An image slicing spectrometer (ISS) for microscopy applications is presented. Its principle is based on the redirecting of image zones by specially organized thin mirrors within a custom fabricated ...component termed an image slicer. The demonstrated prototype can simultaneously acquire a 140 nm spectral range within its 2D field of view from a single image. The spectral resolution of the system is 5.6 nm. The FOV and spatial resolution of the ISS depend on the selected microscope objective and for the results presented is 45 x 45 microm(2) and 0.45 microm respectively. This proof-of-concept system can be easily improved in the future for higher (both spectral and spatial) resolution imaging. The system requires no scanning and minimal post data processing. In addition, the reflective nature of the image slicer and use of prisms for spectral dispersion make the system light efficient. Both of the above features are highly valuable for real time fluorescent-spectral imaging in biological and diagnostic applications.
At the primary care setting, where there are often no or minimal laboratories, examinations often consist of self-testing and rapid diagnostics. Because of this, medical devices must be simple, ...robust, and easy to operate. To address these concerns, an alternate fluorescence microscope design uses ultraviolet (UV) excitation, since fluorescent dyes that are excitable in the visible region are also excitable by UV. This may allow for the removal of typical excitation, emission, and dichroic filters as optical components absorb UV wavelengths and UV is not detected by silicon based detectors. Additionally, UV has a very low penetration into samples, which may allow for controlling the depth of excitation, and thus the imaging volume. Based on these ideas, we developed a simple fluorescence microscope built completely from off-the-shelf components that uses UV to image fluorescently stained samples. The simple opto-mechanical design of the system may allow it to be more compact and easy to use, as well as decrease the overall cost of the diagnostic device. For biological validation, we imaged whole blood stained with acridine orange and performed a two-part white blood cell differential count.
The observation of ionic signaling dynamics in intact pancreatic islets has contributed greatly to our understanding of both α- and β-cell function. Insulin secretion from β-cells depends on the ...firing of action potentials and consequent rises of intracellular calcium activity (Ca2+i). Zinc (Zn2+) is cosecreted with insulin, and has been postulated to play a role in cell-to-cell cross talk within an islet, in particular inhibiting glucagon secretion from α-cells. Thus, measuring Ca2+i and Zn2+ dynamics from both α- and β-cells will elucidate mechanisms underlying islet hormone secretion. Ca2+i and intracellular Zn2+ can be measured using fluorescent biosensors, but the most efficient sensors have overlapping spectra that complicate their discrimination. Hyperspectral imaging can be used to distinguish signals from multiple fluorophores, but available hyperspectral implementations are either too slow to measure the dynamics of ionic signals or not suitable for thick samples. We have developed a five-dimensional (x,y,z,t,λ) imaging system that leverages a snapshot hyperspectral imaging method, image mapping spectrometry, and light-sheet microscopy. This system provides subsecond temporal resolution from deep within multicellular structures. Using a single excitation wavelength (488 nm) we acquired images from triply labeled samples with two biosensors and a genetically expressing fluorescent protein (spectrally overlapping with one of the biosensors) with high temporal resolution. Measurements of Ca2+i and Zn2+ within both α- and β-cells as a function of glucose concentration show heterogeneous uptake of Zn2+ into α-cells that correlates to the known heterogeneities in Ca2+i. These differences in intracellular Zn2+ among α-cells may contribute to the inhibition in glucagon secretion observed at elevated glucose levels.
A novel method for fabricating lens arrays and other non-rotationally symmetric free-form optics is presented. This is a diamond machining technique using 4 controlled axes of motion - X, Y, Z, and ...C. As in 3-axis diamond micro-milling, a diamond ball endmill is mounted to the work spindle of a 4-axis ultra-precision computer numerical control (CNC) machine. Unlike 3-axis micro-milling, the C-axis is used to hold the cutting edge of the tool in contact with the lens surface for the entire cut. This allows the feed rates to be doubled compared to the current state of the art of micro-milling while producing an optically smooth surface with very low surface form error and exceptionally low radius error.
The present work is devoted to experimental results on electrical conductivity of chitosan and chitosan acetate within temperature range 20–325K at different electric field strength. The thickness of ...the fabricated films layers was equal to several micrometers. Relation between internal structure and electrical properties is explored. The mechanism of the electrical conductivity was described prevailingly by Poole-Frenkel mechanism with contribution of hopping, thermo-activation or tunnelling from deep trapping levels.
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•Coexistence of several mechanisms of transport for chitosan derivatives.•Contribution of non-activation hopping and thermal activation processes.•Poole-Frenkel effect is dominated.•Additional important role of field emission is shown.•Hitosan and its octan derivatives may be sensors of pressure and humidity.
Preventing breast cancer will require the development of targeted strategies that can effectively block disease progression. Tamoxifen and aromatase inhibitors are effective in addressing estrogen ...receptor-positive (ER(+)) breast cancer development, but estrogen receptor-negative (ER(-)) breast cancer remains an unmet challenge due to gaps in pathobiologic understanding. In this study, we used reverse-phase protein array to identify activation of Src kinase as an early signaling alteration in premalignant breast lesions of women who did not respond to tamoxifen, a widely used ER antagonist for hormonal therapy of breast cancer. Src kinase blockade with the small-molecule inhibitor saracatinib prevented the disorganized three-dimensional growth of ER(-) mammary epithelial cells in vitro and delayed the development of premalignant lesions and tumors in vivo in mouse models developing HER2(+) and ER(-) mammary tumors, extending tumor-free and overall survival. Mechanistic investigations revealed that Src blockade reduced glucose metabolism as a result of an inhibition in ERK1/2-MNK1-eIF4E-mediated cap-dependent translation of c-Myc and transcription of the glucose transporter GLUT1, thereby limiting energy available for cell growth. Taken together, our results provide a sound rationale to target Src pathways in premalignant breast lesions to limit the development of breast cancers.
A snapshot 3-Dimensional Optical Coherence Tomography system was developed using Image Mapping Spectrometry. This system can give depth information (Z) at different spatial positions (XY) within one ...camera integration time to potentially reduce motion artifact and enhance throughput. The current (x,y,λ) datacube of (85×356×117) provides a 3D visualization of sample with 400 μm depth and 13.4 μm in transverse resolution. Axial resolution of 16.0 μm can also be achieved in this proof-of-concept system. We present an analysis of the theoretical constraints which will guide development of future systems with increased imaging depth and improved axial and lateral resolutions.
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