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Edge illumination (EI) is a promising X-ray phase contrast imaging (XPCI) technique and is expected to translate XPCI into practical applications with laboratory X-ray sources. However, traditional double-mask EI setup requires two acquisitions for extracting phase and absorption information. Although the latest single-mask EI setup allows phase retrieval with single-shot, it requires a nearly ideal detector point spread function (PSF). In this paper, an alternative EI setup is proposed, which remains double-mask but requires only a single-shot. It can implement single-shot XPCI and relax the detector requirements. Numerical calculations are carried out to compare the characteristics of the double- and single-mask EI setup and the proposed setup. The performance of this setup with different illumination conditions is evaluated theoretically. The results suggest that the proposed setup is less affected by the detector PSF compared to the single-mask EI setup and therefore has higher contrast and contrast-to-noise ratio. Phase retrieval can be implemented by this setup with a single-shot, which helps to simplify the operations and eliminate the potential errors in the double-mask EI setup. A narrow illumination width contributes to the contrast but adversely affects the radiation utilization efficiency, and some appropriate trade-offs should be selected according to the practical applications and experimental conditions. On the basis of this setup, the extraction of the quantitative phase and absorption information was also conducted by numerical calculation. [ABSTRACT FROM AUTHOR]

The food irradiation marker, 2‐dodecylcyclobutanone (2‐DCB), assayed by SPME provides a fast and simple method to estimate the irradiation history of fat‐containing food products. The SPME conditions were optimized to maximize the extraction of 2‐DCB from chicken jerky treats (CJT) irradiated at low (5 kGy) and high (50 kGy) doses. The extracted 2‐DCB was measured using GC‐MS in selected ion mode (m/z 98, and 112). Water dilution (1:5) was needed to mobilize 2‐DCB and allow partition to the headspace form the CJT matrix. Increasing the incubation temperature to 80 °C resulted in higher response. Spiking control jerky samples with 2‐DCB from 10 to 150 ng/g CJT compared with spiking water revealed a significant food matrix effect. This method provides a fast, simple, and environmental friendly alternative for the existing solvent extraction methods. [ABSTRACT FROM AUTHOR]

In the field of biomedicine, the research on the mechanism of disease generation, the diagnosis of diseases, and the evaluation of therapeutic effects all require imaging recognition of cell morphological features. Because the optical detection method has the advantages of fast and efficient, non-invasive, non-invasive, and quantitative measurement, it has attracted the attention and favor of researchers. The specificity, non-invasiveness, and ability to perform multicolor imaging of living cells make light microscopy and fluorescence microscopy very important in biological research. Based on the above background, the research content of this paper is the research of three-dimensional microscopic imaging technology based on the phase measurement method. Based on the system design of the three-dimensional quantitative phase microscope, a three-dimensional quantitative phase microscope system based on the phase microscope has been successfully established and obtained a higher Spatial resolution and accurate refractive index expression. And successfully applied to measure the refractive index distribution of living biological cells. Finally, through the experimental simulation of binuclear cells, it is proved that the refractive index errors of each part are: 0.4237%, 1.4322%, 2.1836%, 0.2947%. Good reduction. Although there are certain errors in the reconstruction of the diameters of the large and small nuclei, their relative sizes are well guaranteed, and they can still effectively observe and present the characteristics of binuclear cells and subcellular structures. [ABSTRACT FROM AUTHOR]

Abstract Helico-conical beams (HCBs) are a class of orbital angular momentum (OAM)-carrying beams with spiral phase and intensity profiles. In this communication, we demonstrate the use of a common path interferometer (CPI) to phase-image incoming HCBs and directly detect their OAM-associated properties. The output intensity of the CPI is a direct mapping of the HCB's phase, hence both the topological charge value and sign manifest in the output intensity distribution. The topological charge value is calculated by fringe counting, while the helicity is determined by observing the intensity along the φ = 0 region. With our current CPI setup, we can firmly detect up to l = ± 20. Higher values of l lead to a decrease in the fringe visibility, but this can in principle be improved by tailoring the parameters of the phase contrast filter (PCF) employed in the CPI. We present analytical expressions to optimize the CPI for HCB charge detection. [ABSTRACT FROM AUTHOR]

A grating interferometer (GI) system has been installed in an X-ray microscope equipped with a Zernike phase contrast (ZPC) system and a Cu rotating anode X-ray source. The GI and ZPC systems are switchable, and their performances of phase information extraction have been compared. The GI system is based on a Lau interferometer consisting of an absorption grating and a π/2 phase grating, which extracts a magnified phase shift map of a sample via a phase-stepping measurement. The ZPC system generates a phase contrast image by using a phase plate and a corresponding condenser device. The ZPC system and the GI system are compared in terms of detectability of phase objects. By the Fourier analysis of images of a logarithmic ruler pattern, the spatial resolution was found to be identical between the two systems. Although the sensitivity depends on the sample size, the signal-to-noise ratio of polystyrene spheres with a few microns in diameter was used for sensitivity comparison, showing the superior sensitivity of the GI system to that of the ZPC system. The quantitativeness of the GI system with the phase-stepping measurement was also demonstrated over the ZPC system, which generates halo and shade-off artifacts. The GI system exhibits twin image artifacts that need to be resolved for practical applications of the technique. [ABSTRACT FROM AUTHOR]

