UV Imaging Research Articles

The AstroSat UV Deep Field North: The Far- and Near-ultraviolet Photometric Catalog

We present deep UV imaging observations of the Great Observatories Origins Survey Northern (GOODS-N) field with AstroSat/UVIT (AstroSat UV Deep Field north—AUDFn), using one far-UV (FUV) (F154W, 34.0 ks) and two near-UV (NUV) filters (N242W, 19.2 ks; N245M, 15.5 ks). The nature of the UV sky background was explored across the UVIT field, and a global mean and rms were estimated for each filter. We reach 3σ detection limits of m AB ∼ 27.35, 27.28, and 27.02 mag for a point source in the F154W, N242W, and N245M bands respectively. The 50% completeness limits of the FUV and NUV images are m AB = 26.40 and 27.05 mag respectively. We constructed point-spread functions for each band and estimated their FWHM, which were found to be almost the same: 1.″18 in F154W, 1.″11 in N242W, and 1.″24 in N245M. We used SExtractor to separately identify sources in the FUV and NUV filters and produce the UV source catalog of the entire AUDFn field. The source count slope estimated in FUV and NUV is 0.57 dex mag−1 (between 19 and 25 mag) and 0.44 dex mag−1 (between 18 and 25 mag), respectively. The catalog contains 6839 and 16,171 sources (brighter than the 50% completeness limit) in the FUV and NUV, respectively. Our FUV and NUV flux measurements of the identified sources complement existing multiband data in the GOODS-N field, and enable us to probe rest-frame FUV properties of galaxies at redshift z < 1 and search for candidate Lyman continuum leakers at redshift z > 0.97.

Genetic Variants of the Gsr Gene (rs2978663) and the Progression of Osteoporosis.

Osteoporosis, demonstrated as an associated disease with more than 30 gene disorders, is a polygenic disorder, and it's also implicated in bone mineral density (BMD) regulations. Lipid peroxidation and hydrogen peroxide levels significantly increased and vice versa the antioxidant enzymes decreased such as Glutathione S-Reductase GSR was found in female postmenopausal females. This research was done in order to find out the effect of rs2978663 genotypes on the progression of osteoporosis. First, blood samples were used to extract DNA for analysis. Molecular examination was achieved using PCR, RFLP, and UV imaging after electrophoresis in an agarose gel, and these results were analyzed by SPSS (version 23). The genotypes differed in healthy people, and the proportions varied, as they were: the highest percentage was represented by the GA genotype (78%), followed by the AA genotype (16%), and the GG genotype (6%). For case samples, the highest percentage was represented by the GA genotype (51%), followed by the AA genotype (30%), and the GG genotype (19%). There are significant associations between GA genotype and restriction of fragility disease. The risk of having osteoporosis was significantly lower in those with the GA genotype (OR = 0.1946; 95% CI = 0.04-0.95; P = 0.03). The A allele frequency of the GSR gene (rs2978663) did not change significantly between study groups (OR: 0.9965, 95% CI: 0.5547-1.7816, P value: 0.9905). Overall, it is safe to say that GSR-int3 (rs-2678663) was shown to have no association with osteoporosis in this research of Iraqi women. Inherent variation in the GSR gene (rs-2678663) is associated with decreased osteoporosis risk.

Integrated 4H-SiC Photosensors With Active Pixel Sensor-Type Circuits for MGy-Class Radiation Hardened CMOS UV Image Sensor

For radiation-hardened CMOS image sensor (CIS), 4H-SiC photosensors with active pixel sensor (APS)-type circuits were developed and demonstrated. The dark current of 4H-SiC photodiodes was <2 nA/cm2. The spectral sensitivity characteristics were also evaluated in the wavelength from 200 nm to 400 nm. The maximal quantum efficiency was 63% at 270 nm. The photosensors with APS type circuits showed high responses to UV light, demonstrating their operation. High gamma-ray dose experiments were also carried out. The dark current after 2 MGy (SiO2) irradiation was 25 nA/cm2. The photosensors with APS-type were successfully working after 2 MGy exposure.

