential interference contrast microscope

    NASA Astrophysics Data System (ADS)

    Ishiwata, Hiroshi; Itoh, Masahide

    2014-11-01

    In the field of biology and medicine, observation object of the microscope has been changing from the thin specimen to the thick living tissue. Furthermore, observation of the internal structure of a living tissue is also desired by low invasion. However, the real structure of a phase object with three-dimensional distribution such as a living tissue is difficult to observe, because of the influence of the phase distribution before and behind of observation position. We enabled observation of the internal structure of living tissue without stain, by adding a new function to reduce the influence of phase distribution to our Retardation-Modulated differential interference contrast (RM-DIC) microscope system.

  2. 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.

  3. 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. PMID:21174424

  4. 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.

  5. 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

  6. Phase transitions in a LiMn2O4 nanowire battery observed by operando electron microscopy.

    PubMed

    Lee, Soyeon; Oshima, Yoshifumi; Hosono, Eiji; Zhou, Haoshen; Kim, Kyungsu; Chang, Hansen M; Kanno, Ryoji; Takayanagi, Kunio

    2015-01-27

    Fast charge-discharge process has been reported to give a high capacity loss. A nanobattery consisting of a single LiMn2O4 nanowire cathode, ionic liquid electrolyte and lithium titanium oxide anode was developed for in situ transmission electron microscopy. When it was fully charged or discharged within a range of 4 V in less than half an hour (corresponding average C rate: 2.5C), Li-rich and Li-poor phases were observed to be separated by a transition region, and coexisted during whole process. The phase transition region moved reversibly along the nanowire axis which corresponds to the [011] direction, allowing the volume fraction of both phases to change. In the electron diffraction patterns, the Li-rich phase was seen to have the (100) orientation with respect to the incident electron beam, while the Li-poor phase had the (111̅) orientation. The orientation was changed as the transition region moved. However, the nanowire did not fracture. This suggests that a LiMn2O4 nanowire has the advantage of preventing capacity fading at high charge rates. PMID:25513896

  7. Influence of product phase separation on phospholipase A(2) hydrolysis of supported phospholipid bilayers studied by force microscopy.

    PubMed Central

    Nielsen, Lars K; Balashev, Konstatin; Callisen, Thomas H; Bjørnholm, Thomas

    2002-01-01

    In situ atomic force microscopy studies reveal a marked influence of the initial presence of hydrolysis products on the hydrolysis of supported phospholipid bilayers by phospholipase A(2). By analysis of the nano-scale topography of a number of supported bilayers with different initial product concentrations, made by Langmuir-Blodgett deposition, we show that small depressions enriched in products are efficiently promoting enzyme degradation of the bilayer. These small depressions, which are indicative of phase separation, are initially present in samples with 75% products. The kinetics of phospholipase A(2) exhibit under certain conditions an initial phase of slow hydrolysis, termed the latency phase, followed by a marked increase in the hydrolysis rate. The appearance of the phase-separated bilayer is strikingly similar to that of bilayers at the end of the latency phase. By analysis of individual nano-scale defects we illustrate a quantitative difference in the growth rates of defects caused by product aggregation and other structural defects. This difference shows for the first time how the enzyme prefers one type of defect to another. PMID:12414695

  8. Observation of Shock-Induced Phases of Nb2O5 Single Crystal under High-Resolution Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Kikuchi, Masae; Kusaba, Keiji; Bannai, Eisuke; Fukuoka, Kiyoto; Syono, Yasuhiko; Hiraga, Kenji

    1985-12-01

    Shock-loading experiments on Nb2O5 single crystals were carried out up to 54 GPa by the gun method. The shock-loaded materials are recovered by using both closed and open recovery fixtures and were examined by powder X-ray diffraction analysis and high-resolution electron microscopy. Complete conversion to T-Nb2O5 of μm size, denser by 12% than H-Nb2O5, was found in the pressure range from 20-40 GPa. When single-crystal H-Nb2O5 was shocked perpendicular to the b-axis using the open-system recovery fixture, an unidentified phase referred to as the X-phase, besides T-Nb2O5 and shock-reduced NbxO2 with the rutile structure, was observed. The high-resolution image of the X-phase is interpreted as two-dimensionally disordered H-Nb2O5. The X-phase is probably formed in the rapid decompression process from the shock-induced high-pressure phase.

  9. 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.

  10. In operando tracking phase transformation evolution of lithium iron phosphate with hard X-ray microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Jiajun; Chen-Wiegart, Yu-Chen Karen; Wang, Jun

    2014-08-01

    The delithiation reaction in lithium ion batteries is often accompanied by an electrochemically driven phase transformation process. Tracking the phase transformation process at nanoscale resolution during battery operation provides invaluable information for tailoring the kinetic barrier to optimize the physical and electrochemical properties of battery materials. Here, using hard X-ray microscopy—which offers nanoscale resolution and deep penetration of the material, and takes advantage of the elemental and chemical sensitivity—we develop an in operando approach to track the dynamic phase transformation process in olivine-type lithium iron phosphate at two size scales: a multiple-particle scale to reveal a rate-dependent intercalation pathway through the entire electrode and a single-particle scale to disclose the intraparticle two-phase coexistence mechanism. These findings uncover the underlying two-phase mechanism on the intraparticle scale and the inhomogeneous charge distribution on the multiple-particle scale. This in operando approach opens up unique opportunities for advancing high-performance energy materials.

  11. Optical detection and measurement of living cell morphometric features with single-shot quantitative phase microscopy.

    PubMed

    Bon, Pierre; Savatier, Julien; Merlin, Marine; Wattellier, Benoıt; Monneret, Serge

    2012-07-01

    We present a quadriwave lateral shearing interferometer used as a wavefront sensor and mounted on a commercial non-modified transmission white-light microscope as a quantitative phase imaging technique. The setup is designed to simultaneously make measurements with both quantitative transmission phase and fluorescence modes: phase enables enhanced contrasted visualization of the cell structure including intracellular organelles, while fluorescence allows a complete and precise identification of each component. After the characterization of the phase measurement reliability and sensitivity on calibrated samples, we use these two imaging modes to measure the characteristic optical path difference between subcellular elements (mitochondria, actin fibers, and vesicles) and cell medium, and demonstrate that phase-only information should be sufficient to identify some organelles without any labeling, like lysosomes. Proof of principle results show that the technique could be used either as a qualitative tool for the control of cells before an experiment, or for quantitative studies on morphology, behavior, and dynamics of cells or cellular components. PMID:22894487

  12. 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.

  13. 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

  14. Lensless phase microscopy and diffraction tomography with multi-angle and multi-wavelength illuminations using a LED matrix.

    PubMed

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

    2015-06-01

    We demonstrate lensless quantitative phase microscopy and diffraction tomography based on a compact on-chip platform, using only a CMOS image sensor and a programmable color LED matrix. Based on the multi-wavelength phase retrieval and multi-angle illumination diffraction tomography, this platform offers high quality, depth resolved images with a lateral resolution of 3.72μm and an axial resolution of 5μm, across a wide field-of-view of 24mm2. We experimentally demonstrate the success of our method by imaging cheek cells, micro-beads, and fertilized eggs of Parascaris equorum. Such high-throughput and miniaturized imaging device can provide a cost-effective tool for telemedicine applications and point-of-care diagnostics in resource-limited environments. PMID:26072796

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

    NASA Astrophysics Data System (ADS)

    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.

    2016-03-01

    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.

  16. 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

  17. 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

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

    PubMed Central

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

    2015-01-01

    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

  19. 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

  20. Quadriwave lateral shearing interferometry for quantitative phase microscopy: applications to long-duration imaging

    NASA Astrophysics Data System (ADS)

    Bon, Pierre; Wattellier, Benoit; Monneret, Serge; Marguet, Didier

    2010-02-01

    Phase imaging with a high-resolution wavefront sensor is a useful setup for biological imaging. Our setup is based on a quadriwave lateral shearing interferometer mounted on a non-modified transmission white-light microscope. We propose here to study long-time duration imaging on different type of adherent cells: green monkey kidney COS7 cells, human breast epithelial MCF10A cells, and human breast cancer derived from MDA-231 cells. This study permits a enhanced visualization of the whole cell life at different levels of confluence. Post treatments on phase-shift images are proposed and become very interesting for enhanced visualization of small details and thresholding.

  1. Time-resolved quantitative-phase microscopy of laser-material interactions using a wavefront sensor.

    PubMed

    Gallais, Laurent; Monneret, Serge

    2016-07-15

    We report on a simple and efficient technique based on a wavefront sensor to obtain time-resolved amplitude and phase images of laser-material interactions. The main interest of the technique is to obtain quantitative self-calibrated phase measurements in one shot at the femtosecond time-scale, with high spatial resolution. The technique is used for direct observation and quantitative measurement of the Kerr effect in a fused silica substrate and free electron generation by photo-ionization processes in an optical coating. PMID:27420506

  2. 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

  3. Advanced tip design for liquid phase vibration mode atomic force microscopy.

    PubMed

    Muramatsu, Hiroshi; Yamamoto, Yuji; Shigeno, Masatsugu; Shirakawabe, Yoshiharu; Inoue, Akira; Kim, Woo-Sik; Kim, Seung Jin; Chang, Sang-Mok; Kim, Jong Min

    2008-03-24

    We have fabricated polymer tips for atomic force microscopy in order to elucidate the effects of tip length and shape on cantilever vibration damping in liquids. The vibration damping is investigated by measuring the vibration amplitude of cantilevers as a function of tip-sample distance. The cantilever with a short tip provides a higher damping effect over long tip-sample distances. When the vibration amplitude was rescaled to show the effect of the cantilever width on oscillation damping, the vibration amplitude of cantilevers with various tip lengths was similarly obtained in a long distance range over 50 microm. This similarity is explained by an acoustic damping model in which an acoustic wave is generated by the cantilever. Finally, the results indicate a cantilever with a sufficiently long tip compared to the cantilever width can dramatically reduce the long-range damping effect in a liquid environment. PMID:18328326

  4. Coherence-controlled holographic microscopy for live-cell quantitative phase imaging in turbid media

    NASA Astrophysics Data System (ADS)

    Lostak, M.; Collakova, J.; Slaby, T.; Krizova, A.; Vesely, P.; Chmelik, R.

    2016-03-01

    In this work we present the coherence controlled holographic microscopy (CCHM)1 and its ability to image the living cells in turbid media2. The CCHM method and its advantages are introduced. A 'coherence gate effect'3, that enables imaging in turbid media, occurs owing to the low coherence illumination in our setup. The coherence gate effect is briefly theoretically explained and comparison of images with different illumination sources is shown. After that, the possibility of imaging in turbid media is applied to investigation of cell reactions to cytopathic turbid emulsions. In our experiments we used human cancer cells treated by biologically active phospholipids (BAPs). Cellular events leading to cell death, that would otherwise remain hidden in turbid media, are clearly observable and according to them cell fate can be deduced.

  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. 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.

  7. 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.

  8. Scanning electron microscopy of goat oviductal epithelial cells at the follicular and luteal phases of the oestrus cycle.

    PubMed Central

    Abe, H; Onodera, M; Sugawara, S

    1993-01-01

    The luminal surfaces of epithelial cells in various regions of the oviducts of the goats at the follicular and luteal phases of the oestrous cycle were examined by scanning electron microscopy. Marked cyclic changes were observed on the surface of the epithelium in the fimbriae, ampulla and ampullar-isthmic junction, but few changes were found in the isthmus or uterotubal junction. The epithelium of the fimbriae, ampulla, and ampullar-isthmic junction of oviducts in the follicular phase was extensively ciliated and most of the cilia extended above the apical processes of the nonciliated cells. In the luteal phase, many ciliated cells were hidden by the bulbous processes of the nonciliated cells. In the isthmus and at the uterotubal junction, the apical surfaces of the nonciliated cells were flat or gently rounded at both phases of the oestrous cycle. The results demonstrate that regional variations are associated with the cyclic changes in the epithelial cells of the goat oviduct. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 PMID:8300425

  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. Long-term quantitative phase-contrast imaging of living cells by digital holographic microscopy

    NASA Astrophysics Data System (ADS)

    Liu, S.; Pan, F.; Wang, Z.; Wang, F.; Rong, L.; Shang, P.; Xiao, W.

    2011-04-01

    The dynamic analysis of biological living samples is one of the particular interests in life sciences. An improved digital holographic microscope for long-term quantitative phase-contrast imaging of living cells is presented in this paper. The optical configuration is optimized in the form of a free-space-fiber hybrid system which promotes the flexibility of imaging in complex or semi-enclosed experimental environment. Aberrations compensation is implemented taking into account the additional phase aberration induced by liquid culture medium in long-term observation. The proposed approach is applied to investigate living samples of MC3T3-E1 and MLO-Y4 cells. The experimental results demonstrate its availability in the analysis of cellular changes.

  11. Spectroscopic and theoretical study of the "azo"-dye E124 in condensate phase: evidence of a dominant hydrazo form.

    PubMed

    Almeida, Mariana R; Stephani, Rodrigo; Dos Santos, Hélio F; de Oliveira, Luiz Fernando C

    2010-01-14

    Spectroscopic techniques, including Raman, IR, UV/vis, and NMR were used to characterize the samples of the azo dye Ponceau 4R (also known as E124, New Coccine; Cochineal Red; C.I. no. 16255; Food Red No. 102), which is 1,3-naphthalenedisulfonic acid, 7-hydroxy-8-[(4-sulfo-1-naphthalenyl) azo] trisodium salt in aqueous solution and solid state. In addition, first principle calculations were carried out for the azo (OH) and hydrazo (NH) tautomers in order to assist in the assignment of the experimental data. The two intense bands observed in the UV/vis spectrum, centered at 332 and 507 nm, can be compared to the calculated values at 296 and 474 nm for azo and 315 and 500 nm for hydrazo isomer, with the latter in closer agreement to the experiment. The Raman spectrum is quite sensitive to tautomeric equilibrium; in solid state and aqueous solution, three bands were observed around 1574, 1515, and 1364 cm(-1), assigned to mixed modes including deltaNH + betaCH + nuCC, deltaNH + nuC horizontal lineO + nuC horizontal lineN + betaCH and nuCC vibrations, respectively. These assignments are predicted only for the NH species centered at 1606, 1554, and 1375 cm(-1). The calculated Raman spectrum for the azo (OH) tautomer showed two strong bands at 1468 (nuN = N + deltaOH) and 1324 cm(-1) (nuCC + nuC-N), which were not obtained experimentally. The (13)C NMR spectrum showed a very characteristic peak at 192 ppm assigned to the carbon bound to oxygen in the naphthol ring; the predicted values were 165 ppm for OH and 187 for NH isomer, supporting once again the predominance of NH species in solution. Therefore, all of the experimental and theoretical results strongly suggest the food dye Ponceau 4R or E124 has a major contribution of the hydrazo structure instead of the azo form as the most abundant in condensate phase. PMID:19852449

  12. Spectroscopic and atomic force microscopy characterization of the electrografting of 3,5-bis(4-diazophenoxy)benzoic acid on gold surfaces.

    PubMed

    Civit, Laia; El-Zubir, Osama; Fragoso, Alex; O'Sullivan, Ciara K

    2013-03-15

    The synthesis of a bipodal diazonium salt, 3,5-bis(4-diazophenoxy)benzoic acid, and the study of its electrochemical deposition on gold surfaces is presented. The presence of the organic layer on the gold surface was characterized using atomic force microscopy and X-ray photoelectron spectroscopy, demonstrating the presence of phenyl groups, indicative of the grafted layer as well as the formation of multilayers, dependent on the electrografting conditions. PMID:22960009

  13. 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

  14. 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.

  15. 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.

  16. Scanning tunneling microscopy in TTF-TCNQ: Phase and amplitude modulated charge density waves

    NASA Astrophysics Data System (ADS)

    Wang, Z. Z.; Girard, J. C.; Pasquier, C.; Jérome, D.; Bechgaard, K.

