Single molecule detection and tracking provides at times the only possible method to observe the interactions of low numbers of biomolecules, inlcuding DNA, receptors and signal mediating proteins in living systems. However, most existing imaging methods do not enable both high sensitivity and non-invasive imaging of large specimens. In this study we report a new setup for selective plane illumination microscopy (SPIM), which enables fast imaging and single molecule tracking with the resolution of confocal microscopy and the optical penetration beyond 300 μm. We detect and report our instrumental figures of merit, control values of fluorescence properties of single nano crystals in comparison to both standard widefield configurations, and also values of nanocrystals in multicellular “fruiting bodies” of Dictyostelium, an excellent control as a model developmental system. In the Dictyostelium , we also report some of our first tracking of single nanocrystals with SPIM. The new SPIM setup represents a new technique, which enables fast single molecule imaging and tracking in living systems. 相似文献
Multidirectional selective plane illumination microscopy (mSPIM) reduces absorption and scattering artifacts and provides an evenly illuminated focal plane. mSPIM solves two common problems in light-sheet-based imaging techniques: The shadowing in the excitation path due to absorption in the specimen is eliminated by pivoting the light sheet; the spread of the light sheet by scattering in the sample is compensated by illuminating the sample consecutively from opposing directions. The resulting two images are computationally fused yielding a superior image. The effective light sheet is thinner, and the axial resolution is increased by square root 2 over single-directional SPIM. The multidirectional illumination proves essential in biological specimens such as millimeter-sized embryos. The performance of mSPIM is demonstrated by the imaging of live zebrafish embryos. 相似文献
Fluorescence microscopy (FM) has recently been applied to the detection of airborne asbestos fibers that can cause asbestosis,
mesothelioma and lung cancer. In our previous studies, we discovered that the E. coli protein DksA specifically binds to the most commonly used type of asbestos, chrysotile. We also demonstrated that fluorescent-labeled
DksA enabled far more specific and sensitive detection of airborne asbestos fibers than conventional phase contrast microscopy
(PCM). However, the actual diameter of the thinnest asbestos fibers visualized under the FM platform was unclear, as their
dimensions were below the resolution of optical microscopy. Here, we used correlative microscopy (scanning electron microscopy
[SEM] in combination with FM) to measure the actual diameters of asbestos fibers visualized under the FM platform with fluorescent-labeled
DksA as a probe. Our analysis revealed that FM offers sufficient sensitivity to detect chrysotile fibrils as thin as 30–35 nm.
We therefore conclude that as an analytical method, FM has the potential to detect all countable asbestos fibers in air samples,
thus approaching the sensitivity of SEM. By visualizing thin asbestos fibers at approximately tenfold lower magnifications,
FM enables markedly more rapid counting of fibers than SEM. Thus, fluorescence microscopy represents an advanced analytical
tool for asbestos detection and monitoring. 相似文献
This paper focuses on the mechanical properties and crystal morphology of a self-reinforced high-density polyethylene 5000S (HDPE 5000S) by simultaneously blending with 9 wt% high-molecular-weight polyethylene (HMWPE) and 9 wt% low-molecular-weight polyethylene (LMWPE) (A9) under the shear stress field which was engendered by a self-made dynamic packing injection molding (DPIM) machine. The results of mechanical properties, differential scanning calorimetry, and scanning electron microscopy characterization were as follows: (1) The tensile strength of the dynamic samples increased to 112.1 MPa, 4.85 times as much as that of static packing injection molding (SPIM) samples (23.1 MPa), as a result of realizing polyethylene's self-enhancement; (2) Shish-kebab structure was found in the dynamic samples; (3) The crystallinity of the DPIM A9 sample reached 68.6%, on increase by 18.7% compared with that of the SPIM sample. The formation of the shish-kebab structure and enhancement of mechanical properties are explained. 相似文献
We have developed a new coherent anti-Stokes Raman scattering (CARS) microscopy system with a collinear configuration for use in the fingerprint region. The system consists of a picosecond laser system and a transmission-type laser scanning microscope without a pinhole in front of the detector. The observable Raman-shift region is 900-1750 cm(-1), the spectral resolution is 30cm(-1), and the spatial resolution is smaller than 1 mum in the lateral direction and 3.2 mum in the depth direction, with objectives with a numerical aperture of 0.65. CARS spectra and images of polystyrene beads are demonstrated, and CARS imaging of a viable yeast cell is attempted. 相似文献
In order to achieve a higher lateral resolution required for ultraprecision measurement of microstructural workpieces, phase-only pupil filtering differential confocal microscopy (PFDCM), a new approach is proposed based on the differential confocal microscopy (DCM), which uses a three-zone phase-only pupil filter with lateral super-resolution capability obtained through optimized design to change the distribution of DCM three-dimensional point spread function, so that the DCM lateral resolution is therefore significantly improved while its axial resolution is slightly improved. Preliminary experimental comparison and analyses indicate that, the lateral and axial resolutions of PFDCM are better than 0.2 μm and 2 nm, respectively, when wavelength of incidence laser beam , numerical aperture of measuring lens NA=0.85, and lateral spot size with a three-zone phase-only pupil filter GT=0.65. It is therefore concluded that PFDCM is a new approach to further improvement of lateral resolution in laser probe measurement systems. 相似文献
Intravital imaging of large specimens is intrinsically challenging for postembryonic studies. Selective plane illumination microscopy (SPIM) has been introduced to volumetrically visualize organisms used in developmental biology and experimental genetics. Ideally suited for imaging transparent samples, SPIM can offer high frame rate imaging with optical microscopy resolutions and low phototoxicity. However, its performance quickly deteriorates when applied to opaque tissues. To overcome this limitation, SPIM optics were merged with optical and optoacoustic (photoacoustic) readouts. The performance of this hybrid imaging system was characterized using various phantoms and by imaging a highly scattering ex vivo juvenile zebrafish. The results revealed the system's enhanced capability over that of conventional SPIM for high‐resolution imaging over extended depths of scattering content. The approach described here may enable future visualization of organisms throughout their entire development, encompassing regimes in which the tissue may become opaque.
