Different Wavelengths Of Light Research Articles

Orthogonal Photoswitching in a Porous Organic Framework.

The development of photoresponsive systems with non-invasive orthogonal control by distinct wavelengths of light is still in its infancy. In particular, the design of photochemically triggered-orthogonal systems integrated into solid materials that enable multiple dynamic control over their properties remains a longstanding challenge. Here, we report the orthogonal and reversible control of two types of photoswitches in an integrated solid porous framework, that is, visible-light responsive o-fluoroazobenzene and nitro-spiropyran motifs. The properties of the constructed material can be selectively controlled by different wavelengths of light thus generating four distinct states providing a basis for dynamic multifunctional materials. Solid-state NMR spectroscopy demonstrated the selective transformation of the azobenzene switch in the bulk, which in turn modulates N2 and CO2 adsorption.

Orthogonal Photoswitching in a Porous Organic Framework

AbstractThe development of photoresponsive systems with non‐invasive orthogonal control by distinct wavelengths of light is still in its infancy. In particular, the design of photochemically triggered‐orthogonal systems integrated into solid materials that enable multiple dynamic control over their properties remains a longstanding challenge. Here, we report the orthogonal and reversible control of two types of photoswitches in an integrated solid porous framework, that is, visible‐light responsive o‐fluoroazobenzene and nitro‐spiropyran motifs. The properties of the constructed material can be selectively controlled by different wavelengths of light thus generating four distinct states providing a basis for dynamic multifunctional materials. Solid‐state NMR spectroscopy demonstrated the selective transformation of the azobenzene switch in the bulk, which in turn modulates N2 and CO2 adsorption.

Reciprocally tailored transparent artificial media for frequency and direction dependent light trapping

We propose a quasiperiodic leveled-wave structure whose reciprocal space is represented by spherical belt sections, designed to achieve scattering only for the defined wavelength and direction of incident light. At the same time light is scattered only towards directions of k-vectors for which the waves are trapped by total internal reflection in the structured slab. The trapped light is only weakly scattered and thus spends a long time inside the slab and is attenuated by weak absorption in the slab. The incident light of other direction and/or wavelength is transmitted through the slab almost undisturbed. We quantitatively estimated the scattering mean free paths for incident and trapped light from the first-order Born approximation and develop an analytical model which predicts the absorption for a given slab thickness, refractive index contrast and spherical belt parameters. Reducing the refractive index contrast and thickness of the belt, the selectivity can be increased and the absorption contrast for incident light of different wavelengths can reach 70%. We present numerical simulations with absorption contrast of 63% for refractive index contrast of 0.1, which is in good agreement with our analytical model.

Compact Mid‐Infrared Spectrometer Using Continuously Variable Infrared Filter and Microbolometer Array for Simple and Fast Measurement of Molecular Mid‐IR Spectra

AbstractThe mid‐infrared (mid‐IR) region is attractive for spectroscopy because this range has molecular fingerprint information. Existing FTIR‐based systems are limited by their complex optical systems, highlighting the ongoing necessity to advance miniaturization and simplify these systems. Here, a compact mid‐IR spectroscopy is introduced in the mid‐IR range, utilizing a continuously variable mid‐IR filter. This filter is made from Germanium (Ge) and BaF2 and is produced using physical vapor deposition. Continuously varying wavelengths of mid‐IR light are transmitted from different areas of the filter. These different wavelengths of light enter each pixel of the microbolometer array. Calibration is conducted using a sample material to match each pixel of the microbolometer array to its corresponding wavelength. Additionally, a deconvolution algorithm is applied to sharpen the acquired spectrum. This results in acquisition of high signal‐to‐noise ratio mid‐IR spectra in the LWIR region. Using this technology, mid‐IR spectroscopy for several types of samples like polymer film, and gas molecules is possible. In addition, by adopting total internal reflection, it is possible to measure non‐uniform thickness samples, such as liquid droplets.

Multivariate Analysis of Light-Activated SMOX Gas Sensors.