Summary: The refractive index (RI) of a sample as an endogenous contrast agent plays an important role in transparent live cell imaging. In tomographic phase microscopy (TPM), 3D quantitative RI maps can be reconstructed based on the measured projections of the RI in multiple directions. The resolution of the RI maps not only depends on the numerical aperture of the employed objective lens, but also is determined by the accuracy of the quantitative phase of the sample measured at multiple scanning illumination angles. This paper reports an analogous on‐axis interference TPM, where the interference angle between the sample and reference beams is kept constant for projections in multiple directions to improve the accuracy of the phase maps and the resolution of RI tomograms. The system has been validated with both silica beads and red blood cells. Compared with conventional TPM, the proposed system acquires quantitative RI maps with higher resolution (420 nm @λ = 633 nm) and signal‐to‐noise ratio that can be beneficial for live cell imaging in biomedical applications. [ABSTRACT FROM AUTHOR]

Several pretreatment strategies focus on the removal of a significant part of lignin from plant cell walls, as it is considered the main barrier to the process of deconstructing biomass to simple sugars by hydrolytic enzymes. The ability to chemically differentiate and spatially locate lignins across cell walls provides an important contribution to the effort to improve these processes. Here, we present a novel approach using synchrotron phase-contrast tomography to probe the physicochemical features of plant cell walls. In addition to the 3D cellular architecture, the distribution of dense packed lignin–carbohydrate complexes (or, simply dense lignin) over larger regions and within cell walls has been successfully provided. We examined in particular the effect of the sequential H 2 SO 4 and NaOH pretreatment on sugacane bagasse. Our results revealed that aggregates of dense lignin form elongated 3D structures in cell corners (CC) following the orientation of the sclerenchyma fibers; a remarkable result in the light of the conventional perception that lignin particles are discrete and roughly spherical. After the acid pretreatment, a considerable fraction of the dense lignin primarily located in CCs was removed; and it was further dissolved with the subsequent alkali treatment. Unexpectedly, the two-step pretreatment did not contribute to the cellulose accessibility in terms of available surface area and porosity. This study provides new insights into the underlying mechanisms of biomass deconstruction by pretreatments; and the approach established here can be extended to other systems relevant to the bioenergy and biotechnology arenas. [ABSTRACT FROM AUTHOR]

Innovations in optical microscopy have opened new windows onto scientific research, industrial quality control, and medical practice over the last few decades. One of such innovations is optofluidic time-stretch quantitative phase microscopy – an emerging method for high-throughput quantitative phase imaging that builds on the interference between temporally stretched signal and reference pulses by using dispersive properties of light in both spatial and temporal domains in an interferometric configuration on a microfluidic platform. It achieves the continuous acquisition of both intensity and phase images with a high throughput of more than 10,000 particles or cells per second by overcoming speed limitations that exist in conventional quantitative phase imaging methods. Applications enabled by such capabilities are versatile and include characterization of cancer cells and microalgal cultures. In this paper, we review the principles and applications of optofluidic time-stretch quantitative phase microscopy and discuss its future perspective. [ABSTRACT FROM AUTHOR]

Color-coded light-emitting diode (LED) microscopy (cLEDscope) is a novel computational microscopy technique capable of multi-contrast and quantitative phase imaging of biological specimens using color-multiplexed illumination. Using specially designed LED patterns, it is capable of recording multiple differential phase contrast (DPC) images in a single exposure and employs a computational algorithm to retrieve the phase distribution of the specimens. Herein, we describe the detailed procedures in the cLEDscope implementation for quantitative phase imaging. Several notable features and caveats in the cLEDscope setup and image processing are also outlined. The imaging model is derived for our specific configuration, and the associated phase-retrieval algorithms are presented on the basis of a weak-object transfer function. As an illustrative application of the quantitative cLEDscope, we demonstrate its utility as a sperm-motility analyzer by exploiting its real-time quantitative imaging capability. [ABSTRACT FROM AUTHOR]

The selection of sperm cells possessing normal morphology and motility is crucial for many assisted reproductive technologies (ART), especially for intracytoplasmic sperm injection (ICSI), as sperm quality directly affects the probability of inducing healthy pregnancy. We present a novel platform for real-time quantitative analysis and selection of individual sperm cells without staining. Towards this end, we developed an integrated approach, combining interferometric phase microscopy (IPM), for stain-free sperm imaging and real-time automatic analysis based on the sperm cell 3D morphology and contents, with a disposable microfluidic device, for sperm selection and enrichment. On testing the capabilities of the microfluidic device, we obtained successful selection of sperm cells with a selectivity of 89.5 ± 3.5%, with no negative-decision sperm cells being inadvertently selected. In addition, we demonstrate the accuracy of sperm cell analysis using IPM by comparing the quantitative analysis produced by our IPM-based algorithm to the qualitative visual analysis performed independently by an experienced embryologist, which resulted in precision and specificity of 100%. We believe that the presented integrated approach has the potential to dramatically change the way sperm cells are selected for ICSI and other ART procedures, making the selection process more objective, quantitative and automatic, and thereby increasing success rates. [ABSTRACT FROM AUTHOR]

