Pulsed Irradiation Research Articles

Possibilities for increasing the effectiveness of treatment of respiratory infections of the upper respiratory tract in children of various age groups

The article discusses the experience of complex therapy of rhinitis and sinusitis in children of various age groups, confirming the effectiveness of the combined effects of local thermotherapy, pulsed red light and low-frequency magnetic field. This combination of physical factors has an anti-inflammatory, decongestant, stimulating local cellular activity effect and helps to increase the effectiveness and reduce the overall treatment time for these diseases. The purpose of the study is to evaluate the effectiveness of the combined use of heat, red spectrum phototherapy and magnetic field in the treatment of children with rhinitis and sinusitis. Materials and methods. The observation included 30 children with rhinitis and 40 children with sinusitis aged 2-18 years, receiving combined physiotherapy procedures as part of the main treatment. Results and its discussion. The positive effect of the combined effects of thermotherapy, pulsed light radiation in the red range and low-frequency magnetic field on clinical symptoms and functional indicators of nasal breathing in children with rhinitis and sinusitis has been confirmed. Conclusions. The use of a course of procedures combined with the effects of local thermotherapy, pulsed red light and low-frequency magnetic field against the background of the main treatment helps to increase the effectiveness of the treatment of respiratory infections of the upper respiratory tract in children of various age groups.

Особенности фазовых и структурных превращений в композиционных материалах на основе систем несмешивающихся компонентов при воздействии концентрированных потоков энергии

The features of phase and structural transformations in composite materials based on systems of immiscible components Al – Be, Al – Be – Mg, Fe – Cu, Fe – Cu – Pb under the influence of concentrated heat sources — electric arc, electron and laser beams — are considered. It is shown that when materials of the Al – Be, Al – Be – Mg systems are exposed to an electric arc plasma and an electron flow, they are melted and subsequently cooled by grain grinding, formation of a zone of thermal influence and crystallization of the resulting new structures and phases. In zone of thermal influence, the enrichment of the aluminum matrix with Be particles is observed due to the thermal diffusion processes of their movement. When plasma is exposed to an arc discharge, pulsed and continuous laser radiation, as well as the flow of electrons on the composition Fe – Cu, Fe – Cu – Pb, a change in the morphology of the near-surface layer is observed: the irradiated material in the melt zone is exfoliated and in the process of crystallization the stratified phases are fixed in a solid state. The mechanism of stratification formation is associated with the limited solubility of the elements that make up the composition in the liquid and solid states.

Single hollow-core fiber for the guidance of IR (1030 nm) and visible (515 nm) ultrashort pulsed laser radiations

We present in this contribution a single large-mode area inhibited-coupling hollow-core fiber for guiding laser beam at a wavelength of 1030 nm and its second harmonic at 515 nm with confinement losses below 30 dB/km.

Increasing the shelf life of packaged bakery products by their processing of broadband optical radiation of a pulsed xenon lamp

Pulsed xenon lamps generating a wide spectrum of radiation of the megawatt range are sources of a new generation of biocidal radiation, which shows potential in the food industry. The article presents the results of studies of the efficiency of pulsed xenon lamp radiation in relation to antifungal treatment of bakery products in sealed plastic packaging in order to increase their shelf life. The object of research was commercial samples of bakery products packed in polypropylene film. The samples were processed by radiation from a pulsed xenon lamp with power of 300 watts. It is shown that irradiation of bakery products samples in the mode with an integral fluence of broadband optical radiation of 10 J/cm2 and a dose of short-wave UV radiation of 0.6 J/cm2 makes it possible to increase their shelf life several times (on average 2 times for most types of samples) compared with untreated samples. General conclusion: optical radiation of a pulsed xenon lamp has a pronounced antifungal effect and is able to inhibit the development of mold fungi on bakery products, even when they are processed in packaged form. The obtained results can be used in the development of equipment of antifungal treatment of bakery products.

