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An ultrasonic nondestructive method for evaluating bonding interface properties using Stoneley waves was proposed. First, a theoretical model was established. In this model, the dispersion relationship of the Stoneley wave at the quartz–steel interface and the transient signals generated by a pulse were analyzed. Significant differences were observed in the dispersion characteristics of Stoneley waves under different weak bonding conditions. Laser ultrasonic experiments were conducted to confirm the theoretical predictions, in which different interfacial strengths were simulated through the bonding–curing times. Based on these results, the inversion method was implemented to reconstruct the interfacial stiffness by using the corresponding dispersion of the Stoneley wave at different quartz–steel bonding interfaces extracted by the spectral analysis method. The results showed a similar tendency to those shown by theoretical predictions. Finally, the reconstructed interfacial stiffnesses were used to calculate the transient waveforms of the interface waves at different bonding–curing times, and the results showed good consistency with the experimental results, thereby verifying the rationality of the inversion results. [ABSTRACT FROM AUTHOR]

The measurement of mechanical properties of high-temperature resistant materials at high temperatures is particularly critical, and laser ultrasonic non-destructive testing technology is a prospective approach for measuring mechanical properties in high-temperature environments. Laser ultrasonic propagation models are constructed by finite element analysis, which reveals the effects of different excitation mechanisms on acoustic velocity measurements. It is found that the shear wave in the main propagation direction is hardly detected, and the distinction between shear waves and surface waves in the time domain signal is difficult. Based on the conclusions, the relationships between surface waves, longitudinal waves, and mechanical properties of materials are established by theoretical derivation. According to the propagation characteristics of surface waves and longitudinal waves, the eccentricity detection scheme of the same side and the concentricity detection scheme of the opposite side are, respectively, designed. The velocities of surface waves and longitudinal waves are measured, considering the thermal expansion coefficient and density changes with temperature. The mechanical properties of materials at different temperatures (25–1000 °C) are successfully calculated, and the experimental results are well in accordance with the reference values. It gives a reliable basis for efficient measurement of mechanical properties of materials at high temperatures. [ABSTRACT FROM AUTHOR]

Laser ultrasonic SAFT can be applied for noncontact testing and imaging of defects in structures. However, due to the large demand for signal data by laser scanning, the time consumption of this method would be relatively long. To address this problem, this paper proposes a fast LU-SAFT method with sparse scanning data and F-K based interpolation. It aims to reduce the inspection time but without decreasing the imaging resolution. First, the method determines the minimum number of scanning sparse points using simulation. Then the F-K interpolation method is utilised to recover the full-field unscanned point signal from the sparse scan data. Finally, the reconstructed signal is used for SAFT image reconstruction of the defect. The experimental results show that, for the same scanning area, the proposed method in this paper reduces the number of scanning points by 87.5% and shortens the scanning time by 86.0% compared to conventional LU-SAFT point-by-point scanning. Additionally, the signal-to-noise ratio of the defective SAFT imaging decreases by only about 7.9%. [ABSTRACT FROM AUTHOR]

In this paper, the laser ultrasonic non-destructive testing technology was used to detect the microstructure and mechanical properties of selective laser melting (SLM) 316 L stainless steel after post-treatment. The microstructure and mechanical properties of additively manufactured 316 L stainless steel were measured by Scanning electron microscopy (SEM), Electron backscatter diffraction (EBSD), tensile testing, etc. The laser ultrasonic longitudinal wave signal characteristic values were coupled with the microstructure and mechanical properties of SLM 316 L stainless steel. The results show that: The yield strength has a good correlation with wave speed and attenuation. With the increase of holding temperature and holding time, the grain size increases, the low angle grain boundary decreases, the yield strength gradually decreases from 409 MPa to 359 MPa, the wave velocity increases from 5579 m/s to 5700 m/s, and the frequency domain attenuation coefficient increases from 0.13 dB/mm to 0.16 dB/mm, the central frequency domain is about 10 MHz. The ultimate tensile strength is related to the frequency domain attenuation. The ultimate tensile strength decreases with the increase of the frequency domain attenuation coefficient. It can provide a reference for the evaluation of mechanical properties by laser ultrasonic testing. [ABSTRACT FROM AUTHOR]

Rayleigh waves are highly sensitive to surface and subsurface defects. However, the varying surface profiles of complex structures induce constant changes in the Rayleigh waveform. Furthermore, Rayleigh waves encompass multi-dimensional characteristics of subsurface defects, significantly increasing the difficulty of quantitatively detecting the sizes of subsurface defects in different dimensions. This paper presents a machine learning (ML)-based method for quantitatively detecting subsurface defect depth and width in curved structures using laser-generated Rayleigh waves. An experimentally validated finite element model is first established to construct a dataset of Rayleigh wave signals labeled with multidimensional subsurface defect sizes. The dataset is augmented from 188 to 368 samples using the Mix-up algorithm, with additional experimental signals incorporated. Feature parameters of Rayleigh waves are extracted in both time and frequency domains through waveform analysis and sliding window wavelet transform (SWT). These features are used to train ML models: Gaussian Process (GP), Extreme Gradient Boosting (XGBoost), and Random Forest (RF). Comparative results demonstrate GP achieves the highest prediction accuracy for subsurface defect depth and width on the test set, reaching 98.64% and 97.73%, respectively. The study highlights the integration of experimental and simulated data in training, which reduces costs while enhancing model robustness in practical applications. [ABSTRACT FROM AUTHOR]

The performance of machine learning algorithms is conditioned by the availability of training datasets, which is especially true for the field of nondestructive evaluation. Here we propose one reconfigurable specimen instead of numerous reference specimens with known, unchangeable defect properties, which are usually complicated to fabricate. It consist of a shape memory polymer foil with temperature-dependent Young's modulus and ultrasound attenuation. This open a possibility to generate a reconfigurable defect by projecting a heating laser in the form of a short line on the specimen surface. Ultrasound is generated by a laser pulse at one fixed position and detected by a laser vibrometer at another fixed position for 64 different defect positions and 3 different configurations of the specimen. The obtained diversified datasets are used to optimize the neural network architecture for the interpretation of ultrasound signals. We study the performance of the model in cases of reduced and dissimilar training datasets. In our first study, we classify the specimen configurations with the defect position being the disturbing parameter. The model shows high performance on a dataset of signals obtained at all the defect positions, even if trained on a completely different dataset containing signals obtained at only few defect positions. In our second study, we perform precise defect localization. The model becomes robust to the changes in the specimen configuration when a reduced dataset, containing signals obtained at two different specimen configurations, is used for the training process. This work highlights the potential of the demonstrated machine learning algorithm for industrial quality control. High-volume products (simulated by a reconfigurable specimen in our work) can be rapidly tested on the production line using this single-point and contact-free laser ultrasonic method. [ABSTRACT FROM AUTHOR]

