Light Transmission Imaging Research Articles

Mechanical and Optical Characterization of Single-shade Resin Composites Used in Posterior Teeth.

This study aimed to evaluate the optical and mechanical performance of two single-shade resin-based composites (RBCs) compared to those of a conventional RBC for restoring posterior teeth. Two single-shade RBCs, Omnichroma (Tukoyama) and Vittra Unique APS (FGM), and a conventional RBC, Filtek Z350XT shade A2 (3M Oral Care), were evaluated in this study. The optical shade-matching performance was measured using a spectrophotometer. The light emitted by VALO Grand (Ultradent) and transmitted through the 2.0-mm RBC specimens was evaluated using beam profiling. Knoop hardness (KH, N/mm2), degree of conversion (DC, %) at the top and bottom, flexural strength (FS, MPa), elastic modulus (E, GPa), postgel shrinkage (Shr, %), and shrinkage stress (MPa) were evaluated. Scanning electron microscopy (SEM) was used to characterize the filler. Data for FS, E, and Shr were analyzed by one-way analysis of variance (ANOVA) and KH and DC by repeated one-way ANOVA measurement followed by Tukey test (α=0.05). The modified von Mises stress values, light transmission, and SEM images were analyzed qualitatively. All single-shade RBCs exhibited higher chromatic adaptation than the Filtek Z350XT (p<0.001). Omnichroma exhibited less color difference than Vittra Unique APS, irrespective of the shade. The light transmitted through Omnichroma and Vittra Unique APS increased during polymerization. KH and DC values were significantly reduced from the top to the bottom of the specimens for all RBCs (p<0.001); however, the ratio values were always higher than 80%. In general, all RBCs demonstrated similar mechanical properties. All RBCs exhibited a similar FS (p=0.083) and Shr value (p=0.144). Filtek Z350XT exhibited significantly higher E (p<0.001) than both single-shade RBCs. All RBCs exhibited similar shrinkage stress during restoration and similar residual stress during occlusal loading. Single-shade Omnichroma and Vittra Unique APS increased light transmission during light-activation, demonstrating better chromatic adaptation than conventional Filtek Z350XT. In general, Omnichroma and Vittra Unique APS exhibited similar mechanical properties and shrinkage stress distributions as Filtek Z350XT during light-activation and occlusal loading.

Constructing Efficient and Thermostable Red‐NIR Emitter via Cross Relaxation and Crystal‐Field Engineering of Holmium‐Based Perovskite‐Type Half Metal

AbstractLanthanide ions, as dopants, have evoked widespread research interest owing to the rich optical, magnetic, and electrical properties, but their luminescent intensity is always limited by typical concentration quenching. Herein, a holmium‐based double perovskite of Cs2NaHoCl6 is reported, which surprisingly breaks through this barrier and achieves efficient red‐NIR emission by virtue of the large unit cell, low phonon energy, high content of activators, and cross relaxation phenomenon between Ho3+. The heavy Ho3+ also endows the intriguing half‐metallic nature with a down‐spin conducting band and an up‐spin insulating band. After performing ion doping on crystallographic sites of Na+ and Ho3+, the photoluminescence quantum yield of such red‐NIR emitter under 450 nm excitation is dramatically promoted to 82.3%, benefiting from the improved crystal field environment that alleviates the parity forbidden rule and suppresses non‐radiative recombination loss. Furthermore, the heat‐favorable phonon‐assisted population processes enable the robust photostability against thermal quenching. By combining a 450 nm chip, the red‐NIR light‐emitting diodes are fabricated, in which the wide‐coverage NIR emissions are ideally suited for medical light source, night vision, nondestructive examination, and transmission imaging. It is believed that this work will open an avenue for enhancing the fluorescence of lanthanide ions and developing advanced spintronic materials.

Miniaturized Non-Contact Heating and Transmitted Light Imaging Using an Inexpensive and Modular 3D-Printed Platform for Molecular Diagnostics.

