Typical Pulse Research Articles

An elaborative discussion on the potentiality, functional characteristics, curative effects, antinutritional factors, processing, and industrial applications of faba beans (Vicia faba L.) as a versatile legume

SummaryGlobally, 60% of protein consumption comes from plant‐based sources. By exploring the potential of plant‐based proteins and incorporating them into diverse food options, we can not only enhance the sustainability of our food systems but also contribute to a more balanced and environmentally conscious society. Due to the limited availability of conventional food proteins, there has been a persistent exploration for alternative legume sources for addressing the need for protein‐based foods. Faba bean is a type of pulse that stands out among other legumes due to its high protein content (26.1%) and dietary fibre (25.0%). Faba beans and their derivatives have been suggested as potentially beneficial foods for individuals with diabetes and hypertension. However, faba beans contain some antinutritional factors (ANFs). These antinutrients can have adverse effects on digestion and nutrient absorption. Various strategies like thermal and non‐thermal processing methods have been employed to reduce the ANF content and improve nutritional functionality in faba beans. The applications of faba beans and their potential as replacements for traditional ingredients in various food products are described. By utilising processed fava bean products, novel food formulations and applications can be created, catering to the growing demand for healthier and functional food options.

GENERATION OF RECTANGULAR NANOSECOND ELECTROMAGNETIC PULSES WITH A PICOSECONDS RISE FRONT

A method for generation of ultra-wideband electromagnetic pulses with a nanosecond duration and a picosecond rise time has been studied. The emitter is a horn antenna with a photoconductive switch irradiated by laser pulses. It has been shown that the duration of ultra-wideband electromagnetic pulses is determined by the length of the antenna and the semiconductor material, and the rising front is determined by the front of the laser pulses used to initiate the photoconductive switch. The work shows typical pulse durations of ~1 ns with a rising edge of up to ~34 ps.

Building ultra-thin Inconel 718 sheet joints using low-frequency PLBW scheme: Weld bead quality, keyhole dynamics, and solidification characteristics

Low-frequency pulsed laser beam welding (PLBW) was employed in building 0.32 mm-thick Inconel 718 superalloy butt joints which are frequently applied in manufacturing high-temperature functional units in the aviation industry. Several process parameter combinations concerning peak laser power, welding speed, and pulse frequency were implemented to explore the macro morphology, microstructure, and mechanical properties of the welded joints. Examinations exhibit that the resulting weld beads possess high continuity at the surface with an overlap factor ranging from 0.58 to 0.73. The cross-sectional profile changes from a V-shape to an H-shape with increasing heat input. Finer grain structures composed of γ matrix and γ/Laves eutectic penetration are observed within the FZ center, as compared to that near the fusion line. Excellent performance is achieved in microhardness and tensile tests. Numerical simulation based on an integrated mathematic model reveals periodic keyhole and weld pool dynamics depending on the pulsing laser power. During a typical pulse interval, keyhole geometry collapses within a fraction of a millisecond, leading to a sharp cooling stage at ∼4 × 106 K/s, and then, the melt cools due to the thermal convection with a normal cooling rate of 105 K/s. The full growth of the adjacent weld spot results in the secondary melting zone (SMZ), wherein the columnar dendrites can be refined mainly due to the heterogeneous nucleation as compared to the primary melting zone (PMZ).

Exploring the nutritional and health benefits of pulses from the Indian Himalayan region: A glimpse into the region's rich agricultural heritage.

Pulses have been consumed worldwide for over 10 centuries and are currently among the most widely used foods. They are not economically important, but also nutritionally beneficial as they constitute a good source of protein, fibre, vitamins and minerals such as iron, zinc, folate and magnesium. Pulses, but particularly species such as Macrotyloma uniflorum, Phaseolus vulgaris L., Glycine max L. and Vigna umbellate, are essential ingredients of the local diet in the Indian Himalayan Region (IHR). Consuming pulses can have a favourable effect on cardiovascular health as they improve serum lipid profiles, reduce blood pressure, decrease platelet activity, regulate blood glucose and insulin levels, and reduce inflammation. Although pulses also contain anti-nutritional compounds such as phytates, lectins or enzyme inhibitors, their deleterious effects can be lessened by using effective processing and cooking methods. Despite their great potential, however, the use of some pulses is confined to IHR regions. This comprehensive review discusses the state of the art in available knowledge about various types of pulses grown in IHR in terms of chemical and nutritional properties, health effects, accessibility, and agricultural productivity.