Cell mechanical behaviour is increasingly recognised as a central biophysical parameter in cancer and stem cell research, and methods of investigating their mechanical behaviour are therefore needed. We have developed a novel qualitative method based on quantitative phase imaging which is capable of investigating cell mechanical behaviour in real-time at cellular resolution using optical coherence phase microscopy (OCPM), and stimulating the cells non-invasively using hydrostatic pressure. The method was exemplified to distinguish between cells with distinct mechanical properties, and transient change induced by Cytochalasin D. We showed the potential of quantitative phase imaging to detect nanoscale intracellular displacement induced by varying hydrostatic pressure in microfluidic channels, reflecting cell mechanical behaviour. Further physical modelling is required to yield quantitative mechanical properties. [ABSTRACT FROM AUTHOR]

A two-exposure nearly common-path point diffraction interferometric phase microscopy (IPM) is presented using polarization modulation and one-step grating shifting to implement quantitative phase imaging. The IPM is constructed by an improved Michelson configuration with a reflective grating, and its frequency spectrum generated by a circularly polarized object beam makes double copies through a beam splitter. One copy is low-pass filtered and reflected by a reflective pinhole mirror to create a reference beam, and the other copy is converted by a polarizer and then reflected by a reflective grating to achieve a 45° linearly polarized object beam. By the combination of a polarizing cube beam splitter with 45° tilted angle and a translation of the reflective grating with a π phase shift, four interferograms with π/2 phase shift can be obtained in two exposures. The standard four-step algorithm can then be used to reconstruct the phase of the specimen. The utility of the proposed method was demonstrated with measurements on a phase plate, cells and an oil drop. [ABSTRACT FROM AUTHOR]

We report a novel approach to diffraction phase microscopy (DPM) with automatic pinhole alignment. The pinhole, which serves as a spatial low-pass filter to generate a uniform reference beam, is made out of a liquid crystal display (LCD) device that allows for electrical control. We have made DPM more accessible to users, while maintaining high phase measurement sensitivity and accuracy, through exploring low cost optical components and replacing the tedious pinhole alignment process with an automatic pinhole optical alignment procedure. Due to its flexibility in modifying the size and shape, this LCD device serves as a universal filter, requiring no future replacement. Moreover, a graphic user interface for real-time phase imaging has been also developed by using a USB CMOS camera. Experimental results of height maps of beads sample and live red blood cells (RBCs) dynamics are also presented, making this system ready for broad adaption to biological imaging and material metrology. [ABSTRACT FROM AUTHOR]

This study describes the successful sequential modification of multi-walled carbon nanotube (MWCNT) by Fe3O4magnetic nanoparticles and 2-mercaptobenzothiazole (MBT) followed by its application as a novel sorbent for simultaneous magnetic solid phase microextraction of lead and cadmium. Fourier transform infrared spectroscopy and scanning electron microscopy were employed to confirm the chemical surface modification of the MWCNT. The ions retained on the 2-MBT/magnetic nanoparticles modified MWCNTs were eluted with 1.0 mL of nitric acid (0.8 mol L−1) in methanol solution and determined by the flame atomic absorption spectrometry. All parameters affecting the extraction condition were thoroughly investigated and optimised. Under the optimised condition preconcentration factor of 150.0, enhancement factors of 149.0 and 149.2 and limits of detection of 0.21 and 0.01 µg L−1were achieved for lead and cadmium, respectively. Using the prepared magnetic nanocomposite, the possible interference of other common ions associated with lead and cadmium determination was effectively avoided and the method was successfully applied to the simultaneous determination of the target ions in various environmental water samples. [ABSTRACT FROM AUTHOR]

The development of fluorescent probes and proteins has helped make light microscopy more popular by allowing the visualization of specific subcellular components, location and dynamics of biomolecules. However, it is not always feasible to label the cells as it may be phototoxic or perturb their functionalities. Label-free microscopy techniques allow us to work with live cells without perturbation and to evaluate morphological differences, which in turn can provide useful information for high-throughput assays. In this study, we use one of the most popular label-free techniques called differential interference contrast (DIC) microscopy to estimate the phase of cells and other nearly transparent objects and instantly estimate their height. DIC images provide detailed information about the optical path length (OPL) differences in the sample and they are visually similar to a gradient image. Our previous DIC reconstruction algorithm outputs an image where the values are proportional to the OPL (or implicitly the phase) of the sample. Although the reconstructed images are capable of describing cellular morphology and to a certain extent turn DIC into a quantitative technique, the actual OPL has to be computed from the input DIC image and the microscope calibration settings. Here we propose a computational method to measure the phase and approximate height of cells after microscope calibration, assuming a linear formation model. After a calibration step the phase of further samples can be determined when the refractive indices of the sample and the surrounding medium is known. The precision of the method is demonstrated on reconstructing the thickness of known objects and real cellular samples. [ABSTRACT FROM AUTHOR]

Several dedicated commercial lab-based micro-computed tomography (μCT) systems exist, which provide high-resolution images of samples, with the capability to also deliver in-line phase contrast. X-ray phase contrast is particularly beneficial when visualizing very small features and weakly absorbing samples. The raw measured projections will include both phase and absorption effects. Extending our previous work that addressed the optimization of experimental conditions at the commercial ZEISS Xradia 500 Versa system, single-distance phase-contrast imaging is demonstrated on complex biological and material samples. From data captured at this system, we demonstrate extraction of the phase signal or the correction of the mixed image for the phase shift, and show how this procedure increases the contrast and removes artefacts. These high-quality images, measured without the use of a synchrotron X-ray source, demonstrate that highly sensitive, micrometre-resolution imaging of 3D volumes is widely accessible using commercially advanced laboratory devices. [ABSTRACT FROM AUTHOR]

