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In this paper, we study the design aspects of an indoor visible light positioning (VLP) system that uses an artificial neural network (ANN) for positioning estimation by considering a multipath channel. Previous results usually rely on the simplistic line of sight model with limited validity. The study considers the influence of noise as a performance indicator for the comparison between different design approaches. Three different ANN algorithms are considered, including Levenberg-Marquardt, Bayesian regularization, and scaled conjugate gradient algorithms, to minimize the positioning error (εp) in the VLP system. The ANN design is optimized based on the number of neurons in the hidden layers, the number of training epochs, and the size of the training set. It is shown that, the ANN with Bayesian regularization outperforms the traditional received signal strength (RSS) technique using the non-linear least square estimation for all values of signal to noise ratio (SNR). Furthermore, in the inner region, which includes the area of the receiving plane within the transmitters, the positioning accuracy is improved by 43, 55, and 50% for the SNR of 10, 20, and 30 dB, respectively. In the outer region, which is the remaining area within the room, the positioning accuracy is improved by 57, 32, and 6% for the SNR of 10, 20, and 30 dB, respectively. Moreover, we also analyze the impact of different training dataset sizes in ANN, and we show that it is possible to achieve a minimum εp of 2 cm for 30 dB of SNR using a random selection scheme. Finally, it is observed that εp is low even for lower values of SNR, i.e., εp values are 2, 11, and 44 cm for the SNR of 30, 20, and 10 dB, respectively.
- Klíčová slova
- Bayesian regularization, artificial neural network (ANN), multipath reflections, non-linear least square, visible light communication (VLC), visible light positioning,
- MeSH
- algoritmy * MeSH
- Bayesova věta MeSH
- metoda nejmenších čtverců MeSH
- neuronové sítě * MeSH
- světlo MeSH
- Publikační typ
- časopisecké články MeSH
Light-driven micro/nanomotors represent the next generation of automotive devices that can be easily actuated and controlled by using an external light source. As the field evolves, there is a need for developing more sophisticated micromachines that can fulfill diverse tasks in complex environments. Herein, we introduce single-component BiVO4 micromotors with well-defined micro/nanostructures that can swim both individually and as collectively assembled entities under visible-light irradiation. These devices can perform cargo loading and transport of passive particles as well as living microorganisms without any surface functionalization. Interestingly, after photoactivation, the BiVO4 micromotors exhibited an ability to seek and adhere to yeast cell walls, with the possibility to control their attachment/release by switching the light on/off, respectively. Taking advantage of the selective motor/fungal cells attachment, the fungicidal activity of BiVO4 micromotors under visible illumination was also demonstrated. The presented star-shaped BiVO4 micromotors, obtained by a hydrothermal synthesis, contribute to the potential large-scale fabrication of light-powered micromotors. Moreover, these multifunctional single-component micromachines with controlled self-propulsion, collective behavior, cargo transportation, and photocatalytic activity capabilities hold promising applications in sensing, biohybrids assembly, cargo delivery, and microbiological water pollution remediation.
- Klíčová slova
- bismuth vanadate, cargo transport, fungicidal activity, micromotors, visible light,
- MeSH
- bismut chemie MeSH
- elektrochemické techniky MeSH
- nanostruktury chemie MeSH
- povrchové vlastnosti MeSH
- Saccharomyces cerevisiae cytologie izolace a purifikace MeSH
- světlo * MeSH
- vanadáty chemická syntéza chemie MeSH
- velikost částic MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- bismut MeSH
- bismuth vanadium tetraoxide MeSH Prohlížeč
- vanadáty MeSH
Micro/nanomotors are capable of a wide variety of tasks related, i.e., to biomedical or environmental applications. Light-driven semiconductor-based micromotors are especially appealing, as they can split surrounding water via light irradiation, and therefore, they can move infinitely. However, their motion is typically limited to in-plane motion with four degrees of freedom (4DoF) or even pseudo-1D motion with 2DoF. Herein, magnetically steerable tubular TiO2 /Fe3 O4 /CdS micromotors, termed microsubmarines, with 6DoF motion, based on a fuel-free design where surrounding water acts as fuel upon visible light irradiation, are presented, with an average velocity of 7.9 µm s-1 . Besides, the generation of radicals via such water splitting aids the photocatalytic chemicals degradation with the potential to use solar radiation. A light-induced self-electrophoretic mechanism is responsible for the self-propulsion and can be used to predict the motion direction based on the structure and composition. Finally, the TiO2 /Fe3 O4 /CdS microsubmarines are tested in a proof-of-concept application of high-energy explosive, e.g., picric acid, photocatalytic degradation, with the best performance owing to the versatility of 6DoF motion, the surface coating with amorphous TiO2 layer, and UV light. The results can help optimize light-active micromotor design for potential national security and environmental application, hydrogen evolution, and target cargo delivery.