Distinguishing the nonlinear propagation regimes of vortex femtosecond pulses in fused silica by evaluating the broadened spectrum.

The nonlinear propagation dynamics of vortex femtosecond laser pulses in optical media is a topic with significant importance in various fields, such as nonlinear optics, micromachining, light bullet generation, vortex air lasing, air waveguide and supercontinuum generation. However, how to distinguish the various regimes of nonlinear propagation of vortex femtosecond pulses remains challenging. This study presents a simple method for distinguishing the regimes of nonlinear propagation of femtosecond pulses in fused silica by evaluating the broadening of the laser spectrum as the input pulse power gradually increases. The linear, self-focusing and mature filamentation regimes for Gaussian and vortex femtosecond pulses in fused silica are distinguished. The critical powers for self-focusing and mature filamentation of both types of laser pulses are obtained. Our work provides a rapid and convenient method for distinguishing different regimes of nonlinear propagation and determining the critical powers for self-focusing and mature filamentation of Gaussian and structured laser pulses in optical media.

Acinetobacter baumannii IC2 and IC5 Isolates with Co-Existing blaOXA-143-like and blaOXA-72 and Exhibiting Strong Biofilm Formation in a Mexican Hospital.

Acinetobacter baumannii is an opportunistic pathogen responsible for healthcare-associated infections (HAIs) and outbreaks. Antimicrobial resistance mechanisms and virulence factors allow it to survive and spread in the hospital environment. However, the molecular mechanisms of these traits and their association with international clones are frequently unknown in low- and middle-income countries. Here, we analyze the phenotype and genotype of seventy-six HAIs and outbreak-causing A. baumannii isolates from a Mexican hospital over ten years, with special attention to the carbapenem resistome and biofilm formation. The isolates belonged to the global international clone (IC) 2 and the Latin America endemic IC5 and were predominantly extensively drug-resistant (XDR). Oxacillinases were identified as a common source of carbapenem resistance. We noted the presence of the blaOXA-143-like family (not previously described in Mexico), the blaOXA-72 and the blaOXA-398 found in both ICs. A low prevalence of efflux pump overexpression activity associated with carbapenem resistance was observed. Finally, strong biofilm formation was found, and significant biofilm-related genes were identified, including bfmRS, csuA/BABCDE, pgaABCD and ompA. This study provides a comprehensive profile of the carbapenem resistome of A. baumannii isolates belonging to the same pulse type, along with their significant biofilm formation capacity. Furthermore, it contributes to a better understanding of their role in the recurrence of infection and the endemicity of these isolates in a Mexican hospital.

Global strong solutions of 3D compressible Navier–Stokes equations with short pulse type initial data

Global strong solutions of 3D compressible Navier–Stokes equations with short pulse type initial data

A BaGa4Se7 crystal based pulsed mid-infrared light source with a narrow linewidth in 4-12 µm.

We present a BaGa4Se7 (BGSe) crystal based coherent pulsed light source for high resolution mid-infrared (MIR) spectroscopy in the 4-12 µm region. The all-solid-state system consists of an injection seeded optical parametric generator (OPG) and an optical parametric amplifier (OPA) using two KTiOPO4 crystals. The idler output of OPG-OPA and the fundamental output (1064nm) of a wavelength stabilized Nd:YAG laser are employed for difference frequency generation of MIR pulses in the BGSe crystal. Pulsed MIR radiation in the 4-12 µm range is obtained with typical pulse energies higher than 100 µJ and pulse durations of ∼5ns. By measuring H2O absorption lines in the 8 µm region with this MIR light source and a cavity ring-down spectrometer, the linewidth of the MIR source is inferred as 120 ± 10MHz, which is very close to the Fourier-transform limited linewidth of 5ns laser pulses.