Ultra-low intensity light pulses for large cargo delivery into hard-to-transfect cells using an rGO mixed PDMS microtip device.

Nanoparticle-mediated photoporation has arisen as a universal intracellular delivery tool; however, the direct interaction of nanoparticles and cells hampers its clinical translation. Here, we report a uniform contactless intracellular delivery that transfects a large number of cells within a minute and avoids direct contact of nanoparticles and cells, thereby improving the cell viability. Our platform consists of an array of polydimethylsiloxane (PDMS) mixed reduced graphene oxide (rGO) nanoflakes on pyramidal microtips, uniformly distributed at the apex of the tip. The extraordinary optoelectronic properties of rGO were combined with micro-pyramidal cavities to entrap light in micro-cavities and efficiently convert it into heat through multiple reflections and absorptions. As a result, ultralow infra-red laser pulse irradiation could create cavitation bubbles followed by cell membrane deformation and biomolecular delivery. Using this delivery platform, we have achieved the delivery of small to large cargo (668 Da to 465 kDa) in various mammalian cells, including hard-to-transfect H9C2 cardiomyocytes. The best results were achieved for enzyme (465 kDa) delivery with a transfection efficiency and cell viability of 95% and 98%, respectively, in SiHa cells. The highly efficient cargo delivery tool demonstrated a safe and effective approach for cell therapy and diagnostics.

Feasibility verification of ultrafast FEL generation experimental scheme based on SXFEL

The photon energy in the soft X-ray range corresponds to the fundamental absorption edges of matter. Ultrashort X-ray pulses can be used to observe the breaking of chemical bonds in biochemical reactions and capture the transfer process of electrons in ultrafast physical phenomena. In this paper, the feasibility of ESASE experiments on Shanghai Soft X-ray Free Electron Laser Facility (SXFEL) is theoretically verified. The results show that the ESASE scheme can produce ultrafast light pulses on the order of attosecond, with a peak power of 450 MW. At the same time, the simulation results in this paper verify the feasibility of chirped enhanced SASE schenme based on SXFEL. The results show that compared with the ESASE scheme, the power of the radiation pulse can be greatly improved by this scheme. A relatively low energy electron beam (1.5 GeV) was used to generate about 40 GW of radiation, and the length of the radiation pulse was significantly shortened.

Discrete Wavelet Transformation for the Sensitive Detection of Ultrashort Radiation Pulse with Radiation-induced Acoustics.

Radiation-induced acoustics (RIA) shows promise in advancing radiological imaging and radiotherapy dosimetry methods. However, RIA signals often require extensive averaging to achieve reasonable signal-to-noise ratios, which increases patient radiation exposure and limits real-time applications. Therefore, this paper proposes a discrete wavelet transform (DWT) based filtering approach to denoise the RIA signals and avoid extensive averaging. The algorithm was benchmarked against low-pass filters and tested on various types of RIA sources, including low-energy X-rays, high-energy X-rays, and protons. The proposed method significantly reduced the required averages (1000 times less averaging for low-energy X-ray RIA, 32 times less averaging for high-energy X-ray RIA, and 4 times less averaging for proton RIA) and demonstrated robustness in filtering signals from different sources of radiation. The coif5 wavelet in conjunction with the sqtwolog threshold selection algorithm yielded the best results. The proposed DWT filtering method enables high-quality, automated, and robust filtering of RIA signals, with a performance similar to low-pass filtering, aiding in the clinical translation of radiation-based acoustic imaging for radiology and radiation oncology.