Chemoresistive gas sensors made from SnO2, ZnO, WO3, and In2O3 have been prepared by flame spray pyrolysis. The sensors' response to CO and NO2 in darkness and under illumination at different wavelengths, using commercially available LEDs, was investigated. Operation at room temperature turned out to be impractical due to the condensation of water inside the porous sensing layers and the irreversible changes it caused. Accordingly, for sensors operated at 70 °C, a characterization procedure was developed and proven to deliver consistent data. The resulting data set was so complex that usual univariate data analysis was intricate and, consequently, was investigated by correlation and principal component analysis. The results show that light of different wavelengths affects not only the resistance of each material, both under exposure to the target gases in humidity and in its absence, but also the sensor response to humidity and the target gases. It was found that each of the materials behaves differently under light exposure, and it was possible to identify conditions that need further investigations.

Underwater image enhancement using multi-task fusion.

Underwater images are often scattered due to suspended particles in the water, resulting in light scattering and blocking and reduced visibility and contrast. Color shifts and distortions are also caused by the absorption of different wavelengths of light in the water. This series of problems will make the underwater image quality greatly impaired, resulting in some advanced visual work can not be carried out underwater. In order to solve these problems, this paper proposes an underwater image enhancement method based on multi-task fusion, called MTF. Specifically, we first use linear constraints on the input image to achieve color correction based on the gray world assumption. The corrected image is then used to achieve visibility enhancement using an improved type-II fuzzy set-based algorithm, while the image is contrast enhanced using standard normal distribution probability density function and softplus function. However, in order to obtain more qualitative results, we propose multi-task fusion, in which we solve for similarity, then we obtain fusion weights that guarantee the best features of the image as much as possible from the obtained similarity, and finally we fuse the image with the weights to obtain the output image, and we find that multi-task fusion has excellent image enhancement and restoration capabilities, and also produces visually pleasing results. Extensive qualitative and quantitative evaluations show that MTF method achieves optimal results compared to ten state-of-the-art underwater enhancement algorithms on 2 datasets. Moreover, the method can achieve better results in application tests such as target detection and edge detection.

Molecular Motor-Driven Light-Controlled Logic-Gated K+ Channel for Cancer Cell Apoptosis.

Developing artificial ion transport systems, which process complicated information and step-wise regulate properties, is essential for deeply comprehending the subtle dynamic behaviors of natural channel proteins (NCPs). Here a photo-controlled logic-gated K+ channel based on single-chain random heteropolymers containing molecular motors, exhibiting multi-core processor-like properties to step-wise control ion transport is reported. Designed with oxygen, deoxygenation, and different wavelengths of light as input signals, complicated logical circuits comprising "YES", "AND", "OR" and "NOT" gate components are established. Implementing these logical circuits with K+ transport efficiencies as output signals, multiple state transitions including "ON", "Partially OFF" and "Totally OFF" in liposomes and cancer cells are realized, further causing step-wise anticancer treatments. Dramatic K+ efflux in the "ON" state (decrease by 50% within 7min) significantly induces cancer cell apoptosis. This integrated logic-gated strategy will be expanded toward understanding the delicate mechanism underlying NCPs and treating cancer or other diseases is expected.

Development of an optical sensing system for the detection of lubricity conditions on the rail gage face

ABSTRACT A novel optical sensing device that uses laser-induced fluorescence to detect the lubricity condition of the rail gage-face is evaluated. By analysing the fluorescence properties of eight commonly used gage-face greases used by the U.S. Class I railroads, we observed that the emitted fluorescence of the grease when exposed to ultraviolet (UV) light of different wavelengths can be used for detecting their presence. This observation is used to develop a non-contacting optical sensing device that uses two 405 nm lasers, a fluorescence detector, and a fluorescent bandpass filter, which are optimized for the fluorescence spectra of the greases. Two sensing devices are installed on a robotic rail cart, one on each side, to simultaneously detect the lubricity conditions on the rails over extended distances. After extensive evaluations using both laboratory and field testing, it is confirmed that the optical sensing system can accurately detect the presence of the gage-face grease through the fluorescence intensity or intensity variance, even when there are small quantities of grease in relatively thin layers. Furthermore, the test results indicate a high level of repeatability and efficiency in detecting the spatial distribution of grease along the rail.

Multi-depth focused laser differential interferometer based on chromatic aberration.

