Visibility Enhancement Research Articles

NMR metabolomics to study the metabolic response of human osteoblasts to non-poled and poled poly (L-lactic) acid.

Untargeted nuclear magnetic resonance (NMR) metabolomics was employed, for the first time to our knowledge, to characterize the metabolome of human osteoblast (HOb) cells and extracts in the presence of non-poled or negatively poled poly-L-lactic acid (PLLA). The metabolic response of these cells to this polymer, extensively used in bone regeneration strategies, may potentially translate into useful markers indicative of in vivo biomaterial performance. We present preliminary results of multivariate and univariate analysis of NMR spectra, which have shown the complementarity of lysed cells and extracts in terms of information on cell metabolome, and unveil that, irrespective of poling state, PLLA-grown cells seem to experience enhanced oxidative stress and activated energy metabolism, at the cost of storage lipids and glucose. Possible changes in protein and nucleic acid metabolisms were also suggested, as well as enhanced membrane biosynthesis. Therefore, the presence of PLLA seems to trigger cell catabolism and anti-oxidative protective mechanisms in HOb cells, while directing them towards cellular growth. This was not sufficient, however, to lead to a visible cell proliferation enhancement in the presence of PLLA, although a qualitative tendency for negatively poled PLLA to be more effective in sustaining cell growth than non-poled PLLA was suggested. These preliminary results indicate the potential of NMR metabolomics in enlightening cell metabolism in response to biomaterials and their properties, justifying further studies of the fine effects of poled PLLA on these and other cells of significance in tissue regeneration strategies.

Facile synthesis of m-phenylenediamine-based nanospheres coated with poly(m-phenylenediamine) for building bright iridescent structural color

As significant species of artificial photonic crystals, spherical crystals have attracted great attention. However, the variation of nanospheres for building crystalline arrays is still insufficient for large-scale application and the diversity of them remains to be increased. The enhancement of structural color visibility is another noteworthy subject and fabricating composite particles containing black materials to eliminate the disturbance of scattering and background light is an effective method. Herein, a new monodisperse m-phenylenediamine-based polymer sphere was facilely synthesized as structural color material and further coated by a poly(m-phenylenediamine) black shell for saturation enhancement. Moreover, for the high compatibility with other materials and easy preparation of poly(m-phenylenediamine), the coating procedure was quite effortless and efficient. To the best of our knowledge, this is the first work to synthesize such a monodisperse nanosphere from aromatic diamine and use poly(m-phenylenediamine) as stray light absorber to wrap the monodispersed nanosphere still with high uniformity. Such designation provides new candidate structural color material and optional black additive for wider applications on spherical crystals.

Visibility Enhancement during Severe Weather—Object Tracking with Bounding Box

Visibility Enhancement during Severe Weather—Object Tracking with Bounding Box

Multi-scale fusion algorithm of intensity and polarization-difference images based on edge information enhancement

To better integrate complementary and redundant information from different source images, improve the edge information, and facilitate the target detection. A multi-scale fusion algorithm of intensity and polarization-difference (PD) images based on edge information enhancement is proposed. Firstly, intensity images are obtained by the polarization information analysis method. PD images are obtained by the adaptive polarization-difference imaging approach based on the principle of minimum mutual information. Secondly, guided filter, affine transformations and Block-Matching and 3D filtering are embedded in visibility enhancement to improve the intensity and PD images. Thirdly, the two images are decomposed into high-frequency and low-frequency images by the dual-tree complex wavelet transform (DT-CWT). The high-frequency and low-frequency images are fused by the fusion rules based on edge detection and the regional variance matching degree respectively. Finally, the fusion image is obtained by the inverse DT-CWT. Experimental results demonstrate that fusion images of the proposed algorithm are significantly improved in information entropy, average gradient, and spatial frequency. Compared with the existing methods, it can achieve a better edge enhancement for images in a turbid medium.