This study introduces a reliable method for simultaneously determining the thickness, slope, and ultrasonic velocities of slope plates using laser ultrasonic techniques without any damage in the thermoelastic regime. The method involves solving a system of Equations to determine the arrival times of multiple signals displayed on a waveform. Numerical simulations indicate that the velocity of the skimming longitudinal wave remains constant when the Rayleigh wave does not overlap with its signal. Consequently, a prediction model for aluminum alloy has been established, enabling the estimation of the constant ratio between the velocities of skimming longitudinal and bulk longitudinal waves based on the skimming longitudinal velocity obtained by scanning the generating laser along the material's surface. This ratio, approximately 0.950, facilitates the combination of the skimming longitudinal wave with the reflected and mode-converted waves from the specimen's back surface to deduce the desired parameters. The method successfully determined the thickness, slope, and wave velocities of several specimens with slopes ranging from 0% to 1.96% and a maximum thickness of about 10 mm. Evaluating the influence of the size of the disk ultrasound source produced by the unfocused laser beam, we found that the radius of the disk source should be considered when calculating the arrival time of the skimming longitudinal wave. The root mean square deviation in measuring thickness, slope, longitudinal wave velocity, and shear wave velocity were approximately 0.100 mm, 0.10%, 70 m/s, and 20 m/s, respectively. An assessment of the measured results, based on the root mean square deviation and uncertainty across all specimens, demonstrates the practical feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

This study investigates the effect of changing the chemical composition during ultrasonic atomization (UA) and laser powder bed fusion (LPBF) of low‐alloy steel. UA is used to produce a spherical powder with d50 equal to 49 μm. During UA, the chemical composition of the material changes, which is associated with selective evaporation of Mn from 1.42% to 0.35% and B from 0.0012% to <0.0001%. Thermodynamic calculations confirm that during atomization, mostly Mn and Fe evaporate. To achieve a high density of 3D printed parts, in situ remelting in LPBF is applied. A microstructure consisting of fine grains of tempered martensite and bainite in crystallized meltpools is observed. The selected high‐quality LPBF samples are austenitized in the temperature range of 900–1200 °C for 20 min and quenched in oil. The samples are characterized by light and scanning electron microscopy, as well as Vickers hardness. Changes in chemical composition result in a decrease in the hardenability of the material, and quenching only at 1200 °C produces a martensitic microstructure. LPBF samples show a hardness higher than that of the postheat‐treated sample, but still significantly lower than that of the as‐delivery condition, which is related to the change in chemical composition. [ABSTRACT FROM AUTHOR]

The corrosion on the switch rail’s foot may easily lead to rail breakage. Laser ultrasound detection is often used to assess the integrity of rails. Nevertheless, the inadequate photoacoustic conversion efficiency and vulnerability to surface interference of the entirely non-contact laser ultrasound result in a diminished signal-to-noise ratio (SNR), hence impeding the efficient detection and analysis of minor damages in the rail. This work demonstrates piezoceramic material lead zirconate titanate (PZT) wafers in conjunction with a pulsed laser to create a sensor array capable of accurate array image inspections. The PZT sensor arrays are manufactured in a flexible format that may be easily installed and altered to complicated geometries. Pulsed lasers are used to achieve dense and high-frequency array excitation. This study proposes a novel probabilistic picture location identification strategy by merging the variable mode decomposition algorithm based on parameter optimization (PVMD) and the principle component analysis (PCA) algorithm. The aim is to enhance the SNR and increase the accuracy of damage findings. Simulation and experimental tests have demonstrated the accuracy of the suggested mechanisms and algorithms in identifying damaged regions. [ABSTRACT FROM AUTHOR]

Background: Chronic apical periodontitis is a persistent inflammatory condition affecting the periapical tissues of a tooth. Effective disinfection of the root canal system is crucial for successful endodontic treatment. This study aims to compare the efficacy of ultrasonic irrigation (UI) and laser-activated irrigation (LAI) in promoting healing in chronic apical periodontitis. Materials and Methods: A total of 100 patients diagnosed with chronic apical periodontitis were randomly assigned to two groups: the UI group (n=50) and the LAI group (n=50). Patients in the UI group received endodontic treatment using ultrasonic irrigation, while those in the LAI group received treatment with laser-activated irrigation. The primary outcome measure was the reduction in periapical lesion size, assessed using digital radiographs at baseline, 3 months, and 6 months post-treatment. Secondary outcomes included pain reduction and overall treatment success, defined as the absence of clinical symptoms and radiographic evidence of healing. Results: At the 3-month follow-up, the UI group showed a 60% reduction in periapical lesion size, while the LAI group exhibited a 75% reduction. At the 6-month follow-up, the UI group demonstrated an 80% reduction, and the LAI group achieved a 90% reduction in lesion size. Pain scores decreased significantly in both groups, with the LAI group reporting a more rapid decline in pain levels. Overall treatment success was observed in 85% of patients in the UI group and 95% in the LAI group at the 6-month follow-up. Conclusion: Both ultrasonic irrigation and laser-activated irrigation are effective in promoting healing in chronic apical periodontitis. However, laser-activated irrigation showed superior outcomes in terms of periapical lesion size reduction and overall treatment success. These findings suggest that LAI may be a more effective adjunctive technique in endodontic therapy for chronic apical periodontitis. [ABSTRACT FROM AUTHOR]

In this work, a two-parameter inversion problem is analyzed, related to surface crack widths for measuring depths of normal surface notches, based on a laser-based ultrasonic measurement method in the time domain. In determining the depth measurement formulas, the main technique is the time delay between reflected and scattered waves. Scattered waves are generated by two reflections along the bottom and three mode transformations at the surface of the crack tips. Moreover, the scattering angle of the mode-conversion waves is 30°. These two key factors lead to corrected item "2wβ" in the depth measurement formula. A laser-based ultrasonic experimental platform is built to generate and receive surface waves in a non-contact manner on aluminum and steel specimens with surface cracks. The depth measurement method proposed in this paper has been validated through theoretical, simulation, and experimental methods. Finally, in this paper, an effective approach for quantitatively measuring crack depths, based on laser ultrasound, using the time-domain properties of surface wave propagation is provided. [ABSTRACT FROM AUTHOR]

Aluminium nitride (AlN) materials are widely used in heat-dissipation substrates and electronic device packages. However, the application of aluminium nitride ceramics is hindered by the obvious anisotropy and high brittleness of its crystals, leading to poor material surface integrity and high grinding force. With the rapid development of microelectronics, the requirements for the material's dimensional accuracy, machining efficiency, and surface accuracy are increasing. Therefore, a new machining process is proposed, combining laser and ultrasonic vibration with grinding. The laser–ultrasonic-assisted grinding (LUAG) of aluminium nitride is simulated by molecular dynamics (MD). Meanwhile, the effects of different processing techniques on grinding force, stress distribution, matrix damage mechanism, and subsurface damage depth are systematically investigated and verified by experiments. The results show that laser–ultrasonic-assisted grinding produces 50% lower grinding forces compared to traditional grinding (TG). The microhardness of AlN can reach more than 1200 HV, and the coefficient of friction and wear is reduced by 42.6%. The dislocation lines of the AlN substrate under this process are short but interlaced, making the material prone to phase transformation. Moreover, the subsurface damage depth is low, realising the substrate's material hardening and wear resistance. These studies not only enhance the comprehension of material build-up and stress damage under the synergistic impact of laser, ultrasonic, and abrasive processing but also indicate that the proposed method can facilitate and realise high-performance machining of aluminium nitride substrate surfaces. [ABSTRACT FROM AUTHOR]