Influence of germination and pulse type on texture of high moisture meat analogs

Enhancing the texture profile of high moisture meat analogs (HMMAs) presents a notable challenge, one that can potentially be addressed by diversifying the ingredients used. This research examines how the type of pulse - specifically peas and lentils - and the germination process can impact the functional properties and structural transformation of proteins within these ingredients. A twin-screw extrusion cooking process was used to produce HMMAs with an optimized screw speed of 800 rpm and a final zone temperature of 140 °C. The quality of the HMMAs was evaluated through an analysis of their textural properties and Scanning Electron Microscopy (SEM). Generally, germination and variations in pulse types were seen to create significant (p < 0.05) changes to the protein profile. These changes resulted in reduced subunit molecular weight, altered melting temperatures (120–127 °C), and increased quantities of disulfide bonds. In turn, these shifts elicited corresponding adjustments in the HMMAs when subjected to identical extrusion conditions. Notably, the protein-rich fraction derived from lentils was markedly different (p < 0.05) from that of peas, contributing to lower levels of cohesiveness, chewiness, and gumminess in HMMAs. SEM images taken at 250 × -1000 × magnification demonstrated filaments in HMMAs, illustrating the transformation of proteins from a globular to a fibrous form. Guided by the influence of melting temperature and shear force on pulse protein, the “Thermo-shear Protein Structuring Principle” was proposed. Overall, our findings offer critical insights into how germination and pulse selection can affect protein behavior during the production of HMMAs.

Passively Q-switched mode-locking Er-doped fiber laser with tunable wavelength and pulsating soliton

A passively Q-switched mode-locking erbium-doped fiber laser with tunable wavelength and pulsating soliton is demonstrated. The polarization-maintaining erbium-doped fiber, working as the gain medium, combines with nonlinear polarization rotation to form a Lyot filter in the cavity. A tapered fiber is placed between two polarization controllers to cause a significant insertion loss in the optical path, which makes it easy to generate Q-switched mode-locking (QML) pulses. The wavelength tunable QML laser is implemented simply and easily, and the tunable wavelength ranged from 1528.05 nm to 1569.55 nm, as large as 41.5 nm. In addition, a new type of QML pulse involving pulsating soliton has been discovered in the laser, which was called Q-switched harmonic mode-locking pulsating soliton (QHML-PS). We find that the harmonic order and repetition frequency increases with the rising of the pump power. Our work has tremendous significance for expanding the research and application of emerging QML fiber lasers.

Enhancement of LIBS signal in lithium solution at the interface between liquid and an aluminum substrate

Detecting lithium (Li) in seawater in situ is of great significance for searching deep-sea hydrothermal activities and prospecting oceanic lithium reservoirs. Underwater LIBS (Laser-induced breakdown spectroscopy) has been proven to be an attractive technique for in situ element analysis, but its detecting sensitivity is still hard to satisfy the needs of less rich element analysis. Here, we propose an effective approach to enhance the LIBS signal of Li in bulk water with an immersed metal Al substrate. In this work, a laser beam focused on the substrate's surface with focal offsets between −2.5 mm to 1.5 mm from the surface. A 24 times enhancement factor of the Li signal was achieved with a typical pulse energy of 22 mJ at the optimal focal offset of −0.5 mm. The required minimum pulse energy for 100% breakdown was reduced by 5 times, and the plasma lifetime was 3 times longer, compared with the case without substrate assistance. The quantitative results show that both the LOD and analytical prediction capability of Li can be improved by twice compared to the direct measurement. Moreover, using the background as an internal reference, the average RSD at different concentrations can be further reduced from 45% to 18%. This study not only demonstrates the existence of a spectral enhancement effect at the liquid-solid interface of underwater LIBS, but also reveals an easy-to-implement signal enhancement method for upgrading the development of underwater in situ LIBS sensors.

Build-up dynamics of different pulse types in a dispersion-managed Yb-doped fibre laser

We present a dispersion-managed mode-locked ytterbium fibre laser based on the nonlinear polarization evolution technique. Four single-pulse states could be generated by changing group delay dispersion values from anomalous (−0.0038 ps2) to normal (0.051 ps2) with a grating pair. In the normal dispersion regime, the pulse width was gradually decreased with the decrease of the net dispersion. In the anomalous dispersion region, the typical soliton was obtained, which time-bandwidth product could be calculated as 0.526. In addition, the dynamics of four states were also investigated by using the dispersive Fourier transformation technique. Different pulse evolution dynamics were observed from chaotic state to mode-locking.

Energy transfer from ultrashort electromagnetic pulses to a medium: From micro to macro description

It is shown that a consistent microscopic quantum approach for describing the interaction of ultrashort electromagnetic pulses with matter, developed earlier by the author in the paper [1], leads to the well-known macroscopic formula for the dissipation of the energy of a non-monochromatic field in a medium. This formula is used to study the features of energy transfer from various types of ultrashort pulses both with and without carrier frequency to a solid target.

