Search Results (9)

Photoelectrochromic devices, which combine light-induced color change with energy-efficient optical modulation, have attracted significant attention for applications such as smart windows, displays, and optical sensors. However, achieving high optical modulation, fast switching speeds, and long-term stability remains a major challenge. In this study, we explore the structural and photoelectrochromic enhancements in tungsten oxide (WO₃) films achieved by doping with molybdenum disulfide quantum dots (MoS₂ QDs) and grapheneoxide–molybdenum disulfide quantum dots (GO–MoS₂ QDs) for advanced photoelectrochromic devices. X-ray diffraction (XRD) analysis revealed that doping with MoS₂ QDs and GO–MoS₂ QDs leads to a reduction in the crystallite size of WO₃, as evidenced by the broadening and decrease in peak intensity. Transmission Electron Microscopy (TEM) confirmed the presence of characteristic lattice fringes with interplanar spacings of 0.36 nm, 0.43 nm, and 0.34 nm, corresponding to the planes of WO₃, MoS₂, and graphene. Energy-Dispersive X-ray Spectroscopy (EDS) mapping indicated a uniform distribution of tungsten, oxygen, molybdenum, and sulfur, suggesting homogeneous doping throughout the WO₃ matrix. Scanning Electron Microscopy (SEM) analysis showed a significant decrease in film thickness from 724.3 nm for pure WO₃ to 578.8 nm for MoS₂ QD-doped WO₃ and 588.7 nm for GO–MoS₂ QD-doped WO₃, attributed to enhanced packing density and structural reorganization. These structural modifications are expected to enhance photoelectrochromic performance by improving charge transport and mechanical stability. Photoelectrochromic performance analysis showed a significant improvement in optical modulation upon incorporating MoS₂ QDs and GO–MoS₂ QDs into the WO₃ matrix, achieving a coloration depth of 56.69% and 70.28% at 630 nm, respectively, within 10 min of 1.5 AM sun illumination, with more than 90% recovery of the initial transmittance within 7 h in dark conditions. Additionally, device stability was improved by the incorporation of GO–MoS₂ QDs into the WO₃ layer. The findings demonstrate that incorporating MoS₂ QDs and GO–MoS₂ QDs effectively modifies the structural properties of WO₃, making it a promising material for high-performance photoelectrochromic applications. Full article

Ascorbic acid plays an important role in the synthesis and metabolism of the human body. However, it cannot be synthesized by the human body and needs to be supplemented from exogenous food intake. Ascorbic acid is easily degraded during storage and heating, often causing its content in food to change. It is important to develop a sensitive and accurate photoelectrochemistry (PEC) biosensor for detecting ascorbic acid. The shortage of PEC materials with long illumination wavelengths and low bias voltages impedes the development of ascorbic acid biosensors. Herein, a 3,4,9,10-perylenetetracarboxylic dianhydride (PDA) self-assembly rod material was firstly reported to show significant photocurrent increases to ascorbic acid at 630 nm illumination and 0 V vs. Ag/AgCl. Moreover, the PDA self-assembly rod material was used as a PEC platform to detect ascorbic acid. This self-powered PEC biosensor exhibited a linear response for ascorbic acid from 5 μM·L⁻¹ to 400 μM·L⁻¹; the limit of detection was calculated to be 4.1 μM·L⁻¹. Compared with other ascorbic acid biosensors, the proposed self-powered PEC biosensor shows a relatively wide linear range. In addition, the proposed self-powered PEC biosensor exhibits good practicability in beverage samples. Full article