The ability to simultaneously heat and image samples using transmitted light is crucial for several biological applications. However, existing techniques such as heated stage microscopes, thermal cyclers equipped with imaging capabilities, or non-contact heating systems are often bulky, expensive, and complex. This work presents the development and characterization of a Miniaturized Optically-clear Thermal Enclosure (MOTE) system-an open-source, inexpensive, and low-powered modular system-capable of convectively heating samples while simultaneously imaging them with transmitted light. We develop and validate a computational fluid dynamics (CFD) model to design and optimize the heating chamber. The model simulates velocity and temperature profiles within the heating chamber for various chamber materials and sizes. The computational model yielded an optimal chamber dimension capable of achieving a stable temperature ranging from ambient to 95 °C with a spatial discrepancy of less than 1.5 °C, utilizing less than 8.5 W of power. The dual-functionality of the MOTE system, enabling synchronous heating and transmitted light imaging, was demonstrated through the successful execution of paper-based LAMP reactions to detect λ DNA samples in real-time down to 10 copies/µL of the target concentration. The MOTE system offers a promising and flexible platform for various applications, from molecular diagnostics to biochemical analyses, cell biology, genomics, and education.

Investigating Soil-Root Interactions with the Numerical Model R-SWMS.

In this chapter, we present the Root and Soil Water Movement and Solute transport model R-SWMS, which can be used to simulate flow and transport in the soil-plant system. The equations describing water flow in soil-root systems are presented and numerical solutions are provided. An application of R-SWMS is then briefly discussed, in which we combine in vivo and in silico experiments in order to decrypt water flow in the soil-root domain. More precisely, light transmission imaging experiments were conducted to generate data that can serve as input for the R-SWMS model. These data include the root system architecture, the soil hydraulic properties and the environmental conditions (initial soil water content and boundary conditions, BC). Root hydraulic properties were not acquired experimentally, but set to theoretical values found in the literature. In order to validate the results obtained by the model, the simulated and experimental water content distributions were compared. The model was then used to estimate variables that were not experimentally accessible, such as the actual root water uptake distribution and xylem water potential.

Reflected cross-polarized light microscopy as a method for measuring collagen fiber crimp in musculoskeletal tissues

Many musculoskeletal tissues are composed primarily of type I collagen, which takes on a periodic crimp morphology that allows large tensile strains in the tissue. The spatial period of collagen fiber crimp may be used to infer internal strains in a tissue and is typically measured using transmitted cross-polarized light imaging of thin slices. However, slicing may induce specimen distortion and precludes mechanical loading of the specimen during imaging. We hypothesized that reflected cross-polarized light imaging of thick tissue explants would yield crimp period measurements comparable to those obtained from transmitted light imaging of thin slices. We further hypothesized that these measurements would be sensitive to applied uniaxial strain in the fiber direction. These hypotheses were tested by imaging both intervertebral disc outer annulus fibrosus and medial collateral ligament tissue specimens. We found that both transmitted and reflected light yielded similar crimp period measurements for intervertebral disc tissue, with an overall average of 43.5 ± 11.5 μm. Reflected light yielded a significantly higher crimp period with lower variance than transmission through thin specimens (54.1 ± 10.6 μm versus 50.4 ± 16.0 μm) in the ligament. Upon application of axial tension, crimp periods in both fibers increased at a rate of approximately three times the applied strain (with 3.17% applied strain yielding a 9.64 ± 4.4% increase in crimp period in the disc and an 11.7 ± 3.7% increase in the ligament), indicating significant fibril sliding. In support of our hypotheses, these findings suggest that reflected cross-polarized light is a suitable method for measuring collagen fiber crimp in musculoskeletal tissues, both statically and under tension.

An experimental method to study the absorption capacity of paper towels

This study proposes an experimental method for the in-plane liquid wicking to determine the absorption capacity of retail paper towels. Individual plies of the paper towels were tested to minimize the transverse wicking effects on surface wetting. The method involves arbitrary point source injection of liquid into the paper towel surface while recording microscopic images of the wetted areas as liquid spreads. The samples were selected from two main manufacturing processes: conventional wet pressing and through air drying. The tested liquids were water and decane with various driving forces. Two distinct imaging systems, infrared light absorption imaging and visible light transmission imaging, monitored and recorded the wetting process. The wetted regions were calculated to generate the wetting graphs, which illustrate both the dynamic and static wetting behaviors.It was found the amount of driving force has a negligible effect on the maximum wetted area formed on the surface.So, the maximum wetted area and the paper grammage were applied to determine the absorption capacity of the tested towels. Moreover, the absorption capacity results were validated by the basket-immersion test method (ISO 12625-8).Therefore, the proposed method in this work enables quantification of the absorption capacity of papertowels.

