Application Of Pulses Research Articles

Laboratory validation of in-pipe pulsed thermography in the rapid assessment of external pipe wall thinning in buried metallic utilities

This study characterized the in-pipe thermal signature of external pipewall thinning in steel pipes, a common problem that is caused by external corrosion in hostile underground environment. A model system was prepared to imitate the underground environment by milling several holes of various sizes and residual thicknesses into a mild steel plate. Wall thinning was investigated using active infrared thermography. The non-defective side of the steel plate was heated to 27.4 °C through the application of a thermal energy pulse while the ambient temperature was 22°C. Thermograms were captured inside the pipe at a frequency of 0.02 seconds for 5 min. The images of the thinned surface were processed in two steps. First, the peak contrast time algorithm was used to estimate the residual thickness. Second, Gaussian adaptive thresholding was used to estimate the size of the holes. The maximum observable defects had a diameter of 5 mm and a residual thickness of 3 mm. The type of defect interface (steel–sand or steel–air) had no significant effect on the estimation of residual thickness or size. This study developed a rapid approach in classifying defect's residual thickness by only utilizing two well-known parameters from infrared images – defect's peak thermal contrast and estimated area. Thus, the feasibility of non-destructive, in-pipe, quantitative IR thermographic analysis of buried metal pipelines is demonstrated.

Topology with Memory in Nonlinear Driven-Dissipative Photonic Lattices

We consider a photonic lattice of nonlinear lossy resonators subjected to a coherent drive, where the system remembers its topological phase. Initially, the system is topologically trivial. After the application of an additional coherent pulse, the intensity is increased, which modifies the couplings in the system and then induces a topological phase transition. However, when the effect of the pulse dies out, the system does not go back to the trivial phase. Instead, it remembers the topological phase and maintains its topology acquired during the pulse application. The pulse can be used as a switch to trigger amplification of the topological modes. We further show that the amplification takes place at a different frequency as well as at a different position from those of the pulse, indicating frequency conversion and intensity transfer. Our work can be useful in triggering the different functionalities of active topological photonic devices.

Reversible total ionizing dose effects in NiO/Ga2O3 heterojunction rectifiers

NiO/Ga2O3 heterojunction rectifiers were exposed to 1 Mrad fluences of Co-60 γ-rays either with or without reverse biases. While there is a small component of Compton electrons (600 keV), generated via the interaction of 1.17 and 1.33 MeV gamma photons with the semiconductor, which in turn can lead to displacement damage, most of the energy is lost to ionization. The effect of the exposure to radiation is a 1000× reduction in forward current and a 100× increase in reverse current in the rectifiers, which is independent of whether the devices were biased during this step. The on–off ratio is also reduced by almost five orders of magnitude. There is a slight reduction in carrier concentration in the Ga2O3 drift region, with an effective carrier removal rate of <4 cm−1. The changes in electrical characteristics are reversible by application of short forward current pulses during repeated measurement of the current–voltage characteristics at room temperature. There are no permanent total ionizing dose effects present in the rectifiers to 1 Mad fluences, which along with their resistance to displacement damage effects indicate that these devices may be well-suited to harsh terrestrial and space radiation applications if appropriate bias sequences are implemented to reverse the radiation-induced changes.

Modification of carrot electric properties by moderate electric pulses

The impedance of carrot (variety Jereda) was analyzed just after the application of a moderate Pulse Electric Field, PEF (one, two, or three pulses of alternative sinusoidal signal with a frequency of 20 kHz). The parameters of a single model - consisting of a resistor and a capacitor in parallel connection were calculated using the measured impedance. During pulse application both the resistance and the capacitance significantly decreased and after the pulse, the capacitance permanently increased to values that were higher than the values determined before the pulse application. The resistance, a few seconds after the pulse, also increased in a period that will be referred, in this paper, as ‘restoration’ as a result of probably restored cellular membranes that were damaged during the previous pulse. The restoration of the resistance can be expressed by at least two exponentials with parameters that sensitively depend either on the pulse level (300–800 V/cm) or on the possible pulse repetition. A few seconds after a pulse, a new period starts, which will be referred here as ‘de-restoration’; it is the period in which the resistance decreases substantially, and the capacitance still increases. • Carrot after-pulse goes through restoration (resistance increase) and de-restoration (resistance decrease) processes. • The after-pulse resistance decrease was observed after pulses with maximum pulse intensity higher than ∼250 V/cm. • Time border between restoration and de-restoration was estimated at few seconds. • The resistance increase in restoration can be approximated by two exponentials.