    2003-03-01

    Charge density waves (CDWs) have been studied at the surface of a cleaved tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) single crystal using a low temperature scanning tunneling microscope (STM) under ultrahigh-vacuum conditions, between 300 and 33 K with molecular resolution. All CDW phase transitions of TTF-TCNQ have been identified. The measurement of the modulation wave vector along the a direction provides evidence of the existence of domains comprising single plane wave modulated structures in the temperature regime where the transverse wave vector of the CDW is temperature dependent, as hinted by the theory more than 20 years ago.

  17. Geometric phase low-coherence interference microscopy at high numerical apertures

    NASA Astrophysics Data System (ADS)

    Roy, Maitreyee; Svahn, Peter; Sheppard, Colin J. R.

    2001-09-01

    A low-coherence Linnik interference microscope using high numerical aperture optics has been constructed. The system uses a tungsten halogen lamp and a Koehler illumination, with separate control over field and aperture stops, so that experiments can be conducted with a range of different geometric phase which is achieved by using a polarizing beam splitter, a quarter wave plate and a rotating polarizer. Image information is extracted from the visibility of the fringes, and the position of the visibility peak along the scanning axis, yielding the height of the test surface at the corresponding points.

  18. 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.

  19. Analytical electron microscopy of fine-grained phases in primitive interplanetary dust particles and carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Mackinnon, Ian D. R.; Rietmeijer, Frans J. M.; Mckay, David S.

    1987-01-01

    In order to describe the total mineralogical diversity within primitive extraterrestrial materials, individual interplanetary dust particles (IDPs) collected from the stratosphere as part of the JSC Cosmic Dust Curatorial Program were analyzed using a variety of AEM techniques. Identification of over 250 individual grains within one chondritic porous (CP) IDP shows that most phases could be formed by low temperature processes and that heating of the IDP during atmospheric entry is minimal and less than 600 C. In a review of the mineralogy of IDPs, it was suggested that the occurrence of other silicates such as enstatite whiskers is consistent with the formation in an early turbulent period of the solar nebula. Experimental confirmation of fundamental chemical and physical processes in a stellar environment, such as vapor phase condensation, nucleation, and growth by annealing, is an important aspect of astrophysical models for the evolution of the Solar System. A detailed comparison of chondritic IDP and carbonaceous chondrite mineralogies shows significant differences between the types of silicate minerals as well as the predominant oxides.

  20. 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

  1. The electronic phase diagram of NaFe1-xCoxAs studied by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Yayu

    2014-03-01

    Similar to the high TC cuprates, the iron pnictide superconductors also lie in close proximity to a magnetically ordered phase. The interplay between magnetism and superconductivity (SC) is a central issue concerning the pairing mechanism. A key step for resolving this issue is to acquire a comprehensive picture regarding the nature of various phases and interactions in the iron-based compounds. In this talk we present doping, temperature, and spatial evolutions of the electronic structure of NaFe1-xCoxAs studied by scanning tunneling microscopy. The spin density wave (SDW) gap in the parent state is directly observed, which shows a strongly asymmetric lineshape that is incompatible with conventional Fermi surface nesting. In the underdoped regime the SDW and SC phases are shown to microscopically coexist and compete with each other. The optimally doped sample exhibits a single SC gap, but in the overdoped regime another asymmetric gap-like feature emerges near the Fermi level. In contrast to the rich variations of the low energy electronic states, the high energy spectra of the NaFe1-xCoxAs system remain nearly unchanged until the system enters the strongly overdoped non-SC regime. The implications of the local electronic structures on the pairing mechanism of the iron pnictides will be discussed.

  2. Two-dimensional and three-dimensional viability measurements of adult stem cells with optical coherence phase microscopy

    NASA Astrophysics Data System (ADS)

    Bagnaninchi, Pierre O.; Holmes, Christina; Drummond, Nicola; Daoud, Jamal; Tabrizian, Maryam

    2011-08-01

    Cell viability assays are essential tools for cell biology. They assess healthy cells in a sample and enable the quantification of cellular responses to reagents of interest. Noninvasive and label-free assays are desirable in two-dimensional (2D) and three-dimensional (3D) cell culture to facilitate time-course viability studies. Cellular micromotion, emanating from cell to substrate distance variations, has been demonstrated as a marker of cell viability with electric cell-substrate impedance sensing (ECIS). 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 associated with cellular micromotion. An OCPM has been developed around a Thorlabs engine (λo = 930 nm) 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 micromotion was confirmed by ECIS analysis. Live and fixed ADSCs were then investigated in 2D and 3D with OCPM. Significant differences were found in phase fluctuations between the different conditions. This study indicated that OCPM could potentially assess cell vitality in 2D and in 3D microstructures.

  3. 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

  4. 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

  5. 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.

  6. Spectroscopic Identification and Metallicity Determination of RR Lyrae Variables in Sloan, with a New Metallicity Calibration Including High-Temperature Phase Regions

    NASA Astrophysics Data System (ADS)

    Spalding, Eckhart; Wilhelm, R. J.; De Lee, N. M.

    2014-01-01

    RR Lyrae stars provide important distance markers for tracing out the metallicity and physical extent of tidal streams and the galactic halo. Here we present a method for potentially identifying a few thousand RRL stars by comparing low-resolution, single-epoch spectra from the Sloan Digital Sky Survey (SDSS) DR9. This method is tested against the heavily-sampled ‘Stripe 82’ of SDSS. We have also begun developing a new metallicity calibration that fills in the high-temperature regions in RR Lyrae phases for phase regions other than (and including) minimum light. Our calibration extends metallicity determinations provided by previous methods which were calibrated at minimum light only, and also has the potential for detecting shorter-period RRc stars. Phase information was taken from the MacAdam Student Observatory at the University of Kentucky, and the Moore Observatory at the University of Louisville. Spectroscopy was recorded at the University of Texas’ McDonald Observatory. This spectroscopic data set builds on a metallicity standard that we discuss. Ultimately, this new calibration will allow the gleaning of more accurate metallicity information from spectroscopic data taken by surveys such as SDSS.

  7. Nanoscale nuclear architecture for cancer diagnosis beyond pathology via spatial-domain low-coherence quantitative phase microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Pin; Bista, Rajan K.; Khalbuss, Walid E.; Qiu, Wei; Uttam, Shikhar; Staton, Kevin; Zhang, Lin; Brentnall, Teresa A.; Brand, Randall E.; Liu, Yang

    2010-11-01

    Definitive diagnosis of malignancy is often challenging due to limited availability of human cell or tissue samples and morphological similarity with certain benign conditions. Our recently developed novel technology-spatial-domain low-coherence quantitative phase microscopy (SL-QPM)-overcomes the technical difficulties and enables us to obtain quantitative information about cell nuclear architectural characteristics with nanoscale sensitivity. We explore its ability to improve the identification of malignancy, especially in cytopathologically non-cancerous-appearing cells. We perform proof-of-concept experiments with an animal model of colorectal carcinogenesis-APCMin mouse model and human cytology specimens of colorectal cancer. We show the ability of in situ nanoscale nuclear architectural characteristics in identifying cancerous cells, especially in those labeled as ``indeterminate or normal'' by expert cytopathologists. Our approach is based on the quantitative analysis of the cell nucleus on the original cytology slides without additional processing, which can be readily applied in a conventional clinical setting. Our simple and practical optical microscopy technique may lead to the development of novel methods for early detection of cancer.

  8. Reflectivity and topography of cells grown on glass-coverslips measured with phase-shifted laser feedback interference microscopy

    PubMed Central

    Atılgan, Erdinç; Ovryn, Ben

    2011-01-01

    In spite of the advantages associated with the molecular specificity of fluorescence imaging, there is still a significant need to augment these approaches with label-free imaging. Therefore, we have implemented a form of interference microscopy based upon phase-shifted, laser-feedback interferometry and developed an algorithm that can be used to separate the contribution of the elastically scattered light by sub-cellular structures from the reflection at the coverslip-buffer interface. The method offers an opportunity to probe protein aggregation, index of refraction variations and structure. We measure the topography and reflection from calibration spheres and from stress fibers and adhesions in both fixed and motile cells. Unlike the data acquired with reflection interference contrast microscopy, where the reflection from adhesions can appear dark, our approach demonstrates that these regions have high reflectivity. The data acquired from fixed and live cells show the presence of a dense actin layer located ≈ 100 nm above the coverslip interface. Finally, the measured dynamics of filopodia and the lamella in a live cell supports retrograde flow as the dominate mechanism responsible for filopodia retraction. PMID:21833378

  9. 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

  10. 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

  11. 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

  12. Germination and Outgrowth of Single Spores of Saccharomyces cerevisiae Viewed by Scanning Electron and Phase-Contrast Microscopy

    PubMed Central

    Rousseau, Paul; Halvorson, Harlyn O.; Bulla, Lee A.; Julian, Grant St.

    1972-01-01

    Single spores of Saccharomyces cerevisiae were examined during germination and outgrowth by scanning electron and phase-contrast microscopy. Also determined were changes in cell weight and light absorbance, trehalose utilization, and synthesis of protein and KOH-soluble carbohydrates. These studies reveal that development of the vegetative cell from a spore follows a definite sequence of events involving dramatic physical and chemical modifications. These changes are: initial rapid loss in cellular absorbance followed later by an abrupt gain in absorbance; reduction in cell weight and a subsequent progressive increase; modification of the spore surface with concomitant diminution in refractility; elongation of the cell and augmentation of surface irregularities; rapid decline in trehalose content of the cell accompanied by extensive formation of KOH-soluble carbohydrates; and bud formation. Images PMID:4551750

  13. 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

  14. 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.

  15. Time-gated digital phase conjugation for two-photon excitation microscopy through multimode optical fibers

    NASA Astrophysics Data System (ADS)

    Morales-Delgado, Edgar E.; Farahi, Salma; Papadopoulos, Ioannis N.; Psaltis, Demetri; Moser, Christophe

    2015-12-01

    The large number of modes supported by multimode optical fibers potentially allows the transmission of larger amounts of information compared to single mode fibers. However, when pulsed light is transmitted through multimode fibers, the spatio-temporal profile of the incident beam is altered upon propagation, leading to a highly scrambled spatial profile and a broadened temporal duration due to modal and material dispersion. We present a digital phase conjugation method to counter-propagate through a multimode optical fiber only a group of modes of similar propagation constants which interfere constructively at a single location at the other side of the fiber, generating a spatially focused pulse. Since only modes with the same speed are excited, temporal broadening due to modal dispersion is suppressed, preserving the ultrashort duration of the propagating pulse. Using this technique, we experimentally demonstrate the transmission of focused pulses of 500 fs through a 30 cm length, 200 micrometer core step-index multimode fiber. Additionally, using a graded-index fiber, which allows the propagation of a larger number of modes of the same speed than a graded index fiber (hence a better focusing capability), we have been able to deliver and scan high-intensity focused femtosecond pulses. Moreover, based on the described principle, we demonstrate for the first time two-photon excitation imaging through a multimode optical fiber.

  16. 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

  17. Combined use of hard X-ray phase contrast imaging and X-ray fluorescence microscopy for sub-cellular metal quantification.

    PubMed

    Kosior, Ewelina; Bohic, Sylvain; Suhonen, Heikki; Ortega, Richard; Devès, Guillaume; Carmona, Asuncion; Marchi, Florence; Guillet, Jean Francois; Cloetens, Peter

    2012-02-01

    Hard X-ray fluorescence microscopy and magnified phase contrast imaging are combined to obtain quantitative maps of the projected metal concentration in whole cells. The experiments were performed on freeze dried cells at the nano-imaging station ID22NI of the European Synchrotron Radiation Facility (ESRF). X-ray fluorescence analysis gives the areal mass of most major, minor and trace elements; it is validated using a biological standard of known composition. Quantitative phase contrast imaging provides maps of the projected mass and is validated using calibration samples and through comparison with Atomic Force Microscopy and Scanning Transmission Ion Microscopy. Up to now, absolute quantification at the sub-cellular level was impossible using X-ray fluorescence microscopy but can be reached with the use of the proposed approach. PMID:22182730

  18. Construction of the Magnetic Phase Diagram of FeMn/Ni/Cu(001) Using Photoemission Electron Microscopy

    SciTech Connect

    Wu, J.; Scholl, A.; Arenholz, E.; Hwang, C.; Qiu, Z. Q.

    2011-01-04

    Single crystalline FeMn/Ni bilayer was epitaxially grown on Cu(001) substrate and investigated by photoemission electron microscopy (PEEM). The FeMn and Ni films were grown into two cross wedges to facilitate an independent control of the FeMn (0-20 ML) and Ni (0-20 ML) film thicknesses. The Ni magnetic phases were determined by Ni domain images as a function of the Ni thickness (d{sub Ni}) and the FeMn thickness (d{sub FeMn}). The result shows that as the Ni thickness increases, the Ni film undergoes a paramagnetic-to-ferromagnetic state transition at a critical thickness of d{sub FM} and an in-plane to out-of-plane spin reorientation transition at a thicker thickness d{sub SRT}. The phase diagram shows that both d{sub FM} and d{sub SRT} increase as the FeMn film establishes its antiferromagnetic order.

  19. 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

  20. 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.

  1. A hybrid analog-digital phase-locked loop for frequency mode non-contact scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    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.

  2. Structures of low-coverage phases of Al on the Si(100) surface observed by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Itoh, H.; Itoh, J.; Schmid, A.; Ichinokawa, T.

    1993-11-01

    The structure of the low-coverage Al phases on the Si(100)2×1 surface was determined by scanning tunneling microscopy (STM) with varying bias voltage and bias polarity. Surface structures of 2×2, 2×3, and 2×5 phases formed at below 350 °C consist of Al-dimer lines perpendicular to the underlying Si-dimer rows. The STM images of the Al-dimer lines taken at positive and negative bias between 1 and 3 V agree with those of the theoretical simulation by assuming the parallel Al-dimer structure. Moreover, we found that filled states of Al-Si backbonds and empty states of Al-Al dimer bonds of the parallel Al-dimer lines are observed prominently at -3 and +1 eV at positions on the underlying Si-dimer rows and between Si-dimer rows, respectively. Atomic configurations at the ends of the Al-dimer lines combined with the underlying Si missing dimer defects are discussed on the basis of the observed STM images.

  3. Particle tracking using confocal microscopy to probe the microrheology in a phase-separating emulsion containing nonadsorbing polysaccharide.

    PubMed

    Moschakis, Thomas; Murray, Brent S; Dickinson, Eric

    2006-05-01

    Brownian diffusion of fluorescent microspheres (0.21, 0.5, and 0.89 microm diameter) in conjunction with confocal microscopy has been used to monitor the microrheology of phase-separated regions in a protein-stabilized oil-in-water emulsion containing various low concentrations of a nonadsorbing polysaccharide, xanthan gum. The sensitivity and reliability of the technique has been demonstrated in test experiments on (i) aqueous glycerol solutions and (ii) concentrated surfactant-stabilized emulsions (30-60 vol % oil, 1-2 wt % Tween 20). From particle tracking measurements on the caseinate-stabilized emulsions (30 vol % oil, 1.4 wt % sodium caseinate, pH 7) containing xanthan (0.03-0.07 wt %), the apparent viscosity in the oil-droplet-rich regions has been estimated to be up to 10(3) times higher than that in the phase-separated xanthan-rich regions. This means that our previously determined shape relaxation times for xanthan-containing blobs in the same systems can be attributed to the dominant viscoelasticity of the surrounding regions of concentrated oil droplets and not to the rheology of the xanthan-rich blobs themselves. These data provide clear and unequivocal evidence for the dominant role of the interconnected depletion-flocculated network of oil droplets in the physicochemical mechanism by which hydrocolloid thickeners control the creaming instability of concentrated oil-in-water emulsions. PMID:16649786

  4. ViriChip: a solid phase assay for detection and identification of viruses by atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Nettikadan, Saju R.; Johnson, James C.; Vengasandra, Srikanth G.; Muys, James; Henderson, Eric

    2004-03-01

    Bionanotechnology can be viewed as the integration of tools and concepts in nanotechnology with the attributes of biomolecules. We report here on an atomic force microscopy-immunosensor assay (AFMIA) that couples AFM with solid phase affinity capture of biological entities for the rapid detection and identification of group B coxsackievirus particles. Virus identification is based on type-specific immunocapture and the morphological properties of the captured viruses as obtained by the AFM. Representatives of the six group B coxsackieviruses have been specifically captured from 1 µl volumes of clarified cell lysates, body fluids and environmental samples. Concentration and kinetic profiles for capture indicate that detection is possible at 103 TCID50 µl-1 and the dynamic range of the assay spans three logs. The results demonstrate that the melding of a nanotechnological tool (AFM) with biotechnology (solid phase immunocapture of virus particles) can create a clinically relevant platform, useful for the detection and identification of enterovirus particles in a variety of samples.