The effects of a simple optical clearing protocol on the mechanics of collagenous soft tissue

Optical clearing of biological tissues improves imaging depth for light transmission imaging modalities such as two-photon microscopy. In studies that investigate the interplay between microstructure and tissue-level mechanics, mechanical testing of cleared tissue may be useful. However, the effects of optical clearing on soft tissue mechanics have not been investigated. Thus, we set out to quantify the effects of a simple and effective optical clearing protocol on the mechanics of soft collagenous tissues using ovine mitral valve anterior leaflets as a model system. First, we demonstrate the effectiveness of an isotonic glycerol-DMSO optical clearing protocol in two-photon microscopy. Second, we evaluate the mechanical effects of optical clearing on leaflets under equibiaxial tension in a dependent study design. Lastly, we quantify the shrinkage strain while traction-free and the contractile forces while constrained during clearing. We found the optical clearing protocol to improve two-photon imaging depth from ~100 μm to ~500–800 μm, enabling full-thickness visualization of second-harmonic generation, autofluorescent, and fluorophore-tagged structures. Under equibiaxial tension, cleared tissues exhibited reduced circumferential (p < 0.001) and radial (p = 0.009) transition stretches (i.e. stretch where collagen is recruited), and reduced radial stiffness (p = 0.031). Finally, during clearing we observed ~10–15% circumferential and radial compressive strains, and when constrained, ~2mN of circumferential and radial traction forces. In summary, we suggest the use of this optical clearing agent with mechanical testing be done with care, as it appears to alter the tissue’s stress-free configuration and stiffness, likely due to tissue dehydration.

FVSR-Net: an end-to-end Finger Vein Image Scattering Removal Network

Based on the ever-growing emphasis on high security of biometrics recognition, finger vein recognition has captured more and more attention. However, due to the light scattering in human skin tissue during near-infrared light transmission imaging, the collected finger vein images are always degraded dramatically, which leads to the unreliability of vein features and the low accuracy of finger vein recognition. Although considerable traditional methods are dedicated to eliminating the effect of light scattering on imaging, the clearer images cannot be output end-to-end, the processes of restoring degraded finger vein images are laborious as well. Thereupon, with the aim at improving the visibility of finger vein features and generating clear finger vein images end-to-end, this effort represents a simple and effective method utilizing Convolutional Neural Network (CNN). First, in our previous work, the biological optical model used to settle the matter of skin scattering is modified to output restored finger vein images in an end-to-end manner. Second, a multi-scale CNN named E-Net is established to acquire credible estimation map of finger vein features, which is conducive to the acquisition of pleasurable restoration outcome. Finally, a scattering removal framework, addressed as Finger Vein Image Scattering Removal Network (FVSR-Net), is designed via integrating improved biological optical model with E-Net. Such a novel design facilitates the generation of clearer venous regions and increases computational efficiency and stability. Experiments accomplished on two finger vein datasets demonstrate the superiority of our proposed method in terms of visual quality and recognition performance.

Explainable AI Framework for Imaging-Based Predictive Maintenance for Automotive Applications and Beyond

Predictive maintenance applications for a wide variety of industrial and commercial components are increasingly utilizing imaging-based sensors along with AI (artificial intelligence)/ML (machine learning) based analytics to determine wear of components. Credibility of the analytics, especially for component health, is strongly dependent on explainability. We initially introduce an explainable framework involving a novel light transmission image processing–based methodology utilizing statistical distance metrics (e.g., Wasserstein distance (WD), Kolmogorov-Smirnov statistic) for discriminative classification of unstructured images combined with Bayesian inference/regression to estimate wear level for an air filter application. Subsequently, we incorporate neural network–based models into this framework to develop an AI framework retaining a high level of explainability. The explainable elements of this novel AI model include generation of a statistical distance pseudometric with a feedforward neural network as a discriminative classifier, a spatial block bootstrapping approach to generate synthetic training data, and the use of this discriminant classifier as a predictor in a Bayesian inference/regression model to predict wear levels with 95% prediction and credible intervals. This explainable AI framework can be extended to other families of applications utilizing synthetically generated unstructured and structured images in predictive maintenance and health monitoring.