To achieve quantitative detection of subsurface-inclined cracks, the reflected surface waves from subsurface cracks with different lengths and angles were obtained by the finite element method (FEM). The relationship between the time difference of each feature wave in the reflected waves and the length and angle of the subsurface inclined crack was analysed. The arrival time difference between the lowest trough and the first trough of the reflected wave is independent of the angle of the subsurface crack and approximately a linear function of the crack length. Furthermore, when the crack lengths remain unchanged, the arrival time difference between the highest peak and the second trough of the reflected wave is a quadratic function with the angle of the subsurface crack. Thus, a quantitative measurement method for gauging the length and angle of subsurface inclined cracks is proposed based on the above phenomena. The relationships between the length and angle of the subsurface inclined crack and the arrival time difference of the reflected surface waves were obtained by curve fitting. The proposed method was verified by simulation data. The maximum relative error of the crack length obtained by the method was 7.76%, and the maximum relative error of the obtained inclination angle was 11.61% when the crack angle was large. The proposed approach will open the way for simultaneous measurement of the length and angle of subsurface inclined cracks and structures. [ABSTRACT FROM AUTHOR]

This paper presented a new approach for noncontact inspection of defects in milling groove brazed joints of thrust chamber with laser ultrasonic testing method and synthetic aperture focusing technique (SAFT). Firstly, laser ultrasonic testing methods for milling groove brazed joints of thrust chamber was studied. Subsequently, numerical models were constructed to analyze the influence of defects on laser-excited signals. The analysis revealed that the brazed defects caused internal waves to reflect on the rib surface, manifesting as defect echo signals preceding the outer wall echo. Through scanning setting, the obtained SAFT images illustrate the presence of the defect directly and clearly. Furthermore, an experimental system was established to detect and image artificial defects with different degrees of weld leakage. The experimental results are consistent with simulation results, validating the capability and effectiveness of the testing and imaging method. In general, the proposed laser ultrasound method offers inherent advantages of non-contact detection with high resolution and precision, and it is easy to achieve fast and automated scanning of large and complex structures like thrust chambers, demonstrating its potential for enhancing the safety and reliability of liquid rocket engines. [ABSTRACT FROM AUTHOR]

Photothermal therapy (PTT) has garnered considerable attention as an attractive treatment tool for cancer due to precisely selective treatment and minimal side effects. The primary challenge of PTT, which hinders its widespread application, is the limited therapeutic depth. This limitation arises from optical scattering in biological tissues, causing inadequate heat distribution within the deep tissue. To overcome this challenge, ultrasound‐assisted PTT (ULTRA‐PTT) is proposed that leverages the temporary formation of gas bubbles induced by ultrasound within the light propagation path. These bubbles act as optical clearing agents, effectively reducing optical scattering in biological tissues. To facilitate ULTRA‐PTT, a dedicated handpiece consisting of a ring‐shaped ultrasound transducer and a laser delivery module is developed. In‐vivo experiments show that ULTRA‐PTT statistically outperforms conventional PTT in melanoma treatment, mostly due to its ability to deliver sufficient laser energy to deep‐seated cancer cells. These findings underscore the potential of ULTRA‐PTT to expand the clinical applications of PTT beyond local tumors occurring in superficial tissue. [ABSTRACT FROM AUTHOR]

With the recent advancement in manufacturing, there has been an increasing demand for composite workpieces in the aviation industry. The emergence of composite 3D printing technology that enables the simplification and automation of composite manufacturing processes presents the possibility of replacing the manufacturing process of secondary structures in an unmanned aerial vehicle (UAV). To evaluate the applicability of the technology, a solution for automated non-destructive testing (NDT) that can be applied after the 3D printing process is needed. This study proposes an advanced approach to utilizing laser ultrasonic testing (LUT) for complex-shaped structures fabricated through continuous fiber 3D printing. To ensure accurate defect detection and localization, which are crucial factors in NDT, we propose a method that utilizes a six-degree-of-freedom (6-DOF) robot arm to control the position of the inspection target. By calculating the scan points and path through coordinate transformation and spatial rotation using a quaternion, all surfaces of the targets were inspected. This maintains a constant stand-off distance (SOD) while the sensing laser was vertically incident on the target surface, resulting in a high signal-to-noise ratio (SNR) of the ultrasonic signals. Inspection results have demonstrated the proposed technique to be suitable for detecting defects in complex-shaped 3D-printed structures. [ABSTRACT FROM AUTHOR]

It is shown that the conventional theory of thermoelasticity is insufficient to explain the behavior of pulsed laser ultrasonic signals from materials with defects. A theoretical model of thermoelasticity is proposed that takes into account the thermal excitation of defect states by laser radiation with their subsequent recovery to the initial state with a certain relaxation time. The linear model of thermoelasticity in terms of slow dynamics is developed. The difference in the behavior of ultrasonic signals from dielectrics and metals under pulsed laser excitation is analyzed and explained. It is shown that in the linear approximation of the thermoelastic model, slow dynamic effects can be taken into account by introducing an effective thermal coefficient. [ABSTRACT FROM AUTHOR]

Background: Modern developments in microscopic endodontics have included Dental Operating Microscope (DOM), ultrasonics, piezo technology, CBCT, digital imaging and scanning, laser endodontics, and nanotechnology. Aim: This narrative review also assesses the diagnostic efficiency, treatment outcomes, patients' outcomes and cost-effectiveness of these technologies. Methods: The literature search was done in PubMed, MEDLINE, Scopus, Web of Science, and Cochrane library by searching for English language, peer-reviewed articles published in the last 15 years. Results: According to this review, DOMs and CBCT both considerably increase diagnostic accuracy and therapeutic potential, which enhances treatment outcomes and raises patients' quality of life. Ultrasonics and laser endodontics can be used to produce minimally invasive treatments, and there is little to no pain following surgery. Nanotechnology and digital imaging are two instances of new technologies that still need to be developed. These technologies need significant capital investments from an economic perspective, but the investment pays for itself in returns. Conclusion: This review established that improvements in microscopic endodontic are impressive in diagnostic and therapeutic result while the initial costs are high. Arguments including increased accuracy in treatment, decreased patient discomfort, and better therapeutic outcomes serve as strong arguments for the continued application and advancement of endodontic tactics. [ABSTRACT FROM AUTHOR]