  5. Recent in-situ studies of the evolution of surfaces and interfaces of thin films by spectroscopic phase-modulated ellipsometry

    NASA Astrophysics Data System (ADS)

    Yakovlev, V.; Drevillon, Bernard; Layadi, Nace; Roca i Cabarrocas, Pere

    1993-04-01

    Application of spectroscopic phase modulated ellipsometry (PME) to study both ultrafast and slow processes of interaction of silane (SiH4) with thin film Pd, and to the investigation of the growth kinetics of a-Si:H films deposited by rf glow discharge under UV light irradiation are presented. As compared to other ellipsometric techniques like rotating analyzer ellipsometry (RAE), the phase modulation uses a high frequency of about 50 kHz provided by a photoelastic modulator. Thus, PME allows one to reach 1 - 5 ms time resolution which permits faster real-time measurements than RAE. This remarkable feature of PME makes it particularly suitable for in-situ applications. Changes of optical properties of Pd thin films exposed to SiH4 at different fluxes are monitored by in situ single wavelength ellipsometry in the case of high fluxes which lead to ultrafast process and by in situ spectroscopic ellipsometry at small fluxes and slow kinetics. The study reveals a complicated character of the process which depends on initial flux of silane and leads to formation of Pd disilicide, Pd hydride, and an intrinsic porosity. A qualitative model of the process is proposed.

  6. The mechanism of lamellar-to-inverted hexagonal phase transitions: a study using temperature-jump cryo-electron microscopy.

    PubMed Central

    Siegel, D P; Green, W J; Talmon, Y

    1994-01-01

    The lamellar/inverted hexagonal (L alpha/HII) phase transition can be very fast, despite the drastic change in the topology of the lipid/water interfaces. The first structures to form in this transition may be similar to those that mediate membrane fusion in many lipid systems. To study the transition mechanism and other dynamic phenomena in membrane dispersions, we constructed an apparatus to rapidly trigger the transition and then vitrify the specimens to preserve the structure of transient intermediates. The apparatus applies millisecond-long temperature jumps of variable size to aqueous dispersions of lipids on electron microscope grids at times 9-16 ms before specimen vitrification. The vitrified specimens are then examined by cryo-transmission electron microscopy. Dispersions of egg phosphatidylethanolamine completed the transition within 9 ms when superheated by 20 K. Similar transition times have been observed in dioleoylphosphatidylethanolamine via time-resolved x-ray diffraction. N-monomethylated dioleoylphosphatidylethanolamine dispersions superheated to lesser extent exhibited slower transitions and more complex morphology. The structure of the first intermediates to form in the transition process could not be determined, probably because the intermediates are labile on the time scale of sample cooling and vitrification (< 1 ms) and because of the poor contrast developed by some of these small structures. However, the results are more compatible with a transition mechanism based on "stalk" intermediates than a mechanism involving inverted micellar intermediates. Temperature-jump cryo-transmission electron microscopy should be useful in studying dynamic phenomena in biomembranes, large protein complexes, and other colloidal dispersions. It should be especially helpful in studying the mechanism of protein-induced membrane fusion. Images FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 FIGURE 8 FIGURE 9 FIGURE 10 PMID:8161694

  7. 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.

  8. 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).

  9. 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

  10. Zernike Phase Contrast Cryo-Electron Microscopy and Tomography for Structure Determination at Nanometer and Sub-Nanometer Resolutions

    PubMed Central

    Murata, Kazuyoshi; Liu, Xiangan; Danev, Radostin; Jakana, Joanita; Schmid, Michael F.; King, Jonathan; Nagayama, Kuniaki; Chiu, Wah

    2010-01-01

    SUMMARY Zernike phase contrast cryo-electron microscopy (ZPC-cryoEM) is an emerging technique which is capable of producing higher image contrast than conventional cryoEM. By combining this technique with advanced image processing methods, we achieved subnanometer resolution for two biological specimens: 2-D bacteriorhodopsin crystal and epsilon15 bacteriophage. For an asymmetric reconstruction of epsilon15 bacteriophage, ZPC-cryoEM can reduce the required amount of data by a factor of ~3 compared to conventional cryoEM. The reconstruction was carried out to 13 Å resolution without the need to correct the contrast transfer function. New structural features at the portal vertex of the epsilon15 bacteriophage are revealed in this reconstruction. Using ZPC cryo-electron tomography (ZPC-cryoET), a similar level of data reduction and higher resolution structures of epsilon15 bacteriophage can be obtained relative to conventional cryoET. These results show quantitatively the benefits of ZPC-cryoEM and -cryoET for structural determinations of macromolecular machines at nanometer and subnanometer resolutions. PMID:20696391

  11. Nanoscale phase transformation in Ge2Sb2Te5 using encapsulated scanning probes and retraction force microscopy.

    PubMed

    Bhaskaran, Harish; Sebastian, Abu; Pauza, Andrew; Pozidis, Haralampos; Despont, Michel

    2009-08-01

    Encapsulated conducting probes that can sustain high currents are used to study the nanoscale properties of thin-film stacks comprising of a phase-change chalcogenide, Ge(2)Sb(2)Te(5). Scaling studies on this promising candidate for random-access memory devices had thus far required extensive lithography and nanoscale growth. This seriously hampers rapid materials characterization. This article describes the use of two key techniques, an encapsulated conductive probe and its use in retraction mode, whereby the attractive force between tip and sample is used to maintain electrical contact. The effective transformation of nanoscale dots of amorphous Ge(2)Sb(2)Te(5) into the crystalline state is achieved and the electrical conductivity of the transformed structures is probed. The use of retraction force microscopy in a robust manner is demonstrated by reading the conductivity of the crystalline dots. Both these techniques could enable rapid electrical characterization of nanoscale materials, without extensive nanopatterning, thus reducing material development cycles. PMID:19725656

  12. 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.

  13. The antigen-induced degranulation of basophil leucocytes from atopic subjects, studied by phase-contrast microscopy

    PubMed Central

    Hastie, R.

    1971-01-01

    A type of microscopical chamber is described which enables monolayers of cells to be examined at 37°C by phase-contrast microscopy at high magnification and which can be perfused semi-automatically. Such chambers have been used to observe morphological changes in the basophil leucocytes of atopic subjects when challenged with an extract of Timothy grass pollen. The appearance of basophil leucocytes in monolayers prepared from both washed and defibrinated blood cell suspensions has been studied. Basophils taken from non-atopic subjects or atopic subjects who were not hypersensitive to grass pollen showed no reaction to Timothy grass pollen extract. By contrast, basophils taken from pollen sensitive atopic subjects reacted to Timothy grass pollen extract with an acute change in motility and many degranulated. The morphological changes observed are described and illustrated in detail. No significant changes were seen in other types of cell. Some immunological and cellular mechanisms which may underlie this degranulation of human basophil leucocytes are discussed. ImagesFIG. 2FIG. 3FIG. 4 PMID:4924942

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. Evaluation of the Dark-Medium Objective Lens in Counting Asbestos Fibers by Phase-Contrast Microscopy

    PubMed Central

    Lee, Eun Gyung; Nelson, John H.; Kashon, Michael L.; Harper, Martin

    2015-01-01

    the 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

  19. Multi-illumination Gabor holography recorded in a single camera snap-shot for high-resolution phase retrieval in digital in-line holographic microscopy

    NASA Astrophysics Data System (ADS)

    Sanz, Martin; Picazo-Bueno, Jose A.; Garcia, Javier; Micó, Vicente

    2015-05-01

    In this contribution we introduce MISHELF microscopy, a new concept and design of a lensless holographic microscope based on wavelength multiplexing, single hologram acquisition and digital image processing. The technique which name comes from Multi-Illumination Single-Holographic-Exposure Lensless Fresnel microscopy, is based on the simultaneous illumination and recording of three diffraction patterns in the Fresnel domain. In combination with a novel and fast iterative phase retrieval algorithm, MISHELF microscopy is capable of high-resolution (micron range) phase-retrieved (twin image elimination) biological imaging of dynamic events (video rate recording speed) since it avoids the time multiplexing needed for the in-line hologram sequence recording when using conventional phase-shifting or phase retrieval algorithms. MISHELF microscopy is validated using two different experimental layouts: one using RGB illumination and detection schemes and another using IRRB as illumination while keeping the RGB color camera as detection device. Preliminary experimental results are provided for both experimental layouts using a synthetic object (USAF resolution test target).

  20. 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

  1. High-resolution transmission electron microscopy study of electrically-driven reversible phase change in ge2sb2te5 nanowires.

    PubMed

    Jung, Yeonwoong; Nam, Sung-Wook; Agarwal, Ritesh

    2011-03-01

    By combining high-resolution transmission electron microscopy (HRTEM) characterization and electrical measurements on a unique device platform, we study the reversible electrically-driven phase-change characteristics of self-assembled Ge(2)Sb(2)Te(5) nanowires. Detailed HRTEM analyses are used to correlate and understand the effect of full and intermediate structural transformations on the measured electrical properties of the nanowire devices. The study demonstrates that our unique approach has the potential to provide new information regarding the dynamic structural and electrical states of phase-change materials at the nanoscale, which will aid the design of future phase-change memory devices. PMID:21271735

  2. Highly specific detection of Cryptosporidium spp. oocysts in human stool samples by undemanding and inexpensive phase contrast microscopy.

    PubMed

    Ignatius, Ralf; Klemm, Thomas; Zander, Steffen; Gahutu, Jean Bosco; Kimmig, Peter; Mockenhaupt, Frank P; Regnath, Thomas

    2016-03-01

    To compare phase contrast microscopy (PCM) of unstained slides for the detection of Cryptosporidium spp. oocysts with a commercially available enzyme immunoassay (EIA) for the detection of cryptosporidial antigen in human stool samples, we prospectively analysed by both methods 463 fresh human stool samples obtained from diarrhoeic patients between July and October 2014. Compared with the EIA, the sensitivity, specificity, positive and negative predictive value of PCM were 88.9 % (95 % confidence interval (CI), 66.0-98.1 %), 100 % (95 % CI, 99.0-100 %), 100 % (95 % CI, 77.3-100 %) and 99.6 % (95 % CI, 98.3-100 %), respectively. Additionally, we retrospectively examined with PCM 65 fixed stool samples that had been collected in 2010 from mostly asymptomatic Rwandan children <5 years of age; 14 of these samples had previously yielded positive results with a highly sensitive real-time (RT)-PCR. PCM detected cryptosporidia in 5/14 RT-PCR-positive samples, and notably, also in one of 51 RT-PCR-negative samples, which was subsequently confirmed by acid-fast staining. Positive and negative percent agreement of PCM with RT-PCR were 35.7 % (95 % CI, 16.2-61.4 %) and 98.0 % (95 % CI, 88.7-100 %), respectively. Positive PCM results were associated with higher RT-PCR cycle threshold values (p = 0.044). In conclusion, PCM offers a highly specific, undemanding and inexpensive method for the laboratory diagnosis of acute human cryptosporidiosis independent of the causative Cryptosporidium species. PMID:26646397

  3. Monitoring Rates and Heterogeneity of High-Pressure Germination of Bacillus Spores by Phase-Contrast Microscopy of Individual Spores

    PubMed Central

    Kong, Lingbo; Doona, Christopher J.; Setlow, Peter

    2014-01-01

    Germination of Bacillus spores with a high pressure (HP) of ∼150 MPa is via activation of spores' germinant receptors (GRs). The HP germination of multiple individual Bacillus subtilis spores in a diamond anvil cell (DAC) was monitored with phase-contrast microscopy. Major conclusions were that (i) >95% of wild-type spores germinated in 40 min in a DAC at ∼150 MPa and 37°C but individual spores' germination kinetics were heterogeneous; (ii) individual spores' HP germination kinetic parameters were similar to those of nutrient-triggered germination with a variable lag time (Tlag) prior to a period of the rapid release (ΔTrelease) of the spores' dipicolinic acid in a 1:1 chelate with Ca2+ (CaDPA); (iii) spore germination at 50 MPa had longer average Tlag values than that at ∼150 MPa, but the ΔTrelease values at the two pressures were identical and HPs of <10 MPa did not induce germination; (iv) B. subtilis spores that lacked the cortex-lytic enzyme CwlJ and that were germinated with an HP of 150 MPa exhibited average ΔTrelease values ∼15-fold longer than those for wild-type spores, but the two types of spores exhibited similar average Tlag values; and (v) the germination of wild-type spores given a ≥30-s 140-MPa HP pulse followed by a constant pressure of 1 MPa was the same as that of spores exposed to a constant pressure of 140 MPa that was continued for ≥35 min; (vi) however, after short 150-MPa HP pulses and incubation at 0.1 MPa (ambient pressure), spore germination stopped 5 to 10 min after the HP was released. These results suggest that an HP of ∼150 MPa for ≤30 s is sufficient to fully activate spores' GRs, which remain activated at 1 MPa but can deactivate at ambient pressure. PMID:24162576

  4. 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.

  5. Reducing depth induced spherical aberration in 3D widefield fluorescence microscopy by wavefront coding using the SQUBIC phase mask

    NASA Astrophysics Data System (ADS)

    Patwary, Nurmohammed; Doblas, Ana; King, Sharon V.; Preza, Chrysanthe

    2014-03-01

    Imaging thick biological samples introduces spherical aberration (SA) due to refractive index (RI) mismatch between specimen and imaging lens immersion medium. SA increases with the increase of either depth or RI mismatch. Therefore, it is difficult to find a static compensator for SA1. Different wavefront coding methods2,3 have been studied to find an optimal way of static wavefront correction to reduce depth-induced SA. Inspired by a recent design of a radially symmetric squared cubic (SQUBIC) phase mask that was tested for scanning confocal microscopy1 we have modified the pupil using the SQUBIC mask to engineer the point spread function (PSF) of a wide field fluorescence microscope. In this study, simulated images of a thick test object were generated using a wavefront encoded engineered PSF (WFEPSF) and were restored using space-invariant (SI) and depth-variant (DV) expectation maximization (EM) algorithms implemented in the COSMOS software4. Quantitative comparisons between restorations obtained with both the conventional and WFE PSFs are presented. Simulations show that, in the presence of SA, the use of the SIEM algorithm and a single SQUBIC encoded WFE-PSF can yield adequate image restoration. In addition, in the presence of a large amount of SA, it is possible to get adequate results using the DVEM with fewer DV-PSFs than would typically be required for processing images acquired with a clear circular aperture (CCA) PSF. This result implies that modification of a widefield system with the SQUBIC mask renders the system less sensitive to depth-induced SA and suitable for imaging samples at larger optical depths.

