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Realisation and assessment of a low-cost LED device for contact lens disinfection by visible violet light
摘要： This study presents a device for efficient, low-cost and eye-friendly overnight disinfection of contact lenses by visible violet light as an alternative to disinfection with biocide-containing solutions. Bacterial solutions with one Pseudomonas and one Staphylococcus strain each were irradiated for up to 8 h in commercial transparent contact lens cases by the presented light-emitting diode (LED) device. Samples were taken at different intervals and distributed on agar plates. The surviving bacteria were determined by counting of colony-forming units and compared to the specific requirements of the stand-alone test for contact lens disinfection of the hygiene standard ISO 14729. The concentration of both microorganisms was reduced by three orders of magnitude after less than 4 h of irradiation. The LED current and intensity have not yet been at maximum and could be further increased if necessary for other microorganisms. The presented device fulfils the requirement of the stand-alone test of the contact lens hygienic standard ISO 14729 for the tested Pseudomonas and Staphylococcus strains. According to literature data, the inactivation of Serratia marcescens, Candida albicans and Fusarium solani seems also possible, but may require increased LED current and intensity.
关键词： Staphylococcus,LED device,contact lens,visible light,photoinactivation,Pseudomonas,disinfection
更新于2025-09-12 10:27:22
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Porous single-wall carbon nanotube templates decorated with all-inorganic perovskite nanocrystals for ultra-flexible photodetectors
摘要： As an inevitable optoelectronic material with unique properties, halide perovskites attracted increasing attention in recent years. Meanwhile, hybridization of nanostructured perovskites with one-dimensional (1D) or two-dimensional (2D) functional materials has exhibited unique applications in nanotechnology. In this communication, a highly conducting porous single-wall carbon nanotube (p-SWCNT) template decorated with phase-pure CsPbBr3 nanocrystals by simple solution-phase technique was demonstrated, and the ultra-flexible photodetector Au/p-SWCNT:CsPbBr3/Au showed high sensitivity even in highly bending state. Also, the mechanism of wetting CsPbBr3 along p-SWCNT and the detailed fabrication process for ultra-flexible photodetectors were highlighted. The direct contact (in-situ) on p-SWCNT by crystallization of perovskite precursor can enhance the charge transfer at their interface effectively. At applied bias of +5 V, the optimized photodetector Au/p-SWCNT:CsPbBr3/Au exhibits a maximum photoresponsivity of 41.0 AW-1 with a specific detectivity of 1.67×1012 Jones under an incident 232 μW/cm2 520 nm illumination. In addition, it exhibits excellent mechanical and electrical properties even under high strain (i.e. bending angle up to -17°) and recovers the original performance after repeated bending cycles upto 1000 times. Our experimental results showed that such a hybrid materials provide a promising method for rigid and flexible optoelectronic devices.
关键词： Porous single-wall carbon nanotube (p-SWCN),inorganic perovskite nanocrystals,flexible photodetector,CsPbBr3,visible light photodetector
更新于2025-09-12 10:27:22
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A synthesis of graphene quantum dots/hollow TiO2 nanosphere composites for enhancing visible light photocatalytic activity
摘要： Given the versatility and value of the semiconductor composites for photocatalysis, we reported a new, friendly environment, high specific surface area material of the graphene quantum dots/hollow titanium dioxide nanosphere (GQDs/H-TiO2) composites which are synthesized through a simple hydrothermal method. GQDs (~ 5 nm) exhibit highly photoluminescent and widely visible light absorption properties. H-TiO2 has high surface area and abundant exposed active sites for photocatalysis. The research demonstrates that GQDs coupled on H-TiO2 can effectively enlarge the light absorption of the H-TiO2 to visible region (~ 650 nm) and enhance the electron–hole pair separation efficiency of GQDs/H-TiO2 composites owing to GQDs acting as an electron repository and electron transport bridge. In our delight, the photocurrent enhancement of newly prepared GQDs-3.0/H-TiO2 composite electrode was almost 3.5 times higher in comparison with that in pure H-TiO2 electrode at an applied voltage of 0.5 V using Na2SO4 (0.5 M) solution as the electrolyte. In addition, the photocatalytic activity of the prepared GQDs-3.0/H-TiO2 (96.9%) on the degradation of Rhodamine B (RhB) was also significantly enhanced compared with that of pure H-TiO2 (33.3%) after 180 min. The protocol is suitable not only for the GQDs-modified semiconductors photocatalysts but also provides further insights to apply GQDs to other energy conversion devices.