Integration of filter membrane and Ca2Nb3O10 nanosheets for high performance flexible UV photodetectors

• We first report the integration of filter membrane and Ca 2 Nb 3 O 10 nanosheets UV photodetectors (FM@CNO UV PDs). • The FM@CNO PD shows high responsivity (0.08 AW −1 ), high detectivity (1.1 × 10 12 Jones), high UV/visible rejection ratio (3.86 × 10 3 ) and fast speed (0.12/1.24 ms) under 300 nm light illumination. • The FM@CNO PD exhibits excellent flexibility after many bending cycles. And the FM@CNO array device can be used as a pixel array detector for UV imaging. We report that the integration of filter membrane and Ca 2 Nb 3 O 10 nanosheets (FM@CNO) UV photodetector (UV PD) shows high performance and excellent flexibility. The Ca 2 Nb 3 O 10 nanosheets were prepared by a facile solid-state reaction and liquid exfoliation process. The Ca 2 Nb 3 O 10 nanosheets can be integrated into the pores of a filter membrane via a simple vacuum filtration method. The FM@CNO UV PD shows high performance under 300 nm light illumination at 5 V bias, including high responsivity (0.08 AW −1 ), high detectivity (1.1 × 10 12 Jones), high UV/visible rejection ratio (3.86 × 10 3 ) and fast speed (0.12/1.24 ms). Furthermore, the FM@CNO device exhibits excellent flexibility after many bending cycles. In addition, the FM@CNO array device was used as a pixel array detector for UV imaging. This work provides a novel approach to achieve high performance flexible PDs based on filter membrane and two dimensional materials.

Design of UV Imaging Spectrometer Calibration Structure

Design of UV Imaging Spectrometer Calibration Structure

A rapid and systematic approach for the optimization of radio thin-layer chromatography resolution

Radiopharmaceutical analysis is limited by conventional methods. Radio-HPLC may be inaccurate for some compounds (e.g., 18F-radiopharmaceuticals) due to radionuclide sequester. Radio-TLC is simpler, faster, and detects all species but has limited resolution. Imaging-based readout of TLC plates (e.g., using Cerenkov luminescence imaging) can improve readout resolution, but the underlying chromatographic separation efficiency may be insufficient to resolve chemically similar species such as product and precursor-derived impurities. This study applies a systematic mobile phase optimization method, PRISMA, to improve radio-TLC resolution. The PRISMA method optimizes the mobile phase by selecting the correct solvent, optimizing solvent polarity, and optimizing composition. Without prior knowledge of impurities and by simply observing the separation resolution between a radiopharmaceutical and its nearest radioactive or non-radioactive impurities (observed via UV imaging) for different mobile phases, the PRISMA method enabled the development of high-resolution separation conditions for a wide range of 18F-radiopharmaceuticals ( [18F]PBR-06, [18F]FEPPA, [18F]Fallypride, [18F]FPEB, and [18F]FDOPA). Each optimization required a single batch of crude radiopharmaceutical and a few hours. Interestingly, the optimized TLC method provided greater accuracy (compared to other published TLC methods) in determining the product abundance of one radiopharmaceutical studied in more depth ( [18F]Fallypride) and was capable of resolving a comparable number of species as isocratic radio-HPLC. We used the PRISMA-optimized mobile phase for [18F]FPEB in combination with multi-lane radio-TLC techniques to evaluate reaction performance during high-throughput synthesis optimization of [18F]FPEB. The PRISMA methodology, in combination with high-resolution radio-TLC readout, enables a rapid and systematic approach to achieving high-resolution and accurate analysis of radiopharmaceuticals without the need for radio-HPLC.