Additive Manufacturing (AM) technology is recognized as a pivotal direction for future technological and industrial advancement. Nevertheless, inherent to the manufacturing process are defects such as pores, inclusions, lack of fusion, and layering, which pose significant threats to product quality and safety, thereby serving as significant obstacles to the widespread adoption of additive manufacturing technology. Consequently, in recent years, non-destructive testing techniques for additive manufacturing products have gained considerable attention in research. This paper focuses on components manufactured using the Laser Metal Deposit (LMD) process with AlSi10Mg material. Through a combination of finite element simulations and experimental analysis, this study compares and analyzes the propagation of laser ultrasound within AM components. By examining the characteristics of shear wave reflection signals from internal defects in AM components, a defect quantification method based on a laser ultrasonic (LU) inspection system is proposed. The research findings indicate that this method is capable of detecting sub-millimeter-level internal defects within AM components. Extracting the shear wave reflection signals from defects, enables quantitative assessment of the location and depth of internal defects in AM components. [ABSTRACT FROM AUTHOR]

Guided ultrasonic wavefield propagation imaging (GUPI) is useful for visualizing hidden flaws in aerospace thin-walled structures, but the need for subjective signal processing involving three-dimensional Fourier transformation to increase the visibility of subtle flaws hinders its wider acceptance. A high-resolution wavenumber bandpass filter capable of consolidating subtle flaw-relevant information from a wide frequency band using only two-dimensional Fourier transformation was proposed. The filter overturns the long-standing belief that modes must be separated based on narrow-band data acquisition or processing to achieve high flaw visibility. Its characteristics and advantages were experimentally demonstrated through enhanced visualization of hidden wall-thinning flaws of a plate specimen. Its strength was further demonstrated through the first GUPI visualization of a partially loosened bolt, with unprecedented clarity to discern bolt tightness levels. The results conclusively proved that the proposed filter significantly enhances the resolution of GUPI within a structured processing framework. [ABSTRACT FROM AUTHOR]

In conventional laser ultrasonic (LU) single-mode frequency domain synthetic aperture focusing technique (F-SAFT) imaging, the precision of the imaged defect profile is limited due to the influence of the directionality of laser-induced ultrasound and the directionality of detection. To solve this problem, LU-based F-SAFT imaging with the shear wave, longitudinal wave, and mode-converted wave is proposed in this article. In the experiment, multimode bulk waves are excited by a pulsed laser, and a laser Doppler vibrometer is employed to detect ultrasound waves. The F-SAFT imaging is performed with single-mode and multimode ultrasound wave signals, respectively. The results show that F-SAFT imaging fusing three mode signals (shear, longitudinal, and mode-converted waves) improves the range of the upper surface of the imaged defect by nearly two times. In addition, the profile of the imaged defect is more complete than that of using a combination of both longitudinal and shear waves. By analyzing the influence of the directionality of laser-induced ultrasound and the detection directionality caused by the out-of-plane ultrasound component on the imaging results, a theoretical approach is used to select a reasonable excitation–detection distance for the use of multimode-fused F-SAFT algorithm. Furthermore, the feasibility of the theoretical approach is verified by the experimental results. [ABSTRACT FROM AUTHOR]

The traditional microstructure detecting methods such as metallography and electron backscatter diffraction are destructive to the sample and time-consuming and they cannot meet the needs of rapid online inspection. In this paper, a random forest regression microstructure characterization method based on a laser ultrasound technique is investigated for evaluating the microstructure of a titanium alloy (Ti-6Al-4V). Based on the high correlation between the longitudinal wave velocity of ultrasonic waves, the average grain size of the primary α phase, and the volume fraction of the transformed β matrix of the titanium alloy, and with the longitudinal wave velocity as the input feature and the average grain size of the primary α phase and the volume fraction of the transformed β matrix as the output features, prediction models for the average grain size of the primary α phase and the volume fraction of the transformed β matrix were developed based on a random forest regression. The results show that the mean values of the mean relative errors of the predicted mean grain size of the native α phase and the volume fraction of the transformed β matrix for the six samples in the two prediction models were 11.55% and 10.19%, respectively, and the RMSE and MAE obtained from both prediction models were relatively small, which indicates that the two established random forest regression models have a high prediction accuracy. [ABSTRACT FROM AUTHOR]

This paper introduces a reliable laser ultrasonic technique without damage to the surface in the thermoelastic regime that provides a one-side access method for simultaneously determining the thickness and ultrasonic wave velocity by employing multiple wave modes. Initially, this study determines the optimal separated distance between two laser beams to achieve an effective signal-to-noise ratio of the employed wave modes. Subsequently, a pre-established ratio of 0.95 for the velocity of skimming longitudinal waves and longitudinal waves enables the simultaneous calculation using a combination of the skimming longitudinal wave, reflected shear wave, and mode-converted longitudinal wave in a single measurement. Experiments were carried out on various plane plates made of aluminium alloy 6061, ranging in thickness from 4 to 20 mm, demonstrating a high accuracy in thickness measurement, with a maximum absolute error of 0.05 mm. Compare the results of ultrasonic wave velocity measurements with theoretical calculations, the maximum absolute error is 32 m/s and 80 m/s for longitudinal wave and shear wave, respectively. [ABSTRACT FROM AUTHOR]

This paper investigates the method for water ingress detection in an aluminum honeycomb sandwich structure by laser ultrasonics. To clarify the propagation of Scholte waves generated at the solid-liquid interface, the theoretical dispersion curves in the water-aluminum layered structure are calculated by the global matrix method. Using a laser ultrasonic visualizing inspector, the guided wave propagation in the wavefields has been visualized, which shows the mode conversion behaviors occurring in the water ingress area. The clarification of mode conversion is then investigated by the finite element method. The Scholte modes at the solid-fluid interface and the Lamb modes in the face sheet are interconverted because of the change in the waveguide structure. Wavenumber filter reconstruction and the resulting energy maps are applied to illustrate the mode conversion in the wavefields and to detect the water ingress area. Results show that the appearance of the water layer contributes to the mode conversion behaviors during the guided wave propagation in the honeycomb sandwich structure, which offers the potential for water ingress detection based on the mode conversion behaviors. [ABSTRACT FROM AUTHOR]