A modified version of focused laser differential interferometry (FLDI) is demonstrated with adjacent beam pairs distributed along the optical axis. This feature is accomplished using two different wavelengths of light in the interferometer and accounting for the chromatic aberration of the lenses in the optical setup. It is demonstrated that ray trace calculations can be modified to predict the focal points of each of the two different colored beams, and experiments using a tube jet and a laser-induced blast wave show the instrument still has the expected features of an FLDI as well as continued capability for velocimetry. This modification is in effort to allow FLDI to be used for the analysis of three-dimensional flows, especially if combined with other multi-point variations and targeting high-frequency flow content.

Real-time detection of aflatoxin-contaminated dried figs using lights of different wavelengths by feature extraction with deep learning

Real-time detection of aflatoxin-contaminated dried figs using lights of different wavelengths by feature extraction with deep learning

Long-term, high-resolution in vivo calcium imaging in pigeons

Invivo 2-photon calcium imaging has led to fundamental advances in our understanding of sensory circuits in mammalian species. In contrast, few studies have exploited this methodology in birds, with investigators primarily relying on histological and electrophysiological techniques. Here, we report the development of invivo 2-photon calcium imaging in awake pigeons. We show that the genetically encoded calcium indicator GCaMP6s, delivered by the adeno-associated virus rAAV2/7, allows high-quality, stable, and long-term imaging of neuronal populations at single-cell and single-dendrite resolution in the pigeon forebrain. We demonstrate the utility of our setup by investigating the processing of colors in the visual Wulst, the avian homolog of the visual cortex. We report that neurons in the Wulst are color selective and display diverse response profiles to light of different wavelengths. This technology provides a powerful tool to decipher the operating principles that underlie sensory encoding in birds.

Biomimetic construction of smart nanochannels in covalent organic framework membranes for efficient ion separation

Smart nanochannels can regulate ion transport behavior by external stimulus and display precise ion selectivity in biological membrane systems, but constructing artificial membranes with responsive and tunable channel remains a severe challenge. Herein, smart covalent organic framework (COF) membranes decorated with photo-responsive azobenzene derivatives (COF-Azo) were fabricated by a biomimetic nanochannel modulation (BNM) strategy, endowing membranes with charged and switchable sub-nanochannels. Under different wavelength of light, the smart COF-Azo membranes simultaneously exhibited outstanding mono/monovalent and mono/divalent ion selectivity (K+/Li+ ideal selectivity of 17.9 and Li+/Mg2+ ideal selectivity of 24.9) via closing and opening channels. The conversion of effective pore size at angstrom level is realized by photoisomerization of azobenzene. After several photoswitch cycles, the smart membranes still maintained K+/Li+ selectivity of 6.1 and Li+/Mg2+ selectivity of 20.7 in mixed salt solution, exhibiting great potentials in lithium extraction. This work may blaze a trail in constructing photo-responsive nanochannel membranes for energy-efficient ion separation.

Multifunctional Nanoplatform for Single NIR Laser-Regulated Efficient PDT/PTT/Chemotherapy.

The combination of phototherapy and chemotherapy with superior advantages is a promising strategy for cancer therapy. However, combination therapy is generally regulated by two different wavelengths of light or other stimuli, which results in complex operations and inevitable systemic side effects, even affecting therapeutic efficacy. Herein, we design a signal NIR light-regulated nanoplatform via the self-assembly process of reactive oxygen species (ROS)-sensitive prodrug (DTD), human serum albumin (HSA), and IR780 for combined photothermal/photodynamic therapy and chemotherapy. Upon 808 nm laser irradiation, IR780 in nanoparticles generates abundant ROS and a significant photothermal effect to achieve photothermal/photodynamic therapy. Meanwhile, the generating ROS further cleans up the thioketal link to release DOX for chemotherapy. Hence, signal NIR light can effectively control the process of combination therapy. In vivo and in vitro experiment results demonstrate that the multifunctional nanoparticles exhibit excellent antitumor efficacy via the combination of phototherapy and chemotherapy controlled by a signal NIR laser. Overall, the signal NIR light-regulated nanoparticles with combination therapy performance provide a versatile platform for enhancing antitumor efficacy.