Zinc oxide incorporated carbon nanotubes or graphene oxide nanohybrids for enhanced sonophotocatalytic degradation of methylene blue dye

Zinc oxide (ZnO) nanocrystallites with different weight ratios are incorporated into carbon nanotubes (ZnO/CNTs) or graphene oxide (ZnO/GO) nanohybrids using ultrasonication/hydrothermal approach. The produced nanohybrids were tested in heterogeneous photocatalytic degradation of methylene blue dye (MB) under visible light illumination and in-situ ultrasonication. The zinc oxide incorporated carbon nanotubes nanohybrid having about 70 wt% of ZnO (ZnO(70)/CNT) showed marked visible light photocatalytic activity enhancement for MB degradation (99%, 0.5 g/L catalyst, 0.015 min−1) compared to the rest of the nanohybrids. The performance of MB degradation using ZnO(70)/CNT nanohybrid was even enhanced during employing the dual sonophotocatalysis approach achieving a rate constant of 0.019 min−1. This arises from the structural advantages at the ZnO(70)/CNT interface by which an improvement in electronic conductivity, facile electron transfer, charge carriers separation and increased oxygen vacancies were thoroughly achieved. This was highly ascertained via the catalysts characterization performed via many physiochemical techniques including XRD, TEM-SAED, FTIR, UV–Vis diffuse reflectance, and electrical conductivity, IPCE, PL and EIS. The scavenger studies of the photocatalytic and sonophotocatalytic processes of the MB degradation using ZnO(70)/CNT illustrate the importance of OH (followed by an electron) and holes (followed by OH), respectively proposing the importance of direct and indirect production of OH; as a strong oxidizing moiety.

Fog removal in images using improved dark channel prior and contrast limited adaptive histogram equalization

It is necessary to perform fog removal from an image based on the estimation of depth to increase the visibility of a scene. In this paper, we propose a new algorithm to eradicate fog from images in which fog is defined as a state or cause of perplexity or confusion with respect to the image. It runs at high speed and simultaneously minimizes the halo-artifact with a new median operator in dark channel prior. The proposed method is based on Guided Filter for transmission-map refinement and Contrast Limited Adaptive Histogram Equalization (CLAHE) for visibility improvement. It preserves small details while remaining robust against density of fog, and recovers scene contrast simultaneously. Guided filter improved the transmission map acquired from Median dark channel prior (MDCP), which is an improvement of the Dark Channel Prior DCP by the use of median operation. All of the parameters used in our method are data driven. The quality of algorithm has been validated on several types of fog-degraded images where considerable variation in contrast and illumination exists. Moreover, its performance is compared with the other state-of-the-art methods. The experimental results indicate that the proposed method effectively restores the color and contrast of scene as well as produces satisfactory information in homogeneous fog. It outperforms the existing fog removal methods for run time computational time and other evaluation metrics for rating of visibility enhancement. The proposed method conserves small details part of the image when outstanding vigorous against concentration of fog, and recuperate scene contrast instantaneously. It controls at a high speed than the existing approaches and can diminish the halo effect.

Random scattering of images and visibility enhancement via stochastic resonance

We investigate numerically the random scattering of two-dimensional (2-D) images and the visibility enhancement via stochastic resonance both in intensity and momentum spaces. The multiple scattering destroys the direct transmission of photons, but some ballistic photons carrying the image information still penetrate the scattering media. The underlying ballistic image signals exhibit an instability and are enhanced at the expense of scattering noise under self-focusing nonlinearity, which is described as a stochastic resonance. It is found that the higher ratio of ballistic signals to scattering noise triggers a stronger instability. The effect of visibility enhancement in different scattering conditions is discussed, and the 2-D quasiparticle motion model is designed to analyze the nonlinear dynamic evolution. Our results provide potential guidance for noisy image detection.

Visible light enhancement of ammonia detection using silver nanoparticles decorated on reduced graphene oxide