An interferometric phase microscopy (IPM) is proposed using slightly-off-axis reflective point diffraction interferometry for quantitative phase imaging. A retro-reflector consisting two mirrors is used to generate an angle between the object beam and reference beam, and a 45° tilted polarizing beam splitter is used to split the horizontal and vertical components of the both beams. Two carrier interferograms with π/2 phase-shift can be acquired in one shot, and the phase distribution of a thin specimen can be retrieved using a fast reconstruction method. The new IPM without loss in the utilization of the input-plane field of view combines the real time and optimizing detector bandwidth measurement benefit associated with slightly-off-axis method, high stability associated with common path geometry, and simplicity in terms of procedure and setup. Experiments are carried out on both static and dynamic specimens to demonstrate the validity and stability of the proposed method. [ABSTRACT FROM AUTHOR]

We present a new technique for quantitative phase and amplitude microscopy from a single color image with coded illumination. Our system consists of a commercial brightfield microscope with one hardware modification—an inexpensive 3D printed condenser insert. The method, color-multiplexed Differential Phase Contrast (cDPC), is a single-shot variant of Differential Phase Contrast (DPC), which recovers the phase of a sample from images with asymmetric illumination. We employ partially coherent illumination to achieve resolution corresponding to 2× the objective NA. Quantitative phase can then be used to synthesize DIC and phase contrast images or extract shape and density. We demonstrate amplitude and phase recovery at camera-limited frame rates (50 fps) for various in vitro cell samples and c. elegans in a micro-fluidic channel. [ABSTRACT FROM AUTHOR]

In order to realize high contrast imaging with portable devices for potential mobile healthcare, we demonstrate a hand-held smartphone based quantitative phase microscope using the transport of intensity equation method. With a cost-effective illumination source and compact microscope system, multi-focal images of samples can be captured by the smartphone’s camera via manual focusing. Phase retrieval is performed using a self-developed Android application, which calculates sample phases from multi-plane intensities via solving the Poisson equation. We test the portable microscope using a random phase plate with known phases, and to further demonstrate its performance, a red blood cell smear, a Pap smear and monocot root and broad bean epidermis sections are also successfully imaged. Considering its advantages as an accurate, high-contrast, cost-effective and field-portable device, the smartphone based hand-held quantitative phase microscope is a promising tool which can be adopted in the future in remote healthcare and medical diagnosis. [ABSTRACT FROM AUTHOR]

It is proposed to use local tomography for optical studies of the internal structure of transparent phase microscopic objects, for example, living cells. From among the many local tomography methods that exist, the algorithms of back projection summation (in which partial derivatives of projections are used as projection data) are chosen. The application of local tomography to living cells is reasonable because, using optical phase microscopy, one can easily obtain projection data in the form of first-order derivatives of projections applying the methods of differential interference contrast and shear interferometry. The mathematical fundamentals of local tomography in differential projections are considered, and a computer simulation of different local tomography methods is performed. A tomographic phase microscope and the results of reconstructing a local tomogram of an erythrocyte from a set of experimental differential projections are described. [ABSTRACT FROM AUTHOR]

An artificial wound in a confluent monolayer of human keratinocyte HaCaT cells or mouse embryo fibroblast Swiss NIH 3T3 cells was used to analyze the effects of the nitric oxide (NO) chemical donor, S-nitroso-N-acetylpenicillamine (SNAP). SNAP exposure promoted an enhanced rate of wound closure and accelerated motility of both keratinocytes and fibroblasts compared to control cells. The wounded monolayer cultures of HaCaT and NIH 3T3 cells, treated with or without SNAP, were monitored under a phase contrast microscope. Structural and ultrastructural modifications were analyzed by scanning electron microscopy (SEM). The images were captured by a digital camera at different time points (0-28 h) and the wound area was analyzed through software included in Matlab®. As early as 15 min, SNAP induced significant cytoskeletal remodeling, as shown by immunostaining (phalloidin-labelling), which in turn was associated with increased filopodium number and length rise. NO donor treatment also induced overexpression of Ki-67 protein, a typical marker of cell proliferation, as shown by immunostaining. Both SNAP-induced migration and proliferation were antagonized by the NO-sensitive GC inhibitor 1H-[1,2,4]oxadiazolo[-4,3-a]quinoxalin-1-one (ODQ), which suggests activation of the NO/cGMP signalling cascade in the observed SNAP-induced effects in the early stages of the healing process. Moreover, we provide evidence that PPAR-β antagonist (GSK0660) may interfere with NO-mediated wound healing process. J. Cell. Physiol. 231: 2185-2195, 2016. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

An evaluation of a large database of red wolf fresh ejaculate characteristics (n = 427 ejaculates from 64 wolves) was undertaken to increase knowledge of seminal characteristics in the red wolf and evaluate possible relationships between inbreeding, age, and seminal quality. Phase microscopy analysis of electroejaculates collected over 14 natural breeding seasons was compared with animal ages and inbreeding coefficients. Ejaculate volume increased and sperm concentration and total count decreased as wolves aged (P < 0.01, 0.001, and 0.05, respectively), and the proportion of sperm cell morphological abnormalities was greater in animals with higher coefficients of inbreeding (P < 0.001), particularly for older animals (P < 0.001). Moreover, the mean coefficient of inbreeding of animals that had failed to reproduce given at least one opportunity during their lifetimes was significantly greater than that of wolves with proven fertility, and wolves of proven fertility exhibited higher sperm concentrations and total counts than nonproven wolves. Thus, as the captive red wolf population becomes more inbred, the maximum age of reproduction is likely to decrease; an important finding to consider when projecting population dynamics and determining pairing recommendations. [ABSTRACT FROM AUTHOR]

