Quasi-photonic crystals-boosted highly efficient Ti3C2Tx MXene photothermal materials for untethered actuators and therapeutics.

Near-field thermophotovoltaic systems can achieve ultrahigh power densities, however, this often comes at the cost of reduced efficiency. We show that this power-efficiency trade-off can be mitigated through substrate engineering. We exploit gradient-based optimization and show that thin lossless metallic films with plasma frequencies resonantly matched to the plasmonic emitter can yield high power and spectral efficiency by spectrally enhancing and confining radiative heat transfer to a narrow spectral range just above the photovoltaic bandgap. Compared to noble metals and air-bridged structures, designs deriving from such optimization yield more than an order-of-magnitude increase in radiative power density while maintaining high efficiency. Our results highlight the critical role of the substrate and the potential of substrate optimization for overcoming fundamental limitations of near-field thermophotovoltaic systems.

Dual statistical modeling using Box Behnken and d-optimal designs for optimization of indocyanine green conjugated silver nanoparticles and improvement of their associated photothermal therapy for application in wound healing.

The manuscript discusses the challenges of metrological support for rapidly developing technologies, including electronics, radio vision, and security systems. To foster successful technological advancement, it is essential to expand the state standard base into a higher frequency range of 100–1000 GHz. This expansion is crucial for the verification and certification of devices and measuring instruments operating in the terahertz (millimeter) frequency range. Currently, the frequency range of the State Primary Standard for the unit of spectral power density of radio noise radiation, as defined in GET 21-2021, spans from 0.002 to 178.3 GHz. However, this frequency range is insufficient for the precise testing and certification of the high-precision devices and measuring instruments that are currently being developed. The manuscript presents the results of the development and study of the experimental sample of the primary standard of the unit of spectral power density of radio noise radiation in the frequency range of 220–300 GHz. The experimental sample includes a radiometer, a signal generator for the local oscillator channel, a low-temperature noise generator, a matched load, and a standard attenuator. The following characteristics of the experimental sample are achieved: the equivalent noise temperature of a low-temperature noise generator is from 103 K (220 Hz) to 120 K (300 GHz). The sensitivity of the comparator based on the radiometer is 0.86 K. The characteristics of the experimental sample are comparable with the characteristics of similar devices from the world's leading manufacturer, Radiometer Physics (Germany). The developed experimental sample can be used to calibrate low-noise receiving and amplifying devices of the terahertz range, which are finding increasing application in various fields of science and technology. An important area of application of the developed standard is also the verification of radiometers used in passive radar systems. Additionally, it is noteworthy that the developed radiometer (operating within 220–300 GHz) holds potential for scientific problems related to conducting radio astronomical terrestrial observations in the terahertz range, in particular in atmospheric transparency windows at wavelengths of 1.3 and 0.8 mm, where many spectral lines of atoms and molecules are concentrated.

Bi-modified octahedral cuprous oxide with exposed high-active surface for Fenton-like catalytic degradation of complex polluted water.

Bioorthogonal chemistry that can be controlled through near-infrared (NIR) light is a promising route to therapeutics. This study proposes a method to intracellularly photoactivate prodrugs using plasmonic gold nanostars (AuNSt) and NIR irradiation. Two strategies are followed. On one hand, doxorubicin (Dox) masked with a 2-nitrobenzyl carbamate (proDox1) is used as a photoactivatable prodrug. In the second strategy, a photolabile Dox prodrug (proDox2) obtained by modification of Dox with 2-nitrobenzyl diol bearing a disulfide is attached to the AuNSt surface. Under NIR irradiation AuNSt induce local electromagnetic field enhancement, leading to photocleavage of the 2-nitrobenzyl moiety in both proDox1 and proDox2, and subsequent Dox release. Near field enhancement by excitation of surface plasmons in AuNSt is sufficient to record the surface-enhanced Raman scattering (SERS) spectra of proDox1 and proDox2. The therapeutic potential of this bioorthogonal photoactivation strategy is confirmed in vitro and in vivo using a mouse model of human melanoma. NIR-activated AuNSt induce in vivo the intracellular release of Dox and subsequent cancer cell death, thus reducing tumor growth at low irradiation power density to avoid undesired photothermal effects. These results demonstrate that AuNSt are suitable platforms for NIR light-triggered drug delivery in cancer therapy.