Preparation and pulsed fiber laser applications of emerging nanostructured materials

This review provides recent advances of preparation and pulsed fiber laser applications of emerging nanostructured materials. The preparation methods and applications of these materials as the saturable absorbers in pulsed fiber lasers are provided.

Generation and application of high-contrast laser pulses using plasma mirror in the SULF-1PW beamline

Generation and application of high-contrast laser pulses using plasma mirror in the SULF-1PW beamline

Effect of electropulsing treatment on the precipitation behavior of MnS in sulfur-containing microalloyed 49MnVS3 steel

An experimental investigation has been conducted with respect to the influence of electropulsing treatment (EPT) on the 2D and 3D morphologies, distribution, number and size of MnS precipitates in the high-sulfur micro-alloyed 49MnVS3 steel. After the application of electric current pulse with a peak pulsed voltage of 30 V, the microstructure was refined due to the increasing nucleation rate of particles in liquid steel. Moreover, compared with the untreated steel with spherical MnS randomly distributed in the matrix, the MnS precipitates moved directionally to aggregate on the bottom and top surfaces of the ingot in order to minimize the free energy of the system in case of EPT. For untreated steel samples, the number of MnS was 409 (bottom), 579 (middle) and 437 (top), while that of the treated samples were 226 (bottom), 38 (middle) and 224 (top) in the scanning area of 2.65 × 107 µm2 with ASPEX. The number of MnS with small size decreased while the large-size MnS increased with the application of EPT.

Ab initio simulations of ultrashort laser pulse interaction with Cl-Si(100): implications for atomic layer etching.

Due to the remarkable resistance of SiCl against photo-induced desorption, achieving atomic layer etching (ALE) of Cl-Si(100) through a laser-based method has remained a formidable challenge. In this study, we investigate the interaction between ultrashort laser pulses and the Cl-Si(100) surface via ab initio simulations that combine real-time time-dependent density functional theory and molecular dynamics. Our results demonstrate the direct desorption of the stubborn SiCl layer through the application of appropriate femtosecond laser pulses. Notably, the desorption process is enhanced by pulses with higher laser intensity, shorter wavelength, and longer pulse duration. There is a threshold intensity beyond which the SiCl can be directly desorbed under laser pulses with a wavelength of 488 nm and a pulse duration of 40 ℏ eV-1 (26.3 fs). Analysis of electron localization function reveals a critical bond breaking length of 2.98 Å between Si-Si, connecting SiCl to the bulk material. The time evolution of bond lengths and forces reveals that the desorption of SiCl is primarily driven by repulsive forces generated within the Si-Si bond. Furthermore, electron density difference analysis and Keldysh factor calculations indicate that these repulsive forces arise from multiphoton ionization. This study provides crucial atomic-level insights into the interaction of ultrashort laser pulses with Cl-Si(100), thereby propelling the advancement of laser-induced atomic layer etching techniques.

The structure of tick-borne encephalitis virus determined at X-ray free-electron lasers. Simulations.

The study of virus structures by X-ray free-electron lasers (XFELs) has attracted increased attention in recent decades. Such experiments are based on the collection of 2D diffraction patterns measured at the detector following the application of femtosecond X-ray pulses to biological samples. To prepare an experiment at the European XFEL, the diffraction data for the tick-borne encephalitis virus (TBEV) was simulated with different parameters and the optimal values were identified. Following the necessary steps of a well established data-processing pipeline, the structure of TBEV was obtained. In the structure determination presented, a priori knowledge of the simulated virusorientations was used. The efficiency of the proposed pipeline was demonstrated.

Development of attosecond pulses and their application to ultrafast dynamics of atoms and molecules

In the past two decades, the development of laser technology has made attosecond science become a cutting-edge research field, providing various novel perspectives for the study of quantum few-body ultrafast evolution. At present, the attosecond pulses prepared in laboratories are widely used in experimental research in the form of isolated pulses or pulse trains. The ultrafast changing light field allows one to control and track the motions of electrons on an atomic scale, and realize the real-time tracking of electron dynamics on a sub-femtosecond time scale. This review focuses on the research progress of ultrafast dynamics of atoms and molecules, which is an important part of attosecond science. Firstly, the generation and development of attosecond pulses are reviewed, mainly including the principle of high-order harmonic and the separation method of single-attosecond pulses. Then the applications of attosecond pulses are systematically introduced, including photo-ionization time delay, attosecond charge migration, and non-adiabatic molecular dynamics. Finally, the summary and outlook of the application of attosecond pulses are presented.

An electric-field-driven ferroelectric nanodomain structure and its multilevel data storage application.