Recognition of Heterogeneous Edges in Multiwavelength Transmission Images Based on the Weighted Constraint Decision Method.

Multiwavelength light transmission imaging provides a possibility for early detection of breast cancer. However, due to strong scattering during the transmission process of breast tissue analysis, the transmitted image signal is weak and the image is blurred and this makes heterogeneous edge detection difficult. This paper proposes a method based on the weighted constraint decision (WCD) method to eliminate the erosion and checkerboard effects in image histogram equalization (HE) enhancement and to improve the recognition of heterogeneous edge. Multiwavelength transmission images of phantom are acquired on the designed experimental system and the mask image with high signal-to-noise ratio (SNR) is obtained by frame accumulation and an Otsu thresholding model. Then, during image enhancement the image is divided into low-gray-level (LGL) and high-gray-level (HGL) regions according to the distribution of light intensity in image. And the probability density distribution of gray level in the LGL and HGL regions are redefined respectively according to the WCD method. Finally, the reconstructed image is obtained based on the modified HE. The experimental results show that compared with traditional image enhancement methods, the WCD method proposed in this paper can greatly improve the contrast between heterogeneous region and normal region. Moreover, the correlation between the original image data is maintained to the greatest extent, so that the edge of the heterogeneity can be detected more accurately. In conclusion, the WCD method not only accurately identifies the edge of heterogeneity in multiwavelength transmission images, but it also could improve the clinical application of multiwavelength transmission images in the early detection of breast cancer.

A numerical–experimental assessment of wall impingement models for spark-ignition direct-injection engines

Liquid wall impingement in direct-injection engines can cause soot and hydrocarbon emissions as well as reduced combustion efficiency. This study focuses on detailed evaluations of numerical droplet impingement criteria that govern the onset of splash. The five selected splash criteria, which all extrapolate from single-droplet impacts to full sprays, are representative of those currently in use for spark-ignition direct-injection engines. The computations examined the sensitivity of impinging spray simulations to the splash criteria for a high-pressure, direct-injection swirl spray under atmospheric conditions impinging at a 45° angle onto a flat plate. The numerical results were compared to an unusually extensive set of experimental data: Mie scattering and light transmission imaging, plus quantitative refractive index matching measurements of the fuel film area and thickness, and phase Doppler interferometry measurements of droplet size and velocity near the plate. Good qualitative and at least fair quantitative agreement was obtained for the global spray impingement and wall film formation, especially for single-drop criteria that include the effect of viscosity. The film area and shape were insensitive to the splash criteria, illustrating the importance of film thickness measurements for validating simulations. The results also revealed the sensitivity of impingement calculations to droplet arrival frequency when that is taken into account. In general, the comparisons indicated the need to capture the effect of multiple droplets impinging on the wall at irregular frequencies in the criterion, as well as other important physics of the droplet–wall interaction that may mask the true effect of the impingement criterion.

Microfluidics to determine the diffusive mass transfer of a low viscosity solvent into a high viscosity hydrocarbon

In this work, a microfluidic platform along with X-ray computerized tomography were employed to analyze diffusive mass transfer of a low viscosity solvent (hexane) into a high viscosity hydrocarbon (bitumen). T-shaped microfluidic channels were fabricated to measure the diffusion coefficient in significantly shorter times and lower sample volume compared with traditional methods. Semitransparent nature of bitumen facilitates the application of light transmission imaging during the time and relating intensities to solvent concentration. Diffusion mass transfer was studied with respect to Fickian and Single-File mass transfer mechanisms and corresponding equation was applied to calculate both constant and concentration dependent diffusion coefficients. The accuracy of Fickian mass transfer mechanism was confirmed with calculating values of fitting parameter (i.e. nw) in addition to superimposition of data for both techniques. The optimum values of constant diffusion coefficient for T-shaped microchannel and X-ray technique were 2 × 10−10 and 1.8 × 10−10 m2·s−1, respectively. Concentration dependent diffusion coefficients ranged from 1 × 10−12 to 3.6 × 10−10 m2·s−1 for the experiments that reveal constant mutual diffusion coefficient assumption can result in significantly high errors particularly at low and high solvent mass fractions.

The Observation of the Vein Distribution of a Partial Toe-Transfer Flaps with a Short Vascular Pedicle.