  6. Raman Spectroscopic Investigation of the Superionic Phase Transition in Cs3D(SO4)2

    NASA Astrophysics Data System (ADS)

    Matsumoto, Yoshiyuki; Kakuma, Takayuki; Muta, Shinnosuke

    2016-06-01

    The superionic phase transition of Cs3D(SO4)2 (TCDS) is investigated using Raman scattering and differential scanning calorimetry (DSC) measurements. It is confirmed that TCDS undergoes a superionic phase transition at 415.1 K. The result of the Raman scattering measurement at room temperature shows that TCDS does not form the dimer structure SO4⋯D⋯SO4. It suggests that this phase transition is not caused by the destruction of hydrogen bonds forming a dimer structure.

  7. Infrared optical properties of mixed-phase thin films studied by spectroscopic ellipsometry using boron nitride as an example

    NASA Astrophysics Data System (ADS)

    Schubert, M.; Rheinländer, B.; Franke, E.; Neumann, H.; Tiwald, T. E.; Woollam, J. A.; Hahn, J.; Richter, F.

    1997-11-01

    We present a microstructure-dependent anisotropic infrared-optical dielectric function model for mixed-phase polycrystalline material from which we derive the transverse and longitudinal-optical modes observable in thin films. Infrared ellipsometry over the wavelength range from 700 to 3000 cm-1 is then used to determine the phase and microstructure of polycrystalline and multilayered hexagonal and cubic boron nitride thin films deposited by magnetron sputtering onto (100) silicon. The ellipsometric data depend on the thin-film multilayer structure, the layer-phase composition, and the average orientation of the hexagonal grain c axes. In particular, we demonstrate the existence of spectral shifts of longitudinal optical phonons as a function of microstructure, i.e., the average grain crystallographic orientation within the mixed-phase material.

  8. Exploring the early dust-obscured phase of galaxy formation with blind mid-/far-infrared spectroscopic surveys

    NASA Astrophysics Data System (ADS)

    Bonato, M.; Negrello, M.; Cai, Z.-Y.; De Zotti, G.; Bressan, A.; Lapi, A.; Gruppioni, C.; Spinoglio, L.; Danese, L.

    2014-03-01

    While continuum imaging data at far-infrared to submillimetre wavelengths have provided tight constraints on the population properties of dusty star-forming galaxies up to high redshifts, future space missions like the Space Infrared Telescope for Cosmology and Astrophysics (SPICA) and ground-based facilities like the Cerro Chajnantor Atacama Telescope (CCAT) will allow detailed investigations of their physical properties via their mid-/far-infrared line emission. We present updated predictions for the number counts and the redshift distributions of star-forming galaxies spectroscopically detectable by these future missions. These predictions exploit a recent upgrade of evolutionary models, that include the effect of strong gravitational lensing, in the light of the most recent Herschel and South Pole Telescope data. Moreover the relations between line and continuum infrared luminosity are re-assessed, considering also differences among source populations, with the support of extensive simulations that take into account dust obscuration. The derived line luminosity functions are found to be highly sensitive to the spread of the line to continuum luminosity ratios. Estimates of the expected numbers of detections per spectral line by SPICA/SpicA FAR-infrared Instrument (SAFARI) and by CCAT surveys for different integration times per field of view at fixed total observing time are presented. Comparing with the earlier estimates by Spinoglio et al. we find, in the case of SPICA/SAFARI, differences within a factor of 2 in most cases, but occasionally much larger. More substantial differences are found for CCAT.

  9. Calorimetric and spectroscopic studies of the polymorphic phase behavior of a homologous series of n-saturated 1,2-diacyl phosphatidylethanolamines.

    PubMed Central

    Lewis, R N; McElhaney, R N

    1993-01-01

    The polymorphic phase behavior of a homologous series of n-saturated 1,2-diacyl phosphatidylethanolamines was investigated by differential scanning calorimetry, 31P-nuclear magnetic resonance, and Fourier transform infrared spectroscopy. Upon heating, aqueous dispersions of dried samples of the short- and medium-chain homologues (n < or = 17) exhibit single, highly energetic transitions from a dry, crystalline form to the fully hydrated, liquid-crystalline bilayer at temperatures higher than the lamellar gel-liquid-crystalline phase transition exhibited by fully hydrated samples. In contrast, the longer chain homologues (n > or = 18) first exhibit a transition from a dehydrated solid form to the hydrated L beta gel phase followed by the gel-liquid-crystalline phase transition normally observed with fully hydrated samples. The fully hydrated, aqueous dispersions of these lipids all exhibit reversible, fairly energetic gel-liquid-crystalline transitions at temperatures that are significantly higher than those of the corresponding phosphatidylcholines. In addition, at still higher temperatures, the longer chain members of this series (n > or = 16) exhibit weakly energetic transitions from the lamellar phase to an inverted nonlamellar phase. Upon appropriate incubation at low temperatures, aqueous dispersions of the shorter chain members of this homologous series (n < or = 16) form a highly ordered crystal-like phase that, upon heating, converts directly to the liquid-crystalline phase at the same temperature as do the aqueous dispersions of the dried lipid. The spectroscopic data indicate that unlike the n-saturated diacyl phosphatidylcholines, the stable crystal-like phases of this series of phosphatidylethanolamines describe an isostructural series in which the hydrocarbon chains are packed in an orthorhombic subcell and the headgroup and polar/apolar interfacial regions of the bilayer are effectively immobilized and substantially dehydrated. Our results suggest

  10. 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.

  11. 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.

  12. 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.

  13. 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. PMID:20964277

  14. Mechanochromism of piroxicam accompanied by intermolecular proton transfer probed by spectroscopic methods and solid-phase changes.

    PubMed

    Sheth, Agam R; Lubach, Joseph W; Munson, Eric J; Muller, Francis X; Grant, David J W

    2005-05-11

    Structural and solid-state changes of piroxicam in its crystalline form under mechanical stress were investigated using cryogenic grinding, powder X-ray diffractometry, diffuse-reflectance solid-state ultraviolet-visible spectroscopy, variable-temperature solid-state (13)C nuclear magnetic resonance spectroscopy, and solid-state diffuse-reflectance infrared Fourier transform spectroscopy. Crystalline piroxicam anhydrate exists as colorless single crystals irrespective of the polymorphic form and contains neutral piroxicam molecules. Under mechanical stress, these crystals become yellow amorphous piroxicam, which has a strong propensity to recrystallize to a colorless crystalline phase. The yellow color of amorphous piroxicam is attributed to charged piroxicam molecules. Variable-temperature solid-state (13)C NMR spectroscopy indicates that most of the amorphous piroxicam consists of neutral piroxicam molecules; the charged species comprise only about 8% of the amorphous phase. This ability to quantify the fractions of charged and neutral molecules of piroxicam in the amorphous phase highlights the unique capability of solid-state NMR to quantify mixtures in the absence of standards. Other compounds of piroxicam, which are yellow, are known to contain zwitterionic piroxicam molecules. The present work describes a system in which proton transfer accompanies both solid-state disorder and a change in color induced by mechanical stress, a phenomenon which may be termed mechanochromism of piroxicam. PMID:15869285

  15. 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.

  16. 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

  17. 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.

  18. Spectroscopic study of gas and surface phase chemistries of CF{sub 4} plasmas in an inductively coupled modified gaseous electronics conference reactor

    SciTech Connect

    Zhou Baosuo; Joseph, Eric A.; Overzet, Lawrence J.; Goeckner, Matthew J.

    2006-01-15

    Gas and surface phase chemistries of CF{sub 4} plasma were studied in an inductively coupled modified gaseous electronics conference reference cell, using in situ Fourier transform infrared spectroscopy enhanced by a multipass White cell and in situ spectroscopic ellipsometry. The self-bias dc voltage, densities of gaseous species, fluorocarbon film thickness on Si substrate, as well as etch rates of SiO{sub 2} and Si were measured during plasma processing as functions of the pressure, CF{sub 4} gas flow rate, rf source power, platen bias power, and source-platen gap. The gaseous molecules and radicals monitored included CF{sub 4}, CF{sub 3}, CF{sub 2}, SiF{sub 4}, and COF{sub 2}, among which CF{sub 4} and SiF{sub 4} were found to be the two dominant species, combining for about 80% of the total concentration. The density ratio of SiF{sub 4} and COF{sub 2} was about 2:1 with no bias on the substrate and increased up to {approx}8:1 when Si substrate etching took place. Specifically, as the Si etch rate increased, the COF{sub 2} density dropped, likely due to suppressed etching of the quartz source window, while the density of SiF{sub 4} increased. Comparisons between the gas phase data and etch rate results of Si and SiO{sub 2} indicate that the gas phase chemistry is strongly influenced by surface reactions on the substrate, wall, and quartz source window. The thickness of fluorocarbon reaction layer on Si substrate is mainly determined by densities of fluorocarbon radicals and fluorine atoms in the bulk plasma as well as the self-bias voltage on the substrate, and a thicker film is usually associated with a lower etch rate.

  19. Quantitative phase separation in multiferroic Bi0.88Sm0.12FeO3 ceramics via piezoresponse force microscopy

    NASA Astrophysics Data System (ADS)

    Alikin, D. O.; Turygin, A. P.; Walker, J.; Rojac, T.; Shvartsman, V. V.; Shur, V. Ya.; Kholkin, A. L.

    2015-08-01

    BiFeO3 (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 Pbam phases was detected by conventional X-ray diffraction (XRD); the non-polar Pnma or Pbnm 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.

  20. 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.

  1. 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.

  2. Spectroscopic, nonlinear optical and quantum chemical studies on Pyrrolidinium p-Hydroxybenzoate - A phase matchable organic NLO crystal

    NASA Astrophysics Data System (ADS)

    Shanmugam, G.; Belsley, M. S.; Isakov, D.; de Matos Gomes, E.; 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.

  3. 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. PMID:23792235

  4. 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.

  5. 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. PMID:23453272

  6. Application of maximum likelihood estimator in nano-scale optical path length measurement using spectral-domain optical coherence phase microscopy

    PubMed Central

    Motaghian Nezam, S. M. R.; Joo, C; Tearney, G. J.; de Boer, J. F.

    2009-01-01

    Spectral-domain optical coherence phase microscopy (SD-OCPM) measures minute phase changes in transparent biological specimens using a common path interferometer and a spectrometer based optical coherence tomography system. The Fourier transform of the acquired interference spectrum in spectral-domain optical coherence tomography (SD-OCT) is complex and the phase is affected by contributions from inherent random noise. To reduce this phase noise, knowledge of the probability density function (PDF) of data becomes essential. In the present work, the intensity and phase PDFs of the complex interference signal are theoretically derived and the optical path length (OPL) PDF is experimentally validated. The full knowledge of the PDFs is exploited for optimal estimation (Maximum Likelihood estimation) of the intensity, phase, and signal-to-noise ratio (SNR) in SD-OCPM. Maximum likelihood (ML) estimates of the intensity, SNR, and OPL images are presented for two different scan modes using Bovine Pulmonary Artery Endothelial (BPAE) cells. To investigate the phase accuracy of SD-OCPM, we experimentally calculate and compare the cumulative distribution functions (CDFs) of the OPL standard deviation and the square root of the Cramér-Rao lower bound (1/2SNR) over 100 BPAE images for two different scan modes. The correction to the OPL measurement by applying ML estimation to SD-OCPM for BPAE cells is demonstrated. PMID:18957999

  7. 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

  8. Ruthenium Trisbipyridine as a Candidate for Gas-Phase Spectroscopic Studies in a Fourier Transform Mass Spectrometer

    SciTech Connect

    Jill R. Scott; Jason E. Ham; Bill Durham; Paul L. Tremblay

    2004-02-01

    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 4×107 s-1, while the rate constant using SA was 1×107 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.

  9. Validation of diffuse correlation spectroscopic measurement of cerebral blood flow using phase-encoded velocity mapping magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Buckley, Erin M.; Hance, Dalton; Pawlowski, Thomas; Lynch, Jennifer; Wilson, Felice B.; Mesquita, Rickson C.; Durduran, Turgut; Diaz, Laura K.; Putt, Mary E.; Licht, Daniel J.; Fogel, Mark A.; Yodh, Arjun G.

    2012-03-01

    Diffuse correlation spectroscopy (DCS) is a novel optical technique that appears to be an excellent tool for assessing cerebral blood flow in a continuous and non-invasive manner at the bedside. We present new clinical validation of the DCS methodology by demonstrating strong agreement between DCS indices of relative cerebral blood flow and indices based on phase-encoded velocity mapping magnetic resonance imaging (VENC MRI) of relative blood flow in the jugular veins and superior vena cava. Data were acquired from 46 children with single ventricle cardiac lesions during a hypercapnia intervention. Significant increases in cerebral blood flow, measured both by DCS and by VENC MRI, as well as significant increases in oxyhemoglobin concentration, and total hemoglobin concentration, were observed during hypercapnia. Comparison of blood flow changes measured by VENC MRI in the jugular veins and by DCS revealed a strong linear relationship, R=0.88, p<0.001, slope=0.91+/-0.07. Similar correlations were observed between DCS and VENC MRI in the superior vena cava, R=0.77, slope=0.99+/-0.12, p<0.001. The relationship between VENC MRI in the aorta and DCS, a negative control, was weakly correlated, R=0.46, slope=1.77+/-0.45, p<0.001.

  10. 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.

  11. 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.

  12. High resolution transmission electron microscopy study of the hardening mechanism through phase separation in a beta-Ti-35Nb-7Zr-5Ta alloy for implant applications.

    PubMed

    Afonso, Conrado R M; Ferrandini, Peterson L; Ramirez, Antonio J; Caram, Rubens

    2010-04-01

    beta-Ti alloys are highly attractive metallic materials for biomedical applications due to their high specific strength, high corrosion resistance and excellent biocompatibility, including low elastic modulus. This work aims to clarify the hardening mechanism of a beta-Ti-Nb-Zr-Ta alloy using different characterization techniques. Ingots (50 g) of Ti-35Nb-7Zr-5Ta (wt.%) alloy were arc furnace melted in an Ar((g)) atmosphere, homogenized, hot rolled, solubilized and finally aged at several temperatures from 200 to 700 degrees C for 4 h. Microstructure characterization was performed using X-ray diffraction, optical microscopy, scanning and high resolution transmission electron microscopy (HR-TEM). The 4 h aging showed that the highest hardness values were found when aged at 400 degrees C and the HR-TEM images confirmed splitting of spots on the Fourier space map, which indicated the presence of a coherent interface between separated phases (beta and beta') and explains the hardening mechanism of the alloy. Through geometric phase analysis analysis, using the HR-TEM image, the localized strain map showed 5-10 nm domains of the beta and beta' phases. The combination of suitable values of yield strength, hardness and low Young's modulus makes Ti-35Nb-7Zr-5Ta alloy suitable for medical applications as a metallic orthopedic implant. PMID:19913645

  13. 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

  14. 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.

  15. Observation of amplitude and phase in ridge and photonic crystal waveguides operating at 1.55 microm by use of heterodyne scanning near-field optical microscopy.

    PubMed

    Tortora, P; Abashin, M; Märki, I; Nakagawa, W; Vaccaro, L; Salt, M; Herzig, H P; Levy, U; Fainman, Y

    2005-11-01

    We apply heterodyne scanning near-field optical microscopy (SNOM) to observe with subwavelength resolution the amplitude and phase of optical fields propagating in several microfabricated waveguide devices operating around the 1.55 microm wavelength. Good agreement between the SNOM measurements and predicted optical mode propagation characteristics in standard ridge waveguides demonstrates the validity of the method. In situ observation of the subwavelength-scale distribution and propagation of optical fields in straight and 90 degrees bend photonic crystal waveguides facilitates a more detailed understanding of the optical performance characteristics of these devices and illustrates the usefulness of the technique for investigating nanostructured photonic devices. PMID:16279458

  16. 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.