关键词： composites,graphene quantum dots,hollow TiO2 nanosphere,visible light photocatalytic activity
更新于2025-09-12 10:27:22
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Design and implementation of LED-LED indoor visible light communication system
摘要： This paper investigates the experimental performance of LEDs as both photo-emitter and photoreceiver. In this work LED-LED link is established using BJT and MOSFET based drive circuits at transmitting side and resistor driver operated in photo-conductive mode is used at the receiver side. The LED response as transmitter and receiver is investigated at different operating frequencies with the distance of up to 20 cm and the data rate of 1 Mbps. The SNR values of 8 dB and 11 dB are obtained using BJT and MOSFET drivers respectively at a distance of 20 cm. Furthermore, six different color LEDs are tested on both sides of transceiver to determine the best performing pair. It is observed that the red color LEDs have good responses as a photodiode due to its long wavelength in the visible spectrum. However their performance is significantly effected by ambient noise. Moreover, the responsivity of the Red color LED operated as photoreceiver with respect to different biasing voltages is also experimentally measured and discussed.
关键词： Visible Light Communication,LED as Photo-receiver,LED as Photo-emitter,Indoor communication,Responsivity
更新于2025-09-12 10:27:22
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Optical Fiber and Wireless Communications || Fundamental Analysis for Visible Light Communication with Input‐Dependent Noise
摘要： Recently, visible light communication (VLC) has drawn much attention. In literature, the noise in VLC is often assumed to be independent of the input signal. This assumption neglects a fundamental issue of VLC: due to the random nature of photon emission in the lighting source, the strength of the noise depends on the signal itself. Therefore, the input-dependent noise in VLC should be considered. Given this, the fundamental analysis for the VLC with input-dependent noise is presented in this chapter. Based on the information theory, the theoretical expression of the mutual information is derived. However, the expression of the mutual information is not in a closed form. Furthermore, the lower bound of the mutual information is derived in a closed form. Moreover, the theoretical expression of the bit error rate is also derived. Numerical results verify the accuracy of the derived theoretical expressions in this chapter.
关键词： bit error rate,input-dependent noise,visible light communication,mutual information
更新于2025-09-12 10:27:22
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A tunable synthesis of either benzaldehyde or benzoic acid through blue-violet LED irradiation using TBATB
摘要： In this paper, a highly efficient, metal-free, and homogeneous photooxidative-desilylation of tert-butyldimethylsilyl ethers (TBDMS) in the presence of tetrabutylammonium tribromide (TBATB) under irradiation of visible light was reported. The light source: blue (460 nm) and violet (400 nm) LED, can control selective oxidation to aldehyde or carboxylic acid.
关键词： tetrabutylamonium tribromide,benzyl alcohol,metal-free,tunable synthesis,oxidative-desilylation,visible light photocatalyst
更新于2025-09-12 10:27:22
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Fabrication of a novel type visible-light-driven heterojunction photocatalyst: metal-porphyrinic metal organic framework coupled with PW12/TiO2
摘要： Metalloporphyrinic metal-organic framework (PCN-222) is a promising photocatalytic material due to its large surface area and 1D channel, exceptional stability, high visible-light capture capability, and semiconductor properties. Herein, we constructed a highly efficient visible-light-driven type II heterojunction photocatalyst PCN-222-PW12/TiO2 by one step solvothermal method. The 5 wt. % PCN-222-PW12/TiO2 showed the superior photocatalytic properties for degrading rhodamine B (RhB) and Ofloxacin, which are 10.69 and 10.48 times higher than pure TiO2 under same conditions. The excellent photocatalytic performance of PCN-222-PW12/TiO2 ternary composite material was attributed to the improved adsorption capacity of organic pollutants, optical absorption in the entire visible light region, and highly-efficient separation of photoinduced carriers. Besides, we found that h+, ?O2-, and ?OH are the main active elements in the photocatalytic degradation process. This will back up the higher photocatalytic activity of PCN-222-PW12/TiO2 compared with pure TiO2. The photocatalytic efficiency of composite maintained a similar level of photoactivity after four times recovery, which showed excellent stability and recyclability of PCN-222-PW12/TiO2. This work provides new insights into the fabrication porphyrin-MOF composite materials with high photocatalytic efficiency for environmental remediation.