Solid-state multilevel data storage devices based on ferroelectric materials possess significant potential for use as artificial synapses in building biomimetic neural networks with low energy consumption and efficient data processing capabilities. To enable multilevel data storage, precise control of the ferroelectric domain through voltage pulses is essential. In this study, we investigate the manipulation of ferroelectric nanodomain structures using a nanotip and demonstrate their evolution under controlled application of electric pulses with varying strength and duration. The results highlight the differences in electric-field-driven ferroelectric nanodomain structures between (001)-/(101)- and (111)-oriented PbZr0.2Ti0.8O3 thin films. Interestingly, the latter exhibits highly anisotropic domain wall motion characteristics. The (111)-oriented PbZr0.2Ti0.8O3/SrRuO3 heterostructure demonstrates the best performance in increasing the domain radius with respect to electric pulse strength and duration. It shows at least three resistance states with a high switching ratio, making it a promising candidate for multilevel data storage applications. Additionally, the self-reversal rates of upward and downward domains differ and must be considered in designing and implementing multilevel data storage systems for stability and effectiveness. These findings reveal the potential of ferroelectric nanodomain structures for data storage and pave the way for nanotip-controlled artificial synapses.

Superior Energy Storage Capability and Stability in Lead-Free Relaxors for Dielectric Capacitors Utilizing Nanoscale Polarization Heterogeneous Regions.

The development of high-performance lead-free dielectric ceramic capacitors is essential in the field of advanced electronics and electrical power systems. A huge challenge, however, is how to simultaneously realize large recoverable energy density (Wrec ), ultrahigh efficiency (η), and satisfactory temperature stability to effectuate next-generation high/pulsed power capacitors applications. Here, a strategy of utilizing nanoscale polarization heterogeneous regions is demonstrated for high-performance dielectric capacitors, showing comprehensive properties of large Wrec (≈6.39 J cm-3 ) and ultrahigh η (≈94.4%) at 700 kV cm-1 accompanied by excellent thermal endurance (20-160 °C), frequency stability (5-200 Hz), cycling reliability (1-105 cycles) at 500 kV cm-1 , and superior charging-discharging performance (discharge rate t0.9 ≈ 28.4 ns, power density PD ≈161.3 MW cm-3 ). The observations reveal that constructing the polarization heterogeneous regions in a linear dielectric to form novel relaxor ferroelectrics produces favorable microstructural characters, including extremely small polar nanoregions with high dynamics and multiphase coexistence and stable local structure symmetry, which enables large breakdown strength and ultralow polarization switching hysteresis, hence synergistically contributing to high-efficient capacitive energy storage. This study thus opens up a novel strategy to design lead-free dielectrics with comprehensive high-efficient energy storage performance for advanced pulsed power capacitors applications.

Ga-Sn-O Thin-Film Memristor and Analog Plasticity Characteristic

A Ga-Sn-O (GTO) thin-film memristor has been developed, and an analog plasticity characteristic has been observed. First, GTO thin-film memristors are fabricated by depositing three GTO layers in a stacked structure using sputtering. Next, the current-voltage characteristics are measured by varying the maximum applied voltage after a certain negative voltage, the hysteresis is observed, and the switching characteristics are evaluated, which is regarded as that an analog plasticity characteristic is observed. The parametric study is done for the stacked structure and deposition process, and the proposed operating mechanism is that oxygen vacancies reciprocate by applying negative and positive voltages. Finally, the pulse application characteristic shows the long-term potentiation and depression, which presents a practical possibility to utilize the GTO thin-film memristor for neuromorphic systems.

High Intensity Pulsed Magnetic Field Application in Patients with Chronic Prostatitis Complicated by Erectile Dysfunction: а Randomized Prospective Study

INTRODUCTION. Chronic prostatitis is one of the most common urological nosologies, the third most common diagnosis in men under 50 years old. Existing scientific sources testify to the effectiveness of various physiotherapeutic interventions in patients with infectious-inflammatory diseases of the male reproductive system, complicated by erectile dysfunction. AIM. The aim of the study was the scientific substantiation of high-intensity pulsed magnetic field application in patients with chronic prostatitis complicated by erectile dysfunction. MATERIAL AND METHODS. The study included 60 patients randomized into two groups. The first group (30 people) received high-intensity pulsed magnetic field; the second group (30 people) received drug therapy. RESULTS AND DISCUSSION. It was shown that the high clinical results of high-intensity pulsed magnetic field application were based on the compensation of local blood circulation conditioned by the improvement of the prostate blood flow according to the ultrasound of the prostatic vessels as well as by the elimination of the penile blood supply deficiency due to the improvement of the arterial vessels tone and elimination of venous stasis according to laser doppler flowmetry. CONCLUSION. An innovative method has been developed to treat patients with chronic prostatitis complicated by erectile dysfunction using high-intensity pulsed magnetic field.