A novel NH3 gas sensor based on reduced graphene oxide sheets (rGO) with uniformly decorated silver nanoparticles (AgNPs) on its surface is presented in this work. The aqueous solution containing silver nitrate, gelatin and graphene oxide (GO) is exposed to acoustic energy to reduce the silver nanoparticle on rGO sheets. FESEM image and EDX spot analysis show that an ultrafine spherical AgNPs with the size of about 20–30 nm are uniformly distributed on the rGO sheets. Small Raman shift of centered peaks at 1960 cm−1 indicate the decoration of AgNPs on rGO. The UV–vis absorption peaks show a red shift toward visible spectrum from 267 nm for rGO to 459 nm for rGO decorated with AgNPs. The AgNPs/rGO nano composite as an active layer over the Cr/gold interdigited electrode is fabricated using lithography technique and are tested using a semi-automatic static set up. The sensitivity of the AgNPs/rGO is about 5.8 for 250 ppb of NH3 gas detection. While this sensor shows reproducible, stable and fully recoverable response, its limit of detection (LOD) for NH3 gas is 100 ppt. The response and recovery times are 76 and 84 s respectively. The sensor exhibits an even better sensitivity of about 1.7 times for ammonium gas detection at room temperature when it is expose to visible light of 10 mW cm−2 (blue LED) which is believed to be due to the surface plasmon resonance (SPR) and spillover effects.

Visibility Enhancement by Integrating Refocusing and Direct-Global Separation with Contact Imaging

Contact imaging is a compact lensless microscopy technique that allows observation of living cells placed directly on a charge-coupled device sensor. However, captured images exhibit low visibility in general. This work is aimed at integrating computational refocusing and high-frequency illumination into contact imaging to enhance the visibility of the captured images. Refocusing contributes to the synthesis of shallow depth-of-field images from the light field captured by moving a point light source. The visibility may be enhanced via high-frequency illumination. Naïve integration of both techniques requires several observations. Therefore, we propose an efficient integration from reduced observations by reformulating the computational refocusing applied in contact imaging. Furthermore, we developed a prototype system that demonstrates the effectiveness of the proposed method.

A signal-on nanobiosensor for VEGF165 detection based on supraparticle copper nanoclusters formed on bivalent aptamer

In this study, a signal-on nanobiosensor based on bivalent aptamer-Cu nanocluster was designed and optimized for specific and sensitive detection of VEGF165. The VEGF165 is known as a promising biomarker in different diseases such as cancer in the angiogenic stage. Detection and quantification of VEGF165 is a crucial step in diagnosis and monitoring the treatment plan. The represented nanostructure consists of multimerized VEGF165 aptamer joint with ssDNA based linker in the middle and poly thymine sequences on both 3′ and 5′ ends as a template for Cu-nanocluster supraparticle formation. This self-assembled structure leads to accurate controlling of aggregation in the presence of VEGF165. This study is the first report for Cu nanocluster nucleation on ploy thymine tails of ssDNA which performed in two reduction steps to form stable CuNC supraparticle. The sensing strategy was designed based on the target-induced structure switching mode of the aptamer. In the presence of VEGF165, due to self-assembly induced emission and aggregation-induced emission phenomena this nanostructure depicted the visible wavelength shift and enhancement in the fluorescence emission intensity. Also, the results of the analytical performance of this nanobiosensor indicated the LOD of 12 pM which revealed high rate sensitivity. This aptasensor exhibited stability and decent response linearity range (10–800 pM, R2 = 0.9943). The selectivity and specificity assessment showed high discriminant capability in the real serum sample. In conclusion, this signal-on nanobiosensor provides a facile, sensitive and reliable assay for clinical monitoring of the VEGF165 concentration in serum without further sample preparation.

Nanostructured TiO2 anatase-rutile-carbon solid coating with visible light antimicrobial activity

TiO2 photocatalyst is of interest for antimicrobial coatings on hospital touch-surfaces. Recent research has focused on visible spectrum enhancement of photocatalytic activity. Here, we report TiO2 with a high degree of nanostructure, deposited on stainless steel as a solid layer more than 10 μm thick by pulsed-pressure-MOCVD. The TiO2 coating exhibits a rarely-reported microstructure comprising anatase and rutile in a composite with amorphous carbon. Columnar anatase single crystals are segmented into 15–20 nm thick plates, resulting in a mille-feuilles nanostructure. Polycrystalline rutile columns exhibit dendrite generation resembling pine tree strobili. We propose that high growth rate and co-deposition of carbon contribute to formation of the unique nanostructures. High vapor flux produces step-edge instabilities in the TiO2, and solid carbon preferentially co-deposits on certain high energy facets. The equivalent effective surface area of the nanostructured coating is estimated to be 100 times higher than standard TiO2 coatings and powders. The coatings prepared on stainless steel showed greater than 3-log reduction in viable E coli after 4 hours visible light exposure. The pp-MOCVD approach could represent an up-scalable manufacturing route for supported catalysts of functional nanostructured materials without having to make nanoparticles.

