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Contact lenses are widely used for vision correction and cosmetic purposes. Smart contact lenses offer further opportunities as functionalized non-invasive devices capable of simultaneous vision correction, real-time health monitoring and patient specific drug delivery. Herein, a low-cost vat photopolymerization technique is developed for directly 3D printing functionalized structures on commercially available contact lenses. The process enables controlled deposition of functionalized hydrogels, in customizable patterns, on the commercial contact lens surface with negligible optical losses. Multi-functional contact lenses can also be 3D printed with multiple materials deposited at different regions of the contact lens. Herein, the functionalities of colour blindness correction and real-time UV monitoring are demonstrated, by employing three suitable dyes incorporated into 2-hydroxyethyl methacrylate (HEMA) hydrogel structures printed on contact lenses. The results suggest that 3D printing can pave the way towards simple production of low-cost patient specific smart contact lenses.

Monitoring the solar ultraviolet index (UVI) is of great significance to protect human health. The monitoring of UVI faces several challenges: the accuracy is difficult to control, the complexity of the filter, the increase in volume and price, the decrease in response sensitivity, and the low accuracy of measurement. Considering the limitations and insufficiencies in the current technology, this paper proposes a miniature gallium nitride (GaN)-based erythema response detector. The detector utilizes a double-diode integrated chip for accurate detection of the erythema response, enabling it to closely match the spectral response of the erythema spectrum curve determined by the World Health Organization. This ensures precise correspondence between the output current and ultraviolet index. The measurement error of each UV detector is determined by analyzing eight sets of UV radiation spectra. The experimental findings demonstrate that the proposed detector exhibits a measurement error below 0.4 for each group of UV index measurements. The experimental results show that the measurement accuracy of the detector on the ultraviolet index is at the advanced level compared to the current mainstream commercial ultraviolet detector.

This work concerns the new idea of textile printing with a multi-color system using pastes containing compounds sensitive to ultraviolet (UV) radiation. A screen printing method based on a modified CMYK color system was applied to a cotton woven fabric. Aqueous printing pastes were prepared from thickening and crosslinking agents and UV-sensitive compounds: leuco crystal violet (LCV), leuco malachite green (LMG), and 2,3,5-triphenyltetrazolium chloride (TTC) instead of the system’s standard process colors: cyan, magenta, and yellow. Depending on the number of printed layers and the type of UV radiation (UVA, UVB, and UVC), the modified textile samples change color after irradiation from white to a wide range of colors (from blue, red, and green to purple, brown, and gray). Based on reflectance measurements, the characteristic parameters of the one-, two-, and three-color-printed samples in relation to absorbed dose were determined, e.g., dose sensitivity, linear and dynamic dose response, and threshold dose. This printing method is a new proposal for UV dosimeters and an alternative standard for textile printing. Furthermore, the developed method can be used for the securing, marking, and creative design of textiles and opens up new possibilities for such stimulus-sensitive reactive printing.

The results of the Sun’s UV radiation and stratospheric ozone layer thickness over the region of Novi Sad (Serbia) are reported. Monitoring the UV radiation and stratospheric ozone layer thickness started in 2003 and 2007 respectively. Results recorded during these years have been analyzed. Upon these analyses it can be concluded that during observational period, the significant difference in daily maxima of the UV radiation recordings or ozone seasonal maximal values from year to year, has not been detected. Obtained results are graphically depicted.

To complement innovations at the front- and back-ends of source-separating sanitation systems, this study demonstrates a novel approach for stabilising human urine using sparingly soluble fumaric acid. A reactor was developed to dose fumaric acid passively into freshly excreted urine and was operated to mimic more than 250 typical urination events over 15 days. Fumaric acid at a dose of 5.6 g L -1 effectively maintained urine pH below 4.0, inhibiting enzymatic urea hydrolysis and preventing the precipitation of alkaline earth metals and phosphates, thereby protecting downstream infrastructure from blockages. The stabilised urine retained all its constituents, except for 20% of the sulphate. Novel UV-Vis monitoring techniques were introduced to track fumaric acid depletion (ΔAbs221) and solids settling rate (ΔAbs660), and were demonstrated to be practical surrogates for assessing real-time reactor performance. With an estimated operating cost of less than US$ 5 per person per year, this reactor provides a simple, cost-effective, and scalable solution for stabilising urine in decentralised settings.

The possible use of a simplified UV absorption spectroscopic method for dosimetry of bioactive antirachitic UV radiation has been analyzed. The method is based on the observation of the phototransformation kinetics of the provitamin D3 primary molecule in ethanol (in vitro vitamin D3 synthesis model) by measuring the decrease in the optical density at a fixed wavelength during UV exposure. The method can be used successfully for artificial UV sources with a constant radiation spectrum. However, such a technique turns out to be inapplicable to solar UV dosimetry in view of the variability of the solar UV spectrum that results in a varying rate of formation of irreversible photoproducts.