The purpose of this study was to detect asbestos-containing products and released asbestos fibers from home appliances. The authors investigated a total of 414 appliances manufactured between 1986 and 2007. Appliances were divided into three categories: large-sized electric appliances, small-sized electric appliances, and household items. Analysis for asbestos-containing material (ACM) was performed using polarized light microscopy (PLM) and stereoscopic microscopy. Air sampling was performed to measure airborne concentration of asbestos using a phase-contrast microscope (PCM). The results of the analysis for ACM in appliances show that large-sized electric appliances (refrigerators, washing machines, kimchi-refrigerators) and household items (bicycles, motorcycles, gas boilers) contain asbestos material and small-sized electric appliances do not contain asbestos material. All appliances with detected asbestos material showed typical characteristics of chrysotile (7–50%) and tremolite (7–10%). No released fibers of ACM were detected from the tested appliances when the appliances were operating. This study gives the basic information on asbestos risk to people who use home appliances. Implications: All appliances with detected asbestos material showed typical characteristics of chrysotile (7–50%) and tremolite (7–10%). No released fibers of ACM were detected from the tested appliances when the appliances were operating. [ABSTRACT FROM AUTHOR]

Unlocking the 3-D structure and properties of intact chondritic porous interplanetary dust particles ( IDPs) in nanoscale detail is challenging, which is also complicated by atmospheric entry heating, but is important for advancing our understanding of the formation and origins of IDPs and planetary bodies as well as dust and ice agglomeration in the outer protoplanetary disk. Here, we show that indigenous pores, pristine grains, and thermal alteration products throughout intact particles can be noninvasively visualized and distinguished morphologically and microstructurally in 3-D detail down to ~10 nm by exploiting phase contrast X-ray nanotomography. We have uncovered the surprisingly intricate, submicron, and nanoscale pore structures of a ~10-μm-long porous IDP, consisting of two types of voids that are interconnected in 3-D space. One is morphologically primitive and mostly submicron-sized intergranular voids that are ubiquitous; the other is morphologically advanced and well-defined intragranular nanoholes that run through the approximate centers of ~0.3 μm or lower submicron hollow grains. The distinct hollow grains exhibit complex 3-D morphologies but in 2-D projections resemble typical organic hollow globules observed by transmission electron microscopy. The particle, with its outer region characterized by rough vesicular structures due to thermal alteration, has turned out to be an inherently fragile and intricately submicron- and nanoporous aggregate of the sub-μm grains or grain clumps that are delicately bound together frequently with little grain-to-grain contact in 3-D space. [ABSTRACT FROM AUTHOR]

To demonstrate the correlations between the concentrations of ferruginous body as well as uncoated fiber both of which can be observed with phase-contrast microscope and the concentration of various inorganic fibers including asbestos which requires the observation with TEM or SEM, we measured those indices among Japanese and Korean cases. Though the concentration of ferruginous body in lung tissue is an important index of asbestos exposure, uncoated fibers observed with phase-contrast microscope might be another index especially in such cases with relatively low exposure due to their history of living in a general environment. However, to establish the reliability of uncoated fibers as an index of asbestos exposure, analysis with more cases and from various backgrounds must be carried out. [ABSTRACT FROM AUTHOR]

Purpose To evaluate the effect of multipurpose contact lens care solutions ( MPSs) on the adhesion of Acanthamoeba to rigid gas permeable ( RGP) contact lenses. Methods Acanthamoeba castellanii ( AC) trophozoites were inoculated onto untreated RGP contact lenses ( FP, Extra, or Menicon Z), and numbers of trophozoites adhering to lenses were counted under a phase contrast microscope at 18 h post-inoculation (controls). Similarly, adhering trophozoites were counted at 6 h post-inoculation on each of the three RGP lens types with one of three MPSs (Boston Simplus, Menicare Plus, and O2 Care). Scanning electron microscopic examinations were performed to compare lens surfaces. Results Adhesion of AC trophozoites to untreated FP was greater than to untreated Extra or Menicon Z. Surfaces of Extra and Menicon Z lenses were waxier, smoother, and more homogeneous than those of FP lenses. After treatment with Boston Simplus, adhesion of AC trophozoites was significantly reduced for all lens types as compared with controls ( p < 0.0001). Treatments with Menicare Plus or O2 Care reduced the number of adherent AC trophozoites significantly on FP lenses only as compared with controls ( p < 0.0001). Conclusions The adhesion rates of AC trophozoites to RGP lenses depended on lens surfaces. Boston Simplus reduced the adhesion rate of AC trophozoites more than Menicare Plus or O2 Care. Appropriate RGP lens and MPS selection could decrease the prevalence of Acanthamoeba keratitis. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the optimization of a high energy in-line phase sensitive x-ray imaging prototype under different geometric and operating conditions for mammography application. A phase retrieval algorithm based on phase attenuation duality (PAD) was applied to the phase contrast images acquired by the prototype. Imaging performance was investigated at four magnification values of 1.67, 2, 2.5 and 3 using an acrylic edge, an American College of Radiology (ACR) mammography phantom and contrast detail (CD) phantom with tube potentials of 100, 120 and 140 kVp. The ACR and CD images were acquired at the same mean glandular dose (MGD) of 1.29 mGy with a computed radiography (CR) detector of 43.75 µm pixel pitch at a fixed source to image distance (SID) of 170 cm. The x-ray tube focal spot size was kept constant as 7 µm while a 2.5 mm thick aluminum (Al) filter was used for beam hardening. The performance of phase contrast and phase retrieved images were compared with computer simulations based on the relative phase contrast factor (RPF) at high x-ray energies. The imaging results showed that the x-ray tube operated at 100 kVp under the magnification of 2.5 exhibits superior imaging performance which is in accordance to the computer simulations. As compared to the phase contrast images, the phase retrieved images of the ACR and CD phantoms demonstrated improved imaging contrast and target discrimination. We compared the CD phantom images acquired in conventional contact mode with and without the anti-scatter grid using the same prototype at 1.295 mGy and 2.59 mGy using 40 kVp, a 25 µm rhodium (Rh) filter. At the same radiation dose, the phase sensitive images provided improved detection capabilities for both the large and small discs, while compared to the double dose image acquired in conventional mode, the observer study also indicated that the phase sensitive images provided improved detection capabilities for the large discs. This study therefore validates the potential of using high energy phase contrast x-ray imaging to improve lesion detection and reduce radiation dose for clinical applications such as mammography. [ABSTRACT FROM AUTHOR]