Coherence Deterioration in Ultrafast Fiber Lasers Mode-Locked by Nonlinear Polarization Rotation

Ultrafast lasers based on nonlinear polarization rotation has attracted significant attentions, where artificial saturable absorption is induced by Kerr effect. Due to polarization-dependent device within, nonlinear polarization rotation laser cavity generally operates in scalar regime, while vector dynamics have been observed occasionally. However, coherence deterioration induced by nonlinear polarization evolution are rarely reported. Here, we investigate the coherence deterioration for the ultrafast laser systems based on nonlinear polarization rotation. Three types of vector pulses, group velocity locked vector solitons, polarization rotation vector solitons, and coherence deteriorated states can be generated by finely tuning the birefringence of cavity. Combining dispersive Fourier transform and division-of-amplitude facilitates single-shot measurements of wavelength-resolved states of polarization. We find that birefringence-induced phase shift promotes the wavelength-dependent polarization rotation and various polarization evolution speed. In the coherence deteriorated states, optical polarization rogue waves at certain wavelengths are identified, while optical intensities show different irregular probability distributions.

Pulse-like ground motion observed during the 6 February 2023 MW7.8 Pazarcık Earthquake (Kahramanmaraş, SE Türkiye)

In this study, we analyzed 100 three-component strong ground motion records observed within 200 km of the causative fault of the 6 February 2023 MW7.8 Pazarcık (Kahramanmaraş) Earthquake in SE Türkiye. The wavelet method was utilized to identify and analyze the characteristics of pulse-like ground motions in the near-fault region, while considering the uncertainty of the pulse orientation during the analysis. Our investigation focused on the effects of the focal mechanism and rupture process on the spatial distribution, pulse orientation, and maximum pulse direction of the observed pulse-like ground motion. We also analyzed the amplitude and period of the observed ground pulses and the effect of long-period amplification on the ground motion response spectra. Our results indicated the following: (1) A total of 21 typical ground velocity pulses were observed during this earthquake, exhibiting complex characteristics due to the influence of the strike-slip mechanism and rupture directivity. Most ground pulses (17 out of 21) were recorded within 20 km of the fault, in a wide range of orientations, including normal and parallel to the fault direction. The waveforms exhibited unidirectional features, indicating the effects of left-lateral fault slip. Distinct pulses observed more than 20 km from the fault were mainly oriented normal to the fault. The waveforms were bidirectional with double- or multi-round trips as a result of rupture directivity. (2) The amplitudes of the observed pulses ranged from 30.5 to 220.0 cm/s, with the largest peak velocity of 220.0 cm/s observed at Station 3138. The pulse periods ranged from 2.3 to 14.5 s, with the longest pulse period of 14.5 s observed at Station 3116. The amplitude and period of the pulses observed during this earthquake were comparable to those of similar-magnitude global earthquakes. The amplitude of the pulses decreased significantly with increasing fault distance, whereas the pulse period was not significantly affected by the fault distance. (3) Compared with non-pulse records, the velocity pulse records had a pronounced amplification effect on the acceleration response spectra near the pulse period, with factors ranging from 2.1 to 5.8. The larger velocity pulses also significantly amplified the velocity response spectra, particularly over the long periods. This significant amplification effect of the pulses on the response spectra leads to empirical models underestimating the long-period earthquake ground motion.

Real-time observation of stationary and pulsating noise-like vector pulses in a fiber laser.

Rapid progress in real-time measurement technology has uncovered varieties of transient pulse dynamics. Here, we report the vector nature of noise-like pulse (NLP) in a passive fiber laser based on the nonlinear optical loop mirror (NOLM) as the polarization independent saturable absorber. After achieving the basic operation regime of NLP, various types of vector pulses, namely, the polarization locked noise-like vector pulse (PLNLVP), the group velocity locked noise-like vector pulse (GVLNLVP), and the transitional state of combined characteristics of GVLNLVP and polarization rotation noise-like vector pulse (PRNLVP) are also obtained in the cavity. Besides, by utilizing the Dispersive Fourier transform (DFT) technique, the spectral evolution and the energy vibration of pulsating PLNLVP, GVLNLVP, and the transitional state of combined characteristics of GVLNLVP and PRNLVP are also analyzed in real time. Particularly, the coexisting pulsation vector state of NLP and soliton is also captured. All these findings will help to complement our understanding of noise-like vector pulses (NLVPs) in a fiber laser.