- Klíčová slova
- explosive decontamination, micromotor, six degrees of freedom, visible-light-driven, water fuel,
- MeSH
- dekontaminace MeSH
- světlo MeSH
- voda * MeSH
- vodík MeSH
- výbušné látky * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- voda * MeSH
- vodík MeSH
- výbušné látky * MeSH
Underwater visible light communication (UVLC) has recently come to light as a viable wireless carrier for signal transmission in risky, uncharted, and delicate aquatic environments like seas. Despite the potential of UVLC as a green, clean, and safe alternative to conventional communication methods, it is challenged by significant signal attenuation and turbulent channel conditions compared to long-distance terrestrial communication. To address linear and nonlinear impairments in UVLC systems, this paper presents an adaptive fuzzy logic deep-learning equalizer (AFL-DLE) for 64 Quadrature Amplitude Modulation-Component minimal Amplitude Phase shift (QAM-CAP)-modulated UVLC systems. The proposed AFL-DLE is dependent on complex-valued neural networks and constellation partitioning schemes and utilizes the Enhanced Chaotic Sparrow Search Optimization Algorithm (ECSSOA) to improve overall system performance. Experimental outcomes demonstrate that the suggested equalizer achieves significant reductions in bit error rate (55%), distortion rate (45%), computational complexity (48%), and computation cost (75%) while maintaining a high transmission rate (99%). This approach enables the development of high-speed UVLC systems capable of processing data online, thereby advancing state-of-the-art underwater communication.
- Klíčová slova
- adaptive fuzzy logic, deep learning, deep-learning equalizer, equalization, sparrow search optimization, underwater visible light communication,
- MeSH
- algoritmy MeSH
- deep learning * MeSH
- fuzzy logika MeSH
- komunikace MeSH
- světlo MeSH
- Publikační typ
- časopisecké články MeSH
Photocatalytic micromotors are light-induced, chemically powered micromachines based on photocatalytic materials, activated by light illumination, and have redox reactions with environmental solutions to produce chemical gradients and bubbles that propel the micromachines through self-diffusiophoresis, self-electrophoresis, and bubble recoil. Due to the fact that excitation light relates largely to the bandgaps of selected materials, the development of photocatalytic micromotors has experienced an evolution from ultraviolet-light-activated to visible-light-activated and potentially biocompatible systems. Furthermore, due to the strong redox capacity and physical effects caused by the products or product gradients, photocatalytic micromotors have applications in environmental remediation, micropumps, reversible assembly, transportation, and biomimicry.
- Klíčová slova
- light-activated systems, photocatalytic micromotors, product gradient,
- MeSH
- biomimetické materiály MeSH
- fotochemické procesy * účinky záření MeSH
- mikrotechnologie MeSH
- regenerace a remediace životního prostředí * trendy MeSH
- světlo * MeSH
- ultrafialové záření * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Visible light communication (VLC) is a new paradigm that could revolutionise the future of wireless communication. In VLC, information is transmitted through modulating the visible light spectrum (400⁻700 nm) that is used for illumination. Analytical and experimental work has shown the potential of VLC to provide high-speed data communication with the added advantage of improved energy efficiency and communication security/privacy. VLC is still in the early phase of research. There are fewer review articles published on this topic mostly addressing the physical layer research. Unlike other reviews, this article gives a system prespective of VLC along with the survey on existing literature and potential challenges toward the implementation and integration of VLC.