Integrated 64 pixel UV image sensor and readout in a silicon carbide CMOS technology

This work demonstrates the first on-chip UV optoelectronic integration in 4H-SiC CMOS, which includes an image sensor with 64 active pixels and a total of 1263 transistors on a 100 mm2 chip. The reported image sensor offers serial digital, analog, and 2-bit ADC outputs and operates at 0.39 Hz with a maximum power consumption of 60 μW, which are significant improvements over previous reports. UV optoelectronics have applications in flame detection, satellites, astronomy, UV photography, and healthcare. The complexity of this optoelectronic system paves the way for new applications such harsh environment microcontrollers.

Enhanced Response Speed in 2D Perovskite Oxides-Based Photodetectors for UV Imaging through Surface/Interface Carrier-Transport Modulation.

The long-time decay process induced by the persistent photoconductivity (PPC) in metal oxides-based photodetectors (PDs) impedes our demands for high-speed photodetectors. 2D perovskite oxides, emerging candidates for future high-performance PDs, also suffer from the PPC effect. Here, by integrating 2D perovskite Sr2Nb3O10 (SNO) nanosheets and nitrogen-doped graphene quantum dots (NGQDs), a unique nanoscale heterojunction is designed to modulate surface/interface carrier transport for enhanced response speed. Notably, the decay time is reduced from hundreds of seconds to a few seconds. The 4%NGQDs-SNO PD exhibits excellent performance with a photocurrent of 0.47 μA, a high on-off ratio of 2.2 × 104, and a fast pulse response speed (τdecay = 67.3 ms), making it promising for UV imaging. The trap-involved decay process plays a dominant role in determining the decay time, resulting in the PPC effect in SNO PD, and the trap states mainly originate from oxygen vacancies and chemisorbed oxygen molecules. A significantly enhanced photoresponse speed in NGQDs-SNO PDs can be ascribed to the modulated surface/interface trap states and the efficient carrier pathway provided by the nanoscale heterojunction. This work provides an effective way to enhance the response speed in 2D perovskite oxides constrained by PPC via surface/interface engineering, promoting their applications in optoelectronics.

The forger's identikit: A multi-technique characterization of Pippo Oriani's fake paintings

This work is part of a multi-disciplinary study aimed at creating the first scientific database to support the future authentication of paintings on the art market. In particular, five fake paintings attributed to the Italian painter Pippo Oriani (1909–1972) have been characterized. Since no scientific literature concerning the material composition used by the artist is available, the five paintings were studied with a multi-technique approach aiming at better understanding the forgery process. The obtained results can be used in the future as a first step to support the authentication of Oriani's artworks on the art market. In particular, it allows to evaluate the consistency of data obtained from future scientific investigations on Oriani's artwork with the forgery process reported in the present database. Non-invasive diagnostic tools, such as UV imaging, IR and IR-false colour photography, XRF, μ-Raman and FTIR spectroscopies have been used to fully characterize the fake paintings. The combination of these techniques led to obtaining useful information on the support preparation method, the pictorial materials, and the execution technique of the artist/forger(s).A wide range of inorganic pigments and organic dyes have been detected, together with the use of oil and wax as binders. The results revealed a strong similarity among the different paintings, thus supporting the idea that the forger(s) knew very well the original Oriani's pictorial technique.The detailed identification of all the materials used in the forgery process for Oriani's fake paintings will help to support the authentication of other ambiguous paintings in future cases.

Smallest Scale Clumpy Star Formation in Stephan’s Quintet Revealed from UV and IR Imaging

The spatial distribution and physical sizes of star-forming clumps at the smallest scales provide valuable information on hierarchical star formation (SF). In this context, we report the sites of ongoing SF at ∼120 pc along the interacting galaxies in Stephan’s Quintet compact group using AstroSat-UVIT and JWST data. Since ultraviolet radiation is a direct tracer of recent SF, we identified star-forming clumps in this compact group from the FUV imaging which we used to guide us to detect star-forming regions on JWST IR images. The FUV imaging reveals star-forming regions within which we detect smaller clumps from the higher spatial resolution images of JWST, likely produced by PAH molecules and dust ionized by FUV emission from young massive stars. This analysis reveals the importance of FUV imaging data in identifying star-forming regions in the highest spatial resolution IR imaging available.