Interactive Effects of Blue Light and Water Turbulence on the Growth of the Green Macroalga Ulva australis (Chlorophyta).

Macroalgal growth and yield are key to sustainable aquaculture. Although light and water turbulence are two important factors that affect algal productivity, research on their interaction is limited. Therefore, in this study, we investigated the effects of different wavelengths of light and the presence or absence of water turbulence on the growth of the green macroalga Ulva australis. Water turbulence was found to enhance the growth of U. australis irrespective of photosynthetic performance, but only in blue light cultures. The quantum dose of blue light required to induce 50% growth promotion was 1.02 mol m-2, which is comparable to the reported values for cryptochrome-mediated effects in other macroalgae. The combined effect of blue light and water turbulence led to the accumulation of photosynthesis-related proteins that support plastid differentiation and facilitate efficient photosynthesis and growth. Our findings thus highlight the potential of harnessing blue light and water turbulence to maximise macroalgal cultivation for sustainable and profitable algal aquaculture.

Identifying the wavelength that generates the most voltage and current in a solar panel

Solar power is a potential solution for addressing climate change. There is limited research on how different wavelengths of light affect solar cells, and researchers have come to conflicting conclusions. Determining the most efficient wavelength of light would allow us to improve solar panel efficiency and make panels more cost-effective and desirable for adoption by the general public. A color filter is relatively inexpensive, and it can enhance the efficiency of a solar panel. Ultimately, it can help save the environment by (1) making solar panels as efficient as possible, (2) making society less dependent on fossil fuels, and (3) speeding up adoption of solar power. Therefore, this study focused on determining which wavelength of light generates the most voltage and current from a solar panel as measured by a Raspberry Pi coded to function as a multimeter. We measured the voltage and current that the solar panel generated in the absence or presence of different filters, which produce different wavelengths of light. Learning which, if any, color filter generates the most voltage and current can improve and promote solar power use. We determined that the yellow filter produced the greatest voltage and current compared to using a solar panel without a filter or a red, orange, green, blue, and purple color filter. Our results suggest that yellow color filters can enhance the voltage and current capabilities of solar panels. The findings offer a relatively low-cost solution to increasing the efficiency of solar panels.

Optic treatments to myopia management

Myopia has become a challenge for public health in the last decades due to the increase in its prevalence and its effect on the axial growth of the eye. The main concern about the myopia progression in the child population is due to the appearance of secondary pathologies of myopia in the adulthood. They have been developed various optical and pharmacological treatments in the last years to try to minimize the axial growth of the eye and therefore to try to prevent, to delay or to minimize the impact of pathologies associated to myopia that could provoke loss of vision.Within the optical treatments to control the axial growth progression, orthokeratology contact lenses, peripheral defocus soft contact lenses and ophthalmic lenses have been described. Other optical devices are also being developed that through the management of different wavelengths of light will serve as adjuvants for the myopia control.That presentation will try to show the scientific evidence on the efficacy and safety of the use of these treatments as well as to discuss the possible mechanisms of action to minimize the axial growth progression.

Reversible change of luster color from pale yellow to wine red in microcrystalline film by photochromic diarylethene having a naphthyl group

Microcrystalline film prepared by photochromic diarylethene having a naphthyl group can reversibly change its luster color from pale yellow to wine red upon irradiation with light of different wavelengths.

Generic arrays of surface-positioned and shallow-buried gold multi-shapes as reference samples to benchmark near-field microscopes. Part 1: Applications in s-SNOM depth imaging