Aim: The aim of the study was to investigate the disinfecting efficacy of a standardized irrigating solution activated by ultrasonics or laser irradiation on mature dual-species biofilms at different root levels in vitro. Materials and Methods: Conventional access cavity preparations were done on 160 single-rooted mandibular premolar teeth with single canals. Freshly extracted oral microbial strains of Staphylococcus aureus, Streptococcus mutans, Enterococcus faecalis, and Candida albicans after biochemical confirmation were used to generate two discrete dual-species microbial inoculums. The sterilized tooth samples were randomly segregated into two groups (n = 80) and inoculated with a mixed inoculum of S. aureus + E. faecalis strains (Group 1) and S. mutans + C. albicans strains (Group 2), respectively. Following the 21-day incubation period under aerobic conditions, the infected specimens in each group were divided into four subgroups (n = 20) and subjected to experimental treatment protocols. This included a positive control (no treatment of biofilms), syringe irrigation alone with TruNatomy needle, passive ultrasonically activated irrigation with 20# Irrisafe tip, and laser agitation of irrigant with Er,Cr:YSGG laser using RFT 2 laser tip. Root canals of experimental specimens (except the control samples) are instrumented with TruNatomy rotary file system using 1:1 mixture of 3% NaOCl and 18% etidronic acid as irrigants. The quantitative assessment of reduction in viable biofilm microbes after treatment was done using colony-forming unit counts and confocal laser scanning microscopy image analysis. The obtained data were analyzed statistically with a significant level set at 0.05. Results: Laser-assisted irrigation has shown a considerably higher mean percentage reduction of microbes compared to ultrasonic agitation and the syringe irrigation showed the least microbial reduction (P = 0.001). No significant difference was noted between the three root regions of ultrasonic and laser groups (P > 0.05), whereas in the syringe groups, apical portions showed higher microbial counts compared to cervical and mid-root regions (P = 0.001). Conclusion: Erbium laser-assisted irrigation has performed superior to ultrasonic agitation against both the experimental dual-species biofilms, while the syringe irrigation showed the least microbial reduction specifically at apical root portions. [ABSTRACT FROM AUTHOR]

Thin copper plate is widely used in architecture, transportation, heavy equipment, and integrated circuit substrates due to its unique properties. However, it is challenging to identify surface defects in copper strips arising from various manufacturing stages without direct contact. A laser ultrasonic inspection system was developed based on the Lamb wave (LW) produced by a laser pulse. An all-fiber laser heterodyne interferometer is applied for measuring the ultrasonic signal in combination with an automatic scanning system, which makes the system flexible and compact. A 3-D model simulation of an H62 brass specimen was carried out to determine the LW spatial-temporal wavefield by using the COMSOL Multiphysics software. The characteristics of the ultrasonic wavefield were extracted through continuous wavelet transform analysis. This demonstrates that the A0 mode could be used in defect detection due to its slow speed and vibrational direction. Furthermore, an ultrasonic wave at the center frequency of 370 kHz with maximum energy is suitable for defect detection. In the experiment, the size and location of the defect are determined by the time difference of the transmitted wave and reflected wave, respectively. The relative error of the defect position is 0.14% by averaging six different receiving spots. The width of the defect is linear to the time difference of the transmitted wave. The goodness of fit can reach 0.989, and it is in good agreement with the simulated one. The experimental error is less than 0.395 mm for a 5 mm width of defect. Therefore, this validates that the technique can be potentially utilized in the remote defect detection of thin copper plates. [ABSTRACT FROM AUTHOR]

Spherical pressure vessels as fuel storage for space uses are usually made by the spinning process and precise control of thickness is a prerequisite. The non-contact thickness measurement method is necessary in such a case. Laser ultrasonic technique (LUT) is highly appreciated in this case of non-contact measurement. As a significant amount of surface roughness, i.e., roller wake produced during radial and axial feeding of the roller to the cylinder, the objective of this study is to investigate the effect of rough surfaces generated by the spinning process on thickness measurement using laser-generated ultrasound through experiment. This paper describes the variations in average thickness and amplitude of thickness measured by contact gauge and LUT at hill and valley portion of the roller wake of spinning processed cylinder. Some underestimation occurs at the hill case. The maximum amount of underestimation was about 0.04 mm. The variation in thickness caused by the spinning process can also be measured with no contact by the proposed LUT method. The maximum relative change in thickness due to the spinning process was about 9.5%. Necessary adjustment based on the finding can be a key to establish an efficient real-time thickness measurement system in the spinning process for economic and reliable production of a spherical pressure vessel. [ABSTRACT FROM AUTHOR]

In this paper, transmitted surface waves are used to quantitatively detect the length and angle of inclined surface cracks based on laser ultrasonic technique. The interaction between laser-generated surface waves and inclined surface cracks is analysed, and the propagation path and mode conversion process of the transmitted surface waves are considered. Then, the propagation paths of some peaks and troughs of the transmitted surface waves are obtained. Based on the obtained path and modal conversion information, a quantitative detection method for the length and angle of inclined surface cracks is proposed. The finite element method is used to verify the propagation paths and proposed method, and the results show that the arrival time of the theoretical path is consistent with that of the simulation. The relative measurement errors of the surface crack length and angle are less than 15% and 10%, respectively, which verifies the rationality and correctness of the proposed method. [ABSTRACT FROM AUTHOR]

Small-hole structures, such as the millions of fastener holes found on aircraft, are typical stress-concentration structures prone to fatigue failure. To further improve the strengthening process of this small-hole structure, we make up for the limitations of laser shock processing (LSP) of small holes by combining it with the ultrasonic extrusion strengthening (UES) process to form a new strengthening method—laser shock and ultrasonic extrusion strengthening (LUE). The influence of the LUE process sequence and process parameters on residual stress distribution was studied through FEM, and the gain of fatigue life of specimens after LUE strengthening was also explored through tests. The results show that when using LUE technology, the friction force decreases with the increase in amplitude and decreases by 3.2% when the amplitude is maximum. The LUE process eliminates the thickness effect generated by LSP, which can achieve good stress distribution of small-hole components under smaller laser shock peak pressure, and reduces equipment power. LUE can significantly improve the fatigue life of small-hole components, and the maximum fatigue life gain can be up to 310.66%. [ABSTRACT FROM AUTHOR]

Conditioned steak is easily contaminated by foreign bodies, such as iron sheets, glass, and crush bones in the manufacturing processes, posing hidden safety hazards to consumers. In this study, the feasibility of using ultrasonic imaging to detect and identify foreign bodies in conditioned steaks was investigated. Firstly, the ultrasonic imaging data of foreign bodies was collected. Four discriminant models among them linear discriminant analysis (LDA), and extreme learning machine (ELM) were established, and based on the texture values of the smallest circumscribed rectangular area of the foreign bodies, the type was identified. The foreign bodies were then extracted by gray-level co-occurrence matrix (GLCM). The detection rate of foreign bodies was 97.78 %, meanwhile ELM showed the highest accuracy of recognition rate of 76.67 %. The results showed that ultrasound imaging technology could be used to detect foreign bodies in the conditioned steak and to identify the type of foreign body via pattern recognition. [ABSTRACT FROM AUTHOR]

Laser-cladding technology is now widely used in repairing mechanical parts and creating functional coatings. However, interface defects are commonly found in laser-cladding coatings, significantly impacting the fatigue and mechanical properties of these coatings. Therefore, it is necessary to detect interface defects in laser-cladding coatings. In this study, we utilised laser ultrasonics (LU) method to test interface defects non-destructively. However, the signal-to-noise ratio (SNR) of LU signals was poor. To address this issue, an unsupervised deep learning method was used to enhance the SNR. The results showed that the noises were suppressed by the deep learning method. Based on the deep learning-enhanced LU method, surface acoustic waves were used to present B-scan and C-scan images. The artificial defects with a 0.5 mm diameter were detected. Consequently, the deep learning-enhanced LU method proves to be a viable approach for the contactless, online, and non-destructive testing of interface defects in laser-cladding coatings. [ABSTRACT FROM AUTHOR]