This study examined the effects of low-temperature heat treatment on the characteristics of the rubies from Mong Hsu, Myanmar. Five ruby samples were heated to 400, 600, 900 and 1200 °C for different durations, respectively. Before and after each heating step, a visual examination was conducted with a gem microscope under different illumination conditions. Various spectral analyses such as UV-Vis, FTIR, Raman and PL were also used to examine the effect of heating on the ruby samples. The low-temperature heat treatment enhanced the ruby samples by causing the dark blue core to partially or completely fade away. It then increased the overall light transmittance and enhanced the fluorescence peak around 694 nm but did not improve the red hue of the samples. Two major changes were found in the experiments. One was the dark blue core of the samples that faded as the heating temperature increased. They were verified by the spectra to be the variation in the intervalence charge transfer between Fe²⁺ and Ti⁴⁺. The variation in the intervalence charge transfer of Mong Hsu ruby was not noticeable before heating to 900 °C but changed dramatically when heated to 1200 °C. The other was the shift of the FTIR peak, which is caused by decomposition of minerals due to heating. An FTIR 630 cm⁻¹ peak proved to be sensitive to the low-temperature heating and might be helpful for detecting low-temperature treatment. Full article

Photodynamic therapy is an accepted therapy cancer treatment. Its advantages encourage researchers to delve deeper. The use of nanoparticles in PDT has several advantages including the passive targeting of cancer cells. The aim of this article is to evaluate the effectiveness of AGuIX nanoparticles (activation and guiding of irradiation by X-ray) in the presence or absence of a photosensitizer, Photofrin, under illumination of 630 nm or under X-ray irradiation. The goal is to improve local tumor control by combining PDT with low-dose-X-ray-activated NPs in the treatment of locally advanced metastatic lung cancer. The study of the energy transfer, which occurs after excitation of Gd/Tb chelated in AGuIX in the presence of Photofrin, was carried out. We could observe the formation of singlet oxygen after the light or X-ray excitation of Gd and Tb that was not observed for AGuIX or Photofrin alone, proving that it is possible to realize energy transfer between both compounds. Full article

Red color conversion materials have often been used in conventional white LEDs (light-emitting diodes) to enhance the insufficient deep-red component and thus improve the color-rendering property. Quantum dots (QDs) are one of the candidates for this due to their flexibility in controlling the emission wavelength, which is attributed to the quantum confinement effect. Two types of remote QD components, i.e., QD films and QD caps, were prepared and applied to conventional white LED illumination to improve the color-rendering properties. Thanks to the red component near 630 nm caused by the QD components, the color rendering indices (CRIs) of both Ra and R9 could be increased to over 95. It was found that both the diffusing nature of the reflector and the light recycling process in the vertical cavity between the bottom reflector and the top optical films play important roles in improving the color conversion efficiency of remote QD components. The present study showed that the proper application of remote QDs combined with a suitable optical cavity can control the correlated color temperature of the illumination over a wide range, thus realizing different color appearances of white LED illumination. In addition, a high CRI of over 95 could be achieved due to the sufficient excitation from fewer QDs, due to the strong optical cavity effect. Full article

Objectives: The aim of the study was to clinically evaluate the efficacy of photodynamic therapy in treatment of the reticular form of oral lichen planus (OLP). Materials and Methods: Twenty patients aged 40–76, with 40 confirmed OLP lesions in total, underwent photodynamic therapy (PDT) following the authors’ own protocol, which used 5% 5-aminolevulinic acid as a photosensitizer applied two hours prior to illumination with a diode lamp emitting light at 630 nm and 300 mW. The therapy comprised of 10 weekly illumination sessions and was clinically evaluated between its completion and the end of a 12-month follow-up. Results: While the baseline mean size of all 40 lesions was 2.74 ± 3.03 cm², it was 2.97 ± 3.4 cm² for the 30 lesions on the buccal mucosa and 2.02 ± 1.32 cm² for the remaining 10 on the gingiva and tongue. On completion of the therapy, 37 sites improved, including 14 showing complete remission. From that point, the mean size reduction of 56.2% (1.2 ± 1.4 cm²) rose to 67.88% (0.88 ± 1.3 cm²) 12 months later. Conclusions: The results suggest that ALA-mediated photodynamic therapy was effective for the reticular form of OLP and may become an optional or complementary treatment. Full article