We study the Josephson effect of d-wave superconductor (DS)/ferromagnet insulator (FI)/DS junctions on a surface of topological insulator (TI), We calculate Josephson current I (φ) for various orientations of the junctions where φ is the macroscopic phase difference between two DSs. In certain configurations, we find anomalous current-phase relation I(φ) = - I (-φ + π) with 2π periodicity. In the case where the first-order Josephson coupling is absent without magnetization in FI, I(φ) can be proportional to cosφ. In symmetric junctions, the magnitude of the obtained Josephson current is enhanced due to the zero-energy states on the edge of DS on TI. Even if we introduce an s-wave component of pair potential in DS, we can still expect the anomalous current-phase relation in asymmetric DS junctions with I(φ = 0) ≠ 0. This can be used to probe the induced d-wave component of pair potential on a TI surface in high-Tc cuprate/TI hybrid structures. [ABSTRACT FROM AUTHOR]

The refractive index (RI) distribution can serve as a natural label for undyed cell imaging. However, the majority of images obtained through quantitative phase microscopy is integrated along the illumination angle and cannot reflect additional information about the refractive map on a certain plane. Herein, a light-field reconstruction method to image the RI map within a depth of 0.2 μm is proposed. It records quantitative phase-delay images using a four-step phase shifting method in different directions and then reconstructs a similar scattered light field for the refractive sample on the focus plane. It can image the RI of samples, transparent cell samples in particular, in a manner similar to the observation of scattering characteristics. The light-field reconstruction method is therefore a powerful tool for use in cytobiology studies. [ABSTRACT FROM AUTHOR]

Mode conversion of fast waves in the ion cyclotron range of frequencies (ICRF) is known to result in current drive and flow drive under optimised conditions, which may be utilized to control plasma profiles and improve fusion plasma performance. To describe these processes accurately in a realistic toroidal geometry, numerical simulations are essential. Quantitative comparison of these simulations and the actual experimental measurements is important to validate their predictions and to evaluate their limitations. The phase contrast imaging (PCI) diagnostic has been used to directly detect the ICRF waves in the Alcator C-Mod tokamak. The measurements have been compared with full-wave simulations through a synthetic diagnostic technique. Recently, the frequency response of the PCI detector array on Alcator C-Mod was recalibrated, which greatly improved the comparison between the measurements and the simulations. In this study, mode converted waves for D-3He and D-H plasmas with various ion species compositions were re-analyzed with the new calibration. For the minority heating cases, self-consistent electric fields and a minority ion distribution function were simulated by iterating a full-wave code and a Fokker-Planck code. The simulated mode converted wave intensity was in quite reasonable agreement with the measurements close to the antenna, but discrepancies remain for comparison at larger distances. [ABSTRACT FROM AUTHOR]

This paper describes a highly sensitive spectrum sensing system based on a cross-correlation technique that employs low-cost software-defined radio receivers. By multiplying two data streams received by duplicated receivers and averaging the outputs, a cross-correlation system is able to suppress uncorrelated noise at the cost of measurement time. In this paper, phase-domain detection is proposed to determine whether or not a radio signal is present without any knowledge of signal features. The robustness of our method to noise uncertainty has been verified in both theoretical analyses and simulations. The sensing system has been implemented with low-cost USB tuners and a PC-based digital signal processor. TV-band spectrum sensing has been performed as a demonstration of the system. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