A wide palette of nanoscale imaging techniques operating in the near-field regime has been reported to date, enabling an important number of scientific breakthroughs. While the tuning and benchmarking of near-field microscopes represent a very important step for optimizing the outputs of the imaging sessions, no generally acknowledged standards exist yet in terms of calibration of near-field microscopes, which would play an important role in fully exploiting the potential of these instruments. With this work, we aim to contribute to filling in this gap, by introducing a prototypical sample, that holds potential for becoming a benchmark with respect to comparing the performances of diverse near-field measurement techniques, including traditional, aperture based, scanning near field microscopy (SNOM), or apertureless variants, such as scattering-type scanning nearfield optical microscopy (s-SNOM). The proposed samples have been thoroughly simulated, and an easy fabrication procedure is presented and demonstrated. In this latter context, Au-SiO2 samples sharing different configurations, in terms of geometry, number and depth of contrast yielding layers, enabling both surface and sub-surface nanoscopy measurements, were designed and fabricated. We argue that the proposed prototypical samples can be highly useful for benchmarking the outputs of various near-field microscopy techniques, as they facilitate a broad range of tests, relevant for comparing the performances and accuracy of many diverse investigation methods. We also introduce a methodology for numerically simulating the samples and their near-field after illuminating them with light of different wavelengths, as well as their simple process flow. This methodology can considerably augment their future use as a prototypical sample for the evaluation and calibration of current and next generation near-field nanoscopy techniques. Experimental evidence on the usefulness of these samples as s-SNOM testing and benchmarking tools is provided in the context of differentiation of surface and sub-surface structures, and influence of tip-sample distance on attainable amplitude and phase signals. We consider these efforts to represent an important, required step, in advancing the near-field imaging field, with important potential to augment the outputs of current near-field imaging systems, and to facilitate the development and benchmarking of next generation of near-field instrumentation.

Radionuclide Reporter Imaging to Visualize Tumor Hypoxia Ex Vivo and In Vivo.

In vitro studies using cell culture, including three-dimensional cultures without the involvement of tumor vessels, have limitations in simulating complex intratumoral hypoxic conditions in live subjects. To generate experimental hypoxic conditions closer to those observed in humans in clinical settings, in vivo studies are necessary. In addition, visible light generated via bioluminescence and fluorescence is generally unsuitable for in vivo experiments because of low tissue penetration. Furthermore, near-infrared light (NIR), which has the highest tissue penetration among lights of different wavelengths, cannot be assessed precisely in vivo because of the difficulty in correcting tissue absorption and scatter. For in vivo quantitative analyses, imaging modalities that use high tissue-penetrating signals, such as computed tomography (CT) using X-rays, radionuclide imaging using γ-rays, and magnetic resonance imaging (MRI) using electromagnetic waves, are ideal.Therefore, as an advanced protocol for this research purpose, we provide ex vivo and in vivo methods to investigate the genetic response of multiple copies of hypoxia response elements (HREs) to tumor hypoxia in terms of intensity and intratumoral distribution using a human sodium/iodide symporter (hNIS) reporter gene and radionuclide reporter probes (radioiodine and its chemical analog Tc-99m) based on our previous research. This protocol includes cloning an hNIS reporter construct with multiple copies of HREs, establishing stable cell lines of the reporter construct, preparing a mouse subcutaneous xenograft model, and evaluating the genetic response of multiple HREs to tumor hypoxia using digital autoradiography (ARG) ex vivo and using single-photon emission computed tomography (SPECT) or positron emission tomography (PET) in vivo.

An Au25 nanocluster/MoS2 vdWaals heterojunction phototransistor for chromamorphic visual-afterimage emulation.

Color vision relies on three cone photoreceptors that are sensitive to different wavelengths of light. The interaction of three incident light wavelengths over time creates a fascinating color coupling perception, termed chromamorphic computing. However, the realization of this fascinating characteristic in semiconductor devices remains a great challenge. Herein, a mixed-dimensional optoelectronic transistor based on a novel metal nanocluster Au25(SC12H25)18 and two-dimensional MoS2 van der Waals (vdWaals) heterojunction is proposed for chromamorphic visual-afterimage emulation with red-green-blue three-color spatiotemporal coupling perception. This distinguished molecular-like electronic level of Au25 nanoclusters allows the transistor to have visible light-sensitive properties, endowing it with the ability to perceive color information. Moreover, the chromamorphic functions are realized using a color spatiotemporal coupling approach. By utilizing the photogating effect of light stimulus, the device exhibits visual experience-dependent plasticity in accordance with the Bienenstock-Cooper-Munro (BCM) learning rule. Most importantly, for the first time, intriguing visual afterimages could be implemented using a color sensitization approach based on a close relationship between visual persistence and negative afterimages. These results represent an important step towards a new generation of intelligent visual color perception systems for human-computer interaction, bionic robots, etc.