  17. Spectroscopic characterization of nitroaromatic landmine signature explosives

    NASA Astrophysics Data System (ADS)

    Hernandez-Rivera, Samuel P.; Manrique-Bastidas, Cesar A.; Blanco, Alejandro; Primera, Oliva M.; Pacheco, Leonardo C.; Castillo-Chara, Jairo; Castro, Miguel E.; Mina, Nairmen

    2004-09-01

    TNT and DNT are important explosives used as base charges of landmines and other explosive devices. They are often combined with RDX in specific explosive formulations. Their detection in vapor phase as well as in soil in contact with the explosives is important in landmine detection technology. The spectroscopic signatures of nitroaromatic compounds in neat forms: crystals, droplets, and recrystallized samples were determined by Raman Microspectroscopy (RS), Fourier Transform Infrared Microscopy (FTIR) and Fiber Optics Coupled - Fourier Transform Infrared Spectroscopy (FOC-FTIR) using a grazing angle (GA) probe. TNT exhibits a series of characteristic bands: vibrational signatures, which allow its detection in soil. The spectroscopic signature of neat TNT is dominated by strong bands about 1380 and 2970 cm-1. The intensity and position of these bands were found remarkably different in soil samples spiked with TNT. The 1380 cm-1 band is split into a number of bands in that region. The 2970 cm-1 band is reduced in intensity and new bands are observed about 2880 cm-1. The results are consistent with a different chemical environment of TNT in soil as compared to neat TNT. Interactions were found to be dependent on the physical source of the explosive. In the case of DNT-sand interactions, shifts in vibrational frequencies of the explosives as well as the substrates were found.

  18. Amplitude-modulated atomic force microscopy reveals the near surface nanostructure of surfactant sponge (L(3)) and lamellar (L(α)) phases.

    PubMed

    Wydro, Marc J; Warr, Gregory G; Atkin, Rob

    2015-05-19

    Amplitude-modulated atomic force microscopy (AM-AFM) has been used to study the nanostructure of cetylpyridinium chloride (CPCl)-hexanol-0.2 M NaCl sponge (L3) and lamellar (Lα) phases near a mica surface. For both phases, membrane volume fractions of 22, 27, and 32 vol % were investigated, with the L3 or Lα phase selected by adjusting the co-surfactant/surfactant ratio (hexanol/CPCl). For the L3 phase, the presence of the surface flattens the three-dimensional bulk structure. AM-AFM clearly resolves the membrane and solvent passages in the near surface layer. Increasing the membrane volume fraction decreases the size of the image features because of the lower solvent content. Within error, the average passage sizes in the near surface layer are the same as those in the bulk at the same concentration. Images of the Lα phase reveal undulating near surface sheets. At the highest membrane concentration, the image is very smooth, because the lamellar sheet is confined between the surface and the next near surface layer, which is in close proximity as a result of the low solvent content. As the membrane concentration is reduced, the space between layers is increased and undulations appear in the near surface lamellar structure. Undulations are more pronounced at the lowest membrane volume fraction. PMID:25906083

  19. 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

  20. Hybrid random walk-linear discriminant analysis method for unwrapping quantitative phase microscopy images of biological samples.

    PubMed

    Kim, Diane N H; Teitell, Michael A; Reed, Jason; Zangle, Thomas A

    2015-01-01

    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

  1. Hybrid random walk-linear discriminant analysis method for unwrapping quantitative phase microscopy images of biological samples

    NASA Astrophysics Data System (ADS)

    Kim, Diane N. H.; Teitell, Michael A.; Reed, Jason; Zangle, Thomas A.

    2015-11-01

    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.

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. Interband electronic transitions and phase transformation of multiferroic Bi1-xLaxFe1-yTiyO3 ceramics revealed by temperature-dependent spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Xu, L. P.; Zhang, L. L.; Jiang, P. P.; Yu, J.; Duan, Z. H.; Hu, Z. G.; Zhu, Z. Q.; Chu, J. H.

    2013-12-01

    Optical properties and phase transition of Bi1-xLaxFe1-yTiyO3 (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 ɛ1 increases with the temperature. Meanwhile, the imaginary part ɛ2 in the low-energy region decreases with the temperature and has an opposite trend in the high-energy side. Four typical interband transitions (Ea ˜ 2.50 eV, Eb ˜ 2.70 eV, Ec ˜ 3.60 eV, and Ed ˜ 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 Fe3+ ions with nonmagnetic Ti4+ ions can reduce the exchange interaction between adjacent magnetic moments. Therefore, SE technique can be sensitive for detecting the phase/structural transitions of multiferroic oxides.

  7. 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. PMID:26890087

  8. Fluorescence Microscopy

    PubMed Central

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

    2016-01-01

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

  9. Structure refinement of the δ1p phase in the Fe–Zn system by single-crystal X-ray diffraction combined with scanning transmission electron microscopy

    PubMed Central

    Okamoto, Norihiko L.; Tanaka, Katsushi; Yasuhara, Akira; Inui, Haruyuki

    2014-01-01

    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. PMID:24675597

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Interferometer-based structured-illumination microscopy utilizing complementary phase relationship through constructive and destructive image detection by two cameras.

    PubMed

    Shao, L; Winoto, L; Agard, D A; Gustafsson, M G L; Sedat, J W

    2012-06-01

    In an interferometer-based fluorescence microscope, a beam splitter is often used to combine two emission wavefronts interferometrically. There are two perpendicular paths along which the interference fringes can propagate and normally only one is used for imaging. However, the other path also contains useful information. Here we introduced a second camera to our interferometer-based three-dimensional structured-illumination microscope (I(5)S) to capture the fringes along the normally unused path, which are out of phase by π relative to the fringes along the other path. Based on this complementary phase relationship and the well-defined phase interrelationships among the I(5)S data components, we can deduce and then computationally eliminate the path length errors within the interferometer loop using the simultaneously recorded fringes along the two imaging paths. This self-correction capability can greatly relax the requirement for eliminating the path length differences before and maintaining that status during each imaging session, which are practically challenging tasks. Experimental data is shown to support the theory. PMID:22472010

  15. 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)

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Phase evolution in single-crystalline LiFePO4 followed by in situ scanning X-ray microscopy of a micrometre-sized battery

    NASA Astrophysics Data System (ADS)

    Ohmer, Nils; Fenk, Bernhard; Samuelis, Dominik; Chen, Chia-Chin; Maier, Joachim; Weigand, Markus; Goering, Eberhard; Schütz, Gisela

    2015-01-01

    LiFePO4 is one of the most frequently studied positive electrode materials for lithium-ion batteries during the last years. Nevertheless, there is still an extensive debate on the mechanism of phase transformation. On the one hand this is due to the small energetic differences involved and hence the great sensitivity with respect to parameters such as size and morphology. On the other hand this is due to the lack of in situ observations with appreciable space and time resolution. Here we present scanning transmission X-ray microscopy measurements following in situ the phase boundary propagation within a LiFePO4 single crystal along the (010) orientation during electrochemical lithiation/delithiation. We follow, on a battery-relevant timescale, the evolution of a two-phase-front on a micrometre scale with a lateral resolution of 30 nm and with minutes of time resolution. The growth pattern is found to be dominated by elastic effects rather than being transport-controlled.

  1. Atomic force microscopy on phase-control pulsed force mode in water: Imaging and force analysis on a rhodium-octaethylporphyrin layer on highly oriented pyrolytic graphite

    NASA Astrophysics Data System (ADS)

    Maeda, Yasushi; Yamazaki, Shin-ichi; Kohyama, Masanori

    2014-06-01

    We developed phase-control pulsed force mode (p-PFM) as the operation mode for atomic force microscopy (AFM). The p-PFM allowed us to observe soft or weakly adsorbed materials in a liquid environment using a conventional AFM apparatus, and allowed for force curve mapping (FCM) after offline data processing. We applied the p-PFM to a rhodium-octaethylporphyrin (RhOEP) layer on highly oriented pyrolytic graphite (HOPG), which is applicable to anode catalysts of fuel cells. The RhOEP/HOPG system was stably observed in water by this mode. In the p-PFM image, we found both large and small protrusions, which were not observed in the dynamic force mode, in air. The detailed force analysis suggested that these protrusions are nanobubbles located on the HOPG substrate exposed in holes or pits of the RhOEP layer.

  2. 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.

  3. [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. PMID:23705464

  4. Unbiased characterization of three-phase microstructure of porous lanthanum doped strontium manganite/yttria-stabilized zirconia composite cathodes for solid oxide fuel cells using atomic force microscopy and stereology

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Lynch, M.; Gokhale, A. M.; Liu, M.

    Microstructural characteristics of porous LSM/YSZ composite cathodes greatly influence the performance of solid oxide fuel cells. The triple phase boundaries, for example, account for a significant portion of the electrochemically active sites in these porous composite cathodes. Nonetheless, experimental characterization of the relevant microstructural attributes has been problematic due to lack of suitable microscopy techniques for simultaneous observations of all three phases (i.e., LSM, YSZ, and porosity) needed for identification and unbiased characterization of the triple phase boundaries. In this contribution it is shown that a combination of chemical etching and atomic force microscopy clearly reveals all three phases and the triple phase junctions in the microstructural sections. Further, stereological techniques based on the geometric probabilities of stochastic geometry enable unbiased statistical estimation of total triple phase boundary length per unit volume and other microstructural attributes from simple counting measurements performed on representative microstructural sections.

  5. Spectroscopic methods in gas hydrate research.

    PubMed

    Rauh, Florian; Mizaikoff, Boris

    2012-01-01

    Gas hydrates are crystalline structures comprising a guest molecule surrounded by a water cage, and are particularly relevant due to their natural occurrence in the deep sea and in permafrost areas. Low molecular weight molecules such as methane and carbon dioxide can be sequestered into that cage at suitable temperatures and pressures, facilitating the transition to the solid phase. While the composition and structure of gas hydrates appear to be well understood, their formation and dissociation mechanisms, along with the dynamics and kinetics associated with those processes, remain ambiguous. In order to take advantage of gas hydrates as an energy resource (e.g., methane hydrate), as a sequestration matrix in (for example) CO(2) storage, or for chemical energy conservation/storage, a more detailed molecular level understanding of their formation and dissociation processes, as well as the chemical, physical, and biological parameters that affect these processes, is required. Spectroscopic techniques appear to be most suitable for analyzing the structures of gas hydrates (sometimes in situ), thus providing access to such information across the electromagnetic spectrum. A variety of spectroscopic methods are currently used in gas hydrate research to determine the composition, structure, cage occupancy, guest molecule position, and binding/formation/dissociation mechanisms of the hydrate. To date, the most commonly applied techniques are Raman spectroscopy and solid-state nuclear magnetic resonance (NMR) spectroscopy. Diffraction methods such as neutron and X-ray diffraction are used to determine gas hydrate structures, and to study lattice expansions. Furthermore, UV-vis spectroscopic techniques and scanning electron microscopy (SEM) have assisted in structural studies of gas hydrates. Most recently, waveguide-coupled mid-infrared spectroscopy in the 3-20 μm spectral range has demonstrated its value for in situ studies on the formation and dissociation of gas

  6. 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.

  7. 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.

  8. Ferroelectric domain structures in SrBi2Nb2O9 epitaxial thin films: Electron microscopy and phase-field simulations

    NASA Astrophysics Data System (ADS)

    Li, Y. L.; Chen, L. Q.; Asayama, G.; Schlom, D. G.; Zurbuchen, M. A.; Streiffer, S. K.

    2004-06-01

    Ferroelectric domain structures of (001)SrBi2Nb2O9 epitaxial films, investigated using both transmission electron microscopy and phase-field simulations, are reported. Experiment and numerical simulation both reveal that the domain structures consist of irregularly shaped domains with curved domain walls. It is shown that the elastic contribution to domain structures can be neglected in SrBi2Nb2O9 due to its small ferroelastic distortion, less than 0.0018%. Two-beam dark-field imaging using reflections unique to domains of each of the two 90° polarization axes reveal the domain structure. Phase-field simulation is based on the elastic and electrostatic solutions obtained for thin films under different mechanical and electric boundary conditions. The effects of ferroelastic distortion and dielectric constant on ferroelectric domains are systematically analyzed. It is demonstrated that electrostatic interactions which favor straight domain walls are not sufficient to overcome the domain wall energy which favors curved domains in SrBi2Nb2O9.

  9. Temperature-depending growth and surface structures of low-coverage Al phases on Si(100) observed by scanning tunneling microscopy

    NASA Astrophysics Data System (ADS)

    Itoh, H.; Itoh, J.; Schmid, A.; Ichinokawa, T.

    1994-02-01

    The surface structures of Al on the Si(100) surface, at coverages less than one monolayer deposited at various temperatures, were studied by scanning tunneling microscopy (STM). Surface structures of 2 × 2 and 2 × 3 phases formed at temperatures below 350°C consist of Al-dimer lines with the dimerization parallel to that of the Si-dimers. From the STM images, we can find that a filled state of Al-Si backbonds and an empty state of Al-Al dimer bonds are observed prominently at about -3 and +1 eV at positions on the Si-dimer rows and between the Si-dimer rows, respectively. For deposition above 500°C, the Al-dimer lines change into molecular clusters, each one of them consisting of five or six Al atoms. These molecules form the c(4 × 2 n) structure with buckling of underlying Si-dimer rows. At the same time, two-dimensional (2D) Si and Al islands with 2 × 1 and 2 × 2 structures were formed in the second layer on the c(4 × 2 n) structure. The local structures of the low-coverage Al phases on Si(100), depending on the deposition temperature and coverage, are analyzed by STM.

  10. 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

  11. Correlative Microscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microscopy and Imaging offers many opportunities to collaborate and cooperate with scientists in many different fields nationally and internationally. Images have proven to be very important components in basic research, product development and understanding structure/function relationships in addit...

  12. Phase evolution in {sup 57}Fe/Al multilayers studied through dc magnetization, conversion electron Moessbauer spectroscopy, and transmission electron microscopy

    SciTech Connect

    Jani, Snehal; Lakshmi, N.; Venugopalan, K.; Sebastian, Varkey; Reddy, V. R.; Gupta, Ajay; Lalla, N. P.

    2008-12-15

    Fe/Al multilayer thin films with an overall atomic concentration ratio of Fe:Al=1:2 have been prepared by ion-beam sputtering. Phase formation and microstructural evolution with thermal annealing have been studied by x-ray reflectivity, cross-sectional transmission electron microscopy, dc magnetization, and conversion electron Moessbauer spectroscopy. These studies show that although the starting composition is Al rich, the intermixing of Fe and Al at the interfaces leads to the formation of a magnetic Fe{sub 3}Al-like region at the interface. Thus, the magnetic contribution in the as-deposited multilayer structure (MLS) is not only from pure Fe but also from an Fe{sub 3}Al-like region formed at the interface. On annealing the MLS, a stable nonmagnetic MLS consisting of intermetallic B2Fe{sub 50}Al{sub 50} separated by thin Al layers is formed. Further annealing only induces better ordering of Fe{sub 50}Al{sub 50} and does not destroy the MLS.

  13. 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.

  14. 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

  15. 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

  16. 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

  17. Accurate calculations on 9 Λ-S and 28 Ω states of NSe radical in the gas phase: potential energy curves, spectroscopic parameters and spin-orbit couplings.