Effects of high and low irradiance excimer light in repigmenting vitiligo: A single-center cross-sectional study

Background: In modern medicine, various technical means and developments are actively used in invasive intravascular (IVL) and non-invasive transcutaneous blood irradiation methods, including low-intensity laser radiation (LLLR) of various ranges. Despite the positive clinical results of such exposure, the physical and molecular mechanisms remain incompletely understood. Ultraviolet (UV) and terahertz (THz) ranges of electromagnetic radiation are classified as biogenic; therefore, establishing their effects at the level of blood cells will allow them to be recommended for use in medical and biotechnological practice after the development of appropriate exposure methods. The objective was to study the biogenic activity of ultraviolet (UV) and terahertz (THz) ranges of LLLR on the structural and functional state of red blood cells of rats in vitro. Materials and methods: Using methods of microelectrophoresis, spectrophotometry and chemical erythrograms, the following was studied: zeta potential of red blood cells; the content of the primary products of lipid peroxidation in the red blood cells (fatty acid conjugates of membrane of red blood cells phospholipids — diene (DK), triene (TK), and tetraene (TTK), oxodiene (ODK); resistance of erythrocytes to the action of an acid hemolytic after previous laser irradiation in the UV and THz ranges. Laser irradiation of the samples in the UV range was carried out by a nitrogen pulsed laser (λ = 0.337 μm), with the average radiation power 5 mW; irradiation in the THz range with a continuous CO2 laser (λ = 118.8 μm), the average radiation power is 20 mW. When the samples were irradiated, the density of radiation power W did not exceed 7 W/m2. The exposure dose under nitrogen laser irradiation was D1UV=0.109 J/cm2, D2UV=0.327 J/cm2, D3UV=0.546 J/cm2. Under CO2 laser irradiation, the exposure dose was D1THz=0.624 J/cm2, D2THz=1.871 J/cm2, D3THz=3.119 J/cm2. The thickness of irradiated red blood cell suspension layer was 1 mm. Results: The effect of low-dose LLLR UV and THz radiation causes physicochemical changes in the plasma membrane of erythrocytes. A nonlinear dose-dependent decrease in the electrokinetic potential of the cell surface and an increase in the hemolytic sensitivity of erythrocytes against the background of activation of lipid peroxidation processes in erythrocyte membranes have been established. Conclusions: Under the influence of LLLR, the free-radical peroxidation of lipids of erythrocyte membranes is stimulated. Pronounced biogenic activity of UV of LLLR was detected at the level of erythrocyte membranes. The obtained data can be used to expand the spectrum of application of LLLR of the UV range in IVL techniques.

This paper evaluates the impact of a floating photovoltaic system on lake temperature using a one-dimensional thermal model. The modeling approach incorporates established heat flux formulations and lake temperature dynamics, utilizing key meteorological inputs such as power density of solar radiation, wind speed, air temperature, humidity, and precipitation. The model analyzes temperature variations at different depths under various floating photovoltaic system coverage scenarios and compares them to a reference case without a floating photovoltaic system. The results indicate that a floating photovoltaic system affects the lake’s thermal regime by enhancing cooling during warmer months and limiting heat loss in colder periods. A floating photovoltaic system also alters latent heat flux and evaporation, further affecting the lake’s energy balance and stratification. These findings highlight the importance of considering FPV-related thermal effects in environmental assessments.

We demonstrate a high-performance mid-infrared (MIR) light-emitting diode (LED) based on a black phosphorus (b-P)/n-MoS2 heterojunction. A gold back contact combined with a rhenium-doped n-type MoS2 layer is used to enhance light extraction. The device shows a MIR peak external quantum efficiency (EQE) of (1.6 ± 0.2)% at room temperature and a record (7.0 ± 0.5)% EQE at 77 K, with a maximum radiant power density of (108 ± 8) W/cm2. Finite-element simulations highlight the importance of phonon-assisted band-to-band tunneling under reverse bias and the influence of carrier velocity saturation under forward bias. The simulations also reveal that the high ideality factors extracted from the current-voltage characteristic are due to current crowding at the heterojunction and a consequence of the device geometry. These findings establish a new high-performance b-P LED architecture and provide crucial insights into the physics of MIR sources based on 2D materials.

The rapid advancement of portable device technology, especially in the realms of drones and motor-driven systems, underscores the critical need for thorough analysis of Electromagnetic Interference (EMI) to guarantee operational reliability and safety. These systems’ vulnerability to EMI can result in diminished performance and heightened safety concerns, making it essential to evaluate their susceptibility. This research explores how brushless and brushed motors respond to EMI through Characteristic Mode Analysis (CMA), pinpointing significant frequency modes—2.1 GHz, 2.92 GHz, and 2.98 GHz—that impact motor functionality differently, with Mode 1 at 2.1 GHz being the most significant. Due to constraints in testing capabilities, the study focused on radiation exposure at 2.45 GHz. Experiments conducted with a 22 kW electromagnetic source revealed that as the motor neared the source, disruptions increased, culminating in total motor failure at a distance of 0.6 m. Additionally, the extensive wiring connected to the motor intensified damage by inducing extra currents, thereby amplifying the motor’s susceptibility beyond that of direct radiation exposure. The results of this study demonstrate the effectiveness of CMA in forecasting EMI effects and offer critical insights into the vulnerabilities present in motor-driven systems. By identifying the relevant radiation frequency, pattern, and power density that contribute to component damage, proactive measures can be taken to shield electronic components from adverse environmental conditions characterized by these factors.