Light-responsive self-strained organic semiconductor for large flexible OFET sensing array

With the wide application of organic semiconductors (OSCs), researchers are now grappling with a new challenge: design and synthesize OSCs materials with specific functions to satisfy the requirements of high-performance semiconductor devices. Strain engineering is an effective method to improve the semiconductor material’s carrier mobility, which is fundamentally originated from the rearrangement of the atomic packing model of materials under mechanic stress. Here, we design and synthesize a new OSC material named AZO-BTBT-8 based on high-mobility benzo[b]benzo[4,5]thieno[2,3-d]thiophene (BTBT) as the semiconductor backbone. Octane is employed to increase molecular flexibility and solubility, and azobenzene at the other end of the BTBT backbone provides photoisomerization properties and structural balance. Notably, the AZO-BTBT-8 photoisomerization leads to lattice strain in thin-film devices, where exceptional device performance enhancement is realized. On this basis, a large-scale flexible organic field-effect transistor (OFET) device array is fabricated and realizes high-resolution UV imaging with reversible light response.

Centimeter‐Scale Growth of Unidirectional CsCu2I3 Wire Arrays for High Performance UV Photodetectors

AbstractLead‐free CsCu2I3 has attracted tremendous research interests for photonics and photoelectronics due to their nontoxicity, unique electronic structure, and excellent stability. However, it is still challenging to achieve large‐scale ordered arrays of CsCu2I3 micro/nanowires, which limits their functional applications in integrated optoelectronic devices. Herein, unidirectional CsCu2I3 wire arrays are achieved in centimeter scale through a modified microchannel‐assisted spatial confinement strategy, which can confine the precursor solution into the pre‐fabricated microchannel arrays in large area and control its evaporation. The microstructure characterizations reveal that the orthorhombic CsCu2I3 wires are grown along the c‐axis with high crystallinity. The control experiments and theoretical studies indicate that the initial CsCu2I3 nucleation at the front of the solution in the channels and the stable solute supply maintained by the movement of the coverslip determine the growth of the wires. The photodetectors based on the CsCu2I3 wires show a high responsivity (80 mA W−1 at 365 nm; 1.29 A W−1 at 330 nm) and fast response speed (trise/tdecay = 640 µs/7.1 ms). Furthermore, these CsCu2I3 wire arrays exhibit great potential in future flexible electronic and UV imaging applications. This work opens a new way to grow well‐aligned copper‐based halides nano/microwire arrays for the integrated optoelectronics applications.

Self-powered UV photodetectors and imaging arrays based on NiO/IGZO heterojunctions fabricated at room temperature.

Self-powered UV photodetectors and imaging arrays based on p-type NiO/n-type InGaZnO (IGZO) heterojunctions are fabricated at room temperature by using ratio-frequency magnetron sputtering. The p-n heterojunction exhibits typical rectifying characteristics with a rectification ratio of 7.4×104 at a ±4 V applied bias. A high photo-responsivity of 28.8 mA/W is observed under zero bias at a wavelength of 365 nm. The photodetector possesses a fast response time of 15 ms which is among the best in reported oxide-based p-n junction-based UV photodetectors. Finally, recognition of an "H" pattern is demonstrated by a 10×10 photodetector array at zero bias. The results indicate that the NiO/IGZO based photodetectors may have a great potential in constructing large-scale self-powered UV imaging systems.