Disinfection by ultraviolet light (UV) has received wide endorsement as an important contribution to the multiple barrier approach for protection of public health. UV can be used both to disinfect wastewater discharged to the environment, and to disinfect that water when it is picked up again for human consumption. UV readily blocks infectivity by such chlorine-resistant pathogens as Cryptosporidium parvum, Giardia lamblia and Legionella pneumophila. Multiple disinfectant use is now being discussed to broaden the spectrum of pathogens that can be inactivated by using disinfectants in their most strategically advantageous dose and function. Optimizing multiple barrier strategies requires attention to validation of the concepts and technologies involved. UV technology validation ensures that the equipment can deliver the target UV design dose, and that the monitoring/control technology modulates the dose appropriately with changes in water quality or operating conditions. The bioassay approach for UV reactor validation is recommended over analytical and numerical models. Analytical models, which provide an average dose estimate, have been shown to be inadequate. Numerical models, which utilize Computational Fluid Dynamics (CFD) and UV light intensity models to predict reactor performance, can be accurate when used by skilled professionals but require significant validation and/or calibration against bioassay data.

The concern about the role of aerosols as to their effect in the Earth-Atmosphere system requires observation at multiple temporal and spatial scales. The Moderate Resolution Imaging Spectroradiameters (MODIS) is the main aerosol optical depth (AOD) monitoring satellite instrument, and its accuracy and uncertainty need to be validated against ground based measurements routinely. The comparison between two ground AOD measurement programs, the United States Department of Agriculture (USDA) Ultraviolet-B Monitoring and Research Program (UVMRP) and the Aerosol Robotic Network (AERONET) program, confirms the consistency between them. The intercomparison between the MODIS AOD, the AERONET AOD, and the UVMRP AOD suggests that the UVMRP AOD measurements are suited to be an alternative ground-based validation source for satellite AOD products. The experiments show that the spatial-temporal dependency between the MODIS AOD and the UVMRP AOD is positive in the sense that the MODIS AOD compare more favorably with the UVMRP AOD as the spatial and temporal intervals are increased. However, the analysis shows that the optimal spatial interval for all time windows is defined by an angular subtense of around 1° to 1.25°, while the optimal time window is around 423 to 483 minutes at most spatial intervals. The spatial-temporal approach around 1.25° & 423 minutes shows better agreement than the prevalent strategy of 0.25° & 60 minutes found in other similar investigations.

Water quality monitoring is an essential component of water quality management for water utilities for managing the drinking water supply. Online UV-Vis spectrophotometers are becoming popular choices for online water quality monitoring and process control, as they are reagent free, do not require sample pre-treatments and can provide continuous measurements. The advantages of the online UV-Vis sensors are that they can capture events and allow quicker responses to water quality changes compared to conventional water quality monitoring. This review summarizes the applications of online UV-Vis spectrophotometers for drinking water quality management in the last two decades. Water quality measurements can be performed directly using the built-in generic algorithms of the online UV-Vis instruments, including absorbance at 254 nm (UV254), colour, dissolved organic carbon (DOC), total organic carbon (TOC), turbidity and nitrate. To enhance the usability of this technique by providing a higher level of operations intelligence, the UV-Vis spectra combined with chemometrics approach offers simplicity, flexibility and applicability. The use of anomaly detection and an early warning was also discussed for drinking water quality monitoring at the source or in the distribution system. As most of the online UV-Vis instruments studies in the drinking water field were conducted at the laboratory- and pilot-scale, future work is needed for industrial-scale evaluation with ab appropriate validation methodology. Issues and potential solutions associated with online instruments for water quality monitoring have been provided. Current technique development outcomes indicate that future research and development work is needed for the integration of early warnings and real-time water treatment process control systems using the online UV-Vis spectrophotometers as part of the water quality management system.

As the most frequent wound complication, infection has become a major clinical challenge in wound management. To overcome the “Black Box” status of the wound‐healing process, next‐generation wound dressings with the abilities of real‐time monitoring, diagnosis during early stages, and on‐demand therapy has attracted considerable attention. Here, by combining the emerging development of bioelectronics, a smart flexible electronics‐integrated wound dressing with a double‐layer structure, the upper layer of which is polydimethylsiloxane‐encapsulated flexible electronics integrated with a temperature sensor and ultraviolet (UV) light‐emitting diodes, and the lower layer of which is a UV‐responsive antibacterial hydrogel, is designed. This dressing is expected to provide early infection diagnosis via real‐time wound‐temperature monitoring by the integrated sensor and on‐demand infection treatment by the release of antibiotics from the hydrogel by in situ UV irradiation. The integrated system possesses good flexibility, excellent compatibility, and high monitoring sensitivity and durability. Animal experiment results demonstrate that the integrated system is capable of monitoring wound status in real time, detecting bacterial infection and providing effective treatment on the basis of need. This proof‐of‐concept research holds great promise in developing new strategies to significantly improve wound management and other pathological diagnoses and treatments. A smart flexible electronics‐integrated wound dressing is designed for real‐time monitoring and on‐demand therapy of infected wounds. It is demonstrated that the integrated wound dressing can diagnose infection during early stages by real‐time wound‐temperature monitoring and provide antibacterial treatment based on the collected data via Bluetooth to achieve a closed‐loop wound healing system.