An innovative plant growth monitoring and environmental control platform is designed and implemented in this study. In addition to using multi-band artificial light sources for plant growth and development, an artificial intelligence of things (AIoT) approach is also utilised for environmental parameter monitoring, control, and the recording of plant growth traits and diseases. The five LED bands are white (5000 K), cool white (5500 K), blue (peak: 450 nm), red (660 nm), and light red (630 nm). The tea plant (Camellia sinensis f. formosana) is irradiated using lighting-emitting diodes (LED) composed of bands of different wavelengths. In addition, the number of leaves, contour area of the leaves, and leaf colour during the growth period of two varieties of tea plants (Taicha No. 18 and Taicha No. 8) under different irradiation intensities are analysed. Morphological image processing and deep learning models are simultaneously used to obtain plant growth characterization traits and diseases. The effect of the spectral distribution of the light source on the growth response of tea leaves and the effect of disease suppression are not fully understood. This study depicts how light quality affects the lighting formula changes in tea plants under controlled environments. The experimental results show that in three wavelength ranges (360–500 nm, 500–600 nm, and 600–760 nm), the light intensity ratio was 2.5:2.0:5.5 when the illuminance intensity was about 150 µmol∙m⁻²∙s⁻¹ with a photoperiod of 20:4 (dark); this enabled more leaves, a smaller contour area of the leaves, and a light green colour of the leaves of the tea plant (Taicha No. 18). In addition, during the lighting treatment, when the ratio of the band with an irradiation intensity of 360–500 nm to that with an irradiation intensity of 500–600 nm was 2:1.5, it resulted in a better leaf disease inhibition effect. When the light intensity was increased to more than 400 µmol∙m⁻²∙s⁻¹, it had little effect on the growth and development of the tea plants and the inhibition of diseases. The results of the study also found that there was a significant difference between the colour of the leaves and the relative chlorophyll content of the tea trees. Finally, the tea plant growth response data obtained from manual records and automatic records are compared and discussed. The accuracy rates of leaf number and disease were 94% and 87%, respectively. Compared with the results of manual measurement and recording, the errors were about 3–15%, which verified the effectiveness and practicability of the proposed solution. The innovative platform provides a data-driven crop modeling application for plant factories. Full article

We report the design simulation of the Raman spectrometer using Zemax optical system design software. The design is based on the Czerny–Turner configuration, which includes an optical system consisting of an entrance slit, two concave mirrors, reflecting type diffraction grating and an image detector. The system’s modeling approach is suggested by introducing the corresponding relationship between detector pixels and wavelength, linear CCD receiving surface length and image surface dimension. The simulations were carried out using the POP (physical optics propagation) algorithm. Spot diagram, relative illumination, irradiance plot, modulation transfer function (MTF), geometric and encircled energy were simulated for designing the Raman spectrometer. The simulation results of the Raman spectrometer using a 527 nm wavelength laser as an excitation light source are presented. The present optical system was designed in sequential mode and a Raman spectrum was observed from 530 nm to 630 nm. The analysis shows that the system’s image efficiency was quite good, predicting that it could build an efficient and cost-effective Raman spectrometer for optical diagnostics. Full article

Using light emitting diodes (LEDs) for greenhouse illumination enables the use of automatic control, since both light quality and quantity can be tuned. Potential candidate signals when using biological feedback for light optimisation are steady-state chlorophyll a fluorescence gains at 740 nm, defined as the difference in steady-state fluorescence at 740 nm divided by the difference in incident light quanta caused by (a small) excitation of different LED colours. In this study, experiments were conducted under various background light (quality and quantity) to evaluate if these fluorescence gains change relative to each other. The light regimes investigated were intensities in the range 160–1000 $\mathsf{\mu }\mathrm{mol} {\mathrm{m}}^{-2} {\mathrm{s}}^{-1}$ , and a spectral distribution ranging from 50% to 100% red light. No significant changes in the mutual relation of the fluorescence gains for the investigated LED colours (400, 420, 450, 530, 630 and 660 nm), could be observed when the background light quality was changed. However, changes were noticed as function of light quantity. When passing the photosynthesis saturate intensity level, no further changes in the mutual fluorescence gains could be observed. Full article