The underlying study was carried out aiming at transdermal drug delivery (TDD) of Goniothalamus macrophyllus as sono-photo-sensitizer (SPS) using microneedle (MN) arrays with iontophoresis (MN-IP), electroporation (MN-EP) in conjunction with applying photodynamic therapy (PDT), sonodynamic therapy (SDT) and sono-photodynamic therapy (SPDT) as an up-to-date activated cancer treatment modality. Study was conducted on 120 male Swiss Albino mice, inoculated with Ehrlich ascites carcinoma (EAC) divided into 9 groups. We employed three different arrays of MN electrodes were used (parallel, triangular, and circular), EP, IP with different volts (6, 9, 12 V), an infrared laser and an ultrasound (pulsed and continuous wave) as our two energy sources. Results revealed that parallel 6 V TDD@MN@IP@EP can be used as effective delivery system for G. macrophyllus from skin directly to target EAC cells. In addition MN@IP@EP@TDD G. macrophyllus is a potential SPS for SPDT treatment of EAC. With respect to normal control mice and as opposed to the EAC untreated control mice, MN@EP@IP TDD G. macrophyllus in the laser, ultrasound, and combination activated groups showed a significant increase in the antioxidant markers TAC level and the GST, GR, Catalase, and SOD activities, while decrease in lipid peroxidation oxidative stress parameter MDA levels. In addition significantly increased apoptotic genes expressions (p53, caspase (3, 9), Bax, and TNF alpha) and on the other hand decreased anti- apoptotic (Bcl-2) and angiogenic (VEGF) genes expressions. Moreover significantly ameliorate liver and kidney function decreasing ALT, AST, urea and creatinine respectively. Furthermore MN@IP@EP@TDD G. macrophyllus combined with SPDT was very effective at reducing the growth of tumors and even causing cell death according to microscopic H&E stain results. This process may be related to a sono- and/or photochemical activation mechanism. According to the findings, MN@IP@EP@TDD G. macrophyllus has a lot of potential as a novel, efficient delivery method that in combination with infrared laser and ultrasound activation SPDT demonstrated promising anticancer impact for treating cancer. [ABSTRACT FROM AUTHOR]

An improved frequency-domain synthetic aperture focusing technique (F-SAFT) for laser ultrasonic testing (LUT) is proposed for internal defect detection of small-diameter cylindrical components. Firstly, a LUT automated detection platform is built, a pulsed laser is used to excite ultrasonic waves and a two-wave mixing (TWM) interferometer is used to detect ultrasonic waves. Since ultrasonic signals are affected by the thermal expansion of the pulsed laser, time-frequency analysis is used to obtain the frequency range for imaging longitudinal waves, and the influence of low-frequency clutter is eliminated through multiple filtering. Secondly, in order to balance signal acquisition efficiency and imaging quality, the peak signal-to-noise ratio (PSNR) is used to determine the optimal angular step size. Finally, the equivalent velocity of the longitudinal wave is corrected to compensate for the imaging position error caused by the separation of the ultrasonic excitation point and the detection point. The results show that the method proposed in this paper has high imaging accuracy, which could provide a new approach for in-service non-destructive testing of small-diameter cylindrical components. [ABSTRACT FROM AUTHOR]

Aiming at the problem of deterioration of the properties of beta titanium alloy welded joints due to many porosity defects and coarse grains, multi-vibrator ultrasonic-assisted laser welding (M—ULW) technology was used to improve the structure and properties of beta titanium alloy welded joints. The microstructure evolution, tensile strength, elongation, and fracture behavior of the weld joint were studied through scanning electron microscopy, electron back-scatter diffraction, and a universal testing machine. The results show that ultrasonic vibration has no effect on the phase composition of titanium alloy welds during ultrasonic-assisted laser welding. However, it caused all grains in the weld to be transformed into equiaxed grains, and the higher the amplitude, the finer and more uniformly distributed were the equiaxed grains. When the ultrasonic amplitude reached 20 μm, the fine equiaxed crystals were uniformly distributed throughout the weld, and the average grain size of the weld was 56.15 um, which is only one-third of that of the unultrasonicated laser welded joint. Ultrasonic refinement makes the joint grain size decrease, weakens the beta titanium alloy {200} direction weaving, increases the dislocation density within the weld; and increases the tensile strength of the welded joint. The tensile strength of the welded joints exceeded that of the base material by 907 MPa, and the elongation was significantly increased by a factor of 1.8 compared with that of the un-ultrasonicated laser welded joints, resulting in a shift of the fracture location from the center of the weld to the heat-affected zone. [ABSTRACT FROM AUTHOR]

Introduction: The utilization of various energy sources to assist the machining process has become prominent to achieve substantial improvement in machining performance. These energy sources have also resulted in an alternative to cutting fluids which is safer for both the universe and human beings. The combined action of laser and ultrasonic vibration energies during the turning process has shown significant achievement in machining process capabilities. Moreover, the application of higher compressed air pressure has achieved substantial improvement in machinability during the turning process. Materials and methods: An attempt has been made to improve the machinability of aluminium 3003 alloy during the simultaneous application of compressed air pressure and ultrasonic-vibration-laser-assisted turning (UVLAT) process. Machining performance has been analyzed in terms of machining temperature, tool wear, machining forces, chip morphology, and surface roughness. A comparative machining performance analysis has been carried out between different compressed air pressure for the laser-assisted turning (LAT) and UVLAT processes. Results: The outcomes of the current study indicate a significant reduction in maximum machining temperature due to higher compressed air pressure. Lower tool wear was observed due to a reduction in maximum machining temperature and led to lower machining forces at higher compressed air pressure. Lesser chip segmentation and smooth chip edges were obtained which led to a reduction in surface roughness for higher compressed air pressure during the LAT and UVLAT processes. Conclusion: The presented results are important for manufacturing industries seeking to improve the machinability of aluminium alloys. [ABSTRACT FROM AUTHOR]

The effective detection of delamination defects, especially sub-millimeter delamination defects, in metal-clad plates is of great significance in improving product quality. In this work, the laser ultrasonic (LU) local resonance method is used to locate and characterize the sub-millimeter defects in stainless/carbon steel-clad plates. The influence of the delamination radius on the amplitude and resonant frequency of the laser ultrasound was investigated using 2D axisymmetric finite element (FE) simulations. The simulation results show that both the amplitude and the first resonance frequency (FRF) are effective features for detecting large-scale delamination defects, but the FRF is a better feature for detecting tiny delamination defects. A 304/Q235/304-clad plate specimen was made through a hot rolling bonding process, which contained a large number of self-forming delamination defects. The laser ultrasonic signals of different composite states collected in the experiment have good consistency with the simulated waveforms. The experimental results show that the laser ultrasonic local resonance method is a high-resolution imaging method, which can locate and characterize the sub-millimeter delamination defects in stainless/carbon steel-clad plates. [ABSTRACT FROM AUTHOR]