Uniform Distorted Scene Reduction on Distribution of Colour Cast Correction

Scene in the photo occulated by uniform particles distribution can degrade the image quality accidently. State of the art pre-processing methods are able to enhance visibility by employing local and global filters on the image scene. Regardless of air light and transmission map right estimation, those methods unfortunately produce artifacts and halo effects because of uncorrelated problem between the global and local filter’s windows. Besides, previous approaches might abruptly eliminate the primary scene structure of an image like texture and colour. Therefore, this study aims not solely to improve scene image quality via a recovery method but also to overcome image content issues such as the artefacts and halo effects, and finally to reduce the light disturbance in the scene image. We introduce our proposed visibility enhancement method by using joint ambience distribution that improves the colour cast in the image. Furthermore, the method is able to balance the atmospheric light in correspondence to the depth map accordingly. Consequently, our method maintains the image texture structural information by calculating the lighting estimation and maintaining a range of colours simultaneously. The method is tested on images from the Benchmarking Single Image Dehazing research by assessing their clear edge ratio, gradient, range of saturated pixels, and structural similarity metric index. The scene image restoration assessment results show that our proposed method had outperformed resuls from the Tan, Tarel and He methods by gaining the highest score in the structural similarity index and colourfulness measurement. Furthermore, our proposed method also had achieved acceptable gradient ratio and percentage of the number of saturated pixels. The proposed approach enhances the visibility in the images without affecting them structurally.

Ultrasensitive room temperature ppb-level NO2 gas sensors based on SnS2/rGO nanohybrids with P–N transition and optoelectronic visible light enhancement performance

SnS2/rGO gas sensors were developed, with P–N transition response for room temperature ppb-level NO2 detection and visible light illumination enhancement behavior.

A New Fluorenone-based Turn-on Fluorescent Al3+ Ion Sensor

In this paper, we report a turn-on fluorescence sensing of Al3+ ion using a new fluorenone derivative. The imino derivative of 2-amino-9-fluorenone and mercapto-2-butanone is synthesized and characterized using IR, NMR, and mass spectral techniques. The fluorescence of the compound shows a large enhancement at the addition of Al3+ ions, and other metal ions show insignificant changes of the fluorescence. The stoichiometry and the binding constant of the complex are reported. The detection limit of the Al3+ determination by the fluorenone derivative is 5 × 10–8 M. A visible enhancement of color occurs on illumination of the fluorescent compound – Al3+ ion complex.

Visibility enhancement via optimal two-piece gamma tone mapping for optical see-through displays under ambient light

Visibility of the overlaid virtual image is highly sensitive to surrounding illumination in optical see-through (OST) displays. Ambient light can especially deteriorate the visibility of low gray-levels of comparable luminance. Therefore, we first derive a luminance model based on actual measurements under varied ambient light and use it to extract low gray-level regions (LGR), which suffer from severe contrast loss. It was experimentally found that gamma tone mapping is the most appropriate method for LGR contrast enhancement of OST displays. Luminance boosting before gamma tone mapping allows better expression of very low value gray levels in the output AR image. The gamma values and luminance boosting parameter are optimally determined by cost minimization. Visibility enhancement is verified experimentally on a practical setup using a variety of ambient light levels and images.

Enhancement of damage identification in composite structures with self-heating based vibrothermography

The self-heating vibrothermography non-destructive testing method is a promising approach for testing polymeric composite structures with a single-side access or inability of application of external heating sources for thermal excitation. The method is based on excitation of low-frequency mechanical vibrations with multiple resonant frequencies, which allows for local heating of a tested structure, and based on a captured thermal response, identification of structural damage. Although the method is quite sensitive for damage, the resulting damage signatures in thermograms are often blurred or invisible due to the measurement noise and non-uniform temperature evolution on the surface of a tested structure. In this paper, the authors examine various post-processing techniques applied for infrared thermograms in order to enhance damage detectability in polymeric composite structures. Three types of methods were examined: methods based on statistical features, a new method based on trend estimation of the temperature profiles, and a method based on similarity maps. The results of the processing reveal visible enhancement of the damage detectability using the proposed methods, which allow detecting and identifying more damage signatures compared to single raw thermograms.