    PubMed

    Shi, Deheng; Li, Peiling; Sun, Jinfeng; Zhu, Zunlue

    2014-01-01

    The potential energy curves (PECs) of 28 Ω states generated from 9 Λ-S states (X(2)Π, 1(4)Π, 1(6)Π, 1(2)Σ(+), 1(4)Σ(+), 1(6)Σ(+), 1(4)Σ(-), 2(4)Π and 1(4)Δ) are studied for the first time using an ab initio quantum chemical method. All the 9 Λ-S states correlate to the first two dissociation limits, N((4)Su)+Se((3)Pg) and N((4)Su)+Se((3)Dg), of NSe radical. Of these Λ-S states, the 1(6)Σ(+), 1(4)Σ(+), 1(6)Π, 2(4)Π and 1(4)Δ are found to be rather weakly bound states. The 1(2)Σ(+) is found to be unstable and has double wells. And the 1(6)Σ(+), 1(4)Σ(+), 1(4)Π and 1(6)Π are found to be the inverted ones with the SO coupling included. The PEC calculations are made by the complete active space self-consistent field method, which is followed by the internally contracted multireference configuration interaction approach with the Davidson modification. The spin-orbit coupling is accounted for by the state interaction approach with the Breit-Pauli Hamiltonian. The convergence of the present calculations is discussed with respect to the basis set and the level of theory. Core-valence correlation corrections are included with a cc-pCVTZ basis set. Scalar relativistic corrections are calculated by the third-order Douglas-Kroll Hamiltonian approximation at the level of a cc-pV5Z basis set. All the PECs are extrapolated to the complete basis set limit. The variation with internuclear separation of spin-orbit coupling constants is discussed in brief for some Λ-S states with one shallow well on each PEC. The spectroscopic parameters of 9 Λ-S and 28 Ω states are determined by fitting the first ten vibrational levels whenever available, which are calculated by solving the rovibrational Schrödinger equation with Numerov's method. The splitting energy in the X(2)Π Λ-S state is determined to be about 864.92 cm(-1), which agrees favorably with the measurements of 891.80 cm(-1). Moreover, other spectroscopic parameters of Λ-S and Ω states involved here are

  18. Expansion Microscopy

    PubMed Central

    Chen, Fei; Tillberg, Paul W.; Boyden, Edward S.

    2014-01-01

    In optical microscopy, fine structural details are resolved by using refraction to magnify images of a specimen. Here we report the discovery that, by synthesizing a swellable polymer network within a specimen, it can be physically expanded, resulting in physical magnification. By covalently anchoring specific labels located within the specimen directly to the polymer network, labels spaced closer than the optical diffraction limit can be isotropically separated and optically resolved, a process we call expansion microscopy (ExM). Thus, this process can be used to perform scalable super-resolution microscopy with diffraction-limited microscopes. We demonstrate ExM with effective ~70 nm lateral resolution in both cultured cells and brain tissue, performing three-color super-resolution imaging of ~107 μm3 of the mouse hippocampus with a conventional confocal microscope. PMID:25592419

  19. 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

  20. Intravital microscopy

    PubMed Central

    Masedunskas, Andrius; Milberg, Oleg; Porat-Shliom, Natalie; Sramkova, Monika; Wigand, Tim; Amornphimoltham, Panomwat; Weigert, Roberto

    2012-01-01

    Intravital microscopy is an extremely powerful tool that enables imaging several biological processes in live animals. Recently, the ability to image subcellular structures in several organs combined with the development of sophisticated genetic tools has made possible extending this approach to investigate several aspects of cell biology. Here we provide a general overview of intravital microscopy with the goal of highlighting its potential and challenges. Specifically, this review is geared toward researchers that are new to intravital microscopy and focuses on practical aspects of carrying out imaging in live animals. Here we share the know-how that comes from first-hand experience, including topics such as choosing the right imaging platform and modality, surgery and stabilization techniques, anesthesia and temperature control. Moreover, we highlight some of the approaches that facilitate subcellular imaging in live animals by providing numerous examples of imaging selected organelles and the actin cytoskeleton in multiple organs. PMID:22992750

  1. Synthesis and spectroscopic characterization of nanostructured anatase titania: A photocatalyst

    SciTech Connect

    Porkodi, K. . E-mail: porkodikathirvel@yahoo.com; Arokiamary, S. Daisy

    2007-06-15

    Nanocrystalline TiO{sub 2} was synthesized by the sol-gel process by controlling the crystallite size through calcination. The resulting nanocrystals were characterized using XRD, FT-Raman, SEM/EDX, DSC/TGA and UV-Vis spectroscopic techniques. XRD patterns confirmed the presence of only pure 100% anatase phase TiO{sub 2}. The surface morphology of the nanotitania was evaluated with Scanning Electron Microscopy. The purity of the sol-gel-derived TiO{sub 2} was confirmed through EDX measurements. The band gap of the nanotitania was found to be 3.6 eV from UV-Vis measurements. The pHzpc of the titania sample was measured as 5.90.

  2. Alpha phase precipitation from phase-separated beta phase in a model Ti-Mo-Al alloy studied by direct coupling of transmission electron microscopy and atom probe tomography

    SciTech Connect

    Devaraj, Arun; Nag, Soumya; Banerjee, Rajarshi

    2013-10-19

    The benefit of direct coupling of APT with TEM dark field imaging to investigate early stages of phase transformation in multicomponent alloys is demonstrated by analyzing alpha phase precipitated in a model Ti-10 at% Mo-10 at% Al alloy during annealing at 400oC. Through such a direct coupling approach a thermodynamically unexpected solute partitioning trend between beta matrix and alpha precipitate is observed in the early stages of precipitation, which is explained based on possible nucleation of alpha phase in the Ti rich (Mo and Al depleted regions) created as a result of phase separation in beta matrix. On further higher temperature annealing at 600oC for 1 hour, the alpha precipitates were shown to grow and get enriched in Al and further depleted in Mo reaching the thermodynamic equilibrium.

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. Multivariate Analysis of Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopic Data to Confirm Phase Partitioning in Methacrylate-Based Dentin Adhesive

    PubMed Central

    Ye, Qiang; Parthasarathy, Ranganathan; Abedin, Farhana; Laurence, Jennifer S.; Misra, Anil; Spencer, Paulette

    2014-01-01

    Water is ubiquitous in the mouths of healthy individuals and is a major interfering factor in the development of a durable seal between the tooth and composite restoration. Water leads to the formation of a variety of defects in dentin adhesives; these defects undermine the tooth-composite bond. Our group recently analyzed phase partitioning of dentin adhesives using high-performance liquid chromatography (HPLC). The concentration measurements provided by HPLC offered a more thorough representation of current adhesive performance and elucidated directions to be taken for further improvement. The sample preparation and instrument analysis using HPLC are, however, time-consuming and labor-intensive. The objective of this work was to develop a methodology for rapid, reliable, and accurate quantitative analysis of near-equilibrium phase partitioning in adhesives exposed to conditions simulating the wet oral environment. Analysis by Fourier transform infrared (FT-IR) spectroscopy in combination with multivariate statistical methods, including partial least squares (PLS) regression and principal component regression (PCR), were used for multivariate calibration to quantify the compositions in separated phases. Excellent predictions were achieved when either the hydrophobic-rich phase or the hydrophilic-rich phase mixtures were analyzed. These results indicate that FT-IR spectroscopy has excellent potential as a rapid method of detection and quantification of dentin adhesives that experience phase separation under conditions that simulate the wet oral environment. PMID:24359662

  9. Positron microscopy

    SciTech Connect

    Hulett, L.D. Jr.; Xu, J.

    1995-02-01

    The negative work function property that some materials have for positrons make possible the development of positron reemission microscopy (PRM). Because of the low energies with which the positrons are emitted, some unique applications, such as the imaging of defects, can be made. The history of the concept of PRM, and its present state of development will be reviewed. The potential of positron microprobe techniques will be discussed also.

  10. 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

  11. Calorimetric, spectroscopic and structural investigations of phase polymorphism in [Ru(NH3)6](BF4)3. Part I

    NASA Astrophysics Data System (ADS)

    Dołęga, Diana; Mikuli, Edward; Inaba, Akira; Górska, Natalia; Hołderna-Natkaniec, Krystyna; Nitek, Wojciech

    2013-01-01

    Four crystalline phases of the coordination compound [Ru(NH3)6](BF4)3 are identified by adiabatic calorimetry. Three phase transitions, one at TC3(IV→III)=30.7 K, the second at TC2(III→II)=91.7 K (both accompanied by comparable entropy changes 3.0 and 3.1 J K-1 mol-1, respectively) and the third at TC1(II→I)=241.6 K (accompanied by an entropy change of 8.1 J K-1 mol-1) were discovered. X-ray single crystal diffraction (at 293 K) demonstrates that phase I is a highly dynamic disordered cubic phase (Fm3¯m, No. 225) with two types of BF4- anions differing in a degree of disorder. In phase II (at 170 K) the structure remains cubic (Ia3¯, No. 206), with two different types of cations and four different types of anions. Splitting of certain IR bands connected with NH3 ligands at the observed phase transitions suggests a lowering of the symmetry of the [Ru(NH3)6]3+ complex cation. Both NH3 ligands and BF4- anions perform fast reorientations (τR≈10-12 s), which are significantly slowed down below the phase transition at TC3. 1H NMR studies led to estimate the values of the activation energy of NH3 ligands reorientation in the phases II and I as equal to ˜8 kJ mol-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 ˜24 kJ mol-1. 19F NMR studies give the values of the activation energy of BF4- anions reorientation as ˜6 kJ mol-1. Above the phase transition temperature half of BF4- anions perform a tumbling motion with Ea≈8 kJ mol-1.

  12. 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

  13. 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

  14. 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.

  15. 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. PMID:25833573

  16. Electronic phase transitions in f-electron metals at high pressures: Synchrotron x-ray spectroscopic studies on Gd to 100 GPa

    SciTech Connect

    Choong-Shik, Yoo; Maddox, Brian; Iota, Valentin

    2011-11-11

    Unusual phase transitions driven by electron correlation effects occur in many f-electron metals (lanthanides and actinides alike) from localized phases to itinerant phases at high pressures. The dramatic changes in atomic volumes and crystal structures associated with some of these transitions signify equally important changes in the underlying electronic structure of these correlated f-electron metals. Yet, the relationships among the crystal structure, electronic correlation and electronic structure in f-electron metals have not been well understood. In this study, utilizing recent advances in third generation synchrotron x-ray spectroscopies and high-pressure diamond-anvil cell technologies, we describe the pressure-induced spectral changes across the volume collapse transition in Gd at 60 GPa and well above. The spectral results suggest that the f- electrons of high-pressure Gd phases are highly correlated even at 100 GPa - consistent with the Kondo volume collapse model and the recent experimental evidence of strong electron correlation of {alpha}-Ce.

  17. 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

  18. Synthesis of few layer graphene by direct exfoliation of graphite and a Raman spectroscopic study

    SciTech Connect

    Gayathri, S.; Jayabal, P.; Ramakrishnan, V.; Kottaisamy, M.

    2014-02-15

    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.

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. Analysis of Urinary Calculi Using Infrared Spectroscopic Imaging

    NASA Astrophysics Data System (ADS)

    Sablinskas, Valdas; Lesciute, Daiva; Hendrixson, Vaiva

    2009-06-01

    Kidney stone disease is a cosmopolitan disease, occurring in both industrialized and developing countries and mainly affecting adults aged 2060 years. The formation of kidney stones is a process that includes many factors. Its primary and contributing pathogenic factors are genetic, nutritional and environmental, but also include personal habits. Information about the chemical structure of kidney stones is of great importance to the treatment of the kidney diseases. The usefulness of such information was first recognized in early 1950s. Analysis of urinary stones by various chemical methods, polarization microscopy, x-ray diffraction, porosity determination, solid phase NMR, and thermo analytical procedures have been widely used. Unfortunately, no one method is sufficient to provide all the clinically useful information about the structure and composition of the stones. Infrared spectroscopy can be considered a relatively new method of kidney stone analysis. It allows to identify any organic or inorganic molecules the constituents of kidney stones. So far this method had never been used to collect information about kidney stone component patterns in Lithuania. Since no epidemiological studies have been performed in this field, the medical treatment of kidney stone disease is empirical and often ineffective in hospitals around the country. The aim of this paper is to present some results of analysis of kidney stones extracted from local patients using FTIR spectroscopical microscopy.

  5. Scattering and Spectroscopic Study on the Hydration and Phase Behavior of Aqueous Alcohol Ethoxylate and Methyl Ester Ethoxylate: Effects of Terminal Groups in Hydrophilic Chains.

    PubMed

    Sato, Takaaki; Akahane, Takesi; Amano, Kenshi; Hyodo, Ryo; Yanase, Keiichi; Ogura, Taku

    2016-06-23

    Using dielectric relaxation spectroscopy (DRS), small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and viscometry, we have investigated the hydration behavior, static structures, Brownian dynamics, and mechanical properties of aqueous solutions of alcohol ethoxylate (C12E15) and methyl ester ethoxylate (C12MEE), hereafter abbreviated as AE and MEE, respectively, in which we especially focus on the effects of the endcaps of these nonionic surfactants. We find that AE and MEE exhibit fairly different phase behaviors in water: AE produces liquid crystalline phases at w (surfactant weight fraction) > 0.35, whereas MEE retains a liquid phase in an extremely wide concentration range (w < 0.7) at ambient temperature. The structure factor deduced from SAXS intensities using a generalized indirect Fourier transformation technique and the effective hydration number evaluated from the negative excess bulk water relaxation amplitude revealed by DRS unambiguously demonstrate that hydration water molecules, exhibiting about 4-times-slower collective reorientational dynamics than that of bulk water, contribute to the excluded volume of the micelles. The blocked terminal hydrogen-bond donor/acceptor site of MEE leads to smaller hydration number of MEE than compared to that of AE, and consequently the lower excluded volume of the MEE micelles. The effective micellar volume fraction, ϕ(eff), should be defined by incorporating such different hydration effects. Importantly, voluminosity, defined as the micellar volume fraction per unit mass, is clearly a decreasing function of w, demonstrating progressive dehydration at a higher w. The collective diffusion constants determined by DLS for the AE and MEE micelles show a monotonous increase up to ϕ(eff) ≈ 0.5, as expected for the hard spheres. Low-shear-rate viscosities follow a Krieger-Dougherty model in the identical micellar packing fraction range. All static, dynamic, and mechanical properties of these micellar

  6. Spectroscopic and electrochemical studies on the interaction of an inclusion complex of β-cyclodextrin with 2,6-dinitrophenol in aqueous and solid phases

    NASA Astrophysics Data System (ADS)

    Srinivasan, K.; Stalin, T.; Shanmugapriya, A.; Sivakumar, K.

    2013-03-01

    The inclusion complex of 2,6-dinitrophenol (2,6-DNP) with β-cyclodextrin (β-CD) in solution phase was studied by UV-visible spectrophotometer and electrochemical (cyclic voltammetry) methods. The prototropic behaviors of 2,6-DNP were studied. The binding constant of 'β-CD:2,6-DNP' inclusion complex was calculated using Benesi-Hildebrand plot at 303 K. Thermodynamic parameter (ΔG) involved in the complex formation also calculated. It indicates that the reaction is spontaneous and exergonic process. Formation of solid inclusion complex between β-CD and 2,6-DNP was characterized by 1H NMR, FT-IR, XRD techniques and SEM morphological studies. The β-CD:2,6-DNP inclusion complex obtained by molecular docking studies is in good correlation with the results obtained through experimental methods.

  7. 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

    NASA Astrophysics Data System (ADS)

    Li, Yan Jun; Lee, Seung Hwan; Kinoshita, Yukinori; Ma, Zong Min; Wen, Huanfei; Nomura, Hikaru; Naitoh, Yoshitaka; Sugawara, Yasuhiro

    2016-05-01

    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.

  8. 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. PMID:27067038

  9. 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.

  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. Spectroscopic ellipsometry studies on the m-plane Al1‑ x In x N epilayers grown by metalorganic vapor phase epitaxy on a freestanding GaN substrate

    NASA Astrophysics Data System (ADS)

    Kojima, Kazunobu; Kagaya, Daiki; Yamazaki, Yoshiki; Ikeda, Hirotaka; Fujito, Kenji; Chichibu, Shigefusa F.