Laboratory Tests of the Resistance of an Unmanned Aerial Vehicle to the Normalized near Lightning Electrical Component

This article describes a method of immunity testing for commercial unmanned aircraft vehicles relative to a variable near-lightning electric field component. The research focuses on one of the components of the electromagnetic field generated during a lightning discharge: the electrical component. Studies are proposed showing the influence of only this one factor on overvoltages arising in the drone. So far, no one has analyzed such an impact from emerging disturbances, because previous studies in the area have largely considered the impact of the entire electromagnetic field. This is justified practically, but not scientifically—it is necessary to determine the impact of each component separately. Selected electronic components are tested here. For that purpose, two types of pulses are used: Wave Form 4 (WF4–6.4/69 μs from DO-160 standard) and Voltage waveform 1.2/50 μs (PN-EN 61000-4-5:2014-10). The testing object is centrally placed in a capacitor between two parallel plates of dimensions 2 m by 2 m to provide a homogeneous electric field. The results (from a Rigol 1054Z oscilloscope) are saved in *.CSV files (for further analysis). The research shows that the greatest overvoltages are in active parts of the drone (higher-than-supply voltage level), such as the RF antenna or semiconductors. This emphasizes the need to pay special attention to the protection of these elements against a pulsed electromagnetic field, especially the electric component (e.g., lightning discharge).

Mechanical and Sensory Properties of Pulse Gels in the Development of New Plant Based Food

The shift towards healthier and sustainable food consumption requires a greater variety of plant-based products. This study aimed to determine how the mechanical and sensory properties of three different pulse gels (chickpea, lentil, or red lentil flour) vary with the ingredients (flour, oil, lemon, and salt content). All pulse flours were able to form self-standing gels. Mechanical properties varied with the pulse type and with the formulation differently depending on the pulse. For all pulses, the hardness and stiffness increased with the flour content and decreased with salt. They decreased with lemon in chickpea gels and increased with oil content in the red lentil gel. The Flash Profile technique provided distinctive sensory characteristics of each pulse gel. The red lentil gels were homogeneous, creamy, and compact. The chickpea gels were also compact, but harder. Lentil flour resulted in rough and sandy gels. For the three pulses, including oil and lemon reduced pulse flavors and increased sour taste. The results of this study give insights into the suitability of pulse gels to be the basis of new solid plant-based products whose sensory properties can be modulated by varying the concentration of natural ingredients.

Effect of discharge parameters on electric-spark deposition material transfer

In order to study the influence of discharge parameters on the electric spark deposition process, an automatic electric spark deposition device is built by a closed-loop control system of discharge parameters. An automatic electric spark deposition test is carried out at different control voltages. By analyzing the effective discharge waveform parameters, transfer efficiency, deposition efficiency, contact force in the deposition process, surface morphology, and cross-sectional morphology of the deposition layer under different control voltages, etc. Analysis of the results shows that changing the control voltage has a direct effect on the number of discharge types in the deposition process. With the appropriate control voltage, better transfer efficiency and deposition quality can be achieved. Contact discharge has a greater effect on material transfer efficiency than other types of discharge. The transfer of the electrode to the material on the workpiece is mainly achieved by contact discharge. Automatic control of discharge parameters can also be applied to automatic control of discharge pulse types.

Two types of ultrafast mode-locking operations from an Er-doped fiber laser based on germanene nanosheets

As a member of Xenes family, germanene has excellent nonlinear saturable absorption characteristics. In this work, we prepared germanene nanosheets by liquid phase exfoliation and measured their saturation intensity as 0.6 GW/cm2 with a modulation depth of 8%. Then, conventional solitons with a pulse width of 946 fs and high-energy noise-like pulses with a pulse width of 784 fs were obtained by using germanene nanosheet as a saturable absorber for a mode-locked Erbium-doped fiber laser. The characteristics of the two types of pulses were investigated experimentally. The results reveal that germanene has great potential for modulation devices in ultrafast lasers and can be used as a material for creation of excellent nonlinear optical devices to explore richer applications in ultrafast photonics.Graphical