Janus nanocellulose composite films with superior electromagnetic interference shielding and dual-thermal management.

Abstract The energy and its source of ball lightning (BL) have long been a mystery. At present, there is no consensus on the energy source of BL. The radiation power density and its evolution of a BL are investigated based on its spectra for the first time. The results show that the radiation power density calculated by O I spectral lines is the highest, and its average value is about 37.40 × 107 W/m2. The average radiation power densities calculated by Si I and Fe I spectral lines are only around 3.04 × 107 W/m2 and 2.56 × 107 W/m2, which remained basically steady during the stable luminescence stage. The spectral and energy feature indicated that the BL maybe exist a core with higher energy. The radiation power density shows a periodic pulse feature in the energy core and maintains basically stable in the bright periphery with lower energy. The highest energy of this BL can only excite light radiation of the near infrared band from the O I atoms in the air. The BL moved toward the nearby power line. Deduced from the energy distribution and moving direction that this BL should be associated with small gap intermittent discharge at the bottom of previous cloud‐to‐ground (CG) lightning channel, meanwhile, the strong atmospheric electric field during thunderstorm and its distribution should be a potential outside source that drives the discharge and moving direction of this BL. This work has important reference significance to reveal the mystery of BL and the application of BL phenomenon.

Atmospheric turbulence introduces distortions to the wavefront of propagating optical radiation. It causes image resolution degradation in astronomical telescopes and significantly reduces the power density of radiation on the target in focusing applications. The impact of turbulence fluctuations on the wavefront can be investigated under laboratory conditions using either a fan heater (roughly tuned), a phase plate, or a deformable mirror (finely tuned) as a turbulence-generation device and a wavefront sensor as a wavefront-distortion measurement device. We designed and developed a software simulator and an experimental setup for the reconstruction of atmospheric turbulence-phase fluctuations as well as an adaptive optical system for the compensation of induced aberrations. Both systems use two 60 mm, 92-channel, bimorph deformable mirrors and two tip-tilt correctors. The wavefront is measured using a high-speed Shack–Hartmann wavefront sensor based on an industrial CMOS camera. The system was able to achieve a 500 Hz correction frame rate, and the amplitude of aberrations decreased from 2.6 μm to 0.3 μm during the correction procedure. The use of the tip-tilt corrector allowed a decrease in the focal spot centroid jitter range of 2–3 times from ±26.5 μm and ±24 μm up to ±11.5 μm and ±5.5 μm.

To investigate the influence of enlarged cross-section railway tunnels on high-speed trains' aerodynamic noise source characteristics, the improved delayed detached eddy simulation method is employed to calculate the unsteady flow field around the high-speed train. The aerodynamic noise source characteristics on the train's surface are predicted using the Ffowcs Williams–Hawkings acoustic model. The accuracy of the numerical method is validated through wind tunnel experiments. The results show that, across different operation stages, the unsteady flow field distribution around the high-speed train exhibits similar characteristics. Significant differences are observed in the pulsating pressure distribution on the surfaces of the train body, pantograph, and bogie; however, the dominant frequency remains constant as the train moves. While passing through the enlarged cross section, the sound pressure level at the nose of the head car, the streamlined of the tail car, and the pantograph decreases by 3.1, 10.0, and 9.1 dBA, respectively. The enlarged cross section significantly affects the radiated sound power on the train surface, with the pantograph exhibiting the highest noise radiation power density, followed by the bogie and the train body. The distribution of sound power levels on the train body and pantograph shows distinct dominant frequency characteristics. After passing through the enlarged cross section, the sound power level of the head car decreases by a maximum of 6.7%, while the tail car experiences the slightest reduction of 3.1%. The sound power level of the pantograph decreases only marginally by 3.5 dBA over the entire operation.