High responsivity and flexible deep-UV phototransistor based on Ta-doped β-Ga2O3

Deep-ultraviolet (DUV) phototransistors have shown great potential applications in UV imaging, artificial intelligence, and wearable optoelectronics. Among a large number of wide bandgap semiconductors, the quasi-two-dimensional β-Ga2O3 is considered as an ideal candidate for DUV photodetector applications. Herein, we report a high responsivity (R) and fully flexible Ta-doped β-Ga2O3 DUV phototransistor which exhibits outstanding optoelectrical properties with a high R of 1.32 × 106 A/W, a large detectivity of 5.68 × 1014 Jones, a great photo-to-dark current ratio of 1.10 × 1010%, a high external quantum efficiency of 6.60 × 108%, and an ultra-fast response time of ~3.50 ms. Besides, the flexible Ta-doped β-Ga2O3 device also displays high reliability and mechanical flexibility that can sustain well after over 1 × 104 bending cycles. Moreover, high-contrast imaging of UV light was obtained on the flexible DUV detector arrays, which can be efficiently trained and recognized by an artificial neural network. Our findings offer a perspective to develop wearable optoelectronics and UV imaging based on high-performance flexible β-Ga2O3 DUV phototransistors, providing an inspiration for the future work in artificial intelligence and bionic robot fields.

Investigation of diclofenac release and dynamic structural behavior of non-lamellar liquid crystal formulations during in situ formation by UV–Vis imaging and SAXS

In situ formation of high viscous inverse lyotropic non-lamellar liquid crystalline phases is a promising approach for sustained drug delivery in the joint. The in situ forming process on exposure of two diclofenac-loaded preformulations to aqueous media was characterized with respect to depot size and shape, initial release and structural transitions using UV–Vis imaging and spatially and time-resolved synchrotron small-angle X-ray scattering (SAXS). The preformulations consisted of 10 % (w/w) ethanol, 10 % (w/w) water and a binary lipid mixture of glycerol monooleate (GMO):1,2-dioleoyl-sn-glycero-3-phospho-rac-(1-glycerol) (DOPG) or GMO:medium chain triglycerides (MCT). Upon injection of preformulations into an employed injection-cell containing excess of bio-relevant medium, rapid generation of liquid crystalline depots was observed. UV–Vis images and constructed 2D SAXS maps of the injection-cell showed depots with different shapes and sizes, and features with high nanostructural heterogeneity. More extensive swelling of the GMO:DOPG-based preformulation was observed compared to the GMO:MCT-based preformulation. The UV image analysis found that a higher amount of diclofenac was released in the image area after 20 h from the GMO:MCT depot compared to the GMO:DOPG depot. The injection-cell setup employing UV–Vis imaging and synchrotron SAXS constitutes an attractive approach for evaluating the in situ forming processes of liquid crystalline depots.

Low-Temperature Vapor-Phase Anion-Exchange Strategy for Wide-Bandgap Double-Perovskite Cs2AgBiCl6 Films toward Weak Ultraviolet Light Imaging.

Low-temperature synthesis of high-quality, high-stability, wide-bandgap perovskite films by solution methods is still challenging. Herein, large-scale wide-bandgap Cs2AgBiCl6 (CABC) double perovskite films are synthesized by a vapor-phase anion-exchange strategy. By dedicatedly designing an ultrathin TiO2 modification layer between the substrate and double perovskites, high-quality heterojunctions with matched energy band alignment are formed, contributing to a remarkably enhanced ON/OFF ratio of 2.4 × 104 (86 times) and a responsivity of 16 mA W-1 (12 times). Additionally, the ultraviolet photodetectors (UV PDs) exhibit an excellent UV detection limit of 1.18 μW cm-2 (20 nW), a broad linear dynamic range of 146 dB, and a high specific detectivity of 2.06 × 1011 Jones, as well as long-term stability. Finally, we further demonstrate a weak UV imaging system using CABC UV PDs as imaging sensors. The system is capable of imaging weak UV signals as low as 2.94 μW cm-2 (50 nW). Our results provide a feasible approach for low-temperature fabrication of wide-bandgap perovskite UV PDs and explore the promising application for weak UV detection and imaging.

Impact of UV-based self-assessed photoaging on sun protection intentions: validation based on trail runners and their companions

Appearance-based interventions emphasize how UV exposure contributes to the premature aging of skin. The current study was aimed at evaluating the impact of self-assessed skin damage based on UV imaging on the intention to modify photoprotection habits. A prospective observational study was performed. Mountain runners and their companions participating in the GAP Trail were invited to participate. Participants were asked to complete a validated questionnaire about sun exposure habits, and were invited to see an image of their faces using SkinScope. In total, 116 people participated in the study. The degree of photoaging established by the dermatologist using the Glogau score significantly correlated with that based on self-assessment by the participants using the UV system (p < 0.001). Almost all UV fluorescence image colours significantly correlated with the grade of photoaging. After seeing their image with the UV system, 65.5% stated that they would improve photoprotection measures. UV imaging is a reliable way to self-evaluate photoaging and may reinforce photoprotection habits.