Underwater polarimetric imaging for visibility enhancement utilizing active unpolarized illumination

Underwater imaging is attractive but challenging. Images could be severely degraded by the particles in turbid water because of backscatter generation and signal light attenuation. In this paper, we focus on the scheme of underwater imaging and study the methods of visibility enhancement of turbid underwater images based on polarimetric imaging utilizing active unpolarized illumination. Compared with traditional polarimetric imaging using linearly polarized illumination, using unpolarized illumination ensures the polarization effect of the signal light could be neglected, no matter the depolarization degree of the object is high or low, which expands the application range of underwater polarimetric imaging and makes the underwater polarimetric imaging scheme more reliable and robust. Experimentally, the visibility and the contrast of underwater images are enhanced effectively. In addition, it is demonstrated that our method is applicable for objects of different materials and different imaging distances in turbid water. The contrast of underwater images could be promoted at least 100%, meaning that this kind of technique can be potentially used in many underwater environments.

A robust framework for visibility enhancement of foggy images

This paper presents a robust framework for visibility enhancement of images degraded by foggy weather conditions. The proposed defogged algorithm is developed by the combining of modified visibility restoration approach and S-shaped transfer function for foggy weather degraded images. The proposed defogged algorithm works in two steps: in first step trilateral filter based visibility restoration algorithm is used for visibility and smoothness of the degraded images. Further in the second step S-shaped transfer function is used for contrast enhancement of the foggy images. The image quality metrics of proposed defogged and other existing visibility restoration algorithms are evaluated in terms of Fog Reduction Factor (FRF), Measure of Enhancement Factor (EMF) and blind parameter (η) on different foggy image databases. We demonstrate the strength of proposed defogged algorithm by estimation the thickness of fog in the input image as well as the output image. Finally, the simulation results and visualisation of defogged images indicate that the proposed defogged algorithm is highly effective and efficient for visibility enhancement of foggy images.

Identification of graphene layers by dielectric grating: giant enhancement of visibility

The layer number of graphene plays a critical role in determining its electronic and optical properties; thus the identification of the layer number of graphene is strongly required in experiments. Here, through rigorous coupled-wave analysis, we propose a one-dimensional dielectric grating structure as a promising platform for enhancing the optical contrast of graphene. It is found that the optical contrast of monolayer (bilayer and trilayer) graphene can surprisingly reach 56% (74% and 82%) at normal incidence in the well-designed dielectric grating structure, whose value is around 12 (7 and 6) times than that of monolayer (bilayer and trilayer) graphene supported by a one-dimensional photonic crystal. Our results expand the horizon of the visibility field and indicate its potential for practical identification of the layer number of two-dimensional layered materials in experiments.

Which Healthy Eating Nudges Work Best? A Meta-Analysis of Field Experiments

We examine the effectiveness in field settings of seven healthy eating nudges, classified according to whether they are 1) cognitively-oriented, such as “descriptive nutritional labeling,” “evaluative nutritional labeling,” or “visibility enhancements”; 2) affectively-oriented, such as “hedonic enhancements or “healthy eating calls”; or 3) behaviorally-oriented, such as “convenience enhancements” or “size enhancements.” Our multivariate three-level meta-analysis of 299 effect sizes, controlling for eating behavior, population, and study characteristics, yields a standardized mean difference (Cohen’s d) of .23 (equivalent to -124 kcal/day). Effect sizes increase as the focus of the nudges shifts from cognition (d=.12, -64 kcal) to affect (d=.24, -129 kcal) to behavior (d=.39, -209 kcal). Interventions are more effective at reducing unhealthy eating than increasing healthy eating or reducing total eating. Effect sizes are larger in the US than in other countries; in restaurants or cafeterias than in grocery stores; and in studies including a control group. Effect sizes are similar for food selection vs. consumption, for children vs. adults, and are independent of study duration. Compared to the typical nudge study (d=.12), one implementing the best nudge scenario can expect a six-fold increase in effectiveness (to d=.74), with half due to switching from cognitively-oriented to behaviorally-oriented nudges.