Giant saturation absorption of tungsten trioxide film prepared based on the seedless layer hydrothermal method

Nonlinear materials have gained wide interest as saturable absorbers and pulse compression for pulsed laser applications due to their unique optical properties. This work investigates the third-order nonlinear phenomenon of tungsten trioxide (WO3) thin films. The giant nonlinear absorption and nonlinear refractive index of WO3 thin films were characterized by Z-scan method at 800 nm. We experimentally observed the giant saturable absorption (SA) and nonlinear refractive index of WO3 thin films prepared by the seedless layer hydrothermal method, with SA coefficient being as high as –2.59 × 105 cm⋅GW−1. The SA coefficient is at least one order of magnitude larger than those of the conventional semiconductors. The nonlinear refractive index n 2 of WO3 film has been observed for the first time in recent studies and the corresponding coefficient can be up to 1.793 cm2⋅GW−1. The large third-order nonlinear optical (NLO) response enables WO3 thin films to be promising candidates for optoelectronic and photonic applications in the near-infrared domain.

Energy Storage Properties of Sol-Gel-Processed SrTiO3 Films.

Dielectric films with a high energy storage density and a large breakdown strength are promising material candidates for pulsed power electrical and electronic applications. Perovskite-type dielectric SrTiO3 (STO) has demonstrated interesting properties desirable for capacitive energy storage, including a high dielectric constant, a wide bandgap and a size-induced paraelectric-to-ferroelectric transition. To pave a way toward large-scale production, STO film capacitors were deposited on Pt(111)/Ti/SiO2/Si(100) substrates by the sol-gel method in this paper, and their electrical properties including the energy storage performance were studied as a function of the annealing temperature in the postgrowth rapid thermal annealing (RTA) process. The appearance of a ferroelectric phase at a high annealing temperature of 750 °C was revealed by X-ray diffraction and electrical characterizations (ferroelectric P-E loop). However, this high dielectric constant phase came at the cost of a low breakdown strength and a large hysteresis loss, which are not desirable for the energy storage application. On the other hand, when the RTA process was performed at a low temperature of 550 °C, a poorly crystallized perovskite phase together with a substantial amount of impurity phases appeared, resulting in a low breakdown strength as well as a very low dielectric constant. It is revealed that the best energy storage performance, which corresponds to a large breakdown strength and a medium dielectric constant, is achieved in STO films annealed at 650 °C, which showed a large energy density of 55 J/cm3 and an outstanding energy efficiency of 94.7% (@ 6.5 MV/cm). These findings lay out the foundation for processing high-quality STO film capacitors via the manufacturing-friendly sol-gel method.

Evaluation of Arc Signals, Microstructure and Mechanical Properties in Ultrasonic-Frequency Pulse Underwater Wet Welding Process with Q345 Steel

The ultrasonic-frequency pulse underwater wet welding (UFP-UWW) process was achieved through a constant-voltage-mode power source connecting an ultrasonic-frequency pulse power source in parallel. The arc voltage and welding current waveforms, sound signal variations, microstructural characteristics and mechanical properties at different parameters were investigated. The results showed that the ultrasonic-frequency pulse voltage and current of the UFP-UWW process displayed a periodic high-frequency oscillation on the based values of the conventional UWW process. The arc stability of the UFP-UWW process improved owing to the fact that the proportions of the unstable arc burning region could be reduced to 1.56% after the introduction of the ultrasonic-frequency pulse current. No significant changes in weld width and penetration were observed while the weld dilution rate increased to 54.2% for the combination of 40 V–30 kHz, compared with the results of the conventional UWW process. The flux-cored arc (FCA) welding arc in the air had the same frequency response to the ultrasonic excitation signal, which verified the existence of the ultrasonic-frequency vibration induced by the periodic high-frequency electromagnetic forces. The application of the ultrasonic-frequency pulse produced finer columnar grains in the welds with an average length of 315 μm, although the amount of pro-eutectoid ferrite and acicular ferrite varied little. The mechanical properties of the welded joints were also noticeably enhanced with the application of different ultrasonic excitation frequencies. The optimum tensile strength and impact toughness of the welded joint were improved by 6.7% and 21.7% when the applied ultrasonic excitation voltage was 40 V for a pulsed frequency of 30 kHz. These results facilitate the application of ultrasonic arc welding technology in the marine field.