Imaging techniques for visualizing cerebral vasculature and distinguishing functional areas are essential and critical to the study of various brain diseases. In this paper, with the X-ray phase-contrast imaging technique, we proposed an experiment scheme for the ex vivo mouse brain study, achieving both high spatial resolution and improved soft-tissue contrast. This scheme includes two steps: sample preparation and volume reconstruction. In the first step, we use heparinized saline to displace the blood inside cerebral vessels and then replace it with air making air-filled mouse brain. After sample preparation, X-ray phase-contrast tomography is performed to collect the data for volume reconstruction. Here, we adopt a phase-retrieval combined filtered backprojection method to reconstruct its three-dimensional structure and redesigned the reconstruction kernel. To evaluate its performance, we carried out experiments at Shanghai Synchrotron Radiation Facility. The results show that the air-tissue structured cerebral vasculatures are highly visible with propagation-based phase-contrast imaging and can be clearly resolved in reconstructed crossimages. Besides, functional areas, such as the corpus callosum, corpus striatum, and nuclei, are also clearly resolved. The proposed method is comparable with hematoxylin and eosin staining method but represents the studied mouse brain in three dimensions, offering a potential powerful tool for the research of brain disorders. [ABSTRACT FROM AUTHOR]

A cyclic interferometer, appropriately combined with a long working distance microscope objective, is adapted for quantitative phase microscopy. In such an arrangement, the sample information, in terms of the diffracted orders emerging from the sample, is carried by both the counter propagating beams within the cyclic interferometer. However, positioning the sample close to the input/output cube beam splitter and use of a suitably converging laser beam of light as the input to the interferometer ensure that only one of the counter propagating beams carries the object information to the objective while the other beam, which serves as the reference, allows only the undiffracted component to contribute to the process of image formation. Use of suitable polarization optics renders the interferometer its polarization phase shifting property. Using the proposed arrangement, the experimental results showing the quantitative 3D phase rendering of polystyrene microspheres and micro-wells etched in glass are presented. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A reflection type white light diffraction phase microscope for full field surface profiling of opaque samples is proposed. The system can extract surface profile from one recorded interferogram without any mechanical movement and the use of white light makes it free from speckle noise. We validated the performance of our system by measuring a known step sample and a high-quality plane sample. The step height of the step sample is found to be 88.5 nm with a standard deviation of 1.4 nm, and the surface peak to valley value of the plane sample is found to be 28.6 nm with a standard deviation of 3 nm. [ABSTRACT FROM AUTHOR]

Phase-Contrast MRI (PC-MRI) is a noninvasive technique to measure blood flow. In particular, global but highly quantitative cerebral blood flow (CBF) measurement using PC-MRI complements several other CBF mapping methods such as arterial spin labeling and dynamic susceptibility contrast MRI by providing a calibration factor. The ability to estimate blood supply in physiological units also lays a foundation for assessment of brain metabolic rate. However, a major obstacle before wider applications of this method is that the slice positioning of the scan, ideally placed perpendicular to the feeding arteries, requires considerable expertise and can present a burden to the operator. In the present work, we proposed that the majority of PC-MRI scans can be positioned using an automatic algorithm, leaving only a small fraction of arteries requiring manual positioning. We implemented and evaluated an algorithm for this purpose based on feature extraction of a survey angiogram, which is of minimal operator dependence. In a comparative test-retest study with 7 subjects, the blood flow measurement using this algorithm showed an inter-session coefficient of variation (CoV) of . The Bland-Altman method showed that the automatic method differs from the manual method by between and , for of the CBF measurements. This is comparable to the variance in CBF measurement using manually-positioned PC MRI alone. In a further application of this algorithm to 157 consecutive subjects from typical clinical cohorts, the algorithm provided successful positioning in 89.7% of the arteries. In 79.6% of the subjects, all four arteries could be planned using the algorithm. Chi-square tests of independence showed that the success rate was not dependent on the age or gender, but the patients showed a trend of lower success rate (p = 0.14) compared to healthy controls. In conclusion, this automatic positioning algorithm could improve the application of PC-MRI in CBF quantification. [ABSTRACT FROM AUTHOR]

Abstract: In order to accelerate the commercialization of fuel cells and batteries across a range of applications, an understanding of the mechanisms by which they age and degrade at the microstructural level is required. Here, the most widely commercialized Li-ion batteries based on porous graphite based electrodes which de/intercalate Li+ ions during charge/discharge are studied by two phase contrast enhanced X-ray imaging modes, namely in-line phase contrast and Zernike phase contrast at the micro (synchrotron) and nano (laboratory X-ray microscope) level, respectively. The rate of charge cycling is directly dependent on the nature of the electrode microstructure, which are typically complex multi-scale 3D geometries with significant microstructural heterogeneities. We have been able to characterise the porosity and the tortuosity by micro-CT as well as the morphology of 5 individual graphite particles by nano-tomography finding that while their volume varied significantly their sphericity was surprisingly similar. The volume specific surface areas of the individual grains measured by nano-CT are significantly larger than the total volume specific surface area of the electrode from the micro-CT imaging, which can be attributed to the greater particle surface area visible at higher resolution. [Copyright &y& Elsevier]

We present a technique called white-light diffraction tomography (WDT) for imaging microscopic transparent objects such as live unlabelled cells. The approach extends diffraction tomography to white-light illumination and imaging rather than scattering plane measurements. Our experiments were performed using a conventional phase contrast microscope upgraded with a module to measure quantitative phase images. The axial dimension of the object was reconstructed by scanning the focus through the object and acquiring a stack of phase-resolved images. We reconstructed the three-dimensional structures of live, unlabelled, red blood cells and compared the results with confocal and scanning electron microscopy images. The 350 nm transverse and 900 nm axial resolution achieved reveals subcellular structures at high resolution in Escherichia coli cells. The results establish WDT as a means for measuring three-dimensional subcellular structures in a non-invasive and label-free manner. [ABSTRACT FROM AUTHOR]