When performing partial toe-transfer flaps with a short vascular pedicle, as the flap becomes smaller, the likelihood of securing veins in the flap decreases. The purpose of this study was to clarify how frequently the partial toe-transfer flap with a short pedicle (free vascularized half-big toenail flap) contains veins and elucidate how frequently we can secure the veins with an artery via the first web space approach alone, using the Genial Viewer (a near-infrared light transmission imaging device). We observed the dorsal vein images of the bilateral big toes of 250 volunteers (male, n = 125; female, n = 125) using the device. We counted the total number of dorsal veins in the big toe, the veins that crossed the margin of the region equivalent to the half-big toenail flap, and the veins that branched off from the fibular side of the flap area. An unpaired Student's t-test was used for the statistical analyses. All of the dorsal big toes contained veins. The mean number of the veins was 2.3 (range, 1-4). Branched-off veins were observed in the area equivalent to the half-big toenail flap in 496 (99.2%) of the big toes, and the mean number of veins was 1.9 (range, 0-4). In four cases, the region contained no veins (unilaterally). Branched-off veins were observed in the first web space in 440 (88.0%) of the big toes, and the mean number of veins was 0.9 (range, 0-2). The present study indicated high consistency of the veins in partial toe-transfer flaps with a short vascular pedicle and the high possibility of harvesting a flap with only exposing the first web space. In addition, in most cases, the flap will include one or, at most, two veins in the first web space.

Practical Tips for Cellular Quantification and Imaging Using Thermo Scientific Varioskan LUX Multimode Reader and Invitrogen EVOS FL Auto Cell Imaging System

Practical Tips for Cellular Quantification and Imaging Using Thermo Scientific Varioskan LUX Multimode Reader and Invitrogen EVOS FL Auto Cell Imaging System

Recognition of Banknote Fitness Based on a Fuzzy System Using Visible Light Reflection and Near-infrared Light Transmission Images.

Fitness classification is a technique to assess the quality of banknotes in order to determine whether they are usable. Banknote classification techniques are useful in preventing problems that arise from the circulation of substandard banknotes (such as recognition failures, or bill jams in automated teller machines (ATMs) or bank counting machines). By and large, fitness classification continues to be carried out by humans, and this can cause the problem of varying fitness classifications for the same bill by different evaluators, and requires a lot of time. To address these problems, this study proposes a fuzzy system-based method that can reduce the processing time needed for fitness classification, and can determine the fitness of banknotes through an objective, systematic method rather than subjective judgment. Our algorithm was an implementation to actual banknote counting machine. Based on the results of tests on 3856 banknotes in United States currency (USD), 3956 in Korean currency (KRW), and 2300 banknotes in Indian currency (INR) using visible light reflection (VR) and near-infrared light transmission (NIRT) imaging, the proposed method was found to yield higher accuracy than prevalent banknote fitness classification methods. Moreover, it was confirmed that the proposed algorithm can operate in real time, not only in a normal PC environment, but also in an embedded system environment of a banknote counting machine.

Fricke and polymer gel 2D dosimetry validation using Monte Carlo simulation

Complexity in modern radiotherapy treatments demands advanced dosimetry systems for quality control. These systems must have several characteristics, such as high spatial resolution, tissue equivalence, three-dimensional resolution, and dose-integrating capabilities. In this scenario, gel dosimetry has proved to be a very promising option for quality assurance. In this study, the feasibility of Fricke and polymer gel dosimeters suitably shaped in form of thin layers and optically analyzed by visible light transmission imaging has been investigated for quality assurance in external radiotherapy. Dosimeter irradiation was carried out with a 6-MV photon beam (CLINAC 600C). The analysis of the irradiated dosimeters was done using two-dimensional optical transmission images. These dosimeters were compared with a treatment plan system using Monte Carlo simulations as a reference by means of a gamma test with parameters of 1 mm and 2%. Results show very good agreement between the different dosimetric systems: in the worst-case scenario, 98% of the analyzed points meet the test quality requirements. Therefore, gel dosimetry may be considered as a potential tool for the validation of other dosimetric systems.

Optimisation approaches for concurrent transmitted light imaging during confocal microscopy.