Major biological discoveries are made by interrogating living organisms with light. However, the limited penetration of un‐scattered photons within biological tissues limits the depth range covered by optical methods. Deep‐tissue imaging is achieved by combining light and ultrasound. Optoacoustic imaging exploits the optical generation of ultrasound to render high‐resolution images at depths unattainable with optical microscopy. Recently, laser ultrasound has been suggested as a means of generating broadband acoustic waves for high‐resolution pulse‐echo ultrasound imaging. Herein, an approach is proposed to simultaneously interrogate biological tissues with light and ultrasound based on layer‐by‐layer coating of silica optical fibers with a controlled degree of transparency. The time separation between optoacoustic and ultrasound signals collected with a custom‐made spherical array transducer is exploited for simultaneous 3D optoacoustic and laser ultrasound (OPLUS) imaging with a single laser pulse. OPLUS is shown to enable large‐scale anatomical characterization of tissues along with functional multi‐spectral imaging of chromophores and assessment of cardiac dynamics at ultrafast rates only limited by the pulse repetition frequency of the laser. The suggested approach provides a flexible and scalable means for developing a new generation of systems synergistically combining the powerful capabilities of optoacoustics and ultrasound imaging in biology and medicine. [ABSTRACT FROM AUTHOR]

The design of the resonant ultrasonic vibration-assisted laser cladding (R-UVALC) setup involved employing finite element analysis (FEA) to simulate the ultrasonic transducer, horn, and workpiece in a resonance state. The impact of R-UVALC on AlCrFeMnNi high-entropy alloys was assessed using various ultrasonic vibration amplitudes of 0, 5, 10, and 15 µm, with a constant frequency of 20 kHz. Ultrasonic vibrations reduced pores and cracks and increased the clad breadth, melt pool wetting angle, and laser-clad layer consistency. The columnar elongated grains in proximity to the substrate surface underwent a size reduction and transformed into grains with a more equiaxed shape with the utilization of ultrasonic vibrations at an amplitude of 5 µm. Laser cladding performed without ultrasonic vibrations yields two phases: face-centered cubic (FCC) and body-centered cubic (BCC). However, when the coating is exposed to ultrasonic vibrations with an amplitude of 5 µm, it forms a solitary body-centered cubic (BCC) phase. The microhardness tripled compared to the substrate, and the most significant microhardness value was achieved at 5 µm of ultrasonic vibration. The friction coefficient was assessed at an ambient temperature, revealing that an ultrasonic amplitude yields the lowest friction coefficient, demonstrating the excellent wear resistance properties of the coating. The analysis of the 3D surface profile of the wear indicates that the use of ultrasonic aid with a 5 µm amplitude leads to reduced depth of scars, and the primary wear mechanism observed is abrasive and oxidative wear with fewer grooves and debris. In addition, XPS analysis revealed the presence of metal components in an oxidized condition, suggesting that the wear process is oxidative in nature. Integrating the R-UVALC setup into a resonance state can significantly enhance the efficiency of the laser cladding process in the laser cladding field. [ABSTRACT FROM AUTHOR]

Introduction: Temporomandibular Joint Disorders (TMDs) are considered multifactorial, and several treatment approaches have been proposed for their effective management. The use of non invasive treatment modalities is recommended, which includes Transcutaneous Electric Nerve Stimulation (TENS), Low-Level Laser Therapy (LLLT), acupuncture, ultrasound, and manual therapies. Aim: To evaluate the effectiveness of TENS, LLLT, and ultrasound therapy in patients suffering from TMDs. Materials and Methods: This prospective, randomised clinical trial was conducted on thirty patients (11 males, 19 females) clinically diagnosed with TMD associated with Temporomandibular Joint (TMJ) pain, clicking joint sound, pain in the muscles of mastication, and limited mouth opening. Patients were sequentially randomised into three groups to be treated with TENS, laser beam, and ultrasound therapies, respectively. The Visual Analog Scale (VAS) Score and painfree mouth opening were recorded before, during, and after treatment. Data were analysed using Statistical Package for Social Sciences(SPSS) version 16.0 statistical software. Statistical tests such as the paired sample t-test, Analysis of Variance (ANOVA), and post-hoc Tukey test were performed. Results: There was a significant reduction in the VAS score in the TENS group (3.15), LLLT group (5.75), and ultrasound group (5.50) post-treatment (p<0.001). In addition, improvements in Mean Mouth Opening (MMO) levels were observed with TENS (7.80 mm), LLLT (9.09 mm), and ultrasound therapy (7.15 mm). These differences were found to be statistically significant (p<0.05). The laser and ultrasound groups fared better than the TENS group in the reduction of VAS scores (p<0.05), and there was no significant difference in MMO among the three therapies. Conclusion: Reductions in VAS scores and improvements in mouth opening were noticed in all three groups post-treatment. The laser and ultrasound therapies were more effective in reducing pain compared to TENS therapy. Comparing pretreatment and mid-treatment values, laser beam therapy proved to be more effective in reducing pain scores compared to TENS and ultrasound therapy. [ABSTRACT FROM AUTHOR]

The article presents the discussion on list is compiled from publications, products and information received as a result of exchange agreements, goodwill, research and subscriptions.

Accurate measurement of the stress in steel structures is crucial for structural health monitoring. To achieve this goal, a novel technique, the laser ultrasonic technique, was used in absolute stress measurement in this study. The feasibility of this technique has been verified through theoretical analysis and finite element (FE) analysis. A stress measurement experiment in steel specimens was conducted and the relationship between ultrasonic relative wave velocity and stress was explored. The results revealed that there is a similar linear correlation between the ultrasonic relative wave velocity and absolute stress. The stress can be obtained based on ultrasonic relative wave velocity. According to the stress measurement results, it was found that the absolute error between the measured stress and theoretical stress was largest when the stress level was low, and that the measured error of stress gradually decreased with increases in the applied stress. The relative error between the measured stress and the theoretical stress was within 10% when the stress was higher than 100 MPa. This further verifies the reliability of the laser ultrasonic technique under high-stress conditions. Additionally, the impact of temperature and surface roughness on stress measurement was analyzed. The stress error in stress measurement increased similarly linearly with the increase in temperature and increased non-linearly with the increase in roughness. The corresponding compensation methods were proposed to effectively improve the accuracy of measurement. [ABSTRACT FROM AUTHOR]

Acoustoelasticity, a characteristic of material anharmonicity, gives rise to a link between wave propagation velocity and the stress state in materials. Ultrasonic techniques to monitor this coupling, particularly with high sensitivity and in a noncontact manner, can have widespread application both in the quantification of applied and residual stress and in the characterization of nonlinear material behavior through measurement of higher order elastic constants. Here, we use a laser ultrasonic technique to excite and detect zero group velocity (ZGV) Lamb wave resonances in aluminum plates under uniaxial loading. A laser line source is used to excite these resonances at different orientations with respect to the applied load, and the signals are detected using an interferometer. The effects of stress and source orientation on ZGV resonance frequencies are validated using the theory of acoustoelastic Lamb wave propagation. In addition, a model-based inversion technique is used to extract Murnaghan's third-order elastic constants from measurements of the stress dependence of the first two ZGV modes generated parallel and perpendicular to the applied load. Laser generation and detection of ZGV resonances is shown to be an effective and powerful approach for the noncontact and nondestructive acoustoelastic characterization of elastic waveguides. [ABSTRACT FROM AUTHOR]