Fully coherent soft X-ray pulse generation based on ERL

Energy recovery linacs (ERLs) possess the bright prospect of fully coherent X-ray generation. Recently, we designed a 600 MeV energy recovery linac capable of producing high power fully coherent radiation pulses at 13.5 nm with a relatively low-intensity 256.5 nm seed laser profiting from the employment of angular-dispersion-induced microbunching (ADM) technology. We also designed a matched multiplexed system that can deflect each radiator by 8 mrad with a carefully choreographed multi-bend achromat (MBA) scheme. As a result of downstream MBA’s dispersion compensation, bunching factors will be enhanced both at the fundamental wavelength and high harmonics. The bunching factor of the 19th harmonic increased from 10% to 26%, and that of the 57th harmonic became 8.4%, which is sufficient to generate fully coherent radiation in the soft X-ray range.

Photon Diagnostics for the High-Gain THz FEL at PITZ

Research and development of an accelerator-based THz source prototype for pump-probe experiments at the European XFEL are ongoing at the Photo Injector Test Facility at DESY in Zeuthen (PITZ). Proof-of-principle experiments have been performed to generate a high-gain THz Free-electron Laser (FEL) based on the Self-Amplified Spontaneous Emission scheme. The FEL radiation pulses with a central wavelength of about 100 μm (3 THz) and single pulse energy of several tens μm can be generated. In this paper, we present and discuss the photon diagnostic setup for the THz FEL together with examples of diagnostic results, including pulse energy and an FEL gain curve. The upgraded photon diagnostic setup, capable of measuring pulse energy, transverse distribution, and spectral distribution, is expected to be operational in the spring of 2023.

Superradiance and solids: Reduced description method

Spontaneous ordering in a system of excited emitters with a powerful short radiation pulse predicted by Dicke attracted the great attention of scientists for decades as a bright example of the nontrivial behavior of a nonequilibrium system. The Bogolyubov reduced description method has some advantages and provides new possibilities in the theoretical investigation of the Dicke process. The paper presents the authors’ results of modeling such processes concerning both optical ones in the presence of crystal lattice influence and acoustic superradiance, which is possible in solids. The right choice of reduced description parameters allows the account of atom motions (phonons), cavity influence, and excitations in the emitter system (excitons) in the electromagnetic radiation process. The mathematical analogy between the Dicke system and a spin system in a magnetic field opens the way to applying the reduced description technique to acoustic phenomena previously investigated with the boson variable elimination method. Such a new approach to superradiance in crystals with paramagnetic impurities and with competing mechanisms of relaxation (Wagner model) is outlined. Acoustic superradiance is discussed in connection with the problem of structural phase transitions.

Design of transient front-end signal digitizer for x-ray detector in laser inertial confinement fusion facility.

In a laser inertial confinement fusion (ICF) facility, an x-ray diode (XRD) detector is mainly used for precise measurement of black cavity radiation flow. The rapid rising time of the XRD detector and the intricate radiation environment of the ICF facility have posed new requirements for the bandwidth and anti-interference performance of signal digitization technologies. The standards are tough for the current recording system to meet. In this paper, based on the anti-interference of digital signals in the radiation field of the ICF facility, we have designed an XRD detector specific transient front-end signal digitizer (TFSD). The digitizer may be put together for consistent shielding in the radiation field since its size matches that of the XRD detector. The test results show that the TFSD has a higher signal input bandwidth than the existing recording method, considerably reduces the effect of pulse radiation field on signal recording, and significantly boosts the accuracy of recording and diagnosis.

Irradiation modes and phase explosion during ablation of steel targets with a scanning beam of pulsed radiation of a nanosecond duration Yb:YAG laser

Irradiation modes and phase explosion during ablation of steel targets with a scanning beam of pulsed radiation of a nanosecond duration Yb:YAG laser

Bright ultraviolet knots as possible sources of coherent microwave radiation

A distinctive feature of the September 6, 2012 event was that sources of narrow-band (2–4 GHz) sub-second pulses (SSP) were observed in small areas of flare loops with so-called bright ultraviolet knots with high plasma density up to 1011 10¹¹ cm⁻³. Time profiles of hard X-rays of the flare, although similar to microwave light curves, do not have structures corresponding to SSP. Analysis of microwave, X-ray, and ultraviolet data has shown that the observable pulses of microwave radiation with a narrow spectral band are coherent in nature and are generated by electrons with energies of several tens of kiloelectronvolt in bright knots at a double plasma frequency. The results of the observations suggest that the appearance of bright knots is associated with local processes of energy release due to interaction of flare loops.