    2016-05-01

    Dispersion relationships of the refractive index and extinction coefficient of m-plane Al1‑ x In x N epitaxial films (x = 0.00, 0.23, and 0.30) grown on a freestanding m-plane GaN substrate were determined by spectroscopic ellipsometry measurement. The experimentally obtained ellipsometric parameters tan Ψ and cos Δ, which represent the differences in the p- and s-polarized amplitudes and phases of the incident light, respectively, were well fitted using the standard analytical functions. As the measurement was carried out at photon energies between 1.55 and 5.40 eV, the dispersion curves of the extinction coefficient k exhibited local maxima at approximately the Al1‑ x In x N bandgap energies of x = 0.23 and 0.30, and the sample with x = 0.00 showed an ordinal absorption spectrum with a bandtail formed owing to high-concentration residual impurities. A large and x-dependent energy difference between the absorption and emission spectra (Stokes’ shift) was observed for the Al1‑ x In x N films, suggesting the presence of carrier localization phenomena.

  13. 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.

  14. 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.

  15. 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.

  16. Nanoscale characterization of β-phase H{sub x}Li{sub 1−x}NbO{sub 3} layers by piezoresponse force microscopy

    SciTech Connect

    Manzo, Michele; Gallo, Katia; Denning, Denise; Rodriguez, Brian J.

    2014-08-14

    We investigate a non-destructive approach for the characterization of proton exchanged layers in LiNbO{sub 3} with sub-micrometric resolution by means of piezoresponse force microscopy (PFM). Through systematic analyses, we identify a clear correlation between optical measurements on the extraordinary refractive index and PFM measurements on the piezoelectric d{sub 33} coefficient. Furthermore, we quantify the reduction of the latter induced by proton exchange as 83 ± 2% and 68 ± 3% of the LiNbO{sub 3} value, for undoped and 5 mol. % MgO-doped substrates, respectively.

  17. Systematic characterization of cell cycle phase-dependent protein dynamics and pathway activities by high-content microscopy-assisted cell cycle phenotyping.

    PubMed

    Bruhn, Christopher; Kroll, Torsten; Wang, Zhao-Qi

    2014-12-01

    Cell cycle progression is coordinated with metabolism, signaling and other complex cellular functions. The investigation of cellular processes in a cell cycle stage-dependent manner is often the subject of modern molecular and cell biological research. Cell cycle synchronization and immunostaining of cell cycle markers facilitate such analysis, but are limited in use due to unphysiological experimental stress, cell type dependence and often low flexibility. Here, we describe high-content microscopy-assisted cell cycle phenotyping (hiMAC), which integrates high-resolution cell cycle profiling of asynchronous cell populations with immunofluorescence microscopy. hiMAC is compatible with cell types from any species and allows for statistically powerful, unbiased, simultaneous analysis of protein interactions, modifications and subcellular localization at all cell cycle stages within a single sample. For illustration, we provide a hiMAC analysis pipeline tailored to study DNA damage response and genomic instability using a 3-4-day protocol, which can be adjusted to any other cell cycle stage-dependent analysis. PMID:25458086

  18. 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.

  19. Temperature-dependent quantitative 3{omega} scanning thermal microscopy: Local thermal conductivity changes in NiTi microstructures induced by martensite-austenite phase transition

    SciTech Connect

    Chirtoc, M.; Gibkes, J.; Wernhardt, R.; Pelzl, J.; Wieck, A.

    2008-09-15

    We develop the theoretical description of 3{omega} signals from the resistive Wollaston thermal probe (ThP) of a scanning thermal microscope (SThM) in terms of an equivalent low-pass filter. The normalized amplitude and phase frequency spectra are completely characterized by a single parameter, the crossover frequency f{sub c}(k) depending on the sample thermal conductivity k. The application concerns polycrystalline NiTi shape memory alloy microstructured by focused Ga ion beam milling and implantation. The calibration of the ThP combined with a novel two-step normalization procedure allowed quantitative exploitation of 3{omega} signal variations as small as -1.75% in amplitude and 0.60 deg. in phase upon heating the sample from room temperature to 100 deg. C. This corresponds to k increase of 23.9% that is consistent with the expected thermal conductivity variation due to martensite-austenite structural phase transition. To our knowledge this is for the first time that SThM 3{omega} phase information is used quantitatively as well. The static, calibrated 3{omega} measurements are complementary to 3{omega} SThM images of the patterned sample surface. The local SThM measurement of temperature-dependent thermal conductivity opens the possibility to imaging structural phase transitions at submicron scale.

  20. Piezoelectric force microscopy studies of PbTiO{sub 3} thin films grown via layer-by-layer gas phase reaction.

    SciTech Connect

    Park, M.; Hong, S.; Kim, J.; Kim, Y.; Buehlmann, S.; Kim, Y. K.; No, K.; Materials Science Division; Korea Advanced Inst. of Science and Technology; Imperial Col.; Samsung Electronics

    2009-01-01

    We fabricated 20 nm thick PbTiO{sub 3} films via reactive magnetron sputtering and studied the domain switching phenomena and retention properties using piezoresponse force microscopy. We found that multistep deposited PbTiO{sub 3} thin films showed 29% smaller rms roughness (2.5 versus 3.5 nm), 28% smaller coercive voltage (1.68 versus 2.32 V), 100% higher d{sub 33} value, and improved retention characteristic (89% versus 52% of remained poled domain area in 1280 min after poling) than single-step deposited PbTiO{sub 3} thin films. We attribute the improvement to the more complete chemical reaction between PbO and TiO{sub 2} during the film growth.

  1. 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

  2. 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. PMID:12657810

  3. In situ study of topography, phase and volume changes of titanium dioxide anode in all-solid-state thin film lithium-ion battery by biased scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Zhu, Jing; Feng, Jinkui; Lu, Li; Zeng, Kaiyang

    2012-01-01

    In this study, local cyclic changes of surface topography, phase and volume of TiO2 anode within an all-solid-state thin film Li-ion battery (TiO2/LiPON/LiNi1/3Co1/3Mn1/3O2) at nanoscale are studied. These changes are caused by reversible bias-induced electric field through an in situ scanning probe microscopy (SPM) without external electrochemical attachment. Combining simultaneous measurements of phase and amplitude images, high spatially resolved mapping of “nano-spots” related to Li+ distribution can be obtained, providing new insight into the ionic transport mechanism and diffusion preferred paths in a real all-solid-state thin film lithium ion battery. In addition, the thin film anode shows reversible topographical changes as the volume expansion/contraction is related to the cyclic Li+ insertion/extraction, which are analogues to the charge/discharge behavior observed in electrochemical atomic force microscopy (EC-AFM) studies. The results suggest that the applications of local reversible biases are very useful for modeling the charge/discharge processes of lithium ion batteries.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Spectroscopic infrared ellipsometry

    NASA Astrophysics Data System (ADS)

    Roseler, A.

    1992-03-01

    The spectroscopic infrared ellipsometry (SIRE) by means of the combination of a photometric ellipsometer with a Fourier transform spectrometer is used to measure optical properties in the infrared. From the observed four Stokes parameters, the spectrum of the degree of polarization after the reflection at the sample is calculated and discussed.

  9. Spectroscopic wear detector

    NASA Technical Reports Server (NTRS)

    Madzsar, George C. (Inventor)

    1993-01-01

    The elemental composition of a material exposed to hot gases and subjected to wear is determined. Atoms of an elemental species not appearing in this material are implanted in a surface at a depth based on the maximum allowable wear. The exhaust gases are spectroscopically monitored to determine the exposure of these atoms when the maximum allowable wear is reached.

  10. Transmission electron microscopy characterization of the dislocations of phase A deformed at 11 GPa, 400°C in the multianvil apparatus

    NASA Astrophysics Data System (ADS)

    Cordier, P.; Mussi, A.; Frost, D. J.

    2011-12-01

    Several dense hydrous magnesium silicate (DHMS) phases have been identified as possible carriers for water in subducting slabs. The style and distribution of deformation in subduction zones depends on the nature and rheological properties of subducted materials. If we have reasonable estimates of the rheological properties of anhydrous high-pressure phases, the properties of DHMS are largely unconstrained. In this study, we investigate the deformation mechanisms of phase A (Mg7Si2H6O14) which is hexagonal ( a = 7.86 Å and c = 9.57 Å). Phase A has been synthesized in quasi-hydrostatic conditions from high-purity oxides at 11 GPa, 900°C in a multi-anvil apparatus. After synthesis, the high-pressure phase was recovered and placed in another high-pressure cell designed to induce deviatoric stresses during the compression at 11 GPa, 400°C, i.e. at a temperature lower to the one investigated previously (700°C). Electron transparent thin foils suitable for TEM have been prepared by ion milling at liquid nitrogen temperature. To prevent electron beam damage, TEM characterizations were carried out under low illumination conditions, with a 300 kV accelerating voltage microscope (a Philips° CM30), and a Gatan° cold stage (liquid nitrogen temperature). The grain size of the microstructure is approximately 8 ± 2 μm, with very few sub-grains and the dislocation density is in the order of 2.1013 m-2. At this temperature, we observe many dissociated dislocations with extended stacking faults (dissociation width of the order of 1 μm). Supposing that dislocations are in glide conditions, and using the Ishida's method, we could identify: Partial 1/3 <1 -1 0 0> dislocations and perfect 1/3 <1 1 -2 0> dislocations (in equivalent proportion), in the (0 0 0 1) plane; Partial 1/3 <1 -1 0 0> and 1/3 <-1 1 0 3> dislocations, resulting from the dissociation of 1/3 <2 -1 -1 3> dislocations, and to a lesser extend perfect 1/3 <2 -1 -1 3> dislocations on the {1 -2 1 -1} plane

  11. A scanning tunnelling microscopy study of C and N adsorption phases on the vicinal Ni(100) surfaces Ni(810) and Ni(911)

    NASA Astrophysics Data System (ADS)

    Driver, S. M.; Toomes, R. L.; Woodruff, D. P.

    2016-04-01

    The influence of N and C chemisorption on the morphology and local structure of nominal Ni(810) and Ni(911) surfaces, both vicinal to (100) but with [001] and [ 01 1 bar ] step directions, respectively, has been investigated using scanning tunnelling microscopy (STM) and low energy electron diffraction. Ni(911) undergoes substantial step bunching in the presence of both adsorbates, with the (911)/N surface showing (411) facets, whereas for Ni(810), multiple steps 2-4 layers high are more typical. STM atomic-scale images show the (2 × 2)pg 'clock' reconstruction on the (100) terraces of the (810) surfaces with both C and N, although a second c(2 × 2) structure, most readily reconciled with a 'rumpling' reconstruction, is also seen on Ni(810)/N. On Ni(911), the clock reconstruction is not seen on the (100) terraces with either adsorbate, and these images are typified by protrusions on a (1 × 1) mesh. This absence of clock reconstruction is attributed to the different constraints imposed on the lateral movements of the surface Ni atoms adjacent to the up-step edge of the terraces with a [ 01 1 bar ] step direction.

  12. The Forces at Play in Optical Force Microscopy

    NASA Astrophysics Data System (ADS)

    Brocious, Jordan

    Optical force microscopy is a novel technique where mechanical detection with a cantilevered probe replaces the detection of photons to investigate optically induced processes and states. A theoretical and experimental analysis is performed here of the forces present in optical force microscopy operated in tapping mode, which reveals two dominant optically induced forces, the gradient force and the scattering force. Force-distance curves are reconstructed from experimental amplitude and phase information for glass, gold nanowires and molecular clusters of silicon naphtalocyanine samples. The scattering force is shown to be insensitive to both nano-scale tip-sample distances and sample polarizability and is dependent on the form of the tip. The gradient force demonstrates a z-4 tip-sample distance dependence, localized to a few nanometers, and is strongly dependent on the polarizability of the sample which enables spectroscopic imaging through force detection. The different distance-dependence and polarizability-dependence of the gradient and scattering forces give rise to a complex force-distance curve which determines imaging contrast along with the cantilever set-point, knowledge of which is essential for image interpretation.

  13. Introducing cymantrene labels into scattering scanning near-field infrared microscopy.

    PubMed

    Kopf, Ilona; N'Dongo, Harmel W Peindy; Ballout, Fouad; Schatzschneider, Ulrich; Bründermann, Erik; Havenith, Martina

    2012-11-01

    In this paper we investigate metal-organic compounds as infrared (IR) active labels by scattering scanning near-field infrared microscopy (IR s-SNOM, often also abbreviated as s-SNIM) with a lateral resolution of 90 × 90 nm(2). Tailor-made IR spectroscopic probes based on cymantrene (CpMn(CO)(3) with Cp = η(5)-C(5)H(5)) conjugated to a cysteine-modified pseudoneurotensin (pNT-Cys-OH) peptide were prepared by automated microwave-assisted solid phase peptide synthesis (SPPS) and characterized by HPLC, ESI-MS and IR. Well-defined patterned self-assembled monolayers on a gold surface were prepared by microcontact printing of 1-octadecanethiol (ODT) followed by additional incubation in ethanolic solution of the cymantrene-peptide derivative. The self-assembled monolayers have been evidenced by infrared reflection absorption spectroscopy (IRRAS) and AFM. CO laser source radiation was tuned (1944, 1900, 1798 and 1658 cm(-1)) for imaging contrast with good matching correlation between spectroscopic and topographic patterns at specific characteristic metal carbonyl and amide bands (1944 cm(-1) (λ = 5.14 μm) and 1658 cm(-1) (λ = 6.03 μm)). Cymantrene probes provide an attractive method to tag a unique spectroscopic feature on any bio(macro)molecule. Introducing such probes into super-resolution IR s-SNOM will enable molecular tracking and distribution studies even in complex biological systems. PMID:22966486

  14. Recent developments in GSDIM microscopy

    NASA Astrophysics Data System (ADS)

    Dyba, Marcus; Simonutti, Giulio A.; Fölling, Jonas

    2012-02-01

    In the presented study we characterized the suitability of 15 conventional fluorescence dyes for GSDIM microscopy. For all dyes involved in the screening labeled secondary antibodies for immunohistochemistry are commercially available. The dye performance was tested after staining to fixed mammalian cells. Chemical environments were chosen to be compatible with the applicative and spectroscopic demands. Investigated watery environments are suitable for TIRF based applications. To the best of our knowledge, we present for the first time systematic screening for configurations of dyes embedded in solid polymer. The polymer mounting matches well to the refractive index of oil immersion optics. This is crucial for applications at high penetration depth into the sample and suitable for long-term sample storage. We rated the final super-resolution image quality additional to quantitative characterization of important spectroscopic parameters. Therefore, this dye screening is optimized for various biological imaging applications. Control of the single molecule blinking rate by 405nm light exposure is quantified, as well. It is shown that this important effect is applicable to numerous fluorescent dyes. Thus, the controlled application of low intensities of 405nm light allows to maximize recording speed. As this option is already included in commercial GSDIM microscopes the results of our study allow optimized super-resolution imaging down to ~20nm with multiple dyes and multi-color staining.

  15. Si(111) Surface under Phase Transitions Studied by the Analysis of Inner Layer Structures Using Bias-Dependent Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Miyake, Koji; Kaikoh, Takashi; Li, Yan; Oigawa, Haruhiro; Shigekawa, Hidemi

    1999-06-01

    In both cases of quenched and HBO2-molecule-irradiated Si(111) surfaces, corner holes are observed to exist along the boundaries between 7×7 and disordered structural domains. From the analysis of the bias-dependent STM images, it was found that the corner holes included complete stacking fault and dimer structures in the second layer, i.e., a complete corner hole. This result strongly indicates that the complete corner holes play important roles in both the formation and stabilization processes of the dimer-adatom-stacking fault (DAS) structure. In addition, the formation of a structure similar to that of the corner hole was often observed at the boundaries of three out-of-phase c(2×8) structural domains in quenched surfaces, which may result in nucleuses for the formation of the complete corner hole.

  16. Infrared spectroscopic imaging of kidney tumor tissue

    NASA Astrophysics Data System (ADS)

    Sablinskas, V.; Steiner, G.; Koch, E.; Ceponkus, J.; Pucetaite, M.; Strazdaite, S.; Urboniene, V.; Jankevicius, F.