关键词： Metalloporphyrin-MOF,PW12/TiO2,Photocatalysis,visible-light driven,type II heterojunction
更新于2025-09-12 10:27:22
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[IEEE IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society - Lisbon, Portugal (2019.10.14-2019.10.17)] IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society - Review of LED drivers for Visible Light Communication
摘要： Visible Light Communication (VLC) shows up as a trend for short range wireless networks, which comes as a promising breakthrough for industry. However, this technology still faces challenges on the technical side. In particular, the selection of the appropriate circuit driver to fulfill simultaneously both lighting and communication functions is a non-trivial task. This paper reviews driver solutions intended for VLC applications, summarizing published research according to a proposed classification. Additionally, switched mode circuits stand out among the current works, supporting low data rates with higher overall efficiency at greater power levels. On the other hand, linear power amplifiers are the preferred choice for high data rate systems.
关键词： Efficiency,VLC,Visible Light Communication,LED Drivers,Illumination
更新于2025-09-12 10:27:22
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The fabrication of Au/Pd plasmonic alloys on UiO-66-NH <sub/>2</sub> : an efficient visible light-induced photocatalyst towards the Suzuki Miyaura coupling reaction under ambient conditions
摘要： Visible light harvesting by heterogeneous photocatalysts and their applications in organic transformation reactions for the synthesis of target molecules are quite demanding science in the current scenario. In this regard, herein, a novel metal (Au/Pd)-functionalized metal organic framework (UiO-66-NH2) was synthesized to carry out the Suzuki–Miyaura coupling (SMC) reaction under visible light irradiation at ambient conditions. In order to justify the claim regarding the formation of alloys, crystallinity, morphology, particle size, proper separation of excitons, elemental content and their environment, various sensitive characterization techniques such as XRD, XPS, HRTEM, BET surface area and UV-vis analysis were employed. A mechanistic approach by means of experimental investigations revealed that the strong LSPR effect of Au facilitated the transfer of electrons to the Pd surface to make the surface negatively charged and suitable for the activation of aryl halides. The formed electropositive Au nanoparticles were converted to Au0 by accepting the photo-induced electrons from pristine UiO-66-NH2 and made available only holes at VB for the activation of phenylboronic acid. Among all the synthesized photocatalysts (1 : 2), Au/Pd@UiO-66-NH2 showed the highest activity (>99%) with TOF = 426 h?1 in an EtOH/H2O medium towards the SMC reaction, and the highest activity of this catalyst was supported by the electron gas model, LSPR effect (UV-vis) and active species separation (PL) analysis. The bimetallic noble nanoparticle-anchored UiO-66-NH2 not only expands the synthesis scope of C–C coupling by the SMC reaction under ambient conditions but will also inspire the further exploration of the activation of various reactants towards a wide range of organic transformation reactions.
关键词： visible light harvesting,Suzuki–Miyaura coupling,heterogeneous photocatalysts,LSPR effect,Au/Pd-functionalized metal organic framework
更新于2025-09-12 10:27:22
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Facile constructing plasmonic Z-scheme Au NPs/g-C3N4/BiOBr for enhanced visible light photocatalytic activity
摘要： A novel ternary Au NPs/g-C3N4/BiOBr Z-scheme heterojunction composite was fabricated through hydrothermal and in-situ reduction method, and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible diffuse reflection spectroscopy and photoluminescence emission spectroscopy. The photocatalytic activity was evaluated by the degradation of phenol under visible-light irradiation. It was found that Au NPs/g-C3N4/BiOBr showed enhanced photocatalytic activity, which is 3-fold higher than g-C3N4 and 2.5-fold higher than BiOBr. This could be attributed to the effective separation of photogenerated electron-hole pairs, narrowed band gap (2.10 eV) and surface plasmon resonance (SPR).
关键词： Au NPs/g-C3N4/BiOBr,Z-scheme,phenol,visible-light photocatlysis,plasmon
更新于2025-09-12 10:27:22