Lumbar disc herniation associated with radiculopathy (LDHR) is among the most frequent causes of spine-related disorders. This condition is triggered by irritation of the nerve root caused by a herniated disc. Many non-surgical and surgical approaches are available for managing this prevalent disorder. Non-surgical treatment approaches are considered the preferred initial management methods as they are proven to be efficient in reducing both pain and disability in the absence of any red flags. The methodology employed in this review involves an extensive exploration of recent clinical research, focusing on various non-surgical approaches for LDHR. By exploring the effectiveness and patient-related outcomes of various conservative approaches, including physical therapy modalities and alternative therapies, therapists gain valuable insights that can inform clinical decision-making, ultimately contributing to enhanced patient care and improved outcomes in the treatment of LDHR. The objective of this article is to introduce advanced and new treatment techniques, supplementing existing knowledge on various conservative treatments. It provides a comprehensive overview of the current therapeutic landscape, thereby suggesting pathways for future research to fill the gaps in knowledge. Specific to our detailed review, we identified the following interventions to yield moderate evidence (Level B) of effectiveness for the conservative treatment of LDHR: patient education and self-management, McKenzie method, mobilization and manipulation, exercise therapy, traction (short-term outcomes), neural mobilization, and epidural injections. Two interventions were identified to have weak evidence of effectiveness (Level C): traction for long-term outcomes and dry needling. Three interventions were identified to have conflicting or no evidence (Level D) of effectiveness: electro-diagnostic-based management, laser and ultrasound, and electrotherapy. [ABSTRACT FROM AUTHOR]

Stainless steel (SS) is widely used in many fields including aeronautics, automobiles, marine and mechanical industries due to its outstanding feature such as good corrosion resistance and hardness. However, changes in material properties under stress, particularly changes in Young's modulus, result in the formation of cracks, a reduction in load-bearing capacity, and fatigue damage. So, the structural integrity needs to be evaluated based on a precise measurement of mechanical properties. In this study, Stainless Steel 304 (SS-304) is used as the base material and various tensile stresses are applied ranging from 0 MPa to 100 MPa with increment of 10 MPa in each step. Nondestructive Laser Ultrasound Technique (LUT) has been used to characterize the elastic modulus under various tensile stresses. An inverse program was developed based on the Particle Swarm Optimization (PSO) algorithms to determine material properties. Nonlinear Gauss fitting method was proposed and established the fitting equation and nonlinear curve for Young's modulus and residual stress. The outcome of this research shows that when tensile stress is applied, the mechanical properties decrease by shifting the dispersion curve and also it is evident that the dispersion curves move toward the high-frequency-thickness while increasing the tensile stress. When the tensile stress was increased from 0 MPa to 100 MPa, the value of Young's modulus decreased from 201.7 GPa to 193.5 GPa. Especially, the predominant changes were observed during 30–100 MPa. This observation displays the bonding strength and binding energy between the atomics. Further, the proposed nonlinear Gauss fitting substantiated the experimental values and confirmed that the thickness accuracy is close to the inversion values, with an average difference of 4.32%. This research suggests a potential nondestructive method to determine the residual stress of a material by calculating the changes in the elastic modulus. [ABSTRACT FROM AUTHOR]

The application of laser ultrasonic technology to defect detection is being widely studied. The Synthetic Aperture Focusing Techniques (SAFTs) is one of the imaging algorithms for detecting and imaging internal defects. SAFT based on Delay and Sum (DAS-SAFT) is known for high-quality imaging results. However, it has the disadvantages of the large calculation amount, which severely restricts its application. This work proposes a Co-Overlay Software and Hardware method (SAFT-COSH) based on Zynq, which uses parallelism and pipeline technology on FPGA and can efficiently accelerate DAS-SAFT operations. It can be found that the result obtained by the SAFT-COSH method is similar to the original method. Moreover, the time consumption of the SAFT-COSH system is 1/28 of that of the I9-13900KF CPU used for DAS-SAFT calculation. Finally, it was found by analyzing the time consumption of the DAS-SAFT procedure that the time consumption of SAFT-COSH system is short enough to support realtime 3D defect imaging. Characteristics of high efficiency and low cost in the SAFT-COSH method make it applicable in fields that require fast imaging using SAFT-based methods. [ABSTRACT FROM AUTHOR]

Hectorite is trioctahedral clay mineral that possess unique characteristics of surface reactivity and adsorption, cation exchange capacity and easy delamination in water into individual nano layers. Thus, hectorite can be a promising nanocarrier with biocompatibility, high payload and controlled release of drug. Therefore, in the present study, hectorite has been used for the delivery of two hydrophobic molecules; chemotherapeutic drug DDP [Cis-diamminedichloroplatinum (II)] and natural photosensitizer hypocrellin A (HA) for combinatorial therapy. The experimental results has been fitted to l-type (Langmuir) adsorption isotherm. The adsorption isotherm showed higher affinity of DDP toward the hectorite with almost comparable CEC value of initial silicate layer of hectorite. The loading of drug into nanoclay was further characterize by using SEM, FTIR, XRD, DLS and TGA, which suggest the presence of DDP molecules in between the interparticle and photosensitizer on the surface of nanoclay. After, adsorption the characteristic properties such as photostability and photobleaching of HA has been significantly improved. The photobleaching efficiencies of free HA and Ht-DDP-HA was 72.8 and 55.2%, respectively, and the 1O2 generation quantum yield was 0.86. The in vitro release rate is twofold higher in the presence of laser light and ultrasonic waves. The drug release profile was found to be best fitted by Higuchi square root model, which implicate that release of drug from matrix as square root of time-dependent process and diffusion controlled. The in vitro efficacy of Ht-DDP-HA showed the potent anti-cancerous ability due to combinatorial effect by 2.01 and 1.69 fold times higher efficacy than free DDP and HA, respectively. Flow cytometry data shows the synergistic effect of combined therapy by showing maximum apoptotic and necrotic percentage. [ABSTRACT FROM AUTHOR]

Monitoring the internal temperature of active elements (AE) of high-power lasers is necessary for their safe operation. The article describes a method and device for monitoring the internal temperature of the AE of lasers. The measurements utilize pulsed ultrasonic (US) probing and the temperature dependence of the sound speed in the AE material. A change in the sound speed leads to a change in the phase of the ultrasonic signal passing through the object, which is recorded by the described device. The results of monitoring the AE temperature using ultrasonic probing during operation of an laser device are presented. [ABSTRACT FROM AUTHOR]