(Invited) Operando Optical Spectroscopy Analyses of Photoelectrochemical Water Oxidation Kinetics

Water oxidation is a key kinetic bottleneck in many photoelectrochemical systems for solar to fuels and chemicals. We have recently been developing an operando optical spectroscopic analysis to assay these reaction kinetics in metal oxide photoanodes. This technique, which we refer to as photoinduced absorption spectroscopy, is based around measuring the optical absorption of oxidising species (‘surface holes’) generated in photoanodes under anodic bias and pulsed (typically 5 s) light irradiation. These analyses have allowed us to observe a non-linear dependence of water oxidation kinetics on surface hole density, most typically a 3rd order rate law dependence under circa 1 sun irradiation conditions. In my talk I will talk about three different applications of this PIAS approach to investigate the function of BiVO4, Fe2O3 and TiO2 photoanodes. Firstly I will discuss how this non-linear dependence can be exploited to determine the photoelectrochemically active surface area of photoanodes as function of metal oxide nanostructuring. I will then go on to demonstrate that, when normalised for matched surface hole densities, water oxidation kinetics measured in under light irradiation or in the dark at strong anodic bias are identical, and discuss how this conclusion can be exploited to quantify the photovoltage under irradiation. Finally I will discuss deviation from rate law behaviour observed under > 1 sun irradiation conditions, and its mechanistic origin.

Fast Cycling Speed with Multimillion Cycling Endurance of Ultra‐Low Loss Phase Change Material (Sb2Se3) by Engineered Laser Pulse Irradiation

AbstractProgrammable and reconfigurable photonics is revolutionized the next generation of Si/SiN‐based photonics processors, optical signal processing, and neural and quantum networks. Ultra‐low loss phase‐change technology has the enormous potential to offer energy‐efficient, extra large‐scale integrated (ELSI) nonvolatile programmable photonics that can overcome the limitations of commonly used volatile and energy‐hungry programmable photonic systems. So far, most of the phase change materials (PCM) devices have already shown to be suitable for programmable and reconfigurable photonic circuit applications that do not require extreme endurance or ultra‐fast switching speeds. However, applications with ultra‐fast speed and multi‐million cycling requirements, such as memory cells, quantum computing, optical displays, and optical modulators necessitate enormous improvements in the existing cycling speed and endurance of PCMs, for high‐performance device configuration. Here, optical switching of an ultra‐low loss PCM (Sb2Se3) is demonstrated with an unprecedented combination of rapid cycling speed (0.6 × 105 cycles s−1) and extreme endurance (> 2 × 106 cycles) that pave the way for ultrafast, large‐scale, programmable, and reconfigurable integrated photonic circuits and devices.

Metal-composite hybrid joint adhesion and testing optimization for electric vehicle applications

ABSTRACT Lightweight is a critical feature in automotive applications, especially in electric vehicle applications due to the heavyweight of batteries, thus contributing to improve vehicle efficiency. Multi-material solutions were studied in this paper as a strategy for lightweighting, focusing on the improvement of metal-composite joints obtained by overmolding through the comparison of different laser treated textures and processing parameters. In addition, testing methods to assess the adhesion of these joints were analysed. Firstly, steel surface treatment was carried out by pulsed laser radiation producing different patterns. Secondly, over injection of the composite material based on polyamide 6.6 with 40% recycled carbon fiber was carried out with different processing parameters. The mechanical performance of the joints was assessed through shear-strength analysis, and the morphological analysis was carried out. As outcome, the optimal combination of surface treatment and processing parameters was selected. Finally, a finite element analysis was carried out to evaluate comparatively the suitability of a testing method proposed as an alternative to the standard single lap shear tests, with a configuration that facilitates the specimens manufacturing and test execution. As a result, the adequacy of the method for the assessment of the shear strength of this type of joints was demonstrated.