Hyperthermia Prevents In Vitro and In Vivo Biofilm Formation on Endotracheal Tubes.

There is currently an urgent need to find new strategies to tackle antimicrobial resistance and biofilm-related infections. This study has two aims. First, we evaluated the in vitro efficacy of hyperthermia in preventing biofilm formation on the surfaces of polyvinyl chloride discs. Second, we assessed the in vivo efficacy of hyperthermia in preventing biofilm formation in endotracheal tubes (ETTs) of a rabbit model. For the in vitro studies, nine clinical extensively drug-resistant/multidrug-resistant Gram-negative isolates of Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa and three clinical methicillin-resistant Staphylococcus aureus strains were studied. For biofilm formation, an adhesion step of 30 or 90 min followed by a growth step of 24 h were performed with application of one, two, and three pulses at 42°C for 15 min each pulse after the adhesion step. For the in vivo studies, New Zealand rabbits were intubated with ETTs previously colonized with K. pneumoniae or P. aeruginosa strains, and three pulses at 42°C for 15 min were applied after the adhesion step. The application of three pulses at 42°C for 15 min each pulse was needed to achieve the prevention of the in vitro biofilm formation of 100% of the tested strains. The application of heat pulses in a rabbit intubation model led to biofilm prevention of 85% against two K. pneumoniae strains and 80% against two P. aeruginosa strains compared to the control group. Hyperthermia application through pulses at 42°C could be a new nonantibiotic strategy to prevent biofilm formation in ETTs. IMPORTANCE Biofilm-producing microorganisms are considered medically crucial since they cause 80% of the infections that occur in the human body. Medical devices such as endotracheal tubes (ETTs) can act as a reservoir for pathogens providing the surface to which microorganisms can adhere and cause biofilm-associated infections in critically ill patients. This biofilm has been related with the development of ventilator-associated pneumonia (VAP), with an incidence of 8 to 28%, a mortality rate up to 17% and its associated high extra costs. Although some VAP-preventive measures have been reported, they have not demonstrated a significant reduction of VAP incidence. Therefore, we present a new nonantibiotic strategy based on hyperthermia application to prevent biofilm formation inside ETTs. This technology could reduce VAP incidence, intubation duration, hospital and intensive care unit (ICU) length stays, and mortality rates. Consequently, this could decrease the antibiotics administered and influence the impact of antibiotic resistance in the ICU.

Electric charge build-up and dissipation at pulsed streamer corona by EFISH and probe measurements

This work examines the dynamics of volumetric electric charge deposited by a single pin electrode streamer corona in atmospheric air at ambient conditions. Recent studies show that, at pulse-periodic operation, electric charge remains in surrounding air after the first discharge. This residual charge significantly affects the electric field distribution and morphology of discharges at subsequent pulses. In this study, the residual electrical potential/field was measured during and after dissipation of a pulsed 80 kV streamer corona of alternating polarity. This was accomplished using electrostatic probes and the electric field induced second harmonic method (EFISH generation). The residual volumetric charge of a positive pulse polarity streamer corona occupies a zone of up to 80 mm from the electrode. The subsequent application of a negative polarity pulse leads to partial neutralization of the previous charge and the generation of a region with a high-amplitude electric field. The propagation of following positive polarity pulses is limited by the residual positive volumetric charge. The EFISH method reveals the magnitude of the electric field at discharge propagation and electrostatic probes inform the polarity. Intensified imaging acquisition was used to evaluate the spatial distribution and dynamics of corona discharge during the alternating polarity waveform.

Detection of molecular transitions with nitrogen-vacancy centers and electron-spin labels

We present a protocol that detects molecular conformational changes with two nitroxide electron-spin labels and a nitrogen-vacancy (NV) center in diamond. More specifically, we demonstrate that the NV can detect energy shifts induced by the coupling between electron-spin labels. The protocol relies on the judicious application of microwave and radiofrequency pulses in a range of parameters that ensures stable nitroxide resonances. Furthermore, we demonstrate that our scheme is optimized by using nitroxides with distinct nitrogen isotopes. We develop a simple theoretical model that we combine with Bayesian inference techniques to demonstrate that our method enables the detection of conformational changes in ambient conditions including strong NV dephasing rates as a consequence of the diamond surface proximity and nitroxide thermalization mechanisms. Finally, we counter-intuitively show that with our method the small residual effect of random molecular tumbling becomes a resource that can be exploited to extract inter-label distances.