- Klíčová slova
- LED communication, VLC networks, optical communication, visible light communication,
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Reported is the controllable selectivity syntheses of four distinct products from the same starting materials by visible-light photoredox catalysis. By employing a dicyanopyrazine-derived chromophore (DPZ) as photoredox catalyst, an aerobic radical mechanism has been developed, and allows the reactions of N-tetrahydroisoquinolines (THIQs) with N-itaconimides to through four different pathways, including addition-cyclization, addition-elimination, addition-coupling, and addition-protonation, with satisfactory chemoselectivity. The current strategy provide straightforward access to four different but valuable N-heterocyclic adducts in moderate to excellent yields.
- Klíčová slova
- heterocycles, photochemisty, radicals, reaction mechanisms, synthetic methods,
- MeSH
- cykloadiční reakce MeSH
- katalýza MeSH
- oxidace-redukce MeSH
- světlo * MeSH
- volné radikály chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- volné radikály MeSH
Photoactivatable agents offer the prospect of highly selective cancer therapy with low side effects and novel mechanisms of action that can combat current drug resistance. 1,8-Naphthalimides with their extended π system can behave as light-harvesting groups, fluorescent probes and DNA intercalators. We conjugated N-(carboxymethyl)-1,8-naphthalimide (gly-R-Nap) with an R substituent on the naphthyl group to photoactive diazido PtIV complexes to form t,t,t-[Pt(py)2 (N3 )2 (OH)(gly-R-Nap)], R=H (1), 3-NO2 (2) or 4-NMe2 (3). They show enhanced photo-oxidation, cellular accumulation and promising photo-cytotoxicity in human A2780 ovarian, A549 lung and PC3 prostate cancer cells with visible light activation, and low dark cytotoxicity. Complexes 1 and 2 exhibit pre-intercalation into DNA, resulting in enhanced photo-induced DNA crosslinking. Complex 3 has a red-shifted absorption band at 450 nm, allowing photoactivation and photo-cytotoxicity with green light.
- Klíčová slova
- DFT calculations, DNA intercalation, anticancer activity, interstrand crosslinking, photoactive platinum complexes,
- MeSH
- DNA MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- nádory vaječníků * MeSH
- organoplatinové sloučeniny MeSH
- platina MeSH
- protinádorové látky * farmakologie MeSH
- světlo MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- DNA MeSH
- organoplatinové sloučeniny MeSH
- platina MeSH
- protinádorové látky * MeSH
Fluorescein, eosin Y, and rose bengal are dyes used in clinical medicine and considered (photo-)chemically stable. Upon extensive irradiation with visible light in aqueous solutions, we found that these compounds release carbon monoxide (CO) - a bioactive gasotransmitter - in 40-100% yields along with the production of low-mass secondary photoproducts, such as phthalic and formic acids, in a multistep degradation process. Such photochemistry should be considered in applications of these dyes, and they could also be utilized as visible-light activatable CO-releasing molecules (photoCORMs) with biological implications.
Visible Light Communication (VLC) has received substantial research attention in the last decade. The vast majority of VLC focuses on the modulation of the transmitted light intensity. In this work, however, the intensity is kept constant while the polarization direction is deployed as a carrier of information. Demodulation is realized by using a differential receiver pair equipped with mutually orthogonal polarizers. An analytical expression to evaluate the Signal-to-Noise Ratio (SNR) as a function of the rotation angle of the receiver is derived. It is demonstrated that the signal quality can deteriorate heavily with receiver orientation when using a single differential receiver pair. A way to overcome this drawback using two receiver pairs is described. The analytical expression is experimentally verified through measurements with two different receiver setups. This work demonstrates the potential of polarization-based modulation in the field of VLC, where receiver rotation robustness has been achieved by means of a dedicated quadrant photodiode receiver.
- Klíčová slova
- Visible Light Communication, differential, polarization, quadrant photodiode,
- Publikační typ
- časopisecké články MeSH