Advances in Photoelectric Detection Units for Imaging Based on Perovskite Materials

AbstractAs an excellent representative of a new generation of semiconductor materials, perovskite materials are sweeping the whole photoelectric field like a storm (such as photovoltaic, electroluminescence, photoelectric detection and imaging, memristor, thermoelectricity, and other fields). In the field of photoelectric detection and imaging, perovskite materials show unique and excellent application potential of photoelectric detection and imaging. This paper overviews the recent advances of photoelectric detection units (PDUs) based on perovskite materials for imaging. First, the key characteristics and indexes of perovskite materials and PDUs are introduced. Then, the PDUs of conventional imaging in UV–vis–NIR band are introduced from organic–inorganic hybrid and all‐inorganic perovskite materials respectively. Then, the research of perovskite materials in X‐ray image detection and biological imaging is summarized. Finally, the application prospects of perovskite materials in PDUs imaging is discussed.

Methodological Considerations in Development of UV Imaging for Characterization of Intra-Tumoral Injectables Using cAMP as a Model Substance.

A UV imaging release-testing setup comprising an agarose gel as a model for tumorous tissue was developed. The setup was optimized with respect to agarose concentration (0.5% (w/v)), injection procedure, and temperature control. A repeatable injection protocol was established allowing injection into cavities with well-defined geometries. The effective resolution of the SDi2 UV imaging system is 30–80 µm. The linear range of the imaging system is less than that of typical spectrophotometers. Consequently, non-linear cAMP calibration curves were applied for quantification at 280 nm. The degree of deviation from Beer’s law was affected by the background absorbance of the gel matrix. MATLAB scripts provided hitherto missing flexibility with respect to definition and utilization of quantification zones, contour lines facilitating visualization, and automated, continuous data analysis. Various release patterns were observed for an aqueous solution and in situ forming Pluronic F127 hydrogel and PLGA implants containing cAMP as a model for STING ligands. The UV imaging and MATLAB data analysis setup constituted a significant technical development in terms of visualizing behavior for injectable formulations intended for intra-tumoral delivery, and, thereby, a step toward establishment of a bio-predictive in vitro release-testing method.

Investigation of Lysozyme Diffusion in Agarose Hydrogels Employing a Microfluidics-Based UV Imaging Approach.

Hydrogels are polymer-based materials with a high water content. Due to their biocompatible and cell-friendly nature, they play a major role in a variety of biotechnological applications. For many of these applications, diffusibility is an essential property influencing the choice of material. We present an approach to estimate diffusion coefficients in hydrogels based on absorbance measurements of a UV area imaging system. A microfluidic chip with a y-junction was employed to generate a fluid-hydrogel interface and the diffusion of lysozyme from the fluid into the hydrogel phase was monitored. Employing automated image and data processing, analyte concentration profiles were generated from the absorbance measurements and fits with an analytical solution of Fick’s second law of diffusion were applied to estimate diffusion coefficients. As a case study, the diffusion of lysozyme in hydrogels made from different concentrations (0.5–1.5% (w/w)) of an unmodified and a low-melt agarose was investigated. The estimated diffusion coefficients for lysozyme were between 0.80 ± 0.04×10−10 m2 s−1 for 1.5% (w/w) low-melt agarose and 1.14 ± 0.02×10−10 m2 s−1 for 0.5% (w/w) unmodified agarose. The method proved sensitive enough to resolve significant differences between the diffusion coefficients in different concentrations and types of agarose. The microfluidic approach offers low consumption of analyte and hydrogel and requires only relatively simple instrumentation.