Яркие ультрафиолетовые узлы как возможные источники когерентного микроволнового излучения

A distinctive feature of the September 6, 2012 event was that sources of narrow-band (2–4 GHz) sub-second pulses (SSP) were observed in small areas of flare loops with so-called bright ultraviolet knots with high plasma density up to 10¹¹ cm⁻³. Time profiles of hard X-rays of the flare, although similar to microwave light curves, do not have structures corresponding to SSP. Analysis of microwave, X-ray, and ultraviolet data has shown that the observable pulses of microwave radiation with a narrow spectral band are coherent in nature and are generated by electrons with energies of several tens of kiloelectronvolt in bright knots at a double plasma frequency. The results of the observations suggest that the appearance of bright knots is associated with local processes of energy release due to interaction of flare loops.

Jeszcze szybsza lampa błyskowa czyli Nagroda Nobla z fizyki 2023

Nobel Prize in Physics in 2023 was awarded for generation of attosecond (1 as=10−18 s) pulses of electromagnetic radiation and application of attosecond pulses in studies of electrons in condensedmatter. I show basic physicalmechanisms leading to generation of such pulses and methods to measure them. I also show an exemplary application of attosecond pulses - studies dynamic of photo effect.

Solving the spectral gap problem with a four-mirror bow-tie cavity in waveguide free-electron laser oscillators

The generation of intense coherent radiation pulses in the far-infrared and terahertz regimes is of considerable interest to the free-electron laser (FEL) radiation user community. At long wavelengths, the diffraction effect can be quite severe, therefore, an optical waveguide is required to confine the radiation field. However, it will also bring about some new phenomena, and the most noteworthy one is the spectral gap phenomenon: at some particular wavelengths, regardless of electron beam adjustments, the coupling efficiency and output power of waveguide FEL oscillators drop significantly. Such spectral gap has an adverse effect on experimental results since numerous experiments require continuous spectral scanning. In this paper, we propose to utilize a bow-tie cavity instead of conventional cavities to the waveguide FEL to solve the spectral gap problem. The simulation was carried out based on the parameters of FELiChEM, a newly built user facility in China. Numerical simulation code OPC combining with modified GENESIS is used to enable the modelling, for the first time, of a bow-tie cavity based FEL in the far-infrared wavelength regime. The simulation results indicate that this novel structure can effectively eliminate the spectral gaps and substantially enhance long-wavelength laser performance.

Electromagnetic pulse induced blood-brain barrier breakdown through tight junction opening in rats.

The blood-brain barrier (BBB) is the main obstacle to hydrophilic and large molecules to enter the brain, maintaining the stability of the central nervous system (CNS). But many environmental factors may affect the permeability and structure of the BBB. Electromagnetic pulses (EMP) irradiation has been proven to enhance the permeability of the BBB, but the specific mechanism is still unclear. To explore the potential mechanism of EMP-induced BBB opening, this study investigated the permeability, fine structure and the proteins expression of the tight junction (TJ) of the BBB in the rats exposed to EMP. Using the leakage of fluorescein isothiocyanate-labeled dextran with different molecular mass under different field intensity of EMP exposure, we found that the tracer passing through the BBB is size-dependent in the rat exposed to EMP as field intensity increased. Transmission electron microscopy showed TJ of the endothelial cells in the EMP-exposed group was open, compared with the sham-irradiated group. But the levels of TJ proteins including ZO-1, claudin-5, or occludin were not changed as indicated by western blot. These data suggest that EMP induce BBB opening in a field intensity-dependent manner and probably through dysfunction of TJ proteins instead of their expression. Our findings increase the understanding of the mechanism for EMP working on the brain and are helpful for CNS protection against EMP.