Knowing the influence of fluid flow perturbations on the dynamic behavior of fluid-conveying pipes is of relevance, e.g., when exploiting flow-induced oscillations of pipes to determine the fluids mass flow or density, as done with Coriolis flow meters (CFM). This could be used in the attempts to improve accuracy, precision, and robustness of CFMs. A simple mathematical model of a fluid-conveying pipe is formulated and the effect of pulsating fluid flow is analyzed using a multiple time scaling perturbation analysis. The results are simple analytical predictions for the transverse pipe displacement and approximate axial shift in vibration phase. The analytical predictions are tested against pure numerical solution using representative examples, showing good agreement. Fluid pulsations are predicted not to influence CFM accuracy, since proper signal filtering is seen to allow the determination of the correct mean phase shift. Large amplitude motions, which could influence CFM robustness, do not appear to be induced by the investigated fluid pulsation. Pulsating fluid of the combination resonance type could, however, influence CFMs robustness, if induced pipe motions go unnoticed and uncontrolled during CFM operation by feedback control. The analytical predictions offer an immediate insight into how fluid pulsation affects phase shift, which is a quantity measured by CFMs to estimate the mass flow, and lead to hypotheses for more complex geometries, i.e. industrial CFMs. The validity of these hypotheses is suggested to be tested using laboratory experiments, or detailed computational models taking fluid-structure interaction into account. 相似文献
The Heisenberg-Kitaev(HK) model on various lattices has attracted a lot of attention because it may lead to exotic states such as quantum spin liquid and topological orders.The rare-earth-based kagome lattice(KL) compounds Mg2RE3Sb3O14(RE=Gd,Er) and(RE=Nd) have q=0,120° order and canted ferromagnetic(CFM) order,respectively.Interestingly,the HK model on the KL has the same ground state long-range orders.In the theoretical phase diagram,the CFM phase re... 相似文献
For a fixed 2 μm×2 μm area of a Co/Pt-CoO perpendicular exchange bias system we image the ferromagnetic (FM) domains for various applied fields with 10-nm resolution by magnetic force microscopy (MFM). Using quantitative MFM we measure the local areal density of pinned uncompensated spins (pinUCS) in the antiferromagnetic (AFM) CoO layer and correlate the FM domain structure with the UCS density. Larger applied fields drive the receding domains to areas of proportionally higher pinUCS aligned antiparallel to FM moments. The data confirm that the evolution of the FM domains is determined by the pinUCS in the AFM layer, and also present examples of frustration in the system. 相似文献
In stimulated emission depletion (STED) microscopy, the lateral resolution is in the range of tens of nanometers depending on the sample and the instrument. The axial resolution, however, is in standard systems limited by diffraction to about 500 nm. We present an approach to three-dimensional diffraction-unlimited resolution by observing the sample at two optical angles. The system is realized by using an atomic force microscope (AFM) chip as a microreflector to deflect the STED beams near the region-of-interest (ROI), thus allowing observations at an angle ∠. Consequently, the superior lateral resolution can be utilized to resolve details in the axial direction of the main optical axis of the microscope. Here, fluorescent nanoparticles 90 nm apart and biological structures 80 nm apart along axial direction were distinguished by utilizing an off-the-shelf, commercial STED microscope, coupled with an AFM and an AFM chip micro-reflector. 相似文献
Image formation in focal modulation microscopy using quadrant apertures (QFMM) is presented. The spatial resolution is discussed: compared with confocal microscopy, QFMM can simultaneously enhance the axial and transverse resolution. In contrast to focal modulation microscopy using D-shaped apertures (DFMM), QFMM can maintain x-y symmetry of spatial resolution, thus causing less confusion in imaging interpretation. The capability of background rejection is investigated, showing QFMM has the potential to increase imaging penetration depth. The signal level is also analyzed, indicating that the preferred detector pinhole radius is greater than for DFMM, resulting in a higher signal level. 相似文献