BackgroundThe transmitted light detectors present on most modern confocal microscopes are an under-utilised tool for the live imaging of plant cells. As the light forming the image in this detector is not passed through a pinhole, out-of-focus light is not removed. It is this extended focus that allows the transmitted light image to provide cellular and organismal context for fluorescence optical sections generated confocally. More importantly, the transmitted light detector provides images that have spatial and temporal registration with the fluorescence images, unlike images taken with a separately-mounted camera.ResultsBecause plants often provide difficulties for taking transmitted light images, with the presence of pigments and air pockets in leaves, this study documents several approaches to improving transmitted light images beginning with ensuring that the light paths through the microscope are correctly aligned (Köhler illumination). Pigmented samples can be imaged in real colour using sequential scanning with red, green and blue lasers. The resulting transmitted light images can be optimised and merged in ImageJ to generate colour images that maintain registration with concurrent fluorescence images. For faster imaging of pigmented samples, transmitted light images can be formed with non-absorbed wavelengths. Transmitted light images of Arabidopsis leaves expressing GFP can be improved by concurrent illumination with green and blue light. If the blue light used for YFP excitation is blocked from the transmitted light detector with a cheap, coloured glass filters, the non-absorbed green light will form an improved transmitted light image. Changes in sample colour can be quantified by transmitted light imaging. This has been documented in red onion epidermal cells where changes in vacuolar pH triggered by the weak base methylamine result in measurable colour changes in the vacuolar anthocyanin.ConclusionsMany plant cells contain visible levels of pigment. The transmitted light detector provides a useful tool for documenting and measuring changes in these pigments while maintaining registration with confocal imaging.

Visualization and analysis of nanoparticle transport and ageing in reactive porous media

We present quasi-3D visualization and analysis of engineered nanoparticle (ENP) transport behavior in an experimental setup that uses a transmitted light imaging technique. A flow cell was packed with specially adapted, water-transparent, spherical polyacrylamide beads, which carry a negative surface charge representative of many natural environments. Ubiquitous, oppositely-charged ENPs – Au and Ag NPs – were synthesized and introduced into a flow cell subjected to a macroscopically uniform flow field via point source pulse injection, at three different flow rates. The negatively-charged ENPs behaved like a conservative tracer, in terms of spatio-temporal plume evolution. The positive AgNPs, however, displayed a decrease in their initially strong tendency to attach to the oppositely-charged porous medium. As a result, immobilization of the positive AgNPs was spatially and temporally limited to the vicinity of the point of injection; beyond this region, the AgNPs were mobile and effluent contained AgNPs with hydrodynamic diameters significantly larger than those of the injected AgNPs. This behavior is understood by dynamic light scattering and ζ potential measurements, which showed aggregation processes and inversion in particle surface charge to occur during transport of the positive ENPs. These findings have broad implications for ENP mobility and reactivity in the environment.

Evaluation of natural hog casings modified by surfactant solutions combined with lactic acid by response surface methodology

The effects of soy lecithin concentrations (X1, 1:25–1:30), soy oil concentrations (X2, 0%–2.5%), residence time for surfactant solutions (X3, 60–90 min) and lactic acid concentrations (X4, 18–21 ml/kg) on technological properties of hog casings were evaluated by response surface methodology (RSM). The burst pressure, maximum rupture force, and elongation of both uncooked treated casings (UTC) and cooked treated casings (CTC) were determined. The histological structures of UTC and CTC were observed by light microscopy and transmission electron microscope and images illustrated that casings became more porous after treatments. Polynomial regression models on burst pressure of UTC (P < 0.05) and CTC (P < 0.05), maximum rupture force of UTC (P < 0.01) and elongation of CTC (P < 0.01) were established. Sausage was made using modified casing with the best resistance of burst pressure or rupture force. Bursting during immersion vacuum cooling did not happen to sausages made from these modified casings.

Objective paper structure comparison: Assessing comparison algorithms

More than just being a substrate, paper can also provide evidence for the provenance of documents. An earlier paper described a method to compare paper structure, based on the Fourier power spectra of light transmission images. Good results were obtained by using the 2D correlation of images derived from the power spectra as a similarity score, but the method was very computationally intensive. Different comparison algorithms are evaluated in this paper, using information theoretical criteria. An angular invariant algorithm turned out to be as effective as the original one but 4 orders of magnitude faster, making the use of much larger databases possible.