The increased use of smartphones in daily life challenges researchers regarding the quality of light emitted by screens. This study aims to analyze displays’ qualitative and quantitative light parameters from various smartphone models available on the market over the last decade. Advanced photometric and colorimetric measurements using complex instrumentation were performed. It covered the color gamut, channel linearity response, refresh rate, flickering, spatial radiation distribution, luminance, uniformity, and static contrast. The analysis showed that, despite advances in smartphone display technology, differences in visible radiation parameters between older and newer models are surprisingly marginal. However, improvements were observed in newer models in terms of viewing angles and compliance with the sRGB standard. Tested built-in blue light reduction filters were ineffective. It only slightly reduces light between 380 nm and 480 nm. In contrast, much higher decreases in this spectral range were achieved for dedicated applications. However, it lowered radiant power density across the visible spectrum, significantly decreasing the displays’ correlated color temperature. Enabling the power-saving mode caused the deterioration of parameters such as refresh rate, but the flicker depth remained constant. Static contrast for most tested devices was also at the same level. The findings confirm the need for further studies on display technology development that supports user well-being while minimizing its harmful effects.

The morphology of zinc oxide microstructures obtained by microwave synthesis has been studied and the features of its photoluminescence spectra have been revealed. X-ray diffraction analysis revealed that the synthesised zinc oxide samples have hexagonal crystalline structure. It was found that with increasing power density of excitation radiation in zinc oxide microstructures, band narrowing is observed and the maximum intensity of the photoluminescence spectrum shifts to the long-wave region. It is shown that zinc oxide microcrystalline structures obtained by microwave synthesis have a significant intensity of ultraviolet luminescence bands of free excitons at room temperature and are promising for the creation of short-wave light sources.

Purpose. To compare light-oxygen and photodynamic effects at the development of inflammatory reactions caused by histamine so as to study mechanisms of the singlet oxygen effect at biological objects and to optimize their application in clinical practice.Materials and methods. A domestic diode laser ‘Super Sab’ with λ ≈ 1265 nm (produced by New Surgical Technologies LLC, Moscow, Russia) was used as a source of laser light. 10 female rats of Wistar population weighing 250–300 g were taken in the study. Power density of laser irradiation was 0.25 W/cm2 (exposure dose – 30 J/cm2). Not irradiated scarification sites were used as controls. Histamine concentration in the solution after its irradiation with the same laser was studied by the immunoenzymatic analysis. Photodynamic effect was studied in 12 volunteers; scarification samples with histamine and preliminary applied gel photosensitizer ‘Photoditazine’ were put to them, and the subsequent irradiation with laser light generated by device ‘Atkus-2’ (produced by CJSC ‘Semiconductor Devices, St. Petersburg) having λ ≈ 662 nm, power density 0.3 W/cm2 and exposure dose 50 J/cm2 was made. Scarifications without irradiation were used as controls.Results. Reliable results (p ≤ 0.01) obtained in the experimental animals revealed the decrease of inflammatory reactions at the irradiated scarification sites with histamine application compared to the controls. While examining the histamine solution irradiated in vitro, no decrease in the histamine concentration was found under different irradiation doses. Histamine tests in volunteers also revealed reliable results (p ≤ 0.05) when the decrease of inflammatory reactions was seen in them after photosensitiser application compared to the controls.Conclusion. The newly obtained data may clarify some mechanisms of light-oxygen and photodynamic therapy (LOT and PDT); they may also expand indications for clinical application of the discussed therapy and serve as a starting point for future in-depth trials in this direction. One of them, in particular, may be revealing changes in the chemical structure of some important biologically active substances under the impact of LOT and PDT.

Laser action on chromium-vanadium-nitride coatings on steel in ambient air by paired nanosecond laser pulses at wavelengths of 355 and 532 nm, in which the time interval is regulated within the pair and the pulse order and radiation power densities are varied from tens to hundreds of MW/cm<sup>2</sup>, allows one to achieve wider possibilities of modifying the surface structure, properties, and composition of irradiated coatings.

The study of the effectiveness of soft wheat seeds pre-sowing treatment with a continuous semiconductor laser (the wavelength of λ = 637 nm, the power density (Wp) of 2, 4, 8 W/m2, the duration of exposure of 5, 30, 60 seconds) is presented in the work. The maximal increase in the wheat yield, as well as in the growth of most morphometric indicators of its productivity, was recorded in the experimental variant during pre-sowing seed treatment with the laser with a maximum power density of 8 W/m2 and with the longest exposure time of 60 seconds. In addition, when seeds were irradiated with a laser with a maximum power density of 8 W/m2, a decrease in the development of a complex of especially dangerous pathogens (helminthosporiosis root rot, septoria-pyrenophorous spotting, yellow rust) was observed. In general, with an increase in the power density of laser radiation and in the time of its exposure to seeds, the growth of the maximum number of morphometric indicators of wheat productivity and a decrease in the intensity of disease affect were revealed.