    2011-02-01

    Infrared spectroscopic imaging of cancerous kidney tissue was performed by means of FTIR microscopy. The spectra of thin tissue cryosections were collected with 64x64 MCT FPA detector and imaging area was increased up to 5.4×5.4 mm by mapping by means of PC controlled x,y stage. Chemical images of the samples were constructed using statistical treatment of the raw spectra. Several unsupervised and supervised statistical methods were used. The imaging results are compared with results of the standard histopathological analysis. It was concluded that application of method of cluster analysis ensures the best contrast of the images. It was found that border between cancerous and normal tissues visible in the infrared spectroscopic image corresponds with the border visible in histopathological image. Closer examination of the infrared spectroscopic image reveals that small domains of cancerous cells are found beyond the border in areas distant from the border up to 3 mm. Such domains are not visible in the histopathological images. The smallest domains found in the infrared images are approx. 60 μm.

  17. Scanning tunneling microscopy studies of growth medium & temperature dependent structural phases of alkanethiol self-assembled monolayers, reactive self-assembled monolayers, & flat gold nanoparticle/indium tin oxide substrates and a scanning surface photovoltage microscopy study for local mechanical stress characterization in complementary metal oxide semiconductor devices

    NASA Astrophysics Data System (ADS)

    Dahanayaka, Dahanayaka Liyanage Daminda Hemal

    Self-assembled monolayers (SAMs) of alkanethiolates on Au(111) represent promising platforms to study the molecular surfaces and interfaces for applications ranging from molecular electronics, nanophotonics to biology. Understanding the effect of growth conditions on SAMs particularly on their structural features is important from both fundamental and applied points of view. Knowledge of SAM structural features and structural phase transitions provides important insights into molecular packing for the control of the molecular self-assembly. We compared SAMs grown from different media, from 1 mM C10 solution in decalin, hexadecane and triethylene glycol and from C10 vapor. We present a molecularly-resolved scanning tunneling microscopy study showing the dependence of the SAM structure on the growth conditions. We have established conditions for making samples almost vacancy islands (VI) free with very large SAM domains of (2✓3 x 3)rect. superstructure and (✓3 x 4✓3)R30° striped-phase and investigated the orientation of low-index step edges of Au(111) for normal and striped-phase SAMs. We showed that the striped phase is stable to converting to (2✓3 x 3)rect. below 40°C. We demonstrate that flat gold nanoparticles (FGNPs) supported on indium tin oxide glass (ITO) are excellent substrates for molecularly-resolved STM imaging of alkanethiol SAMs. Nanoparticles were characterized using STM, TEM, and SEM techniques. Surface treatment techniques, Ar/O2 and H 2 plasma treatments, dry thermal annealing and exposures to UV/O 3, were used to prepare the surfaces of FGNPs supported on ITO and Au/mica substrates for high-resolution STM imaging of alkanethiol SAMs. We developed a convergent approach to functionalize SAM surfaces. Ordered mixed monolayers comprised of alkanethiols and azidoalkanethiols islands are formed and subsequent IMesCuIBr catalyzed [3+2] "click" cycloaddition reaction with substituted alkyne introduced dilute substituent onto the ordered surface

  18. 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

  19. 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.

  20. Quantitative comparison of the void distribution in a. beta. '-phase Ni-Al-In alloy using x-ray small-angle scattering and transmission-electron microscopy. [Ni-51. 2 at. % Al-2. 6 at. % In

    SciTech Connect

    Epperson, J.E.; Loomis, B.A.; Lin, J.S.

    1981-11-01

    Small-angle scattering is a rather mature discipline which can yield valuable information on the size, amount, and distribution of inhomogeneities encountered in materials-science research. Methods have been publisheed which permit one to extend the standard analysis of data from a small-angle-scattering experiment to include determination of the distribution of particle sizes. This extended analysis has been carried out for voids in a ..beta..'-phase Ni-Al-In alloy, and, in order to assess the reliability of the procedure, the identical void distribution as been characterized by transmission-electron microscopy. A quantitative comparison is made of the results from thses two independent experiments, and the general performance of the Brill-Schmidt method for particle-size determinations is discussed. 6 figures, 1 table.

  1. SEM, EDX, infrared and Raman spectroscopic characterization of the silicate mineral yuksporite.

    PubMed

    Frost, Ray L; López, Andrés; Scholz, Ricardo; Theiss, Frederick L; Romano, Antônio Wilson

    2015-02-25

    The mineral yuksporite (K,Ba)NaCa2(Si,Ti)4O11(F,OH)⋅H2O 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. PMID:25240833

  2. 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.

  3. Optical characteristics of pulsed laser deposited Ge-Sb-Te thin films studied by spectroscopic ellipsometry

    SciTech Connect

    Nemec, P.; Prikryl, J.; Frumar, M.; Nazabal, V.

    2011-04-01

    Pulsed laser deposition technique was used for the fabrication of (GeTe){sub 1-x}(Sb{sub 2}Te{sub 3}){sub x} (x = 0, 0.33, 0.50, 0.66, and 1) amorphous thin films. Scanning electron microscopy with energy-dispersive x-ray analysis, x-ray diffraction, optical reflectivity, and sheet resistance temperature dependences as well as variable angle spectroscopic ellipsometry measurements were used to characterize as-deposited (amorphous) and annealed (rocksaltlike) layers. In order to extract optical functions of the films, the Cody-Lorentz model was applied for the analysis of ellipsometric data. Fitted sets of Cody-Lorentz model parameters are discussed in relation with chemical composition and the structure of the layers. The GeTe component content was found to be responsible for the huge optical functions and thickness changes upon amorphous-to-fcc phase transition.

  4. 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.

  5. Scanning tomographic acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Lee, Hua

    2002-11-01

    This paper provides an overview of the design and development of the scanning tomographic acoustic microscopy (STAM). This research effort spans over a period of more than 12 years, which successfully elevated the acoustic microscopy from the traditional intensity-mapping mode to the level of holographic and tomographic imaging. The tomographic imaging capability of STAM was developed on the platform of the scanning laser acoustic microscope (SLAM), which operates in a coherent transmission mode with plane-wave illumination and scanning laser wavefield detection. The image formation techniques were based on the backward propagation method implemented in the plane-to-plane format. In this paper, the key elements of the design and development, including the modification of the data-acquisition hardware, implementation of image reconstruction algorithms for multiple-frequency and multiple-angle tomography, and the high-precision phase-correction and image registration techniques for the superposition of coherent sub-images, will be discussed. Results of full-scale experiments will also be included to demonstrate the capability of holographic and tomographic image formation in microscopic scale.

  6. 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.

  7. 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...

  8. 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.

  9. Comparison of microstructures and phase compositions of artificial and bone-derived hydroxyapatites by transmission electron microscopy and energy dispersive electron spectroscopy.

    PubMed

    Lee, Jong Kook

    2014-11-01

    Biological problems associated with sintered implants fabricated from artificially synthesized hydroxyapatite include selective dissolution at grain boundaries, microstructural disintegration in the body due to particle loosening, and slow crack growth at the implant surface. In addition, mechanical degradation has been shown to be significant, thus limiting their application as load-bearing medical implants. In contrast, bone-derived hydroxyapatite bioceramics have highly dissolution-resistant properties and excellent biocompatibility in the body. They are also easy to synthesize by thermal decomposition of animal bone. In this study, microstructural observations and crystal phase analysis of bone-derived hydroxyapatite were investigated by TEM and EDS using sintered hydroxyapatite samples. In addition, a comparative investigation into elemental distributions and the microstructures of artificial hydroxyapatite, bovine, and tuna bone-derived hydroxyapatites was performed. Bone-derived HA consists mainly of HA and a small amount of MgO. Hot-pressed HA compacts showed homogeneous microstructures and densities of 95-97%, however, grain sizes and microstructures varied with the starting powders. PMID:25958617

  10. Coherent nonlinear optical imaging: beyond fluorescence microscopy.

    PubMed

    Min, Wei; Freudiger, Christian W; Lu, Sijia; Xie, X Sunney

    2011-01-01

    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 excited-state absorption, stimulated emission, and ground-state depletion), provides new image contrasts for nonfluorescent species. Thanks to the high-frequency modulation transfer scheme, these imaging techniques 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 and excitation and detection schemes, as well as exemplary biomedical applications of this emerging class of molecular imaging techniques. PMID:21453061

  11. 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

  12. Gate Spacer Width Monitoring Study with Scatterometry Based on Spectroscopic Ellipsometry

    NASA Astrophysics Data System (ADS)

    Vachellerie, V.; Kremer, S.; Elazami, A.; Morin, P.; Julien, C.; Duca, D.; Guiheux, D.; Bicais, N.; Pokrant, S.

    2005-09-01

    Critical Dimension (CD) control of Gate Spacers is key to achieve in well controlled implantations and a tight distribution of Vt for transistors on semiconductors devices. Presently, historical methods for CD control (top-down low-voltage Scanning Electron Microscopy, Atomic Force Microscopy, Transmission Electron Microscopy or Electrical CD measurement) are facing limitations with regards to precision, matching, throughput or sample damage. So, with the reduction of design rules approaching the 65nm technology node, the need for a fast, precise and versatile "in-line" (at the process step) measurement of the spacer width and profile becomes critical, in order to shorten the spacer process development phase and the response time to production excursions. In this paper, we investigate the metrology performances and limitations (sensitivity, precision and accuracy) of Scatterometry (SCD) based on Spectroscopic Ellipsometry (SE) for this application using a KLA-TENCOR SpectraCD system. We show that it will be suitable for, at least, a simple oxide-nitride spacer configuration. We also explore its capability to measure more complex structures like the double-spacer configuration (LDD offset & S/D spacer). Finally, we show how additional information provided by Scatterometry helps in understanding process variations and how they correlate to end of line parametric test results.

  13. Proton spectroscopic imaging of human brain

    NASA Astrophysics Data System (ADS)

    Moonen, Chrit T. W.; Sobering, Geoffrey; Van Zijl, Peter C. M.; Gillen, Joe; Von Kienlin, Markus; Bizzi, Alberto

    Signals from water and fat can cause artifacts in proton spectroscopic imaging in the human brain. The major problem is variation of the B0 field over a range of several ppm within the sensitive volume of the standard whole-head coil. Here, the coherence-pathway formalism is used to describe and evaluate the origin of artifacts in a double spin-echo (PRESS) sequence. The attenuation of unwanted coherences using pulsed field gradients is described for homogeneous and inhomogeneous B0 fields. The effect of the following parameters on the quality of the spectroscopic images is analyzed: (a) directional order of plane selection, (b) positioning of phase-encode gradients in the sequence, (c) postprocessing spatial windowing, and (d) motion. It is shown that, for a typical echo time of 272 ms, it is not necessary to first select a region of interest within the brain borders when sufficient phase-encode steps are used. Examples of 2D proton spectroscopic images with a nominal voxel volume of 0.85 ml are given for a healthy volunteer and a patient with a low-grade glioma.

  14. Single laser beam photothermal microscopy

    NASA Astrophysics Data System (ADS)

    Heber, Andre; Selmke, Markus; Braun, Marco; Cichos, Frank

    2015-03-01

    Fluorescence microscopy provides a tool to study dynamics in softmatter materials on a molecular level. However, the observation time for fluorescent objects is limited due to bleaching. One way to overcome this limitation is the use of gold nanoparticles as labels. They are chemically inert under typical situations. These particles are selectively imaged using a modulated heating laser and a non-absorbed detection laser even in the presence of background scatterers. The absorbed power results in a localised temperature profile and to a refractive index change which only occurs for absorption. For finite thermal diffusivities the temperature profile does not instantly follow temperature changes present on the nanoparticle's surface. This results in an out-of-phase modulation of the detection laser. By exploiting the limited thermal diffusivity we show that a single laser beam being intensity modulated is enough to selectively image and quantify absorption. The use of a single laser makes photothermal microscopy easier to implement into existing microscopy setups.

  15. 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.

  16. 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.

  17. Holographic microscopy studies of emulsions

    NASA Technical Reports Server (NTRS)

    Witherow, W. K.

    1981-01-01

    A holographic microscopy system that records and observes the dynamic properties of separation of dispersed immiscible fluids is described. The holographic construction system and reconstruction system that were used to obtain particle size and distribution information from the holograms are discussed. The holographic microscopy system is used to observed the phase separating processes in immiscible fluids that were isothermally cooled into the two phase region. Nucleation, growth rates, coalescence, and particle motion are successfully demonstrated with this system. Thus a holographic particle sizing system with a resolution of 2 micrometers and a field of view of 100 cu cm was developed that provides the capability of testing the theories of separating immiscible fluids for particle number densities in the range of 10 to 10 to the 7th power particles.

  18. Spectroscopic Ellipsometry Applications in Advanced Lithography Research

    NASA Astrophysics Data System (ADS)

    Synowicki, R. A.; Pribil, Greg K.; Hilfiker, James N.; Edwards, Kevin

    2005-09-01

    Spectroscopic ellipsometry (SE) is an optical metrology technique widely used in the semiconductor industry. For lithography applications SE is routinely used for measurement of film thickness and refractive index of polymer photoresist and antireflective coatings. While this remains a primary use of SE, applications are now expanding into other areas of advanced lithography research. New applications include immersion lithography, phase-shift photomasks, transparent pellicles, 193 and 157 nm lithography, stepper optical coatings, imprint lithography, and even real-time monitoring of etch development rate in liquid ambients. Of recent interest are studies of immersion fluids where knowledge of the fluid refractive index and absorption are critical to their use in immersion lithography. Phase-shift photomasks are also of interest as the thickness and index of the phase-shift and absorber layers must be critically controlled for accurate intensity and phase transmission. Thin transparent pellicles to protect these masks must be also characterized for thickness and refractive index. Infrared ellipsometry is sensitive to chemical composition, film thickness, and how film chemistry changes with processing. Real-time monitoring of polymer film thickness during etching in a liquid developer allows etch rate and endpoint determination with monolayer sensitivity. This work considers these emerging applications to survey the current status of spectroscopic ellipsometry as a characterization technique in advanced lithography applications.

  19. 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.

  20. Applications of subsurface microscopy.

    PubMed

    Tetard, Laurene; Passian, Ali; Farahi, Rubye H; Voy, Brynn H; Thundat, Thomas

    2012-01-01

    Exploring the interior of a cell is of tremendous importance in order to assess the effects of nanomaterials on biological systems. Outside of a controlled laboratory environment, nanomaterials will most likely not be conveniently labeled or tagged so that their translocation within a biological system cannot be easily identified and quantified. Ideally, the characterization of nanomaterials within a cell requires a nondestructive, label-free, and subsurface approach. Subsurface nanoscale imaging represents a real challenge for instrumentation. Indeed the tools available for high resolution characterization, including optical, electron or scanning probe microscopies, mainly provide topography images or require taggants that fluoresce. Although the intercellular environment holds a great deal of information, subsurface visualization remains a poorly explored area. Recently, it was discovered that by mechanically perturbing a sample, it was possible to observe its response in time with nanoscale resolution by probing the surface with a micro-resonator such as a microcantilever probe. Microcantilevers are used as the force-sensing probes in atomic force microscopy (AFM), where the nanometer-scale probe tip on the microcantilever interacts with the sample in a highly controlled manner to produce high-resolution raster-scanned information of the sample surface. Taking advantage of the existing capabilities of AFM, we present a novel technique, mode synthesizing atomic force microscopy (MSAFM), which has the ability to probe subsurface structures such as non-labeled nanoparticles embedded in a cell. In MSAFM mechanical actuators (PZTs) excite the probe and the sample at different frequencies as depicted in the first figure of this chapter. The nonlinear nature of the tip-sample interaction, at the point of contact of the probe and the surface of the sample, in the contact mode AFM configuration permits the mixing of the elastic waves. The new dynamic system comprises new