Microscopy using visible electromagnetic radiation can be used to investigate living cells in various environments. But bright field microscopy only provides two-dimensional (2D) intensity distribution at a single object plane. One of the ways to retrieve object height/thickness information is to employ quantitative phase microscopic (QPM) techniques. Interferometric QPM techniques are widely used for this. Digital holographic microscopy (DHM) is one of the state-of-the-art methods for quantitative three-dimensional (3D) imaging. Usually it is implemented in two-beam geometry, which is prone to mechanical vibrations. But to study dynamics of objects like red blood cells, one needs temporal stability much better than the fluctuations of the object, which the two-beam geometry fails to deliver. One way to overcome this hurdle is to use self-referencing techniques, in which a portion of the object beam will act as the reference beam. Here the development of self-referencing QPM techniques is described along with the results. [ABSTRACT FROM AUTHOR]

-We have designed and fabricated a broadband short-slot hybrid coupler using a two-stage linear taper in W-band. The coupler consists of two metal pieces split at the edge of the narrow wall of the waveguide, which makes it possible to use simple direct machining for fabrication. The electrical performance of the coupler was measured by a Vector Network Analyzer (VNA) at room temperature. The results showed excellent performance as designed: amplitude imbalance between the two output ports of ≤ 1 dB, phase difference between the output ports with respect to 90° < 3°, input return loss < –15 dB, and isolation < –15 dB across the measured frequency range of 85-110 GHz. The short-slot hybrid coupler was used in a balanced Superconductor-Insulator-Superconductor (SIS) mixer at 4 K. The noise performance was almost the same as that of the two single-ended mixers used in the balanced mixer. These results indicate that our short-slot hybrid coupler has great potential for practical applications, such as at millimeter- and submillimeter-waves. [ABSTRACT FROM AUTHOR]

The coupling of the rate of cell growth to the rate of cell division determines cell size, a defining characteristic that is central to cell function and, ultimately, to tissue architecture. The physiology of size homeostasis has fascinated generations of biologists, but the mechanism, challenged by experimental limitations, remains largely unknown. In this paper, we propose a unique optical method that can measure the dry mass of thick live cells as accurately as that for thin cells with high computational efficiency. With this technique, we quantify, with unprecedented accuracy, the asymmetry of division in lymphoblasts and epithelial cells. We can then use the Collins-Richmond model of conservation to compute the relationship between growth rate and cell mass. In attached epithelial cells, we find that due to the asymmetry in cell division and size-dependent growth rate, there is active regulation of cell size. Thus, like nonadherent cells, size homeostasis requires feedback control. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) X-ray tomographic micro-imaging system has been developed. The optical system is based on a scanning-imaging X-ray microscope (SIXM) optics, which is a hybrid system consisting of a scanning microscope optics with a one-dimensional (1D) focusing (line-focusing) device and an imaging microscope optics with a 1D objective. In the SIXM system, each 1D dataset of a two-dimensional (2D) image is recorded independently. An object is illuminated with a line-focused beam. Positional information of the region illuminated by the line-focused beam is recorded with the 1D imaging microscope optics as line-profile data. By scanning the object with the line focus, 2D image data are obtained. In the same manner as for a scanning microscope optics with a multi-pixel detector, imaging modes such as phase contrast and absorption contrast can be arbitrarily configured after the image data acquisition. By combining a tomographic scan method and the SIXM system, quantitative 3D imaging is performed. Results of a feasibility study of the SIXM for 3D imaging are shown. [ABSTRACT FROM AUTHOR]

In this paper, wavelet-transform-based time-frequency domain reflectometry (WTFDR) is proposed for load impedance measurement. in order to measure the load impedance, the energy of the measured signal in the time-frequency domain, the phase difference between the reference signal and the reflected signal, the characteristic impedance, and the attenuation factor of the measured cable must all be known. Since the complex wavelet transform is composed of real and imaginary parts, the phase difference is easily obtained using the ratio of the real coefficient to the imaginary coefficient. In addition, the wavelet energy denotes the sum of the square of the modulus of the wavelet transform and describes the energy of the measured signal in the time and frequency domains. To accurately determine the characteristic impedance and attenuation factors, the power cable should be estimated as a coaxial cable. Using WTFDR with the complex mother wavelet and the estimated power cable, the load impedance can be obtained simply and accurately. Finally, real experiments for the evaluation of various load impedances are carried out to confirm the effectiveness and accuracy of the proposed method compared to the conventional time-frequency domain reflectometry. [ABSTRACT FROM AUTHOR]

Abstract: We present an averaged spectral domain phase microscopy (A-SDPM) for high-sensitive quantitative phase imaging, where multiple spectral phases from different wavenumbers are fully exploited to determine the final optical path difference (OPD). Uncertainties of recovered spectral phases and OPDs at all wavenumbers are investigated, and a threshold value for the uncertainty of OPD is set to obtain the optimized averaging. A sensitivity of 17.84pm is achieved under signal to noise ratio (SNR) of 61dB, resulting in a 4.11 fold reduction in noise compared with the single spectral phase approach. The performance of the proposed A-SDPM is further illustrated by phase imaging of a coverslip with continuous changes in OPD. [Copyright &y& Elsevier]